Harnessing structural reconstruction to enhance the electrochemical stability and performance of VS₂ for aqueous zinc-ion storage

Summary

Layered VS₂ with large interlayer spacing and high conductivity is a promising cathode for aqueous zinc-ion batteries (AZIBs) but suffers from structural instability. Here, a VS₂/MnS hybrid is designed to stabilize the VS₂ framework through electrochemically induced structural reconstruction. Rietveld refinement of neutron diffraction data confirms the coexistence of hexagonal 1T-VS₂ and cubic MnS, with VS₂ as the dominant phase. Operando synchrotron radiation X-ray diffraction reveals gradual MnS dissolution during the first charge and limited Mn incorporation into VS₂, forming a stable Mn-intercalated phase (VS₂-Mn). X-ray absorption spectroscopy and density functional theory demonstrate that VS₂-Mn exhibits improved structural stability, electrical conductivity, and electron-transfer capability. Benefiting from this reconstruction, the VS₂-Mn electrode delivers a high capacity of 297.9 mAh g⁻¹ at 0.1 A g⁻¹, outstanding cycling stability (78.6% after 3,000 cycles at 10 A g⁻¹), and excellent rate capability. This study highlights structural reconstruction as an effective route to design advanced AZIB cathodes.

Graphical abstract

Highlights

• •Electrochemically induced reconstruction stabilizes layered VS₂ cathode
• •Neutron and synchrotron radiation X-ray diffraction reveal Mn incorporation into VS₂ framework
• •Mn-intercalated VS₂ exhibits enhanced conductivity and structural robustness
• •Reconstructed VS₂-Mn electrode exhibits excellent rate performance and cycling stability

Energy engineering; Energy systems; Energy storage

Introduction

Amid the escalating global energy crisis and growing environmental concerns, the development of sustainable and eco-friendly energy storage technologies has become an urgent scientific priority.^1,2 Lithium-ion batteries (LIBs), with their high energy density, elevated output voltage, and low self-discharge rate, have dominated the commercial energy storage market.^3,4 However, the scarcity of lithium resources, rising production costs, and inherent safety issues severely constrain their large-scale deployment. Therefore, identifying alternative systems that are safe, cost-effective, and high-performing is of paramount importance.^5,6 Among various candidates, aqueous zinc-ion batteries (AZIBs) have attracted considerable attention owing to their intrinsic merits, including a low redox potential (−0.76 V vs. SHE), high theoretical specific and volumetric capacities (820 mAh g⁻¹ and 5,855 mAh cm⁻³, respectively), inherent safety, and low cost.^7,8 Nevertheless, the strong electrostatic interaction between divalent Zn²⁺ and host lattices often causes sluggish ion diffusion and structural degradation of cathode materials, resulting in limited capacity retention and poor reversibility.^9,10 Consequently, developing structurally stable and Zn²⁺-compatible cathodes with high electronic and ionic conductivity is critical for advancing the practical performance of AZIBs.

Layered transition-metal dichalcogenides such as MoS₂, WS₂, and VS₂ have emerged as promising cathode candidates due to their two-dimensional architectures, tunable electronic structures, and efficient ion transport.^11,12 In particular, VS₂ offers large interlayer spacing (5.76 Å vs. 3.35 Å for graphite) and weaker electrostatic interaction with Zn²⁺, enabling rapid and reversible ion intercalation.^13,14,15 Nevertheless, the practical application of VS₂ is still limited by the insufficient number of active sites, short ion-diffusion paths, and significant volume fluctuations during cycling, all of which led to rapid capacity fading.¹⁶

