Polymer engineering for electrodes of aqueous zinc ion batteries

With the increasing demand for scalable and cost-effective electrochemical energy storage,aqueous zinc ion batteries(AZIBs)have a broad application prospect as an inexpensive,efficient,and naturally secure energy storage device.However,the limitations suffered by AZIBs,including volume expansion and active materials dissolution of the cathode,electrochemical corrosion,irreversible side reactions,zinc dendrites of the anode,have seriously decelerated the civilianization process of AZIBs.Currently,polymers have tremendous superiority for application in AZIBs attributed to their exceptional chemical stability,tunable structure,high energy density and outstanding mechanical properties.Considering the expanding applications of AZIBs and the superiority of polymers,this comprehensive paper meticulously reviews the benefits of utilizing polymeric applied to cathodes and anodes,respectively.To begin with,with adjustable structure as an entry point,the correlation between polymer structure and the function of energy storage as well as optimization is deeply investigated in respect to the mechanism.Then,depending on the diversity of properties and structures,the development of polymers in AZIBs is summarized,including conductive polymers,redox polymers as well as carbon composite polymers for cathode and polyvinylidene fluoride-,carbonyl-,amino-,nitrile-based polymers for anode,and a comprehensive evaluation of the shortcomings of these strategies is provided.Finally,an outlook highlights some of the challenges posed by the application of polymers and offers insights into the potential future direction of polymers in AZIBs.It is designed to provide a thorough reference for researchers and developers working on polymer for AZIBs.

Asymmetric Electrolytes Design for Aqueous Multivalent Metal Ion Batteries

With the rapid development of portable electronics and electric road vehicles,high-energy-density batteries have been becoming front-burner issues.Traditionally,homogeneous electrolyte cannot simultaneously meet diametrically opposed demands of high-potential cathode and low-potential anode,which are essential for high-voltage batteries.Meanwhile,homogeneous electrolyte is difficult to achieve bi-or multi-functions to meet different requirements of electrodes.In comparison,the asymmetric electrolyte with bi-or multi-layer disparate components can satisfy distinct requirements by playing different roles of each electrolyte layer and meanwhile compensates weakness of individual electrolyte.Consequently,the asymmetric electrolyte can not only suppress by-product sedimentation and continuous electrolyte decomposition at the anode while preserving active substances at the cathode for high-voltage batteries with long cyclic lifespan.In this review,we comprehensively divide asymmetric electrolytes into three categories:decoupled liquid-state electrolytes,bi-phase solid/liquid electrolytes and decoupled asymmetric solid-state electrolytes.The design principles,reaction mechanism and mutual compatibility are also studied,respectively.Finally,we provide a comprehensive vision for the simplification of structure to reduce costs and increase device energy density,and the optimization of solvation structure at anolyte/catholyte interface to realize fast ion transport kinetics.

Vanadium oxide nanospheres encapsulated in N-doped carbon nanofibers with morphology and defect dual-engineering toward advanced aqueous zinc-ion batteries

Vanadium-based electrodes are regarded as attractive cathode materials in aqueous zinc ion batteries(ZIBs)caused by their high capacity and unique layered structure.However,it is extremely challenging to acquire high electrochemical performance owing to the limited electronic conductivity,sluggish ion kinetics,and severe volume expansion during the insertion/extraction process of Zn^(2+).Herein,a series of V_(2)O_(3)nanospheres embedded N-doped carbon nanofiber structures with various V_(2)O_(3)spherical morphologies(solid,core-shell,hollow)have been designed for the first time by an electrospinning technique followed thermal treatments.The N-doped carbon nanofibers not only improve the electrical conductivity and the structural stability,but also provides encapsulating shells to prevent the vanadium dissolution and aggregation of V_(2)O_(3)particles.Furthermore,the varied morphological structures of V_(2)O_(3)with abundant oxygen vacancies can alleviate the volume change and increase the Zn^(2+)pathway.Besides,the phase transition between V_(2)O_(3)and Zn_XV_(2)O_(5-m)·n H_(2)O in the cycling was also certified.As a result,the as-obtained composite delivers excellent long-term cycle stability and enhanced rate performance for coin cells,which is also confirmed through density functional theory(DFT)calculations.Even assembled into flexible ZIBs,the sample still exhibits superior electrochemical performance,which may afford new design concept for flexible cathode materials of ZIBs.

