Carbon felt (CF) acted as an "ionic capacitor" to enhance flow electrode capacitive deionization (FCDI) desalination performance.

Flow electrode capacitive deionization (FCDI) is a new ion removal technology with sustainable deionization performance. However, the interface resistance has a significant impact on ions migration in FCDI. We therefore introduced a novel FCDI device that incorporated a layer of carbon felt as an "ionic capacitor" between the flow electrode and the ion exchange membrane, termed CF-FCDI. Mechanism exploration results revealed that the addition of carbon felt reduced device resistance, shorten electron transfer pathways, improved charge efficiency, and increased ion migration rate. Experimental results demonstrated that the improved CF-FCDI device achieved 44 % higher desalination rate compared to traditional device. In addition, long term operation experiments confirmed the stability of CF-FCDI device, highlighting its potential as a viable desalination solution. The findings of this study provided valuable insights for further development of FCDI and offered a promising solution for its applications such as seawater desalination. [ABSTRACT FROM AUTHOR]