Zinc–Bromine Rechargeable Batteries:From Device Configuration,Electrochemistry,Material to Performance Evaluation

Zinc–bromine rechargeable batteries(ZBRBs)are one of the most powerful candidates for next-generation energy storage due to their potentially lower material cost,deep discharge capability,non-flammable electrolytes,relatively long lifetime and good reversibility.However,many opportunities remain to improve the efficiency and stability of these batteries for long-life operation.Here,we discuss the device configurations,working mechanisms and performance evaluation of ZBRBs.Both non-flow(static)and flow-type cells are highlighted in detail in this review.The fundamental electrochemical aspects,including the key challenges and promising solutions,are discussed,with particular attention paid to zinc and bromine half-cells,as their performance plays a critical role in determining the electrochemical performance of the battery system.The following sections examine the key performance metrics of ZBRBs and assessment methods using various ex situ and in situ/operando techniques.The review concludes with insights into future developments and prospects for high-performance ZBRBs.

Metal-organic frameworks based single-atom catalysts for advanced fuel cells and rechargeable batteries

The next-generation energy storage systems such as fuel cells,metal-air batteries,and alkali metal(Li,Na)-chalcogen(S,Se)batteries have received increasing attention owing to their high energy density and low cost.However,one of the main obstacles of these systems is the poor reaction kinetics in the involved chemical reactions.Therefore,it is essential to incorporate suitable and efficient catalysts into the cell.These years,single-atom catalysts(SACs)are emerging as a frontier in catalysis due to their maximum atom efficiency and unique reaction selectivity.For SACs fabrication,metal-organic frameworks(MOFs)have been confirmed as promising templates or precursors due to their high metal loadings,structural adjustability,porosity,and tailorable catalytic site.In this review,we summarize effective strategies for fabricating SACs by MOFs with corresponding advanced characterization techniques and illustrate the key role of MOFs-based SACs in these batteries by explaining their reaction mechanisms and challenges.Finally,current applications,prospects,and opportunities for MOFs-based SACs in energy storage systems are discussed.

3D printing critical materials for rechargeable batteries: from materials, design and optimization strategies to applications

Three-dimensional(3D)printing,an additive manufacturing technique,is widely employed for the fabrication of various electrochemical energy storage devices(EESDs),such as batteries and supercapacitors,ranging from nanoscale to macroscale.This technique offers excellent manufacturing flexibility,geometric designability,cost-effectiveness,and eco-friendliness.Recent studies have focused on the utilization of 3D-printed critical materials for EESDs,which have demonstrated remarkable electrochemical performances,including high energy densities and rate capabilities,attributed to improved ion/electron transport abilities and fast kinetics.However,there is a lack of comprehensive reviews summarizing and discussing the recent advancements in the structural design and application of 3D-printed critical materials for EESDs,particularly rechargeable batteries.In this review,we primarily concentrate on the current progress in 3D printing(3DP)critical materials for emerging batteries.We commence by outlining the key characteristics of major 3DP methods employed for fabricating EESDs,encompassing design principles,materials selection,and optimization strategies.Subsequently,we summarize the recent advancements in 3D-printed critical materials(anode,cathode,electrolyte,separator,and current collector)for secondary batteries,including conventional Li-ion(LIBs),Na-ion(SIBs),K-ion(KIBs)batteries,as well as Li/Na/K/Zn metal batteries,Zn-air batteries,and Ni–Fe batteries.Within these sections,we discuss the 3DP precursor,design principles of 3D structures,and working mechanisms of the electrodes.Finally,we address the major challenges and potential applications in the development of 3D-printed critical materials for rechargeable batteries.

Progress in aqueous rechargeable batteries

Over the past decades, a series of aqueous rechargeable batteries(ARBs) were explored, investigated and demonstrated. Among them,aqueous rechargeable alkali-metal ion(Li^+Na^+, K^+) batteries, aqueous rechargeable-metal ion(Zn^(2+),Mg^(2+), Ca^(2+), Al^(3+)) batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. By critically reviewing state-of-the-art technologies and the most promising results so far, we aim to analyze the benefits of ARBs and the critical issues to be addressed, and to promote better development of ARBs.

