Zn Dendrites Research Articles

Alleviating zinc dendrite growth by versatile sodium carboxymethyl cellulose electrolyte additive to boost long-life aqueous Zn ion capacitors

Zn ion capacitors (ZICs) have become a strong candidate for energy storage equipment because the advantages of environment friendly, high safety, low cost. However, the Zn anode suffers from severe dendrite growth and irreversible side reactions, resulting in a short cycle life of ZICs. In this work, a green and low-cost sodium carboxymethyl cellulose (CMC-Na) is used as an additive in ZnSO4 electrolyte. The density functional theory calculations and molecular dynamics simulations demonstrate that CMC-Na can effectively optimize the electrolyte environment and regulate the electrode-electrolyte interface. Among them, Na+ has a lower redox site compared to Zn2+, Na+ can be reduced preferentially to Zn2+, the formation of the electrostatic protection layer can inhibit the formation of differential electric field and promote the uniform distribution of the electric field, which is conducive to the homogenization of the nucleation sites of the Zn deposition layer. The organic molecules contain abundant hydrophilic groups (OH, COO−), which can effectively optimize the structure of Zn2+ solvation sheath by destroying the hydrogen bonding network in the environment of ZnSO4 electrolyte, thus reducing the rate of side reactions and the random growth of dendrites will be suppressed. And the Zn//Zn cells with ZnSO4+CMC-Na(0.13) electrolyte enable to perform a stable cycle over 1600 h (at 4 mA cm−2 with a capacity of 1 mAh cm−2), which is vastly superior that of without additive (only 70 h). The results confirm that the import of CMC-Na additive into the ZnSO4 electrolyte can effectively prevent side reaction and achieve uniform deposition of Zn dendrites. The low-cost electrolyte additive provides an innovative strategy or the protection of Zn metal electrode in aqueous electrochemical energy storage devices.

Direct Growth of a Polymer Film to Induce Horizontal Orientation of Zn4(OH)6SO4·xH2O for Stable Zn Metal Batteries.

The loose and randomly oriented byproduct (i.e., Zn4(OH)6SO4·xH2O, ZHS) in situ formed on the zinc (Zn) surface is recognized to be the primary cause for dendritic Zn growth and side reactions. Switching the detrimental passivation film into a dense and kinetically favorable solid electrolyte interphase (SEI) is a straightforward strategy to tackle these issues faced by Zn metal anodes but remains largely unexplored. Herein, a new polymer film directly grown on Zn metal through room-temperature plasma-enhanced chemical vapor deposition is proposed to induce the lateral growth of ZHS nanosheets and decrease the Zn2+ desolvation barrier, thereby forming a beneficial composite SEI for suppressing Zn dendrite growth and surface corrosion. As a result of the joint effect, we realize an impressively stable cycling behavior in symmetric cell over 3400 h at 2 mA cm-2. Moreover, full cells also demonstrate prolonged lifespans. This work opens a new avenue for stabilizing Zn metal batteries by turning detrimental ZHS into a favorable interlayer.

Imidazole-2-carboxaldehyde additive participation in construction of SEI enabling ultra-stable Zn anode

Poor stability caused by side reactions such as corrosion, Zn dendrite and hydrogen evolution are crucial factors hindering commercial application in queous zinc ion energy storage systems. This article offers a strategy, zinc-rich Solid electrolyte interface (SEI) layer with polar groups by imidazole-2-carboxaldehyde (2-ICA) electrolyte additive, which helps form stable electrode/electrolyte interface and rapid Zn2+ transfer interface with low resistance. Firstly, the chelation with Zn2+ of 2-ICA and its zincophilic capability enable the rapid formation of the SEI layer and result in more sites for initial nucleation, which then guides the uniform Zn2+ deposition. Additionally, the introduced SEI with polar groups accelerates the de-solvation kinetics of Zn2+ and the Zn2+ transfer ability in electrode/electrolyte interface, which enable high-rate charge and discharge. Therefore, the symmetric battery based on 2-ICA electrolyte exhibits excellent cycling stability at 20 mA cm−2 (cycling up to 800 h). At the same time, assembled Zn//Cu also has a high average Coulombic efficiency (99.2 %). The zinc-ion hybrid capacitors (ZICs) assembled based on this electrolyte also exhibit outstanding electrochemical properties. This work offers a simple and novel way to realize high performance and great safety zinc-based energy storage devices.

