Electroconvective flow in presence of polyethylene glycol oligomer additives

TL;DR

This study investigates how polyethylene glycol oligomer additives influence electroconvective flow during metal electrodeposition, showing that they delay and suppress hydrodynamic instabilities, which could improve battery stability.

Contribution

It provides experimental evidence that oligomer additives can stabilize electrochemical interfaces by suppressing electroconvection, highlighting the importance of polymer-interface interactions.

Findings

Electroconvection is delayed and suppressed by oligomers.

Polymer effects at the interface are crucial for stabilization.

Additives improve uniformity of ion flux during deposition.

Abstract

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. Here, we experimentally investigate how oligomer additives interact with the hydrodynamic instability at a cation selective interface. From electrochemical measurements and direct visualization experiments, we find 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.