Multi-Scale Structure Engineering of ZnSnO3 for Ultra-Long-Life Aqueous Zinc-Metal Batteries

In situ engineering of a glutathione-derived hydrophobic layer for durable and dendrite-free Zn anodes

Aqueous Zn-ion batteries (AZIBs) are gaining increasing attention for large-scale energy storage due to their cost-effectiveness, safety, and high volumetric energy density. However, their practical application is still hindered by challenges such as uncontrolled growth of Zn dendrites and unwanted side reactions. In this study, we introduce an interfacial engineering strategy by applying a glutathione (GSH) functional layer on the surface of the Zn anode (GSH@Zn). The GSH layer not only mitigates corrosion by increasing the hydrophobicity of Zn anodes but also guides uniform Zn deposition. Moreover, the native oxides on Zn anodes are etched by glutathione, resulting in an increased electrochemical active area and reduced interfacial impedance, which improves reaction kinetics. Therefore, the GSH@Zn anode demonstrates stable, long-term plating/stripping cycling, operating dendrite-free for 4500 h at 1 mA cm-2, significantly outperforming bare Zn anodes, which short-circuit after only 130 h. When paired with a vanadium-based cathode, the full cell shows excellent cycling stability and rate capability, retaining 86 % of its capacity after 2000 cycles and releasing 60 % of its capacity at 4 A g-1. This work offers an effective strategy to enhance the stability and reversibility of Zn anodes in aqueous electrolytes, laying the groundwork for the development of durable, high-performance Zn-based energy storage systems.

Electrolyte Additive-Assembled Interconnecting Molecules-Zinc Anode Interface for Zinc-Ion Hybrid Supercapacitors

Zinc-ion hybrid supercapacitors (ZHSs) are promising energy storage systems integrating high energy density and high-power density, whereas they are plagued by the poor electrochemical stability and inferior kinetics of zinc anodes. Herein, we report an electrolyte additive-assembled interconnecting molecules-zinc anode interface, realizing highly stable and fast-kinetics zinc anodes for ZHSs. The sulfobutyl groups-grafted β-cyclodextrin (SC) supramolecules as a trace additive in ZnSO4 electrolytes not only adsorb on zinc anodes but also self-assemble into an interconnecting molecule interface benefiting from the mutual attraction between the electron-rich sulfobutyl group and the electron-poor cavity of the adjacent SC supramolecule. The interconnecting molecules-zinc anode interface provides abundant anion-trapping cavities and zincophilic groups to enhance Zn2+ transference number and homogenize Zn2+ deposition sites, and meanwhile, it accelerates the desolvation of hydrated Zn2+ to improve zinc deposition kinetics and inhibit active water molecules from inducing parasitic reactions at the zinc deposition interface, making zinc anodes present superior reversibility with 99.7% Coulombic efficiency, ~ 30 times increase in operation lifetime and an outstanding cumulative capacity at large current densities. ZHSs with 20,000-cycle life and optimized rate capability are thereby achieved. This work provides an inspiring strategy for designing zinc anode interfaces to promote the development of ZHSs.

Innovative synergistic control of electric fields and Zn2+ dynamics for revolutionizing zinc metal battery stability

Aqueous zinc-ion batteries (ZIBs) are emerging as promising next-generation energy storage systems due to their inherent safety, environmental sustainability, and cost-effectiveness. However, their widespread application is hindered by challenges such as dendritic Zn growth, hydrogen evolution, and corrosion-induced passivation, which compromise performance and scalability. To overcome these obstacles, we developed a novel dual-interface modified zinc anode by integrating a zinc fluoride (ZnF2)-silicon (Si) interface using fluorine-doped silicon nanoparticles encapsulated within hollow mesoporous carbon nanospheres (F-Si@HMCS). The in situ formation of a ZnF2 layer provides high electrochemical stability, effectively suppressing dendrite formation, mitigating zinc corrosion, and reducing side reactions with the electrolyte. The silica layer further facilitates uniform Zn electrodeposition by forming Si-O-Zn bonds, which regulate electric field distribution and lower nucleation energy barriers. Additionally, the hollow mesoporous carbon structure facilitates efficient ion transport and acts as a buffer against volume changes during cycling. Consequently, the F-Si@HMCS@Zn electrode exhibits a long lifespan of over 2500 h at 5 mA cm-2 with a capacity of 0.5 mA h cm-2 in a symmetrical cell test. When coupled with α-MnO2 cathodes, the resulting ZIBs exhibit outstanding stable cycle life over 2000 cycles at 2 A g-1.

