Amphipathic Phenylalanine-Induced Nucleophilic-Hydrophobic Interface Toward Highly Reversible Zn Anode

Aqueous Zn^(2+)-ion batteries(AZIBs),recognized for their high security,reliability,and cost efficiency,have garnered considerable attention.However,the prevalent issues of dendrite growth and parasitic reactions at the Zn electrode interface significantly impede their practical application.In this study,we introduced a ubiquitous biomolecule of phenylalanine(Phe)into the electrolyte as a multifunctional additive to improve the reversibility of the Zn anode.Leveraging its exceptional nucleophilic characteristics,Phe molecules tend to coordinate with Zn^(2+)ions for optimizing the solvation environment.Simultaneously,the distinctive lipophilicity of aromatic amino acids empowers Phe with a higher adsorption energy,enabling the construction of a multifunctional protective interphase.The hydrophobic benzene ring ligands act as cleaners for repelling H_(2)O molecules,while the hydrophilic hydroxyl and carboxyl groups attract Zn^(2+)ions for homogenizing Zn^(2+)flux.Moreover,the preferential reduction of Phe molecules prior to H_(2)O facilitates the in situ formation of an organic-inorganic hybrid solid electrolyte interphase,enhancing the interfacial stability of the Zn anode.Consequently,Zn||Zn cells display improved reversibility,achieving an extended cycle life of 5250 h.Additionally,Zn||LMO full cells exhibit enhanced cyclability of retaining 77.3%capacity after 300 cycles,demonstrating substantial potential in advancing the commercialization of AZIBs.

Dual-function protective layer for highly reversible Zn anode

The thermodynamic instability of zinc anodes in aqueous electrolytes leads to issues such as corrosion,hydrogen evolution reactions(HER), and dendrite growth, severely hindering the practical application of zinc-based aqueous energy storage devices. To address these challenges, this work proposes a dualfunction zinc anode protective layer, composed of Zn-Al-In layered double oxides(ILDO) by rationally designing Zn-Al layered double hydroxides(Zn-Al LDHs) for the first time. Differing from previous works on the LDHs coatings, firstly, the ILDO layer accelerates zinc-ion desolvation and also captures and anchors SO_(4)^(2-). Secondly, the in-situ formation of the Zn-In alloy phase effectively lowers the nucleation energy barrier, thereby regulating zinc nucleation. Consequently, the zinc anode with the ILDO protective layer demonstrates long-term stability exceeding 1900 h and low voltage hysteresis of 7.5 m V at 0.5 m A cm^(-2) and 0.5 m A h cm^(-2). Additionally, it significantly enhances the rate capability and cycling performance of Zn@ILDO//MnO_(2) full batteries and Zn@ILDO//activated carbon zinc-ion hybrid capacitors.This simple and effective dual-function protective layer strategy offers a promising approach for achieving high-performance zinc-ion batteries.

Synergistic“Anchor‑Capture”Enabled by Amino and Carboxyl for Constructing Robust Interface of Zn Anode

While the rechargeable aqueous zinc-ion batteries(AZIBs)have been recognized as one of the most viable batteries for scale-up application,the instability on Zn anode–electrolyte interface bottleneck the further development dramatically.Herein,we utilize the amino acid glycine(Gly)as an electrolyte additive to stabilize the Zn anode–electrolyte interface.The unique interfacial chemistry is facilitated by the synergistic“anchor-capture”effect of polar groups in Gly molecule,manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn^(2+)in the local region.As such,this robust anode–electrolyte interface inhibits the disordered migration of Zn^(2+),and effectively suppresses both side reactions and dendrite growth.The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22%at 1 mA cm^(−2)and 0.5 mAh cm^(−2)over 500 cycles.Even at a high Zn utilization rate(depth of discharge,DODZn)of 68%,a steady cycle life up to 200 h is obtained for ultrathin Zn foils(20μm).The superior rate capability and long-term cycle stability of Zn–MnO_(2)full cells further prove the effectiveness of Gly in stabilizing Zn anode.This work sheds light on additive designing from the specific roles of polar groups for AZIBs.

