Effect of La Doping on Kinetic and Thermodynamic Performances of Ti1.2CrMn Alloy upon De/Hydrogenation.

ABSTRACT

Development of efficient hydrogen storage materials is one of the great challenges in the area of hydrogen energy and fuel cells. Herein, a La-doped Ti1.2CrMn alloy with high hydriding capacity (2.1 wt % H) and dehydriding capacity (1.8 wt % H) was successfully developed. The crystallographic characteristics, microstructural evolution, and hydrogen storage mechanisms of the alloy were investigated systematically. It was found that the introduction of La increased the cell volume of alloy and thus improved the hydrogenation kinetic, practical hydrogenation capacity, and cyclic property. The hydrogenation kinetic results of the La-doped alloy indicate that it exhibited a higher hydrogenation rate than that of the La-free alloy. It is ascribed to the formation of LaH3, which provides a fast diffusion channel for hydrogen atoms to enter the alloy matrix. The dehydrogenation enthalpy (ΔH) of the La-doped alloy was calculated by the van't Hoff equation and PCT curves to be ∼18.2 kJ/mol. The cycle test proves that the La-doped Ti1.2CrMn alloy, due to La addition, reduces the lattice expansion and lattice stress and exhibits excellent durability.