Electrochemical Performance Studies on Nickel-cobalt Electroplated La-Mg-Ni-based Hydrogen Storage Alloys

doi:10.3724/SP.J.1077.2010.00647

Abstract

Abstract: In order to improve cycling stability and overall electrochemical properties of La-Mg-Ni-based hydrogen storage alloys, an electroplating treatment was applied on La_0.88Mg_0.12Ni_2.95Mn_0.10Co_0.55Al_0.10alloy powders. The effect of cobalt-nickel coating on the morphological and electrochemical properties was studied. FESEM results show that spherical nickel-cobalt alloy particles are deposited on the surface of the alloys. Electrochemical tests indicate that the maximum discharge capacity, the cycling stability and the high rate dischargeability (HRD) are remarkably improved. After 200 charge/discharge cycles, the capacity retention rate increases from 60% (uncoated) to 80% (nickel-cobalt coated). The HRD at 1080mA/g rises by 23% for the nickel-cobalt coated alloy electrodes. Linear polarization and Electrochemical Impedance Spectroscope (EIS) results reveal that the surface of alloy electrodes with cobalt-nickel coatings is more catalytic for the electrochemical charge transfer reactions.

Key words: La-Mg-Ni-based hydrogen storage alloy, surface treatment, electroplating, nickel-cobalt alloy, electrochemical characteristics

CLC Number:

TM 912

DING Hui-Ling1,2, HAO Jian-Sheng1,3, ZHU Xi-Lin2,3, LI Yuan2, HAN Shu-Min1,2, ZHANG Jing-Wu1. Electrochemical Performance Studies on Nickel-cobalt Electroplated La-Mg-Ni-based Hydrogen Storage Alloys[J]. Journal of Inorganic Materials, 2010, 25(6): 647-652.

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