| 摘要 |
The present invention provides a nonaqueous electrolyte solution, which can improve flame retardancy and ameliorate performances of a battery without deteriorating the basic battery performance as far as possible, and a secondary battery. The nonaqueous electrolyte solution is a nonaqueous electrolyte solution for a secondary battery that contains metal salts including ions of metals belonging to group 1 or 2 of the periodic table and a specific cyclic compound having phosphorus and nitrogen atoms in a non-protonic solvent. The non-protonic solvent is a solvent that contains at least one kind of carboxylic acid ester compound and carbonic acid ester compound, and a ratio (M PN /Ms) between a mass (Ms) of the non-protonic solvent containing the metal salts and a mass (M PN ) of the cyclic compound is 0.01 to 1. |
