Structural, dynamic, and diffusion properties of a Li6(PS4)SCl superionic conductor from molecular dynamics simulations; prediction of a dramatically improved conductor. Issue 30 (21st July 2022)

• Record Type: Journal Article
• Authors: Das, Tridip; Merinov, Boris V.; Yang, Moon Young; Goddard III, William A.
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 30(2022)
• Page Start: 16319
• Page End: 16327
• Publication Date: 2022-07-21
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2ta02715a
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Li6 (PS4 )SCl superionic conductor – solid electrolyte for next generation batteries. Abstract : Li-Superionic-conducting materials are considered the most desirable solid electrolytes to enhance fast battery charging/discharging. Extensive experimental and computational studies have been reported on various Li-ion electrolytes but the detailed mechanism of long-range ion transport in solid state superionic conductors has not been elucidated. We report here the results of molecular dynamics simulations with applied electric fields to explain both cationic and anionic diffusion mechanisms leading to Li-superionic conductivity in Li6 (PS4 )SCl. We find that Li migration in this material occurs via a conjugated substitutional type diffusion involving rearrangements of three or more Li ions in a 3D matrix of the anions that are essentially stationary for temperatures below 350 K. In this mechanism the presence of an equal number of filled and empty sites plays an important role. The predicted Li-ion conductivity of 7.2 × 10 −3 S cm −1 for single phase Li6 (PS4 )SCl at 298 K agrees well with recent room temperature NMR and impedance measurements, 3.9 × 10 −3 S cm −1 and 7.1 × 10 −3 S cm −1, respectively. The calculated activation energy of 0.24 eV is comparable to 0.27–0.29 eV obtained from NMR. We predict that Li5 (PS4 )Cl2 will have a conductivity over 10 times higher than that of Li6 (PS4 )SCl, making it the best superionic conductor.