Tailoring the Kinetic Behavior of Hydride Forming Materials for Hydrogen Storage

Hydride forming materials, i.e., binary, complex hydrides, and their mixtures, have been extensively investigated owing to their potential hydrogen storage properties. They possess high volumetric hydrogen capacity and relative high gravimetric hydrogen capacity. However, one of the main constraints for their practical application is their slow kinetic behavior. For this reason, enormous effort has been devoted to improve the hydrogenation and dehydrogenation rates. Several strategies have been developed for the enhancement of the kinetic behavior of the most relevant hydride forming materials such as MgH2, MBH4 (M = Li, Ca, Mg, Na, K), MNH2 (M = Li and Mg), MBH4 + ‘MH2 (M = Li, Ca, Mg; ‘M = Li, Mg, Ca), and MNH2 + ‘MH2 (M = Li, Mg; ‘M = Li). Tuning the kinetic behavior of these hydride forming materials involves different approaches and their combinations. The most relevant approaches are: (1) improving the microstructural refinement via mechanical milling, (2) doping with transition metal and transition metal compounds, (3) forming in situ catalyst, and (4) nanoconfining doped hydride forming materials. Herein, basic concepts about the chemical reaction for the hydride compound formation/decomposition, thermodynamics, kinetics, and applied strategies to enhance the kinetic behavior of hydride compounds and systems are comprehensively described and discussed.