Novel Mg-Ni fibers for hydrogen storage at moderate temperatures

This study reports a breakthrough achievement in the fabrication of Mg-Ni-Ag hydrogen storage fibers (with a diameter of 30∼50 μm) via melt extraction technology. By regulating the annealing process of the metallic glass precursor, in-situ and homogeneous dispersion of Mg₂Ni nanoparticles within the matrix is successfully achieved. These nanostructured fibers exhibit superior hydrogen storage performance compared to conventional high-energy ball-milled materials. The optimized fibers demonstrate hydrogen absorption capability at 40 °C and achieve complete dehydrogenation within 5.2 min at 275 °C under 0.1 MPa pressure. This enhanced performance is attributed to a significant reduction in dehydrogenation activation energy to 99.4 kJ/mol, achieved through microstructural engineering. Detailed analysis of microstructural evolution during hydrogen cycling reveals that the progressive refinement of Mg₂Ni particles during cycling increases specific surface area, thereby enhancing hydrogen dissociation efficiency and atomic hydrogen flux. The synergistic effects from lattice stress fields and interfacial dynamics accelerate both hydrogen absorption and desorption kinetics. This structural design strategy, combining nano-refinement effects with stress modulation, provides new insights for developing advanced metal hydride systems with optimized thermodynamic and kinetic properties.