Effects of zr substitution on TiMn-based AB₂-type hydrogen storage alloy

TiMn-based alloys, specifically the AB_₂-type hydrogen storage alloys, are regarded as one of the primary promising materials for large capacity hydrogen storage. This is due to the high hydrogen storage capacity and favorable hydrogen absorption/desorption plateau pressure. However, challenges such as difficult activation, lower practical hydrogen storage capacity than theoretical capacity, and poor cycling performance limit their potential for future applications, thus requiring further improvement. In this research, Zr was used to partially substitute Ti on the A site of the alloy, resulting in the formation of Ti_0.75₋ₓZr_0.25₊ₓCr0.85Mn_0.95Fe_0.2 alloys. The results indicate that increasing the Zr content significantly enhances the hydrogen storage capacity and cycling stability of the alloy. Among them, the Ti_0.65Zr_0.35Cr_0.85Mn_0.95Fe_0.2 alloy exhibited the maximum hydrogen storage capacity of 1.866 wt.% at room temperature, with an effective hydrogen storage capacity of 1.847 wt.%. After 100 cycles at 328 K, the hydrogen storage capacity remained at 1.646 wt.%, making it one of the high-performance TiMn-based AB_₂-type hydrogen storage alloys to date. This approach enhances the hydrogen storage properties of the alloy and presents an innovative pathway for advancing TiMn-based AB_₂-type hydrogen storage alloys moving forward.