PVDF porous matrix with controlled microstructure prepared by TIPS process as polymer electrolyte for lithium ion battery

Poly(vinylidene fluoride) (PVDF) microporous matrix of polymer electrolyte for lithium ion battery was prepared via the thermally induced phase separation (TIPS) process using diluent mixture of dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). Since this method has only one parameter, namely the DBP/DEHP ratio in diluent mixture, the membrane microstructure is easily and conveniently controlled. With the assistance of a pseudo-binary temperature-DBP ratio phase diagram of the PVDF-diluent mixture system, the membrane formation mechanism for different microstructures of membranes was proposed. In addition to studying the different microstructures available in TIPS process, the relationship between performance of membrane, electrochemical property of polymer electrolyte and final microstructure has been investigated in this paper.