Ternary Zn3V3O8 superstructure and synergistic modification of separator promote high performance and stable zinc ion battery

Aqueous zinc-ion batteries have attracted much attention from researchers owing to their safety and eminent energy density. However, the exploration of an appropriate cathode with high reversible capacity is still a huge challenge. In this manuscript, the ternary Zn3V3O8 superstructure with an energy density of 317 Wh kg−1 was successfully prepared with a micro-nano ternary hierarchical structure and the incorporation doping of nitrogen and carbon (ZVO@CN). Thanks to the multilevel morphology and high conductivity of carbon and nitrogen, the novel ZVO@CN cathode delivers the eminent reversible capacity of 192 mAh/g at 5 A/g after 2200 cycles for aqueous zinc ion battery. Importantly, the ex-situ XRD and XPS were adopted to explore the energy storage kinetics. Consequently, the pristine material is been transformed to Zn3(OH)2V2O7·2H2O in the initial charging at 1.3 V, and this phase transition is nonreversible. After the second cycle, the intercalation/extraction of Zn2+ in Zn3(OH)2V2O7·2H2O supplies the reversible capacity. Besides, to solve the rapid capacity delay caused by dendrite growth at low current density on the Zn anodes, the C3N4 coating Zn is prepared to modify the separator (Zn@C3N4@GF). It has effectively relieved the negative effect of Zn dendrite with highly improved stability. When the ZVO@CN and Zn@C3N4@GF were used as cathode and separator, the batteries exhibited a dominant discharge capacity of 235 mAh/g at 0.1 A/g after 380 cycles, only reducing the 50 mAh/g compared to the initial capacity. This means it only decreases the discharge capacity of 0.13 mA g−1 per cycle.

Boosting the reversibility of Zn anodes via synergistic cation–anion interface adsorption with addition of multifunctional potassium polyacrylate

Rechargeable aqueous Zn batteries have the edge in resource reserve, cost, energy and conversion efficiency due to the inherent features of metal Zn anodes. However, the application of Zn-based batteries is being seriously hindered by Zn dendrites and water-induced side-reactions. Here, potassium polyacrylate (K-PAM) is proposed as the electrolyte additive to form a synergistic cation–anion interface on Zn surface. The carboxyl anions and K+ cations are preferentially adsorbed on the Zn surface due to the intrinsic surfactant characteristics, which could homogenize Zn plating and suppress parasitic reactions. The synergistic regulation of K-PAM additive endows the ZnZn symmetric cells with excellent cyclic durability of 1250 h at 1 mA cm−2, which is significantly better than the polyacrylic acid additive only with carboxyl anions. Moreover, trace K-PAM addition into traditional ZnSO4 electrolyte endows the ZnCu batteries with a considerable average Coulombic efficiency of 99.2 %. Additionally, higher capacity retention and excellent cycling stability of ZnVO2 cells further mark K-PAM as a potentially impressive aqueous electrolyte additive for high-performance Zn-based batteries. This work will provide a promising method for the synergistic regulation with cations and anions of electrolyte additives to improve the stability and reversibility of Zn anodes.

Sodium Citrate Electrolyte Additive to Improve Zinc Anode Behavior in Aqueous Zinc-Ion Batteries

Despite features of cost-effectiveness, high safety, and superior capacity, aqueous zinc-ion batteries (ZIBs) have issues of uncontrolled dendritic cell failure and poor Zn utilization, resulting in inferior cycling reversibility. Herein, the environmentally friendly and naturally abundant sodium citrate (SC) was adopted as a dual-functional additive for ZnSO4-based (ZSO) electrolytes. Owing to the abundant hydrogen-bond donors and hydrogen-bond acceptors of SC, the Zn2+-solvation shell is interrupted to facilitate Zn desolvation, resulting in inhibited corrosion reactions. Additionally, sodium ions (Na+) from the SC additive with a lower effective reduction potential than that of zinc ions (Zn2+) form an electrostatic shield inhibiting the formation of initial surface protuberances and subsequent Zn dendrite growth. This assists in the Zn three-dimensional (3D) diffusion and deposition, thereby effectively enhancing cycling stability. Specifically, a long cycling lifespan (more than 760 h) of the Zn//Zn symmetric cell is achieved with a 2 M ZSO-1.0 SC electrolyte at a current density of 1 mA cm−2. When coupled with the NaV3O8·1.5 H2O (NVO) cathode, the full battery containing SC additive exhibited a capacity retention rate (40.0%) and a cycling life of 400 cycles at a current density of 1 A g−1 compared with that of pure ZnSO4 electrolyte (23.8%). This work provides a protocol for selecting an environmentally friendly and naturally abundant dual-functional electrolyte additive to achieve solvation shell regulation and Zn anode protection for the practical large-scale application of ZIBs.

