Battery cells with a safety layer

Abstract

To provide a water-responsive battery cell with a safety layer that can protect tissue from damage and / or electrolysis when the battery cell is exposed to aqueous solutions or moist tissue.SOLUTION: A battery 50 includes a housing having first and second poles, and a composite water-responsive safety layer 64 including a polymeric material and positioned adjacent to at least one of the first and second poles, the composite water-responsive safety layer is adapted to change from an electronically non-conductive state to an electronically conductive state upon contact with an aqueous solution, the composite water-responsive safety layer further includes at least one metal salt.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] Cross-reference with related applications This application claims priority to U.S. Patent Application No. 16 / 016,466, filed on June 22, 2018, which is a continuation-in-part application of U.S. Patent Application No. 15 / 677,921, filed on 15 August 2017, both of which are incorporated into this Application in their entirety by reference and constitute part of this Application.

[0002] Statement regarding federally funded research or development This invention was made under CRADA (SC03 / 1672) between Procter & Gamble Company and Sandia National Laboratories and operated for the U.S. Department of Energy. Duracell Company and its subsidiary Duracell US Operations, Inc. are successors to the interests of Procter & Gamble Company under CRADA (SC03 / 1672). The Government has certain rights in this invention.

[0003] This disclosure relates to a battery cell, and more particularly to a battery cell having a water-responsive safety layer that can protect the battery cell from tissue damage and / or electrolysis when exposed to an aqueous solution or moist tissue. [Background technology]

[0004] The background information provided herein is generally intended to provide context for the information presented.

[0005] Electrochemical cells, or batteries, are generally used as sources of electrical energy. Small batteries are particularly useful for powering consumer products. Small batteries come in various cell types. Common small battery cell types include AAA, AA, B, C, D, 9V, CR2, and CR123A. Other types of small batteries, known as button cells (including wider cells sometimes called coin cells), are frequently used to power a wide variety of products, including but not limited to watches, cameras, calculators, keyless entry systems for vehicles, laser pointers, and glucometers. Figure 1 shows the structure of a typical button cell 10, comprising a cathode 12 located in a cathode can 14 and an anode 16 located in an anode cup 18. A separator 20 physically separates and electronically insulates the anode 16 from the cathode 12. An insulating gasket 22 helps to seal the cell to prevent electrolyte loss and insulate the cathode can 14 from the anode cup 18, preventing ambient atmospheric components from entering the cell. Button cells typically have a long service life, for example, well over a year in the continuous use of a wristwatch. Furthermore, most button cells have low self-discharge, and therefore retain their charge for relatively long periods when not under load.

[0006] Button cell batteries are common in many portable consumer electronic devices, but the size, shape, and appearance of these batteries, particularly coin-cell batteries with a diameter of 20mm such as 2016 lithium cells and 2032 lithium cells, can pose a swallowing hazard to infants, toddlers, and pets. These hazards can cause physical harm, especially if the cells are swallowed without the knowledge of others. Furthermore, some of these button cell batteries may pose a relatively greater hazard than others, and consumers may not fully understand this risk. For example, coin-cell batteries such as 2016 3V lithium cells and 2032 3V lithium cells, based on the chemical reaction between lithium and manganese dioxide, are sized to easily become lodged in a person's throat and thus could cause electrolysis of bodily fluids or, for example, combustion of esophageal / organ tissue if swallowed. [Overview of the project] [Problems that the invention aims to solve]

[0007] In one embodiment, the disclosure provides a battery comprising a housing having first and second electrodes, and a composite water-responsive safety layer comprising a polymer material and positioned adjacent to at least one of the first and second electrodes, wherein the composite water-responsive safety layer changes from an electron-nonconducting state to an electron-conducting state upon contact with an aqueous solution, and further comprising at least one metal salt.

[0008] In one improvement of the battery, at least one metal salt of the composite water-responsive safety layer comprises at least a first metal salt and a second metal salt.

[0009] In another embodiment, the Disclosure provides a method comprising the steps of: preparing a battery housing having first and second electrodes; and forming a composite water-responsive safety layer between the first and second electrodes of the battery housing by depositing a composition between the electrodes such that the composition is adjacent to at least one of the first and second electrodes, wherein the composition comprises a polymer material and at least one metal salt, and the composite water-responsive safety layer changes from an electron-nonconducting state to an electron-conducting state upon contact with an aqueous solution.

[0010] In one improvement of this method, at least one metal salt of the composition comprises at least a first metal salt and a second metal salt.

[0011] This specification concludes with claims that specifically point out and expressly claim the subject matter that is deemed to constitute the present invention, but the present invention will be better understood from the following description, to be interpreted in conjunction with the accompanying drawings. The figures described below illustrate various embodiments of the battery cell disclosed herein. It should be understood that each figure illustrates a typical embodiment of the battery cell disclosed herein. [Brief explanation of the drawing]

[0012] [Figure 1] This shows a conventional button cell. [Figure 2A] This shows an example of a battery in the form of a coin cell, which has a composite water-responsive safety layer that changes from an electron-nonconductive state to an electron-conductive state when it comes into contact with an aqueous solution. [Figure 2B] This shows an example of a battery in the form of a coin cell, which has a composite water-responsive safety layer that changes from an electron-nonconductive state to an electron-conductive state when it comes into contact with an aqueous solution. [Figure 3] This is a schematic diagram of a prototype battery configuration, in which the composite water-responsive safety layer comprises a polymer matrix containing polyethylene glycol (PEG), a metal salt, and a metal powder. [Figure 4]This is a plot of voltage changes over time in different tests using the prototype battery configuration shown in Figure 3, which represents an example of a composite water-responsive safety layer being exposed to an aqueous solution. [Figure 5] This shows an example of a button cell-shaped battery having a composite water-responsive safety layer deposited at a specific location between the negative and positive electrodes of the battery. [Figure 6] Figure 5 shows a plot of voltage changes over time in different tests relating to a battery configuration, illustrating an example of a composite water-responsive safety layer being exposed to an aqueous solution. [Figure 7] The graph illustrates the time required for an example battery cell with a composite water-responsive safety layer to short-circuit when exposed to an aqueous solution. [Figure 8] The graph illustrates the time required for another example of a battery cell with a composite water-responsive safety layer to short-circuit when exposed to an aqueous solution. [Figure 9] The graph illustrates the time required for other typical battery cells with a composite water-responsive safety layer to short-circuit when exposed to an aqueous solution. [Modes for carrying out the invention]

[0013] An electrochemical cell or battery may be a primary or secondary battery. A primary battery is designed to be discharged only once, for example, until depleted, and then discarded. Primary batteries are described, for example, in David Linden's Handbook of Batteries (McGraw-Hill, 4th edition, 2011). A secondary battery is designed to be rechargeable. A secondary battery may be discharged and then recharged many times, for example, more than 50 times, more than 100 times, or more than 1000 times. Secondary batteries are described, for example, in David Linden's Handbook of Batteries (McGraw-Hill, 4th edition, 2011). The battery may contain water-soluble or non-water-soluble electrolytes. Therefore, the battery may contain various combinations of electrochemical bonds and electrolytes. A consumer battery may be either a primary or secondary battery. However, due to the charge stored in the battery and the exposed electrodes, it is beneficial to protect consumer batteries, especially small batteries, from damage when exposed to moist tissue. In particular, it is beneficial to protect batteries from exposing consumers to electrolysis or burns, both of which can occur, for example, if a battery is swallowed. If the positive and negative electrodes of a battery are exposed to moist bodily fluids, electrolysis of water occurs, leading to the generation of hydroxide ions, which can cause burning of tissue, especially tissue adjacent to the negative electrode. This application describes a technique for short-circuiting a battery in such a situation, thereby reducing the cell voltage and effectively preventing tissue damage.

