Figure 6
Ledge mechanism of lithiation in c-Si. (a–c) HRTEM image sequences showing the lithiation process by lateral ledge flow (marked by colored arrows) in the amorphous/crystalline interface (ACI) and the simultaneous peeling-off of the {111} planes over 5 s. The ACI is 3–4 atomic layers thick, and the atomic layers are distorted and different from both the mottled contrast in the top a-LixSi layer and the regular lattice in the bottom c-Si. (d) Schematic showing the peeling-off of the 
atomic layers by the continuous in-plane ledge flow during lithiation. (e) Lateral displacement of the seven ledges projected to the horizontal [111] direction versus time. Ledges can move faster on the {111} facet and slower on the {112} planes. The ledge flow speed is inversely proportional to the ledge density that gives a constant radial etching rate. Reproduced with permission.54