To overcome the intrinsic structural fragility and sluggish Zn²⁺ transport kinetics of pristine VS₂, compositional modification represents an effective route to improve its electrochemical reversibility and conductivity. Introducing manganese sulfide (MnS), a transition metal sulfide with high theoretical capacity, good chemical stability, and comparable chalcogen environment, is expected to buffer the lattice strain of VS₂ and accelerate charge transfer. Herein, VS₂/MnS composite were synthesized through a one-step hydrothermal method and investigated as cathodes for AZIBs. Rietveld refinement of neutron powder diffraction (NPD) confirmed the coexistence of hexagonal 1T-VS₂ and cubic MnS, with VS₂ as the dominant phase. Operando synchrotron radiation X-ray diffraction (SRXRD) together with ex situ synchrotron radiation soft X-ray absorption spectroscopy (sXAS) revealed that the composite undergoes a distinct structural reconstruction during the initial electrochemical cycles, leading to the formation of Mn-intercalated VS₂ (VS₂-Mn). This reconstructed phase enhances structural stability and facilitates electron transport, thereby contributing to improved electrochemical performance. The VS₂-Mn electrode delivers a high specific capacity of 297.9 mAh g⁻¹ at 0.1 A g⁻¹, retains 94.8% of its specific capacity after 2,000 cycles at 5 A g⁻¹, and maintains 78.6% specific capacity retention even after 3,000 cycles at 10 A g⁻¹, along with remarkable rate capability. These results demonstrate that electrochemically induced reconstruction provides an effective pathway for designing AZIB cathodes with high capacity, long cycle life, and superior rate performance.

Results and discussion

Structure self-optimization

By a one-step hydrothermal method, we synthesized VS₂/MnS hybrid materials (see experimental section for details). As shown in Figure S1, the X-ray diffraction (XRD) peaks can be well indexed to cubic MnS (JCPDS card no. 01-072-1534) and hexagonal VS₂ (JCPDS card no. 00-036-1139). Remarkably, the diffraction pattern of the composite exhibits the characteristic diffraction peaks of both phases without detectable impurities. To further determine the unit-cell parameters and phase fractions, Rietveld refinement of the NPD data was performed (Figure 1A). As summarized in Table S1, the refinement confirms that the VS₂ phase in VS₂/MnS crystallizes in the 1T-type layered structure (space group, P—3m1), where V atoms reside at octahedral sites coordinated by six S atoms, with refined lattice parameters of a = b = 3.21762(9) Å and c = 5.7623(5) Å. In contrast, the MnS phase adopts a rock-salt-type cubic structure (space group, Fm—3m), in which each Mn atom is octahedrally coordinated by six S atoms, with a lattice parameter of a = b = c = 5.20812(4) Å. Specifically, quantitative phase analysis shows that VS₂ is the dominant phase in the composite, accounting for 70.5(9) wt. %, while MnS contributes 29.5(6) wt. %. The scanning electron microscopy (SEM) images reveal that the VS₂ in the VS₂/MnS mixture retains its original flower-like shape, whereas MnS has transformed from its original nanoparticle form into nanocubes (Figures S2–S4). Elemental mapping (Figure S5) further demonstrates that V and Mn signals are spatially separated, with V concentrated in the VS₂ domains and Mn in the MnS regions, confirming the phase-segregated nature of the composite. More importantly, an electrochemical strategy was adopted to induce structural reconstruction in VS₂/MnS by expanding the operating voltage window from 0.3–1.5 V to 0.1–1.7 V (Figure S6). Within the narrower voltage window, the reaction is mainly limited to reversible Zn²⁺ intercalation/deintercalation with negligible structural change. In contrast, extending the window introduces stronger reduction and oxidation conditions, promoting V-S bond rearrangement and Mn oxidation, which collaboratively trigger the reconstruction of VS₂/MnS into a more stable and kinetically favorable framework.¹⁷

Figure 1.

Analysis of crystal structure evolution for the VS₂/MnS electrode

(A) Refined NPD pattern collected at 300 K of VS₂/MnS.

(B) Operando SRXRD patterns collected during the first discharge-charge-discharge cycle, together with the corresponding voltage profile (right).

(C) Plots of operando SRXRD diffraction intensity evolution in the 32°–36° range and (D) in the 47.5°–50° range.

(E) XRD patterns at full charge/discharge for different numbers of cycles.

