WO2022076672A1 - Bipolar flow battery - Google Patents

Abstract

A bipolar flow battery, an assembly comprising a bipolar flow battery in a casing, and methods for producing hydrogen, or both hydrogen and electricity, with the bipolar flow battery or assembly.

Description

BIPOLAR FLOW BATTERY

Cross-Reference to Related Applications

[0001] This application claims benefit of, and priority to, U.S. Provisional Application No. 63/089,828, filed on October 9, 2020, U.S. Provisional Application No. 63/193,902, filed on May 27, 2021 , and U.S. Provisional Application No.

63/226,344, filed on July 28, 2021 , the entire contents of all of which are specifically incorporated by reference herein.

Field of the Disclosure

[0002] This disclosure relates to the field of bipolar flow batteries.

Summary

[0003] One embodiment of the disclosure is a bipolar flow battery comprising: a sequence of alternating anodes and cathode current collectors forming two or more consecutive cells in series, each cell comprising an anode and a cathode current collector; wherein one or more anodes comprise boron, aluminum, gallium, indium or thallium; wherein the anodes and cathode current collectors have a shape comprising two opposing primary surfaces, a thickness measured from one primary surface to the other, and a perimeter; wherein, within each cell, the anode and cathode current collector are separated by a distance through which a shared electrolyte fluid may flow in contact with one primary surface of each; and wherein the series of cells comprises a terminal anode end and a terminal cathode current collector end; and the cathode current collector of one or more cells is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

[0004] Another embodiment is a bipolar flow battery assembly comprising the bipolar flow battery disposed in a casing.

[0005] Additional embodiments include methods of producing hydrogen, or both hydrogen and electricity, which comprise providing a flow of electrolyte fluid through the cells of the bipolar flow battery, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[0006] More embodiments are included in the detailed description that follows. Brief Description of the Drawings

[0007] The accompanying figures constitute a part of this disclosure. The figures serve to provide a further understanding of certain exemplary embodiments. The disclosure and claims are not limited to embodiments illustrated in the figures. [0008] FIG. 1 A is a perspective view of an exemplary bipolar flow battery of the disclosure. FIG. 1 B is a side view of the battery shown in FIG. 1A. FIG. 1 C is a top view of the battery shown in FIG. 1A. FIG. 1 D is a front view of a primary surface of an exemplary anode or cathode current collector in the battery shown in FIGs. 1A, 1 B and 1C.

[0009] Fig. 2A is a cross-sectional view of a casing for an exemplary bipolar flow battery assembly of the disclosure. FIG. 2B is a perspective and cross-sectional view of the casing. FIG. 2C is a perspective view of the casing.

[0010] FIG. 3A is a front view of a primary surface of an exemplary anode in a bipolar flow battery of the disclosure with sealing between the anode and battery assembly casing. FIG. 3B is a cross-sectional and side view of an exemplary battery assembly with sealing between the anodes and casing.

[0011] FIG. 4A is a perspective view of an exemplary bipolar flow battery of the disclosure, with prongs included in the terminal anode and terminal cathode current collector to facilitate connection to an electrical load. FIG. 4B is a cross- sectional view of an exemplary power connector system to electrically connect the terminal anode to a terminal connector that is accessible at the exterior of the battery assembly casing.

[0012] FIG. 5A is a cross-sectional and perspective view of a top portion of a casing, including a receiving manifold, for an exemplary bipolar flow battery assembly that is designated as an alpha assembly. FIG. 5B is a cross-sectional and perspective view of the battery assembly casing, including the top portion in FIG. 5A. FIG. 5C is a perspective view of a bottom portion of the casing, which includes a source manifold and that is also included in FIG. 5B. FIG. 5D is a cross-sectional and top view of the casing shown in of FIG. 5B.

[0013] FIG. 6A is a cross-sectional and perspective view of a top portion of a casing, including a receiving manifold, for an exemplary bipolar flow battery assembly that is designated as a beta assembly. FIG. 6B is a cross-sectional and perspective view of the battery assembly casing, including the top portion in FIG. 6A. FIG. 6C is a cross-sectional view of the assembly. FIG. 6D is a perspective view of the exterior casing of the assembly casing.

[0014] FIG. 7 is a perspective view of an exemplary 2-cell bipolar flow battery of the disclosure.

[0015] FIG. 8A is a perspective and cross-sectional view of an exemplary bipolar flow battery assembly comprising a 2-cell bipolar flow battery disposed in a casing. FIG. 8B is a cross-sectional side view of an assembly inclusive of that shown in FIG. 8A and also including top (receiving) and bottom (source) manifolds and flow channels.

[0016] FIG. 9 is a graph demonstrating the results of an experiment described in Example 4.

[0017] FIG. 10 is a graph illustrating the relationship between the spacing within battery cells and estimated max areal power as described in Example 5.

[0018] FIG. 11 is a graph illustrating the relationship between the spacing within battery cells and estimated ohmic resistance as described in Example 5.

[0019] FIG. 12A is a top view of an exemplary 4-cell bipolar flow battery of the disclosure. FIG. 12B is a perspective view of the battery shown in FIG 12A. FIG. 12C is a top view of an exemplary bipolar flow battery assembly comprising the battery of FIG. 12A disposed in a casing. FIG. 12D is a perspective and cross- sectional view of another exemplary assembly comprising the battery of FIG. 12A disposed in a casing.

Detailed Description

[0020] Various additional embodiments of the disclosure will now be explained in further detail. Both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of this disclosure or of the claims. Any discussion of certain embodiments or features, including those depicted in the figures, serve to illustrate certain exemplary aspects of the disclosure. The disclosure and claims are not limited to the embodiments specifically discussed herein or illustrated in the figures.

[0021] One embodiment of the disclosure is a bipolar flow battery comprising: a sequence of alternating anodes and cathode current collectors forming two or more consecutive cells in series, each cell comprising an anode and a cathode current collector; wherein one or more anodes comprise boron, aluminum, gallium, indium or thallium; wherein the anodes and cathode current collectors have a shape comprising two opposing primary surfaces, a thickness measured from one primary surface to the other, and a perimeter; wherein, within each cell, the anode and cathode current collector are separated by a distance through which a shared electrolyte fluid may flow in contact with one primary surface of each; and wherein the series of cells comprises a terminal anode end and a terminal cathode current collector end; and the cathode current collector of one or more cells is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

[0022] One or more anodes in the bipolar flow battery comprise boron, aluminum, gallium, indium or thallium, which are elements in Group 13 of the Periodic Table. One anode, or more than one anode, may comprise, for example: 1 ) only one of the named elements, 2) a combination of two or more of the named elements, or 3) one or two or more of the named elements as well as one or more additional elements. In some embodiments, all anodes in the battery comprise boron, aluminum, gallium, indium or thallium.

[0023] One or more (including possibly all) of the anodes could comprise 95% or more by weight of boron, aluminum, gallium, indium, thallium or a combination of those elements. For example, one or more anodes may comprise aluminum, such as aluminum in the amount of 95% by weight or more (or 98% or more or 99% or more) in each anode that comprises it. One or more anodes may further comprise one or more additional elements, such as magnesium, silicon, iron, copper, chromium, zinc, titanium or manganese, including combinations of any number of these.

[0024] One illustrative anode is made of Aluminum Alloy 6061. Another illustrative anode is made of 1000 series Aluminum Alloy. A further illustrative anode is made of an alloy having the name Galinstan, which is an alloy of gallium, indium and tin. Additional exemplary anodes may comprise aluminum and, by weight %, 0.0-0.15% magnesium, 0.0-0.8% silicon, 0.0-0.7% iron, 0.0-0.4% copper, 0.0- 0.35% chromium, 0.0-0.25% zinc, 0.0-0.25% titanium, 0.0-0.03% gallium, 0.0- 0.05% indium and 0.0-0.15% manganese.

[0025] One or more anodes may consist essentially of, or consist of, boron, aluminum, gallium, indium or thallium. One or more anodes could also consist essentially of, or consist of, boron, aluminum, gallium, indium or thallium, together with one or more of magnesium, silicon, iron, copper, chromium, zinc, titanium or manganese.

[0026] The bipolar flow battery comprises cathode current collectors. In some embodiments, one or more of the cathode current collectors comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver. One cathode current collector, or more than one cathode current collector, could comprise, for example: 1 ) only one of these named materials, 2) a combination of two or more of the named materials, or 3) one or two or more of the named materials as well as one or more additional materials. In some embodiments, all cathode current collectors in the battery comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver. As an example, one or more (including possibly all) of the cathode current collectors may comprise phosphor bronze comprising copper, tin and phosphorous, such as C510 phosphor bronze.

[0027] One or more cathode current collectors may consist essentially of, or consist of, bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver.

[0028] The bipolar flow battery may comprise cells having anodes all constructed of same material, or the anodes in some cells may comprise material different from that of anodes in other cells. Similarly, the cathode current collectors may all be constructed of the same material, or the cathode current collectors in some cells could comprise material different from that of others. In some embodiments, the bipolar flow battery comprises one or more anodes comprising aluminum and one or more cathode current collectors comprising phosphor bronze.

[0029] The bipolar flow battery comprises two or more consecutive cells in series formed by the sequence of alternating anodes and cathode current collectors. The battery may comprise any number of alternating anodes and cathode current collectors, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40 or 50 or more anodes alternating with 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40 or 50 or more cathode current collectors, resulting in as many cells in series. In some embodiments, the battery comprises five or more cells in series.

[0030] The anodes and cathode current collectors have a shape comprising two opposing primary surfaces, a thickness measured from one primary surface to the other, and a perimeter. In some embodiments, the anodes and cathode current collectors having two primary opposing surfaces are flat. In other embodiments, the anodes and cathode current collectors having two primary opposing surfaces include an arc shape, such as when the anode and cathode current collectors comprise a curve in their shape.

