A deep insight into electronic and ionic transport properties of solid-state sodium electrolyte Na3SbSe4

Low electronic and high-ionic conductivities are indispensable for viable solid-state electrolytes (SSEs), which are key components of all-solid-state batteries. Here, we provide a deep atomistic insight into electronic and ionic transport properties of antimony-based sodium selenide Na3SbSe4 as a promising SSE for sodium-ion batteries, using highly accurate first-principles calculations and molecular dynamics (MD) simulations. Our calculations of phonon dispersions within the self-consistent phonon theory and elastic constants confirm dynamical and mechanical stabilities with ductility favorable for a good contact with electrodes. We determine bandgap of 1.8 eV by applying the GW method and calculate electronic conductivities considering the phonon, deformation, and impurity scatterings, revealing that Na3SbSe4 behaves as insulator at low carrier concentration and low temperature while semiconductor otherwise. Furthermore, we perform MD simulations with machine learning interatomic potential, demonstrating high Na ionic conductivity of 1.57 mS/cm at room temperature with a low activation energy of 0.19 eV.