Closed‐loop Recyclable and Robust Supramolecular Hydrogel Electrolytes With High Zinc Ion Mobility for Stable Zinc Anode

ABSTRACT

Hydrogel electrolytes are promising candidates for zinc‐based energy storage systems (ZESs) owing to their superior safety features, favorable ionic conductivity and interfacial compatibility. However, current hydrogel electrolytes suffer from weak mechanical strength, low Zn²⁺ transference numbers, causing Zn dendrite growth and parasitic reactions, while the common permanent covalent crosslinked polymer matrices are non‐recyclable. Herein, a supramolecular hydrogel electrolyte that achieves robust mechanical rigidity with high Zn²⁺ mobility is developed by introducing guanylate quadruplex (G‐quadruplex), which effectively regulates concentration gradients and confines water activity. Experimental characterizations and theoretical simulations display that the G‐quadruplex polyanionic network restrains water activity, homogenizes Zn²⁺ flux and uniforms electric field, effectively stabilize the Zn anode. The hydrogel electrolyte enables durable cycling life of 3,800 hours at 1 mA cm⁻² and 1,800 hours at 10 mA cm⁻² in Zn//Zn symmetric cells. Additionally, the zinc‐ion hybrid supercapacitors display outstanding electrochemical performance and high safety, achieving 97.4% capacity retention over 10 000 cycles. Moreover, the wasted supramolecular hydrogel can be facilely depolymerized back into monomers and biomacromolecules with negligible performances loss, underscoring its recyclability advantage over conventional covalently crosslinked hydrogels. This work provides a supramolecular engineering strategy that overcomes the trade‐offs in hydrogel electrolytes, advancing sustainable and durable ZESs.

A recyclable supramolecular hydrogel electrolyte incorporating G‐quadruplex polyanionic network achieves high Zn²⁺ mobility and mechanical robustness simultaneously. The G‐quadruplex polyanionic framework regulates Zn²⁺ solvation, restrains water activity, and uniformizes ion flux, enabling dendrite‐free zinc anodes.

1. Introduction

The storage of intermittent renewable power requires rechargeable systems that concurrently exhibit high power density, cost‐effectiveness, and inherent safety [1, 2, 3]. Among post‐lithium chemistries, ZESs demonstrate considerable potential for sustainable energy storage due to their high theoretical capacity (820 mAh g⁻¹), favorable redox potential (–0.76 V vs. SHE), and low‐cost (US$ 1.85∼4.4 kg⁻¹) [4, 5, 6, 7, 8]. However, zinc dendrite growth and parasitic reactions provoke internal short circuits and rapid capacity deterioration, severely limiting the practical application of ZESs [9, 10]. A variety of strategies have been proposed to address these issues, such as introducing electrolyte additive [11, 12], constructing artificial protective layers [13, 14, 15], modifying separators [16, 17], and employing hydrogel electrolyte [18, 19]. Among these strategies, hydrogel electrolytes emerging as one of the most effective solution in suppressing Zn dendrite growth and mitigating parasitic reactions for the advantages: (i) favorable ionic conductivity and interfacial compatibility; (ii) abundant hydrophilic functional groups that enable tunable Zn²⁺ solvation structure and confined water activity; and (iii) intrinsic stiffness and elasticity for effective dendrite suppression [20, 21, 22, 23, 24].

Until now, various hydrogel electrolytes have been developed for their inherent safety and favorable electrochemical characteristics [25, 26, 27], however, current hydrogel electrolytes generally faces a trade‐off between mechanical properties and ionic conductivity. High‐strength hydrogel electrolytes can ensure secure and stable device operation while inhibiting Zn dendrite penetration through mechanical confinement [28, 29]. Nevertheless, common methods to strengthen hydrogels (e.g., denser crosslinking, phase separation, or nanofillers) inevitably restrict chain mobility and block ion transport, reducing ionic conductivity and device lifespan [30, 31]. Conversely, high ionic conductivity usually requires high water content and low crosslinking density, which weakens mechanical strength [20, 32]. The high water content also increases water activity, promoting hydrogen evolution and side reactions on the Zn anode. Moreover, the Zn²⁺ transference number in common hydrogels is typically low, causing concentration polarization, uneven electric fields, and dendrite growth [33, 34, 35]. To overcome the above issues, introducing polyanionic or polyzwitterionic networks with polar groups into hydrogels to construct Zn²⁺ transport channels is a promising approach for the functional groups such as ─COO⁻, ─SO₃ ⁻ on polymer chains can bind Zn²⁺ via coordination interaction, providing consecutive Zn²⁺ transport pathways [36, 37, 38, 39]. This strategy not only facilitates Zn²⁺ migration but also maintains good mechanical properties and high ionic conductivity of hydrogel electrolytes. Despite the advantages, these hydrogel electrolytes with permanent covalent crosslinked polymer networks constructed by C─C covalent bonds is inert and non‐recyclable. Substantial hydrogel electrolyte waste will generate after end‐of‐life disposal, leading to resource waste and serious environmental problems. Therefore, it is necessary to develop a hydrogel electrolyte with excellent electrochemical properties and closed‐loop recyclability for the sustainable ZESs with long‐term cycling stability.

Small‐molecule‐based supramolecular (SS) hydrogels are constructed by the self‐assembly of small molecules via dynamic reversible non‐covalent interactions, such as guanylate quadruplex (G‐quadruplex), UPy quadruple hydrogen‐bonded assemblies, Fmoc‐peptide nanofibers, which exhibit wide application in biomedicine, tissue engineering, and flexible electronics [40, 41]. Among these supramolecular motifs, G‐quadruplex featuring ordered nanostructures and dynamic responsiveness [42, 43]. G‐quadruplex are assembled from guanosine monophosphate (GMP) and central cations (e.g., Na⁺, K⁺, and NH₄ ⁺), stabilized by hydrogen bonding and π–π stacking, forming an ordered column skeleton [44, 45]. The ordered G‐quadruplex polyanionic skeleton can form coordination interaction with Zn²⁺, which is promising for serving as Zn²⁺ transport channels and favorable for fast Zn²⁺ ion transport [46, 47]. Furthermore, the reversible noncovalent interactions endow G‐quadruplex with pH‐responsive behavior, enabling their on‐demand disassembly and recovery of monomers for reuse. This offers a practical solution to the end‐of‐service‐life issue of hydrogel electrolytes. However, such SS systems intrinsically suffer from mechanical deficiencies, including poor mechanical strength and limited stretchability, which severely restrict their practical utilization in ZESs [48, 49, 50]. Therefore, it is challenging but promising to construct G‐quadruplex‐based supramolecular hydrogel electrolyte with high mechanical properties to meet the requirements in sustainable ZESs.

