Flow Electrode Capacitive Deionization (FCDI) Test Cell (40mm*140mm) with Three Electrode Configuration, CFCDITC3E

Integrating a three-electrode configuration into a Flow Electrode Capacitive Deionization (FCDI) test cell is a specialized setup used primarily for electrochemical research. While standard FCDI uses two electrodes to measure total cell voltage, a three-electrode setup allows you to isolate the half-cell potential of either the anode or the cathode. This is critical for understanding which electrode is limiting performance or if unwanted side reactions (like water splitting or carbon oxidation) are occurring at a specific interface.

To convert a standard FCDI cell into a three-electrode system, a Reference Electrode (RE) is supposed to be added into the electrolyte flow path without disrupting the electric field between the Working Electrode (WE) and Counter Electrode (CE). As for the reference electrodes, (1) Luggin Capillary Method: A small capillary is inserted through the cell housing, positioned as close as possible to the surface of the Ion Exchange Membrane (IEM) on the side you wish to measure. (2) In-Line Placement: The RE (typically Ag/AgCl or Hg/Hg2SO4) is placed in a small chamber immediately downstream or upstream of the slurry flow, though this introduces "iR drop" (ohmic resistance) errors. (3) Integrated Micro-RE: Some advanced test cells use a wire-type reference electrode embedded directly into the flow channel spacer.

References:

1. H. M. Saif, et al., How should flow electrode capacitive deionization (FCDI) be operated to achieve efficient desalination and scalability?, Desalination, 2025, 606, 118769. 

2. C. Zhang, et al. Flow Electrode Capacitive Deionization (FCDI): Recent Developments, Environmental Applications, and Future Perspectives, Environ. Sci. Technol. 2021, 55, 8, 4243–4267.