To elucidate the structural evolution of the VS₂/MnS electrode, operando SRXRD was employed to monitor the reconstruction process in real time during the first charge-discharge cycle. As shown in Figure 1B, the VS₂ diffraction peaks shift toward lower angles upon the first discharge, indicative of Zn²⁺ insertion into the interlayers and the consequent lattice expansion. In contrast, the MnS diffraction peaks remain nearly unchanged in position (Figures 1B–1D), suggesting that the MnS lattice parameters vary only slightly and that its crystal framework remains relatively stable during cycling. However, the intensity of these peaks gradually decreases during discharge and exhibits a noticeable drop at a specific voltage during charge. Combined with the slight shifts in Mn 2p binding energies and the appearance of Zn 2p signals in the X-ray photoelectron spectroscopy (XPS), these results indicate limited Zn²⁺ incorporation or surface ion exchange within MnS, rather than significant lattice expansion or complete cation substitution (Figure S7). During the subsequent charge, the VS₂ diffraction peak remains nearly unchanged in position, while a slight variation in intensity can still be observed around 0.87 V. Meanwhile, the MnS peak intensity continues to decrease at this stage (Figures 1C and 1D), implying progressive structural degradation or partial dissolution of MnS during cycling. In the second discharge, VS₂ diffraction peaks again shift to lower angles due to Zn²⁺ reinsertion, whereas MnS diffraction peak intensities continue to decline. After the third discharge, the MnS signature almost vanish in the XRD patterns (Figure 1E), indicating that MnS no longer exists as an independent phase but is partially incorporated into the VS₂ lattice, thereby reconstructing into Mn-intercalated VS₂ (VS₂-Mn). The (001) diffraction peak correspondingly shifts from 15.7° to 15.55° (Figure S8), further confirming the lattice expansion after structural reconstruction. Based on the Mn K-edge X-ray absorption near edge structure (XANES) at different states, the Mn oxidation state in the fully discharged state of the first cycle is similar to that of commercial MnS (+2). After subsequent cycles, the pre-edge peak gradually shifts toward higher energy, indicating an increase in the Mn oxidation state (Figure S9). Combined with the operando SRXRD results, this transition corresponds to the collapse of the MnS lattice and the formation of VS₂-Mn during the structural reconstruction process. Inductively coupled plasma analysis corroborates the incorporation of a small amount of Mn after third cycles (Table S2). Meanwhile, the formation energy of VS₂-Mn (Table S3) is calculated to be negative in combination with density functional theory (DFT) calculations, confirming the thermodynamic feasibility of Mn intercalation. Moreover, SEM elemental mapping collected during the first three cycles directly visualizes the gradual loss of Mn. The presence of elemental Mn can still be detected during the first two cycles but become nearly undetectable by the third (Figure S10), in agreement with the XRD observations.

