Fabrication of Na_0.67Li_0.05Ni_0.28Mn_0.67O₂ 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 Na0.67Li0.05Ni0.28Mn0.67O2 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 Na0.67Li0.05Ni0.28Mn0.67O2 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 Na0.67Li0.05Ni0.28Mn0.67O2 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.