Climate change motivates the search for non-carbon-emitting energy generation and storage solutions. Metal hydrides show promising characteristics for this purpose. Using systematic ab initio and atomistic simulations, we explore the potential of the abundant defects in the materials such as grain boundaries, dislocations, and microcracks for enhancing the thermodynamics and kinetics of Al-based hydride formation.

Firstly, we consider tailoring and employing the negative pressure of microstructural and structural defects to enhance H solubility and thus hydride formation as a novel concept. Using the ab initio thermodynamics method, we created the negative pressure-dependent phase diagram of Alane hydride AlH3 in the gas pressure and temperature domain. We demonstrate that such an enhancement at the negatively pressurized crack tip region is feasible by increasing the mechanical tensile load on the specimen. The theoretical predictions have been used to reassess and interpret atom probe tomography experiments for a high-strength 7XXX-aluminium alloy that shows a substantial enhancement of hydrogen concentration at structural defects near a stress-corrosion crack tip.

Secondly, using the ab initio simulations we studied the effect of grain boundaries on the stability and kinetics of hydride formation in Al-based alloys. We calculate the concentration-dependent segregation energies of H to various grain boundaries such as $\Sigma$3, $\Sigma$9, $\Sigma$5, and $\Sigma$11 that are proven to have elevated H concentration. We explore the potential of these grain boundaries for enhancing the formation of hydrides by acting as nucleation sites and reducing the critical chemical potential for their formation through the results of these calculations. Based on these insights we derive strategies for exploiting metals as H-storage materials.