To provide an energy storage device which ensures a long lifetime and excellent output characteristics in the range from low temperature to normal temperature.
The energy storage device has a positive electrode having two regions different in the reactive mechanism. The regions comprise a positive electrode Faraday layer exhibiting the faradaic reaction wherein the oxidation state of an active material is mainly changed and the electrical charge is moved into inside of the active material, a positive electrode non-Faraday layer exhibiting the non-faradaic reaction wherein the electrical charge is mainly stored/released by physically absorbing/desorbing ions to/from the surface of the active material, and a negative electrode with a region having the faradaic reaction mechanism on a negative electrode collector. As an additional characteristic, this device provides an active material to enable insertion/removal of lithium ions on the region having the faradaic reaction mechanism, and both of the positive electrode Faraday layer and the positive electrode non-Faraday layer are completely exposed on the side in opposition to the negative electrode. Fabrication of such an energy storage device ensures a long lifetime and excellent output characteristics in the range from low temperature to normal temperature.
KOBAYASHI MITSURU
OKUMURA SOUBUN
ARAI JUICHI
Next Patent: ENERGY STORAGE DEVICE