[0031]The primary surfaces are opposing faces of the anode or cathode current collector and have a larger surface area compared to the surface area on other portions of the components. FIG. 1 D illustrates a primary surface 160 of an exemplary anode or cathode current collector. The surface area of the primary surface depends on the height H and width W of the component. Where the width tapers slightly as in the embodiment shown, the surface area will be less than if the component were perfectly rectangular without tapering. As illustrated in FIG. 1 C, the components have a thickness tanode or tccc between their opposing primary surfaces. The surface area of each of the top and bottom or other sides of the components around their perimeter can be determined by taking into account the thickness of the components. In many embodiments, including in FIG. 1 C , the opposing primary surfaces are parallel such as when the thickness within each component does not vary. The anodes and cathode current collectors may have opposing primary surfaces of any appropriate size, such as 8 cm by 13 cm in the case of a rectangular shape. [0032] The anodes and cathode current collectors may be in any appropriate form, such as in the form of sheets, screens, bars or foils. Such forms can be thin and flat with opposing top and bottom faces serving as the primary surfaces of the anodes and cathode current collectors. Alternatively, the forms can be thin and curved such as in the form of an arc, with the opposing faces of the curved shape serving as the primary surfaces. The anodes may have any appropriate thickness, such as from 1 mm to 25.4 mm. The cathode current collectors may also have any appropriate thickness, such as from 0.05 mm to 2.0 mm. In some embodiments, the thickness of the anode is greater than the thickness of the cathode current collector in one or more cells. The appropriate height and width of anodes and cathode current collectors for specific applications may be cut (such as laser or die cut) from commercially available stock of the materials. [0033] The anodes and cathode current collectors have a perimeter, such as a perimeter that comprises four comers. Any corners on the perimeter may be rounded. Rounded corners may facilitate the placement of a seal around the perimeter of an anode or cathode current collector. The terminal anode at the terminal anode end of the battery and/or the terminal cathode current collector at the terminal cathode current collector end of the battery may optionally have a different geometry compared to the other anodes and cathode current collectors in the battery. For example, those terminal components may differ in their thickness or primary surface area or shape compared to other anodes and cathode current collectors. For example, the terminal components 110a and 120e in FIG. 1 A are more rectangular than the other components. The terminal anode also has a greater thickness than the other anodes as shown in FIGs. 1 B and 1 C. The different geometries may be advantageous for providing any necessary wiring or other electrical connections to the terminal components for purposes of connecting the battery to an electrical load.

[0034] Within each cell, the anode and cathode current collector are separated by a distance through which a shared electrolyte fluid may flow in contact with a primary surface of each. That distance may be referred to herein as a gap or flow space between the anode and cathode current collector. The shared electrolyte is an electrolyte fluid that flows between the anode and cathode current collector while contacting both. The battery could therefore be characterized as a “single fluid” battery compared to a two-fluid battery that uses two separate electrolyte fluids partitioned between half cells.

[0035] In some embodiments, the distance between the anode and cathode current collector in each cell is 4 mm or less, such as 1 mm or less, or is from 1 .27 mm to 7.62 mm. The distance between the anode and cathode current collector in each cell could be identical throughout the series. The anode and cathode current collector in a cell may be maintained at a distance from each other using any appropriate technique. For instance, the battery could include fixtures that hold those components in place at a distance from each other.

[0036] The cathode current collector of one or more cells is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell. In many embodiments, the cathode current collector of each cell, except the terminal cathode current collector, is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell. The remaining opposing surface of the cathode current collector may be exposed to the flow of electrolyte fluid.

[0037] Among one or more (including possibly all) cathode current collectors fastened to anodes, the majority of their primary surface could be fastened to the anode primary surface. More than 50% (such as 95%, 99% or more) of the cathode current collector primary surface could be fastened to the anode primary surface. Also among one or more cathode current collectors fastened to anodes, the majority of the anode primary surface could be fastened to the cathode current collector primary surface. More than 50% (such as 95%, 99% or more) of the anode primary surface could be fastened to the cathode current collector primary surface. The “surface” in this context refers to the surface determined from the height and width of the primary surface of the battery components and does not take into account the porosity of the components.

[0038] One or more of the cathode current collectors fastened to anodes of adjacent cells could be in direct physical contact with the anodes. In some embodiments, an electrically conductive material is interposed between at least a portion of one or more cathode current collectors and anodes to which they are fastened. [0039] Any appropriate techniques may be used to fasten the cathode current collectors and anodes. For example, one or more rivets could fasten a cathode current collector to the anode of an adjacent cell, where the rivets may comprise, for instance, stainless steel, zinc-steel, nickel-copper or brass-bronze.

[0040] One or more of the cathode current collectors could be fastened to the anodes of adjacent cells through bonding with an electrically conductive adhesive, such as a silver conductive epoxy. An example of such an epoxy is MG Chemicals #8331 -14G. Additional techniques for fastening the cathode current collectors and anodes include ultrasonic welding, SMAW welding, MIG welding, TIG welding, explosive welding, laser welding, brazing, thermal reflow, soldering and explosive joining.

[0041] FIGs. 1 A, 1 B and 1 C illustrate an exemplary embodiment of a bipolar flow battery of the disclosure. FIG. 1A is a perspective view of battery 100 comprising five anodes and five cathode current collectors. FIG. 1 B is a side view of the battery shown in FIG. 1A. Taken together, the alternating anodes and cathode current collectors form five cells, each comprising an anode and cathode current collector separated by a distance.

[0042] The battery includes anodes 110a, 110b, 110c, 110d and 110e and cathode current collectors 120a, 120b, 120c, 120d and 120e. Anode 110a is the terminal anode to the battery, and cathode current collector 120e is the terminal cathode current collector to the battery.

[0043] FIG. 1 C is a top view of the battery shown in FIGs. 1A and 1 B. Taken together, the alternating anodes and cathode current collectors form five cells in series labeled as 130a, 130b, 130c, 130d and 130e in FIG. 1 C. Each cell comprises a distance 140 between the anode and cathode current collector through which an electrolyte fluid may flow. FIG. 1 C also illustrates the thickness of the terminal anode (tanode) and terminal cathode current collector (tccc).

[0044] FIG. 1 D is a front view of a primary surface of an exemplary non-terminal anode or cathode current collector in the battery. It has a primary surface 160 and shape that tapers slightly to two rounded corners 170a and 170b on its perimeter. The rounded comers are also visible in FIGs. 1 A and 1 B. The terminal anode and terminal cathode current collector differ in shape from the remaining anodes and cathode current collectors in that they are more rectangular in shape. [0045] The anodes and cathode current collectors in FIG. 1A are positioned with their primary surfaces being parallel to each other throughout the series of cells. The cathode current collector of every cell, except the terminal cathode current collector, is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell. For example, cathode current collector 120a in cell 130a is fastened on one of its primary surfaces to a primary surface of anode 110b in adjacent cell 130b. The opposing primary surface of cathode current collector 120a is exposed to the flow of electrolyte fluid. Similarly, cathode current collector 120d in cell 130d is fastened on one of its primary surfaces to a primary surface of anode 110e in adjacent cell 130e. The cathode current collectors and anodes are fastened in this illustration with an electrically conductive adhesive that is not visible in the figures.

[0046] The terms “battery” and “batteries” when used to describe embodiments of the disclosure can include any of the bipolar flow batteries described herein, with or without the addition of an electrolyte fluid. The terms “battery” and “batteries” as used herein therefore include bipolar cell configurations that could be used in electrochemical devices. The terms “battery and “batteries” can also include a device that comprises one or more additional components, such as associated wiring and any other structural components associated with the device, including components added for convenient and safe use of the device by an end user. [0047] The batteries can be used as electrochemical devices when provided with an electrolyte fluid. Another embodiment of the disclosure therefore includes the bipolar flow battery and an electrolyte fluid disposed between the anode and cathode current collector of one or more cells of the battery, wherein the electrolyte fluid is a catholyte comprising an oxidant. In some embodiments, electrolyte fluid is disposed between the anode and cathode current collector of all cells in the battery.

[0048] The battery cells operate as flow cells for the flow battery, with electrolyte fluid flowing into the cell between the anodes and cathode current collectors of the cells and then exiting the cell. The distance between the anode and cathode current collector in each cell serves as a convenient conduit for flow of electrolyte fluid. The electrolyte fluid could be stored outside of the cell then directed to flow through the cells during operation of the battery.

[0049] The electrolyte fluid can comprise any appropriate components, including those disclosed in WO 2018/169855 A1 or WO 2020/056003 A2, the entire contents of both of which are specifically incorporated by reference herein. The electrolyte fluid is a liquid. The liquid may be in the form of a solution with components dissolved in a solvent.

[0050] The electrolyte fluid may comprise a polar solvent. Table 1 lists nonlimiting examples of polar solvents for use in the electrolyte fluid:

Table 1 : Polar Solvents

[0051] In some embodiments, the electrolyte fluid comprises water, one or more alcohols (such as methanol or ethanol), or both water and one or more alcohols as the polar solvent. In other embodiments, the electrolyte fluid consists only of water, only of one or more alcohols, or only of a mixture of water and one or more alcohols as the polar solvent. In further embodiments, the electrolyte fluid comprises a mixture of water with one or more other polar solvents, including one or more other polar solvents listed in Table 1. The polar solvent may consist essentially of, or consist of, only water and one or more polar solvents listed in Table 1.

[0052] The electrolyte fluid comprises an oxidant to be reduced in the electrochemical reaction as the material of the anode is oxidized. The current collector is characterized as a “cathode current collector” because it is believed to distribute electrons that reduce the oxidant within the electrolyte fluid at the surface of the current collector. The electrolyte fluid can be characterized as a “catholyte” because it is the source of oxidant for reduction at the cathode current collector.

[0053] A non-limiting list of compounds in Table 2, or their corresponding salts and acids as the case may be, could be delivered as oxidants and/or dissociate in the polar solvent to form oxidants.

Table 2: Oxidants

_

[0054] As used herein, the term "oxidant" refers to a compound added to perform oxidation as well as the resulting anion that results from dissociation of that compound. Thus, peroxydisulfuric acid (H2S2O8), sodium peroxydisulfate

(Na2S20s) and the peroxydisulfate anion (S2O8^2-) are all oxidants as used herein.

When the acid or salt form of the peroxydisulfate oxidant, for example, is added to an electrolyte fluid of the disclosure, there can be dissociation into the anion form. The anion form is the form which acts to oxidize another species and which in turn is reduced. Exemplary concentrations of oxidants in the fluid include, for example, from 0.25M to 1 M, from 0.5M to 1 M, from 0.75 to 1 M, from 0.5M to 0.75M, from 0.25M to 0.75M, or from 0.25M to 0.5M.

[0055] All references to particular oxidants, salts, bases and acids herein, by name or formula, as components of the electrolyte fluid include the dissociated forms of those components. As a result, the term peroxydisulfuric acid (or its formula H2S2O8) includes H2²⁺S2O8²’, the term sodium peroxydisulfate (or its formula Na2S20s) includes Na2²⁺S2O8²’ and the term sodium hydroxide (or its formula NaOH) includes Na⁺OH’.

[0056] In some embodiments, the electrolyte fluid comprises sodium peroxydisulfate, peroxydisulfuric acid, peroxydisulfate anion (S2O8^2-), or combinations of these. In further embodiments, the electrolyte fluid comprises sodium peroxydisulfate, peroxydisulfuric acid, or peroxydisulfate anion (S2O8^2-) in combination with any other oxidant, such as in combination with any other oxidants listed in Table 2 or their respective salts or acids. For example, the electrolyte fluid may comprise sodium peroxydisulfate and sodium hypochlorite. [0057] The oxidant can be, for example, in the form of a salt or an acid. Sodium peroxydisulfate is an oxidant and also a salt. Peroxydisulfuric acid is an oxidant and also an acid. Alternatively, if the oxidant is not a salt or an acid, an appropriate salt (such as a metal salt) or acid can be added to the fluid with the oxidant to provide components to form an electrolyte fluid. In some embodiments, the oxidant is a salt or acid and a second salt is added to or formed in the fluid with the oxidant, thereby resulting in the electrolyte fluid comprising two salts or an acid and a salt.

