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Summary: A nitrogen‐doped carbon coated subglobose Na3V2(PO4)2F3@C (NVPF) cathode for sodium‐ion batteries was synthesized by using hexadecyl trimethyl ammonium bromide (CTAB) as soft template and polyvinylidene fluoride (PVDF) as carbon source. CTAB plays a significant role on the formation of sphere micelles. Precursor ions are self‐assembled on the surface at appropriate concentration and its mechanism is investigated in subglobose NVPF@C‐4. CTAB also increases the conductivity of carbon layer as −(CH3)3N+ in CTAB is combined with residual carbon from PVDF to form partially N‐doped carbon. Meanwhile, the carbon source PVDF contributes to prevent the generation of impurity Na3V2(PO4)3 by compensating the evaporative fluorine. Generally, CTAB and PVDF play multifunctional roles in regulating Na3V2(PO4)2F3@C cathode with well‐developed crystallite, high rate performance, good conductivity, and ultra‐long cycle life. The specific capacity of NVPF@C‐4 cathode at 0.1 C and 10 C is as high as 121.5 mAh·g−1 and 99.2 mAh·g−1 with high capacity retention of 90.1% even after 1000 cycles at 10 C. The excellent rate performance is also attributed to the high diffusion coefficient of Na+ and high exchange current according to the kinetic analysis. The enhanced electrochemical performances reveal the special regulation in this paper is feasible to obtain excellent structural stability of NVPF materials. [ABSTRACT FROM AUTHOR]

• High performance N -doped Na 3 V 2 (PO 4) 2 F 3 /C is constructed by a PECVD technology. • Pyridinic, pyrrolic and graphitic nitrogen are generated at high energy condition. • The formation of defects on the carbon can accelerate the diffusion of sodium ions. • NVPF@N-3 delivers excellent rate, cyclic performance and structural stability. • The capacity retention of cathode NVPF@N-3 is 91.4% at 10 c after 1000 cycles. One N -doped carbon coated Na 3 V 2 (PO 4) 2 F 3 /C cathode for sodium-ion batteries was successfully prepared by a Plasma enhanced chemical vapor deposition (PECVD) method. N 2 gas is used as the nitrogen source and it is ionized to form chemically active nitrogen ion. It can easily react with the carbon atoms in sample Na 3 V 2 (PO 4) 2 F 3 /C. Research results show that the introduction of N does not affect the crystal structure of the material. The N -doped carbon layer in sample Na 3 V 2 (PO 4) 2 F 3 /C becomes more and more homogeneous. The formation of the pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen in the carbon layer can generate additional active sites to shorten the transmission distance of sodium ions, which can improve the electrochemical performance of Na 3 V 2 (PO 4) 2 F 3 /C cathode. The NVPF@N-3 cathode treated by PECVD for 30 min displays excellent rate performance (109.8 mAh•g−1 at 5 C) and cyclic performance, in which the capacity retention after 1000 cycles at 10 C is 91.4% and the crystal structure of NVPF@N-3 is well maintained. This research demonstrates that the pyrolytic carbon in Na 3 V 2 (PO 4) 2 F 3 /C cathode for sodium-ion batteries can be effectively doped by Nitrogen through a novel PECVD technology. [Display omitted] [ABSTRACT FROM AUTHOR]