Figure 3: Basic physics of shock electrodeposition.
From: Dendrite Suppression by Shock Electrodeposition in Charged Porous Media

(a) Dendritic instability of electrodeposition in free solution upon diffusion limitation in the electrolyte, where the scarce supply of cations focuses onto a protrusion and results in a self-amplifying process. (b) Stability of deionization shock propagation in response to over-limiting current in a leaky membrane, where a lagging part of the shock wave is removed by large Ohmic currents through the depleted region and results a flat, stable shock wave. (c) Stabilization of electrodeposition behind a deionization shock, if the second effect overcomes the first during fast growth at over-limiting current.