An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries

Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries(ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions(e.g. corrosion and hydrogen evolution)in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.

Boosting Zn^(2+)kinetics via the multifunctional pre-desolvation interface for dendrite-free Zn anodes

Aqueous zinc ion batteries(AZIBs)are an advanced secondary battery technology to supplement lithiumion batteries.It has been widely concerned and developed recently based on the element abundance and safety advantages.However,AZIBs still suffer from serious problems such as dendrites Zn,hydrogen evolution corrosion,and surface passivation,which hinder the further commercial application of AZIBs.Herein,an in-situ ZnCr_(2)O_(4)(ZCO)interface endows AZIBs with dendrite-free and ultra-low polarization by realizing Zn^(2+)pre-desolvation,constraining H2O-induced corrosio n,and boosting Zn^(2+)transport/deposition kinetics.The ZCO@Zn anode harvests an ultrahigh cumulative capacity of~20000 mA h cm^(-2)(cycle time:over 4000 h)at a high current density of 10 mA cm^(-2),indicating excellent reversibility of Zn deposition,Such superior performance is among the best cyclability in AZIBs.Moreover,the multifunctional ZCO interface improves the Coulombic efficiency(CE)to 99.7%for more than 2600 cycles.The outstanding electrochemical performance is also verified by the long-term cycle stability of ZCO@Zn//α-MnO_(2) full cells.Notably,the as-proposed method is efficient and low-cost enough to enable mass production.This work provides new insights into the uniform Zn electrodeposition at the scale of interfacial Zn^(2+)predesolvation and kinetics improvement.

2D Materials Boost Advanced Zn Anodes:Principles,Advances,and Challenges

Aqueous zinc-ion battery(ZIB)featuring with high safety,low cost,environmentally friendly,and high energy density is one of the most promising systems for large-scale energy storage application.Despite extensive research progress made in developing high-performance cathodes,the Zn anode issues,such as Zn dendrites,corrosion,and hydrogen evolution,have been observed to shorten ZIB’s lifespan seriously,thus restricting their practical application.Engineering advanced Zn anodes based on two-dimensional(2D)materials are widely investigated to address these issues.With atomic thickness,2D materials possess ultrahigh specific surface area,much exposed active sites,superior mechanical strength and flexibility,and unique electrical properties,which confirm to be a promising alternative anode material for ZIBs.This review aims to boost rational design strategies of 2D materials for practical application of ZIB by combining the fundamental principle and research progress.Firstly,the fundamental principles of 2D materials against the drawbacks of Zn anode are introduced.Then,the designed strategies of several typical 2D materials for stable Zn anodes are comprehensively summarized.Finally,perspectives on the future development of advanced Zn anodes by taking advantage of these unique properties of 2D materials are proposed.

Electrolyte Strategies Toward Optimizing Zn Anode for Zinc-Ion Batteries

Zinc-ion batteries(ZIBs)with low cost and high safety have become potential candidates for large-scale energy storage.However,the knotty Zn anode issues such as dendritic growth,hydrogen evolution reaction(HER)and corrosion and passivation are still unavoidable,which greatly limits the wide applications of ZIBs.The states and additives of electrolytes are closely related to these problems.However,there is a lack of systematic understanding and discussion about the intrinsic connection between the states and additives of electrolyte and Zn anode issues.In this review,the basic principles of dendritic growth,HER and corrosion and passivation are fi rstly introduced,and then,electrolyte optimization strategies with the corresponding electrochemical properties are systematically summarized.In particular,the action mechanism of electrolyte additives and the electrolyte states for Zn anode optimization is analyzed in detail.Finally,some unique views on the improvement of electrolyte for Zn anode optimization are put forward,which is expected to provide a certain professional reference for designing high-performance ZIBs.

