| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte second battery which provides reduced capacity degradation following a charging/discharging cycle and has good charging/discharging cycle characteristics, by adding a specific range of concentration of sodium ions to the electrolyte. SOLUTION: The nonaqueous electrolyte second battery consists of a negative electrode and a positive electrode which can dope or de-dope lithium, and nonaqueous electrolyte solution in which electrolyte is solved in nonaqueous solvent, and the nonaqueous electrolyte solution contains 5-3000 ppm concentration of Na ions. In order to provide the electrolyte solution which contains Na ions, ion crystal which contains sodium is added to nonaqueous solution in which electrolyte is solved and the electrolyte solution is adjusted. As ion crystal, any sodium salt which can be solved in electrolyte solution can be used. Especially, NaPFb is preferable. As a Na ion source, metal Na can also be used. |
