| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte, having a flame resistance, a high electric conductivity, and reductive decomposition stability by containing a phosphonate in an electrolyte solvent. SOLUTION: A phosphonate is represented by the formula, wherein R1 , R2 , R3 are C1-4 alkyl groups. In particular, ones having 1-2 carbon atoms, or methyl group and ethyl group are desirable. These have high electric conductivity and reductive decomposition resistance in spite of flame resistant phosphonate compounds. The phosphonates may be used alone or in combination of two or more. A cyclic carbonic ester, for example, butylenecarbonate, and a chain carbonic ester, for example dimethylcarbonate may be added. In this case, the phosphonate, the cyclic carbonic ester, and the chain carbonic ester are preferably set to 10-80/5-50/5-50 by capacity ratios, in order to obtain high electric conductivity and reductive decomposition resistance. |
