Electrochemical kinetic performances of electroplating Co-Ni on La-Mg-Ni-based hydrogen storage alloys

Electroplating Co-Ni treatment was applied to the surface of the La0.75Mg0.25Ni3.48 alloy electrodes in order to improve the electrochemical and kinetic performances. The Scanning electron microscope-Energy dispersive spectroscopy and X-ray diffraction results showed that the electrodes were plated with a homogeneous Co-Ni alloy film. The alloy coating significantly improved the high rate discharge-ability of the alloy electrode, and the HRD value increased to 57.5% at discharge current density 1875 mA/g after the Co-Ni-coating. The exchange current density I-0, the limiting current density I-L and the oxidation peak current also increased for the coated alloy. The improvement of overall electrode performances was attributed to an enhancement in electro-catalytic activity and conductivity at the alloy surface, owing to the precipitation of the Co-Ni layer. (C) 2015 Elsevier B.V. All rights reserved.