Revealing the effect of Y substitution on the hydrogen storage performance and structure of La–Ca–Mg–Ni alloy system

In this study, the effect of yttrium (Y) substitution on the microstructure and the hydrogen storage characteristics of La 0.56-x Y x Ca 1.03 Mg 1.32 Ni 9 (x = 0.05, 0.20, 0.40) alloy system was examined. Cocktailing the element inside initially AB 3 structure can introduce academically interested multiphase structure, which can eventually alter the hydrogen storage performance while reducing material costs. The yttrium increment would result in reduced unit cell volume in the structure, thereby hindering hydrogen diffusion kinetics in the samples. When tested using pressure-composition-isotherm method, the Y-substituted alloys show a low residual hydrogen remain in the alloy after room-temperature discharging. Among the three different amounts of Y substitutions, the alloy with Y = 0.05 exhibited the best balance of hydrogen capacity (1.64 wt% under 3.6 MPa hydrogen charging) and a good residual hydrogen (∼87 % useable hydrogen). Although a substitution of 40% of lanthanum by Y has decreased the hydrogen uptake from 1.64 wt.% to 1.20 wt.%, it may find applications which require higher equilibrium pressures and lower retained hydrogen. This study has demonstrated that the partial substitution of lanthanum with yttrium can be an effective strategy to tailor hydrogen storage and kinetic performance, offering promising properties for stationary applications. • Yttrium-doped, cost-effective AB₃-type La-Ca-Mg-Ni alloys show H₂ capacity comparable to conventional AB₅-type alloys. • Substituting lanthanum with yttrium significantly reduces hydrogen retention during desorption. • This work provides a potential way of tuning the hydrogen storage performance through element substitution.