Synergistic Regulation of Charge and Ion Transport in Mn‐Rich NASICON Cathodes Toward High‐Energy Sodium‐Ion Batteries

Manganese‐based sodium superionic conductor (NASICON)‐type cathodes offer a cost‐effective route to high‐energy‐density sodium‐ion batteries but suffer from severe kinetic and stability limitations due to cooperative Jahn–Teller distortion and prevalent Mn/Na anti‐site defects. Here, we propose a dual‐regulation strategy that synchronously optimizes charge transfer and ion transport through the concerted incorporation of redox activators V/Cr and a structural expander Zr. The resulting Na 3.55 Mn 1.2 Ti 0.6 V 0.1 Cr 0.05 Zr 0.05 (PO 4 ) 3 (NM 1.2 TVCZP) cathode delivers a high average operating voltage (∼3.64 V), a considerable capacity (110.0 mAh g −1 at 0.1C), remarkable rate capability (73.5 mAh g −1 at 5.0C), and stable long‐term cycling (81.44% capacity retention after 200 cycles at 1.0C). Structural and electrochemical analyses reveal that V/Cr doping activates the Mn 2+ /Mn 3+ /Mn 4+ redox couples and suppresses anti‐site defects, while Zr expands the lattice and restrains long‐range Jahn–Teller distortion. This synergy enables fast Na + diffusion and highly reversible phase evolution, yielding minimal voltage hysteresis and enhanced structural reversibility. The NM 1.2 TVCZP || hard carbon (HC) full cell achieves a high energy density of 384.2 Wh kg −1 . Our work establishes a holistic materials‐design paradigm that unifies multi‐electron redox activity with rapid ion transport and structural integrity, offering a practical and scalable pathway to high‐performance, Mn‐based NASICON cathodes for sodium‐ion batteries.