Non-halogenated zinc additives for zinc halide secondary batteries

Abstract

An electrolyte for use in a zinc halide secondary electrochemical cell is provided that comprises about 20% to about 70% by weight of a zinc halide of the formula ZnY2, or any combination of zinc halides of the formula ZnY2, where Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof; about 10% to about 79% by weight of HO; and about 0.5% to about 20% by weight of one or more zinc additives. The one or more zinc additives include a first zinc additive, the first zinc additive being a salt that is not a zinc halide and has a molecular weight of about 65 Å. 3 Also provided is a zinc halide secondary battery comprising at least one electrochemical cell comprising at least one bipolar electrode and a zinc halide electrolyte. Also provided is a zinc halide secondary battery comprising a zinc metal reservoir.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 252,936, filed October 6, 2021, the disclosure of which is incorporated by reference in its entirety into this specification.

[0002] Technical Field

[0002] Described herein are zinc additives for zinc halide secondary batteries. [Background technology]

[0003] background

[0003] Zinc halide batteries have been developed as devices for storing electrical energy. Conventional zinc halide batteries (e.g., zinc bromide batteries) employ bipolar electrodes placed in a static, i.e., non-flowing, aqueous zinc bromide solution. The process of charging and discharging an electric current in a zinc halide battery generally involves the transfer of Zn 2+ / Zn(s) and X - This is achieved by the reaction of a redox couple such as / X2. When a battery is charged with an electric current, the following chemical reactions take place: Zinc 2+ +2e - →Zn 2X - →X2+2e - (wherein X is a halogen, such as Cl, Br, or I). Conversely, when the battery discharges current, the following chemical reaction occurs: Zn → Zn 2+ +2e - X2+2e - →2X - .

[0004]

[0004] These zinc halide storage batteries were formed with bipolar electrochemical cell stacks, where each electrode contained two poles, such that the anodic reaction occurred on one side of the electrode and the cathodic reaction occurred on the other side of the same electrode. In this situation, the bipolar electrodes were often configured as plates, and the cell stack was assembled to form a prismatic shape. During charging and discharging of the bipolar battery, the electrode plates act as conductors for adjacent cells; that is, each electrode plate acts as the anode of one cell and the cathode of the cell adjacent to it. In this prismatic battery geometry, the entire surface area of ​​the electrode plates that separate adjacent electrochemical cells transfers current from cell to cell.

[0005]

[0005] Thus, when a conventional bipolar zinc halide battery is charged, zinc metal is electrolytically plated on the anode side of the bipolar electrode plates while halogen species are formed on the cathode side of the electrode plates, and when the battery is discharged, the plated zinc metal is oxidized to free electrons that are conducted through the electrode plates to reduce the halogen species to produce halide anions.

[0006]

[0006] Zinc halide batteries require positively charged zinc ions and negatively charged halide ions to be available at the anode and cathode electrodes, respectively, during the charging process. However, in the high concentration aqueous electrolytes required for high energy batteries, zinc thermodynamically dissolves in [ZnBr3] - and [ZnBr4] 2- Zinc halide tends to form highly negatively charged complexes with halogens such as Zn2+, Zn3+, Zn4+, Zn5+, Zn6+, Zn7+, Zn8+, Zn9+, Zn10+, Zn11+, Zn12+, Zn13+, Zn14+, Zn2+, Zn3+, Zn4+, Zn5+, Zn6+, Zn15+, Zn16+, Zn17+, Zn2+, Zn18+, Zn2+, Zn19+, Zn2+, Zn2+, Zn3+, Zn4+, Zn5 ...

[0007]

[0007] Determining the chemical species of zinc bromide electrolytes has been studied with and without the addition of zinc chloride electrolyte. See, for example, Rajarathnam, GP, et al., “Chemical Speciation of Zinc-Halide Complexes in Zinc / Bromine Flow Battery Electrolytes,” J. Electrochemical Soc., 168, 070522 (2021). [ZnBr4] 2- , [ZnCl4] 2- The proportion of tetracoordinated zinc halides, such as , and mixed Cl / Br complexes, was found to increase with increasing salt concentration. The authors did not suggest a method to reduce the proportion of tetracoordinated zinc halides in electrolytes containing high concentrations of zinc halide salts. Summary of the Invention [Problem to be solved by the invention]

[0008] overview

[0008] This disclosure describes an aqueous electrolyte for use in a zinc halide secondary battery that improves electrolyte utilization and improves the coulombic efficiency of the zinc halide battery. This disclosure also describes the addition of a zinc metal reservoir to a zinc halide secondary battery to improve electrolyte utilization and improve the coulombic efficiency of the zinc halide battery. [Means for solving the problem]

[0009]

[0009] In one aspect, the present disclosure describes an electrolyte for use in a zinc halide secondary electrochemical cell comprising about 20% to about 70% by weight of a zinc halide of the formula ZnY2, or any combination of zinc halides of the formula ZnY2, where Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof, about 10% to about 79% by weight of H2O, and about 0.5% to about 20% by weight of one or more zinc additives. The one or more zinc additives include a first zinc additive, the first zinc additive being a salt that is not a zinc halide and having a molecular weight of about 65 Å. 3 The anion has a van der Waals volume greater than

[0010]

[0010] In some embodiments, the electrolyte comprises about 0.5% to about 3% by weight of the first zinc additive. In some embodiments, the molar ratio of total zinc ions to halide ions in the electrolyte is about 1:2 to about 1:3.

[0011]

[0011] In some embodiments, the electrolyte comprises about 0.5% to about 20% by weight of the first zinc additive. In some embodiments, the molar ratio of total zinc ions to halide ions in the electrolyte is about 1:1 to about 1:2.5.

[0012]

[0012] In some embodiments, the one or more zinc additives further include a second zinc additive, the second zinc additive being a salt that is not a zinc halide and having a molecular weight of about 65 Å. 3 In some embodiments, the electrolyte comprises about 0.5% to about 15% by weight of the second zinc additive.

[0013]

[0013] In some embodiments, the first zinc additive is zinc trifluoromethanesulfonate, zinc perfluorobutanesulfonate, zinc bis(trifluoromethane)sulfonimide, zinc methanesulfonate, zinc p-toluenesulfonate, zinc hexafluorophosphate, zinc tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, or any combination thereof.

[0014] In some embodiments, the electrolyte further comprises about 0.5% to about 15% by weight KBr and about 0.5% to about 15% by weight KCl.

[0015] In some embodiments, the electrolyte further comprises about 0.05% to about 20% by weight of one or more quaternary ammonium reagents, each of which has the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - wherein R 1 is hydrogen or an alkyl group, R 2 , R 3 , and R 4 are each independently R 1 is an alkyl group the same as or different from X - is a chloride ion or a bromide ion. In some embodiments, the one or more quaternary ammonium reagents comprise a first quaternary ammonium reagent at a concentration of about 0.05% to about 20% by weight.

[0016] In some embodiments, the first quaternary ammonium reagent is tetra-C chloride. 1~6 Alkylammonium or Tetra-C Bromide 1~6 In some embodiments, the first quaternary ammonium reagent is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

[0017] In some embodiments, the one or more quaternary ammonium reagents further comprise a second quaternary ammonium reagent. In some embodiments, the second quaternary ammonium reagent is represented by the formula N +(R 1 )(R 2 )(R 3 )(R 4 )X - wherein R 1 is hydrogen or an alkyl group, R 2 , R 3 , and R 4 are each independently R 1 is an alkyl group the same as or different from X - is a chloride ion or a bromide ion. In some embodiments, the concentration of the second quaternary ammonium reagent is from about 0.05% to about 20% by weight.

[0018]

[0018] In some embodiments, the second quaternary ammonium reagent is trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium chloride or bromide.

[0019] In some embodiments, the electrolyte further comprises about 0.2% to about 2.5% by weight of DME-PEG. In some embodiments, the electrolyte comprises a DME-PEG having a number average molecular weight of about 1000 amu, a DME-PEG having a number average molecular weight of about 2000 amu, or a combination thereof.

[0020]

[0020] In some embodiments, the electrolyte further comprises about 0.25% to about 5% by weight of a glycol, the glycol being ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, hexalene glycol, or any combination thereof.

[0021] In some embodiments, the electrolyte further comprises about 0.5% to about 10% by weight of glyme, where the glyme is monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof.

[0022]

[0022] In some embodiments, the electrolyte further contains less than 1 wt. % of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, or any combination thereof.

[0023] In some embodiments, the electrolyte further comprises 0.1% to 2% by weight of acetic acid, sodium acetate, potassium acetate, or any combination thereof.

[0024] In some embodiments, the electrolyte is used in a static secondary zinc halide battery.

[0025] In some embodiments, the electrolyte is used in a flow secondary zinc halide battery.

[0026]

[0026] In some embodiments, the utilization of zinc halide in an electrolyte of a zinc halide secondary electrochemical cell is increased by about 5% to about 40% compared to an equivalent electrolyte in a zinc halide secondary electrochemical cell not containing one or more zinc additives.

[0027]

[0027] Another aspect of the present disclosure describes a zinc halide secondary battery comprising at least one electrochemical cell comprising at least one bipolar electrode and a zinc halide electrolyte. The bipolar electrode comprises a bipolar electrode plate having an anode surface on one side of the bipolar electrode plate and a cathode surface on the other side of the bipolar electrode plate opposite the anode surface. The zinc halide electrolyte is in contact with the bipolar electrode plate. The zinc halide electrolyte is as described herein.

[0028] In some embodiments, the zinc halide electrolyte comprises about 20% to about 70% by weight of a zinc halide of formula ZnY2, or any combination of zinc halides of formula ZnY2, where Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof, about 10% to about 79% by weight of H2O, and about 0.5% to about 20% by weight of one or more zinc additives. The one or more zinc additives include a first zinc additive, the first zinc additive being a salt that is not a zinc halide and having a molecular weight of about 65 Å. 3 The anion has a van der Waals volume greater than

[0029]

[0029] In some embodiments, the zinc halide secondary battery is a zinc halide static secondary battery.

[0030]

[0030] In some embodiments, the zinc halide secondary battery is a zinc halide flow secondary battery.

[0031]

[0031] In some embodiments, the utilization of zinc halide in each electrolyte of at least one electrochemical cell of a zinc halide secondary battery is increased by about 5% to about 40% compared to an equivalent electrolyte in an electrochemical cell of a zinc halide secondary battery that does not contain one or more zinc additives.

[0032]

[0032] In some embodiments, the zinc halide secondary battery further includes a cathode assembly disposed on the cathode side of the bipolar electrode plate.

[0033] In some embodiments, the cathode assembly includes a carbon material affixed to a surface of a bipolar electrode plate using an adhesive layer.

