Preparation and properties of gel membrane containingporous PVDF-HFP matrix and cross-linked PEG for lithium ion conduction

Lithium ion conducting membranes are the key materials for lithium batteries. The lithium ion conducting gel polymer electrolyte membrane (Li-GPEM) based on porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix and cross-linked PEG network is prepared by a typical phase inversion process. By immersing the porous PVDF-HFP membrane in liquid electrolyte containing poly(ethylene glycol) diacrylate (PEGDA) and an initiator to absorb the liquid electrolyte at 25°C, and then thermally cross-linking at 60°C, the Li-GPEM is fabricated successfully. The measurements on its weight loss, mechanical and electrochemical properties reveal that the obtained Li-GPEM has better overall performance than the liquid and blend gel systems used as conductive media in lithium batteries. The ionic conductivity of the fabricated Li-GPEM can reach as high as 2.25 × 10^-3 S/cm at 25°C.