Synergistic function of milling time and Ni addition on microstructure and hydrogen storage properties of CeMg12 type materials

In order to ameliorate hydrogen storage properties of the CeMg ₁₂ series alloy, the paper investigated the influence of ball milling time and Ni content on the microstructure and gaseous hydrogen sorption properties of alloys. Microstructure studies have shown that prolonging milling time and adding nickel are beneficial for the formation of amorphous and nanocrystalline structure; the formation of rare earth hydrides CeH _2.51 and Mg ₂NiH ₄ in situ inside the alloy can provide catalytic function for improving the hydrogenation and dehydrogenation properties of the alloy. The addition of nickel powder and the increment of ball milling time are propitious to amend the hydrogen absorption and desorption performances of ball milling CeMg ₁₂ alloy. The CeMg ₁₂/Ni alloy of ball-milled for 10 h has the best thermodynamic properties including platform and hysteresis effect of absorption and desorption. For CeMg ₁₂/Ni under going ball milling 10 h treatment, the absolute value of enthalpy in the process of dehydriding of Mg/MgH ₂ system is reduced from 76.32 kJ/mol to 70.27 kJ/mol when the Ni content increases from 0 wt% to 30 wt%. With respect to the dynamic properties of alloys, proper prolongation of ball milling time and increase of nickel content are beneficial to improve the dehydrogenation kinetics of the alloy, the ball milling CeMg ₁₂+20 wt%Ni alloy for 10 h has the best dynamic property.