Batteries that Deactivate in a Conductive Aqueous Medium and Methods of Making The Same
20220311109 · 2022-09-29
Assignee
Inventors
- Bryan Laulicht (Danbury, CT, US)
- Jonah Myerberg (Lexington, MA, US)
- Ravikumar Vasudevan (Fairfield, CT, US)
- Zachary A. Kelly (Middletown, CT, US)
- Jeff M. Karp (Brookline, MA, US)
- Robert Langer (Newton, MA)
Cpc classification
H01M50/574
ELECTRICITY
International classification
H01M50/574
ELECTRICITY
H01M50/198
ELECTRICITY
Abstract
The present disclosure provides batteries that have a reduced risk or no risk of gastrointestinal damage in a conductive aqueous environment, such as when accidentally swallowed. The batteries of the present disclosure advantageously stop producing significant current flow shortly after contact with a conductive aqueous medium, including the conductive aqueous medium of a wet tissue environment such as that found in the GI tract. The present disclosure further provides multi-layered laminate materials useful for manufacturing such batteries and methods for making the batteries. The batteries are, in some embodiments, 3 V or 1.5 V coin or button cell-type batteries.
Claims
1. A battery comprising: an anode case; a cathode case comprising an inner conductive layer, an outer conductive layer, and an insulating layer between the inner and the outer conductive layers, an electrochemical cell comprising an anode, a cathode, and a separator positioned between the anode and the cathode; and a gasket between the anode case and the cathode case; wherein the inner and the outer conductive layers are in electrical contact through at least one bridge.
2.-131. (canceled)
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DESCRIPTION OF CERTAIN EMBODIMENTS
[0206] As used herein, the term about refers to a numeric value, including, for example, whole numbers, fractions, and percentages, whether or not explicitly indicated. The term about generally refers to a range of numerical values (e.g., +/−5-10% of the recited range) that one of ordinary skill in the art would consider equivalent to the recited value (e.g., having the same function or result). When terms such as at least and about precede a list of numerical values or ranges, the terms modify all of the values or ranges provided in the list. In some instances, the term about may include numerical values that are rounded to the nearest significant figure.
[0207] As used here, “a” or “an” means “at least one” or “one or more” unless otherwise specified. As used herein, the term “or” means “and/or” unless specified otherwise. In the context of a multiple depending claim, the use of “or” when referring back to other claims refers to those claims in the alternative only.
I. Exemplary Batteries
[0208] The present disclosure provides batteries that are safer and less likely to damage tissue when ingested, for example when a child or pet accidentally swallows the battery. The present disclosure pertains to any battery, and in particular embodiments, the present disclosure provides a coin or button cell-type battery, such as a 3 volt or a 1.5 volt button cell battery.
[0209] Exemplary battery 200 comprises:
[0210] an anode case 201;
[0211] a cathode case 202, the cathode case comprising an inner conductive layer 203, an outer conductive layer 204, and an insulating layer 205 between the inner and the outer conductive layers,
[0212] an electrochemical cell comprising an anode 206, a cathode 207, and a separator 208 between the anode and the cathode; and
[0213] a gasket 209 between the anode case and the cathode case;
[0214] wherein the inner and the outer conductive layers are in electrical contact through at least one bridge 210.
[0215] In some embodiments, after contact of the at least one bridge with a conductive aqueous medium, the electrical contact between the inner conductive layer and the outer conductive layer through the at least one bridge is reduced or severed.
[0216]
[0217] While not being bound by theory, the present batteries are safer upon accidental ingestion because the current flow between the anode and cathode is interrupted in a relatively short period of time, thereby preventing the formation of a caustic local environment around the battery that can cause tissue damage. When at least one bridge and the anode case are in contact with a conductive aqueous medium, a transient conductive pathway can form between the anode and cathode, thereby allowing current to flow. In the presence of this current, the bridge undergoes electrochemical oxidation. Electrochemical oxidation of the bridge reduces its conductivity or severs it thereby reducing or severing the electrical connection between the inner and outer conductive layers, effectively limiting the conductive pathway and the resulting current over a relatively short period of time, such as within two hours, one hour, 30 minutes, 20 minutes, 10 minutes or 5 minutes.
[0218] In one embodiment, oxidation of a bridge results in electrochemical dissolution of the bridge material, such as dissolution of metal ions into the conductive aqueous medium. In another embodiment, oxidation of the bridge results in formation of an oxide on the bridge. The oxide effectively insulates the bridge such that the electrical connection is reduced.
[0219] After the battery has been exposed to a conductive aqueous solution and the bridge has been oxidized to deactivate the battery, the battery cannot be easily discharged to exhaust the energy in the cell by conventional means. As depicted in
[0220] The term “bridge” as used herein refers to a connection or link between inner and outer conductive layers that are separated by an insulating layer. The bridge provides an electrical contact between the inner and outer conductive layers. The bridge may comprise a conductive material that is the same as or different from the inner and/or outer conductive layer materials. In certain embodiments, the bridge comprises at least one extension of the inner conductive layer and/or the outer conductive layer. The extension may be one or more projections extending radially outward from a conductive layer, or the extension may be a single annular ring. In other embodiments, the bridge may comprise a wire, strip, or sheet of a conductive material that is soldered or otherwise affixed to the inner and outer conductive layers such that the electric connection is established. In some embodiments, the at least one bridge comprises a material that is capable of electrochemical oxidation when at least one part of the bridge is exposed to a conductive aqueous medium. For example, the at least one bridge comprises a material that is capable of electrochemical oxidation when a transient conductive pathway is formed between the anode and the cathode through a conductive aqueous medium.
[0221] The “electrical contact” provided by a bridge has a low resistance such that a current can flow. In one embodiment, the electrical contact may be measured by determining the electrical resistance between the inner and the outer conductive layers. In one embodiment, the electrical resistance between the inner and the outer conductive layers is less than about 1 ohm, from about 0.01 ohms to about 1 ohm, from about 1 ohm to about 10 ohms, or from about 10 ohms to about 100 ohms prior to the contact with a conductive aqueous medium. In another embodiment, the electrical contact is measured by determining the electrical conductivity between the inner and the outer conductive layers through the at least one bridge in a dry environment, for example, prior to contact with a conductive aqueous medium. Electrical conductivity can be determined by measuring the resistance, current, and/or voltage.
