Electrode stack for alkaline electrochemical cells

Abstract

In some embodiments, the electrochemical cell (200) may include a container; electrodes disposed within the container, the electrodes including a first set of electrodes and a second set of electrodes, the first set of electrodes including one or more first electrodes (207) and the second set of electrodes including one or more second electrodes (205), the one or more first electrodes and the one or more second electrodes alternating in the stack such that the first electrodes do not contact one another and the second electrodes do not contact one another; a separator set (203, 204) including one or more separators disposed between the first set of electrodes and the second set of electrodes; an electrolyte solution disposed within the container; and a current collector disposed within the container.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 63 / 387,441, filed December 14, 2022, which is incorporated by reference herein in its entirety.

[0002] The present disclosure relates generally to alkaline batteries, and more particularly to alkaline batteries having electrodes arranged in a stacked configuration. [Background technology]

[0003] Alkaline electrochemical cells are commercially available in cell sizes commonly known as LR6 (AA), LR03 (AAA), LR14 (C), and LR20 (D). The cells have a cylindrical shape that must conform to dimensional standards set by organizations such as the International Electrotechnical Commission. Electrochemical cells are utilized by consumers to power a wide range of electrical devices, such as clocks, radios, toys, electronic games, film cameras commonly including flash bulb units, and digital cameras. Such electrical devices have a wide range of discharge conditions, for example, from low drain ("low rate") to relatively high drain ("high rate"). Due to the increased use of high-drain devices, batteries with improved high-rate discharge characteristics are needed. However, improvements in high-rate discharge characteristics can adversely affect low-rate discharge characteristics, and vice versa. Summary of the Invention

[0004] Various embodiments relate to an electrochemical cell comprising: a container having a closed bottom end and an open top end; a closure assembly secured to and closing the open top end of the container; a stack including two or more tablet-shaped electrodes disposed within the container, the two or more tablet-shaped electrodes including one or more sets of first electrodes and one or more sets of second electrodes, the one or more first electrodes and the one or more second electrodes alternating within the stack; a separator set including one or more separators disposed between each electrode in the stack; an electrolyte solution disposed within the container; and a current collector disposed within the container.

[0005] In certain embodiments, the one or more separators of the electrochemical cell include at least one first separator and at least one second separator, wherein the at least one first separator has a different composition from the at least one second separator. In certain embodiments, the one or more first electrodes are anodes comprising a zinc material. In various embodiments, the one or more second electrodes are cathodes comprising a manganese dioxide material. In certain embodiments, the electrochemical cell further includes a second electrode positioned on the lower end of the stack adjacent to the closed lower end of the container. In various embodiments, the electrochemical cell further includes a second electrode positioned on the upper end of the stack adjacent to the open upper end of the container. In certain embodiments, each of the one or more second electrodes defines a central opening extending therethrough, each of the one or more second electrodes further includes an insulating sleeve lining the central opening, and the current collector is a current collector nail extending through the center of the insulating sleeve. In various embodiments, at least one of the one or more separators is secured to each of the one or more first electrodes, and a current collector nail extends through the center of the at least one separator secured to each of the one or more first electrodes and electrically connects with the active material of the one or more first electrodes. In some embodiments, each of the one or more first electrodes includes a gasket that electrically insulates the active material of the one or more first electrodes from the container, and at least one of the one or more separators is secured to the gasket. In various embodiments, each of the one or more second electrodes includes at least one separator, and an insulating sleeve of each of the one or more second electrodes includes one or more grommets that secure the at least one separator of each second electrode.

[0006] Certain embodiments relate to an anode for an electrochemical cell comprising: an anode active material composition; an insulating gasket having open ends, the insulating gasket enclosing the anode active material; and an ion-permeable separator disk secured over each of the open ends of the insulating gasket to seal the anode active material within the insulating gasket.

[0007] In certain embodiments, the anode active material includes particulate zinc suspended in an electrolyte gel, particulate zinc oxide, and dissolved zinc oxide. In various embodiments, the insulating gasket includes a polymeric material. In certain embodiments, the insulating gasket includes a cylindrical sleeve having a first open end and an opposite second open end, a first grommet secured on the first open end, with a first separator secured on the first grommet, and a second grommet secured on the second open end, with a second separator secured on the second grommet. In certain embodiments, the first separator is adhered onto the first grommet, and the second separator is adhered onto the second grommet.

[0008] Various embodiments relate to a cathode comprising: a cathode active material composition formed in an annular shape defining a central opening extending therethrough; a first ion-permeable separator sheet on a first side of the cathode active material composition; a second ion-permeable separator sheet on a second side of the cathode active material composition; and an insulating sleeve positioned within the central opening, a first end of the insulating sleeve extending beyond the first ion-permeable separator sheet to secure the first ion-permeable separator sheet to the first side of the cathode active material composition, and a second end of the insulating sleeve extending beyond the second ion-permeable separator sheet to secure the second ion-permeable separator sheet to the second side of the cathode active material composition.

[0009] In certain embodiments, the first and second ion-permeable separator sheets are planar, and the sidewalls of the cathode active material composition extending between the first and second sides are exposed. In various embodiments, the insulating sleeve includes a first grommet and a second grommet secured to the first grommet within the cylindrical open center of the cathode active material composition.

[0010] Having thus generally described the present disclosure, reference is now made to the accompanying drawings, which are not necessarily drawn to scale. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional elevation view of an exemplary alkaline electrochemical cell. [Figure 2A] FIG. 1 is a cross-sectional elevation view of an exemplary alkaline electrochemical cell having an electrode stackup according to some embodiments. [Figure 2B] 1 is an X-ray image of an electrochemical cell having a stacked electrode tablet configuration according to some embodiments. [Figure 3A] FIG. 1 is a cross-sectional exploded view of an exemplary alkaline electrode set for use in an electrode stack configuration in an electrochemical cell according to some embodiments. [Figure 3B] FIG. 2 is a cross-sectional exploded view of an exemplary cathode tablet according to some embodiments. [Figure 4A] FIG. 2 is a cross-sectional exploded view of components of an exemplary anode tablet according to some embodiments. [Figure 4B] FIG. 2 is a cross-sectional exploded view of components of an exemplary anode tablet according to some embodiments. [Figure 4C] FIG. 2 is a cross-sectional exploded view of components of an exemplary anode tablet according to some embodiments. [Figure 5] 1 is a table of exemplary estimates for electrochemical cell characteristics having stacked electrode configurations according to some embodiments. [Figure 6] 1 is a table of exemplary material compositions for electrochemical cells having stacked electrode configurations according to some embodiments. [Figure 7] 1 is a flowchart of an exemplary method for manufacturing an electrochemical cell according to some embodiments. [Figure 8] 1 is another flowchart of an exemplary method of manufacturing an electrochemical cell according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] Various embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, various embodiments may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. In the following description, various components may be identified as having specific values ​​or parameters. However, these items are provided as exemplary embodiments. In fact, many equivalent parameters, sizes, ranges, and / or values ​​may be implemented, and the exemplary embodiments do not limit various aspects and concepts of the embodiments. The terms “first,” “second,” and the like, “primary,” “exemplary,” “secondary,” and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Furthermore, the terms “a,” “an,” and “the” do not denote a limitation of quantity, but rather indicate the presence of “at least one” of the referenced item. For example, "an organic additive" may refer to two or more organic additives.

[0013] Unless they are clearly mutually inconsistent, each embodiment disclosed herein is intended to be applicable to each of the other embodiments of the present disclosure. All combinations and subcombinations of the various elements described herein are included within the scope of the embodiments.

[0014] When a parameter range is given, it is understood that all integers and ranges within that range, including their first, second, third, fourth, and fifth decimal places, are also provided by the embodiment. For example, "5 to 10%" includes 5%, 6%, 7%, 8%, 9%, and 10%; 5.0%, 5.1%, 5.2%, 9.8%, 9.9%, and 10.0%; and 5.00%, 5.01%, 5.02%, 9.98%, 9.99%, and 10.00%, as well as, for example, 6 to 9%, 7 to 10%, 5.1% to 9.9%, and 5.01% to 9.99%. As another example, "0.00001 to 1M" includes 0.00005 to 0.0001M and 0.001 to 0.01M.

