Manganese octahedral point-constructed oxygen defects realize highly stable lithium-rich cathode materials

Lithium-rich layered oxides (LLOs) are highly favored by researchers for their high specific capacity and low cost. However, the severe voltage and capacity degradation of the material have become the biggest obstacle to commercial application. In this work, the construction of oxygen vacancies on the surface of Li-rich cathode and SiO44- gradient doping have been used in Li-rich materials to improve its performance. The presence of oxygen defects in MnO6 octahedra stabilizes its structure and enhances the electrochemical activity of TM ions. This also serves to reduce the energy level and intensity of the unhybridized O 2p orbitals, as well as decrease the release of lattice oxygen. The "localization effect" of SiO44− on TM ions also inhibits their irreversible migration. After modification, the electrochemical performance of the material has been significantly improved. The initial Coulombic efficiency increased to 89.46 % (82.68 % for LLO), while the specific capacity discharge at 5C reached 178.8 mAh g−1 (139.2 mAh g−1 for LLO). Additionally, the capacity rate after 500 cycles at 1C was 74.1 % (54.5 % for LLO). Therefore, this work provides valuable insights for designing oxygen-deficient lithium-rich cathode materials.