Relevance of the Semiconductor Microstructure in the Pseudocapacitance of the Electrodes Fabricated by EPD of Binder-Free β-Ni(OH)2 Nanoplatelets

Ni foams have been coated with beta-Ni(OH)(2) nanoplatelets through a simple, green and cost-effective method which consists in the direct Electrophoretic Deposition (EPD) of particles from the post-reaction medium in an one-pot process. Further thermal treatment leads to NiO coatings for its application as electrode in pseudocapacitors. p-Ni(OH)2 nanoplatelets were produced by a chemical precipitation of Ni precursors, free of synthesis modifiers and with the aid of ultrasound. The stabilization of the nanoplatelets was carried out in a solvent mixture of 19:1 EtOH:H2O adding polyethielimine (PEI). Deposited films were sintered at 325 degrees C and 450 degrees C, resulting in semiconductor structures exhibiting and elevated connectivity in absence of any kind of binders or carbon connectors. The influence of the nanoplatelets packing and sintering on the final microstructure and the electrochemical performance of the electrode were discussed in terms of specific capacitance. Values of 363 and 424 F/g were obtained for films with the same amount of the deposited mass sintered at 325 and 450 degrees C, respectively. Moreover, the reliability of the proposed method allows the fabrication of electrodes with different amounts of electroactive material and porosity. The well-interconnected microstructure and the good adhesion of the NiO film to the Ni substrate provides a high cycling stability during 1000 cycles. (C) 2015 The Electrochemical Society. All rights reserved.