Regulating Zn Deposition via an Artificial Solid–Electrolyte Interface with Aligned Dipoles for Long Life Zn Anode

Aqueous zinc ion batteries show prospects for next-generation renewable energy storage devices.However,the practical applications have been limited by the issues derived from Zn anode.As one of serious problems,Zn dendrite growth caused from the uncontrollable Zn deposition is unfavorable.Herein,with the aim to regulate Zn deposition,an artificial solid–electrolyte interface is subtly engineered with a perovskite type material,BaTiO3,which can be polarized,and its polarization could be switched under the external electric field.Resulting from the aligned dipole in BaTiO3 layer,zinc ions could move in order during cycling process.Regulated Zn migration at the anode/electrolyte interface contributes to the even Zn stripping/plating and confined Zn dendrite growth.As a result,the reversible Zn plating/stripping processes for over 2000 h have been achieved at 1 mA cm^(−2) with capacity of 1 mAh cm−2.Furthermore,this anode endowing the electric dipoles shows enhanced cycling stability for aqueous Zn-MnO2 batteries.The battery can deliver nearly 100%Coulombic efficiency at 2 Ag^(−1) after 300 cycles.

Simultaneously Regulating Uniform Zn^(2+) Flux and Electron Conduction by MOF/rGO Interlayers for High‑Performance Zn Anodes

Owing to the merits of low cost,high safety and environmental benignity,rechargeable aqueous Zn-based batteries(ZBs)have gained tremendous attention in recent years.Nevertheless,the poor reversibility of Zn anodes that originates from dendrite growth,surface passivation and corrosion,severely hinders the further development of ZBs.To tackle these issues,here we report a Janus separator based on a Zn-ion conductive metal-organic framework(MOF)and reduced graphene oxide(rGO),which is able to regulate uniform Zn2+flux and electron conduction simultaneously during battery operation.Facilitated by the MOF/rGO bifunctional interlayers,the Zn anodes demonstrate stable plating/stripping behavior(over 500 h at 1 mA cm^(−2)),high Coulombic efficiency(99.2%at 2 mA cm^(−2) after 100 cycles)and reduced redox barrier.Moreover,it is also found that the Zn corrosion can be effectively retarded through diminishing the potential discrepancy on Zn surface.Such a separator engineering also saliently promotes the overall performance of Zn|MnO2 full cells,which deliver nearly 100%capacity retention after 2000 cycles at 4 A g^(−1) and high power density over 10 kW kg^(−1).This work provides a feasible route to the high-performance Zn anodes for ZBs.

Interface Reversible Electric Field Regulated by Amphoteric Charged Protein-Based Coating Toward High-Rate and Robust Zn Anode

Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn^(2+) uniform deposition.However,strong interactions between the coating and Zn^(2+) and sluggish transport of Zn^(2+) lead to high anodic polarization.Here,we present a bio-inspired silk fibroin(SF)coating with amphoteric charges to construct an interface reversible electric field,which manipulates the transfer kinetics of Zn^(2+) and reduces anodic polarization.The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn^(2+) flux via the inter-play between the charged coating and adsorbed ions,endowing the Zn-SF anode with low polarization voltage and stable plating/stripping.Experimental analyses with theo-retical calculations suggest that SF can facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+) and provide nucleation sites for uniform deposition.Consequently,the Zn-SF anode delivers a high-rate performance with low voltage polarization(83 mV at 20 mA cm^(−2)) and excellent stability(1500 h at 1 mA cm^(−2);500 h at 10 mA cm^(−2)),realizing exceptional cumulative capacity of 2.5 Ah cm^(−2).The full cell coupled with Zn_(x)V_(2)O_(5)·nH_(2)O(ZnVO)cathode achieves specific energy of~270.5/150.6 Wh kg^(−1)(at 0.5/10 A g^(−1))with-99.8% Coulombic efficiency and retains~80.3%(at 5.0 A g^(−1))after 3000 cycles.

