| abstract |
To provide an energy storage device with high electric capacitance in relation to an electrical double layer storage device. The energy storage device comprises a positive electrode material containing graphite, a negative electrode material containing an oxide of at least one metal element selected from Ti, Zr, V, Cr, Mo, Mn, Fe, Co, Ni, Cu, Zn, Sn, Sb, Bi, W and Ta, which may preferably contains a metal oxide containing at least Ti as a metal element, and an electrolyte solution. This energy storage device has high capacitance and high discharge voltage, thereby having high energy, and the device can have high energy density, while being excellent in cycle characteristics and rate characteristics. |