LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery in which the precipitation of lithium is suppressed.SOLUTION: A lithium ion secondary battery provided according to the present invention comprises: an electrode body; a nonaqueous electrolyte; and a battery case in which the electrode body and the nonaqueous electrolyte are enclosed. The electrode body is a wound electrode body arranged by winding a laminate of a sheet-like positive electrode, a sheet-like negative electrode, and a sheet-like separator disposed between the positive and negative electrodes. The positive electrode includes: a positive electrode collector; and a positive electrode active material layer disposed on a surface of the positive electrode collector. The negative electrode includes: a negative electrode current collector; and a negative electrode active material layer disposed on a surface of the negative electrode current collector. The wound electrode body has: flat portions composed of portions of the laminate remaining flat; and bent portions composed of portions of the laminate kept bent. In at least part of the bent portions, a solid electrolytic layer is provided between the negative electrode active material layer and the separator.