A novel deionization technology was reported based on dual-ions electrochemistry technique, which possesses a stable salt removal capacity of 68.5 mg g−1. The salt is removed during the discharge process, and thus the system is called “desalination generator”.

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.

Desalination is a sustainable process that removes sodium and chloride ions from seawater. Herein, we demonstrate a faradaic mechanism to promote the capacity of capacitive deionization in highly concentrated salt water via an electrochemical deionization device. In this system, ion removal is achieved by the faradaic mechanism via a constant current operation mode, which is improved based on the constant voltage operation mode used in the conventional CDI operation. Benefiting from the high capacity and excellent rate performance of Prussian blue as an active electrochemical reaction material, the designed unit has revealed a superior removal capacity with an ultrafast ion removal rate. A high removal capacity of 101.7 mg g has been obtained with proper flow rate and current density. To further improve the performance of the EDI, a reduced graphene oxide with nanopores and Prussian blue composite has been synthesized. The PB@NPG has demonstrated a high salt removal capacity of 120.0 mg g at 1 C with an energy consumption of 6.76 kT per ion removed, which is much lower than most CDI methods. A particularly high rate performance of 0.5430 mg g s has been achieved at 40 C. The faradaic mechanism promoted EDI has provided a new insight into the design and selection of host materials for highly concentrated salt water desalination.

No abstract

Desalination devices such as capacitive deionization (CDI) have been developed for many years as an approach to relief freshwater shortage. However, due to the limitation of physical adsorption capacity of CDI, the salt removal capacity is unable to reach high value. To enhance the desalination capacity effectively, battery materials are employed to fabricate a dual‐ion electrochemical deionization (DEDI) device. Herein, a binder‐free DEDI system with two free‐standing aerogel electrodes is reported. A Na3V2(PO4)3/graphene hybrid aerogel is used as sodium electrode and a AgCl/graphene hybrid aerogel is used as chloride electrode. With electric current passing through, sodium and chloride ions are released or absorbed by two aerogel electrodes. This system achieves super high desalination capacity, excellent cycling stability, and rapid desalination rate. The desalination capacity is as high as 107.5 mg g−1 after 50 cycles with the current density of 100 mA g−1. The outstanding desalination performance of this system shows a synergistic effect of combining battery materials with graphene for deionization and promises a new potential alternative of future desalination design.

A novel electrochemical deionization system based on a NaTi2(PO4)3/rGO nanocomposite with ultrahigh salt removal capacity, rapid desalination rate and good stability.

The nature of liquid structures with their changing behaviors remains an unsolved fundamental problem in many fields of science and technology. It has been widely accepted that liquid structures change gradually with temperature and/or pressure. With x-ray diffraction in the melt In-Sn80, however, we have confirmed that a temperature-dependent discontinuous structural change could occur in some binary liquids, which does not fall into any other up-to-date recognized liquid-liquid changes. This finding, together with the recently recognized pressure-induced liquid change, suggests that the conventional view on liquids should be revised.

Seawater desalination is a promising way to alleviate water scarcity nowadays. Present capacitive desalination methods have limitation of salt removal capacity. Herein, a new dual-ion electrochemical desalination system with an ultrahigh desalination capacity is reported. It is composed of Na3V2(PO4)3@C wires as a sodium ion Faradaic electrode, AgCl as a chloride ion Faradaic electrode, and salt feed solution as the electrolyte. When a constant current is applied, redox reactions occur on electrodes, releasing or removing sodium ions and chloride ions. Na3V2(PO4)3 has a high sodium specific capacity, and as a sodium superionic conductor, Na3V2(PO4)3@C wires form an ion conductor network, providing high sodium ion mobility. Additionally, both the wire structure and carbon shell enhance the electrical conductivity of Na3V2(PO4)3. Benefiting from these, outstanding desalination performance, rate capability, and cycle capability have been achieved with the Na3V2(PO4)3@C wire–AgCl device. An ultrahigh desalination capacity of 98.0 mg/g is obtained at a current density of 100 mA/g for more than 50 cycles. This system provides a viable dual-ion electrochemical desalination strategy, which outperforms most of the existing desalination methods.