Manipulating Interfacial Stability Via Absorption-Competition Mechanism for Long-Lifespan Zn Anode

The stability of Zn anode in various Znbased energy storage devices is the key problem to be solved.Herein,aromatic aldehyde additives are selected to modulate the interface reactions between the Zn anode and electrolyte.Through comprehensively considering electrochemical measurements,DFT calculations and FEA simulations,novel mechanisms of one kind of aromatic aldehyde,veratraldehyde in inhibiting Zn dendrite/by-products can be obtained.This additive prefers to absorb on the Zn surface than H_(2)O molecules and Zn^(2+),while competes with hydrogen evolution reaction and Zn plating/stripping proces s via redox reactions,thus preventing the decomposition of active H_(2)O near the interface and uncontrollable Zn dendrite growth via a synactic absorption-competition mechanism.As a result,Zn-Zn symmetric cells with the veratraldehyde additive realize an excellent cycling life of 3200 h under 1 mA cm^(-2)/1 mAh cm^(-2)and over 800 h even under 5 mA cm^(-2)/5 mAh cm^(-2).Moreover,Zn-Ti and Zn-MnO_(2)cells with the veratraldehyde additive both obtain elevated performance than that with pure ZnSO_(4)electrolyte.Finally,two more aromatic aldehyde additives are chosen to prove their universality in stabilizing Zn anodes.

Progress in research on metal-based materials in stabilized Zn anodes

Aqueous zinc-ion batteries(ZIBs) combine the benefits of metallic Zn anodes with those of aqueous electrolytes and are well suited for large-scale energy storage because of their inherent high safety, cost-effectiveness, and eco-friendliness. Currently, the practical application of such batteries is hindered by the poor cycling performance of Zn anodes due to uncontrolled dendrite formation and severe side reactions, although recent reports suggest that these problems can be mitigated through the modification of Zn anodes with metal-based materials.Given that the mechanisms of improving Zn deposition and the structural evolution of metal-based materials have not been systematically reviewed, we herein systematically overview the metal-based materials used to stabilize Zn anodes, starting with a brief summary of the anode working mechanism and the challenges faced by stabilized Zn anodes. Subsequently, the design principles of Zn anodes stabilized by metal-based materials and the related recent progress are reviewed, and the key challenges and perspectives for the future development of such Zn anodes are proposed.

Stable and dendrite-free Zn anode with artificial desolvation interface layer toward high-performance Zn-ion capacitor

Aqueous Zn-based energy storage devices possess tremendous advantages, such as low cost, high safety,and competitive energy density, due to employing a Zn metal anode and aqueous electrolyte. However,the cycling stability and rate ability of a Zn anode are hindered by Zn dendrite growth and sluggish ion transfer in the electrode/electrolyte interface. Herein, the interfacial properties of Zn anodes are improved through the introduction of a silver(Ag) protective layer, which facilitates uniform Zn deposition and regulates Zn ion transport. As a result, Ag-coated Zn anodes display stable cycling performance(600 h at 1 m A cm^(-2)) and low overpotential(150 mV at 50 mA cm^(-2)after 2000 cycles). The Ag layer in situ electrochemically converts into an AgZn_(3) layer and promotes Zn ion desolvation and threedimensional diffusion processes. Moreover, a Zn-ion capacitor assembled with an Ag-coated Zn anode and active carbon cathode shows a capable cycling lifespan and rate performance. This study provides a feasible strategy for constructing a stabilized and dendrite-free Zn anode for the development of high-performance Zn-based energy storage devices.