[0015] As used herein, "about" in the context of a numerical value or numerical range means within ±10% of the stated or claimed numerical value or range.

[0016] As used herein, "metal additive" refers to a metal-containing compound added to the electrolyte and / or cathode. Examples are metal salts and metal oxides. As used herein, "metal ion" refers to an ion of any element that can be considered a metal, including, but not limited to, metals, transition metals (any element in Groups 3-12, particularly Groups 4-11 of the Periodic Table), lanthanides, actinides, alkaline earth metals, and alkali metals. "Metal salt" refers to any salt formed from a metal ion. "Metal oxide" refers to any compound containing a metal ion and oxygen in the -2 oxidation state. Examples of metals suitable for the metal salts, metal oxides, and metal ions of the present invention include magnesium (Mg), barium (Ba), nickel (Ni), copper (Cu), aluminum (Al), and cerium (Ce).

[0017] As used herein, "improvement" with respect to specific capacity generally means that the specific capacity is increased. Generally, an "improvement" in a performance characteristic or metric of a material or electrochemical cell means that the performance characteristic or metric is different (compared to that of a different material or electrochemical cell) in a way that a user or manufacturer of the material or cell would find desirable (e.g., lower cost, last longer, provide more power, are more durable, are easier or faster to manufacture, etc.).

[0018] As used herein, "specific capacity" refers to the total amount of charge in an electrochemical cell when discharged at a particular rate, typically measured in ampere-hours.

[0019] As used herein, "run time" refers to the length of time that an electrochemical cell will be capable of providing an effective voltage level, or a voltage above the cut-off voltage.

[0020] The embodiments will be better understood with reference to the figures, which show various embodiments of cylindrical primary electrochemical cells in cross-section elevation. FIG. 1 illustrates an exemplary primary electrochemical cell having a nail- or bobbin-type construction and dimensions comparable to a conventional LR6 (AA)-sized alkaline cell. FIGS. 2A-2B and 3A-3B provide details of alternative arrangements in which the electrodes are configured in a stacked tablet configuration. It will be understood that the embodiments described herein apply to both alkaline (Zn / MnO) and alkaline-P (Zn / MnO + others) primary cell chemistries. The materials and designs for the electrochemical cell components shown in the figures are for illustrative purposes; other materials and designs, including secondary electrochemical cell chemistries, may be used instead. The non-limiting embodiments described above relate to alkaline electrochemical cells with manganese dioxide in the cathode as the active material.

[0021] FIG. 1 shows an electrochemical cell 1 including a container or can 10 having a closed bottom end 24, an open top end 22, and a sidewall 26 (e.g., a cylindrical sidewall) therebetween. The closed bottom end 24 includes a terminal cover 20 including a protrusion. The can 10 has an interior wall 16. In this embodiment, the positive terminal cover 20 is welded or otherwise attached to the bottom end 24. In one embodiment, the terminal cover 20 may be formed using plated steel having a protruding ridge, for example, in its central region. The container 10 may be formed of a metal, such as steel, preferably plated with nickel, cobalt, and / or other metals or alloys on its interior, or other material with sufficient structural properties to accommodate various inputs within the electrochemical cell. A label 28 may be formed around the exterior of the container 10 and may be formed to cover the peripheral edges of the positive terminal cover 20 and the negative terminal cover 46, so long as the negative terminal cover 46 is electrically insulated from the container 10 and the positive terminal 20.

[0022] Within the container 10, a first electrode 18 (e.g., an anode) and a second electrode 12 (e.g., a cathode) are disposed with a separator 14 therebetween. The first electrode 18 is disposed within a space defined by the separator 14 and a closure assembly 40 secured to and closing an open end 22 of the container 10. The closed end 24, sidewall 26, and closure assembly 40 define a cavity in which the cell's electrodes are housed. As described in further detail later in this disclosure, the first electrodes 18 and second electrodes 12 may be stacked vertically, with a plurality of separators 14 collectively embodied as a set of separators disposed therebetween. In some embodiments, a plurality of the first electrodes 18 and second electrodes 12 may be stacked vertically in an alternating arrangement, with individual separators 14 from the set of separators 14 disposed therebetween. For example, a stack may include a second electrode on the bottom of the stack, a separator, a first electrode, another separator, and then another second electrode, with the stack continuing in this arrangement until the electrochemical cells are filled or the desired height for the stack is reached. It should be understood that in other embodiments, the first electrode is positioned on the bottom of the stack. This stack configuration and variations are described in more detail later in this disclosure.

[0023] The closure assembly 40 includes a closure member 42, such as a gasket, a current collector 44, and a conductive terminal 46 in electrical contact with the current collector 44. The closure member 42 preferably includes a pressure relief vent that would allow the closure member to rupture if the cell's internal pressure becomes excessive. The closure member 42 may be formed from another material, such as a polymeric or elastomeric material, e.g., an injection-moldable polymer blend such as nylon-6,6, poly(phenylene oxide) or a polystyrene-combined polypropylene matrix, or a metal, provided that the current collector 44 and conductive terminal 46 are electrically insulated from the container 10, which serves as a current collector for the second electrode 12 (cathode). In the illustrated embodiment, the current collector 44 is an elongated, nail- or bobbin-shaped element that extends into the first electrode 18 (anode). The current collector 44 is made of one or more metals or metal alloys, such as copper or brass. In certain embodiments, the current collector 44 portion may be a conductively plated nail / rod having a metal or plastic core plated with one or more metals or metal alloys. Other suitable materials may also be utilized. The current collector 44 is inserted through a hole (e.g., a centrally located hole) in the closure member 42. In some embodiments, the electrodes 12 and 18 may be configured to be annular in shape, with the current collector 44 disposed through the center of the ring.

[0024] First electrode 18 is preferably the negative electrode or anode. The negative electrode comprises a mixture of one or more active materials, a conductive material, optionally solid zinc oxide, and a surfactant. The negative electrode may optionally include other additives, such as binders or gelling agents, and the like. Exemplary anode compositions that can be used in the electrochemical cells described herein are described in detail in U.S. Patent Application Publication No. 2023 / 0107037, which is incorporated herein by reference in its entirety.

[0025] Zinc is an exemplary primary active material for the negative electrode of embodiments. In alternative embodiments, mercury, aluminum, silicon, lithium, and magnesium may also be used. Preferably, the volume of active material utilized in the negative electrode is sufficient to maintain the desired particle-to-particle contact and the desired anode-to-cathode (A:C) ratio.

[0026] Particle-to-particle contact must be maintained throughout the useful life of the battery. If the volume of active material in the negative electrode is too small, the cell voltage may suddenly drop to an unacceptably low value when the cell is powering the device. The voltage drop is believed to be caused by a loss of continuity within the negative electrode's conductive matrix. The conductive matrix may be formed from undischarged active material particles, conductive electrochemically generated oxides, or a combination of these. The voltage drop may occur after oxides begin to form but before a sufficient network has been established to bridge all of the active material particles present.

[0027] Zinc suitable for use in the embodiments can be produced from a number of different commercial sources under various designations, such as BIA 100, BIA 115, etc. Umicore SA, Brussels, Belgium, is an example of a zinc supplier. In a preferred embodiment, the zinc powder generally has 25 to 40 percent fines less than 75 μm, and preferably 28 to 38 percent fines less than 75 μm. Generally, a lower percentage of fines will not allow the desired DSC service to be achieved, and utilizing a higher percentage of fines may result in increased gassing. A suitable zinc alloy is required to reduce gassing of the negative electrode in the cell and maintain test service results.

[0028] Typically, a surfactant is present in the negative electrode, either a nonionic surfactant or an anionic surfactant, or a combination thereof. It has been found that the anode resistance increases during discharge with the addition of solid zinc oxide alone, but is mitigated by the addition of a surfactant. The addition of a surfactant increases the surface charge density of the solid zinc oxide, which, as shown above, reduces the anode resistance.

