Predicting hydrogen storage properties of multicomponent metal hydrides: Modeling of pressure, capacity, hysteresis, and slope

Metal hydrides are considered as an important group of materials in the future hydrogen-based economy. Their development is mostly based on time-consuming experimental trial-and-error methods. This work accelerates this pathway using a computational framework for the thermodynamic modeling of metal hydrides under para-equilibrium conditions. By employing the CALPHAD method on a six-component AB5-type (Ce, La)(Ni, Al, Fe, Mn)5-H system, we are able to make precise predictions regarding hydrogen absorption enthalpies, plateau pressures, and hydrogen sorption capacities. Additionally, this is the first time the hydrogenation/dehydroganation hysteresis effect has been successfully modeled using separate thermodynamic databases for hydrogen absorption and desorption. Furthermore, we introduce a method to directly calculate sloped pressure-composition-temperature (PCT) curves from X-ray diffraction data. This validation demonstrates the framework’s capability to assess the hydrogen storage properties of complex multi-component systems in an efficient manner. This work lays the groundwork for future metal hydride thermodynamic studies on a variety of material classes, as well as optimization of alloys for applications even beyond classical hydrogen storage.