A simple approach to metal hydride alloy optimization

Hildebrand-Scott (1950) solubility parameters can be obtained for metals and alloys by calculating the cohesive energy density (CED), equal to the square of the solubility parameter, and a function of the heat of sublimation and the atomic volume. It is suggested that the solubility parameter permits estimation of the hydrogen storage capacity of an alloy and that alloys with a solubility parameter approximately equal to the parameter for hydrogen will have greater hydrogen storage capacity than other alloys. Equilibrium pressure - temperature relationships for some metal hydrides are presented in conjunction with the calculated solubility parameter and correlated with characteristics which would be useful in hydrogen-powered vehicles. Alloy properties which increase the amount of nonstoichiometric reversible hydrogen absorption are discussed.