Roles of Slab-Gliding-Induced Surface Nano-Steps in High-Voltage Instability of LiCoO 2

-blocking layer, ultimately causing a rapid capacity decay. We further demonstrate that even if a rock-salt (RS) phase forms electrochemically in situ (e-RS) on the LCO surface, it fails to suppress the lattice-O loss due to the emergence of surface nanosteps. In contrast, a prefabricated RS layer (p-RS) with enhanced mechanical robustness effectively inhibits the formation of such nanosteps, thereby intrinsically suppressing lattice-O loss during cycling. This work identifies slab-gliding-induced surface nanosteps as a key structural trigger for lattice-O loss and demonstrates that prefabricated RS coatings offer an effective route to stabilize high-voltage LCO cathodes.