Mixed polyhalide electrolytes for static batteries and methods for producing static battery cells - Patents.com

Abstract

A mixed polyhalide initial electrolyte for a static zinc halide battery is provided. Also provided is a method for manufacturing a static battery cell, the method including the steps of providing an initial electrolyte including one or more sources of chloride ions and one or more sources of bromide ions, wherein the one or more sources of chloride ions and the one or more sources of bromide ions are provided in a predetermined ratio selected to result in a target amount of mixed polyhalide upon charging of the initial electrolyte, and forming an electrochemical cell including an anode, a cathode, and the initial electrolyte.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Application No. 63 / 422,229, filed November 3, 2022, which is incorporated herein by reference in its entirety.

[0002] Described herein are mixed polyhalide electrolytes for a static battery and methods for making static battery cells containing the same. Specifically, described herein are mixed polyhalide electrolytes for a static zinc halide battery and methods for making static zinc halide battery cells containing the same. [Background technology]

[0003] Zinc halide batteries have been developed as devices for storing electrical energy. Conventional zinc halide batteries (e.g., zinc bromide batteries) utilize bipolar electrodes placed in a static, i.e., non-flowing, aqueous zinc bromide solution. The charge and discharge process of electrical current in a zinc halide battery generally involves the flow of Zn in the zinc halide electrolyte. 2+ / Zn(s) and X - This is achieved by the reaction of a redox couple such as / X2. When a current is applied to the battery, Zn 2+ +2 e - →Zn 2X - →X2+2 e - (wherein X is a halogen (e.g., Cl, Br, or I)). Conversely, when the battery discharges current, Zn → Zn 2+ +2 e - X2+2 e- →2X - A chemical reaction occurs.

[0004] These zinc halide batteries are formed as bipolar electrochemical cell stacks, where each electrode contains two poles, with the anodic reaction occurring on one side of the electrode and the cathodic reaction occurring on the other side of the same electrode. In this context, the bipolar electrodes are often configured as plates, and the cell stack is assembled to form a prismatic shape. During charging and discharging of a bipolar battery, the electrode plates function as electrical conductors for adjacent cells; that is, each electrode plate acts as the anode of one cell and the cathode of the adjacent cell. In this prismatic battery configuration, the entire surface area of ​​the electrode plates separating adjacent electrochemical cells transfers current from cell to cell.

[0005] When a conventional bipolar zinc halide battery is charged, zinc metal is electrolytically plated on the anode side of the bipolar electrode plates and molecular halogen species are formed on the cathode side of the electrode plates. When the battery is discharged, the plated metallic zinc is oxidized to free electrons that conduct through the electrode plates and reduce the molecular halogen species to form halide anions.

[0006] Historically, static zinc bromide batteries have achieved limited energy and power densities due to density gradients observed in the electrolyte. During battery charging, a dense polybromide phase forms and then sinks to the bottom of the cell, making it difficult to utilize the entire electrode surface area during charging to higher capacities and, therefore, higher energy densities. Thus, static zinc halide batteries face the unique challenge of simultaneously increasing the energy and power densities of static zinc halide batteries without using a flowing electrolyte. Because flow batteries use a flowing electrolyte, such density gradients are not observed in the electrolyte of such flow batteries. Thus, the challenges of static zinc halide batteries described above are not relevant to flow zinc halide batteries.

[0007] Chinese Patent No. CN102479968B discloses a redox flow battery that uses zinc chloride and zinc bromide solutions as electrolytes. The anode and cathode are made of inert, electrically conductive materials, and the zinc chloride and zinc bromide solutions are stored in an anode electrolyte storage tank and a cathode electrolyte storage tank, respectively. During battery operation, the electrolyte solution is circulated between the battery modules and the electrolyte storage tank using a circulation pump.

[0008] BrCl2 as a positive electrode redox couple - / Br - The use of Zn-Br-Cl has been demonstrated in Ti-Br-Cl flow batteries (TBCFBs). See, for example, Xu, Y. et al., "A High Energy Density Bromine-Based Flow Battery with Two-Electron Transfer," ACS Energy Lett., 7, 1034-1039 (2022). Also, Zou, Y. et al., "A Four-Electron Zn-I Aqueous Battery Enabled by Reversible I - / I2 / I + See also "Conversion," Nature Communications, 12, 170 (2021).

[0009] Biswas, S. et al., "Minimal Architecture Zinc-bromine Battery for Low Cost Electrochemical Energy Storage," Energy Env't Sci., 10, 114-120 (2017), discusses the problems arising from the tendency of polybrominated species to separate and stratify in aqueous systems. However, they address the issue by proposing a horizontal cell architecture with the bromine cathode at the bottom of the cell and the zinc anode at the top, forgoing the use of complexing agents. While this approach supposedly keeps the polybrominated species where they are needed, it introduces new challenges for commercially scalable cell architecture regarding gas generation, zinc plating, and efficient cell packing. Summary of the Invention

[0010] This disclosure describes a mixed polyhalide starting electrolyte for a static zinc halide battery. This disclosure also describes a method for manufacturing a static zinc halide battery cell containing the same.

[0011] In one aspect, the present disclosure describes a method for manufacturing a static battery cell, the method including providing an initial electrolyte including one or more sources of chloride ions and one or more sources of bromide ions, wherein the one or more sources of chloride ions and the one or more sources of bromide ions are provided in a predetermined ratio selected to result in a target amount of mixed polyhalide upon charging of the initial electrolyte, and forming an electrochemical cell including an anode, a cathode, and the initial electrolyte.

[0012] In some embodiments, the static battery cell is a static zinc halide electrochemical cell.

[0013] In some embodiments, the static zinc halide electrochemical cell is in a static zinc halide battery.

[0014] The initial electrolyte includes one or more sources of chloride ions, including, by way of non-limiting example, ZnCl, KCl, NHCl, LiCl, CuCl, CaCl, FeCl, SbCl, CrCl, NaCl, BiCl, a quaternary ammonium salt containing chloride anions, or a combination thereof.

[0015] The initial electrolyte includes one or more sources of bromide ions, including, by way of non-limiting example, ZnBr, KBr, NHBr, LiBr, CuBr, CaBr, NaBr, AgBr, AlBr, a quaternary ammonium salt containing a bromide anion, or a combination thereof.

[0016] In some embodiments, the predetermined ratio of the one or more sources of chloride ions to the one or more sources of bromide ions is a molar ratio of total chloride ions to total bromide ions of from about 1:1 to about 13:1.

[0017] In some embodiments, the predetermined ratio of the one or more sources of chloride ions to the one or more sources of bromide ions is a molar ratio of total chloride ions to total bromide ions of from about 1:1 to about 2:1.

[0018] In some embodiments, the predetermined ratio of the one or more sources of chloride ions to the one or more sources of bromide ions is a molar ratio of total chloride ions to total bromide ions of about 1.25:1 to about 1.5:1.

[0019] In another aspect of the present disclosure, an initial electrolyte for use in a static secondary zinc halide electrochemical cell is described, comprising about 5 wt.% to about 30 wt.% ZnBr, about 5 wt.% to about 60 wt.% ZnCl, about 10 wt.% to about 60 wt.% HO, and about 0.05 wt.% to about 20 wt.% of one or more quaternary ammonium agents. In a further aspect, a mixed polyhalide is formed upon at least significant charging of the initial electrolyte.

[0020] In some embodiments, the mixed polyhalides that may be produced upon charging, significant charging, or greater than significant charging have the general formula [X (2n+1) Y (2m) ] - (wherein X and Y are different from each other and independently represent either Cl or Br, n is an integer of 0 to 5, and m is an integer of 1 to 5).

[0021] In some embodiments, mixed polyhalides are formed when the initial electrolyte (containing different halides in a predetermined ratio) in an electrochemical cell undergoes charging to reach an open circuit potential greater than 1.82 V and a volumetric charge capacity greater than 54 mAh / mL.

[0022] In some embodiments, the one or more quaternary ammonium agents are of the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - (In the formula, R 1 is hydrogen or an alkyl group, and R 2 , R 3 and R 4 are each independently R 1 is an alkyl group that is the same as or different from X - is chloride or bromide.

[0023] In some embodiments, the initial electrolyte further comprises between about 0.5 wt.% and about 15 wt.% KBr and between about 0.5 wt.% and about 15 wt.% KCl.

[0024] In some embodiments, the initial electrolyte further comprises about 0.5 wt.% to about 15 wt.% KCl.

