Effect of Ni content on the hydrogen storage behavior of ZrCo1−xNix alloys

ZrCo1−xNix (x = 0, 0.1, 0.2 and 0.3) alloys were prepared and their hydrogen storage behavior were studied. ZrCo1−xNix alloys of compositions with x = 0, 0.1, 0.2 and 0.3 prepared by arc-melting method and characterized by X-ray diffraction analysis. XRD analysis showed that the alloys of composition with x = 0, 0.1, 0.2 and 0.3 forms cubic phase similar to ZrCo with traces of ZrCo2 phase. A trace amount of an additional phase similar to ZrNi was found for the alloy with composition x = 0.3. Hydrogen desorption pressure–composition–temperature (PCT) measurements were carried out using Sievertʹs type volumetric apparatus and the hydrogen desorption pressure–composition isotherms (PCIs) were generated for all the alloys in the temperature range of 523–603 K. A single sloping plateau was observed for each isotherm and the plateau pressure was found to increase with increasing Ni content in ZrCo1−xNix alloys at the same experimental temperature. A vanʹt Hoff plot was constructed using plateau pressure data of each pressure–composition isotherm and the thermodynamic parameters were calculated for desorption of hydrogen in the ZrCo1−xNix–H2 systems. The enthalpy and entropy change for desorption of hydrogen were calculated. In addition, the hydrogen absorption–desorption cyclic life studies were performed on ZrCo1−xNix alloys at 583 K up to 50 cycles. It was observed that with increasing Ni content the durability against disproportionation of alloys increases.