Tailoring Local Electronic Configuration of Na ₄ Fe ₃ (PO ₄ ) ₂ P ₂ O ₇ Cathode via Reductive Coupling Mechanism toward Ultra‐Wide Temperature Sodium‐Ion Batteries

Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 (NFPP) has emerged as the most promising candidate for cathode materials in sodium‐ion batteries (SIBs). However, its application is still limited by the inherent low electronic conductivity and insufficient structural stability at extreme temperatures. Herein, we innovatively propose a novel strategy for precisely regulating the local electronic configuration based on the reductive coupling mechanism (RCM), which significantly enhances the reversibility and charge transfer kinetics of the Fe 2+ /Fe 3+ redox reaction. By introducing high electronegativity transition metal ions (TM n+ , Ni 2 + /Co 2 + ) into the NFPP lattice (NFNCPP), the O 2p‐TM 3d orbital hybridization is successfully induced, effectively reducing the band gap and strengthening the Fe─O bonding, thereby simultaneously enhancing the Na + diffusion kinetics and the thermodynamic stability of the lattice. Therefore, the advanced NFNCPP cathodes exhibit ultra‐long cycle life (over 36 000 cycles) and wide‐temperature adaptability (from −50 C to 60°C). Remarkably, the NFNCPP||hard carbon (HC) full cells demonstrate stable cycling performance at −20°C and 60°C. This work establishes a transformative pathway toward advanced SIB cathodes featuring ultra‐long cycle life and robust wide‐temperature‐range stability.