Linking the Microstructure of Ball-Milled Mg-Ni Hydrogen Storage Materials to Reactive Properties and Techno-Economic Feasibility.

Solid-state metal hydride hydrogen storage exhibits advantages compared to gaseous or liquid storage, including high volumetric hydrogen storage density and improved safety. However, challenges related to technological and economical scalability, including kinetic and thermodynamic limitations, cyclability, and cost concerns, remain unresolved. In this work, Mg-Ni composites were synthesized by ball milling to identify the effects of milling parameters on performance. The macro- and microstructures of the materials and hydrogen absorption properties were investigated to assess performance for hydrogen storage. Additionally, techno-economic analysis was conducted to evaluate feasibility for practical applications and the relative effects of synthesis conditions on overall cost-effectiveness. The results indicated that variations in milling time and rotational speed modified lattice parameters and particle sizes, which in turn influenced hydrogen absorption behavior. From the techno-economic analysis, a ball milling time of 2 h at 300 rpm speed produced the most cost-effective material in terms of balancing total capacity and electricity costs (0.77 $ per kg H stored).