Atomistic investigation of phase stability and sodium ion conduction in sulfide electrolytes.

Author

Sabina Zakhidovna ChertmanovaFollow

Date on Master's Thesis/Doctoral Dissertation

12-2021

Document Type

Master's Thesis

Degree Name

M.S.

Department

Mechanical Engineering

Degree Program

Mechanical Engineering, MS

Committee Chair

Narayanan, Badri

Committee Member

Wang, Hui

Committee Member

Sumanasekera, Gamini U.

Author's Keywords

solid state battery; solid state electrolytes; solid electrolytes; NSS; sodium ion electrolytes; sodium sulfide electrolytes

Abstract

In this thesis, we employ a combination of density functional theory (DFT) calculations, and ab initio molecular dynamics (AIMD) simulations to identify the effect of chemical doping on (a) thermodynamic phase stability, and (b) Na-ion conduction in Na₃SbS₄ (NSS) solid-state electrolytes. We found that (a) Se doped electrolytes, namely, Na₃SbS_exS_4-x undergo a tetragonal-to-cubic structural phase transition at x > 3 (Se-rich), and (b) the size, valence, and electronegativity of chemical dopants that substitute Na in Na₃SbS₄ have a cumulative profound impact on Na-ion conductivity. Specifically, substituting Na with higher valence dopant (e.g., In3+) that are similar in size to Na can result in substantial improvement in Na-ion conduction (~2-2.5 times that in undoped case) owing to the increased Na-vacancy concentration in the doped electrolytes. AIMD trajectories also elucidate the effect of dopant on the atomic-scale pathways underlying Na-conduction.

Recommended Citation

Chertmanova, Sabina Zakhidovna, "Atomistic investigation of phase stability and sodium ion conduction in sulfide electrolytes." (2021). Electronic Theses and Dissertations. Paper 3798.
https://doi.org/10.18297/etd/3798