Herein, a tough and recyclable G‐quadruplex‐based hydrogel electrolyte (designated Gelatin/G‐quadruplex‐Zn, GGQZ) was developed by integrating G‐quadruplex with gelatin through ionic cross‐linking and salting‐out effects. The poly‐anion skeleton of G‐quadruplex selectively captures Zn²⁺ and promoting its transport along the G‐quadruplex chains, realizing in a high ionic conductivity of 24.4 mS cm⁻¹ and high Zn²⁺ transference number of 0.71. Experimental characterizations and theoretical simulations collectively demonstrated that the abundant phosphate moieties function as zincophilic coordination sites, promoting Zn²⁺ transport, homogenizing ionic flux, and modulating water activity. The synergistic effects effectively inhibit dendritic zinc growth and parasitic side reactions on Zn anodes. Consequently, the GGQZ hydrogel electrolyte achieved stable cycling stability in Zn//Zn symmetric cells, sustaining operation for 3800 h at 1 mA cm⁻² and 1800 h at 10 mA cm⁻². When applied in zinc‐ion hybrid supercapacitors (ZIHCs), it delivered a capacity retention of 97.4% after 10 000 cycles at 1 mA cm⁻². Moreover, leveraging the pH‐responsive G‐quadruplex and temperature‐responsive gelatin networks, the wasted GGQZ hydrogel electrolytes were efficiently depolymerized back into raw materials, underscoring its sustainability advantage over conventional covalent cross‐linked hydrogels.

2. Results and Discussion

Na₂GMP is a renewable nucleotide produced by microbial fermentation at an industrial scale of over 10 000 tons per year, with relatively low production costs (Table S4). Herein, a monomer‐recyclable supramolecular hydrogel electrolyte was fabricated by the renewable Na₂GMP and gelatin, driven by multiple non‐covalent interactions (e.g., H‐bond, π–π stacking, ion‐dipolar coordination, etc.) (Figures 1a and S1). Leveraging the self‐complementary hydrogen‐bonding edges and aromatic surfaces, Na₂GMP could assembles into G‐quartets via Hoogsteen hydrogen bonding and co‐ordination to a central cation (such as Na⁺or K⁺), which further stacks into G‐quadruplex nanofibers through π–π interactions (Figure 1b). Simultaneously, the gelatin network spontaneously interwove with the G‐quadruplex network, generating an interpenetrating network hydrogel (Gelatin/G‐quadruplex, denoted GGQ). The as‐synthesized GGQ supramolecular hydrogel was then soaked in a 2.8 mol L⁻¹ ZnSO₄ aqueous solution for 60 min to obtain the Gelatin/G‐quadruplex‐Zn (GGQZ) hydrogel electrolyte. After the physical crosslinking process, the tough and dynamic GGQZ hydrogel was obtained, and the composition is showed in Table S1. TEM image of the G‐quadruplex hydrogel revealed a densely fibrous structure with diameters of ca. 20–40 nm and low network porosity, whereas the soaked G‐quadruplex hydrogel (G‐quadruplex‐Zn²⁺) exhibited a significantly cross‐linked fibrous network with fiber sizes of ca. 40–100 nm and increased porosity (Figure 1c,d). This structural evolution stems from Zn²⁺‐induced ionic cross‐linking, which effectively eliminates electrostatic repulsion between adjacent G‐quadruplex chains, promotes their aggregation into thicker fibrous chains, strengthens the G‐quadruplex framework, and concurrently increases the overall porosity. Additionally, the SO₄ ²⁻‐dominated salting‐out effect enhances hydrogen bonding between gelatin chains and reduces disorder within the gelatin structure in the soaking process. The synergistic physical cross‐linking of salting‐out effects (gelatin‐SO₄ ²⁻) and ionic cross‐linking (G‐quadruplex‐Zn²⁺) effect results in the mechanically robust Gelatin/G‐quadruplex‐Zn (GGQZ) hydrogel.

FIGURE 1.

(a) Schematic illustration of the supramolecular GGQZ hydrogel electrolyte. (b) Self‐assembly process illustration of G‐quadruplex. (c) TEM images of the G‐quadruplex hydrogel and (d) G‐quadruplex‐Zn²⁺ hydrogel (e) XPS of the GGQ and GGQZ hydrogel electrolytes. (f) Raman spectrum of H‐bond of the Gelatin‐S and GGQZ hydrogel electrolytes. (g) Ionic conductivity and (h) rheological tests of Gelatin‐S, G‐quadruplex‐Zn, GGQZ hydrogel electrolytes. (i) Strain and stress and (j) elastic modulus and toughness of the Gelatin‐S and GGQZ hydrogel electrolytes. Data are presented as mean ± SD (n = 6, 6 independent measurements per group). Statistical significance is performed, the results in (g), (i), and (j) are obtained by Student's t‐test.

