Powder Materials. High Energy Density Electric Double Layer Capacitor.

High energy density electric double layer capacitor (12V·200F) for maintenance free power source was developed. The energy density is 1.48 Wh/kg at 25 °Cand 1.11 Wh/kg even at -25 °C. The capacitor supplies electric current at 100 mA for 6 hours. The capacitance decrease at low temperature was improved by optimizing the density of the activated carbon/carbon composite electrode.