Synergistic hydrogen desorption of HCS MgH2 + LiAlH4 composite

• 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.

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.