General Prelithiation Approaches and the Corresponding Full Cell Design

Abstract

Prelithiation technology is widely regarded as an effective strategy to enhance the energy density and extend the cycle life of lithium‐ion batteries (LIBs). The principle of prelithiation is to introduce additional active Li⁺, thereby compensating for Li losses during initial charging and long‐term cycling. However, the current summaries of various prelithiation approaches are predominantly focused on liquid LIBs, with limited reviews available on solid‐state LIBs. Compared to liquid LIBs, solid‐state LIBs not only face uniformity issues caused by the uneven mixing of active materials and Li sources during prelithiation, but also encounter severe kinetic challenges arising from rigid solid–solid interface contact. Here, various prelithiation techniques are first integrated and the dynamic correlation between the prelithiation of each component in a full cell and its electrochemical performance is systematically introduced. Furthermore, the challenges of prelithiation techniques in solid‐state LIBs in terms of solid–solid interface and Li⁺ transport are discussed. Finally, these prelithiation technologies are expected to be extended to the design of other premetallation agents, which guide the development of high‐energy and high‐safety energy storage systems.

Prelithiation boosts the electrochemical performance of lithium‐ion batteries by compensating for lithium loss. This review integrates the synergistic effects of prelithiation of each component in full cells. Additionally, the kinetic challenges of prelithiation in all‐solid‐state lithium‐ion batteries are summarized. Finally, the prelithiation strategy is extended to other premetallation designs, providing guidance for the establishment of high‐energy and high‐safety energy storage systems.

1. Introduction

With worsening environmental issues and increasing consumption of fossil resources, various electrochemical energy storage (EES) systems have emerged and are being rapidly developed to meet the needs of sustainable development.^{[ 1 ]} Rechargeable lithium‐ion batteries (LIBs) are recognized as the most promising EES systems because of their remarkable merits such as high‐energy density, no memory effect, and low selfdischarge.^{[ 2 ]} However, LIBs face severe challenges related to active Li loss during the initial cycling stage. The electrolyte undergoes irreversible decomposition at the electrode/electrolyte interface, forming a solid electrolyte interphase (SEI) layer primarily composed of inorganic lithium salts (e.g., lithium carbonate (Li₂CO₃), LiF) and organic lithium compounds (e.g., ROCO₂Li).^{[ 3 ]} Additionally, some Li⁺ become permanently trapped in defects in the electrode materials, and continuous side reactions at the electrode interface lead to the accumulation of electrochemically inactive “dead Li”.^{[ 4 ]} These multiple active Li losses result in an initial Coulombic efficiency (ICE) for graphite anodes typically below 90%, while for high‐capacity silicon (Si)‐based anodes, it can drop below 70% (Figure 1a).^{[ 5 ]} This irreversible Li loss not only reduces the actual energy density by 15–30% compared to the theoretical value but also leads to the continuous depletion of Li reserves during long‐term cycling.^{[ 6 ]} Ultimately, this exacerbates the instability of the electrode/electrolyte interface and accelerates capacity fading, which limits the practical application boundaries of high‐energy LIBs.

Figure 1.

Schematic of the effect of prelithiation in LIBs.

Prelithiation technology is a promising approach to compensate for irreversible capacity loss and to improve the energy density and cycle life of LIBs (Figure 1b). A number of prelithiation strategies have been developed (Figure 2 ), and early research focused mainly on the construction of technical systems for the anode and cathode prelithiation of LIBs. Anode prelithiation compensates for Li through electrochemical contact (e.g., Li foil, Li alloy additives) or chemical reduction reactions. Cathode prelithiation relies on Li‐rich additives or overlithiated cathode materials to release supplementary Li sources. Subsequently, the prelithiation of inactive components of LIBs is systematically investigated, including electrolyte optimization,^{[ 7 ]} separator and collector modification.^{[ 8 ]} Finally, innovative strategies extend the scope of prelithiation studies to various industrial feasibility. Despite the unique advantages of each prelithiation approach, their realization of large‐scale commercial application has been hampered by some limitations. For example, prelithiation anode reagents are technically difficult to integrate with the current electrode preparation process due to their high chemical reactivity.^{[ 5} , ^{9 ]} Moreover, since the cathode prelithiation reagents and overlithiated cathodes cannot provide high enough prelithiation capacity, they are difficult to pair with next‐generation high specific capacity anode materials such as Si, germanium (Ge), tin (Sn).^{[ 10 ]} It is worth noting that the existing prelithiation technologies are mainly applicable to liquid LIBs. Rapidly evolving all‐solid‐state lithium‐ion batteries (ASSLIBs) face more serious problems of low ICE and irreversible capacity loss, which are more prominent than those of liquid LIB systems due to the poor mechanical compatibility at the solid–solid interface, resulting in impeded Li⁺ transport. This special interfacial property imposes higher requirements on prelithiation technology for ASSLIBs.

Figure 2.

Main progress of research on prelithiation in LIBs.

Currently, the electrochemical performance of common full cells is still hindered by poor cycling stability and low energy density, which can no longer meet the urgent market demands.^{[ 11 ]} The new full cell systems, designed according to the degree of anode prelithiation, offer significant structural and performance advantages. For the partially prelithiated system, partial Li compensation of the anode (e.g., graphite/hard‐carbon‐based anode) by chemical prelithiation agents or functional additives can compensate for the loss of initial active Li due to SEI formation.^{[ 12 ]} It improves ICE and mitigates the continuous consumption of active Li caused by SEI reconstruction and volume deformation during cycling, significantly improving cycling stability. The combination of a fully lithiated anode (e.g., Li─C or Li─Si alloy anode) with a Li‐free cathode (e.g., FeS₂ or S cathode) extends the selectivity of high‐capacity cathode materials and enables the design of high‐energy battery systems.^{[ 13 ]} However, challenges such as Li dendrite growth and anode volume expansion still need to be overcome.^{[ 14 ]} For ASSLIBs, solid‐state electrolytes with high mechanical properties may partially inhibit the penetration of Li dendrites to some extent.^{[ 15 ]} However, the parasitic reaction at the interface between the electrode and the solid‐state electrolyte, changes in the volume of the Li anode, and the limitations of the dry‐film process of electrode have led to a much lower ICE than that of liquid LIBs.^{[ 16 ]} Recently, the researchers proposed a targeted prelithiation scheme, where the anode uses a Li─Si alloy to compensate for Li loss, and the cathode optimizes the conductive structure through a Li‐containing coating, both of which synergistically repair the internal ion/electron transport network of the electrode, thus enhancing the actual performance of ASSLIBs.^{[ 17 ]}

In this review, we first integrate previously published prelithiation strategies based on active Li addition compensation techniques for the anode, cathode, and inactive components, and analyze the advantages and challenges of various prelithiation techniques for different components of LIBs. Additionally, the dynamic correlation between the synergistic Li supplementation of each component and its performance is systematically revealed with respect to the limitations of the current single prelithiation mechanism for full cell. Second, to address the kinetic limitations of prelithiation in ASSLIBs, we summarize the prelithiation approaches based on ASSLIBs, which provide effective strategies for constructing of ASSLIBs with high‐energy density. Given the lack of universal metal compensation strategies for emerging energy storage systems such as sodium‐, potassium‐, and magnesium‐ion batteries, this review systematically examines the design principles and modification approaches of prelithiation agents, which will provide theoretical references for developing premetallation agents for other secondary‐ion batteries. Thus, it provides practical application of next‐generation EES systems with high‐energy‐density and high safety.

2. Anode Prelithiation

Anode prelithiation technology, which compensates for active Li loss at the anode, has become a key strategy for ensuring stable anodes with high capacity, high average CE, and long cycle life.^{[ 18 ]} This part focuses on three main approaches to anode prelithiation: the direct prelithiation method based on physical contact, functional materials as prelithiation additives, and the chemical prelithiation method based on molecular reactions. It systematically examines their underlying mechanisms and technological evolution. The direct contact method utilizes spontaneous thermodynamic reactions at the physical interface between an external Li source and the electrode to promote Li diffusion, forming a prelithiation layer. Prelithiation additives such as Li metal powders and Li‐rich alloys can be incorporated into the electrode to serve as a Li‐supplementing source. The chemical method achieves deep and uniform lithiation of the electrode active material through molecular‐scale penetration and redox reactions of the Li solution.

2.1. Direct Contact Prelithiation

Direct contact prelithiation technology achieves directional Li supplementation by establishing physical contact between the anode and Li source.^{[ 19 ]} The key to its performance enhancement depends on the control of interfacial reactions.^{[ 20 ]} Depending on the interfacial electron/ion transport paths, the technology can be subdivided into three categories: internal short‐circuit, external short‐circuit, and composite layer prelithiation (Figure 3 ). Internal short‐circuit prelithiation uses the inherent potential difference of the materials to drive lithiation, external short‐circuit introduces an external circuit to precisely control the reaction process, and composite layer design optimizes interfacial transport and the uniformity of Li intercalation through an intermediate medium.

Figure 3.

Anode prelithiation: direct contact. Internal short‐circuit prelithiation. a) Schematic illustration of internal contact prelithiation. The working anode and Li foil are wetted with electrolytes and then compressed by external mechanical force to achieve prelithiation.^{[ 21 ]} b) Gradient nanocrystalline Li─Al alloy layer formed on an Al anode after short‐duration (60 min) low‐pressure (62 kPa) contact prelithiation.^{[ 22 ]} c) SEI composition of SiO_1.3 and micrometer‐sized Si after contact prelithiation and its effect on subsequent cycling.^{[ 23 ]} External short‐circuit prelithiation. d) Optimized real‐time voltage monitoring system for precise control of prelithiation depth.^{[ 24 ]} e) Schematic of a multianode battery system connected via an external circuit to Li metal for scalable prelithiation.^{[ 25 ]} f) Illustration of controlling the prelithiation rate by adjusting the external current intensity.^{[ 26 ]} Composite interlayer prelithiation. g) Electron‐conductive interlayers introduced between the anode and Li foil for uniform prelithiation of SiO_x electrodes.^{[ 20 ]} h) Intermediate buffer layer inserted between the Si/graphite composite anode and Li foil to optimize Li⁺/e⁻ transport pathways.^{[ 27 ]} i) Artificial electron channels based on Li─Ag alloy architectures designed at the graphite anode/Li interface for homogeneous prelithiation.^{[ 28 ]} (a) Reproduced with permission.^{[ 21 ]} Copyright 2011, American Chemical Society. (b) Reproduced with permission.^{[ 22 ]} Copyright 2020, Elsevier. (c) Reproduced with permission.^{[ 23 ]} Copyright 2023, Wiley‐VCH. (d) Reproduced with permission.^{[ 24 ]} Copyright 2016, American Chemical Society. (e) Reproduced with permission.^{[ 25 ]} Copyright 2019, Elsevier. (f) Reproduced with permission.^{[ 26 ]} Copyright 2024, Elsevier. (g) Reproduced with permission.^{[ 20 ]} Copyright 2019, American Chemical Society. (h) Reproduced with permission.^{[ 27 ]} Copyright 2022, Elsevier. (i) Reproduced with permission.^{[ 28 ]} Copyright 2022, Wiley‐VCH.

The core of internal short‐circuit prelithiation lies in the design of the spontaneous reaction mechanism. Taking Si nanowires as an example, lithiation is thermodynamically self‐driven through shorting between the nanowires and Li foil, replenishing 50% of the capacity (2000 mAh g⁻¹) in just 20 min (Figure 3a).^{[ 21 ]} However, uneven current density caused by a rough interface limits the application of this technology in high‐area‐capacity electrodes, prompting researchers to turn to interfacial control in prelithiation. A gradient Li─Al alloy layer generated by Al foil under 60 kPa pressure achieves uniform Li diffusion, allowing the battery to cycle 600 times without capacity degradation (Figure 3b).^{[ 22 ]} Notably, the impact of material composition on interface properties is even more profound—the oxygen element in SiO_x accelerates the formation of the Li─Si phase with high ionic conductivity, and the in situ constructed mosaic‐like SEI exhibits both high mechanical modulus (120 GPa) (Figure 3c). Compared to prelithiated Si anodes, the full cell with prelithiated SiO_x improves the capacity retention after 200 cycles by 23%.^{[ 23 ]} This development suggests that internal short‐circuit prelithiation overcomes homogenization bottlenecks through the design of interfacial compositions and control of reaction kinetics.

External short‐circuit prelithiation adjusts the reaction process precisely via an external circuit, addressing the limitations of internal short‐circuit prelithiation, which cannot control the depth and speed of lithiation. By adding resistance to the external circuit, the Li supplementation time for SiO_x anodes can be precisely controlled to 30 min, with the first cycle efficiency improving from 73.6% to 94.9%, corresponding to a full cell energy density of 508.5 Wh kg⁻¹ (Figure 3d). This method prevents Li dendrite formation by optimizing the short‐circuit current density, while maintaining compatibility with commercial production lines.^{[ 24 ]} For stacked battery prelithiation, Watanabe et al. proposed a perforated electrode technique, using lasers to create 20 µm microholes in the graphite anode (Figure 3e). This enables the simultaneous completion of prelithiation for three layers of anodes while shortening the vertical Li⁺ transport path by 75%. The optimized battery nearly eliminates irreversible capacity loss during the first cycle.^{[ 25 ]} Niu et al. further combined electrode microstructure design with external short‐circuit prelithiation, proposing a combination of perforated electrodes and controlled current (Figure 3f). Using an electrochemical‐concentration field coupled approach to simulate the Li dissolution, diffusion, and reaction process, they determined that when the perforated electrode channel diameter is set to 500 µm and the electrode spacing is 8.7 mm, the prelithiation efficiency and uniformity are significantly improved.^{[ 26 ]} Consequently, in the SiO/graphite composite anode, uniform Li capacity of 30 mAh is achieved in 10 h (with a global Li concentration distribution standard deviation ζ <0.1), reducing the prelithiation time by 75% compared to traditional methods (which require 40–50 h).

Composite layer prelithiation technology reconstructs the interface transport network through functionalized intermediate layers. For example, a carbon nanotube (CNT)–polymer buffer layer builds a uniform electron/ion mixed conductive path, improving the SiO_x homogenous lithiation efficiency by 3 times (Figure 3g).^{[ 20 ]} For industrialization needs, researchers designed a porous carbon‐based intermediate buffer layer (IBL) (Figure 3h). Its Li─IBL micro‐nanocomposite structure effectively inhibits Li failure under 85% relative humidity (RH) and regulates the lithiation depth of Si/graphite anodes under 3 MPa calendering pressure. The final 1.6 Ah pouch cell achieves an energy density of 362 Wh kg⁻¹.^{[ 27 ]} The Li─Ag alloy artificial electronic channel is innovative in breaking through the Li source utilization bottleneck.^{[ 28 ]} It monodisperses an island‐like structure that guides 90.7% of the active Li into the graphite lattice, while suppressing the formation of dead Li caused by dry‐state corrosion, resulting in a 35.8% increase in the full cell energy density with LiNi_0.5Co_0.2Mn_0.3O₂ cathode (Figure 3i). Table 1 systematically summarizes the implementation methods of direct contact prelithiation, along with the ICE and cycling performance of prelithiated electrodes.

Table 1.

The summary of direct contact prelithiation.