[0058] Exemplary salts, such as metal salts, that can be present in the electrolyte fluid in addition to an oxidant, are listed in Table 3. All references to “salts” include compounds such as those in Table 3 as well as the dissociated forms of the compounds when in solution.

Table 3: Metal Salts

[0059] The metal salt should be a compound that dissociates in the polar solvent so as to produce a metal ion and corresponding anion. An example of such a metal salt is aluminum chloride, sodium chloride, aluminum sulfate or sodium sulfate, such as at a concentration of 0.5M in the fluid. In embodiments where the fluid comprises two salts, such as when the oxidant is a salt and the fluid comprises an additional salt such as one listed in Table 3, the salts may comprise either the same or different anion components. The salt may be included in the fluid before operating the electrochemical device or may be formed by chemical reaction in the fluid during operation of the electrochemical device.

[0060] The electrolyte fluid may further comprise a base such as a strong base. Examples of strong bases include LiOH, RbOH, CsOH, Sr(OH)2, Ba(OH)2, NaOH, KOH, Ca(OH)2, or combinations thereof. One particular example is NaOH, such as at a concentration of 0.1 M to 0.5M, or 2M to 5M in the fluid. In other embodiments, the electrolyte fluid comprises one or more acids such as nitric acid or sulfuric acid.

[0061] The electrolyte fluid may therefore comprise, consist essentially of, or consist of, a polar solvent and an oxidant. In some embodiments, the oxidant is a salt or acid. In other embodiments, the oxidant is not a salt or acid, and the electrolyte fluid further comprises, consists essentially of, or consists of, a salt. [0062]An example polar solvent is water. An example oxidant is a salt of peroxydisulfate (such as sodium peroxydisulfate). The electrolyte fluid could therefore comprise, consist essentially of, or consist of: water, and sodium peroxydisulfate(aq), peroxydisulfuric acid(aq) or peroxydisulfate anion (S2O8²’), which includes any combination of two or more of these. The electrolyte fluid could comprise, consist essentially of, or consist of, an aqueous solution of one or more hypochlorite salts, such as sodium hypochlorite. In further embodiments, the electrolyte fluid comprises water and the S20s²’ and/or CIO’ ion. In such embodiments, the electrolyte fluid may comprise one or more of Na2S20s(aq), H2S20s(aq) and NaCIO(aq).

[0063] The electrolyte fluid may comprise, consist essentially of, or consist of, a salt that is different from the oxidant. An example salt is a salt of a sulfate (such as sodium sulfate or other metal sulfate). A fluid that comprises, consists essentially of, or consists of a polar solvent and oxidant; or of a polar solvent, oxidant, and salt; may further comprise, consist essentially of, or consist of a base or an acid. Example bases include sodium hydroxide and potassium hydroxide. Example acids include sulfuric acid and nitric acid.

[0064] Additional embodiments of the of the bipolar flow battery do not comprise a cathode in solid, gel, powder or paste form and/or do not comprise an anode in gel, powder or paste form. Additional embodiments do not comprise an electrolyte in solid or gel form.

[0065] Further embodiments of the bipolar flow battery do not comprise a solid substrate (such as a current collector) having, in addition, positive and negative active materials disposed on opposing surfaces of the substrate. Yet further embodiments do not comprise an ion-exchange membrane or an electrolytecontaining porous separator disposed between the anode and cathode current collector in the same cell.

[0066] Many embodiments of the disclosure include batteries not intended to be recharged. Thus, in some embodiments, the battery is further characterized as a primary battery.

[0067] The bipolar flow battery may produce hydrogen gas when contacted with the electrolyte fluid. The battery may produce both hydrogen and electricity when contacted with the electrolyte fluid and while also connected to an electrical load. The load could be the resistance in a wire or it could be an electrical application such as an electrically-powered device.

[0068] Electrical applications include electrical grid applications such as cell phone towers, cell phone tower backup power, backup power for wind farms or solar farms, battery backup as an alternative to a gas generator, or any other electrical load. The electricity could also be used to power vehicles, electric motors, conventional batteries, household appliances, consumer goods or toys. The hydrogen may be delivered to an application such as a fuel cell for electricity production, hydrogen compressors, fuel-cell powered vehicles, an engine or furnace for burning, or a tank for storage. Exemplary vehicles that could be powered by electricity and/or hydrogen produced by a battery of the disclosure include cars, trucks, motorcycles, airplanes, boats, tractors, quads, scooters, forklifts, golf carts, lift trucks and motorized grocery cars.

[0069] The bipolar flow battery could be used as a hydrogen supplementation device, such as for a diesel engine on a diesel-powered vehicle. This would comprise supplying hydrogen produced by the battery to an engine to assist in combustion. The diesel engine may be augmented with hydrogen gas to achieve a higher diesel fuel specific fuel consumption or to improve various exhaust emissions.

[0070] Methods for producing hydrogen, or for producing both hydrogen and electricity, therefore form additional embodiments of the disclosure. One method of the disclosure is a method for producing hydrogen, which comprises providing a flow of electrolyte fluid through one or more (including possibly all) cells in the bipolar flow battery of the disclosure, wherein the electrolyte fluid is a catholyte comprising an oxidant. Another is a method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more of the cells in the bipolar flow battery while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant. [0071] The electrolyte fluid could originate from a source and flow through each battery cell essentially simultaneously. This flow path configuration contrasts with flowing an electrolyte fluid through a series of cells sequentially, such as starting at an inlet end of a series and then through each cell in the series to the outlet end of the series. In some embodiments, the electrolyte fluid is the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity. Additional embodiments of these methods do not result in the electrodeposition of solid material on the cathode current collectors or substantial consumption of the cathode current collector material.

[0072] A further embodiment of the disclosure includes a bipolar flow battery assembly comprising the bipolar flow battery of the disclosure disposed in a casing. Such a casing could enclose the battery and also an electrolyte fluid, and may include any other structural components such as terminals, plugs, fittings and ports associated with the device, including components added for convenient and safe use of the device by an end user. The casing could be made of any appropriate materials of construction, such as electrical insulators and materials that are chemically resistant to the electrolyte fluid and mechanically sound. Such materials can include glass and plastics, such as ABS or nylon plastic.

[0073] The casing may be in the form of a unitary body or in the form of several portions that may connect together. Connected portions could comprise a seal at their interface to prevent or reduce leakage of contents inside the casing to the outside environment. One example sealing technique for these connected portions is the use of a gasket. The casing, or portions of it, could be manufactured by any suitable technique, including 3D printing or injection molding.

[0074] The casing could be designed to contain electrolyte fluid intended for flow through the battery cells. For example, the casing design could form a source manifold, a receiving manifold, and a battery containment region between the source and receiving manifolds, wherein the battery is disposed in the battery containment region. The source and receiving manifolds may each be configured to contain a bulk volume of electrolyte fluid. The manifolds and battery containment region can be in fluid communication such that electrolyte fluid may flow from the source manifold through the battery cells to the receiving manifold. The flow of electrolyte fluid may be accomplished with the use of a pump, for example.

[0075] The casing may form a plurality of flow channels extending from the source manifold to an inlet end of the battery containment region, and a plurality of flow channels extending from the receiving manifold to an outlet end of the battery containment region, the flow channels configured to provide for flow of an electrolyte fluid from the source manifold and through the battery cells. Electrolyte fluid exiting the battery containment region may then flow through flow channels to the receiving manifold, where the electrolyte fluid from the distinct channels may recombine. In such a configuration, the number of flow channels extending from each manifold may equal the number of cells in the battery, such that each flow channel extending from the source manifold is positioned to flow an electrolyte fluid into one cell and each flow channel extending from the receiving manifold is positioned to receive electrolyte fluid from one cell. The flow channels could have any appropriate geometry for their cross-section, such as a rectangular cross section as could result from the use of a casing as shown in FIG. 5D. The term “plurality” in the context of the plurality of flow channels refers to two or more flow channels. The number of flow channels extending from each manifold may be the same or different. The number of flow channels extending from each manifold may also be the same or different from the number of cells in the battery.

[0076] The flow channels from the source manifold may extend in a linear path to the inlet end of the battery containment region, and, similarly, the flow channels from the receiving manifold may extend in a linear path to the outlet end of the battery containment region. Alternatively, the flow channels from the source manifold could extend in a non-linear path to the inlet end of the battery containment region and/or the flow channels from the receiving manifold could extend in a non-linear path to the outlet end of the battery containment region. Example non-linear paths could comprise serpentine or zig-zag paths. The length of the path of travel in the flow channels could be designed sufficiently long to normalize flow of electrolyte fluid before the electrolyte fluid enters the battery cells.

[0077] Fig. 2A is a cross-sectional view of a casing 200 for an exemplary bipolar flow battery assembly of the disclosure. The casing forms a source manifold 205, a receiving manifold 210 and a battery containment region 215. The casing further forms five flow channels 220 extending from the source manifold to an inlet end of the battery containment region, and five flow channels 225 extending from the receiving manifold to an outlet end of the battery containment region. The flow channels extend from their respective manifolds in a linear path to the battery containment region. The flow channels have a rectangular cross-section and are configured to provide a flow of electrolyte fluid through the flow spaces (also with a rectangular cross-section) of the five-cell battery shown in FIGs. 1A, 1 B and 1 C, which could be disposed in the casing.

[0078] The battery containment region of the assembly may comprise a plurality of slots formed by the casing, the slots having a width configured to receive and hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter. A seal may be disposed between at least a portion of the perimeter of one or more of such anodes, cathode current collectors, or fastened anodes and cathode current collectors and at least a portion of the casing slots in which they are disposed.

[0079] The battery containment region of the assembly may instead or also comprise a plurality of slots formed by the casing, the slots having a width configured to receive a seal configured to hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter. The seal can be seated within the slot, and a portion of the seal may optionally extend outside of the slot. One or more of the anodes, cathode current collectors, or fastened anodes and cathode current collectors could then be press- fit against the seals or otherwise placed in contact with the seals.

[0080] The seals serve to reduce or prevent electrolyte leakage between adjacent battery cells by hindering any electrolyte path between them. This in turn can minimize cell-to-cell interactions, isolating the cells while ensuring that each battery cell receives an appropriate amount of electrolyte fluid.