[0029] One exemplary surfactant is DISPERBYK-190 from BYK-Chemie GmbH of Wesel, Germany. The surfactant is present in an amount sufficient to disperse the solid zinc oxide, preferably from about 0.00064 to about 0.20 weight percent or more, based on the total weight of the negative electrode. DISPERBYK-190 is believed to be a solution containing a water-soluble, high molecular weight block copolymer containing one or more functional groups, believed to be at least two different types of functional groups. The surfactant has anionic / nonionic characteristics due to its respective functional groups. Furthermore, the number average molecular weight of the block copolymer DISPERBYK-190 is believed to be greater than 1000, as measured using gel permeation chromatography. Water solubility, if present in the electrode composition, may be offset by the presence of a hydrophobic component. In one embodiment, the surfactant is utilized in an amount of from about 10 to about 100 ppm, preferably from about 15 to about 50 ppm of zinc is utilized in the negative electrode. DISPERBYK-190 does not contain any organic solvents and is therefore considered suitable for water-based systems. DISPERBYK-190 has an acid number in mg KOH / g of 10 and a density of 1.06 g / ml at 20°C.

[0030] In one embodiment, the negative electrode comprises solid zinc oxide in an amount of about 0.2 to 5 weight percent, based on the total weight of the negative electrode. In one embodiment, the negative electrode comprises solid zinc oxide in an amount of about 1 to 4 weight percent. In a preferred embodiment, the negative electrode comprises solid zinc oxide in an amount of about 0.3 to 1 weight percent. In a more preferred embodiment, the negative electrode comprises solid zinc oxide in an amount of about 0.66 weight percent.

[0031] In one embodiment, zinc oxide is substituted to reduce its solubility. In one embodiment, the zinc portion in the zinc oxide is substituted with another cation. In one embodiment, the substituted zinc oxide has the formula Zn 1-x Y x O. Here, Y is at least one cation substituent, and 0 < x ≦ 0.50. In one embodiment, the cation substituent is selected from the group consisting of Mg, Ca, Bi, Ba, Al, Si, Be, Cd, Ni, Co, Sn, and Sr, and any combination thereof. In one embodiment, x is 0.01 to 0.40, or 0.02 to 0.35, or 0.04 to 0.30, or 0.05 to 0.25, or 0.10 to 0.20. In one embodiment, x is ≧ 0.01, ≧ 0.02, ≧ 0.04, ≧ 0.06, ≧ 0.08, ≧ 0.10, ≧ 0.12, ≧ 0.14, ≧ 0.16, ≧ 0.18, ≧ 0.20, ≧ 0.25, ≧ 0.30, ≧ 0.35, or ≧ 0.40.

[0032] In one embodiment, the oxygen portion in the zinc oxide is substituted with another anion. In one embodiment, the substituted zinc oxide has the formula ZnO 1-w A (2w / z) . Here, A is at least one anion substituent, 0 < w ≦ 0.50, and z is the charge of the anion substituent. In one embodiment, the anion substituent is selected from the group consisting of CO3 2- and PO4[[ID=!17]] 3- , and combinations thereof. In one embodiment, w is 0.01 to 0.40, or 0.02 to 0.35, or 0.04 to 0.30, or 0.05 to 0.25, or 0.10 to 0.20. In one embodiment, w is ≧ 0.01, ≧ 0.02, ≧ 0.04, ≧ 0.06, ≧ 0.08, ≧ 0.10, ≧ 0.12, ≧ 0.14, ≧ 0.16, ≧ 0.18, ≧ 0.20, ≧ 0.25, ≧ 0.30, ≧ 0.35, or ≧ 0.40. In one embodiment, the zinc oxide contains cation substituents and anion substituents.

[0033] It should be noted that there seems to be an error in the original text where "PO4 3- " is written as "PO4 " in the middle of the text. The corrected translation is provided above with the appropriate handling of this error. If this is not what you intended, please check the original text again.In one embodiment, the aqueous electrolyte is an aqueous alkali metal hydroxide electrolyte and includes an alkali metal hydroxide, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), or the like, or a mixture thereof. Potassium hydroxide is preferred. The alkaline electrolyte used to form the gel electrolyte of the negative electrode contains the alkali metal hydroxide in an amount of about 26 to about 36 weight percent, e.g., about 26 to about 32 weight percent, and particularly about 26 to about 30 weight percent, based on the total weight of the alkaline electrolyte. It has been found that interactions occur between the negative electrode alkali metal hydroxide and the added solid zinc oxide, and that less alkaline metal hydroxides improve DSC service. Less alkaline electrolytes are preferred, but can result in rapid electrolyte separation at the anode. Increasing the alkali metal hydroxide concentration creates a more stable anode but can degrade DSC service. The metal ions in the electrolyte can have a concentration of 0.1 to 20,000 ppm. In an alternative embodiment, the electrolyte can be neutral or salt-based, as in zinc-carbon cells.

[0034] The aqueous alkaline electrolyte solution also includes dissolved zinc oxide in an amount of about 1.5 to 4 weight percent, based on the total weight of the aqueous alkaline electrolyte solution.

[0035] As is well known in the art, a gelling agent is preferably utilized in the negative electrode, such as cross-linked polyacrylic acid, such as Carbopol® 940, available from Noveon, Inc. of Cleveland, Ohio, USA. Carboxymethyl cellulose, polyacrylamide, and sodium polyacrylate are examples of other gelling agents suitable for use in alkaline electrolyte solutions. The gelling agent is desirable to maintain a substantially uniform dispersion of zinc and solid zinc oxide particles within the negative electrode. The amount of gelling agent present is selected to result in a lower electrolyte separation rate and not excessively increase the anode viscosity at yield stress, which can cause problems related to dispensing the anode.

[0036] To improve plating on the nail current collector and reduce negative electrode outgassing, dissolved zinc oxide is preferably present in the anode via dissolution in the aqueous electrolyte solution. The added dissolved zinc oxide is separate and distinct from the solid zinc oxide present in the anode composition. In one embodiment, a level of dissolved zinc oxide in an amount of 3 to 4 weight percent based on the total weight of the negative electrode electrolyte solution is preferred. In one embodiment, dissolved zinc oxide is present in the negative electrode electrolyte solution in an amount greater than 3 weight percent. Soluble or dissolved zinc oxide generally has a specific surface area of ​​about 4 m, as measured using a Tristar 3000 BET specific surface area analyzer from Micrometrics with multipoint calibration after the zinc oxide is allowed to degas for 1 hour at 150°C. 2 / g or less, and a particle size D50 (average particle size) of about 1 μm, measured using a CILAS particle size analyzer as set forth above.

[0037] Other components that may optionally be present in the negative electrode include, but are not limited to, anti-gassing agents, organic or inorganic corrosion inhibitors, plating agents, binders, or other surfactants. Examples of anti-gassing or corrosion inhibitors may include indium salts, such as indium hydroxide, perfluoroalkylammonium salts, alkali metal sulfides, etc.

[0038] The negative electrode can be formed in a number of different ways known in the art, for example, the negative electrode components can be dry blended and added to the cell, the alkaline electrolyte is added separately, or, as in the preferred embodiment, a pre-gelled negative electrode process is utilized.

[0039] In one embodiment, zinc and solid zinc oxide powders, as well as any optional powders other than the gelling agent, are combined and mixed. A surfactant is then introduced into the mixture containing zinc and solid zinc oxide. A pregel containing alkaline electrolyte, soluble zinc oxide, and a gelling agent, and optionally other liquid components, are introduced into the surfactant, zinc, and solid zinc oxide mixture, which are further mixed to obtain a substantially uniform mixture prior to addition to the cell. Alternatively, in a more preferred embodiment, solid zinc oxide is pre-dispersed in a negative electrode pregel containing alkaline electrolyte, a gelling agent, soluble zinc oxide, and other desired liquids, and blended for, e.g., about 15 minutes. Next, solid zinc oxide and surfactant are added, and the negative electrode is blended for an additional period of time, such as about 20 minutes. The amount of gel electrolyte utilized in the negative electrode is generally about 25 to about 35 weight percent, e.g., about 32 weight percent, based on the total weight of the negative electrode. The volume percentage of the gel electrolyte can be about 70% based on the total volume of the negative electrode.

