Multi-hierarchical nanosheet-assembled chrysanthemum-structured Na3V2(PO4)3/C as electrode materials for high-performance sodium-ion batteries
The structure and morphology of sodium vanadium phosphate (Na3V2(PO4)3) play a vital role in enhancing the electrochemical performance of sodium-ion batteries due to the inherent poor electronic conductivity of the phosphate framework. In order to improve this drawback, a new chrysanthemum-structured (Na3V2(PO4)3/C material has been successfully assembled with multi-hierarchical nanosheets via a hydrothermal method. Continuous scattering nanosheets in chrysanthemum petals are beneficial in reducing energy consumption during the process of sodium ion diffusion, on which the carbon-coated surface can significantly increase overall conductivity. The as-prepared sample exhibits outstanding electrochemical performance due to its unique structure. It rendered a high initial specific capacity of 117.4 mAh g−1 at a current density of 0.05 C. Further increasing the current density to 10 C, the initial specific capacity still achieves 101.3 mAh g−1 and remains at 87.5 mAh g−1 after 1000 cycles. In addition, a symmetrical sodium-ion full battery using the chrysanthemum-structured Na3V2(PO4)3/C materials as both the cathode and anode has been successfully fabricated, delivering the capacity of 62 mAh g−1 at 1 C and achieving the coulombic efficiency at an average of 96.4% within 100 cycles. These results indicate that the new chrysanthemum-structured (Na3V2(PO4)3/C can provide a new idea for the development of high-performance sodium-ion batteries.