Lithium ion secondary battery

A 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 4 parts by weight per 100 parts by weight of said filler, and
• said resin binder comprises a plurality of resin binders including core-shell type rubber particles and other resin binder,
• said rubber particles have an adhesive surface portion including at least an acrylonitrile unit, an acrylate unit, or a methacrylate unit,
• said other resin binder comprises at least one selected from the group consisting of fluorocarbon resins, cellulose resins, and polyvinyl pyrrolidone, and
• the ratio of said core-shell type rubber particles to the total amount of resin binders is 20 to 80 wt. %.