Pushing Lithium Cobalt Oxides to 4.7 V by Lattice‐Matched Interfacial Engineering

Abstract The utilization of high‐voltage LiCoO 2 is imperative to break the bottleneck of the practical energy density of lithium‐ion batteries. However, LiCoO 2 suffers from severe structural and interfacial degradation at > 4.55 V. Herein, a novel lattice‐matched LiCoPO 4 coating is rationally designed for LiCoO 2 which works at 4.6 V (vs Li/Li + ) or above. This LiCoPO 4 coating, derived by an in situ chemical reaction, grows epitaxially on LiCoO 2 crystallite with strong bonding and complete coverage to LiCoO 2 , ensuring a stable cathode–electrolyte interface with fewer side reactions and alleviated intergranular cracking and phase collapse during repeated high‐voltage lithiation/delithiation processes. In addition, the formed strong covalent P–O tetrahedron configuration at the interface effectively decreases the surface oxygen activity of LiCoO 2 , further suppressing oxygen release and irreversible phase transition. Therefore, the LiCoPO 4 ‐LiCoO 2 ǁLi cells display excellent capacity retention of 87% after 300 cycles at 4.6 V and stable operation at 4.6 V/55 ° C or 4.7 V/30 ° C. The strategy of lattice‐matching growth affords a new way to impact the development of high‐voltage LiCoO 2 and beyond.