一种双锂盐梳状聚合物电解质的制备及电化学性能

Synthesis of a Dual-lithium-salt Comb Polymer Electrolyte and Its Electrochemical Performance

将聚乙二醇单甲醚(MPEG)接枝在聚(异丁烯-alt-马来酸酐)(PIAMA)上合成梳状锂单离子导体PIAMA-g-MPEG,并与双(三氟甲基磺酰)亚胺锂(LiTFSI)复合制成双锂盐梳状聚合物电解质薄膜.用核磁共振波谱(^(1)H NMR)、热重分析(TG)、扫描电子显微镜(SEM)、电化学阻抗(EIS)和电池充放电测试等方法对聚合物基体和电解质的物化性质和电化学性能进行了研究.结果表明,设计的双锂盐梳状聚合物电解质能够有效解离并传输锂离子,70℃下离子迁移数(tLi^(+))为0.32,离子电导率(σ)为1.5×10^(−4) S/cm,电化学稳定窗口为0~4.9 V(vs.Li/Li^(+)).组装Li|PIAMA-g-MPEG|Li电池并进行70℃恒电流充放电电压极化测试,结果表明,电解质与金属锂负极兼容性较好,能够有效抑制锂枝晶的生长.组装LiFePO_(4)|PIAMA-g-MPEG|Li电池进行70℃长循环及倍率性能测试,电解质表现出了优异的高温性能.

Polyethylene glycol monomethyl ether(MPEG)was grafted on poly(isobutylene-alt-maleic anhydride)(PIAMA)to synthesize comb-like lithium mono-ion conductor PIAMA-g-MPEG,which was mixed with lithium bis(trifluoromethylsulfonyl)imide(LiTFSI)to form double-lithium-salt comb polymer electrolyte membrane.Nuclear magnetic resonance(^(1)H NMR)spectroscopy,thermogravimetric analysis(TG),scanning electron microscopy(SEM),electrochemical impedance(EIS)and battery charge-discharge test were used to study the physical,chemical and electrochemical properties of polymer matrix and electrolyte.The results show that the designed double lithium salt comb polymer electrolyte can effectively dissociate and transport lithium ions,the ion mobility tLi^(+)is 0.32 at 70℃,the ion conductivity(σ)is 1.5×10^(−4) S/cm,the electrochemical stability window is 0-4.9 V(vs.Li/Li^(+)).The assembled Li|PIAMA-g-MPEG|Li battery and the constant current charge-discharge voltage polarization test at 70℃show that the electrolyte has good compatibility with the metal lithium negative electrode and can effectively inhibit the growth of lithium dendrites.The assembled LiFePO_(4)|PIAMA-g-MPEG|Li battery was subjected to 70℃long cycle and rate performance test,and the electrolyte showed excellent high temperature performance.