Surface Modification of Na₃V₂(PO₄)₃ by Nitrogen and Sulfur Dual-Doped Carbon Layer with Advanced Sodium Storage...

Nitrogen and sulfur dual-doped carbon layer wrapped Na₃V₂(PO₄)₃ nanoparticles (NVP@NSC) have been successfully fabricated by the facile solid-state method. In this hierarchical structure, the Na₃V₂(PO₄)₃ nanoparticles are well dispersed and closely coated by nitrogen and sulfur dual-doped carbon layer, constructing an effective and interconnected conducting network to reduce the internal resistance. Furthermore, the uniform coating layers alleviate the agglomeration of Na₃V₂(PO₄)₃ as well as mitigate the side reaction between electrode and electrolyte. Because of the excellent electron transfer mutually enhancing sodium diffusion for this extraordinary structure, the NVP@NSC composite delivers an impressive discharge capacity of 113.0 mAh g^-1 at 1 C and shows a capacity retention of 82.1% after 5000 cycles at an ultrahigh rate of 50 C, suggesting the remarkable rate capability and long cyclicity. Surprisingly, a reversible capacity of 91.1 mAh g^-1 is maintained after 1000 cycles at 5 C under the elevated temperature of 55 °C. The approach of nitrogen and sulfur dual-doped carbon-coated Na₃V₂(PO₄)₃ provides an effective and promising strategy to enhance the ultrahigh rate and ultralong life property of cathode, which can be used for large-scale commercial production in sodium ion batteries.