Revealing the role of calcium ion intercalation of hydrated vanadium oxides for aqueous zinc-ion batteries

Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.

Novel high-voltage cathode for aqueous zinc ion batteries:Porous K_(0.5)VOPO_(4)·1.5H_(2)O with reversible solid-solution intercalation and conversion storage mechanism

Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for the first time a new porous K_(0.5)VOPO_(4)·1.5H_(2)O polyanionic cathode(P-KIVP)with high output voltage(above 1.2 V)that can be manufactured at room temperature using straightforward coprecipitation and etching techniques.The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase co nversion pathway throughout the Zn^(2+)storage process,as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy.Similar to other layered vanadium-based polyanionic materials,the P-KVP cathode experiences a progressive decline in voltage during the cycle,which is demonstrated to be caused by the irreversible conversion into amorphous VO_(x).By introducing a new electrolyte containing Zn(OTF)_(2) to a mixed triethyl phosphate and water solution,it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer.As a proof-of-concept,the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch,highlighting the application potential of P-KVP cathode.

Stabilization of flake Zn powder anodes via designing functional additives in electrolytes for aqueous Zn ion batteries

Zn powder anodes have attracted much attention in aqueous Zn ion battery applications due to advantages such as low cost and processability.However,the high-activity Zn powder anode faces problems such as side reactions,hydrogen evolution,and dendrites,which limit the cycling stability of the cell.In this work,the high activity of Zn powder is weakened by introducing low-cost erythritol as a functional additive in the ZnSO_(4) electrolyte to improve the cycle life of the cell.Both theoretical calculations and empirical evidence demonstrate that the incorporation of erythritol alters the coordination sphere of Zn^(2+)and modifies the local molecular architecture of the electrolyte.This modification serves to diminish the reactivity of water molecules,thereby efficaciously suppressing dendrite formation and deleterious ancillary reactions on the zinc powder anode surfaces.Concurrently,erythritol functions as an interfacial cationic captor,enhancing reaction dynamics and facilitating the development of a favorable protective layer throughout the zinc plating/stripping process.Consequently,the symmetric cell paired with an erythritol-containing electrolyte manifests stable cycling performance for an extended duration of 850 h at a current density of 0.288 mA cm^(-2)and areal capacity of 0.144 mAh cm^(-2).Notably,it maintains a cycling life of 400 h even under intensified conditions (2.88 mA cm^(-2)/1.44 mA h cm^(-2)).Furthermore,the constructed Na_(2)V_(6)O_(16)·3H_(2)O full cell illustrated remarkable capacity retention of 155.8 mA h g^(-1)following 800 cycles at a high rate of 5 A g^(-1).

A Molecular-Sieving Interphase Towards Low-Concentrated Aqueous Sodium-Ion Batteries

Aqueous sodium-ion batteries are known for poor rechargeability because of the competitive water decomposition reactions and the high electrode solubility.Improvements have been reported by saltconcentrated and organic-hybridized electrolyte designs,however,at the expense of cost and safety.Here,we report the prolonged cycling of ASIBs in routine dilute electrolytes by employing artificial electrode coatings consisting of NaX zeolite and NaOH-neutralized perfluorinated sulfonic polymer.The as-formed composite interphase exhibits a molecularsieving effect jointly played by zeolite channels and size-shrunken ionic domains in the polymer matrix,which enables high rejection of hydrated Na^(+)ions while allowing fast dehydrated Na^(+)permeance.Applying this coating to electrode surfaces expands the electrochemical window of a practically feasible 2 mol kg^(-1) sodium trifluoromethanesulfonate aqueous electrolyte to 2.70 V and affords Na_(2)MnFe(CN)_(6)//NaTi_(2)(PO_(4))_(3) full cells with an unprecedented cycling stability of 94.9%capacity retention after 200 cycles at 1 C.Combined with emerging electrolyte modifications,this molecular-sieving interphase brings amplified benefits in long-term operation of ASIBs.

