PVDF-Based Micro Inorganic Fillers-Containing Polymer Electrolyte Membranes

Polymer electrolyte membranes based on poly (vinylidene fluoride-co-hexafluoropropylene) (PVDFHFP) with and without different types of micro inorganic fillers were prepared by phase-inversion process.Morphologies, porosities and electrochemical properties of the as-prepared membranes were investigated by means of scanning electronic microscopy (SEM), PC (propylene carbonate) uptake and alternating current(AC) impedance technique. Compared with other membranes, the membrane with micro SiO2 filler shows a dense morphology so that its PC uptake is the highest, namely, 339%. The membrane filled with micro TiO2exhibits good electrochemical performances: the ion conductivity is as high as 1.1 × 10-3 S/cm at 18 ℃,which can meet the demand of lithium ion batteries. Moreover, its initial charge-discharge efficiency exceeds89 %. The composite membranes with micro SiO2, TiO2 and A12O3 are more suitable for the utilization in lithium ion batteries due to better cycleability, whereas the battery assembled with the blank membrane containing no inorganic fillers encounters a short circuit after the 5th cycle.