Polyelectrolyte Membrane Enables Highly Reversible Zinc Battery Chemistry via Immobilizing Anion and Stabilizing Water

The integration of water-based electrolytes into zinc-ion batteries encounters challenges due to the limited voltage window of water, interfacial side reactions of mobile counterions, and the growth of zinc metal (Zn0) dendrites during charge. In this study, we introduce a nonfluorinated, cation-conducting polyelectrolyte membrane (PEM) designed to alleviate these challenges by suppressing the reactivities of both water and counterions. This PEM forms hydrogen bonds with water molecules through its proton-accepting side chains, thus shifting the lowest unoccupied molecular orbital (LUMO) energy of water from -0.37 to -0.14 eV and inducing a negative shift in the onset potential for hydrogen evolution by 110 mV. Additionally, it immobilizes the counteranions onto the polymer backbones via covalent bonding, hence making the Zn2+ transference number nearly unity (0.96). Meanwhile, the high modulus PEM establishes a solid-state diffusion barrier to homogenize the interfacial Zn2+ flux, leading to 3D in-plane interfacial Zn2+ diffusion and compact Zn0 plating within the (002) plane. Atomic resolution scanning transmission electron microscopy (STEM) reveals corrosion-free Zn0 deposition without electrolyte degradation, while operando transition X-ray microscopy (TXM) further illustrates the real-time dendrite-free Zn0 plating process at 5 mA/cm2. Consequently, the unique properties of this water-binding and anion-tethering PEM enable enhanced electrochemical performance without employing highly fluorinated and expensive anions. This PEM demonstrates a durability of 3800 h in Zn0-Zn0 symmetric cells and a lifetime of 6000 cycles in Zn0-LiV3O8 full cells.

Ultrasensitive Chemiresistive Gas Sensors Based on Dual-Mesoporous Zinc Stannate Composites for Room Temperature Rice Quality Monitoring

The integration of dual-mesoporous structures, the construction of heterojunctions, and the incorporation of highly concentrated oxygen vacancies are pivotal for advancing metal oxide-based gas sensors. Nonetheless, achieving an optimal design that simultaneously combines mesoporous structures, precise heterojunction modulation, and controlled oxygen vacancies through a one-step process remains challenging. This study proposes an innovative method for fabricating zinc stannate semiconductors featuring dual-mesoporous structures and tunable oxygen vacancies via a direct solution precursor plasma spray technique. As a proof of concept, the resulting zinc stannate-based coatings are applied to detect 2-undecanone, a key biomarker for rice aging. Remarkably, the zinc oxide/zinc stannate heterojunctions with a well-defined secondary pore structure exhibit exceptional gas-sensing performance for 2-undecanone at room temperature. Furthermore, practical experiments indicate that the developed sensor effectively identifies adulteration in various rice varieties. These results underscore the potential of this method for designing metal oxides with tailored properties for high-performance gas sensors. The enhanced adsorption capacity and dual-mesoporous features of this semiconductor make it a promising candidate for sensing applications in agricultural food safety inspections.

