| 摘要 |
PROBLEM TO BE SOLVED: To enhance cycle and shelf life characteristics by including a specific amount of a phosphorus compound in the nonaqueous electrolyte. SOLUTION: In this nonaqueous electrolyte, 5 to 90 ppm of a phosphorus compound indicated by the formula is included. In the formula R1, R2 and R3 are each alkyl groups and is any one of a methyl group, ethyl group, propyl group, or isopropyl group. Where the relationship among R1, R2 and R3 satisfies any one of R1=R2=R3; R1≠R2≠R3; R1=R2 and R2≠R3; R1=R3 and R1≠R2; or R2=R3 and R1≠R2. When the electrolyte including this phosphorus compound is used, high denseness suppresses reaction of a negative electrode with the electrolyte, and a protective film capable of maintaining sufficient ion conductivity is formed in the negative electrode shape. Thereby a secondary battery having excellent both cycle and shelf life characteristics. |
