Fig. 3: Electron density evolution of the Co–O and O–O interactions.

a Structural model of LiCoO₂ with the indexed (\(01\bar{4}\)) plane near the [100] direction (top). CoO₄ (\(01\bar{4}\)) plane of the CoO₆ octahedra (bottom). b–e Static deformation density maps of the (\(01\bar{4}\)) CoO₄ plane and corresponding three-dimensional (3D) views of b LiCoO₂, c Li_0.6CoO₂, d Li_0.4CoO₂, and e Li_0.3CoO₂. The electron density is present in different colors with the color scale shown on the left. The red color region means the electron density accumulation, and the blue color region represents the electron density depletion. All of the maps use a contour interval of 0.1 e Å⁻³, with positive, negative, and zero contours drawn as solid black, dashed black, and solid olive-green lines, respectively. The 3D renderings of the deformation density maps for the CoO₆ octahedra are viewed in the same direction as the top model in panel a. The 3D version in panel e can be observed more clearly in Supplementary Fig. 7. The inclined arrows show the [001] direction, and all of the 3D views use the same color scheme. For clarity, the map was plotted by a homemade program, in which a translucency factor (the alpha component in the ARGB color scheme) is used to remove most of the white background.