High performance Na₃V₂(PO₄)₃ cathode prepared by a facile solution evaporation method for sodium-ion batteries

Based on its abundance and low cost, sodium based batteries have aroused extensive attention for large scale energy-storage systems. In the current work, Na₃V₂(PO₄)₃ prepared by a facile solution evaporation method (denoted as NVP-SE) is used as cathode materials for sodium ion battery, with a control sample by solid state method. Raman spectrum and TEM are used to study the carbon layer coated on NVP-SE. The results show a highly graphitization and well-coated carbon layer, which is predominant by sp² carbon. Graphitized carbon leads to high electrical conductivity, which can improve the rate performance of Na₃V₂(PO₄)₃ materials. Besides, GITT tests show high Na-ion diffusion coefficient. Even at 30 C, the NVP-SE cathode still delivers a capacity of 70 mAh g⁻¹. Moreover, the material also shows great long term cycling performance. After 500 cycles at 1 C rate and 1000 cycles at 5 C, its discharge capacities are still 103.3 mAh g⁻¹ and 85.4 mAh g⁻¹, which maintain 92.6% and 85.0% of its initial capacity. Thus, simple preparation process and excellent electrochemical performance for Na₃V₂(PO₄)₃/C extend it as a potential material for high power applications.