Electrolyte design for reversible zinc metal chemistry

Metal anodes hold significant promise for next-generation energy storage, yet achieving highly reversible plating/stripping remains challenging due to dendrite formation and side reactions. Here we present a tailored electrolyte design to surpass 99.9% Coulombic efficiency (CE) in zinc metal anodes by co-engineering salts and solvents to address two critical factors: plating morphology and the anode-electrolyte interface. By integrating a dual-salt approach and organic co-solvent design, these issues can be effectively addressed. The resulting hybrid dual-salt electrolyte renders CE of 99.95% at 1 mA cm-2 at a medium concentration (3.5 m). Building upon the near-unity CE, an anode-free cell with ZnI2 cathode can stably run more than 1000 cycles under practical conditions with minimal capacity loss. Our findings provide a promising pathway for the design of reversible metal anodes, advancing metal-based battery technologies for broader energy storage applications.

Fast Kinetics Enabled by Ion Enrichment Layer for Dendrite-Free Zinc Anode

Aqueous zinc-ion batteries (AZIBs) are considered a promising choice for energy storage devices owing to the excellent safety and favorable capacity of the Zn anode. However, the uncontrolled dendrite growth of Zn anode severely constrains the practical applications of AZIBs. Herein, a novel ion enrichment layer of CuS is designed and constructed on the Zn foil surface to achieve dendrite-free Zn anode. This CuS with appropriate Zn affinity and hollow architecture exhibits ion enriching characteristics. Furthermore, CuS@Zn anode can significantly reduce de-solvation barriers of hydrated Zn2+, promoting Zn2+ migration and minimizing nucleation overpotential. Benefiting from the above results, the Zn deposition kinetics are effectively improved. As expected, the CuS@Zn anode exhibits significantly improved Zn plating/stripping reversibility for 1000 h at 1 mA cm-2 and 900 h at 5 mA cm-2 . Furthermore, the assembled CuS@Zn||MnO2 full battery also exhibits superior rate performance and cycling stability. This work provides a feasible method to achieve uniform and dense Zn deposition for the stabilization of Zn anode.

Grain Boundary Filling Empowers (002)-Textured Zn Metal Anodes with Superior Stability

Aqueous Zn battery is promising for grid-level energy storage due to its high safety and low cost, but dendrite growth and side reactions at the Zn metal anode hinder its development. Designing Zn with (002) orientation improves the stability of the Zn anode, yet grain boundaries remain susceptible to corrosion and dendrite growth. Addressing these intergranular issues is crucial for enhancing the electrochemical performance of (002)-textured Zn. Here, a strategy based on grain boundary wetting to fill intergranular regions and mitigate these issues is reported. By systematically investigating boundary fillers and filling conditions, In metal is chosen as the filler, and one-step annealing is used to synergistically convert commercial Zn foils into single (002)-textured Zn while filling In into the boundaries. The inter-crystalline-modified (002)-textured Zn (IM(002) Zn) effectively inhibits corrosion and dendrite growth, resulting in excellent stability in batteries. This work offers new insights into Zn anode protection and the development of high-energy Zn batteries.

Dual-Functional Interfacial Layer Enabled by Gating-Shielding Effects for Ultra-Stable Zn Anode

Large-scale application of low-cost, high-safety and environment-compatible aqueous Zn metal batteries (ZMBs) is hindered by Zn dendrite failure and side reactions. Herein, highly reversible ZMBs are obtained by addition of trace D-pantothenate calcium additives to engineer a dual-functional interfacial layer, which is enabled by a bioinspired gating effect for excluding competitive free water near Zn surface due to the trapping and immobilization of water by hydroxyl groups, and guiding target Zn2+ transport across interface through carboxyl groups of pantothenate anions, as well as a dynamic electrostatic shielding effect around Zn protuberances from Ca2+ cations to ensure uniform Zn2+ deposition. In consequence, interfacial side reactions are perfectly inhibited owing to reduced water molecules reaching Zn surface, and the uniform and compact deposition of Zn2+ is achieved due to promoted Zn2+ transport and deposition kinetics. The ultra-stable symmetric cells with beyond 9000 h at 0.5 mA cm-2 with 0.5 mAh cm-2 and over 5000 h at 5 mA cm-2 with 1 mAh cm-2, and an average Coulombic efficiency of 99.8% at 1 mA cm-2 with 1 mAh cm-2, are amazingly realized. The regulated-electrolyte demonstrates high compatibility with verified cathodes for stable full cells. This work opens a brand-new pathway to regulate Zn/electrolyte interface to promise reversible ZMBs.