Nanohollow Carbon for Rechargeable Batteries:Ongoing Progresses and Challenges

Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.

Halogen Storage Electrode Materials for Rechargeable Batteries

The ever-increasing demand for rechargeable batteries with high energy density,abundant resources,and high safety has pushed the development of various battery technologies based on cation,anion,or dual-ion transfer.The use of halogen storage electrode materials has led to new concept battery systems such as halide-ion batteries(HIB)and dual-ion batteries(DIB).This review highlights the recent progress on these electrode materials,including metal(oxy)halides,layered double hydroxides,MXenes,graphite-based materials,and organic materials with carbon or nitrogen redox centers.The reversible electrochemical halogen storage of halide ions(e.g.,F^(−),Cl^(−),and Br^(−)),dual halogen(e.g.,Br_(m)Cl_(n) and [ICl_(2)]^(−)),or binary halide anions(e.g.,PF_(6)^(−),AlCl_(4)^(−),[ZnCl_(x)]^(2−x),and [MgCl_(x)]^(2−x)) in the electrodes is covered.The challenges and mechanisms of halogen storage in various electrode materials in HIBs and DIBs are summarized and analyzed,providing insights into the development of high-performance halogen storage electrode materials for rechargeable batteries.

Two-dimensional metal oxide nanosheets for rechargeable batteries

Two-dimensional（2D） metal oxide nanosheets have attracted much attention as potential electrode materials for rechargeable batteries in recent years. This is primarily due to their natural abundance, environmental compatibility, and low cost as well as good electrochemical properties. Despite the fact that most metal oxides possess low conductivity, the introduction of some conductive heterogeneous components, such as nano-carbon, carbon nanotubes（CNTs）, and graphene, to form metal oxide-based hybrids,can effectively overcome this drawback. In this mini review, we will summarize the recent advances of three typical 2D metal oxide nanomaterials, namely, binary metal oxides, ternary metal oxides, and hybrid metal oxides, which are used for the electrochemical applications of next-generation rechargeable batteries, mainly for lithium-ion batteries（LIBs） and sodium-ion batteries（SIBs）. Hence, this review intends to functionalize as a good reference for the further research on 2D nanomaterials and the further development of energy-storage devices.

Reinventing the mechanism of high-performance Bi anode in aqueous K^+ rechargeable batteries

Increasing attention has been paid to rechargeable aqueous batteries due to their high safety and low cost.However,they remain in their infancy because of the limited choice of available anode materials with high specific capacity and satisfying cycling performance.Bi metal with layered structure can act as an ideal anode material with high capacity;however,the energy storage mechanism has not well elucidated.Herein,we demonstrate that Bi metal enables affording ultra-high specific capacity(254.3 mAh g^-1),superior rate capability and a capacity retention of 88.8%after 1600 cycles.Different from the previously-reported redox reaction mechanisms of Bi electrode,efficient(de)alloying of K+is responsible for its excellent performance.An excellent aqueous Bi battery is fabricated by matching Bi anode with Co(OH)2 cathode in KOH(1 M)electrolyte.Its outstanding performance is quite adequate and competitive for electrochemical energy storage devices.

Electrochemical Impedance Spectroscopy Study on Novel Carbon-Sulfur Nano-Composite Cathodes in Lithium Rechargeable Batteries

Carbon-sulfur nano-composite cathodes for lithium rechargeable batteries were investigated by electrochemical impedance spectroscopy (EIS). The novel carbon-sulfur nano-composite material was synthesized by heating sublimed sulfur and high surface area activated carbon (HSAAC) in certain conditions. Equivalent circuits were used to fit the spectra at different discharge states. The variations of impedance spectra, charge-transfer resistance and double layer capacitance were discussed. The changes of EIS with potential were analyzed based on a plausible electrical equivalent circuit model, and some parameters were measured and analyzed about electrochemical performance and state of charge and discharge of the electrode. The good accuracy in fitting values of the model to the experimental data indicates that the mathematical model gives out a satisfying description upon the mechanism of high rate of capacity fade in lithium-sulfur battery.

