Atomic‐Level Dual‐Cation Engineering Enables High‐Performance Na4VMn(PO4)3 Cathodes for Sodium‐Ion Batteries

Abstract Na Super Ionic Conductor (NASICON)‐type Na 4 VMn(PO 4 ) 3 (NVMP) is a promising cathode for sodium‐ion batteries (SIBs) but suffers from sluggish Na‐ion transport and capacity fading. Here, we propose a site‐selective dual‐cation engineering strategy in which Li + and K + are respectively introduced into Na2 and Na1 sites to synergistically suppress Jahn‐Teller distortion, reinforce the framework, and expand Na‐ion diffusion channels. Structural characterizations and ex‐situ X‐ray Diffraction (XRD) confirm that the co‐doped materials maintain reversible lattice evolution throughout prolonged cycling. The engineered hierarchical porous architecture further facilitates rapid Na‐ion transport by constructing interconnected ion–electron pathways. Electronic structure analyses demonstrate that dual‐cation doping buffers lattice strain and stabilizes V 3+ /V 4+ redox centers, minimizing polarization and enabling quasi‐single‐phase redox behavior at high rates. The optimized Li 0.08 K 0.02 ‐NVMP exhibits exceptional cycling stability, retaining 95.36% of its capacity after 1,000 cycles at 10 C and 89.35% after 10 000 cycles at 20 C. Remarkably, Li 0.02 K 0.08 ‐NVMP achieves an initial capacity of 158.8 mAh g −1 at 1 C and maintains 132.7 mAh g −1 at 20 C, demonstrating outstanding rate capability and durability. These results establish a generalizable strategy for constructing high‐performance NASICON cathodes via atomic‐level lattice and electronic regulation for advanced sodium‐ion batteries.