Wound electrode body lithium ion battery having active electrode material layers of different widths

A lithium ion battery comprising:

• a wound electrode body that is obtained by disposing an elongated positive electrode and an elongated negative electrode to face each other in an insulated state so as to obtain a laminate and winding the laminate in a longitudinal direction by a predetermined number of turns, in which the elongated positive electrode includes an elongated positive electrode current collector and a positive electrode active material layer attached to the positive electrode current collector, and the elongated negative electrode includes an elongated negative electrode current collector and a negative electrode active material layer attached to the negative electrode current collector;
• a nonaqueous electrolytic solution that contains at least a supporting electrolyte and a nonaqueous solvent;
• and
• a battery case that accommodates the wound electrode body and the nonaqueous electrolytic solution, wherein
• the negative electrode active material layer includes a film containing a component derived from an oxalato complex compound and is formed to be wider than the positive electrode active material layer in a width direction perpendicular to the longitudinal direction,
• the negative electrode active material layer includes a facing portion which faces the positive electrode active material layer and non-facing portions which do not face the positive electrode active material layer,
• in measurement lines of the facing portion, a highest resistance value is present in a length region of less than 15% from a center of a facing center region in the width direction,
• the facing center region is a region of the facing portion excluding regions adjacent to the non-facing portions,
• the measurement lines are plural straight lines ranging from one end to another end in the width direction, and
• the resistance value is measured at each of the measurement lines.