Electrochemical Behavior of α-Tungsten Carbide-Derived Carbon Based Electric Double-Layer Capacitors

Abstract

Cyclic voltammetry, constant current charge/discharge, electrochemical impedance spectroscopy and constant power methods have been applied to establish the electrochemical characteristics for electric double–layer capacitor (EDLC) consisting of 1 M (C2H5)3CH3NBF4 electrolyte in acetonitrile and micro/mesoporous carbon electrodes prepared from α–tungsten carbide, noted as WC–CDC. The N2 sorption (total BET specific surface area (SBET ≤ 1580 m2 g−1), micropore area (Smicro ≤ 1550 m2 g−1), total pore volume (Vtot ≤ 0.89 cm3 g−1) and pore size distribution (obtained by non–local density functional theory) have been correlated with the electrochemical characteristics for EDLCs (region of ideal polarizability (ΔE = 3.0 V), characteristic time constant (τR = 0.41 s), specific series capacitance (Cm;s ≤ 132 F g−1)) dependent on the WC–CDC synthesis temperature. High specific energy (41 W h kg−1) and specific power (430 kW kg−1) values, normalized to the total active mass of both WC–CDC electrodes, synthesized at Tsynt = 1000°C, have been calculated at cell potential 3.0 V.