Producing method for lithium-ion secondary battery

A producing method for a lithium-ion secondary battery comprising a positive electrode plate provided with a positive active material layer on a surface of a positive current collecting foil formed of an aluminum foil, a negative electrode plate, non-aqueous electrolytic solution including LiPF6, and a battery case to house the positive electrode plate, the negative electrode plate, and the non-aqueous electrolytic solution, the producing method including:

• positive-electrode-plate producing of producing the positive electrode plate having the positive active material layer on the surface of the positive current collecting foil;
• electrode-body producing of producing an electrode body provided with the positive electrode plate and the negative electrode plate;
• housing the electrode body in the battery case;
• water-content adjusting of adjusting a water content of the positive active material layer to be within a range from 100 ppm or more to less than 500 ppm after the housing;
• injecting the non-aqueous electrolytic solution into the battery case housed with the electrode body to produce an injection-completed battery;
• and
• initial charging of initially charging the injection-completed battery, wherein
• the injecting is to inject the non-aqueous electrolytic solution into the battery case housed with the electrode body, in which the water content of the positive active material layer is within the range of from 100 ppm or more to less than 500 ppm.