Li source	Prelithiation conditions	Prelithiation capacity	Prelithiated electrodes	ICE	Cycle life (number)	Capacity retention	Refs.
Li foil	20 min/pressure	≈2000 mAh g−1	Si nanowire	≈211%	10	75%	[21]
Li─Al foil	60 min/62 kPa	144 mAh g−1	Graphite (full cell)	101%	200	90%	[22]
Li foil	4 min/5.5 kPa	≈2700 mAh g−1	Si	96%	200	44%	[23]
Li foil	12.5 min/5.5 kPa	≈1200 mAh g−1	SiO1.3	101%	200	77%	[23]
Li foil	External short circuit 30 min	1370 mAh g−1	c‐SiOx	95%	100	74%	[24]
Li foil	External short circuit 20 min/20 µm	–	Graphite	99%	10	90%	[25]
Li─Cu foil	External short circuit 30 mAh g−1/500 µm	30 mAh	SiO /Graphite	–	–	–	[26]
Li foil/CNT/PVB	20 min/2 kg	173 mAh g−1	SiOx (full cell)	87%	200	74%	[20]
Li foil/carbon/polyvinylidene difluoride (PVDF)	2 h/3 MPa	–	Si/Graphite (full cell)	89%	1000	94%	[27]
Li─Ag alloy	Direct‐current magnetron sputtering	≈2 mAh cm−2	Graphite (full cell)	91%	600	72%	[28]

The evolution of direct contact prelithiation technology has become increasingly clear. Initially, internal short‐circuit technology was the first to verify the feasibility of physical contact lithiation. Then, external short‐circuit technology addressed uncontrollable defects by regulating the external circuit, and composite layer technology further tackled challenges related to interface transport and process compatibility. Current research has largely focused on vertical advancements in individual technologies; however, future efforts should prioritize horizontal integration. For example, combining composites with perforated electrode structures could enhance homogeneity, or machine learning could be used to optimize external circuit control parameters. The synergistic optimization of these three technologies is advancing direct contact prelithiation from laboratory exploration to engineering applications.

2.2. Prelithiation Additives

In recent years, additive prelithiation technology has become an important strategy for extending the cycle life of LIBs, due to its powerful Li compensation capability.^{[ 29 ]} Based on the characteristics of material systems, current research focuses on two main categories of prelithiation additives: Li metal‐based and Li alloy‐based materials (Figure 4 ). The former utilizes the high reactivity of Li metal to achieve rapid Li compensation through structural designs such as powders, films, or grids; the latter combines Li alloy compounds with the design of passivation layers, improving environmental compatibility while avoiding the oxidation failure risks associated with pure Li. These two types of materials promote the development of prelithiation technology in terms of active Li content, environmental compatibility, and process adaptability, providing multidimensional design strategies to address issues such as low ICE and rapid capacity degradation.

Figure 4.

Anode prelithiation: additives. Li metal. a) Stabilized Li metal powder (SLMP). SLMP initiates prelithiation of the Si anode by breaking its inert shell under pressure.^{[ 30 ]} b) Li strips. Schematic of roll‐to‐roll prelithiation with ultrathin Li strips on a graphite anode.^{[ 31 ]} c) Li mesh. Direct integration of Li metal meshes into the anode.^{[ 32 ]} d) Li wire. Ultrathin Li wire produced by loading Li metal onto silver‐plated aramid yarn for compensating Li loss in fiber‐based graphite anodes.^{[ 33 ]} e) Vacuum thermal deposition of Li. Vacuum thermally deposited Li outperforms conventional Li foil by enhancing interfacial electron/ion pathways.^{[ 34 ]} f) Schematic of a micrometer‐sized Si electrode after vacuum thermal deposition of Li.^{[ 35 ]} Li alloys. g) Li_xSi─Li₂O core–shell nanoparticles.^{[ 12 ]} h) Li_xSi/Li₂O composites.^{[ 9 ]} i) Artificial‐SEI‐protected Li_xSi nanoparticles.^{[ 36 ]} j) LiF‐coated Li_xSi nanoparticles.^{[ 37 ]} k) Li₂₂Z₅ alloys and Li₂₂Z₅─Li₂O composites (Z = Si, Ge, and Sn) synthesized by prelithiation of group IV elements and their corresponding oxides using a one‐pot metallurgical process.^{[ 38 ]} l) Air‐ and water‐stable Li‐rich Si/graphite anodes leverage surface O─Li─Si ternary bonding structures to achieve ambient processing compatibility.^{[ 39 ]} (a) Reproduced with permission.^{[ 30 ]} Copyright 2013, American Chemical Society. (b) Reproduced with permission.^{[ 31 ]} Copyright 2024, Elsevier. (c) Reproduced with permission.^{[ 32 ]} Copyright 2023, American Chemical Society. (d) Reproduced with permission.^{[ 33 ]} Copyright 2024, Oxford University Press. (e) Reproduced with permission.^{[ 34 ]} Copyright 2022, Wiley‐VCH. (f) Reproduced with permission.^{[ 35 ]} Copyright 2022, Wiley‐VCH. (g) Reproduced with permission.^{[ 12 ]} Copyright 2014, Springer Nature. (h) Reproduced with permission.^{[ 9 ]} Copyright 2016, National Academy of Sciences of America. (i) Reproduced with permission.^{[ 36 ]} Copyright 2015, American Chemical Society. (j) Reproduced with permission.^{[ 37 ]} Copyright 2017, American Chemical Society. (k) Reproduced with permission.^{[ 38 ]} Copyright 2018, Elsevier. (l) Reproduced with permission.^{[ 39 ]} Copyright 2024, Wiley‐VCH.

The diverse design of Li‐metal‐based additives effectively addresses the low efficiency and complex processes associated with direct contact prelithiation technologies. Stabilized Li metal powder (SLMP) achieves stabilization by constructing a uniform Li₂CO₃ passivation layer on the surface of Li metal particles. This key passivation measure effectively isolates the Li metal from direct contact with air and moisture, significantly suppressing side reactions. Among these, the Li₂CO₃ coating technology, based on molten Li atomization–carbonation reactions (Li(l) + CO₂(g) → Li₂CO₃(s)), has been successfully commercialized. This process enables the in situ formation of a dense Li₂CO₃ layer, ≈350 nm thick (≈3 wt%), on the surface of Li particles.^{[ 29 ]} This engineered interface imparts moderate stability to the SLMP, enabling stable storage in dry air with a dew point below −40 °C for over 6 months. In practical applications, exemplified by commercial products such as Livent's SLMP, the powder is typically dispersed in inert solvents like toluene or cyclohexane and deposited onto electrode surfaces via spray coating.^{[ 40 ]} Subsequent calendering at pressures exceeding 6 MPa disrupts the passivation layer, activating Li release (Figure 4a). This process elevates the ICE of Si‐based electrodes to nearly 100%.^{[ 30 ]} To match large‐scale manufacturing scenarios, ultrathin Li strips (6 µm) are integrated through a roll‐to‐roll process with a self‐compensating mechanism, compensating for Li loss while reducing additional processing steps, leading to a 17.8% increase in the energy density of pouch cells (Figure 4b).^{[ 31 ]} Further structural innovations include the precise control of porosity in porous Li grids, which enables the localized distribution of in situ prelithiation of the Si anode (Figure 4c). The synergistic core–shell Si particle design reduces the total capacity decay rate by 30%.^{[ 32 ]} For flexible devices, Li wire supported by silver‐coated aramid fibers serves as a Li compensation additive to compensate for the first‐cycle Li loss in graphite anodes, enhancing the ICE from 88% to ≈100%, achieving an energy density of 139.8 Wh kg⁻¹ in fiber batteries (Figure 4d).^{[ 33 ]} These methods, through the synergistic optimization of physical structures and processing techniques, provide multilevel preparation solutions for Li metal additives, from micro‐nanoscales to macroscopic devices.

Vacuum thermal evaporation of Li technology has addressed the issue of low utilization inherent in traditional Li foils by modulating the electronic channel density (Figure 4e,f). Studies indicate that this method produces a uniform nano‐Li film on the surface of the graphite anode, with an electronic channel density more than 3 times that of the mechanical rolling process (Figure 4e). Consequently, the proportion of dead Li decreases from 26% to 8%, while capacity retention exceeds 95% after 600 cycles. The core of this technology lies in the robust bonding interactions between Li atoms and substrate atoms during the vapor deposition process, which leads to the formation of a continuous electron/ion conductive network.^{[ 34 ]} Further investigations reveal that evaporated Li can infiltrate pore structures and establish 3D conductive frameworks even on complex microstructure Si electrodes (Figure 4f). This enhancement improves the ICE to over 90% and extends the cycle life by 50%.^{[ 35 ]} This high‐precision interface engineering strategy provides a critical foundation for the industrial‐scale prelithiation of high‐capacity anodes like Si‐based materials.

As the pivotal Li‐alloy‐based additive materials, Li─Si alloy strikes a balance between high capacity and stability through diversified interface passivation strategies (Figure 4g,j). Groundbreaking studies introduced Li_xSi─Li₂O core–shell particles,^{[ 12 ]} where the Li₂O shell effectively isolates the reactive core in dry air environments, resulting in a capacity retention rate of up to 85% after 3 days. To overcome the performance limitations of the core–shell structure in humid environments, a microdomain dispersion strategy embeds Li_xSi nanodomains into a highly crystalline Li₂O matrix using an alloying method.^{[ 9 ]} This innovation not only elevates capacity retention to 85.9% under 40% RH, but also mitigates the volume expansion of Si through strongly anchored O─Li chemical bonding. At the interfacial engineering level, artificial SEI‐coated Li_xSi,^{[ 36 ]} in combination with the hydrophobic properties of a fluorocarbon composite coating, ensures that the material maintains a capacity of 1600 mAh g⁻¹ for 6 h at 10% RH, with ICE reaching 96.8%. Furthermore, surface fluorination technology further improves interface stability by forming a dense LiF crystalline layer (≈20 nm thickness), quintupling cycle life relative to untreated samples and achieving a high capacity of 2504 mAh g⁻¹ in standard N‐methyl‐2‐pyrrolidone (NMP) solvent‐based electrode processing environments.^{[ 37 ]} This multilevel passivation strategy addresses the industrial limitations of Li─Si alloys from three perspectives – the core, matrix, and interface‐delivering systematic solutions for concurrent high ICE and extended cycling performance.

The scope of materials for prelithiation additives has expanded beyond Si to include various alloy elements and composite structures (Figure 4k,l). Investigations into Group IV elements (Ge, Sn) show that Li₂₂Z₅ (Z = Ge, Sn) alloys use Li₂O matrices to protect active components from moisture, maintaining 93% capacity retention after 6 h of storage at 45% RH.^{[ 38 ]} Among these, the Ge‐based system demonstrates the best stability due to its higher Li─Ge bond energy (ΔG = −2.98 eV), with a prelithiation capacity of 1335 mAh g⁻¹. Lithiated graphite achieves a breakthrough in ambient prelithiation by embedding organic Li sources (e.g., ─COOLi) within nanopores, forming O─Li─Si tricoordination structures. This approach enables direct, air‐processable manufacturing, elevating ICE to 116%, while constraining volume expansion below 6%.^{[ 39 ]} These non‐Si systems not only validate universal design principles for alloy‐based prelithiation additives but also establish versatile frameworks for various anode materials through tailored chemical bond reorganization and porous architecture engineering. Table 2 systematically summarizes the types of prelithiation additives, along with the ICE and cycling performance of the prelithiated electrodes.

Table 2.

The summary of prelithiation additives.

Prelithiation additives	Prelithiated electrodes	Capacity [mAh g−1]	ICE	Cycle life (number)	Capacity retention	Refs.
SLMP	Graphite	–	91% (full cell)	50	99%	[41]
SLMP	GeOx	–	85% (full cell)	200	94%	[42]
SLMP	SiO	–	90% (full cell)	100	80%	[29]
SLMP	SiO	–	88% (full cell)	140	79%	[40]
SLMP	SiO	1001.8	82%	15	75%	[43]
SLMP	Si	≈2500	95%	150	–	[44]
Li strips	Graphite	–	116%	1200	88%	[31]
Li foil	SiOx	–	115%	200	≈83%	[45]
Li metal (thermal evaporation)	SiOx	1250	68%	5000	54%	[46]
Li metal (thermal evaporation)	Si	3750	–	200	–	[47]
Li metal (thermal evaporation)	Si	2774	85% (full cell)	150	77%	[35]
Li─C	Graphite	2534	101%	100	78%	[48]
LixSi/Li2O	Si	1400	94%	50	–	[12]
LixSi/Li2O	SiO	2059	94%	400	73%	[9]
LixSi/Li2O	SiO	1859	416%	50	71%	[49]
LixSi/Artificial SEI	Si	2100	97%	50	–	[36]
LixSi/LiF	Graphite	2504	102%	650	87%	[37]
LixSi/graphene	Si	–	–	400	98%	[13]
LixSi/Li2O/TiyOz	Si	2326	238%	500	77%	[50]
Li─Si─Fe─Mn	Si	997.89	90%	250	79%	[51]
LixSn/PPy	Sn	550	–	300	86%	[52]
Li22Ge5	Graphite	1335	101%	100	–	[38]
Li22Sn5	Sn	910	94%	100	–	[38]
LiH	SiO	1203	91%	300	39%	[53]

The rapid development of additive prelithiation technology has played a key role in advancing high‐energy battery system designs. However, it still faces challenges related to large‐scale production, stability under conventional environments, and compatibility with slurry solvents. Future research should focus on addressing issues of material homogeneity in large‐scale production and developing adaptive protective layers to improve compatibility with industrial manufacturing processes.

2.3. Chemical Prelithiation

Prelithiation additives are limited by mixing homogeneity and insufficient solid–solid interface contact, both of which can result in uneven Li distribution.^{[ 54 ]} By contrast, chemical prelithiation technology enhances the uniformity of prelithiation by utilizing the inherent molecular‐scale dispersion properties of liquid‐phase active Li species.^{[ 55 ]} This technology uses Li─arene complexes (LACs) or organic lithium salt solutions as the core carriers, leveraging the solvent's permeability and molecular‐level reactivity to regulate Li distribution within the electrode. The core innovations focus on three areas (Figure 5 ): uniform prelithiation (Li─arene solution), coregulation of ligands/solvents (adaptability to redox potential), and optimization of solution stability (degradation inhibition and scalability for storage).

Figure 5.

Anode prelithiation: chemical reagents. Li─arene complexes. a) Molecular‐scale prelithiation of SiO anodes using Li─biphenyl/tetrahydrofuran (THF) reagents achieves more uniform lithiation than SLMP additives.^{[ 55 ]} b) Schematic of Li─naphthalene/THF reagents integrated with roll‐to‐roll electrode manufacturing processes.^{[ 56 ]} Ligand and solvent optimization. c) Electron‐donating groups on arene ligands modulate redox potentials of prelithiation reagents below those of SiO anodes.^{[ 57 ]} d) The geometric configurations and highest occupied molecular orbital (HOMO) energy levels calculated by density functional theory (DFT) reveal distinct solvent effects of Li─biphenyl in DME, THF, and 2‐Me─THF.^{[ 54 ]} e) Weakly solvating solvents (e.g., 2‐Me─THF and tetrahydropyran (THP)) prevent solvent intercalation into graphite layers while maintaining the reagent reactivity.^{[ 58 ]} Stability of prelithiation solutions. f) 1 m Li─biphenyl/THF exhibits gradual decomposition upon ambient air exposure.^{[ 59 ]} g) A hierarchical reaction mechanism governs Li─biphenyl/2‐Me─THF reagent: the active monomer Li₁Bp[2MT]₁ dimerizes into an inactive Li₂Bp[2MT]₂ species, which is irreversibly reduced by locally accumulated highly reductive Li to LiH, H₂, and CH₄.^{[ 60 ]} (a) Reproduced with permission.^{[ 55 ]} Copyright 2020, American Chemical Society. (b) Reproduced with permission.^{[ 56 ]} Copyright 2022, Wiley‐VCH. (c) Reproduced with permission.^{[ 57 ]} Copyright 2020, Wiley‐VCH. (d) Reproduced with permission.^{[ 54 ]} Copyright 2021, Wiley‐VCH. (e) Reproduced with permission.^{[ 58 ]} Copyright 2021, American Chemical Society. (f) Reproduced with permission.^{[ 59 ]} Copyright 2019, American Chemical Society. (g) Reproduced with permission.^{[ 60 ]} Copyright 2024, Wiley‐VCH.