[0222] In some embodiments, electrical contact comprises an inner conductive layer, a bridge, and an outer conductive layer in physical contact through coating, pressing, crimping, stamping, pinching, soldering, welding, and/or the use of adhesives. In other embodiments, electrical contact comprises at least two conductive surfaces in close proximity allowing for quantum tunneling between the inner conductive layer and the bridge, between the bridge and outer conductive layer, or between the inner conductive layer and the bridge in addition to the bridge and outer conductive layer. In another embodiment, a quantum tunneling composite is used to make electrical contact.
[0223] The electrical contact is reduced or severed after contact with a conductive aqueous medium within a relatively short period of time. Once the electrical contact is reduced or severed, the current flow is such that the formation of hydroxide ions is greatly reduced or ceases, and a high pH, caustic environment is not formed. The reduction or severance of the electrical contact may be determined by measuring the resistance, the current, and/or the battery voltage. In some embodiments, the electrical contact is reduced or severed within about 60 minutes or less, about 30 minutes or less, about 20 minutes or less, or about 10 minutes or less. Because the electrical contact is reduced relatively quickly, the damage caused in vivo may be significantly reduced.
[0224] In some embodiments, the resistance between the inner and outer conductive layers increases to greater than about 500 ohms, greater than about 50 kohms, or greater than about 500 kohms after contact with a conductive aqueous medium. In other embodiments, the resistance increases such that the voltage of the battery, after drying, is 1.23 V or less.
[0225] The battery is considered dry when the battery is removed from and is no longer in contact with an aqueous medium (conductive or non-conductive) for at least about 24 hours and is, for example, placed in a desiccator during those 24 hours.
[0226] Open circuit voltage (OCV) is the difference of electrical potential between two terminals of a device when disconnected from any circuit, also known as an open circuit. Closed circuit voltage (CCV) is the difference of electrical potential between two terminals of a device when connected in a circuit. CCV measurements may also be indicated by specifying the resistor used in series in the circuit along with the duration of time. Examples of some CCV measurements disclosed herein use about a 15 kohm resistor, about a 3.9 kohm resistor, or about a 1 kohm resistor. Examples of time durations used to measure CCV disclosed herein are about 1 sec, about 3 sec, or about 5 sec after closing the circuit. The measurement of OCV and CCV of the battery are known in the art.
[0227] In some embodiments, after the contact with a conductive aqueous environment, the OCV of the exemplary battery is less than about 1.23 V, is less than about 1.2 V, or is less than about 1 V after about a 5 second measurement.
[0228] In further embodiments, after the contact with a conductive aqueous environment, the CCV of the exemplary battery is less than about 1.23 V, is less than about 1.2 V, or is less than about 1 V after about a 1 second to about a 5 second measurement when in series with about a 15 kohm resistor, about a 3.9 kohm resistor, or about a 1 kohm resistor.
[0229] In other embodiments, after the contact with a conductive aqueous environment, the current between the inner conductive layer and the outer conductive layer is less than about 0.1 mA, less than about 0.01 mA, or less than about 1 ρA.
[0230] “Reduced” means a reduction relative to a reference. In some embodiments, by “reduced” is meant the reduction of about 5% or more, of about 10% or more, of about 20% or more, of about 30% or more, of about 40% or more, of about 50% or more, of about 60% or more, of about 70% or more, of about 80% or more, of about 90% or more, of about 100% or more, of about 200% or more, of about 500% or more, or of about 1000% or more relative to a reference value. In some embodiments, by “reduced” is meant the reduction of about 5% to about 50%, of about 10% to about 20%, of about 50% to about 100%. In some embodiments, the reduction may be in reference to the electrical contact, current, or voltage of the battery prior to contact with a conductive aqueous medium.
[0231] “Electrical contact is severed” means the electrical connection between two components is broken and the electrical circuit is an open circuit.
[0232] “Increased” means an increase relative to a reference. In some embodiments, by “increased” is meant an increase of about 5% or more, of about 10% or more, of about 20% or more, of about 30% a or more, of about 40% or more, of about 50% or more, of about 60% or more, of about 70% or more, of about 80% or more, of about 90% or more, of about 100% or more, of about 200% or more, of about 1000% or more, of about 10,000%, and/or of about 100,000% relative to a reference value. In some embodiments, by “increased” is meant an increase of about 5% to about 100%, of about 100% to about 10,000%, of about 10,000% to about 1,000,000%. In some embodiments, the increase may be in reference to the resistance between the inner and outer conductive layers prior to the contact with the conductive aqueous medium.
[0233] Several embodiments of the bridge are possible. For example, a bridge may be formed from an extension or protrusion of the inner conductive layer such that the bridge is in electrical contact (e.g., in physical contact) with the outer conductive layer. Alternatively, a bridge may comprise a portion of the outer conductive layer such that the bridge is in electrical contact (e.g., in physical contact) with the inner conductive layer.
[0234] The bridge may comprise a material that is the same as or different from the inner and outer conductive layers. In certain embodiments, the bridge comprises a material that oxidizes more rapidly than the inner or outer conductive layers. The oxidation rate of the bridge will depend on the specific material, the texture of the material, and/or the thickness of the material used to form the bridge.
[0235] In some embodiments, the at least one bridge comprises a plurality of extensions, each extension comprising:
[0236] a) a portion of the inner conductive layer extending over the insulating layer to electrically contact the outer conductive layer along the rim of the cathode case, or
[0237] b) a portion of the outer conductive layer extending over the insulating layer to electrically contact the inner conductive layer along the rim of the cathode case, or
[0238] c) a combination of a) and b).
[0239]
[0240] In certain embodiments, the at least one bridge comprises at least one seam along the rim of the cathode case, the at least one seam comprising:
[0241] a) the inner conductive layer extending over the insulating layer to electrically contact the outer conductive layer at the rim of the cathode case, or
[0242] b) the outer conductive layer extending over the insulating layer to electrically contact the inner conductive layer at the rim of the cathode case, or
[0243] c) a combination of a) and b).
