| 摘要 |
PROBLEM TO BE SOLVED: To provide an energy storage element having a high energy density like a secondary battery and an excellent output characteristic and charge- discharge cycle characteristic like a capacitor. SOLUTION: The energy storage element is composed of a positive electrode consisting of metal oxide admitting electrochemical insertion and separation of lithium ions and containing carbon having a specific surface area of no less than 1000 m<2> /g, a negative electrode containing lithium, and an electrolytic solution containing Degree 4 ammonium salt or Degree 4 phosphonium salt, wherein the metal oxide is an oxide of at least one of the metals belonging to the extent between the 4th and 6th period and between Group 3 and 12 in the Periodic Table. |
