First Principles Insight into Antiperovskite c-Na3HS Solid State Electrolyte

TL;DR

This study uses first-principles calculations to evaluate c-Na3HS as a stable, high-conductivity solid-state electrolyte for sodium-ion batteries, showing promising stability and ionic transport properties.

Contribution

It provides the first detailed theoretical analysis of c-Na3HS's stability and ionic conductivity, highlighting its potential as a sodium-ion battery electrolyte.

Findings

c-Na3HS is dynamically, thermally, and mechanically stable.

Ionic conductivity can be increased by vacancy and halogen doping.

Activation energy for Na ion migration is around 300 meV, reduced to 100 meV with vacancies.

Abstract

We explore the potential of novel antiperovskite c-Na3HS to be a solid-state electrolyte for sodium-ion batteries. To investigate the dynamical stability, phase stability, thermal stability, mechanical stability and ionic, electronic and diffusive properties of c-Na3HS, the first-principles methods based on density functional theory (DFT) and ab-initio molecular dynamics (AIMD) simulations have been employed. c-Na3HS has no imaginary phonon modes indicating its dynamical stability. Key findings include small energy-above-hull, the wide band gap of 4.35 eV and mechanical stability analysis that indicates the moderately hard and a little brittle nature of c-Na3HS. The activation energy of Na in c-Na3HS is calculated to be ~300 meV that reduces to ~ 100 meV on introducing Na-vacancy. The ionic conductivity can be enhanced up to ~3 order of magnitude by vacancy and halogen doping in c-Na3HS structure. Thus, the obtained results indicate that c-Na3HS can be viable option to be utilized as solid-state electrolyte in sodium-ion batteries.