Enhancing the oxidation resistance in Ti–V–Mn hydrogen storage alloy by adding Zr8Ni21

Abstract

BCC-type hydrogen storage alloys suffer from rapid oxidation degradation. This study demonstrates that incorporating 10 wt% Zr₈Ni₂₁ intermetallic compound into Ti₃₇V₄₀Mn₂₃ significantly enhances its oxidation resistance and preserves hydrogen storage capacity. The results revealed that the hydrogen absorption capacity (at 303 K) of Ti₃₇V₄₀Mn₂₃ alloy decreased drastically from 3.10 wt% to 0.64 wt% after just one day of exposure to air, indicating severe oxidation. The newly developed alloy maintained the hydrogen absorption capacity (at 303 K) of 2.81 wt% even after 90 days of air exposure; and its hydrogen desorption capacity (at 303 K) remained at 99.2 % of the original value. Long-term oxidation slightly reduced desorption plateau pressure and decreased desorption enthalpy to 31.2 kJ/mol H₂, indicating reduced hydride stability. The superior performance stems from: (i) Zr₈Ni₂₁ addition reducing surface metal oxides while increasing oxygen vacancies, facilitating H-diffusion from the surface to the bulk; (ii) Zr's strong oxygen affinity enabling sacrificial early-stage oxidation, protecting the BCC phase; and (iii) absence of oxygen-enriched phases, maintaining an unoxidized alloy core.