LAUSR

Abstract We focused on the work function of metals as an index of ion binding property between metals and hydrogen and analyzed the relation between the standard entropy change of metal hydrides and the work function of metals (alloys). The standard entropy change of saline hydrides and metallic hydrides roughly increased with the work function. It was indicated that hydrogen storage alloys consist of metal elements A and B whose work functions are small and large, respectively. The standard entropy changes of alloy-based metal hydrides with different composition ratio ΔS0 linearly increased with the work functions of the alloys Wc. Wc also linearly increased with the bulk modulus Bc. Then, it was found that ΔS0 was proportional to the standard heat of formation ΔH0 because dWc/dBc, dΔS0/dWc and dΔH0/dBc are constant.