[0014] This disclosure provides a battery cell comprising a composite water-responsive safety layer and / or a composite water-responsive and pH-responsive safety layer comprising a polymer that incorporates a safe level of benign material that can cause a short circuit to be generated electrochemically when the composite water-responsive safety layer is moistened, such as when the composite water-responsive safety layer is exposed to an aqueous solution in the form of saliva, gastric juice, or other fluids. The resulting short circuit can reduce the voltage of the battery cell to below a desired threshold level, thereby reducing and / or effectively preventing the electrolysis of water and the formation of harmful electrochemically generated ions (e.g., hydroxide ions) that accompany it. The desired threshold levels can vary, but in some examples detailed herein, the cells can preferably be short-circuited to less than 1.5V, including less than 1.4V, less than 1.3V, less than 1.2V, less than 1.1V, less than 1.0V, less than 0.9V, less than 0.8V, less than 0.7V, less than 0.6V, less than 0.5V, less than 0.4V, less than 0.3V, less than 0.2V, and less than 0.1V, and even down to about 0V. Preferably, the mere application of a composite water-responsive safety layer and / or a composite water-responsive and pH-responsive safety layer does not affect the battery cell performance under normal operating conditions, and therefore, for example, the battery has substantially the same voltage and capacity before and after the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer is provided to the battery. Batteries incorporating a composite water-responsive safety layer and / or a composite water-responsive and pH-responsive safety layer are illustrated and described herein using button cells, more particularly coin cells, but any battery type, including but not limited to common consumer batteries such as AAAA, AAA, AA, B, C, D, 9V, CR2, CR123A, 1 / 3N, button cells, and coin cells, may be modified to include the composite water-responsive safety and / or composite water and pH-responsive safety layer relating to this disclosure. Generally, short-circuiting the voltage of a battery cell to below about 1.2V completely prevents the electrolysis of water, while lowering the voltage to below 1.5V helps to reduce the amount of electrolysis that would otherwise occur.Therefore, in a preferred embodiment, since significant burning of esophageal tissue does not become apparent until after 2 hours, the voltage of the cell drops below 1.5V, more preferably below 1.2V, within 2 hours (or 7200 seconds).

[0015] As used herein, the term "water-responsive" refers to a composite safety layer that does not transition from an electronically non-conductive state to an electronically conductive state when exposed to air. Instead, a specific amount of moisture absorption is required before the composite safety layer can transition from the electronically non-conductive state to the electronically conductive state. Accordingly, the composite water-responsive safety layer is itself hygroscopic. In particular, each component comprised in the composite water-responsive safety layer is generally not hygroscopic; stated differently, the composite water-responsive safety layer generally comprises both hygroscopic components and non-hygroscopic components. As a result, the atmosphere should not cause the composite water-responsive safety layer to transition from the electronically non-conductive state to the electronically conductive state, and therefore should not cause a short circuit. However, the composite water-responsive safety layer may short circuit if exposed to a high humidity environment for a prolonged period. For example, a cell having a composite water-responsive safety layer described herein is preferably capable of being stored in an environment having a maximum relative humidity of 90% (at a temperature between about 20°C and about 50°C, for example at about 30°C or about 40°C) for at least 2 hours, at least 12 hours, at least 10 days, at least 30 days, and / or at least 60 days. In addition, a cell having a composite water-responsive safety layer described herein is preferably capable of being stored in an environment having a maximum relative humidity of 65% (at a temperature between about 20°C and about 50°C, for example at about 30°C or about 40°C) for at least 2 days, at least 10 days, at least 60 days, and / or at least 90 days.

[0016] As used herein, the term "water-responsive and pH-responsive" refers to a composite safety layer that does not necessarily transition from an electronically non-conductive state to an electronically conductive state when exposed only to water. Specifically, a water-responsive and pH-responsive composite safety layer remains in a non-conductive state when in contact with an aqueous solution having a first predetermined pH range, and transitions from the non-conductive state to the conductive state in response to contact with an aqueous fluid having a second, different predetermined pH range.

[0017] In one embodiment, a composite water-responsive and pH-responsive positive composite safety layer is provided, which remains in a non-conductive state in an aqueous solution having an acidic or near-neutral pH value, and transitions from a non-conductive state to a conductive state in response to contacting the composite water-responsive and pH-responsive safety layer with a water-soluble fluid having a pH higher than 5.0, for example, from about 5.0 to about 12.0, from about 5.5 to about 8.0, from about 6.0 to about 7.8, from about 6.2 to about 7.6, from about 8.0 to about 10.0, from about 10.0 to about 12.0, or higher than 12.0. Accordingly, the pH of saliva or bodily fluid, which is altered as a result of water electrolysis, can promote dendrite growth and the accompanying cell short-circuiting. By way of example, the composite water-responsive and pH-responsive safety layer may comprise a polymer, for example, polyvinyl acetate, a salt such as ammonium carbonate, and a metal powder, for example, copper powder or zinc powder. When the composite water-responsive and pH-responsive safety layer is brought into contact with an alkaline medium such as saliva, ammonium carbonate forms ammonia and carbonate anions, and the metal powder may oxidize to form metal cations that can be reduced at the negative electrode of the battery, whereby a dendritic metal structure grows within the composite water-responsive safety layer and can electronically connect the negative electrode to the positive electrode under safety conditions, for example, when a person or an infant swallows a battery cell.

[0018] In other embodiments, a composite water-responsive and pH-responsive safety layer is provided that remains nonconductive in aqueous solutions having a neutral or acidic pH, for example, less than 7.0, and changes from nonconductive to conductive in response to contact with a water-soluble fluid having an alkaline pH greater than 7.0, for example, about 8.0 to about 12.0. As an example, the composite water-responsive and pH-responsive safety layer may comprise a polymer, such as polyvinyl acetate, a water-soluble salt such as ammonium chloride, and a water-insoluble copper metal salt such as copper carbonate. When the composite water-responsive and pH-responsive safety layer is brought into contact with an alkaline medium such as saliva, ammonium chloride (NH4Cl) can dissolve near and within the safety layer. Hydroxide ions generated at the negative electrode due to the electrolysis of water deprotonate ammonium ions to form water ammonia (NH3). The water-soluble / soluble ammonia reacts with a substantially insoluble metal salt copper carbonate to form a soluble composite ion Cu(NH3)4, which can be reduced at the negative electrode of the battery. 2+ This allows for the formation of a dendritic metal structure, which grows within a composite water-responsive and pH-responsive layer, enabling the electronic connection of the negative electrode to the positive electrode under safe conditions, for example, when a person or infant swallows the battery cell.

[0019] The composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer comprises polymer materials. Any number of polymers may be used individually or in combination to form the composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer. In preferred embodiments, at least one of the polymers in the composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer is a hygroscopic polymer, although the composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer may also be made hygroscopic by metal salts contained therein. In addition to polyethylene glycol (PEG), other polymers or combinations thereof can be used to form the layer matrix. Non-limiting examples include, but are not limited to, polyethylene oxide (PEO), polyacrylic acid (PAA), polyamide (PA), polymethyl methacrylate and other polyacrylates, polyvinyl alcohol and modified polyvinyl alcohol, acrylate copolymers, polyvinyl acetate, poly(vinyl butyrate), poly(vinyl propionate), and poly(vinyl formate), but are not limited to polyvinyl esters, polyvinylpyrrolidone, pullulan, gelatin, hydroxypropyl methylcellulose (HPMC), low viscosity grade hydroxypropyl cellulose, polysaccharides, guar gum, xanthan gum, locust bean gum, carrageenan, and starch, but are not limited to water-soluble natural polymers, modified starch including but not limited to ethoxylated starch and hydroxypropylated starch, copolymers of the aforementioned, including but not limited to polyvinyl ester copolymers such as poly(ethylene-vinyl acetate), and copolymers of any of the aforementioned. The polymer is preferably a biologically inert material that is non-toxic or has little toxicity. The weight-average molecular weight of the polymer is not limited, but is generally at least 1 kD, for example 1 kD to 1000 kD, 5 kD to 750 kD, 50 kD to 750 kD, for example about 500 kD.