Electrochemistry

To investigate the storage behavior of Zn²⁺ in reconstructed VS₂-Mn, the electrochemical performance of VS₂-Mn was evaluated using coin cells (consisting of a VS₂-Mn cathode, a 3 M Zn(CF₃SO₃)₂ electrolyte, and a Zn foil anode). As shown in Figure 2A, the cyclic voltammetry (CV) curves were recorded within a voltage window of 0.1–1.7 V (vs. Zn/Zn²⁺) at the scan rate of 0.1 mV s⁻¹. In the first CV scan, multiple redox peaks are observed, among which the anodic feature at ∼1.5 V disappears in subsequent cycles, indicating the irreversibility of the corresponding oxidation process. The CV curves for the 2^nd and 3^rd cycles do not completely coincide, suggesting that they are undergoing a process of structural self-optimization.^18,19 Thereafter, three redox peak pairs at 0.69/0.78 V, 0.93/1.07 V, and 1.08/1.17 V overlap well during the subsequent 5^th and 6^th cycles (Figure S11), highlighting the establishment of highly reversible electrochemical Zn²⁺ storage. The galvanostatic charge-discharge profiles further corroborate the CV results (Figure 2B). Benefiting from the irreversible transformation that occurs during the first charge, the optimized structure is more conducive to storing Zn²⁺, resulting in the VS₂-Mn electrode exhibiting excellent electrochemical performance. Figure 2C displays the rate performance of Zn||VS₂-Mn cells at 0.1 to 5.0 A g⁻¹. The discharge-specific capacities of the Zn||VS₂-Mn cells are 297.9, 239.6, 220.9, 210.8, 199.6, 192.2, and 179.9 mAh g⁻¹ at 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, and 5.0 A g⁻¹, respectively. The cells still deliver a considerable capacity of 144.6 mAh g⁻¹ even at 10 A g⁻¹ (Figure S12). These are significantly higher than the MnS, VS₂, and the physically mixed VS₂-MnS electrode (mass ratio 7:3) at the same specific current (Figure S13). Furthermore, the VS₂-Mn electrode exhibits superior rate performance compared to other VS₂ electrodes reported in the literature (Figure 2D).^{14,15,20,21,22,23,24,25,26} When the specific current returns to 0.1 A g⁻¹, the specific capacity recovers to 257.4 mAh g⁻¹, confirming excellent electrochemical reversibility. Additionally, the Zn||VS₂-Mn cell demonstrates excellent cycling stability with 94.8% capacity retention after 2,000 cycles at 5 A g⁻¹ (Figure S14). Meanwhile, the capacity retention is 87% after 2,000 cycles at 10 A g⁻¹ and 78.6% even after 3,000 cycles (Figure 2E), which is superior to VS₂, MnS, the physically mixed VS₂-MnS electrode (mass ratio 7:3) (Figure S15), and previously reported VS₂-based electrodes.^{14,15,21,22,23,24,25,26,27,28} To gain deeper insight into the role of Mn²⁺, we investigate the electrochemical performance of VS₂ using an electrolyte of 3 M Zn(CF₃SO₃)₂ + 0.1 M Mn(CF₃SO₃)₂ instead of the original 3 M Zn(CF₃SO₃)₂. The rate performance is comparable to that of the VS₂/MnS. However, the capacity retention is about 66% after 2,000 cycles and further declines to ∼60% after 3,200 cycles at 10 A g⁻¹, indicating poorer long-term stability (Figure S16). This result suggests that the Mn source generated through in-situ reconstruction of the VS₂/MnS composite into a VS₂-Mn structure is more stable and better preserves structural integrity during cycling. The Ragone plot indicates the specific energy and specific power compared with other AZIB cathodes (Figure S17). The results show that at a specific power of 741.5 W kg⁻¹, the Zn||VS₂-Mn cell has a specific energy of 158.6 Wh kg⁻¹, which is superior to many AZIB cathodes that have been reported, such as VS₂,²³ Zn Hexacyanoferrate,²⁹ V₂O₃,³⁰ Todorokite MnO₂,³¹ MnO_x@Ti₃C₂T_x,³² and Ni doped Mn₂O₃.³³ Collectively, these results highlight that the reconstructed VS₂-Mn cathode, derived from the irreversible first-cycle transformation of VS₂/MnS, offers fast kinetics, high reversibility, and exceptional durability.

Figure 2.

Electrochemistry measurements of Zn||VS₂-Mn cells

(A) CV curves of the 1^st, 2^nd, and 3^rd cycles at a scan rate of 0.1 mV s⁻¹.

(B) Galvanostatic charge-discharge curves during different cycles at a specific current of 100 mA g⁻¹.

(C) Rate performance at the specific current from 0.1 A g⁻¹ to 5.0 A g⁻¹.

(D) Comparison of rate capacities between the present VS₂-Mn and previously reported VS₂-based cathodes for AZIBs.

(E) Cycling stability.

Kinetics analysis of Zn ions

The electrochemical kinetics were investigated to understand further the Zn²⁺ storage performance after the structural reconfiguration of the VS₂-Mn electrode. As shown in Figure 3A, CV measurements were performed at different scan rates. With increasing scan rate from 0.2 to 1.0 mV s⁻¹, the overall CV profiles remain essentially identical, with only slight peak shifts and broadening, indicative of well-preserved redox behavior.³⁴ Typically, the peak current (i) and the corresponding scan rate (v) follow a power law relationship described by

$$i=a{v}^b$$ (Equation 1)

