(668d) Stabilizing Electroconvection in Viscoelastic Media

Electrodeposition is widely used to create coatings of metals and other materials on conductive substrates. The process also plays an important role in rechargeable batteries that utilize metals as anodes, where it must be carefully managed to facilitate stable and safe operations at low operating temperatures, high rates, and over many cycles of charge and discharge. In all currently used electrolytes, deposition is subject to three types of instabilities: chemical, morphological, and hydrodynamic at both low and high current densities, which lead to complex transport phenomena in the electrolyte and unstable deposition, including formation of ramified structures known as dendrites. This talk will discuss results from experimental studies designed to investigate the stability of electrodeposition in viscoelastic liquid electrolytes. A goal of the study is to develop novel electrolytes, in which viscoelastic flow effects can stabilize electrodeposition at both low and high current densities. The electrolytes studied span the range from viscoelastic liquids to jammed polymer tethered particles to understand how different visoelastic media impact the electrodeposition. A variety of methods were used to study these impacts, including in-situ studies of electrodeposition of lithium along with analyses of overlimiting conductance that is thought to arise from an hydrodynamic instability dubbed Electroosmotic Flow of the second kind [1]. Recent work has shown that polymer solutions yield different deposit morphologies and impact the flow field near the electrode [2]. Improvements to the techniques are being developed to grow upon this work and understand it at a more fundamental level. The results of this progress have shown the viscoelastic systems do have a significant reduction in the overlimiting conductance and therefore impact the hydrodynamic instabilities in the electrolyte. This work can enable further studies in systems such as gel and solid polymer electrolytes to have a full understanding of how polymer electrolytes can impact electroconvective flows and the resulting deposition of metals.

[1] Rubinstein, Isaak, and Boris Zaltzman. "Electro-osmotically induced convection at a permselective membrane." Physical Review E 62.2 (2000): 2238.

[2] Wei, S., Cheng, Z., Nath, P., Tikekar, M. D., Li, G., & Archer, L. A. (2018). Stabilizing electrochemical interfaces in viscoelastic liquid electrolytes. Science Advances, 4(3).