[0020] In an embodiment, the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer comprises a metal salt. Since the metal salt provides a reducible sacrificial material at the negative electrode of the battery, a dendritic metal structure grows within the composite water-responsive membrane to electronically connect the negative electrode to the positive electrode under safe conditions, for example when a person or an infant swallows the battery cell, whereby the battery cell is exposed to an aqueous solution in the form of saliva, gastric juice, or other fluids, and as a result, the cell is strategically short-circuited without significant electrolysis of water and the accompanying hydroxide ion generation and tissue burning. Copper(II)(Cu +2 ), Iron(II)(Fe +2 ), Mercury(II)(Hg +2 ), Nickel(II)(Ni +2 ), Silver(I)(Ag + ) and similar transition metal cations, and Zinc(II)(Zn +2 ), Bismuth(III)(Bi +3 ), Indium(III)(In +3 ), Lead(II)(Pb +2 ), Tin(II)(Sn +2Suitable metal salts may be used that contain, but are not limited to, other metal cations, including, combinations thereof, etc. Acetates, adipicates, alginates, ascorbicates, aspartates, benzenesulfons, benzoates, bicarbonates, bisulfates, tartrates, borates, bromides, butyrates, camphorates, camphor sulfons, carbonates, chlorides, citrates, cyclopentanepropionates, diglucons, dihydrochlorides, diphosphates, dodecyl sulfates, edetates, ethanesulfons, fumarates, glucoheptones, glucomates, glutamates, glycerophosphates, hemisulfates, heptates, hexanoates, hydrobroms, hydrochlorides, hydroiodides, hydroxides, hydroxyethanesulfons, hydroxynaphthoates, iodides, lactates, lactobionic acids, laurates, laurates Representative metal salts comprising anions, including but not limited to maleate, malonate, mandelate, mesylate, methanesulfonate, methyl bromide, methylnitrate, methyl sulfate, mucate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, piclate, pivalate, polygalacturonate, propionate, salicylate, stearate, acetate, succinate, sulfate, tanate, tartrate, theophylline, thiocyanate, triethiodide, toluenesulfonate, undecanoic acid, valerate, and mixtures thereof, may be used. Specific metal salts include, but are not limited to, bismuth carbonate, bismuth chloride, bismuth sulfate, bismuth nitrate, bismuth subsalicylate, bismuth oxide, copper carbonate, copper chloride, copper sulfate, copper oxalate, copper hydroxide, iron carbonate, iron chloride, iron sulfate, indium carbonate, indium chloride, indium sulfate, lead carbonate, lead chloride, lead sulfate, mercury carbonate, mercury chloride, mercury sulfate, nickel carbonate, nickel chloride, nickel sulfate, silver carbonate, silver chloride, silver sulfate, tin carbonate, tin chloride, tin sulfate, zinc carbonate, zinc chloride, zinc sulfate, their hydrates, their basic salts (hydroxides, oxides), and combinations thereof.Furthermore, nonmetallic salts such as ammonium carbonate ((NH4)2CO3) and ammonium chloride (NH4Cl) may be used in combination with metal salts. In addition, other metal salts such as sodium chloride (NaCl) may be included, which do not provide a reducible sacrificial substance at the negative electrode of the battery but can support the transition from an electron-nonconducting state to an electron-conducting state by, for example, acting as a humectant and / or by enhancing the conductivity of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer.

[0021] As used herein, the term “copper carbonate” refers to copper(II) carbonate (also known as cupric carbonate and neutral copper carbonate) and basic copper carbonate (also known as basic cupric carbonate, copper hydroxide, and malachite). Therefore, as used herein, the term “copper carbonate” (unless otherwise specified) refers to both (neutral) copper(II) carbonate (CuCO3) and basic copper carbonate (CuCO3·Cu(OH)2). Generally, as used herein, this term refers to basic copper carbonate, but unless further specified by neutral or basic designation, both materials should be understood as being intended.

[0022] In one improvement, at least one metal salt in the composite water-responsive safety layer comprises at least a first metal salt and a second metal salt. When the second metal salt, such as a water-insoluble copper carbonate, is present in combination with a water-soluble salt such as copper sulfate, the cell preferably does not show a change in cell voltage even after being exposed to high relative humidity for a long period of time. As used herein, “water-soluble” refers to a solute having a water solubility of more than 100 mg / L, more than 150 mg / L, more than 200 mg / L, more than 1000 mg / L, and / or more than 100 g / L (at about 25°C and about pH 7). For example, copper sulfate has a water solubility of about 220 g / L (at about 25°C and about pH 7). On the other hand, “water-insoluble” refers to a solute having a water solubility of less than 10 mg / L, less than 7.5 mg / L, less than 5 mg / L, less than 2.5 mg / L, and / or less than 1 mg / L (at about 25°C and about pH 7). For example, copper(II) carbonate has a solubility in water of approximately 1.46 mg / L (at approximately 25°C and pH 7), while basic copper carbonate has a solubility in water of approximately 4.68 mg / L (at approximately 25°C and pH 7). When a combination of water-insoluble and water-soluble salts is used, there may be a difference in water solubility between the water-insoluble and water-soluble salts of at least 10, at least 100, at least 1000, and / or at least 10,000. For example, copper sulfate is 10,000 times more soluble in water than basic copper carbonate. In other examples, the ratio of water solubility between water-insoluble and water-soluble salts can be at least approximately 1:10 (e.g., at least approximately 1:100, 1:1,000, 1:10,000, or more).

[0023] While the water solubility values ​​for many salts can sometimes be found in the literature, here they are determined using either the "flask method" or the "column elution method." As described in EPA OPPTS 830.7840 (Water Solubility), incorporated herein by reference, column elution is used for substances with low solubility (solubility less than 10 mg / L), while the flask method is used for substances with even higher solubility (solubility greater than 10 mg / L).

[0024] In short, water solubility is determined in water at the relevant pH (e.g., approximately 5.5 to 8.5, such as 7.0) and temperature (e.g., approximately 20°C to 30°C, such as approximately 25°C). In the flask method, the test substance is first pulverized and weighed into a container, so that approximately five times the amount determined by the preliminary test is placed in the container and weighed, after which the indicated amount of water is added to the container (e.g., 1 L). Once saturation is achieved, the mixture is cooled to the test temperature and stirred until equilibrium is reached. The mass concentration of the test substance dissolved in an aqueous solution (which must not contain undissolved particles) can be analytically determined by any useful methodology (gas or liquid chromatography, titration, photometry, and / or voltammetry). Gas chromatography is preferred. In the column elution method, a microcolumn containing an excess of the test substance with an inert support (beads, silica, sand, etc.) is eluted with water, and the mass concentration of the substance in the eluate is determined when the concentration of the eluate is constant. This method is based on eluting the test substance with water at a constant temperature from a column packed with a substance finely distributed on an inert support material. The flow rate of water should be adjusted so that a saturated solution escapes from the column. Saturation is achieved when the mass concentration—determined by an appropriate method—is constant in a continuous ratio of eluents at different flow rates. This is indicated by a horizontal region when the concentration is plotted against time or elution volume. As previously mentioned, the mass concentration of the test substance dissolved in aqueous solution can be analytically determined by any useful methodology (e.g., gas or liquid chromatography, titration, photometry, and / or voltammetry). Gas chromatography is preferred.