[0244] The seam can be created through crimping, stamping, pinching, soldering, welding, and/or adhesives.
[0245] A “conductive aqueous medium” as used herein includes without limitation conductive water-containing solutions, such as aqueous salt solutions and aqueous buffered solutions; bodily fluids, such as digestive fluids, saliva, mucous, wet tissue, and blood; aqueous gels; and the like. The resistivity of a conductive aqueous medium is 1 Mohm-cm or less.
[0246] A “non-conductive aqueous medium” as used here in refers to purified or deionized water or to solutions of water including nonionic cleaning detergents where the solution has a resistivity of more than 1 Mohm-cm.
[0247] A “conductive pathway” as used herein includes without limitation a path where charge can flow to complete a circuit between the anode and cathode of a battery. The anode case and the bridge, for example, form a conductive pathway when both are in contact with a conductive aqueous medium. Electrolysis of water is one indicator of the presence of a conductive pathway. One indicator of electrolysis may be the presence of bubbling from the anode when the battery is in contact with the conductive aqueous medium. Alternatively, an increase in pH near the anode terminal may indicate the presence of a conductive pathway.
[0248] Anode and cathode materials can be chosen from any known in the battery art. The anode case provides a protective barrier for the anode, and generally comprises a conductive material. Suitable materials for the anode case are known to those in the art. The separator generally provides physical separation between the anode and the cathode and can be made from any materials known in the art. Additionally, an electrolyte may be included in the battery, as well understood in the art.
[0249] A gasket is advantageously between the anode case and the cathode case and may provide a seal between the anode and cathode. The gasket may comprise a non-conductive material, such as an elastomeric material or a plastic. Non-conductive materials include, without limitation, nylon, polytetrafluoroethylene, fluorinated ethylene-propylene, chlorotrifluoroethylene, perfluoroalkoxy polymer, polyvinyls, polyethylene, polyethylene terephthalate, polypropylene, polystyrene, polysulfone, silicone rubbers, and the like.
II. Exemplary Cathode Case
[0250] A. Exemplary Cathode Case Structure
[0251]
[0252]
[0253] As seen in
[0254]
[0255]
[0256] In yet another embodiment, depicted in
[0257] In another embodiment, depicted in
[0258] In another embodiment, depicted in
[0259] A bridge may be formed in any manner available to those skilled in the art, in addition to the crimping process described above. For example, the bridge can be stamped, ultrasonically welded, laser welded, sputtered, physical vapor deposited, plated, soldered, brazened, thermoformed, printed with conductive ink or otherwise affixed to the inner conductive layer and/or the outer conductive layer.
[0260] In still further embodiments, the insulating layer in the cathode case further comprises: a) a multilayered construction comprising an adhesive layer in contact with the outer conductive layer, b) a multilayered construction comprising an adhesive layer in contact with the inner conductive layer, or c) both a) and b).
[0261] An adhesive useful in this embodiment includes, without limitation, a pressure-sensitive adhesive, a rubber-based adhesive, an epoxy, a polyurethane, a silicone adhesive, a phenolic resin, a UV curable adhesive, an acrylate adhesive, or any combination of two or more thereof.
[0262] B. Exemplary Cathode Case Materials
[0263] The cathode case components may comprise a variety of materials known to those in the art. Suitable materials for the inner conductive layer include, without limitation, conductive metals. In certain embodiments, the inner conductive layer comprises aluminum, stainless steel, chromium, tungsten, gold, vanadium, nickel, titanium, tantalum, silver, an alloy thereof, or a combination of any two or more thereof. In a particular embodiment, the inner conductive layer comprises aluminum or an aluminum alloy.
[0264] The outer conductive layer also may comprise a conductive metal. Exemplary metals useful for the outer conductive layer include, without limitation, stainless steel, nickel, gold, aluminum, titanium, an alloy thereof, or a combination of any two or more thereof. In a particular embodiment, the outer conductive layer comprises stainless steel.
[0265] Stainless steel is an alloy and is commercially available in a variety of forms. Stainless steel useful for the outer conductive layer includes, without limitation, SS304, SS316, SS430, duplex 2205, duplex 2304, duplex 2507, or one or more other stainless steels with a chromium content equal to or greater than 10% by weight and/or a nickel content equal to or greater than 0.1%. by weight.
[0266] In addition to conductive metals, the inner conductive layer and outer conductive layer may comprise conductive composites. In one embodiment, conductive particles are embedded in a non-conductive medium to form an overall conductive film that is coated onto the cathode case as the inner conductive layer and/or the outer conductive layer. In another embodiment, conductive carbon black, carbon nanotubes, graphene, graphite, and/or carbon fibers are used as the conductive particles in a conductive composite film.
[0267] The insulating layer can be any insulating material known in the art. In some embodiments, the insulating layer has a breakdown voltage that is greater than the open circuit voltage of the battery.
[0268] The “breakdown voltage,” as used herein, is the minimum voltage that causes a portion of an insulator to become electrically conductive. In certain embodiments, the breakdown voltage of the insulating layer is greater than 3.3 volts. Useful materials for the insulating layer include, without limitation, a hydrophobic polymer, a natural rubber, a cellulose acetate, a paper dielectric, a ceramic, a metal oxide, a nitride, a carbide, or a combination of any two or more thereof.
[0269] A hydrophobic polymer includes, without limitation, a polyethylene terephthalate, a polytetrafluoroethylene, a fluorinated ethylene propylene, a perfluoroalkoxyalkane, a polyvinyl fluoride, a polyvinylidine difluoride, a polypropylene, a polyurethane, a polyimide, a dimethylpolysiloxane, or a combination of any two or more thereof. In some embodiments, the insulating layer comprises polyethylene terephthalate.
[0270] Metal oxides useful for the insulating layer include, without limitation, silicon dioxide, aluminum oxide, nickel oxide, chromium oxide, or a combination of any two or more thereof.
[0271] In one embodiment, the insulating layer comprises a cup-shaped thermoform. A cup-shaped thermoform may comprise a thermoplastic, including without limitation polyphenylene sulfide and/or a fluoropolymer (including polyvinylidene difluoride, polytetrafluoroethylene, perfluoroalkoxyalkane polymer, fluorinated ethylene propylene, and any combination thereof).
