Mitigating the Cooperative Distortion and Phase Transition of P′2 Phase to Prepare Stable Fast‐Charghing Layered Cathode

ABSTRACT

Sodium‐ion batteries are promising for large‐scale energy storage systems, but simultaneously achieving high capacity, super‐fast charging, and long‐term cycling remains challenging. Here, we report a P′2‐type layered oxide cathode Na _0.67 Fe _0.2 Mn _0.8 O ₂ @Oxygen‐Free derived from conventional P2‐type Na _0.67 Fe _0.2 Mn _0.8 O ₂ via oxygen‐free re‐sintering treatment, and further introduce trace Cu/Ti into the transition metal layer to obtain Na _0.67 Fe _0.2 Mn _0.76 Cu _0.02 Ti _0.02 O ₂ . The co‐doping strategy alleviates phase transition and enhances structural stability. As a result, FMOF‐CT delivers a high reversible capacity of 197.76 mAh g ^{− 1} at 0.2C and retains 99.35% of its initial capacity after 100 cycles at an ultra‐high rate of 20C. Combined in situ characterization methods reveal that the superior kinetic performance originates from faster Na ⁺ diffusion, smoother P′2–P2–OP4 phase evolution, and mitigated interlayer slip. Subsequently, neutron powder diffraction is performed to reveal the structure‐activity relationship. This work demonstrates an effective structural design for achieving super‐fast charging and stable cycling in layered oxide cathodes for sodium‐ion batteries.