Patent ID: 7211352

Claim:
A composite polymer electrolyte for a lithium secondary battery, which comprises: a first polymer matrix made of a first porous polymer with a first pore size, wherein the first porous polymer is polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyichioride, cellulose, nylon, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer or blend thereof, and wherein the first polymer matrix does not comprise a polymer type single ion conductor; a second polymer matrix coated on the first polymer matrix and made of a single ion conductor consisting essentially of polymer, an inorganic material, and a second porous polymer with a second pore size smaller than the first pore size, wherein the second porous polymer is a vinylidene fluoride based polymer, an acrylate based polymer, a copolymer or a blend thereof, and wherein the second polymer matrix has an ionic conductivity equal to or higher than the ionic conductivity of the first polymer matrix; and an electrolyte solution impregnated into the first polymer matrix and the second polymer matrix.