[0025] For further details on determining solubility, see, for example, the Organisation for Economic Co-operation and Development (OECD), "Test No. 105: Water Solubility," OECD Guidelines for Testing Chemicals, adopted July 27, 1995 (7 pp.); OECD Environment Department: Joint meeting of the Committee on Chemicals and the Working Group on Chemicals, Agrochemicals and Biotechnology, "Guidance Document on the Conversion / Dissolution of Metals and Metallic Compounds in Water-Soluble Media," OECD Test and Evaluation Series, No. 29, July 23, 2001 (19 pp.); "Provision of Test Methods under Regulation (EC) No. 1907 / 2006 of the European Parliament and the Council on Registration, Evaluation, Authorization and Restriction of Chemicals (REACH), Parliamentary Regulation (EC) No. 440 / 2008 of May 30, 2008," Official J. European Union. Details are cited in L142, Part.A.6 (p.57-66), May 31, 2008, (739 pp.); and in the U.S. Environmental Protection Agency, "Guidelines for Product Characterization Testing - OPPTS 830.7860 Water Solubility (Generator Column Method)," EPA 712-C-96-042, August 1996 (19 pp.) and the U.S. Environmental Protection Agency, "Guidelines for Product Characterization Testing - OPPTS 830.7840, Water Solubility: Column Elution Method, Shake Flask Method," EPA 712-C-98-041, March 1998 (14 pp.), each of which is incorporated in its entirety by reference.

[0026] In one embodiment, the composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer comprises a polymer but substantially lacks (additive) metal salts. In this regard, the metal material of the negative electrode may be oxidized, thereby providing an ion source that can serve as a sacrificial material for dendrite growth. Thus, in another embodiment, the present disclosure provides a battery comprising a housing comprising first and second electrodes, and a composite water-responsive safety layer comprising a polymer material and positioned adjacent to at least one of the first and second electrodes, wherein the composite water-responsive safety layer changes from an electron-nonconducting state to an electron-conducting state when in contact with an aqueous solution.

[0027] In embodiments, the combined water-responsive and pH-responsive safety layer comprises a nonmetallic salt. Specific nonmetallic salts include, but are not limited to, ammonium carbonate ((NH4)2CO3) and ammonium chloride (NH4Cl).

[0028] The composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer may optionally further comprise a reducing agent. As used herein, the term “reducing agent” generally refers to organic reducing agents, inorganic reducing agents, or particles of metal elements or metal alloys in their fully reduced state. The reducing agent can reduce soluble metal ions to conductive elemental metals even at a distance from the negative electrode without the application of a cell potential (i.e., electrolytic elution of the metal occurs). Electrolytic elution of the metal can lead to the formation of cross-linked dendrite portions as they grow in the composite water-responsive safety layer, establishing electronic connections between the battery electrodes and thereby facilitating a short circuit of the cell. Therefore, in one embodiment, the composite water-responsive safety layer may comprise a polymer material, a metal powder such as zinc powder, and a powdered metal salt contained therein, such as copper sulfate. In a dry state, the reaction between zinc and copper sulfate is prevented, and the safety layer is non-conductive. When exposed to a water-soluble environment, as in the case of accidental ingestion, copper can dissolve to produce copper ions, which are reduced by zinc metal to form copper dendrites, which grow and connect to adjacent dendrites, thereby creating conductive paths across the gaps between battery electrodes, resulting in a short circuit in the cell. Reducing agents may be used that include, but are not limited to, ascorbic acid or ascorbates, tocopherol, sodium borohydride, aluminum(0)(Al), calcium(0)(Ca), iron(0)(Fe), magnesium(0)(Mg), nickel(0)(Ni), tin(0)(Sn), titanium(0)(Ti), zinc(0)(Zn), and their alloys and combinations.

[0029] The combined water-responsive safety layer and / or the combined water-responsive and pH-responsive safety layer may optionally further comprise metal powder. As used herein, the term “metal powder” generally refers to particles of a metal element or metal alloy in its fully reduced state. The metal particles may have particle sizes ranging from about 0.1 μm to about 500 μm, for example, about 0.50 μm to about 100 μm, and / or about 1 μm to about 50 μm. The metal powder may remain in a reduced form within the water-responsive safety layer and / or the water-responsive and pH-responsive safety layer, where it may assist in the growth of bridging dendrite portions, thereby establishing electronic connections between battery electrodes and consequently facilitating short circuits in the cells. Elemental metals including but not limited to bismuth(O)(Bi), copper(O)(Cu), iron(O)(Fe), indium(O)(In), lead(O)(Pb), magnesium(O)(Mg), mercury(O)(Hg), nickel(O)(Ni), silver(O)(Ag), tin(O)(Sn), zinc(O)(Zn), and their alloys and combinations may be used. Furthermore, the metal powder is oxidizable by the positive electrode, thereby providing an ion source that can function as a sacrificial material for dendrite growth. The metal powder can also simultaneously function as a bridge and sacrificial material for dendrite growth. Thus, in further other embodiments, the composite water-responsive safety layer may contain the aforementioned polymer material and metal powder without substantially containing any metal salts.

[0030] The composite water-responsive safety layer may contain one or more polymers, one or more metal salts, and optionally one or more metal powders. Any combination of metal salts and metal powders may be included in combination with one or more polymers to obtain a composite water-responsive safety film. Any of the metal salts, polymers, and optional metal powders may be treated by various methods, including but not limited to ball milling, to reduce particle size. The combination of metal salts, polymers, and optional metal powders may be deposited to obtain a safety polymer layer comprising metal salts, polymers, and optional metal powders.

[0031] Generally, a combination of polymers, one or more metal salts, and optional metal powders may include a solvent to facilitate the process. Generally, the solvent is not limited. Suitable solvents include, but are not limited to, aliphatic solvents, aromatic solvents, and isoparaffinic solvents. Specific examples include, but are not limited to, acetone, ethyl acetate, toluene, xylene, terpineol, n-methyl-2-pyrrolidone, hexane, pentane, and diglyme. By utilizing a solvent, a composite water-responsive safety layer can be obtained using solvent casting methods such as spin casting. In addition, by utilizing a solvent, the composite water-responsive safety layer can be deposited using inkjet printing deposition and various known spraying methods. Other deposition methods may be used, including, but not limited to, direct ink writing (where the composition is extruded from a nozzle and applied directly to the battery, as described herein) and contact printing techniques such as flexographic printing, gravure printing, and pad printing. Furthermore, a technique may be used in which a composition for forming a composite water-responsive safety layer and / or a composite water-responsive and pH-responsive safety layer is deposited onto a substrate or backing and dried so that it can be applied directly to the battery surface (similar to applying a sticker) after transfer printing or removal of the composite water-responsive safety layer. The same solvent and method can be used to obtain the composite water-responsive and pH-responsive safety layer.

