High performance Na3V2 (PO4)3/C composite electrode for sodium-ion capacitors

Sodium-ion capacitors were assembled with Na3V2(PO4)(3)/C composite cathode and activated carbon (AC) anode. In this work, Na3V2(PO4)(3) (NVP) and NVP/C have been investigated as electrode materials in sodium ion capacitors for the first time. Electrochemical tests, such as cyclic voltammetry (CV), chronopotentiometry, and cycling were also performed to study the behavior of NVP and NVP/C. The specific capacitance and energy density of NVP/C composite electrode are as high as 51.0 F g(-1) and 15.9 Wh kg(-1). The optimized voltage range of sodium-ion capacitors is from 0 to 1.5 V. NVP/C composite demonstrates that it retained up to 80 % of the initial capacitance after 100 cycles. The outperforming results could be ascribed to the NVP/C composite, which indicates that NVP/C composite is more suitable as cathodematerials for sodium-ion capacitors.