Zinc Dendrites Research Articles

In‐Situ Ultrafast Construction of Zinc Tungstate Interface Layer for Highly Reversible Zinc Anodes

AbstractConstructing artificial solid electrolyte interface on the Zn anode surface is recognized as an appealing method to inhibit zinc dendrites and side reactions, whereas the current techniques are complex and time‐consuming. Here, a robust and zincophilic zinc tungstate (ZnWO4) layer has been in situ constructed on the Zn anode surface (denoted as ZWO@Zn) by an ultrafast chemical solution reaction. Comprehensive characterizations and theoretical calculations demonstrate that the ZWO layer can effectively modulate the interfacial electric field distribution and promote the Zn2+ uniform diffusion, thus facilitating the uniform Zn2+ nucleation and suppressing zinc dendrites. Besides, ZWO layer can prevent direct contact between the Zn/water and increase the hydrogen evolution reaction overpotential to eliminate side reactions. Consequently, the in situ constructed ZWO layer facilitates remarkable reversibility in the ZWO@Zn||Ti battery, achieving an impressive Coulombic efficiency of 99.36 % under 1.0 mA cm−2, unprecedented cycling lifespan exceeding 1800 h under 1.0 mA cm−2 in ZWO@Zn||ZWO@Zn battery, and a steady and reliable operation of the overall ZWO@Zn||VS2 battery. The work provides a simple, low cost, and ultrafast pathway to crafting protective layers for driving advancements in aqueous zinc‐metal batteries.

An Ionic Liquid Supramolecular Gel Electrolyte with Unique Wide Operating Temperature Range Properties for Zinc-Ion Batteries.

Zinc-ion batteries are promising candidates for large-scale energy storage. The side reactions of the hydrogen evolution reaction (HER) and zinc dendrite growth are major challenges for developing high-performance zinc-ion batteries. In this paper, a supramolecular gel electrolyte (BLO-ILZE) was self-assembled in an ionic liquid (EMIMBF4) with zinc tetrafluoroborate (Zn(BF4)2) on the separator in situ to obtain a gel electrolyte used in zinc-ion batteries. BLO-ILZE is demonstrated to significantly enhance conductivity over a broad temperature range between -70 and 100 °C. Interestingly, through testing and fitting, it is found that the supramolecular gel electrolyte satisfies the liquid state law over a wide temperature range, and even achieves high conductivity (2.12 mS cm-1) at -40 °C. It is equivalent to the conductivity of aqueous zinc-ion batteries (ZnSO4/H2O) at -10 °C, which is 2.33 mS cm-1. Moreover, the supramolecular gel electrolyte can effectively inhibit the HER, thus exhibiting a longer lifetime in Zn/Zn cells for 3470 h at 1 mA cm-2 compared to the aqueous zinc-ion batteries with the Zn(BF4)2 aqueous electrolyte (400 h at 1 mA cm-2). The assembled V2O5/BLO-ILZE/Zn full cells also showed cycling performance, with 5000 cycles at 0.5 mA g-1 at room temperature, a capacity of 98%, and a coulombic efficiency of about 100%.

The impact of surface functional groups on MXene anode protective layer in aqueous zinc-ion batteries: Understanding the mechanism

The development of energy storage has seen a significant increase in the use of aqueous zinc-ion batteries (AZIBs) with intrinsic safety, which have become an important choice for new high-security energy storage. However, the dendrite growth and hydrogen evolution reaction (HER) on Zn anodes present a significant challenge to the commercialisation of AZIBs. The stability of Zn anodes can be effectively improved by using an anodic interfacial protective layer. The novel two-dimensional (2D) MXene material is capable of effectively inhibiting zinc dendrite growth and the HER reaction when employed as a protective layer for AZIBs anodes due to its readily adjustable properties. The surface functional groups of MXene exhibit different electrochemical properties in different electrolytes, which affects the realization of the protective function. The current understanding of the influence of these surface functional groups on the monolayer MXene as an anodic protective layer for AZIBs is incomplete. A combination of density functional theory calculations and molecular dynamics simulations was employed to investigate the electronic properties, adsorption energies for Zn2+ and H2O, free energies for HER, Zn2+ diffusion energy barriers, Zn2+ diffusion coefficients, and coordination numbers of Zn2+ with water molecules of monolayer MXene (Mo2CTx) with nine different surface functional groups were investigated. The mechanism of the impact of surface functional groups on monolayer Mo2CTx as an anodic protective layer for AZIBs was elucidated. This study will provide guidance for the extensive use of MXene materials in AZIBs to effectively enhance the anode stability and prolong the battery operation life.

