A hybrid system of capacitive deionization and redox flow battery for continuous desalination and energy storage

In conventional capacitive deionization (CDI) system, ions are stored on the surface of the solid phase materials limiting the desalination performance with low stability. To overcome these problems, the present work endeavors to separate the ions from the brine and store it in the electrolyte medium avoiding storage of ions on the electrode materials. To serve this purpose, a combined system is designed with both CDI and a redox flow battery (RFB) with organic electrolytes, which is operated at a voltage value greater than that of the potential value corresponding to water splitting. The developed system shows a desalination capacity value of 80 mg g⁻¹ at a desalination rate of 0.11 mg cm⁻² min⁻¹ with the energy consumption value of 44.27 kT per ion. Furthermore, the system can be operated continuously without additional control to desalinate a much larger volume of saline. From the results, it can be found that salt storage in the organic electrolyte medium is found to be an advanced technique for increasing the desalination performance, while the RFB is charged or discharged simultaneously.