High-capacity and fast hydrogen de/absorption mechanism with improved thermodynamic properties by Zr doping

AB₂-type hydrogen storage alloys are widely recognized as promising solid-state hydrogen storage materials due to their ability to rapidly absorb and desorb hydrogen under mild conditions. However, their maximum hydrogen absorption capacity, desorption ratio, plateau pressure, and cycling stability still require improvement. In this study, a series of Ti_1.1-xZr_xCrMn (x = 0, 0.1, 0.2, and 0.3) alloys were synthesized to investigated the effect of Zr substitution on hydrogen storage performance. All alloys exhibit a single C14 Laves phase structure, and increasing Zr content led to an expansion unit cell volumes and a reduction in plateau pressures. When the Zr content is increased from 0.2 to 0.3, a large amount of white phase precipitates. The Ti_0.9Zr_0.2CrMn alloy represents the highest hydrogen capacity with 1.89 wt%, rapid kinetics and excellent cycling stability with no significant capacity loss after 50 cycles. The hydrogen desorption process follows a diffusion-controlled mechanism, and the Ti_0.9Zr_0.2CrMn alloy exhibiting a low hydrogen desorption activation energy of 20.66 kJ/mol. These findings offer guidance for the structural and thermodynamic design of Ti-based alloys and support their potential for practical hydrogen storage applications.