Patent ID: 7754377

Claim:
A manufacturing method of the lithium ion secondary battery comprising: a positive electrode capable of absorbing and desorbing lithium ion; a negative electrode capable of absorbing and desorbing lithium ion; a porous film interposed between said positive electrode and said negative electrode; and a non-aqueous electrolyte; wherein said porous film is adhered to a surface of at least one of said positive electrode and said negative electrode, said porous film comprises a filler and a resin binder, a content of said resin binder in said porous film is 1.5 to 8 parts by weight per 100 parts by weight of said filler, and an amount of said resin binder is smaller in a first surface side where said porous film is in contact with said surface of said electrode, and larger in a second surface side opposite to said first surface side, comprising the steps of: (a) preparing a paste including 100 parts by weight of a filler, 1.5 to 8 parts by weight of a resin binder including at least an acrylonitrile unit, an acrylate unit, or a methacrylate unit, and a dispersion medium of said filler, (b) applying said paste to a surface of at least one of a positive electrode and a negative electrode, and (c) drying the paste applied on the surface of said electrode at a temperature of not less than 100° C. to not more than 180° C.