Hydrogen desorption and absorption properties of Pd and MgO or nano-sized Ni-added MgH2 + LiBH4 composites

•Preparation of Pd and MgO or Ni-added MgH2 + LiBH4 composites.•Examination of absorption and desorption properties of composites.•79MgH2 + 15LiBH4 + 1Pd + 5Ni showed the highest desorption rate.•84MgH2 + 15LiBH4 + 1Pd had the highest absorption rate.•Pd is considered to act as a catalyst to reaction of MgH2 + LiBH4 composite.

In order to increase the hydrogen storage capacity of Mg-based materials, LiBH4 with a higher hydrogen storage capacity of 18.4 wt% was added to MgH2. Pd and MgO or nano-sized Ni were added to improve the desorption rate and decrease the desorption temperature of MgH2 and LiBH4 composite. Composite powders with compositions of 69.7 wt% MgH2 + 30.3 wt% LiBH4, 84 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd, 79 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd + 5 wt% MgO, and 79 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd + 5 wt% Ni were prepared by planetary ball milling under hydrogen. The absorption and desorption properties of the samples were then examined. Among these samples, 79 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd + 5 wt% Ni showed the highest desorption rate and the largest released hydrogen quantity, releasing 4.70 wt% H for 50 min, and 5.70 wt% H for 300 min. Among these samples, 84 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd showed the highest absorption rate and the largest absorbed hydrogen quantity, absorbing 5.3 wt% H for about 25 min, and absorbing hydrogen even after 550 min, in particular. 84 wt% MgH2 + 15 wt% LiBH4 + 1 wt% Pd exhibited a relatively high desorption rate.

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