[0025] For a better understanding, these and other features, aspects and advantages of the present disclosure will now be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 shows an exploded view of an electrochemical cell according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a side view of a battery according to one embodiment of the present disclosure. [Figure 3] FIG. 3 is an exploded view of the battery of FIG. 2. [Figure 4] FIG. 3 is an exploded view of a terminal assembly used in the battery of FIG. 2. [Figure 5] FIG. 3 is a front view of a battery frame member used in the battery of FIG. 2. [Figure 6] 1 shows the effect of decreasing the molar ratio of zinc chloride to zinc bromide in the electrolyte on the formation of polybromide at the bottom of the vial. [Figure 7]1 shows representative voltages as a function of test time for a mixed polyhalide initial electrolyte according to one embodiment of the present disclosure, and a zinc bromide initial electrolyte (control) that forms polybromide upon charging and does not form a mixed polyhalide as in the present disclosure. [Figure 8] 1 shows the effect of the overall Cl / Br molar ratio in a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure on discharge energy (Wh). [Figure 9] FIG. 1 shows representative average coulombic efficiencies (%) over 10 charge-discharge cycles for a mixed polyhalide initial electrolyte according to one embodiment of the present disclosure, and a zinc bromide initial electrolyte that forms polybromide upon charging and does not form a mixed polyhalide as in the present disclosure. [Figure 10] FIG. 1 shows representative average coulombic efficiencies as a function of cycle length for a mixed polyhalide initial electrolyte according to one embodiment of the present disclosure, and a zinc bromide initial electrolyte that forms polybromide upon charging, but does not form a mixed polyhalide as in the present disclosure. [Figure 11] 1 shows representative cell discharge voltage (V) as a function of cell discharge energy density (Wh / L) for a mixed polyhalide initial electrolyte according to one embodiment of the present disclosure, and a zinc bromide initial electrolyte that forms polybromide upon charging but does not form a mixed polyhalide as in the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0027]

[0023] Embodiments of the present disclosure will be described in detail with reference to the drawings, in which like reference numerals 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 will not be described in detail to avoid obscuring the present disclosure in unnecessary detail. The specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching those skilled in the art to utilize the present disclosure in substantially any appropriately detailed structure.

[0028] [I. Definition] The terms "electrochemical cell" or "cell" are used interchangeably herein to refer to a device that can generate electrical energy from a chemical reaction or drive a chemical reaction through the introduction of electrical energy. An electrochemical cell may be part of a bipolar stack or may be a unipolar (or monopolar) electrochemical cell. An electrochemical cell may be connected to any number of other electrochemical cells in a series or parallel connection, or may be a stand-alone device.

[0029] The term "battery" as used herein encompasses an electrical storage device containing at least one electrochemical cell. For example, a battery may be composed of approximately 5 to 50 electrochemical cells in series. "Secondary batteries" are rechargeable, while "primary batteries" are not. In the secondary batteries of the present disclosure, the battery anode is designated as the positive electrode when discharging and the negative electrode when charging. In contrast, the battery cathode is designated as the negative electrode when discharging and the positive electrode when charging.

[0030] The term "electrode" as used herein 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.

[0031] 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, whereas in secondary or rechargeable batteries, the anode is the electrode that undergoes chemical reduction during the charge phase of the cell. Anodes are formed from electrically conductive or semiconductive materials, such as metals (e.g., titanium or TiC-coated titanium), metal oxides, metal alloys, metal composites, semiconductors, conductive plastics, etc.

[0032] The term "cathode," as used herein, refers to the positive electrode into which electrons flow during the discharge phase of a battery. The cathode is also the electrode that undergoes chemical reduction during the discharge phase, whereas in secondary or rechargeable batteries, the cathode is the electrode that undergoes chemical oxidation during the charge phase of the cell. Cathodes are formed from electrically conductive or semiconductive materials, such as metals, metal oxides, metal alloys, metal composites, semiconductors, conductive plastics, and the like.

[0033] The terms "monopolar electrode" or "unipolar electrode" as used herein refer to an electrode that functions as a cell anode or a cell cathode without contributing to an additional cell electrochemical reaction.

[0034] 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 instances, a bipolar electrode includes two surfaces, a cathode surface and an anode surface, connected by a conductive material. For example, a bipolar electrode plate may have opposing surfaces, where one surface is an anode surface and the other surface is a cathode surface, and the conductive material is the thickness of the plate between the opposing surfaces.

[0035] The term "electrolyte," as used herein, 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. Electrolytes include mixtures of materials such as aqueous solutions of metal halide salts (e.g., ZnBr, ZnCl, etc.).

[0036] 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. Halogens are reactive non-metallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.

[0037] 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 to create a fluoride, chloride, bromide, iodide, or astatine compound.

[0038] The term "polyhalide" as used herein refers to a molecular ion containing three or more halogen atoms of the same type and having an overall charge of -1. Polyhalides include, but are not limited to, Br3 - , Br5 - , Cl3 - , or Cl5 - Examples include:

[0039] The term "polybromide" as used herein refers to a molecular ion containing three or more bromine atoms and having an overall charge of -1. During charging of a battery in a halide electrolyte composed primarily of bromide ions dissolved in solution, bromide is electrochemically converted to bromine (Br2), which then combines with free bromide in solution to form polybromides. Polybromides typically form a non-aqueous phase in the electrolyte after formation. Polybromides include, by non-limiting example, Br3 - and Br5 - (MW 239.7 and 399.5 g / mol, respectively).

[0040] The term "mixed polyhalide" as used herein refers to a molecular ion containing three or more different types of halogen atoms, such as bromine and chlorine atoms, with an overall charge of -1. During charging of a battery in a non-rechargeable electrolyte composed of a selected ratio of bromide and chloride ions dissolved in solution, bromide is electrochemically converted to bromine (Br2). Then, at higher charging voltages, bromine combines with chloride ions in solution and is further oxidized to form a mixed polyhalide. In one embodiment, mixed polyhalides are formed when a non-rechargeable electrolyte having a predetermined ratio of different halide ions is used. Non-limiting examples of predetermined ratios of different halide ions in the non-rechargeable electrolyte include a total chloride to bromide molar ratio of 1:1 to 13:1. Preferably, the total chloride to bromide molar ratio in the non-rechargeable electrolyte ranges from about 1.5:1 to about 2.5:1. Mixed polyhalides include, by way of non-limiting example, BrCl2. - (MW 150.8 g / mol) or ClBr2 - (MW 195.3 g / mol).

[0041] The term "anion" as used herein refers to any chemical entity having one or more permanent negative charges. Examples of anions include, but are not limited to, fluoride, chloride, bromide, iodide, arsenate, phosphate, arsenite, hydrogenphosphate, dihydrogenphosphate, sulfate, nitrate, hydrogensulfate, 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.

[0042] The term "titanium material," as used herein, may include, but is not limited to, titanium (any oxidation state), TiC, alloys of TiC such as TiCxM (where x is 0, 1, 2, 3, or 4 and M is a metal), titanium carbohydride, non-stoichiometric titanium-carbon compounds, and combinations thereof.

[0043] The term "titanium carbide" is used interchangeably herein with "titanium carbide material" and includes, but is not limited to, TiC, alloys of TiC such as TiCxM (where x is 0, 1, 2, 3, or 4 and M is a metal), titanium carbohydride, non-stoichiometric titanium-carbon compounds, and combinations thereof.

[0044] The term "zinc metal" is used herein to refer generally to Zn(0) or Zn o Also known as zinc.

[0045] The term "dimethyl ether poly(ethylene glycol)", "DME-PEG" refers to the 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 approximately 2000 amu. n ) refers to a DME-PEG polymer having the following structure:

[0046] The term "dimethyl ether" as used herein refers to an organic compound having the formula CH3OCH3.

[0047] The term "flocculation concentration" herein refers to the total concentration (e.g., wt.%) of each component of a class of ingredients or a class of agents (e.g., quaternary ammonium agents). In one example, the flocculation concentration of one or more quaternary ammonium agents in an electrolyte is the sum of the concentrations (e.g., weight percent) of each constituent quaternary ammonium agent present in the electrolyte. Thus, if an electrolyte has three quaternary ammonium agents, the flocculation concentration of the three quaternary ammonium agents is the sum of the respective concentrations of the three quaternary ammonium agents present in the electrolyte. Alternatively, if an electrolyte has only one quaternary ammonium agent, the flocculation concentration of the quaternary ammonium agent is simply the concentration of the single quaternary ammonium agent present in the electrolyte.

[0048] The term "alcohol," as used herein, refers to any organic compound whose molecule contains one or more hydroxyl groups bonded to a carbon atom. Alcohols include, for example, methanol, ethanol, 1-propanol (i.e., n-propanol), 2-propanol (i.e., iso-propanol), 1-butanol (i.e., n-butanol), sec-butanol, iso-butanol, tert-butanol, 1-pentanol, or any combination thereof.

[0049] The term "hydroxyl group" as used herein refers to an --OH group.

[0050] The term "glycol" as used herein refers to any of a class of organic compounds belonging to the alcohol family. In a glycol molecule, two hydroxyl (-OH) groups are attached to different carbon atoms. Glycols include, for example, C 16 glycols, including ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, hexalene glycol, or any combination thereof. 1~10 Other examples of glycols include substituted ethylene and propylene glycols.

[0051] The term "weight percent" and its abbreviations "wt.%" or "wt%" are used interchangeably herein to refer to the product of 100 times the mass of one or more components divided by the total mass of a mixture or product containing said components.

number

[0052] The term "quaternary ammonium agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom. Non-limiting examples of quaternary ammonium agents include tetra-alkylammonium 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 having at least one quaternary nitrogen atom, combinations thereof, etc.), or any combination thereof. The tetra-alkylammonium halides may be symmetrically or asymmetrically substituted with respect to the substituent of the quaternary nitrogen atom.

[0053] The term "viologen" as used herein refers to any bipyridinium derivative of 4-4'-bipyridine.