Fourier transform infrared (FTIR) spectroscopy was conducted to investigate the evolution of molecular‐level interactions of the hydrogel electrolytes. As depicted in Figure S2a,b, the characteristic peak nears 3300 cm⁻¹, ascribable to hydrogen‐bonded O─H/N─H stretching modes, exhibited pronounced broadening and intensity enhancement. Quantitative analysis revealed that the GGQZ hydrogel possesses a markedly higher proportion of strong hydrogen bonds, increasing from 45.8% in GGQ to 54.9% in GGQZ, accompanied by a decrease in medium hydrogen bonds (from 32.7% to 31.3%) and weak hydrogen bonds (from 21.5% to 13.7%) (Figure S2d). The increased fraction of strong hydrogen bonds, coupled with the reduced fraction of medium and weak hydrogen bonds, indicates that the hydrogen‐bonding network in the GGQ precursor hydrogel has been substantially strengthened by the salting‐out effect. Additionally, the enlarged absorbance of ‐HPO₄ ⁻ bands within the 900–1300 cm⁻¹ region (Figure S2c) conforming the formation of ionic associations between Zn²⁺ cations and phosphate anions. Conformational stability of the hydrogel frameworks was subsequently evaluated via circular dichroism (CD) spectroscopy. For pure gelatin or G‐quadruplex hydrogels, the characteristic CD peak at 190–210 nm (corresponding to random coil conformations) showed a significant decrease after the ion‐exchange process. In sharp contrast, the double‐network GGQ hydrogel retained a well‐defined characteristic peak at this wavelength (Figure S3), which confirms that the two networks are effectively interwoven and restrict the conformational rearrangement. The dimensional stability of the hydrogels was further confirmed after soaking in ZnSO₄ aqueous solution (Figure S4). The pure gelatin and G‐quadruplex hydrogels displayed significant volume shrinkage, whereas the Gelatin/G‐quadruplex hydrogel showed minimal volume change and maintained its dimensions. This improved dimensional stability is attributed to the entanglement between the two networks. X‐ray photoelectron spectroscopy (XPS) and zeta potential characterization were conducted to analyze the ion exchange mediated by Zn²⁺. The corresponding spectra (Figures 1e and S5) shows the almost disappearance of the Na⁺ characteristic peak and the emergence of a distinct Zn²⁺ peak, which directly demonstrated the ion exchange between Na⁺ and Zn²⁺ during soaking. Consistent with this, zeta potential measurements revealed a significant shift from –27.63 mV (pure G‐quadruplex hydrogel) to –2.54 mV (G‐quadruplex‐Zn hydrogel), confirming the effective capture of Zn²⁺ within the G‐quadruplex network via electrostatic interactions (Figure S6). The short‐range stacking order of G‐quadruplex motifs was characterized by x‐ray diffraction (XRD) (Figure S7). Upon Zn²⁺ incorporation, the characteristic diffraction peak at 26.94°—corresponding to a π–π stacking distance of 3.31 Å between G‐quartets—shifted to a higher 2θ value (27.13°) [49, 51], indicating a reduced spacing of 3.28 Å. This peak migration suggested enhanced π–π stacking interactions between neighboring G‐quartets, stemming from Zn²⁺‐mediated electrostatic interactions that compressed interplanar separation. Raman spectroscopic analysis was subsequently performed to investigate the hydrogen‐bonding network of the hydrogel matrices (Figure 1f). Compared to the salting‐out gelatin hydrogel (Gelatin‐S hydrogel), the GGQZ hydrogel exhibited enhanced O─H stretching peaks in the 3000–3800 cm⁻¹ range. Quantitative analysis revealed that the GGQZ hydrogel exhibited a higher proportion of strong hydrogen bonds, with a reduction in medium/weak hydrogen bonds. This transformation is attributed to the participation of hydrophilic groups in the G‐quadruplex‐Zn network in stronger hydrogen‐bonding interactions with H₂O molecules, which weakens the water reactivity and improves the network integrity.

Eelectrochemical impedance spectroscopy (EIS) and ionic conductivity measurements (Figures 1g and S8) demonstrated that the G‐quadruplex‐Zn network endowed the hydrogel with superior electrochemical performance, characterized by lower impedance and higher ionic conductivity compared with Gelatin‐S hydrogel. Because the ─HPO₄ ⁻ groups in the G‐quadruplex polyanionic structure provide continuous coordination sites with Zn²⁺, creating low‐energy‐barrier pathways for fast Zn²⁺ transport along the scaffold. Additionally, Zn²⁺‐mediated ionic cross‐linking between adjacent G‐quadruplex chains generates a rigid yet dynamic network, imparting high modulus to the hydrogel without permanent covalent crosslinks. As shown in Figure S9, the Gelatin‐S hydrogel exhibited a soft yet fragile nature, whereas the G‐quadruplex‐Zn and GGQZ hydrogels displayed self‐supporting capability. Rheological tests results (Figures 1h and S10) illustrated the storage modulus (G') of the GGQZ hydrogel was approximately 62 times higher than that of the Gelatin‐S hydrogel, indicating a significantly stiffer network structure. The mechanical properties of the hydrogels were further characterized by uniaxial tensile test (Figures 1i,j and S11). The GGQZ hydrogel demonstrated a fracture strain of approximately 240%, substantially exceeding the break elongation of ∼170% of the Gelatin‐S hydrogel. Moreover, the fracture strength of the GGQZ hydrogel (786.5 kPa) is 6.3 times that of the Gelatin‐S hydrogel (124.6 kPa). Hysteresis tests (Figures S12 and S13) further demonstrate the superior energy‐dissipating capability of the GGQZ hydrogel: dissipated energy increased from 34.3 to 122.3 kJ m⁻³ as strain rose from 20% to 100%, markedly exceeding the 2.2–69.8 kJ m⁻³ range of the Gelatin‐S hydrogel. At 100% strain, the GGQZ hydrogel exhibited a large hysteresis loop, dissipating 335.2 kJ m⁻³—nearly 5 fold that of the Gelatin‐S hydrogel (70.4 kJ m⁻³). These results confirmed that the G‐quadruplex‐Zn network functions as an effective energy‐dissipating domain, substantially enhanced the toughness of the hydrogels.

The self‐assembly mechanism and Na⁺ stabilization mechanism of the G‐quartet were explored through DFT calculations conducted in the aqueous phase at the B3LYP‐D3(BJ)/ma‐TZVP level using Gaussian 16 (Figure 2a). The DFT‐optimized structure revealed Na⁺ positioned in the central plane of the G‐quartet, interacting with four carbonyl oxygen atoms from guanine. The optimized structure of G‐quartet (ΔE_int = 990.2 kcal mol⁻¹) showed strong coordination between the Na⁺ and O = C (2.28 Å). Moreover, the N₁‐H─O₆ = C and N₂‐H─N₇ distance was 1.84 and 1.85 Å, respectively, belonging to short hydrogen bonds, suggesting a compact packing in G‐quartet. Moreover, the reduced density gradient (RDG) and gradient isosurfaces of G‐quadruplex also displayed negative position of the downward spike and strong H‐bond effect corresponding the hoogesteen type H‐bonds in G‐quartet (Figure S14). The optimized G‐quartet model was subjected to molecular dynamics (MD) simulations to investigate the assembly process and properties of G‐quadruplex. In a 50 ns simulation, the G‐quartets with aromatic surfaces self‐assemble through π–π stacking interactions and form hydrogen bonds with H₂O via phosphate groups (Figure S15), which is consistent with the self‐assembly mechanism proposed above. As illustrated in the MD simulation of GGQZ hydrogel in Figure S16, the H‐bonds between gelatin–gelatin increased within time and a substantial reduction in hydrogen bonding between gelatin‐H₂O was observed, corresponding to the “salting‐out” effect. Moreover, the abundant H‐bonds between G‐quartet‐H₂O also accounted for the decreased water activity in the GGQZ hydrogel.

FIGURE 2.