[0032] The battery surface may be activated by any suitable surface activation technique, such as a plasma treatment including but not limited to argon or corona treatment, a UV / ozone treatment, a flame treatment, an acid treatment, or a base treatment, but not limited to these. Such pre-deposition treatment may enhance the adhesion of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer to the battery surface. Adhesion promoters, particularly silane adhesion promoters, have been shown to enhance the adhesion of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer to the battery surface, especially after the surface has been activated using UV / ozone treatment. Typical adhesion promoters include dialkoxysilanes such as diethoxydimethylsilane, diethoxy(methyl)vinylsilane; 1,3-diethoxy-1,1,3,3-tetramethyldisiloxane; dimethoxydimethylsilane; dimethoxydimethylsilane; dimethoxymethylvinylsilane; and methyldiethoxysilane; monoalkoxysilanes such as ethoxytrimethylsilane and methoxytrimethylsilane; trialkoxysilanes such as 3-aminopropyl)triethoxysilane ("APTES"); (chloromethyl)triethoxysilane; triethoxy(ethyl)silane; triethoxymethylsilane; triethoxymethylsilane; triethoxy Examples include, but are not limited to, vinylsilanes; trimethoxymethylsilanes; trimethoxymethylsilanes; vinyltrimethoxysilanes; trihalosilanes such as vinyltrimethoxysilane and tert-butyltrichlorosilane; di-n-octyldichlorosilanes; hexachlorodisilanes; methyltrichlorosilanes; methyltrichlorosilanes; trichloro(dichloromethyl)silanes; trichlorovinylsilanes; bissilanes such as 1,2-bis(triethoxysilyl)ethane; 1,2-bis(trimethoxysilyl)ethane; 1,2-bis(trichlorosilyl)ethane; and bis(trichlorosilyl)methane; and combinations thereof.

[0033] The combined water-responsive safety layer and / or the combined water-responsive and pH-responsive safety layer may further comprise additives such as stabilizers, pologens, and / or pigments. Stabilizers may be used to maintain the rheology of the composition and prevent rapid settling of the composition. Typical stabilizers include dispersants such as polyurethane and polyacrylic dispersants available under the trademark names Efka® PU and Efka® PA (BASF Corporation), respectively; fumed metal oxide rheology additives, including but not limited to fumed silica and fumed alumina rheology additives available under the trademark names Aerosil® (Evonik) and CAB-O-SIL® (Cabot Corporation); and chelating agents such as sodium ethylenediaminetetraacetate. Of course, other metal oxide rheology additives may be used. Pologens may be used to promote wetting and adhesion. Typical pologens include, but are not limited to, ammonium chloride, ammonium carbonate, citric acid, water-soluble sugars (e.g., glucose, sucrose, fructose, etc.), polyethylene glycol, sodium chloride, and sodium acetate. Pigments may be used to produce the desired aesthetic effect and may be selected from pigments, dyes, and combinations thereof.

[0034] Polymer materials may be present in amounts of 5% to 90% by weight, for example 10% to 85% by weight, based on the weight of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer. Metal salts may be present in amounts of 5% to 95% by weight, for example 10% to 90% by weight, based on the weight of the composite water-responsive safety layer. Similarly, non-metallic salts may be present in amounts of 5% to 95% by weight, for example 10% to 90% by weight, based on the weight of the composite water-responsive and pH-responsive safety layer. Metal powders, if present, may be present in amounts of 5% to 95% by weight, for example 10% to 90% by weight, based on the weight of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer. Adhesion promoters, if present, may be present in amounts of 0.1% to 5% by weight, for example 0.25% to 2.0% by weight, based on the weight of the composite water-responsive safety layer and / or the composite water-responsive and pH-responsive safety layer. Rheological additives, if present, may be present in an amount of 0.1% to 7.5% by weight, for example 0.25% to 5.0% by weight, based on the weight of the combined water-responsive safety layer and / or the combined water-responsive and pH-responsive safety layer. Colorants, if present, may be present in an amount of 1% to 35% by weight, for example 2.5% to 30% by weight, based on the weight of the combined water-responsive safety layer and / or the combined water-responsive and pH-responsive safety layer.

[0035] The composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer is positioned over the gap between the positive and negative electrodes and generally has a thickness of 30 μm to 1000 μm, for example, 30 μm to 100 μm, 50 μm to 200 μm, 100 μm to 300 μm, 50 μm to 500 μm, and / or 100 μm to 1000 μm. Generally, the composite water-responsive safety layer and / or composite water-responsive and pH-responsive safety layer covers at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or nearly 100% of the outer circumference defined between the anode cup and the cathode can. Generally, the composite water-responsive layer and / or the composite water-responsive and pH-responsive safety layer are in contact with both a portion of the anode cup and a portion of the cathode can, but generally, contact with only one of the battery electrodes is sufficient, as will be explained in more detail below. In embodiments, the composite water-responsive layer and / or the composite water-responsive and pH-responsive safety layer have a width of 200 μm to 2000 μm (corresponding to the gap between the positive and negative electrodes in a coin cell).

[0036] Figures 2A and 2B show a battery 50, which may be any type of primary or secondary battery and in the illustrated example is a button cell type battery. The battery 50 includes a battery housing surrounding the battery, the housing includes a cathode can 54 and an anode cup 58, the cathode can 54 housing a cathode 52 within the housing, and the anode cup 58 housing an anode 56 within the housing, and the cathode 52 and anode 56 are electronically separated by a separator 60 in the cell 50. The cathode can 54 and anode cup 58 each form a different pole of the battery 50.

[0037] The cathode can 54 and anode cup 58 are separated by a separator 60 that extends over a lateral range of the cathode 52, for example substantially across the diameter of the battery 50. By electronically separating the can 54 and the cup 58, an insulating gasket 62 extends into the cathode can 54, thereby providing an insulating buffer surrounding the anode cup 58, which also seals the cell to prevent electrolyte loss.

[0038] As shown in the figure, the battery 50 further includes a composite water-responsive safety layer 64 surrounding at least a portion of the insulating gasket 62, the composite water-responsive safety layer 64 in contact with both a portion of the anode cup 58 and a portion of the cathode can 54. The composite water-responsive safety layer 64 is an electron short-circuit layer that changes the cell from an electron-nonconductive state corresponding to the normal operating state of the battery cell 10 to an electron-conductive state caused by exposure to a safe state, generally saliva, gastric juice, or other water-soluble fluid. For example, the safe state may be when a person or infant swallows the battery cell 50, or when the battery cell 50 is exposed to an aqueous solution in the form of saliva, gastric juice, or other water-soluble fluid. As will be further described herein, upon contact with an aqueous solution, the composite water-responsive safety layer 64 changes from an electron-nonconductive state to an electron-conductive state in response to contact with an aqueous solution such as saliva or gastric juice, water, or other water-soluble fluid.

[0039] In a typical example, the composite water-responsive safety layer 64 is formed by mixing polyethylene glycol (PEG), approximately 10% by weight of zinc (Zn) particles (approximately 20 mesh size), and approximately 10% by weight of copper sulfate (CuSO4) particles in a glass vial on a stirring plate maintained at approximately 50°C, and then depositing the composition on or around at least a portion of the insulating gasket 62. By covering at least a portion of the insulating gasket 62 with a composition containing metal oxide components, for example, when a person or infant swallows the battery cell 50, a reducible sacrificial material is favorably provided at the negative electrode, allowing a dendrite metal structure to grow under safe conditions and electrically connect the anode to the cathode, thereby exposing the battery cell 50 to an aqueous solution in the form of saliva, gastric juice, or other fluids, and consequently, the button cell short-circuits without significant electrolysis of water and the resulting generation of hydroxide ions and combustion of tissue. The composite water-responsive layer is shown to be in contact with both a portion of the anode cup 58 and a portion of the cathode can 54, but generally contact with only one of the battery electrodes is sufficient, for example, because the device may be provided with contact pads that help establish electronic contact between the dendrites of the composite water-responsive layer and the other battery electrode.

