Coin battery with thin aversive agent coating

Abstract

An electrochemical cell is provided having at least a portion of the outer surface thereof coated with a thin layer of an aversive coating to prevent children from swallowing the electrochemical cell. Compositions and methods for applying a thin layer of an aversive coating to an electrochemical cell having sufficiently low resistance to allow current to pass through the aversive coating are described.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority benefit of U.S. Non-Provisional Application No. 18 / 593,533, filed March 1, 2024, which claims priority benefit of U.S. Provisional Application No. 63 / 508,745, filed June 16, 2023; U.S. Non-Provisional Application No. 18 / 593,391, filed March 1, 2024, which claims priority benefit of U.S. Provisional Application No. 63 / 508,777, filed June 16, 2023; and U.S. Non-Provisional Application No. 18 / 593,527, filed March 1, 2024, which claims priority benefit of U.S. Provisional Application No. 63 / 508,764, filed June 16, 2023, which are incorporated herein by reference in their entirety.

[0003] This application also incorporates by reference U.S. Non-Provisional Application No. 18 / 593,561, filed March 1, 2024, which claims priority benefit of U.S. Provisional Application No. 63 / 586,879, filed September 29, 2023. TECHNICAL FIELD

[0004] The present disclosure relates generally to coin or button-type electrochemical cells. BACKGROUND

[0005] Coin cell units or coin cells, such as those described in International Patent Publication No. PCT / US2013 / 021430, filed January 14, 2013, the contents of which are incorporated herein by reference in their entirety, are small, disc-shaped batteries commonly used in a wide range of electronic devices, such as hearing aids, cochlear implant processors, calculators, remote controls, and wristwatches. These cell units and batteries are often referred to as button batteries due to their shape and size.

[0006] Ingestion of coin cell batteries by children can cause severe injury and even death, in part due to the generation of hydroxide (high pH) on the negative side from electrolytic reactions that occur when the battery comes into contact with body fluids such as interstitial fluid, mucus, esophageal lining fluid, gastric fluid, and the like, as a result of the current from the battery. The formed hydroxide causes alkaline burns and esophageal perforation. Severe injury can occur in as little as two hours.

[0007] To address this problem, many manufacturers have adopted anti- swallow features. For example, anti-swallow features are raised borders around the perimeter of the battery. The raised borders make it difficult for children to swallow the battery. Other anti-swallow features include bittering coatings on the surface of the battery that discourage children from putting the battery in their mouths. However, if swallowed, a coin or button cell battery coated with a bitterant or having a raised perimeter can still cause electrolytic reactions in the esophagus or stomach and cause serious injury. Thus, it can be helpful to provide a signal to parents or other caregivers that a battery can have been ingested. Such a signal can be achieved by using a colorant to stain the mouth, hands, or other areas that have been wetted by bodily fluids such as saliva that have come into contact with a lithium coin battery. SUMMARY

[0008] Various embodiments provide electrochemical cells having an aversive coating covering at least a portion of the exterior to discourage children from ingesting the electrochemical cell. The aversive coating includes 0.2 wt% to 10 wt% of an aversive taste agent and 45 wt% to 99.8 wt% of a water-soluble polymer. The thickness of the aversive coating provides a low enough electrical resistance (e.g., less than 68,000 Ω) to allow current generated by the electrochemical cell to pass through the aversive coating. The aversive agent composition includes at least one aversive taste agent and optionally a colorant. In some embodiments, the aversive taste agent is denatonium benzoate (DNB), capsaicin, allyl isothiocyanate, or piperine.

[0009] In some embodiments, the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide, or polyethylene glycol (PEG). In some embodiments, the water-soluble polymer is PVA. In some embodiments, the PVA has a molecular weight of about 10,000 to about 150,000. In some embodiments, the PVA is about 80% to about 95% hydrolyzed. In some embodiments, the PVA has a molecular weight of about 75,000 and is about 88% hydrolyzed.

[0010] In some embodiments, the aversive coating further includes 0.1 wt% to 5.0 wt% of an adhesion promoter. In some embodiments, the adhesion promoter is Lubrizol 2063. In some embodiments, the aversive coating further includes 0.01 wt% to 50 wt% of a surfactant. In some embodiments, the surfactant is sodium dodecyl sulfate (SDS).

[0011] In some embodiments, the dry weight composition of the aversive coating comprises about 3.0 wt% to about 9.0 wt% DNB and about 47 wt% to about 97 wt% PVA. In some embodiments, the dry weight composition of the aversive coating comprises about 3.0 wt% to about 9.0 wt% DNB, about 47 wt% to about 93 wt% PVA, and about 4.0 wt% to about 48 wt% SDS.

[0012] In some embodiments, the electrochemical cell is a coin cell or a button cell. In some embodiments, greater than 50 area % of the outer surface of the positive terminal and / or the negative terminal is coated with the aversive coating. In some embodiments, the total dry weight of the aversive coating applied to the electrochemical cell is about 0.1 mg to about 0.5 mg. In some embodiments, the thickness of the aversive coating is less than 1 pm. In some embodiments, the total amount of aversive taste agent is about 10 pg to about 30 pg. In some embodiments, the electrochemical cell is packaged in a child-resistant package.

[0013] Various embodiments provide methods of manufacturing an electrochemical cell coated with the aversive coating. The methods include preparing a coating solution comprising about 0.001 wt% to 0.1 wt% of an aversive taste agent and about 0.01 wt% to about 1.0 wt% of a water-soluble polymer dissolved in one or more solvents, applying the coating solution to greater than 50% of the area of the positive terminal or the negative terminal of the electrochemical cell to provide a thickness that is sufficiently low to allow passage of current generated by the electrochemical cell through the aversive coating; and drying the solution onto the exterior of the electrochemical cell.

[0014] In some embodiments, the coating solution is prepared by dissolving 0.001 wt% to 0.1 wt% of an aversive taste agent in one or more solvents. In some embodiments, the coating solution further comprises 0.001 wt% to 0.1 wt% of an adhesion promoter.

[0015] In some embodiments, the coating solution is prepared by heating PVA in water to about 95 °C for about 60 minutes to dissolve prior to adding a solution comprising dissolved Lubrizol 2063. In some embodiments, the solution comprising dissolved PVA is cooled prior to adding the aversive agent composition.

[0016] In some embodiments, the coating solution is prepared by dissolving 0.001 wt% to 0.2 wt% of a surfactant in the coating solution.

[0017] In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA and about 0.01 wt% DNB in one or more solvents. In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA, about 0.01 wt% DNB, and about 0.001 wt% to about 0.1 wt% Lubrizol 2063 in one or more solvents. In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA, about 0.01 wt% DNB, and about 0.01 wt% to about 0.1 wt% SDS in one or more solvents.

[0018] In some embodiments, the coating solution is applied to greater than 60%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of the area of the positive and / or negative terminal.

[0019] In some embodiments, the method of manufacturing an electrochemical cell further comprises cleaning an outer surface of the electrochemical cell prior to applying the coating solution. BRIEF DESCRIPTION OF DRAWINGS

[0020] Reference will now be made to the drawings, which do not necessarily show to scale, as the dimensions of the various features can have been exaggerated for illustrative purposes. The appended drawings, figures, graphs, images, and the like illustrate various exemplary, non-limiting, inventive aspects, embodiments, and features (‘examples’ or ‘instances’) according to the present disclosure: Figure 1 is a schematic of a coin cell according to one embodiment, immersed in a saliva solution.

[0021] Figure 2 is a perspective and cross-sectional view of an electrochemical coin cell according to one embodiment.

[0022] Figure 3 is a two-dimensional cross-sectional view of an electrochemical coin cell as shown in Figure 2

[0023] Figure 4 is a schematic of a method of manufacturing an electrochemical cell coated with an aversive coating.

