Air/Flow Cells

Within the past few decades an ample amount of attention has given towards developing redox flow batteries (RFBs) based on various redox couples in aqueous media due mainly to high theoretical energy densities (e.g. 440 Wh kg-1 in a Zn-Br RFB).

However, low practical energy densities are obtained due to poor solubility of active species in aqueous solvents, dendrite formation during charging, safety issues raised by the corrosive nature of aqueous acidic solvents such as H2SO4 in vanadium RFBs limit their application to stationary energy storage.

In the search for less corrosive and safe solvents, ionic liquids (ILs) draw much attention owing to their high thermal and electrochemical stability, wide electrochemical windows and negligible vapour pressures. Therefore, this research work is focused on investigating redox chemistries in IL electrolytes for the development of a high energy density small scale RFB that is safe and stable. For instance, in a recent study with 1-ethyl-3-methylimidazolium dicyanamide we have shown that highly concentrated systems are favourable under flow condition due to superior Zn plating/stripping current densities (100 mA cm-2 discharge current density) low overpotentials for Zn electrodeposition, and uniform Zn morphologies. With these promising results our investigation has further extended into different ILs and other redox couples suitable for our application.

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