[0054] The term "complexing agent" herein and in the zinc halide battery literature typically refers to a positively charged quaternary ammonium organic compound. The complexing agent is used to fuse, bond, or complex the polybromide or polyhalide species formed in the battery, thereby creating a species in which the positively charged quaternary ammonium and the negatively charged polybromide or polyhalide are one compound with a lower vapor pressure and greater thermodynamic stability.

[0055] The term "ammonium bromide complexing agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom, where the quaternary nitrogen atom 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.

[0056] The term "imidazolium bromide complexing agent," as used herein, refers to any compound, salt, or material containing a quaternary nitrogen atom, where the quaternary nitrogen atom 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.

[0057] The term "pyridinium bromide complexing agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom, where the quaternary nitrogen atom 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.

[0058] The term "pyrrolidinium bromide complexing agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom, where the quaternary nitrogen atom is part of a pyrrolidinium moiety. An example of a pyrrolidinium bromide complexing agent is 1-butyl-1-methylpyrrolidinium bromide.

[0059] The term "morpholinium bromide complexing agent" as used herein refers to any compound, salt, or material containing a quaternary nitrogen atom, where the quaternary nitrogen atom is part of a morpholinium moiety. An example of a morpholinium bromide complexing agent is N-ethyl-N-methylmorpholinium bromide.

[0060] The term "phosphonium bromide complexing agent" as used herein refers to any compound, salt, or material that contains a quaternary phosphonium atom. An example of a phosphonium bromide complexing agent is tetraethylphosphonium bromide.

[0061] The term "crown ether" as used herein refers to a cyclic chemical 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.

[0062] The term "alkyl" group, as used herein, 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.

[0063] The term "aryl" group, used herein alone or as part of a larger moiety, such as "aralkyl," "aralkoxy," or "aryloxyalkyl," refers to monocyclic (e.g., phenyl); bicyclic (e.g., indenyl, naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl); tricyclic (e.g., fluorenyl, tetrahydrofluorenyl, anthracenyl, or tetrahydroanthracenyl); or benzo-fused groups having three rings. For example, benzo-fused groups include groups having two or more C 4~8Includes phenyl fused to a carbocyclic moiety. The aryl is 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; sulfamido; oxo; or carbamoyl. Alternatively, the aryl may be unsubstituted.

[0064] Substituted aryls include, for example, 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-heterocycloaliphatic-o-alkylaryls, heteroarylaminocarbonylaryls, nitroalkylaryls, alkylsulfonylaminoalkylaryls, heterocycloaliphaticcarbonylaryls, alkylsulfonylalkylaryls, cyanoalkylaryls, heterocycloaliphaticcarbonylaryls, alkylcarbonylaminoaryls, hydroxyalkylaryls, alkylcarbonylaryls, aminocarbonylaryls, alkylsulfonylaminoaryls, dialkylaminoaryls, alkylaryls, and trihaloalkylaryls.

[0065] The term "aralkyl" group, as used herein, 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 aralkyl group is, for example, benzyl. A "heteroaralkyl" group refers to an alkyl group substituted with a heteroaryl.

[0066] The term "cycloalkyl" group, as used herein, refers to a saturated carbocyclic monocyclic, bicyclic, or tricyclic, or polycyclic (fused or bridged) ring of 3 to 10 (e.g., 5 to 10) carbon atoms. Monocyclic cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like. Bicyclic cycloalkyl groups include, but are not limited to, 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, bicycle[2.2.1]heptanyl, bicycle[3.1.1]heptanyl, and the like. Polycyclic groups include, but are not limited to, adamantyl, cubyl, norbornyl, and the like. The cycloalkyl ring may be optionally substituted at any chemically feasible ring position.

[0067] The term "heterocycloalkyl" group, as used herein, refers to a 3- to 10-membered monocyclic or bicyclic (fused or bridged) (e.g., 5- to 10-membered monocyclic 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). Heterocycloalkyl groups include, for example, optionally substituted piperidyl, piperazyl, tetrahydropyranyl, tetrahydrofuryl, 1,4-dioxolanyl, 1,4-dithianyl, 1,3-dioxolanyl, oxazolidyl, isoxazolidyl, morpholinyl, thiomorpholyl, octahydrobenzofuryl, octahydrochromenyl, octahydrothiochromenyl, octahydroindolyl, octahydropyrindinyl, decahydroquinolinyl, octahydrobenzo[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 with a phenyl moiety, such as tetrahydroisoquinoline. Heterocycloalkyl ring structures may be optionally substituted at any chemically feasible position on one or more rings.

[0068] The term "heteroaryl" group, as used herein, 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 is aromatic. Heteroaryl groups include benzo-fused ring systems having 2 to 3 rings. For example, a benzo-fused group can be a benzo-fused group having one or two C 4~8 Contains a benzo fused to a heterocyclic moiety (eg, indolisyl, indolyl, isoindolyl, 3H-indolyl, indolinyl, benzo[b]furyl, benzo[b]thiophenyl, quinolinyl, or isoquinolinyl). Some examples of heteroaryl are 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.

[0069] When an element or layer is referred to as "resting," "engaging," "connected," "attached," or "coupled" to another element or layer, it may be directly resting, engaging, connected, attached, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as "directly resting," "directly engaging," "directly connected," "directly attached," or "directly coupled" to 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" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and" includes any and all combinations of one or more of the associated listed items.

[0070] Terms such as upper, lower, top, bottom, right, left, etc. may be used herein to describe the position of various elements relative to other elements. These terms represent the location of elements in an exemplary configuration. However, it will be apparent to one skilled in the art that 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.

[0071] The term "plurality" as used herein refers to two or more of a described element. In some embodiments, plurality refers to three or more, four or more, or five or more of a described element.

[0072] The term "chemically compatible" as used herein refers to a material that does not interfere with the chemistry of the electrochemical cell in a manner that significantly adversely affects the performance of the electrochemical cell. A chemically compatible material is chemically compatible with the electrolyte (e.g., zinc halide electrolyte, alkaline electrolyte) and the anode and cathode materials.

[0073] The term "chemically inert" as used herein refers to a material that does not chemically react in any significant way with the electrolyte, anode, or cathode of an electrochemical cell.

[0074] The terms "charging," "charging," or "charging," as used herein, refer to the process of charging an electrochemical cell that occurs when an external current is applied across the electrochemical cell, with the cathode being the positive terminal and the anode being the negative terminal. Either the electrochemical cell, the electrolyte within the electrochemical cell, or the battery can be said to be "charging."

[0075] The terms "initial electrolyte" or "uncharged electrolyte" as used herein refer to the electrolyte before charging.

[0076] The terms "charged electrolyte" or "charged electrolyte" as used herein refer to an electrolyte contained within an electrochemical cell that has undergone any amount of charging such that it is no longer in the "initial electrolyte" state.

[0077] The terms "charged electrochemical cell" or "charged electrochemical cell" as used herein refer to an electrochemical cell that has undergone any amount of charging such that the electrolyte contained within the electrochemical cell is no longer in the "initial electrolyte" state.

[0078] The terms "significantly charged" or "subjected to significant charge," as used herein in the context of an electrochemical cell or an electrolyte contained within an electrochemical cell, refer to an electrochemical cell or an electrolyte contained within an electrochemical cell that has undergone charging to reach an open circuit potential of at least 1.82 V and a volumetric charge capacity of at least 54 mAh / mL.

[0079] The term "mixed polyhalide electrolyte" as used herein refers to an aqueous electrolyte having a mixture of bromide and chloride ions in solution, which, in one aspect, forms a mixed polyhalide when subjected to significant charge. As used herein, "mixed polyhalide electrolyte" is a generic term that encompasses both the initial electrolyte and the charged electrolyte at any charge state. However, for clarity, the mixed polyhalide is present in significant amounts in the charged electrolyte only when it has undergone significant charge.

[0080] The term "electrolyte density gradient" as used herein refers to regions of an electrolyte having different densities due to changes in the distribution of molecular species with different molecular weights within a charged electrolyte. In one aspect, an electrolyte density gradient results from molecular ions containing three or more halogen atoms (of the same type or different types) and having different molecular weights within a charged electrolyte.

[0081] The "coulombic efficiency" of a secondary battery herein refers to the ratio of discharge capacity to charge capacity within the same charge-discharge cycle.

[0082] The "current density distribution" of a battery, as used herein, refers to the variation in local current density across the surface of an electrode.

[0083] II. Electrochemical Cells and Batteries In one aspect, the present disclosure provides an initial electrolyte for use in static secondary zinc halide electrochemical cells and batteries. In another aspect, the present disclosure provides a static secondary zinc halide battery including the initial electrolyte.

[0084] (A. Electrolyte) The present disclosure provides starting electrolytes useful in non-flowing (i.e., static) secondary zinc halide electrochemical cells and batteries. In these electrochemical cells and batteries, the zinc halide (e.g., a combination of zinc bromide and zinc chloride) present in the starting electrolyte serves as the electrochemically active material. These electrochemical cells and batteries are described below.

[0085] The initial electrolyte of the present disclosure is a zinc halide electrolyte that contacts at least one electrode of the electrochemical cell. The initial electrolyte is mechanically separated in each cell of a static secondary zinc halide battery. In some embodiments, the electrodes are bipolar electrodes, and the initial 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.

[0086] In one embodiment of a static secondary zinc bromide battery, for example, positively charged zinc ions and negatively charged halide ions must be available at the anode and cathode electrodes, respectively.

