The pseudocapacitance and morphology of an electrodeposited cobalt hydroxide (Co(OH)(2)) significantly depends on the architecture of the electrode substrate. The nano-porous Ni framework, derived from the selective dissolution of Cu from a Ni-Cu alloy, effectively promotes the electrochemical utilization of deposited Co(OH)(2) even at a high loading amount condition. The great electronic and ionic conduction within the nano-structured electrode improves the energy storage performance of Co(OH)(2) as compared to that for a conventional flat Ni substrate. In this work, the Co(OH)(2) mass specific capacitance, evaluated using cyclic voltammetry (CV), only slightly decreases from 2650 to 2470 Fg(-1) when the potential sweep rate is substantially increased from 5 to 200 mVs(-1). The developed Ni(OH)(2)/NiOOH (from the nano-porous framework) incorporates with the deposited Co(OH)(2) upon CV cycling; the mixed hydroxide shows a noticeably synergistic capacitance. Furthermore, the dissolution of Co(OH)(2) in KOH electrolyte is greatly suppressed due to the incorporation of Ni(OH)(2)/NiOOH, consequently prolonging the electrode cycle life. (C) 2011 Elsevier B.V. All rights reserved.
