Figure 3.

a) Gray scale XY slice (horizontal cross section) from a tomogram captured before discharge; the red square indicates the region of interest with which the neighboring image is associated. b) Enlarged view of the XY slice showing pristine electrode before discharge. c) Gray scale XY slice from a tomogram captured after discharge; the red square indicates the region of interest with which the neighboring image is associated. d) Enlarged view of the XY slice showing electrode after discharge. Inset: Section of the current collecting mesh showing a 3D view of the crack openings. Movies S1 and S2 (Supporting Information) show the evolution of the slices in the XY and ZX plane in real time.