BINDER FOR ELECTRICITY STORAGE DEVICE

摘要

To provide a binder for a storage battery device, whereby good adhesion is obtainable, and it is possible to realize good charge and discharge characteristics in a secondary battery by well suppressing swelling of an electrode by an electrolytic solution. A binder for a storage battery device, which is made of a fluorinated copolymer comprising repeating units (a) derived from tetrafluoroethylene and repeating units (b) derived from propylene, wherein the molar ratio (a)/(b) is from 60/40 to 75/25, and the total of the repeating units (a) and (b) is at least 90 mol% in all repeating units.