Potentiostatically deposited nanostructured α-Co(OH)2:: A high performance electrode material for redox-capacitors

A high specific capacitance was obtained for alpha-Co(OH)(2) potentiostatically deposited onto a stainless-steel electrode in 0.1 M Co(NO3)(2) electrolyte at - 1.0 V vs. Ag/AgCl. The structure and surface morphology of the obtained alpha-Co(OH)(2) were studied by using X-ray diffraction analysis and scanning electron microscopy. A network of nanolayered alpha-Co(OH)(2) sheets was obtained; the average thickness of individual alpha-Co(OH)(2) sheets was 10 mn, and the thickness of the deposit was several micrometers. The capacitive characteristics of the alpha-Co(OH)(2) electrodes were investigated by means of cyclic voltammetry and constant current charge-discharge cycling in 1 M KOH electrolyte. A specific capacitance of 860 F g(-1) was obtained for a 0.8 mg cm(-2) alpha-Co(OH)(2) deposit. The specific capacitance did not decrease significantly for the active mass loading range of 0. 1-0. 8 mg cm(-2) due its layered structure, which allowed easy penetration of electrolyte and effective utilization of electrode material even at a higher mass. This opens up the possibility of using such materials in supercapacitor applications. (c) 2007 Elsevier B.V. All rights reserved.