摘要
聚合物基固体电解质在高能量密度和高安全性固态电池领域具有良好的应用前景.然而,现有的聚合物基固体电解质在应用时仍然面临室温离子电导率低、电解质/电极界面接触差、电化学窗口窄等严峻挑战.本文从聚合物基固体电解质离子电导率的提升和界面性能的改善出发,重点阐述聚合物基固体电解质的发展现状及优化策略.首先,从两个方面总结了聚合物基固体电解质离子电导率的定向优化策略:构建连续、定向取向的离子传输路径和缩短离子传输距离;其次,总结了聚合物基固体电解质/电极之间的界面优化策略:构建润湿界面和制作非对称电解质,以降低电解质/电极的界面电阻,提升电解质/电极的界面相容性;最后,对聚合物基固体电解质和固态电池的发展前景进行了展望,并提出了该领域的重点发展方向以及先进的分析测试方法,为聚合物基固体电解质的研究和发展提供全面的了解和深入的指导.
Since the commercialization of lithium-ion batteries in the 1990 s,lithium-ion batteries have been successfully applied in portable electronics,electric vehicles,and grid energy storage.Although current organic liquid electrolytes have high ionic conductivities,they are inherently flammable,volatile,and prone to leakage.Moreover,severe side reactions and dendrite growth on the surface of the lithium anode during the charge-discharge process can cause safety hazards,which greatly impede their applications in lithium metal batteries.Solid electrolytes,including inorganic solid electrolytes and polymer electrolytes,are regarded as effective alternatives to organic liquid electrolytes for the construction of lithium metal batteries with high energy density and safety.Among them,solid polymer electrolytes offer excellent flexibility,processability,and interfacial compatibility over inorganic solid electrolytes,and they are extraordinarily promising for lithium metal batteries with high energy density and safety.Ideal solid polymer electrolytes should have following features:(1)High ionic conductivity(>10^(–4) S cm^(–1))at room temperature;(2)high lithium ion transference number(~1)to reduce the concentration polarization and improve the rate performance of batteries;(3)intimate contact at the electrode/electrolyte interfaces;(4)wide electrochemical window(>4.5 V vs.Li/Li+)to match high-voltage cathodes and improve the energy density of batteries;(5)good mechanical stability to resist processing,buffer electrode volume change and inhibit dendrite growth;(6)good thermal stability to withstand environmental changes.Generally,the ionic conductivity of pure solid polymer electrolytes at room temperature is low(~10^(–6) S cm^(–1)).Researchers have tried to improve the ionic conductivities by adjusting the lithium salt concentration,such as developing“polymer-in-salt”solid electrolytes.However,increasing the concentration of lithium salt leads to the deterioration of the mechanical strength.Strategies such as developing novel lithium salts,modifying polymer matrix,and incorporating inorganic fillers into solid polymer electrolytes are proposed to promote ionic conductivities of solid polymer electrolytes.In particular,composite polymer electrolytes,fabricated by dispersing a certain amount of inorganic fillers into solid polymer electrolytes,have improved ionic conductivities without sacrificing their mechanical performances.Poor interfacial property between electrodes and electrolytes is also a critical issue for solid polymer electrolytes.On one hand,poor and uneven solid/solid contacts at the electrode/electrolyte interfaces lead to high resistance and sluggish ionic transport kinetics.Furthermore,the volume change of the positive and negative electrodes in the charge/discharge process deteriorates the interfacial contacts,blocks the ion and electron transport through the interfaces,and greatly reduces the electrochemical reaction kinetics.On the other hand,the electrochemical windows of solid polymer electrolytes are usually narrow(<4.5 V).During cycling,redox reactions are prone to occur at the electrode/electrolyte interfaces,causing battery failure.Solid polymer electrolytes have also poor thermal and mechanical stabilities.Therefore,design and synthesis of polymer-based solid electrolytes with excellent comprehensive performances and construction of fast and stable ion transport channels at the electrolyte/electrode interfaces are of great significance for the successful development of solid-state lithium metal batteries.This paper presents a brief review of the research progress in solid polymer electrolytes from two aspects:Improving the ionic conductivities of solid polymer electrolytes and enhancing the interfacial performance at electrolyte/electrode interfaces.First,targeted optimization strategies on ionic conductivities of solid polymer electrolytes,including constructing continuously aligned ionic transport paths and shortening the ionic transport distance,are summarized.Second,interface optimization strategies,including constructing wetting interfaces and synthesizing asymmetric electrolytes,are presented to reduce the interface resistance and improve the interfacial contact.Finally,perspectives on the development of solid polymer electrolytes and high-performance solid-state lithium metal batteries are discussed,and key research directions and advanced test methods are proposed.This review may provide a comprehensive understanding and further guidance for not only the material design of solid polymer electrolytes,but also the structural design of lithium metal batteries with favorable electrochemical and interfacial performances.
作者
周晓燕
付佳龙
李卓
郁睿
刘松涛
李志勇
魏璐
郭新
Xiaoyan Zhou;Jialong Fu;Zhuo Li;Rui Yu;Songtao Liu;Zhiyong Li;Lu Wei;Xin Guo(State Key Laboratory of Material Processing and Die&Mould Technology,School of Materials Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2022年第9期842-859,共18页
Chinese Science Bulletin
基金
国家自然科学基金委员会国际(地区)合作与交流项目(51961145302)
中国博士后科学基金(2020M682403)
湖北省自然科学基金(2019CFB110)资助。
关键词
聚合物基固体电解质
锂离子电导率
电解质/电极界面
固态电池
polymer-based solid electrolyte
lithium-ion conductivity
electrolyte/electrode interface
solid-state battery