[0024] Figure 5 shows an electrochemical cell with a thin layer of aversive coating applied to the negative terminal.

[0025] Figure 6 is a perspective and cross-sectional view of an electrochemical coin cell according to one embodiment, with a thin layer of aversive coating applied to the negative terminal.

[0026] Figure 7 ​An exemplary child-resistant package 600 is shown in accordance with one embodiment. DETAILED DESCRIPTION

[0027] Coin cells, also known as button cells, are small monobloc batteries that are commonly used to power low-power devices such as watches, calculators, hearing aids, and small electronic devices. These batteries are small and compact so that they are easy to use and store, and can be provided in a variety of sizes, chemistries, and rated voltages.

[0028] Coin cells were originally developed for use in hearing aids, and are now used in a variety of other applications and devices such as watches, calculators, and other small electronic devices. Coin cells are typically composed of a positive electrode (cathode), a negative electrode (anode), and an electrolyte that allows ions to flow between the electrodes. The electrodes and electrolyte are encapsulated in a small, circular metal casing that is typically made of stainless steel or nickel-plated brass.

[0029] The positive electrode is typically made of a metal oxide such as silver oxide or manganese dioxide, and is coated onto a metal grid or foil. The negative electrode is typically made of a metal such as zinc or lithium, and is also coated onto a metal grid or foil. The electrolyte is typically a liquid or gel, and is designed to allow ions to flow between the electrodes.

[0030] The electrodes and electrolyte are arranged in a specific configuration within the metal casing depending on the battery chemistry and rated voltage. For example, in a manganese dioxide-based battery, the positive electrode is placed in the center of the battery, while the negative electrode is placed around the outside of the positive electrode. This arrangement allows the battery to provide a high current output while maintaining a small size.

[0031] The external components include a casing or housing that defines an internal volume in which the anode and cathode are housed, held physically apart by a separator such as an ion-permeable separator, an electrolyte-permeable separator, etc. The anode and cathode have different active materials such as zinc and manganese dioxide, respectively. These materials are selected based on their electrochemical properties to enable them to facilitate the flow of electrons from one terminal to the other. The electrolyte is a liquid or gel substance that allows ions to move between the anode and cathode. The electrolyte is typically a combination of a salt such as potassium hydroxide and water.

[0032] Coin cells can be provided in a variety of chemistries, each with its own unique performance characteristics. For example, alkaline coin cells are the most common type of button cell and are commonly used in low-power devices such as watches, calculators, and small electronic devices. These batteries use an alkaline electrolyte and a zinc-based negative electrode and can be provided in a variety of sizes and rated voltages. Silver oxide coin cells are commonly used in high-power devices such as camcorders, calculators, and medical devices. These batteries use a silver oxide positive electrode and a zinc-based negative electrode and are designed to provide high voltage output and long life. Zinc-air coin cells are commonly used in hearing aids and use a zinc-based negative electrode and air as the positive electrode. However, these battery chemistries often have drawbacks such as outgassing risk, explosion risk, fire risk, battery life shortening, inconsistent discharge, discharge temperature variation issues, etc. Lithium is a popular alternative to other conventional battery chemistries, especially for low-power devices such as watches, calculators, and small electronic devices that use coin cells. These batteries typically use a manganese dioxide-based positive electrode and a lithium-based negative electrode.

[0033] The primary electrochemical reaction that occurs after ingestion of a coin cell battery is the electrolysis of water due to the presence of the following factors: (a) the coin cell battery itself provides a direct current voltage, 3V OCV (open circuit voltage); (b) the ionically conductive medium (saliva) connects the anode (+) and cathode (-) terminals; and (c) the two terminals and the saliva conductive path complete a closed loop for the electrolytic cell. If the voltage supply of the electrolytic cell is high enough to overcome the polarization and the 1.23V thermodynamic voltage window for water electrolysis, an electrochemical reaction will occur. In fact, the electrolytic reaction associated with ingestion of a lithium battery can be more severe than the electrolysis associated with ingestion of an alkaline battery. This is because the driving force (voltage difference between the battery voltage and the theoretical water electrolysis voltage of 1.23V) is much higher in the case of a 3V lithium battery (3.0V - 1.23V = 1.77V in the case of a lithium battery, and 1.5V - 1.23V = 0.27V in the case of an alkaline battery).

[0034] It is worth noting that the nomenclature of the electrolytic cell is opposite to that used for batteries. Thus, the terms "anode" and "electrolytic anode" refer to the electrode where oxidation occurs, and the terms "cathode" and "electrolytic cathode" refer to the electrode where reduction occurs. When an electrolytic cell such as a coin cell is assembled and the active electrochemical components are sealed within the battery, the negative terminal will be in electrical communication with the anode or electrolytic anode, and the positive terminal will be in electrical communication with the cathode or electrolytic cathode. It should also be noted that electrolysis requires the application of a voltage, thus providing a direct contrast to corrosion, which typically occurs naturally under ambient conditions.

[0035] Figure 1To help illustrate the electrolytic reactions in question, a simulated Li-Mn02electrochemical coin cell 6 is immersed in a saliva solution 5. The primary reactions that occur when a battery with these same components is ingested and lodged in a person's esophagus are shown, although the battery electrodes are shown as discrete components. Specifically, the battery 6 operates at approximately 3V DC and includes a coin cell cup (e.g., positive container) 12, a coin cell can (e.g., negative container) 20, an anode 40, and a cathode 50. The anode 40 and the cathode 50 contain materials that are specifically selected based on their compatibility with the intended electrochemical reactions; for example, x Li + Mn02→ Li-Mn02, where Mn is reduced as lithium ions enter the lattice.

[0036] The outer surface of the coin cell cup 12 acts as the negative terminal (cathode in the electrolytic cell), and the outer surface of the coin cell can 20 acts as the positive terminal (anode in the electrolytic cell). The hydrogen evolution reaction occurs on the coin cell cup 12 by accepting electrons from the battery anode 40, which in this case includes lithium. At the coin cell can 20 (anode in the electrolytic cell), a variety of reactions such as metal dissolution, oxygen evolution, and possible chloride oxidation occur and compete with each other. Charge neutrality in the saliva solution 5 is maintained by the movement of anions 8 from the coin cell cup 12 (negative terminal) to the coin cell can 20 (positive terminal) and the opposite direction movement of cations 7. As the metal from the coin cell can 20 oxidizes, it loses electrons to the battery cathode 50, which in this case is manganese dioxide. Ultimately, the end products at the coin cell can 20 depend on its potential, and the solution pH is a result of the combined anodic and cathodic reactions. Furthermore, the solution pH reflects the real-time products generated in the reaction zone between the esophagus and the coin cell; thus, the solution pH is localized and does not necessarily reflect the pH of the bulk solution (i.e., the rest of the saliva not in close proximity to the reaction zone).

[0037] When a 3V lithium coin cell is immersed in a neutral or alkaline saliva solution, the possible electrochemical reactions on the coin cell cup 12 (negative terminal) are shown below. Note that saliva is typically neutral.

[0038] (1) 2H2O + 2e - H2↑ + 2OH - E0 = -0.83V

[0039] (2) O2 + 2H2O + 4e - 4OH - E0 = -0.4V

[0040] Typically, reaction (1) dominates because of the limited solubility of oxygen in water, such that the oxygen concentration in saliva is too low. Either way, the production of hydroxyl ions (i.e., OH - ) raises the pH of the saliva, possibly to a level that can cause alkaline burns of the esophagus.

[0041] Saliva can sometimes be acidic. In this case, the reactions at the coin cell cup 12 are as follows: (1a) 2H + + 2e - H2↑ E0 = - 0.0V (2a) O2 + 4H + + 4e - 2H2O E0 = 1.23 V In either case, the choice of material used at the negative terminal, which has a high hydrogen evolution overpotential, will shift the dominant reactions from (1) and (2) to (1a) and (2a). This has the beneficial effect of reducing or eliminating the formation of hydroxyl radicals, which can cause localized alkaline burns of the esophageal tissue.

