Enhanced Power Performance of Highly Mesoporous Sol-Gel TiC Derived Carbons in Ionic Liquid and Non-Aqueous Electrolyte Based Capacitors

Abstract

The electrical double layer capacitors (EDLC) based on hierarchical micro-mesoporous sol-gel TiC derived carbon (SgTiC-CDC) electrodes and 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMeImBF4) and 1M Et3MeNBF4 + acetonitrile (AN) as the electrolytes were tested to establish the electrochemical characteristics and region of ideal polarizability. The precursors for the micro-mesoporous carbon electrodes were synthesized via modified sol-gel synthesis process. Compared to traditional titanium carbide derived carbons, where precursor carbide is commercially available, the sol-gel TiC derived hierarchical carbon materials exhibit larger specific density functional theory (DFT) surface areas (up to 1700 m2 g−1) and an unique pore size distribution with more mesopores between 2 and 10 nm. The electrochemical properties of the EDLCs were investigated using the cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge/discharge and constant power discharge methods. The EDLCs demonstrated nearly ideal capacitive behavior even at very high charging/discharging currents (10 A g−1) and cell potential scan rates (500 mV s−1). The EDLCs completed from SgTiC-CDC materials and EtMeImBF4 and Et3MeNBF4 + AN show good energy efficiencies (varying from 93% to 95% at current 1 A g−1) and coulombic efficiency values exceeded 99%. Thus, the EDLCs completed are very promising devices for extremely high power/energy density applications.