Enhancing understandability and performance of flow electrode capacitive deionisation by optimizing configurational and operational parameters: A review on recent progress

The aim of the researchers working in the field of desalination is to develop a cost-effective, energy-efficient and eco-friendly desalination technology to address the scarcity of potable water. Nowadays, Capacitive Deionization (CDI) is an emerging desalination technology that has the potential to overcome challenges of existing technologies, but discontinuous desalination due to electrode saturation is a limiting factor. To overcome this limitation of CDI, concept of flow electrode was introduced in CDI resulting in a novel Flow electrode Deionization (FCDI) technology. FCDI has the potential of continuous desalination as flowable nature of electrode allows electrode material regeneration outside the FCDI cell. But the limitation of using flow electrode is drop-in electrical-conductive, that leads to a decrease in desalination performance and cell efficiency. For enhancement of electronic conductivity of flow electrode, researchers are working on the optimization of flow electrode constituents, i.e. carbon weight percentage (CWP), conductive additives and electrolyte concentrations. This article presents a systematic review of the recent advances and progress made in FCDI technology on the basis of the cell architecture, flow electrode constituents, energy recovery and application area. Moreover, this work discusses current shortcoming and future challenges associated with the development and practical applications of FCDI technology.