Direct Synthesis of LiAlH4 from Ti-Doped Active LiAl Alloy

LiAlH4, characterized by high hydrogen capacity and metastable properties, is regarded as a promising hydrogen source under mild conditions. However, its reversible regeneration from dehydrogenated production is hindered thermodynamically and kinetically. Herein, we demonstrate an active Li–Al–Ti nanocrystalline alloy prepared by melt spinning and cryomilling to enable directly synthesizing nano-LiAlH4. Due to the non-equilibrium preparation methods, the grain/particle size of the alloy was reduced, stress defects were introduced, and the dispersion of the Ti catalyst was promoted. The refined Li–Al–Ti nanocrystalline alloy with abundant defects and uniform catalytic sites demonstrated a high reactivity of the particle surface, thereby enhancing hydrogen absorption and desorption kinetics. Nano-LiAlH4 was directly obtained by ball milling a 5% Ti containing Li–Al–Ti nanocrystalline alloy with a grain size of 17.4 nm and Al3Ti catalytic phase distributed under 20 bar hydrogen pressure for 16 h. The obtained LiAlH4 exhibited room temperature dehydrogenation performance and good reversibility. This finding provides a potential strategy for the non-solvent synthesis and direct hydrogenation of metastable LiAlH4 hydrogen storage materials.