Effect of Complex Surface Treatment on Morphology and Electrochemical Properties of La–Mg–Ni-Based Alloys

Abstract

La-Mg-Ni-based hydrogen storage alloys show high electrochemical capacity, and thus have been considered as promising negative electrode materials of metal hydride/nickel secondaray batteries. In our endeavor to improving high rate dischargeability of the alloys, first fluorination and subsequent microencapsulation with Co-Mo modificatioin layer was performed on the alloy particle surface. The scanning electrode microscopy and energy despersive spectroscopy results show that the untreated alloy has a smooth surface, while the complex treatment creats a coarse modification layer, consisting mainly of Mo and Co elements. The electro-catalytic activity on the alloy surface was ameliorated owing to the charge centers in the modification layer, bringing a noticleable improvement to the electrochemical properties. The maximum discharge capacity increases by 18 mAh/g, the middle discharge voltage rises by 0.013 V and the high rate dischargeability at 1500 mA/g mouts up by 9.2%.