LITHIUM ION BATTERY

A lithium ion battery () of the invention includes a battery main body () which includes one or more power generation elements configured by laminating a positive electrode layer () including a positive electrode active material layer () and a positive electrode current collector (), an electrolyte layer including a separator () and an electrolytic solution, and a negative electrode layer () including a negative electrode active material layer () and a negative electrode current collector (), in this order, an outer package () in which the battery main body () is sealed, a positive electrode terminal () which is electrically connected to the positive electrode current collector () and at least a part of which is exposed to the outside of the outer package (), and a negative electrode terminal () which is electrically connected to the negative electrode current collector () and a part of which is exposed to an outside of the outer package (). In the lithium ion battery () of the embodiment, an end portion () on an outer side of the negative electrode current collector () and an end portion () on an inner side of the negative electrode terminal () are joined with each other, and the lithium ion battery includes a first non-joint portion () which is not joined with the negative electrode terminal (), on a most distal end portion (A) on the outer side of the negative electrode current collector (). In addition, in the lithium ion battery () of the embodiment, an end portion () on the outer side of the positive electrode current collector () and an end portion () on the inner side of the positive electrode terminal () are joined with each other, and the lithium ion battery includes a third non-joint portion () which is not joined with the positive electrode terminal (), on a most distal end portion (A) on the outer side of the positive electrode current collector ().