Synergistic La/F Co-Doping for Enhanced Lattice Oxygen Stability and Long-Term Cycling Stability in High-Capacity Li-Rich Layered Cathodes

Lithium-rich layered oxides (LLOs) constitute promising cathode candidates for next-generation Li-ion batteries, since their high reversible capacities arise from the combined contribution of transition-metal cations and lattice oxygen redox. However, their practical application is hampered by structural degradation arising from metastable anionic redox. Herein, a synergistic La/F co-doping strategy is reported by us so that the structural and electrochemical stability of LLOs can be enhanced. The complementary effects of La and F co-doping modification and their influence on crystal structure, elemental distribution, and electrochemical performance are systematically investigated. We demonstrate that La/F co-doping stabilizes the oxygen lattice framework, suppresses transition-metal migration into lithium layers, and promotes long-range structural ordering. Mechanistically, La3+ doping enlarges the lattice spacing to facilitate Li+ diffusion, while F− substitution strengthens metal–fluorine bonds, reinforcing the anionic framework and suppressing irreversible oxygen release. As a result, the La/F co-doped material (LMCNOLF) exhibits markedly improved initial Coulombic efficiency, superior rate capability, and excellent long-term cycling stability. Moreover, it retains 89% of its initial capacity after 300 cycles and outperforms both the La-doped and undoped counterparts. Kinetic analysis reveals that LMCNOLF maintains lower charge-transfer impedance and higher Li+ diffusion coefficients. This work elucidates the mechanism of La/F synergistic doping in stabilizing lattice oxygen and suppressing structural degradation, offering a rational design route for high-performance Li-rich layered cathodes.