Research progresses on cathode materials of aqueous zinc-ion batteries

Electrochemical energy storage and conversion techniques that exhibit the merits such as high energy density,rapid response kinetics,economical maintenance requirements and expedient installation procedures will hold a pivotal role in the forthcoming energy storage technologies revolution.In recent years,aqueous zinc-ion batteries(AZIBs)have garnered substantial attention as a compelling candidate for large-scale energy storage systems,primarily attributable to their advantageous featu res encompassing cost-effectiveness,environmental sustainability,and robust safety profiles.Currently,one of the primary factors hindering the further development of AZIBs originates from the challenge of cathode materials.Specifically,the three mainstream types of mainstream cathode materials,in terms of manganese-based compounds,vanadium-based compounds and Prussian blue analogues,surfer from the dissolution of Mn~(2+),in the low discharge voltage,and the low specific capacity,respectively.Several strategies have been developed to compensation the above intrinsic defects for these cathode materials,including the ionic doping,defect engineering,and materials match.Accordingly,this review first provides a systematic summarization of the zinc storage mechanism in AZIBs,following by the inherent merit and demerit of three kind of cathode materials during zinc storage analyzed from their structure characteristic,and then the recent development of critical strategies towards the intrinsic insufficiency of these cathode materials.In this review,the methodologies aimed at enhancing the efficacy of manganese-based and vanadium-based compounds are emphasis emphasized.Additionally,the article outlines the future prospective directions as well as strategic proposal for cathode materials in AZIBs.

Adsorption of rubidium ion from aqueous solution by surface ion imprinted materials

A new type of rubidium ion-imprinted polymer has been synthesized by the surface-imprinting technique using methacrylic acid as the functional monomer,the rubidium ion as the template,methanol as the solvent,and silica as a carrier.Ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile were used as acrosslinker and an initiator,respectively.In addition,based on the macrocyclic effect of crown ethers,the 18-crown-6 ligand was introduced as a ligand to fix the template ions better.Scanning electron microscopy,zeta-potential analysis,Fourier transform infrared spectroscopy,thermogravimetric analysis,and X-ray photoelectron spectroscopy were performed to characterize the ion-imprinted polymer.The effects of the preparation and adsorption conditions on the adsorption performance of the rubidium ion-imprinted polymer were investigated.The results indicated that the rubidium ion-imprinted polymer has high selectivity and faster kinetics than other adsorbents,with an equilibrium adsorption capacity of 200.19 mg·g^(-1)at 298 K within 25 min.The sorption isotherm was well described by the Freundlich isotherm model,while the adsorption kinetics fitted the pseudo-second-order kinetic model.Consecutive adsorption-desorption experiments showed that the ion-imprinted polymer had good chemical stability and reusability.

Advances in Mn‑Based Electrode Materials for Aqueous Sodium‑Ion Batteries

Aqueous sodium-ion batteries have attracted extensive attention for large-scale energy storage applications,due to abundant sodium resources,low cost,intrinsic safety of aqueous electrolytes and eco-friendliness.The electrochemical performance of aqueous sodium-ion batteries is affected by the properties of electrode materials and electrolytes.Among various electrode materials,Mn-based electrode materials have attracted tremendous attention because of the abundance of Mn,low cost,nontoxicity,eco-friendliness and interesting electrochemical performance.Aqueous electrolytes having narrow electrochemical window also affect the electrochemical performance of Mn-based electrode materials.In this review,we introduce systematically Mn-based electrode materials for aqueous sodium-ion batteries from cathode and anode materials and offer a comprehensive overview about their recent development.These Mn-based materials include oxides,Prussian blue analogues and polyanion compounds.We summarize and discuss the composition,crystal structure,morphology and electrochemical properties of Mn-based electrode materials.The improvement methods based on electrolyte optimization,element doping or substitution,optimization of morphology and carbon modification are highlighted.The perspectives of Mn-based electrode materials for future studies are also provided.We believe this review is important and helpful to explore and apply Mn-based electrode materials in aqueous sodium-ion batteries.

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.

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.

