To solve such a problem that when chlorine ions are used in a nonaqueous electrolyte as an electrolyte salt, it is difficult to enhance the electrical characteristics or energy density of an electrochemical energy storage device and the reliability of the device may be impaired.
The nonaqueous electrolyte of the present invention includes a quaternary ammonium chloride, an alkaline earth metal chloride, and an organic solvent. A nonaqueous electrolyte having a high concentration of an electrolyte salt can be obtained, by adjusting the combination of the quaternary ammonium chloride and the alkaline earth metal chloride as well as the structure or the ratio of the organic solvent. A secondary battery or an electric double-layer capacitor can be operated by chlorine ions discharged from quaternary ammonium ions, alkaline earth metal ions and a quaternary ammonium salt in the electrolyte as well as anions generated by an alkaline earth metal chloride.
OKUMI ZENHACHI
HIRAI TOSHIRO
NAKADA AKIRA
Daisuke Nagano
Kentaro Fujii