| 摘要 |
PROBLEM TO BE SOLVED: To increase ion conductivity when an electrolytic solution is impregnated and to impregnate the electrolytic solution at a low temperature in a short time by specifying the surface roughness and porosity of a foam body thin film containing a bridging-treated polyvinylidene fluoride polymer. SOLUTION: This battery separator is made of a bridging-treated foam body film, can be used for a battery constituting element as a separator, and shows superior battery performance. The separator contains a vinylidene fluoride polymer having a bridge structure. The porosity of the foam body structure by the bubble volume is preferably set to 50-98%. The surface roughness Ra on one or both faces of a foam body thin film must be 1.2μm or above and 1/4 of the thickness or below in accordance with JIS B 0601. An electrolytic solution can be impregnated at a temperature of about 70 deg.C in a short time, and high ion conductivity and superior dimensional stability and heat resistance can be obtained, when the electrolytic solution is impregnated.
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