[0081] The seal may be disposed along at least a portion of the perimeter of one or more (including possibly all) anodes, cathode current collectors, or fastened anodes and cathode current collectors, and may cover the entire thickness or less than the entire thickness of the one or more anodes, cathode current collectors, or fastened anodes and cathode current collectors where it is disposed. At least a portion of such seals could also simultaneously seal two connected portions of the casing at their interface. In some embodiments, the assembly does not comprise a seal between the terminal anode and/or terminal cathode current collector and casing. In further embodiments, seals are provided only around the perimeter of one or more anodes, whether or not those anodes are fastened to cathode current collectors.

[0082] It may be advantageous to provide a seal along the entire perimeters of some or all anodes, cathode current collectors, or fastened anodes and cathode current collectors, to reduce as much as possible any parasitic cell-cell interactions that may occur due to electrolyte fluid leaking through gaps caused by corrosion of the anode or cathode current collector, such as in a press fit mechanism. [0083] Any appropriate sealing mechanisms can be used. Exemplary seals include those in the form of a gasket, such as O-rings, including linear O-rings. The seals may be made of any appropriate material, such as synthetic or natural rubber, including natural rubber, silicone rubber, nitrile butadiene rubber, neoprene rubber or polytetrafluoroethylene. An O-ring (such as a linear O-ring) extended along the perimeter of the respective battery component could provide a functional sealing mechanism that will not substantially degrade over the lifetime of the component.

[0084] When using a seal such as a gasket, a tape or lacquer may also be disposed between the gasket and the anodes, cathode current collectors, or fastened anodes and cathode current collectors. The tape or lacquer may be applied, for example, on all or essentially all of the thickness of the anodes, cathode current collectors, or fastened anodes and cathode current collectors, providing a surface on which the O-rings may then seal.

[0085] The tape or lacquer used for this purpose would advantageously be sufficiently resistant to degradation by the electrolyte fluid and made of electrically insulating material. An example tape is Kapton tape. In one embodiment, one or more anodes, cathode current collectors, or fastened anodes and cathode current collectors include a layer of tape around their perimeter. The Kapton tape provides a barrier to corrosion and is electrically non-conductive. The Kapton tape prevents the anode from corroding in the area around the perimeter, preventing degradation of the material’s sealing surface.

[0086] The battery containment region in FIG. 2A comprises slots 230a on the inlet end of the battery containment region, slots 230b on the outlet end of the battery containment region and slots 230c on one side of the battery containment region. Additional slots can be disposed on the opposing side of the battery containment region but are not visible in FIG. 2A. The slots have a width configured to receive the anodes, cathode current collectors, or fastened anodes and cathode current collectors of the battery, or a width configured to receive a seal that will seal the battery components to the casing.

[0087] FIGs. 3A and 3B illustrate battery components sealed to the casing using a seal disposed in the slots formed by the casing. FIG. 3A is a front view of the primary surface of an exemplary anode 310 in a bipolar flow battery of the disclosure and a sealing (in two parts 350 and 360) between the anode and battery assembly casing portions 370 and 380 around the perimeter of the anode. O-ring 350 creates a fluid seal between the lower three perimeter sides of the anode and the casing, while the linear O-ring 360 creates a fluid seal between the top of the unit cell anode and interface of two connected portions of the casing 370 and 380.

[0088] FIG. 3B is a cross-sectional and side view of an exemplary battery assembly, with sealing between the anodes and casing, where the seal is disposed in the casing slots. The figure illustrates five anodes 310 and five cathode current collectors 320 forming five cells 330. Seals 350 and 360 are disposed along the perimeter of the anodes to seal the anodes to casing portions 370 and 380. Electrolyte fluid may flow through the cells in gaps 340. In the embodiments illustrated in FIGs. 3A and 3B, the seals are in the form of linear O- rings. Kapton tape 390 is disposed between the anode and linear O-ring as shown in FIG. 3A.

[0089] The battery assembly can include one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly. It may also include one or more ports, such as on the receiving manifold, for withdrawing hydrogen gas from the assembly. The assembly may operate, for example, with the receiving manifold positioned above the source manifold, with the flow of electrolyte fluid against gravity. In that configuration, hydrogen gas produced by the battery can flow in the same direction as the electrolyte and exit through a port on the receiving manifold. A hydrogen removal fitting can allow for the majority of hydrogen gas to exit the device through a hydrogen tube, with any remainder still passing through the assembly outlet.

[0090] FIG. 2B is a perspective view of the casing 200 shown in FIG. 2A. The casing comprises assembly inlets 235a and 235b to the source manifold for providing electrolyte fluid to the assembly, and an assembly outlet 240 from the receiving manifold for withdrawing electrolyte fluid from the assembly. Fitting 238 is threaded into manifold block 237 at the assembly outlet, and fitting 234 is threaded into manifold block 233 at an assembly inlet, as shown in FIGs. 2A, 2B and 2C. The fittings and manifold blocks may be constructed of any appropriate material, such as stainless steel. Port 245 is provided to remove hydrogen gas from the assembly.

[0091] The assembly could optionally also include a plate, comprising a plurality of orifices, disposed within one or both of the manifolds, the plate in the source manifold being disposed between an assembly inlet and flow channels leading to the battery containment region, and the plate in the receiving manifold being disposed between the flow channels extending from the receiving manifold and the assembly outlet. FIG. 2B illustrates such plates 250 and 255 disposed in the source manifold and receiving manifold, respectively. Electrolyte fluid entering the assembly can first pass through the plate orifices before entering the flow channels leading to the battery. Flowing electrolyte fluid through the orifices in the plate can result in a more uniform velocity of electrolyte fluid, and also assists in converting horizontal flow into the manifold into a vertical profile. Placing a corresponding plate in the receiving manifold can create back pressure and facilitate hydrogen gas separation. In some embodiments, the combined surface area of the orifices in the source manifold is less than or equal to the cross- sectional area of the assembly inlet for electrolyte fluid.

[0092] FIG. 2C is a perspective view of the casing shown in FIGs. 2A and 2B. The casing is in the form of three connected plastic portions 270, 275 and 280 that could be sealed at their interfaces.

[0093]As a further optional feature, the battery assembly could include a dividing wall that divides the manifolds and flow channels into isolated sections at a location along the length of the battery, such as at or near the middle of the battery series length, wherein the source manifold in each section is in fluid communication with only flow channels and the receiving manifold in the same section. Such a dividing wall isolates the fluid in the isolated halves of the manifolds to increase cell-cell isolation. In such a configuration, each section may comprise one or more assembly section inlets for providing electrolyte fluid to the source manifold of each section and one or more assembly section outlets for withdrawing electrolyte fluid from the receiving manifold in each section. Similarly, each section may comprise one or more ports such as on the receiving manifold of each section for withdrawing hydrogen gas. More than one dividing wall could be included to divide the assembly into as many isolated sections as desired. [0094] Load wires may be connected to the terminal anode and terminal cathode current collector and made available for access by the user in any appropriate manner. For example, the load wires may be connected to the terminal anode and terminal cathode current collector and passed through the interior of the apparatus to exit through the electrolyte inlet or outlet of the assembly. In some embodiments, load wires are connected using rivets that mechanically and electrically connect the load wire to the terminal anode and terminal cathode current collector. The wires could then be placed through the fluid tubing, and finally connected to a load.

[0095] In other embodiments, terminal connectors are designed to pass through a channel in the battery assembly casing. The terminal anode and terminal cathode current collector can be fitted with one end of an electrical connector, and the other end of the connector can be epoxied into a top portion of the casing, with the epoxy providing a fluid seal. During assembly, the top portion of the casing can be lowered onto the battery case, and the electrical connectors can be connected.

[0096] The assembly may therefore comprise an anode terminal connector accessible on the exterior of the casing that is in electrical contact with the terminal anode, and a cathode current collector terminal connector accessible to the exterior of the casing that is in electrical contact with the terminal cathode current collector. FIG. 2A illustrates these terminal connectors 260 and 265 in electrical contact with the terminal anode and terminal cathode current collector, respectively. A load wire may then be connected to these external terminal connectors.

[0097] The assembly can include a power connector system electrically connecting the terminal anode to its terminal connector and a power connector system electrically connecting the terminal cathode current collector to its terminal connector. FIG. 4A illustrates one exemplary configuration of a battery 400 of the disclosure. Terminal anode 410 and terminal cathode current collector 420 are provided with extensions, or prongs, 425. The prongs may optionally be rendered inactive in any electrochemical reaction by wrapping them with appropriate material. FIG. 4A also illustrates seals 460 positioned around at least a portion of the perimeter of certain anodes.

[0098] FIG. 4B is a cross-sectional view of an exemplary power connector system to electrically connect the prongs 425 of terminal anode 410 to terminal connector 455 that is accessible at the exterior of the battery assembly casing 440. The power connector systems, such as power system 430, may comprise plug (male) 450 and receptacle (female) 445 contacts. The plug (male) contact can be directly or indirectly in contact with a terminal connector 455 and mated to the receptacle (female) contact that is directly or indirectly in contact with the anode. Power connector systems may similarly be used on the cathode current collectors, optional with blocks 435 added to facilitate the electrical connection.

[0099] Electrolyte fluid may be provided to the assembly using any appropriate technique. For instance, one exemplary system could comprise the battery assembly of the disclosure and an electrolyte fluid reservoir configured to store a bulk volume of electrolyte fluid, wherein the electrolyte fluid reservoir comprises an inlet for receiving electrolyte fluid from one or more assembly outlets and an outlet for providing electrolyte fluid to one or more assembly inlets.

[00100] Methods of the disclosure that include the flow battery assembly comprise providing a flow of electrolyte fluid through one or more (including possibly all) battery cells in the assembly, wherein the electrolyte fluid is a catholyte comprising an oxidant. Also included is a method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more battery cells in the assembly while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant. The electrolyte fluid can have any appropriate composition as described previously.

[00101] Electrolyte fluid flowing through the battery cells can be conveniently recirculated. One such method comprises: providing a battery assembly of the disclosure; providing an electrolyte fluid in the source manifold of the assembly; flowing the electrolyte fluid from the source manifold through one or more battery cells and into the receiving manifold; and recirculating at least a portion of electrolyte fluid from the receiving manifold to the source manifold.

[00102] This method could comprise one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly, and which comprises recirculating at least a portion of electrolyte from the receiving manifold to the source manifold by flowing at least a portion of electrolyte fluid from an assembly outlet to an assembly inlet.

[00103] This recirculation method could involve flowing at least a portion of electrolyte fluid from an assembly outlet to an electrolyte fluid reservoir, then flowing at least a portion of electrolyte fluid from the electrolyte fluid reservoir to an assembly inlet. The method could further comprise providing additional electrolyte fluid, or one or more components thereof, to the assembly during its operation, such as by adding it to an electrolyte fluid reservoir that is in fluid communication with an assembly inlet. The method could also comprise withdrawing spent electrolyte fluid, or one or more components thereof, from the assembly during its operation, or withdrawing spent electrolyte fluid, or one or more components thereof, from the fluid reservoir.