Multiscale computational analysis of the self‐assembly mechanism and Zn²⁺ transport properties in the GGQZ hydrogel electrolytes. (a) Optical photograph of GGQZ hydrogel electrolyte and DFT‐optimized structure of the G‐quartet with Na⁺ stabilization. (b) Binding energies for Zn²⁺ coordination with H₂O, SO₄ ²⁻, gelatin, and GMP, and for SO₄ ²⁻ interactions. (c–f) RDFs and CNs of Zn²⁺‐O pairs in the Gelatin‐S and GGQZ hydrogel electrolytes. (g, i) MD simulation snapshots showing solvation structures in Gelatin‐S versus GGQZ hydrogels and (h, j) corresponding electrostatic potential mapping. (k) MD‐simulated Zn²⁺ transport pathway through consecutive ─HPO₄ ⁻ groups along G‐quadruplex chains. (l) Mean square displacement (MSD) and (m) non‐Gaussian parameter (α₂(t)) analysis in GGQZ compared to Gelatin‐S hydrogels. (n–p) HOMO, adsorption energies on Zn surface, and differential charge density maps illustrating interfacial electron transfer of different molecules.

First‐principles calculations employing DFT quantified the binding energies for interactions among Zn²⁺, gelatin, G‐quartets, and H₂O molecules. The obtained values were as follows: –0.13 eV for H₂O–H₂O, –4.97 eV for Zn²⁺‐H₂O, –27.42 eV for Zn²⁺‐SO₄ ²⁻, –9.05 eV for Zn²⁺‐gelatin, –17.71 eV for Zn²⁺‐GMP, –18.24 eV for SO₄ ²⁻‐H₂O, and –2.77 eV for SO₄ ²⁻‐gelatin, respectively (Figure 2b). Moreover, the minimum electrostatic potentials for H₂O, gelatin, G‐quadruplex, and SO₄ ²⁻ are –1.88, –2.20, –6.90, and –11.08 eV, respectively (Figure S17). DFT calculations revealed the strong binding energy for Zn²⁺‐GMP and significantly lower minimum electrostatic potential of G‐quadruplexes compared to H₂O, suggesting G‐quadruplex potential in capture Zn²⁺ and reorganizing the Zn²⁺ solvation shell. Additionally, the GMP‐H₂O binding energy (–0.7 eV) exceeds the H₂O–H₂O interaction (–0.2 eV), signifying the capacity of GMP to bind water through phosphate moieties and restructure the hydrogen‐bond network of water. MD simulations of different hydrogel electrolytes were conducted to probe the primary solvation shell (PSS) composition of Zn²⁺, coordination numbers (CN), and radial distribution functions (RDFs) of the various hydrogel electrolytes (Figure 2c–f). In the Gelatin‐S system, the Zn─O RDF peak at 1.94 Å from Zn^{2 +} corresponds to PSS water, whereas a sharp feature at 1.84 Å reflects Zn─O(SO₄ ²⁻). The GGQZ electrolyte exhibited similar peaks, yet a new Zn─O contribution from ─HPO₄ ⁻ groups emerges at 1.82 Å from Zn²⁺ with a CN of 0.22, confirming GMP incorporation in the PSS of Zn²⁺. The Zn─O(H₂O) coordination number declines from 4.01 (Gelatin‐S) to 3.83 (GGQZ), revealing that the G‐quadruplex–Zn network effectively decreases CN of H₂O. The reduced Zn─O(SO₄ ²⁻) g(r) peak intensity and coordination number (from 0.38 of Gelatin‐S to 0.33 of GGQZ) demonstrate that competitive coordination of ─HPO₄ ⁻‐Zn²⁺ with SO₄ ²⁻‐Zn²⁺, suppressing the formation of Zn²⁺‐SO₄ ²⁻ contact ion pair. MD simulations further identified six representative ion‐cluster configurations of varying Zn²⁺ quantities, revealing that ─HPO₄ ⁻ groups seldom participate in these configurations, indicating a lack of simultaneous coordination with SO₄ ²⁻ to a single Zn²⁺ (Figures S18 and S19). Furthermore, the solvation energy of [Zn(H₂O)₆] was –626.58 kcal/mol and decreased to –1050.92 kcal/mol for [Zn(H₂O)₅(GMP)]⁺, corresponding to the stronger effect in capturing Zn²⁺ of GMP (Figure 2g–j). Moreover, the significant reduction in electrostatic potential diminishes repulsive forces within the solvation sheath, thereby facilitating Zn²⁺ transport [52]. The above studies indicate that GMP molecules can engage in the Zn²⁺ solvation structure, suppressing formation of SO₄ ²⁻‐Zn²⁺ contact ion pair, promote Zn²⁺ transport and decreasing active water content in PSS. Moreover, molecular dynamics simulations revealed that Zn²⁺ transport through consecutive ─HPO₄ ⁻ groups (Figure 2k). The Gibbs free energy between two neighboring ─HPO₄ ⁻ is merely about 7 kcal mol⁻¹, indicative of the facile migration of Zn²⁺ (Figure S20). Analysis of Zn²⁺ mean square displacement (MSD) over 30 ns revealed migration rates 2.08 times faster in GGQZ hydrogels relative to the Gelatin‐S control group (Figure 2l), demonstrating that sequential zincophilic sites along G‐quadruplex chains substantially enhanced Zn²⁺ transport. The facilitated transport of Zn²⁺ within the G‐quadruplex network was further examined through analysis of the non‐Gaussian parameter alpha_2(t) extracted from MD simulations (Figure 2m). It shows that the G‐quadruplex network accelerated Zn²⁺ escape from the constraints of polar groups, reducing the caging time from 774 –349 ps. Additionally, the alpha_2(t) plateau is more negative in GGQZ system (shifting from –0.17 to –0.38), corresponding to enhanced Zn²⁺ capture capacity of the G‐quadruplex network and long‐range regulation of Zn²⁺ transport, which enables Zn²⁺ to transport larger displacement. Combining multiple experimental results (FTIR, zeta potential tests, XPS, etc.) with simulations (DFT, MD), the transport mechanism for rapid Zn²⁺ transport in GGQZ hydrogel electrolytes is proposed, in which Zn²⁺ sequentially coordinates with ─HPO₄ ⁻ groups on the G‐quadruplex chains; these phosphate groups provide continuous coordination sites that reconstruct solvated Zn²⁺ ions and create low‐energy‐barrier pathways for fast transport.

Molecular orbital calculations were performed to elucidate deeper insight into the Zn/electrolyte interfacial chemistry (Figure 2n). Compared to the low‐lying highest occupied molecular orbital (HOMO) of H₂O (–7.94 eV), gelatin and G‐quartet (assemble by 4 GMP and Na⁺) exhibit significantly higher HOMO energies (–6.78 and –2.46 eV, respectively), suggesting their higher tendency toward electron donation to Zn²⁺, particularly for the G‐quartet [53]. DFT‐derived adsorption energies for GMP (–2.13 eV) and gelatin (–0.69 eV) are substantially more negative than for water (–0.08 eV), indicating preferential binding to the Zn anode surface (Figure 2o) [12]. Differential charge density analysis further elucidates interfacial molecular interactions, where yellow and cyan regions in the charge maps correspond to electron accumulation and depletion, respectively (Figure 2p). Strong chemisorption, evidenced by pronounced charge transfer stemming from G‐quadruplex, fosters establishment of a water‐depleted interfacial layer between electrode and electrolyte. Consequently, these characteristics make the GGQZ hydrogel electrochemically promising for uniform Zn deposition and dendrite suppression, thereby stabilizing the zinc anode.