[0042] When a 3V lithium coin cell is immersed in a solution of saliva 5 and the coin cell cup 20 contains nickel at least partially along its surface, the possible electrochemical reactions at the coin cell cup 20 (positive terminal) are as follows.

[0043] (3) 4OH - - 4e - O2↑ + 2H2O

[0044] (4) Ni - 2e - + 2OH - Ni(OH)2

[0045] Reaction (4) typically dominates, such that the metal component in the coin cell cup 20 tends to oxidize. In fact, lithium electrochemical coin cell cups are typically nickel plated, as exemplified by the oxidation of nickel in reaction (4). If the coin cell cup 20 is constructed of other metals, such as stainless steel, the iron in these alloys can oxidize in similar reactions. Once the metal surface of the coin cell cup 20 has passivated (i.e., by forming a dense oxide film on the bare metal surface), the oxygen evolution reaction (3) can dominate if the voltage is high enough.

[0046] Furthermore, as shown in (3a) and (4a) below, dissolution of the metal can 20 can also be a possible result if the iron-based metal (typically some type of steel) is exposed, especially to the extent that hydroxides are present (e.g., through the above-mentioned competing reactions) and / or in an acidic environment (e.g., through saliva).

[0047] (3a) Fe - 2e - Fe 2+ (in an acidic medium)

[0048] (4a) Fe - 2e - + 2OH - Fe(OH)2 (in a basic medium)

[0049] Any combination of the cathodic processes in reactions (1) to (2a) and the anodic processes in reactions (3) to (4a) can complete Figure 1 the electrolysis cell 6 depicted in FIG. 1. For example, a combination of (1) and (3) results in the following electrolysis reaction in water (i.e., water splitting): (5) 2H2O H2↑ + O2↑ Ε0 = - 1.23 V Note that the electrolysis reaction (5) has a thermodynamic potential of 1.23 V, and the negative sign of ΔΕ0 indicates that this reaction is not spontaneous. Therefore, a DC power source of at least 1.23 V is required to initiate and sustain reaction (5), and as shown in FIG. 1, the coin cell 6 supplies 3 V DC. Figure 1

[0050] Furthermore, if the amount of sodium chloride (NaCl) in the saliva is relatively high, the following electrolysis reaction can occur instead of (5) (discussed previously): (6) 2NaCl + 2H2O Cl2↑ + H2↑ + 2NaOH In reaction (6), one of the products is sodium hydroxide (NaOH), which is another factor that contributes to a high solution pH and a potentially caustic solution that can be able to burn human tissue.

[0051] In summary, Figure 1 ​The depicted conventional electrochemical coin cell 6 and the reactions (1) through (6) associated with its immersion in saliva 5 demonstrate the formation of hydroxide ions from some sort of electrolysis. Thus, the burns and damage caused when a coin cell becomes lodged in the esophagus accidentally can be caused by the high saliva pH formed during these reactions, but these reactions and the corresponding effects on pH can be highly localized and difficult to detect if the pH is not measured in the vicinity of the components involved. In other words, due to mass transport limitations in the esophagus, a person with a lodged coin cell can experience different pH values in the tissue that interacts with the coin cell can 20 (positive terminal) and the tissue that interacts with the coin cell cup 12 (negative terminal), with the solution with the higher pH facing the negative terminal (i.e., the coin cell cup 12) due to the diffusion limitations of the liquid within the esophagus. Figure 1

[0052] In certain aspects and basic concepts of the various embodiments of the present disclosure relate to the case of saliva and / or a saliva-based aqueous solution, saliva can be represented as consisting of: 0.4 g KCl; 0.4 g NaCl; 0.906 g CaCl2; 0.560 g Na3PO4 - 12H2O; 2 ml 10% H3PO4; 0.0016 g Na2S; 1 g urea; and the balance deionized water to make 1 liter of solution. Although this formulation is intended to mimic human saliva in a standardized manner, small variations and / or actual human saliva can be used as a substitute, although in this case the deviation from the representative formulation will be noted appropriately.

[0053] Figure 2 Figure 3 One arrangement of an electrochemical coin cell 10 that is well suited for aspects and embodiments of the present disclosure is depicted, although coin cell 10 can employ various alternative component orientations and arrangements. Moreover, the specific devices and processes illustrated in the drawings and described herein are exemplary embodiments of the claimed inventive concepts defined in the appended claims. Thus, the precise dimensions and physical characteristics related to the embodiments disclosed herein should not be considered limiting, except insofar as such dimensions or characteristics are intrinsic to producing the desired reactions.

[0054] As Figure 2 3 ​​​As shown in the figure, the electrochemical coin cell 10 also includes a cathode terminal 20 (i.e., a cell can) that includes a closed end 21, an open end 22 having a terminal edge 23, and a sidewall 24 extending between the closed end 21 and the open end 22. The cathode terminal 20 serves as the positive electrode of the coin cell. Further, the cathode terminal 20 is comprised of a metallic material, such as titanium, a titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, or another electronic conductor. The closed end 21 can also have a composition comprised of titanium metal, a titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, or another electronic conductor.

[0055] The coin cell 10 further includes a gasket 30 that provides a seal between the anode terminal 12 and the cathode terminal 20 Figure 2 and 3 The gasket 30 is typically made of an electrically non-conductive elastomeric material capable of providing a compression seal between the anode terminal 12 and the cathode terminal 20. The material for the gasket 30 must also be selected with reference to its stability in the presence of electrolyte, its resilience, and its resistance to cold flow. Suitable materials for the gasket 30 include the following: nylon, polytetrafluoroethylene, fluorinated ethylene-propylene, chlorotrifluoroethylene, perfluoroalkoxy polymer, polyethylenes, polyethylene, polypropylene, polystyrene, polysulfone, and the like.

[0056] The electrochemical coin cell 10 also includes an electrolyte 34. As understood by one of ordinary skill in the art, a variety of materials can be used for the electrolyte 34. For example, the electrolyte 34 can be comprised of a composition of at least one lithium salt dissolved in an organic solvent or organic solvent blend. Suitable salts for lithium coin cells are lithium triflate, lithium triflimide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, or a combination thereof. Common organic solvents for lithium coin cells are propylene carbonate and 1,2-dimethoxyethane.

[0057] The electrochemical cell 10 also has an anode 40 disposed in electrical connection with the anode terminal 12. As understood by one of ordinary skill in the art, the anode 40 can be comprised of a variety of alkali metals and alloys thereof with aluminum or magnesium, so long as the composition is suitable for acting as an anode in an electrochemical cell. In one embodiment, the anode 40 is primarily comprised of a lithium material suitable for acting as an anode in an electrochemical cell having a cathode primarily comprised of manganese dioxide.

[0058] The electrochemical cell 10 also includes a cathode 50 arranged in electrical connection with the cathode terminal 20. As also understood by one of ordinary skill in the art, the cathode 50 can be comprised of a variety of materials suitable for use as a cathode in a lithium-based electrochemical cell. In one embodiment, the cathode 50 is primarily comprised of manganese dioxide.

[0059] The electrochemical coin cell 10 further includes a separator 38 disposed between the anode 40 and the cathode 50 to provide insulation therebetween. The separator 38 can be comprised of any of a variety of polymeric materials that provide electrical insulation between the anode terminal 12 and the cathode terminal 20, for example. For example, the separator 38 can be formed of a polypropylene or polyethylene nonwoven film having a thickness between about 20 μιη and about 60 μιη.

