Gel polymer electrolytes based on active PVDF separator for lithium ion battery. I: Preparation and property of PVDF/poly(dimethylsiloxane) blending membrane

► This is an easy method to prepare gel polymer electrolyte for lithium battery based on the modified active separator. ► To our best knowledge, few studies on the blend of polysiloxane with the PVDF polymer materials have been reported. Polysiloxane was used as an effective addictive in the blending separator due to its outstanding properties. ► The electrochemical properties of active separators were accord with their characters well. ► The structure of the active separator is stable and effective. This work explores the “active” separator that can be activated into gel or polymer electrolyte membrane. The active nature and easier processing property make the separator more applicable in assembling batteries. To improve the activeness of PVDF based separators, the poly(dimethylsiloxane) (PDMS) was blended into porous PVDF membrane matrix via a typical phase inversion route. By measuring the composition, morphology, ion conductivity, and so on, the work studies the influence of PDMS on structure and properties of blending separators. Compared with pure PVDF membrane having comparable porous structure, the adoption of PDMS not only decreases the crystallinity and increases the breaking elongation efficiently, but also enhances the stability of entrapped liquid electrolyte and ion conductivity. For separators with PVDF/PDMS mass ratio in 7/3, the liquid electrolyte uptake reached 250 wt% and ion conductivity of formed gel electrolyte membrane was 1.17 × 10 −3 S cm −1, which was acceptable for high voltage lithium ion batteries.