Investigations on calculation of heat of formation for multi-element AB5-type hydrogen storage alloy

Abstract

With development in hydrogen energy research, more and more applications of hydrogen storage materials have been put forward. This requires synthesis of new materials for specific purpose. In context to designing of metal hydride bed, thermodynamic parameter ‘Heat of formation’ (ΔH) for hydrogen storage alloy is very important. Theoretical calculation of ΔH for binary compound or ternary hydride is accomplished by well known ‘Miedema's Rule of Reverse Stability’. Experimentally ΔH may be determined using Van't Hoff Equation. So far, theoretical calculation of ΔH for multi-element alloy is not known. In the present investigation simple phenomenological formulae have been proposed to calculate ΔH for multi-element alloy including AHm, BHm, ABn, ABnH2m, ABn-xCx, ABn-xCxH2m, ABn-x-yCxDy, ABn-x-yCxDyH2m and so on. The calculated values of ΔH in present investigation have been compared with the experimental reported value or calculated by any other model reported in literature. An excellent agreement has been observed between the two.