Recent Progress and Challenges in Faradic Capacitive Desalination: From Mechanism to Performance

Abstract

Due to substantial consumption and widespread contamination of the available freshwater resources, green, economical, and sustainable water recycling technologies are urgently needed. Recently, Faradic capacitive deionization (CDI), an emerging desalination technology, has shown great desalination potential due to its high salt removal ability, low consumption, and hardly any co‐ion exclusion effect. However, the ion removal mechanisms and structure–property relationships of Faradic CDI are still unclear. Therefore, it is necessary to summarize the current research progress and challenges of Faradic CDI. In this review, the recent progress of Faradic CDI from five aspects is systematically reviewed: cell architectures, desalination mechanisms, evaluation indicators, operation modes, and electrode materials. The working mechanisms of Faradic CDI are classified as insertion reaction, conversion reaction, ion‐redox species interaction, and ion‐redox couple interaction in the electrolytes. The intrinsic and desalination properties of a series of Na+ and Cl− capturing materials are described in detail in terms of design concepts, structural analysis, and synthesis modulation. In addition, the effects of different cell architectures, operation modes, and electrode materials on the desalination performance of Faradic CDI are also investigated. Finally, the work summarizes the challenges remaining in Faradic CDI and provides the prospects and directions for future development.

Structural distortion-induced monoclinic sodium iron hexacyanoferrate as a high-performance electrode for rocking-chair desalination batteries

“…17,18 As a typical PBA, sodium iron hexacyanoferrate (NaFeHCF) is regarded as a promising material for DB thanks to its low cost, environmental friendliness, and facile, scalable production process. 19 However, NaFeHCF suffers from mediocre desalination capacity and poor cyclic stability. 20 Most previous studies have focused on improving the desalination performance of NaFeHCF by conductive layer coating and/or metal-ion ( e.g.…”

Emerging Frontiers in Multichannel Membrane Capacitive Deionization: Recent Advances and Future Prospects

“…Additionally, pore size distribution, potential of zero charge, and co-ion repulsion are known to considerably affect the ion sorption capacity. Thus, this model provides a theoretical foundation for selecting appropriate electrode materials and optimizing electrode synthesis for CDI. − Various electrode materials, including non-Faradaic materials − and Faradaic materials, ,− such as MXene, silver/silver chloride, Prussian blue analogues, and polymer materials − have been developed for CDI. Moreover, novel CDI systems, including membrane CDI, hybrid CDI, inverted CDI, and flow-electrode CDI, have been established to enhance the performance and applicability .…”

Asymmetric Fe2+/Fe3+-Mediated Flow-Electrode Capacitive Deionization for the Removal of Chloride Ions in Reclaimed Water

“…10 In the classical CDI process, driven by an electric field, ions in the feedwater migrate to the surface of the oppositely charged electrode and are then stored in the double electric layer (EDL) formed at the electrode/electrolyte interface. 11 However, a subsequent discharge process is required to regenerate the electrode capacity, which leads to intermittent operation of the CDI. 12 In addition, the electrode adsorption capacity is limited by the static electrode projection area.…”

“…Capacitive deionization (CDI) technology has received much attention because of its low energy consumption, high efficiency, and environmental friendliness of no chemical dosing . In the classical CDI process, driven by an electric field, ions in the feedwater migrate to the surface of the oppositely charged electrode and are then stored in the double electric layer (EDL) formed at the electrode/electrolyte interface . However, a subsequent discharge process is required to regenerate the electrode capacity, which leads to intermittent operation of the CDI .…”