Coupling desalination and energy storage with redox flow electrodes

Abstract

Both freshwater shortage and energy crisis are global issues. Herein, we present a double-function system of faradaic desalination and a redox flow battery consisting of VCl3|NaI redox flow electrodes and a feed stream. The system has a nominal cell potential (E0 = +0.79 V). During the discharge process, the salt ions in the feed are extracted by the redox reaction of the flow electrodes, which is indicated by salt removal. Stable and reversible salt removal capacity and electricity can be achieved up to 30 cycles. The energy consumption is as low as 10.27 kJ mol-1 salt. The energy efficiency is as high as 50% in the current aqueous redox flow battery. With energy recovery, the desalination energy consumption decreases greatly to 5.38 kJ mol-1; this is the lowest reported value to date. This "redox flow battery desalination generator" can be operated in a voltage range of 0.3-1.1 V. Our research provides a novel method for obtaining energy-saving desalination and redox flow batteries.

Dual‐Zinc Electrode Electrochemical Desalination

“…The curve of the energy consumption versus salt removal rate at different current densities is shown in Figure S8 in the Supporting Information. For comparison, intermittent operation of a VCl 3 /NaI flow‐battery desalination consumes approximately 10 kJ mol −1 . Other flow battery desalination systems and desalination batteries show much higher levels for energy consumption at the same current density.…”

“…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 . These desalination devices operate by the use of individual capture/release of ions by two separate electrode materials.…”

“…Electrochemical desalination has also been reported for cells based on redox electrolytes, such as K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ], Zn/ZnCl 2 , I 3 − /I − , and Cu/CuSO 4 . These aforementioned redox‐electrolyte systems do not yet provide continuous operation owing to the separated electrode design . The integration of a continuous, energy‐saving, economic, and easy‐operation desalination technology is a key asset for the development of advanced desalination devices.…”

Integrated Saltwater Desalination and Energy Storage through a pH Neutral Aqueous Organic Redox Flow Battery

“…[ 16–18 ] These first attempts show promising ability as desalinators, with energy efficiency of <15 KJ mol −1 of salt removed. [ 16–18 ] However, simple metal salts (ZnCl 2 , VCl 2 , and NaI) used as charge storage materials in these reported desalination RFBs are subject to the issue of membrane crossover which causes irreversible capacity loss, thus reducing the cycling life of these desalination RFBs. In addition, high cell resistance of these systems limits the current density available to <2 mA cm −2 .…”

Boosting High-Rate Zinc-Storage Performance by the Rational Design of Mn2O3 Nanoporous Architecture Cathode

“…However, the use of ZIBs is still far away from practical applications because it is difficult to obtain a proper cathode material as the host for storage of Zn ions. Prussian blue analogues and vanadium-based materials are considered as potential cathode materials in ZIBs, whereas the former exhibits respectable cycling performance but limited capacities, and the latter delivers high capacities but low operating voltage [23][24][25][26]. Therefore, it is desirable to develop high-capacity ZIBs cathode materials.…”