Electrochemical Behaviour of the Composite Polymer Electrolyte P(VDF-HFP)-PMMA/CaCO<sub>3</sub>(SiO<sub>2</sub>)

Abstract

Electrochemical behavior of the composite polymer electrolyte (CPE) prepared from polyvinylidene fluoride-co-hexafluoropropylene (P (VDF-HFP)), poly (methyl methacrylate) (PMMA), and nanosized CaCO3 (SiO2) particles was investigated by confocal laser scanning microscopy, X-ray diffraction (XRD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Results show that CPEs have many micropores, and that the addition of PMMA can increase the absorption potential of the liquid electrolyte and therefore improve ionic conductivity. The best performance of CPE was found at a P (VDF-HFP) /PMMA mass ratio of 1:1. The composite polymer electrolyte that was produced by adding nanosized CaCO3 and SiO2 to a P (VDF-HFP)-PMMA base keeps the amorphous structure of the original polymer base. The ionic conductivity of CPE can reach 3.42 mS•cm^(-1) and the electrochemical window can be up to 4.8 V at room temperature. A test on Li/CPE/GMS cells showed that the composite polymer electrolyte was compatible with graphite anodes. The battery made from Li/CPE (CaCO3) /LiCoO2 was shown to have a superior rate discharging performance to Li/CPE (SiO2) /LiCoO2.