(706d) Investigating Transport Processes in Electrochemical Reactors with Slurry Electrodes

Electrochemical reactors with slurry electrodes are ideal for large-scale applications in energy storage, water treatment, and electrochemical manufacturing. These reactors use slurry electrodes made of conductive and/or electrochemically active colloidal particles suspended in aqueous or non-aqueous solvents, which are pumped through flow channels between the current collectors and separator. Attractive interactions between particles form dynamic networks that shuttle electrons, while ionic species travel through tortuous liquid pathways, enabling electrochemical reactions at particle-liquid interfaces. This architecture offers several advantages, including a high surface area for electrochemical reactions, continuous reactor operation, and the ability to incorporate electrochemically active, catalytic, and/or ion-absorbing particles, making it suitable for applications like flow batteries, capacitive deionization cells, and electrochemical manufacturing reactors.

A fundamental understanding of charge transport, electrochemical kinetics, and slurry flow dynamics is essential for efficient reactor design. However, the evolving particle networks and liquid pathways in the slurry pose challenges for understanding electronic and ionic transport. Additionally, the slurry’s non-Newtonian rheology, caused by the colloidal solids, leads to complex flow profiles and increased pumping losses compared to traditional liquid electrolytes.

This work employes electrochemical and rheological experiments to investigate electronic and ionic mass transport, and electrode flow behavior, as a function of particle concentration, inter-particle attraction, and slurry flow rate. High particle concentrations, strong inter-particle attractions, and low flow rates promote robust particle networks, improving electronic transport but increasing liquid pathway tortuosity, which hinders ionic transport. In contrast, high flow rates, low particle concentrations, and weaker inter-particle attractions disrupt particle networks, leading to poor electronic transport but enhanced mixing and faster ionic transport. These extremes result in mass transfer-limiting and ohmically-limiting reactor performance regimes. The microstructural origins of the results will be discussed. The findings of this work will advance electrochemical reactor design with slurry electrodes.