| 摘要 |
PURPOSE:To increase conductivity and charge-discharge efficiency and to make it possible to use in a wide temperature range by using a specific mixed solvent in an electrolyte, and specifying the contents of moisture and the other impurities. CONSTITUTION:A negative active material is lithium or a lithium alloy capable of discharge of a lithium ion. A positive active material is a substance which performs reversible reaction electrochemically with a lithium ion. An electrolyte is a solution obtained by dissolving a lithium salt in an organic solvent. As the organic solvent of the electrolyte, a mixed solvent of ethylene carbonate and one or more solvents selected from a group of compounds having polar double bond of >C=O and/or >S=O, in a volume ratio of 40-90% is used. The moisture contents in the electrolyte are 150ppm or less and the impurity contents other than moisture are 1,000ppm or less. Thereby, charge-discharge capacity, cycle life, and energy density are increased. |
