Nonaqueous electrolyte secondary battery, battery assembly, and method of manufacturing the same

A battery assembly comprising:

• a positive electrode that includes a positive electrode active material layer containing a positive electrode active material and N-methyl-2-pyrrolidone;
• a negative electrode that includes a negative electrode active material layer containing a negative electrode active material;
• and
• a nonaqueous electrolytic solution that contains an oxalato complex compound, wherein
• a following expression of 0.000036≦B2/A2′≦0.001048 is satisfied, where A2′ ppm represents a content of N-methyl-2-pyrrolidone per unit mass in one of five regions which is most distant from the negative electrode, the five regions being equally divided from the positive electrode active material layer in a thickness direction, and B2 mol/kg represents a content of the oxalato complex compound per unit mass of the negative electrode active material.

A nonaqueous electrolyte secondary battery comprising:

• a positive electrode that includes a positive electrode active material layer containing a positive electrode active material;
• a negative electrode that includes a negative electrode active material layer containing a negative electrode active material;
• and
• a nonaqueous electrolytic solution, wherein
• the negative electrode active material includes a film, and
• the film contains a component derived from an oxalato complex compound and a component derived from N-methyl-2-pyrrolidone.