[0034]

[0034] In some embodiments, the zinc halide secondary battery further includes two terminal electrochemical cells, each terminal electrochemical cell including a bipolar electrode, a terminal assembly, and a zinc halide electrolyte.

[0035]

[0035] Yet another aspect of the present disclosure describes a zinc halide secondary battery comprising a zinc metal reservoir. The zinc halide secondary battery also comprises at least one electrochemical cell comprising at least one bipolar electrode and a zinc halide electrolyte. The bipolar electrode comprises a bipolar electrode plate, having an anode surface on one side of the bipolar electrode plate and a cathode surface on the other side opposite the anode surface of the bipolar electrode plate. The zinc halide electrolyte is in contact with the bipolar electrode plate. The zinc halide electrolyte is either a zinc halide electrolyte as described herein or a zinc halide electrolyte without one or more zinc additives as described herein.

[0036] In some embodiments, the zinc metal reservoir is in at least one electrochemical cell and in contact with the electrolyte. In some embodiments, the zinc metal reservoir is also in contact with the anode of the at least one electrochemical cell. However, the zinc metal reservoir is not in contact with the cathode of the at least one electrochemical cell.

[0037]

[0037] In some embodiments, the zinc metal reservoir is composed of zinc metal in the form of a powder, granules, foil, sheet, wire, or shavings.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] These and other features, aspects, and advantages of the present disclosure will become better understood from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0039] [Figure 1]

[0039] FIG. 1 is an exploded view of an electrochemical cell according to one embodiment of the present disclosure. [Diagram 2]

[0040] FIG. 2 is a side view of a battery according to one embodiment of the present invention. [Diagram 3]

[0041] FIG. 3 is an exploded view of the battery of FIG. 2. [Figure 4]

[0042] FIG. 3 is an exploded view of an end assembly used in the battery of FIG. [Diagram 5]

[0043] FIG. 3 is a front view of a battery frame member used in the battery of FIG. 2. [Figure 6]

[0044] 1 shows representative average coulombic efficiency (%) as a function of zinc bromide utilization based on charge rate (%) for electrolytes with and without a zinc additive according to embodiments of the present disclosure. [Figure 7]

[0045] FIG. 1 shows a representative [ZnBr4]2− peak height ratio (%) as a function of zinc bromide concentration (M) for electrolytes with and without a zinc additive according to an embodiment of the present disclosure, as measured by Raman spectroscopy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Detailed Description of the Preferred Embodiments

[0046] The embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, similar reference numbers identify similar or identical elements. It should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be embodied in various forms. Well-known functions or structures are not described in detail to avoid obscuring the present disclosure with unnecessary details. Therefore, the specific structure and function details disclosed in this specification should not be interpreted as limiting, but merely as a basis for the claims and as a typical basis for teaching those skilled in the art to variously adopt the present disclosure into virtually any suitable detailed structure.

[0041]

[0047] I. Definition

[0048] As used herein, the terms "electrochemical cell" or "cell" are used interchangeably to refer to a device that can generate electrical energy from a chemical reaction or facilitate a chemical reaction through the introduction of electrical energy. The electrochemical cell may be a bipolar electrochemical cell or a terminal electrochemical cell.

[0042]

[0049] The term "battery" as used herein encompasses an electrical storage device that includes at least one electrochemical cell. For example, a battery may be composed of about 10-50 electrochemical cells in series. "Secondary batteries" are rechargeable, whereas "primary batteries" are not rechargeable. For secondary batteries of the present disclosure, the battery anode is designated as the positive electrode during discharge and the negative electrode during charging.

[0043]

[0050] As used herein, "electrolyte" refers to a substance that behaves as an electrically conductive medium. For example, an electrolyte facilitates the movement of electrons and cations within a cell. An electrolyte includes a mixture of substances such as an aqueous solution of a metal halide salt (e.g., ZnBr2, ZnCl2, etc.).

[0044]

[0051] As used herein, the term "electrode" refers to an electrical conductor used to contact a non-metallic portion of a circuit (e.g., a semiconductor, an electrolyte, or a vacuum). An electrode can also be referred to as either an anode or a cathode.

[0045]

[0052] The term "anode" as used herein refers to the negative electrode from which electrons flow during the discharge phase of a battery. The anode is also the electrode that undergoes chemical oxidation during the discharge phase. However, in secondary or rechargeable cells, the anode is the electrode that undergoes chemical reduction during the charge phase of the cell. The anode is formed from a conductive or semiconductive material, such as a metal (e.g., titanium or TiC-coated titanium), a metal oxide, a metal alloy, a metal composite, a semiconductor, and the like.

[0046]

[0053] The term "cathode" as used herein refers to the positive electrode into which electrons flow during the discharge phase of the battery. The cathode is also the electrode that undergoes chemical reduction during the discharge phase. However, in secondary or rechargeable cells, the cathode is the electrode that undergoes chemical oxidation during the charge phase of the cell. Cathodes are formed from conductive or semiconducting materials, such as metals, metal oxides, metal alloys, metal composites, semiconductors, and the like.

[0047]

[0054] The term "bipolar electrode" as used herein refers to an electrode that functions as an anode in one cell and a cathode in another cell. For example, in a battery, a bipolar electrode functions as an anode in one cell and a cathode in an immediately adjacent cell. In some examples, a bipolar electrode has two surfaces, a cathode surface and an anode surface, and these two surfaces are connected by a conductive material. For example, a bipolar electrode plate can have opposing surfaces, one surface being an anode surface and the other surface being a cathode surface, and the conductive material is the thickness of the plate between the opposing surfaces.

[0048]

[0055] The term "halide" as used herein refers to a binary compound of a halogen with another element or radical that is less electronegative (or more electropositive) than the halogen and forms a fluoride, chloride, bromide, iodide, or astatide compound.

[0049]

[0056] The term "halogen" as used herein refers to any of the elements fluorine, chlorine, bromine, iodine, and astatine, which occupy Group VIIA (17) of the periodic table. The halogens are reactive nonmetallic elements that form strongly acidic compounds with hydrogen and from which simple salts can be prepared.

[0050]

[0057] The term "anion" as used herein refers to any chemical entity that has one or more permanent negative charges. Examples of anions include, but are not limited to, fluoride, chloride, bromide, iodide, arsenate, phosphate, arsenite, hydrogen phosphate, dihydrogen phosphate, sulfate, nitrate, hydrogen sulfate, nitrite, thiosulfate, sulfite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, hypobromite, carbonate, chromate, bicarbonate, dichromate, acetate, formate, cyanide, amide, cyanate, peroxide, thiocyanate, oxalate, hydroxide, and permanganate.

[0051]

[0058] As used herein, "titanium-based materials" include, but are not limited to, titanium (in any oxidation state), TiC, alloys of TiC, e.g., TiC x M (x is 0, 1, 2, 3, or 4 and M is a metal), titanium carbides, non-stoichiometric titanium-carbon compounds, and combinations thereof.

[0052]

[0059] As used herein, "titanium carbide" is used interchangeably with "titanium carbide material" and includes, but is not limited to, TiC, alloys of TiC, e.g., TiC x M (x is 0, 1, 2, 3, or 4 and M is a metal), titanium carbides, non-stoichiometric titanium-carbon compounds, and combinations thereof.

[0053]

[0060] As used herein, the term "zinc metal" refers generally to Zn(0) or Zn 0 Also known as zinc ion.

[0054]

[0061] For purposes of this disclosure, the term "dimethyl ether poly(ethylene glycol)," "DME-PEG," has the following structure: [ka] where n is an integer. DME-PEG1000 is a polymer having a number average molecular weight (M n ), and DME-PEG2000 refers to a DME-PEG polymer having a number average molecular weight (M) of about 2000 amu. n )

[0055]

[0062] As used herein, the term "dimethyl ether" refers to an organic compound having the formula CH3OCH3.

[0056]

[0063] The term "total concentration" as used herein refers to the combined total concentration (e.g., weight percent) of each component of a material class or reagent class (e.g., quaternary ammonium reagents). In one example, the total concentration of one or more quaternary ammonium reagents in an electrolyte is the sum of the concentrations (e.g., weight percent) of each component quaternary ammonium reagent present in the electrolyte. Thus, if an electrolyte contains three quaternary ammonium reagents, the total concentration of the three quaternary ammonium reagents is the sum of the concentrations of each of the three quaternary ammonium reagents present in the electrolyte. And, if an electrolyte contains only one quaternary ammonium reagent, the total concentration of the quaternary ammonium reagents is simply the concentration of the single quaternary ammonium reagent present in the electrolyte.

[0057]

[0064] The term "alcohol" as used herein refers to any organic compound whose molecule contains one or more hydroxyl groups attached to a carbon atom. Examples of alcohols include methanol, ethanol, 1-propanol (i.e., n-propanol), 2-propanol (i.e., isopropanol), 1-butanol (i.e., n-butanol), sec-butanol, isobutanol, tert-butanol, 1-pentanol, or any combination thereof.

[0058]

[0065] As used herein, the term "hydroxyl group" refers to an --OH group.

[0059]

[0066] The term "glycol" as used herein refers to any of a class of organic compounds that belong to the alcohol family. In a glycol molecule, two hydroxyl (-OH) groups are attached to different carbon atoms. Examples of glycols include C 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179 ... 1~10 Other examples of glycols include substituted ethylene glycol and substituted propylene glycol.

[0060]

[0067] As used herein, the term "weight percent" and its abbreviations "wt.%" or "wt%" are used interchangeably to refer to the product of the mass of one or more ingredients divided by the total mass of a mixture or product containing those ingredients, multiplied by 100:

number

[0061]

[0068] The term "quaternary ammonium reagent" as used herein refers to any compound, salt, or material that contains a quaternary nitrogen atom. Non-limiting examples of quaternary ammonium reagents include, for example, tetraalkylammonium halides (e.g., tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, alkyl-substituted pyridinium halides, alkyl-substituted morpholinium halides, combinations thereof, etc.), heterocyclic ammonium halides (e.g., alkyl-substituted pyrrolidinium halides (e.g., N-methyl-N-ethylpyrrolidinium halides or N-ethyl-N-methylpyrrolidinium halides), alkyl-substituted pyridinium halides, alkyl-substituted morpholinium halides, viologens with at least one quaternary nitrogen atom, combinations thereof, etc.), or any combination thereof. Tetraalkylammonium halides may be symmetrically or asymmetrically substituted with respect to the substituents of the quaternary nitrogen atom.

[0062]

[0069] As used herein, the term "viologen" refers to any bipyridinium derivative of 4-4'-bipyridine.

