Quan Lu, Tongyin Shen, Chunlin Li, Yujin Wei, Yu Zhou, Mingru Su, Panpan Zhang, Chenteng Sun, Jianchun Wu, Fei Wang, Leyi Zhang, Qianqiu Tian, Yunjian Liu, Renheng Wang
Achieving both long-term stability and superior rate capability in Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 (NFPP) cathodes remains a major challenge for sodium-ion batteries. Herein, we demonstrate a synergistic bond-defect strategy that circumvents this trade-off. The complementary interaction between Zn and F establishes a synergistic bond-defect environment. The strong bonding of Zn 2+ mitigates the charge localization associated with F – doping. Furthermore, the strategy narrows the electronic bandgap to near-metallic values and enhances the degree of graphitization in carbon coatings, resulting in a marked improvement in electronic conductivity. The optimized Na 3.95 Fe 2.95 Zn 0.05 (PO 4 ) 2 P 2 O 6.95 F 0.05 (NFZPPF) exhibits outstanding cycling stability with 76.25% retention after 16,000 cycles at 20 C and remarkable rate performance, delivering 68.6 mAh g –1 at 50 C. Coupled with a hard carbon anode, the full cell retains 88.8% capacity after 200 cycles at 2 C, underscoring its viability for practical sodium-ion storage.