| abstract |
To provide a binder for a storage battery device, whereby good adhesion in an electrode and flexibility are obtainable, and it is possible to realize good charge and discharge characteristics when used for a secondary battery. A binder for a storage battery device, which is made of a fluorinated copolymer comprising structural units (a) derived from tetrafluoroethylene and structural units (b) derived from propylene, wherein the molar ratio (a)/(b) is from 40/60 to 50/50, and the total of the structural units (a) and (b) is at least 90 mol% in all structural units. |