Hybrid heterojunction containing rich oxygen vacancies for suppressing lattice oxygen release of Li-rich Mn-based layered oxides cathodes

Li-rich manganese-based layered oxides (LLOs) cathode materials possess the high theoretical capacity (>250 mAh g^-1), which have garnered significant global attention as promising cathode materials for the next generation of high-energy density lithium-ion batteries. However, the irreversible release of lattice oxygen in LLOs severely limits its commercial application. Herein, a facile ultrasonic-assisted calcination method is employed to induce the formation of hybrid heterojunction containing rich oxygen vacancies (HROV) composed of C₃N₄@LLOs and Li₃PO₄@LLOs on the surface of LLOs, thereby obtaining modified LLOs (M-LLOs). M-LLOs exhibit enhanced initial Coulombic efficiency from 80.18 % to 85.1 %, elevated initial discharge specific capacity from 270.2mAh g^-1 to 311.5 mAh g^-1, and improved capacity retention rate after 300 cycles at 1C from 58.8 % to 84.2 %. Combining in-situ characterization techniques with density functional theory (DFT) calculations reveal the performance improvement mechanism of M-LLOs, which demonstrates that HROV effectively suppresses the irreversible release of lattice oxygen, enhances the binding strength of Mn-O bonds in M-LLOs, and consequently stabilize the structural phase transitions during charge/discharge processes. These results provide insights into understanding the functional role of hybrid heterojunctions in suppressing lattice oxygen release of LLOs, and provide essential theoretical foundations to accelerate the commercialization process of LLOs.