Polypyride intercalation boosting the kinetics and stability of V_(3)O_(7)·H_(2)O cathodes for aqueous zinc-ion batteries

V_(3)O_(7)·H_(2)O(VO)is a high capacity cathode material in the field of aqueous zinc ion batteries(AZIBs),but it is limited by slow ion migration and low electrical conductivity.In this paper,polypyridine(PPyd)intercalated VO with nanoribbon structure was prepared by a simple in-situ pre-intercalation,which is noted VO-PPyd.The total density of states(TDOS)shows that after the pre-intercalation of PPyd,an intermediate energy level appears between the valence band and conduction band,which provides a step that can effectively reduce the band gap and enhance the electron conductivity.Furthermore,the density functional theory(DFT)results found that Zn^(2+)is more easily de-intercalated from the V-O skeleton,which proves that the embeddedness of PPyd improves the diffusion kinetics of Zn^(2+).Electrochemical studies have shown that VO-PPyd cathode materials exhibit excellent rate performance(high specific capacity of 465 and 192 mA h g^(-1)at 0.2 and 10 A g^(-1),respectively)and long-term cycling performance(92.7%capacity retention rate after 5300 cycles),due to their advantages in structure and composition.More importantly,the energy density of VO-PPyd//Zn at 581 and 5806 W kg^(-1)is 375 and 247 W h kg^(-1),respectively.VO-PPyd exhibits excellent electrochemical properties compared to previously reported vanadium based cathodes,which makes it highly competitive in the field of high-performance cathode materials of AZIBs.

Building stabilized Cu_(0.17)Mn_(0.03)V_(2)O_(5−□)·2.16H_(2)O cathode enables an outstanding room‐/low‐temperature aqueous Zn‐ion batteries

Vanadium oxide cathode materials with stable crystal structure and fast Zn^(2+) storage capabilities are extremely important to achieving outstanding electrochemical performance in aqueous zinc‐ion batteries.In this work,a one‐step hydrothermal method was used to manipulate the bimetallic ion intercalation into the interlayer of vanadium oxide.The pre‐intercalated Cu ions act as pillars to pin the vanadium oxide(V‐O)layers,establishing stabilized two‐dimensional channels for fast Zn^(2+) diffusion.The occupation of Mn ions between V‐O interlayer further expands the layer spacing and increases the concentration of oxygen defects(Od),which boosts the Zn^(2+) diffusion kinetics.As a result,as‐prepared Cu_(0.17)Mn_(0.03)V_(2)O_(5−□)·2.16H_(2)O cathode shows outstanding Zn‐storage capabilities under room‐and lowtemperature environments(e.g.,440.3 mAh g^(−1) at room temperature and 294.3 mAh g^(−1)at−60°C).Importantly,it shows a long cycling life and high capacity retention of 93.4%over 2500 cycles at 2 A g^(−1) at−60°C.Furthermore,the reversible intercalation chemistry mechanisms during discharging/charging processes were revealed via operando X‐ray powder diffraction and ex situ Raman characterizations.The strategy of a couple of 3d transition metal doping provides a solution for the development of superior room‐/lowtemperature vanadium‐based cathode materials.

Review of vanadium-based electrode materials for rechargeable aqueous zinc ion batteries

In recent years,rechargeable aqueous zinc ion batteries(ZIBs),as emerging energy storage devices,stand out from numerous metal ion batteries.Due to the advantages of low cost,environmentally friendly characteristic and safety,ZIBs can be considered as alternatives to lithium-ion batteries(LIBs).Vanadiumbased compounds with various structures and large layer spacings are considered as suitable cathode candidates for ZIBs.In this review,the recent research advances of vanadium-based electrode materials are systematically summarized.The electrode design strategy,electrochemical performances and energy storage mechanisms are emphasized.Finally,we point out the limitation of vanadium-based materials at present and the future prospect.

