High Ionic Conductivity with Improved Lithium Stability of CaS- and CaI 2 -Doped Li 7 P 3 S 11 Solid Electrolytes Synthesized by Liquid-Phase Synthesis.

Li 7 P 3 S 11 solid electrolytes (SEs) subjected to liquid-phase synthesis with CaS or CaI 2 doping were investigated in terms of their ionic conductivity and stability toward lithium anodes. No peak shifts were observed in the XRD patterns of CaS- or CaI 2 -doped Li 7 P 3 S 11 , indicating that the doping element remained at the grain boundary. CaS- or CaI 2 -doped Li 7 P 3 S 11 showed no internal short circuit, and the cycling continued, indicating that not only CaI 2 including I - but also CaS could help increase the lithium stability. These results provide insights for the development of sulfide SEs for use in all-solid-state batteries in terms of their ionic conductivity and stability toward lithium anodes.