Recent Advances in Computational Materials Science Approach for Optimal Design of Hydrogen Storage Alloys

Hydrogen storage alloys play a crucial role in realizing efficient and safe hydrogen-based energy systems. The thermodynamic properties of these alloys are highly sensitive to their composition, and precise control of alloying element types and concentrations enables optimization of plateau pressure, hydrogen storage capacity, and absorption–desorption kinetics tailored to specific operating conditions. However, experimental exploration of the vast compositional space of multicomponent alloys is limited by substantial time and cost, underscoring the growing importance of computational design and prediction methodologies. This review provides a comprehensive overview of systematic composition design strategies for hydrogen storage alloys based on DFT(Density functional theory) calculations and CALPHAD (CALculation of PHAse Diagrams) approaches. The use of DFT to predict hydride formation enthalpies and to evaluate plateau pressure variations is examined, with emphasis on the correlation between theoretical predictions, experimental data, and alloying effects illustrated through representative TiFe-based alloy systems. For the CALPHAD methodology, the principles of Gibbs energy minimization for predicting phase equilibria and PCT(Pressure–composition–temperature) behavior are discussed, including recent advances in modeling para-equilibrium states in metal–hydrogen systems. Particular attention is given to emerging methodologies for quantitatively capturing non-ideal PCT characteristics―such as plateau slope and hysteresis―through the integration of para-equilibrium thermodynamics and microstrain analysis.