Optimizing hydrogen ad/desorption of Mg-based hydrides for energy-storage applications

Abstract

• The typical structures and hydrogen storage mechanism of MgH 2 are briefly introduced. • The research progress of Mg-based hydrides is discussed systematically. • The outlook and remaining challenges upon Mg-based hydrides are delivered in detail. Hydrogen energy is expected to be an “ideal fuel” in the era of decarbonization. The discovery, development, and modification of high-performance hydrogen storage materials are the keys to the future development of solid-state hydrogen storage and hydrogen energy utilization. Magnesium hydride (MgH 2 ), with its high hydrogen storage capacity, abundant natural reserves, and environmental friendliness, has been extensively researched. Herein, we briefly summarize the typical structure and hydrogenation/dehydrogenation reaction mechanism of MgH 2 and provide a comprehensive overview of strategies to effectively tune the thermodynamics and kinetics of Mg-based materials, such as alloying, nanosizing, the introduction of additives, and composite modification. With substantial efforts, great achievements have been achieved, such as lower absorption/desorption temperatures and better cycling stability. Nonetheless, some pivotal issues remain to be addressed, such as unfavorable hydrogenation/dehydrogenation factors, harsh conditions, slow kinetics, incomplete dehydrogenation, low hydrogen purity, expensive catalysts, and a lack of valid exploration of mechanisms in the hydrogenation/dehydrogenation process. Lastly, some future development prospects of MgH 2 in energy-efficient conversion and storage have been presented, including advanced manufacturing ways, stabilization of nanostructures, the introduction of additives combined with structural modification, and utilization of advanced characterization techniques.