Method for producing battery and battery

A method for producing a battery including:

• an electrode body including a positive electrode sheet having an aluminum foil, the positive electrode sheet including a foil layered part formed of a foil exposed portions exposing the aluminum foil, the foil exposed portions being overlapped in a thickness direction;
• and
• a positive terminal member made of aluminum and resistance-welded to the foil layered part,
• the foil layered part and the positive terminal member being joined to each other through a plurality of nuggets distributed in a scattered-point pattern in an expanding direction of the aluminum foil,
• wherein the method includes:
• a forming step of forming, in the foil layered part, a foil welded part made of an aluminum foil overlapped and welded to each other in the thickness direction by ultrasonic welding, the foil welded part being formed with a first high-position part located at a high position on one side in the thickness direction and a plurality of low-position parts positioned at a lower position than the first high-position part, the low-position parts being distributed in a scattered-point pattern within the first high-position part, in at least part of a to-be-joined surface on the one side in the thickness direction of surfaces of the foil welded part;
• and
• a resistance-welding step of placing the first high-position part into contact with the positive terminal member, applying electric current to the terminal member to generate the nugget in the first low-position part, and resistance-welding the foil welded part of the electrode body and the terminal member through the nugget.