[0272] In another embodiment, the cup-shaped thermoform comprises a thermoplastic elastomer, including without limitation, a thermoplastic polyurethane, a thermoplastic polyolefin, or a combination thereof. In one embodiment, a thermoplastic elastomer comprises a copolymer, such as styrene-ethylene-butylene-styrene.
[0273] In some embodiments, the insulating layer comprises a multi-layered construct. For example, a multilayered construct may comprise an adhesive layer in contact with the outer conductive layer, an adhesive layer in contact with the inner conductive layer, or both.
[0274] An adhesive useful for the adhesive layer includes, without limitation, a pressure sensitive adhesive, a rubber-based adhesive, an epoxy, a polyurethane, a silicone adhesive, a phenolic resin, a UV curable adhesive, an acrylate adhesive, a laminating adhesive and derivatives thereof, a fluoropolymer, or any combination of two or more thereof. In certain embodiments, the adhesive comprises a low or high density polyethylene (HDPE/LDPE), a polyolefin or derivative thereof, an acid containing an adhesive such as EAA or EMAA, an ionomer, a terpolymer of ethylene, and acrylate, including methyl acrylate or isobutyl acrylate, ethylene-vinyl acetate (EVA), or any combination of two or more thereof.
[0275] In one embodiment, the insulating layer comprises a multilayer construct comprising an acrylic pressure sensitive adhesive layer in contact with the outer conductive layer, a laminating adhesive in contact with the inner conductive layer and a polyethylene terephthalate between the adhesive layers. In one embodiment, the insulating layer is multi-layered construct comprising a 25-40 μm layer of acrylic pressure sensitive adhesive in contact with the outer conductive layer, a 1-12.5 μm layer of laminate adhesive in contact with the inner conductive layer, and a 1-25 μm layer of polyethylene terephthalate between the two adhesive layers.
[0276] In some embodiments, the insulating layer further comprises an internal support member (
[0277] In some embodiments, the internal support member comprises a metal, including, without limitation, stainless steel, nickel, gold, aluminum, titanium, an alloy thereof, or a combination of any two or more thereof. In one embodiment, the stainless steel used in the internal support member comprises SS304, SS316, SS430, duplex 2205, duplex 2304, duplex 2507, or one or more other steel with a chromium content equal to or greater than about 10% by weight and/or a nickel content equal to or greater than 0.1%. by weight.
[0278] In some embodiments, the internal support member is coated with an insulating layer. The insulating layer may cover part or all of the internal support member. In some embodiments, the insulating layer encapsulates the internal support member. In some embodiments, the coating comprises a thermoset elastomer. In some embodiments, a coating of up to about 50 μm of thermoset elastomer is spray-coated on an internal support member using an air assisted spray or needle dispensed conformal coating. Examples of thermoset elastomers include without limitation polydimethylsiloxane, crosslinked polyurethane coating, crosslinked acrylates, rubberized epoxy, or any combination thereof. Crosslinked acrylates may be crosslinked, in some embodiments, using an ultraviolet light source.
[0279] After coating, molding or thermoforming to form the insulating layer, the overall shrinkage of the insulating material, in some embodiments, is less than about 30%, less than about 15%, or less than about 5%.
[0280] After coating, molding or thermoforming to form the insulating layer, its dielectric properties can be determined by any conventional method, including by DC resistance or conductance. ASTM D257-14, Standard Test Methods for DC Resistance or Conductance of Insulating Materials, ASTM International, West Conshohocken, Pa., 2014, which is hereby incorporated by reference in its entirety, is one method of determining DC resistance or conductance of a material. In one embodiment, the insulating layer comprises a dielectric breakdown strength of at least 50V per 25 micron of insulating layer thickness.
[0281] In some embodiments, the glass transition temperature (Tg) of a polymer coating is sufficiently high in order to minimize warping, shrinkage, or deformation of the polymer during of a high temperature process, for instance during metallization. Alternatively, during test processes, the test battery may be exposed to temperatures of up to 130° C. for thermal abuse testing to confirm that the polymer layer does not shift in position or breakdown. The Tg of thermoplastic elastomers in some embodiments is greater than 80° C., greater than about 90° C., greater than about 100° C., greater than about 110° C., greater than about 120° C., greater than about 130° C., greater than about 140° C., or greater than about 150° C. In other embodiments, the glass transition temperature ranges from about 80° C. to about 350° C., about 80° C. to about 300° C., about 80° C. to about 250° C., about 90° C. to about 350° C., about 90° C. to about 300° C., about 90° C. to about 250° C., about 100° C. to about 350° C., about 100° C. to about 300° C., about 100° C. to about 250° C., about 110° C. to about 350° C., about 110° C. to about 300° C., about 110° C. to about 250° C., about 130° C. to about 350° C., about 130° C. to about 300° C., about 130° C. to about 250° C., about 140° C. to about 350° C., about 140° C. to about 300° C., about 140° C. to about 250° C., about 150° C. to about 350° C., about 150° C. to about 300° C., or about 150° C. to about 250° C.
[0282] In some embodiments, the decomposition temperature of the thermoset polymer is greater than about 85° C., greater than about 100° C., greater than about 125° C., greater than about 150° C., greater than about 175° C., or greater than about 200° C.
[0283] Another test that batteries may be subjected to is low to high thermal cycling from about −45° C. to about 75° C. In some embodiments, the insulating layer comprises a polymer that prevents cracking and internal shorting during thermal cycling.
[0284] In some embodiments, under immersion in water, 0.85% saline, 25% Ringers solution, or artificial saliva solution, the polymer may become saturated with water. Thus, there may be some diffusion of water through the polymeric insulating layer, resulting in a change in electrical properties of the insulating layer, referred to as “water permeability.” Water permeability may occur at the region around the crimp radius of a battery. The extent to which a polymer is exposed to water in this region may range from a 0 to 500 micron wide circumference around the inner diameter of a cathode can. The water permeability will therefore depend on the width of exposure to water and the type of polymer. Under immersion in water, 0.85% saline, or artificial saliva solution, the polymer may become saturated with water, resulting in water diffusion and an increase in conductivity of the insulating layer. In some embodiments, the increase in conductivity may be no more than about 1000%, no more than about 100%, or no more than about 10%.
