Effect of alkali-metal substitution on hydrogen storage properties of NaMgH3 hydride perovskites: DFT insights
Journal
International Journal of Hydrogen Energy
Journal Volume
257
Start Page
156487
ISSN
0360-3199
Date Issued
2026-08-05
Author(s)
Guji, Kefyalew Wagari
Geleta, Tesfaye Abebe
Shongwe, Mxolisi Brendon
Kanyane, Lehlogonolo Rudolf
Malatji, Nicholus
Abstract
First-principles density functional theory (DFT) calculations investigate the effects of Li and K substitution and hydrogen-site occupancy on the structural, electronic, mechanical, and hydrogen-storage properties of NaMgH3 hydride perovskites examining both edge-centered and face-centered hydrogen configurations. Li substitution induces lattice contraction and strengthens Mg–H interactions, increasing gravimetric hydrogen capacity to 7.15 wt% (Li0.5Na0.5MgH3) and 7.90 wt% (Li0.75Na0.25MgH3), while K substitution expands the lattice, weakens hydrogen binding, and facilitates hydrogen release. Electronic-structure calculations, confirmed at the HSE06 level, reveal metallic behavior for edge-centered configurations and semiconducting behavior for face-centered configurations, which are more thermodynamically stable. Mechanical properties remain stable but increasingly brittle behavior after substitution, and ab initio molecular dynamics (AIMD) confirm dynamic stability at 300, 500, and 700 K. Overall, Li0.5Na0.5MgH3 offers the most practical balance of capacity and desorption temperature, whereas Li0.75Na0.25MgH3's higher capacity is offset by a desorption temperature (139.6 K) too low for ambient-condition hydrogen retention. © 2026 Hydrogen Energy Publications LLC.
Subjects
Alkali-metal doping
First-principles calculations
Hydrogen storage materials
NaMgH3hydrides
Structural and electronic properties
Publisher
Elsevier BV
Type
journal article