Double regulation of Mg95Ni5 hydride in suppressing ammonia and promoting hydrogen evolution for Mg(BH4)2·2NH3

•HCS Mg95Ni5 was introduced into the Mg(BH4)2·2NH3 system for the first time.•The excellent performance of inhibiting ammonia and releasing hydrogen is attributed to the dual regulation effects of MgH2 and nickel.•When the ratio of Mg(BH4)2·2NH3 and Mg95Ni5 is 2:1, the dehydrogenation kinetic properties of the composite is the best among all the samples. The study on inhibiting the release of ammonia from Mg(BH4)2·2NH3 has attracted the attention of many researchers. In this paper, a facile method was used to introduce HCS (hydriding combustion synthesis) processed Mg95Ni5 into the Mg(BH4)2·2NH3 system, which successfully suppressed the release of ammonia completely. The composite shows the best hydrogen desorption kinetics when Mg(BH4)2·2NH3 and Mg95Ni5 hydride were mixed in a mass ratio of 2:1. The initial dehydrogenation temperature of the composite is as low as 75 °C, which is 70 °C lower than that of Mg(BH4)2·2NH3. In the thermal desorption test, when the temperature rises to 500 °C, the amount of hydrogen released is 11.66 wt%, reaching 98.4% of the total amount of hydrogen released. The excellent performance of inhibiting ammonia and releasing hydrogen is attributed to the dual regulation effects of MgH2 and nickel. Magnesium hydride can effectively inhibit ammonia release, and the high dispersibility of nickel improves the kinetic performance of MgH2 in the system. This study further confirms the ammonia suppression effect of MgH2 on Mg(BH4)2·2NH3 and provides ideas for improving the kinetic performance of the composite system.