Microporous PVdF-HFP based gel polymer electrolytes reinforced by PEGDMA network

We have successfully developed a new process to prepare microporous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer based gel electrolyte with polyethylene glycol dimethacrylate (PEGDMA) network without the need for extraction process. Microporous structure in polymer matrix is achieved by solvent controlled evaporation from solution containing a copolymer in a mixture of volatile solvent and nonsolvent. The high tensile modulus and better flexibility of the membrane are improved by combination of PEGDMA network and PVdF-HFP copolymer chain which is plasticized by polyethylene glycol (PEG). The blend polymer membrane with composition of PVdF-HFP/PEG/PEGDMA (5/3/2) shows electrolyte uptake of 98.2% and ionic conductivity exceeding 1.0 X 10(-3) S cm(-1) at room temperature in the presence of 1 M LiPF6/EC-DEC. AC impedance studies also confirm that this blend gel electrolyte can form stable passivation layer on the lithium metal surface. In addition, the use of the blend gel electrolyte assures electrochemical stability up to 5.0 V vs. Li/Li+. (C) 2004 Published by Elsevier B.V.