[0063]

[0070] The term "ammonium bromide complexing agent" as used herein refers to any compound, salt, or material that contains a quaternary nitrogen atom, which is not part of an imidazolium, pyridinium, pyrrolidinium, morpholinium, or phosphonium moiety. Examples of ammonium bromide complexing agents include tetraethylammonium bromide, trimethylpropylammonium bromide, dodecyltrimethylammonium bromide, cetyltriethylammonium bromide, and hexyltrimethylammonium bromide.

[0064]

[0071] The term "imidazolium bromide complexing agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom, which is part of the imidazolium moiety. Examples of imidazolium bromide complexing agents include 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-2,3-dimethylimidazolium bromide, 1-decyl-3-methylimidazolium bromide, 1-butyl-2,3-dimethylimidazolium bromide, 1-methyl-3-octylimidazolium bromide, and 1-methyl-3-hexylimidazolium bromide.

[0065]

[0072] The term "pyridinium bromide complexing agent" as used herein refers to any compound, salt, or substance that contains a quaternary nitrogen atom, which is part of a pyridinium moiety. Examples of pyridinium bromide complexing agents include 1-ethyl-2-methylpyridinium bromide, 1-ethyl-3-methylpyridinium bromide, 1-ethyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-3-methylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, and 1-hexylpyridinium bromide.

[0066]

[0073] As used herein, the term "pyrrolidinium bromide complexing agent" refers to any compound, salt, or material that contains a quaternary nitrogen atom, which is part of a pyrrolidinium moiety. An example of a pyrrolidinium bromide complexing agent is 1-butyl-1-methylpyrrolidinium bromide.

[0067]

[0074] As used herein, the term "morpholinium bromide complexing agent" refers to any compound, salt, or substance that contains a quaternary nitrogen atom, which is part of a morpholinium moiety. An example of a morpholinium bromide complexing agent is N-ethyl-N-methylmorpholinium bromide.

[0068]

[0075] As used herein, the term "phosphonium bromide complexing agent" refers to any compound, salt, or material that contains a quaternary phosphonium atom. An example of a phosphonium bromide complexing agent is tetraethylphosphonium bromide.

[0069]

[0076] The term "crown ether" as used herein refers to a cyclic compound consisting of a ring containing at least three ether groups. Examples of crown ethers include 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and diaza-18-crown-6.

[0070]

[0077] As used herein, an "alkyl" group refers to a saturated aliphatic hydrocarbon group containing 1 to 20 (e.g., 1 to 16, 1 to 12, 1 to 8, 1 to 6, or 1 to 4) carbon atoms. The alkyl group can be straight-chained or branched. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, and cetyl.

[0071]

[0078] As used herein, an "aryl" group, used alone or as part of a larger moiety such as "aralkyl", "aralkoxy", or "aryloxyalkyl", refers to a monocyclic (e.g., phenyl); a bicyclic (e.g., indenyl, naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl); a tricyclic (e.g., fluorenyl, tetrahydrofluorenyl, anthracenyl, or tetrahydroanthracenyl); or a benzo-fused group having three rings. For example, a benzo-fused group is one having two or more C 4~8 Contains a phenyl fused to a carbocyclic moiety. The aryl may be optionally substituted with one or more substituents including aliphatic (e.g., alkyl, alkenyl, or alkynyl); cycloalkyl; (cycloalkyl)alkyl; heterocycloalkyl; (heterocycloalkyl)alkyl; aryl; heteroaryl; alkoxy; cycloalkyloxy; heterocycloalkyloxy; aryloxy; heteroaryloxy; aralkyloxy; heteroaralkyloxy; aroyl; heteroaroyl; amino; aminoalkyl; nitro; carboxy; carbonyl (e.g., alkoxycarbonyl, alkylcarbonyl, aminocarbonyl, (alkylamino)alkylaminocarbonyl, arylaminocarbonyl, heteroarylaminocarbonyl; or sulfonylcarbonyl); arylalkylcarbonyloxy; sulfonyl (e.g., alkylsulfonyl or aminosulfonyl); sulfinyl (e.g., alkylsulfinyl); sulfanyl (e.g., alkylsulfanyl); cyano; halo; hydroxyl; acyl; mercapto; sulfoxy; urea; thiourea; sulfamoyl; sulfamide; oxo; or carbamoyl. Alternatively, the aryl can be unsubstituted.

[0072]

[0079] Examples of substituted aryls include haloaryls, alkoxycarbonylaryls, alkylaminoalkylaminocarbonylaryls, p,m-dihaloaryls, p-amino-p-alkoxycarbonylaryls, m-amino-m-cyanoaryls, aminoaryls, alkylcarbonylaminoaryls, cyanoalkylaryls, alkoxyaryls, aminosulfonylaryls, alkylsulfonylaryls, aminoaryls, p-halo-m-aminoaryls, cyanoaryls, hydroxyalkylaryls, alkoxyalkylaryls, hydroxyaryls, carboxyalkylaryls, dialkylaminoalkylaryls, m-heteroalicyclic-o-alkylaryls, heteroarylaminocarbonylaryls, nitroalkylaryls, alkylsulfonylaminoalkylaryls, heteroalicycliccarbonylaryls, alkylsulfonylalkylaryls, cyanoalkylaryls, heteroalicycliccarbonylaryls, alkylcarbonylaminoaryls, hydroxyalkylaryls, alkylcarbonylaryls, aminocarbonylaryls, alkylsulfonylaminoaryls, dialkylaminoaryls, alkylaryls, and trihaloalkylaryls.

[0073]

[0080] As used herein, an "aralkyl" group refers to an alkyl group substituted with an aryl group (e.g., C 1~4 "Aralkyl" refers to an alkyl group substituted with a heteroaryl. Both "alkyl" and "aryl" are defined herein. An example of an aralkyl group is benzyl. A "heteroaralkyl" group refers to an alkyl group substituted with a heteroaryl.

[0074]

[0081] As used herein, a "cycloalkyl" group refers to a saturated carbocyclic monocyclic, bicyclic, tricyclic, or polycyclic (fused or bridged) ring of 3 to 10 (e.g., 5 to 10) carbon atoms. Non-limiting examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like. Non-limiting examples of bicyclic cycloalkyl groups include octahydro-indenyl, decahydro-naphthyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, bicyclo[3.3.1]nonyl, bicyclo[3.3.2.]decyl, bicyclo[2.2.2]octyl, bicyclo[2.2.1]heptanyl, bicyclo[3.1.1]heptanyl, and the like. Non-limiting examples of polycyclic groups include adamantyl, cubyl, norbornyl, and the like. Cycloalkyl rings may be optionally substituted at any chemically feasible position on the ring.

[0075]

[0082] As used herein, a "heterocycloalkyl" group refers to a 3- to 10-membered mono- or bicyclic (fused or bridged) (e.g., 5- to 10-membered mono- or bicyclic) saturated ring structure in which one or more of the ring atoms is a heteroatom (e.g., N, O, S, or combinations thereof). Examples of heterocycloalkyl groups include optionally substituted piperidyl, piperazyl, tetrahydropyranyl, tetrahydrofuryl, 1,4-dioxolanyl, 1,4-dithianyl, 1,3-dioxolanyl, oxazolidyl, isoxazolidyl, morpholinyl, thiomorpholyl, octahydro-benzofuryl, octahydro-chromenyl, octahydro-thiochromenyl, octahydro-indolyl, octahydro-pyridinyl, decahydro-quinolinyl, octahydro-benzo[b]thiophenyl, 2-oxa-bicyclo[2,2.2]octyl, 1-aza-bicyclo[2.2.2]octyl, 3-aza-bicyclo[3.2.1]octanyl, 2,6-dioxa-tricyclo[3.3.1.0 ... 3,7]nonyl, tropane. Monocyclic heterocycloalkyl groups may be fused to a phenyl moiety, such as tetrahydroisoquinoline. Heterocycloalkyl ring structures may be optionally substituted at any chemically feasible position on the ring.

[0076]

[0083] As used herein, a "heteroaryl" group refers to a monocyclic, bicyclic, or tricyclic ring system having 4 to 15 ring atoms, in which one or more of the ring atoms is a heteroatom (e.g., N, O, S, or a combination thereof) and one or more rings of the bicyclic or tricyclic ring system are aromatic. Heteroaryl groups include benzo-fused ring systems having 2 to 3 rings. For example, benzo-fused groups include 1 or 2 C 4~8 Included are benzo fused to a heterocyclic moiety (eg, indolyl, indolyl, isoindolyl, 3H-indolyl, indolinyl, benzo[b]furyl, benzo[b]thiophenyl, quinolinyl, or isoquinolinyl). Some examples of heteroaryl include azetidinyl, pyridyl, 1H-indazolyl, furyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, tetrazolyl, benzofuryl, isoquinolinyl, benzthiazolyl, xanthene, thioxanthene, phenothiazine, dihydroindole, benzo[1,3]dioxole, benzo[b]furyl, benzo[b]thiophenyl, indazolyl, benzimidazolyl, benzthiazolyl, pryl, cinnolyl, quinolyl, quinazolyl, cinnolyl, phthalazyl, quinazolyl, quinoxalyl, isoquinolyl, 4H-quinolizyl, benzo-1,2,5-thiadiazolyl, or 1,8-naphthyridyl. Heteroaryl also includes bipyridine compounds.

[0077]

[0084] When an element or layer is referred to as being "on," "engaged with," "connected with," "coupled with," or "connected with" another element or layer, it can be directly on, directly engaged with, directly connected with, directly bonded with, or directly connected to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged with," "directly connected with," "directly bonded with," or "directly connected with" another element or layer, there may not be intervening elements or layers. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0078]

[0085] Terms such as top, bottom, upper, lower, right, left, etc. may be used herein to describe the location of various elements relative to other elements. These terms represent the location of the elements in an exemplary configuration. However, it will be apparent to one of ordinary skill in the art that the battery frame members may be rotated in space without departing from the present disclosure, and therefore these terms should not be used to limit the scope of the present disclosure.

[0079]

[0086] As used herein, "overmolding" refers to the process of adding an additional layer of material over an existing part or component by injection molding.

[0080]

[0087] As used herein, a "plurality" refers to two or more of a described element. In some embodiments, a plurality refers to three or more, four or more, or five or more of a described element.

[0081]

[0088] As used herein, "chemically compatible" refers to a material that does not interfere with the chemistry of the electrochemical cell in a manner that significantly and adversely affects the performance of the electrochemical cell. Chemically compatible materials are chemically compatible with the electrolyte (e.g., zinc halide electrolyte, alkaline electrolyte), as well as the anode and cathode materials.

[0082]

[0089] As used herein, "chemically inert" refers to a material that does not chemically react in any significant way with the electrolyte, anode, or cathode of an electrochemical cell.