Cooperative Chloride Hydrogel Electrolytes Enabling Ultralow-Temperature Aqueous Zinc Ion Batteries by the Hofmeister Effect

Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety,environmental friendliness,and low cost.However,the freezing of aqueous electrolytes limits the normal operation of batteries at low temperatures.Herein,a series of high-performance and low-cost chloride hydrogel electrolytes with high concentrations and low freezing points are developed.The electrochemical windows of the chloride hydrogel electrolytes are enlarged by>1 V under cryogenic conditions due to the obvious evolution of hydrogen bonds,which highly facilitates the operation of electrolytes at ultralow temperatures,as evidenced by the low-temperature Raman spectroscopy and linear scanning voltammetry.Based on the Hofmeister effect,the hydrogen-bond network of the cooperative chloride hydrogel electrolyte comprising 3 M ZnCl_(2)and 6 M LiCl can be strongly interrupted,thus exhibiting a sufficient ionic conductivity of 1.14 mS cm;and a low activation energy of 0.21 e V at-50℃.This superior electrolyte endows a polyaniline/Zn battery with a remarkable discharge specific capacity of 96.5 mAh g;at-50℃,while the capacity retention remains~100%after 2000 cycles.These results will broaden the basic understanding of chloride hydrogel electrolytes and provide new insights into the development of ultralow-temperature aqueous batteries.

Synergistically constructed lamination-like network of redox-active polyimide and MXene via π-π interactions for aqueous NH_(4)^(+) storage

As a nonmetallic charge carrier,ammonium ion(NH_(4)^(+))has garnered significant attention in the construction of aqueous batteries due to its advantages of low molar mass,small hydration size and rapid diffusion in aqueous solutions.Polymers are a kind of potential electro-active materials for aqueous NH_(4)^(+)storage.However,traditional polymer electrodes are typically created by covering the bulky collectors with excessive additives,which could lead to low volume capacity and unsatisfactory stability.Herein,a nanoparticle-like polyimide(PI)was synthesized and then combined with MXene nanosheets to synergistically construct an additive-free and self-standing PI@MXene composite electrode.Significantly,the redox-active PI nanoparticles are enclosed between conductive MXene flakes to create a 3D lamination-like network that promotes electron transmission,while theπ-πinteractions existing between PI and MXene contribute to the enhanced structural integrity and stability within the composite electrode.As such,it delivers superior aqueous NH_(4)^(+)storage behaviors in terms of a notable specific capacity of 110.7 mA·h·cm^(–3) and a long lifespan with only 0.0064%drop each cycle.Furthermore,in-situ Raman and UV–Vis examinations provide evidence of reversible and stable redox mechanism of the PI@MXene composite electrode during NH_(4)^(+)uptake/removal,highlighting its significance in the area of electrochemical energy storage.

Manipulating Horizontal Zn Deposition with Graphene Interpenetrated Zn Hybrid Foils for Dendrite-Free Aqueous Zinc Ion Batteries

Aqueous zinc ion batteries(ZIBs)with intrinsic safety have great potentials in portable devices,but suffer from limited cycling life mainly caused by serious dendrite growth and unavoidable side reactions of Zn anodes.Herein,graphene interpenetrated Zn(GiZn)hybrid foils are developed for dendrite-free and long-term Zn anodes for high-performance ZIBs.The GiZn anode is prepared by interfacial assembly of reduced graphene oxide(rGO)on the skeletons of zinc foams,followed by mechanical compression into hybrid foils and drying process.The presence of the rGO nanosheets in the GiZn hybrid foils provides abundant zincophilic sites to induce horizontal Zn deposition for Zn metal anodes without the growth of dendrites.Meanwhile,the uniform distribution of rGO nanosheets endows the hybrid foils with superior conductivity and wetting ability with electrolytes for reduced interfacial resistances.As a result,GiZn-based symmetric cells exhibit a small voltage hysteresis of 30.4 mV and remarkable areal capacity of 30 mAh cm^(-2)at 0.5 mA cm^(-2).Further,GiZn anodes also enable the corresponding aqueous Zn||MnO_(2)batteries with high capacity of 168.5 mAh g^(-1)at 8 C,superior to the counterpart with pure Zn foil anodes(72.7 mAh g^(-1)).Therefore,GiZn hybrid foil anodes will shed light on the rational construction of 2D material-interpenetrated Zn hybrid foil anodes for high-performance ZIBs.