Regulating the solvation structure of Zn2+ via glycine enables a long-cycling neutral zinc-ferricyanide flow battery

Zinc-based flow batteries hold potential promise for extensive energy storage on a large scale owing to their high energy density and low cost. However, their widespread implementation is impeded by challenges associated with zinc (Zn) dendrites and side reactions like the hydrogen evolution reaction on the anode. Theoretical calculations have confirmed that glycine (Gly) has the ability to coordinate with Zn2+, displacing H2O molecules in the solvation shell, thereby restoring the solvation structure of Zn2+ and promoting the release of reactive Zn2+ during plating/stripping processes. As a result, the incorporation of Gly into the anolyte of a neutral zinc-ferricyanide (Zn/Fe) flow battery (ZIFB) effectively inhibits the formation of Zn dendrites and impedes side reactions, leading to highly reversible and stable Zn plating/stripping reactions. A Zn||Zn symmetric flow battery utilizing Gly in the anolyte demonstrated extended cycling durability, lasting over 550 h at a current density of 30 mA cm−2, in contrast to the failure of a Gly-free anolyte system after 150 h. Notably, this approach facilitates a neutral ZIFB achieving an impressive energy efficiency exceeding 70 %, even at a high current density of 70 mA cm−2, with a cycle lifespan exceeding 800 h (33 days) at a current density of 30 mA cm−2. Conversely, the neutral ZIFB lacking Gly showed a significantly shorter cycle life of only 260 h under identical operational conditions (30 mA cm−2). Due to the economic benefits of Gly and the proposed user-friendly route, this strategy demonstrates great potential for promoting the widespread adoption of zinc-based flow batteries with improved performance for practical use.

The Burgeoning Zinc Powder Anode for Aqueous Zinc Metal Batteries: from Electrode Preparation to Performance Enhancement

AbstractAqueous zinc metal batteries (AZMBs) have emerged as a focal point of interest in academic research and industrial strategic planning. Zinc powder (ZP) is poised to assume a prominent position in both future research and practical applications due to its high Zn utilization rate and processability. However, critical challenges need to be addressed before realizing substantial progress. Notably, severe voltage polarization and gas production of ZP electrodes stand out as the primary causes of battery failure, differing with zinc foil where short circuits caused by zinc dendrites contribute to battery failure. While numerous comprehensive reviews have offered effective strategies for zinc foil, a systematic summary of ZP electrodes is still lacking. For ZP, electrode preparation dictates the performance. This review summarizes the criteria for optimal ZP electrodes, covering electrode components, preparation methods, and technique parameters. It emphatically introduces the underlying causes and strategies of water‐related side reactions and briefly analyzes the stripping/plating behaviors of ZP electrodes. The status quo of ZP‐based batteries is then discussed in categories of ZP, current collector, conductive scaffold, binder, and electrolytes. Finally, potential avenues for future research are proposed from three aspects to enhance the focus on ZP electrodes and facilitate the practical application of AZMBs.