The GGQZ hydrogel electrolyte stabilize the zinc anode via the combination of mechanical and electrochemical mechanisms. From a mechanical perspective, the robust, high‐modulus hydrogel inhibits dendrite nucleation by guiding uniform lateral Zn deposition along the electrode surface, yielding planar growth modes [28, 54]. Electrochemically, the polyanionic G‐quadruplex framework selectively captures Zn²⁺ while establishing Zn²⁺ transport pathways, homogenizing Zn²⁺ flux and uniforming the electric field distribution. Specifically, the ─HPO₄ ⁻ moieties facilitate Zn²⁺ transport, modulate Zn²⁺ solvation shells, and constrain water activity, establishing a stable interfacial microenvironment that suppresses dendritic growth and parasitic reactions (Figure 3a). The Zn²⁺ transference number (t_Zn ²⁺) of the GGQZ hydrogel electrolyte was measured to be 0.71, substantially exceeding the value of 0.34 obtained for the Gelatin‐S counterpart (Figure 3b,c). This pronounced enhancement validates that the G‐quadruplex‐Zn network accelerates Zn²⁺ transport and facilitates homogeneous Zn plating. Chronoamperometric (CA) analysis revealed a two‐dimensional diffusion profile for Zn²⁺ in the Gelatin‐S hydrogel electrolyte, coupled with higher current density that correspond to random nucleation and accelerated dendrite growth (Figure 3d). In contrast, the GGQZ hydrogel electrolyte displayed a stable three‐dimensional diffusion mode in Zn²⁺ nucleation, signifying substantial reformation of Zn²⁺ nucleation kinetics by the G‐quadruplex‐Zn network. Furthermore, the activation energy (E_a), fitted from electrochemical impedance spectroscopy (EIS) measurements via the Arrhenius equation (1/Rct = Aexp(−E_a/RT)), provides a quantitative parameter for Zn²⁺ de‐solvation kinetics (Figures 3e and S21). The GGQZ electrolyte exhibits an E_a of 21.42 kJ mol⁻¹, lower than that of the Gelatin‐S electrolyte (30.93 kJ mol⁻¹), indicating that the G‐quadruplex‐Zn network facilitates Zn²⁺ desolvation and enhances charge‐transfer kinetics. Moreover, the GGQZ hydrogel electrolyte exhibits a higher nucleation overpotential (NOP) of 73.2 mV compared to 44.4 mV for the Gelatin‐S electrolyte (Figure 3f), consistent with CV measurements (Figure S22). The higher NOP corresponds to greater driving force during Zn²⁺ electrodeposition, yielding finer, denser nuclei that facilitate homogeneous Zn²⁺ deposition [55, 56]. The capacitive current observed in the non‐Faradaic CV region stems from electric double‐layer formation, enabling subsequent determination of the hydrogel double‐layer capacitance (Figures 3g and S23) [57]. The reduced capacitance of GGQZ hydrogel originates from preferential GMP adsorption on the zinc electrode surface, which obstructs Zn²⁺ binding sites and decreases charge storage capacity. In situ electrochemical impedance spectroscopy conducted on Zn||Zn symmetric cells demonstrated a marked decline in charge‐transfer resistance for the Gelatin‐S hydrogel electrolyte during consecutive plating/stripping cycles. By contrast, the GGQZ hydrogel electrolyte maintained stable impedance values, indicating robust interfacial electrochemical stability at the zinc anode throughout the deposition process (Figure S24). Moreover, water activity confinement effectively reduces corrosion and the hydrogen evolution reaction. Tafel plots indicate that corrosion current densities vary significantly in different electrolytes, from 0.0118 mA cm⁻² for the Gelatin‐S hydrogel electrolyte to 0.0093 mA cm⁻² for the GGQZ hydrogel electrolyte, confirming that GGQZ hydrogel electrolyte effectively restrains Zn anode corrosion (Figure 3h). Linear sweep voltammetry (LSV) shows that GGQZ hydrogel electrolyte exhibited significantly lower potential than the Gelatin‐S hydrogel electrolyte due to optimized Zn²⁺ solvation and limited active water, demonstrating efficient hydrogen evolution inhibition (Figure 3i).

FIGURE 3.

Electrochemical and physical insights into dendrite suppression and Zn²⁺ deposition behavior in the GGQZ hydrogel electrolytes. (a) Schematic illustration of the multifunctional regulation mechanisms of GGQZ hydrogel electrolytes. (b and c) Assessment of Zn²⁺ transfer numbers in Gelatin‐S and GGQZ hydrogel electrolytes. (d) Chronoamperometry (CA) profiles, (e) Arrhenius plots and (f) nucleation overpotential of the Gelatin‐S and GGQZ hydrogel electrolytes. (g) Double‐layer capacitance calculated from non‐Faradaic CV scans. (h) Tafel plots, (i) Linear sweep voltammetry (LSV) curves of the Gelatin‐S and GGQZ hydrogel electrolytes. (j) CLSM 3D height maps corresponding surface roughness fluctuation, (k–m) CAFM current maps and (n–p) KPFM surface potential maps of the Gelatin‐S and GGQZ hydrogel electrolytes assembled Zn anode. COMSOL finite element simulations of (q and r) Zn²⁺ concentration distribution and (s and t) electric field of different hydrogel electrolytes assembled Zn anode during Zn plating process.

