Mechanism insight into improved desalination performance and energy efficiency in redox flow deionization with ion exchange resins

In this work, we proposed a concept of redox flow deionization (RFDI) by constructing ion transport channels using ion exchange resins into the redox flow desalination (RFD) cell, and achieved a remarkable reduction of 27.4% in energy consumption and an increase of 24.1% in electrical power output compared to the conventional RFD system at the feed concentration of 1000–5000 mg L−1. Finite element analysis results further revealed the mechanism of RFDI process indicating that the ion exchange resin reduced the cell resistance by forming ions transport channels, which consequently improved the performance of RFDI. As a proof-of-concept application, the RFDI was evaluated for desalination of brackish water, which exhibited a freshwater productivity of 3.85 to 7.79 L m−2 h−1 with energy consumption of 5.39 to 2.31 Wh L–1. What’s more, further modification of the ion transport channels in the RFDI cell could result in even higher brackish water desalination and energy storage performance. The findings of this study have significant implications for addressing global freshwater scarcity and the development of more efficient and sustainable desalination technologies.