Improved electrochemical performance of Na3V2(PO4)3 modified by N-doped carbon coating and Zr doping

Na3V2-xZrx(PO4)(3)/CN composites (x = 0, 0.01, 0.02 and 0.03) were designed and synthesized by a low cost solid-state route, and their crystal structure, morphology and electrochemical properties were comparatively studied in detail. The results reveal that minute amount of Zr4+ doping did not change the basic structure of Na3V2(PO4)(3) and Zr-doped Na3V2-xZrx(PO4)(3)/CN samples exhibit obvious improved electrochemical performance due to their higher electrical conductivity and smaller charge transfer resistance compared with undoped sample. Among the Zr-doped Na3V2(PO4)(3)/CN samples, Na3V1.98Zr0.02(PO4)(3)/CN composite possesses the best rate capability and cycle property. It delivers the specific discharge capacities of 115, 102 and 97 mAh g(-1) at 0.2, 10 and 20 C, respectively, and at a high rate of 20 C, 97.3% of its initial value is kept after 1000 cycles.