Effect of selected dopants on conductivity and moisture stability of Li3PS4 sulfide solid electrolyte: a first-principles study

• Published in: Materials today chemistry 2022-06, Vol.24, p.100837, Article 100837
• Main Authors: Nikodimos, Y., Su, W.-N., Bezabh, H.K., Tsai, M.-C., Yang, C.-C., Hwang, B.J.
• Format: Article
• Language: English
• Subjects: Ab initio molecular dynamics (AIMD); Computational screening; Density functional theory (DFT); Ionic conductivity; Moisture sensitivity
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2022.100837

The first principle computational screening was performed to investigate the effect of selected dopants for Li3PS4 sulfide solid electrolyte on its ionic conductivity and stability toward moisture. The results suggest that substitution P5+ using isovalent cations whose electronegativity (EN) value is closer to the value of S has more significant effects on the ionic conductivity, whereby W5+ and Sb5+ can improve most. Similarly, aliovalent cation substitutions with compensating changes in the lithium-ion concentration, particularly those with a lower oxidation state and higher EN, such as Cu2+, effectively enhance the lithium-ion conductivity in this structure. For cation dopants, it is found that ionic conductivity improvement of Li3PS4 is the synergetic effect of EN and oxidation number of the dopant as well as the material's lattice parameter change. Oxides of the considered cation dopants can also improve the ionic conductivity of the material but have much lower lithium-ion conductivity than the cases of cation dopants. However, the metal oxide dopants, particularly those derived from soft Lewis' acid cations, show a marginal improvement in moisture stability of the Li3PS4 electrolyte. The effect of halides and metal halide dopants on the lithium-ion conductivity and moisture stability of Li3PS4 electrolyte are also studied. It is found that metal halides are more effective than any other dopants in improving the ionic conductivity of Li3PS4. [Display omitted] •First principles are used to study the effect of dopants on ionic conductivity of Li3PS4.•The dopants' effect in stabilizing its moisture instability is also investigated.•Cation and metal halide dopants improve the ionic conductivity of Li3PS4 significantly.•Metal oxide is the most effective in improving moisture instability of Li3PS4.•Soft cations improve of its ionic conductivity and moisture instability simultaneously.