Work

Comparison of current collector architectures for Flow-electrode Capacitive Deionization

Year: 2024

Type: article

Abstract: Flow-electrode Capacitive Deionization (FCDI) is a relatively young technology that allows energy-efficient desalination and salt concentration. FCDI employs flow electrodes, suspensions of conductive particles capable of storing ions in the electric double layer at their surface upon charging. To facilitate charging, the flow electrode particles must be electrically contacted using current collectors. Current collectors must guide the flow electrode along a membrane surface, provide a surface area for electrical contact with the particles, and be inert at high salt concentrations. In this study, we compare different current collector architectures for FCDI. Graphite plates and membrane-electrode assemblies made of carbon fiber fabric are two architectures described in the recent literature. We introduce a new current collector architecture based on a bipolar plate made of expanded graphite. These novel current collectors show up to 55 % higher salt transfer than graphite plates, rendering them a valuable new architecture for FCDI modules. Comparative analysis of different current collector architectures shows that the side walls of a flow channel are more effective at charge transport than the bottom wall. Furthermore, surface roughness impacts charge transport, with smoother surfaces leading to higher salt removal rates.

Source: Desalination

DOI: 10.1016/j.desal.2024.117595