[0285] Water permeability data on exemplary materials used in the Examples is provided in Table 1.
TABLE-US-00001 TABLE 1 Water permeability of exemplary insulating layer materials Polymer Type ULTEM D570 Data Polypropylene PET PEI PPS PVDF 24 Hours 0.01 to 0.1% 0.25% 0.02 to 0.03 to 0.030% 0.03% 0.06% Saturation 0.1% 0.7% 1.25% 0.05% 0.06% (Equilibrium)
[0286] The extent to which polymers absorbed water was measured according to ASTM standard testing, ASTM D570-98(2018), Standard Test Method for Water Absorption of Plastics, ASTM International, West Conshohocken, Pa., 2018, which is hereby incorporated by reference in its entirety.
[0287] In some embodiments, the bridge comprises a conductive material, such as a metal. Metals useful for the bridge material include metals that are readily oxidized in the presence of a current flow, such as stainless steel, magnesium, aluminum, manganese, zinc, chromium, cobalt, nickel, tin, antimony, bismuth, copper, silicon, silver, zirconium, or a combination of any two or more thereof. In some embodiments, the stainless steel comprises SS304, SS316, SS430, a duplex stainless steel, or one or more other steel with a chromium content equal to or greater than 10% by weight and/or a nickel content equal to or greater than 0.1% by weight.
[0288] In certain embodiments, the bridge oxidizes at the same rate or more rapidly than the outer conductive layer. In particular embodiments, the bridge oxidizes in less than about 1 hour after initial contact with a conductive aqueous medium. In other embodiments, the bridge oxides in less than about 30 minutes, less than about 20 minutes, or less than about 10 minutes.
[0289] C. Exemplary Layer Thickness
[0290]
[0291] In some embodiments, the outer conductive layer 1304 may have a uniform (
[0292] In some embodiments, the inner conductive layer 1303 has a uniform or variable thickness ranging from about 100 nm to about 400 μm. In some embodiments, the inner conductive layer has a thickness ranging from about 100 nm to about 350 μm, about 1 μm to about 350 μm, about 200 μm to about 350 μm, about 1 μm to about 50 μm, about 5 μm to about 50 μm, about 50 μm to 250 μm, or about 5 μm to about 200 μm.
[0293] In some embodiments, the insulating layer 1305 has a uniform or varying thickness ranging from about 1 μm to about 400 μm. In some embodiments, the insulating layer has a thickness ranging from about 1 μm to about 350 μm, about 200 μm to about 350 μm, about 1 μm to about 50 μm, about 5 μm to about 50 μm, about 50 μm to 250 μm, or about 5 μm to about 200 μm.
[0294] In certain embodiments, the insulating layer includes an internal support 1317 having a uniform or varying thickness ranging from about 200 μm to about 356 μm (
[0295] The at least one bridge may have a uniform or varying thickness ranging from about 100 nm to about 50 μm.
[0296] Methods for forming layers having the above described thicknesses are known in the art. For example, physical vapor deposition is useful for forming layers having a thickness of about 100 nm to about 10 μm. Cladding, welding, pinching, or stamping are useful processes for forming layers having a thickness ranging from about 1 μm to about 400 μm.
III. Exemplary Contact with a Conductive Aqueous Medium
[0297] Contact of a battery with a conductive aqueous medium includes immersing a battery in a conductive aqueous medium or contacting the battery with a wet tissue, such as tissues of the mouth, throat, esophagus, or any other part of the GI tract of a mammal. In some embodiments, the contact with the conductive aqueous medium comprises placement of the battery on a hydrated tissue such that the at least one bridge and at least a part of the anode case is in contact with the hydrated tissue. In some embodiments, the hydrated tissue is hydrated ham, while in other embodiments, the tissue is hydrated pig esophageal tissue.
[0298] In another embodiment, the contact with the conductive aqueous medium comprises immersion of the battery, anode terminal facing up, in the conductive aqueous medium. In one embodiment, the conductive aqueous medium is about 20 mL of 0.85% w/w saline solution or about 20 mL of 25% Ringers solution with an initial pH ranging from about 5 to about 7, and after the battery is immersed, the average pH of the saline solution over the first 60-minute time period does not exceed an average pH of about 10 with a sampling interval of every 5 minutes, 25% Ringer's solution contains 36.75 mM sodium chloride, 1.00 mM potassium chloride, and 0.75 mM calcium chloride. The pH should be measured directly in the solution container about 3 cm above the center of the anode case with either pH paper or a digital pH meter without mixing. In yet another embodiment, the pH of the solution does not exceed about 9.5 for a time period of 10 to 60 minutes after immersion. In another embodiment, the pH of the solution does not exceed 9 for a time period of from 10 to 60 minutes after immersion. In yet another embodiment, the pH of the solution does not exceed about 8.5 for a time period of 10 to 60 minutes after immersion. In yet another embodiment, the pH of the solution does not exceed about 8 for a time period of 10 to 60 minutes after immersion. In yet another embodiment, the pH of the solution does not exceed about 7.5 for a time period of 10 to 60 minutes after immersion.
[0299] In another embodiment, after immersion of the battery in 20 mL of a 0.85% w/w saline solution or 20 mL of 25% Ringers solution having a pH of about 5 to 7 at room temperature for at least 1 hour, the electrical resistance between the inner conductive layer and the outer conductive layer is greater than about 500 ohms, greater than about 50 kohms, or greater than about 500 kohms. In another embodiment, the connection between the inner conductive layer and the outer conductive layer becomes an open circuit. In another embodiment, the current between the inner conductive layer and the outer conductive layer is less than about 0.1 mA, lesser than about 0.01 mA, or lesser than about 1 μA.
[0300] In some embodiments, the battery is immersed with anode side facing up in about 20 mL of the about 0.85% saline solution or about 20 mL of 25% Ringers solution.
