(Invited) Mesoscale Modeling of Solid-State Hydrogen Storage Mechanisms

Abstract

Metal hydrides have been considered as a promising class of solid-state hydrogen storage materials owing to their excellent volumetric and gravimetric storage densities, which can overcome critical technological limits of the currently available high-pressure hydrogen gas storage approach. Solid-state hydrogen storage mechanisms involve the complicated coupling of chemical/physical processes over vast ranges of multiple length and time scales. These include surface reactions with hydrogen gas; surface/bulk/interface mass transport processes; structural modifications occurring under operation; and intermediate phase nucleation-and-growth processes associated with hydrogen incorporation. Essentially, these are collective dynamic processes of atomic/molecular species that determine the thermodynamics and kinetics of nano- or micro-level characteristics. The mesoscale continuum modeling framework can provide a unified platform for integrating the necessary atomistic approaches, which typically provide higher accuracy for nanoscale chemical processes, and continuum approaches, which offer far greater flexibility and scalability and can describe materials at the microstructural level. In this presentation, we demonstrate our integrated effort as part of the DOE Hydrogen Storage Materials—Advanced Research Consortium(HyMARC) under the Energy Materials Network(EMN) towards the multiscale modeling of hydrogen storage mechanisms in metal hydrides for hydrogen storage. Specifically, we will report our recent efforts on the development of an integrated mesoscale modeling framework that can directly incorporate parameters derived from predictive atomistic modeling approaches such as ab initiocalculations and molecular dynamics simulations. Representative case studies will be presented, including beyond-ideal thermodynamic modeling of complex hydrides, effective mass transport/mechanical response modeling for complex hydride microstructures, and phase-field modeling of reaction-induced phase transformations of simple or complex metal hydrides during the (re/de)hydrogenation.