Hydrogen storage properties of Mg 100− xNi x ( x = 5, 11.3, 20, 25) composites prepared by hydriding combustion synthesis followed by mechanical milling (HCS + MM)

Abstract

We reported the structure and the notable hydrogen storage properties of the composites Mg 100− x Ni x ( x = 5, 11.3, 20, 25) prepared from metallic powder mixtures of magnesium and nickel by the process of HCS + MM, i.e., the hydriding combustion synthesis (HCS) followed by mechanical milling (MM). X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrated that mechanical milling led to drastic pulverization and grain refinement of the composite produced by HCS. All the composites with different compositions showed a remarkable decline in dehydriding temperature comparing with that of the hydride mixtures prepared only by HCS. Furthermore, the hydriding rates of these composites were excellent. At 313 K the composite Mg 80Ni 20 showed the highest hydrogen capacity of 2.77 wt.% within 600 s among these four composites. The Mg 95Ni 5 showed maximum capacity of 4.88 wt.% at 373 K and 5.41 wt.% at 473 K within only 100 s. Some factors contributing to the improvement in hydriding rates were discussed in this paper.