Yuanlin Yan, Shikang Jiang, Lingfei Zhao, Hanlin Wang, Jiajia An, Jiarun Geng, Ye Qing Li, Hao Zhu, Pan Xiong, Junwu Zhu, Qinfen Gu, Guoxiu Wang, Ruohan Yu, Limin Zhou, Hui Xia, M. Z. Q. Chen
Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 is a potential cathode for sodium-ion batteries. However, its low electronic conductivity and insufficient Na + diffusion kinetics severely hinder practical application. Herein, this study proposes a lattice confinement-coupled local bond anchoring strategy, where the profound overlap between the vacant t 2g (d 0 ) orbitals of Ti 4+ and O 2p orbitals within the confined space enhances π-bond coupling hybridization. This enables rapid electron delocalization through the Ti–O–Fe network and intrinsically improves the electrical conductivity. Simultaneously, rigid [TiO 6 ] units anchor the lattice strain, confining it to microscopic regions and suppressing destructive macroscopic deformation. As a result, the Na 3.90 Fe 2.95 Ti 0.05 (PO 4 ) 2 P 2 O 7 retained 86.2% of its capacity after 2000 cycles at 10 C. Furthermore, at −40 °C, it delivers a reversible capacity of 90.43 mAh·g –1 at 0.5 C (vs 91.88% of room temperature). This demonstrates that the lattice-confinement-based design paradigm successfully unlocks the immense potential of sodium-ion batteries.