[0087] In conventional zinc bromide starting electrolytes containing low concentrations of chloride, 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 during charging of the electrochemical cell or battery. In contrast, bromine is reduced to bromide anions during discharge.

[0088] Bromine combines with bromide to form polybromide anions at or near the cathode electrode. 2Br - ⇔Br2+2e - ;Br2+Br - ⇔Br3 - ;E=1.04V (1) It can be expressed as follows.

[0089] As shown in equation (1), in a conventional zinc bromide initial electrolyte containing a low concentration of chloride, polybromides (e.g., Br3 - and Br5 - (MW 239.7 and 399.5 g / mol, respectively) are formed, which have densities much higher than that of aqueous electrolytes, about 1.6 g / mL, causing non-uniform electrolyte height gradients and thus poor electrode surface area utilization in electrochemical cells subjected to significant charge. For example, polybromides such as Br3 -For zinc halide batteries, the density of the electrolyte is about 2.0 g / ml to about 2.2 g / ml. Thus, historically, one of the biggest challenges for static zinc halide batteries has been the electrolyte density gradient across the height of the electrochemical cell, which results in uneven electrode utilization and limited energy and power density.

[0090] One route to reducing the electrolyte density gradient across the cell height is to create an initial electrolyte with a mixed chloride / bromide polyhalide, which has a lower density than the previously known polybromides. A mixed halide initial electrolyte with a high concentration of zinc chloride allows for the addition of a mixed polyhalide (e.g., BrCl2 - (MW 150.7 g / mol)) is a conventional polybrominated compound (e.g., Br3 - and Br5 - (MW 239.7 and 399.5 g / mol, respectively). The mixed polyhalides formed therefore have significantly lower densities than conventional polybromides, thus reducing the electrolyte density gradient across the height of the cell.

[0091] As the molar ratio of zinc chloride to zinc bromide increases, the cathodic reaction can change from equation (1) above to equation (2) below: 2Br - +4Cl - ⇔2BrCl2 - +2e - ;E=1.3V (2)

[0092] When Equation (2) becomes the dominant cathode reaction in a static zinc halide battery (instead of Equation (1)), an additional benefit that solves many historical problems with static zinc halide batteries is that the final product of Equation (2) has a significantly lower molecular weight than the final product of Equation (1). This results in an initial electrolyte containing mixed polyhalides that is less dense in Equation (2) and does not sink to the bottom of the cell, allowing utilization of the full electrode height. Furthermore, Equation (2) has a higher voltage than Equation (1), resulting in a higher energy battery.

[0093] This disclosure relates specifically to starting electrolytes that can be used in static zinc halide batteries. The starting electrolytes are mixed chloride / bromide electrolytes that can achieve higher voltages, higher energy and power densities, and lower density mixed polyhalides. This is achieved by formulating the mixed chloride / bromide electrolyte with the proper concentrations and ratios of zinc chloride, zinc bromide, potassium chloride, and potassium bromide, along with appropriate complexing agents and zinc plating additives. The lower density of the mixed polyhalides in these starting electrolytes is important for solving the problem of electrolyte density gradients (stratification) across the electrolyte height in conventional static zinc bromide batteries, where the polybromide formed from charging the electrolyte is much denser than the initial aqueous electrolyte, resulting in accumulation of polybromide at the bottom of the cell and uneven electrode height utilization during discharge.

[0094] Figure 6 shows the effect of decreasing the molar ratio of zinc chloride to zinc bromide in the electrolyte on the formation of polybromides at the bottom of the vial. The shades shown represent the coloration and opacity of the aqueous phase of a given sample, resulting from the distribution of suspended or dissolved halide complexes in that sample. As shown in Figure 6, decreasing the molar ratio of zinc chloride to zinc bromide in the initial electrolyte results in the formation of the aforementioned dense polybromides at the bottom of the vial. As a result, initial electrolytes containing more zinc chloride form buoyant mixed polyhalides in the electrolyte that do not sink or accumulate at the bottom of the vial. The implication of this result is that if an initial electrolyte with an equal or greater proportion of chloride relative to bromide is used, the full height of a static zinc halide battery can be fully utilized, a significant improvement over historical static zinc bromide batteries. In some embodiments, the molar ratio of total chloride to bromide in the uncharged or initial electrolyte is from about 1:1 to about 13:1. Preferably, the molar ratio of total chloride to bromide in the uncharged or initial electrolyte is from about 1:1 to about 2:1. Preferably, the molar ratio of total chloride to bromide in the uncharged or initial electrolyte is from about 1.25:1 to about 1.5:1.

[0095] One aspect of the present disclosure provides an uncharged or initial electrolyte for use in a static secondary zinc halide electrochemical cell, comprising about 5 wt.% to about 30 wt.% ZnBr; about 5 wt.% to about 60 wt.% ZnCl; about 10 wt.% to about 60 wt.% HO; and about 0.05 wt.% to about 20 wt.% of one or more quaternary ammonium agents. During charging of the cell, low molecular weight halide ions (e.g., bromide and chloride) in the uncharged electrolyte are converted to high molecular weight polyhalides (e.g., Br3 - , Br5 - etc.) and high molecular weight mixed polyhalides (e.g., BrCl2 - , ClBr2 - The amount and type of polyhalides and mixed polyhalides formed during charging depend on many uncharged electrolyte variables, including halide concentration, pH, chloride to bromide ratio, battery charge capacity, and battery voltage. Once the high molecular weight polyhalides and mixed polyhalides are electrochemically formed, they are typically chemically complexed with a quaternary ammonium agent. The polyhalide or mixed polyhalide complex with the quaternary ammonium agent may be stored until the battery is discharged.

[0096] In some embodiments, mixed polyhalides are formed when an uncharged electrolyte (comprising different halides in a predetermined ratio) in an electrochemical cell is charged to an open circuit potential of at least 1.82 V and a volumetric charge capacity of at least 54 mAh / mL. In some embodiments, mixed polyhalides are formed when an uncharged electrolyte (comprising different halides in a predetermined ratio) in an electrochemical cell is charged to an open circuit potential greater than 1.82 V and a volumetric charge capacity greater than 54 mAh / mL. Open circuit potentials greater than 1.82 V include, but are not limited to, 1.83 V to 2.10 V. Volumetric charge capacities greater than 54 mAh / mL include, but are not limited to, 55 mAh / mL to 104 mAh / mL.

[0097] In some embodiments, mixed polyhalides may be produced by subjecting a cell to further charging after the cell has already received a significant charge. Such mixed polyhalides have the general formula [X (2n+1) Y (2m) ] - (wherein X and Y are different from each other and independently represent either Cl or Br, n is an integer from 0 to 5, and m is an integer from 1 to 5.) Non-limiting examples of mixed polyhalides produced during the charging process include BrCl2 - (MW 150.8 g / mol), ClBr2 - (MW 195.3 g / mol), or a combination thereof.

[0098] In some embodiments, the total molar ratio of chloride ions to bromide ions in the uncharged electrolyte is from about 1:1 to about 13:1. In some embodiments, the total molar ratio of chloride ions to bromide ions in the uncharged electrolyte is from about 1:1 to about 2:1. In yet another embodiment, the total molar ratio of chloride ions to bromide ions in the uncharged electrolyte is from about 1.25:1 to about 1.5:1.

[0099] In some embodiments, the electrolyte after charging does not have a density gradient along the length of the electrode during the charging process, regardless of the charge capacity, hi some embodiments, the electrolyte after charging forms a lower density gradient during the charging process compared to an electrolyte containing a total chloride to bromide molar ratio of less than about 1:1.

[0100] In some embodiments, the density of the initial electrolyte is from about 1.2 to about 2.10 g / cm 3 In some embodiments, when an electrochemical cell containing the initial electrolyte is subjected to at least a significant charge, the density of the electrolyte at the end of charge is between about 1.4 and about 2.20 g / cm 3 is.

[0101] In some embodiments, the ratio of the density of the initial electrolyte to the density of the electrolyte after charging is about 1.3 to about 1. In one aspect, such a ratio is achieved when an electrochemical cell containing the initial electrolyte undergoes at least significant charging. In another embodiment, the ratio of the density of the initial electrolyte to the density of the electrolyte after charging is about 1.15 to about 1. In one aspect, such a ratio is achieved when an electrochemical cell containing the initial electrolyte undergoes at least significant charging.

[0102] In some embodiments, the initial electrolyte of the present disclosure provides a higher coulombic efficiency in a static secondary zinc halide electrochemical cell compared to a static secondary zinc halide electrochemical cell comprising an initial electrolyte before charging that includes a total chloride to bromide molar ratio of less than about 1:1.

[0103] In some embodiments, the initial electrolyte further comprises other components suitable within the scope of the present disclosure. For example, additional components in the initial electrolyte described in PCT Publication No. WO2016 / 057477, filed October 6, 2015; PCT Publication No. WO2017 / 172878, filed March 29, 2017; U.S. Patent No. 10,276,872, filed March 29, 2016; and U.S. Patent Application Publication No. 2011 / 0253553A1, filed March 21, 2011, all of which are incorporated herein by reference, can be used within the scope of the present disclosure.

[0104] In some embodiments, the initial electrolyte further comprises between about 0.5 wt.% and about 15 wt.% KBr and between about 0.5 wt.% and about 15 wt.% KCl.

