Patent ID: 7816038

Claim:
A method for producing a lithium ion secondary battery, comprising the steps of: forming a positive electrode material mixture layer on a positive electrode substrate to obtain a positive electrode; forming a negative electrode material mixture layer on a negative electrode substrate to obtain a negative electrode; forming an electronically insulating porous film that is bonded to a surface of at least one of said positive electrode and said negative electrode; interposing a separator between said positive electrode and said negative electrode to form an electrode plate assembly, said separator being a microporous sheet composed of polyolefin resin; and impregnating said electrode plate assembly with a non aqueous electrolyte, wherein said step of forming a porous film comprises the steps of: preparing a porous film paste that contains a film binder comprising a thermo-cross-linkable resin and a particulate filler; applying said porous film paste onto a surface of at least one of said positive electrode and said negative electrode and heating the resultant applied film; and heating said applied film at a temperature of 150° C. or higher, said thermo-cross-linkable resin being a single-liquid-type resin with a masked cross-linkable site, and said masked cross-linkable site being activated at 100° C. or higher.