International Journal of Hydrogen Energy, Vol.34, No.23, 9402-9408, 2009
Electrochemical performance studies on cobalt and nickel electroplated La-Mg-Ni-based hydrogen storage alloys
A novel electroplating treatment was applied onto La-Mg-Ni-based La(0.88)Mg(0.12)Ni(2.95)Mn(0.10)Co(0.55)Al(0.10) alloy powders. The effect of cobalt or nickel metallic coating on morphological and electrochemical properties was studied FESEM results showed that a dense layer of spherical cobalt particles with uniform radius and an undulate layer of lamellar nickel formed on the surface of the Co- and Ni-coated alloys, respectively. These coatings enhanced the conductivity and the catalytic activity. besides acting as a protective layer, thereby improving the electrochemical properties The maximum discharge capacity increased from original 316 mAh/g to 335 mAh/g on Co-coated alloys and 336 mAh/g on Ni-coated ones, the cycling stability was enhanced and the self-discharge was suppressed. The high rate dischargeability (HRD) was ameliorated remarkably, and the HRD value at 1500 mA/g rose by 10% and 17%, for cobalt- and nickel-coated alloy electrodes respectively, which is believed to be ascribed to the improved kinetics from the metallic coatings on the surface (C) 2009 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved.