Aqueous redox flow batteries comprising matched ionomer membranes
First Claim
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1. A flow battery comprising:
- a first aqueous electrolyte comprising a first redox active material, the first redox active material being a first metal ligand coordination compound bearing a first ionic charge;
a second aqueous electrolyte comprising a second redox active material, the second redox active material being a second metal ligand coordination compound bearing a second ionic charge;
a first electrode in contact with said first aqueous electrolyte;
a second electrode in contact with said second aqueous electrolyte; and
a separator comprising an ionomer membrane disposed between said first and second aqueous electrolytes, the ionomer membrane comprising a polymer with ionized repeating units and electrically neutral repeating units;
wherein the first redox active material and the second redox active material differ from one another, the first ionic charge has a sign that is the same in an oxidized form and a reduced form of the first redox active material, the second ionic charge has a sign that is the same in an oxidized form and a reduced form of the second redox active material, and the signs of the first ionic charge and the second ionic charge are individually the same as a charge sign of the ionized repeating units in the ionomer membrane; and
wherein the flow battery operates or is capable of operating;
(a) where the first or second redox active materials comprise 3% or less of the molar flux of ions passing through the ionomer membrane;
or(b) with a round trip current efficiency that is at least about 95%;
or(c) at a current density of at least 100 mA/cm2 with a round trip voltage efficiency of at least about 90%;
or(d) with the electrolytes having an energy density of at least about 30 Wh/L;
or(e) with a combination of any two or more of (a), (b), (c), and (d).
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Abstract
This invention is directed to aqueous redox flow batteries comprising ionically charged redox active materials and ionomer membranes, wherein the charge of the redox active materials is of the same sign as that of the ionomer, so as to confer specific improvements.
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Citations
20 Claims
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1. A flow battery comprising:
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a first aqueous electrolyte comprising a first redox active material, the first redox active material being a first metal ligand coordination compound bearing a first ionic charge; a second aqueous electrolyte comprising a second redox active material, the second redox active material being a second metal ligand coordination compound bearing a second ionic charge; a first electrode in contact with said first aqueous electrolyte; a second electrode in contact with said second aqueous electrolyte; and a separator comprising an ionomer membrane disposed between said first and second aqueous electrolytes, the ionomer membrane comprising a polymer with ionized repeating units and electrically neutral repeating units; wherein the first redox active material and the second redox active material differ from one another, the first ionic charge has a sign that is the same in an oxidized form and a reduced form of the first redox active material, the second ionic charge has a sign that is the same in an oxidized form and a reduced form of the second redox active material, and the signs of the first ionic charge and the second ionic charge are individually the same as a charge sign of the ionized repeating units in the ionomer membrane; and wherein the flow battery operates or is capable of operating; (a) where the first or second redox active materials comprise 3% or less of the molar flux of ions passing through the ionomer membrane;
or(b) with a round trip current efficiency that is at least about 95%;
or(c) at a current density of at least 100 mA/cm2 with a round trip voltage efficiency of at least about 90%;
or(d) with the electrolytes having an energy density of at least about 30 Wh/L;
or(e) with a combination of any two or more of (a), (b), (c), and (d). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification