Figure 2. 3D view and quantitative analysis of surface curvature evolution in NIB.

(a) Evolution of the two principal curvatures, convex and concave, during the first electrochemical cycle. (b) Schematic illustration (colour) showing surface curvature change, and the corresponding real cross-section images (grey) of selected particle shown below. The discharge/charge profile is presented as the background. (c) 3D view of surface curvedness evolution during the first electrochemical cycle. The curvedness is calculated on the two principal curvatures, convex and concave feature. See Supplementary Information for details. Scale bar, 10 μm.