Patent ID: 6924067

Claim:
A polymer lithium battery, comprising: a positive electrode; a polymer electrolyte and a negative electrode wherein the polymer electrolyte comprises a copolymer and a composite lithium salt, wherein the copolymer is comprises: a substrate polymer and a branched polymer having a main chain whose repeating unit is composed of an oligoethylene oxide chain and a connector molecule bonded to the oligoethylene oxide chain the connector molecule being bonded to an end group of the main oligoethylene oxide chain by an ether bond, bonded to an end group of a branched oligoethylene oxide chain by an ether bond, and bonded to an end group of the main oligoethylene oxide chain or the branched oligoethylene oxide side chain of a neighboring repeating unit by an ester bond to form the repeating unit of the oligoethylene oxide chain wherein said lithium salt is at least one member selected from the group consisting of Li(CF 3 SO 2 ) 2 N—LiPF 6 composite salts and Li(C 2 F 5 SO 2 ) 2 N—LiPF 6 composite salts.