[00104] In embodiments of any of the disclosed methods, the electrolyte fluid could be the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity. The methods could also not result in the electrodeposition of solid material on the cathode current collectors.

[00105] Embodiments of any of the disclosed methods could also comprise providing an approximately equal distribution of flow of electrolyte fluid through the series of battery cells. As an example, embodiments of the disclosure could flow electrolyte fluid through the cells such that the volumetric flow rate of electrolyte fluid in a cell that is the lowest in the battery is within 10% of the volumetric flow rate of electrolyte fluid in the cell that is highest in the battery. [00106] Additional embodiments of the disclosure include any casing designs disclosed herein that do not contain a battery. Such casings could be manufactured and sold separately from the batteries they are intended to contain. Example 1 : 300W system with a 5-cell bipolar flow battery

[00107] A 300W bipolar flow battery system was designed to provide a fully electrically linear, scaled up embodiment of a single electrolyte fluid, membraneless battery prototype. The 300W would be provided by a direct battery electricity combined with electricity generated from a hydrogen fuel cell with 60% efficiency. Non-terminal battery cells were tapered along their long axis, as shown in FIG. 1 D, to improve the sealing mechanism, in addition to a layer of chemically resistant Kapton tape to prevent degradation on the unit cell component sealing surface. Bipolar battery cells were sealed around their perimeter with two 0.139 inch (3.53 mm) diameter 50A durometer silicone linear O-rings [McMaster 5229T51] as depicted in FIG 3A. One linear O-ring created a seal between the top portion of the casing and the top of the bipolar unit cell components while a second linear O-ring created a fluid seal between the casing of the battery containment region and the remaining unit cell components sides.

[00108] The 300W bipolar battery system utilized five battery cells in an assembly as shown in FIGs. 2A, 2B and 2C. Bulk electrolyte entered the bottom source manifold via two 10 mm barbed fittings in a horizontal, turbulent manner before passing through an orifice plate which redirected bulk electrolyte into a near uniform, vertical, laminar profile. The laminar bulk electrolyte split into five flow channels passing through the five bipolar battery cells, before recoalescing in the top receiving manifold. A dedicated hydrogen port in the top manifold provided a hydrogen gas tap off removing the majority of generated gas. The three portions of the casing as shown in FIG. 2C were manufactured via Selective Laser Sintering (SLS) with PA 12 40% glass filled powder, custom manifold plates and top 1 inch ID x % inch (3.54 cm x 1 .91 cm) NPT male barbed hose fittings [McMaster 5361 K47] were 304 stainless steel, and the two 10 mm barbed 1/4 BSPP fittings were 316 stainless steel [Koolance FIT-V10B-SS].

[00109] The terminal battery components provided electrical power via electrical terminal assembly, as shown in FIGs. 4A and 4B, that electrically connected the terminal battery components to external load wires. The electrical terminal connector assembly mitigated potential electrolyte and hydrogen leaks by potting the connectors with epoxy.

[00110] The 300W bipolar battery system was characterized with a 2M NaOH, 0.5M Na2S2O8, solution held at 60°C. This chemistry reduced hydrogen generation rate which resulted in a longer anode lifetime and longer oxidant lifetime for more efficient system characterization. The battery system used aluminum anodes and phosphor bronze cathode current collectors. The measured bipolar flow battery system open circuit voltage was 9.941V, an average of 1 ,988V per cell or 96.93% of linear open circuit voltage.

[00111] Open circuit voltage of each battery cell was directly measured with various research-focused modifications, such as individual cellular voltage probes, to the battery casing and unit cell components. The measured 300W bipolar system open circuit voltage was 10.03V for an average of 2.007V per cell, which was 97.8% of the single cell open circuit voltage. Each bipolar cell successfully demonstrated linear open circuit voltage with the individual battery cell voltage curves nearly overlayed. The 300W system demonstrated near perfect open circuit voltage linearity at both a system and individual cellular level, and was a successfully linear embodiment of the bipolar cell topology.

[00112] The 300W bipolar system underwent verification testing with 2M

NaOH, 0.5M Na2S2O8, 60°C battery chemistry. The prototype battery system was evaluated over four separate tests to verify several key metrics, including successful cell-cell sealing and a 300W combined maximum power output. Cellcell sealing was verified with visual inspection of each sealing surface being free from corrosion in addition to the previously mentioned 97.8% open circuit voltage linearity results. The 300W combined maximum power output specification was exceeded with the battery system outputting 318W to 333W depending on the test. Hydrogen derived electricity through a 60% efficient fuel cell was calculated at 257.27W, or 470 mW/cm², using an energy mechanistic model. Direct maximum electrical power output from the 300W system ranged from 61 ,0W to 76.5W, or 111 .5mW/cm² to 139.9mW/cm², over the four tests with electrical power increasing each experiment. [00113] The 300W bipolar system increased in electrical areal power throughout the four different verification experiments, which was counterintuitive in view of an increase in ohmic resistance. The aluminum anode thickness marginally decreased with each test by appromixately 0.176 mm. The first 300W system test yielded an electrical areal maximum power output of 111 .5mW/cm², Test 2 yielded 112.8mW/cm², Test 3 yielded 126.9mW/cm², and Test 4 yielded 139.9mW/cm². The resultant electrical areal power curves shifted upward at nearly every load condition, with each global electrical areal power maximum increasing with each successive test. The phenomenon driving this behavior may be due to a discrete step forming at the kapton tape-aluminum anode boundary, causing turbulent conditions as the anode was consumed. Turbulent conditions may improve electrolyte mixing over the surfaces of the battery components, reducing local depletion of the oxidant at the cathode current collector surface.

Further increases in electrical areal power output exploiting this phenomenon may result in realized performance increases in electrical power output, specific energy, energy density, and various other energy and power metrics.

Example 2: Alpha prototype of 1500W system with a 30-cell bipolar flow battery [00114] FIGs. 5A, 5B, 5C and 5D provide a variety of views of an exemplary casing for a 1500W, 30-cell battery, designated as an alpha prototype.

[00115] FIG. 5A is a cross-sectional and perspective view of a top (receiving) portion of the casing for the exemplary bipolar flow battery assembly. FIG. 5B is a cross-sectional and perspective view of the casing, including the top portion in FIG. 5A. FIG. 5C is a perspective view of a bottom (source) portion of the casing that is also included in FIG. 5B.

[00116] The casing includes source manifold 505, receiving manifold 510 and battery containment region 515, shown in these figures without the battery or electrolyte fluid. Flow channels 520 extend from the source manifold to an inlet end of the battery containment region. Flow channels 525 extend from the receiving manifold to an outside side of the battery containment region. The number of flow channels, 30, is equal to the number of cells in the battery to be placed in the battery containment region. [00117] The battery containment region 515 comprises a plurality of slots 530a, 530b and 530c formed by the casing. The slots have a width configured to receive a seal that will seal one or more of the anodes, cathode current collectors, or fastened anodes and cathode current collectors, to the casing. The slots are provided on both the inlet end of the battery containment region (530a) and on the outlet end of the battery containment region (530b). Slots 530c are also provided on the sides of the battery containment region as seen more clearly in FIG. 5D. [00118] The casing includes assembly inlets 535a and 535b to the source manifold for providing electrolyte fluid to the assembly, and assembly outlet 540 from the receiving manifold for withdrawing electrolyte fluid. Fitting 538 is threaded into manifold block 537 at the assembly outlet, and fitting 534 is threaded into manifold block 533 at an assembly inlet, as shown in FIG. 5B. A plate comprising a plurality of orifices is disposed within each of the manifolds. Plate 545 is disposed in the source manifold and plate 550 is disposed in the receiving manifold. FIG. 5C illustrates plate 545 within casing 560.

[00119] FIG. 5D is a cross-sectional and top view of the casing shown in of FIG. 5B. The flow channels 555 in the casing align with the spaces between the anodes and cathode current collectors of the battery cells and facilitate the flow of electrolyte fluid through the battery cells.

Example 3: Beta prototype of 1500W system with 30-cell bipolar flow battery [00120] FIGs. 6A, 6B, 6C and 6D provide a variety of views of an exemplary casing for a 1500W, 30-cell battery, designated as a beta prototype.

[00121] FIG. 6A is a cross-sectional and perspective view of a top (receiving) portion of the casing for the exemplary bipolar flow battery assembly. FIG. 6B is a cross-sectional and perspective view of the casing, including the top portion in FIG. 6A. FIG. 6C is a cross-sectional view of the assembly. FIG. 6D is a perspective view of the exterior casing of the assembly.

[00122] This prototype includes a dividing wall 670 that divides the manifolds and flow channels into isolated sections 690 and 695, where the source manifold in each section is in fluid communication with only flow channels and the receiving manifold in the same section. Part numbers identified for the beta assembly are provided largely only for section 695 of the assembly. The part numbers are mentioned herein in the plural form because many have corresponding parts also present in section 690.

[00123] The casing includes source manifolds 605, receiving manifolds 610 and battery containment regions 615, shown without the battery electrodes or electrolyte fluid. Flow channels 620 extend from the source manifold to an inlet end of the battery containment region. Flow channels 625 extend from the receiving manifold to an outlet side of the battery containment region. The number of flow channels, 30, is equal to the number of cells in the battery to be placed in the battery containment region.

[00124] The battery containment regions 615 each comprise a plurality of slots 630a, 630b and 630c formed by the casing. The slots have a width configured to receive a seal that will seal one or more of the anodes, cathode current collectors, or fastened anodes and cathode current collectors, to the casing. The slots are provided on the inlet end of the battery containment regions (630a), the outlet end of the battery containment regions (630b) and on the sides of the battery containment regions 630c.

[00125] The casing includes assembly inlets 635 to the source manifold for providing electrolyte fluid to the assembly, and assembly outlets 640 from the receiving manifold for withdrawing electrolyte fluid. Fitting 638 is threaded into manifold block 637 at the assembly outlet, and fitting 634 is threaded into manifold block 633 at the assembly inlet, as shown in FIGs. 6B and 6C. A plate comprising a plurality of orifices is disposed within each of the manifolds. Plates 645 are disposed in the source manifolds and plates 650 are disposed in the receiving manifolds. Hydrogen ports 655 provide for withdrawal of hydrogen gas from the assembly. Terminals 665a and 665b are electrically connected to the terminal anode and terminal cathode current collector in the battery, respectively.

[00126] FIG. 6D is a perspective view of the exterior casing of the assembly, shown in this exemplary embodiment as being in three connected portions 675, 680 and 685.

