Crucial role of Zr_xNi_y addition during hydrogen absorption/desorption of Ti₃₇V₄₀Mn₂₃ alloy

In order to improve the hydriding/dehydriding kinetics of Ti-V-Mn alloys, Ti₃₇V₄₀Mn₂₃+10 wt% Zr_xNi_y were prepared. The microstructure, kinetic properties, and hydrogen absorption/desorption mechanisms were investigated. The findings revealed that Ti₃₇V₄₀Mn₂₃ exhibited single BCC phase structure, while the addition of 10 wt% Zr_xNi_y facilitated the formation of C14 Laves phase. The Johnson-Mehl-Avrami model was adopted and demonstrated a good fit for all alloys. Ti₃₇V₄₀Mn₂₃+10 wt% Zr₈Ni₂₁ demonstrated optimal hydrogen storage kinetic properties, which exhibited a remarkable hydrogen desorption capacity of 2.15 wt% at 363 K. The promotion can be attributed to the increased presence of fresh surfaces and the enhanced C14 Laves phase proportion. Moreover, the dehydrogenation activation energy decreased from 109.91 kJ/mol to 55.20 kJ/mol after incorporating 10 wt% Zr₈Ni₂₁, indicating hydrogen atoms were easier to detach from the interior of the alloys.