Polyethylene-supported poly(methyl methacrylate-co-butyl acrylate)-based novel gel polymer electrolyte for lithium ion battery

A new copolymer, poly(methyl methacrylate- co -butyl acrylate) (P(MMA- co- BA)), was synthesized by emulsion polymerization with different mass ratio of methyl methacrylate (MMA) and butyl acrylate (BA). The membranes were prepared by phase inversion and corresponding gel polymer electrolytes (GPEs) were obtained by immersing the membrane into a liquid electrolyte. In this design, the hard monomer MMA provided the copolymer with good electrolyte uptake, while the soft monomer BA provided the GPE with strong adhesion between the anode and cathode of lithium ion battery. The properties of the resulting product were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectra, scanning electron spectroscopy, linear sweep voltammetry, thermogravimetric analysis, cyclic voltammetry, electrochemical impedance spectroscopy and charge/discharge test. The results show that the obtained GPE based on P(MMA- co -BA) with the mass ratios of MMA and BA = 6:1 exhibits good conductivity (as high as 1.2 × 10 −3 S cm −1 ) at room temperature and high electrochemical stability (up to 4.9 V vs. Li/Li + ). With the application of the polyethylene (PE)-supported GPE in Li/Li(Li 0.13 Ni 0.30 Mn 0.57 )O 2 battery, the battery presents good cyclic stability (maintaining 95.4 % of its initial discharge capacity after 50 cycles) at room temperature.