LiPF 6 based ethylene carbonate–dimethyl carbonate electrolyte for high power density electrical double layer capacitor

Abstract

Electrochemical characteristics of the electrical double layer capacitor based on the two identical microporous carbide derived carbon C(TiC 950) electrodes in 1 M LiPF 6 ethylene carbonate–dimethyl carbonate (1:1 by volume) mixture have been studied using cyclic voltammetry and electrochemical impedance spectroscopy. Specific capacitance, phase angle, series and parallel resistances, characteristic time constant, energy and power densities etc. have been calculated and found to be dependent on the cell potential applied. Wide region of ideal polarisability Δ E ≤ 3.2 V, short characteristic time constant and high limiting capacitance 129 F g −1, complex power and maximal energy and power density values have been obtained, indicating that this electrolyte can be used for high energy and power density supercapacitors. Additionally, the supercapacitors based on the partially graphitized C(VC) (applied as negatively charged electrode) and amorphous C(TiC 950) (applied as positively charged electrode) were completed and tested. The calculated energy and power densities were for asymmetrical C(VC 1100)|C(TiC 950)|1 M LiPF 6 + EC + DMC cell 26.2 Wh kg −1 and 57.2 kW kg −1, respectively, but for symmetrical C(TiC 950)|C(TiC 950)|1 M LiPF 6 + EC + DMC cell somewhat higher energy density 36.7 Wh kg −1 and power density 83.6 kW kg −1 values were established.