Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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/cm2; (b) operating with a round trip voltage efficiency of at least 60% with a current density of at least about 100 mA/cm2; and/or (c) giving rise to diffusion rates through the separator for the first active material, the second active material, or both, of about 1×10?7 mol/cm2-sec or less.

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

Abstract: 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 ?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/cm2.

Abstract: Titanium coordination complexes, particularly titanium catecholate complexes, can be attractive active materials for use in flow batteries. However, such coordination complexes can be difficult to prepare from inexpensive starting materials, particularly in aqueous solutions. Titanium oxychloride and titanium tetrachloride represent relatively inexpensive titanium sources that can be used for preparing such coordination complexes. Methods for preparing titanium catecholate complexes can include combining one or more catecholate ligands and titanium oxychloride in an aqueous solution, and reacting the one or more catecholate ligands with the titanium oxychloride in the aqueous solution to form the titanium catecholate complex. Titanium tetrachloride can be used as a precursor for forming the titanium oxychloride in situ. In some instances, the titanium catecholate complex can be isolated in a solid form, which can be substantially free of alkali metal ions.

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

Abstract: 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.

Abstract: Provided are compositions having the formula MnTi(L1)(L2)(L3) wherein L1 is a catecholate, and L2 and L3 are each independently selected from catecholates, ascorbate, citrate, glycolates, a polyol, gluconate, glycinate, hydroxyalkanoates, acetate, formate, benzoates, malate, maleate, phthalates, sarcosinate, salicylate, oxalate, a urea, polyamine, aminophenolates, acetylacetone or lactate; each M is independently Na, Li, or K; n is 0 or an integer from 1-6. Also provided are energy storage systems.

Abstract: Provided are compositions having the formula MnTi(L1)(L2)(L3) wherein L1 is a catecholate, and L2 and L3 are each independently selected from catecholates, ascorbate, citrate, glycolates, a polyol, gluconate, glycinate, hydroxyalkanoates, acetate, formate, benzoates, malate, maleate, phthalates, sarcosinate, salicylate, oxalate, a urea, polyamine, aminophenolates, acetylacetone or lactate; each M is independently Na, Li, or K; n is 0 or an integer from 1-6. Also provided are energy storage systems.

Abstract: 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.

Abstract: 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.

Abstract: Provided are compositions having the formula MnTi(L1)(L2)(L3) wherein L1 is a catecholate, and L2 and L3 are each independently selected from catecholates, ascorbate, citrate, glycolates, a polyol, gluconate, glycinate, hydroxyalkanoates, acetate, formate, benzoates, malate, maleate, phthalates, sarcosinate, salicylate, oxalate, a urea, polyamine, aminophenolates, acetylacetone or lactate; each M is independently Na, Li, or K; n is 0 or an integer from 1-6. Also provided are energy storage systems.

Abstract: The invention concerns flow batteries comprising: a first aqueous electrolyte comprising a first redox active material; a second aqueous electrolyte comprising a second redox active material; a first electrode in contact with the first aqueous electrolyte; a second electrode in contact with the second aqueous electrolyte and a separator disposed between the first aqueous electrolyte and the second aqueous electrolyte; the flow battery having an open circuit potential of at least 1.4 V, and is capable of operating or is operating at a current density at least about 50 mA/cm2, wherein both of the first and second redox active materials remain soluble in both the charged and discharged states. In certain embodiments, the redox active materials are metal ligand coordination compounds. The disclosure also describes systems comprising these flow batteries and methods of them.

Abstract: 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/cm2; (b) operating with a round trip voltage efficiency of at least 60% with a current density of at least about 100 mA/cm2; and/or (c) giving rise to diffusion rates through the separator for the first active material, the second active material, or both, of about 1×10?7 mol/cm2-sec or less.

Abstract: 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.

Abstract: 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.