Manabu Tsushima

Performance of Capacitors Using Organic Electrolytes

Electric double-layer capacitors (EDLC) based on charge storage at the interface between a high surface area activated carbon electrode and an electrolyte solution are characterized by their long cycle life and high power density in comparison with batteries. However, energy density of electric double-layer capacitors obtained at present is at most 1Wh/kg at a power density of 600W/kg and smaller compared with that of batteries, which limits the applications of the capacitor. Therefore, new capacitors which show larger energy density than that of electric-double layer capacitors are proposed. The new capacitors are hybrid capacitors consisting of activated carbon cathode, Li-doped graphite anode and an organic electrolyte. Maximum voltage applicable to the cell becomes over 4.0V which is larger than that of the electric double-layer capacitor. As a result, discharged energy density of the cell becomes 4Wh/kg at a power density of 600W/kg.