The application of synchrotron X-ray techniques to the study ofrechargeable batteries

The increased use of rechargeable batteries in portable electronic devices and the continuous develop-ment of novel applications （e.g. transportation and large scale energy storage）, have raised a strong de-mand for high performance batteries with increased energy density, cycle and calendar life, safety andlower costs. This triggers significant efforts to reveal the fundamental mechanism determining batteryperformance with the use of advanced analytical techniques. However, the inherently complex character-istics of battery systems make the mechanism analysis sophisticated and difficult. Synchrotron radiationis an advanced collimated light source with high intensity and tunable energies. It has particular ad-vantages in electronic structure and geometric structure （both the short-range and long-range structure）analysis of materials on different length and time scales. In the past decades, synchrotron X-ray tech-niques have been widely used to understand the fundamental mechanism and guide the technologicaloptimization of batteries. In particular, in situ and operando techniques with high spatial and temporalresolution, enable the nondestructive, real time dynamic investigation of the electrochemical reaction,and lead to significant deep insights into the battery operation mechanism. This review gives a brief introduction of the application of synchrotron X-ray techniques to the inves-tigation of battery systems. The five widely implicated techniques, including X-ray diffraction （XRD）, PairDistribution Function （PDF）, Hard and Soft X-ray absorption spectroscopy （XAS） and X-ray photoelectronspectroscopy （XPS） will be reviewed, with the emphasis on their in situ studies of battery systems during cycling.

Advanced metal–organic frameworks for aqueous sodium-ion rechargeable batteries

Inexpensive and abundant sodium resources make energy storage systems using sodium chemistry promising replacements for typical lithium-ion rechargeable batteries(LIBs).Fortuitously,aqueous sodium-ion rechargeable batteries(ASIBs),which operate in aqueous electrolytes,are cheaper,safer,and more ionically conductive than batteries that operate in conventional organic electrolytes;furthermore,they are suitable for grid-scale energy storage applications.As electrode materials for storing Na~+ ions in ASIBs,a variety of multifunctional metal-organic frameworks(MOFs) have demonstrated great potential in terms of having porous 3 D crystal structures,compatibility with aqueous solutions,long cycle lives(≥1000 cycles),and ease of synthesis.The present review describes MOF-derived technologies for the successful application of MOFs to ASIBs and suggests future challenges in this area of research based on the current understanding.

Synthesis of CDMO from LiOH and EMD and the Performances of Li/CDMO Rechargeable Batteries

The synthesis of CDMO from LiOH and EMD has been investigated by thermogravimetry and pow- der X-ray diffraction analysis.The results showed that it took place from below 100 to 400℃.When the proportion of Li:Mn in the starting mixture was 3:7,the measured weight loss during this process was 7.40% for heat-treated EMD and 8.33% for non-heat-treated EMD.Based on these data and X-ray diffraction results the obtained product would be 3LiMn204 - MnO2.This material was es- sentially amorphous.It can insert 4.7 Li per 3LiMn_2O_4·MnO_2,leading to a capacity of 170- 200 mAh/g and demonstrated reasonable discharge and recharge cycle performance for both test cells and practical batteries.