The LAC solution has effectively addressed the challenge of balancing prelithiation uniformity and reaction kinetics through molecular‐level reactions.^{[ 55 ]} The Li─biphenyl solution achieves homogeneous prelithiation of SiO_x particles within 5 min, increasing the ICE from 76% to 90%, significantly outperforming contact prelithiation methods (<80%) (Figure 5a).^{[ 55 ]} Further studies demonstrated that coupling the Li─naphthalene solution with a roll‐to‐roll electrode manufacturing process enables synchronous electrode formation and prelithiation on an industrial‐scale production line, resulting in an increased treatment capacity of 2.4 mAh cm⁻² (Figure 5b). This highlights the feasibility of chemical prelithiation for large‐scale manufacturing.^{[ 56 ]} However, its high reduction potential (>0.3 V vs Li/Li⁺) remains a limiting factor for compatibility with low‐potential Si anodes.

Ligand functionalization modification and weak solvent coordination strategies have been engineered to reduce the redox potentials of chemical prelithiation agents, achieving targeted compatibility with diverse anode materials (Figure 5c–e). Introducing strong electron‐donating substituents (such as 4,4′‐dimethyl) on biphenyl can regulate the LUMO energy level of the LAC, reducing the reduction potential from 0.33 to 0.13 V (vs Li/Li⁺) (Figure 5c).^{[ 57 ]} This modification promotes active Li alloying with Si rather than merely forming a SEI layer, ultimately achieving an exceptional ICE of 142%. Solvent engineering employing a strong electron‐donating, bulky solvent like 2‐Me─tetrahydrofuran (THF) reduces the redox potential of Li─biphenyl to 0.08 V.^{[ 54 ]} Strong‐coordinating solvents promote BP⁻ depletion during Li⁺ desolvation, generating free Li⁺─DME₂ species that cause graphite exfoliation through cointercalation. Conversely, weak solvents maintain Li⁺─BP⁻ coordination during desolvation, preventing solvent cointercalation. The coordination ability of commonly used solvents is ranked as THP < 2‐Me─THF < THF < DME (Figure 5d). Fourier transform infrared spectroscopy (FTIR), ⁷Li nuclear magnetic resonance (NMR) spectroscopy, and density functional theory (DFT) calculations demonstrate that the strong coordination of Li⁺─BP⁻ in weak solvents prevents the cointercalation of free solvents and facilitates the formation of binary graphite intercalation compounds (GICs), rather than ternary GICs (Figure 5e).^{[ 58 ]} This molecular engineering regulation mechanism is progressively refining the theoretical principles for the customized design of prelithiation reagents. Table 3 systematically summarizes various ligand–solvent combinations of chemical prelithiation reagents, along with the corresponding prelithiated electrode types and electrochemical performance.

Table 3.

The summary of LAC solutions for prelithiation.

Li─arene	Solvent	Prelithiated electrodes	ICE	Cycle life (number)	Capacity retention	Refs.
Li─Biphenyl	THF	SnO2/C	83% (full cell)	200	80%	[61]
Li─Biphenyl	THF	SiOx/C	90%	400	–	[55]
Li─Biphenyl	THF	SiOx/C	91%	100	54%	[62]
Li─Biphenyl	THF	P/C	93%	240	–	[63]
Li─Biphenyl	THF	P/C	91%	2000	–	[59]
Li─Biphenyl	THF	Hard carbon	106%	200	93%	[64]
Li─Biphenyl	2‐Me─THF	Graphite/SiOx	≈100%	300	74%	[58]
Li─Biphenyl	2‐Me─THF	Graphite	≈100%	200	103%	[54]
Li─Biphenyl	DME	S/PAN	63% (full cell)	50	–	[65]
Li─4,4′‐di‐tert‐butylbiphenyl	NMP	Graphene oxide	93%	200	88%	[66]
Li─9,9‐dimethylfluorene	DME	Al	100% (full cell)	100	–	[67]
Li─9,9‐dimethylfluorene	THF	SiO	91%	100	80%	[68]
Li─4,4′‐dimethylbiphenyl	THF	Hard carbon	94%	350	100%	[69]
Li─4,4′‐dimethylbiphenyl	DME	SiO	≈100%	–	–	[57]
Li─Naphthalene	THF	S	≈191%	100	80%	[70]
Li─Naphthalene	DME	S/PAN	94% (full cell)	250	91%	[71]
Li─Naphthalene	DME	Hard carbon	100%	500	94%	[72]
Li─Naphthalene	DME	Li4Ti5O12	99%	–	–	[73]
Li─Naphthalene	THF	LiCoO2 (LCO)	–	100	–	[74]
Li─Cyanonaphthalene	THF	SiO	100%	1000	74%	[75]
Li─1‐methylnaphthalene	DME	Hard carbon	98%	500	90%	[76]
Li─Biphenyl	2‐Me─THF	Graphite/SiOx	98%	200	–	[77]
Li─Biphenyl	2‐Me─THF	Graphite	110%	200	77%	[78]
Li─Biphenyl	THF	SiO/C	89%	200	96%	[79]
Li─4,4′‐dimethylbiphenyl	DME	SiO	100%	350	91%	[80]

The long‐term stability and environmental tolerance of solvent components are critical challenges in the industrialization of chemical prelithiation. To address the issue of rapid deactivation of prelithiation reagents in air, studies show that high‐concentration (1 M) Li─biphenyl/THF solutions can spontaneously form a surface protective film of biphenyl derivatives that prevents oxygen corrosion.^{[ 59 ]} This allows the solution to remain stable for 14 days in air, retaining over 85% of its activity. By contrast, low‐concentration (10 mm) solutions fail completely within 48 h due to defects in the protective film. Degradation kinetics analysis of Li─biphenyl/2‐Me─THF systems confirms deactivation stems from the dimerization of active Li₁Bp[2MT]₁ complexes (half‐life: 16 h at 25 °C) and irreversible reactions with trace moisture.^{[ 60 ]} By incorporating sterically hindered ligands (e.g., 4‐methylbiphenyl) combined with low‐temperature storage (5 °C) and anisole‐based encapsulation layer, the dimerization half‐life of Li⁺─arene active monomers can be extended beyond 1080 h. This “surface shielding–molecular passivation” hierarchical stabilization mechanism provides a guidance for the long‐term storage and open production line application of chemical prelithiation reagents.

However, the transition of chemical prelithiation technology from laboratory‐scale studies to industrial‐scale applications still faces a range of systemic challenges that require resolution. The fundamental issue resides in the inherent limitations of LAC solutions, particularly in terms of air stability, toxicity, and manufacturing compatibility.^{[ 5 ]} The primary challenge is their extreme sensitivity to air and potential toxicity. These complexes (e.g., Li─Biphenyl, Li─Naphthalene) are highly reactive to oxygen and moisture, and exposure to air can easily trigger violent decomposition or self‐ignition.^{[ 59} , ^{60 ]} This necessitates maintaining the operating environment under ultrahigh‐purity inert conditions, with humidity typically <1 ppm and a dew point of <−76 °C, substantially increasing equipment costs (e.g., large‐scale glove boxes or drying room systems) and process complexity.^{[ 18 ]} Additionally, their reaction byproducts (such as biphenyl radical anion Bp⁻ and naphthalene anion Naph⁻) exhibit potential biological toxicity (LD50: 3280 and 2590 mg kg⁻¹).^{[ 81 ]} Commonly used solvents such as THF and DME are volatile, posing health and environmental hazards, thus necessitating more stringent safety protocols and waste disposal measures.

Furthermore, the manufacturing compatibility challenge centers on the integration of chemical prelithiation with roll‐to‐roll production processes. Although LAC solutions can be incorporated into continuous production lines by immersion or spraying, the numerous steps involved—such as solution immersion, subsequent washing, and drying—increase the complexity of existing electrode manufacturing processes.^{[ 56 ]} The issue of solvent residue (>300 ppm) necessitates the inclusion of extended vacuum desorption steps, significantly impeding production efficiency. Meanwhile, the swelling effect of prelithiation solvents (e.g., THF) on polyvinylidene difluoride (PVDF) binders can compromise electrode structural uniformity, causing local delamination of the active material.^{[ 82 ]}

Finally, a safety challenge in the chemical prelithiation process of large‐area electrodes lies in the mismatch between the reaction exothermic kinetics and the thermal diffusion capability.^{[ 83 ]} During the immersion process, the high reduction enthalpy of Li─arene complexes, coupled with the low thermal diffusivity of macroscopic electrodes, can result in localized heat accumulation. If a spraying process is employed, the microdroplets (20–50 µm) generated by atomization significantly increase the reaction interface between active materials (such as Li─Biphenyl) and oxygen. More critically, the instantaneous supersaturation effect induced by the volatilization of solvents like THF can trigger the exothermic dimerization reaction of aromatic ligand free radicals, which rapidly escalates localized hotspots into thermal runaway at the electrode scale.^{[ 84 ]}

Therefore, the future direction of chemical prelithiation will focus on developing LAC solutions with broad humidity adaptability to eliminate the dependence on inert atmospheres; establishing a solvent recycling and regeneration process chain to minimize raw material loss and environmental risks; achieving efficient integration with continuous roll‐to‐roll manufacturing processes; and ultimately overcoming the prelithiation bottleneck for large‐area electrodes, thereby driving the technology from laboratory scale to industrial‐scale application.

3. Cathode Prelithiation

Anode prelithiation is a widely employed strategy to mitigate the irreversible loss of active Li⁺, which is primarily caused by the formation of the SEI and other parasitic reactions. However, the high chemical reactivity and ambient instability of anode prelithiation agents have hindered their practical application. By contrast, cathode prelithiation presents a more convenient approach for Li compensation, owing to its simpler fabrication process and superior stability.^{[ 5} , ^{85 ]} Generally, cathode prelithiation can be classified into two main strategies: the use of cathode prelithiation additives and the development of overlithiated cathode materials.

3.1. Cathode Prelithiation Additives

From a practical application perspective, cathode prelithiation materials must satisfy four fundamental criteria: delithiation potential aligned with the cathode's operational voltage window; prelithiation capacity exceeding 300 mAh g⁻¹; excellent chemical stability with no intolerable side reactions occurring with the overall battery system; excellent environmental stability and high adaptability to industrial‐scale manufacturing. Guided by these design principles, four representative cathode prelithiation additives can be systematically classified as follows: transition metal oxides; metalloid oxides; organic lithium compounds; inorganic lithium compounds.

Transition metal oxides (TMOs), such as Li₂NiO₂,^{[ 86 ]} Li₂CuO₂,^{[ 87 ]} Li₅FeO₄,^{[ 88 ]} and Li₆CoO₄,^{[ 89 ]} have been widely explored as effective prelithiation reagents due to their sufficient active Li compensation capacity. For instance, orthorhombic Li₂NiO₂ delivers a prelithiation capacity of 294.7 mAh g⁻¹ within the voltage range of 2.8–4.3 V (vs Li/Li⁺). Incorporating 8 wt% Li₂NiO₂ into LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) improves the capacity retention of a 6 Ah NCM811||Si/C pouch cell to 80.9% over 700 cycles at 1C.^{[ 90 ]} However, the practical performance of Li₂NiO₂ is hindered by sluggish reaction kinetics and side reactions. To overcome this limitation, Wu et al. and Lee et al. proposed the preparation of Li₂Cu_xNi_1−xO₂ through a solid solution strategy (e.g., Li₂Cu_0.1Ni_0.9O₂, 325.4 mAh g⁻¹; Li₂Cu_0.6Ni_0.4O₂, 371.2 mAh g⁻¹) (Figure 6a).^{[ 91} , ^{92 ]} The improvement is primarily attributed to the larger ionic radius of Cu²⁺ (0.73 Å) compared to Ni²⁺ (0.69 Å), which weakens the coordination strength between the transition metal and oxygen, thereby facilitating the redox reactions of Ni²⁺/Ni³⁺ and anionic oxygen.^{[ 93 ]} In parallel, Li₅FeO₄, an antifluorite‐type oxide with a theoretical capacity 867 mAh g⁻¹, has garnered attention as a promising prelithiation additive. Su et al. synthesized Li₅FeO₄ by calcining LiOH and Fe₂O₃ precursors at high temperature in an argon‐filled atmosphere, achieving an initial charge capacity exceeding 700 mAh g⁻¹ at 4.3 V.^{[ 94 ]} When 7 wt% Li₅FeO₄ is incorporated into LiCoO₂ (LCO) cathodes, the reversible capacity of LCO||hard carbon full cell increases from 126 to 144 mAh g⁻¹. To further improve the reaction kinetics of Li₅FeO₄, Lee et al. integrated conductive CNT networks and reduced particle sizes of Li₅FeO₄ to 200–400 nm.^{[ 95 ]} Further, Mn‐doped Li_5.125Fe_0.875Mn_0.125O₄ (578 mAh g⁻¹) and Zr‐doped Li₅Fe_0.97Mn_0.03O₄ (725 mAh g⁻¹) were developed to improve Li mobility and oxygen redox activity.^{[ 96 ]} Despite their high capacity, both Li₅FeO₄ and Li₂NiO₂ exhibit poor stability under ambient conditions. Exposure to air leads to Li loss and the formation of insulating by‐products such as Li₂O, Li₂CO₃, and LiOH, resulting in surface reconstruction and reduced Li⁺ diffusion.^{[ 97 ]} Various surface coating strategies have been employed to stabilize TMOs, suppress side reactions, and reduce surface alkalinity under ambient conditions—an essential factor in preventing cathode slurry gelation. For example, Lee et al. and Li et al. synthesized LiTaO₃@Li₂NiO₂ and Li₆CoO₄@Li₅FeO₄, respectively, to enhance ambient stability (Figure 6b,c).^{[ 98} , ^{99 ]} Compared with pristine Li₂NiO₂, the first charge capacity of LiTaO₃@Li₂NiO₂ increases by 36.2% after exposure to air (40% RH) for 24 h. Similarly, the initial charge capacity of Li₆CoO₄@Li₅FeO₄ improves from 64.9 to 518.7 mAh g⁻¹ compared to Li₅FeO₄ after exposure to air for 1 h. Another study showed that Li₃PO₄‐coated Li₅FeO₄ retained a much higher capacity after 3 h of air exposure at 25 °C and 57% RH (94.5 vs 637.3 mAh g⁻¹).^{[ 100 ]}

Figure 6.

Cathode prelithiation: representatives of cathode additives. Transition metal oxides. a) Crystal structures of pristine Li₂NiO₂ and Cu‐doped Li₂Cu_xNi_1−xO₂ solid solutions.^{[ 91 ]} b) Schematic of the stabilization effect of LiTaO₃@Li₂NiO₂.^{[ 98 ]} c) The preparation process of Li₆CoO₄@Li₅FeO₄ prelithiation reagents.^{[ 99 ]} Metalloid oxides. d) Reaction mechanism of elemental sulfur (S) in the Li₄SiO₄/S. e) Rheological characteristic curves of a commercial LiFePO₄ cathode, bare Li₄SiO₄‐based cathode, and Li₄SiO₄/S‐based cathode. f) Long‐term cycling performance of 2.3 Ah LiFePO₄||graphite pouch cell with 10 wt% Li₄SiO₄/S.^{[ 101 ]} (a) Reproduced with permission.^{[ 91 ]} Copyright 2023, American Chemical Society. (b) Reproduced with permission.^{[ 98 ]} Copyright 2023, Elsevier. (c) Reproduced with permission.^{[ 99 ]} Copyright 2021, IOP Publishing. (d–f) Reproduced with permission.^{[ 101 ]} Copyright 2024, Wiley‐VCH.

