Physical and electrochemical properties of PVdF-HFP/SiO2-based polymer electrolytes prepared using dimethyl acetamide solvent and water non-solvent

Abstract

Poly[(vinylidene fluoride)-co-hexafluoropropylene]/SiO2 polymer electrolytes were prepared by a phase inversion technique using DMAc solvent and water non-solvent. Cast film electrolytes filled with the same amount of SiO2 using DMAc were also made to compare physical and electrochemical properties. DMAc had a higher solubility to PVdF-based polymers than NMP, and DMAc produced highly porous structures with bigger cavities and influenced the reduction of crystallinity. Due to the highly porous nature of phase inversion membranes, the uptake of electrolyte solution reached more than 400% and room-temperature ionic conductivity was more than 10-3 S · cm-1. All of the liquid absorbed, however, did not necessarily contribute to increases in ionic conductivity. This was due to the different conduction modes of lithium cations in a complicated porous structure. Comprehensively optimizing all the properties measured, the phase inversion membrane electrolytes with 10-30 wt.-% SiO2 were the best candidates for use as the polymer electrolyte of lithium rechargeable batteries. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.