[0040] In addition to the aqueous alkaline electrolyte absorbed by the gelling agent during the negative electrode fabrication process, an additional amount of an aqueous solution of alkali metal hydroxide, i.e., “electrolyte shot,” “free electrolyte,” or “alkaline electrolyte solution,” is added to the cell during the fabrication process. The electrolyte shot can be incorporated into the cell by placing it in the cavity defined by the positive electrode, negative electrode, or a combination thereof. The method used to incorporate the electrolyte shot into the cell is not important as long as it contacts the negative electrode, positive electrode, and separator. In one embodiment, the electrolyte shot is added both before and after the addition of the negative electrode mixture. In one embodiment, approximately 0.97 grams of a 29 weight percent KOH solution is added to an LR6-type cell as the electrolyte shot, and approximately 0.87 grams is added to the separator-lined cavity before the negative electrode is inserted. The remaining portion of the 29 weight percent KOH solution is injected into the separator-lined cavity after the negative electrode is inserted. In certain embodiments, the electrolyte shot includes an alkali metal hydroxide electrolyte (e.g., KOH). The alkali metal hydroxide electrolyte can have dissolved zinc oxide or zinc hydroxide. In certain embodiments, the alkali metal hydroxide electrolyte comprises dissolved zinc oxide in the range of about 0.01 to 6.0 weight percent.In embodiments, the electrolyte shot is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6 ,3.7,3.8,3.9,4.0,4.1,4.2,4.3,4.4,4.5,4.6,4.7,4.8,4.9,5.0,5.1,5.2,5.3,5.4,5.5,5.6,5.7,5.8,5.9,6.0,6.1,6.2,6.3,6.4,6.5,6.6,6.7,6.8,6.9,7.0,7.1,7.2,7.3,7.4,7.5,7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3 , 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13.0, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, or 14.0 weight percent dissolved zinc oxide equivalent.

[0041] The electrolyte shot, in one embodiment, contains a metal additive and is a source of metal ions that will adsorb onto the manganese dioxide-containing cathode. In one embodiment, the same metal additive present in the electrolyte shot is present in the electrolyte solution incorporated into the cathode. In one embodiment, the electrolyte shot has a different metal additive concentration than the cathode electrolyte solution. In an alternative embodiment, the electrolyte shot and the cathode electrolyte solution have the same metal additive concentration. In one embodiment, the metal additive present in the electrolyte shot is not present in the cathode.

[0042] In one embodiment, the metal additive will be insoluble or have very low solubility in the electrolyte solution at room temperature (~25°C). In one embodiment, the metal additive will be insoluble in the electrolyte solution at 1 x 10 -x where x is 10 to 75.

[0043] The second electrode 12, also referred to herein as the positive electrode or cathode, preferably includes manganese dioxide (commonly referred to as EMD) as the electrochemically active material. The EMD is generally present in an amount of about 80 to about 92 weight percent, and preferably about 81 to 85 weight percent, based on the total weight of the positive electrode, i.e., manganese dioxide, conductive material, positive electrode electrolyte, and additives, if present, including organic additives. The positive electrode is formed by combining and mixing the desired components of the electrode, subsequently dispensing a quantity of the mixture into the open end of a container, and then using a ram to form the mixture into a solid tubular configuration that defines a cavity within the container into which the separator 14 and first electrode 18 will later be disposed. The second electrode 12 has a ledge 30 and an interior surface 32, as shown in FIG. 1 . Alternatively, the positive electrode may be formed by preforming multiple rings from a mixture containing EMD and, optionally, additives, and then inserting the rings into a container to form a tubular second electrode. The cell shown in Figure 1 will typically include three or four rings.

[0044] The positive electrode can include other components, such as a conductive material, e.g., graphite, that, when mixed with the EMD, provides a conductive matrix substantially throughout the positive electrode. The conductive material can be natural, i.e., mined, or synthetic, i.e., man-made. In one embodiment, the cell includes a positive electrode having an active material, or oxide-to-carbon (O:C) ratio, ranging from about 12 to about 24. In one embodiment, the O:C ratio ranges from about 12 to 14. Too high an oxide-to-carbon ratio can reduce the can-to-cathode resistance, which can affect overall cell resistance and potentially affect high-rate testing, such as DSC testing, or higher cutoff voltages. Furthermore, the graphite can be expandable or non-expandable. Suppliers of graphite for use in alkaline batteries include Timcal America of Westlake, Ohio, Superior Graphite Company of Chicago, Ill., and Lonza, Ltd. of Basel, Switzerland. The conductive material is generally present in an amount of about 5 to about 10 weight percent based on the total weight of the positive electrode. Too much graphite can reduce EMD input and therefore cell capacity, while too little graphite can increase the can-to-cathode contact resistance and / or bulk cathode resistance. One example of an additional additive is barium sulfate (BaSO4), commercially available from Bario E. Derivati ​​S.p.A. of Massa, Italy. Barium sulfate is generally present in an amount of about 1 to about 2 weight percent based on the total weight of the positive electrode. Other additives can include, for example, barium acetate, titanium dioxide, binders such as coastylene, and calcium stearate.

[0045] In one embodiment, the cathode comprises the metal additive as a solid. In one embodiment, the metal additive is present as a solid in the cathode at a concentration of 0.1 to 1000 ppm relative to the total mass of the cathode.

[0046] In some embodiments, the cathode may include a nickelate material as described in U.S. Patent No. 11,560,321, which is incorporated by reference herein in its entirety.

[0047] In one embodiment, the positive electrode component (EMD), conductive material, and barium sulfate, and optionally, additives, are mixed together to form a uniform mixture. During the mixing process, an alkaline electrolyte solution, such as an approximately 37% to approximately 40% KOH solution, optionally containing organic additives, is evenly dispersed within the mixture, ensuring uniform distribution of the solution throughout the positive electrode material. The mixture is then added to a container and molded using a ram. The moisture content within the container and the positive electrode mixture before and after molding, as well as the components of the mixture, are preferably optimized to enable high-quality positive electrodes to be molded. Optimizing the mixture moisture minimizes splashing and flashing caused by a wet mixture and minimizes spalling and excessive tool wear caused by a dry mixture, helping to achieve the desired high cathode weight. The moisture content within the positive electrode mixture can affect the overall cell electrolyte balance and impact high-rate testing.

[0048] One of the parameters utilized by cell designers characterizes cell designs as the anode (A) to cathode (C) ratio, i.e., the ratio of the electrochemical capacity of one electrode to the electrochemical capacity of the opposing electrode, such as the A:C ratio. For LR6-type alkaline primary cells utilizing zinc in the negative electrode or anode and MnO2 in the positive electrode or cathode, the A:C ratio can be greater than 1.32:1, e.g., greater than 1.34:1, and particularly 1.36:1, for impact-molded positive electrodes. The A:C ratio for ring-molded positive electrodes can be lower, such as from about 1.3:1 to about 1.1:1. The cathode can be ring-molded in some embodiments.

[0049] A separator 14 is provided to separate the first electrode 18 from the second electrode 12. The separator 14 maintains physical isolation of the positive electrode's electrochemically active material from the negative electrode's electrochemically active material, allowing ion transport between the electrode materials. In addition, the separator serves as a wicking medium for the electrolyte and a collar to prevent fragmented portions of the negative electrode from contacting the top of the positive electrode. The separator 14 can be a layered, ion-permeable nonwoven fabric. A typical separator typically includes two or more layers of paper. Conventional separators are typically formed by preforming the separator material into a cup-shaped basket (which is then inserted under the cavity defined by the second electrode 12 and closed end 24 and any positive electrode material thereon), or by inserting two rectangular sheets of the separator into the cavity with the material rotated 90° relative to each other to form the basket during cell assembly. Conventional preformed separators typically consist of a sheet of nonwoven fabric rolled into a cylindrical shape that conforms to the interior wall of the second electrode and has a closed bottom end.