Li‐rich metalloid oxides, such as Li₄SiO₄, represent a promising class of cathode prelithiation reagents that address both the loss of active Li during SEI formation and the persistent side reactions that occur during long‐term cycling. However, Li₄SiO₄ suffers from low ionic conductivity (1.21 × 10⁻⁵ S cm⁻¹, 25 °C) and the high Gibbs free energy (1347.2 kJ mol⁻¹), limiting its utility.^{[ 101 ]} Tian et al. addressed this by introducing sulfur (S) element to form a composite Li₄SiO₄/S (2Li₄SiO₄ + S → SiO₂ + Li₂SO₄ + 6Li⁺ + 6e⁻), achieving a prelithiation capacity of ≈566 mAh g⁻¹ (Figure 6d).^{[ 101 ]} This is attributed to the fact that the addition of S increased the ionic conductivity of Li₄SiO₄/S at 25 °C (2.67 × 10⁻⁵ vs 1.21 × 10⁻⁵ S cm⁻¹), while the optimization of the reaction pathway lowered the reactive Gibbs free energy of Li₄SiO₄ (686.39 vs 1347.2 kJ mol⁻¹). Additionally, Li₄SiO₄/S demonstrates excellent environmental stability, maintaining structural integrity after 24 h of exposure to either humid air (60% RH) or the solvent NMP. Moreover, the Li₄SiO₄/S‐based slurry exhibits rheological behavior comparable to commercial LiFePO₄ (LFP) slurries (2.1 × 10⁵ vs 1.7 × 10⁵ mPa s at 1.0 rad s⁻¹), ensuring compatibility with standard electrode fabrication (Figure 6e). As shown in Figure 6f, the LFP||graphite pouch cell with 10 wt% Li₄SiO₄/S composite demonstrates 85% capacity retention after 3000 cycles at 1C, corresponding to a capacity fade of 0.005% per cycle.

Due to the high prelithiation capacity and environmental compatibility, organic lithium compounds, such as Li₂C₂O₄,^{[ 8} , ^{102 ]} Li₂C₃O₅,^{[ 102 ]} Li₂C₄O₄,^{[ 103 ]} C₂H₃O₂Li,^{[ 3 ]} have been investigated as effective cathode prelithiation additives. Taking Li₂C₂O₄ as an example, its full decomposition produces gaseous CO₂ and active Li (Li₂C₂O₄ → 2Li⁺ + 2CO₂ + 2e⁻), where CO₂ can be expelled from the battery through gas pocket removal or open‐formation processes, reducing the impact of residual byproducts on battery performance. However, the poor ionic and electronic conductivity of Li₂C₂O₄ leads to a high oxidation potential (>4.7 V), limiting its practical application. To enhance its reaction kinetics, a recrystallization method was developed to produce Li₂C₂O₄ particles (1–10 µm) in combination with CMK‐3 (specific surface area ≥800 m² g⁻¹), reducing the oxidation potential to 4.25 V at 0.02C.^{[ 8 ]} Further studies revealed that catalytic effects of carbon‐based materials, transition metal oxides (e.g., NiO, Co₃O₄), and transition metal carbides (e.g., Mo₂C, Mo₂C─W₂C) could catalyze the decomposition of Li₂C₂O₄.^{[ 104 ]} To enable scalable production, a spray‐drying method was applied to synthesize MoC_1−x/NC─Li₂C₂O₄ composites, achieving an activation potential of 4.24 V (Figure 7a).^{[ 105 ]} In addition to catalytic approaches, molecular structure tuning has proven effective. Specifically, it was found that the decomposition potential of Li₂C₃O₅ and Li₂C₂O₄ decreases with an increasing number of carbonyl groups (Figure 7b).^{[ 102} , ^{106 ]} This is attributed to the electron‐withdrawing nature of carbonyl groups, which reduces the electronic density and raises the highest occupied molecular orbital (HOMO) energy level, thereby reducing the decomposition potential. Li₂C₄O₄, while exhibiting a slightly lower theoretical specific capacity (440 mAh g⁻¹) and decomposition potential (≈4 V), also demonstrates promising prelithiation capability (Li₂C₄O₄ → 2CO₂ + 2C + 2e⁻ + 2Li⁺). The NCM622||Si/Gr full cell with 0, 2.5, 5, and 10 wt% Li₂C₄O₄ in the cathode reaches 60% state of health after 81, 96, 105, and 138 cycles, respectively—extending cycle life by 19%, 30%, and 70% for 2.5, 5, and 10 wt%.^{[ 103 ]} Additionally, a metal carboxylate additive (C₂H₃O₂Li) was designed based on the Kolbe electrolysis mechanism. The oxidative decomposition potential is governed by the bond strength of the metal–oxygen bond. Incorporating electron‐donating substituents and metal cations with low charge density effectively weakens this bond, thus lowering the decomposition potential (Figure 7c).^{[ 3 ]}

Figure 7.

Cathode prelithiation: representatives of cathode additives. Organic lithium compounds. a) Schematic illustration of the synthesis process of MoC_1−x/NC‐Li₂C₂O₄ composites.^{[ 105 ]} b) Chemical structural formulae of Li₂C₃O₅ and Li₂C₂O₄.^{[ 102 ]} c) Illustration of the premetallation mechanism triggered by the Kolbe electrolysis for EES systems.^{[ 3 ]} Inorganic lithium compounds. d) Schematic illustration of the whole prelithiation process for graphite anode with Li₃N as a prelithiation additive.^{[ 107 ]} e) Structural design and synthesis of Co─Li₂CO₃@LiCoO₂ by ball milling.^{[ 108 ]} f) The preparation process of Li₂O/metal prelithiation reagent by the reaction of metal oxides with molten lithium.^{[ 109 ]} g) Schematic of the air stability of Fe/LiF/Li₂O composites.^{[ 110 ]} h) Schematic illustration of the preparation process of Li₂S─PAN composites.^{[ 65 ]} i) Schematic of Li₃P@rGO as a cathode prelithiation additive.^{[ 111 ]} (a) Reproduced with permission.^{[ 105 ]} Copyright 2024, Elsevier. (b) Reproduced with permission.^{[ 102 ]} Copyright 2010, Elsevier. (c) Reproduced with permission.^{[ 3 ]} Copyright 2021, Wiley‐VCH. (d) Reproduced with permission.^{[ 107 ]} Copyright 2020, Elsevier. (e) Reproduced with permission.^{[ 108 ]} Copyright 2023, Wiley‐VCH. (f) Reproduced with permission.^{[ 109 ]} Copyright 2020, Springer Nature. (g) Reproduced with permission.^{[ 110 ]} Copyright 2020, American Chemical Society. (h) Reproduced with permission.^{[ 65 ]} Copyright 2021, American Chemical Society. (i) Reproduced with permission.^{[ 111 ]} Copyright 2021, American Chemical Society.

Inorganic lithium compounds, such as Li₃N,^{[ 112 ]} Li₂O,^{[ 113 ]} Li₂S,^{[ 114 ]} and Li₃P,^{[ 111 ]} with high theoretical specific capacity, have been extensively studied as cathode additives to compensate for active Li loss in LIBs. Among them, Li₃N is an α‐phase ionic conductor that delivers 1 mS cm⁻¹ at room temperature. However, its practical application is hindered by its insufficient stability in conventional polar solvents (e.g., NMP, dimethyl sulfoxide, and H₂O). The stability of Li₃N can be greatly improved by surface passivation with layers like Li₂O/Li₂CO₃@Li₃N or LiF/Li₂CO₃@Li₃N.^{[ 115 ]} For example, the LiF/Li₂CO₃@Li₃N retained a high prelithiation capacity of 1576 mAh g⁻¹ (≈90% of the initial capacity) after 26 h of exposure to humid air (12% RH). To evaluate the suitability of Li₃N‐based additives in electrodes, it was found that surface coating of LCO electrodes with Li₃N (5 wt%) outperforms bulk dispersion of Li₃N (2–4 wt%) within the electrode matrix.^{[ 112 ]} This is attributed to gas generation and poor electronic conductivity associated with the dispersed configuration. To optimize electrode design and address solvent compatibility issues, a method combining Li metal vaporization and nitrogen treatment was employed to introduce a controlled amount of Li₃N on the electrode surface (Figure 7d).^{[ 107 ]} The discharge capacity of LFP||graphite full cells (1% Li₃N) increased by 30.7% after 120 cycles. Additionally, Li₃N shows increasing prelithiation capacity of 1319.7 and 1399.3 at cutoff potentials of 4.0 and 4.2 V (vs Li/Li⁺), respectively—though still below its theoretical capacity of 2309 mAh g⁻¹.^{[ 107} , ^{112 ]} Therefore, advanced characterization techniques, such as differential electrochemical mass spectrometry, in situ Raman, and in situ FTIR, are required to thoroughly investigate the reaction mechanism of Li₃N.

Li₂O and LiF, while exhibiting excellent air stability, suffer from high decomposition potentials (>4.7 V vs Li/Li⁺), which limit their electrochemical reactivity. To enhance electrochemical reactivity, strategies such as particle size optimization, conductive network enhancement, and catalyst introduction are commonly employed. For example, Li₂O@LiCoO₂, Li₂O₂@LiNi_0.33Co_0.33Mn_0.33O₂, and Li₂CO₃@LiCoO₂, prepared via ball milling, effectively utilized optimized particle sizes and the catalytic effect of high‐valent cobalt, both achieving oxidative decomposition potentials lower than 4.3 V.^{[ 113} , ^{116 ]} In addition, transition‐element‐doped defect engineering significantly reduced the decomposition potential of Li₂CO₃ (Co─Li₂CO₃@LiCoO₂, 4.25 V, 612 mAh g⁻¹) and Li₂O ((Li_0.66Co_0.11 ^□ _0.23)₂O, 4.0 V, ≈980 mAh g⁻¹) by enhancing conductivity and weakening Li─O bonds (Figure 7e).^{[ 108} , ^{117 ]} Unlike the aforementioned strategies, the reaction pathway of Li₂O by introducing transition metals (e.g., Co) has transformed its decomposition into a conversion reaction, improving reaction kinetics and achieving a capacity of 609 mAh g⁻¹ for Co/Li₂O (Figure 7f).^{[ 109 ]} This technique has also been successfully applied to enhance the reaction kinetics of LiF (Co/LiF, 516 mAh g⁻¹) and Li₂S (Co/Li₂S, 670 mAh g⁻¹).^{[ 118 ]} Recently, a ternary Fe/LiF/Li₂O additive was synthesized via the reaction FeOF + Li → Li₂O + LiF + Fe, leveraging the electronic conductivity of M─O and the air stability of M─F bonds to deliver a capacity of 527 mAh g⁻¹ (Figure 7g).^{[ 110 ]} Compared to the binary Fe/Li₂O, the ternary Fe/LiF/Li₂O showed 43.1% higher capacity retention after 48 h (65.3% vs 22.2%). Similar to LiTaO₃@Li₂NiO₂ and Li₆CoO₄@Li₅FeO₄, a poly(methyl methacrylate)‐coated stabilized Li₂O₂‐based reagent (P─Li₂O₂, 1148 mAh g⁻¹) was developed using electrospinning techniques, significantly enhancing its stability under ambient conditions (80.4% vs 18.9%, 8 h, 40% RH).^{[ 119 ]}

Compared to Li₂O and Li₃N, compounds such as Li₂S, Li₂Se, and Li₃P decompose into solid products (S, Se, and P, respectively), thereby avoiding issues like electrode structure degradation and cell swelling caused by gas evolution during prelithiation. However, the practical application of Li₂S is limited by its low ionic conductivity (≈10⁻⁵ S cm⁻¹, RT), electronic conductivity (≈10⁻¹³ S cm⁻¹, RT), as well as the insulating nature of its decomposition product sulfur.^{[ 120 ]} Furthermore, the polysulfide intermediates formed during the reaction exhibit poor compatibility with conventional carbonate‐based electrolytes. Alternatively, Li₂Se exhibits superior ionic conductivity (>10⁻⁵ S cm⁻¹, RT) and high electronic conductivity of its decomposition product Se (≈10⁻³ S cm⁻¹, RT), along with improved thermodynamic and chemical stability in carbonate electrolytes.^{[ 120 ]} Incorporating 6 wt% Li₂Se into LFP cathodes has been shown to enhance the initial specific capacity by 9% and the energy density by 19.8%, while maintaining excellent rate capability and cycling stability. Additionally, Li₂S─PAN (668 mAh g⁻¹, 2.5–4.0 V) could effectively mitigate polysulfide dissolution and shuttle effects, owing to its unique organic backbone and stable S confinement mechanism (Figure 7h).^{[ 65 ]} The LFP/Li₂S─PAN||Si/C full cell showed reversible capacities of 123 and 107 mAh g⁻¹ in the 1st and 10th cycles, respectively, which were 15.5% and 24.5% higher than those of the LFP||Si/C cell. Wang et al. developed a Li₃P@rGO composite by embedding Li₃P into reduced oxidized graphene (rGO) matrix, which significantly enhanced both the electrochemical performance of the battery (Figure 7i).^{[ 111 ]} Notably, when 2.5 wt% of Li₃P@rGO is applied on the LFP side of a LFP||graphite full cell, the device delivers initial discharge capacities of 160.6 mAh g⁻¹—an increase of 10.2% compared to the cell without the additive. This performance enhancement can be partly attributed to the unique property of Li₃P, whose decomposition yields elemental phosphorus with flame‐retardant characteristics and a delithiation potential around 1 V.

In summary, cathode prelithiation, offering simpler processing and better stability than anode prelithiation, has emerged as a more practical strategy to compensate for lithium loss, mainly through additives or overlithiated materials. Transition metal oxides (e.g., Li₂NiO₂, Li₅FeO₄) require doping or composite strategies to enhance prelithiation capacity, while their environmental sensitivity necessitates surface coatings (e.g., LiTaO₃, Li₃PO₄) for improved stability. Organic lithium compounds (e.g., Li₂C₂O₄) rely on catalytic strategies or molecular design to lower decomposition potentials. However, their inherently low conductivity necessitates the formation of optimized nanocomposites to improve their electrochemical performance. Despite these advances, the evolution of gaseous by‐products during decomposition can compromise electrode structural integrity. Metalloid oxides (e.g., Li₄SiO₄) and inorganic lithium salts (Li₂O, Li₃N, etc.) offer high theoretical capacities, but face challenges including excessive decomposition potential and poor conductive by‐products, requiring transition metal doping (e.g., Co/Li₂O) or interfacial engineering to optimize reaction kinetics. Additionally, solid‐state by‐products from these reagents may adversely affect long‐term cycling stability. Collectively, the key challenges in developing effective cathode prelithiation additives center on achieving environmental stability, managing decomposition by‐products, and ensuring scalability. Table 4 provides a systematic summary of the prelithiation capacity of various cathode prelithiation additives, along with full cell configurations and electrochemical performance.

Table 4.

The summary of various cathode prelithiation additives.

