Synergistic effects of NaAlH₄, LiBH₄, and Ni additives on the hydrogen storage performance of MgH₂

Despite its high theoretical hydrogen storage capacity, the practical application of MgH₂ as a hydrogen storage material is limited by its high dehydrogenation temperatures and sluggish hydrogenation/dehydrogenation kinetics. To address these limitations, we developed a novel MgH₂-based composite incorporating NaAlH₄, LiBH₄, and Ni, and investigated its reaction mechanisms through phase characterization after reactive mechanical grinding and hydrogenation/dehydrogenation cycling. The MgH₂-2Ni-10LiBH₄-10NaAlH₄ material exhibited an effective hydrogen storage capacity of 8.03 wt%, reversibly releasing 7.23 wt% of hydrogen within 30 min at 320 ℃ and absorbing 7.16 wt% within 10 min. Phase analysis after dehydrogenation revealed the formation of Mg, NaBH₄, LiH, Al, Mg₁₇Al₁₂, Li₃Mg₇, and Al₃Ni₂. The preferential formation of Al₃Ni₂, resulting from the higher chemical affinity between Al and Ni compared to Mg, effectively suppressed the formation of Mg₂Ni. These phase transformations significantly enhanced the hydrogenation/dehydrogenation kinetics, enabling stable cycling performance with a reversible hydrogen storage capacity of 6.85 wt% over 30 cycles. This study demonstrates that co-incorporation of Ni, NaAlH₄, and LiBH₄ can synergistically enhance the hydrogen storage properties of MgH₂, highlighting its potential as promising candidate for practical hydrogen storage applications.