LITHIUM ION BATTERY

PROBLEM TO BE SOLVED: To provide a lithium ion battery capable of preventing decomposition of a solvent used in an electrolyte and bringing out the energy density, which a positive active material and a negative active material essentially have, to the maximum. SOLUTION: A positive electrode side electrolyte 5 prepared by dissolving a lithium salt in a positive electrode side solvent comprising a first ionic liquid and/or a first organic solvent and a positive active material 6 are arranged on the positive electrode 1 side of a separator 3 comprising an inorganic solid electrolyte having lithium ion conductivity, and a negative electrode side electrolyte 7 prepared by dissolving the lithium salt in a negative electrode 2 side solvent comprising a second ionic liquid and/or a second organic solvent and a negative active material 8 are arranged on the negative electrode side of the separator 3. The positive electrode side solvent has a potential window in at least a potential region where the positive active material performs oxidation reduction reaction, and the negative electrode side solvent has a potential window in at least a potential region where the negative active material performs oxidation reduction reaction. COPYRIGHT: (C)2009,JPO&INPIT