High energy density electric double-layer capacitor by Li-doping techniques

Improvement of the energy density of electric double-layer capacitor (EDLC) consisting of a pair of polarized electrodes of activated carbon and non-aqueous electrolyte is one of the important factors for applications such as electric vehicles or high power electric sources. The cell voltage of EDLC is limited by the electrochemical potential window of the non-aqueous electrolyte, which is 2.5V to 3.0V. In the present work, we could make the cell voltage higher (>3V) by doping lithium ions to activated carbon electrodes, resulting in a quadratic increase of the power density of the EDLC and longer charge-discharge cycle life.