LiGaOS is a fast Li-Ion conductor: A first-principles prediction

Solid Li-ion conducting electrolytes are highly sought for all solid-state Li-batteries, which are considered the next-generation safe batteries. Here a systematic computational study on the intrinsic transport properties of lithium gallium oxysulfide, LiGaOS (S. G. Pmc21), as a potential solid-state Li-ion electrolyte have been reported. The phonon dispersion spectrum analysis indicates that LiGaOS crystal structure is dynamically stable. The energy band structure and density of states calculations suggest that LiGaOS is an insulator with a wide indirect band gap of ∼5.44 eV. The CI-NEB calculations reveal that the “kick-off” collective migration via Li-interstitials is the dominant conduction mechanism for Li-transport, with an extremely low energy barrier of 0.05 eV. The corresponding Li-ion self-diffusion coefficient estimated by transition state theory is in the order of magnitude of 10−3 cm2/s at room temperature, with the dominant charge carrier being Li-interstitial. Overall, the presented first-principles calculations suggest that LiGaOS is a promising solid Li-ion electrolyte for future all-solid-state lithium batteries. [Display omitted] •The structural stability and Li-ion diffusion in the LiGaOS crystal were studied by first-principles calculations.•LiGaOS has wide electrochemical window of 5.44 eV and high ionic conductivity of 10-3 cm2/s at room temperature.•The “kick-off” collective migration is dominant mechanism, the interstitial Li direct migration is a secondary mechanism.