LiAlH4Nanoparticles Encapsulated within Metallic Titanium Shells for Enhanced Hydrogen Storage

Lithium aluminum hydride (LiAlH4) is considered as a promising hydrogen storage material due to its high gravimetric hydrogen storage density. However, sluggish hydrogen kinetics and poor reversibility have prevented its use in practical applications. Improvements of the hydrogen properties of LiAlH4 have been proposed through a nanostructuring approach of the material. Herein, we developed a method to encapsulate freestanding LiAlH4 nanoparticles within a Ti shell upon reduction of TiCl3 at their surface. The LiAlH4@Ti core–shell nanostructures obtained through precise control in the reduction kinetics and the concentration of the Ti precursor led to a significant improvement in the dehydrogenation temperatures and desorption kinetics. Indeed, 5.8 mass % of hydrogen was released within 25 min at 150 °C from LiAlH4@Ti. More remarkably, the formation of the core–shell structure led to the disappearance of the well known exothermic decomposition path of LiAlH4, which evidenced the possibility of altering the hydrogen thermodynamics of LiAlH4. Partial hydrogen reversibility was observed at 150 °C and a 10 MPa hydrogen pressure, mainly because of the loss of the core–shell structure upon hydrogen cycling. However, this demonstrates that with finer control over the nanostructuring of LiAlH4, practical hydrogen storage conditions are within reach.