Fig. 1: Materials characterization.

a XRD Rietveld refinement results of NaMnF (Mn-based Prussian blue) with an inset of the cell structure. b XRD Rietveld refinement results of NaFeMn (Fe-substituted Mn-based Prussian blue) with an inset of the cell structure. In the insets, the orange and blue octahedra represent Mn–N6 and Fe–C6, respectively. The yellow, brown, silvery, and red spheres represent Na, C, N, and O atoms, respectively. c TGA results of NaMnF and NaFeMnF powders. d Raman spectra of NaMnF and NaFeMnF powders. e The tenth charge/discharge profiles of PTCDI||NaFeMnF and PTCDI||NaMnF in 17.6 m NaClO4 at 2 A g−1 at 25 °C. f, g SEM images of NaMnF powder. h, i SEM images of NaFeMnF powder. j, k STEM-mapping images of NaMnF powder. l, m STEM-mapping images of NaFeMnF powder.