A dual-ion electrochemistry deionization system based on AgCl-Na_0.44MnO₂ electrodes

Abstract

Novel desalination technologies with high ion removal capacity and low energy consumption are desirable to tackle the water shortage challenge. Herein, we report a dual-ion electrochemistry deionization (DEDI) system with silver chloride as the electrochemical chloride release/capture anode, sodium manganese oxide as the electrochemical sodium release/capture cathode, and flow salt solution as the electrolyte. Sodium and chloride ions are synergistically released to the flow electrolyte feed at an applied positive current. Under negative current conditions, the two ions are extracted from the flow electrolyte feed to their corresponding electrodes at the same time, which can cause a conductivity decrease indicating salt removal. The salt absorption/desorption capacity of the novel deionization system is stable and reversible, up to 57.4 mg g for 100 cycles, which is much higher than that obtained by conventional or hybrid capacitive deionization devices. The charge efficiency is 0.979/0.956 during the salt desorption/absorption process. This research will be of great significance for high efficiency and low energy consumption seawater desalination.

Dual‐Ion Electrochemical Deionization System with Binder‐Free Aerogel Electrodes

“…The giant enhancement of our DEDI was mainly owing to its large chemical adsorption capacity. The super high value of our DEDI was also higher in comparison with some recent DEDI works, e.g., 57.4 mg g −1 of Na 0.44 MnO 2 ‐AgCl, 68.5 mg g −1 of Na 0.44 MnO 2 ‐BiOCl, 98.0 mg g −1 of Na 3 V 2 (PO 4 ) 3 ‐AgCl, 105 mg g −1 of NaTi 2 (PO 4 ) 3 ‐Ag, etc. Different from all the DEDI systems above, our device was fabricated with free‐standing aerogel electrodes.…”

“…Motivated by HCDI and desalination battery, a novel desalination device, dual‐ion electrochemical deionization (DEDI) was designed and reported recently . In a DEDI device, both sodium and chloride ions are chemically adsorbed by electrodes when current passes through.…”

“…Some previous works have successfully achieved very high desalination capacity with DEDI, e.g. 57.4 mg g −1 for Na 0.44 MnO 2 ‐AgCl system, 68.5 mg g −1 for Na 0.44 MnO 2 ‐BiOCl system, 98.0 mg g −1 for Na 3 V 2 (PO 4 ) 3 ‐AgCl system, 105 mg g −1 for NaTi 2 (PO 4 ) 3 ‐Ag system, etc. Among these works, we found that the desalination devices with sodium super ionic conductor (NASICON), had higher desalination capacity.…”

Rectangular Tunnel‐Structured Na0.4MnO2 as a Promising Cathode Material Withstanding a High Cutoff Voltage for Na‐Ion Batteries

“…With the quick development of society, the problems of energy crisis and environmental pollution are increasingly serious . Therefore, more and more attention has been drawn to new energy .…”

Dual‐Zinc Electrode Electrochemical Desalination

“…Dual‐ion faradaic deionization is a promising new concept for electrochemical desalination. This technology can be used to achieve an ion capture capacity that is up to six times higher than conventional CDI . Various deionization designs based on the faradaic electrode reaction have been proposed, including rocking‐chair desalination, redox‐flow battery desalination, and some novel design desalination .…”