Patent ID: 7252689

Claim:
A method for fabricating a lithium ion secondary battery comprising the steps of: (a) preparing an electrode plate A comprising an active material capable of absorbing and desorbing lithium ions and a binder mainly composed of a polymer material “a”, and an electrode plate B comprising an active material capable of absorbing and desorbing lithium ions and a binder mainly composed of a polymer material “b”; (b) preparing a separator by forming on said electrode plate B a porous polymer layer mainly composed of said polymer material “a” or a copolymer of said polymer material “a”; (c) forming a flat electrode plate assembly by laminating in mutual opposition said electrode plate A and said electrode plate B via said separator to be a laminate and winding up said laminate in flat form; (d) soaking said flat electrode plate assembly in a non-aqueous electrolyte to obtain a soaked state by accommodating said flat electrode plate assembly and said non-aqueous electrolyte in a battery case; and (e) integrating said flat electrode plate assembly in the adhering state by heating said flat electrode plate assembly still in the soaked state at a heating temperature of 80° C. to 100° C., followed by cooling, while applying pressure in a direction of thickness of said flat electrode plate assembly.