NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD OF MANUFACTURING NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

A nonaqueous electrolyte secondary battery that is an example of an embodiment includes a flat electrode body that has a winding structure in which a positive electrode and a negative electrode are wound with a separator interposed in between, in which flat portions and bend portions are formed in the flat electrode body. A negative electrode mixture layer is provided in the negative electrode to a winding outer end thereof. The negative electrode includes an extension portion that extends out from a winding outer end of the positive electrode towards a winding direction outer side. A length L of the extension portion in a winding direction satisfies a condition L/((a−b)×2+bπ)>0.135, where a is a width of the electrode body and b is a thickness of the electrode body.