The synergistic effect of PVA-based gel electrolyte and Cu2+ on the optimization of zinc anode

In practical applications, rechargeable aqueous zinc ion batteries (AZIBs) face challenges such as battery leakage and pronounced dendrite growth on the zinc anode, primarily due to the absence of superior electrolyte materials. These issues significantly impact the longevity and reliability of AZIBs. To address these problems, we have designed a novel Zn(CF3SO3)2-polyvinyl alcohol(PVA)-Cu(CF3SO3)2 gel electrolyte(CPVF) consisting of poly(vinyl alcohol) (PVA) synergized with Cu2+. This innovative electrolyte not only effectively prevents leakage, a common issue with conventional electrolytes, but also promotes the uniform deposition of zinc ions. The ordered porous structure within the PVA matrix restricts the uncontrolled growth of zinc dendrites, while the Cu2+ in the gel offer a multitude of uniform zinc-philic sites in the form of Cu0 on the zinc anode. As a result, the Zn//CPVF//Zn symmetrical battery demonstrates remarkable cycling stability, with a lifespan exceeding 1200 h at 1 mA/cm2 and 0.5 mAh/cm2. Furthermore, the Zn//CPVF//V2O5 full cell retains 82.6 % of its capacity after 500 cycles at 1 A/g. The research results provide guidance for the design and optimization of high-performance and low-cost AZIBs electrolyte materials.

High‐Performance Zinc Anode Enabled by Zincophilic and Hydrophobic ZnO@Nitrogen‐Doped Carbon/MXene Interface

Aqueous zinc‐ion batteries (AZIBs) are one of the most promising systems for large‐scale energy storage, but their zinc metal anodes suffer from unsatisfactory stability and reversibility due to the uncontrollable Zn dendrite growth and undesirable side reactions. Herein, a ZnO‐anchored nitrogen‐doped carbon/Ti3C2Tx MXene composite (ZnO@NC/MXene) is developed as a protective layer onto the zinc anode, which establishes a zincophilic and hydrophobic interface. In the ZnO@NC/MXene layer, the nitrogen sites efficiently enhances the adsorption of Zn2+, the ZnO provides homogenous nucleation sites for Zn2+ deposition, and the highly conductive MXene ensures even electric field distribution, synergistically inhibiting the zinc dendrites. Additionally, the hydrophobic ZnO@NC/MXene layer suppresses side reactions by limiting contact between the Zn anode and active water. Therefore, the Zn electrode modified by the ZnO@NC/MXene layer shows remarkable stability with a cycle life of over 2600 h in Zn||Zn symmetric cell and outstanding reversibility with an average coulombic efficiency of 99.37% for over 1000 cycles in Zn||Cu asymmetric cell. Coupled with V2O5 cathode, the full cell reveals excellent cycle stability of exceeding 1000 cycles at 4 A g‐1. These results indicate the potential of the zincophilic and hydrophobic ZnO@NC/MXene as a promising interface layer for protecting Zn anode in AZIBs.

New Alkalescent Electrolyte Chemistry for Zinc‐Ferricyanide Flow Battery

AbstractAlkaline zinc‐ferricyanide flow batteries are efficiency and economical as energy storage solutions. However, they suffer from low energy density and short calendar life. The strongly alkaline conditions (3 mol L−1 OH−) reduce the solubility of ferri/ferro‐cyanide (normally only 0.4 mol L−1 at 25 °C) and induce the formation of zinc dendrites at the anode. Here, we report a new zinc‐ferricyanide flow battery based on a mild alkalescent (pH 12) electrolyte. Using a chelating agent to rearrange ferri/ferro‐cyanide ion‐solvent interactions and improve salt dissociation, we increased the solubility of ferri/ferro‐cyanide to 1.7 mol L−1 and prevented zinc dendrites. Our battery has an energy density of ~74 Wh L−1catholyte at 60 °C and remains stable for 1800 cycles (1800 hours) at 0 °C and for >1400 cycles (2300 hours) at 25 °C. An alkalescent zinc‐ferricyanide cell stack built using this alkalescent electrolyte stably delivers 608 W of power for ~40 days.

New Alkalescent Electrolyte Chemistry for Zinc-Ferricyanide Flow Battery.

