Effect of ball-milling time on hydrogen storage properties of NdMg12-Ni alloy

In this study, the NdMg12-Ni alloy was synthesized through a ball milling process, and a comprehensive analysis of the mechanisms by which ball milling duration affects the thermodynamic and kinetic properties of hydrogen absorption and desorption was systematically explored. The experimental findings reveal that the ball milling process is capable of inducing a modest quantity of the Mg2Ni phase on the surface of the NdMg12-Ni alloy. As the ball milling duration is prolonged, the concentration of nanocrystals within the NdMg12-Ni alloy initially increases, followed by a subsequent decline. Specifically, upon reaching a ball milling duration of 6h, the primary structure of the NdMg12-Ni alloy manifests itself in a nanocrystalline phase, intertwined with a small presence of amorphous components. In terms of thermodynamic properties, the hydrogen absorption enthalpy Delta H ab of sample NdMg12-Ni+6h reaches its minimum, recording a mere 74.6109 kJ/mol. With regard to kinetic features, the NdMg12-Ni+6h sample displayed exceptional hydrogen absorption kinetics across the temperature range of 330 degrees C-350 degrees C, accomplishing 95% of its saturated hydrogen storage capacity in just 180s. Furthermore, as ball milling time increased from 0 to 8 h, the hydrogen desorption activation energy of NdMg12-Ni alloy experienced a significant decline from 236.3334 kJ/mol to 115.2953 kJ/mol, and the optimal hydrogen desorption temperature was also effectively reduced.