Structural and electrolyte properties of Li4P2S6

•Li4P2S6 is very stable, maintaining its crystal structure up to 950 °C in vacuum and 280 °C in air.•Li4P2S6 can be synthesized at temperatures ranging from 750–900 °C.•The ground state structure is disordered due to multiple arrangements of P2S6 building blocks.•The Arrhenius activation energy for conduction is of 0.29 eV, similar to technologically viable electrolytes.•Simulations show that interstitial sites contribute to the mechanism of ionic conduction.

Experiment and simulations are used to investigate the structural and electrolyte properties of Li4P2S6. Compared with other thiophosphate materials, Li4P2S6 is quite stable, maintaining its crystal structure up to temperatures as high as 950 °C in vacuum and up to 280 °C in air. While its ionic conductivity is small, 2.38 × 10− 7 S/cm at 25 °C and 2.33 × 10− 6 S/cm at 100 °C, its Arrhenius activation energy of 0.29 eV is similar to technologically viable electrolytes. Computer simulations provide insight into the causes and effects of disorder in this material and also indicate that the mechanism of the ion conduction is dominated by interstitial sites.