[0040] To evaluate the polymer matrix for use in the composite water-responsive safety layer relating to this disclosure, a two-lead test was performed as shown in Figure 3. A 50 μL sample of the sample material composition was deposited between two zinc wires (approximately 200 μm apart). The composition varies depending on the material to be tested. In the illustrated example, the composition comprises a polymer matrix containing polyethylene glycol (PEG), 10 wt% zinc particles (Zn powder), and 10 wt% copper sulfate, CuSO4 particles. To simulate a 3.0-volt rated CR2032 button cell lithium battery, the voltage source to the two zinc wires was set to 3V, and the current compliance was set to 30 mA (maximum current of the CR2032 battery). A 200 μL aliquot of a saliva substitute solution (specifically, 25% Ringer's solution) was deposited on the polymer matrix. The potential was monitored for up to 1 hour.

[0041] Figure 4 shows the results of several repeated tests on different CR2032 batteries, each with a composite water-responsive safety layer. Although each test was performed at a different start time, each test showed that the anode and cathode short-circuited, reducing the effective battery voltage from 3V to less than 1V in just 90 seconds.

[0042] Figure 5 shows another example of a battery cell 100 with a cathode can 102, an anode cup 104, and a polymer layer 106. To help suppress the occurrence of hydrogen bubbling during metal dendrite growth, which can hinder good metal dendrite growth when the cell is exposed to an aqueous solution, a composite water-responsive safety layer 106 is formed, as disclosed herein, by first plating the exposed anode cup 104 with a Zn layer 108, and then, for example, plating zinc metal dots onto the anode cup 104, thereafter optionally depositing one or more metal powders in combination over a composition comprising one or more polymer materials and one or more metal salts. The Zn layer 108 locally increases the hydrogen overpotential, thereby advantageously suppressing hydrogen bubbling at specific locations where the zinc layer is deposited. Alternatively, hydrogen bubbling can be suppressed and the formation of a metal dendrite short-circuit connection between the cathode can 102 and the anode cup 104 can be promoted by using other metal layers, either alone or in combination, that have a considerably higher hydrogen overpotential (compared to the hydrogen overpotential of the negative electrode material, generally Ni or stainless steel), including tin (Sn), indium (In), bismuth (Bi), lead (Pb), zinc (Zn), and mercury (Hg).

[0043] A composition comprising polyethylene glycol dissolved or suspended in acetone (having a weight-average molecular weight of 4000 g / mol), copper sulfate powder (a solid dissolved or suspended at 15% by weight in the slurry), and zinc metal dust (a solid dissolved or suspended at 15% by weight in the slurry) was heated on a hot plate to approximately 50°C and thoroughly mixed with a Teflon-coated magnetic stirring rod. A sample (15 μL) of this composition was pipetteed into positions around the clip edge 112 of half of battery 100 having a Zn layer 108.

[0044] Therefore, the composite water-responsive safety layer 106 may be formed as a substantially continuous layer around the battery surface of the anode cup 104, in particular, such that the composite water-responsive safety layer is positioned along the outer circumference of the anode cup 104, preferably in contact with the outer circumference of the anode cup 104, and along the outer circumference of the cathode can 102, preferably in contact with the outer circumference of the cathode can 102, or, more generally, it may be positioned between the first and second (e.g., positive and negative) battery electrodes, as shown via the upper end of the battery cell 100. In other examples, as shown via the bottom of the battery cell 100, the composite water-responsive safety layer 106 does not need to be continuous, but rather may be periodically positioned (e.g., deposited, layered, etc.), and may be deposited as discrete dots 110, for example, as shown in Figure 5.

[0045] Direct measurements of the voltage across battery 100 when the battery was immersed in a 25% Ringer aqueous solution were used to confirm a short circuit in an external battery cell. The results, as shown in Figure 6, indicated that a cell short circuit occurred and that metal dendrites grew to help the cell short circuit reduce the voltage of battery cell 100 to a non-threat value of less than 1V.

[0046] In the example shown in Figure 7, the composite water-responsive safety layer comprises approximately 12.5 wt% polyvinyl acetate (PVAc), approximately 4.16 wt% polyethylene oxide (PEO), approximately 8.33 wt% copper sulfate particles (CuSO4), and approximately 75 wt% basic copper carbonate particles (CuCO3·Cu(OH)2, also known as malachite). Preferably, as shown in Figure 7, the cell voltage decreases very rapidly and efficiently upon contact with the aqueous solution. The voltage drop is only observed for 20 minutes, but the voltage decreases further over time. In addition, cells having a composite water-responsive safety layer comprising the aforementioned mixture showed no change in cell voltage even after exposure to 90% relative humidity for at least 2 hours.

[0047] In the example shown in Figure 8, the composite water-responsive safety layer comprises approximately 16.75 wt% polyvinyl acetate (PVAc), approximately 6.25 wt% polyethylene oxide (PEO), approximately 12.5 wt% copper sulfate particles (CuSO4), and approximately 62.5 wt% basic copper carbonate particles (CuCO3·Cu(OH)2). Preferably, as shown in Figure 8, the voltage of the cell decreases very rapidly and efficiently upon contact with the aqueous solution. Although the voltage drop is only shown for 20 minutes in Figure 8, the voltage decreases further over time. In line with this, as can be seen in the table below, after 2 hours, the voltage of the cell with the aforementioned safety layer was well below 1.2V, and the pH was relatively neutral and therefore could not burn the tissue. [Table 1] In addition, the cell having a composite water-responsive safety layer comprising the aforementioned mixture showed no change in cell voltage even after being exposed to 90% relative humidity for at least two hours.

[0048] In the example shown in Figure 9, the composite water-responsive safety layer comprises approximately 16.67 wt% polyvinyl acetate (PVAc 500K, polyvinyl acetate with a weight-average molecular weight of approximately 500,000), approximately 41.67 wt% copper sulfate particles (CuSO4), and approximately 41.67 wt% basic copper carbonate particles (CuCO3·Cu(OH)2). Generally, approximately 400 mg of polyvinyl acetate is dissolved in approximately 1 mL of xylene, to which approximately 1 g of ball-milled CuSO4 and 1 g of ball-milled CuCO3·Cu(OH)2 are added. The composition is filled into a syringe, and after being allowed to equilibrate at room temperature, it is deposited on the cell in the gap between the first and second battery electrodes. After deposition, the composition is allowed to dry in air (approximately 24 hours). Preferably, as shown in Figure 9, the cell voltage decreases very rapidly and efficiently upon contact with the aqueous solution. In fact, in these cells, the voltage drops to below 1.2V in less than 400 seconds.

[0049] In other specific examples, the composite water-responsive safety layer comprises approximately 22 wt% PEG 6K (polyethylene glycol with a weight-average molecular weight of approximately 6,000), approximately 2 wt% PMMA 75K (polymethyl methacrylate with a weight-average molecular weight of approximately 75,000), approximately 38 wt% zinc particles (Zn powder), and approximately 38 wt% copper sulfate (CuSO4) particles. Generally, the polymer components are dissolved in acetone, to which the zinc particles and ball-milled CuSO4 are added. The viscosity of the formulation was adjusted with terpineol. Using a nozzle tool, the formulation is deposited along the outer circumference of the anode cup in contact with the outer circumference of the anode cup, and along the outer circumference of the cathode can in contact with the outer circumference of the cathode can, thereby forming the composite water-responsive safety layer in the gap between the first and second battery electrodes. Xylene can also be used instead of acetone, and xylene is preferred for aerosol and microdispensing (such as inkjet printing) deposition.

