Insights on the Properties of the O-Doped Argyrodite Sulfide Solid Electrolytes (LiPSClO =0-1).

Argyrodite sulfide solid electrolytes, such as LiPSCl (LPSC), have received much attention due to their high ionic conductivity (>1 mS cm) and success in all-solid-state batteries (long cycle performance, high energy density, etc.). Numerous efforts are spent on modifying the properties of the electrolyte itself. Here, we combine first-principles calculations with experiments to investigate O-doped argyrodite sulfide solid electrolytes (LiPSClO = 0-1). It is found that LiPSClO (LPSCO) with = 0.25 and cubic phase (4̅3 ) shows the highest ion conductivity of 4.7 mS cm (cold-pressed), higher than that of undoped LiPSCl (4.2 mS cm). The bare LiCoO/LPSCO/Li-In all-solid-state battery exhibits an initial capacity of 131 mA h g at 0.1 C and satisfactory cycling stability with 86% capacity retention after 250 cycles to the 4th cycle at 0.3 C under 25 °C. In addition, the NCM811/LPSCO/Li-In cell is assembled using bare LiNiCoMnO cathode and shows an initial discharge capacity of 181 mA h g at 0.1 C and 160 mA h g at 0.3 C. The doping of oxygen-forming LiPSClO also improves the stability to Li metal, proven by cyclic voltammetry and powder X-ray diffraction tests. The calculation results for the band structure reveals that LPSC has the lowest unoccupied molecular orbital than LPSCO, further confirming the above conclusion.