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 Sievert's 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 van't 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-H-2 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. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.