The Roles of Aluminum, Magnesium, and Vanadium on the Dissolution and Diffusion Properties of Hydrogen in Titanium Hydrides

Although metal titanium (Ti) is widely used for hydrogen storage, the cyclical charging and discharging of hydrogen (H) typically require high temperatures, which hinders its widespread use. Charging and discharging are closely associated with the dissolution and diffusion of H in Ti. Although alloying elements in Ti have been experimentally observed to affect the dissolution and diffusion of H, the distinct roles of common dopants remain unclear. So, this study systematically investigates the influence of aluminum (Al), magnesium (Mg), and vanadium (V) on the dissolution, diffusion, and aggregation behavior of H in δ‐TiH 2 using ab initio calculations, nudged elastic band (NEB) method, and kinetic Monte Carlo (KMC) simulations. The results indicate that V hinders H dissolution, while Al and Mg, particularly Mg, promote it. Mg strongly traps H atoms, leading to significant H aggregation and facilitating the formation of H bubbles. In contrast, Al exhibits weak trapping ability, and V repels H atoms, inhibiting their accumulation. Diffusion kinetics are also affected: Al and V reduce H diffusion barriers in certain paths, whereas Mg has a negligible effect. KMC simulations confirm that H atoms predominantly cluster around Mg even at elevated temperatures, while they tend to disperse away from Al and V. These findings provide atomic‐scale insights into the role of alloying elements in H behavior in titanium hydrides, which is crucial for designing Ti‐based hydrogen storage materials.