Prelithiation additive	Potential range	Prelithiation capacity	Full cell [wt%] additive	Cycle life (number)	Capacity increasing	Refs.
Li2NiO2	2.8–4.3 V	295 mAh g−1	NCM811||Si/C‐ 8 wt%	100	13 mAh g−1	[90]
Li2Cu0.1Ni0.9O2	2.8–4.4 V	325 mAh g−1	NCM811||graphite‐ 13 wt%	100	≈8 mAh g−1	[91]
Li2Cu0.6Ni0.4O2	3.0–4.3 V	373 mAh g−1	NCM811||Cu‐ 30 wt%	100	≈150 mAh g−1	[92]
LiTaO3@Li2NiO2	2.5–4.3 V	≈190 mAh g−1	NCM811||SiOx/C‐ 10 wt%	200	≈12 mAh g−1	[98]
Li5FeO4	3.0–4.7 V	763 mAh g−1	NCM523||Si/C‐ 7.1 wt%	80	≈28 mAh g−1	[121]
Li6MnO4	2.5–4.5 V	≈645 mAh g−1	NCM811||SiOx/C‐ 10 wt%	35	≈23 mAh g−1	[122]
LiAlO2@Li6CoO4	3.0–4.3 V	727 mAh g−1	NCM811||SiOx/C	50	55 mAh g−1	[123]
Li6CoO4@Li5FeO4	2.5–4.5 V	≈710 mAh g−1	NCM811||graphite‐ 8 wt%	50	–	[99]
Li5.125Fe0.875Mn0.125O4	2.0–4.5 V	578 mAh g−1	LFP||Si/C‐ 5 wt%	100	≈12 mAh g−1	[96]
Li5Fe0.97Zr0.03O4	2.5–4.5 V	725 mAh g−1	NCM811||graphite	50	≈12 mAh g−1	[96]
Li4SiO4/S	2.5–4.6 V	≈566 mAh g−1	LFP||graphite	3000	–	[101]
Ni/N─rGO@Li2C2O4	2.5–4.5 V	≈260 mAh g−1	NCM811||SiOx‐ 10 wt%	120	40 mAh g−1	[104]
Li2C2O4/Mo2C	3.0–4.4 V	263 mAh g−1	LCO||SiO‐ 10 wt%	150	39 mAh g−1	[104]
MoC1−x/NC@Li2C2O4	3.0–4.7 V	439 mAh g−1	NCM622||graphite	110	24 mAh g−1	[105]
Li2C2O4/MoN	2.5–4.2 V	318 mAh g−1	LFP||graphite	250	24 mAh g−1	[124]
Li2C4O4	1.5–4.5 V	≈430 mAh g−1	LFP||Cu‐ 10 wt%	40	≈65 mAh g−1	[125]
C2H3O2Li	2.5–4.5 V	≈350 mAh g−1	LFP||graphite	50	2 mAh g−1	[3]
C3O5Li2	2.5–4.5 V	432 mAh g−1	LFP||graphite‐ 4.8 wt%	500	≈25 mAh g−1	[126]
C6H3O2FLi2	2.0–4.2 V	383 mAh g−1	NCM622||Cu‐ 15 wt%	100	≈110 mAh g−1	[127]
Li3N	2.0–4.0 V	1320 mAh g−1	LFP||graphite‐ 1 wt%	120	23 mAh g−1	[107]
LiF/Li2CO3@Li3N	2.8–4.2 V	≈1799 mAh g−1	LFP||hard carbon‐ 2.5 wt%	400	≈45 mAh g−1	[115]
Li2CO3	3.0–4.6 V	692 mAh g−1	NCM523||Si/C‐ 5 wt%	50	32 mAh g−1	[128]
Co─Li2CO3@LiCoO2	3.0–4.7 V	612 mAh g−1	NCM811||Si/C‐ 9 wt%	50	≈38 mAh g−1	[108]
PMMA─Li2O2	3.0–4.6 V	1148 mAh g−1	NCM523||Si/C‐ 4.8 wt%	50	47 mAh g−1	[119]
Li2O─Li2CoO2	2.5–4.3 V	≈880 mAh g−1	LFP||graphite‐ 3.5 wt%	100	≈45 mAh g−1	[113]
Li2O/rGO	2.5–4.0 V	488 mAh g−1	LFP||hard carbon	100	33 mAh g−1	[129]
(Li0.66Co0.11 □ 0.23)2O	3.0–4.3 V	≈980 mAh g−1	LCO||SiOx/C‐ 7 wt%	50	≈15 mAh g−1	[117]
Co/Li2O	2.5–4.1 V	609 mAh g−1	LFP||graphite‐ 4.8 wt%	100	≈30 mAh g−1	[109]
Fe/LiF/Li2O	2.5–4.4 V	527 mAh g−1	NCM811||SiO/C‐ 4.8 wt%	100	≈22 mAh g−1	[110]
Li2S/KB/polyvinylpyrrolidone (PVP)	1.8–3.8 V	≈650 mAh g−1	LFP||Si/C	200	≈85 mAh g−1	[130]
Li2Se	2.5–4.4 V	527 mAh g−1	LFP||graphite‐ 6 wt%	100	≈30 mAh g−1	[120]
Li2Se	1.0–4.3 V	479 mAh g−1	NCM811||Si/C‐ 7 wt%	150	37 mAh g−1	[120]
Li2S─PAN	2.5–4.0 V	668 mAh g−1	LFP||Si/C	30	≈40 mAh g−1	[65]
Li3P@rGO	2.0–3.8 V	1547 mAh g−1	LFP||graphite‐ 5 wt%	100	16 mAh g−1	[111]

3.2. Overlithiated Cathode Materials

Overlithiated cathode materials are predominantly employed in three major categories: polyanion‐type cathodes (e.g., LiFePO₄ and Li₃V₂(PO₄)₃),^{[ 131 ]} spinel‐type cathodes (e.g., LiNi_0.5Mn_1.5O₄ and LiMn₂O₄),^{[ 132 ]} and layered oxide cathodes (e.g., LiNi_0.8Co_0.1Mn_0.1O₂ and LiNi_0.6Co_0.2Mn_0.2O₂).^{[ 133 ]} Through chemical or electrochemical prelithiation, these materials can incorporate additional active Li into their crystal structures while maintaining structural stability. This portion of active Li⁺, once dislodged during the initial charging cycle, cannot be reversibly reintercalated into the cathode material in subsequent cycles due to kinetic limitations. Consequently, this “dynamically lost” capacity can be utilized to compensate for the irreversible loss of active Li. In the following sections, we summarize recent research on the overlithiated cathode materials, including polyanionic, spinel structured, and layered structured cathodes.

LiFePO₄, a widely commercialized polyanionic cathode material, accommodates excess Li⁺ at octahedral Fe and tetrahedral P sites upon overlithiation. This process is accompanied by a reduction in the Fe 2p binding energy from 711.0 eV (pristine LFP) to 710.7 eV (Figure 8a).^{[ 131 ]} However, due to its limited extra Li storage capacity, overlithiated LFP delivers a relatively low Li compensation capacity (≈20 mAh g⁻¹). Compared to LFP, Li₃V₂(PO₄)₃ has a multistep (de)intercalation behavior, making it more suitable for Li compensation. During the first charge to 3.6 V, Li⁺ is extracted from Li₃V₂(PO₄)₃, forming Li₂V₂(PO₄)₃. This Li release can offset irreversible Li loss at the anode (Figure 8b).^{[ 131 ]} Since subsequent discharging occurs above 3.5 V, Li⁺ cannot be reinserted, resulting in a full cell configuration of Li₂V₂(PO₄)₃||Li_xC. To further enhance the prelithiation capacity, Li₃V₂(PO₄)₃ can be electrochemically reduced to Li₅V₂(PO₄)₃ prior to cell assembly (Figure 8c).^{[ 131 ]} Upon initial charging, Li₅V₂(PO₄)₃||hard carbon donates more Li⁺ to the anode, achieving a higher reversible capacity (124.2 vs 82.1 mAh g⁻¹). However, this material is highly air sensitive, retaining only ≈77% of its initial capacity after 12 h of exposure to ambient conditions.

Figure 8.

Overlithiation for different types of cathode materials. Polyanionic cathodes. a) The initial discharge/recharge voltage profiles of the LFP electrodes with different prelithiation capacities (Li_1+xFePO₄, x ≥ 0).^{[ 131 ]} b) Charge/discharge profiles of Li₃V₂(PO₄)₃||hard carbon and prelithiated Li₂V₂(PO₄)₃||Li_xC full cell after the first cycle.^{[ 131 ]} c) Electrochemical prelithiation process of Li₅V₂(PO₄)₃||hard carbon full cell. The extra two Li⁺ in Li₅V₂(PO₄)₃ were used for the lithiation of hard carbon and the formation of SEI.^{[ 131 ]} Spinel structured cathodes. d) Voltage profiles of the LiNi_0.5Mn_1.5O₄||Li (Li_xNi_0.5Mn_1.5O₄ (0 ≤ x < 2)).^{[ 132 ]} e) Electrochemical performance of LiMn₂O₄ in half cell configuration.^{[ 132 ]} f) The first charge curve of Li_1.04Ni_0.5Mn_1.5O₄ and Li_1.62Ni_0.5Mn_1.5O₄.^{[ 132 ]} Layered structured cathodes. g) Crystal structures of NCM811 and Li₂NCM811 along with the corresponding Li occupations.^{[ 133 ]} h) Comparison of the discharge capacities of Li_1+xNCM811 and Li_1+xNCM622 at the 4th cycle and 200th cycle.^{[ 133 ]} i) Schematic diagram of the gradient interphase layer on the surface of overlithiated LiNi_0.65Mn_0.20Co_0.15O₂.^{[ 133 ]} (a) Reproduced with permission.^{[ 131 ]} Copyright 2022, Wiley‐VCH. (b) Reproduced with permission.^{[ 131 ]} Copyright 2017, Wiley‐VCH. (c) Reproduced with permission.^{[ 131 ]} Copyright 2019, Elsevier. (d) Reproduced with permission.^{[ 132 ]} Copyright 2023, Royal Society of Chemistry. (e) Reproduced with permission.^{[ 132 ]} Copyright 2019, Elsevier. (f) Reproduced with permission.^{[ 132 ]} Copyright 2019, American Chemical Society. (g) Reproduced with permission.^{[ 133 ]} Copyright 2021, Wiley‐VCH. (h) Reproduced with permission.^{[ 133 ]} Copyright 2025, Elsevier. (i) Reproduced with permission.^{[ 133 ]} Copyright 2021, American Chemical Society.

Spinel structured cathodes such as LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ allow reversible Li insertion into both octahedral and tetrahedral sites, making them promising overlithiated cathode materials.^{[ 134 ]} For LiNi_xMn_2−xO₄, the embedding of Li⁺ is accompanied by a phase transition from cubic to tetragonal (Figure 8d).^{[ 132 ]} Taking LiMn₂O₄ as an example, it can incorporate a maximum of ≈0.75 moles of Li (Li_1.75Mn₂O₄) under a current density of 100 mA g⁻¹ (Figure 8e).^{[ 132 ]} However, excessive overlithiation compromises the cycling stability of electrodes. For instance, the initial discharge capacity decreases from 124 mAh g⁻¹ for Li_1.04Ni_0.5Mn_1.5O₄ to 102 mAh g⁻¹ for Li_1.62Ni_0.5Mn_1.5O₄ (Figure 8f).^{[ 132 ]} This capacity reduction can be attributed to the following factors: i) the Jahn–Teller effect in the overlithiated LiNi_0.5Mn_1.5O₄ induces severe ion mixing (with up to 42% of active Mn³⁺ in Li_1.62Ni_0.5Mn_1.5O₄); ii) Li⁺ detachment accompanied by a phase transition between the cubic and tetragonal phases disrupts the spinel framework of LiNi_0.5Mn_1.5O₄.

In layered cathodes such as NCM622 and NCM811, overlithiation pushes Li⁺ into tetrahedral sites of the Li layer. However, full occupation of tetrahedral sites by active Li⁺—as seen in Li₂Ni_0.8Co_0.1Mn_0.1O₂—blocks Li⁺ diffusion pathways.^{[ 133 ]} While this excess Li⁺ is electrochemically unfavorable for energy storage, it can serve as a Li reservoir to compensate for Li loss in the cell. For example, Chen and co‐workers prepared Li_1.37Ni_0.8Co_0.1Mn_0.1O₂ cathode via an electrochemical method, achieving a capacity retention of 84% after 100 cycles for Li_1.37Ni_0.8Co_0.1Mn_0.1O₂||Cu (25 mg cm⁻², 447 Wh kg⁻¹), compared to NCM811||Cu (≈35%) (Figure 8g).^{[ 133 ]} Moreover, LiNi_0.6Co_0.2Mn_0.2O₂ demonstrates superior overlithiation capability (100% vs 28%, at 0.05C rate), faster overlithiation rate, and better cycling stability (91.2% vs 82.9%) than NCM811 (Figure 8h), likely due to its favorable lattice parameters (larger c‐axis, smaller ab‐axis).^{[ 133 ]} In addition, an appropriate degree of surface prelithiation not only supplies additional active Li but also enhances the cycling stability of the electrode material. Taking LiNi_0.65Mn_0.20Co_0.15O₂ as an example, Liu et al. developed a gradient Li‐rich layer on the surface of LiNi_0.65Mn_0.20Co_0.15O₂ via immersion treatment in a Li─naphthalenide/THF solution, resulting in an additional capacity of 24 mAh g⁻¹. This treatment also reduced Ni³⁺ to Ni²⁺, promoting Li/Ni intermixing and stabilizing the layered structure by suppressing transition to a spinel phase (Figure 8i).^{[ 133 ]}

The overlithiation of cathode materials is primarily achieved through two main approaches: electrochemical prelithiation and chemical prelithiation (e.g., Li─naphthalenide/THF, Li─biphenyl, and LiI/acetonitrile).^{[ 74} , ¹³³ , ^{135 ]} However, these methods often suffer from the poor stability of the Li source. Moorhead‐Rosenberg et al. developed a microwave‐assisted chemical prelithiation method for LiNi_0.5Mn_1.5O₄, utilizing tetraethylene glycol as the reducing agent and hydrated LiOH as the Li source.^{[ 136 ]} This approach eliminates the need for an inert atmosphere and effectively addresses the high reactivity issue of the Li source.

Overall, the prelithiation capacity of overlithiated cathodes is typically below 100 mAh g⁻¹, which is inadequate for battery systems experiencing substantial Li losses—such as those employing Si‐based anodes. In parallel, their structural stability remains a key concern, with challenges including high ambient reactivity (e.g., Li₅V₂(PO₄)₃) and phase transitions during Li insertion/extraction (e.g., cubic‐to‐tetragonal transitions in spinel‐type Li_1+xNi_yMn_2−yO₄). Additionally, current synthesis methods—such as microwave‐assisted and solvent‐based approaches—are limited by process complexity and poor scalability. These factors highlight the pressing need for controllable, scalable, one‐step fabrication routes. In summary, overlithiated cathode strategies need to overcome significant barriers to simultaneously achieve adequate Li compensation, structural robustness, and manufacturing feasibility. Table 5 provides a systematic summary of prelithiation capacity of various overlithiated cathodes, along with full cell configurations and electrochemical performance.

Table 5.

The summary of various overlithiated cathodes.

Overlithiated cathodes	Prelithiation capacity	Full cell	Cycle life (number)	Capacity increasing	Refs.
Li3V2(PO4)3	≈70 mAh g−1	Li3V2(PO4)3||hard carbon	2000	–	[131]
Li5V2(PO4)3	–	Li5V2(PO4)3||hard carbon	150	–	[131]
Li1.35Ni0.5Mn1.5O4	≈90 mAh g−1	Li1.35Ni0.5Mn1.5O4||Si/C	100	≈45 mAh g−1	[132]
Li1.62Ni0.5Mn1.5O4	72 mAh g−1	Li1.62Ni0.5Mn1.5O4||Si/C	100	26 mAh g−1	[132]
Li1.37Ni0.8Co0.1Mn0.1O2	≈55 mAh g−1	Li1.37Ni0.8Co0.1Mn0.1O2||Cu	100	≈100 mAh g−1	[133]
Li1.33Ni0.6Co0.2Mn0.2O2	≈40 mAh g−1	Li1.33Ni0.6Co0.2Mn0.2O2||Cu	200	≈50 mAh g−1	[133]
Li1+xNi0.65Mn0.20Co0.15O2	24 mAh g−1	Li1+xNi0.65Mn0.20Co0.15O2||Si/C	70	–	[133]

4. Prelithiation of Other Parts of LIBs

The battery contains not only active materials responsible for Li⁺ insertion and extraction, but also various functional components such as electrolytes, current collectors, separators, binders, and encapsulation materials. Prelithiation reagents can be incorporated either by direct mixing with electrode materials or by leveraging these functional components as Li reservoirs to compensate for active Li⁺ loss.^{[ 5} , ^{137 ]} Additionally, prelithiation can effectively reduce the irreversible consumption of active Li⁺ by these functional components during cycling. In the following section, we summarize recent prelithiation strategies targeting functional components, which can be broadly categorized into four main approaches: binder system modification, separator engineering, electrolyte formulation, and current collector design.