[0050] In further specific examples, the composite water-responsive safety layer comprises approximately 17 wt% PVAc 100K (polyvinyl acetate with a weight-average molecular weight of approximately 100,000), approximately 41.5 wt% zinc particles (Zn powder), and approximately 41.5 wt% copper sulfate CuSO4 particles. Generally, the polymer is dissolved in xylene at approximately 60°C, to which the zinc particles and ball-milled CuSO4 are added. The formulation is deposited by aerosol printing using an airbrush. Masking is used to facilitate deposition, and thus the composite water-responsive safety layer is formed in the gap between the first and second battery electrodes.

[0051] In further specific examples, the composite water-responsive safety layer comprises approximately 29 wt% PVAc 100K (polyvinyl acetate with a weight-average molecular weight of approximately 100,000) and approximately 71 wt% copper sulfate CuSO4 particles. Generally, the polymer is dissolved in xylene at approximately 50°C, to which ball-milled CuSO4 and a colorant, specifically phthalocyanine blue BN pigment, are added. The formulation is deposited in the gap between the first and second battery electrodes by direct writing / extrusion using a nozzle tool.

[0052] In further specific additional examples, composite water-responsive safety layers were prepared from an ink composition comprising approximately 1 g of PVAc 500K (polyvinyl acetate with a weight-average molecular weight of approximately 500,000), approximately 2.5 g of copper sulfate (CuSO4), particles, and approximately 2.5 g of basic copper carbonate particles (CuCO3·Cu(OH)2). Generally, polyvinyl acetate was dissolved in approximately 5 mL of xylene at approximately 70°C and approximately 50 or approximately 100 mg of fumed silica rheology additive CAB-O-SIL-EH-5, after which ball-milled CuSO4 and CuCO3·Cu(OH)2 were added to form the ink formulation. The formulation was deposited in the gap between the first and second battery electrodes by direct writing printing using a nozzle with a tip diameter of approximately 0.41 mm. Formulations with higher concentrations of fumed silica rheology additive showed higher resolution.

[0053] Further examples A-D were prepared according to Table 2. [Table 2]

[0054] All reagents can be used as received without further processing or purification. However, to impart the desired rheological and anti-sedimentation properties to the formulation, basic copper carbonate was first dispersed in a solvent (acetone) and then wet-ball-milled for 2 hours (Retsch Mixer Mill MM200, Retsch GmbH) to reduce the particle size to approximately 1-30 μm. After filtering the resulting slurry, the solid was placed in a container and dried (in air or under vacuum). Copper sulfate was dry-ball-milled for 30 minutes. Copper sulfate and (3-aminopropyl)triethoxysilane were stored in a desiccator until use.

[0055] In 20 mL glass vials with Teflon-coated magnetic micro-stirring rods, 200 mg of PVAc (500 kD) was dissolved in 2 mL of toluene for each example A and D, with continuous stirring on a magnetic stirring plate. When the PVAc was completely dissolved (up to 1 hour), basic copper carbonate (500 mg), copper sulfate (500 mg), colorants (200 mg carbon black, 100 mg super copper, and 400 mg Titan black in each of Examples A, B, and D; Example C contains no further pigments), and Aerosil-200 (30 mg) were added and mixed for 5–10 minutes to produce a uniformly dispersed slurry. When stored in a desiccator or other moisture-free environment, the mixtures remained stable for at least one week. If precipitation occurred, vigorous stirring / mixing was sufficient to redisperse the solid components in the mixture.

[0056] The surface was cleaned and activated to enhance adhesion. The received cells were cleaned and activated using UV / ozone treatment for several minutes. Sufficient activation was confirmed when a drop of deionized water easily wetted the activated surface and the contact angle was less than 10 degrees. The activated surface was coated with a mixture of components to resuspend all components as soon as possible after activation (within 1 hour for best results) (5-10 minutes). APTES was added to the (otherwise complete) mixture shortly before deposition, and the mixture was stirred for a further 5 minutes. Typical deposition volume was 10-15 μL, and less than 20 μL. The mixture was deposited by hand or by extruding it through the gap between the first and second battery electrodes using a nozzle tool.

[0057] Measurements performed using a rheometer showed that the coating exhibited low shear (0.001 s). -1 It is a gel at a shear rate of >1,000,000 Pa·s and also under high shear (100s) -1 It was shown to be a viscous liquid at a shear rate of 1,000 Pa·s.

[0058] The battery with the composite safety membrane according to Example A was evaluated for passivation performance and moisture resistance at 70% relative humidity (40°C). The composite water-responsive safety membrane preferably demonstrated that there was no change in cell voltage even after exposure to 70% relative humidity for more than 16 days. Furthermore, the cell voltage decreased upon contact with the aqueous solution, resulting in the voltage of the cell with the aforementioned safety layer falling well below 1.2V after 2 hours, actually becoming less than 0.1V, with a neutral pH, and therefore unable to burn tissue.

[0059] Throughout this specification, multiple examples may implement components or structures described as single examples. Structures and functions given as separate components in some examples may be implemented as combined structures or components. Similarly, structures and functions given as single components may be implemented as separate components. These and other variations, modifications, additions, and improvements are within the scope of the subject matter of this specification.

[0060] Any reference to “one embodiment” or “one embodiment” used herein means that the specific elements, features, structures, or characteristics described in relation to that embodiment are included in at least one embodiment. The phrase “in one embodiment” appearing in various places herein does not necessarily refer to the same embodiment.

[0061] As used herein, the terms “equipped,” “possessing,” “included,” “contained,” “having,” “possessing,” or any other variation thereof are intended to encompass non-exclusive inclusion. For example, a process, method, article, or apparatus containing a list of elements is not necessarily limited to those elements alone, and may include other elements not expressly listed or specific to such process, method, article, or apparatus. Furthermore, unless the opposite is expressly stated, “or” means an inclusive “or” and not an exclusive “or.” For example, element A or B is satisfied by any one of the following: A exists and B does not; A does not exist and B exists; and both A and B exist.

[0062] Furthermore, the use of “one (a)” or “one (an)” is used to describe the elements and components of the embodiments herein. This is done solely for convenience and to give a general meaning to the description. This description and the following claims should be read as including one or at least one, and singular forms also include plural forms unless it becomes clear that it means something else.

[0063] Since it is impractical, if not impossible, to describe all possible embodiments, the detailed description should be interpreted as an example and does not describe all possible embodiments. Numerous alternative embodiments can be carried out using either the current art or art developed after the filing date of this application.

Claims

1. It is a battery, A housing comprising a first pole and a second pole, A composite water-responsive safety layer comprising a polymer material and positioned adjacent to at least one of the first electrode and the second electrode, wherein the composite water-responsive safety layer changes from an electron-nonconductive state to an electron-conductive state upon contact with an aqueous solution, and the composite water-responsive safety layer further comprises at least one metal salt, Equipped with, The composite water-responsive safety layer is arranged to be exposed to the aqueous solution when in contact with the aqueous solution, in a battery.

2. The battery according to claim 1, wherein the polymer material comprises polyethylene glycol, polyethylene oxide, polyacrylic acid, polyacrylate, polyvinyl alcohol and modified polyvinyl alcohol, water-soluble acrylate copolymer, polyvinyl ester, polyvinylpyrrolidone, pullulan, gelatin, hydroxypropyl methylcellulose (HPMC), low viscosity grade hydroxypropylcellulose, polysaccharides, water-soluble natural polymer, modified starch, copolymers of the above, or combinations of the above.

3. The battery according to claim 1, wherein the polymer material is a biologically inert material.

4. The battery according to claim 1, wherein the composite water-responsive safety layer further comprises unoxidized metal powder.

