Lockheed Martin Energy, LLC

Lockheed Martin Advanced Energy Storage, LLC

Sun Catalytix Corporation

John Goeltz

Arthur J Esswein

Desiree Amadeo

Steven Y Reece

Evan R King

Thomas D Jarvi

Nitin Tyagi

Thomas Harry Madden

Adam Morris-Cohen

Kean L Duffey

Paravastu Badrinarayanan

Joseph Johannes Henricus Pijpers

Matthew Millard

Srivatsava Venkataranga Puranam

Joseph Johannes Pijpers

Stable solutions comprising high concentrations of charged coordination complexes, including iron hexacyanides are described, as are methods of preparing and using same in chemical energy storage systems, including flow battery systems. The use of these compositions allows energy storage densities at levels unavailable by other iron hexacyanide systems.

High solubility iron hexacyanides

The present invention relates to methods and apparatuses for determining the ratio of oxidized and reduced forms of a redox couple in solution, each method comprising: contacting first and second stationary working electrodes and first and second counter electrode to the solution; applying a first potential at the first stationary working electrode and a second potential at the second stationary working electrode relative to the respective counter electrodes and measuring first and second constant currents for the first and second stationary working electrodes, respectively; wherein the first and second constant currents have opposite signs and the ratio of the absolute values of the first and second constant currents reflects the ratio of the oxidized and reduced forms of the redox couple in solution. When used in the context of monitoring/controlling electrochemical cells, additional embodiments include those further comprising oxidizing or reducing the solution.

Apparatus and method for determining state of charge in a redox flow battery via limiting currents

Solids can sometimes form in one or more electrolyte solutions during operation of flow batteries and related electrochemical systems. Over time, the solids can accumulate and compromise the integrity of flow pathways and other various flow battery components. Flow batteries configured for mitigating solids therein can include an autonomous solids separator, such as a lamella clarifier. Such flow batteries can include a first half-cell containing a first electrolyte solution, a second half-cell containing a second electrolyte solution, a first flow loop configured to circulate the first electrolyte solution through the first half-cell, a second flow loop configured to circulate the second electrolyte solution through the second half-cell, and at least one lamella clarifier in fluid communication with at least one of the first half-cell and the second half-cell. A hydrocyclone can be used as an alternative to a lamella clarifier in some instances.

Solids mitigation within flow batteries

The present invention relates to methods and apparatuses for determining the ratio of oxidized and reduced forms of a redox couple in solution, each method comprising: (a) contacting a first stationary working electrode and a first counter electrode to the solution; (b) applying a first potential at the first working electrode and measuring a first constant current; (c) applying a second potential at the first working electrode and measuring a second constant current; wherein the sign of the first and second currents are not the same; and wherein the ratio of the absolute values of the first and second currents reflects the ratio of the oxidized and reduced forms of the redox couple in solution. When used in the context of monitoring/controlling electrochemical cells, additional embodiments include those further comprising (d) oxidizing or reducing the solution, so as to alter the balance of the oxidized and reduced forms of the redox couple in solution, to a degree dependent on the ratio of the absolute values of the first and second currents. These embodiments may be used in the context of maintaining an electrochemical cell, stack, or system.

Parasitic reactions, such as production of hydrogen and oxidation by oxygen, can occur under the operating conditions of flow batteries and other electrochemical systems. Such parasitic reactions can undesirably impact operating performance by altering the pH and/or state of charge of one or both electrolyte solutions in a flow battery. Electrochemical balancing cells can allow rebalancing of electrolyte solutions to take place. Electrochemical balancing cells suitable for placement in fluid communication with both electrolyte solutions of a flow battery can include: a first chamber containing a first electrode, a second chamber containing a second electrode, a third chamber disposed between the first chamber and the second chamber, an ion-selective membrane forming a first interface between the first chamber and the third chamber, and a bipolar membrane forming a second interface between the second chamber and the third chamber.

Flow battery balancing cells having a bipolar membrane for simultaneous modification of a negative electrolyte solution and a positive electrolyte solution

This invention is directed to aqueous redox flow batteries comprising redox-active metal ligand coordination compounds. The compounds and configurations described herein enable flow batteries with performance and cost parameters that represent a significant improvement over that previous known in the art.

Aqueous redox flow batteries comprising metal ligand coordination compounds

This invention is directed to aqueous redox flow batteries comprising ionically charged redox active materials and separators, wherein the separator is about 100 microns or less and the flow battery is capable of (a) operating with a current efficiency of at least 85% with a current density of at least about 100 mA/cm; (b) operating with a round trip voltage efficiency of at least 60% with a current density of at least about 100 mA/cm; and/or (c) giving rise to diffusion rates through the separator for the first active material, the second active material, or both, of about 1&#xd7;10mol/cm-sec or less.

Electrochemical energy storage systems and methods featuring optimal membrane systems

This invention is directed to aqueous redox flow batteries comprising ionically charged redox active materials at least one of which is a sulfonated catechol.

Aqueous redox flow batteries featuring improved cell design characteristics

The invention concerns flow batteries comprising: a first half-cell comprising: (i) a first aqueous electrolyte comprising a first redox active material; and a first carbon electrode in contact with the first aqueous electrolyte; (ii) a second half-cell comprising: a second aqueous electrolyte comprising a second redox active material; and a second carbon electrode in contact with the second aqueous electrolyte; and (iii) a separator disposed between the first half-cell and the second half-cell; the first half-cell having a half-cell potential equal to or more negative than about &#x2212;0.3 V with respect to a reversible hydrogen electrode; and the first aqueous electrolyte having a pH in a range of from about 8 to about 13, wherein the flow battery is capable of operating or is operating at a current density at least about 25 mA/cm.

Electrochemical energy storage systems and methods featuring large negative half-cell potentials

Productive electrochemical reactions can often occur most effectively in proximity to a separator dividing an electrochemical cell into two half-cells. Parasitic reactions can often occur at locations more removed from the separator. Parasitic reactions are generally undesirable in flow batteries and other electrochemical systems, since they can impact operating performance. Flow batteries having a decreased incidence of parasitic reactions can include, a first half-cell containing a first electrode, a second half-cell containing a second electrode, a separator disposed between the first half-cell and the second half-cell and contacting the first and second electrodes, a first bipolar plate contacting the first electrode, and a second bipolar plate contacting the second electrode, where a portion of the first electrode or the first bipolar plate contains a dielectric material. The first electrode and the first bipolar plate still define a contiguous electrically conductive pathway when containing the dielectric material.

Mitigation of parasitic reactions within flow batteries

Titanium complexes containing at least one catecholate ligand can be desirable active materials for flow batteries and other electrochemical energy storage systems. Such complexes can be formed through reacting a catechol compound with a titanium reagent in an organic solvent, removing a byproduct species, and then obtaining an aqueous phase containing a salt form of the titanium catechol complex, particularly an alkali metal salt form. More specifically, the methods can include: forming a catechol solution containing a catechol compound and an organic solvent, contacting a titanium reagent with the catechol solution to form a reaction mixture, reacting the titanium reagent with the catechol compound to form an intermediate titanium catechol complex and a byproduct species, separating the byproduct species, and combining an alkaline aqueous solution containing a base with the intermediate titanium catechol complex to produce a salt form titanium catechol complex at least partially dissolved in an aqueous phase.

Processes for forming titanium catechol complexes

The present invention relates to redox flow batteries and methods and apparatuses for monitoring the compositions of the electrolytes therein. In particular, the present invention relates to methods and configurations for monitoring the state-of-charge of an electrolyte stream of a flow cell or flow battery.

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Carmel, CA, United States of America

John Goeltz