where i denotes the peak current (A), v represents the scanning rate (V s⁻¹), and a, b are constants. The b value reflects the rate-limiting step in the electrochemical process and varies from 0.5 to 1.0. When the value of b is equal to 0.5, it indicates that the electrochemical process is controlled by ionic diffusion, while when the value of b is 1.0, it indicates capacitive behavior.³⁵ The equation log (i) = blog (v) + log (a) is derived from Equation 1, and the b values of the cathodic and anodic peaks in the CV curves are calculated to be 1.00, 0.89, 0.96, 0.99, 1.19, and 1.11, respectively (Figure 3B). The results show that the Zn²⁺ storage behavior of VS₂-Mn after structural reconfiguration is mainly controlled by capacitance, which leads to fast Zn²⁺ diffusion kinetics, enabling high-rate performance.^36,37,38,39 To further quantify the contribution of diffusion control and capacitance control at a specific scan rate, Equation 1 is transformed to form Equation 2:

$$i\left(\mathrm{V}\right)=k_1\nu +k_2{\nu }^{1/2}$$ (Equation 2)

Figure 3.

Kinetics of Zn ion behavior

(A) CV curves of VS₂-Mn at various scan rates from 0.2 to 1.0 mV s⁻¹.

(B) Log(i) versus log(v) plots at specific peak currents.

(C) Contribution ratio of capacitive capacity at the scan rate of 0.8 mV s⁻¹.

(D) Contribution ratio of the capacitive and diffusion-controlled charge storage.

From the above equation, the current i at a specific potential (V) can be divided into a capacitance-limiting effect (k₁v) and a diffusion-controlled effect (k₂v^1/2).⁴⁰ Figure 3C depicts a typical CV curve for capacitive current (purple area) versus total current at 0.8 mV s⁻¹. Approximately 92.3% of the total charge comes from the capacitive current, which responses accounts for the remarkable rate capability of the VS₂-Mn cathode. As the scan rate increases from 0.2 mV s⁻¹ to 1 mV s⁻¹, the capacitive contribution increases from 69.3% to 94.7% (Figure 3D), indicating a significant increase in the proportion of capacitance-dominated processes. This pronounced capacitive behavior reflects the rapid Zn²⁺ kinetics and directly explains the exceptional rate performance of VS₂-Mn cathode.

Zn-ion storage mechanism

As mentioned above, the partial dissolution of MnS within the VS₂/MnS composite generate a self-optimized cathode, markedly enhancing Zn²⁺ electrochemical performance. However, the influence of residual Mn on the electronic structure and Zn²⁺ storage mechanism of the reconstructed phase remains to be clarified. Consequently, sXAS was conducted on the VS₂/MnS electrodes. The pristine VS₂ exhibits an octahedral coordination environment, in which the asymmetric distribution of 3d electrons around V results in the splitting of d orbitals into three energy levels: e (d_yz, d_xz), b (d_xy, d_x²-_y²), and a (d_z²).^41,42 As shown in Figure 4A, the V L-edge spectrum comprises two characteristic regions corresponding to the dipole-allowed transitions of V 2p_3/2 → 3d (L₃) and V 2p_1/2 → 3d (L₂).^43,44 The feature at approximately 515.6 eV is assigned to transitions from V 2p_3/2 to e orbitals, whereas the peak near 520.0 eV originates from transitions to the b and a orbitals.^45,46 During electrochemical cycling, both V L₃ and V L₂ edges shift toward lower energies upon full discharge and revert to higher energies after recharge, signifying the reversible reduction and oxidation of V⁴⁺ during Zn²⁺ insertion and extraction.^18,47 The increased intensity of the V L-edge in the second cycle relative to the first implies a gradual reduction in d-orbital electron occupancy, which restricts electron transport during the initial reconstruction process (Figure 4A). In contrast, once the structure becomes stabilized, the V L-edge intensity in the seventh cycle is lower than that in the sixth (Figure 4B), suggesting enhanced delocalization of d electrons and improved charge transfer kinetics.^48,49 The energy separation between the V L₃ and V L₂ edges, associated with 2p spin-orbit coupling,^44,50 decreases from 6.89 eV prior to reconstruction to 6.62 eV afterward. This narrowing arises from the partial intercalation of Mn into the VS₂ layers, which slightly reduces the V valence state and modulates the local electronic environment. The charge density difference analysis (Figure S18) further verifies that Mn incorporation leads to a redistribution of electron density surrounding the V and S atoms.

Figure 4.

Zn-ion storage mechanistic investigation

(A) sXAS spectra of the V L edge and O K edge of the VS₂/MnS electrode when fully charged and discharged in the first two cycles.

(B) sXAS spectra of the V L edge and O K edge of the VS₂/MnS electrode when fully charged and discharged in the 6^th and 7^th cycles.

(C) Density of states for VS₂ and VS₂-Mn.

(D–F) The ex situ XRD patterns and the corresponding charge-discharge profiles for the 6^th cycle at 0.1 A g⁻¹.

(G) V 2p high-resolution XPS spectra of VS₂-Mn at the fully discharged and fully charged states of the 6^th cycle and the fully discharged state of the 7^th cycle.

(H) The schematic illustration of the energy storage mechanism in the Zn||VS₂/MnS battery.

Beyond these experimental observations, the incorporated Mn atoms may also alter the hybridization between V 3d and S 3p orbitals, thus influencing the corresponding electronic states. To corroborate this effect, DFT calculations were carried out to analyze the electronic density of states (DOSs) of pristine VS₂ and VS₂-Mn. As shown in Figure 4C, the VS₂-Mn system exhibits a considerably higher DOS near the Fermi level compared with pristine VS₂, confirming the enhancement of electronic conductivity.³⁵ This improved charge-transport capability accounts for the superior rate performance of the VS₂-Mn electrode.

To investigate the structural evolution and valence state changes of the reconstructed VS₂-Mn electrode during reversible Zn²⁺ de/intercalation, ex situ XRD and XPS analyses were performed. Figures 4D–4F present the XRD patterns collected at different states of the 6^th charge/discharge cycle at 0.1 A g⁻¹, along with the corresponding electrochemical profiles. Upon discharge to 0.1 V, the (001) and (011) diffraction peaks of VS₂-Mn shift toward lower angles (Figures 4F and S19), indicative of interlayer expansion caused by Zn²⁺ insertion. During subsequent charging, these diffraction peaks return to their original positions, confirming the extraction of Zn²⁺ and demonstrating highly reversible structural evolution. Complementary insights into the valence state changes were obtained from XPS analysis. As shown in Figure S20, no Zn signal is observed in the pristine state, whereas a pronounced Zn 2p peak emerges upon full discharge, verifying Zn²⁺ intercalation into the VS₂-Mn framework. After full charging, a weak Zn 2p signal persists, likely arising from residual surface-adsorbed Zn²⁺. The V 2p spectra reveal that vanadium predominantly exists as V⁴⁺ (2p_3/2 at 516.7 eV) with a minor V²⁺ component (2p_3/2 at 513.7 eV) in the pristine state (Figure S21). In the fully discharged state of the 6^th cycle, Zn²⁺ insertion causes the V²⁺ signal to disappear, the V⁴⁺ signal to weaken, and V⁵⁺ to increase markedly, indicating oxidation of low-valence vanadium during Zn²⁺ incorporation (Figure 4G). Upon full charging, Zn²⁺ extraction restores the V⁴⁺ signal, reflecting a reversible redox interaction coupled to Zn²⁺ intercalation/deintercalation. In the fully discharged state of the 7^th cycle, V⁵⁺ becomes the predominant component, accompanied by a small amount of V⁴⁺, further confirming the high reversibility of the vanadium redox reaction. The results highlight that structural reconstruction endows the VS₂-Mn electrode with enhanced stability, enabling fully reversible Zn²⁺ intercalation/deintercalation and thereby ensuring outstanding cycling durability. As illustrated in Figure 4H, the initial VS₂/MnS undergoes an irreversible transformation into Mn-intercalated VS₂. The reconstructed structure provides a more robust and flexible host framework, which facilitates the repeated insertion and extraction of Zn²⁺ ions within the VS₂ layers.

