Improved dehydrogenation properties of Mg(BH4)2·2NH3 combined with LiAlH4

• Effect of LiAlH4 on the dehydrogenation of Mg(BH4)2·2NH3 system is investigated.
• The decomposition properties of Mg(BH4)2·2NH3 are improved by the addition of LiAlH4.
• Decomposition processes of the Mg(BH4)2·2NH3–2LiAlH4 composite are studied.

The decomposition properties of Mg(BH4)2·2NH3 combined with LiAlH4 mixtures were investigated systematically. It revealed that the hydrogen desorption temperature shifted to 100 °C with the superior suppression of ammonia, and desorption rates were improved with the increased LiAlH4 ratio (0.5, 1, 2), respectively. When the LiAlH4 ratio was increased to 2, the binary system exhibited three dehydrogen steps with an onset temperature at 98 °C and 5.4 wt % H2 desorbed rapidly at the same temperature, while no apparent evolution of H2 was observed for individual Mg(BH4)2·2NH3 and LiAlH4 below 150 °C. The dehydrogenation rate of the system was improved by about 92% more than that of Mg(BH4)2·2NH3. These results indicate that the dehydrogenation of Mg(BH4)2·2NH3 is enhanced significantly by the introduction of LiAlH4. The synergetic factor of the aided-cation effect and dihydrogen interaction may contribute to prevent the NH3 group from being dissociated as ammonia.