Advance in reversible Zn anodes promoted by 2D materials

With the growing energy demand associated with high safety and low-cost requirement,aqueous zinc-ion batteries(AZIBs)have been considered as one of the most promising next-generation batteries.However,some key issues,such as uncontrollable dendrites growth,severe corrosion,hydrogen evolution and side reactions of Zn anodes during charge/discharge process,have hindered its pragmatic applications.Two-dimensional(2D)materials hold advantages of unique physical and chemical properties,large surface areas and abundant active sites,which have been successfully used to overcome the above shortcomings of Zn anodes in recent years.In this review,the issues and challenges of Zn anodes are outlined.Then,the state-of-the-art progress on Zn anodes modification based on 2D materials such as graphene,2D metal carbides and nitrides(MXenes),2D metal-organic frameworks(MOFs),2D covalent organic frameworks(COFs),2D transition metal compounds and other 2D materials is discussed in detail.Finally,the perspectives of employing 2D materials in highly reversible Zn anodes are summarized and discussed.

Polyzwitterionic cross-linked double network hydrogel electrolyte enabling high-stable Zn anode

Zn metal anode suffers from dendrite issues and passive byproducts,which severely plagues the practical application of aqueous Zn metal batteries.Herein,a polyzwitterionic cross-linked double network hydrogel electrolyte composed of physical crosslinking(hyaluronic acid)and chemical crosslinking(synthetic zwitterionic monomer copolymerized with acrylamide)is introduced to overcome these obstacles.On the one hand,highly hydrophilic physical network provides an energy dissipation channel to buffer stress and builds a H_(2)O-poor interface to avoid side reactions.On the other hand,the charged groups(sulfonic and imidazolyl)in chemical crosslinking structure build anion/cation transport channels to boost ions’kinetics migration and regulate the typical solvent structure[Zn(H_(2)O)_(6)]^(2+)to R-SO_(3)^(−)[Zn(H_(2)O)_(4)]^(2+),with uniform electric field distribution and significant resistance to dendrites and parasitic reactions.Based on the above functions,the symmetric zinc cell exhibits superior cycle stability for more than 420 h at a high current density of 5 mA·cm^(−2),and Zn||MnO_(2)full cell has a reversible specific capacity of 150 mAh·g^(−1)after 1000 cycles at 2 C with this hydrogel electrolyte.Furthermore,the pouch cell delivers impressive flexibility and cyclability for energy-storage applications.

Multifunctional Sodium Gluconate Electrolyte Additive Enabling Highly Reversible Zn Anodes

Sodium gluconate(SG)is reported as an electrolyte additive for rechargeable aqueous zinc batteries.The SG addition is proposed to modulate the nucleation overpotential and plating behaviors of Zn by forming a shielding buffer layer because of the adsorption priority and large steric hindrance effect,which contributes to limited rampant Zn^(2+)diffusion and mitigated hydrogen evolution and corrosion.With the introduction of 30 mmol/L SG in 2 mol/L ZnSO_(4)electrolyte,the Zn anode harvests a reversible cycling of 1200 h at 5 mA/cm^(2)and a high average Coulombic efficiency of Zn plating/stripping(99.6%).Full cells coupling Zn anode with V_(2)O_(5)·1.6H_(2)O or polyaniline cathode far surpass the SG additivefree batteries in terms of cycle stability and rate capability.This work provides an inspiration for design of a high-effective and low-cost electrolyte additive towards Zn-based energy storage devices.

A widely used nonionic surfactant with desired functional groups as aqueous electrolyte additives for stabilizing Zn anode

Aqueous Zn-ion batteries(AZIBs) have emerged as potential candidates for Li-ion batteries due to their intrinsic safety and high capacity.However,metallic Zn anodes encounter dendrite growth and water-induced corrosion,rendering poor stability and severe irreversibility at the electrode/electrolyte interface during cycling.To stabilize the Zn anode,we report a low-cost and effective nonionic surfactant,Tween-20 polymer,as an electrolyte additive for AZIBs.For Tween-20,sequential oxyethylene groups tended to be preferentially adsorbed on the Zn electrode to form a shielding layer for regulating uniform Zn nucleation.Moreover,the hydrophobic hendecyl chains prevented H_(2)O-induced corrosion on the Zn anode surface.Benefiting from the desired functional groups,when only trace amounts of Tween-20(0.050 g·L^(-1)) were used,the Zn anode displayed good cycling stability over 2170 h at10 mA·cm^(-2) and a high average Coulombic efficiency of98.94% over 1000 cycles.The Tween-20 polymer can also be effectively employed in MnO_(2)/Zn full batteries.Considering their toxicity,price and amount of usage,these surfactant additives provide a promising strategy for realizing the stability and reversibility of high-performance Zn anodes.

