Effect of La/Ce on the gas-phase hydrogen absorption and desorption kinetics of AB₅-type alloy

The La_1-xCe_xNi₅（x = 0,0.25,0.5） rare earth-based hydrogen storage alloys were prepared by vacuum arc furnace melting method. The effects of La/Ce content on the microstructure and hydrogen absorption and desorption kinetics were investigated through XRD and PCT. The XRD results showed that the main phase of the hydrogenated alloy was LaNi₅. Partial substitution of La with Ce did not change the original phase composition,but the unit cell volume of the alloy gradually decreased. In addition,the isothermal platform pressure of the alloy gradually increased as the amount of Ce increases,and the hydrogen absorption kinetics accelerated. When x = 0.5,the time for the alloy to reach the inflection point of the hydrogen absorption curve was 52 s. Moreover,the desorption activation energy also decreased with the increase of Ce content. The desorption activation energy of the x = 0.5 alloy was 28.5 kJ/mol.