Effects of electroless composite plating Ni-Cu-P on the electrochemical properties of La-Mg-Ni-based hydrogen storage alloy

In order to improve the overall electrochemical performances of La-Mg-Ni-based hydrogen storage alloy, electroless composite plating Ni-Cu-P treatment was applied to La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10 alloy powders. SEM observation showed that the composite treatment resulted in spherical particles more densely depositing on the alloy surface, and subsequently EDS analysis indicated that the particles should be Ni-Cu-P compounds. These particle coatings enhanced the conductivity and the catalytic activity, besides acting as a protective layer, thereby improving the electrochemical properties of the alloy. The discharge capacity of the alloy electrode noticeably increased from 338 mA/g to 361 mA/g. The capacity retention after 200 charge/discharge cycles and the high rate dischargeability (HRD) at 1500 mA/g discharge current density of the alloy electrode increased from 76.0% and 27.7% to 84.8% and 37.0%, respectively. The superior HRD value is believed to be ascribed to the improved kinetics from the compact metallic layers on the surface. (C) 2013 Elsevier B.V. All rights reserved.