Lithium-ion secondary battery and its manufacturing method

Disclosed is a method for producing a lithium ion secondary battery comprising a step for obtaining a positive electrode by having a positive electrode mix layer supported by a positive electrode core member, a step for obtaining a negative electrode by having a negative electrode mix layer supported by a negative electrode core member, a step for forming an electron-insulating porous film which is bonded to the surface of at least one of the positive electrode and the negative electrode, a step for forming an electrode plate group by interposing a separator between the positive electrode and the negative electrode, and a step for impregnating the electrode plate group with a nonaqueous electrolyte solution. In this method, the step for forming the porous film comprises a sub-step for preparing a porous film paste containing filler particles and a film binder containing a thermally crosslinkable resin, and a sub-step for coating the surface of at least one of the positive electrode and the negative electrode with the porous film paste and heating the thus-obtained coating film.