[00127] This 1 ,500W, or 1 ,5kW, bipolar flow battery assembly was characterized with a 2M NaOH, 0.5M Na2S2O8, solution held at 60°C. This chemistry reduced hydrogen generation rate which resulted in a longer anode lifetime and longer oxidant lifetime for more efficient system characterization. The battery system used aluminum anodes and phosphor bronze cathode current collectors. The measured bipolar system open circuit voltage was 51 ,10V, an average of 1 ,70V per cell or 83.04% of linear open circuit voltage, demonstrated on the resulting voltage curve.

[00128] The 1 ,5kW bipolar system underwent verification testing with 2M NaOH, 0.5M Na2S2O8, 60°C battery chemistry. The prototype battery system was evaluated over two separate tests to verify a 1 ,5kW combined maximum power output. The 1500W combined maximum power output specification was met with the battery system outputting 1515W. Hydrogen derived electricity through a 60% efficient fuel cell was calculated at 1333W, or 406 mW/cm², using an energy mechanistic model. Direct maximum electrical power output from the 1 ,5kW system was measured at 182W, or 55.45mW/cm².

Example 4

[00129] FIG. 7 illustrates an exemplary 2-cell bipolar flow battery of the disclosure 700. The battery comprises anodes 710a and 710b and cathode current collectors 720a and 720b. Together the alternating anodes and cathode current collectors form cells 730a and 730b, with the cathode current collector 720a of cell 730a fastened to the anode 710b of adjacent cell 730b with an electrically conductive adhesive.

[00130] FIG. 8A is a perspective and cross-sectional view of an assembly comprising the bipolar flow battery of FIG. 7 disposed in a casing 840. This apparatus is designed to help minimize cell-to-cell interactions.

[00131] The assembly includes gasket 810 at the top end of the battery containment region and gasket 820 at the bottom end. Gaskets 810 and 830 form seals between connected portions of the casing, as further seen in FIG. 8B. This assembly isolates the cells while ensuring that each cell receives an appropriate amount of electrolyte fluid. Cell isolation is achieved by effectively disconnecting the fluid channels via gaskets at the top and bottom of each pair of battery components. In this assembly, gaskets are used not only for the repeating unit cell, but also for the terminal anode in the configuration as well. [00132] FIG. 8B is a cross-sectional view of the assembly shown in FIG. 8A, also including source and receiving manifolds 850 and 860, respectively. The fluid manifolds in an assembly such as that illustrated in FIG. 8B assist to distribute the flow of electrolyte fluid equally between the cells. Flow channels 880 are joined at the source manifold, but split into flow channels before reaching the battery containment region 870. The flow channels have a fixed distance where flow normalizes in the channel, which further aids in cell-cell isolation. Flow channels 890 direct electrolyte fluid from the battery containment region 870 to receiving manifold 860.

[00133] In a two cell bipolar arrangement, flow is ideally split evenly between the two cells. In this Example, a single cell battery and the 2-cell bipolar flow battery shown in FIG. 7 were tested in the same conditions (60°C, 5M NaOH, 0.25M Na2S20s, and approximately equal normalized flow rates). The distance between the anodes and cathode current collectors in each cell was 0.1 inches (2.5 mm). The 2-cell battery was positioned in a casing as shown in FIGs. 8A and 8B. The 2-cell battery reached 100.14% of linear open circuit voltage, which implies the 2-cell bipolar battery was fully isolated and there was at least 0.14% of experimental variation. Maximum electrical areal power for the 2-cell bipolar battery was only 80.83% of maximum electrical areal power of a 1-cell battery, which is most likely due to improper flow distribution in the input manifold. In nonmaximum power areas, the 2-cell bipolar battery was approximately 95% of linear areal power output with respect to the single cell bipolar battery.

[00134] FIG. 9 presents the results of the experiment, with the data provided in the following Table 4.

Table 4

Example 5

[00135] A number of experiments were conducted using an electrolyte fluid of 5M NaOH, 0.25M Na2S2O8, at 60°C and same flow rate. Table 5 provides the results of several experiments using 1 cell or a 2-cell bipolar flow battery shown in FIG. 7 having a space of 0.05 inches (1 .27 mm) between the anode and cathode current collector within a cell.

Table 5

[00136] Table 6 provides the results of several experiments using 1 cell or a 2 cells bipolar flow battery having a space of 0.1 inches (2.54 mm) between the anode and cathode current collector within a cell.

Table 6

[00137] FIGs. 10 and 11 are additional graphs illustrating the relationship between the spacing within battery cells and the estimated max areal power and estimated ohmic resistance, respectively.

[00138] The trendline suggests a max power intercept for the topology/chemistry of 221 mW/cm². The max power intercept value may increase with electrical contact improvements, flow profile optimization, modifications to the electrolyte chemistry or other engineering design improvements.

Example 6

[00139] FIGs. 12A and 12B represent exemplary embodiments of a 4-cell bipolar battery of the disclosure. FIG. 12A is a top view of the battery. FIG. 12B is a perspective view of the battery shown in FIG. 12A.

[00140] The bipolar flow battery 1200 comprises four anodes 1210a, 1210b, 1210c and 121 Od, alternating with cathode current collectors 1220a, 1220b, 1220c and 1220d to form cells 1230a, 1230b, 1230c and 1230d. Cathode current collectors 1220a, 1220b and 1220c are fastened to the anodes of their adjacent cells with rivets 1250c, 1250a and 1250b, respectively. Electrolyte fluid may flow through gaps 1240 formed by the distance between the anode and cathode current collector in each cell.

[00141] FIG. 12C is a top view of an exemplary bipolar flow battery assembly comprising the bipolar cell configuration of FIG. 12A disposed in a casing 1260. FIG. 12D is a perspective and cross-sectional view of an exemplary bipolar flow battery assembly comprising the battery of FIG. 12A disposed in a casing. The casing comprises source manifold 1270, receiving manifold 1280 and a battery containment region 1290. Exemplary Embodiments

[00142] Exemplary embodiments of the disclosure include those provided in the following clauses.

[00143] Clause 1. A bipolar flow battery comprising: a sequence of alternating anodes and cathode current collectors forming two or more consecutive cells in series, each cell comprising an anode and a cathode current collector; wherein one or more anodes comprise boron, aluminum, gallium, indium or thallium; wherein the anodes and cathode current collectors have a shape comprising two opposing primary surfaces, a thickness measured from one primary surface to the other, and a perimeter; wherein, within each cell, the anode and cathode current collector are separated by a distance through which a shared electrolyte fluid may flow in contact with one primary surface of each; and wherein the series of cells comprises a terminal anode end and a terminal cathode current collector end; and the cathode current collector of one or more cells is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

[00144] Clause 2. The battery of clause 1 , wherein all anodes comprise boron, aluminum, gallium, indium or thallium.

[00145] Clause 3. The battery of any one of clauses 1 -2, wherein the one or more anodes comprise aluminum.

[00146] Clause 4. The battery of any one of clauses 1 -3, wherein the one or more anodes further comprise magnesium, silicon, iron, copper, chromium, zinc, titanium or manganese.

[00147] Clause 5. The battery of any one of clauses 1 -4, wherein one or more cathode current collectors comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver.

[00148] Clause 6. The battery of clause 5, wherein all cathode current collectors comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver.

[00149] Clause 7. The battery of any one of clauses 5-6, wherein the one or more cathode current collectors comprise phosphor bronze.

[00150] Clause 8. The battery of any one of clauses 1-7, wherein the anodes and cathode current collectors are flat.

[00151] Clause 9. The battery of any one of clauses 1-8, wherein the anodes and cathode current collectors are in the form of sheets, screens, bars or foils.

[00152] Clause 10. The battery of any one of clauses 1-9, wherein the cathode current collector of each cell, except the terminal cathode current collector, is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

[00153] Clause H . The battery of any one of clauses 1-10, wherein, among one or more cathode current collectors fastened to anodes, the majority of their primary surface is fastened to the anode surface.

[00154] Clause 12. The battery of any one of clauses 1-11 , wherein, among one or more cathode current collectors fastened to anodes, the majority of the anode primary surface is fastened to the cathode current collector surface.

[00155] Clause 13. The battery of any one of clauses 1-12, wherein one or more cathode current collectors fastened to anodes of adjacent cells are in direct physical contact with the anodes.

[00156] Clause 14. The battery of any one of clauses 1-12, which comprises an electrically conductive material interposed between at least a portion of one or more cathode current collectors and anodes to which they are fastened.

[00157] Clause 15. The battery of any one of clause 1-12, wherein the cathode current collectors are fastened to the anodes of adjacent cells through bonding with an electrically conductive adhesive.

[00158] Clause 16. The battery of clause 15, wherein the electrically conductive adhesive is silver conductive epoxy.

[00159] Clause 17. The battery of any one of clauses 1-16, further comprising an electrolyte fluid disposed between the anode and cathode current collector of one or more cells in the series, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[00160] Clause 18. The battery of clause 17, wherein the oxidant is a salt or acid.

[00161] Clause 19. The battery of clause 17, wherein the oxidant is not a salt or acid, and wherein the electrolyte fluid further comprises a salt.

[00162] Clause 20. The battery of clause 17, wherein the electrolyte fluid comprises: water, and sodium peroxydisulfate(aq), peroxydisulfuric acid(aq) or peroxydisulfate anion (S2O8^2-).

[00163] Clause 21 . The battery of any one of clauses 17 and 20, wherein the electrolyte fluid comprises an aqueous solution of one or more hypochlorite salts.

[00164] Clause 22. The battery of clause 21 , which comprises sodium hypochlorite.

[00165] Clause 23. The battery of any one of clauses 17-22, wherein the electrolyte fluid further comprises a base.

[00166] Clause 24. The battery of clause 23, wherein the base is sodium hydroxide.

[00167] Clause 25. The battery of any one of clauses 17-24, wherein the electrolyte fluid comprises a metal sulfate.

[00168] Clause 26. The battery of clause 25, wherein the metal sulfate is sodium sulfate.

[00169] Clause 27. The battery of clause 17, wherein the electrolyte fluid comprises water, sodium peroxydisulfate(aq) and sodium hydroxide.

[00170] Clause 28. The battery of any one of clauses 1-27, which does not comprise a cathode in solid, gel, powder or paste form.

[00171] Clause 29. The battery of any one of clauses 1-28, which does not comprise an anode in gel, powder or paste form. [00172] Clause 30. The battery of any one of clauses 1-29, which does not comprise a solid substrate having, in addition, positive and negative active materials disposed on opposing surfaces of the substrate.

[00173] Clause 31 . The battery of clause 30, wherein the solid substrate is a current collector.

[00174] Clause 32. The battery of any one of clauses 1-31 , which does not comprise an ion-exchange membrane.

[00175] Clause 33. The battery of any one of clauses 1-32, which does not comprise an electrolyte in solid or gel form.

[00176] Clause 34. The battery of any one of clauses 1-33, which does not comprise an electrolyte-containing porous separator disposed between the anodes and cathode current collectors in the same cell.

