Metal Hydrides Of Mg₂NiH₄-LiBH₄ Hydrogen Storage Performance Impact

LiBH₄/Mg₂NiH₄ sysytem has been considered as the potential hydrogen storage material material due to its fine reversible hydrogen storage performance in relatively mild conditions. However, the poor hydrogenation/dehydrogenation rate and the relative high temperature of reversible hydrogen storage restrict its practical application. In this study,4Li BH4 + 5Mg2 Ni H4 + 20 wt.% REH（REH = La H3 and Nd H2.5） and 4Li BH4 + 5Mg2 Ni H4+ 20 wt.% TMH（TMH = YH3 and Nb H） composites were prepared by ball milling LiBH₄/Mg₂NiH₄ and rare earth hydride or transition metal hydride powders. In this work,the microstructures and reversible hydrogen storage properties of composites were investigated.The study found that the use of La Mg2 Ni and Nd Mg2 Ni alloys hydrogenation decomposition of La H3 and Nd H2.5. La H3 and Nd H2.5 can improve the kinetic and thermodynamic properties of the LiBH₄/Mg₂NiH₄ system. At 548 K, 0.01 MPa hydrogen pressure, the 4Li BH4 + 5Mg2 Ni H4 + 20 wt.% REH（REH = La H3 and Nd H2.5） composites at 500 s release amount of hydrogen was increased by 0.68 wt.% and 0.24 wt.% than Li BH4-Mg2 Ni H4 system under the same conditions. The DTA date show that the additives La H3 and Nd H2.5, which is remarkably reduced the the onset dehydrogenation temperature of the Li BH4-Mg2 Ni H4 system. La H3 and Nd H2.5 dramatically improve the hydrogen storage properties of the LiBH₄/Mg₂NiH₄ system. This is because in the composite material, and the hydrogenation reaction La H3 and Nd H2.5 of Li BH4 / Mg2 Ni H4 system has good catalytic effect, while promoting the nanometer Mg floc generated in the subsequent hydrogen absorption/desorption cycles that morphology of Mg exhibit good hydrogen storage properties.Compared with La H3 and Nd H2.5, and YH3 and Nb H not only happened hydrogen absorption/desorption effect, also participated in the LiBH₄/Mg₂NiH₄ system of hydrogen absorption/desorption reaction, withdrawing LiBH₄/Mg₂NiH₄ system hydrogen absorption/desorption process catalyze. YH3 and Nb H significantly improve hydrogen storage properties LiBH₄/Mg₂NiH₄ system, but also reduces the thermal stabilityLiBH₄/Mg₂NiH₄ system, 4Li BH4 + 5Mg2 Ni H4 + 20 wt.% TMH（TMH = YH3 and Nb H）composite hydrogen desorption the temperature was reduced by 67 K and 27 K.