Confocal laser scanning microscopy imaging disclosed the surface roughness parameters of 2.02 µm for the GGQZ specimen and 17.43 µm for the Gelatin‐S control after zinc deposition (Figures 3j and S25). The zinc foil surface in GGQZ hydrogel electrolyte presented a smooth, compact morphology. Conversely, the Gelatin‐S hydrogel electrolyte exhibited a rough topography characterized by marked dendritic structures and extensive by‐product deposition. To acquire deeper mechanistic understanding, atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), and conductive AFM (CAFM) analyses were subsequently performed. CAFM revealed that Zn anode cycled with the Gelatin‐S hydrogel electrolyte exhibited marked heterogeneity, with large fluctuation of 593.3 pA (Figure 3k). In contrast, the GGQZ hydrogel assembled Zn anode demonstrated uniform current distribution with a remarkably low fluctuation of 7.1 pA (Figure 3l) and excellent stability (Figure 3m). These electrical differences originated from morphological distinctions: the Gelatin‐S system presented a wavy morphology with high surface roughness (Ra = 468 nm), whereas the GGQZ system showed a dense, flat surface with Ra merely 163 nm (Figure S26). Surface potential measurements followed a similar pattern, where the anode in the Gelatin‐S hydrogel electrolyte displayed non‐uniform distribution with large fluctuation of 186.5 mV (Figure 3n), while the GGQZ anode exhibited highly homogeneous potential distribution with low fluctuation of 38.5 mV (Figure 3o), demonstrating superior stability (Figure 3p). Finite element modeling (FEM) simulations were further conducted to elucidate the electric field distribution and ionic concentration gradient throughout the Zn deposition process. Modeling of Zn dendrite evolution over the 0–120 s timeframe demonstrated irregular growth in the Gelatin‐S hydrogel electrolyte (Figure S27). Simulations of electric field and Zn²⁺ concentration during dendrite evolution further revealed consistent gradients and field distributions that promote uniform Zn²⁺ nucleation and deposition (Figure 3q–t). Consequently, the G‐quadruplex‐Zn network effectively inhibited dendrite expansion by modulating Zn²⁺ diffusion and deposition kinetics through coordinated regulation of both concentration gradients and electric fields.

The performance of the GGQZ hydrogel electrolyte in suppressing dendritic growth and parasitic reactions was assessed through Zn//Zn symmetric and Zn//Cu asymmetric cell. The Zn//Zn symmetric cells with the GGQZ hydrogel electrolyte demonstrated remarkable cycling stability, sustaining operation for over 3800 h at 1 mA cm⁻²/1 mAh cm⁻², substantially surpassing the 278 h lifespan of the Gelatin‐S cells (Figure 4a), consistent with aforementioned experimental characterizations and theoretical simulations. Under higher current densities, the GGQZ cells maintained stable performance for 2300 h at 5 mA cm⁻² and 1800 h at 10 mA cm⁻², while the Gelatin‐S cells failed within 253 and 216 h, respectively, exhibiting polarization exceeding 400 mV under 10 mA cm⁻²/1 mAh cm⁻² (Figures 4b and S28). Rate capability assessments further reveal steadier voltage profiles for the GGQZ cells across various current densities (Figure 4c). Exchange current density measurements indicated enhanced Zn^{2 +} deposition kinetics in the GGQZ cells (2.34 mA cm⁻²) compared to the Gelatin‐S systems (1.48 mA cm⁻²) (Figure S29). Depth of discharge characterization demonstrated rapid short‐circuiting in the Gelatin‐S Zn||Zn cells, whereas the use of GGQZ hydrogel electrolyte ensured stable cycling. In Zn||Cu configurations, Gelatin‐S cell failed after 95 cycles, while the GGQZ cells sustained stable operation over 600 cycles with an exceptional average Coulombic efficiency of 99.67% (Figure 4d). Corresponding capacity‐voltage profiles exhibited higher voltage polarization and stable hysteresis, confirming reversible Zn plating/stripping in GGQZ (Figure 4e). Additionally, a shelving‐recovery test (24 h rest intervals every 10 cycles) underscored superior stability of the GGQZ cells (> 600 h at 5 mA cm⁻²/1 mAh cm⁻²), dramatically exceeding the 42 h duration for Gelatin‐S cells (Figure S30). In situ optical microscopy displayed obvious dendrite and parasitic by‐products on the Zn anode in the Gelatin‐S hydrogel electrolytes, while the GGQZ hydrogel electrolytes achieved planar deposition with excellent suppression of hydrogen evolution reactions (Figure 4f). Post‐cycling XRD analysis of Zn anodes indicated the formation of Zn₄SO₄(OH)₆·H₂O by‐product on the Zn anode in the Gelatin‐S cells, signifying severe corrosion and reduced Coulombic efficiency (Figure 4g,h). Conversely, the Zn anode in the GGQZ cell exclusively exhibited metallic Zn reflections. The I(002)/I(100) intensity ratios of 2.24 for the Gelatin‐S hydrogel electrolyte and 4.29 for the GGQZ hydrogel electrolyte demonstrate preferred (002) basal plane exposure in the latter. This oriented deposition originated from continuous ─HPO₄ ⁻ groups within the G‐quadruplex‐Zn network, establishing an electrostatic shielding layer that homogenized Zn²⁺ concentration and electric field distributions, thereby promoting Zn (002) orientation while inhibiting side reactions. X‐ray photoelectron spectroscopy (XPS) of post‐deposition Zn surfaces (Figures S31 and S32) revealed characteristic signals for C─O─P (533.1 eV), P─O─Zn (135.3 eV), and Zn₃(PO₄)₂ (1022.8 eV) in GGQZ electrolyte, confirming the GMP adsorption and the protective interfacial layer formation on the Zn anode. Scanning electron microscopy of cycled Zn foils demonstrated massive dendrite accumulation on the Zn anode in the Gelatin‐S electrolyte that ultimately formed numerous vertical dendrites (Figures 4i and S33), accounting for voltage polarization and short‐circuiting phenomena. In contrast, the Zn anode surface in the GGQZ electrolyte remained planar and smooth throughout cycling. Furthermore, the GGQZ hydrogel electrolyte exhibited competitive electrochemical performance relative to recent literature reports (Figure 4j), confirming its effectiveness in suppressing of side reactions and dendritic growth for stable operation in ZESs.

FIGURE 4.

Electrochemical cycling performance and Zn deposition morphology in symmetric and asymmetric cells. Long‐term galvanostatic cycling of Zn//Zn symmetric cells using different hydrogel electrolytes at (a) 1 mA cm⁻²/1 mAh cm⁻² and (b) 10 mA cm⁻²/1 mAh cm⁻². (c) Rate capability tests at current densities ranging from 1 to 10 mA cm⁻². (d) CE and (e) corresponding capacity voltage profiles of Gelatin‐S and GGQZ assembled asymmetric cells at 5 mA cm⁻² and 1 mAh cm⁻². (f) In situ optical microscopy images of Zn deposition process under 10 mA cm⁻² in Gelatin‐S versus GGQZ cells. (g and h) XRD patterns of Zn foil after 50 cycles at 5 mA cm⁻²/1 mAh cm⁻² in Gelatin‐S and GGQZ cells. (i) Post‑cycling SEM surface morphologies of Zn anodes in the Gelatin‐S and GGQZ cells with different cycle time. (j) Comparison of cyclic reversibility with representative hydrogel electrolytes reported before.

