Abstract
Storage capacity, working pressure and temperature, cycle life, and rate of absorption and desorption in hydrogen storage are current emphasized developing issues. We use a vacuum arc remelter to prepare as-cast alloys. The alloys are characterized by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffractometry (XRD). Pressure-composition-isotherm (PCI) curves are used to investigate the absorption and desorption of hydrogen. After detailed investigation we conclude that both equal- and non-equal-molar high-entropy alloys have a high potentiality in hydrogen storage.Results on Laves phase-related CoFeMnTiVxZry (0.4 ≦ x, y ≦ 3) high-entropy alloys shows that with Zr as a component, high-entropy alloys are easily activated and absorb hydrogen. Simultaneous addition of Zr and V improves the capacity of hydrogen absorption. In this experiment, we first adopt the most popularly used equal-molar compositions in high-entropy alloys as a base to find a suitable alloy series, then change the relative amount among components in alloys or make substitution for elements to investigate in detail the effects of elements and non-equal molar compositions on the hydrogen storage properties.An equipartition method (EPM) for calculation formation enthalpy of multicomponent metal hydrides proposed in this study shows a linear relationship between enthalpy per mole atom in alloy and maximum storage capacity in atomic ratio for a single system. On the other hand, for different systems total energy determines the maximum storage capacity among systems.