Development of Ti-V-Cr-Mn-Mo-Ce high-entropy alloys for high-density hydrogen storage in water bath environments

The V-based body-centered cubic(BCC)-type hydrogen storage alloys have attracted significant attention due to their high theoretical hydrogen storage capacity of3.80 wt%.However,their practical application faces challenges related to low dehydriding capacity and poor activation performance.To overcome these challenges,a BCC-type Ti-V-Cr-Mn-Mo-Ce high-entropy alloy(HEA)with an effectively dehydriding capacity of 2.5 wt% above 0.1 MPa was prepared.By introduction of Mo and conducting heat treatment,the precipitation of Ti-rich phase in HEA was successfully suppressed,resulting in improved compositional uniformity and dehydriding capacity.Consequently,the effective dehydriding capacity increased significantly from 0.60 wt% to 2.50 wt% at 65℃,surpassing that of other types of hydrogen storage alloys under the same conditions.Moreover,the addition of 1 wt%Ce enabled initial hydrogen absorption at 25℃ without the need for activation at 400℃.Furthermore,Ce doping reduced the dehydriding activation energy of the Ti-V-Cr-Mn-Mo-Ce HEA from 52.71 to 42.82 kJ·mol^(-1)Additionally,the enthalpy value of dehydrogenation decreased from 46.89 to 17.96 k J·mol^(-1),attributed to a decrease in the hysteresis factor from 0.68 to 0.52.These findings provide valuable insights for optimizing the hydrogen storage property of HEA.