fig3

Figure 3. (A) Schematic illustration of structure of FeF₂ with Fe (red) and F (green). In the 3D view (left), the unit cell is outlined by thick blue lines. The thin black lines outline a 1 × 2 × 2 supercell. Alternative arrangement of Fe-F along the [001] direction in the unit cell is shown in the red and green planes. (B) Li (yellow) insertion along the [001] direction. (C) Expansion/contraction of Fe/LiF along different directions. (D) Perspective view of checkerboard arrangement of the converted Fe domains along the [001] FeF₂ direction. Reproduced from Ref.^[9] with permission. Copyright 2018 American Chemical Society.