Binders are essential for integrating the electrode active material, conductive additives, and current collector into a mechanically robust and electrochemically stable composite architecture. Si‐based anodes, known for their high specific capacity, present a unique challenge due to significant volume expansion during cycling, demanding exceptional adhesion and mechanical integrity from the binder.^{[ 138 ]} Traditional binders such as PVDF often fall short in meeting these requirements. By contrast, polyacrylic acid (PAA) contains abundant polar functional groups (─COOH), which form strong hydrogen bonds and ion–dipole interactions with silanol groups on Si‐based surface. This effectively mitigates the volume expansion of Si particles.^{[ 139 ]} However, these functional groups (e.g., ─COOH and ─SO₃H) irreversibly react with active Li⁺ during the initial charging process, leading to substantial irreversible consumption of active Li⁺. To address this issue, binder prelithiation strategies have emerged. Crucially, only an optimal degree of prelithiation (i.e., achieving a specific ─COOH/─COOLi ratio) can simultaneously balance the mechanical strength, interfacial stability, and ionic transport kinetics of the binder. Insufficient prelithiation (e.g., PAA, Li_0.25PAA, and Li_0.5PAA) fails to adequately compensate for the irreversible lithium consumption by PAA binders. Conversely, excessive prelithiation (e.g., LiPAA) eliminates hydrogen bonding, severely degrading the binder's mechanical properties (Figure 9a).^{[ 140 ]} For example, Zhang et al. developed a prelithiated rigid‐rod poly(2,2′‐disulfonyl‐4,4′‐benzidine‐terephthalamide) (PBDT) binder with an ionic conductivity of 3.2 × 10⁻⁴ S cm⁻¹ in the liquid LiPF₆ electrolyte at room temperature, effectively reducing active lithium loss while enhancing Li⁺ transport.^{[ 141 ]} As a result, the ICE and cycling stability of the Si‐based anode with the PBDT binder (83.6%, 1010.5 mAh g⁻¹) are significantly improved compared to the Si‐based anode with a PVDF binder (646.8 mAh g⁻¹) after 200 cycles. However, the inherent brittleness of both PBDT and PAA limits their long‐term cycling stability. A hybrid binder (N─P─LiPN) synthesized by integrating a rigid PAA backbone with a flexible Nafion buffer shows excellent mechanical compliance and enhanced Li⁺ conductivity (Figure 9b).^{[ 142 ]} The Si@N─P─LiPN electrode achieves an ICE of 93.18% and maintains stable cycling for 500 cycles at 0.2C. Overall, prelithiated binders featuring functional groups such as ─COOLi or ─SO₃Li not only exhibit outstanding mechanical performance crucial for accommodating Si volume changes but also significantly improve lithium‐ion transport within the electrode. This combination highlights their potential as promising alternatives to conventional nonlithiated binders (e.g., PVDF) for high‐capacity silicon‐based LIBs.

Figure 9.

Prelithiation of other components of batteries. Binders. a) Li _x PAA with different Li contents is obtained from the reaction of PAA and LiOH.^{[ 140 ]} b) Schematic diagram of the hard/soft modulated trifunctional network binder (N─P─LiPN) formed by partially prelithiated Li_xPAA (framework) and soft Li_xNafion (buffer).^{[ 142 ]} Separators. c) Schematic diagram of the prelithiation process of Li₅FeO₄‐decorated separator in a Li‐ion battery.^{[ 143 ]} d) Schematic illustration of a direct regeneration strategy based on a functionalized prelithiated separator.^{[ 144 ]} Electrolytes. e) Schematic diagram of the prelithiation process of organic LiSO₂CF₃ salt in a assembled cell.^{[ 145 ]} f) Cycling performance of monoclinic Fe₂(MoO₄)₃/Mg Swagelok‐type cell using (PhMgCl)₂─AlCl₃ + LiCl + LiCl/THF electrolytes with different LiCl amounts (0, 0.5, 1.0, and 1.5 mol L⁻¹).^{[ 7 ]} Collectors. g) Schematic illustration of the roll‐to‐roll prelithiation process of anodes by transfer printing.^{[ 146 ]} h) Schematic of the preparation process of the air‐stable lithium‐sandwiched current collector (Cu|LiAg|Cu, CLC) and the stabilized lithiation path of graphite anode.^{[ 147 ]} (a) Reproduced with permission.^{[ 140 ]} Copyright 2022, Wiley‐VCH. (b) Reproduced with permission.^{[ 142 ]} Copyright 2020, Wiley‐VCH. (c) Reproduced with permission.^{[ 143 ]} Copyright 2023, Wiley‐VCH. (d) Reproduced with permission.^{[ 144 ]} Copyright 2024, Wiley‐VCH. (e) Reproduced with permission.^{[ 145 ]} Copyright 2025, Springer Nature. (f) Reproduced with permission.^{[ 7 ]} Copyright 2020, American Chemical Society. (g) Reproduced with permission.^{[ 146 ]} Copyright 2023, Springer Nature. (h) Reproduced with permission.^{[ 147 ]} Copyright 2024, Royal Society of Chemistry.

Separators, in liquid LIBs, not only physically isolate the cathode and anode to prevent short circuits but also facilitate electrolyte infiltration and Li⁺ transport. Functionalized separators coated with prelithiation additives—such as Li₂S/Co nanocomposites, Li₂S@C, Li₅FeO₄/Super P/PVDF, and LiC₆—effectively mitigate irreversible Li loss while minimizing structural disruption from residual additives.^{[ 8} , ¹⁴³ , ^{148 ]} Take Li₅FeO₄/Super P/PVDF (LFO─FS) as example, the NCM811|LFO─FS|SiO_x/C full cell exhibits an initial discharge capacity of 196 mAh g⁻¹ representing a 43% improvement over the NCM811|polypropylene (PP)|SiO_x/C cell (137 mAh g⁻¹) (Figure 9c). To further enhance process compatibility and environmental stability (e.g., under humid air), prelithiation separators such as few‐layered graphene flakes─Li₅FeO₄@PP (FGF/LFO@PP), Li₂C₂O₄/CMK‐3@PP (FPS), and Li₂C₄O₄─3CNT@PP (LRS) have been developed.^{[ 8} , ¹⁴⁴ , ^{149 ]} Take LRS as an example, Liu et al. proposed a continuous prelithiation strategy by introducing Li replenishment points every 50 cycles. In a LFP|LRS|graphite cell, this approach maintains a high capacity of 140.4 mAh g⁻¹ after 716 cycles at 0.5C, with a retention of 97.2%. Notably, prelithiation separators not only compensate for Li loss but also revive degraded electrodes. For example, in a degraded LFP (D‐LFP) cell (146.2 mAh g⁻¹), replacing the commercial separator with a FPS restored the discharge capacity to 152.0 mAh g⁻¹ at 0.05C (Figure 9d). The D‐LFP|FPS|graphite full cell maintains 146.7 mAh g⁻¹ after 292 cycles, corresponding to 90.7% retention, in contrast to just 78.5 mAh g⁻¹ and 18.7% retention without the prelithiation separator.

Electrolyte, often described as the “blood” of LIBs, can also serve as extra Li sources when dissolved with sacrificial lithium salts. Recently, Chen et al. employed machine learning to discover a soluble organic lithium salt—LiSO₂CF₃, 189.6 mAh g⁻¹ at 60 mA g⁻¹—with favorable electrochemical performance, decomposition behavior, and prelithiation capability (Figure 9e).^{[ 145 ]} Upon oxidative decomposition during charging, LiSO₂CF₃ releases active Li⁺ along with gases such as SO₂ and C₂F₆, which can be vented from the battery to maintain structural integrity. By introducing LiSO₂CF₃ into a battery with a capacity reduced to 85%, the capacity is restored to 99.6% (1.0 Ah) of its initial value by the 1824th cycle. Furthermore, through repeated Li compensation, 96.0% capacity (0.96 Ah) is retained by the 11 818th cycle, with a capacity decay rate of only 0.34% per 1000 cycles. Additionally, Wang et al. also demonstrated that prelithiation of the electrolyte could activate electrodes in magnesium‐ion batteries.^{[ 7 ]} The slow diffusion of magnesium ions typically results in low iron intercalation levels and rapid capacity decay at the cathode. By adding LiCl to the (PhMgCl)₂─AlCl₃ electrolyte, Li⁺ preintercalates into Fe₂(MoO₄)₃, facilitating Mg²⁺ diffusion. A capacity of ≈80 mAh g⁻¹ is achieved at 1.5 mol L⁻¹ LiCl, and ≈40 mAh g⁻¹ remains after 50 cycles, compared to negligible capacity without LiCl (Figure 9f).

The current collector not only supports electrode components and conducts current but also serves as platforms for Li supplementation compatible with roll‐to‐roll processing. Yang et al. developed a continuous electrodeposition and transfer printing system for prelithiation, comprising electrodeposition, surface cleaning, and transfer printing (Figure 9g).^{[ 146 ]} The ICE of prelithiated graphite and Si/C composite anodes is improved to 99.99% and 99.05%, respectively. In terms of full cell performance, the NCM||30preGr (Li‐loading equivalent to 30% of the graphite capacity) battery achieved 79.6% discharge capacity retention after 595 cycles at 0.5C, while the NCM||25preSi/C (Li‐loading equivalent to 25% of the Si/C capacity) cell retained 95.1% discharge capacity after 98 cycles at 0.1C. However, prelithiation residues (e.g., Li₂O, Li₂CO₃) from transfer‐printing system adversely affect both electrode adhesion and electrical conductivity. To mitigate this issue, Zhang et al. designed an air‐stable Li‐complemented collector with a sandwich structure (Cu/LiAg/Cu, CLC) to address the issue of residues from contact prelithiation (Figure 9h).^{[ 147 ]} The mechanical rolling process of CLC created 5 µm micropores on its surface (16 µm thickness), enabling efficient Li⁺ transport. Although the ICE of the LFP||graphite─CLC cell is only 92% due to the low active Li release rate, the continuous release of active Li from CLC enables the battery to achieve a capacity retention rate of 96% after 400 cycles, compared to 80% for the control. Furthermore, for Si‐based anodes, the CLC prelithiation method effectively reduces electrode damage and heat generation caused by roll lithiation.

In summary, prelithiation strategies targeting various inactive components of LIBs—including binders, separators, electrolytes, and current collectors—have demonstrated effectiveness in compensating for active Li loss during cycling. However, major challenges remain in three key areas: binder engineering (e.g., Li_xPAA and N─P─LiPN systems), functionalized separator modifications (e.g., Li₂C₄O₄─3CNT and FGF/LFO composites), and roll‐to‐roll compatible current collector prelithiation. These limitations largely stem from the high reactivity and poor scalability of Li precursors, along with adverse effects of byproducts on electrode/electrolyte interfaces. Future research should focus on interfacial stabilization, fine‐tuning Li release kinetics, and mechanistic elucidation of Li compensation pathways to realize scalable, robust prelithiation technologies. Table 6 provides a systematic summary of various prelithiation methods for inactive components of LIBs, along with full cell configurations and electrochemical performance.

Table 6.

The summary of other prelithiation methods for LIBs.

Prelithiation additive	Full cell	Cycle life (number)	Capacity increasing (mAh g−1)	Refs.
PBDT	LiNi0.5Mn0.3Co0.2O2||Si/C	50	57	[141]
Li0.5PAA	Si||Li	300	788	[140]
N─P─LiPN	Si||Li	100	≈1350	[142]
Li2S/Co	LFP||graphite	100	≈45	[8]
Li5FeO4─FS	NCM811||SiOx/C	100	52	[143]
FGF/LFO	D‐LFP||graphite	250	≈140	[144]
LiC6@PP/PE	LFP||Si	100	≈120	[148]
Li2C4O4─3CNT	LFP||graphite	300	≈12	[149]
Li2C2O4/CMK‐3	D‐LFP||graphite	292	68	[8]
LiSO2CF3	LFP||graphite	11 818	–	[145]
Li	LiNi0.33Mn0.33Co0.33O2||Si/C	98	23	[146]
Cu/LiAg/Cu	LFP||graphite	400	–	[147]

5. High‐Capacity Prelithiated Full Cell System

The development of high‐capacity full cell systems demands holistic consideration of electrode material compatibility, interfacial stability, and Li supply management.^{[ 150 ]} State‐of‐the‐art LIBs employing ternary cathodes (practical energy density <350 Wh kg⁻¹) are approaching the fundamental limitations of existing technological routes.^{[ 151 ]} While high‐capacity Li‐free cathodes such as FeS₂ (894 mAh g⁻¹, 1271 Wh kg⁻¹)^{[ 152 ]} and S (1672 mAh g⁻¹, 2510 Wh kg⁻¹)^{[ 153 ]} demonstrate exceptional cathode capacity enhancements, their Li‐free nature necessitates the use of a Li metal anode to provide a shuttle of Li⁺. This, in turn, gives rise to safety hazards, including continuous Li dendrite growth and increased side reactions at the interface.^{[ 154 ]} Prelithiation technology by preconverting anode materials such as C, Si, and P into Li storage phases (LiC₆, Li₂₂Si₅, Li₃P), innovatively establishes a “prelithiated anode||Li‐free cathode” full cell system. This paradigm not only surmounts energy density constraints but also neutralizes the inherent safety risks associated with Li metal anodes. The advantages of this system can be summarized as follows: anode‐derived Li supply (allowing the use of high‐capacity Li‐free cathodes), coordinated interfacial–electrochemical and bulk‐mechanical stabilization (synchronously suppressing the shuttle effect of polysulfides and the failure of anode expansion), and a breakthrough in energy density (the theoretical energy density of the LiC₆||S system exceeding 1000 Wh kg⁻¹).^{[ 13 ]}

Graphite‐based prelithiated C anodes have shown excellent compatibility with S cathodes. For example, a full cell system utilizing prelithiated graphite (LiC₆) paired with S/Ketjen black composite cathodes achieves an initial discharge capacity of 1300 mAh g⁻¹, with a capacity retention rate of over 67% after 400 cycles, and an energy density of 572 Wh kg⁻¹ (Figure 10a).^{[ 155 ]} The high reversibility of the LiC₆ anode is attributed to the stable SEI formed on its surface, which effectively suppresses the polysulfide shuttle effect. The LiC₆||FeS₂ system, constructed through an in situ prelithiation process, achieves 72% capacity retention after 300 cycles in a carbonate electrolyte, demonstrating broader electrolyte compatibility compared to traditional Li metal anodes (Figure 10b).^{[ 156 ]} The primary challenges for Li_xC||S full cells include S loading density limitations and fluctuations in rate performance. Developing high‐loading S composite cathodes and efficient conductive network designs is the key optimization avenue.

Figure 10.