Organic 3D interconnected graphene aerogel as cathode materials for high-performance aqueous zinc ion battery

Aqueous rechargeable zinc ion batteries are very attractive in large-scale storage applications,because they have high safety,low cost and good durability.Nonetheless,their advancements are hindered by a dearth of positive host materials(cathode)due to sluggish diffusion of Zn2+in the solid inorganic frameworks.Here,we report a novel organic electrode material of poly 3,4,9,10-perylentetracarboxylic dianhydride(PPTCDA)/graphene aerogel(GA).The 3D interconnected porous architecture synthesized through a simple solvothermal reaction,where the PPTCDA is homogenously embedded in the GA nanosheets.The self-assembly of PPTCDA/GA coin-type cell will not only significantly improve the durability and extend lifetime of the devices,but also reduce the electronic waste and economic cost.The self-assembled structure does not require the auxiliary electrode and conductive agent to prepare the electrode material,which is a simple method for preparing the coin-type cell and a foundation for the next large-scale production.The PPTCDA/GA delivers a high capacity of≥200 m Ah g^–1 with the voltage of 0.0~1.5 V.After 300 cycles,the capacity retention rate still close to 100%.The discussion on the mechanism of Zn2+intercalation/deintercalation in the PPTCDA/GA electrode is explored by Fourier transform infrared spectrometer(FT-IR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)characterizations.The morphology and structure of PPTCDA/GA are examined by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).

Electrode materials for aqueous multivalent metal-ion batteries: Current status and future prospect

In recent years,the pursuit of high-efficiency electrochemical storage technology,the multivalent metalion batteries (MIBs) based on aqueous electrolytes have been widely explored by researchers because of their safety,environmental friendliness,abundant reserves and low price,and especially the merits in energy and power densities.This review firstly expounds on the problems existing in the electrode materials of aqueous multivalent MIBs (Zn^(2+),Mg^(2+),Al^(3+),Ca^(2+)),from the classical inorganic materials to the emerging organic compounds,and then summarizes the design strategies in bulk and interface structure of electrodes with favorable kinetics and stable cycling performance,especially laying the emphasis on the charge storage mechanism of cathode materials and dendrite-free Zinc anode from the aspect of electrolyte optimization strategies,which can be extended to other aqueous multivalent MIBs.Ultimately,the possible development directions of the aqueous multivalent MIBs in the future are provided,anticipating to provide a meaningful guideline for researchers in this area.

Pairing nitroxyl radical and phenazine with electron-withdrawing/-donating substituents in “water-in-ionic liquid” for high-voltage aqueous redox flow batteries

Aqueous redox-active organic materials-base electrolytes are sustainable alternatives to vanadium-based electrolyte for redoxflow batteries(RFBs)due to the advantages of high ionic conductivity,environmentally benign,safety and low cost.However,the underexplored redox properties of organic materials and the narrow thermodynamic electrolysis window of water(1.23 V)hinder their wide applications.Therefore,seeking suitable organic redox couples and aqueous electrolytes with a high output voltage is highly suggested for advancing the aqueous organic RFBs.In this work,the functionalized phenazine and nitroxyl radical with electron-donating and electron-withdrawing group exhibit redox potential of-0.88 V and 0.78 V vs.Ag,respectively,in“water-in-ionic liquid”supporting electrolytes.Raman spectra reveal that the activity of water is largely suppressed in“water-in-ionic liquid”due to the enhanced hydrogen bond interactions between ionic liquid and water,enabling an electrochemical stability window above 3 V.“Water-in-ionic liquid”supporting electrolytes help to shift redox potential of nitroxyl radical and enable the redox activity of functionalized phenazine.The assembled aqueous RFB allows a theoretical cell voltage of 1.66 V and shows a practical discharge voltage of 1.5 V in the“water-in-ionic liquid”electrolytes.Meanwhile,capacity retention of 99.91%per cycle is achieved over 500 charge/discharge cycles.A power density of 112 mW cm^(-2) is obtained at a current density of 30 mA cm^(-2).This work highlights the importance of rationally combining supporting electrolytes and organic molecules to achieve high-voltage aqueous RFBs.

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.

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.