[0060] As also shown in Figure 2 and 3 The electrochemical cell 10 can be configured as a button cell or coin cell configuration having an overall cell outer diameter 54 and an overall cell height 58, as shown. The overall cell outer diameter 54 can have a dimension between about 5 mm and about 25 mm, and the overall cell height 58 can have a dimension between about 0.5 mm and about 10 mm. It is generally understood that button cells or coin cells having these dimensions are most likely to become lodged in the esophagus following accidental ingestion. For example, the electrochemical cell 10 can be manufactured in a CR2016 configuration as defined by the International Electrotechnical Commission (TEC), wherein the overall cell outer diameter 54 has a diameter of about 20 mm, and the overall cell height 58 has a thickness of about 1.6 mm.

[0061] Another aspect of the disclosed methods relates to methods of constructing and / or manufacturing coin cells having the features described herein. The methods include providing a negative electrode active material comprising lithium, and disposing the material in separate halves of an electrically conductive container, and providing a non-aqueous organic liquid electrolyte prior to hermetically sealing the halves of the electrically conductive container to form the cell.

[0062] Another aspect of the disclosed methods is a method of providing and / or manufacturing a battery to avoid injury associated with ingestion of the battery, and to avoid injury caused by ingestion of the battery. In these aspects, any of the above-described battery designs and constructions can be provided. At its core, the methods of the present invention relate to manufacturing batteries and providing the batteries for sale and / or consumer use.

[0063] As used throughout this specification, duplex stainless steel is any duplex steel that exhibits both ferrite and austenite crystal structures. Any reference to a particular grade should be considered a reference to the standard published by ASTM International, unless the context indicates some other reference known to one of ordinary skill in the metallurgical arts.

[0064] Repellent coating

[0065] Aspects of the present disclosure relate to aversive coatings for electrochemical cells. An aversive coating is formed by applying a solution comprising an aversive taste agent and a binder, such as a water-soluble polymer, to a surface, such as a surface of a battery, and allowing the solution to dry. The aversive coating comprises at least one aversive agent, which can be an aversive taste agent, such as a bitter agent, an aversive odor agent, or a salivating agent. An "aversive taste agent" refers to a substance that is bitter, sour, pungent, peppery, or otherwise undesirable in flavor to discourage ingestion of the battery by a child. An "aversive odor agent" is an odoriferous substance that has an undesirable odor, such as ammonia or sulfur. A "salivating agent" refers to a substance that induces saliva production when in contact with the oral cavity. The aversive agent composition can also comprise a colorant to warn parents that a child has attempted to ingest a battery.

[0066] The aversive coating has a thin layer (< 1 pm) of a composition that allows the aversive coating to be applied to an electrochemical cell.

[0067] In some embodiments, the dry weight composition of the aversive coating comprises 0.2 wt% to 10 wt% of the aversive taste agent and 45 wt% to 99.8 wt% of the water-soluble polymer. In some embodiments, the aversive coating comprises one or more additives that balance the dry weight composition.

[0068] The aversive coating comprises at least one aversive taste agent (e.g., a bitter agent). In some embodiments, the aversive taste agent is selected from the group consisting of denatonium benzoate (DNB), capsaicin, allyl isothiocyanate, or piperine. In some embodiments, the aversive taste agent is DNB. In some embodiments, the dry weight composition of the aversive coating comprises 0.2 wt% to 10 wt% of the aversive taste agent. In some embodiments, the dry weight composition of the aversive coating comprises about 3.0 wt% to about 9.0 wt% DNB.

[0069] The water-soluble polymer contained in the aversive coating acts as a binder to adhere the aversive agent composition to the electrochemical cell. In some embodiments, the dry weight composition of the aversive coating comprises 45 wt% to 99.8 wt%, 50 wt% to 95 wt%, 60 wt% to 95 wt%, 70 wt% to 95 wt%, 75 wt% to 95 wt%, 80 wt% to 95 wt%, 85 wt% to 95 wt%, or 90 wt% to about 95 wt% of the water-soluble polymer. In some embodiments, the dry weight composition of the aversive coating comprises about 45.9 wt% of the water-soluble polymer.

[0070] In some embodiments, the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide, or polyethylene glycol (PEG). In some embodiments, the water-soluble polymer is PVA. In some embodiments, the water-soluble polymer has a molecular weight of about 10,000 to about 150,000, about 10,000 to about 100,000, about 50,000 to about 100,000, about 60,000 to about 90,000, about 70,000 to about 80,000, or about 75,000. In some embodiments, the PVA has a molecular weight of about 50,000 to about 100,000. In some embodiments, the PVA has a molecular weight of about 10,000 to about 150,000, about 10,000 to about 100,000, about 50,000 to about 100,000, about 60,000 to about 100,000, about 60,000 to about 90,000, about 70,000 to about 100,000, about 70,000 to about 90,000, or about 70,000 to about 80,000. In some embodiments, the PVA has a molecular weight of about 75,000. All molecular weights are described as average mass in grams per mole.

[0071] Polyvinyl alcohol is prepared from polyvinyl acetate by hydrolyzing the ester functional groups to hydroxyl functional groups. The degree of hydrolysis of polyvinyl alcohol can vary. For 80% hydrolyzed PVA, about 80% of the monomer units contain a hydroxyl group and about 20% of the monomer units contain acetate. In some embodiments, the PVA is about 70% to 100% hydrolyzed, about 70% to about 99% hydrolyzed, about 80% to about 99% hydrolyzed, about 85% to about 95% hydrolyzed, about 80% to about 90% hydrolyzed, or about 85% to about 90% hydrolyzed. In some embodiments, the PVA is about 80% to about 95% hydrolyzed. In some embodiments, the PVA is about 88% hydrolyzed. In some embodiments, the PVA has a molecular weight of about 75,000 and is about 88% hydrolyzed.

[0072] In some embodiments, the one or more additives of the aversive coating comprise an adhesion promoter. The addition of an adhesion promoter can help the aversive coating better adhere to the surface of the electrochemical cell. In some embodiments, the dry weight composition of the aversive coating comprises 0.1 wt% to about 5.0 wt% of an adhesion promoter. In some embodiments, the adhesion promoter is Lubrizol 2063, Lubrizol 2062, DowSil Z-6137, DowSil 3-6121, PP-6 (PP water from Marabin Environmental Conservation Printing Ink Co. Ltd), BYK-4509, or BYK-4510. In some embodiments, the adhesion promoter is Lubrizol 2063, a hydroxyl and carboxyl functionalized phosphate ester.

[0073] In some embodiments, the one or more additives of the aversive coating comprise a surfactant. Surfactants lower the surface tension of a solution and can act as wetting agents and dispersants to aid in the application of the aversive coating to the electrochemical cell. In some embodiments, the dry weight composition of the aversive coating comprises 0.01 wt% to about 50 wt% of a surfactant. In some embodiments, the surfactant is an alkyl sulfate, an alkyl ether sulfate, an alkyl benzene sulfonate, a polyoxyethylene ether, a phosphate ester, or a carboxylate. In some embodiments, the surfactant is sodium dodecyl sulfate (SDS), sodium lauryl ether sulfate (SLES), sodium stearate, Triton X-100, polysorbate 20 (Tween® 20), or dioctyl sodium sulfosuccinate (DOSS). In some embodiments, the surfactant is sodium dodecyl sulfate (SDS).

