Enhanced thermal and electrochemical properties of poly(vinylidene fluoride-co-hexafluoropropylene)-based composite polymer electrolytes doped with CaTiO3 dielectric ceramics

Abstract

Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))-based composite polymer electrolytes (CPEs) doped with different amounts of CaTiO3 inorganic fillers are prepared by phase inversion. With adding the CaTiO3 fillers into the P(VDF-HFP) polymer matrix, the CPE membranes show more abundant and uniform micro-pore structure with lower crystallinity, better thermal stability and mechanical strength. The characterization results show that the ionic conductivity at room temperature and electrochemical working window of the CPE doped with 5 wt% CaTiO3 fillers (CPE-5) can be up to about 3.557 mS cm−1 and 5.1 V, respectively. The interfacial resistance of the Li/CPE-5/Li simulated cell can quickly stabilize at 750 Ω after 5 days storage, and the assembled LiCoO2/CPE-5/Li coin cell shows excellent rate and cycle performance. Moreover, the CPE-5 membrane can still well maintain the original micro-pore structure after 100 cycles at 1.0 C without visible cracks. Those results suggest that the as-fabricated CPE doped with 5 wt% CaTiO3 inorganic fillers may become a promising polymer electrolyte for the lithium ion battery