[0105] In some embodiments, the initial electrolyte further comprises about 0.5 wt.% to about 15 wt.% KCl. In some embodiments, the initial electrolyte does not comprise KBr. In some embodiments, the initial electrolyte comprises about 0 wt.% KBr.

[0106] The initial electrolyte includes one or more sources of chloride ions, including, by way of non-limiting example, ZnCl, KCl, NH, Cl, LiCl, CuCl, CaCl, FeCl, SbCl, CrCl, NaCl, BiCl, and quaternary ammonium salts containing chloride anions.

[0107] The initial electrolyte includes one or more sources of bromide ions, non-limiting examples of which include, for example, ZnBr, KBr, NHBr, LiBr, CuBr, CaBr, NaBr, AgBr, AlBr, and quaternary ammonium salts containing bromide anions.

[0108] In some embodiments, the initial electrolyte comprises ZnBr, ZnCl, KCl, and KBr. In some embodiments, the total molar ratio of chloride ions to bromide ions in the initial electrolyte is from about 1:1 to about 13:1. In another embodiment, the total molar ratio of bromide ions to chloride ions in the initial electrolyte is from about 1:1 to about 2:1. In yet another embodiment, the total molar ratio of bromide ions to chloride ions in the initial electrolyte is from about 1.25:1 to about 1.5:1.

[0109] In some embodiments, the initial electrolyte comprises from about 0.05 wt.% to about 20 wt.% of one or more quaternary ammonium agents, each of which has the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - (In the formula, R 1 is hydrogen or an alkyl group, and R 2 , R 3 and R 4 are each independently R 1 is an alkyl group that is the same as or different from X - is chloride or bromide.

[0110] In some embodiments, the one or more quaternary ammonium agents include a first quaternary ammonium agent. In some embodiments, the first quaternary ammonium agent is tetra-C chloride. 1~6 Alkylammonium or Tetra-C Bromide 1~6 In some embodiments, the first quaternary ammonium agent is selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

[0111] In some embodiments, the one or more quaternary ammonium agents further comprise a second quaternary ammonium agent. In some embodiments, the second quaternary ammonium agent has the formula N + (R 1 )(R 2 )(R 3 )(R 4 )X - (In the formula, R 1 is hydrogen or an alkyl group, and R 2 , R 3 and R 4 are each independently R 1 is an alkyl group that is the same as or different from X - is chloride or bromide.

[0112] In some embodiments, the second quaternary ammonium agent is trimethylethylammonium, trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, triethylpropylammonium, triethylbutylammonium, tripropylmethylammonium, tripropylethylammonium, or tripropylbutylammonium chloride or bromide.

[0113] In some embodiments, the initial electrolyte further comprises about 0.1 wt.% to about 3 wt.% of a glycol, wherein the glycol is ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, hexylene glycol, or any combination thereof. In one embodiment, the glycol is neopentyl glycol.

[0114] In some embodiments, the initial electrolyte further comprises about 0.1 wt.% to about 3 wt.% of a glyme, wherein the glyme is monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or any combination thereof. In one embodiment, the glyme is tetraglyme. In some embodiments, the glyme is dipropylene glycol dimethyl ether (DMM).

[0115] In some embodiments, the initial electrolyte further comprises less than 0.1 wt.% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, Cr, Sc, Cu, Al, Ru, Sr, or any combination thereof, hi some embodiments, the initial electrolyte further comprises up to 1 wt.% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, Cr, Sc, Cu, Al, Ru, Sr, or any combination thereof.

[0116] In some embodiments, the initial electrolyte comprises about 5 wt.% to about 40 wt.% ZnBr; about 5 wt.% to about 60 wt.% ZnCl; about 10 wt.% to about 60 wt.% HO; about 1 wt.% to about 10 wt.% KBr; about 1 wt.% to about 20 wt.% KCl; and about 0.05 wt.% to about 20 wt.% of one or more quaternary ammonium agents.

[0117] In some embodiments, the initial electrolyte comprises about 5 wt.% to about 40 wt.% ZnBr; about 5 wt.% to about 60 wt.% ZnCl; about 10 wt.% to about 60 wt.% HO; about 1 wt.% to about 20 wt.% KCl; and about 0.05 wt.% to about 20 wt.% of one or more quaternary ammonium agents.

[0118] In some embodiments, the initial electrolyte further comprises about 0.1 wt.% to about 3 wt.% DME-PEG, hi some embodiments, the initial 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.

[0119] In some embodiments, the initial electrolyte further comprises about 0.1 wt.% to about 3 wt.% PEG, hi some embodiments, the initial electrolyte comprises PEG having a number average molecular weight of about 1000 amu, PEG having a number average molecular weight of about 3500 amu, or a combination thereof.

[0120] In some embodiments, the initial electrolyte does not include DME-PEG.

[0121] In some embodiments, the initial electrolyte does not include PEG.

[0122] Non-limiting examples of initial electrolytes that result in mixed polyhalides of the present disclosure when an electrochemical cell containing the initial electrolyte undergoes at least significant charging are shown below in Table 1-Part 1 and Table 1-Part 2.

[0123] [Table 1]

[0124] [Table 2]

[0125] Initial electrolytes containing mixed polyhalides according to embodiments of the present disclosure have also been found to advantageously improve the coulombic efficiency of static secondary zinc halide electrochemical cells. In some embodiments, the coulombic efficiency of static secondary zinc halide electrochemical cells containing mixed polyhalide initial electrolytes according to embodiments of the present disclosure is increased by about 3% to about 8% compared to comparable static secondary zinc bromide cells containing initial zinc bromide electrolytes that form polybromides upon charging and do not form mixed polyhalides in the electrolyte, as disclosed herein. This is demonstrated in the examples below.

[0126] An initial electrolyte including a mixed polyhalide according to embodiments of the present disclosure may advantageously improve the current density distribution across the height of the electrodes of a static secondary zinc halide electrochemical cell.

[0127] The inventors of the present disclosure also unexpectedly discovered that it was possible to achieve these results using an initial electrolyte created at a pH of about 3. Prior to the present invention, BrCl2 - The reaction was thought to occur only in very low pH electrolytes, below about pH 1, or in very concentrated electrolytes with little free water.

[0128] The chloride and bromide concentrations in the initial electrolyte may be determined as follows: The cell may be charged using the protocol described in Example 3 below. The cell may then be disconnected from the electrical connection, opened, and an aliquot of electrolyte removed from the cell. An aliquot (e.g., 10 mL) may be obtained from the top of the cell, and an aliquot (e.g., 10 mL) may be obtained from the bottom of the cell. The bromide and chloride concentrations may be analytically determined for each aliquot to chemically represent the distribution of bromide and chloride at the top and bottom of the various electrolytes.

[0129] The open circuit voltage of the cell may be determined as follows: The cell may be charged using the protocol described in Example 3 below. After charging, the open circuit voltage of the cell may be measured. This open circuit voltage may vary depending on the final composition of the mixed polyhalide after charging.

[0130] The UV-visible spectrum of the electrolyte after charging may be determined as follows: The cell may be charged using the protocol described in Example 3 below. The cell may be disconnected from the electrical connection, then opened and an aliquot of electrolyte may be removed from the cell. An aliquot (e.g., 10 mL) may be obtained from the top of the cell, and an aliquot (e.g., 10 mL) may be obtained from the bottom of the cell, and UV-visible spectroscopy may be performed on each aliquot. The type of mixed polyhalide formed may exhibit different UV-visible spectra due to the color of the mixed polyhalide changing depending on the bromide and chloride content in the mixed polyhalide, as shown, for example, in FIG. 6.

[0131] The electrolyte density gradient may be determined as follows: The cell may be charged using the protocol described in Example 3 below. The cell may then be disconnected from the electrical connection, opened, and aliquots of electrolyte removed from the cell. An aliquot (e.g., 10 mL) may be taken from the top of the cell, and an aliquot (e.g., 10 mL) may be taken from the bottom of the cell, and an electrolyte density measurement may be performed on each aliquot.

[0132] (B. Electrochemical Cells) Another aspect of the present disclosure provides a secondary zinc halide battery comprising the initial electrolyte described above. The secondary zinc halide battery is a static (non-flowing) secondary zinc halide battery. The construction of static batteries is well known to those skilled in the art. In the following aspects, the battery is described as a static bipolar electrochemical battery. Those skilled in the art will recognize alternative battery constructions, such as unipolar (or monopolar) batteries. Therefore, alternative static battery constructions will not be discussed in detail herein.

[0133] (B. Static Bipolar Electrochemical Cell) 2 and 3, one embodiment of a static (non-flowing) bipolar zinc halide secondary electrochemical battery 500 of the present disclosure includes at least one bipolar electrochemical cell and two terminal electrochemical cells. In some embodiments, the bipolar electrochemical battery includes approximately 10-50 bipolar electrochemical cells in series and two terminal electrochemical cells. For example, in one embodiment, the bipolar electrochemical battery includes 26 bipolar electrochemical cells in series and two terminal electrochemical cells. In another embodiment, the bipolar electrochemical battery includes 38 bipolar electrochemical cells in series and two terminal electrochemical cells.

[0134] (Bi bipolar electrochemical cell) 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.

