Interplay between metal deposition and electroconvection on a charge selective electrode*

We investigate an unknown coupling effect between dendrite growth and electroconvective instability (EC), which arises from electrokinetic instability at the electrolyte-electrode interface. To achieve this, we design an in situ Operando microscopy platform that visualizes ion concentration, fluid flow, and dendrite growth at the electrode-electrolyte (Zn-ZnSO4) interface. Based on the order of occurrence between EC and dendrite formations, we identified five distinct dynamic regimes: (i) inert regime where neither EC nor dendrites occur, (ii) EC regime exhibiting only EC, (iii) EC-dendrite regime where dendrites form at current hotspots induced by EC, (iv) EC/dendrite regime where the both EC and dendrites simultaneously occur, and (v) dendrite regime where only dendrite forms. By incorporating the Damkohler number (ion reduction reaction vs. self-diffusion on the electrode), electric Rayleigh number, and the second Damkohler number (ion diffusion from the electrolyte vs. ion reduction reaction on the electrode), we diversify the five dynamic regimes. Our study sheds light on the interplay between EC and dendrite formation, providing valuable insights for devising novel strategies to control dendrite growth.