Heterostructured Ni(OH)2-Co(OH)2 composites on 3D ordered Ni-Co nanoparticles fabricated on microchannel plates for advanced miniature supercapacitor

Silicon microchannel plates (Si-MCPs) coated with a layer of nickel cobalt alloy (NCA) constitute an excellent substrate for miniature supercapacitors. Nanoscale Ni(OH)(2)-Co(OH)(2) composite particles serving as the active materials are electrodeposited on ordered three-dimensional (3D) NCA/Ni/Si-MCPs and the Ni(OH)(2)-Co(OH)(2) composites have different structures depending on the amount of Co(OH)(2) in Ni(OH)(2). The nickel hydroxide synthesized from a water-acetone 0.1 M Ni(NO3)(2)center dot 6H(2)O solvent has a compact structure, but that from a 0.1 M Ni(NO3)(2)center dot 6H(2)O solvent containing 5% Co(NO3)(2)center dot 6H(2)O is loosely packed with nanoparticles and that from a 0.1 M Ni(NO3)(2) center dot 6H(2)O solvent containing 10% Co(NO3)(2) center dot 6H(2)O contains many nanoparticles. Addition of Co(NO3)(2) center dot 6H(2)O results in a smooth morphology. The smooth structure is also observed from active materials produced in 20% and 30% Co(NO3)(2) center dot 6H(2)O solvents. Five types of electrode materials are investigated from the perspective of electrochemical capacitors by conducting cyclic voltammogram, galvanostatic charge-discharge measurements, and electrochemical impedance spectroscopy. In this experiment, the highest specific capacitance of 7.8 F cm(-2) is achieved in the samples prepared in 10% Co(NO3)(2) center dot 6H(2)O at a discharge current density of 20 mA cm (2). It is much better than 1.46 F cm (2) observed from previous attempts and the materials have excellent capacity retention. (C) 2013 Elsevier B.V. All rights reserved.