[0050] Exemplary Alkaline Electrochemical Cell with Stacked Electrodes Batteries with high anode / cathode interfacial areas may have better high-rate performance (e.g., longer run times for high-discharge devices). However, electrochemical cells with high interfacial areas require correspondingly high separator surface areas to keep the anode and cathode electrically isolated. Due to the increased volume resulting from the higher surface area of ​​the included separator material, electrochemical cells with increased interfacial area between electrodes (compared to the traditional bobbin-type cell described and shown with reference to FIG. 1 ) have limited remaining volume for the anode and cathode active materials. In addition, high interfacial area cell designs with multiple anodes and / or multiple cathodes require additional current collectors per electrode to electrically connect the electrodes to their respective terminals outside the cell. Again, these required current collectors occupy additional volume within the cell, further constraining the amount of space available for the active materials. Furthermore, these configurations increase the complexity of production assembly for electrochemical cells.

[0051] In contrast to conventional "bobbin"-type designs of electrochemical cells, the exemplary stacked electrode cell configurations described herein include tablet-shaped electrodes (e.g., cylindrical, square, rectangular, and / or other shapes). The tablet-shaped electrodes have an outer periphery shaped to fit within the cell can (e.g., a circular periphery to fit within a cylindrical cell). The tablet-shaped electrodes have a dual interface between adjacent electrodes. That is, each tablet-shaped electrode can be separated (by a separator) from another electrode at the top or bottom of the electrode. As a specific example, an anode electrode can be positioned such that a cathode electrode is disposed on either side of the anode electrode (both above and below the anode electrode), and a cathode electrode can be positioned such that an anode electrode is disposed on either side of the cathode electrode (both above and below the cathode electrode). Multiple tablet-shaped electrodes can be positioned within a cell to fill the cell canister. As an example, two electrodes (e.g., one anode and one cathode), three electrodes (e.g., two cathodes and one anode), four electrodes, five electrodes, six electrodes, seven electrodes, and / or the like may be disposed within the cell canister. The height of the tablet-shaped electrodes may be determined by the total number of electrodes to be positioned within the cell canister to maximize the amount of active material in the electrodes disposed within the cell. For example, a tablet-shaped electrode of a cell having five tablet-shaped electrodes positioned therein will have a greater height than a tablet-shaped electrode of a cell having seven tablet-shaped electrodes positioned therein (for a cell of the same size and shape). As described in more detail herein, each tablet-shaped electrode includes an insulating component to insulate the electrode active material from the current collector of the opposite polarity. For example, the cathode electrode tablet includes a centrally located insulating component (e.g., a centrally located insulating sleeve and / or grommet lining a centrally located hole extending through the cathode) to insulate the cathode active material from the centrally located anode current collector (e.g., a current collector nail extending along the central axis of the cell).The anode electrode tablet includes a ring-shaped insulating component (e.g., a ring-shaped gasket positioned around the periphery of the anode electrode tablet and / or one or more lids / caps secured to the ring-shaped gasket) positioned on the periphery of the anode electrode tablet to insulate the anode active material from the cell can, which serves as the cathode current collector. A separator disk is further provided to separate the anode and cathode active materials from each other.

[0052] Although these tablet-type electrodes require additional non-active materials in the cell (e.g., additional separator material, insulating components not present in bobbin-type cells, and / or the like), the increased surface area between the electrodes contributes to more complete discharge of the active material in the electrodes during high-rate discharge compared to bobbin-type cells, resulting in a higher theoretical capacity for cells with stacked electrode tablets than for bobbin-type cells with the same electrode active material composition.

[0053] These configurations may also be distinguished from other exemplary cell configurations, such as "jelly roll" type cells, which may require metal foil current collectors to block diffusion. The configurations described in this disclosure may also include electrodes having reduced thicknesses compared to those in "bobbin" and "jelly roll" type cells.

[0054] 2A-4C illustrate electrode configurations (tablet-shaped electrodes positioned within an electrode stack including two or more electrodes) for electrochemical cells having increased interfacial area (per volume of active material) between the anode and cathode compared to the bobbin-type cell shown in FIG. 1 . Specifically, FIG. 2A is a schematic diagram of a cutaway view of an electrochemical cell cut along the vertical center plane of the electrochemical cell. FIG. 2B is an X-ray view of an exemplary electrochemical cell having a configuration described herein. FIGS. 3A-4C illustrate schematic exploded views of anode and cathode components (alternatively referred to herein as electrode “tablets”) that may be positioned within an electrochemical cell with a stacked electrode configuration. In the stacked electrode configurations shown in the figures, each electrode is embodied as an annular “tablet” within the stack. As noted above, other electrode tablet shapes may also be provided in certain embodiments to accommodate other electrochemical cell geometries. These tablet-shaped electrodes are stacked in an electrochemical cell can in an alternating arrangement (e.g., alternating anode tablets and cathode tablets along the height of the stack of electrodes in the electrochemical cell). Adjacent electrodes are separated from each other by one or more layers of separator material (e.g., separator paper provided as a separator disk that may be affixed as part of one or more of the electrodes). In certain embodiments, the number of anode electrodes is the same as the number of cathode electrodes, while in other embodiments, the number of anode electrodes may differ from the number of cathode electrodes.

[0055] It will be understood that the figures shown and described in this disclosure are exemplary, and that some components (including, but not limited to, separators, cans, and current collectors) have been removed for clarity and to highlight various components of the embodiments of the present disclosure. Furthermore, the active material compositions of each of the anode, cathode, current collector, separator sheet, can, and other components as described with reference to FIG. 1 may be utilized in the embodiments of FIGS. 2A-4C. For example, when referring to various electrodes in the description for FIGS. 2A-4C, the description of the first electrode 18 (e.g., anode) and second electrode 12 (e.g., cathode)—including their compositions—from previous sections of this disclosure may apply to the first and second electrodes shown and described for FIGS. 2A-4C.

[0056] 2A-4C, in some embodiments, an electrochemical cell 200 is provided. FIGS. 2A-2B show views of an assembled cell 200 having a stack of tablet-shaped electrodes therein, while FIGS. 3A-3B show exploded views of a single cathode tablet for placement within a stack of cells 200 to illustrate the various components of the cathode tablet, according to various embodiments. FIGS. 4A-4C show exploded views of an exemplary anode tablet for placement within a stack of electrodes in cell 200, according to certain embodiments.

[0057] In some embodiments, cell 200 includes a plurality of first electrodes 207 (anodes) and a plurality of second electrodes 205 (cathodes) arranged in a stack within cell 200. In some embodiments, the plurality of first electrodes 207 may be considered collectively as a set of first electrodes, and the plurality of second electrodes 205 may be considered collectively as a set of second electrodes. This stack arrangement can be seen at least in FIGS. 2A-2B, where the stack alternates between first electrodes 207 and second electrodes 205. As also shown in FIGS. 2A-2B, the second electrodes 205 (cathodes) are disposed at the bottom of the stack, while the first electrodes 207 (anodes) are disposed at the top of the stack. In some embodiments, the first and second electrodes 207, 205 may be disposed within a can 210 that serves as a current collector and is in conductive contact with each of the second electrodes 205 (through the exposed sidewalls of the second electrodes 205). Thus, the second electrodes 205 may be in contact with the interior walls of the can, while the first electrode 207 may be insulated from the interior walls of the can 210 (e.g., by an anode gasket 201, as described below). In some embodiments, the first and second electrodes 207, 205 may have an annular shape within the cylindrical cell 200. In some embodiments, a current collector 209 may be disposed within the cell 200 and in conductive contact with each of the first electrodes 207. In some embodiments, the current collector 209 may be disposed within a central opening extending centrally through each of the second electrodes 205 and the anode (while being electrically insulated from the cathode material by grommets, as described herein). In some embodiments, the current collector 209 may be configured so that it does not extend into (or completely through) the second electrode 205 on the bottom of the stack.

