A porous poly(vinylidene fluoride) gel electrolyte for lithium ion batteries prepared by using salicylic acid as a foaming agent

A porous gel polymer electrolyte based on poly(vinylidene fluoride) (PVDF) was for the first time prepared via a foaming technology using salicylic acid as a foaming agent. The pores are evenly distributed with an average diameter of about 400 nm. The results from TG/DTA, XRD and Fr-IR show that there are no vesicant residues after the PVDF film was heat-treated at 200 degrees C to get the porous structure. When the film is gelled with liquid electrolyte, the ion conductivity can be up to 4.8 x 10(-3) S cm(-1) at room temperature and the activation energy for ionic transfer is 10.2 kJ mol(-1). LiCoO2 cathode also presents good cycling performance. These primary results show great promise for this simple method to prepare porous gel polymer electrolytes for practical application in lithium ion batteries. (C) 2008 Elsevier B.V. All rights reserved.