Preparation and performance of gel polymer electrolyte based on electrospun polymer membrane and ionic liquid for lithium ion battery

A gel polymer electrolyte (GPE) based on an electrospun polymer membrane of poly(acrylonitrile)/poly(methyl methacrylate) (PAN/PMMA) incorporating with a room-temperature ionic liquid N-methy-N-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) was prepared and its performance for lithium ion batteries was investigated. The SEM observation and porosity measurement indicate that the electrospun membrane has an interconnected uniform morphology with an average fiber diameter of 450 nm and a porosity of 86%. The results from electrochemical measurements show that the GPE has highly ionic conductivity, wide electrochemical window and good charge/discharge performance. The ionic conductivity of the GPE at room temperature is 3.6 × 10−3 S cm−1. The GPE is stable at the potential higher than 5 V (versus Li+/Li). The capacity of LiFePO4 in the cell Li/GPE/LiFePO4 is 139, 134, 120, and 101 mAh g−1 at the charge/discharge rate of 0.1, 0.2, 0.5 and 1 C, respectively, and remains unchanged after 10 cycles for each rate.