[0135] FIG. 1 is an exploded view of an electrochemical cell 100 of the present disclosure, which includes a bipolar electrode 102, a cell frame member 114, a terminal assembly 104, and the initial zinc halide electrolyte described above.

[0136] [1. Bipolar electrode] 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 another side of the bipolar electrode plate opposite the anode surface. On the cathode surface of the bipolar electrode plate 702, a carbon material 624 is secured 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. The structure of the bipolar electrode 502 will be described with reference to the exploded view of the terminal assembly 504 in FIG. 4, as the structure of the bipolar electrode 502 is identical to that of the bipolar electrode of the terminal assembly 504.

[0137] The bipolar electrodes 502 of the present disclosure are configured to plate zinc metal on the anode electrode surface and produce halide or mixed halide species that are reversibly sequestered in the carbon material during charging of the electrochemical cell. Conversely, these electrodes can oxidize the plated zinc metal to produce Zn 2+ The catalyst is configured to produce cations to reduce halide or mixed halide species to their corresponding anions during discharge of the electrochemical cell.

[0138] (a. Bipolar electrode plate) 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 material made conductive by incorporating conductive fillers into the plastic. In some embodiments, the bipolar electrode plate 702 includes a titanium material (e.g., titanium or titanium oxide). In other embodiments, 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 the titanium carbide material. In some embodiments, the bipolar electrode plate 702 includes an electrically conductive carbon material (e.g., a graphite plate). In some examples, 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 an electrically conductive plastic. Any suitable electrically 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 electrically conductive plastic materials may include a base resin polymer having carbon black, graphite, fumed silica, or a combination thereof. For example, the electrically conductive plastics described in U.S. Pat. No. 4,169,816, filed March 6, 1978, which is incorporated herein by reference, may be used within the scope of the present disclosure.

[0139] In some embodiments, the bipolar electrode plates may be substantially rectangular, with one dimension visually larger than the other to give them a rectangular appearance. In the XYZ coordinate space shown in FIG. 3 , the width dimension of the terminal assembly 504 is in the X direction and is the larger dimension relative to the Y dimension. The height dimension of the terminal assembly 504 is in the Y direction and is the shorter dimension relative to the X dimension, giving the illustrated terminal assembly 504 and disassembled battery a rectangular appearance. The Z direction represents the depth (i.e., thickness) of the illustrated battery components. As shown 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 terminal 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 as the width and height, respectively, of the terminal assembly 504 shown in FIG. 7 .

[0140] 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 optionally undergo a surface treatment (e.g., coating, 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 within the electrochemically active area. In other embodiments, the outer surface may also be sandblasted within the electrochemically active area associated with the area enclosed by the cathode assembly.

[0141] In some embodiments, for example, at least a portion of the inner surface, at least a portion of the outer surface, or at least a portion of both surfaces is treated (e.g., sandblasted) to provide a roughened surface. In some cases, at least a portion of the inner surface of a bipolar electrode plate is treated (e.g., sandblasted) to provide a roughened surface. In some cases, the area of ​​the inner surface treated to provide a roughened surface is substantially defined by the periphery of a cathode assembly secured to the outer surface of the electrode plate.

[0142] (b. Cathode Assembly) The electrochemical cell of the present disclosure includes a cathode assembly located on the cathode surface of a bipolar electrode plate 702. In some embodiments, the cathode assembly includes at least one carbon material 624 and an adhesion layer 711 electrically connecting 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 surface) of the bipolar electrode plate 702. In other embodiments, the cathode assembly includes a cathode cage electrically connecting the carbon material 624 to the cathode surface of the bipolar electrode plate 702. Cathode cages are described in U.S. Provisional 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.

[0143] (i. Carbon materials) 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. Suitable carbon materials for the electrochemical cells of the present disclosure may include any carbon material capable of reversibly absorbing aqueous bromine species (e.g., aqueous bromine or aqueous bromide) and that is substantially chemically inert in the presence of an electrolyte. In some embodiments, the carbon material comprises carbon black or other furnace-process carbon. Suitable carbon black materials include, but are not limited to, Cabot Vulcan® XC72R, Akzo-Nobel Ketjenblack EC600JD, and other matte black blends of conductive furnace-process carbon black. In some embodiments, the carbon material may also include other components, including, but not limited to, a PTFE binder and deionized water. For example, the carbon material has a water content of less than 50 wt.% (e.g., between about 0.01 wt.% and about 30 wt.%) by weight of the carbon material. In some embodiments, the carbon material comprises PTFE (eg, about 0.5 wt.% to about 5 wt.%, by weight of the carbon material).

[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.

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

[0146] In some embodiments, the carbon material may be substantially rectangular, with one dimension visually larger than the other to give the article a rectangular appearance. In the XYZ coordinate space shown in FIGS. 3 and 4, the width dimension of the carbon material 624 is in the X direction (shown as "W" in FIG. 4) and is the larger dimension relative to the Y dimension, thereby giving the article a rectangular appearance. The height dimension of the carbon material 624 is in the Y direction (shown as "H" in FIGS. 4 and 10) and is the shorter dimension relative 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. 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.

[0147] [2. Terminal Assembly] 4 , the terminal assembly 504 of the present disclosure includes a terminal connector 708, a conductive plate 704 having an electrically 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, where 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, and 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 area of ​​the conductive plate 704, and where the electrically conductive perimeter 706 allows for bidirectional, uniform current flow through the conductive plate 704 between the terminal connector 708 and the terminal bipolar electrode plate 702.

[0148] The insulating tape member 710 does not cover the entire surface of the conductive plate 704, allowing the electrically conductive perimeter 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 connected in electrical communication with the conductive plate 304. In some embodiments, the outer surface of the conductive plate 704 is bonded to the terminal connector 708. In some embodiments, the terminal connector 708 comprises any electrically conductive material. In one embodiment, the terminal connection comprises brass (e.g., the terminal connector is a tab assembly that is in electrical communication with or contact with the terminal perimeter).

[0149] 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, without limitation, a titanium material coated with a titanium carbide material, through holes, a roughened inner surface, etc. The electrically conductive perimeter 706 of the flat plate 704 with the electrical insulating tape member 710 is joined to the terminal bipolar electrode plate 702 such that the electrically conductive perimeter 706 is approximately centered on an electrochemically active region of the terminal bipolar electrode plate 702. In some embodiments, the electrochemically active region corresponds to the region 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 the charge / discharge cycle of an electrochemical cell. In these embodiments, the electrochemically active area of ​​the terminal bipolar electrode plate 702 associated with the battery's cathode terminal 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., terminal cathode electrode plate). The electrochemically active area of ​​the terminal bipolar electrode plate 702 associated with the battery's anode terminal may correspond to the area on its inner surface facing the cathode assembly disposed on the front surface of an adjacent bipolar electrode plate (terminal anode assembly) that forms a layer of zinc metal upon charging of the battery. 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.

[0150] FIG. 4 provides an exploded view of the terminal assembly used 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, electrically conductive perimeter 306, and terminal connector 708.

[0151] In some embodiments, the electrically conductive perimeter 706 formed by the weld is centered within the electrochemically active area of ​​the terminal bipolar electrode plate 702. In some embodiments, the electrically conductive perimeter 706 is substantially rectangular, substantially circular, or substantially oval. In some embodiments, the electrically conductive perimeter 706 is substantially rectangular.

[0152] In some embodiments, the conductive plate 704 having the electrically insulating tape member 710 is centered within the electrochemically active area of ​​the terminal bipolar electrode plate 702 .

[0153] In some embodiments, the surface of the electrically insulating tape member is joined to the surface of the conductive plate by welding or adhesive, hi some embodiments, the adhesive is electrically conductive.

[0154] 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.

[0155] In some embodiments, the terminal assembly is a terminal cathode assembly, which includes a terminal bipolar electrode plate 702 having an electrochemically active area, a conductive flat plate 704 having an electrically insulating tape member 710 disposed on a surface of the terminal bipolar electrode plate 702 and approximately centered on the electrochemically active area, and a cathode assembly, such as any of the cathode assemblies described herein, disposed on the interior surface of the terminal bipolar electrode plate 702.

[0156] In some embodiments, the terminal assembly is a terminal anode assembly, which includes a terminal bipolar electrode plate 702 having an electrochemically active area, a conductive flat plate 704 having an electrically insulating tape member 710 centered on the electrochemically active area, and the terminal anode assembly is devoid of a cathode assembly.

[0157] In some embodiments, the electrically conductive periphery 706 of the conductive plate 704 having the electrically insulating tape member 710 is joined to the surface of the terminal bipolar electrode plate 702 by welding or adhesive. In some examples, the adhesive is electrically conductive. Non-limiting examples of suitable electrically 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.

[0158] 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 an electrically conductive ceramic.

[0159] In some embodiments, at least one of the conductive plate 704 or the terminal bipolar electrode plate 702 with the electrical 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 electrical insulating tape member 710 comprises a titanium material coated with a titanium carbide material.

[0160] In some embodiments, at least one inner surface of the conductive plate 704 having the electrical insulating tape member 710 comprises copper.

[0161] 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 an electrically conductive ceramic.

[0162] 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.

[0163] In some embodiments, the electrical insulating tape member 710 may be constructed from any adhesive material that is inherently electrically insulating, including, by way of non-limiting example, Kapton®, Mylar®, polyimide, polyethylene, nylon, Teflon®, neoprene, or any other electrically insulating polymer.