[0083]

[0090] As used herein, "substantially rectangular" refers to a shape that is not strictly rectangular, but has four sides and has the appearance of a rectangle when viewed.

[0084]

[0091] As used herein, "substantially parallel" means that the surfaces of a substantially parallel object are no more than 2° (2 degrees) from parallel over the length of the surfaces.

[0085]

[0092] II. Electrochemical Cells and Batteries

[0093] In one aspect, the present disclosure provides an electrolyte for use in zinc halide secondary electrochemical cells and batteries. In another aspect, the present disclosure provides a zinc halide secondary battery comprising the electrolyte. The zinc halide secondary battery may be a zinc halide static (non-flowing) secondary battery or may be a zinc halide flow secondary battery. In yet another aspect, the present disclosure provides a zinc halide secondary battery comprising a zinc metal reservoir. The electrolyte of the zinc halide secondary battery is either an electrolyte comprising one or more zinc additives as described herein or an electrolyte not comprising one or more zinc additives as described herein.

[0086]

[0094] A. Electrolyte

[0095] The present disclosure provides electrolytes useful in flowing or non-flowing (i.e., static) zinc halide secondary electrochemical cells and batteries in which the zinc halide (e.g., zinc bromide, zinc chloride, or any combination of the two) present in the electrolyte functions as the electrochemically active material. These electrochemical cells and batteries are described below.

[0087]

[0096] The electrolyte of the present disclosure is an aqueous zinc halide electrolyte in contact with the bipolar electrode plate of at least one bipolar electrode of the electrochemical cell. In some embodiments, the electrolyte is interposed between the inner surface of the terminal end plate, the cathode assembly, the front surface of the bipolar electrode, and the inner surface of the frame, if present. In some embodiments, the zinc halide secondary battery is a zinc halide flow secondary battery in which the electrolyte flows through all of the bipolar cells. In another embodiment, the zinc halide secondary battery is a zinc halide static secondary battery in which the electrolyte is mechanically separated within each bipolar cell.

[0088]

[0097] In a zinc bromide secondary battery embodiment, for example, positively charged zinc ions and negatively charged bromide ions must be available at the anode and cathode electrodes, respectively, during the charging process. Bromide anions at or near the cathode electrode (e.g., the carbon material of the cathode assembly) exposed to the electrolyte are oxidized to bromine when the electrochemical cell or battery is charged. Conversely, bromine is reduced to bromide anions during discharge. The conversion between bromine and bromide anions at or near the cathode electrode can be represented as follows:

[0098] Br2+2e - →2Br -

[0089]

[0099] However, in the highly concentrated aqueous electrolytes required for higher energy batteries, zinc thermodynamically favors forming highly negatively charged complexes with the halogens. In the bromide example, this is specifically [ZnBr3]. -and [ZnBr4] 2- These negatively charged zinc species then migrate to the cathode instead of the anode during the charging process, resulting in a zinc-starved anode while the zinc halide utilization is high. This limits electrolyte utilization and requires the battery cell to contain more zinc halide than would theoretically be needed if only positively charged zinc ions and negatively charged halide ions were in solution, resulting in increased battery cost.

[0090]

[0100] The inventors of the present disclosure have discovered that [ZnBr3] - or [ZnBr4] 2- We have found that one route to reducing the formation of highly negatively charged complexes with halogens, such as [ZnBr3], is to add zinc to the electrolyte in the form of one or more zinc additives that are zinc salts with non-halogen anions. The addition of zinc salts that do not contain halide anions increases the molar ratio of zinc ions to halide ions in the electrolyte, resulting in [ZnBr3]. - or [ZnBr4] 2- However, the one or more zinc additives must contain an electrochemically inactive non-halide anion. Furthermore, both the zinc cation and the non-halide anion must also be highly soluble in the resulting aqueous electrolyte to allow for the dissolution of a sufficient amount of the one or more zinc additives to affect the molar ratio of zinc ions to halide ions. The one or more zinc additives of the present disclosure meet these requirements and form highly negatively charged zinc complexes ([ZnBr3] - or [ZnBr4] 2- etc.), but also provides other benefits to zinc halide batteries, as described below.

[0091]

[0101] One aspect of the present disclosure provides an electrolyte for use in a zinc halide secondary electrochemical cell comprising about 20% to about 70% by weight of a zinc halide of formula ZnY2, or any combination of zinc halides of formula ZnY2, where Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof; about 10% to about 79% by weight of HO; and about 0.5% to about 20% by weight of one or more zinc additives. The one or more zinc additives include a first zinc additive. The first zinc additive is a salt that is not a zinc halide and has a pH of about 65 Å. 3 The anion has a van der Waals volume greater than

[0092]

[0102] In some embodiments, the electrolyte comprises from about 0.5% to about 3% by weight of one or more first zinc additives, and in some embodiments, the molar ratio of total zinc ions to halide ions in the electrolyte is from about 1:2 to about 1:3.

[0093]

[0103] In some embodiments, the electrolyte comprises from about 0.5% to about 20% by weight of one or more first zinc additives, and in some embodiments, the molar ratio of total zinc ions to halide ions in the electrolyte is from about 1:1 to about 1:2.5.

[0094]

[0104] In some embodiments, the one or more zinc additives further comprise a second zinc additive different from the first zinc additive. The second zinc additive is a non-zinc halide salt and has a molecular weight of about 65 Å. 3 In some embodiments, the electrolyte comprises about 0.5% to about 15% by weight of the second zinc additive.

[0095]

[0105] Non-limiting examples of the first zinc additive of the present disclosure include, for example, zinc trifluoromethanesulfonate, zinc perfluorobutanesulfonate, zinc bis(trifluoromethane)sulfonimide, zinc methanosulfonate, zinc p-toluenesulfonate, zinc hexafluorophosphate, zinc tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, or any combination thereof.

[0096]

[0106] Non-limiting examples of second zinc additives of the present disclosure include, for example, zinc nitrate, zinc sulfate, zinc perchlorate, zinc tetrafluoroborate, or any combination thereof.

[0097]

[0107] The measurement of van der Waals volume is well known to those skilled in the art. For example, see Zhao, YH, et al., "Fast Calculation of van der Waals Volume as a Sum of Atomic and Bond Contributions and Its Application to Drug Compounds," J. Org. Chem., 68, 7368-7373 (2003), which is incorporated herein by reference and may be used within the scope of the present disclosure. The van der Waals volumes of some examples of the first zinc additive of the present disclosure are shown in Table 1 below.

[0098] [Table 1]

[0099]

[0108] The van der Waals volumes of some examples of the second zinc additive of the present disclosure are shown in Table 2 below.

[0100] [Table 2]

[0101]

[0109] As used herein, the "zinc halide utilization" of an electrolyte refers to the moles of zinc electrochemically consumed divided by the moles of zinc available in the electrolyte of the battery. It has also been found that the addition of one or more zinc additives of the present disclosure to the electrolyte advantageously improves the utilization of the zinc halide in the electrolyte of a zinc halide secondary electrochemical cell. In some embodiments, the utilization of the zinc halide in the electrolyte of a zinc halide secondary electrochemical cell is increased by about 5% to about 40% compared to the equivalent electrolyte of a zinc halide secondary electrochemical cell that does not include one or more zinc additives.

[0102]

[0110] As used herein, the "coulombic efficiency" of a secondary battery refers to the ratio of discharge capacity to charge capacity within the same cycle. It has also been found that the addition of one or more zinc additives of the present disclosure to an electrolyte advantageously improves the coulombic efficiency of a zinc halide secondary electrochemical cell. In some embodiments, the coulombic efficiency of a zinc halide secondary electrochemical cell is increased by about 5% to about 25% compared to a zinc halide secondary electrochemical cell that does not include one or more zinc additives. As can be seen from the following examples, the higher the utilization of zinc halide in an electrolyte that includes one or more zinc additives of the present disclosure, the higher the coulombic efficiency that can be achieved.

[0103]

[0111] The inventors of the present disclosure have also unexpectedly discovered that the addition of one or more zinc additives of the present disclosure to an electrolyte improves the morphology of the zinc plating and increases the viscosity of the electrolyte. The increased viscosity of the electrolyte reduces the amount of polyhalogen (Br3 - or Br5 - (e.g., Zn) can remain at the cathode and slow the diffusion of polyhalogen species from the cathode. In particular, the zinc additive allows higher viscosities to be achieved without a linear decrease in electrical conductivity. Furthermore, some of the zinc additives are highly soluble in aqueous high-concentration zinc halide electrolytes.

[0104]

[0112] In some embodiments, the electrolyte further comprises other components suitable within the scope of the present disclosure. For example, additional components in the electrolyte described in International Publication No. WO 2016 / 057477, filed October 6, 2015, International Publication No. WO 2017 / 172878, filed March 29, 2017, U.S. Patent No. 10,276,872, filed March 29, 2016, and U.S. Patent Application Publication No. 2011 / 025355311, filed March 21, 2011 (all of which are incorporated herein by reference) can be used within the scope of the present disclosure.

[0105]

[0113] In some embodiments, the electrolyte further comprises about 0.5% to about 15% by weight KBr and about 0.5% to about 15% by weight KCl.

[0106]

[0114] In some embodiments, the electrolyte further comprises from about 0.05% to about 20% by weight of one or more quaternary ammonium reagents, each of which has the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - wherein R 1 is hydrogen or an alkyl group, R 2 , R 3 , and R 4 are each independently R 1 is an alkyl group the same as or different from X - is a chloride ion or a bromide ion. In some embodiments, the one or more quaternary ammonium reagents include a first quaternary ammonium reagent having a concentration of about 0.05% to about 20% by weight.

[0107]

[0115] In some embodiments, the first quaternary ammonium reagent is tetra-C chloride. 1~6 Alkylammonium or Tetra-C Bromide 1~6In some embodiments, the first quaternary ammonium reagent is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

[0108]

[0116] In some embodiments, the one or more quaternary ammonium reagents further comprise a second quaternary ammonium reagent. In some embodiments, the second quaternary ammonium reagent is represented by the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - wherein R 1 is hydrogen or an alkyl group, R 2 , R 3 , and R 4 are each independently R 1 is an alkyl group the same as or different from X - is a chloride ion or a bromide ion. In some embodiments, the concentration of the second quaternary ammonium reagent is from about 0.05% to about 20% by weight.

[0109]

[0117] In some embodiments, the second quaternary ammonium reagent is trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium chloride or bromide.

[0110]

[0118] In some embodiments, the electrolyte further comprises about 0.25% to about 5% by weight of a glycol, the glycol being ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, hexalene glycol, or any combination thereof, in one embodiment, the glycol is neopentyl glycol.