IV. Exemplary Laminates
[0301] Next, the present disclosure provides multi-layer laminates that are useful for forming an electrode case. An exemplary multi-layer laminate 1400 is depicted in
[0302] The multi-layer laminates may advantageously be used to form an electrode case, such as a cathode case, for a battery as described herein, and after contact of the at least one bridge with a conductive aqueous medium, the electrical contact between the first and the second conductive layers is reduced or severed.
[0303] The first conductive layer may comprise any conductive material. In some embodiments, the first conductive layer comprises aluminum, stainless steel, nickel, chromium, tungsten, vanadium, or a combination of any two or more thereof. The second conductive layer also may comprise any conductive material. Metals useful for the second conductive layer include, without limitation, stainless steel, aluminum, titanium, or a combination of any two or more thereof.
[0304] In a particular embodiment, the second conductive layer comprises stainless steel. Useful stainless steels include, without limitation, SS304, SS316, SS430, a duplex stainless steel, steel with a chromium contact greater than or equal to about 10% by weight and a nickel content greater than or equal to about 0.1% by weight, or a combination of any two or more thereof.
[0305] The insulating layer may be, in some embodiments, a hydrophobic polymer, a natural rubber, a silicone elastomer, a cellulose acetate, a paper dielectric, a ceramic, a metal oxide, a nitride, a carbide, or a combination of any two or more thereof. The hydrophobic polymer may be polyethylene terephthalate, a polytetrafluoroethylene, a fluorinated ethylene propylene, a polyvinyl fluoride, a polyvinylidine difluoride, a polypropylene, a polyurethane, a polyimide, a dimethylpolysiloxane, an adhesive, an anodized aluminum, or a combination of any two or more thereof. Useful metal oxides include is aluminum oxide, nickel oxide, chromium oxide, or a combination of any two or more thereof.
[0306] In some embodiments the insulating layer further comprises: a) multiple layers; b) a multilayered construction including an adhesive layer in contact with the outer conductive layer; c) a multilayered construction including an adhesive layer in contact with the inner conductive layer; or d) a) b) and/or c).
[0307] The adhesive layers of the multilayered insulating layer may comprise a pressure-sensitive adhesive, a rubber-based adhesive, an epoxy, a polyurethane, a silicone adhesive, a phenolic resin, a UV curable adhesive, an acrylate adhesive, a laminating adhesive, a fluoropolymer, or any combination of two or more thereof.
[0308] The at least one bridge that may be formed with the laminate may comprises a material that is capable of electrochemical dissolution in a conductive aqueous medium. Useful materials for the bridge include stainless steel, aluminum, chromium, magnesium, nickel, copper, zinc, or a combination of any two or more thereof.
[0309] In some embodiments, the first conductive layer has a uniform or variable thickness ranging from about 100 nm to about 400 μm, 100 nm to about 350 μm, 1 μm to about 350 μm, about 200 μm to about 350 μm, about 1 μm to about 50 μm, or about 50 μm to 200 μm.
[0310] In some embodiments, the second conductive layer may have a uniform or varying thickness ranging from about 100 nm to about 400 μm, about 100 nm to about 350 μm, about 1 μm to about 350 μm. In some embodiments, the second conductive layer has a thickness ranging from about 200 μm to about 350 μm, about 1 μm to about 50 μm, or about 50 μm to 200 μm.
[0311] In some embodiments, the insulating layer has a uniform or varying thickness ranging from about 100 nm to about 400 μm, about 100 nm to about 350 μm, about 1 μm to about 350 μm, about 200 μm to about 350 μm, about 1 μm to about 50 μm, or about 50 μm to 200 μm.
[0312] In certain embodiments, the insulating layer includes an internal support having a uniform or varying thickness ranging from about 200 μm to about 356 μm.
[0313] The at least one bridge may have a uniform or varying thickness ranging from about 100 nm to about 50 μm.
V. Exemplary Methods of Manufacture
[0314] The present disclosure further provides methods for manufacturing the aforementioned exemplary cathode cases and exemplary batteries. Several methods are available, including the following non-limiting examples. In one embodiment depicted in
[0315] a) providing a laminate having a first conductive layer 1503, a second conductive layer 1504, and an insulating layer 1505 between the first and the second conductive layers;
[0316] b) stamping 1530 the laminate to form a cathode case 1500A comprising a bottom, an annular side, and a rim; and
[0317] c) forming at least one bridge between the first and the second conductive layers, wherein the first conductive layer forms an interior surface of the case, and the second conductive layer forms an exterior surface of the case.
[0318] In some embodiments, the bridge may be formed by crimping the rim. Alternatively, the stamping process forms the bridge. In another embodiment as depicted in
[0319] In other embodiments, where the edge of the can is rolled in either direction (
[0320] The at least one bridge may comprise a portion of the first conductive layer in electrical contact with the second conductive layer. Alternatively, the at least one bridge may comprise a portion of the second conductive layer in electrical contact with the first conductive layer.
[0321] In some embodiments, the at least one bridge comprises a conductive wire, a conductive strip, or a conductive sheet. A plurality of bridges of may be formed, or a single bridge may be formed.
[0322] In another embodiment, a method of manufacturing a cathode case having an internal support in the insulating layer comprises:
[0323] a) providing an internal support comprising a bottom, an annular side, a rim, an interior surface, and an exterior surface:
[0324] b) depositing an insulating layer on the interior, the exterior and the rim of the internal support;
[0325] c) depositing a first conductive material on the insulating layer on the interior surface and optionally the rim, thereby forming an inner conductive layer;
[0326] d) depositing a second conductive material on the insulating layer on the exterior surface and optionally the rim, thereby forming an outer conductive layer;
[0327] wherein the inner conductive layer and the outer conductive layers are in contact via at least one bridge (
[0328]
[0329]
[0330] In another embodiment, depicted in
[0331]
[0332] Yet another manufacturing process is shown in
[0333] In another embodiment depicted in
[0334] In another embodiment depicted in
[0335] In another embodiment depicted in
[0336] In another embodiment depicted in
[0337] In another embodiment depicted in
[0338] In some embodiments of any of the aforementioned methods of manufacture, an insulating material is formed into a cup-shaped insulating layer by thermoforming. Alternatively, the insulating layer may be formed into a cup shape by molding. In some embodiments, the molding produces a cup-shaped insulating layer having a thickness ranging from about 10 μm to about 100 μm thick.