Prelithiated anode||Li‐free cathode full cell systems. Prelithiated C anodes. a) A Li_xC||S full cell system exhibits superior cycling stability over conventional Li||S configurations, attributed to mitigated Li depletion and dendrite suppression.^{[ 155 ]} b) The structure of the LiC₆||FeS₂ full cell with in situ prelithiated graphite anode.^{[ 156 ]} Prelithiated Si anodes. c) A CNT‐interlayered Li_xSi||S full cell design to suppress polysulfide crosstalk.^{[ 157 ]} d) A freestanding Li_xSi alloy/graphene foil anode achieves 99.5% average CE (vs 98.8% in conventional Li─S systems) through physical confinement of polysulfides, enabling ambient‐air process compatibility while maintaining electrochemical stability.^{[ 13 ]} Prelithiated P anodes. e) Schematic of a Li_xP||S full cell system.^{[ 63 ]} f) The Li₃P||S full cell demonstrates a high capacity retention of 97.1% over 600 cycles, driven by the stabilized Li₃P/electrolyte interface.^{[ 158 ]} (a) Reproduced with permission.^{[ 155 ]} Copyright 2018, Elsevier. (b) Reproduced with permission.^{[ 156 ]} Copyright 2024, American Chemical Society. (c) Reproduced with permission.^{[ 157 ]} Copyright 2020, Elsevier. (d) Reproduced with permission.^{[ 13 ]} Copyright 2017, Springer Nature. (e) Reproduced with permission.^{[ 63 ]} Copyright 2020, Elsevier. (f) Reproduced with permission.^{[ 158 ]} Copyright 2020, Royal Society of Chemistry.

Prelithiated Si anodes, with a theoretical capacity of nearly 4200 mAh g⁻¹ (based on Si), are an ideal candidate for high‐energy density LIBs. However, challenges such as the expansion failure of Si anodes with high Li content and their reactivity with polysulfides are difficult to overcome. Mesoporous Si (with a pore size of 10 nm) is prelithiated by direct contact to obtain Li_xSi alloys (initial capacity of 2997 mAh g⁻¹), where the hierarchical pore structure helps buffer the 300% volume strain.^{[ 157 ]} A full cell system of Li_xSi||S is constructed with a CNT interlayer (Figure 10c). Scanning electron microscope–energy dispersive spectrometer confirmed that the CNT interlayer physically adsorbs polysulfides, enhancing the capacity retention from 63% to 80%. A further advancement is the development of air‐stable Li₂₂Si₅/graphene composite foil (Figure 10d).^{[ 13 ]} The multilayer graphene (3–6 layers) coating allows the electrode to retain 86% of its capacity after 3 days of exposure to 50% RH, whereas pure Li fails after just 3 min of exposure. A drawback is that the discharge voltage plateau of the Li_xSi─S system is about 0.1–0.2 V lower than that of the Li─S system. This gap can be compensated by controlling the lithiation degree (Li_xSi, x = 2.2–4.4) and adjusting the S host energy levels. The current bottleneck in the practical application of Li─Si alloys lies in the large‐scale passivation process. Adopting gradient lithiation strategies and in situ construction of artificial SEI layers is expected to lead to breakthroughs for large‐scale applications.

P‐based materials, with their high specific capacity (2596 mAh g⁻¹) and fast ionic conduction characteristics at 25 °C (ionic conductivity of 10⁻⁴ S cm⁻²), demonstrate unique advantages in fast‐charging batteries.^{[ 159 ]} Through the chemical prelithiation process, a Li₃P‐based Li compensation network is constructed in the P/C composite anode (40 wt% P content). This significantly improves the ICE from 74% to 93%, effectively addressing the issue of active Li loss in high‐capacity alloy anodes (Figure 10e).^{[ 63 ]} The prelithiated P/C anode retains 880 mAh g⁻¹ of capacity (84% of the theoretical value) at a high rate of 2 A g⁻¹, attributed to the high interface energy (45.64 meV Å⁻²) of Li₃P and the low solvent molecular coordination, which facilitates the rapid desolvation of Li⁺.^{[ 160 ]} However, the Li₃P||S full cell system is initially limited by cycling degradation caused by polysulfide shuttling and polyphosphide dissolution, resulting in only 67.8% capacity retention after 300 cycles. Han et al. constructed a LiF‐rich (>80%) SEI layer on the Li₃P surface using a locally high‐concentration electrolyte (LiFSI─triethyl phosphate/1,1,2,2‐tetrafluoroethyl‐2,2,2‐trifluoroethyl ether), enabling the Li₃P||S full cell to achieve a capacity retention of 97.1% after 600 cycles with an average CE greater than 99% (Figure 10f).^{[ 158 ]} Although the voltage platform of the current P─S full cell is limited to between 1.7 and 2.0 V, the high specific capacity characteristics of S and P, combined with their Earth abundance (0.05% and 0.12% in the crust, respectively), make this system a promising candidate for the next generation of sustainable batteries. Table 7 presents examples of full cells featuring different prelithiated anodes paired with Li‐free cathodes, along with their corresponding battery performance.

Table 7.

The summary of prelithiated anode||Li‐free cathode full cells.

Prelithiated anode	Full cell	ICE	Cycle life (number)	Capacity retention	Refs.
LixC	S/KB||LixC	≈100%	400	≈60%	[155]
LiC6	FeS2||LiC6	≈85%	300	72%	[156]
LiC6	MoS6||LiC6	≈69%	300	≈81%	[156]
LiC6	VS4||LiC6	≈89%	300	≈55%	[156]
LixSi	S||LixSi	≈107%	100	80%	[157]
LixSi/graphene	S/C||LixSi/graphene	≈100%	110	≈80%	[13]
LixSi/graphene	V2O5||LixSi/graphene	≈99%	200	≈93%	[13]
LixP	S/C||LixP	≈112%	300	68%	[63]
Li3P	S||Li3P	≈100%	600	97%	[158]

In summary, the combination of prelithiated anodes and Li‐free cathodes creates a new architecture for high‐energy full cells. The three types of prelithiated anode materials are positioned for differentiated applications based on their intrinsic characteristics: C‐based systems focus on process maturity and cycling stability, Si‐based systems aim for extreme capacity characteristics, and P‐based systems concentrate on fast ion transport and fast‐charging scenarios. Future research on these full cells will focus on overcoming core challenges such as the low loading and sluggish kinetics of Li‐free cathodes, the air instability of prelithiated anodes, and the low voltage platform limitations of Li_xP‐based full cells.

6. Prelithiation Strategies for ASSLIBs

ASSLIBs have emerged as a frontier technology in energy storage owing to their intrinsic safety from the elimination of flammable liquid electrolytes.^{[ 161 ]} However, parasitic reactions at the solid‐state electrolyte/electrode interface coupled with irreversible volumetric fluctuations of Li metal collectively accelerate irreversible Li loss, rendering the optimization of ICE a pivotal prerequisite for practical implementation.^{[ 16 ]} Moreover, specific electrode fabrication protocols for ASSLIBs—such as solvent‐free dry‐film processing—and cell integration techniques like high‐pressure stacking pose substantial constraints on the applicability of conventional prelithiation strategies matured in liquid electrolyte systems.^{[ 162 ]} For instance, the absence of solvent wettability in dry electrodes hinders uniform dispersion of prelithiation agents, while the rigid interfacial contact in solid‐state systems demands precise kinetic compatibility for Li source activation. Studies reveal that in identical Si‐based systems, liquid cells achieve an ICE of 78.3%, whereas ASSLIBs typically exhibit ICE values below 60% due to restricted interfacial Li transport and low active material utilization.^{[ 16} , ^{163 ]} This discrepancy has driven the development of ASSLIBs‐specific prelithiation strategies, with the dual objectives of replenishing Li inventory and reconstructing multiscale electron/ion transport networks within electrodes. Currently, anode prelithiation predominantly focuses on Li─Si alloys, while cathode prelithiation relies on Li‐containing coatings, synergistically advancing ASSLIBs toward practical viability.

The design of anode prelithiation must focus on two key aspects: Li source supplementation and interfacial stabilization.^{[ 164 ]} Prelithiated Si significantly enhances the cycling stability and rate capability of the ASSLIBs by compensating for Li loss, improving electron/ion conductivity, and optimizing stability of structures and interfaces. This approach resolves the intertwined challenges of ion transport limitations and volume effects in Si‐based anodes (Figure 11a).^{[ 16 ]} Studies reveal that the electron/ion conduction properties of Li─Si alloys are intrinsically linked to their lithiation degree. For instance, Li₂Si exhibits a five‐order‐of‐magnitude increase in electronic conductivity (10 S cm⁻¹, 25 °C) compared to pristine Si (10⁻⁴ S cm⁻¹, 25 °C).^{[ 16 ]} However, ionic conductivity does not scale linearly with Li concentration: Li_2.2Si demonstrates optimal ion transport efficiency (≈4 × 10⁻³ S cm⁻¹, 25 °C) when interfaced with sulfide electrolytes, while highly lithiated phases such as Li₁₅Si₄ or Li₂₁Si₅ suffer from reduced diffusivity due to Li‐dense packing (Figure 11b).^{[ 165 ]} These phase‐dependent variations highlight the necessity for precise prelithiation control, requiring a balance between Li concentration gradients and the construction of percolation pathways. Prelithiated Si further stabilizes interfacial chemistry by suppressing sulfide electrolyte decomposition. Electrochemical degradation occurs continuously at the Si─Li₆PS₅Cl solid–solid interface. X‐ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry confirm that the components in the SEI layer include decomposition products of Li₆PS₅Cl (Li₃P, Li₂S, and LiCl) as well as components derived from SiO_x on the Si surface (SiO₂, Li_xSiO_y, and Li₂O). These multiphase components cause the interfacial impedance to increase with each cycle.^{[ 165 ]} Prelithiated Si forms Li_xSiO_y by reducing SiO_x species in advance, which prevents the decomposition of Li₆PS₅Cl and achieves chemical passivation of the interface. EIS analysis of the Li₂Si||Li₆PS₅Cl||Li₂Si symmetric cell confirms that the electrolyte bulk impedance dominates the total cell impedance (R = 30.1Ω), while the contribution of the prelithiated Si interface is below 2 Ω.^{[ 16 ]} Leveraging these advancements, LCO||Li₂Si full cells achieve an ICE of 95.7% (vs 78.3% for pristine Si) and a high areal capacity of 10 mAh cm⁻² (equivalent to 236 Wh kg⁻¹) through optimized charge transfer mechanisms.^{[ 16 ]}

Figure 11.

Strategies for anode prelithiation in ASSLIBs. a) Radar chart comparing various electrochemical performance metrics of Si anodes and prelithiated Si anodes in ASSLIBs.^{[ 16 ]} b) Ionic conductivity of prelithiated Si anodes in different lithiation states reveals the optimal Li content for solid‐state operation.^{[ 165 ]} c) Li_4.4Si serves as both a Li reservoir and an interfacial layer between the Si anode and solid electrolyte.^{[ 166 ]} d) 3D bicontinuous Li⁺/e⁻ conductive networks constructed through Li₁₅Si₄/LiC₆ composites accelerate anode kinetics by synergizing Li alloy and graphite phases.^{[ 167 ]} e) Schematic of a LCO||prelithiated Si full cell configuration tailored for solid‐state architectures.^{[ 168 ]} f) Schematic of the in situ prelithiation strategy for electrolyte‐free Si anodes.^{[ 163 ]} (a) Reproduced with permission.^{[ 16 ]} Copyright 2024, Springer Nature. (b) Reproduced with permission.^{[ 165 ]} Copyright 2024, Springer Nature. (c) Reproduced with permission.^{[ 166 ]} Copyright 2024, Wiley‐VCH. (d) Reproduced with permission.^{[ 167 ]} Copyright 2023, Springer Nature. (e) Reproduced with permission.^{[ 168 ]} Copyright 2023, Royal Society of Chemistry. (f) Reproduced with permission.^{[ 163 ]} Copyright 2023, Elsevier.

From traditional binary alloys to multifunctional composite systems, the design of prelithiated Si anodes is transitioning from functional specificity to collaborative optimization. Solid‐state NMR and phase‐field simulations have elucidated the heterogeneous distribution of Li accumulation at the electrode/electrolyte interface in ASSLIBs. Since highly lithiated phases (such as Li_4.4Si) are incapable of accommodating additional Li, the accumulation of excess Li migrating from the cathode may pose a risk of dendrite formation. To mitigate this issue, the Li_4.4Si/Si composite anode leverages the advantages of functional partitioning: the upper layer of Li_4.4Si compensates for Li losses during the cycling process, and its low Young's modulus (0.89 GPa) effectively mitigates expansion‐induced interfacial damage; the bottom Si layer functions as a buffer reservoir for excess Li, preventing dendrite formation due to local Li oversaturation (Figure 11c).^{[ 166 ]} This hierarchical architecture realizes compatibility with sulfide electrolytes at high areal capacities (5.22 mAh cm⁻²), achieving a groundbreaking cell‐level energy density of 303.9 Wh kg⁻¹. Furthermore, bicontinuous conductive networks (LiC₆/Li₁₅Si₄) formed via in situ electrochemical sintering of composite Si/hard carbon particles enhance electronic conductivity by nearly six orders of magnitude (0.87 S cm⁻¹, 55 °C) (Figure 11d).^{[ 167 ]} During cycling, Li₁₅Si₄ exhibits superior plastic deformability (hardness ≈1.3 GPa) compared to rigid pure Si (>10 GPa), while the high specific surface area of hard carbon provides anchoring sites for uniform Li deposition. These features collectively suppress crack propagation induced by Si expansion (electrode volume change ≈10%). However, it is important to recognize that volume changes for different alloy phases during the Li insertion/extraction process can induce redistributions of interfacial stresses.

The breakthrough at the full cell level substantiates the engineering viability of prelithiation technology. A synergistic approach that integrates Li₂₁Si₅/Si composite anodes with high‐loading LCO cathodes (21.1 mg cm⁻²) achieves a record areal capacity of 17.9 mAh cm⁻², along with 66.7% capacity retention after 1000 cycles at 55 °C and 1C charge capability (Figure 11e).^{[ 168 ]} In situ transmission electron microscope confirmed interfacial fusion between Li₂₁Si₅ and Si particles, forming stable ion/electron channels that facilitate Li⁺ transport. Figure 11f illustrates the successful implementation of a direct contact prelithiation strategy in ASSLIBs.^{[ 163 ]} By introducing an ultrathin Li foil (10 µm) between a self‐supported Si film (97.5% Si content) and a copper current collector, spontaneous Li─Si alloying is triggered under a stack pressure of 300 MPa, leading to the precise formation of Li_0.85Si phase. This approach achieves a breakthrough in battery energy density of 402 Wh kg⁻¹ (based on total electrode mass), demonstrating a broad range of temperature adaptability from −30 to 50 °C.

It is crucial to emphasize that anode prelithiation is significant only in configurations where the anode, rather than the cathode, represents the limiting factor for improving ICE of ASSLIBs. For example, the ICE of NCM811||prelithiated Si full cell increases only marginally from 72.5% to 73.7%, with this small change being limited by the intrinsically low ICE of NCM811 (75%).^{[ 16 ]} Consequently, developing cathode prelithiation technology for ASSLIBs is essential to address both the loss of active Li in the cathode and issues related to interfacial degradation. As cathode prelithiation additives, Li₃N and Li₃P facilitate Li compensation through sacrificial decomposition. Li₃N decomposes into Li and N₂ during charging (2Li₃N → 6Li⁺ + N₂ + 6e⁻), and its high Li content (theoretical capacity ≈2309 mAh g⁻¹) significantly enhances the ICE of the full cell (Figure 12a).^{[ 169 ]} However, the release of N₂ gas may lead to swelling issues in the battery. By contrast, Li₃P releases a prelithiation capacity of 983 mAh g⁻¹ via a delithiation reaction (Li₃P → 3Li⁺ + P + 3e⁻), and its mixed ionic–electronic conductive properties (both ionic and electronic conductivity >10⁻⁴ S cm⁻¹, 25 °C) eliminate the need for additional conductive agents, thereby avoiding side reactions between carbon‐based additives and sulfide electrolytes (Figure 12b). Experiments show that adding 5 wt% Li₃P reduces the first‐cycle capacity loss of the LCO||graphite full cell from 27.7% to 15% and maintains 84% capacity retention after 200 cycles.^{[ 170 ]} Although the inert interface layer formed by phosphorus from the delithiation product further suppresses electrolyte decomposition, only 63.4% of the Li₃P capacity is released in the first cycle, likely due to the phosphorus shell impeding internal reactions.

