Interfacial compatibility of gel polymer electrolyte and electrode on performance of Li-ion battery

Abstract

Interfacial compatibility of composite polymer electrolyte and electrode is the key factor to affect the performance of polymer Li-ion batteries. In this work, liquid electrolyte, pristine PVDF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) gel polymer electrolyte (GPE) and nano-TiO2-poly(methyl methacrylate) (PMMA) hybrid doped PVDF-HFP composite polymer electrolyte (CPE) are used to investigate the interfacial compatibility between electrolyte and electrode on performance of LiCoO2/Li cells. The electrochemical performances of cells are studied by charge/discharge tests and electrochemical impedance. The interfacial compatibility coefficient (λ) that related to the interface of electrolyte and electrode is evaluated in terms of the fitting (i=e, sf, b and ct) with equivalent circuit and diffusion resistance (Rdiff). The results confirm that the C-rare performance of cells with GPE is more significantly associated with the interfacial compatibility than the ionic conductivity of GPE.