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

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)(3)CH3NBF4 electrolyte in acetonitrile and micro/mesoporous carbon electrodes prepared from alpha-tungsten carbide, noted as WC-CDC. The N-2 sorption (total BET specific surface area (S-BET <= 1580 m(2) g(-1)), micropore area (S-micro <= 1550 m(2) g(-1)), total pore volume (V-tot <= 0.89 cm(3) 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 (Delta E = 3.0 V), characteristic time constant (iota(R) = 0.41 s), specific series capacitance (C-m;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 T-synt = 1000 degrees C, have been calculated at cell potential 3.0 V. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.021203jes] All rights reserved.