The safety aspect of sodium ion batteries for practical applications

Sodium-ion batteries(SIBs)with advantages of abundant resource and low cost have emerged as promising candidates for the next-generation energy storage systems.However,safety issues existing in electrolytes,anodes,and cathodes bring about frequent accidents regarding battery fires and explosions and impede the development of high-performance SIBs.Therefore,safety analysis and high-safety battery design have become prerequisites for the development of advanced energy storage systems.The reported reviews that only focus on a specific issue are difficult to provide overall guidance for building high-safety SIBs.To overcome the limitation,this review summarizes the recent research progress from the perspective of key components of SIBs for the first time and evaluates the characteristics of various improvement strategies.By orderly analyzing the root causes of safety problems associated with different components in SIBs(including electrolytes,anodes,and cathodes),corresponding improvement strategies for each component were discussed systematically.In addition,some noteworthy points and perspectives including the chain reaction between security issues and the selection of improvement strategies tailored to different needs have also been proposed.In brief,this review is designed to deepen our understanding of the SIBs safety issues and provide guidance and assistance for designing high-safety SIBs.

Progress in electrolyte and interface of hard carbon and graphite anode for sodiumion battery

It is essential to replace lithium-ion batteries(LIBs)from the perspective of the Earth's resources and the sustainable development of mankind.Sodium-ion batteries(SIBs)are important candidates due to their low price and abundant storage capacity.Hard carbon(HC)and graphite have important applications in anode materials of SIBs.In this review,the research progress in electrolyte and interface between HC and graphite anode for SIBs is summarized.The properties and performance of three types of widely used electrolytes(carbo nate ester,ether,and ionic liquid)with additives,as well as the formation of solid electrolyte interface(SEI),which are crucial to the reversible capacity and rate capability of HC anodes,are also discussed.In this review,the co-intercalation performance and mechanism of solvation Na+into graphite are summarized.Besides,the faced challenges and existing problems in this field are also succinctly highlighted.

A perspective on the Li-ion battery

In the 1960s,Rouxel in France and Robert Schroeder in Germany explored the chemistry of reversible intercalation of Li^+between MS2(M=transition metal)layers held together by weak Van der Waals bonding[1].In 1967,Kummer and Webber of the Ford Motor Co.had discovered fast 2D Na+diffusion at 300℃in incompletely occupied Na^+and O layers between spinel blocks of an aluminum oxide and had invented a sodium-sulfur battery operating above 300℃.

Prussian-blue materials:Revealing new opportunities for rechargeable batteries

The demand to increase energy density of rechargeable batteries for portable electronic devices and electric vehicles and to reduce the cost for grid-scale energy storage necessitates the exploration of new chemistries of electrode materials for rechargeable batteries.The open framework-structure of Prussian-blue materials has recently been demonstrated as a promising cathode host for a variety of monovalent and multivalent cations with the tunable working voltage and discharge capacities.Recent progress toward the application of Prussian-blue cathode materials for rechargeable batteries is reviewed,with special emphasis on charge-storage mechanisms of different insertion species,factors influencing electrochemical performances,and possible approaches to overcome their intrinsic limitations.

The prospect and challenges of sodium-ion batteries for low-temperature conditions

In recent years,considerable attention has been focused on the development of sodium-ion batteries(SIBs)because of the natural abundance of raw materials and the possibility of low cost,which can alleviate the concerns of the limited lithium resources and the increasing cost of lithium-ion batteries.With the growing demand for reliable electric energy storage devices,requirements have been proposed to further increase the comprehensive performance of SIBs.Especially,the low-temperature tolerance has become an urgent technical obstacle in the practical application of SIBs,because the low operating temperature will lead to sluggish electrochemical reaction kinetics and unstable interfacial reactions,which will deteriorate the performance and even cause safety issues.On the basis of the charge-storage mechanism of SIBs,optimization of the composition and structure of electrolyte and electrode materials is crucial to building SIBs with high performance at low temperatures.In this review,the recent research progress and challenges were systematically summarized in terms of electrolytes and cathode and anode materials for SIBs operating at low temperatures.The typical full-cell configurations of SIBs at low temperatures were introduced to shed light on the fundamental research and the exploitation of SIBs with high performance for practical applications.

Formation of Stable Interphase of Polymer-in-Salt Electrolyte in All-Solid-State Lithium Batteries

The integration of solid-polymer electrolytes into all-solid-state lithium batteries is highly desirable to overcome the limitations of current battery configurations that have a low energy density and severe safety concerns.Polyacrylonitrile is an appealing matrix for solid-polymer electrolytes;however,the practical utilization of such polymer electrolytes in all-solid-state cells is impeded by inferior ionic conductivity and instability against a lithium-metal anode.In this work,we show that a polymer-in-salt electrolyte based on polyacrylonitrile with a lithium salt as the major component exhibits a wide electrochemically stable window,a high ionic conductivity,and an increased lithium-ion transference number.The growth of dendrites from the lithium-metal anode was suppressed effectively by the polymer-in-salt electrolyte to increase the safety features of the batteries.In addition,we found that a stable interphase was formed between the lithium-metal anode and the polymer-in-salt electrolyte to restrain the uncontrolled parasitic reactions,and we demonstrated an all-solid-state battery configuration with a LiFePO4 cathode and the polymer-in-salt electrolyte,which exhibited a superior cycling stability and rate capability.