A "Zn2+ in Salt" Interphase Enabling High-Performance Zn Metal Anodes

Zinc metal is a promising anode candidate for aqueous zinc ion batteries due to its high theoretical capacity, low cost, and high safety. However, its application is currently restricted by hydrogen evolution reactions (HER), by-product formation, and Zn dendrite growth. Herein, a "Zn2+ in salt" (ZIS) interphase is in situ constructed on the surface of the anode (ZIS@Zn). Unlike the conventional "Zn2+ in water" working environment of Zn anodes, the intrinsic hydrophobicity of the ZIS interphase isolates the anode from direct contact with the aqueous electrolyte, thereby protecting it from HER, and the accompanying side reactions. More importantly, it works as an ordered water-free ion-conducting medium, which guides uniform Zn deposition and facilitates rapid Zn2+ migration at the interface. As a result, the symmetric cells assembled with ZIS@Zn exhibit dendrite-free plating/striping at 4500 h and a high critical current of 14 mA cm-2. When matched with a vanadium-based (NVO) cathode, the full battery exhibits excellent long-term cycling stability, with 88% capacity retention after 1600 cycles. This work provides an effective strategy to promote the stability and reversibility of Zn anodes in aqueous electrolytes.

Zincophilic Nanospheres Assembled as Solid-Electrolyte Interphase on Zn Metal Anodes for Reversible High-rate Zn-Ion Storage

Aqueous Zn-ion batteries (ZIBs) are considered to be one of the most promising energy storage devices in the post-lithium-ion era with fast ionic conductivity, safety, and low cost. However, excessive accumulation of zinc dendrites will fracture and produce dead zinc, resulting in the unsatisfied utilization rate of Zn anodes, which greatly restricts the lifespan of the battery and reduces the reversibility. In this paper, by constructing a protective layer of ZnSnO3 hollow nanospheres in situ growth on the surface of the Zn anode, more zincophilic sites are established on the electrode surface. It demonstrates that uniform deposition of Zn ions by deepening the binding energy with Zn ion and its unique hollow structure shortens the diffusion distance of Zn ions and enhances the reaction kinetics. The assembled Zn-ion hybrid supercapacitor (ZHSC) of ZnSnO3@Zn//AC achieved a long-term lifespan with 4000 cycles at a current density of 10 mA cm-2 with a Coulombic efficiency of 99.31% and capacity retention of 79.6%. This work offers a new path for advanced Zn anodes interphase supporting the long cycle life with large capacities and improving electrochemical reversibility.

Stabilizing Zn/electrolyte Interphasial Chemistry by a Sustained-Release Drug Inspired Indium-Chelated Resin Protective Layer for High-Areal-Capacity Zn//V2O5 Batteries

For zinc-metal batteries, the instable chemistry at Zn/electrolyte interphasial region results in severe hydrogen evolution reaction (HER) and dendrite growth, significantly impairing Zn anode reversibility. Moreover, an often-overlooked aspect is this instability can be further exacerbated by the interaction with dissolved cathode species in full batteries. Here, inspired by sustained-release drug technology, an indium-chelated resin protective layer (Chelex-In), incorporating a sustained-release mechanism for indium, is developed on Zn surface, stabilizing the anode/electrolyte interphase to ensure reversible Zn plating/stripping performance throughout the entire lifespan of Zn//V2O5 batteries. The sustained-release indium onto Zn electrode promotes a persistent anticatalytic effect against HER and fosters uniform heterogeneous Zn nucleation. Meanwhile, on the electrolyte side, the residual resin matrix with immobilized iminodiacetates anions can also repel detrimental anions (SO4 2- and polyoxovanadate ions dissolved from V2O5 cathode) outside the electric double layer. This dual synergetic regulation on both electrode and electrolyte sides culminates a more stable interphasial environment, effectively enhancing Zn anode reversibility in practical high-areal-capacity full battery systems. Consequently, the bio-inspired Chelex-In protective layer enables an ultralong lifespan of Zn anode over 2800 h, which is also successfully demonstrated in ultrahigh areal capacity Zn//V2O5 full batteries (4.79 mAh cm-2).