Molecular engineering of self-assembled monolayers for highly utilized Zn anodes

Stabilizing the Zn anode under high utilization rates is highly applauded yet very challenging in aqueous Zn batteries.Here,we rationally design a zincophilic short-chain aromatic molecule,4-mercaptopyridine(4Mpy),to construct self-assembled monolayers(SAMs)on a copper substrate to achieve highly utilized Zn anodes.We reveal that 4Mpy could be firmly bound on the Cu substrate via Cu–S bond to form compact and uniform SAMs,which could effectively isolate the water on the electrode surface and thus eliminate the water-related side reactions.In addition,the short-chain aromatic ring structure of 4Mpy could not only ensure the ordered arrangement of zincophilic pyridine N but also facilitate charge transfer,thus enabling uniform and rapid Zn deposition.Consequently,the Zn/4Mpy/Cu electrode not only enables the symmetric cell to stably cycle for over 180 h at 10 mA cm^(-2) under a high depth-of-discharge of 90%,but also allows the MnO_(2)-paired pouch cell to survive for 100 cycles under a high Zn utilization rate of 78.8%.An anode-free 4Mpy/Cu||graphite cell also operates for 150 cycles without obvious capacity fading at 0.1 A g^(-1).This control of interfacial chemistry via SAMs to achieve high utilization rates of metal anodes provides a new paradigm for developing high-energy metal-based batteries.

Highly reversible Zn anode enabled by anticatalytic carbon layer with suppressed hydrogen evolution

Aqueous zinc-ion batteries(AZIBs)have emerged as a promising high-efficiency energy storage system due to the high energy density,low-cost and environmental friendliness.However,the practical application of AZIBs is severely restricted by the challenges faced by the Zn anode,which include uncontrollable dendrite growth,corrosion and hydrogen evolution reaction.Herein,a simple and convenient physical vapor deposition(PVD)method is reported for fabricating uniform graphite as a protection layer on the surface of Zn anode.The high conductivity graphite layer on Zn anode(denoted as Zn@C)not only benefits the uniform distribution of the electric field,but also provides numerous Zn nucleation sites to regulate and navigate Zn-ion stripping/plating behaviors.Additionally,the graphite layer with a poor catalytic activity endows the Zn@C anode with a highly suppressed hydrogen evolution.Consequently,a hydrogen and dendrite free anode is achieved with artificial anticatalytic carbon layer on Zn anode,exhibiting a high reversibility and excellent cycling stability over 2600 h at the current density of 5 mA·cm^(-2)with a capacity of 2.5 mAh·cm^(-2)and longtime cycling stability for assembled full cells.This work strategically designs the properties of the artificial interface layer to effectively address various challenges simultaneously,which presents insights for the future development of high-performance rechargeable AZIBs.

Recent advances and perspectives for Zn-based batteries:Zn anode and electrolyte

Zn-based batteries have attracted extensive attention due to their high theoretical energy density,safety,abundant resources,environmental friendliness,and low cost.They are a new energy storage and conversion technology with significant development potential and have been widely used in renewable energy and portable electronic devices.Considerable attempts have been devoted to improving the performance of Zn-based batteries.Specifically,battery cycle life and energy efficiency can be improved by electrolyte modification and the construction of highly efficient rechargeable Zn anodes.This review compiles the progress of the research related to Zn anodes and electrolytes,especially in the last five years.This review will introduce fundamental concepts,summarize recent development,and inspire further systematic research for high-performance Zn-based batteries in the future.