Li₈P₂S₉ solid electrolyte with high ionic conductivity and air stability by Bi₂Se₃ co-doping

Excellent ionic conductivity and electronic insulation are core properties of solid electrolytes. In this study, we use high-energy ball milling and high-temperature sintering heat treatment to prepare a solid electrolyte, and its ionic conductivity (1.57 x 10(-4) S & sdot;cm(-1)) is comparable with that of Li8P2S9 in the glass-ceramic state. On this basis, we modify the prepared LPS solid-state electrolyte through Bi2Se3 doping. First-principles computations based on density functional theory (DFT) indicate that Bi2Se3 doping can broaden lithium-ion transport channels and increase the lithium-ion conduction rate. With a doping ratio of 4 %, the ion conductivity reaches 3.02 x 10(-3) S & sdot;cm(-1), which offers good insulation to electrons and a stable -0.5 to 5 V (vs. Li/Li+) high-voltage platform. Additionally, Bi2Se3 doping significantly improved the air stability of the LPS solid electrolyte, reducing its adsorption energy to water and preventing the replacement of S by O from H2O.