Rescuing zinc anode-electrolyte interface: mechanisms, theoretical simulations and in situ characterizations

The research interest in aqueous zinc-ion batteries (AZIBs) has been surging due to the advantages of safety, abundance, and high electrochemical performance. However, some technique issues, such as dendrites, hydrogen evolution reaction, and corrosion, severely prohibit the development of AZIBs in practical utilizations. The underlying mechanisms regarding electrochemical performance deterioration and structure degradation are too complex to understand, especially when it comes to zinc metal anode-electrolyte interface. Recently, theoretical simulations and in situ characterizations have played a crucial role in AZIBs and are exploited to guide the research on electrolyte engineering and solid electrolyte interphase. Herein, we present a comprehensive review of the current state of the fundamental mechanisms involved in the zinc plating/stripping process and underscore the importance of theoretical simulations and in situ characterizations in mechanism research. Finally, we summarize the challenges and opportunities for AZIBs in practical applications, especially as a stationary energy storage and conversion device in a smart grid.

Molecular Engineering Enables Hydrogel Electrolyte with Ionic Hopping Migration and Self-Healability toward Dendrite-Free Zinc-Metal Anodes

Hydrogel electrolytes (HEs), characterized by intrinsic safety, mechanical stability, and biocompatibility, can promote the development of flexible aqueous zinc-ion batteries (FAZIBs). However, current FAZIB technology is severely restricted by the uncontrollable dendrite growth arising from undesirable reactions between the HEs with sluggish ionic conductivity and Zn metal. To overcome this challenge, this work proposes a molecular engineering strategy, which involves the introduction of oxygen-rich poly(urea-urethane) (OR-PUU) into polyacrylamide (PAM)-based HEs. The OR-PUU/PAM HEs facilitate rapid ion transfer through their ionic hopping migration mechanism, resulting in uniform and orderly Zn2+ deposition. The abundant polar groups on the OR-PUU molecules in OR-PUU/PAM HEs break the inherent H-bond network, tune the solvation structure of hydrated Zn2+, and inhibit the occurrence of side reactions. Moreover, the interaction of hierarchical H-bonds in the OR-PUU/PAM HEs endows them with self-healability, enabling in situ repair of cracks induced by plating/stripping. Consequently, Zn symmetric cells incorporating the novel OR-PUU/PAM HEs exhibit a long cycling life of 2000 h. The resulting Zn-MnO2 battery displays a low capacity decay rate of 0.009% over 2000 cycles at 2000 mA g-1. Overall, this work provides valuable insights to facilitate the realization of dendrite-free Zn-metal anodes through the molecular engineering of HEs.

Ionic Layer Epitaxy Growth of Organic/Inorganic Composite Protective Layers for Large-Area Li and Zn Metal Anodes

Li and Zn metal batteries using organic and aqueous electrolytes, respectively, are desirable next-generation energy storage systems to replace the traditional Li-ion batteries. However, their cycle life and safety performance are severely constrained by a series of issues that are attributed to dendrite growth. To solve these issues, a nanothick ZnO-oleic acid (ZnO-OA) composite protective layer is developed by a facile ionic layer epitaxy method. The ZnO-OA layer provides strong lithophilic and zincophilic properties, which can effectively induce uniform ion deposition. As a result, the ZnO-OA protected Li and Zn metal anodes can cycle stably for over 600 and 1000 h under a large current density of 10 mA cm-2. Employing the ZnO-OA protected anodes, the Li||LiFePO4 cell can maintain a capacity retention of 99.5% after 600 cycles at a 1 C rate and the Zn||MnO2 cell can operate stably for 1000 cycles at 1 A g-1 current density.