Ion‐Sieving Effect Enabled by Sulfonation of Cellulose Separator Realizing Dendrite‐Free Zn Deposition

AbstractAqueous zinc‐ion batteries (AZIBs) hold great potential for grid‐scale energy storage systems, owing to their intrinsic safety and low cost. Nevertheless, their industrialization faces challenges of severe Zn dendrites and parasitic reactions. In this study, sulfonated cellulose separator (denoted as CF‐SO3) with low thickness, exceptional mechanical strength, and large ionic conductivity is developed. Benefiting from the electrostatic repulsion between ─SO3− functional groups and SO42− anions and the strongly interaction between ─SO3− and Zn2+ cations, the migration of SO42− anions can be restricted, the 2D diffusion of Zn2+ ions at the surface of Zn electrode can be suppressed, and the desolvation of hydrated Zn2+ ions can be promoted. Concurrently, the homogeneous nanochannels within CF‐SO3 separator can ensure uniform electric field and Zn2+ ion flux. With these benefits, the CF‐SO3 separator enables Zn//Zn cells to run stably for 1200 h at 4 mAh cm−2 by facilitating oriented and dendrite‐free Zn deposition. Under a large depth of discharge of 68.3%, a life span of 400 h can still be achieved. Additionally, the reliability of CF‐SO3 separator is confirmed in Zn//MnO2 and Zn//H11Al2V6O23.2 full batteries with high mass loading conditions. This work provides valuable guidance for the advancement of high‐performance separators of AZIBs.

An Iodine‐Chemisorption Binder for High‐Loading and Shuttle‐Free Zn–Iodine Batteries

AbstractAqueous zinc–iodine (Zn–I2) batteries have attracted considerable research interest as an alternative energy storage system due to their high specific capacity, intrinsic safety, and low cost. However, the notorious shuttle effect of soluble polyiodides causes severe capacity loss and poor electrochemical reversibility, restricting their practical usage. Herein, this study reports a bifunctional binder (polyacrylonitrile copolymer, as known as LA133) with strong iodine‐chemisorption capability for aqueous Zn–I2 batteries to suppress polyiodide shuttling. From both calculation and experimental data, this study reveals that the amide and carboxyl groups in LA133 binder can strongly bond to polyiodides, significantly immobilizing them at cathode side. As a result, fewer byproducts, slower hydrogen evolution, and lesser Zn dendrite in the Zn–I2 battery are observed. Consequently, the battery shows high specific capacity (202.8 mAh g−1) with high iodine utilization efficiency (96.1%), and long cycling lifespan (2700 cycles). At the high mass loading of 7.82 mg cm−2, the battery can still retain 83.3% of its initial capacity after 1000 cycles. The specific capacity based on total cathode slurry mass reaches 71.2 mAh g−1, higher than most of the recent works. The strategy opens a new avenue to address the shuttling challenge of Zn–I2 batteries through bifunctional binder.

High-Fluidity/High-Strength Dual-Layer Gel Electrolytes Enable Ultra-Flexible and Dendrite-Free Fiber-Shaped Aqueous Zinc Metal Battery.

Fiber-shaped aqueous zinc-ion batteries (FAZIBs) with intrinsic safety, highcapacity, and superb omnidirectional flexibility hold promise for wearable energy-supply devices. However, the interfacial separation of fiber-shaped electrodes and electrolytes caused by Zinc (Zn) stripping process and severe Zn dendrites occurring at the folded area under bending condition seriously restricts FAZIBs' practical application. Here, an advanced confinement encapsulation strategy is originally reported to construct dual-layer gel electrolyte consisting of high-fluidity polyvinyl alcohol-Zn acetate inner layer and high-strength Zn alginate outer layer for fiber-shaped Zn anode. Benefiting from the synergistic effect of inner-outer gel electrolyte and the formation of solid electrolyte interphaseon Zn anode surface by lysine additive, the resulting fiber-shaped Zn-Zn symmetric cell delivers long cycling life over 800h at 1 mA cm-2 with dynamic bending frequency of 0.1Hz. The finite element simulation further confirms that dual-layer gel electrolyte can effectively suppress the interfacial separation arising from the Zn stripping and bending process. More importantly, a robust twisted fiber-shaped Zn/zinc hexacyanoferrate battery based on dual-layer gel electrolyte is successfully assembled, achieving a remarkable capacity retention of 97.7% after bending 500 cycles. Therefore, such novel dual-layer gel electrolyte design paves the way for the development of long-life fiber-shaped aqueous metal batteries.

