Figure 11.

The structural characterization and electrochemical performance analysis of NaFePO₄/C composite as a cathode in SIBs. (a) SEM images of the NaFePO₄/C composites demonstrating a rather smooth spherical morphology. (b) TEM image showing the morphology of the microsphere composite in greater detail. (c) XRD pattern of LiFePO₄ powder precursor, the delithiated FePO₄ sample and the NaFePO₄ sample demonstrating the characteristic peaks. (d–h) Elemental maps of the microsphere composite exhibiting the constituent elements and a rather uniform distribution. (j) Schematic representation of the electrochemical displacement reaction that results in the formation of NaFePO₄ from LiFePO₄. (k) Galvanostatic charging-discharging curves of the half-cell with NaFePO₄/C cathode at various rates. (l) CV of the NaFePO₄/C cathode system vs. Na/Na⁺ showing the characteristic redox peaks. (m) Capacity retention of the PB composite cathode for both the charge and discharge cycles. Copyright 2015, American Chemical Society.