Cobalt-induced charge redistribution and lattice distortion enable accelerated sodium storage kinetics in NASICON-type Na3V2(PO4)3

Cation substitution provides an effective route to regulate electrochemical kinetics in NASICON-type cathodes, yet the interplay between electronic structure and ion transport remains insufficiently clarified. Here, cobalt substitution is introduced into Na 3 V 2 (PO 4 ) 3 to simultaneously tailor electronic states and sodium diffusion pathways. The incorporation of Co 2+ may induce local structural perturbation within the NASICON framework, leading to enhanced metal‑oxygen covalency and a continuous distribution of electronic states near the Fermi level. This modification promotes charge-transfer kinetics. Concurrently, the induced lattice distortion lowers the Na + migration energy barrier from 0.36 to 0.21 eV, enabling faster ion transport. The optimized Na 3 V 1.88 Co 0.12 (PO 4 ) 3 exhibits a discharge capacity of 96.04 mAh g −1 at 2C (1C = 117 mAh g −1 ) and maintains 91.34% of its capacity after 1000 cycles. A practical NVCP-15||hard carbon full cell demonstrates promising sodium-ion storage performance, achieving an initial discharge capacity of 73.58 mAh g −1 , stable cycling with 78.7% capacity retention after 300 cycles at 1C, and robust rate capability with 41.2 mAh g −1 retained at 5C. This study establishes a coupling mechanism between lattice distortion, electronic reconstruction, and ion transport, providing a design strategy for high-performance NASICON cathodes.