Arrays of Hierarchical Zincophilic Nanorods with Trapping‐and‐Leveling Deposition for Ultrastable Zn Metal Anodes

AbstractRechargeable aqueous zinc‐ion batteries (ZIBs) are highly promising for large‐scale sustainable energy storage applications, but there remain serious problems such as Zn dendrites and side reactions that limit the cycling performance. Herein, arrays of core–shell nanorods on Cu foam are developed to stabilize zinc anodes, which have a hierarchical topological structure consisting of N‐doped carbon layers embedded with a zincophilic component of Cu5Zn8 alloy (Cu5Zn8@NC). It is found that the inner Cu5Zn8 alloys have minimized nucleation barriers and act as preferred nucleation sites, and the hierarchical arrays provide the protective layers to further accommodate the high‐capacity plating Zn, leading to a trapping‐and‐leveling process of Zn deposition. The as‐obtained Zn layers play an important role in homogenizing the interfacial ionic fluxes and reducing the local current densities. As a result, the optimized Cu5Zn8@NC host yields a superb Coulombic efficiency of 99.7% over 5000 plating/stripping cycles, and the corresponding symmetric cell delivers an ultralong dendrite‐free cycle life of 7000 h with a low overpotential of 16.5 mV at 1 mA cm−2 and 1 mAh cm−2. The ZIB assembled with the zinc anode and a V2O5 cathode exhibits long‐term charging/discharging cycles as well, up to 89.2% capacity retention after 10 000 cycles.

Facile Electrolytic (111)‐Textured Copper Foil for Dendrite‐Free Zinc Metal Batteries

AbstractAqueous Zn metal batteries are emerging as a promising candidate for the next‐generation largescale energy storage system due to their high safety, low lost, and eco‐friendliness. Nevertheless, their practical application is restricted by the uncontrollable Zn dendrite growth and the limited utilization of the Zn metal anode. Herein, a room temperature electrodeposition strategy based on an optimized rate relationship between the diffusion and consumption of Cu2+ to prepare a (111)‐textured Cu current collector for the construction of the dendrite‐free Zn metal anode with high reversibility is developed. Attributed to the high lattice match between the (002) facet of Zn with the (111) facet of Cu, the deposition of Zn along its [001] orientation is achieved on the (111)‐textured Cu. The (002) facets horizontally aligned with the current collector endow Zn with the dendrite‐free planar construction and superior corrosion resistance, resulting in a high reversibility with a long life‐span over 2186 cycles. Impressively, the resultant Zn anodes can stabilize the operation of pouch cells with an extremely demanding negative‐to‐positive capacity ratio of 2. This work provides a new avenue for the development of the current collectors for the low‐cost sustainable energy storage.

Spatial Confinement of Sn/TiO2 Nanoparticles in Hollow Mesoporous Carbon Spheres Opal for Stable Zn Metal Anodes

AbstractThe sluggish Zn2+ diffusion and high nucleation energy barrier induce uncontrolled growth of Zn dendrites and detrimental parasitic reactions, severely hampering the commercialization of Zn metal anodes (ZMAs). Herein, hollow mesoporous carbon sphere opal with confined Sn/TiO2 clusters (HMCSST) is designed as the host to spatially regulate the Zn deposition. Owing to the capillary effect of the ordered hierarchical porous structure, the mass diffusion can be dramatically accelerated to promote a fast deposition kinetics at the interface between ZMA and electrolyte. Besides, the encapsulated ultrafine Sn/TiO2 clusters serve as zincophilic sites to achieve both the uniform Zn deposition on the hierarchical porous opal host and the high thermodynamic stability of ZMAs. Benefiting from the structural and componential merits, the HMCSST host effectively reduces the activation energy to enable a temporal‐spatial ordering of Zn nucleation and growth. As expected, the stable HMCSST‐Zn electrode guarantees steady Zn platting/stripping with long‐term stability over 1300 h in a symmetrical cell at a depth of discharge of 37.5%. As a proof‐of‐concept demonstration, an HMCSST‐Zn||ammonium vanadate full cell shows a long lifespan over 5000 cycles at 10.0 A g−1 with low polarization.

Flexible Zn-ion Electrochromic Batteries with Multiple-color Variations.