[0111]

[0119] In some embodiments, the electrolyte further comprises about 0.5% to about 10% by weight of glyme, where the glyme is monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof, hi one embodiment, the glyme is tetraglyme.

[0112]

[0120] In some embodiments, the electrolyte further comprises less than 1 wt. % of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, or any combination thereof.

[0113]

[0121] In some embodiments, the electrolyte further comprises 0.1% to 2% by weight of acetic acid, sodium acetate, potassium acetate, or any combination thereof.

[0114]

[0122] In some embodiments, the electrolyte includes about 25% to about 45% by weight of a zinc halide of formula ZnY2, or any combination of zinc halides of formula ZnY2; about 25% to about 50% by weight of HO; about 1% to about 20% by weight of one or more zinc additives; about 0.5% to about 15% by weight of KBr; about 0.5% to about 15% by weight of KCl; and about 0.05% to about 20% by weight of one or more quaternary ammonium reagents.

[0115]

[0123] In some embodiments, the electrolyte is used in a static zinc halide electrochemical cell. In some embodiments, the electrolyte further comprises about 0.2% to about 2.5% by weight of DME-PEG. In some embodiments, the electrolyte comprises DME-PEG having a number average molecular weight of about 1000 amu, DME-PEG having a number average molecular weight of about 2000 amu, or a combination thereof.

[0116]

[0124] In some embodiments, the electrolyte is used in a zinc halide flow electrochemical cell. In some embodiments, the electrolyte does not include DME-PEG.

[0117]

[0125] B. Bipolar Electrochemical Cell

[0126] Another aspect of the present disclosure provides a zinc halide secondary battery comprising the above-described electrolyte. The zinc halide secondary battery may be a zinc halide static (non-flowing) secondary battery or a zinc halide flow secondary battery.

[0118]

[0127] B.1. Static Bipolar Electrochemical Cell

[0128] 2 and 3, an embodiment of a static (non-flowable) bipolar zinc halide secondary electrochemical battery 500 of the present disclosure includes at least one bipolar electrochemical cell and two end electrochemical cells. In some embodiments, the bipolar electrochemical battery includes approximately 10-50 bipolar electrochemical cells in series and the two end electrochemical cells. For example, in one embodiment, the bipolar electrochemical battery includes 26 bipolar electrochemical cells in series and the two end electrochemical cells. In another embodiment, the bipolar electrochemical battery includes 38 bipolar electrochemical cells in series and the two end electrochemical cells.

[0119]

[0129] B.1.i. Bipolar electrochemical cells

[0130] At least one bipolar electrochemical cell includes a bipolar electrode 502, a battery frame member 514, and a zinc halide electrolyte. The terminal electrochemical cell includes a bipolar electrode 502, a battery frame member 514, a terminal assembly 504, a terminal end plate 505, and a zinc halide electrolyte.

[0120]

[0131] FIG. 1 shows an exploded view of an electrochemical cell 100 of the present disclosure, including a bipolar electrode 102, a battery frame member 114, an end assembly 104, and the zinc halide electrolyte described above.

[0121]

[0132] 1. Bipolar electrodes

[0133] 3 and 4, the bipolar electrode 502 of the present disclosure includes a bipolar electrode plate 702 having an anode surface on one side of the bipolar electrode plate and a cathode surface on the other side opposite the anode surface of the bipolar electrode plate. On the cathode surface of the bipolar electrode plate 702, a carbon material 624 is attached to the surface of the bipolar electrode plate 702 using an adhesive layer 711 such that the carbon material 624 is in electrical communication with at least the surface of the bipolar electrode plate 702. Since the structure of the bipolar electrode 502 is the same as that of the bipolar electrode of the end assembly 504, the structure of the bipolar electrode 502 will be described with reference to the exploded view of the end assembly 504 in FIG.

[0122]

[0134] The bipolar electrodes 502 of the present disclosure are configured such that zinc metal is plated on the anode electrode surface to produce halide or mixed halide species that are reversibly sequestered in the carbon material during charging of the electrochemical cell. Conversely, these electrodes oxidize the plated zinc metal to Zn during discharging of the electrochemical cell. 2+ The catalyst is configured to generate a cation and reduce a halide or mixed halide species to the corresponding anion.

[0123]

[0135] a.Bipolar electrode plate

[0136] The bipolar electrode plate 702 includes a conductive coating or film that is relatively inert to the zinc halide electrolyte used in the electrochemical cell. In some embodiments, the coating or film covers a portion of the surface of the bipolar electrode plate 702. In some embodiments, the bipolar electrode plate 702 includes titanium, titanium oxide, TiC, TIN, or graphite. Optionally, the bipolar electrode plate 702 is a plastic-based material that is rendered conductive by compounding a conductive filler into the plastic. In some embodiments, the bipolar electrode plate 702 includes a titanium material (e.g., titanium or titanium oxide). In another embodiment, the bipolar electrode plate 702 includes a titanium material coated with a titanium carbide material. In these embodiments, at least a portion of the surface of the bipolar electrode plate 702 is coated with a titanium carbide material. In some embodiments, the bipolar electrode plate 702 includes a conductive carbon material (e.g., a graphite plate). In some cases, the bipolar electrode plate 702 includes a graphite plate coated with a titanium carbide material. In these embodiments, at least a portion of the surface of the bipolar electrode plate 702 is coated with a titanium carbide material. In some embodiments, the bipolar electrode plate 702 comprises a conductive plastic. Any suitable conductive plastic may be used within the scope of the present invention. Conductive plastics are well known to those skilled in the art and will not be described in detail herein. Such conductive plastic-based materials may include a base resin polymer and carbon black, graphite, fumed silica, or combinations thereof. For example, the conductive plastics described in U.S. Pat. No. 4,169,816, filed Mar. 6, 1978, which is incorporated herein by reference, may be used within the scope of the present disclosure.

[0124]

[0137] In some embodiments, the bipolar electrode plates may be substantially rectangular, with one dimension clearly larger than the other to give the appearance of a rectangle. In the XYZ coordinate space shown in FIG. 3, the width dimension of the end assembly 504 is the X direction, which is the larger dimension compared to the Y dimension. The height dimension of the end assembly 504 is the Y direction, which is the smaller dimension compared to the X dimension. This gives the illustrated end assembly 504, and the battery depicted in the exploded view, a rectangular appearance. The Z direction represents the depth (i.e., thickness) of the illustrated battery components. As seen in FIGS. 3 and 4, the orientation of the bipolar electrode plates and the orientation of the carbon material are complementary to the orientation of the end assembly 504, such that the width and height of the bipolar electrode plates and the width and height of the carbon material share approximately the same orientation, respectively, as the width and height of the end assembly 504 depicted in FIG. 7.

[0125]

[0138] The bipolar electrode plate may be formed by stamping or other suitable process. A portion of the surface of the bipolar electrode plate 702 may be optionally surface treated (e.g., coated, etc.) to enhance the electrochemical properties of the cell or battery. The inner surface of the bipolar electrode plate may include an electrochemically active area associated with or defined by the formation of a zinc metal layer upon charging of the cell or battery. In some embodiments, the inner surface of the electrode plate may be sandblasted or otherwise treated in the electrochemically active area. In another embodiment, the outer surface may also be sandblasted in the electrochemically active area associated with the area enclosed by the cathode assembly.

[0126]

[0139] For example, in some embodiments, at least a portion of the inner surface, at least a portion of the outer surface, or at least a portion of both surfaces are treated (e.g., sandblasted) to provide a rough surface. In some cases, at least a portion of the inner surface of the bipolar electrode plate is treated (e.g., sandblasted) to provide a rough surface. In some cases, the area of ​​the inner surface that is treated to provide a rough surface is substantially defined by a periphery of a cathode assembly attached to the outer surface of the electrode plate.

[0127]

[0140] b. Cathode Assembly

[0141] The electrochemical cell of the present disclosure includes a cathode assembly located on the cathode side of the bipolar electrode plate 702. In some embodiments, the cathode assembly includes at least one carbon material 624 and an adhesion layer 711 that electrically connects the carbon material 624 to the bipolar electrode plate 702. The carbon material is located on a coating material on a surface (e.g., the cathode side) of the bipolar electrode plate 702. In another embodiment, the cathode assembly includes a cathode cage that electrically connects the carbon material 624 to the cathode side of the bipolar electrode plate 702. Cathode cages are described in U.S. Provisional Patent Application No. 63 / 168,699, filed March 31, 2021, which is incorporated herein by reference, and may be used within the scope of the present disclosure.

[0128]

[0142] i. Carbon materials

[0143] The carbon material 624 is in electrical communication with the surface of the bipolar electrode plate 702 and is adhered to the bipolar electrode plate 702 using an adhesive layer 711. Carbon materials suitable for the electrochemical cells of the present disclosure can include any carbon material that can reversibly absorb an aqueous solution of bromine species (e.g., an aqueous bromine solution or an aqueous bromide solution) and is substantially chemically inert in the presence of an electrolyte. In some embodiments, the carbon material includes carbon black or other furnace carbon. Suitable carbon black materials include, but are not limited to, Cabot Vulcan® XC72R, Akzo-Nobel Ketjenblack EC600JD, and other matte black mixtures of furnace conductive carbon blacks. In some embodiments, the carbon material can also include other components, such as, but not limited to, a PTFE binder and deionized water. For example, the carbon material has a moisture content of less than 50% by weight (e.g., about 0.01% to about 30% by weight) based on the weight of the carbon material. In some embodiments, the carbon material includes PTFE (eg, about 0.5% to about 5% by weight of the carbon material).

[0129]

[0144] In some embodiments, the carbon material may be in the form of one or more thin rectangular blocks. In some embodiments, the carbon material may comprise a single solid block. In other embodiments, the carbon material may comprise 1-5, 1-3, or 1-2 solid blocks of carbon black.

[0130]

[0145] In some embodiments, the carbon material may be comprised of woven carbon fiber or a non-woven carbon felt material.

[0131]

[0146] In some embodiments, the carbon material may be substantially rectangular, with one dimension clearly larger than the other to give the article a rectangular appearance. In the XYZ coordinate space shown in Figures 3 and 4, the width dimension of the carbon material 624 is in the X direction (shown as "W" in Figure 4), which is the larger dimension compared to the Y, giving the article a rectangular appearance. The height dimension of the carbon material 624 is in the Y direction (shown as "H" in Figures 4 and 10), which is the shorter dimension compared to the width dimension. The orientation of the bipolar electrochemical cell 500 and the orientation of the carbon material 624 are complementary such that the width and height of the bipolar electrochemical cell 500 share approximately the same orientation as the width and height of the carbon material 624, respectively. Batteries having such embodiments of carbon materials are described in U.S. Patent Application No. 17 / 410,552, filed August 24, 2021, which is incorporated herein by reference, and may be used within the scope of the present disclosure.

