The effect of ball milling time and different content of the TiNi0.56Co0.44 alloy on the structure and electrochemical properties of MgNi–x wt% TiNi0.56Co0.44 (x = 0, 10, 30, 50) alloys were studied systematically. The results indicated that the cycle durability of the alloy was improved with addition of the TiNi0.56Co0.44 alloy. By cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis, it was shown that the introduction of the TiNi0.56Co0.44 alloy could significantly improve the catalytic activity of the electrode, decrease the charge-transfer reaction resistance and the diffusion impedance of H atoms. Potentiodynamic polarization curves revealed that anti-corrosion performance of the composite electrodes was enhanced, which was responsible for the ameliorative cycle stability of composite alloys. A high discharge capacity and good cycle stability had been observed for the x = 10 (10 h) composite electrode with a maximum discharge capacity of 397 mAh/g and capacity retaining rate (S50) of 62%.
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This work was financially supported by 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).