| 摘要 |
The nonaqueous solvent of the present invention for a nonaqueous secondary battery primarily contains a mixed solvent of a fluorinated cyclic carbonate having a structure in which one fluorine atom is bonded to each of two alkoxy group carbon atoms adjacent to carbonate oxygen atoms and a fluorinated acyclic carbonate having a similar structure. The fluorinated cyclic carbonate, in comparison with the unsubstituted cyclic carbonate, has not only an enhanced thermal stability but also a suppressed reactivity with the positive electrode in a charged state even at elevated temperatures. In addition, it forms a protective film which, with respect to a negative electrode in a charged state, suppresses reactivity between the negative electrode and the nonaqueous electrolyte solution. The fluorinated acyclic carbonate suppresses the reactivity with the positive electrode in a charged state and also lowers the viscosity of the nonaqueous electrolyte solution.
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