Plotting the Clarifying Curves and Determination of the Specific Amount of Settled Material during the Initial Period to Sedimentation in Stationary Column of Aqueous Suspensions of Solids

The present paper presents an algorithm and a program for plotting the clarifying curves and for determination of the specific amount of settled material during the initial period based on data obtained from sedimentation experiments in stationary column of aqueous suspensions of solids particles with different concentrations. The algorithm and program have been developed for an interactive, rapid and convenient processing of the data obtained from sedimentation experiments in stationary column of aqueous suspensions of solids particles and allow obtaining with accuracy of precise and expressive graphs which characterize the behaviour of aqueous suspensions to sedimentation in stationary column. Sedimentation study of different aqueous suspensions of solids particles in stationary column is of great importance for experimentally determining the important parameters required to design and exploitation clarifiers and sludge thickeners from waste water treatment plants.

Research status and perspectives of MXene-based materials for aqueous zinc-ion batteries

Aqueous zinc-ion batteries(AZIBs)as green battery systems have attracted widespread attention in large-scale electrochemical energy storage devices,owing to their high safety,abundant Zn materials,high theoretica specific capacity and low redox potential.Nevertheless there are some thorny issues in AZIBs that hinder their practical application,such as low intrinsic electron conductivity,slow ion migration kinetics,zinc dendrites and side reactions.MXene-based materials with superior conductivity,large polar surface and abundant active sites can simultaneously serve as cathode materials,electrolyte additive and protection layer of anode to regulate redox reactions of AZIBs.Although various materials have been used to improve electrochemical performances of AZIBs there is a lack of in-depth discussion on the regulation mechanism of MXene-based materials for AZIBs.In this review,we elaborate the research progress of MXenebased materials in AZIBs,including their application in cathode materials and inhibition of zinc dendrites.Finally the future prospects and development directions of MXenebased materials that may improve performance of AZIBs are prospected.

Advanced organic electrode materials for aqueous rechargeable batteries

Organic electrode materials take advantages of potentially sustainable production and structural tunability compared with present commercial inorganic electrode materials.However,their applications in traditional rechargeable batteries with nonaqueous electrolytes suffer from the premature failure and safety concerns.In comparison,aqueous rechargeable batteries based on organic electrode materials have received extensive attentions in recent years for low-cost and sustainable energy storage systems due to their inherent safety.This review aims to provide a comprehensive summary on the recent progress in advanced organic electrode materials for aqueous rechargeable batteries.We start from the overview of working principles and general design strategies of organic electrode materials in aqueous rechargeable batteries.Then the research advances of organic electrode materials in various aqueous rechargeable batteries are highlighted in terms of charge carriers(monovalent ions,multivalent ions,and anions).We emphasized the characteristics of organic electrode materials in various charge carriers.Finally,the critical challenges and future efforts of aqueous organic rechargeable batteries are discussed.More organic electrode materials with better electronic conductivity and fast reaction kinetics are still needed to build advanced aqueous batteries for commercial applications.

Functional carbon materials for high-performance Zn metal anodes

The realization of“carbon peak”and“carbon neutralization”highly depends on the efficient utilization of renewable energy sources.Exploring reliable and low-cost electrochemical energy storage systems is an ever-growing demand for renewable energy integration.Among available candidates,aqueous zinc-ion batteries(AZIBs)receive extensive researchers'attention because of their material abundance,high capacity,high safety,and environmental friendliness.However,the irreversible issues of Zn anode in terms of notorious dendric Zn growth,Zn corrosion/hydrogen evolution,and passivation significantly impede the commercialization of high-performance AZIBs.Carbon materials have advantages of large specific surface area,low cost,high electrical conductivity,controllable structure,and good stability.Their application provides remedies for improving the comprehensive performance of Zn anodes.In this review,the fundamentals and issues of Zn anodes,and the research progress with functional carbon materials for Zn anodes in recent years are presented.Three major strategies are described in detail,including the use of carbon materials(carbon nanotubes,graphene,carbon fiber,metal-organic framework(MOF)derived host,etc.)as Zn plating/stripping substrates,as protective coating layers on Zn,and as electrolyte additives.Finally,the remaining challenges and perspectives of carbon materials in high-performance AZIBs are outlined.

