Electroconvection in the Presence of PEG Oligomer Additives

Metal electrodeposition in batteries is fundamentally unstable and affected by different instabilities depending on operating conditions and chemical composition. Particularly at high charging rates, a hydrodynamic instability called electroconvection sets in that aggravates the situation by creating non-uniform ion flux and preferential deposition at the electrode. In this talk, I will discuss our experimental work focusing on how PEG oligomer additives interact with electroconvective flow at a cation selective interface. By combining electrochemical characterization techniques and direct visualization experiments, we found that electroconvection is delayed and suppressed at all voltage in the presence of oligomers. Our results also reveal that it is important to consider the role of polymers at the interface, in addition to their bulk effects, to understand the stabilization effect and its mechanism. To this end, I will also discuss a theoretical polymer layer model we developed to corroborate our experimental results and explore the possible physics behind the increased stability and its eventual saturation.