Fabrication of Na0.67Li0.05Ni0.28Mn0.67O2 Cathode with Synergistic Engineering of Li-Doping and Mn-Precursor for High-Performance Sodium-Ion Batteries

P2-type transition-metal oxides as promising cathode materials for sodium-ion batteries (SIBs) possess unique layered structures and superior electrochemical properties, but suffer from the kinetic retardation and structural instability caused by problems such as Na⁺/vacancy ordering, Jahn–Teller distortion, and irreversible P2–O2 phase transition. Herein, we report the fabrication of a P2-type Na_0.67Li_0.05Ni_0.28Mn_0.67O₂ cathode material via a simple solid-state method, using micro-octahedral Mn₂O₃ as Mn-precursor with simultaneous Li-doping. The combined adoptions of micro-octahedral Mn₂O₃ precursors and Li-doping effectively enhance the structural stability of the Na_0.67Li_0.05Ni_0.28Mn_0.67O₂ cathode by inhibiting the Jahn–Teller distortion and suppressing the phase transition of P2–O2 and increase the electronic conductivity and ion diffusion coefficient during charging and discharging processes. Consequently, the as-fabricated Na_0.67Li_0.05Ni_0.28Mn_0.67O₂ cathode demonstrates superior sodium storage performance, delivering a reversible capacity of 144.6 mAh g^–1 at 0.1C with 91.8% capacity retention after 50 cycles and sustaining 82.6% capacity retention after 500 cycles at 5C. This research offers a viable approach for creating high-performance P2-type cathodes for advanced SIBs.