Design and Experimental Validation of an Asymmetric Four-Chamber Redox Flow Desalination Cell for Energy-Efficient Ion Removal

An asymmetric four-chamber redox flow desalination cell was developed to enhance ion transport and energy efficiency by controlling chamber geometry, applied voltage, and electrolyte flow rate. The design integrates thick outer redox chambers with thin desalination chambers to promote uniform redox reactions and stable mass transfer. The system operated stably for 12 h and achieved a high salt removal rate of approximately 1226 mmol·m⁻²·h⁻¹ at 1.0 V with low specific energy consumption of about 99.74 kJ·mol⁻¹, demonstrating both durable operation and highly promising desalination performance. Electrochemical impedance analysis further confirmed that increased electrolyte flow reduces charge-transfer and diffusion resistances, enabling faster ionic transport. These findings highlight the originality of the chamber-asymmetric design and its promise for compact, low-voltage redox flow systems. This work provides design guidelines for next-generation flow-based desalination systems and suggests future research directions in scaling the architecture, optimizing flow-channel geometry, and integrating higher-stability redox electrolytes for long-term practical operation.