| abstract |
A solid electrolytic secondary battery comprising a positive electrode, a negative electrode and a solid electrolyte interposed between the electrodes, wherein the solid electrolyte contains, as a matrix polymer, a block copolymer of vinylidene fluoride and hexafluoropropylene. The membrane of the block copolymer has a strong mechanical toughness and a high solvent retaining capability and, when used as a matrix polymer of the solid electrolyte, significantly improves an adhesion strength, load characteristics and low-temperature characteristics. A constitutional ratio of hexafluoropropylene in the block copolymer is preferably 3 to 7.5 wt.% with a molecular weight of not smaller than 550,000 and a copolymer having a weight-average molecular weight (Mw) of not smaller than 300,000 and smaller than 550,000 may be jointly used. |