[00177] Clause 35. The battery of any one of clauses 1-34, wherein the battery is a primary battery.

[00178] Clause 36. A method for producing hydrogen, which comprises providing a flow of electrolyte fluid through one or more cells in the battery of any one of clauses 1-35, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[00179] Clause 37. A method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more cells in the battery of any one of clauses 1-35 while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[00180] Clause 38. The method of any one of clauses 36-37, wherein the electrolyte fluid is the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity.

[00181] Clause 39. The method of any one of clauses 36-38, which does not result in the electrodeposition of solid material on the cathode current collectors.

[00182] Clause 40. A bipolar flow battery assembly comprising the battery of any one of clauses 1-35 disposed in a casing.

[00183] Clause 41 . The battery assembly of clause 40, wherein the casing comprises glass or plastic. [00184] Clause 42. The battery assembly of any one of clauses 40-41 , wherein the casing is a unitary body.

[00185] Clause 43. The battery assembly of any one of clauses 40-41 , wherein the casing is in the form of two or more connected portions.

[00186] Clause 44. The battery assembly of any one of clauses 40-43, wherein the casing forms a source manifold, a receiving manifold, and a battery containment region between the source and receiving manifolds, wherein the battery is disposed in the battery containment region.

[00187] Clause 45. The battery assembly of clause 44, wherein the source and receiving manifolds are each configured to contain a bulk volume of electrolyte fluid, the manifolds and battery containment region being in fluid communication such that electrolyte fluid may flow from the source manifold through the battery cells to the receiving manifold.

[00188] Clause 46. The battery assembly of clause 45, wherein the casing further forms a plurality of flow channels extending from the source manifold to an inlet end of the battery containment region, and a plurality of flow channels extending from the receiving manifold to an outlet side of the battery containment region, the flow channels configured to provide for flow of an electrolyte fluid through the battery cells.

[00189] Clause 47. The battery assembly of clause 46, wherein the number of flow channels extending from each manifold is equal to the number of cells in the battery, each flow channel extending from the source manifold positioned to flow an electrolyte fluid into one cell and each flow channel extending from the receiving manifold positioned to receive electrolyte fluid from one cell.

[00190] Clause 48. The battery assembly of any one of clauses 46-47, wherein the flow channels from the source manifold extend in a linear path to the inlet end of the battery containment region, and the flow channels from the receiving manifold extend in a linear path to the outlet side of the battery containment region.

[00191] Clause 49. The battery assembly of any one of clauses 46-47, wherein the flow channels from the source manifold extend in a non-linear path to the inlet end of the battery containment region and/or the flow channels from the receiving manifold extend in a non-linear path to the outlet side of the battery containment region.

[00192] Clause 50. The battery assembly of clause 49, wherein the nonlinear path of the flow channels comprises a serpentine or zig-zag path.

[00193] Clause 51 . The battery assembly of any one of clauses 44-50, wherein the battery containment region comprises a plurality of slots formed by the casing, the slots having a width configured to receive and hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter.

[00194] Clause 52. The battery assembly of any one of clauses 44-50, wherein the battery containment region comprises a plurality of slots formed by the casing, the slots having a width configured to receive a seal configured to hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter.

[00195] Clause 53. The battery assembly of clause 52, in which at least a portion of the seal also seals two connected portions of the casing at their interface.

[00196] Clause 54. The battery assembly of any one of clauses 52-53, which comprises a seal disposed along at least a portion of the perimeter of one or more anodes.

[00197] Clause 55. The battery assembly of any one of clauses 52-54, which comprises a seal disposed along at least a portion of the perimeter of one or more cathode current collectors.

[00198] Clause 56. The battery assembly of clause 55, which does not comprise a seal between the terminal cathode current collector and casing.

[00199] Clause 57. The battery assembly of any one of clauses 52-56, which comprises a seal disposed along at least a portion of the perimeter of one or more pairs of fastened anodes and cathode current collectors.

[00200] Clause 58. The battery assembly of any one of clauses 52-57, wherein the seal is in the form of a gasket.

[00201] Clause 59. The battery assembly of clause 58, wherein the gasket is a linear O-ring. [00202] Clause 60. The battery assembly of any one of clauses 58-59, which further comprises a tape or lacquer disposed between the gasket and the anodes, cathode current collectors, or fastened anodes and cathode current collectors.

[00203] Clause 61 . The battery assembly of any one of clauses 44-60, which further comprises one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly.

[00204] Clause 62. The battery assembly of any one of clauses 44-61 , which further comprises one or more ports on the receiving manifold for withdrawing hydrogen gas from the assembly.

[00205] Clause 63. The battery assembly of any one of clauses 61 -62, which further comprises a plate, comprising a plurality of orifices, disposed within each of the manifolds, the plate in the source manifold being disposed between an assembly inlet and flow channels leading to the battery containment region, and the plate in the receiving manifold being disposed between the flow channels extending from the receiving manifold and an assembly outlet.

[00206] Clause 64. The battery assembly of any one of clauses 46-63, which comprises a dividing wall that divides the manifolds and flow channels into isolated sections at a location along the length of the battery, wherein the source manifold in each section is in fluid communication with only flow channels and the receiving manifold in the same section.

[00207] Clause 65. The battery assembly of clause 64, which comprises one or more assembly section inlets for providing electrolyte fluid to the source manifold of each section and one or more assembly section outlets for withdrawing electrolyte fluid from the receiving manifold in each section.

[00208] Clause 66. The battery assembly of any one of clauses 64-65, which comprises one or more ports on the receiving manifold of each section for withdrawing hydrogen gas.

[00209] Clause 67. The battery assembly of any one of clauses 40-66, which comprises an anode terminal connector accessible on the exterior of the casing that is in electrical contact with the terminal anode, and a cathode current collector terminal connector accessible to the exterior of the casing that is in electrical contact with the terminal cathode current collector.

[00210] Clause 68. The battery assembly of clause 67, which comprises power connector system electrically connecting the terminal anode to its terminal connector and a power connector system electrically connecting the terminal cathode current collector to its terminal connector.

[00211] Clause 69. The battery assembly of clause 68, wherein each power connector systems comprises plug (male) and receptacle (female) contacts.

[00212] Clause 70. The battery assembly of clause 69, wherein the plug (male) contact is directly or indirectly in contact with a terminal connector and is mated to the receptacle (female) contact that is directly or indirectly in contact with the anode or cathode current collector.

[00213] Clause 71. A system, which comprises the battery assembly of any one of clauses 61 -70 and an electrolyte fluid reservoir configured to store a bulk volume of electrolyte fluid, wherein the electrolyte fluid reservoir comprises an inlet for receiving electrolyte fluid from one or more assembly outlets and an outlet for providing electrolyte fluid to one or more assembly inlets.

[00214] Clause 72. A method for producing hydrogen, which comprises providing a flow of electrolyte fluid through one or more cells in the battery assembly of any one of clauses 40-70, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[00215] Clause 73. A method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more cells in the battery assembly of any one of clauses 40-70 while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant.

[00216] Clause 74. A method which comprises: providing the battery assembly of any one of clauses 44-70; providing an electrolyte fluid in the source manifold; flowing the electrolyte fluid from the source manifold through one or more of the battery cells and into the receiving manifold; and recirculating at least a portion of electrolyte fluid from the receiving manifold to the source manifold. [00217] Clause 75. The method of clause 74, which comprises one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly, and which comprises recirculating at least a portion of electrolyte from the receiving manifold to the source manifold by flowing at least a portion of electrolyte fluid from an assembly outlet to an assembly inlet.

[00218] Clause 76. The method of clause 75, which comprises flowing at least a portion of electrolyte fluid from an assembly outlet to an electrolyte fluid reservoir, then flowing at least a portion of electrolyte fluid from the electrolyte fluid reservoir to an assembly inlet.

[00219] Clause 77. The method of any one of clauses 74-76, which further comprises providing additional electrolyte fluid, or one or more components thereof, to the assembly during its operation.

[00220] Clause 78. The method of clause 77, which comprises providing additional electrolyte fluid, or one or more components thereof, by adding it to an electrolyte fluid reservoir that is in fluid communication with an assembly inlet.

[00221] Clause 79. The method of any one of clauses 74-78, which further comprises withdrawing spent electrolyte fluid, or one or more components thereof, from the assembly during its operation.

[00222] Clause 80. The method of any one of clause 72-79, wherein the electrolyte fluid is the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity.

[00223] Clause 81 . The method of any one of clauses 72-80, which does not result in the electrodeposition of solid material on the cathode current collectors.

[00224] Clause 82. The method of any one of clauses 72-81 , which comprises providing an approximately equal distribution of flow of electrolyte fluid through the series of battery cells.

Claims

We claim:

1 . A bipolar flow battery comprising: a sequence of alternating anodes and cathode current collectors forming two or more consecutive cells in series, each cell comprising an anode and a cathode current collector; wherein one or more anodes comprise boron, aluminum, gallium, indium or thallium; wherein the anodes and cathode current collectors have a shape comprising two opposing primary surfaces, a thickness measured from one primary surface to the other, and a perimeter; wherein, within each cell, the anode and cathode current collector are separated by a distance through which a shared electrolyte fluid may flow in contact with one primary surface of each; and wherein the series of cells comprises a terminal anode end and a terminal cathode current collector end; and the cathode current collector of one or more cells is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

2. The battery of claim 1 , wherein all anodes comprise boron, aluminum, gallium, indium or thallium.

3. The battery of any one of claims 1-2, wherein the one or more anodes comprise aluminum.

4. The battery of any one of claims 1-3, wherein the one or more anodes further comprise magnesium, silicon, iron, copper, chromium, zinc, titanium or manganese.

5. The battery of any one of claims 1-4, wherein one or more cathode current collectors comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver.

6. The battery of claim 5, wherein all cathode current collectors comprise bronze, phosphor bronze, steel, carbon, the graphite allotrope of carbon, carbon impregnated with a metal, carbon foam, copper, tin, iron, lead, platinum, gold or silver.

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7. The battery of any one of claims 5-6, wherein the one or more cathode current collectors comprise phosphor bronze.

8. The battery of any one of claims 1-7, wherein the anodes and cathode current collectors are flat.

9. The battery of any one of claims 1-8, wherein the anodes and cathode current collectors are in the form of sheets, screens, bars or foils.

10. The battery of any one of claims 1-9, wherein the cathode current collector of each cell, except the terminal cathode current collector, is fastened on one of its primary surfaces to a primary surface of the anode of an adjacent cell.

11 . The battery of any one of claims 1 -10, wherein, among one or more cathode current collectors fastened to anodes, the majority of their primary surface is fastened to the anode surface.

12. The battery of any one of claims 1-11 , wherein, among one or more cathode current collectors fastened to anodes, the majority of the anode primary surface is fastened to the cathode current collector surface.

