Assessment of liquid crystal template deposited porous nickel as a supercapacitor electrode material

The high surface area porous nickel, obtained by template electrodeposition using a hexagonal liquid crystalline phase medium as a template was evaluated as a potential material for electrochemical capacitors using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies in 6 M KOH. A single electrode double layer capacitance of 1.4 F/cm(2) (at 2 mV/s scan rate) was obtained using CV, which corresponds to a specific capacitance of 473 F/g. EIS studies show the typical behavior of a porous electrode and the data were analyzed in terms of complex capacitance and complex power from which the relaxation time constant (tau(o)) has been determined. Nickel oxide electrode, obtained by the electrochemical oxidation of porous Ni, shows a double layer capacitance value of 171 mF/cm(2), which corresponds to a specific capacitance of 57 F/g. The relaxation time constants for the template deposited porous nickel and nickel oxide were determined to be 1.35 s and 33 ms, respectively. The values of double layer capacitance and specific capacitance of the porous nickel with fast response time are the highest values reported for nickel in the literature so far. (c) 2005 The Electrochemical Society.