[0074] In some embodiments, the one or more additives of the aversive coating comprise a viscosity modifier to aid in dispensing the solution comprising the aversive coating. In some embodiments, the dry weight composition of the aversive coating comprises 0.01% to about 2.0% by weight of a viscosity modifier. In some embodiments, the viscosity modifier is a carbomer, a high molecular weight synthetic polymer of acrylic acid and allyl sucrose or allyl pentaerythritol, such as Carbopol® (e.g., Aqua SF-1, Aqua SF-3, Aqua CC, Silk 100, SC-800, 980 Polymer, Ultrez 10, Ultrez 21) or Pemulen™ (e.g., TR-1, TR-2, EZ-4U). In some embodiments, the viscosity modifier is a polyethylene glycol (PEG) which can have various molecular weights, such as PEG-400. In some embodiments, the viscosity modifier is a natural polysaccharide, such as xanthan gum, guar gum, or cellulose gum. In some embodiments, the viscosity modifier is a cellulose derivative, such as carboxymethylcellulose (CMC) or hydroxyethylcellulose (HEC). Examples of viscosity modifiers include, but are not limited to, Viscolam®, Esaflor®, Ammonyx®, Ninol®, and Amphosol® thickeners. In some embodiments, the viscosity modifier is carboxymethylcellulose (CMC).

[0075] In some embodiments, the aversive coating further comprises a colorant. In some embodiments, the dry weight composition of the aversive coating comprises 0.5% to 55% by weight of a colorant. In some embodiments, the dry weight composition of the aversive coating comprises 5% to 55%, 10% to 55%, 20% to 55%, 30% to 55%, or 40% to 55% by weight of a colorant. In some embodiments, the colorant comprises FD&C Blue No. 1 (Brilliant Blue FCF), FD&C Blue No. 2 (Indigo Carmine), FD&C Green No. 3 (Fast Green FCF), FD&C Red No. 3 (Erythrosine), FD&C Red No. 40 (Allura Red AC), FD&C Yellow No. 5 (Tartrazine), or FD&C Yellow No. 6 (Sunset Yellow). In some embodiments, the aversive coating comprises FD&C Blue No. 1.

[0076] In some embodiments, the dry weight composition of the aversive coating comprises about 3.0% to about 9.0% by weight of DNB and about 47% to about 97% by weight of PVA. In some embodiments, the dry weight composition of the aversive coating comprises 3.0% to about 9.0% by weight of DNB, about 47% to about 93% by weight of PVA, and about 4% to about 48% by weight of SDS.

[0077] In one embodiment, the dry weight composition of the aversive coating comprises about 9.0 wt% DNB and about 91 wt% PVA. In one embodiment, the dry weight composition of the aversive coating comprises about 5.0 wt% DNB and about 95 wt% PVA.

[0078] In one embodiment, the dry weight composition of the aversive coating comprises about 3 wt% DNB, about 65 wt% PVA, and about 32 wt% SDS. In one embodiment, the dry weight composition of the aversive coating comprises about 5 wt% DNB, about 48 wt% PVA, and about 47 wt% SDS. In one embodiment, the dry weight composition of the aversive coating comprises about 8 wt% DNB, about 84 wt% PVA, and about 8 wt% SDS. In one embodiment, the dry weight composition of the aversive coating comprises about 5 wt% DNB, about 91 wt% PVA, and about 4 wt% Lubrizol 2063.

[0079] In one embodiment, the dry weight composition of the aversive coating comprises about 5.0 wt% DNB and about 95 wt% PAA. In one embodiment, the dry weight composition of the aversive coating comprises about 5.0 wt% capsaicin and about 95 wt% PVA.

[0080] Electrochemical cell

[0081] Aspects of the present disclosure relate to electrochemical cells coated with the aversive coatings described herein. The electrochemical cell comprises a positive terminal defining a first portion of an exterior of the electrochemical cell; a negative terminal electrically isolated from the positive terminal and defining a second portion of the exterior of the electrochemical cell; an anode disposed within an interior of the electrochemical cell and electrically connected to the negative terminal; and a cathode disposed within the interior of the electrochemical cell, wherein the cathode is electrically separated from the anode and electrically connected to the positive terminal. At least a portion of the exterior of the electrochemical cell is coated with the aversive coatings provided herein.

[0082] In some embodiments, the electrochemical cell is a button cell or a coin cell. In some embodiments, the electrochemical cell is a lithium coin cell. Lithium coin cells include, but are not limited to, CR1025, CR1216, CR1616, CR1620, CR1632, CR2016, CR2025, CR2032, CR2430, and CR2450 cells. Coin cells typically have diameters of 10 mm, 16 mm, 20 mm, and 24 mm, which provide approximately 79 mm 2 , 201 mm 2 , 314 mm 2 , and 452 mm2 terminal area.

[0083] Certain embodiments include electrochemical cells having an aversive coating covering at least a portion of at least one battery terminal (e.g., a positive terminal or a negative terminal), wherein the aversive coating has a thickness thin enough for the aversive coating to have a low enough electrical resistance to allow current generated by the electrochemical cell to pass through the aversive coating to a connected device (e.g., a terminal of the connected device). For example, a positive terminal can be coated with an aversive coating, a negative terminal can be coated with an aversive coating, or a portion of a positive terminal and / or a negative terminal can be coated with an aversive coating (e.g., greater than 50 area% of a positive terminal; greater than 50 area% of a negative terminal; less than 50 area% of a positive terminal; or less than 50 area% of a negative terminal).

[0084] In some embodiments, greater than 50 area%, greater than 60 area%, greater than 70 area%, greater than 75 area%, greater than 80 area%, greater than 85 area%, or greater than 90 area% of a positive terminal and / or a negative terminal is coated with an aversive coating.

[0085] In some embodiments, greater than 50 area% of an outer surface of a positive terminal is coated with an aversive coating. The outer surface 25 of the positive terminal 20 is shown in Figure 2 and Figure 3 .

[0086] In some embodiments, greater than 50 area% of an outer surface of a negative terminal is coated with an aversive coating. The outer surface 17 of the negative terminal 12 is shown in Figure 2 and Figure 3 .

[0087] In some embodiments, a sidewall of a grommet is not coated with an aversive coating. The sidewall 24 of the grommet 30 is shown in Figure 2 and Figure 3 .

[0088] Figure 5 shows one example of a coin cell 10 having a thin layer 60 of aversive coating applied to a negative terminal, and Figure 6 shows a schematic cross-sectional view of a coin cell having a thin layer 60 of aversive coating applied to a negative terminal.

[0089] In some embodiments, the aversive coating covers a circular area on the positive terminal and / or the negative terminal. In some embodiments, the circular area covered by the aversive coating has a diameter of about 16 mm.

[0090] In some embodiments, an electrochemical cell having greater than 50% of the area of its positive and / or negative terminal coated with a repellent coating maintains a resistance of less than 68,000 Ω, less than 60,000 Ω, less than 50,000 Ω, less than 40,000 Ω, less than 30,000 Ω, less than 20,000 Ω, less than 10,000 Ω, or less than 1,000 Ω. In some embodiments, an electrochemical cell having greater than 50% of the area of its positive and / or negative terminal coated with a repellent coating maintains a resistance of less than 100 Ω. The resistance (e.g. ) from a repellent coating is affected by the thickness of the repellent coating and the percentage of terminal area coated with the repellent coating. In order for an electrochemical cell having a terminal coated with a repellent coating to maintain adequate performance, the resistance from the coating must be low enough. However, the threshold of resistance that is low enough to maintain performance can vary significantly based on the type and application of the electrochemical cell. Electrochemical cells used for low rate applications, such as watch batteries, use a constant low current and thus can maintain performance at a higher resistance from a repellent coating. For example, a CR2032 lithium coin cell used can have a thicker layer of repellent coating with a resistance of less than 68,000 Ω, such as 10,000 Ω, while maintaining functionality as a watch battery. However, for electrochemical cells designed for higher discharge rates, such as a key fob battery that uses higher current for short pulses, a lower resistance is necessary for performance. For alkaline coin or button cells, such as an LR44 battery used in a key fob, in order to provide a 10 mA current, the resistance should be less than 100 Ω to maintain a voltage of 1 V. Thus, a thinner layer of repellent coating with a very low resistance (<100 Ω) can be used for devices with higher discharge rates.

