Effect of SiC on hydrogen storage properties of Mg ₉₅Ni ₅ prepared by hydriding combustion synthesis and mechanical milling

The effect of SiC on the hydrogen storage properties of Mg ₉₅Ni ₅ prepared by hydriding combustion synthesis and mechanical milling (HCS + MM) was studied. Product with 2 wt.% SiC doping is the best one among these HCS + MM products in improving the hydrogen storage properties. It required only 80 s to reach its saturated hydrogen capacity of 5.91 wt.% at 373 K and desorbed 69.7% hydrogen within 1800 s at 523 K. The activation energy for hydrogen desorption decreased from 160 kJ/mol for Mg ₉₅Ni ₅ to 143 kJ/mol for Mg ₉₅Ni ₅ + 2 wt.% SiC, indicating that SiC has an obvious positive effect on the dehydriding properties. More importantly, cyclic hydriding analysis demonstrated that the HCS + MM-Mg ₉₅Ni ₅ + 2 wt.% SiC composite possessed excellent cyclic hydriding stability at 473 K. It is suggested that the microstructures of the HCS + MM products with SiC addition had remarkable influence on the enhancing of the hydriding/dehydriding and cyclic properties.