Fig. 1: Structural characterizations and Na+ transfer investigation of as-synthesized heterostructured NFS-H. | Nature Communications

Fig. 1: Structural characterizations and Na+ transfer investigation of as-synthesized heterostructured NFS-H.

From: Bridging multiscale interfaces for developing ionically conductive high-voltage iron sulfate-containing sodium-based battery positive electrodes

Fig. 1

a Schematic illustration of the heterostructure. The blue and red areas represent Na2.26Fe1.87(SO4)3 and Na6Fe(SO4)4 in positive material, respectively. The white and black arrows represent sodium-ion transport in Na2.26Fe1.87(SO4)3 and Na6Fe(SO4)4, respectively. And the blue and red arrows represent the characteristics of Na2.26Fe1.87(SO4)3 (higher working voltage) and Na6Fe(SO4)4 (faster ionic diffusion), respectively. b Synchrotron high-pressure powder X-ray diffraction Rietveld refinement, which was carried out on NFS-H powder (inset: SEM image. The color of light blue was obtained via additional manipulation in the original SEM image for better color contrast). c, d The Na+ migration channels (blue-green isosurface) revealed by BVSE calculation for Na2.26Fe1.87(SO4)3 and Na6Fe(SO4)4 crystals, respectively. e Na+ migration barriers along different directions. f Energy profiles of path Na2–Na2 along 1D direction.

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