Roadmap for rechargeable batteries:present and beyond

Rechargeable batteries currently hold the largest share of the electrochemical energy storage market,and they play a major role in the sustainable energy transition and industrial decarbonization to respond to global climate change.Due to the increased popularity of consumer electronics and electric vehicles,lithium-ion batteries have quickly become the most successful rechargeable batteries in the past three decades,yet growing demands in diversified application scenarios call for new types of rechargeable batteries.Tremendous efforts are made to developing the next-generation post-Li-ion rechargeable batteries,which include,but are not limited to solid-state batteries,lithium–sulfur batteries,sodium-/potassium-ion batteries,organic batteries,magnesium-/zinc-ion batteries,aqueous batteries and flow batteries.Despite the great achievements,challenges persist in precise understandings about the electrochemical reaction and charge transfer process,and optimal design of key materials and interfaces in a battery.This roadmap tends to provide an overview about the current research progress,key challenges and future prospects of various types of rechargeable batteries.New computational methods for materials development,and characterization techniques will also be discussed as they play an important role in battery research.

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.

Mn-based cathode materials for rechargeable batteries

The rapid expansion of renewable energies asks for great progress of energy-storage technologies for sustainable energy supplies,which raises the compelling demand of high-performance rechargeable batteries.To satisfy the huge demand from the coming energy-storage market,the resource and cost-effectiveness of rechargeable batteries become more and more important.Manganese(Mn)as a key transition element with advantages including high abundance,low cost,and low toxicity derives various kinds(spinels,layered oxides,polyanions,Prussian blue analogs,etc.)of high-performance Mn-based electrode materials,especially cathodes,for rechargeable batteries ranging from Li-ion batteries,Na-ion batteries,aqueous batteries,to multivalent metal-ion batteries.It is anticipated that Mn-based materials with Mn as the major transition-metal element will constitute a flourishing family of Mn-based rechargeable batteries(Mn RBs)for large-scale and differentiated energy-storage applications.On the other hand,several critical issues including Jahn-Teller effect,Mn dissolution,and O release greatly hinder the pace of Mn RBs,which require extensive material optimizations and battery/system improvements.This review aims to provide an investigation about Mn-based materials and batteries for the coming energy-storage demands,with compelling issues and challenges that must be overcome.

Electrode particulate materials for advanced rechargeable batteries:A review

The demand for large-scale energy storage is increasing due to the decreasing non-renewable resources and deteriorating environmental pollution.Developing rechargeable batteries with high energy density and long cycle performance is an ideal choice to meet the demand of energy storage system.The development of excellent electrode particles is of great significance in the commercialization of nextgeneration batteries.The ideal electrode particles should balance raw material reserves,electrochemical performance,price and environmental protection.Among them,the development of electrode particulate materials with excellent electrochemical properties is the top priority at present.In this review,the typical researches of electrode materials are summarized in terms of crystal structure,morphology,pore structure,surface and interface regulation.Firstly,the structural characteristics and improvement methods of transition metal oxides,polyanionic compounds,Prussian blue and their analogues are introduced.Then,the different effects of particulate morphology,pore,surface and interface structure on the performance of electrode materials are discussed.For designing high-performance electrode materials,preparation route should be set according to the particle properties of the materials and the synergistic effect of various optimization methods should be adopted.At the same time,in addition to the electrode materials,other components of the rechargeable batteries,such as current collector,separator and electrolytes,should be optimized to improve the overall performance of the batteries.This review would provide important guiding principle for designing high-performance electrode particulate materials.

Heteroatom anchors Fe-Mn dual-atom catalysts with bi-functional oxygen catalytic activity for low-temperature rechargeable flexible Zn-air batteries

