Surface Lattice Modulation Enables Stable Cycling of High-Loading All-solid-state Batteries at High Voltages

Halide solid electrolytes, known for their high ionic conductivity at room temperature and good oxidative stability, face notable challenges in all-solid-state Li-ion batteries (ASSBs), especially with unstable cathode/solid electrolyte (SE) interface and increasing interfacial resistance during cycling. In this work, we have developed an Al3+-doped, cation-disordered epitaxial nanolayer on the LiCoO2 surface by reacting it with an artificially constructed AlPO4 nanoshell; this lithium-deficient layer featuring a rock-salt-like phase effectively suppresses oxidative decomposition of Li3InCl6 electrolyte and stabilizes the cathode/SE interface at 4.5 V. The ASSBs with the halide electrolyte Li3InCl6 and a high-loading LiCoO2 cathode demonstrated high discharge capacity and long cycling life from 3 to 4.5 V. Our findings emphasize the importance of specialized cathode surface modification in preventing SE degradation and achieving stable cycling of halide-based ASSBs at high voltages. We have demonstrated a surface-lattice-doping (SLD) strategy for the stabilization of the solid electrolyte/cathode interface for its working at a high voltage of 4.5 V. Specifically, a uniform AlPO4 coating layer was built with nanometer precision around the LiCoO2 (LCO) particle. The following sintering at high temperature induced a homogeneous Al3+ diffusion into the LCO crust, leading to a controlled degree of surface Al/Co/Li disorder together with the formed Li+-conductive Li3PO4 islands decorating the LCO surface. We found that this SLD strategy is capable of not only suppressing the structural degradation of LCO itself, but also effectively mitigating the decomposition of the chloride-based solid electrolyte at the interface, thereby ensuring the assembled all-solid-state batteries with the halide electrolyte Li3InCl6 and a LiCoO2 cathode excellent cycling stability at 4.5 V. image