Nonaqueous electrolyte secondary batteries

A nonaqueous electrolyte secondary battery comprising:

• an electrode assembly in which a positive electrode and a negative electrode are stacked together through a separator;
• a nonaqueous electrolytic solution;
• and
• an exterior case accommodating the electrode assembly and the nonaqueous electrolytic solution, wherein:
• the negative electrode is electrically connected to the exterior case,
• the exterior case contains iron,
• the nonaqueous electrolytic solution includes a fluorinated carboxylate ester and lithium fluorosulfate salt (LiSO3F),
• the fluorinated carboxylate ester is represented by the following formula:
• where R1 and R2 are each any of H, F, CH3−xFx (x is 1, 2 or 3) and R3 is an alkyl group having 1 to 3 carbon atoms or is a fluorinated alkyl group having 1 to 3 carbon atoms, and
• the lithium fluorosulfate salt (LiSO3F) is present in the nonaqueous electrolytic solution in a range from 1 mass % to 3 mass %.