Influence of addition of Cu(OH)_2 to KOH alkaline electrolyte on electrochemical properties of La_2Mg_(0.9)Al_(0.1)Ni_(7.5)Co_(1.5) hydrogen storage alloy electrode

摘要

The influence of the addition of Cu(OH)2 to 6 mol/L KOH alkaline electrolyte on the electrochemical properties of La2Mg0.9Al0.1Ni7.5Co1.5 hydrogen storage alloy electrode was investigated by electron probe X-ray microanalysis(EPMA),X-ray diffraction(XRD) and electrochemical measurements. EPMA micrographs and XRD patterns show that the surface of the hydride electrode is plated by metal copper film. The thickness and compactness of Cu film increase with the increment of charge-discharge cycle number. The copper film of the hydride electrode surface can keep the hydrogen storage alloy particle in the electrode interior from oxidizing availably. The addition of Cu(OH)2 to alkaline electrolyte lowers the activation property and the high rate dischargeability of the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrode,but has no negative effect on the maximum discharge capacity of the hydride electrode. Moreover,it is effective to improve the cyclic stability of the hydride electrode utilizing electrodeposit Cu film on the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrodes surface.