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

The high-voltage induced undesirable surface passivation bilayer (cathode/electrolyte interface and cation-densified surface phase) of LiCoO₂ inevitably leads to battery degradation. Herein, a continual/uniform enamel-like olivine layer on LiCoO₂ 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 LiCoO₂ and enamel-like layer restrains both lattice oxygen loss and associated layered-to-spinel structural distortion. Moreover, the thermal stability of highly delithiated LiCoO₂ is improved, as both the onset temperatures of layered-to-spinel transition and O₂ evolution are simultaneously postponed. Stable operation of LiCoO₂ 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.