锂内盐两性离子聚合物电解质的制备与电化学性能研究  

Preparation and Electrochemical Performance of Polyzwitterion Containing Intramolecular Salt as Solid Electrolytes for Lithium-ion Batteries

作　　者：刘书畅 吴海莹 张灵志[1,2] Shu-chang Liu;Hai-ying Wu;Ling-zhi Zhang(CAS Key Laboratory of Renewable Energy,Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640;University of Science and Technology of China,Hefei 230026)

机构地区：[1]中国科学院可再生能源重点实验室、广东省新能源和可再生能源研究开发与应用重点实验室、中国科学院广州能源研究所,广州510640 [2]中国科学技术大学,合肥230026

出　　处：《高分子学报》2024年第3期296-308,共13页Acta Polymerica Sinica

基　　金：中科院科技服务网络计划(STS)东莞专项(项目号20211600200331);东莞市重点领域研发项目(项目号20221200300112)资助.

摘　　要：与有机电解液相比,聚合物电解质可以有效提高电池的安全性和能量密度,但离子电导率低、电化学窗口较窄和对锂金属不稳定等问题限制了其实际应用.本文工作通过自由基共聚制备了一种复合锂内盐两性离子聚合物(P(AMPSLi-IL)).通过静电纺丝技术将不同质量比的P(AMPSLi-IL)和聚乙烯醇(PVA)制备为一系列的纳米纤维膜(PVA-P(AMPSLi-IL)),其热分解温度为280℃,其中PVA9-P(AMPSLi-IL)1的拉伸强度最大为13.8 MPa.将双氟磺酰亚胺锂(LiFSI)溶于碳酸乙烯酯(EC)中,配制1 mol·L^(-1)的溶液作为基础电解液.纤维膜在基础电解液中,以二缩三丙二醇二丙烯酸酯(TPGDA)作为交联剂原位凝胶化得到电解质膜.优化后的PVA9-P(AMPSLi-IL)_(1)基电解质室温离子电导率高达2.87×10^(-3) S·cm^(-1),锂离子迁移数高达0.85.而且该电解质的氧化电位为4.34 V(versus Li/Li^(+)),优于基础电解液的3.92 V(versus Li/Li^(+)).在锂锂对称电池中该电解质能保持超过1800 h的稳定循环,展示了对锂金属极佳的界面稳定性.将该电解质应用于磷酸铁锂半电池,0.5 C下其初始放电比容量为145.7 mAh·g^(-1),200圈后的容量保持率达79.0%.Polymer electrolytes are known to be more effective in enhancing the safety and energy density of lithium-ion batteries as compared to organic electrolytes.However,the practical application of polymer electrolytes is hindered due to their low ionic conductivity,narrow electrochemical window,and incompatibility with lithium metal anode.In this work,a polyzwitterion(P(AMPSLi-IL))containing intramolecular lithium salt of lithium bis(trifluoromethanesulphonyl)imide(LiTFSI)was designed and synthesized through a radical copolymerization of acryloyloxyethyltrimethyl ammonium bis(trifluoromethanesulphonyl)imide(AETATFSI)and lithium 2-acrylamido-2-methylpropanesulfonic acid(AMPSLi).A series of nanofiber membranes composed of poly(vinyl alcohol)(PVA)and P(AMPSLi-IL)were prepared by electrospinning technology.The nanofiber membrane with optimized ratio of PVA to P(AMPSLi-IL)shows a high tensile strength of 13.8 MPa and thermal decomposition temperature of 280℃.The nanofiber membranes were in situ gelated in a based electrolyte(1 mol/L LiFSI in EC)with tri-(propylene glycol)diacrylate(TPGDA)as a crosslinking agent,which was used as a polymeric solid electrolyte.The optimized electrolyte of PVA9-P(AMPSLi-IL)_(1) exhibited a high ionic conductivity of 2.87×10^(-3) S·cm^(-1) at room-temperature,high lithium transference number of 0.85 and oxidation potential of 4.34 V(versus Li/Li^(+)).The symmetric Li|Li cell with the PVA9-P(AMPSLi-IL)_(1) electrolyte shows an excellent cycle stability for over 1800 h,demonstrating a great compatibility between Li anode and the PVA9-P(AMPSLi-IL)_(1) electrolyte.The LFP|Li half cell with the PVA9-P(AMPSLi-IL)1 electrolyte delivers an initial discharge capacity of 145.7 mAh·g^(-1) at 0.5 C with a capacity retention of 79.0%after 200 cycles.

关 键 词：锂金属电池 聚合物电解质 两性离子聚合物 聚乙烯醇 

分 类 号：TQ317[化学工程—高聚物工业] TM912[电气工程—电力电子与电力传动]