BINDER FOR ENERGY STORAGE DEVICE, ELECTRODE FOR ENERGY STORAGE DEVICE, ENERGY STORAGE DEVICE, POLYMER COMPOSITE, AND PRODUCTION METHOD OF BINDER FOR ENERGY STORAGE DEVICE

A binder for an energy storage device including a polymer composite formed by compositing a polyimide precursor and/or a polyimide with a cyclic molecule having multiple ether bonds. The polyimide precursor contains a reactant of a tetracarboxylic acid component and a diamine component. The polyimide is obtained by imidizing a part or all of the polyimide precursor.