Unlocking high-performance organic cathodes:tailoring active group densities in covalent frameworks for aqueous zinc ion batteries

Aqueous zinc ion batteries(AZIBs)are a promising energy storage technology due to their cost-effectiveness and safety.Organic materials with sustainable and designable structures are of great interest as AZIBs cath-odes.However,small molecules in organic cathode materials face dissolution problems and suboptimal cycle life,whereas large molecules suffer from a low theoretical capacity due to their inert carbon skeletons.Here,we designed two covalent organic framework(COF)materials(benzoquinoxaline benzoquinone-based COF(BB-COF)and triquinoxalinylene benzoquinone-based COF(TB-COF))with the same structure and number of energy storage groups to investigate the correlation between the densities of active sites and electrochemi-cal performance.We conclude that the electrochemical behavior of organic conjugate-based energy storage materials lacks a linear correlation with active site quantity.Adjusting active site densities is crucial for mate-rial advancement.BB-COF and TB-COF with dual active sites(C=O and C=N)exhibit distinct characteristics.TB-COF,which has dense active groups,shows a high initial capacity(222 mAh g^(-1)).Conversely,BB-COF,which features a large conjugated ring diameter,presents superior rate performance and enduring cycle stability.It even maintains stable cycling for 2000 cycles at-40℃.In-situ electrochemical quartz crystal mic-robalance tests reveal the energy storage mechanism of BB-COF,in which H+storage is followed by Zn2+storage.

High durable aqueous zinc ion batteries by synergistic effect of V_(6)O_(13)/VO_(2) electrode materials

Vanadium oxides have attracted one’s wide attention due to their diverse valences and spatial structure as cathode for aqueous zinc ion batteries.However,a strong electrostatic interaction exists between Zn ions and host materials,which leads to their sluggish reaction kinetics and inferior structural stability.Herein,we design a kind of vanadium-based electrode materials with abundant phase boundaries and oxygen defects.The assembled Zn//V_(6)O_(13)/VO_(2) batteries deliver a specific capacity of 498.3 mA h g^(-1)at 0.2 A g^(-1) and retain a capacity of 485.8 mA h g^(-1)after 100 cycles.Moreover,they achieve a retention rate of 96.8% after 5000 cycles at 10 A g^(-1).The soft pack cells also show excellent mechanical stability at different folding conditions.

First-row transition metal compounds for aqueous metal ion batteries

In recent years,a series of aqueous metal ion batteries(AMIBs)has been developed to improve the safety and cost-efficiency of portable electronics and electric vehicles.However,the significant gaps in energy density,power density,and cycle stability of AMIBs directly hinder them from replacing the currently widely used non-aqueous metal ion batteries,which stems from the lack of reasonable configuration and performance optimization of electrode materials.First-row transition metal compounds(FRTMCs),with the advantages of optional voltage ranges(from low to high),adjustable crystal structures(layered and tunnel types with large spacing),and designable morphology(multi-dimensional nanostructures),are widely used to construct high-performance AMIBs.However,no comprehensive review papers were generated to highlight their specific and significant roles in AMIBs.In this review,we first summarize the superiority and characteristics of FRTMCs in AMIBs.Then,we put forward control strategies of FRTMCs from subsurface engineering to inner construction to promote capacitance control and diffusion control energy storage.After that,the electrochemical performance of the FRTMCs regulation strategies in AMIBs is reviewed.Finally,we present potential directions and challenges for further enhancements of FRTMCs in AMIBs.The review aims to provide an in-depth understanding of regulation strategies for enhancing energy storage to build high-performance AMIBs that meet practical applications.