Synergistic Modulation of In-Situ Hybrid Interface Construction and pH Buffering Enabled Ultra-Stable Zinc Anode at High Current Density and Areal Capacity

In aqueous electrolytes, the uncontrollable interfacial evolution caused by a series of factors such as pH variation and unregulated Zn2+ diffusion would usually result in the rapid failure of metallic Zn anode. Considering the high correlation among various triggers that induce the anode deterioration, a synergistic modulation strategy based on electrolyte modification is developed. Benefitting from the unique pH buffer mechanism of the electrolyte additive and its capability to in situ construct a zincophilic solid interface, this synergistic effect can comprehensively manage the thermodynamic and kinetic properties of Zn anode by inhibiting the pH variation and parasitic side reactions, accelerating de-solvation of hydrated Zn2+ , and regulating the diffusion behavior of Zn2+ to realize uniform Zn deposition. Thus, the modified Zn anode can achieve an impressive lifespan at ultra-high current density and areal capacity, operating stably for 609 and 209 hours at 20 mA cm-2 , 20 mAh cm-2 and 40 mA cm-2 , 20 mAh cm-2 , respectively. Based on this exceptional performance, high loading Zn||NH4 V4 O10 batteries can achieve excellent cycle stability and rate performance. Compared with those previously reported single pH buffer strategies, the synergistic modulation concept is expected to provide a new approach for highly stable Zn anode in aqueous zinc-ion batteries.

Guiding Zn Uniform Deposition with Polymer Additives for Long-lasting and Highly Utilized Zn Metal Anodes

The parasitic side reaction on Zn anode is the key issue which hinders the development of aqueous Zn-based energy storage systems on power-grid applications. Here, a polymer additive (PMCNA) engineered by copolymerizing 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-acryloyl glycinamide (NAGA) was employed to regulate the Zn deposition environment for satisfying side reaction inhibition performance during long-term cycling with high Zn utilization. The PMCNA can preferentially adsorb on Zn metal surface to form a uniform protective layer for effective water molecule repelling and side reaction resistance. In addition, the PMCNA can guide Zn nucleation and deposition along 002 plane for further side reaction and dendrite suppression. Consequently, the PMCNA additive can enable the Zn//Zn battery with an ultrahigh depth of discharge (DOD) of 90.0 % for over 420 h, the Zn//active carbon (AC) capacitor with long cycling lifespan, and the Zn//PANI battery with Zn utilization of 51.3 % at low N/P ratio of 2.6.

Lithium Bis(oxalate)borate Additive for Self-repairing Zincophilic Solid Electrolyte Interphases towards Ultrahigh-rate and Ultra-stable Zinc Anodes

The artificial solid electrolyte interphase (SEI) plays a pivotal role in Zn anode stabilization but its long-term effectiveness at high rates is still challenged. Herein, to achieve superior long-life and high-rate Zn anode, an exquisite electrolyte additive, lithium bis(oxalate)borate (LiBOB), is proposed to in situ derive a highly Zn2+ -conductive SEI and to dynamically patrol its cycling-initiated defects. Profiting from the as-constructed real-time, automatic SEI repairing mechanism, the Zn anode can be cycled with distinct reversibility over 1800 h at an ultrahigh current density of 50 mA cm-2 , presenting a record-high cumulative capacity up to 45 Ah cm-2 . The superiority of the formulated electrolyte is further demonstrated in the Zn||MnO2 and Zn||NaV3 O8 full batteries, even when tested under harsh conditions (limited Zn supply (N/P≈3), 2500 cycles). This work brings inspiration for developing fast-charging Zn batteries toward grid-scale storage of renewable energy sources.