Synergistic hydrogen desorption of HCS MgH₂+LiAlH₄ composite

MgH₂ was prepared by HCS (hydriding combustion synthesis) method, and the as-prepared product (HCS MgH₂) was further combined with LiAlH₄ by mechanical milling in order to form a new composite of HCS MgH₂+LiAlH₄. Structural and hydrogen storage properties of the HCS MgH₂+LiAlH₄ composite have been investigated systematically by XRD (X-ray diffraction), SEM (scanning electron microscope), DSC (differential scanning calorimetry) and hydrogenation/dehydrogenation measurements. A mutual destabilization effect has been observed between HCS MgH₂ and LiAlH₄ during hydrogen desorption. The dehydrogenation mechanism of the composite has been revealed. Compared with commercial MgH₂ (Com MgH₂)+LiAlH₄ composite, the HCS MgH₂+LiAlH₄ composite shows more pronounced synergistic hydrogen desorption with notably decreased dehydrogenation temperature owing to the unique microstructures of the HCS MgH₂, which may provide favorable channels for diffusion of hydrogen atoms and promote synergistic hydrogen desorption of the composite. The dehydrogenation barrier of the HCS MgH₂+LiAlH₄ composite is lower than that of the Com MgH₂+LiAlH₄ composite. Moreover, the HCS MgH₂+LiAlH₄ composite exhibits fast re-hydrogenation kinetics in the first two cycles. •One reactive HCS MgH₂+LiAlH₄ composite has been developed for the first time.•Synergistic hydrogen desorption between HCS MgH₂ and LiAlH₄ has been observed.•HCS MgH₂ shows more pronounced mutual destabilization effect than commercial MgH₂.•The novel composite shows fast re-hydrogenation kinetics in the first two cycles.