5. The battery according to claim 4, wherein the metal powder comprises one or more metal powders selected from the group consisting of bismuth (0) (Bi), copper (0) (Cu), iron (0) (Fe), indium (0) (In), lead (0) (Pb), nickel (0) (Ni), magnesium (0) (Mg), mercury (0) (Hg), silver (0) (Ag), tin (0) (Sn), zinc (0) (Zn), alloys thereof, and any combination thereof.

6. The battery according to claim 1, further comprising a metal layer in contact with the outer surface of at least one of the electrodes.

7. The battery according to claim 1, wherein a metal layer is in contact with the negative electrode (corresponding to the anode of the battery) and comprises a metal selected from the group consisting of bismuth(0)(Bi), indium(0)(In), lead(0)(Pb), mercury(0)(Hg), tin(0)(Sn), zinc(0)(Zn), alloys thereof, and any combination thereof.

8. The composite water-responsive safety layer comprises a polymer selected from polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and any combination thereof, wherein the metal salt is copper sulfate (CuSO4). ４ The battery according to claim 1, including ).

9. The battery according to claim 8, wherein the composite water-responsive safety layer further comprises zinc (Zn) particles.

10. The battery according to claim 8, wherein the copper sulfate is present in an amount of at least 5% by weight based on the total weight of the composite water-responsive safety layer.

11. The battery according to claim 1, wherein the positive electrode is electronically separated from the negative electrode by an insulating gasket, the composite water-responsive safety layer is located adjacent to the insulating gasket, and the composite water-responsive safety layer extends between the positive electrode (corresponding to the cathode of the battery) and the negative electrode (corresponding to the anode of the battery) and contacts both the positive electrode and the negative electrode.

12. The battery according to claim 11, wherein the composite water-responsive safety layer extends continuously between the positive electrode and the negative electrode, and over the outer circumference of at least one of the positive electrode and the negative electrode.

13. The battery according to claim 11, wherein the composite water-responsive safety layer extends between the positive electrode and the negative electrode, and over a portion of the outer circumference of at least one of the positive electrode and the negative electrode.

14. The battery according to claim 1, wherein the battery is selected from AAAA, AAA battery, AA battery, B battery, C battery, D battery, 9V battery, CR2 battery, CR123A battery, 1 / 3N battery, button cell, and coin cell.

15. Said metal salt is Cu +2 , Fe +2 , Hg +2 , Ni +2 , Ag + , Zn +2 , Bi +3 , In +3 , Pb +2 , and Sn +2 The battery according to claim 1, comprising a cation selected from one or more of the group of

16. The aforementioned metal salts include acetate, adipine, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bicarbonate, bisulfate, tartrate, borate, bromide, butyrate, camphorate, camphor sulfonate, carbonate, chloride, citrate, cyclopentanepropionate, digluconate, dihydrochloride, diphosphate, dodecyl sulfate, edetate, ethanesulfonate, fumarate, glucoheptone, glucomate, glutamate, glycerophosphate, hemisulfate, heptate, hexanoate, hydrobromide, hydrochloride, hydroiodide, hydroxide, hydroxyethanesulfonate, hydroxynaphthoate, iodide, lactate, lactobionic acid, and lauric acid. The battery according to claim 1, comprising one or more anions selected from the group consisting of nitrates, laurates, maleates, malons, mandelates, mesylates, methanesulfons, methyl bromides, methylnitrates, methyl sulfates, mucates, 2-naphthalenesulfons, nicotinates, nitrates, oleates, oxalates, palmitates, pamoates, pectinates, persulfates, 3-phenylpropionates, phosphates, piclates, pivalates, polygalacturonates, propions, salicylates, stearates, acetates, succinates, sulfates, tannates, tartrates, theophyllineates, thiocyanates, triethioides, toluenesulfonates, undecanoic acid, and valerates.

17. The battery according to claim 1, wherein the metal salt comprises one or more metal salts selected from the group consisting of bismuth carbonate, bismuth chloride, bismuth sulfate, bismuth nitrate, bismuth subsalicylate, bismuth oxide, copper carbonate, copper chloride, copper sulfate, copper oxalate, copper hydroxide, iron carbonate, iron chloride, iron sulfate, indium carbonate, indium chloride, indium sulfate, lead carbonate, lead chloride, lead sulfate, mercury carbonate, mercury chloride, mercury sulfate, nickel carbonate, nickel chloride, nickel sulfate, silver carbonate, silver chloride, silver sulfate, tin carbonate, tin chloride, tin sulfate, zinc carbonate, zinc chloride, zinc sulfate, hydrates thereof, and basic salts thereof.

18. It is a method, The steps include: preparing a battery housing having a first pole and a second pole; A step of forming a composite water-responsive safety layer between the first and second electrodes of a battery housing by depositing the composition between the electrodes such that the composition is located adjacent to at least one of the first and second electrodes, wherein the composition comprises a polymer material and at least one metal salt, the composite water-responsive safety layer changes from an electron-nonconducting state to an electron-conducting state upon contact with an aqueous solution, and the composite water-responsive safety layer is arranged to be exposed to the aqueous solution upon contact with the aqueous solution, A method that includes [something].

19. The method according to claim 18, wherein the polymer material comprises polyethylene glycol, polyethylene oxide, polyacrylic acid, polyacrylate, polyvinyl alcohol and modified polyvinyl alcohol, water-soluble acrylate copolymer, polyvinylpyrrolidone, polyvinyl ester, pullulan, gelatin, hydroxypropyl methylcellulose (HPMC), low viscosity grade hydroxypropylcellulose, polysaccharides, water-soluble natural polymers, modified starch, copolymers of the above, or combinations of the above.

20. The aforementioned metal salt is Cu +2 Fe +2 Hg +2 , Ni +2 Ag + , Zn +2 , Bi +3 In +3 , Pb +2 , and Sn +2 The method according to claim 18, comprising one or more cations selected from the group.

21. The aforementioned metal salts include acetate, adipine, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bicarbonate, bisulfate, tartrate, borate, bromide, butyrate, camphorate, camphor sulfonate, carbonate, chloride, citrate, cyclopentanepropionate, digluconate, dihydrochloride, diphosphate, dodecyl sulfate, edetate, ethanesulfonate, fumarate, glucoheptone, glucomate, glutamate, glycerophosphate, hemisulfate, heptate, hexanoate, hydrobromide, hydrochloride, hydroiodide, hydroxide, hydroxyethanesulfonate, hydroxynaphthoate, iodide, lactate, lactobionic acid, and lauric acid. The method according to claim 18, comprising one or more anions selected from the group consisting of phosphate, laurate, maleate, malonate, mandelate, mesylate, methanesulfonate, methyl bromide, methylnitrate, methyl sulfate, mucate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, piclate, pivalate, polygalacturonate, propionate, salicylate, stearate, acetate, succinate, sulfate, tanate, tartrate, theophylline, thiocyanate, triethiodide, toluenesulfonate, undecanoic acid, and valerate.

22. The method according to claim 18, wherein the metal salt comprises one or more metal salts selected from the group consisting of bismuth carbonate, bismuth chloride, bismuth sulfate, bismuth nitrate, bismuth subsalicylate, bismuth oxide, copper carbonate, copper chloride, copper sulfate, copper oxalate, copper hydroxide, iron carbonate, iron chloride, iron sulfate, indium carbonate, indium chloride, indium sulfate, lead carbonate, lead chloride, lead sulfate, mercury carbonate, mercury chloride, mercury sulfate, nickel carbonate, nickel chloride, nickel sulfate, silver carbonate, silver chloride, silver sulfate, tin carbonate, tin chloride, tin sulfate, zinc carbonate, zinc chloride, zinc sulfate, hydrates thereof, and basic salts thereof.

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