Alkaline zinc-ferricyanide flow batteries are efficiency and economical as energy storage solutions. However, they suffer from low energy density and short calendar life. The strongly alkaline conditions (3 mol L-1 OH-) reduce the solubility of ferri/ferro-cyanide (normally only 0.4 mol L-1 at 25 °C) and induce the formation of zinc dendrites at the anode. Here, we report a new zinc-ferricyanide flow battery based on a mild alkalescent (pH 12) electrolyte. Using a chelating agent to rearrange ferri/ferro-cyanide ion-solvent interactions and improve salt dissociation, we increased the solubility of ferri/ferro-cyanide to 1.7 mol L-1 and prevented zinc dendrites. Our battery has an energy density of ~74 Wh L-1 catholyte at 60 °C and remains stable for 1800 cycles (1800 hours) at 0 °C and for >1400 cycles (2300 hours) at 25 °C. An alkalescent zinc-ferricyanide cell stack built using this alkalescent electrolyte stably delivers 608 W of power for ~40 days.

Low-Cost Aqueous Electrolyte with MBA Additives for Uniform and Stable Zinc Deposition.

Aqueous zinc ion batteries (AZIBs) are attracting increasing research interest due to their intrinsic safety, low cost, and scalability. However, the issues including hydrogen evolution, interface corrosion, and zinc dendrites at anodes have seriously limited the development of aqueous zinc ion batteries. Here, N,N-methylenebis(acrylamide) (MBA) additives with -CONH- groups are introduced to form hydrogen bonds with water and suppress H2O activity, inhibiting the occurrence of hydrogen evolution and corrosion reactions at the interface. In situ optical microscopy demonstrates that the MBA additive promotes the uniform deposition of Zn2+ and then suppresses the dendrite growth on the zinc anode. Therefore, Zn//Ti asymmetric batteries demonstrate a high plating/stripping efficiency of 99.5%, while Zn//Zn symmetric batteries display an excellent cycle stability for more than 1000 h. The Zn//MnO2 full cells exhibit remarkable cycling stability for 700 cycles in aqueous electrolytes with MBA additives. The additive engineering via MBA achieved the dendrite-free Zn anodes and stable full batteries, which is favorable for advanced AZIBs in practical applications.

Regulation of Zn2+ solvation shell by a novel N-methylacetamide based eutectic electrolyte toward high-performance zinc-ion batteries

Aqueous Zn-ion batteries (AZIBs) have been regarded as promising alternatives to Li-ion batteries due to their advantages, such as low cost, high safety, and environmental friendliness. However, AZIBs face significant challenges in limited stability and lifetime owing to zinc dendrite growth and serious side reactions caused by water molecules in the aqueous electrolyte during cycling. To address these issues, a new eutectic electrolyte based on Zn(ClO4)2·6H2O-N-methylacetamide (ZN) is proposed in this work. Compared with aqueous electrolyte, the ZN eutectic electrolyte containing organic N-methylacetamide could regulate the solvated structure of Zn2+, effectively suppressing zinc dendrite growth and side reactions. As a result, the Zn//NH4V4O10 full cell with the eutectic ZN-1-3 electrolyte demonstrates significantly enhanced cycling stability after 1000 cycles at 1 A g−1. Therefore, this study not only presents a new eutectic electrolyte for zinc-ion batteries but also provides a deep understanding of the influence of Zn2+ solvation structure on the cycle stability, contributing to the exploration of novel electrolytes for high-performance AZIBs.

