Anti-thermal shrinkage nanoparticles/polymer and ionic liquid based gel polymer electrolyte for lithium ion battery

A new gel polymer electrolyte (GPE) system for lithium ion battery was developed by using anti-thermal shrinkagable nanoparticles/polymer incorporating with ionic liquid. Polyethylene-supported SiO2/poly(methyl methacrylate–acrylonitrile–vinyl acetate) (P(MMA–AN–VAc)) and Al2O3/P(MMA–AN–VAc) separators were prepared and the corresponding GPEs, SiO2/P(MMA–AN–VAc) + LiTFSI + PYR14TFSI/VC and Al2O3/P(MMA–AN–VAc) + LiTFSI + PYR14TFSI/VC, were obtained by immersing the separators in an ionic liquid electrolyte of 0.5 mol kg−1 LiTFSI in PYR14TFSI/VC. The structure and performance of the separators and corresponding GPEs were characterized by thermogravimetric analysis (TGA), air permeability, scanning electron spectroscopy (SEM), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV) and charge–discharge test. It is found that the nanoparticles/polymer separators have good dimensional stability and the corresponding GPEs have good ionic conductivity and excellent compatibility with the electrodes of lithium ion battery. SiO2/P(MMA–AN–VAc) and Al2O3/P(MMA–AN–VAc) separators are stable up to 310 °C and have a Gurley value of 8 s. SiO2/P(MMA–AN–VAc) based GPE has an ionic conductivity of 1.2 × 10−3 S cm−1 at room temperature and an oxidative decomposition potential of 5.3 V (vs. Li/Li+). The interfacial resistance between anode lithium and GPE is changed from 47 Ω cm2 on the first day to 118 Ω cm2 after the 25 days. The battery Li/GPE/LiFePO4 shows good rate and cyclic performance.