Microporous polymer electrolyte based on PVDF-PEO

Abstract

[2,3] . At present, polymer electrolytes mainly include three kinds: dry polymer electrolytes, gel polymer electrolytes and microporous polymer electrolytes. From the aspect of industrialization, microporous polymer electrolytes have significant value of study and perspective of application. USA company Bellcore invented the microporous membrane of P(VDF-HFP) copolymer. After absorbing liquid electrolyte, it had favorable ionic conductivity and mechanical property, but in producing process the solvent such as acetone was needed to extract nonsolvent (DBP) which was used to make pores, which was not advantageous to producing on a large scale. Now the studies of microporous polymer electrolytes are mostly focused on the polymer system containing fluorin, such as PVDF, and P(VDF-HFP) [3—11] . In this communication, we first prepared PVDF-PEO blended microporous polymer electrolyte by phase inversion technique. The PVDF and PEO were dissolved in a volatile solvent and nonsolvent with high boiling point, then, the solution was placed in a certain circumstance and at a certain temperature. Finally the volatile solvent evaporated and microporous structure was obtained after the phase separation between polymer system and nonsolvent. The result shows that the microporous structure of polymer system, such as pore size, porosity and connectivity, is obviously improved by the addition of PEO. Accordingly the ionic conductivity of room temperature was greatly enhanced. In addition, the preparation method is simple and no need to extract DBP. PVDF-PEO microporous membranes were prepared by phase inversion technique [10]