Structure modification of magnesium hydride for solid hydrogen storage

Hydrogen has received widespread attention as a clean future energy source. However, the key challenge to enable Hydrogen as an energy vector is its storage. When comparing the various hydrogen storage methodologies, solid hydrogen storage using metal hydrides is quite attractive due to its high Volumatic energy density and high safety. In this review, we summarized the importance and research progress of magnesium (Mg) based hydrides for hydrogen storage, with a focus on porous materials, which are different from previous work. Specifically, we present the hydrogen storage mechanisms by solid materials, particularly metal materials, along with their kinetic and thermodynamic principles. Additionally, synthesis methods of these materials using ball milling, thin film deposition, and direct current plasma technology are systematically classified and described. Performance improvements of Mg-based alloys or composites through catalysis, alloying and nanosizing were screened and concluded. Finally, Porous-structure based improvements for Mg-based materials are emphasized, including Mg porous films, Mg metal-organic frameworks (Mg-MOFs) and Mg-based nanoconfined materials. This paper provides future guidance to enable the improved performance of Mg hydrides in solid hydrogen storage as well as other lightweight metal hydrogen storage materials by structure modification instead of adding rare-earth elements.