M-N-C(M=Fe,Co,Ni,etc.) catalyst owns high catalytic activity in the oxygen catalytic reaction which is the most likely to replace the Pt-based catalysts.But it is still a challenge to further increase the active site density.This article constructs the high-efficiency FeMn-N/S-C-1000 catalyst to realize ORR/OER bifunctional catalysis by hetero-atom,bimetal(Fe,Mn) doped simultaneously strategy.When evaluated it as bi-functional electro-catalysts,FeMn-N/S-C-1000 exhibits excellent catalytic activity(E_(1/2)=0.924 V,E_(j=10)=1.617 V) in alkaline media,outperforms conventional Pt/C,RuO_(2) and most non-precious-metal catalysts reported recently,Such outstanding performance is owing to N,S co-coordinated with metal to form multi-types of single atom,dual atom active sites to carry out bi-catalysis.Importantly,nitrite poison test provides the proof that the active sites of FeMn-N/S-C are more than that of single-atom catalysts to promote catalytic reactions directly.To better understand the local structure of Fe and Mn active sites,XAS and DFT were employed to reveal that FeMn-N_5/S-C site plays the key role during catalysis.Notably,the FeMn-N/S-C-1000 based low-temperature rechargeable flexible Zn-air also exhibits superior discharge performance and extraordinary durability at-40℃.This work will provide a new idea to design diatomic catalysts applied in low-temperature rechargeable batteries.

In situ Raman,FTIR,and XRD spectroscopic studies in fuel cells and rechargeable batteries

As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance,which mainly rely on the rational design of catalysts,electrode materials,and electrode/electrolyte interfaces in EESC,based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions.Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques,such as in situ Raman,Fourier transform infrared(FTIR),and X-ray diffraction(XRD)spectroscopy.These techniques can provide characteristic spectroscopic information of molecules and/or crystals,which are sensitive to structure/phase changes resulted from different electrochemical working conditions,hence allowing for intermediates identification and mechanisms understanding.This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman,FTIR,and XRD spectroscopy.The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction(ORR)in fuel cells,on representative high capacity and/or resource abundance cathodes and anodes,and on the solid electrolyte interface(SEI)in rechargeable batteries are discussed.We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.

Electrolyte additive enhances the electrochemical performance of Cu for rechargeable Cu//Zn batteries

Cu-based cathodes in aqueous batteries become very attractive in view of high theoretical capacity,moderate operation voltage and rich reserves of raw materials.However,their applications are obstructed by serious side reactions.The side reaction mainly arises from the spontaneous formation of Cu_(2)O,which occupies the electrode surface and lowers the reaction reversibility.Here,Na_(2)EDTA is introduced to address these issues.Both experimental results and theoretical calculations indicate that the Na_(2)EDTA reshapes the solvation structure of Cu^(2+)and modifies the electrode/electrolyte interface.Therefore,the redox potential of Cu^(2+)/Cu_(2)O is reduced and the surface of Cu is protected from H2O,thereby inhibiting the formation of Cu_(2)O.Meanwhile,the change in the solvation structure reduces the electrostatic repulsion between Cu^(2+)and the cathode,leading to high local concentration and benefiting uniform deposition.The results shed light on the applications of rechargeable Cu-based batteries.

Aerophilic Triphase Interface Tuned by Carbon Dots Driving Durable and Flexible Rechargeable Zn‑Air Batteries

Efficient bifunctional catalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are vital for rechargeable Zn-air batteries(ZABs).Herein,an oxygen-respirable sponge-like Co@C–O–Cs catalyst with oxygen-rich active sites was designed and constructed for both ORR and OER by a facile carbon dot-assisted strategy.The aerophilic triphase interface of Co@C–O–Cs cathode efficiently boosts oxygen diffusion and transfer.The theoretical calculations and experimental studies revealed that the Co–C–COC active sites can redistribute the local charge density and lower the reaction energy barrier.The Co@C–O–Cs catalyst displays superior bifunctional catalytic activities with a half-wave potential of 0.82 V for ORR and an ultralow overpotential of 294 mV at 10 mA cm^(−2) for OER.Moreover,it can drive the liquid ZABs with high peak power density(106.4 mW cm^(−2)),specific capacity(720.7 mAh g^(−1)),outstanding long-term cycle stability(over 750 cycles at 10 mA cm^(−2)),and exhibits excellent feasibility in flexible all-solid-state ZABs.These findings provide new insights into the rational design of efficient bifunctional oxygen catalysts in rechargeable metal-air batteries.