[0058] In some embodiments, the first electrode 207 may have the composition of the anode 18 as described above with respect to FIG. 1 . In some embodiments, the first electrode 207 may include zinc active material disposed in an electrolyte shot. In some embodiments, the first electrode 207 may be contained within an anode gasket 201 to electrically insulate the first electrode 207 from the can 210. In some embodiments, the anode gasket 201 may be ring-shaped and have an interference fit with the can 210 for a tight fit. In some embodiments, the anode gasket 201 may be composed of a thermoplastic material, such as polypropylene or nylon. Additionally, the anode gasket 201 may compress the separator (described below) to prevent leakage of electrode material around the separator's edges, which could create a short circuit between adjacent anodes and cathodes.

[0059] 4A-4C illustrate alternative embodiments of an anode gasket 201 according to certain embodiments. In the embodiment of FIGS. 4A-4B, including both a cutaway view ( FIG. 4A ) and an exploded view ( FIG. 4B ), the anode gasket 201 includes a sleeve 221 (e.g., a cylindrical sleeve) that surrounds the outer periphery of an anode material (not shown). Grommets 222 are secured to opposite ends of the sleeve 221, with inner portions of the grommets extending into the interior of the sleeve. The grommets 222 may be constructed of the same material as the sleeve 221. The grommets 222 may be friction-fit within the interior of the sleeve, such that the outer surface of the inner portion of each grommet 222 is in frictional contact with the inner surface of the sleeve 221. As shown, the grommets 222 additionally include outer portions having a diameter that at least substantially matches the outer diameter of the sleeve 221. Grommet 222 additionally is characterized by at least a substantially planar end surface to which separator disk 223 (comprising a separator material as described herein) is secured (e.g., adhered with an adhesive). The resulting anode tablet 207 is sealed within sleeve 221, grommet 222, and separator disk 223. As described herein, separator disk 223 can be pierced by nail current collector 209 during assembly of electrochemical cell 200 to electrically connect the anode material in anode tablet 207 with the negative terminal of electrochemical cell 200.

[0060] 4C shows a cutaway view of another alternative embodiment of an anode gasket 201 according to certain embodiments. As shown in FIG. 4C, the anode gasket 201 includes an anode cup 225 (e.g., a cylindrical anode cup), an anode lid 226 (e.g., a cylindrical anode lid) secured (e.g., friction-secured, glued, and / or the like) to the anode cup 225 to form the anode gasket 201, and a separator disk 223 secured to the opposite open end of the anode gasket 201. In the illustrated embodiment, the anode cup 225 defines a cylindrical outer surface having a hollow interior. The hollow interior is defined by a stepped inner surface having a wide portion and a narrow portion. The narrow portion has an inner surface that is parallel to the inner surface of the wide portion. The narrow portion defines a first open end of the anode gasket 201 to which the separator disk 223 is secured (e.g., glued).

[0061] The anode lid 226 can be formed from the same material (e.g., an insulating material) as the anode cup 225. While not drawn to scale in FIG. 4C , the anode lid 226 in the illustrated embodiment defines an at least substantially uniform cylindrical inner surface. The diameter of the inner surface is at least substantially the same as the diameter of the inner surface of the narrow portion of the anode cup 225. The outer surface of the anode lid 226 defines a stepped profile that fits securely within the wider portion of the anode cup 225. The anode lid 226 has a length to fit within the anode cup 225 such that the at least substantially uniform cylindrical inner surface of the anode lid is positioned adjacent the narrow portion of the anode cup 225 to collectively define an at least substantially continuous inner surface of the anode gasket 201 that encloses the anode material. As shown, a separator disk 223 is secured (e.g., glued) onto the open end of the anode lid 226 to seal the anode material within the anode gasket 201.

[0062] In some embodiments, second electrode 205 can have the composition of cathode 12 as described above with respect to Figure 1. In some embodiments, as shown in the exploded views in Figures 3A-3B, second electrode 205 can be an assembly including tablet 208 with one or more ion-permeable separator sheets 203, 204 (including a first ion-permeable separator sheet and a second ion-permeable separator sheet having a different composition than the first) disposed on either side (top and bottom) of tablet 208, and a centrally located grommet (embodied as a two-part grommet including male and female grommets 202, 206) separating second electrode 205 from current collector 209. As shown, the second electrode 205 has exposed sidewalls (extending between the top and bottom separator sheets of the second electrode 205) such that when the tablet-shaped second electrode 205 is placed within the cell canister, the active material within the cathode is placed in electrical contact with the cell canister, which acts as the cathode current collector.

[0063] In some embodiments, tablet 208 may be cathode tablet 208. In some embodiments, one or more separator sheets 203, 204 may be part of a separator set including multiple separator sheets 203, 204. In certain embodiments, separator sheet 203 is a first separator and separator sheet 204 is a second separator. First separator sheet 203 and second separator sheet 204 may include the same separator material (being of the same separator composition) or different separator materials (being of different separator compositions). Like anode gasket 201, the opposing side of the grommet may compress the separator to further seal against short circuits created around the separator layer between adjacent electrodes. In some embodiments, the grommets 202, 206 may be separator material and the second electrode 205 may be sealed within the separator sheets 203, 204, which would eliminate the need for the grommets 202, 206.

[0064] In some embodiments, the grommets 202, 206 may provide electrical insulation between the first electrode 207 and the second electrode 205. In some embodiments, the grommets 202, 206 may help guide the insertion of the current collector 209. That is, the current collector 209 may be disposed through an internal bore of the grommets 202, 206. In some embodiments, the grommets 202, 206 may be friction-fit with the outer surface of the current collector 209, while in other embodiments, the current collector 209 may be disposed through an internal bore of the grommets 202, 206 such that a space is left between the inner surface of the grommets 202, 206 and the outer surface of the current collector 209.

[0065] 3B , a cylindrical sleeve 232 can be positioned within the central aperture of the tablet 208, and a grommet 231 can be secured within the interior of the central sleeve 232 (e.g., via an adhesive or a friction fit). The grommet 232 can have enlarged end portions that extend radially outward beyond the outer cylindrical surface of the sleeve 232. The enlarged end portions can be configured to cover at least a portion of the separator sheet 203 (disc-shaped separator sheet 203) positioned at the opposite end of the tablet 208 to secure the separator sheet 203 onto the tablet 208. As shown, the tablet 208 has an exposed outer cylindrical surface that is disposed in electrical contact with the inner surface of the electrochemical cell can when the tablet 208 is placed within the electrochemical cell.

[0066] In some embodiments, separator sheets 203, 204 may be disposed on only one side of tablet 205. For example, for the bottom second electrode 205 of a stack of electrodes in cell 200, the tablet 208 for that bottom second electrode 205 may have separator sheets 203, 204 disposed only on the "top" side of cathode tablet 208 (the side interfacing with first electrode 207). In such a configuration, the underside of second electrode 205 may be in electrical contact with cell can 210, which acts as a current collector.

[0067] In some embodiments, the male and female grommets 202, 206 may be connected and the connection length may be varied to allow for a range of thicknesses of the electrodes 205, 207. In some embodiments, the tablet 208 may include a cathode material, as described above in this disclosure.

[0068] In some embodiments, separator sheets 203, 204 may be paper discs that act as electrical insulators and are ionically conductive. Separator sheets 203, 204 may be annular with a central hole. In some embodiments, separator sheet 203 adjacent to first electrode 207 may be of a different material than the other separator sheets 204. In some embodiments, separator sheets 203, 204 may be constructed of a variety of materials, including nonwoven paper having a composition of cellulose and PVA fibers, bi-ply paper with a higher density side, and / or cellophane.

[0069] In some embodiments, one or more of separator sheets 203, 204 may be disposed within anode gasket 201 to prevent anode active material from seeping between various components of cell 200 and creating a short circuit (e.g., upon contact with cathode active material or the cathode current collector).

[0070] In some embodiments, a sealant (eg, an adhesive) may be used to improve the containment of the anode between the separator sheets 203 , 204 and the anode gasket 201 .

