Thermodynamics and kinetics of hydrogen absorption–desorption of highly crystalline LaNi₅

Lanthanum penta-nickel (LaNi₅) has been considered as potential candidates for hydrogen storage application at room temperature (20 °C). The intermetallic could store more than 1.36 mass % hydrogen. Substantially, work has been done on the hydrogenation–dehydrogenation kinetics and thermodynamics of LaNi₅. It has been reported that the hydrogen storage capacity reduced after single activation due to the deep trap of hydrogen. The kinetics and thermodynamics of trap hydrogen need to be quantified to understand the nature of trap and the required temperature to release the trapped hydrogen. In the current study, thermodynamics and kinetics of hydrogenation–dehydrogenation of high phase purity crystalline LaNi₅ were investigated. Sievert's apparatus was used to investigate the pressure composition-temperature measurement to find out the cyclic hydrogen storage capacity and the thermodynamic parameters. The thermodynamic data obtained were evaluated using high-pressure differential scanning calorimetric technique. The trap hydrogen and their desorption kinetics were studied using thermogravimetric–thermal analysis–mass spectrometric techniques.