[0132]

[0147] 2. Terminal Assembly

[0148] 4, a terminal assembly 504 of the present disclosure includes a terminal connector 708, a conductive plate 704 having a conductive perimeter 706, an electrically insulating tape member 710, and a terminal bipolar electrode plate 702. The conductive plate 704, the terminal bipolar electrode plate 702, and the electrically insulating tape member 710 each have inner and outer surfaces that are at least substantially parallel to one another, the outer surface of the conductive plate 704 is bonded to the terminal connector 708, the inner surface of the conductive plate 704 is bonded to the outer surface of the terminal bipolar electrode plate 702, the electrically insulating tape member 710 is disposed between the inner surface of the conductive plate 704 and the outer surface of the bipolar electrode plate 702 such that the electrically insulating tape member 710 does not cover the entire inner surface of the conductive plate 704, and the conductive perimeter 706 allows for a bidirectional uniform flow of electrical current through the conductive plate 704 between the terminal connector 708 and the terminal bipolar electrode plate 702.

[0133]

[0149] The insulating tape member 710 does not cover the entire surface of the conductive plate 704, thereby allowing the conductive rim 706 to be in electrical communication with the terminal bipolar electrode plate 702. In some embodiments, the dimensions of the insulating tape member 710 are smaller than the dimensions of the conductive plate 704. A terminal connector 708 of the bipolar electrochemical cell is in electrical communication with the conductive plate 304. In some embodiments, the outer surface of the conductive plate 704 is connected with the terminal connector 708. In some embodiments, the terminal connector 708 comprises any conductive material. In one embodiment, the terminal connection comprises brass (e.g., the terminal connector is a tab assembly that is in electrical communication or contact with the terminal rim).

[0134]

[0150] The terminal bipolar electrode plate 702 of the terminal assembly 504 has inner and outer surfaces that are at least substantially parallel to the inner and outer surfaces of the conductive flat plate 704 and the electrical insulating tape member 710. The terminal bipolar electrode plate 702 may include, but is not limited to, a titanium material coated with a titanium carbide material, through holes, a roughened inner surface, and the like. The conductive perimeter 706 of the flat plate 704 with the electrical insulating tape member 710 is bonded to the terminal bipolar electrode plate 702 such that the conductive perimeter 706 is approximately centered within the electrochemically active area of ​​the terminal bipolar electrode plate 702. In some embodiments, the electrochemically active area corresponds to an area extending between the inner and outer surfaces of the terminal bipolar electrode plate 702 that is in chemical or electrical communication with an adjacent bipolar electrode plate during a charge / discharge cycle of an electrochemical cell. In these embodiments, the electrochemically active area of ​​the terminal bipolar electrode plate 702 associated with the cathode end of the battery corresponds to or is defined by the area surrounded by a cathode assembly disposed on the inner surface of the terminal bipolar electrode plate 702 (e.g., the terminal cathode electrode). The electrochemically active area of ​​the terminal bipolar electrode plate 702 associated with the anode end of the battery may correspond to the area on the inner surface facing the cathode assembly disposed in front of the adjacent bipolar electrode plate and that forms a layer of zinc metal upon charging of the battery (terminal anode assembly). In some embodiments, at least a portion of the surface (e.g., at least the chemically active area) of the terminal bipolar electrode plate 702 of the terminal anode assembly is roughened.

[0135]

[0151] FIG. 4 illustrates an exploded view of a terminal assembly for use in the battery of FIG. 2, showing the cathode carbon material 624, adhesive layer 711, terminal bipolar electrode plate 702, electrically insulating tape member 710, conductive plate 704, conductive rim 306, and terminal connector 708.

[0136]

[0152] In some embodiments, the conductive rim 706 formed by the weld is centrally located within the electrochemically active area of ​​the terminal bipolar electrode plate 702. In some embodiments, the conductive rim 706 is substantially rectangular, substantially circular, or substantially elliptical. In some embodiments, the conductive rim 706 is substantially rectangular.

[0137]

[0153] In some embodiments, a conductive plate 704 having an electrically insulating tape member 710 is centrally positioned within the electrochemically active area of ​​the terminal bipolar electrode plate 702 .

[0138]

[0154] In some embodiments, a surface of the electrically insulating tape member is joined to a surface of the conductive plate by welding or an adhesive, hi some embodiments, the adhesive is electrically conductive.

[0139]

[0155] The conductive plates described herein are larger than prior art current aggregators, providing more contact points and better current density distribution, which reduces manufacturing costs.

[0140]

[0156] In some embodiments, the terminal assembly is a terminal cathode assembly that includes a terminal bipolar electrode plate 702 having an electrochemically active area, a conductive plate 704 having an electrically insulating tape member 710 disposed approximately in the center of the surface electrochemically active area of ​​the terminal bipolar electrode plate 702, and a cathode assembly, such as any of the cathode assemblies described herein, disposed on the inner surface of the terminal bipolar electrode plate 702.

[0141]

[0157] In some embodiments, the terminal assembly is a terminal anode assembly that includes a terminal bipolar electrode plate 702 having an electrochemically active area and a conductive flat plate 704 having an electrically insulating tape member 710 centrally disposed in the electrochemically active area, and the terminal anode assembly does not include a cathode assembly.

[0142]

[0158] In some embodiments, the conductive periphery 706 of the conductive plate 704 having the electrically insulating tape member 710 is bonded to the surface of the terminal bipolar electrode plate 702 by welding or adhesive. In some cases, the adhesive is electrically conductive. Non-limiting examples of suitable conductive adhesives include graphite-filled adhesives (e.g., graphite-filled epoxy, graphite-filled silicone, graphite-filled elastomer, or any combination thereof), nickel-filled adhesives (e.g., nickel-filled epoxy), silver-filled adhesives (e.g., silver-filled epoxy), copper-filled adhesives (e.g., copper-filled epoxy), any combination thereof, and the like.

[0143]

[0159] In some embodiments, the conductive plate 704 having the electrically insulating tape member 710 is constructed from at least one of a copper alloy, copper / titanium clad, aluminum, titanium, and a conductive ceramic.

[0144]

[0160] In some embodiments, at least one of the conductive plate 704 or the terminal bipolar electrode plate 702 with the electrically insulating tape member 710 comprises titanium. In some embodiments, at least one of the conductive plate 704 or the terminal bipolar electrode plate 702 with the electrically insulating tape member 710 comprises a titanium material coated with a titanium carbide material.

[0145]

[0161] In some embodiments, at least one inner surface of the conductive plate 704 having the electrically insulating tape member 710 comprises copper.

[0146]

[0162] In some embodiments, at least one outer surface of the conductive plate 704 having the electrically insulating tape member 710 comprises at least one of copper, titanium, and a conductive ceramic.

[0147]

[0163] In some embodiments, the conductive plate 704 with the electrically insulating tape member 710 comprises a first metal and the terminal bipolar electrode plate 702 comprises a second metal.

[0148]

[0164] In some embodiments, the electrical insulating tape member 710 may be constructed from any adhesive material that is electrically insulating in nature, non-limiting examples of which include, for example, Kapton™, Mylar™, polyimide, polyethylene, nylon, Teflon, neoprene, or any other electrically insulating polymer.

[0149]

[0165] 3. Battery frame components

[0166] In some embodiments, the batteries of the present disclosure include a battery frame member 514 interposed between two adjacent bipolar electrodes or between a bipolar electrode 502 and an end assembly 504 (e.g., a terminal anode assembly or a terminal cathode assembly).

[0150]

[0167] The width and height of the battery frame member 514 are complementary to the width "W" and height "H" of the carbon material 624, respectively. The width of the battery frame member 514 is the dimension along (parallel to) the bottom surface of the battery frame member 514, and the gas flow passages 801 are located at the top of the battery frame member 514 (as shown in FIG. 5). In the XYZ coordinate space shown in FIG. 3, the width dimension of the battery frame member 514 is the X direction, and the height dimension of the battery frame member 514 is the Y direction. The depth of the battery frame member 514 is the Z direction, which is the dimension perpendicular to the height and width of the battery frame member 514 (shown as "D" in FIG. 3). In some embodiments, the frame member 514 is substantially rectangular, with one dimension clearly larger than the other to give it a rectangular appearance.

[0151]

[0168] 5, the battery frame member 514 has an outer edge and an inner edge that defines an open interior region. In some embodiments, the battery frame member 514 is configured such that the open interior region is approximately centered relative to the center of the electrochemically active area of ​​the terminal bipolar electrode plate 702 received by the battery frame member 514 and / or relative to the center of the cathode assembly disposed on the terminal bipolar electrode plate 702. In some embodiments, the outer edge of the battery frame member 514 defines the outer surface of the battery.

[0152]

[0169] In some embodiments, the battery frame member 514 includes a first side that faces and holds a first (terminal) bipolar electrode plate 702 and a second side that is disposed opposite the first side of the battery frame member 514 and faces and holds a second bipolar electrode plate. The second electrode plate is adjacent to and parallel to the first electrode plate in the battery. The first and second electrode plates and the terminal electrode plate can be configured to have substantially the same size and shape. In some embodiments, the battery frame member 514 contacts the anode bipolar electrode plate on one side and the cathode bipolar electrode plate of an adjacent bipolar cell on the other side.

[0153]

[0170] In some embodiments, the battery frame member 514 includes a seal member 516 (FIG. 5) that extends around the inner edge of the entire frame. In some embodiments, the battery frame member 514 includes a first seal member 516 disposed along a first inner edge. In some embodiments, the first seal member is an O-ring. In some embodiments, the first seal member 516 is a gasket. In some embodiments, each inner edge is configured to receive a seal member 516 mounted therein that forms a substantially leak-free seal when the seal is compressed between a corresponding bipolar electrode plate or end plate and the battery frame member 514 when the electrochemical cell is assembled to provide a sealing interface between the bipolar electrode plate or end plate and the battery frame member 514. The seal members cooperate to retain electrolyte between opposing bipolar electrode plates and the battery frame member 514, or between a bipolar electrode plate, an end electrode plate, and the frame member 514. In some embodiments, the seal member 516 is overmolded onto the frame member 514. In some embodiments, the seal member 516 is affixed to the frame member 514 using a form-in-place liquid curing process. In some embodiments, the seal member 516 extends above the depth of the frame member 514 and is compressed during assembly.

