Toward scalable and energy efficient desalination: Synergistic advances in FCDI design

Flow capacitive deionization (FCDI) is emerging as a promising desalination technology, offering continuous operation, high water recovery (up to 97 %), and lower energy consumption compared to conventional methods. The performance of FCDI systems is primarily influenced by two critical factors: active electrode materials and flow channel geometries. These elements govern ion transport, charge transfer efficiency, and energy consumption. Although material and channel design improvements are often studied independently, their combined effect plays a pivotal role in optimizing performance and warrants integrated evaluation. However, previous reviews have typically examined these parameters separately, overlooking their synergistic impact on ion transport and energy efficiency. This review uniquely integrates advancements in both material engineering and flow channel design, presenting a comprehensive evaluation of their coupled effects on desalination performance. This review sheds light on recent advancements in both areas, consolidating progress in electrode material innovations and flow channel designs. Reported advancements include salt removal rates of around 3.29 micromoles per square centimeter per minute, charge efficiencies approaching 90 %, and energy recovery efficiencies up to 36 %. Laboratory-scale systems typically achieve 70–95 % salt removal at energy demands of 0.1–0.5 kWh m −3 with up to 60 % energy recovery, while pilot-scale systems demonstrate 50–80 % salt removal at 0.5–2.0 kWh m −3 . The combined optimization of high-performance electrode materials such as activated carbon, carbon nanotubes, and redox-active composites with innovative flow channel designs including hexagonal, spiral, and 3D foam structures greatly improves ion transport and energy utilization. Overall, these integrated advancements highlight FCDI’s strong potential as a scalable, energy efficient solution for treating high salinity water and supporting large scale desalination applications.