Diffusion Mechanism of the Sodium-Ion Solid Electrolyte Na₃PS₄ and Potential Improvements of Halogen Doping

Diffusion Mechanism of the Sodium-Ion Solid Electrolyte Na₃PS₄ and Potential Improvements of Halogen Doping

de Klerk, N.J.J. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Wagemaker, M. (TU Delft RST/Fundamental Aspects of Materials and Energy)

2016-05-10

Density functional theory (DFT) molecular dynamics (MD)-simulations were performed on cubic and tetragonal Na₃PS₄. The MD simulations show that the Na-conductivity based on the predicted self-diffusion is high in both the cubic and tetragonal phases. Higher Na-ion conductivity in Na₃PS₄ can be obtained by introducing Na-ion vacancies. Just 2% vacancies result in a conductivity of 0.2 S/cm, which is an order of magnitude larger than the calculated conductivity of the stoichiometric compound. MD simulations of halogen-doped cubic Na₃PS₄ suggest a practical route to introduce vacancies, where Br-doping is predicted to result in the highest bulk conductivity. Detailed investigation of the Na-ion transitions during the MD simulation reveals the role of vacancies and phonons in the diffusion mechanism. Furthermore, the orders of magnitude difference between the MD simulations and experiments suggest that macroscopic conductivity can be significantly increased by reducing the grain boundary resistance.

http://resolver.tudelft.nl/uuid:600fe2d4-98f8-47f8-a188-b7361ec65f90

https://doi.org/10.1021/acs.chemmater.6b00698

2017-05-10

0897-4756

Chemistry of Materials, 28 (9), 3122-3130

Accepted Author Manuscript

Institutional Repository

journal article

© 2016 N.J.J. de Klerk, M. Wagemaker