Emerging rechargeable aqueous aluminum ion battery:Status,challenges,and outlooks

Aluminum ion battery(AIB)technology is an exciting alternative for post-lithium energy storage.AIBs based on ionic liquids have enabled advances in both cathode material development and fundamental understanding on mechanisms.Recently,unlocking chemistry in rechargeable aqueous aluminum ion battery(AAIB)provides impressive prospects in terms of kinetics,cost,safety considerations,and ease of operation.To review the progress on AAIB,we discuss the critical issues on aluminum electrochemistry in aqueous system,cathode material design to overcome the drawbacks by multivalent aluminum ions,and challenges on electrolyte design,aluminum stripping/plating,solid-electrolyte interface(SEI)formation,and design of cathode materials.This review aims to stimulate exploration of high-performance AAIB and rationalize feasibility grounded on underlying reaction mechanisms.

Highly stable aqueous rechargeable Zn-ion battery:The synergistic effect between NaV_(6)O_(15) and V_(2)O_(5) in skin-core heterostructured nanowires cathode

The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^(^(2+))and cathode materials.Hence,a novel NaV_(6)O_(15)/V_(2)O_(5) skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV_(6)O_(15)/V_(2)O_(5) cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV_(6)O_(15)/V_(2)O_(5),in which the sheath of NaV_(6)O_(15) possesses high stability and conductivity,and the V_(2)O_(5) endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn^(2+)transport but also further consolidates the stability of the layers of V_(2)O_(5) during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.

Aqueous Zn-MnO_(2) battery: Approaching the energy storage limit with deep Zn^(2+) pre-intercalation and revealing the ions insertion/extraction mechanisms

Rechargeable aqueous zinc ion batteries(AZIBs)were considered as one of the most promising candidates for large-scale energy storage due to the merits of high safety and inexpensiveness.As AZIBs cathode material,Mn O_(2)possesses great merits but was greatly hindered due to the sluggish diffusion kinetic of Zn^(2+) during electrochemical operations.Herein,deep Zn^(2+) ions intercalatedδ-Mn O_(2)(Zn-Mn O_(2))was achieved by the in situ electrochemical deposition route,which significantly enhanced the diffusion ability of Zn^(2+) due to the synergistic effects of Zn^(2+) pillars and structural H;O.The resultant Zn-Mn O_(2)based AZIBs delivers a record capacity of 696 m Ah/g(0.5 m Ah/cm^(2))based on the initial mass loading,which is approaching the theoretical capacity of Mn O_(2)with a two-electrons reaction.In-situ Raman studies reveal highly reversible Zn^(2+)ions insertion/extraction behaviors and here the Zn-Mn O_(2)plays the role of a container during the charge–discharge process.Further charge storage mechanism investigations point out the insertion/extraction of Zn^(2+) and H^(+) coincides,and such process is significantly facilitated results from superior interlayered configurations of Zn-Mn O_(2)The excellent electrochemical performance of Zn-Mn O_(2)achieved in this work suggests the deep ions pre-intercalation strategy may aid in the future development of advanced cathodes for AZIBs.

Emerging rechargeable aqueous magnesium ion battery

Recently,aqueous rechargeable batteries have played an essential role in developing renewable energy due to the merits of low cost,high security,and high energy density.Among various aqueous-based batteries,aqueous magnesium ion batteries(AMIBs)have rich reserves and high theoretical specific capacity(3833 mAh cm3).However,for future industrialization,AMIBs still face many scientific issues to be solved,such as the slow diffusion of magnesium ions in the material structure,the desolvation penalty at electrode-electrolyte interfaces,the cost of water-in-salt electrolyte,the low voltage of traditional aqueous electrolyte,etc.And yet a comprehensive summary of the components of AMIBs is lacking in the research community.This review mainly introduces the exploration and development of AMIB systems and related components.We conduct an in-depth study of the cathode materials appropriate for magnesium ion batteries from their crystal structures,focusing primarily on layered structures,spinel structures,tunnel structures,and three-dimensional framework structures.We also investigate the anode materials,ranging from inorganic materials to organic materials,as well as the electrolyte materials(from the traditional electrolyte to water-in-salt electrolyte).Finally,some perspectives on ensuing optimization design for future research efforts in the AMIBs field are summarized.