Supercapacitors, deliver operational lifespans exceeding 10⁵ cycles with rapid response characteristics, which can effectively mitigate instantaneous fluctuations in renewable energy generation systems [3]. Herein, flexible pouch‐type zinc‐ion hybrid supercapacitors (ZIHCs) were assembled by sandwiching hydrogel electrolytes between activated carbon (AC) cathodes and Zn anodes and encapsulating with aluminum plastic film (Figure 5a). Cyclic voltammetry (CV) of the ZIHCs based on the Gelatin‐S and GGQZ hydrogel electrolytes showed expanded enclosed areas from 10 to 100 mV s⁻¹ within a 1.8 V operating window (Figures 5b and S34), verifying accelerated electron/ion transport dynamics in GGQZ. Galvanostatic charge/discharge (GCD) profiles demonstrated pronounced symmetry (Figure 5c). Based on enhanced Zn²⁺ transference number and high ionic conductivity, the GGQZ‐based ZIHCs exhibited excellent rate performance. The GGQZ‐based ZIHCs possessed higher specific capacitance of 386.5, 360.3, 337.2, 306.4, 273.9, and 170.3 F g⁻¹ than that of the Gelatin‐S‐based ZIHCs of 356.5, 315.4, 275.2, 244.2, 271.2, 121.9 F g⁻¹ at current densities of 0.5, 1, 2, 3, 4, and 5 A g⁻¹, respectively (Figure 5d). Long‐term cycling assessments were conducted on the ZIHCs under different current densities (Figure 5e). The GGQZ‐based ZIHCs retains 97.4%, 92.9%, and 78.9% of its initial capacity after 10 000 cycles at 1, 5, and 10 A g⁻¹, respectively. In sharp contrast, the Gelatin‐S‐based ZIHCs retained only 92.8%, 83.8%, and 51.8% of capacitance retention after 10 000 cycles at 1, 5, and 10 A g⁻¹, respectively. This discrepancy originated from the GGQZ hydrogel's ability to suppress by‐product accumulation and promote Zn²⁺ migration. Moreover, after long cycling, the GGQZ still maintained its structural stability. As evidenced by x‐ray diffraction (XRD), confirming that the π–π stacking peak at 27.14° is retained after cycling, verifying the survival of the G‐quartet stacking arrangement after 10 000 cycles in ZIHCs (Figure S35a). TEM images also reveal that the long‐range fibrous architecture remains intact without appreciable structural collapse (Figure S35b,c). CV curves after different cycles at 10 mV s⁻¹ demonstrated that the GGQZ‐based ZIHCs exhibited stable curves, whereas the Gelatin‐S‐based ZIHCs showed noticeable shifts in their CV curves with the number of cycles, confirming the superior reversibility of the GGQZ‐based ZIHCs (Figure 5f). GCD profiles corroborate the result, showing limited changes in the GGQZ‐based ZIHCs, while the Gelatin‐S‐based ZIHCs displayed significant changes (Figure 5g). More encouragingly, the energy density of the ZIHCs could reach impressive values ranging from 46.3 to 165.6 Wh kg⁻¹ at power densities between 0.27 and 1.47 kW kg⁻¹, comparable to many related high performance supercapacitors (Figure S36). Moreover. the GGQZ‐based supercapacitors exhibited over 96% of capacitance retention under continuous bending cycles (Figure 5h), demonstrating excellent mechanical stability. Figure 5i depicts a pouch‐type ZIHC powering blue LED bulbs under harsh bending and cutting conditions, confirming the practical applicability and safety of the GGQZ‐based ZIHCs. Owing to their high power density, long cycling lifespan, and exceptional safety, GGQZ‐based ZIHCs represent promising candidates for short‐duration energy storage systems critical to future clean energy infrastructure (5j).

FIGURE 5.

Electrochemical performance and flexibility demonstration of the ZIHCs assembled with Gelatin‐S and GGQZ hydrogel electrolytes. (a) Schematic illustration of the flexible pouch ZIHC. (b) Cyclic voltammetry curves at scan rates from 10 to 100 mV s⁻¹ within a 1.8 V operating window of GGQZ‐based ZIHC. (c) Galvanostatic charge–discharge profiles at different current density of GGQZ‐based ZIHC. (d) Specific capacitance comparison at current densities of 0.5, 1, 2, 3, 4, and 5 A g⁻¹ with different hydrogel electrolytes based ZIHCs. (e) Long‐term cycling stability at 1, 5, and 10 A g⁻¹ over 10 000 cycles with different hydrogel electrolytes based ZIHCs. (f) CV curves at 10 mV s⁻¹ and (g) GCD profiles at 5 A g⁻¹ in different cycles. (h) Capacitance retention of GGQZ hydrogel electrolytes assembled ZIHC under continuous bending deformations. (i) Photographs of a pouch ZIHC powering blue LEDs under normal, bent, and cut conditions. (j) Conceptual deployment of ZIHCs in renewable energy storage systems for energy integration.

