Comparison of current collector architectures for Flow-electrode Capacitive Deionization

Desalination, vol. 582, pp. 117595

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.

Authors 6

1. Niklas Köller Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany

2. Mila Perrey Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany

3. Lantz K. Brückner Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany

4. Philipp Schäfer Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany

5. Christian J. Linnartz Aachen DWI-Leibniz-Institute for Interactive Materials e.V

   DWI – Leibniz Institute for Interactive Materials · RWTH Aachen University

   Affiliation as printed

   DWI - Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, 52074 Aachen, Germany

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany

6. Matthias Weßling corresponding Aachen DWI-Leibniz-Institute for Interactive Materials e.V

   DWI – Leibniz Institute for Interactive Materials · RWTH Aachen University

   Affiliation as printed

   DWI - Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, 52074 Aachen, Germany

   RWTH Aachen University, Aachener Verfahrenstechnik-Chemical Process Engineering, Forckenbeckstraße 51, 52074 Aachen, Germany