Method for producing a power storage device

A method for producing a power storage device,

• the power storage device comprising:
• an electrode body having a pair of electrode body flat surfaces and including a plurality of electrode sheets laminated in a thickness direction perpendicular to an extending direction of the flat surfaces;
• an electrolytic solution;
• a case that has a pair of case side walls each facing one of the electrode flat surfaces and accommodates the electrode body and the electrolytic solution,
• wherein the method comprises:
• (a) compressively deforming including pressing the pair of case side walls of the case against the electrode body after the power storage device is subjected to initial charging and aging but before permanent sealing, to:
• compress the electrode body interposed between the pair of case side walls in the thickness direction;
• and
• plastically deform at least one of the pair of case side walls to be recessed toward the electrode body so that the pair of case side walls continue to press the electrode body in the thickness direction even after releasing the pressing;
• after the compressively deforming,
• (b) hermetically permanently sealing the case of the power storage device in which inside of the case is in communication with outside;
• and
• (c) releasing the pressing on the power storage device applied in the compressively deforming.