Lattice‐Matched Interfacial Modulation Based on Olivine Enamel‐Like Front‐Face Fabrication for High‐Voltage LiCoO2

Abstract The high‐voltage induced undesirable surface passivation bilayer (cathode/electrolyte interface and cation‐densified surface phase) of LiCoO 2 inevitably leads to battery degradation. Herein, a continual/uniform enamel‐like olivine layer on LiCoO 2 surface is fabricated by employing a high‐speed mechanical fusion method . The enamel‐like layer suppresses interfacial side reactions by tuning EC dehydrogenation, contributing to an ultrathin and stable cathode/electrolyte interface. The strong bonding affinity between LiCoO 2 and enamel‐like layer restrains both lattice oxygen loss and associated layered‐to‐spinel structural distortion. Moreover, the thermal stability of highly delithiated LiCoO 2 is improved, as both the onset temperatures of layered‐to‐spinel transition and O 2 evolution are simultaneously postponed. Stable operation of LiCoO 2 at 4.6 V high‐voltage and 55 °C elevated temperature (both >85% capacity retention after 200 cycles) is achieved. This facile and scalable high‐speed solid‐phase coating strategy establishes a technical paradigm to enhance surface/interface stability of high‐energy‐density cathode candidates by constructing an ideal enamel‐like surface layer.