Electrochromic batteries as emerging smart energy devices are highly sought after owing to their real-time energy monitoring through visual color conversion. However, their large-scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn-ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion-redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored -SO3 - and -NH3 +, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn2+ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid-charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g-1 at 0.05 A ⋅ g-1 with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g-1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.

Flexible Zn‐ion Electrochromic Batteries with Multiple‐color Variations

AbstractElectrochromic batteries as emerging smart energy devices are highly sought after owing to their real‐time energy monitoring through visual color conversion. However, their large‐scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn‐ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion‐redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored −SO3− and ‐NH3+, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn2+ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid‐charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g−1 at 0.05 A ⋅ g−1 with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g−1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.

Dendrite-free zinc deposition enabled by MXene/nylon scaffold and polydopamine solid-electrolyte interphase for flexible zinc-ion batteries

The rapid growth of wearable and portable electronic devices calls for energy storage devices with good flexibility, high energy density, and safety. Rechargeable aqueous Zn ion batteries (ZIBs) with the merits of environmental benignity, high safety, and low cost have arisen as promising energy storage candidates for wearable electronic systems. However, the unstable Zn anode interface and notorious Zn dendrite formation hinder the application of flexible ZIBs. Herein, a highly stable and flexible Zn anode is developed by taking advantage of highly conductive Ti3C2 MXene coated nylon fabric (MXNY) as a three-dimensional (3D) Zn deposition skeleton and polydopamine (PDA) as a solid electrolyte interface (SEI). The combination of MXNY and PDA SEI provides synergistic benefits such as a stabilized interface for homogenous and dendrite-free Zn deposition and improved corrosion resistance. As a result, a flexible and stable Zn anode with improved Coulombic efficiency of 99.6 % at a current density of 10 mA cm–2 for 1 mA h cm–2, and long cycling stability of more than 3000 h at a current density of 0.5 mA cm–2 for 0.5 mA h cm–2 can be achieved. When paired with a flexible cathode, the quasi-solid-state ZIB can power various electronic devices under different mechanical deformations, indicating its promising potential as flexible energy storage devices for wearable and portable electronics.

Enabling Stable Zn Anode with PVDF/CNTs Nanocomposites Protective Layer Toward High‐Performance Aqueous Zinc‐Ion Batteries

AbstractDue to its abundance of natural resources, high theoretical capacity, and suitable redox potential (−0.76 V vs SHE), Zn anode has received extensive attention both from academy and industry. However, the coexistence of Zn and H2O, which is unfortunately thermodynamically unstable, always involves severe metal corrosion, H2 evolution, dendrite growth, resulting in low reversibility of Zn anode. Herein, a phase transfer method is adapted to design a porous conductive protective layer on the Zn anode, denoted as (PVDF (Polyvinylidene fluoride)/CNTs(Carbon Nanotubes)‐PT(phase transfer) @ Zn). Based on in situ characterization, COMSOL simulation, and migration energy barrier calculation, it can be demonstrated that PVDF/CNTs‐PT @ Zn effectively inhibited the production of Zn dendrites and the side reactions triggered by H2O, achieving uniform deposition. Especially, the full picture of Zn deposition is observed using in situ computed tomography (CT). The symmetrical cell using the PVDF/CNTs‐PT @ Zn demonstrates dendrite‐free plating/stripping and possesses much better cycle stability than the bare Zn. A stable rechargeable full battery is demoed through coupling the PVDF/CNTs‐PT @ Zn anode with commercial V2O5. The strategy showcases a feasible pathway to inhibit Zn dendrite and side reactions in aqueous Zn ion battery, opening a promising avenue for the construction of metal anode protection layer.

Synergistically regulating Zn-ion flux and accelerating ion transport kinetics via zincophilic covalent organic framework interlayer for stable Zn metal anode

Zn metal is considered as an ideal anode for aqueous zinc-ion batteries (AZIBs) owing to the inherent merits of low cost, high theoretical capacity, and remarkable safety. However, the formation of Zn dendrites and water-induced parasitic reactions hamper the commercialization of AZIBs. Herein, a synergetic strategy to accelerate ion transfer kinetics and regulate Zn-ion flux has been proposed to achieve dendrite-free Zn anodes via a series of zincophilic covalent organic framework (COF) films. The nanoporous and mechanically stable COF films synthesized by the liquid–liquid interfacial polymerization can be straightforward transferred on the Zn foil surface through a dip-coating technique. Benefiting from the affinity between Zn2+ and electron-rich ketone, the zincophilic COF interlayers promote the de-solvation of hydrated Zn2+, simultaneously offer ample Zn2+ transport channels to facilitate rapid diffusion and regulating a homogenous Zn2+ flux, thereby inhibiting the dendritic growth and leading to the uniform Zn deposition. Additionally, the COF films with strong adherence and large surface area effectively separate Zn anodes from bulk aqueous electrolytes, inhibiting the water-induced corrosion reactions. As a result, the symmetric cell with COF-modified Zn anode exhibited a stable cycling lifetime more than 900 h at 1 mA∙cm−2 and 1 mAh∙cm−2, accompanied by a low voltage polarization of merely 74.3 mV. As a simple approach to synergistically restrict Zn-ion flux and enhance ion transport kinetics using zincophilic COF films via interfacial synthesis, this work would provide new insights into developing highly stable Zn anodes.

