We present a zinc|ferricyanide hybrid flow battery that achieves extensive first-pass desalination while simultaneously supplying electrical energy (10 Wh/L). We demonstrate 85% salt removal from simulated seawater (35 g/L NaCl) and 86% from hypersaline brine (100 g/L NaCl), together with reversible battery operation over 100 h with high round-trip efficiency (84.8%). The system has a high operating voltage (E 0 = +1.25 V), low specific energy consumption (2.11 Wh/L for 85% salt removal), and a desalination flux (4.7 mol/m 2 •h) on par with that of reverse osmosis membranes. Salt removal was similarly effective at higher feed salinities, for which reverse osmosis becomes physically impossible because of the pressure required. The results have positive implications for regions that rely on desalination for their freshwater needs, especially where sea salinity is high. Alternatively, the battery may also be useful in minimal liquid discharge wastewater treatment if operated as a brine concentrator.

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Electrochemical behavior of Ag, Bi, Cu, Fe, Ni and Sn substrates on zinc deposition was evaluated over battery cycling by cyclic voltammetry and electrochemical impedance spectroscopy. The effect of Bi, Cu, Ni, and Sn substrates on zinc electrodeposition during battery cycling was investigated using scanning electron microscopy and X-ray diffraction. The corrosion behavior of each metal in 9 M KOH and the corrosion rates of zinc plated on each substrate were analyzed by Tafel extrapolation method from the potentiodynamic polarization curves and electrochemical impedance spectroscopy. Although the charge-transfer resistance (R ct) of zinc electrodeposition is lowest on Sn, Sn eventually corrodes on cycling in alkaline media. Use of Ni as a substrate causes zinc to deteriorate on account of rapid hydrogen evolution. Bi and Cu substrates are more suitable for use as current collectors in zinc-anode alkaline