[0164] [3. Battery frame components] 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 a terminal assembly 504 (e.g., a terminal anode assembly or a terminal cathode assembly).

[0165] The width and height of the battery frame member 514 are positioned 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 of the battery frame member 514, and the gas channels 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 in the X direction, while the height dimension of the battery frame member 514 is in the Y direction. The depth of the battery frame member 514 is in the Z direction and 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 visually larger than the other to give it a rectangular appearance.

[0166] 5, in one embodiment, the battery frame member 514 has an outer periphery and an inner periphery that defines an open interior region. In some embodiments, the battery frame member 514 is configured so that the open interior region is approximately centered about the center of the electrochemically active area of ​​the terminal bipolar electrode plate 702 received by the battery frame member 514 and / or the center of a cathode assembly disposed on the terminal bipolar electrode plate 702. In some embodiments, the outer periphery of the battery frame member 514 defines the outer surface of the battery.

[0167] In some embodiments, the battery frame member 514 includes a first side that faces and holds the first (terminal) bipolar electrode plate 702 and a second side that faces and holds the second bipolar electrode plate, the second side being positioned on the opposite side of the battery frame member 514 from the first side. The second electrode plate is adjacent to and parallel to the first electrode plate within the battery. The first and second electrode plates and the terminal electrode plate may 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.

[0168] In some embodiments, the battery frame member 514 includes a sealing member 516 ( FIG. 5 ) that extends around the inner periphery of the entire frame. In some embodiments, the battery frame member 514 includes a first sealing member 516 disposed along the first inner periphery. In some embodiments, the first sealing member is an O-ring. In some embodiments, the first sealing member 516 is a gasket. In some embodiments, each inner periphery is configured to receive a sealing member 516 seated therein, which forms a substantially leak-tight seal when the seal is compressed between the corresponding bipolar electrode plate or terminal electrode plate and the battery frame member 514 to provide a sealed interface between the bipolar electrode plate or end plate and the battery frame member 514 when the electrochemical cell is assembled. The sealing members cooperate to retain electrolyte between the opposing bipolar electrode plate and the battery frame member 514, or between the bipolar electrode plate, terminal electrode plate, and the frame member 514. In some embodiments, the sealing member 516 is overmolded onto the frame member 514. In some embodiments, the sealing member 516 is applied to the frame member 514 using a form-in-place liquid curing process. In some embodiments, the sealing member 516 extends above the depth of the frame member 514 and is compressed during assembly.

[0169] In some embodiments, the battery frame member 514 includes a groove in the bottom portion of the battery frame member 514 to prevent voltage abnormalities during cycling. In some embodiments, the groove includes a groove ledge 406 and a clearance space 407 below the groove ledge 406. In some embodiments, the cathode carbon material 624 rests on the groove ledge 406. The presence of the groove ledge and the clearance space below the groove ledge has been found to prevent voltage abnormalities during cycling. In some embodiments, there is no clearance space 407 below the groove ledge 406, and the groove ledge 406 extends to the bottom of the battery frame member 514. In some embodiments, the groove ledge 406 on which the cathode carbon material 624 rests may be 0.5 to 5 cm high, including the clearance space 407 below the groove ledge 406, and may be 3 to 10 mm wide along the entire bottom portion of the width of the battery frame member 514.

[0170] In some embodiments, the battery frame member includes a first frame member and a second frame member, in which 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 flush with a second outer edge of the second frame member.

[0171] 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 around the perimeter of the battery frame member 514 .

[0172] In some embodiments, the battery frame member 514 includes a gas channel 801 at the top of the battery frame member 514 directly above a vent hole 802. The vent hole 802 allows gas to escape into the gas channel 801. In some embodiments, the gas channel 801 associated with each battery frame member 514 is covered, eliminating the need to place a cover over the gas channel 801 after the battery frame members are assembled together. As described herein, the gas channel 801 is the cell headspace for gases from the electrochemical cells within the battery frame member 514. In some embodiments, the frame member 514 is filled with electrolyte through a fill hole in the gas channel (with a plug 809 inserted therein, as shown), and the gas channel 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 channel 801 from the environment. In embodiments in which the fill hole and the vent hole 802 are not the same, the vent hole remains open to the gas channel during battery operation. In other embodiments, the electrolyte is added to the battery through the vent.

[0173] In some embodiments, a liquid diversion system is located at the top of the cell frame member 514, directly below the vent 802 that allows gas to escape into the gas channel 801. While the gas channel 801 provides gas communication throughout the cell 500, the liquid diversion system prevents liquid from entering the gas channel 801 through a series of functions. In some embodiments, the liquid diversion system includes a primary flow diverter 803 with two partial blocking walls 804 and multiple secondary blocking walls 808, ensuring that liquid is always directed back to the open interior area within the cell frame member 514. In some embodiments, the primary flow diverter 803 consists of a horizontal plastic protrusion with end pieces facing downward at an angle ranging from 30 to 60 degrees. In some embodiments, the secondary blocking walls ensure that minimal fluid reaches the primary flow diverter. In some embodiments, the secondary blocking walls 808 herein are designed to alternately face up and down relative to the frame member 514 to break internal electrolyte waves caused by violent sloshing or tilting. One advantage of the liquid shunt system is that it improves battery quality by retaining the electrolyte contained within the frame members during shipping.

[0174] Each battery frame member 514 may be formed from flame-retardant polypropylene fiber, high-density polyethylene, polyphenylene oxide, or polyphenylene ether. Each battery frame member 514 may receive two adjacent bipolar electrode plates, or a bipolar electrode plate and a terminal electrode plate. Each battery frame member 514 may also contain an aqueous electrolyte solution (e.g., a zinc halide electrolyte or a zinc bromide electrolyte), which is received through the vent holes 802.

[0175] [4. Compression plate] 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 used within the scope of the present disclosure, for example, the compression plates described in PCT Publication No. WO2019 / 108513, filed November 27, 2018, which is incorporated herein by reference. [Example]

[0176] [III. Examples]

[0177] [Example 1] Preparation of Mixed Polyhalide Electrolytes and Control Electrolytes A mixed halide initial electrolyte aqueous solution was prepared containing zinc bromide in the concentration range of 0.2 M to 3.0 M, zinc chloride in the concentration range of 1.0 M to 4.0 M, potassium halide salts in the concentration range of 1.0 to 3.5 M, and tetraalkylammonium salts in the concentration range of 0.5 to 1.0 M. An initial electrolyte aqueous solution with the same composition as above but without zinc chloride was also prepared and served as a control electrolyte aqueous solution.

[0178] [Example 2] (Comparison of voltages generated using mixed polyhalide electrolyte and control electrolyte) Test cells were assembled using titanium carbide-coated titanium metal current collectors formed on plates. The anode and cathode plates were placed in a slotted high-density polyethylene cell, which held the plates in a parallel configuration with 14 mm spacing. Prior to cell assembly, carbon felt was attached to the cathode titanium current collector using 0.8 ml of electrically conductive acetone-based glue. The assembled cell was filled with 20 ml of the initial electrolyte described in Example 1. The test cells were cycled using an Arbin Instruments battery cycler. The cells were charged at a constant current of 150 mA to a capacity of 0.9 Ah. The charge voltage limit was 2.3 V. The cells were discharged at a constant current of 140 mA until the voltage reached 1.1 V, and then further discharged at a constant current of 50 mA until the voltage reached 1.1 V. Figure 7 shows representative voltages as a function of test time for a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure and a zinc bromide initial electrolyte that forms polybromides upon charging but does not form mixed polyhalides as disclosed herein. The plot in Figure 7 shows that the cell using the mixed polyhalide initial electrolyte has an open circuit voltage of 2 V (compared to 1.75 V for the conventional zinc bromide battery), a discharge start voltage of 1.86 V (compared to 1.63 V for the conventional zinc bromide battery), and a discharge energy approximately 10–20% higher (depending on the chloride to bromide ratio) than the conventional zinc bromide battery. The results shown in Figure 7 are consistent with the voltage increase in equation (2) above. Notably, the discharge time is also significantly longer with the mixed polyhalide electrolyte. This higher Coulombic efficiency suggests that the proposed electrolyte density gradient reduction mechanism is effective in the mixed polyhalide initial electrolyte.

[0179] As shown in Figure 7, the change to a monotonically increasing charge voltage offers additional advantages for the design and operation of battery energy storage systems (BESSs) compared to battery energy storage systems using control polybromide chemistries. State-of-charge monitoring is a key operational requirement for BESSs, and voltage measurements are traditionally used to track the state of charge during operation. With the voltage profile of control polybromide chemistries, this can be done during discharge, but not during charge, because the flatness of the voltage profile means there is no significant relationship between the state of charge and the charge voltage. This significantly complicates state-of-charge monitoring and overcharge protection when using such batteries. In contrast, the monotonically increasing voltage of polyhalide chemistries means that simpler methods of voltage tracking can be used during both charge and discharge.

