Tuning microstructures of Mg-Ce-Ni hydrogen storage alloys via Cu and carbon nanotube additions

Mg-based alloys are regarded as highly promising materials for hydrogen storage. Despite significant improvements of the properties for Mg-based alloys, challenges such as slow hydrogen absorption/desorption kinetics and high thermodynamic stability continue to limit their practical application. In this study, to assess hydrogen storage alloys with enhanced properties, incorporating both internal microstructure modulation through the preparation of amorphous/nanocrystalline structures and surface property enhancement with the addition of Cu and carbon nanotubes (CNTs), the kinetic properties of activation and hydrogenation, thermodynamic properties, and dehydrogenation kinetics are tested. The results reveal a complementary interaction between the added Cu and CNTs, contributing to the superior hydrogen storage performance observed in sample 7A-2Cu-1CNTs with an amorphous/nanocrystalline structure compared to the other experimental samples. Additionally, the samples are fully activated after the initial hydrogen absorption and desorption cycle, demonstrating outstanding hydrogenation kinetics under both high and low temperature experimental conditions. Particularly noteworthy is that the hydrogen absorption exceeds 1.8 wt.% within one hour at 333 K. Furthermore, the activation energy for dehydrogenation is decreased to 64.71 kJ·mol^–1. This research may offer novel insights for the design of new-type Mg-based hydrogen storage alloys, which possess milder conditions for hydrogen absorption and desorption.