Preparation of microporous PVDF based polymer electrolytes

Microporous PVDF-HFP (Kynar 2801) and PVDF-HFP/PS (where PS is polystyrene) films were prepared without solvent extraction using a solvent/nonsolvent method and the volatile plasticizers propyl carbonate (PC) or diethylcarbonate (DEC). Films with and without silicon dioxide (SiO2) were prepared. The conductivity of the films increased with increasing pore volume, measured by a nonsolvent uptake method. The films had improved conductivity compared with films made using the Bellcore process. Conductivities of 4 mS cm−1 were obtained using the liquid electrolyte LiPF6 (1 M) in EC/DMC/DEC (4:5:1 by weight).