| abstract |
An optionally oriented copolyester film comprising a copolyester which comprises repeating units derived from an aliphatic diol, an aromatic dicarboxylic acid and a poly(alkylene oxide), wherein the copolyester film further comprises lithium ions, and wherein the film has a thickness of no more than about 25μm. The copolyester film is suitable for use a separator in a lithium-ion rechargeable battery. |