Balancing thermodynamics, kinetics, and reversibility in Ti-doped Mg(BH4)2: A first-principles assessment of a practical solid-state hydrogen storage material
Comprehensive investigation reveals improved thermodynamics and kinetics in Ti-doped Mg(BH4)2, suggesting practical hydrogen storage solutions.
Key Points
This work aims to evaluate the potential of Ti-doped Mg(BH4)2 as a solid-state hydrogen storage material by assessing its thermodynamic and kinetic properties.
Conducted first-principles calculations using density functional theory
Analyzed structural and electronic properties of pristine and Ti-doped Mg(BH4)2
Performed phonon and elastic stability analyses
Utilized nudged elastic band calculations for hydrogen migration barriers
Conducted van't Hoff analysis for temperature-related behavior.
Pristine Mg(BH4)2 exhibits a gravimetric hydrogen capacity of about 14.9 wt% but has a desorption enthalpy of around 42 kJ mol−1 H2.
Ti doping improves hydrogen capacity to approximately 10.4 wt% and reduces desorption enthalpy to about 36 kJ mol−1 H2.
Hydrogen diffusion barriers decrease from approximately 0.52 eV to about 0.38 eV with Ti substitution.
Phonon and elastic stability analyses confirm the dynamic and mechanical stability of the Ti-doped material.
Localized Ti-3d states near the Fermi level enhance hydrogen mobility and a van't Hoff analysis indicates possible ambient temperature hydrogen release.