Electrochemical Behavior of Carbide Derived Carbons in LiPF_6 and LiCF_3SO_3 Non-Aqueous Electrolytes

摘要

This paper presents the electrochemical characteristics of electric double layer capacitors (EDLCs) based on two different non-aqueous electrolytes - 1 M LiPF_6 and 1 M LiCF_3SO_4 in ethylene carbonate/dimethyl carbonate (1:1) mixture. The behavior of vanadium carbide derived carbon VC-CDC(800) and titanium carbide derived carbon TiC-CDC(950) in these electrolytes was studied using cyclic voltammetry and impedance spectroscopy. A wide region of ideal polarizability U < 3.2 V, short characteristic time constant, limiting capacitance up to 129 F g"1, and high energy and power densities were obtained for systems with LiPF_6 electrolyte, indicating that this electrolyte can be used in supercapacitors with high specific performance. In case of LiCF_3SO_4 electrolyte a lower voltage region of ideal polarizability was obtained and the highest discharge capacitance values were about 75 F g~(-1), explained by the electroreduction of CF_3SO_3~-anions and partial contamination of electrode surfaces under study.