| abstract |
Disclosed is an energy storage device comprising a positive electrode mainly composed of an activated carbon, a negative electrode mainly composed of a compound which is obtained by having a carbonaceous material capable of adsorbing/desorbing lithium ions adsorb lithium ions up to 75-100% of the full adsorption capacity of the carbonaceous material, and an electrolyte solution containing a lithium salt and a nonaqueous solvent. The energy storage device hardly decreases in capacity and has high reliability. This energy storage device is able to supply high capacity energy during a momentary power outage or the like. |