[0154]

[0171] In some embodiments, the battery frame member 514 includes a groove at the bottom of the battery frame member 514 to prevent voltage anomalies during cycling. In some embodiments, the groove includes a groove shelf 406 and a void space 407 below the groove shelf 406. In some embodiments, the cathode carbon material 624 rests on the groove shelf 406. It has been found that the presence of the groove shelf and the void space below the groove shelf prevents voltage anomalies during cycling. In some embodiments, there is no void space 407 below the groove shelf 406, and the groove shelf 406 extends to the bottom of the battery frame member 514. In some embodiments, the groove shelf 406 on which the cathode carbon material 624 rests may be 0.5-5 cm high, including the void space 407 below the groove shelf 406, and may be 3-10 mm wide along the entire bottom of the width of the battery frame member 514.

[0155]

[0172] In some embodiments, the battery frame member includes a first frame member and a second frame member, in some embodiments, the first frame member and the second frame member are horizontally stacked and vertically oriented, and a first outer edge of the first frame member is substantially coplanar with a second outer edge of the second frame member.

[0156]

[0173] In some embodiments of the battery, each battery frame member 514 is plastic welded to an adjacent frame member 514 using a weld bead 805 on the periphery of the battery frame member 514 .

[0157]

[0174] In some embodiments, the battery frame member 514 includes a gas flow passage 801 at the top of the battery frame member 514, directly above the vent hole 802. The vent hole 802 allows gas to escape into the gas flow passage 801. In some embodiments, the gas flow passage 801 associated with each battery frame member 514 is covered, so that no cover is required over the gas flow passage 801 after the battery frame members are assembled together. As described herein, the gas flow passage 801 is the cell headspace for gas from the electrochemical cells in the battery frame member 514. In some embodiments, the frame member 514 is filled with electrolyte through a gas flow passage fill hole (with a plug 809 inserted therein as shown), and the gas flow passage 801 also communicates with the vent hole 802. Once the battery is filled with electrolyte, the plug 809 is inserted into the fill hole, sealing the gas flow passage 801 from the environment. In embodiments where the fill hole and the vent hole 802 are not identical, the vent hole remains open to the gas flow passage during battery operation. In another embodiment, electrolyte is added to the battery through the vent.

[0158]

[0175] In some embodiments, there is a liquid diversion system at the top of the cell frame member 514 directly below the vent 802 that allows gas to escape to the gas flow path 801. The gas flow path 801 allows gas to communicate throughout the cell 500, while the liquid diversion system prevents liquid from entering the gas flow path 801 through a series of features. In some embodiments, the liquid diversion system includes a primary diverter 803 having two partial blocking walls 804 and multiple secondary blocking walls 808, which ensures that liquid is always directed back to the open interior area within the cell frame member 514. In some embodiments, the primary diverter 803 consists of a horizontal plastic protrusion with a downward termination at an angle ranging from 30 degrees to 60 degrees. In some embodiments, the secondary blocking walls ensure that minimal fluid reaches the primary diverter. In some embodiments, the secondary blocking walls 808 herein are designed to alternately face downward and upward with respect to the frame member 514 to block waves of internal electrolyte caused by violent sloshing or tilting. One advantage of the fluid bypass system is that it improves battery quality by keeping the electrolyte contained within the frame members during shipping.

[0159]

[0176] Each battery frame member 514 can be formed from flame retardant polypropylene fibers, high density polyethylene, polyphenylene oxide, or polyphenylene ether. Each battery frame member 514 can house two adjacent bipolar electrode plates, or a bipolar electrode plate and an end electrode plate. Each battery frame member 514 can also house an aqueous electrolyte (e.g., zinc halide electrolyte or zinc bromide electrolyte) that is received via vent 802.

[0160]

[0177] 4.Compression plate

[0178] In some embodiments, the electrochemical cell or battery includes a pair of compression plates located at the ends of the electrochemical cell or battery. Suitable compression plates may be, for example, those described in International Publication WO 2019 / 108513, filed November 27, 2018, and may be used within the scope of the present disclosure.

[0161]

[0179] B.2. Flow Bipolar Electrochemical Cell

[0180] Zinc halide flow batteries for use in the present disclosure are well known to those skilled in the art. For example, such flow batteries and electrolytes that may be used in such batteries are described in U.S. Patent Application Publication No. 2011 / 0253553, which is incorporated herein by reference, and may be used within the scope of the present disclosure.

[0162]

[0181] One embodiment of a zinc halide flow bipolar secondary battery includes two inert electrodes with a separator centrally located between the electrodes at an appropriate equidistant distance from each electrode. In some embodiments, the separator may be biased toward one electrode. The electrolyte is an aqueous solution of zinc halide with additional salt additives. The electrolyte is typically supplied to the two separate compartments of the cell via a circulation system from two separate external reservoirs.

[0163]

[0182] The electrolyte contains a water-soluble complexing agent that reacts rapidly with halogen molecules on the cathode side of the cell during charging to form a thick oil that is immiscible with water and settles to the bottom of the cathode reservoir. Mechanical means prevent recirculation of the halogen-containing oil, thereby externally sequestering any elemental bromine generated during charging.

[0164]

[0183] During discharge, bromine-containing liquid that settles to the bottom of the cathode reservoir is reintroduced to the cathode side of the cell, whereby elemental halogens can be reduced to form halide ions.

[0165]

[0184] During charging and discharging, the electrolyte utilized on the anode side is circulated and zinc ions are plated onto the electrode as zinc metal during charging and redissolved into solution as zinc ions during discharging.

[0166]

[0185] C. Bipolar electrochemical cell with zinc metal reservoir

[0186] In yet another aspect, the present disclosure provides a zinc halide secondary battery that includes a zinc metal reservoir. The reservoir is a source of zinc metal and is comprised of zinc metal present in a form known to those skilled in the art. Non-limiting examples of forms of the zinc metal in the zinc metal reservoir include, for example, powder, granules, foil, sheet, wire, or shavings. The zinc metal and zinc metal reservoir are present in the zinc halide secondary battery in addition to and separate from the galvanization of the anode that occurs during charging of the battery. In some embodiments, the zinc metal reservoir is in contact with the electrolyte and is used to replenish the zinc in the electrolyte as described below.

[0167]

[0187] The zinc halide secondary battery of this embodiment of the present disclosure may be a zinc halide static (non-flowing) secondary battery or a zinc halide flow secondary battery, which may be substantially similar to the zinc halide static (non-flowing) secondary battery or the zinc halide flow secondary battery described above. Therefore, the structure and function of these zinc halide secondary batteries will not be described in detail again. However, the zinc halide secondary battery of this embodiment of the present disclosure is different from the zinc halide secondary battery described above in that it has a zinc metal reservoir in the zinc halide secondary battery. In addition to having a zinc metal reservoir in the zinc halide secondary battery, another major difference from the zinc halide secondary battery described above is that the zinc halide electrolyte in the zinc halide secondary battery is either a zinc halide electrolyte containing one or more zinc additives described above, or a zinc halide electrolyte not containing one or more zinc additives described above.

[0168]

[0188] For example, in addition to the zinc metal reservoir, the zinc halide secondary battery of this aspect of the disclosure also includes at least one electrochemical cell including at least one bipolar electrode and a zinc halide electrolyte. The bipolar electrode includes a bipolar electrode plate having an anode surface on one side of the bipolar electrode plate and a cathode surface on the other side of the bipolar electrode plate opposite the anode surface. The zinc halide electrolyte is in contact with the bipolar electrode plate. The zinc halide electrolyte is either a zinc halide electrolyte containing one or more zinc additives as described above, or a zinc halide electrolyte without one or more zinc additives as described above.

[0169]

[0189] In some embodiments, the zinc metal reservoir is in at least one electrochemical cell and in contact with the electrolyte. For example, the zinc metal reservoir can be in the electrolyte. In some embodiments, the zinc metal reservoir is also in contact with the anode of the at least one electrochemical cell. However, the zinc metal reservoir is not in contact with the cathode of the at least one electrochemical cell.

[0170]

[0190] The zinc metal in the zinc metal reservoir is such that zinc metal is available if at least one of the electrochemical cells becomes unbalanced. The electrochemical cells can become unbalanced due to differences in the efficiency of the anodic and cathodic reactions, causing the ratio of zinc ions to halide ions in the electrolyte to fluctuate. If the ratio of zinc ions to halide ions in the electrolyte decreases due to a lower efficiency of the cathode compared to the anode, a portion of the zinc metal reservoir can dissolve into the electrolyte to restore the ratio of zinc ions to halide ions.

[0171]

[0191] The zinc metal reservoir can be present in at least one electrochemical cell in an amount of about 1% to 20% by weight of the electrolyte.

[0172]

[0192] Without wishing to be bound by theory, it is hypothesized that zinc metal in a zinc metal reservoir present in at least one electrochemical cell dissolves into the zinc halide electrolyte during operation of the battery, thereby replacing zinc ions in the electrolyte that are consumed during charging, thereby increasing the ratio of zinc ions to zinc halide ions in the electrolyte during charging of the battery. Thus, by improving the ratio of zinc ions to halide ions (e.g., bromide ions) in the electrolyte, the addition of a zinc metal reservoir in turn increases the ratio of higher order negatively charged zinc complexes (e.g., [ZnBr3] - or [ZnBr4] 2- ) formation and improves Coulombic efficiency. EXAMPLES

[0173]

[0193] III. Examples

[0194] Example 1: Preparation of electrolyte containing non-halogenated zinc additive

[0195] An aqueous electrolyte was prepared containing zinc bromide in the concentration range of 0.7 M to 2.9 M, zinc trifluoromethanesulfonate in the concentration range of 0.4 M to 0.7 M, potassium halide salt in the concentration range of 0.4 to 2.6 M, and tetraalkylammonium salt in the concentration range of 0.3 to 0.5 M. An aqueous electrolyte having the same composition as above but without the zinc additive (such as zinc trifluoromethanesulfonate) was also prepared as a control electrolyte.

