Elucidating the Impact of Li 3 InCl 6 -Coated LiNi 0.8 Co 0.15 Al 0.05 O 2 on the Electro-Chemo-Mechanics of Li 6 PS 5 Cl-Based Solid-State Batteries.

Li 6 PS 5 Cl has attracted significant attention due to its high Li-ion conductivity and processability, facilitating large-scale solid-state battery applications. However, when paired with high-voltage cathodes, it experiences adverse side reactions. Li 3 InCl 6 (LIC), known for its higher stability at high voltages and moderate Li-ion conductivity, is considered a catholyte to address the limitations of Li 6 PS 5 Cl. To extend the stability of Li 6 PS 5 Cl toward LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA), we applied nanocrystalline LIC as a 180 nm-thick protective coating in a core-shell-like fashion (LIC@NCA) via mechanofusion. Solid-state batteries with LIC@NCA allow an initial discharge specific capacity of 148 mA h/g at 0.1C and 80% capacity retention for 200 cycles at 0.2C with a cutoff voltage of 4.2 V (vs Li/Li + ), while cells without LIC coating suffers from low initial discharge capacity and poor retention. Using a wide spectrum of advanced characterization techniques, such as operando XRD, XPS, FIB-SEM, and TOF-SIMS, we reveal that the superior performance of solid-state batteries employing LIC@NCA is related to the suppression of detrimental interfacial reactions of NCA with Li 6 PS 5 Cl, delamination, and particle cracking compared to uncoated NCA.