Degradation Evolution for Li ZrCl Electrolytes in Humid Air and Enhanced Air Stability via Effective Indium Substitution.

Superionic halides have aroused interests in field of solid electrolytes such as Li ZrCl . However, they are still facing challenges including poor air stability which lacks in-depth investigation. Here, moisture instability of Li ZrCl is demonstrated and decomposition mechanism in air is clearly revealed. Li ZrCl decomposes into Li ZrO , ZrOCl ·xH O and LiCl during initial stage as halides upon moisture exposure. Later, these side products evolve into LiCl(H O) and Li Zr O after longer time exposure. More importantly, structure of destroyed halides cannot be recovered after postheating. Later, Indium is doped into Li ZrCl (9.7 × 10 S cm ) to explore its effect on structure and properties. Crystal structure of ball-milled In-doped Li ZrCl electrolytes is converted from the Li YCl -like to Li InCl -like with increasing In content and ionic conductivity can also be enhanced (0.768-1.13) × 10 S cm ). More importantly, good air stability of optimal Li Zr In Cl is achieved since halide hydrates are formed after air exposure instead of total decomposition and the hydrates can be restored to Li Zr In Cl after postheating. Moreover, reheated Li Zr In Cl after air exposure is successfully applied in solid-state LiNi Co Mn O /halides/Li PS Cl/Li-In battery. The results in this work can provide insights into air instability of Li ZrCl and effective strategy to regulate air stability of halides.