[0071] In some embodiments, cell 200 may include a current collector gasket 212, which may be a gasket as previously disclosed and described with reference to at least FIG. 1 and the related description. In some embodiments, gasket 212 may be a plastic gasket with a safety vent feature. In some embodiments, current collector gasket 212 and anode gasket 201 fit snugly together to enclose first electrode 207 on top of the electrode stack. In some embodiments, cell 200 may also include an electrolyte shot dispensed into cell 200 and into the center of ring-shaped electrode tablets 207, 205 to saturate each separator sheet 203, 204 and fill any excess irregular space below current collector gasket 212.

[0072] FIG. 5 is a table illustrating components of different exemplary configurations of stacked electrode embodiments for an LR6 electrochemical cell. These are merely examples, and other tablet sizes, tablet counts, and / or the like may be utilized in certain embodiments. In some embodiments, as shown in FIG. 2A , the stack may have a second electrode 205 at the bottom of the stack and a first electrode 207 at the top of the stack. In some embodiments, there may be four second electrodes and four first electrodes disposed within cell 200 for a total of eight electrodes and seven separator interfaces between adjacent first electrodes 207 and second electrodes 205. The number of electrodes within a stack within cell 200 may be increased to improve the rate capability of cell 200, but this may have tradeoffs that affect performance in other areas. For example, increasing the number of electrodes within a cell requires a reduction in the height of each tablet. Changing the height of the electrodes may have a corresponding change in the height of the grommets and gaskets, as described herein. Increasing the number of electrode tablets has a corresponding increase in interfacial area between the anode and cathode in the cell, but increasing the number of electrode tablets requires an increase in the amount of separator material in the cell, which in turn reduces the cell volume that can be made available for active material. This can result in increased high-rate performance, but reduced low-rate performance (due to the reduced active material in the cell).

[0073] Still referring to FIG. 5, the second column shows control cells (e.g., cells with a bobbin-type configuration as in FIG. 1). The remaining columns provide details of exemplary cells with three, five, seven, and nine separator increments separating the first and second electrode tablets 207, 205. Here, the first electrode 207 contains the anode active material, and the second electrode 205 contains the cathode active material. The left column shows various properties of the electrochemical cells and their components (e.g., total electrode height, total wet paper thickness, interfacial surface area, etc.), and their associated rows show how those properties vary depending on the electrode and separator configuration within the cell. The bottom row shows the percentage of anode utilization during discharge for each configuration. Note that the anode utilization value is estimated based on a function of the number of electrodes in the stack. However, increasing the number of separator increments (and thereby increasing the interfacial surface area) is calculated to increase anode utilization up to 100% for nine separator increments, at least as shown in Figure 5. Increasing the number of separator increments is also calculated to decrease cathode capacity when compared to the baseline cell.

[0074] The table shown in FIG. 5 also describes other expected characteristics of various electrochemical cells having stacked tablet configurations. For example, increasing the number of separator tablets results in a corresponding decrease in the height of the electrodes 205, 207 that allow them to fit within the cell 200. In some embodiments, the electrodes may have the same height, while in other embodiments, the electrodes may have different heights within a single cell 200. In some embodiments, the electrodes may all have a central hole (e.g., to accommodate a current collector). Such a configuration facilitates manufacturing. In other embodiments, the bottom electrode (e.g., the cathode tablet) may not have a central hole therein. As another example, the total separator wet volume may increase as the total number of separator increments increases.

[0075] FIG. 6 shows another table summarizing the characteristics of a particular electrochemical cell equipped with an electrode table as described herein. Six exemplary cell designs (Ex. 1-6) are summarized and compared with a conventional bobbin cell design summarized as a control. In FIG. 6, Ex. 1 describes a cell design using seven cathode tablets, Ex. 2 describes a cell design using five cathode tablets, Ex. 3 describes a cell design using seven cathode tablets, Ex. 4 describes a cell design using seven cathode tablets, Ex. 5 describes a cell design using fourteen cathode tablets, and Ex. 6 describes a cell design using fourteen cathode tablets. Cells Ex. 1-4 each utilize an anode tablet with a "cup and lid" design as shown and described in FIG. 4C. Cells Ex. 5-6 each utilize an anode tablet with a "sleeve" design as shown and described in FIG. 4A-4B. Cell Ex. 5 includes zinc foil attached to zinc current collector nails, as described in detail in U.S. Patent Application No. 15 / 057,639, filed November 21, 2022, the contents of which are incorporated herein by reference in their entirety. Figure 6 demonstrates the volume of components within the electrochemical cell, as well as the maximum diffusion distance of the active material within the anode and cathode, and the interfacial area between the anode and cathode within each electrochemical cell. As shown, each of Cells Ex. 1-6 has an anode diffusion distance that is smaller than that of a conventional bobbin cell (values ​​shown in the table are provided as a percentage comparison with the conventional bobbin cell design). Cells Ex. 1 and Ex. 3-6 each have a cathode diffusion distance that is smaller than that of a conventional bobbin cell design. Additionally, each of Cells Ex. 1 and Ex. 3-6 has a higher interfacial surface area compared to the conventional bobbin cell design. Cell Ex. 2 has higher cathode and anode capacities compared to the conventional bobbin cell design.

[0076] Exemplary Methods for Making Alkaline Electrochemical Cells Having Stacked Electrodes 7 is a flow chart illustrating exemplary methods for fabricating an alkaline electrochemical cell having stacked electrodes. These exemplary methods are provided for fabricating an electrochemical cell 200 having stacked electrodes as described herein.

[0077] As shown in FIG. 7 , manufacturing method 300 may include step 302 of inserting a first cathode (including separator material, a cathode tablet, and male and female grommets) into an electrochemical cell. In some embodiments, the first cathode may be assembled before being inserted into the electrochemical cell. The cathode tablet may include cathode material that is pressed into the final shape of the cathode tablet. The separator material may be a paper disk placed on the opposite side of the cathode tablet. In some embodiments, the cathode tablet and separator may be annular and have a central hole. The male and female grommets may be inserted into the central hole of the annular cathode tablet and separator material. The male and female grommets, together with the separator, may seal the first cathode to prevent anode material from seeping through and contacting the cathode. When the first cathode is inserted into the electrochemical cell in step 302, the active material of the cathode tablet may contact the can, thereby causing the can to act as the cathode current collector. An additional step prior to inserting the cathode into the electrochemical cell may include applying a sealant to the separator material and / or grommet of the cathode to further seal the cathode.

[0078] Method 300 may also include step 304 of inserting an annular gasket into the electrochemical cell, the gasket configured to receive anode material within its open interior. In some embodiments, when the gasket is inserted into the electrochemical cell, the lower edge of the gasket may press against the top surface of the first cathode. This may sandwich the separator material between the gasket and the cathode tablet, which may prevent the anode material from leaking into the cathode (or vice versa). The gasket may frictionally engage the inner wall of the can and engage the cathode, which may press the cathode against the bottom of the can. In some embodiments, the upper edge of the gasket may support a second cathode, which may be inserted into the cell, as described below. When the second cathode is inserted into the cell, the separator material of the second cathode may be sandwiched between the cathode tablet and the gasket, again preventing any anode material from leaking into the cathode (or vice versa).

[0079] Method 300 may include step 306 of providing a second cathode (having a separator material) within the electrochemical cell. As with the first cathode, the second cathode may be assembled prior to insertion into the electrochemical cell in a manner similar to that in which the first cathode was assembled. Method 300 may include step 308 of inserting a second gasket into the electrochemical cell, the second gasket configured to receive the anode material. The insertion of the second gasket in step 308 may be substantially similar to the insertion of the first gasket in step 304. Steps 302, 304, 306, and 308 may be repeated as desired to insert additional cathodes and gaskets.

[0080] Method 300 includes step 310 of providing (e.g., extruding) an anode into the electrochemical cell through the central hole of the grommet. As described herein, because the central hole of the grommet is electrically insulated from the cathode material, the anode material can be extruded through the central hole of the cathode without risk of creating a short circuit. Method 300 may then include step 312 of inserting an anode current collector (e.g., a nail) into the electrochemical cell through the aligned central holes of the grommet. Inserting the anode current collector through the central hole of the cathode allows the anode current collector to make electrical contact with the anode material in each of the anode material layers in the stacked electrode cell. In some embodiments, method 300 may allow an electrolyte shot to be inserted into cell 200 while still allowing trapped air to escape from cell 200.