[0091] Regardless of the location of the repellent coating on the electrochemical cell (e.g., covering a large portion of the negative terminal), the repellent coating is applied in a very thin layer. In some embodiments, the repellent coating has a thickness of less than 1 pm to provide a low enough resistance to allow current to pass through the repellent coating. In some embodiments, the repellent coating has a thickness of less than 0.8 pm. In some embodiments, the repellent coating has a thickness of about 0.4 pm to about 0.6 pm.

[0092] In some embodiments, the total dry weight of repellent coating applied to the electrochemical cell is about 0.1 mg to about 0.5 mg. In some embodiments, the total dry weight of repellent coating applied to the electrochemical cell is about 0.4 mg.

[0093] To be of sufficient aversive nature, at least 1 pg of the aversive gustatory agent is applied to each electrochemical cell. In some embodiments, the total amount of aversive gustatory agent applied to the electrochemical cell is between 1 pg and 50 pg, between 5 pg and 50 pg, between 5 pg and 40 pg, between 5 pg and 30 pg, between 10 pg and 30 pg, or between 10 pg and 25 pg. In some embodiments, the total amount of aversive gustatory agent applied to the electrochemical cell is approximately 25 pg.

[0094] In some embodiments, the electrochemical cell is packaged in a child-resistant package for sale. Figure 7 Embodiments of the child-resistant package 600 are shown with two batteries 610 disposed within the child-resistant package 600, but it should be understood that in other example embodiments, one battery or more than two batteries can be packaged within a single child-resistant package. As shown, the child-resistant package can embody a blister package having a planar paperboard backing 601 and a covering layer of thermoformed plastic 602 adhered to a surface of the planar paperboard backing 601. In the illustrated embodiment, the thermoformed plastic layer 602 includes a battery receptacle 603 that is formed to house the one or more batteries packaged within the package. The battery receptacle 603 has an open end and defines a recess sized such that the one or more batteries fit entirely within the battery receptacle 603 so that the planar paperboard backing 601 can be secured across the open end of the recess. In addition, the plastic layer 602 additionally includes a reinforcing ridge that surrounds the battery receptacle 603. The reinforcing ridge 604 is hollow and extends in the same direction as the battery receptacle 603. The reinforcing ridge 604 provides additional rigidity to the child-resistant package 600 to deter a child from bending the child-resistant package 600 to release the batteries stored therein.

[0095] The plastic layer 602 can include any of a variety of thermoplastic plastics. For example, the plastic layer can be polyvinyl chloride (PVC), although other plastic materials can also be used. The plastic layer can be thick enough to prevent a child from tearing the plastic layer. For example, the plastic layer can have a thickness of greater than 3 mils (e.g., between 3-7 mils).

[0096] As described above, the plastic layer 602 can be adhered to the flat paperboard backing 601 using an adhesive. For example, the adhesive can be a polyurethane-based adhesive, although other adhesives can be used. Greater than 50% of the area of the flat paperboard backing 601 can be adhered to the flat portion of the plastic layer 602. Greater percentage of the flat paperboard backing 601 adhered to the plastic layer 602 increases the difficulty for a child to remove the flat paperboard backing 601 from the plastic layer 602 to release the battery therefrom. Accordingly, certain embodiments can adhere greater than 60%, greater than 70%, greater than 80%, or greater than 90% of the flat paperboard backing 601 to the plastic material 602 by area.

[0097] Further, as shown in FIG. 6B, the size of the plastic layer 602 can cover the entire area of the flat paperboard backing 601. In this manner, a child cannot bend the flat paperboard backing 601 to delaminate or otherwise release the plastic layer 602 from the surface of the flat paperboard backing 601. Figure 7

[0098] Methods of making electrochemical cells with aversive coatings

[0099] Methods of making electrochemical cells coated with aversive coatings are described. The electrochemical cells disclosed herein can be made according to any method known in the art. The method includes preparing a coating solution by dissolving an aversive agent composition and a water-soluble polymer in one or more solvents, applying the coating solution to at least a portion of the exterior of an electrochemical cell, and drying the solution onto the exterior of the electrochemical cell.

[0100] To provide a low enough resistance to allow current to pass through the aversive coating, the aversive coating is applied in a thin layer (e.g., < 1 pm). A coating solution that has been sufficiently diluted with a solvent can be used to achieve a thin enough layer of the aversive coating. Additives in the coating solution such as surfactants and viscosity modifiers can also be used to apply a thin layer of the aversive coating.

[0101] ​The coating solution includes 0.001 wt% to 0.1 wt% of the aversive taste agent and 0.01 wt% to 1.0 wt% of the water-soluble polymer dissolved in one or more solvents. The water-soluble polymer and the aversive taste agent are dissolved in the solvent to provide a final concentration of 0.01 wt% to 1.0 wt% of the water-soluble polymer and 0.001 wt% to 0.1 wt% of the aversive taste agent in the coating solution. Having a low concentration (within the ranges discussed) of the water-soluble polymer and the aversive taste agent (and other additives, such as colorants, if applicable) ensures that the resulting wet mixture can be applied in a thin layer onto the surface of the battery such that the passage of current from the battery terminals through the dried coating is not impeded. While the coating does provide some resistance to the current, providing the inherently resistive coating in a thin enough layer enables electrons to tunnel through the coating such that current can flow from the battery.

[0102] In some embodiments, the coating solution further includes 0.001 wt% to 0.1 wt% of an adhesion promoter. In some embodiments, the coating solution further includes 0.001 wt% to 0.2 wt% of a colorant, such as FD&C Blue No. 1. In some embodiments, the coating solution further includes 0.001 wt% to 0.2 wt% of a surfactant. In some embodiments, the coating solution further includes 0.001 wt% to 0.1 wt% of a viscosity modifier.

[0103] In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA and about 0.01 wt% DNB in one or more solvents. In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA, about 0.01 wt% DNB, and about 0.001 wt% to about 0.1 wt% Lubrizol 2063 in one or more solvents. In some embodiments, the coating solution is prepared by dissolving about 0.1 wt% to about 0.2 wt% PVA, about 0.01 wt% DNB, and about 0.01 wt% to about 0.1 wt% SDS in one or more solvents.

[0104] The water-soluble polymer can be heated to an appropriate temperature for a period of time to fully dissolve in the coating solution. In some embodiments, the water-soluble polymer is PVA, and the PVA is heated to about 95 °C for about 60 minutes to dissolve. In some embodiments, a solution of the dissolved adhesion promoter (e.g., Lubrizol 2063) is added to the coating solution including the dissolved water-soluble polymer. In some embodiments, the coating solution heated to dissolve the water-soluble polymer is cooled before the addition of the aversive agent composition including the aversive taste agent and optional colorant.

[0105] As shown in FIG. 1, a method of manufacturing coated electrochemical cells on an assembly line can include introducing a tray of electrochemical cells 100 after manufacturing, performing a pretreatment process 200, applying a coating solution 300, drying the coating on the electrochemical cells 400, and removing the tray 500 for packaging. Figure 4 The outer surface of the electrochemical cell can be cleaned after manufacturing as part of the pretreatment process 200 and prior to applying the coating solution 300. Removal of grease or residue from the manufacturing process can facilitate adhesion of the coating solution to the electrochemical cell. In some embodiments, the electrochemical cell is sprayed with deionized water for a period of time (e.g., 5 to 10 seconds) prior to applying the coating solution. In some embodiments, the electrochemical cell is rinsed at a temperature above room temperature (e.g., 27°C to 35°C). The electrochemical cell can be dried prior to applying the coating solution. In some embodiments, the electrochemical cell is dried with hot air for a period of time (e.g., 1 to 5 seconds) after rinsing. In some embodiments, the electrochemical cell is dried with air at a temperature of about 25°C.