Revealing the alkali ions effects in potential shift and Zn dendrites suppression via electrolyte concentration regulation in aqueous zinc ion batteries

The energy density of aqueous reachable batteries (ARBs) is limited by the output voltage in the aqueous electrolyte. Herein, low-cost aqueous hybrid electrolytes composed of ZnSO4 and K2SO4 dual salts effectively improve the output voltage and suppress the zinc dendrites. The aqueous full cells assembled with potassium zinc hexacyanoferrate (KZnHCF) cathodes and zinc foil anodes reach an output voltage of 1.92 V and an energy density of 107.6 Wh kg−1. It is demonstrated the reversible insertion/extraction of K+ at the cathodes and uniform zinc deposition/striping at the anode in hybrid electrolyte via a series in-situ and ex-situ investigation. The dual salt electrolyte can not only satisfy the reversible capacitive dominated process at the cathodes but also suppress the zinc dendrite. Density functional theory (DFT) calculation demonstrates the K+ preferential intercalation mechanism of KZnHCF in hybrid electrolyte and the inhibition effect of K+ insertion on Zn2+ insertion. This strategy presents a promising approach for development of high performance and low-cost aqueous electrolyte.

Oligopeptide‐Induced Multifunctional Interface Layer with Protonated Hydrophobic Behavior and Strong Affinity for Highly Stable Zinc Anode

AbstractZinc‐ion batteries (ZIBs) have attracted wide attention due to their low redox potential, high capacity, and intrinsic safety. However, key issues such as zinc dendrite growth, corrosion, and passivation on zinc anode detrimentally affect the electrochemical performance. Herein, as proof of a concept of oligopeptide, glutathione with functional groups including –NH2 and −SH is introduced as an electrolyte additive to construct a multifunctional electrode–electrolyte interface layer on the zinc anode. A protonated amino group (NH3+) is formed, which prevents the adsorption of water molecules on the Zn anode, building a hydrophobic interface layer and thus attenuating corrosion. Moreover, the strong interaction between the −SH and the zinc allows glutathione molecules to be tightly anchored to the electrode surface, constructing a robust interface layer. Consequently, a long cycling life of nearly 3000 h at 1 mA cm−2 for the Zn||Zn symmetric battery is achieved, and a stable cycling life of 1600 h is demonstrated at 3 mA cm−2. Furthermore, Zn||activated carbon (AC) hybrid capacitor with the glutathione‐containing electrolyte runs stably for nearly 28 000 cycles at 5 A g−1, among the best results of reported Zn hybrid capacitors.

Modulation of zinc deposition behaviour by electrostatically spun PAN-ZnTFSI fibre layer on separator for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) are well-suited for current energy storage technologies due to their high safety and low cost. However, battery failures resulting from dendrites and side reactions restrict their widespread application. Here, we designed a polyacrylonitrile (PAN)-zinc trifluoromethanesulfonate (ZnTFSI) nanofibre synergistic glass fibre (PZ-GF) to modulate the interfacial deposition kinetics. The effective coordination of numerous CN functional groups within PZ, in conjunction with Zn2+, results in the homogeneous dispersion of the electric field across the electrode, which promotes the uniform deposition of Zn2+ on the zinc anode and thus significantly inhibits the rapid growth of zinc dendrites. ZnTFSI is hydrophilic and has strong hydrogen bonding interactions with the H2O molecule so that the separator can be used as a molecular sieve to regulate the flux of H2O, promote the desolvation of hydrated zinc ions, and inhibit side reactions.Tests of the initial nucleation overpotential of the symmetric battery and calculation of the activation energy reflect that PZ-GF has a smaller nucleation energy barrier and enhanced kinetic effect. And the zinc symmetric battery with PZ-GF film shows an ultra-long cycle stability of 1200 cycles with a capacity retention of 75 % even at 0.5 A g−1 for the Zn//VO2 full cells.

