Electrochemical Analysis of High-Performance Flow-Electrode Capacitive Mixing (F-CapMix) under Different Operating Conditions

Unlike fixed-electrode-based capacitive mixing (CapMix) cells that are characterized by intermittent power generation, flow-electrode capacitive mixing (F-CapMix) cells show continuous power generation characteristics owing to the continuous flow of the electrode in the unit cell. F-CapMix cells can be operated in two modes, depending on whether the feed water is fresh water or seawater. In this study, the F-CapMix cell was operated under the fresh-water-based flow-electrode/salt water mode (FFW) and the salt-water-based flow-electrode/fresh water mode (FSW). Under the FFW mode (similar to 0.175 W/m(2)), the F-CapMix cell showed a higher power density of 6.7% than under the FSW mode (similar to 0.164 W/m(2)). Additionally, impedance analysis based on various flow-electrode and feed water flow conditions under both the modes showed that the higher power density of the F-CapMix cell could be attributed to its lower non-ohmic resistance (i.e., lower charge transfer resistance via the ion-exchange membrane) in the FFW mode than in the FSW mode.

Automated summary

The study demonstrates that the power density of F-CapMix cells depends on the operating mode and impedance conditions. In this experiment, F-CapMix cells operating under the fresh-water-based flow-electrode mode exhibited a higher power density compared to those operating under the salt-water-based flow-electrode mode.