[0106] The aversive coating can be applied to the electrochemical cell according to any method known in the art. In some embodiments, the coating solution is applied by dipping, spraying, printing, or dispensing the coating solution on the electrochemical cell. Dipping all or a portion of the electrochemical cell into the coating solution can be used to apply a thin layer of the aversive coating to the electrochemical cell. The coating solution can also be sprayed onto one or both of the terminals to apply a thin layer of the aversive coating. In embodiments where only a portion of the positive or negative terminal is coated with the aversive coating, a mask can be used to selectively apply the aversive coating to the desired portion of the electrochemical cell. A mask is a solid, non-absorbing material having holes or gaps in a desired pattern and is placed between the electrochemical cell and the device dispensing the coating solution to enable the coating solution to be deposited on specific portions of the electrochemical cell. The mask can be removed after the aversive coating is dried.

[0107] In some embodiments, the coating solution is applied to greater than 60%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of the area of the positive terminal and / or the negative terminal.

[0108] In some embodiments, a total amount of about 20 mg to about 250 mg of the coating solution is applied to the electrochemical cell.

[0109]

[0110] Example

[0111] ​As discussed herein, a bittering agent, coloring agent, salivating agent, and / or other aversive agent can be added to at least a portion of the exterior of the coin cell battery. The aversive agent can include a substance that elicits a strong unpleasant taste or smell, such as a spicy, peppery, sour, bitter, or foul taste. Examples include capsaicin, allyl isothiocyanate, and piperine. For example, one or more aversive agents can be added to a coating that adheres to the exterior surface of the battery. In one embodiment, a water-soluble polymer such as polyvinyl alcohol (PVA) is added to a water-based aversive agent solution to encapsulate the aversive agent in a PVA network and apply to the battery surface. As the water of the aversive agent solution evaporates, the polymer acts as a binder and adheres the aversive agent (and other active materials, such as coloring agents and / or salivating agents) to the battery surface. However, the coating remains soluble in water (or water-like solutions, such as saliva) so that when a person (e.g., a child) places the battery in their mouth, the aversive agent is released from the battery surface. The unpleasant taste of the aversive agent can cause the person to spit out the battery rather than swallow it.

[0112] The coating (comprising a polymer, bittering agent, and / or other active material) can be added to any portion of the exterior of the coin cell battery, including on one terminal or both terminals of the battery. The resulting coating does not impede the electrical conductivity of the battery, which the inventors believe is because electron tunneling is still possible through the coated material.

[0113] For water-soluble polymers, such as but not limited to PVA and polyacrylic acid (PAA), the upper limit of the amount of polymer used (e.g., the resulting thickness of the polymer coating) is the amount of polymer in which the exterior of the battery remains electrically conductive. The lower limit of the amount of polymer used is the amount of polymer that sufficiently binds the aversive agent (e.g., denatonium benzoate (DNB), but other coloring agents or salivating agents can be incorporated). When applied as a wet formulation, PVA ranges from approximately 0.1% to 0.2%. The dry weight composition of the aversive coating is approximately 45% to 99.8% PVA by weight. The polymer can be a low molecular weight polymer (1-10 Ks), a medium molecular weight polymer (10-100 Ks), or a high molecular weight polymer (>100 Ks). Low molecular weight polymers have high water solubility, and the shorter chains provide less chain entanglement and higher molecular mobility. However, low molecular weight polymers tend to form beads rather than fibers in solution and provide a weaker material. High molecular weight polymers have low water solubility, but a higher degree of chain entanglement occurs and films with high tensile strength are formed. Higher molecular weight polymers also tend to form more tenacious and chemically resistant materials. Additionally, the viscosity of a solution containing a polymer increases with molecular weight. Medium molecular weight polymers have moderate water solubility, strength, and viscosity. The appropriate size of the polymer can be selected with additives such as adhesion promoters, surfactants, and viscosity modifiers to form an aversive coating that is thin (<1 pm) and sufficiently adhered to the surface of the electrochemical cell.

[0114] The amount of aversive agent can be selected to provide an unpleasant battery taste. For example, the amount of DNB can be selected to be between 1-120 pg (e.g., between 5-30 pg) for each coin cell.

[0115] The coating can be applied using any of a variety of different coating methods, such as providing small droplets of material (e.g., by pipette). Other application methods include dipping the cell in a rinse, spraying the cell, pad printing onto the cell, screen printing onto the cell, needle dispensing onto the cell, and / or the like. Any method can be used so long as it deposits a thin layer uniformly.

[0116] In certain embodiments, additional additives can be provided to further enhance the desired properties of the resulting coating. For example, a surfactant can be added to the solution to enhance the wettability of the coating. In certain embodiments, the cell surface can also be treated by plasma sonication or other means to increase the surface energy to better accept the coating.

[0117] The coating can be applied to various locations on the exterior of the cell. The coating is transparent and colorless (in embodiments not including a colorant), and is nearly invisible if applied uniformly. Thus, the coating can be applied to the entire exterior surface of the cell, to only the positive or negative terminal (e.g., the entire negative terminal), or to any location on the exterior of the cell.

[0118] When coating a terminal (e.g., the negative terminal), a portion of the terminal (e.g., the outermost 1-2 mm to prevent shorting when wetted with the solution) can be masked so that the masked portion is not coated with the coating material. The coating material can then be sprayed onto the terminal, and the mask can then be removed after the coating dries.

[0119] The coating solution itself can have the following composition: solvent (including, e.g., water, isopropyl alcohol, ethanol, mixtures thereof, and / or other organic solvent materials); DNB (or other aversive agent), optional additives (e.g., surfactants, adhesion promoters, etc.), optional low concentration polymer binder (e.g., PVA, PAA, polyethylene glycol, polyacrylamide, and / or the like), optional viscosity modifier (e.g., carboxymethyl cellulose (CMC)) for better processing. The coating can be applied by spraying.

[0120] The polymeric binder can be provided in the solution in an amount of between about 0.00001 wt% and 1 wt%. For example, in an amount of between about 0.01 wt% and 0.2 wt%, or more specifically, in an amount of between about 0.1 wt% and 0.2 wt%. In certain embodiments, the colorant can be provided in the solution in an amount of about 0.001 wt% and 0.2 wt%. The viscosity modifier (e.g., thickening agent) can be provided in the solution in an amount of about 0 wt% and 0.1 wt%. The aversive agent (e.g., DNB) can be provided in an amount of between about 0.001 wt% and 0.1 wt% (e.g., between about 0.005 wt% and 0.02 wt%) of the solution.

[0121] Prior to coating, the battery can be cleaned using, for example, deionized water (e.g., cyclically processed deionized water having a conductivity <10 uS / cm) at 30°C for a total of 8 seconds. The battery can be subjected to hot air drying starting 0.5 seconds after rinsing is complete. The hot air drying has a duration of about 3 seconds at an air temperature of 25°C.

[0122] The coating can be sprayed onto the cleaned battery surface about 1 second after air drying is complete. The battery can then be dried (e.g., by hot air drying) to dry the coating onto the battery. If a portion of the battery is masked, the mask can be removed after the coating is dried.

[0123] However, when the coating is sprayed on the terminals of the battery, the coating can have a dry thickness that is thin enough to maintain electrical conductivity through the coating (e.g., via electron tunneling).

[0124] CONCLUSION

[0125] Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which these embodiments pertain having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the embodiments are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and the associated drawings set forth exemplary embodiments, it will be understood that various modifications are possible to one skilled in the art within the scope of the appended claims. In this regard, for example, the different combinations of elements and / or functions described above can be provided in alternative embodiments. For example, elements and / or functions can be interchanged among embodiments, and / or the various storage, database, and / or communication mechanisms can be used to store and / or communicate data and / or transmit it collected and used by the elements disclosed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0126] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters given in the specification and claims are approximations only and thus can vary by a small amount. Generally, the numerical values are approximations that can vary by ± 20% in one example, ± 10% in another example, ± 5% in another example, ± 1% in another example, and ± 0.1% in another example, as such variations are appropriate to perform the disclosed methods.

