Fig. 3: Charge distributions in the first charged state.

a 3D Ni valence state distribution, b representative region of the 3D Ni valence state distribution, and c 2D nanodomain valence gradient of the rod-NMC. d 3D Ni valence state distribution, e representative region of the 3D Ni valence state distribution, and f 2D nanodomain valence gradient of the gravel-NMC. The nanodomain valence gradient vectors are represented by the black arrows, where the vector direction and magnitude are represented by the arrow direction and arrow length, respectively. The scale bars in (a) and (d) are 3 μm, and the scale bars in (b–c) and (e–f) are 1 μm. The Ni K-edge absorption energies are color-coded, in which blue stands for lower edge energy and red means higher edge energy.