To provide a battery which is stable with good storing property of electrolyte, highly ion conductive, and superior in charging and discharging cycle durability by using a polymer electrolyte, which has a copolymer including a polymer unit based on vinylidene fluoride and a polymer unit based on (polyfluoroalkyl)ethylene as matrix and contains a solution of lithium salt.
The weight ratio of a polymer unit, based on vinylidene fluoride to the polymer unit based on (polyfluoroalkyl)ethylene in a copolymer, is preferably 10/90-97/3. Here, by the (polyfluoroalkyl)ethylene is meant an alkyl ehtylene in which two or more hydrogen atoms in the alkyl group are substituted by fluorine atoms. As the solvent of the lithium salt solution, carbonate is preferably used, including propylene carbonate. Moreover the content of the lithium salt solution in the polymer electrolyte is suitably set to 30-90 wt.%.
TAMURA MASAYUKI
HIRATSUKA KAZUYA
KAZUHARA MANABU
IKEDA KATSUHARU
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