Hydrogel electrolytes are widely applied in devices such as batteries, supercapacitors, and flexible wearable technologies. Composed of polymer matrix, their disposal caused environmental pollution, similarly as plastics or adhesives. Recyclable hydrogel electrolytes enable the recovery of valuable material, such as polymer matrices and electrolyte salts, facilitating resource conservation. Here, a recyclable GGQZ hydrogel electrolyte assembles through dynamic supramolecular interactions was developed, which responsive to external stimuli, enabling the conversion of waste hydrogels into reusable raw materials. As the gelatin network was temperature‐responsive and G‐quadruplex network was pH‐responsive, the double‐network supramolecular hydrogel could disassemble specific network into solution in specific external stimuli (Figure S37). Rheological characterization determined the sol‐gel transition point of the pure gelatin hydrogel to be 44.8°C, corresponding to the cross‐over where storage modulus (G′) equals loss modulus (G″) (Figure S38). Figures 6a and S39 show the recycling process. First, the used hydrogel was heated to 70°C at pH 1–2 to disassemble the gelatin and G‐quadruplex networks, yielding a mixed solution of gelatin and ZnSO₄ and Zn²⁺‐GMP precipitate (Figure S40). After filtration, gelatin was recovered by microfiltration to remove ZnSO₄ and dried at 70°C for 12 h. The precipitate was then treated with NaOH to obtain Zn(OH)₂ and Na₂GMP solution, and Na₂GMP monomers were recovered by drying the Na₂GMP solution at 70°C for 12 h. Proton NMR spectroscopy validated the success recovery and purification of the Na₂GMP monomers (Figure 6b). During the entire recycling process, GMP underwent different pH‐dependent states: aqueous solution (pH 6–7), hydrogel (pH 3–5), and Zn²⁺‐H₂GMP coordination complex (pH 1–2) (Figure 6c). The pH‐sensitive G‐quadruplex‐Zn framework disassembles under acidic conditions (pH < 2), where complete protonation of phosphate groups (─PO₄H₂) and N₇ sites disrupts the G‐quartet hydrogen‐bonding network. Simultaneously, Zn²⁺ coordinates to the available N₇ donors, acting as inter‐molecular bridges to form the insoluble Zn²⁺‐GMP coordination complex [58]. This behavior is attributed to varying GMP solvation energies at different pH levels: –195.8 kcal mol⁻¹ for Na₂GMP, –64.7 kcal mol⁻¹ for NaHGMP, and –35.1 kcal mol⁻¹ for H₂GMP (Figure 6d). As solvation energy decreasing, hydrophobic interactions increasing, the GMP monomer self‐assembled into supramolecular, corresponding to the transitions from solution to hydrogel. Moreover, the electrostatic potential energy diagram shows that the electrostatic potential ranges for Na₂GMP, NaHGMP, and H₂GMP are –10.36–0.42 eV, –5.78–1.66 eV, and –3.00–6.02 eV, respectively (Figure 6e). The minimal electrostatic potential increased with the protonation of the phosphate group, indicating weakened interaction with water and enhanced hydrophobic effect. Consequently, at low pH, the supramolecular disassembled, which exposed the hydrogen‐bonding edges of GMP and formed Zn²⁺‐H₂GMP coordination complex spontaneously [44]. GGQZ hydrogel electrolytes reassembled from recycled monomers retained 99.1% of their initial conductivity after two cycles (Figure 6f). Consist with this, the recycled GGQZ hydrogel electrolytes maintained 91.8% of their initial mechanical strength (Figure 6g). TOST analysis confirms that, within equivalence margins of ±5% for ionic conductivity and ±10% for fracture strength, the recycled hydrogels remain statistically equivalent to the pristine sample in both properties (p < 0.05). Moreover, the supercapacitor device assembled by the hydrogel prepared by the recycled material also maintains excellent cycle stability (retain 96.8% of initial capacity after 10 000 cycles), indicating that the hydrogel prepared by the recycled material still has good functionality, which can effectively stabilize the zinc anode and achieve long cycle stability (Figure S41).

FIGURE 6.

Design and life‐cycle assessment of the recyclable GGQZ hydrogel electrolyte. (a) Schematic diagram of the recycling process of the GGQZ hydrogel electrolyte and optical photographs of various stages in the actual recycling process. (b) ¹H NMR spectra of Na₂GMP after regeneration. (c) pH‐dependent phase transitions of GMP from aqueous solution (pH 6–7) to hydrogel (pH 3–5) and Zn‐GMP precipitation (pH 1–2). (d) Solvation energies and (e) electrostatic potential maps of GMP monomers at varied protonation states. (f) Ionic conductivity and (g) mechanical performance of the recycled GGQZ hydrogel electrolytes. (h) Disaggregated climate change potential from cradle‐to‐grave life‐cycle assessment of different hydrogels. (i) Comparative LCA of other environmental impact categories. Data are presented as mean ± SD (n = 6, 6 independent measurements per group). Statistical significance is performed, the results in (f) and (g) are obtained by two one‐sided tests.

Life cycle assessment (LCA) methodology was employed to evaluate the environmental sustainability characteristics of the GGQZ hydrogel electrolytes [59], including two representative petroleum‐derived PAM‐based [60] and PVA‐based [28] hydrogel electrolytes as the controls. LCA reveals that cradle‐to‐gate production of the GGQZ hydrogel electrolyte offers a reduced CO₂ footprint and significantly lower impacts than non‐renewable electrolytes (PAM/LA/PSBMA and PVA‐PAM‐PAN‐Zn) across multiple categories: ecotoxicity, non‐renewable energy resources, and both carcinogenic and non‐carcinogenic human toxicity (Figure S42). Disaggregated results (Figure S43) show that the adoption of non‐renewable materials PAM/PVA/PAN/DMSO causes severe environmental impacts, particularly in acidification, freshwater ecotoxicity, and non‐renewable energy consumption, demonstrating that renewable hydrogels effectively reduce multifaceted environmental burdens. Moreover, compared to direct landfill disposal of petroleum‐based hydrogels, the recyclable GGQZ hydrogel facilitates material recovery and further mitigates environmental impacts. As shown in Figure 6h, the recycled GGQZ (Re‐GGQZ) hydrogel exhibited a climate change potential of only 0.13 kg CO₂ equiv kg⁻¹, whereas cradle‐to‐grave values for landfill disposal of GGQZ, PAM/LA/PSBMA, and PVA‐PAM‐PAN‐Zn were 0.63, 1.59, and 2.62 kg CO₂ equiv kg⁻¹, respectively. Consistent across other impact categories (Figures 6i and S44), material recycling substantially reduced environmental burdens. The Re‐GGQZ hydrogel thus demonstrates both reduced impacts and closed‐loop material sustainability through simple, green processes.

3. Conclusion

In summary, a recyclable supramolecular hydrogel electrolyte with outstanding comprehensive performance was developed. Through multiple non‐covalent interactions, the renewable gelatin and Na₂GMP constructed a robust yet dynamic hydrogel that simultaneously fulfills mechanical, electrochemical, and sustainability requirements. Computational and experimental evidence revealed that the ─HPO₄ ⁻ functional group displace water in PSS of Zn²⁺, suppressing contact ion pair formation, and constraining water activity. Simultaneously, the polyanionic G‐quadruplex accelerated Zn²⁺ transport and homogenized the electric field distribution and Zn²⁺ flux at the electrode–electrolyte interface, suppressing dendritic nucleation and mitigating parasitic side reactions. Consequently, the GGQZ‐based Zn//Zn symmetric cells achieved stable cycling stability, surpassing 3800 h at 1 mA cm⁻²/1 mAh cm⁻² and 1800 h at 10 mA cm⁻²/1 mAh cm⁻². Moreover, the GGQZ‐based Zn//Cu asymmetric cells maintained a high average Coulombic efficiency of 99.67% across 600 cycles. The corresponding ZIHCs also demonstrated exceptional durability, preserving 97.4% of their initial capacitance after 10 000 cycles at 1 mA cm⁻², while maintaining stable work under severe mechanical deformations (bending/cutting). Moreover, the pH‐triggered G‐quadruplex and thermo‐responsive gelatin enabled full recycling of wasted hydrogel into initial monomers and biomacromolecules with negligible performances loss. This work establishes a green, scalable supramolecular design paradigm for high‐performance hydrogel electrolytes, offering practical design guidelines for developing next‐generation sustainable energy storage systems.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Supporting File: anie73578‐sup‐0001‐SuppMat.pdf.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.