[0339] In some embodiments of the aforementioned manufacturing methods, the inner conductive layer can be formed by casting a conductive metal to form a cup. In some embodiments, the cast conductive metal cup can fit inside a cup-shaped insulating layer. In one embodiment, aluminum or an aluminum alloys can be cast to form a cup having a thickness ranging from about 5 μm to about 50 μm. Casting advantageously may prevent wrinkling that may happen during a stamping or forming process. The cast conductive layer may further include a plurality of tabs, for example, as depicted in
[0340] The resistance of the cathode case can be measured using a four probe milliohm meter (Extech Model #380580) for quality control. As depicted in
[0341] The measurement of internal resistance of the battery is known in the art. One method for measuring internal resistance is measuring the AC impedance at 1 kHz using a Gamry potentiostat.
[0342] In some manufacturing processes, the assembled cell is sprayed or immersed in a nonconductive aqueous medium shortly after assembly to presumably remove any excess material and/or solvent in a manner that does not interfere with the battery stability or performance.
[0343] In some embodiments, a battery as disclosed herein may not deactivate in a non-conductive aqueous medium. In some embodiments, deactivation occurs when the voltage of the battery decreases to 1.23V or lower when the battery is dry and when the battery voltage is measured in series with a 15 kohm resistor. For example, deactivation of a battery disclosed herein may not occur after immersion of in a nonconductive aqueous medium for up to 1 minute, for up to 10 minutes, for up to 1 hour, for up to 3 hours, for up to 1 day, or for up to 10 days.
[0344] In some embodiments, the internal resistance of a battery as disclosed herein may increase by less than about 1 ohm, by less than about 10 ohm, by less than about 20 ohm, by less than about 100 ohm, or by less than about 500 ohm after immersion of the battery in a nonconductive aqueous medium for up to about 1 minute, for up to about 10 minutes, for up to about 1 hour, for up to about 3 hours, for up to about 1 day, or for up to about 10 days.
[0345] In some embodiments, the resistance of an exemplary battery measured between the inner conductive layer and the outer conductive layer may increase by less than about 1 ohm, by less than about 10 ohm, by less than about 20 ohm, by less than about 100 ohm, or by less than about 500 ohm after immersion of the battery in a nonconductive aqueous medium for up to about 1 minute, for up to about 10 minutes, for up to about 1 hour, for up to about 3 hours, for up to about 1 day, or for up to about 10 days.
[0346] In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms after immersion of the battery in a non-conductive aqueous medium from about 1 min to 180 minutes, or from about 1 min to 60 min, or from about 1 min to 10 min.
[0347] In some embodiments, the shelf-life stability of a battery may be estimated by testing the battery after storage in conditions more extreme than typical storage conditions.
[0348] In some embodiments, the battery is stored in an environment having a temperature in the range of about −20° C. to about 60° C. In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms after storing the battery in an environment having a temperature in the range of −20° C. to 60° C., or in the range of about 40° to about 60, such as at a temperature of about 40° C., about 45° C., about 50° C., about 55° C., or about 60° C. In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms after storing the battery in an environment having any of the above temperatures for more than about 2 hours, or from about 2 hours to 60 days, or from about 120 hours to 20 days, or from about 60 days to 1 year.
[0349] In some embodiments, the battery is stored in an environment having a relative humidity (RH) in the range of from 0 to 100% RH, such as about 30% h to about 90% RH. In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms when stored in an environment having a relative humidity of about 95% or lower, or a relative humidity of about 90% or lower, or between 30% to 90% RH. In some embodiments the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms after storing the battery in an environment having any of the above relative humidity values for more than about 2 hours, or from 2 hours to 60 days, or from 120 hours to 20 days, or from 60 days to 1 year.
[0350] In still other embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does increase by more than about 20 ohms after being stored in an environment having a temperature of from 40° C. to 60° C. for 2 hours to 7 days.
[0351] In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms when the battery is stored in the environment having relative humidity of about 95% or lower, or when the battery is stored in the environment having relative humidity of about 95% or lower, for more than about 2 hours, or from 2 hours to 60 days, or from 2 hours to 20 days, or from 120 hours to 7 days, or from 7 days to 60 days.
[0352] In other embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms when the battery is stored in an environment having relative humidity of about 30% to about 90% for about 2 hours to about 7 days.
[0353] In some embodiments, the internal resistance of the battery does not increase by more than about 500 ohms, or does not increase by more than about 100 ohms, or does not increase by more than about 50 ohms, or does not increase by more than about 20 ohms when the battery is stored in an environment having relative humidity of from about 30% to about 90% and a temperature of from about 40° C. to about 45° C. for about 2 hours to 7 days.
EXAMPLES
Example 1
[0354] A. Manufacture of an Example Battery
[0355] An exemplary cathode case is shown in
[0356]
[0357]
[0358] B. Comparative Tests of Control Batteries and Example Batteries
[0359] The results of exposing a commercial Maxell CR2032 lithium control battery, a lab-made control battery, and the treatment example battery to saline, 25% Ringers solution, deionized water, hydrated esophageal tissue, and hydrated ham are reported below. These tests simulate the activity of the batteries under biologic conditions (e.g., after being swallowed and reacting with living tissue).