Conclusion

In summary, a VS₂/MnS hybrid was successfully synthesized via a one-step hydrothermal strategy. Rietveld refinement of NPD data confirmed the coexistence of hexagonal 1T-VS₂ and cubic MnS phases, with VS₂ as the dominant component. Operando SRXRD revealed gradual MnS dissolution and partial Mn intercalation into the VS₂ lattice during the initial charge, leading to the formation of a structurally stabilized Mn-intercalated phase (VS₂-Mn). ex situ sXAS and DFT calculations jointly verified that this reconstructed VS₂-Mn phase possesses optimized electronic structure, improved charge-transfer kinetics, and enhanced lattice stability. The electrochemical structural reconfiguration made VS₂-Mn more favorable for electron transfer and structural stabilization, resulting in excellent rate capability (297.9 mAh g⁻¹ at 0.1 A g⁻¹ and 144.6 mAh g⁻¹ at 10 A g⁻¹) and ultralong cycling stability with capacity retention of up to 94.8% after 2,000 cycles at 5 A g⁻¹. Furthermore, the capacity retention rate was 87% after 2,000 cycles and 78.6% after 3,000 cycles even at 10 A g⁻¹. This in situ electrochemical structure self-optimization through partial phase dissolution and Mn intercalation may provide a potential route to designing high-performance electrode materials for AZIBs.

Limitations of the study

This study clarifies the contribution of structural reconstruction to the improved electrochemical performance of VS₂ in aqueous zinc-ion storage, but some limitations exist. So far, the approach has only been validated in layered VS₂, and further studies are needed to confirm its effectiveness in other layered compounds, including V₂C MXene and V₂O₅.

Resource availability

Lead contact

Further information and requests for resources and reagents should be directed to and will be fulfilled by the lead contact, Li Song (song2012@ustc.edu.cn).

Materials availability

This study did not generate new unique reagents.

Data and code availability

• •Data reported in this article will be shared by the lead contact upon request.
• •This paper does not report original code.
• •Any additional information required to reanalyze the data reported in this paper is available from the lead contact upon request.
• •All data supporting the findings of this study are available within the article and from the corresponding authors upon reasonable request.

Acknowledgments

This work was financially supported in part by National Key R&D Program of China (2022YFA1504100), NSFC (12225508, U23A20121, 52202120 and 22075264), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA0410401) and Open Fund of the China Spallation Neutron Source Songshan Lake Science City (KFKT2023B09). The authors thank the Shanghai synchrotron Radiation Facility (BL14W1 and 14B1, SSRF), the Beijing Synchrotron Radiation Facility (1W1B and 4B9A, BSRF), the Hefei Synchrotron Radiation Facility (MCD-A and MCD-B Soochow Beamline for Energy Materials, Photoemission and Catalysis/Surface Science at NSRL), and the USTC Center for Micro and Nanoscale Research and Fabrication for helps in characterizations. The AI-driven experiments, simulations and model training were performed on the robotic AI-Scientist platform of Chinese Academy of Sciences.

Author contributions

K.Z., S.C., and L.S. designed the study. K.Z., X.H., S.W., C.W., and W.W. performed the experiments. K.Z., F.S., and L.H., analyzed the data and wrote the manuscript, which was edited by S.C., L.H., and L.S.

Declaration of interests

The authors declare no conflicts of interest.

STAR★Methods

Key resources table

REAGENT or RESOURCE	SOURCE	IDENTIFIER
Chemical
NH4VO3 powder	Aladdin, 99%	N/A
ammonium hydroxide	Sinopharm Chemical Reagent Co., Ltd, 25–28%	N/A
KMnO4 powder	Sinopharm Chemical Reagent Co., Ltd, ≥99.5%	N/A
Thioacetamide	Sinopharm Chemical Reagent Co., Ltd, ≥99.0%	N/A

Method details

Synthesis of VS₂/MnS hybrid material

0.232 g of NH₄VO₃ was dissolved in a beaker containing 30 mL of deionized water and 2 mL of ammonium hydroxide was added, along with stirring with a magnetic stirrer. 1 mmol of KMnO₄ was added to the above solution. Then, 2.254 g of thioacetamide (TAA) was dissolved in the above mixture and stirring was continued for 3 h. Finally, the mixture was transferred to the liner of a 50 mL hydrothermal reactor and kept at 180°C for 20 h. The hydrothermal product was washed alternately with deionized water and ethanol 5 times and then freeze-dried for 12 h to obtain black VS₂/MnS.

Synthesis of VS₂ nanosheets

The yellow VS₂ was obtained by excluding 1 mmol of KMnO₄ from the above solution, while keeping other conditions the same.