Reconfiguring the Electrolyte Network Structure with Bio‐Inspired Cryoprotective Additive for Low‐Temperature Aqueous Zinc Batteries

AbstractDespite promising performance at ambient temperature, the development of aqueous zinc batteries is jeopardized by the freeze of aqueous electrolytes and deteriorative electrode‐electrolyte interphase at low temperatures. Herein, inspired by the cryoprotective mechanism of extracellular polysaccharides in biological organisms, a quaternized galactomannan polysaccharide (q‐GPA) is proposed as a cryoprotective additive for improving low‐temperature performance of aqueous zinc batteries. Mechanistic studies revealed that a multi‐hydroxyl galactomannan backbone can substantially attenuate the activity of water molecules through the reconfiguration of the hydrogen bond network, which inhibits ice crystal formation at subzero temperatures and thus depress the freezing point of the electrolyte. Meanwhile, the quaternary ammonium groups tethered on the q‐GPA skeleton are intended to neutralize the interfacial electric field through electrostatic repulsion, thereby accelerating Zn2+ deposition kinetics and prohibiting zinc dendrite growth. Impressively, the q‐GPA–modified electrolyte enables an extended lifespan of over 1700 h in Zn||Zn symmetric battery at a high current density of 3 mA cm−2 and an ultralong cycle life of 5000 cycles with a capacity retention of 99.2% in the Zn||Na2V6O16·1.5H2O (NVO) full battery at −30 °C. This work provides unprecedented possibilities for optimizing the electrolyte formulation of low‐temperature aqueous batteries.

Zincophilic and hydrophobic groups of surfactant-type electrolyte additive enabled stable anode/electrolyte interface toward long-lifespan aqueous zinc ion batteries

Rechargeable aqueous zinc-ion batteries, while promising in terms of safety, cost-effectiveness, and eco-friendliness, face challenges such as zinc dendrite growth and parasitic reactions at the anode/electrolyte interface. Herein, a low-cost cationic surfactant, dodecyltrimethyl ammonium chloride (DTAC) is deployed as a competitive additive in traditional ZnSO4 electrolyte to stabilize the zinc anode. Firstly, the DTAC additive disrupts the hydrogen bonding network and regulates the solvation structure. Secondly, the DTA+ cations preferentially adsorb onto the anode surface vertically, forming a dodecyl chain hydrophobic layer that suppresses the side reactions. Thirdly, the hydrophobic layer not only elevates the nucleation overpotential of Zn2+ ions but also limits their 2D diffusion at the anode surface, triggering oriented deposition of metal zinc and inhibiting dendrite growth. Leveraging these triple-regulation effects, the Zn//Zn symmetric cell with DTAC additives achieves an ultra-long cycle life of 2000 h at a current density of 1 mA cm−2 with 1 mAh cm−2. Furthermore, the Zn//MnO2 full cell with DTAC additive demonstrates promising performance, delivering an initial capacity of 149.44 mAh g−1 at 5 A g−1 and retaining 83.02 % of its capacity after 2000 cycles. These results underscore the potential of DTAC additives in advancing the industrialization of AZIBs.

Wood-inspired anisotropic hydrogel electrolyte with large modulus and low tortuosity realizing durable dendrite-free zinc-ion batteries

While aqueous zinc-ion batteries exhibit great potential, their performance is impeded by zinc dendrites. Existing literature has proposed the use of hydrogel electrolytes to ameliorate this issue. Nevertheless, the mechanical attributes of hydrogel electrolytes, particularly their modulus, are suboptimal, primarily ascribed to the substantial water content. This drawback would severely restrict the dendrite-inhibiting efficacy, especially under large mass loadings of active materials. Inspired by the structural characteristics of wood, this study endeavors to fabricate the anisotropic carboxymethyl cellulose hydrogel electrolyte through directional freezing, salting-out effect, and compression reinforcement, aiming to maximize the modulus along the direction perpendicular to the electrode surface. The heightened modulus concurrently serves to suppress the vertical deposition of the intermediate product at the cathode. Meanwhile, the oriented channels with low tortuosity enabled by the anisotropic structure are beneficial to the ionic transport between the anode and cathode. Comparative analysis with an isotropic hydrogel sample reveals a marked enhancement in both modulus and ionic conductivity in the anisotropic hydrogel. This enhancement contributes to significantly improved zinc stripping/plating reversibility and mitigated electrochemical polarization. Additionally, a durable quasi-solid-state Zn//MnO2 battery with noteworthy volumetric energy density is realized. This study offers unique perspectives for designing hydrogel electrolytes and augmenting battery performance.

