Boosting the Performance of Na ₄ MnV(PO ₄ ) ₃ Cathode Through Nitrogen‐Doped Carbon Coating for Sodium‐Ion Batteries

NASICON‐type Na 4 MnV(PO 4 ) 3 (NMVP) has attracted considerable attention for its open 3D framework and high theoretical capacity. However, the material suffers from relatively poor electronic conductivity, which limits its rate capability. Additionally, during charge and discharge process, the Jahn‐Teller effect of Mn 3+ can trigger lattice distortion, resulting in inferior cycling stability. In this study, nitrogen (N) was doped into the carbon layer of Na 4 MnV(PO 4 ) 3 via a sol‐gel method to synthesize a series of Na 4 MnV(PO 4 ) 3 ‐PVP X materials (x = 0, 0.01, 0.02, and 0.03). Among the series, NMVP/C‐PVP 0.02 exhibited outstanding performance, delivering a discharge capacity of 107.8 mAh g −1 at 0.2C and retaining 87.8% of its capacity after 100 cycles. Moreover, it maintained 71% of its initial capacity even after 1,500 cycles at 5C. Furthermore, a full cell assembled with a hard carbon anode (HC//NMVP/C‐PVP 0.02 ) achieved a discharge capacity of 84.5 mAh g −1 at 5C. This work presents a promising strategy for advancing the commercialization of polyanion‐type cathode materials. The nitrogen‐doped carbon coating effectively enhances the structural stability of NMVP and facilitates the rapid (de)intercalation of sodium ions, thereby improving its overall electrochemical performance.