[0180] Another advantage associated with the monotonically increasing voltage of polyhalide chemistries compared to batteries with control polybromide chemistries is that they allow for operation of the batteries in a parallel configuration. In such a configuration, the current flowing across each cell is adjusted to ensure that each cell has the same overall voltage. To safely implement such a configuration, it is important that the relationship between the cell voltage and state of charge provides a self-balancing effect, whereby batteries with higher states of charge have higher voltages and thereby draw less current. In the absence of such an effect, operating batteries in parallel can result in significant state-of-charge imbalances, as current mismatches lead to long-term accumulation of state-of-charge imbalances. While the charge voltage profile of control polybromide chemistries does not provide such a self-balancing effect, the voltage profile of polyhalide chemistries does. This leads to significant improvements in operational flexibility and battery energy storage design possibilities.

[0181] [Example 3] (Operating conditions for testing) 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 configuration, separated by a 12 mm thick high-density polyethylene frame containing a recessed sealing ring that allowed the cell to be sealed by compressing the parts between two opposing steel compression plates. Prior to cell assembly, carbon felt was attached to the cathode titanium current collector using 13 ml of electrically conductive acetone-based glue. The assembled cell was filled with 210 ml of the initial electrolyte described in Example 1. The test cells were cycled using an Arbin Instruments battery cycler. Discharge energy, coulombic efficiency, and self-discharge tests were performed under the following conditions:

[0182] Maximum charging voltage: 2.2V~2.4V

[0183] Minimum discharge voltage: 1.1V

[0184] Charging power range: 16mW / cm 2 ~41mW / cm 2 (12mW / mL~31mW / mL)

[0185] Discharge power range: 16mW / cm 2 ~41mW / cm 2 (12mW / mL~31mW / mL)

[0186] Charging capacity range: 68mAh / cm 2 ~137mAh / cm 2 (54mAh / mL~104mAh / mL)

[0187] where the denominator of the geometric area is normalized to the geometric surface area of ​​the cathode electrode and the denominator is normalized to the available electrolyte volume in the cell in mL.

[0188] [Example 4] (Effect of Cl / Br ratio on discharge energy) The cell was constructed and tested as described in Example 3. Figure 8 shows the 165 cm 2A cell with a cathode geometric surface area of ​​97 mAh / cm 2 Figure 1 shows the effect of the overall Cl / Br molar ratio of a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure on discharge energy (Wh) when charged to a capacity of 1000 kJ / cm². The maximum discharge energy occurs when the chloride to bromide ratio is approximately 2:1. This suggests that there is an optimal ratio where the mixed polyhalide species predominates during charge; below this ratio, the high-density polybromide species dominate; above this ratio, there may be insufficient bromide available at the electrode to form the mixed polyhalide. There may be competing effects of the halide ratio, resulting in different beneficial ratios.

[0189] [Example 5] (Comparison of coulombic efficiency of cells containing mixed polyhalide electrolytes and polybromide-only cells) Figure 9 shows representative average coulombic efficiencies (%) over 10 charge-discharge cycles for a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure and a zinc bromide initial electrolyte that forms polybromide upon charging but does not form a mixed polyhalide as disclosed herein. The electrolyte that forms the mixed polyhalide consistently had higher coulombic efficiencies than the polybromide-only electrolyte.

[0190] [Example 6] (Comparison of coulombic efficiency as a function of cycle length between cells containing mixed polyhalide electrolytes and cells containing only polybromide electrolytes) Cells were constructed and tested as described in Example 3. To investigate the coulombic efficiency as a function of cycle length, the cycle length was varied by changing the charging power. Figure 10 shows representative average coulombic efficiencies as a function of cycle length for a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure and a polybromide-only initial electrolyte that forms polybromides upon charging, but not mixed polyhalides as disclosed herein. The coulombic efficiency decreased with cycle length for the polybromide-forming initial electrolyte, but remained nearly constant for the mixed polyhalide-forming electrolyte. This suggests that the self-discharge rate is lower for the mixed polyhalide species compared to the polybromide species.

[0191] [Example 7] (Comparison of cell discharge voltages between cells containing mixed polyhalide electrolyte and polybromide only cells) Cells were constructed and tested as described in Example 3. Figure 11 shows representative cell discharge voltages (V) as a function of cell discharge energy density (Wh / L) for a mixed polyhalide initial electrolyte according to an embodiment of the present disclosure and a zinc bromide initial electrolyte that forms polybromides upon charging but does not form a mixed polyhalide as disclosed herein. The mixed polyhalide initial electrolyte exhibits higher discharge voltages and longer discharge times than the zinc bromide-only initial electrolyte.

[0192] [Other forms] It should be apparent that the foregoing relates only to preferred embodiments of the electrolyte and battery disclosed herein, and that numerous changes and modifications thereto are possible without departing from the spirit and scope of the invention as defined by the following claims and their equivalents.

[0193] From the foregoing and with reference to the various drawing figures, those skilled in the art will understand that certain modifications can 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, it is not intended that the disclosure be limited thereto, for it is intended that the disclosure be as broad as the art will permit, and that the specification be read in the same manner. Accordingly, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. 1. A method for manufacturing a static battery cell, comprising: providing an initial electrolyte comprising one or more sources of chloride ions and one or more sources of bromide ions, said one or more sources of chloride ions and said one or more sources of bromide ions being provided in a predetermined ratio selected to result in a target amount of mixed polyhalides upon at least significant charging of said initial electrolyte; forming an electrochemical cell including an anode, a cathode and said initial electrolyte; A method comprising:

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

3. 3. The method of claim 2, wherein the static zinc halide electrochemical cell is in a static zinc halide battery.

4. The initial electrolyte is about 5 wt. % to about 30 wt. % ZnBr ２ , about 5 wt. % to about 60 wt. % ZnCl ２ , about 10 wt. % to about 60 wt. % H ２ 4. The method of claim 1, further comprising: 0, and about 0.05 wt. % to about 20 wt. % of one or more quaternary ammonium agents.

5. The mixed polyhalide formed upon at least significant charging of the initial electrolyte is represented by the general formula [X （２ｎ＋１） Y （２ｍ） ] － wherein X and Y are different from each other and independently represent either Cl or Br, n is an integer from 0 to 5, and m is an integer from 1 to 5.

6. The mixed polyhalide is BrCl ２ － , ClBr ２ － The method according to any one of claims 1 to 5, wherein the method is a combination thereof.

7. The one or more sources of chloride ions may be ZnCl ２ , KCl, NH ４ Cl, LiCl, CuCl ２ , CaCl ２ , FeCl ３ , SbCl ３ , CrCl ３ , NaCl, BiCl ３ 7. The method of claim 1, wherein the anion is a quaternary ammonium salt containing a chloride anion, or a combination thereof.

8. The one or more sources of bromide ions may be ZnBr ２ , KBr, NH ４ Br, LiBr, CuBr ２ , CaBr ２ , NaBr, AgBr, AlBr ３ 8. The method of claim 1, wherein the anion is a quaternary ammonium salt containing a bromide anion, or a combination thereof.

9. 9. The method of any one of claims 1 to 8, wherein the predetermined ratio of the one or more sources of chloride ions to the one or more sources of bromide ions is a molar ratio of total chloride ions to total bromide ions of from about 1:1 to about 13:

1.

10. 10. The method of any one of claims 1 to 9, wherein the predetermined ratio of the one or more sources of chloride ions to the one or more sources of bromide ions is a molar ratio of total chloride ions to total bromide ions of from about 1:1 to about 2:

1.

11. 11. The method of any one of claims 1 to 10, wherein the initial electrolyte further comprises about 0.5 wt.% to about 15 wt.% KBr and about 0.5 wt.% to about 15 wt.% KCl.

12. 12. The method of claim 1, wherein the initial electrolyte further comprises about 0.5 wt. % to about 15 wt. % KCl.

13. 13. The method of any one of claims 1 to 12, wherein the initial electrolyte comprises about 0 wt. % KBr.

14. The one or more quaternary ammonium agents are of the formula N ＋ (R １ ) (R ２ ) (R ３ ) (R ４ ) X － (In the formula, R １ is hydrogen or an alkyl group, and R ２ , R ３ and R ４ are each independently R １ is an alkyl group that is the same as or different from X － The method of any one of claims 4 to 13, wherein the quaternary ammonium agents having the formula:

15. 15. The method of any one of claims 4 to 14, wherein the one or more quaternary ammonium agents are independently selected from tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, or tetrabutylammonium bromide.

16. 16. The method of any one of claims 1 to 15, wherein the initial electrolyte further comprises about 0.1 wt. % to about 3 wt. % of a glyme, wherein the glyme is monoglyme, diglyme, triglyme, tetraglyme, pentaglyme, hexaglyme, or a combination thereof.

17. 17. The method of any one of claims 1 to 16, wherein the initial electrolyte further comprises up to 1 wt.% of one or more additives selected from Sn, In, Ga, Al, Tl, Bi, Pb, Sb, Ag, Mn, Fe, Cr, Sc, Cu, Al, Ru, Sr, or combinations thereof.

18. 18. The method of any one of claims 1 to 17, wherein the initial electrolyte further 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.

19. 19. The method of any one of claims 1 to 18, wherein the initial electrolyte further comprises PEG having a number average molecular weight of about 1000 amu, PEG having a number average molecular weight of about 3500 amu, or a combination thereof.

20. 20. The method of any one of claims 1 to 19, wherein significant charging of the electrochemical cell occurs when the electrochemical cell undergoes charging until it reaches an open circuit potential of at least 1.82 V and a volumetric charge capacity of at least 54 mAh / mL.

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