The electrochemical properties of MmNi3.6Co0.7Al0.3Mn0.4 alloy modified with carbon nanomaterials by ball milling

The MmNi3.6Co0.7Al0.3Mn0.4 alloy surface is modified with multiwalled carbon nanotubes and carbon black (10 wt.%) by ball milling for 50 min. The microstructures of the obtained materials are examined and analyzed by X-ray diffraction, SEM and TEM. It is confirmed that the surface of AB5 alloy is modified by shorter carbon nanotubes and thin carbon flake, respectively, when carbon nanotubes and carbon black are added. The electrochemical properties of the obtained materials are measured and compared with those of the original AB5 alloy. It is found that high rate discharge ability of the alloys after surface modification by carbon nanomaterials increases to some extent due to the decrease of electrochemical reaction resistance and the increase of double capacitance as obtained by electrochemical impedance spectra. In particular, the modified alloy with the carbon nanotubes shows a superior performance to carbon black, especially in the discharge rate of 2000 mA/g. Besides, the addition of carbon nanomaterials reduces the extent of the amorphism of the AB5 alloy during ball milling