High ionic conductivity of multivalent cation doped Li 6 PS 5 Cl solid electrolytes synthesized by mechanical milling.

The performances of next generation all-solid-state batteries might be improved by using multi-valent cation doped Li 6 PS 5 Cl solid electrolytes. This study provided solid electrolytes at room temperature using planetary ball milling without heat treatment. Li 6 PS 5 Cl was doped with a variety of multivalent cations, where an electrolyte comprising 98% Li 6 PS 5 Cl with 2% YCl 3 doping exhibited an ionic conductivity (13 mS cm -1 ) five times higher than pure Li 6 PS 5 Cl (2.6 mS cm -1 ) at 50 °C. However, this difference in ionic conductivity at room temperature was slight. No peak shifts were observed, including in the synchrotron XRD measurements, and the electron diffraction patterns of the nano-crystallites ( ca. 10-30 nm) detected using TEM exhibited neither peak shifts nor new peaks. The doping element remained at the grain boundary, likely lowering the grain boundary resistance. These results are expected to offer insights for the development of other lithium-ion conductors for use in all-solid-state batteries.