Natural honey helps stabilize zinc anode for dendrite-free aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have garnered significant attention as energy storage devices due to their high theoretical capacity, low cost, and superior safety. However, uncontrolled Zn dendrite growth and parasitic side reactions have hindered their practical applications. Herein, a novel low-cost and non-toxic electrolyte additive, honey, is incorporated into the typical ZnSO4 electrolyte to stabilize the Zn anode for high performance AZIBs. Both simulation and experimental results suggest that the natural honey additive can regulate the interaction of Zn2+ with SO42− and H2O molecules, thereby promoting the desolvation of Zn2+. Concurrently, glucose and fructose molecules in honey tend to absorb onto the Zn anode, facilitating the uniform deposition of Zn2+. Therefore, the honey additive can effectively inhibit the growth of Zn dendrites and side reactions. As expected, the Zn-symmetric cell with ZnSO4-honey electrolyte achieves excellent Zn stripping/plating reversibility, maintaining stable potentials over 2000 h at 1 mA cm−2 and nearly 1200 h at 5 mA cm−2. When coupling with MnO2 cathode, the full cell with the honey additive also displays improved long-term durability. Furthermore, the packaged pouch cell demonstrates surprising flexibility and satisfactory security under different harsh environments, showing practical feasibility in future wearable devices.

Electrolyte Solvation Chemistry for Stabilizing the Zn Anode via Functionalized Organic Agents.

As a potential candidate for grid-scale energy storage technology, aqueous Zn-ion batteries (ZIBs) have attracted considerable attention due to their intrinsic safety, environmental friendliness, and ease of fabrication. Nevertheless, the road to industry for this technique is hindered by serious issues, including undesired side reactions, random growth of the Zn dendrites, electrode passivation, and anode corrosion, which are associated with the high reactivity of water molecules during the electrochemical reactions. These challenges are strongly dependent on electrolyte solvation chemistry (ESC), which subsequently determines the electrochemical behavior of the metal ions and water molecules on the electrode surface. In this work, a comprehensive understanding of optimized ESC with specified functional groups on the mixing agents to stabilize the Zn anode is provided. First, the challenges facing the ZIBs and their chemical principles are outlined. Specific attention is paid to the working principles of the mixing agents with different functional groups. Then the recent progress is summarized and compared. Finally, perspectives on future research for the aqueous Zn batteries are presented from the point of view.

Suppressing Zn pulverization with three-dimensional inert-cation diversion dam for long-life Zn metal batteries

Tremendous attention has been paid to the water-associated side reactions and zinc (Zn) dendrite growth on the electrode-electrolyte interface. However, the Zn pulverization that can cause continuous depletion of active Zn metal and exacerbate hydrogen evolution is severely neglected. Here, we disclose that the excessive Zn feeding that causes incomplete crystallization is responsible for Zn pulverization formation through analyzing the thermodynamic and kinetics process of Zn deposition. On the basis, we introduce 1-ethyl-3-methylimidazolium cations (EMIm+) into the electrolyte to form a Galton-board-like three-dimensional inert-cation (3DIC) region. Modeling test shows that the 3DIC EMIm+ can induce the Zn2+ flux to follow in a Gauss distribution, thus acting as elastic sites to buffer the perpendicular diffusion of Zn2+ and direct the lateral diffusion, thus effectively avoiding the local Zn2+ accumulation and irreversible crystal formation. Consequently, anti-pulverized Zn metal deposition behavior is achieved with an average Coulombic efficiency of 99.6% at 5 mA cm-2 over 2,000 cycles and superb stability in symmetric cell over 1,200 h at -30 °C. Furthermore, the Zn||KVOH pouch cell can stably cycle over 1,200 cycles at 2 A g-1 and maintain a capacity of up to 12 mAh.