Predictive Modeling of Electrodeposition in a Single Pore Flow-Through Electrode: From Electronucleation to Coating Thickness Uniformity

Abstract

The emergence of advanced manufacturing methods capable of producing porous three-dimensional structures has expanded the design space for next-generation functional components. The ability to fabricate ordered 3D foams for use in electrocatalysis reactors has increased the need for controlled deposition of catalytic metals onto porous support materials, such as carbon. However, there is a lack of clear design guidelines for electrodeposition onto 3D substrates, due to the geometric complexity and multi-scale nature of the problem. Furthermore, electro-nucleation phenomena are often overlooked in macro-scale models of current distribution during deposition. Here, a graphite flow-through electrode is used as a model system for copper deposition within a single pore. Potential distributions and electro-nucleation phenomena are coupled in a continuum level model by incorporating nucleation size and density as a function of overpotential, determined experimentally using in-situ atomic force microscopy. The model predictions are validated by measuring the coating uniformity in the pore using micro-computed X-ray tomography. A scaling analysis comprising dimensionless parameters such as the Wagner number is presented. The simplified scaling relationship framework can guide the electrodeposition process and electrode design to optimize plating of porous substrates under fluid flow conditions.

In Situ Determination of the Potential Distribution within a Copper Foam Electrode in a Zinc‐Air/Silver Hybrid Flow Battery

“…Metal deposits can then be evaluated through advanced imaging techniques. [32,33] Yet, experimental measurements at foam electrodes remain critical to validate these models for modern energy storage technologies. [34] These validations are challenging, mainly due to the fact that local liquid-phase potentials at different points along and across the metal foam are considerably difficult to measure in practice.…”

“…Moreover, local current and potential distributions reside, fundamentally, within the irregular polyhedral cells (each of their sides is an open pore) that form such cellular foam materials. [33,35] Thus, the application of potential probes in the liquid-phase within individual cells or pores in the porous material is the most suitable measurement technique since no destructive analysis of the electrodes is necessary and the challenging operation of complex ad hoc electrochemical cell designs is eliminated. For instance, the use of flexible dynamic hydrogen electrodes (DHEs) in zinc-based systems has become increasingly popular due to their good handling in a wide and dynamic pH range.…”

“…Meanwhile, the latest developments have used 3D models and finite element solvers to combine electrode kinetics and electrolyte hydrodynamics at planar, [30,31] and 3D or porous substrates. Metal deposits can then be evaluated through advanced imaging techniques [32,33] . Yet, experimental measurements at foam electrodes remain critical to validate these models for modern energy storage technologies [34] .…”

“…These validations are challenging, mainly due to the fact that local liquid‐phase potentials at different points along and across the metal foam are considerably difficult to measure in practice. Moreover, local current and potential distributions reside, fundamentally, within the irregular polyhedral cells (each of their sides is an open pore) that form such cellular foam materials [33,35] …”