Effects of metal oxides addition on the electrochemical performance of M1Ni3.5Co0.6Mn0.4Al0.5 hydrogen storage alloy
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The AB5-type M1Ni3.5Co0.6Mn0.4Al0.5 alloy (where M1 denotes mixed lanthanide) was modified with different additives (ZnO and MnO2), and the effects of metal oxides on the electrochemical properties of the M1Ni3.5Co0.6Mn0.4Al0.5 − x% M (x = 5, 10; M = ZnO, MnO2) alloy were studied. The results showed that the addition of metal oxides had a positive effect on the activation property of the alloy electrode. With the addition of ZnO, the maximum discharge capacity of the alloy increased from 315 to 334 mAh/g (x = 5) and 341 mAh/g (x = 10) with good cycle capability (C30/Cmax) (87% for x = 5 and 85% for x = 10), while the maximum discharge capacity remained invariable and the cyclic stability was deteriorated by the addition of MnO2. Linear polarization (LP), cycle voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements were also performed to investigate the electrochemical kinetics of alloy electrodes.
KeywordsMnO2 Discharge Capacity Electrochemical Impedance Spectroscopy MgH2 Exchange Current Density
The authors wish to express their thanks to the National Natural Science Foundation of China (50772133) and the Open Subject of State of Key Laboratory for Powder Metallurgy of Central South University (2008112009).