[0174]

[0196] Example 2: Testing of electrolytes containing non-halogenated zinc additives in prototype cells

[0197] Test cells were assembled using titanium carbide coated titanium metal current collectors formed into plates. The anode and cathode plates were placed in a parallel arrangement separated by a 12 mm thick high density polyethylene frame. The high density polyethylene frame contained an embedded seal ring that allowed the cell to be sealed by compressing the components between two opposing steel compression plates. Prior to assembling the cell, carbon felt was attached to the cathode titanium current collector using 13 ml of conductive acetone based adhesive. The assembled cell was filled with 210 ml of the electrolyte described in Example 1. The test cells were cycled using an Arbin Instruments Battery Cycling Tester. The cells were charged at a constant power of 4 W to a capacity of 8-16 Ah. The charge voltage limit was 2.4 V. The cells were discharged at a constant power of 4 W until the voltage reached 1.1 V. Figure 6 shows the average coulombic efficiency of the cell population as a function of zinc bromide utilization in the electrolyte. Compared to a control electrolyte without zinc trifluoromethanesulfonate, the addition of 0.4-0.7 M zinc trifluoromethanesulfonate improved the coulombic efficiency when charging to higher levels of zinc bromide utilization. Without being bound by theory, it is believed that zinc trifluoromethanesulfonate improves the zinc to bromide ratio in the electrolyte, resulting in [ZnBr3] - or [ZnBr4] 2- It is hypothesized that this improves coulombic efficiency by reducing the formation of highly negatively charged zinc complexes such as

[0175]

[0198] Example 3: Analysis of zinc halide species using Raman spectroscopy

[0199] Electrolyte samples were prepared as in Example 1. Data were collected on a Renishaw inVia confocal Raman microscope using a 532 nm excitation laser. Samples were prepared by pipetting a drop of electrolyte onto a silicon wafer and aligning the centre of the drop with the beam. Data points were taken at 60 cm -1 ~350cm -1 2cm -1 The laser intensity was 120 cm-1 ~210cm -1 The Raman shift peak was fitted to [ZnBr4] 2- (150cm -1 ), [ZnBr3] - (164cm -1 ), and ZnBr2 (181 cm -1 ) including a sharp peak at 127 cm -1 ~203cm -1 To fit the peak, we first focused on the 127 cm -1 and 203 cm -1 A linear background was applied connecting the points of the three Lorentzian peaks, and their positions were adjusted to within ±1 cm of the expected value. -1 and the full width at half maximum is limited to 14 cm. -1 (which is empirically known to give a good fit). Figure 7 shows the [ZnBr4] of the electrolyte with varying zinc bromide concentration. 2- The peak height ratios are shown. Compared to the control electrolyte without zinc additive, electrolytes containing 0.4-0.7M zinc trifluoromethanesulfonate showed a significant increase in [ZnBr4] at comparable zinc bromide concentrations. 2- The peak height ratio decreased.

[0176]

[0200] Other embodiments

[0201] The foregoing relates only to preferred embodiments of the electrolyte and battery disclosed herein, and it will be apparent that numerous changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

[0177]

[0202] From the foregoing and with reference to the various drawings, one skilled in the art will appreciate that certain modifications may be made to the present disclosure without departing from the scope of the present disclosure. While several embodiments of the present disclosure are shown in the drawings, the disclosure is not intended to be limited thereto, as the disclosure is as broad as the art permits, and the specification is intended to be read in the same manner. Thus, the above description should not be construed as limiting, but merely as exemplifications of certain embodiments. One skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. 1. An electrolyte for use in a zinc halide secondary electrochemical cell comprising: From about 20% by weight to about 70% by weight of the formula ZnY ２ or zinc halide of the formula ZnY ２ wherein Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof; About 10% to about 79% by weight H ２ O. and from about 0.5% to about 20% by weight of one or more zinc additives; Including, The one or more zinc additives include a first zinc additive, the first zinc additive being a salt that is not a zinc halide, and ３ an anion having a van der Waals volume greater than

2. about 0.5% to about 15% by weight of KBr; About 0.5% to about 15% by weight KCl; The electrolyte of claim 1 further comprising:

3. The composition further comprises from about 0.05% to about 20% by weight of one or more quaternary ammonium reagents, each quaternary ammonium reagent having the formula N ＋ (R １ ) (R ２ ) (R ３ ) (R ４ ) X － wherein R １ is hydrogen or an alkyl group; R ２ , R ３ , and R ４ are each independently R １ is an alkyl group the same as or different from X － is a chloride ion or a bromide ion, The electrolyte solution according to claim 2.

4. 10. The electrolyte of claim 1 comprising from about 0.5% to about 3% by weight of said first zinc additive.

5. 5. The electrolyte of claim 4, wherein the molar ratio of total zinc ions to halide ions in the electrolyte is from about 1:2 to about 1:

3.

6. 10. The electrolyte of claim 1 comprising from about 0.5% to about 20% by weight of said first zinc additive.

7. 7. The electrolyte of claim 6, wherein the molar ratio of total zinc ions to halide ions in the electrolyte is from about 1:1 to about 1:2.

5.

8. The one or more zinc additives further include a second zinc additive, the second zinc additive being a salt that is not a zinc halide and having a thickness of about 65 Å. ３ 7. The electrolyte of claim 6 comprising an anion having a van der Waals volume less than

9. 9. The electrolyte of claim 8 comprising from about 0.5% to about 15% by weight of said second zinc additive.

10. 2. The electrolyte of claim 1, wherein the first zinc additive is zinc trifluoromethanesulfonate, zinc perfluorobutanesulfonate, zinc bis(trifluoromethane)sulfonimide, zinc methanesulfonate, zinc p-toluenesulfonate, zinc hexafluorophosphate, zinc tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, or any combination thereof.

11. From about 25% by weight to about 45% by weight of the formula ZnY ２ or zinc halide of the formula ZnY ２ and any combination of zinc halides of the formula: About 25% to about 50% by weight H ２ O. and from about 1% to about 20% by weight of said one or more zinc additives; about 0.5% to about 15% by weight of KBr; About 0.5% to about 15% by weight KCl; from about 0.05% to about 20% by weight of said one or more quaternary ammonium reagents; The electrolyte of claim 3 comprising:

12. The one or more quaternary ammonium reagents include a first quaternary ammonium reagent at a concentration of about 0.05% to about 20% by weight, the first quaternary ammonium reagent being tetra-C chloride. １～６ Alkylammonium or Tetra-C Bromide １～６ 4. The electrolyte of claim 3, wherein the electrolyte is selected from alkyl ammonium salts.

13. 13. The electrolyte of claim 12, wherein the first quaternary ammonium reagent is tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

14. The one or more quaternary ammonium reagents further comprise a second quaternary ammonium reagent, the second quaternary ammonium reagent having the formula N ＋ (R １ ) (R ２ ) (R ３ ) (R ４ ) X － wherein R １ is hydrogen or an alkyl group; R ２ , R ３ , and R ４ are each independently R １ is an alkyl group the same as or different from X － is a chloride ion or a bromide ion; the concentration of the second quaternary ammonium reagent is from about 0.05% to about 20% by weight; The electrolyte solution according to claim 13.

15. 15. The electrolyte of claim 14, wherein the second quaternary ammonium reagent is trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium chloride or bromide.

16. 4. The electrolyte of claim 3 further comprising about 0.2% to about 2.5% by weight of DME-PEG.

17. 17. The electrolyte of claim 16 comprising a DME-PEG having a number average molecular weight of about 1000 amu, a DME-PEG having a number average molecular weight of about 2000 amu, or a combination thereof.

18. 4. The electrolyte of claim 3, further comprising about 0.25% to about 5% by weight of a glycol, the glycol being ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, hexalene glycol, or any combination thereof.

19. 4. The electrolyte of claim 3, further comprising about 0.5% to about 10% by weight of glyme, wherein the glyme is monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof.

20. 4. The electrolyte of claim 3, further comprising less than 1 wt. % of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, or any combination thereof.

21. 4. The electrolyte of claim 3, further comprising 0.1% to 2% by weight of acetic acid, sodium acetate, potassium acetate, or any combination thereof.

22. 2. The electrolyte of claim 1, wherein the zinc halide electrochemical cell is a zinc halide static electrochemical cell.

23. 2. The electrolyte of claim 1, wherein the zinc halide electrochemical cell is a zinc halide flow electrochemical cell.

24. 10. The electrolyte of claim 1, wherein the utilization of the zinc halide in the electrolyte of the zinc halide secondary electrochemical cell is increased by about 5% to about 40% as compared to an equivalent electrolyte in a zinc halide secondary electrochemical cell not containing the one or more zinc additives.

25. 1. A zinc halide secondary battery comprising at least one electrochemical cell including at least one bipolar electrode and a zinc halide electrolyte, the bipolar electrode includes a bipolar electrode plate having an anode surface on one side of the bipolar electrode plate and a cathode surface on another side of the bipolar electrode plate opposite the anode surface; the zinc halide electrolyte is in contact with the bipolar electrode plates; The zinc halide electrolyte is From about 20% by weight to about 50% by weight of a compound of the formula ZnY ２ or zinc halide of the formula ZnY ２ wherein Y is a halogen selected from fluorine, chlorine, bromine, iodine, or any combination thereof; About 30% to about 79% by weight H ２ O. and from about 0.5% to about 20% by weight of one or more zinc additives; the one or more zinc additives include a first zinc additive, the first zinc additive being a salt that is not a zinc halide, ３ A zinc halide secondary battery comprising an anion having a van der Waals volume greater than

26. The electrolyte solution is about 0.5% to about 15% by weight of KBr; About 0.5% to about 15% by weight KCl; 26. The zinc halide secondary battery of claim 25, further comprising:

27. The electrolyte further comprises from about 0.05% to about 20% by weight of one or more quaternary ammonium reagents, each quaternary ammonium reagent having the formula N ＋ (R １ ) (R ２ ) (R ３ ) (R ４ ) X － wherein R １ is hydrogen or an alkyl group; R ２ , R ３ , and R ４ are each independently R １ is an alkyl group the same as or different from X － is a chloride ion or a bromide ion, 27. The zinc halide secondary battery of claim 26.

28. 26. The zinc halide secondary battery of claim 25, wherein the electrolyte further comprises about 0.2% to about 2.5% by weight of DME-PEG.

29. 26. The zinc halide secondary battery of claim 25, wherein the first zinc additive is zinc trifluoromethanesulfonate, zinc perfluorobutanesulfonate, zinc bis(trifluoromethane)sulfonimide, zinc methanesulfonate, zinc p-toluenesulfonate, zinc hexafluorophosphate, zinc tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, or any combination thereof.

30. The one or more zinc additives further include a second zinc additive, the second zinc additive being a salt that is not a zinc halide and having a thickness of about 65 Å. ３ 26. The zinc halide secondary battery of claim 25 comprising an anion having a van der Waals volume less than

31. 26. The zinc halide secondary battery of claim 25, wherein the electrolyte comprises from about 0.5% to about 15% by weight of the second zinc additive.

32. 26. The zinc halide secondary battery of claim 25, wherein the zinc halide secondary battery is a zinc halide static secondary battery.

33. 26. The zinc halide secondary battery of claim 25, wherein the zinc halide secondary battery is a zinc halide flow secondary battery.

34. 26. The zinc halide secondary battery of claim 25, wherein the utilization of zinc halide in said electrolyte of each of said at least one electrochemical cell of said zinc halide secondary battery is increased by about 5% to about 40% compared to a comparable electrolyte of an electrochemical cell of said zinc halide secondary battery not including said one or more zinc additives.

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