Synthesis of MnS nanoparticles

Black MnS was obtained by keeping 0.232 g NH₄VO₃ out of the above solution, while keeping other conditions the same.

Materials characterizations

The SEM results for microstructural characterization of the samples were obtained on SU8220. The XRD patterns were obtained using a D8-Advance power diffractometer equipped with a Cu Kα radiation source at a wavelength of λ = 1.54 Å. The O K-edge and V L-edge were acquired on the beamline BL12B (MCD) at the National Synchrotron Radiation Laboratory (NSRL). The operando SRXRD measurements were conducted on the beamline BL14B1 of the Shanghai Synchrotron Radiation Facility (SSRF). The synchrotron radiation X-ray wavelength was 0.8889 Å. The XPS results were performed on an ESCALAB 250 spectrometer equipped with a monochromatic Al Kα X-ray source (hν = 1486.6 eV), and the binding energies were calibrated against the C 1s peak at 284.6 eV. The Mn K-edge X-ray absorption spectra were collected at the 14W1 beamline of the Shanghai Synchrotron Radiation Facility (SSRF). A Si (111) double-crystal monochromator was employed for X-ray monochromatization, and a Mn foil was used for energy calibration. NPD measurements were performed on the general purpose powder diffractometer (GPPD) at the China Spallation Neutron Source (CSNS). The collected data were analyzed by Rietveld refinement using the GSAS program suite⁵¹ in combination with the EXPGUI interface.⁵²

Measurements of electrochemical performance

The active materials (VS₂/MnS hybrid material, VS₂, and MnS), carbon black, and polyvinylidene fluoride (PVDF) were weighed and mixed in the ratio of 7:2:1 and milled in an onyx mortar for 10 min to make a homogeneous mixture of solids. Add another 250 μL of N-methyl-2-pyrrolidone (NMP) to the above mortar and continue grinding for 10 min. After grinding, the resulting slurry was coated on the pre-treated stainless-steel mesh circle (pre-treatment of stainless-steel mesh: first, the 1000-mesh stainless steel mesh was stamped into a circle with a radius of 6 mm, then immersed in ethanol and ultrasonically washed for 5–10 min, and finally placed in a 100°C vacuum oven to dry for 12 h). The mass load of active material on each stainless-steel mesh circular sheet was approximately 1.13 mg cm⁻². Subsequently, the circular stainless-steel mesh coated with slurry was placed into an oven at 70°C for pre-drying for 30 min and then transferred to a vacuum oven at 100°C for drying for 12 h. The corresponding VS₂/MnS mixture electrodes, VS₂ electrodes, and MnS electrodes were obtained, respectively. The dried electrodes, medium-rate qualitative filter paper of type 102 with a radius of 10 mm (separator), 120 μL of 3 M Zn(CF₃SO₃)₂ (electrolyte), and 30 μm-thick zinc sheets (counter electrode) were assembled into CR2032 coin-type cells. The rate performance, galvanostatic charge and discharge curves, and stability performance of the cells were measured on the Land CT2001A testing system in the voltage range of 0.01–3.0 V at room temperature. CV curves were measured on an electrochemical workstation (CHI660D, Shanghai CH Instrument Company, China) over a voltage range of 0.1–1.7 V.

DFT calculation

All the calculations are performed in the framework of the DTF with the projector augmented plane-wave method, as implemented in the Vienna ab initio simulation package.⁵³ The generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (PBE) is selected for the exchange-correlation potential.⁵⁴ The cut-off energy for plane wave is set to 480 eV. The energy criterion is set to 10⁻⁵ eV in the iterative solution of the Kohn-Sham equation. All the structures are relaxed until the residual forces on the atoms have declined to less than 0.02 eV/Å. To avoid interlaminar interactions, a vacuum spacing of 20 Å is applied perpendicular to the slab. The formation energy E_form is expressed as

$$E_{form}=E_{{VS}_2-Mn}-E_{{VS}_2}-E_{Mn}$$ (Equation 3)

where $E_{{VS}_2}$, $E_{{VS}_2-Mn}$ and E_Mn are the energies of VS₂, VS₂-Mn and the atom Mn.

Quantification and statistical analysis

This study does not include statistical analysis or quantification.

Published: December 11, 2025