The application of mathematical models to the calculation of selected hydrogen storage properties (formation enthalpy and hysteresis) of AB2-type alloys

Two mathematical models have been applied to AB2-type hydrogen-absorbing alloys. The first model is for the calculation of hydride formation enthalpy and the second model allows for the calculation of P-C-T curves. Certain physical parameters (activity coefficient of hydrogen (γ), partial molar volume of hydrogen (V̄H), solution heat of hydrogen (ΔHs), enthalpy (ΔH) and entropy (ΔS) of formation of a hydride, slope factor (fs) of a plateau and the variation rate (k) of slope factor with respect to temperature in a plateau region of P-C-T curves) for these intermetallic compounds and their hydrides are estimated from these models. From the second model, the relationship between the hysteresis factor (RT ln Pa/Pd) and temperature, hydrogen concentration and slope factor of the plateau region for the P-C-T curves has been obtained.