[0081] FIG. 8 is a flow chart illustrating a second exemplary method for manufacturing an electrochemical cell having stacked electrodes.

[0082] As shown in FIG. 8, cathode tablets and anode tablets are constructed before insertion into an electrochemical cell. Specifically, step 601 indicates that multiple cathode tablets are constructed, and step 602 indicates that multiple anode tablets are constructed. The cathode tablets are constructed by forming a cathode disk with a central through-hole. The cathode disk can be formed by pressing cathode material into the desired shape of the cathode disk. A separator sheet is placed on the opposite planar end of the cathode disk while maintaining the exposed cylindrical sidewall of the cathode disk. Next, an insulating material grommet (and / or sleeve), as shown in FIGS. 3A-3B, is inserted into the central through-hole to insulate the cathode material from the anode current collector nail, which will be inserted later through the central through-hole, and to secure the separator material onto the planar surface of the cathode tablet. As described above, the grommet (and / or sleeve) is secured to each other to secure the separator material onto the surface of the cathode material.

[0083] Referring to step 602, as shown in Figures 4A-4C, an anode tablet is constructed by placing the anode material inside a sealed anode tablet. In embodiments where the anode material is a flowable material (e.g., a gel), the anode material may be extruded or otherwise provided into an anode sleeve 221 having a sealed end (e.g., a separator material sealed onto one end of the sleeve 221). Once the anode material is provided within the sleeve 221, the open end of the sleeve may be sealed by securing a separator onto the open end of the sleeve to create a completely sealed anode tablet.

[0084] Referring again to FIG. 8, the electrochemical cell is constructed by stacking the cathode and anode tablets inside the electrochemical cell. The cathode tablet is inserted into the electrochemical cell first, as shown in step 603, followed by the anode tablet, as shown in step 604. Steps 603-604 are repeated until the desired number of cathode and anode tablets have been inserted into the electrochemical cell. While FIG. 8 shows the cathode tablet being inserted into the electrochemical cell first, it should be understood that in other embodiments, the anode tablet may be inserted first.

[0085] Once the desired number of assembled cathode and anode tablets are inserted into the electrochemical cell, an anode current collector nail is inserted through the center of the electrode, as shown in step 605. The current collector nail extends through a central through-hole in the cathode tablet, in the cathode tablet's grommet and / or sleeve, to electrically insulate the current collector nail from the cathode active material. The current collector nail pierces the sealed anode tablet by extending through the separator sheets on both sides of the anode tablet. The current collector nail extends from the top of the electrochemical cell and into at least the first anode tablet inserted in the cell (the lowest anode tablet in the electrochemical cell). For those electrochemical cells having a cathode tablet on the lower inner surface of the electrochemical cell, the cathode tablet may not extend into the insulated central opening of the lowest cathode tablet. In such embodiments, the distal end of the anode current collector nail is positioned within the lowest anode tablet in the electrochemical cell. The open top end of the electrochemical cell is then sealed with a closure assembly that includes a gasket and a negative terminal in electrical connection with the anode current collector.

[0086] While the embodiments have been illustrated and described in detail above, such illustration and description should be considered illustrative or exemplary, and not limiting. It will be understood that changes and modifications may be made by those skilled in the art within the scope and spirit of the appended claims. The embodiments include any combination of features from different embodiments described above and below.

[0087] The embodiments are further described through the following illustrative, non-limiting examples that provide a deeper understanding of the embodiments and their many advantages. The following examples are included to demonstrate preferred embodiments. Those skilled in the art will understand that the techniques disclosed in the following examples are representative of techniques used in the embodiments to function well in practicing the embodiments, and therefore can be considered to constitute preferred modes for their implementation. However, those skilled in the art will, in light of the present disclosure, understand that many changes can be made in the specific embodiments disclosed and still obtain a like or similar result without departing from the spirit and scope of the embodiments.

[0088] Many modifications and other embodiments of the disclosure described herein will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the disclosure is not to be limited to the particular embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. An electrochemical cell comprising: a container having a closed bottom end and an open top end; a closure assembly secured to the open top end of the container to close the open top end; a stack including two or more tablet-shaped electrodes disposed within the container, the two or more tablet-shaped electrodes including one or more sets of first electrodes and one or more sets of second electrodes; a stack, wherein the one or more first electrodes and the one or more second electrodes alternate within the stack; a separator set including one or more separators disposed between each electrode in the stack; an electrolyte solution disposed within the container; a current collector disposed within the container; An electrochemical cell comprising:

2. 10. The electrochemical cell of claim 1, wherein the one or more separators include at least one first separator and at least one second separator, the at least one first separator having a different composition than the at least one second separator.

3. 10. The electrochemical cell of claim 1, wherein the one or more first electrodes are anodes comprising a zinc material.

4. 4. The electrochemical cell of claim 3, wherein the one or more second electrodes is a cathode comprising a manganese dioxide material.

5. 5. The electrochemical cell of claim 4, further comprising a second electrode positioned on the bottom end of the stack adjacent the closed bottom end of the container.

6. 6. The electrochemical cell of claim 5, further comprising a second electrode positioned on the top end of the stack adjacent the open top end of the container.

7. each of the one or more second electrodes defining a central opening extending therethrough, and each of the one or more second electrodes further including an insulating sleeve lining the central opening; 10. The electrochemical cell of claim 1, wherein the current collector is a current collector nail that extends through the center of the insulating sleeve.

8. 8. The electrochemical cell of claim 7, wherein at least one of the one or more separators is secured to each of the one or more first electrodes, and the current collector nail extends through a center of the at least one separator secured to each of the one or more first electrodes and makes electrical connection with an active material of the one or more first electrodes.

9. 10. The electrochemical cell of claim 8, wherein each of the one or more first electrodes includes a gasket that electrically insulates the active material of the one or more first electrodes from the container, and wherein the at least one of the one or more separators is secured to the gasket.

10. each of the one or more second electrodes includes at least one separator; 8. The electrochemical cell of claim 7, wherein the insulating sleeve of each of the one or more second electrodes includes one or more grommets that secure the at least one separator of each second electrode.

11. an anode, an anode active material composition; an insulating gasket having an open end, said insulating gasket surrounding said anode active material; an ion-permeable separator disk secured over each of the open ends of the insulating gasket to seal the anode active material within the insulating gasket; an anode comprising:

12. the anode active material is Particulate zinc suspended in an electrolyte gel; particulate zinc oxide, and Dissolved zinc oxide, 12. The anode of claim 11, comprising:

13. The anode of claim 11 , wherein the insulating gasket comprises a polymeric material.

14. The insulating gasket is a cylindrical sleeve having a first open end and an opposite second open end; a first grommet secured over the first open end, a first separator secured over the first grommet; and a second grommet secured onto the second open end, a second separator secured onto the second grommet; 12. The anode of claim 11, comprising:

15. 15. The anode of claim 14, wherein the first separator is adhered over the first grommet and the second separator is adhered over the second grommet.

16. a cathode, a cathode active material composition formed in an annular shape defining a central opening extending therethrough; and a first ion-permeable separator sheet on a first side of the cathode active material composition; a second ion-permeable separator sheet on a second side of the cathode active material composition; and an insulating sleeve positioned within the central opening, a first end of the insulating sleeve extending beyond the first ion permeable separator sheet to secure the first ion permeable separator sheet to the first side of the cathode active material composition; an insulating sleeve, a second end of the insulating sleeve extending beyond the second ion permeable separator sheet to secure the second ion permeable separator sheet to the second side of the cathode active material composition; and a cathode.

17. 17. The cathode of claim 16, wherein the first ion-permeable separator sheet and the second ion-permeable separator sheet are planar, and a sidewall of the cathode active material composition extending between the first side and the second side is exposed.

18. 17. The cathode of claim 16, wherein the insulating sleeve includes a first grommet within the cylindrical open center of the cathode active material composition and a second grommet secured to the first grommet.

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