A Temperature Self-Adaptive Electrolyte for Wide-Temperature Aqueous Zinc-Ion Batteries.

The advancement of aqueous zinc-ion batteries (AZIBs) is often hampered by the dendritic zinc growth and the parasitic side reactions between the zinc anode and the aqueous electrolyte, especially under extreme temperature conditions. This study unveils the performance decay mechanism of zinc anodes in harsh environments, characterized by "dead zinc" at low temperatures and aggravated hydrogen evolution and adverse by-products at elevated temperatures. To address these issues, a temperature self-adaptive electrolyte (TSAE), founded on the competitive coordination principle of co-solvent and anions, is introduced. This electrolyte exhibits a dynamic solvation capability, engendering an inorganic-rich solid electrolyte interface (SEI) at low temperatures while an organic alkyl ether- and alkyl carbonate-containing SEI at elevated temperatures. The self-adaptability of the electrolyte significantly enhances the performance of the zinc anode across a broad temperature range. A Zn//Zn symmetrical cell, based on the TSAE, showcases reversible plating/stripping exceeding 16800 h (>700 d) at room temperature under 1mA cm-2 and 1 mAh cm-2, setting a record of lifespan. Furthermore, the TSAE enables stable operation of the zinc full batteries across an ultrawide temperature range of -35 to 75°C. This work illuminates a pathway for optimizing AZIBs under extreme temperatures by fine-tuning the interfacial chemistry.

Influence of non-polar groups in quaternary ammonium compounds on the growth of zinc dendrites

Dendritic growth is a common behavior during the electrodeposition of zinc, which degrades the compactness and thickness uniformity of the zinc film. In this work, a series of quaternary ammonium compounds (QAC) with different non-polar groups (based on the number of carbon atoms in non-polar groups represented as C1, C4, C8, C12 and C16, respectively) were introduced into the basic electrolyte to inhibit the zinc dendritic growth. The results showed that the deposition of zinc became smoother with the increase of non-polar group length, which was attributed to the fact that the non-polar groups of the additive limit the random diffusion of Zn2+ and changed the adsorption state of the surface, so that a uniform zinc film was obtained. Meanwhile, the Zn-Zn symmetric cells with the addition of C8 achieved a stable cycle time of over 600 h. But with the further increase of length (C12 and C16), the migration of Zn2+ to the electrode surface became extremely difficult for strong steric hindrance, resulting in a rough deposition morphology.

Strategies of regulating Zn2+ solvation structures toward advanced aqueous zinc-based batteries

Rechargeable aqueous zinc-based batteries not only pave the way for environmentally friendly and safe energy storage devices but also hold great promise for reducing the manufacturing costs of next-generation batteries, positioning them as the most promising energy storage system to replace lithium-ion batteries. However, the commercial application of aqueous zinc-based batteries (AZBs) is severely constrained by issues such as zinc dendrites, hydrogen evolution reaction (HER), and electrode corrosion. While significant efforts have been devoted to exploring electrode materials and their storage mechanisms in this system in recent years, research on the nature of Zn2+ solvation in electrolytes remains insufficient. Therefore, this review primarily provides a comprehensive and in-depth elucidation of the existing issues such as dendrite formation, hydrogen/oxygen evolution, electrode corrosion and passivation interactions. Additionally, from the perspective of electrolyte optimization, this review emphasizes existing strategies to address Zn2+ solvation, including adjusting electrolyte concentration, incorporating functional additives or co-solvents, utilizing ionic liquids, and developing hydrogel electrolytes, and summarizes approaches and mechanisms for improving their relevant performance. Finally, prospects for electrolyte modification and innovation directions of AZBs are proposed, providing guidance for future AZB studies.