Influence of carbon polymorphism towards improved sodium storage properties of Na3V2O2x (PO4)(2)F3-2x

Abstract

The effects of 10 wt.% super P carbon, multiwalled carbon nanotubes (MWCNTs), and reduced graphene oxide (rGO) on particles size and electrochemical properties of Na3V2O2x (PO4)(2)F3-2x cathode material were studied. Among these three carbon polymorphs, using MWCNT in composite is effective to obtain low particle size and enhanced electrochemical properties of Na3V2O2x (PO4)(2)F3-2x . While using rGO to make the composite, the particle size becomes quite big, leading a smaller surface contact area with the electrolytes and thereby resulting in poor cyclability. Na3V2O2x (PO4)(2)F3-2x -MWCNT composite shows a high capacity of 98 mAh g(-1)at 0.1 C rate for 100 cycles, and further, it exhibits a stable capacity of 89 mAh g(-1) at 0.2 C rate vs. NaTi2(PO4)(3)-MWCNT in full cell configuration.