Recent advances in combustion/explosion hazards and suppression strategies for metal hydride hydrogen storage materials

Metal hydride solid-state hydrogen storage materials show strong potential for large-scale hydrogen energy applications because of their high volumetric hydrogen storage density, mild operating conditions, and relatively sound inherent safety. However, combustion and explosion hazards remain during preparation, storage, utilization, and disposal. These hazards mainly arise from hydrogen release during endothermic dehydrogenation, subsequent exothermic combustion of released hydrogen and oxidation of active metal residues, formation of combustible dust clouds, and rapid interaction with air. This review examines the process features and associated combustion and explosion hazards of the primary preparation routes for metal hydrides. It further analyzes the combustion and explosion behavior and multiphase reaction mechanisms of representative metal hydrides, with particular emphasis on how the dehydrogenation-oxidation coupling process intensifies flame propagation and explosion severity. In addition, the review summarizes the suppression mechanisms of inert gases, solid inhibitors, and composite inhibitors, highlighting physical dilution and cooling, free-radical scavenging, and protective film formation. The reviewed evidence indicates that preparation process control and appropriately selected suppression strategies can lessen combustion and explosion hazards and provide practical guidance for the safer engineering deployment of metal hydride hydrogen storage materials.