Reversible H2 storage at moderate temperature by a trilayered lithium borohydride nanocomposite

Hydrogen storage in lithium borohydride (LiBH4) with high gravimetric and volumetric hydrogen densities has attracted intensive research interest. However, the high working temperatures and poor reversibility due to the high thermodynamic stability and kinetic barriers limits its practical applications. Herein, we fabricate a trilayered nanostructure composed of graphene, Ni nanoclusters, and LiBH4 nanoparticles in sequence, through a layer-by-layer assembly approach, where LiBH4 is mostly partitioned from graphene by the Ni nanoclusters. The use of graphene plays important role on uniformly dispersing Ni nanoclusters and forming LiBH4 nanoparticles. The direct contact of Ni nanoclusters with LiBH4 significantly promotes the cleaving of the H-H bonds and B clusters during hydrogenation, creating additional hydrogen absorption sites and reducing the H adsorption energy of B. As a result, a high reversible storage of 12.3 wt% H2 with respect to LiBH4 commencing from 70 °C to 350 °C under 100 bar H2 is achieved. This finding guides the design and fabrication of light-metal hydride nanostructures for practical on-board hydrogen storage applications. LiBH4 is promising for hydrogen storage but limited by high kinetic barriers. Here, a trilayered graphene/Ni/LiBH4 nanostructure is fabricated, enabling a reduced H-adsorption energy, thus a high reversible storage capacity under moderate conditions.