Preparation of nickel modified activated carbon/AB5 alloy composite and its electrochemical hydrogen absorbing properties

Due to the good catalysis of metal nickel for the electrochemical reduction/oxidation reactions between H2O and H in alkaline electrolyte, it is separately introduced into activated carbon (AC) by ball milling (named AC-1), liquid phase reduction (AC-2) and hydrothermal (AC-3) methods. The results of scanning electron microscopy (SEM) show that different to the aggregation of metal nickel in AC-1 and the coating of metal nickel on the surface of AC-2, metal nickel introduced by the hydrothermal method is uniformly dispersed among the AC-3 particles. The AC-3/AB5 alloy (90 wt%) composite shows the best electrochemical hydrogen absorbing activity. Its capacity at a 0.2 C rate reaches to 318 mA h/g. Compared to the AB5 alloy electrode, its discharge capacity separately increases 16% at a 1 C rate and 59% at a 3 C rate, which is particularly suitable for the high-power nickel metal-hydride (Ni–MH) battery.