Figure 12.
Structural characterization and electrochemical performance analysis of NaFePO4/C composite as a cathode in SIBs. (a) SEM images of the Na3V2(PO4)2F3@C (NVPF/C) composites exhibiting bead like morphology. (b) TEM image showing the morphology demonstrating the “worm-like” mesoporous structure. (c) XRD pattern of NVPF sample with the core-double shell structure (NVPF@Cd) in comparison with the NVPF sample with just simple carbon coating (NVPF@C), demonstrating the characteristic peaks. (d) FFT image of the NVPF@Cd sample clearly demonstrating the carbon coating in the nanocomposite. (e–h) Elemental maps of the NVPF@Cd composite depicting the constituent elements uniformly distributed. (j) Schematic representation of the synthesis of the NVPF@Cd nanocomposite from its precursors. (k) Galvanostatic charging-discharging curves of the half-cell with NVPF/Cd cathode for various cycles. (l) Rate performance demonstration of the nanocomposite electrode showing its performance at varying C rates. (m) Capacity retention of the NVPF@Cd composite and its corresponding coulombic efficiency. Copyright 2016, American Chemical Society.