(1. College of Chemistry and Chemical Engineering,Yantai University, Yantai 264005, China)(2. Hubei Institute of Aerospace Chemotechnology,Xiangyang 441003, China)
The efficient and safe storage and transport of hydrogen are bottleneck issues that necessitate a solution for the implementation of hydrogen as a sustainable clean energy resource. Magnesium is abundant in the earth’s crust, and its hydride (MgH2) has a hydrogen content of 7.6%, which is the highest among the binary metal hydrides that can reversibly store hydrogen. With a volumetric hydrogen capacity (110 kg/m3) higher than liquid hydrogen, MgH2 is regarded as a promising solid hydrogen storage medium. However, the high operation temperature due to its stable thermodynamics (enthalpy of formation is -75 kJ/mol) limits its practical application for PEM fuel cell. In order to improve the hydrogen sorption performance of MgH2, intensive research activities have been undertaken worldwide in the past decades and significant improvements have been achieved. In particular, hydrogen storage properties of MgH2 close to the practical requirement have been attained by the size-effect through nanostructuring. This paper introduces the physical characteristics of magnesium-based hydrogen storage materials, principles and achievements for the improvement of hydrogen sorption kinetics and thermodynamics, as well as remaining issues. Prospects for further improvement of sorption performance have been discussed.