13. The battery of any one of claims 1-12, wherein one or more cathode current collectors fastened to anodes of adjacent cells are in direct physical contact with the anodes.

14. The battery of any one of claims 1-12, which comprises an electrically conductive material interposed between at least a portion of one or more cathode current collectors and anodes to which they are fastened.

15. The battery of any one of claims 1-12, wherein the cathode current collectors are fastened to the anodes of adjacent cells through bonding with an electrically conductive adhesive.

16. The battery of claim 15, wherein the electrically conductive adhesive is silver conductive epoxy.

17. The battery of any one of claims 1-16, further comprising an electrolyte fluid disposed between the anode and cathode current collector of one or more cells in the series, wherein the electrolyte fluid is a catholyte comprising an oxidant.

18. The battery of claim 17, wherein the oxidant is a salt or acid.

45

19. The battery of claim 17, wherein the oxidant is not a salt or acid, and wherein the electrolyte fluid further comprises a salt.

20. The battery of claim 17, wherein the electrolyte fluid comprises: water, and sodium peroxydisulfate(aq), peroxydisulfuric acid(aq) or peroxydisulfate anion (S2O8^2-).

21 . The battery of any one of claims 17 and 20, wherein the electrolyte fluid comprises an aqueous solution of one or more hypochlorite salts.

22. The battery of claim 21 , which comprises sodium hypochlorite.

23. The battery of any one of claims 17-22, wherein the electrolyte fluid further comprises a base.

24. The battery of claim 23, wherein the base is sodium hydroxide.

25. The battery of any one of claims 17-24, wherein the electrolyte fluid comprises a metal sulfate.

26. The battery of claim 25, wherein the metal sulfate is sodium sulfate.

27. The battery of claim 17, wherein the electrolyte fluid comprises water, sodium peroxydisulfate(aq) and sodium hydroxide.

28. The battery of any one of claims 1-27, which does not comprise a cathode in solid, gel, powder or paste form.

29. The battery of any one of claims 1-28, which does not comprise an anode in gel, powder or paste form.

30. The battery of any one of claims 1-29, which does not comprise a solid substrate having, in addition, positive and negative active materials disposed on opposing surfaces of the substrate.

31 . The battery of claim 30, wherein the solid substrate is a current collector.

32. The battery of any one of claims 1-31 , which does not comprise an ionexchange membrane.

33. The battery of any one of claims 1-32, which does not comprise an electrolyte in solid or gel form.

46

34. The battery of any one of claims 1-33, which does not comprise an electrolyte-containing porous separator disposed between the anodes and cathode current collectors in the same cell.

35. The battery of any one of claims 1-34, wherein the battery is a primary battery.

36. A method for producing hydrogen, which comprises providing a flow of electrolyte fluid through one or more cells in the battery of any one of claims 1-35, wherein the electrolyte fluid is a catholyte comprising an oxidant.

37. A method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more cells in the battery of any one of claims 1-35 while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant.

38. The method of any one of claims 36-37, wherein the electrolyte fluid is the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity.

39. The method of any one of claims 36-38, which does not result in the electrodeposition of solid material on the cathode current collectors.

40. A bipolar flow battery assembly comprising the battery of any one of claims 1-35 disposed in a casing.

41 . The battery assembly of claim 40, wherein the casing comprises glass or plastic.

42. The battery assembly of any one of claims 40-41 , wherein the casing is a unitary body.

43. The battery assembly of any one of claims 40-41 , wherein the casing is in the form of two or more connected portions.

44. The battery assembly of any one of claims 40-43, wherein the casing forms a source manifold, a receiving manifold, and a battery containment region between the source and receiving manifolds, wherein the battery is disposed in the battery containment region.

45. The battery assembly of claim 44, wherein the source and receiving manifolds are each configured to contain a bulk volume of electrolyte fluid, the manifolds and battery containment region being in fluid communication such that electrolyte fluid may flow from the source manifold through the battery cells to the receiving manifold.

46. The battery assembly of claim 45, wherein the casing further forms a plurality of flow channels extending from the source manifold to an inlet end of the battery containment region, and a plurality of flow channels extending from the receiving manifold to an outlet side of the battery containment region, the flow channels configured to provide for flow of an electrolyte fluid through the battery cells.

47. The battery assembly of claim 46, wherein the number of flow channels extending from each manifold is equal to the number of cells in the battery, each flow channel extending from the source manifold positioned to flow an electrolyte fluid into one cell and each flow channel extending from the receiving manifold positioned to receive electrolyte fluid from one cell.

48. The battery assembly of any one of claims 46-47, wherein the flow channels from the source manifold extend in a linear path to the inlet end of the battery containment region, and the flow channels from the receiving manifold extend in a linear path to the outlet side of the battery containment region.

49. The battery assembly of any one of claims 46-47, wherein the flow channels from the source manifold extend in a non-linear path to the inlet end of the battery containment region and/or the flow channels from the receiving manifold extend in a non-linear path to the outlet side of the battery containment region.

50. The battery assembly of claim 49, wherein the non-linear path of the flow channels comprises a serpentine or zig-zag path.

51 . The battery assembly of any one of claims 44-50, wherein the battery containment region comprises a plurality of slots formed by the casing, the slots having a width configured to receive and hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter.

52. The battery assembly of any one of claims 44-50, wherein the battery containment region comprises a plurality of slots formed by the casing, the slots having a width configured to receive a seal configured to hold in place an anode, cathode current collector, or fastened anode and current collector along at least a portion of its perimeter.

53. The battery assembly of claim 52, in which at least a portion of the seal also seals two connected portions of the casing at their interface.

54. The battery assembly of any one of claims 52-53, which comprises a seal disposed along at least a portion of the perimeter of one or more anodes.

55. The battery assembly of any one of claims 52-54, which comprises a seal disposed along at least a portion of the perimeter of one or more cathode current collectors.

56. The battery assembly of claim 55, which does not comprise a seal between the terminal cathode current collector and casing.

57. The battery assembly of any one of claims 52-56, which comprises a seal disposed along at least a portion of the perimeter of one or more pairs of fastened anodes and cathode current collectors.

58. The battery assembly of any one of claims 52-57, wherein the seal is in the form of a gasket.

59. The battery assembly of claim 58, wherein the gasket is a linear 0- ring.

60. The battery assembly of any one of claims 58-59, which further comprises a tape or lacquer disposed between the gasket and the anodes, cathode current collectors, or fastened anodes and cathode current collectors.

61 . The battery assembly of any one of claims 44-60, which further comprises one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly.

62. The battery assembly of any one of claims 44-61 , which further comprises one or more ports on the receiving manifold for withdrawing hydrogen gas from the assembly.

63. The battery assembly of any one of claims 61 -62, which further comprises a plate, comprising a plurality of orifices, disposed within each of the manifolds, the plate in the source manifold being disposed between an assembly inlet and flow channels leading to the battery containment region, and the plate in

49 the receiving manifold being disposed between the flow channels extending from the receiving manifold and an assembly outlet.

64. The battery assembly of any one of claims 46-63, which comprises a dividing wall that divides the manifolds and flow channels into isolated sections at a location along the length of the battery, wherein the source manifold in each section is in fluid communication with only flow channels and the receiving manifold in the same section.

65. The battery assembly of claim 64, which comprises one or more assembly section inlets for providing electrolyte fluid to the source manifold of each section and one or more assembly section outlets for withdrawing electrolyte fluid from the receiving manifold in each section.

66. The battery assembly of any one of claims 64-65, which comprises one or more ports on the receiving manifold of each section for withdrawing hydrogen gas.

67. The battery assembly of any one of claims 40-66, which comprises an anode terminal connector accessible on the exterior of the casing that is in electrical contact with the terminal anode, and a cathode current collector terminal connector accessible to the exterior of the casing that is in electrical contact with the terminal cathode current collector.

68. The battery assembly of claim 67, which comprises power connector system electrically connecting the terminal anode to its terminal connector and a power connector system electrically connecting the terminal cathode current collector to its terminal connector.

69. The battery assembly of claim 68, wherein each power connector systems comprises plug (male) and receptacle (female) contacts.

70. The battery assembly of claim 69, wherein the plug (male) contact is directly or indirectly in contact with a terminal connector and is mated to the receptacle (female) contact that is directly or indirectly in contact with the anode or cathode current collector.

71 . A system, which comprises the battery assembly of any one of claims 61-70 and an electrolyte fluid reservoir configured to store a bulk volume of electrolyte fluid, wherein the electrolyte fluid reservoir comprises an inlet for

50 receiving electrolyte fluid from one or more assembly outlets and an outlet for providing electrolyte fluid to one or more assembly inlets.

72. A method for producing hydrogen, which comprises providing a flow of electrolyte fluid through one or more cells in the battery assembly of any one of claims 40-70, wherein the electrolyte fluid is a catholyte comprising an oxidant.

73. A method for producing hydrogen and electricity, which comprises providing a flow of electrolyte fluid through one or more cells in the battery assembly of any one of claims 40-70 while the battery is connected to an electrical load, wherein the electrolyte fluid is a catholyte comprising an oxidant.

74. A method which comprises: providing the battery assembly of any one of claims 44-70; providing an electrolyte fluid in the source manifold; flowing the electrolyte fluid from the source manifold through one or more of the battery cells and into the receiving manifold; and recirculating at least a portion of electrolyte fluid from the receiving manifold to the source manifold.

75. The method of claim 74, which comprises one or more assembly inlets to the source manifold for providing electrolyte fluid to the assembly and one or more assembly outlets from the receiving manifold for withdrawing electrolyte fluid from the assembly, and which comprises recirculating at least a portion of electrolyte from the receiving manifold to the source manifold by flowing at least a portion of electrolyte fluid from an assembly outlet to an assembly inlet.

76. The method of claim 75, which comprises flowing at least a portion of electrolyte fluid from an assembly outlet to an electrolyte fluid reservoir, then flowing at least a portion of electrolyte fluid from the electrolyte fluid reservoir to an assembly inlet.

77. The method of any one of claims 74-76, which further comprises providing additional electrolyte fluid, or one or more components thereof, to the assembly during its operation.

78. The method of claim 77, which comprises providing additional electrolyte fluid, or one or more components thereof, by adding it to an electrolyte fluid reservoir that is in fluid communication with an assembly inlet.

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79. The method of any one of claims 74-78, which further comprises withdrawing spent electrolyte fluid, or one or more components thereof, from the assembly during its operation.

80. The method of any one of claims 72-79, wherein the electrolyte fluid is the only source of material reduced in the electrochemical reaction that produces the hydrogen or electricity.

81 . The method of any one of claims 72-80, which does not result in the electrodeposition of solid material on the cathode current collectors.

82. The method of any one of claims 72-81 , which comprises providing an approximately equal distribution of flow of electrolyte fluid through the series of battery cells.

52