Preparation and performance study on P(St-MMA)-SiO2 doped P(VDF-HFP) based composite polymer electrolyte

The organic-inorganic hybrid material poly(styrene-methyl methacrylate)-silica (P(St-MMA)-SiO2) was successfully prepared by in situ polymerization confirmed by Fourier transform infrared spectroscopy and was employed to fabricate poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) based composite polymer electrolyte (CPE) membrane. Desirable CPEs can be obtained by immersing the CPE membranes into 1.0mol L-1 LiPF6-EC/DMC/EMC (LiPF6 ethylene carbonate + dimethyl carbonate + ethylmethyl carbonate) liquid electrolyte for about 0.5 h for activation. The corresponding physicochemical properties were characterized by SEM, XRD, electrochemical impedance spectroscopy and charge-discharge cycle testing measurements. The results indicate that the as-prepared CPEs have excellent properties when the mass ratio of the hybrid P(St-MMA)-SiO2 particles to polymer matrix P(VDF-HFP) reaches 1: 10, at which point the SEM analyses show that the as-prepared P(St-MMA)-SiO2 particles are uniformly dispersed in the membrane and the CPE membrane presents a homogeneous surface with abundant interconnected micropores. The XRD results show that there may exist interaction forces between the P(St-MMA)-SiO2 particles and the polymer matrix, which can obviously decrease the crystallinity of the composite membrane. Moreover, the ionic conductivity at room temperature and the electrochemical working window of the CPE membrane can reach 3.146 mS cm(-1) and 4.7 V, respectively. The assembled LiCoO2/CPE/Li coin cell with the CPE presents excellent charge-discharge and C-rate performance, which indicates that P(St-MMA)-SiO2 hybrid material is a promising additive for the P(VDF-HFP) based CPE of the lithium ion battery. (C) 2016 Society of Chemical Industry