Figure 12.

Strategies for cathode prelithiation in ASSLIBs. a) Schematic representation of ASSLIBs with Li₃N prelithiation additive during the charging process.^{[ 169 ]} b) Synthesis pathway for the Li₃P cathode prelithiation additive.^{[ 170 ]} c) Li₂O‐prelithiated NCM811 cathode design.^{[ 171 ]} d) Comparison between ASSLIBs with bare NCM811 (left) and Li₅FeO₄‐coated NCM811 (right). In addition to supplying Li to the full cell, the coated prelithiation agent serves as a protective layer, effectively suppressing decomposition and degradation of both the cathode and solid‐state electrolyte materials.^{[ 17 ]} (a) Reproduced with permission.^{[ 169 ]} Copyright 2024, Wiley‐VCH. (b) Reproduced with permission.^{[ 170 ]} Copyright 2021, Wiley‐VCH. (c) Reproduced with permission.^{[ 171 ]} Copyright 2023, Wiley‐VCH. (d) Reproduced with permission.^{[ 17 ]} Copyright 2023, Wiley‐VCH.

The innovation of prelithiation coatings integrates Li compensation with interface protection functions, making it a crucial strategy for enhancing the stability of cathodes under high voltage. Amorphous Li₂O coatings (≈5 nm) are uniformly applied to the surface of small‐sized single‐crystal NCM811 through high‐temperature calcination, providing an additional Li source (improving ICE to 82.7%) and serving as a physical barrier to suppress the oxidative decomposition of Li₆PS₅Cl electrolytes (Figure 12c). In 4.5 V high‐voltage cycling, this coating improves the capacity retention of NCM811 from 57.6% (uncoated) to 100% after 200 cycles, with the interface impedance reduced by 83% (19.6 vs 117.1 Ω).^{[ 171 ]} Similarly, Li₅FeO₄ coatings are uniformly applied to the surface of NCM811 via ball milling (Figure 12d). They serve as prelithiation agents, releasing 709.5 mAh g⁻¹ of Li during the first charge to compensate for Li loss. Meanwhile, they function as interfacial protection layers, reducing Li₆PS₅Cl decomposition by over 50% and suppressing phase transition from layered to rock‐salt structure. The Li₅FeO₄‐coated NCM811||Si pouch cell achieves an energy density of 440 Wh kg⁻¹, validating the suitability of this coating design for high‐energy‐density systems.^{[ 17 ]} Table 8 summarizes the performance of full cells after anode or cathode prelithiation treatments in ASSLIBs. Compared to the focus on additive decomposition potential and residue management in liquid systems, the cathode prelithiation strategy for ASSLIBs emphasizes enhancing Li release kinetics and optimizing interface stability. This provides a unique design approach to address interfacial side reactions and Li transport barriers in high‐nickel cathodes within solid‐state LIB systems.

Table 8.

The summary of prelithiation in ASSLIBs.

Anode prelithiation	Full cell	ICE	Cycle life (number)	Capacity retention	Refs.
Li1Si	LCO||Li1Si	96%	1000	74%	[16]
Li1Si	NCM811||Li1Si	86%	1000	84%	[172]
Li0.85Si	NCM811||Li0.85Si	82%	300	57%	[163]
Li4.4Si─Si	NCM811||Li4.4Si─Si	78%	400	70%	[166]
Li21Si5─Si	LCO||Li21Si5─Si	98%	1000	67%	[168]
Li15Si4─LiC6	NCM811||Li15Si4─LiC6	82%	5000	62%	[167]
Li─Si/graphite	LCO||Li─Si/graphite	85%	200	85%	[173]
LiSi	FeOS||LixSi	86%	2000	84%	[174]
LixC	NCM811||LixC	–	600	79%	[175]
Li0.4Al	LiNi0.83Co0.12Mn0.05O2||Li0.4Al	84%	2000	100%	[176]

Cathode prelithiation	Full cell	Increase in discharge capacity [mAh g−1]	Cycle life (number)	Capacity retention	Refs.
Li3N	NCM||In	≈10	200	76%	[169]
Li3P	LCO||graphite	≈35	100	81%	[170]
Li2O	NCM811||Li─In	–	200	100%	[171]
Li5FeO4	NCM811||In	25	50	83%	[17]

The development of prelithiation technology for ASSLIBs is more urgent than for liquid systems. Its core challenges stem from Li compensation kinetics hysteresis caused by rigid solid‐state interface contact, as well as stricter requirements for the uniform introduction of Li sources due to dry electrode preparation processes. In the future, it will be essential to promote the development of prelithiation agents with high ionic conductivity and low cost, while focusing on prelithiation strategies that are specifically adapted to ASSLIB manufacturing processes, such as dry‐film formation, high‐temperature sintering, and multilayer stacking.

7. Challenges and Perspectives

Prelithiation technology has emerged as a critical strategy to address the challenges of low ICE and cycling performance degradation in LIBs by actively compensating for irreversible Li loss. This review systematically summarizes prelithiation approaches for both liquid and solid‐state LIB systems, encompassing the synergistic optimization of anode, cathode, electrolyte, binder, and current collector components. It also discusses the structural paradigms for innovative full cells based on prelithiated anodes and Li‐free cathodes. Finally, the role of prelithiation in ASSLIBs is clarified, focusing on its contribution to active Li compensation, interface stability, and the construction of Li⁺ transport networks.

Anode prelithiation, achieved through Li source additives (e.g., Li metal, Li alloys) or chemical reagents, effectively mitigates irreversible Li loss during SEI formation and cycling, markedly improving the ICE (>95%) and cycling stability of high‐capacity anodes such as Si‐based materials. However, surface protective layers designed to enhance the air stability of prelithiation agents, while inhibiting Li oxidation, hinder Li⁺ transport due to their extremely low ionic/electronic conductivity (e.g., the ionic conductivity of LiF is <10⁻¹⁰ S cm⁻¹), leading to reduced active Li utilization and sluggish interface reaction kinetics. Furthermore, although current prelithiation agents exhibit adequate stability in dry air (dew point <−40 °C), the passivation layers readily react with water molecules under conventional humidity conditions (>40% RH), forming insulating LiOH/Li₂CO₃ and necessitating ultralow dew point manufacturing environments (increasing costs by 30–50%). A more pressing challenge arises from solvent compatibility issues: current prelithiation agents such as SLMP and Li alloys are incompatible with NMP solvent. These challenges hinder the integration of the prelithiation process into mainstream electrode manufacturing workflows. Future advancements must focus on three key directions: i) designing “adaptive passivation layers,” such as dynamic hydrophobic/lithiophilic interfaces that form dense protective layers during storage via humidity‐responsive mechanisms and controllably decompose during battery activation; ii) developing hydrostable prelithiation agents (e.g., organic lithium salts^{[ 39 ]}) that leverage hydrogen bonding between lithium carboxylate (─COOLi) and aqueous binders (e.g., PAA) to achieve slurry compatibility; iii) advancing dry‐process in situ prelithiation techniques that introduce Li sources via solvent‐free methods and activate Li penetration through roll pressing, circumventing polar solvent limitations and reducing manufacturing costs.

The core advantages of cathode prelithiation agents lie in their exceptional stability and high compatibility with existing electrode manufacturing processes, enabling seamless integration into commercial production lines. However, their practical application faces three critical bottlenecks. First, the capacity disadvantage: compared to anode prelithiation agents (e.g., SLMP >3000 mAh g⁻¹), cathode systems such as Li‐rich transition metal oxides (e.g., Li₂NiO₂, Li₅FeO₄) generally exhibit specific capacities below 800 mAh g⁻¹, necessitating high additive loadings to compensate for Li loss in Si‐based anodes. The accumulation of inactive byproducts (e.g., residual Li₂O, metallic species) progressively blocks Li⁺ transport channels and triggers transition metal (e.g., Ni, Fe) dissolution, resulting in cumulative interfacial impedance. Second, gas evolution risks: although sacrificial Li compounds (e.g., Li₂C₂O₄, Li₂C₄O₄) can satisfy the Li replenishment requirements of batteries at low loadings (<5 wt%), they generate gaseous byproducts (e.g., CO₂, CO) during decomposition, which induce electrode structural swelling or microcracks. This necessitates staged pressurized venting protocols during battery formation to achieve directional gas evacuation. Third, system compatibility barriers: ultrahigh‐capacity materials like Li₂S exhibit negligible practical utility due to insulating decomposition products, moisture sensitivity, and severe side reactions with carbonate‐based electrolytes, effectively excluding them from mainstream solutions. Future research could integrate artificial‐intelligence‐assisted high‐throughput screening of prelithiation agents, using machine‐learning‐driven design of composite structures for prelithiation agents (such as oxygen vacancy creation or element doping) to steer decomposition products toward high ionic conductivity phases (e.g., Li₃PO₄). Concurrently, gas–solid interface coregulation technologies must be developed, leveraging micrometer‐scale porous electrode architectures and dynamic pressure management systems to enable in situ gas adsorption and directional emission, minimizing gas‐induced swelling. More importantly, it is imperative to establish a full‐cell‐level multiscale dynamic evaluation system for prelithiation. By integrating in situ electrochemical–mechanical coupling characterization techniques, this system will enable systematic quantitative analysis of Li compensation efficiency, electrode structural stability, and interfacial chemical evolution in prelithiated cathodes and anodes. Such an evaluation framework will facilitate engineering validation, ranging from coin cells to Ah‐scale pouch cells, thereby driving the large‐scale implementation of the prelithiation technology.

Prelithiation technology has emerged as a critical enabler for the practical deployment of solid‐state batteries by precisely compensating active Li loss and reconstructing ion transport networks at the electrode/electrolyte interface. Current research focuses on the dual‐functional design of “in situ compensation and interface adaptation” for Li─Si alloy anodes and the synergistic optimization of “Li compensation and electrochemical compatibility” for cathode interface modification layers. This has successfully achieved a technological leap from a single Li source supplementation to the construction of multiscale ion/electron collaborative transport networks. However, the solid–solid interface characteristics and the dry processing technologies in ASSLIBs, which render traditional liquid prelithiation strategies ineffective, necessitate the development of new principles and methods through coordinated advancements in transport mechanism optimization and large‐scale process innovation.

At the interface ionic transport level, the key issue to address is the dynamic matching of anode evolution with ion/electron transport pathways. Structural reconstruction during lithiation/delithiation processes can lead to localized stress concentration and interface contact failure. For example, in Li─Si alloys, ion transport barriers at heterophase interfaces may accumulate with increased cycling. Future research should reveal the Li⁺ cross‐phase transport mechanisms in composite electrodes through multiscale simulations and in situ characterization under operando conditions. Design strategies such as gradient lithiation phase distribution or adaptive conductive networks should be explored to maintain continuous transport pathways during dynamic cycling. At the device integration level, overcoming process bottlenecks in the uniform dispersion and large‐scale manufacturing of solid‐state prelithiation agents is essential. For instance, the liquid immersion method fails completely in dry electrodes. This necessitates the development of new technologies like dry mechanical fusion, in situ electrochemical sintering, or Li gas‐phase deposition to achieve uniform distribution of Li sources within the electrodes. Meanwhile, electrode structure distortion caused by high‐pressure stacking processes should be addressed through innovative designs, such as 3D porous frameworks or stress‐buffering interlayers, to synergistically regulate the uniformity of prelithiation reagents distribution and interface mechanical stability. It is also important to emphasize that, at the full cell level, prelithiation needs to balance the dynamic matching of anode and cathode kinetics with the spatial distribution of Li sources. Overlithiation of a single electrode should be avoided to prevent exacerbating interface side reactions or increasing the risk of Li dendrite growth. This requires establishing cross‐scale prelithiation quantification criteria and full life‐cycle management strategies, offering solutions for breakthroughs in performance and manufacturing paradigm innovations for high‐energy ASSLIBs.

The successful implementation of prelithiation technology has established a critical paradigm for the premetallation of other metal‐ion battery systems, including sodium‐, potassium‐, and magnesium‐ion batteries. Nevertheless, the core challenge in transferring this technology arises from the intrinsic differences between the target metal ions (Na⁺, K⁺, Mg²⁺) and Li⁺. Presodiation technology can compensate for the first‐cycle capacity loss through the use of sodium metal powder or chemical presodiation methods (e.g., Na─Naphthalene complexes).^{[ 177 ]} However, the large ionic radius of Na⁺ (1.02 vs Li⁺ 0.76 Å) significantly increases the steric hindrance during its diffusion within anode materials, severely constraining both the depth and efficiency of presodiation.^{[ 178 ]} Furthermore, typical cathode additives (e.g., Na₂C₂O₄, NaCO₂CH₃) release gases like CO during decomposition while supplementing sodium, and this unintended gas release triggers electrode swelling and interface degradation.^{[ 3} , ^{179 ]} Prepotassiation technology faces the primary challenge of uncontrollable potassium dendrite formation, which poses significant safety hazards.^{[ 180 ]} Consequently, controlling the uniformity and extent of prepotassiation is far more demanding than that of prelithiation. Potassium's remarkably soft and viscous texture complicates direct contact with the electrode during prepotassiation. Furthermore, the strong reducing nature of potassium necessitates that prepotassiation reagents, such as K─Naphthalene complexes, be meticulously isolated from both air and moisture throughout electrode processing and storage, which further escalates the safety risks involved.^{[ 181 ]} Premagnesiation technology faces fundamental challenges related to multivalent ion transport. Although the multicharged nature of Mg²⁺ provides a high theoretical specific capacity, its strong Coulombic interactions make desolvation difficult in premagnesiation solutions and result in high energy barriers for diffusion in electrode materials.^{[ 182 ]} This requires the reconstruction of ion transport pathways during premagnesiation processing, weakening the solvation structure of Mg²⁺ and constructing highly conductive Mg²⁺ interface layers to synergistically optimize interfacial migration dynamics.

Therefore, breakthroughs in the following areas are required for the future development of presodiation, prepotassiation, or premagnesiation technologies. For sodium‐ion systems, it is crucial to develop new presodiation additives with high stability and minimal gas release, as well as to thoroughly investigate the optimization mechanisms of diffusion dynamics for large‐sized Na⁺ in electrode materials. For potassium‐ion systems, the focus should be on designing prepotassiation artificial interfaces that effectively suppress dendrite growth, while exploring safe chemical prepotassiation or solid‐state prepotassiation processes. In magnesium‐ion systems, the core challenge of premagnesiation technology is to reconstruct the solvation sheath and develop high‐conductivity Mg²⁺ interface channels to enable rapid Mg²⁺ transport from external magnesium sources to the electrode material. Given the above system‐specific challenges and optimization strategies, there is an urgent need to establish a universal theoretical framework for premetallation. This framework should quantify the dynamic relationship between metal ion radius, reactivity, capacity, and premetallation efficiency, thus providing rational design guidelines that link atomic‐scale characteristics to macroscopic electrode performance. Such a framework would systematically guide the development of high‐stability premetallation agents and facilitate the transition of lithium‐, sodium‐, potassium‐, and magnesium‐ion batteries from laboratory innovations to practical engineering applications.

Conflict of Interest

The authors declare no conflict of interest.

Biographies

Junyu Hou is a Postdoctoral Researcher at the Department of Materials Science, Fudan University. He received his Ph.D. degree from the Beijing University of Aeronautics and Astronautics in 2022. His research focuses on the synthesis and characterization of composite solid‐state electrolytes.

Jie Zhao is an Associate Professor at the Department of Materials Science, Fudan University. She received her Ph.D. degree from the Department of Materials Science and Engineering, Stanford University in 2018. She worked as a Postdoctoral Fellow at the Center for Bio‐Integrated Electronics at the Northwestern University from 2018 to 2020. She is mainly engaged in the research of high‐capacity anode materials and prelithiation reagents for next‐generation secondary batteries.