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

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 (trifluoromethylsulfonynimide(LiTFSI) to form double-lithium-salt comb polymer electrolyte membrane. Nuclear magnetic resonance CH 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 t(Li)(+) is 0.32 at 70 degrees C, the ion conductivity (sigma) is 1.5x10(-4) S/cm, the electrochemical stability window is 0-4.9 V (vs. Li/Li+). The assembled LiIPIAMA-g-MPEGILi battery and the constant current charge-discharge voltage polarization test at 70 degrees C show that the electrolyte has good compatibility with the metal lithium negative electrode and can effectively inhibit the growth of lithium dendrites. The assembled LiFePO4 vertical bar PIAMA-g-MPEG vertical bar Li battery was subjected to 70 degrees C long cycle and rate performance test, and the electrolyte showed excellent high temperature performance.