Engineered nitrogen doping on VO_(2)(B)enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries

Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries(AZIBs).Nevertheless,their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application.Herein,a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO_(2)(B)nanobelts(denoted as VO_(2)-N)by the ammonia heat treatment.Compared with pure VO_(2)(B),VO_(2)-N shows an expanded lattice,reduced grain size,and disordered structure,which facilitates ion transport,provides additional ion storage sites,and improves structural durability,thus presenting much-enhanced zinc-ion storage performance.Density functional theory calculations demonstrate that nitrogen doping in VO_(2)(B)improves its electronic properties and reduces the zinc-ion diffusion barrier.The optimal VO_(2)-N400 electrode exhibits a high specific capacity of 373.7 mA h g^(-1)after 100 cycles at 0.1 A g^(-1)and stable cycling performance after 2000 cycles at 5 A g^(-1).The zinc-ion storage mechanism of VO_(2)-N is identified as a typical intercalation/de-intercalation process.

An Environment-Friendly High-Performance Aqueous Mg-Na Hybrid-Ion Battery Using an Organic Polymer Anode

Aqueous Mg ion batteries(AMIBs)show great potential in energy storage for their advantages of high capacity,abundant resource,and environmental friendliness.However,the development of AMIBs is limited due to the scarcity of suitable anode materials.In this study,a new polymer anode material(PNTAQ)with flower-like nanosheet structure is synthesized for aqueous Mg-Na hybrid-ion battery(AMNHIB).PNTAQ possess carbonyl functional groups which can be oxidized and reduced reversibly in aqueous solution containing alkaline metal ions.PNTAQ displays a discharge specific capacity of 245 mAh g^(−1)at 50 mA g^(−1)in 1 M MgCl_(2)+0.5 M NaCl electrolyte,which is much higher than that in single 1 M MgCl_(2)or 0.5 M NaCl electrolyte.Even cycling at 1000 mA g^(−1)for 1000 times,the capacity retention can still maintain at 87.2%.A full Mg-Na hybrid-ion cell is assembled by employingβ-MnO_(2)as cathode and PNTAQ as anode material,it exhibits a specific capacity of 91.6 mAh g^(−1)at 100 mA g^(−1).The polymer electrode material well maintains its framework structure during the discharge/charge cycling process of the hybrid-ion battery.

A high-capacity viologen-based anolyte for high energy density neutral pH aqueous redox-flow batteries

Redox-flow batteries(RFBs)are a promising energy storage technology with remarkable scalability and safety for storing vast amounts of renewable energy and mitigating outputfluctuations of renewable power grids.We demonstrate a neutral pH aqueous RFB using a custom-designed 1’,1’’’,1’’’’’-(benzene-1,3,5-triyltris(methylene))tris(1-(3-(trimethyl ammonio)propyl)-[4’’,4’’’-bipyridine]-1,1’-diium)nonachloride(BTTMPB)as a 3 e-storage anolyte.The custom design with the high polarization in charge density has led to the excellent water solubility of 4.0 M in H_(2)O(321.6 A h L^(-1))and 2.4 M in 2.0 M NaCl(192.9 A h L^(-1)).The density functional theory(DFT)calculations and electrochemical experiments have shown 3 e-storage response of BTTMPB with a diffusion coefficient of 3.1×10^(-6)cm^(2) s^(-1)and rate con-stant of 1.6×10^(-2)cm s^(-1) for thefirst reduction process.The synthesized anolyte was paired with(Ferrocenylmethyl)trimethylammonium chloride(FcNCl)as catholyte enabling a 0.92 V aqueous RFB with 125.9 W h L^(-1)theoretical energy density.The aqueous RFB has an excellent cycling performance from 10-30 m A cm^(-2),energy efficiency up to 80%,capacity retention of 99.96%per cycle at 20 m A cm^(-2),and a high demonstrated energy density of 29.1 W h L^(-1).

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.

Issues and strategies of cathode materials for mild aqueous static zinc-ion batteries

Researchers prefer mild aqueous static zinc-ion batteries(ASZIBs)for their distinct benefits of excellent safety,abundant zinc resources,low cost,and high energy density.However,at the moment there are some issues with the cathode materials of mild ASZIBs,including dissolution,by-products,poor conductivity,and a contentious energy storage system.Consequently,there are numerous difficulties in the development of high-performance mild ASZIBs cathode materials.This overview examines the mechanisms for storing energy and the de-velopments in inorganic,organic,and other novel cathode materials that have emerged in recent years.At the same time,three solutions—structural engineering,interface engineering,and reaction pathway engineering—as well as the difficulties now faced by the cathode materials of mild ASZIBs are forcefully introduced.Finally,a prospect is made regarding the evolution of cathode materials in the future.