[0127] All examples and / or embodiments presented herein are considered to be non-limiting. Moreover, no inference should be made regarding the embodiments discussed herein and not discussed herein, as such inference would be improper in light of the above discussion. For example, it is to be understood that the logic and / or topology of any combination of any data flow sequences, program components (collections of components), other components, and / or any current set of features as described in the drawings and / or throughout, are not limited to a fixed order and / or arrangement of operations, but that any disclosed order is exemplary, and that the disclosure contemplates all equivalents, regardless of order. Moreover, it is to be understood that these features and steps are not limited to sequential execution, but can be executed asynchronously, concurrently, in parallel, simultaneously, synchronously, etc., as the disclosure contemplates. Thus, some of these features can be mutually exclusive in that they cannot exist simultaneously in a single embodiment. Similarly, some features apply to one aspect of the innovation and not to others. Moreover, the disclosure includes other innovations that are disclosed and can not be explicitly recited. Thus, it is to be understood that the advantages, embodiments, examples, functions, features, logic, operations, organization, structures, topologies, and / or other aspects of the disclosure should not be considered to be limiting or a restriction on the disclosure defined by the embodiments, examples, claims, or equivalents thereof. It is to be understood that various embodiments or portions of various embodiments of coin cells described herein can be implemented depending on the particular needs and / or features of an electrochemical cell, such as a coin cell, which enables great flexibility and customization.

Claims

1. An electrochemical cell comprising: a positive terminal defining a first portion of an exterior of the electrochemical cell; a negative terminal electrically insulated from the positive terminal and defining a second portion of the exterior of the electrochemical cell; an anode disposed within an interior of the electrochemical cell and electrically connected to the negative terminal; a cathode disposed within the interior of the electrochemical cell, wherein the cathode is electrically separated from the anode and electrically connected to the positive terminal; and an aversive coating covering at least a portion of the exterior of the electrochemical cell, wherein a dry weight composition of the aversive coating comprises: 0.2 wt% to 10 wt% of an aversive taste agent; and 45 wt% to 99.8 wt% of a water-soluble polymer, wherein a thickness of the aversive coating provides a low enough electrical resistance to allow passage of electrical current generated by the electrochemical cell through the aversive coating.

2. The electrochemical cell of claim 1, wherein the aversive taste agent is selected from the group consisting of denatonium benzoate (DNB), capsaicin, allyl isothiocyanate, or piperine.

3. The electrochemical cell of claim 1, wherein the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide, and polyethylene glycol (PEG).

4. The electrochemical cell of claim 1, wherein the water-soluble polymer is PVA, and the PVA has a molecular weight of about 10,000 to about 150,000.

5. The electrochemical cell of claim 1, wherein the water-soluble polymer is PVA, and the PVA is about 80% to about 95% hydrolyzed.

6. The electrochemical cell of claim 4, wherein the PVA has a molecular weight of about 75,000 and is about 88% hydrolyzed.

7. The electrochemical cell of claim 1, wherein the aversive coating further comprises 0.1 wt% to 5.0 wt% of an adhesion promoter.

8. The electrochemical cell of claim 7, wherein the adhesion promoter is Lubrizol 2063.

9. The electrochemical cell of claim 1, wherein the aversive coating further comprises 0.01 wt% to 50 wt% of a surfactant.

10. The electrochemical cell of claim 9, wherein the surfactant is sodium dodecyl sulfate (SDS).

11. The electrochemical cell of claim 1, wherein the aversive coating comprises: about 3.0 wt% to about 9.0 wt% DNB, and about 47 wt% to about 97 wt% PVA.

12. The electrochemical cell of claim 11, wherein the aversive coating further comprises about 2.0 wt% to about 3.0 wt% Lubrizol 2063.

13. The electrochemical cell of claim 11, wherein the aversive coating further comprises about 4.0 wt% to about 50 wt% SDS.

14. The electrochemical cell of claim 1, wherein the electrochemical cell is a button cell or a coin cell.

15. The electrochemical cell of claim 11, wherein the total amount of aversive gustatory agent is about 10 pg to about 25 pg.

16. The electrochemical cell of claim 11, wherein the aversive coating covers greater than 50% of the area of at least one of the positive or negative terminal.

17. The electrochemical cell of claim 16, wherein the aversive coating covers greater than 50% of the total area of the first portion of the exterior and the second portion of the exterior of the electrochemical cell.

18. The electrochemical cell of claim 11, wherein the aversive coating covers greater than 50% of the area of the second portion of the exterior of the electrochemical cell.

19. The electrochemical cell of claim 11, wherein the total dry weight of aversive coating applied to the electrochemical cell is about 0.1 mg to about 0.5 mg.

20. The electrochemical cell of claim 11, wherein the thickness of the aversive coating is less than 1 pm.

21. The electrochemical cell of claim 20, wherein the thickness of the aversive coating is less than 0.8 pm.

22. The electrochemical cell of claim 21, wherein the thickness of the aversive coating is about 0.4 pm to about 0.6 pm.

23. The electrochemical cell of claim 1, wherein the electrochemical cell is packaged in a child-resistant package.

24. A method of making a child-resistant electrochemical cell, wherein at least a portion of the exterior of the electrochemical cell is coated with an aversive coating, wherein the dry weight composition of the aversive coating comprises 0.2 wt% to 10 wt% aversive gustatory agent and 45 wt% to 99.8 wt% water-soluble polymer, wherein the electrochemical cell is electrically conductive through one or more positive or negative terminals coated with the aversive coating, the method comprising: preparing a coating solution, wherein the coating solution comprises 0.001 wt% to 0.1 wt% aversive gustatory agent and 0.01 wt% to 1.0 wt% water-soluble polymer dissolved in one or more solvents; applying the coating solution to greater than 50% of the area of a positive or negative terminal of an electrochemical cell to provide a thickness that provides a low enough resistance to allow current generated by the electrochemical cell to pass through the aversive coating; and drying the solution onto the exterior of the electrochemical cell.

25. The method of claim 24, wherein the aversive gustatory agent is selected from the group consisting of denatonium benzoate (DNB), capsaicin, allyl isothiocyanate, or piperine, and wherein the coating solution comprises 0.2 wt% to 2.0 wt% aversive gustatory agent.

26. The method of claim 24, wherein preparing the coating solution further comprises dissolving 0.001 wt% to 0.1 wt% adhesion promoter in the one or more solvents.

27. The method of claim 24, wherein the water-soluble polymer is PVA, and wherein the PVA is heated to about 95 °C for about 60 minutes in order to dissolve. ​ 28. The method of claim 27, wherein preparing the coating solution further comprises cooling the PVA prior to adding the aversive taste agent.

29. The method of claim 24, wherein preparing the coating solution further comprises dissolving 0.001 wt% to 0.2 wt% of a surfactant in the one or more solvents.

30. The method of claim 24, wherein the coating solution comprises: about 0.01 wt% DNB; and about 0.1 wt% to about 0.2% PVA.

31. The method of claim 30, wherein the coating solution further comprises about 0.001 wt% to about 0.1 wt% Lubrizol 2063.

32. The method of claim 30, wherein the coating solution further comprises about 0.01 wt% to about 0.1 wt% SDS.

33. The method of claim 24, wherein the coating solution is applied to greater than 60%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of the area of the positive terminal.

34. The method of claim 24, wherein the coating solution is applied to greater than 60%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% of the area of the negative terminal.

35. The method of claim 24, wherein the applying comprises dipping or spraying the coating solution on at least a portion of the positive terminal or the negative terminal of the electrochemical cell.

36. The method of claim 24, wherein the method further comprises cleaning an exterior surface of the electrochemical cell prior to applying the coating solution.

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