Mechanical properties and ionic conductivity of gel polymer electrolyte based on poly(vinylidene-fluoride-co-hexafluoropropylene)

Gel polymer electrolytes were prepared from poly(vinylidene-fluoride-co-hex afluoropropylene) (PVH), which had higher mechanical properties and a highe r dielectric constant (epsilon = 8-13) than other polymeric matrixes. The m echanical properties and ionic conductivities were investigated as a functi on of the blend ratio of the electrolyte solution and polymer matrix. Ethyl ene carbonate/gamma -butyrolactone and lithium triflate were used as the so lvent and salt, respectively. The mechanical properties such as the tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09 X 10(-3) S/cm at 25 degreesC for 40 wt % PVH against the electrolyte solution. The tensile str ength, tensile modulus, and compression modulus were increased with increas ing PVH content and they all abruptly changed between 70 and 80 wt % PVH. T he dynamic shear moduli showed behavior typical of a gel and varied with th e shear strain amplitude or applied frequencies. (C) 2001 John Wiley & Sons , Inc.