[0360] i) Immersion in Saline
[0361]
[0362] The lab-made control and treatment example batteries were examined by scanning electron microscopy (SEM) before and after the immersion in saline experiment. Following the experiment, the batteries were dried for at least 24 hours in a desiccator. The top down view of the crimp area of the lab-made control is shown before saline immersion in
[0363] ii). Immersion in 25% Ringers Solution and DI Water
[0364]
TABLE-US-00002 TABLE 2 The duration of time for exemplary batteries to drop below 1.2V in 25% Ringers Solution and other voltage and pH measurements. Exemplary Al layer Time to Voltage Voltage Run battery thickness drop below after after pH after ID embodiment type (μm) 1.2 V (min) 1 hr (V) 2 hr (V) 2 hr 3137 Double-fold 9 11.8 0.544 0.058 6 3141 Double-fold 9 10.0 0.495 — — 3142 Double-fold 9 7.1 0.528 — — 3148 Double-fold 9 11.1 0.666 — — 3143 Double-fold 5 4.3 0.450 0.099 6 3144 Double-fold 5 4.2 0.097 0.009 5 3145 Double-fold 5 2.1 0.302 −0.025 5 3147 4-tab 9 5.0 0.409 0.062 5 3149 4-tab 9 3.5 0.316 0.104 5 3150 4-tab 9 9.6 0.244 0.137 5 3153 4-tab 9 8.2 0.372 0.043 5 3159 4-tab 9 9.1 0.435 −0.004 5 3160 4-tab 9 4.6 0.372 −0.107 5 310A Commercial N/A — 1.885 1.794 12.5 Control 310B Commercial N/A — 2.099 1.958 12.5 Control
[0365] The results of four exemplary batteries, specifically the double-fold example with an Al layer thickness of 9 μm described further in example 3, and one commercial control CR2032 are shown in
[0366] To test the stability of the treated cells under cleaning conditions similar to cleaning procedures to which commercial batteries are subjected, an exemplary battery, specifically a double-fold embodiment with a 9 μm Al layer, (3219) and a commercial control cell (320C) were immersed in deionized water (18 MΩ-cm) for 10 days at room temperature (
[0367] In some commercial manufacturing processes, the cell is sprayed or immersed in a non-conductive aqueous medium shortly after assembly to presumably remove any excess material and/or solvent. Exemplary non-conductive aqueous mediums may include 18 Mohm-cm deionized water or non-ionic cleaning solutions with a resistivity greater than 1 Mohm-cm. The immersion in 18 Mohm-cm deionized water described above suggest that the exemplary battery may behave similarly to commercial batteries under cleaning conditions.
[0368] iii) Extended Immersion is 25% Ringers Solution
[0369] Five exemplary batteries, specifically the double-fold embodiments with a 9 μm Al layer, and one commercial Maxell control cell were immersed in 15 mL of 25% Ringers solution for at least 14 days. An image of the double-fold insert and the double-fold insert inside of a CR2032 stainless steel cathode case are shown in
[0370] All five example cells, 3501 through 3505, followed a similar pH curve during the first 120 minutes of the experiment (
[0371] Shown in
[0372] The progression of the reaction can be seen in
[0373] After at least 14 days, the cells were removed and cleaned in 18 MΩ-cm deionized water with light brushing to remove excess solids.
TABLE-US-00003 TABLE 3 Physical and Electrical Measurements of Commercial and Exemplary Batteries after long term immersion in 25% Ringers Solution. Mass Mass OCV 15k_C 3.9k_C 1k_CC pH of Sample Days (g) Change (g) (V) CV (V) CV (V) V (V) solution 350A 0 2.948 — 3.312 3.306 3.289 3.23 5.5 17 2.963 0.015 −0.003 0 0 0 Not measured 3501 0 2.795 — 3.206 3.193 3.158 3.048 5 14 2.805 0.010 0.001 0 0 0 6 3502 0 2.812 — 3.296 3.286 3.255 3.161 5 14 2.825 0.013 2.701 0.022 0.005 0.001 6 3503 0 2.735 — 3.268 3.239 3.157 2.856 5 14 2.741 0.006 0.033 0 0 0 5.5 3504 0 2.715 — 3.276 3.182 2.474 1.866 5 14 2.723 0.008 0.001 0 0 0 6 3505 0 2.733 — 3.238 3.227 3.194 3.101 5 14 2.743 0.010 0.524 0.001 0 0 6
[0374] In Table 3, the open circuit voltage (OCV) as well as the closed circuit voltage (CCV) under 15 kohm for 5 seconds (15 k_CCV), 3.9 kohm for 5 seconds (3.9 k_CCV), and 1 kohm for 1 second (1 k_CCV) loads is recorded before and after immersion. The lab-made prototype cells have a higher variability in initial electrical performance since they were made in a lab and not on a commercial line. After immersion, all of the cells have a very high internal resistance and are incapable of carrying a load of 15 kohm with any significant voltage. The only cell to read an OCV over 1.2 V is sample 3502. This could be due to a very high resistance pathway still intact after immersion facilitated by some remaining solution. The resistance is large enough to not allow electrolysis of the conductive aqueous medium to take place. When sample 3502 was remeasured after three days drying on the bench top, the OCV read 0.018 V. The commercial cell also could not maintain a voltage with a 15 kohm load, but this is likely due to the capacity being drained as the cell continued to react with the solution to form hydroxide ions and the internal chemistry eventually being exposed to solution.
[0375] In the prototype samples, a small amount of white precipitate is formed after 15 minutes which becomes more apparent as the sample is immersed in solution for longer periods of time (
TABLE-US-00004 TABLE 4 ICP-OES Analysis of the solutions from the Commercial and Exemplary Batteries experiments after long term immersion in 25% Ringers Solution. ICP-OES Units μg/L μg/L μg/L μg/L μg/L μg/L Metals Fe Cr Li Mn Ni Al Sample Solutions 350A (Commercial) 3746000 721200 816800 29460 273600 5951 3501 874 35 50 26 30 149100 3502 1108 78 13 26 60 165800 3503 697 19 14 16 18 118200 3504 889 29 10 65 26 154900 3505 893 22 10 21 23 170900 25% Ringers Solution 32 ND 8 ND ND 315 (Background) PQL 100 5 10 5 5 100 LOD 25 1.25 5 1.25 1.25 25 PQL = Practical Quantitation Limit; LOD = Limit of Detection; ND = No Detection
[0376] The solution from the commercial control contained high concentrations of elements expected from the corrosion of stainless steel such as Fe, Ni, and Cr. The control also had very high levels of Mn and Li which likely came from the internal contents breaching the cell after the casing became compromised. The prototype cells had extremely low levels of Li and Mn suggesting that the internal contents of the cell did not spill out into the solution.
[0377] iv.) Resistance of the Aluminum and Stainless Steel Electrical Junction During Elevated Temperature and High Humidity Testing of the Double-Fold Embodiment
[0378] Double-fold laminate inserts 4020, as described in
[0379] How long a battery can be stored without losing its specified performance is considered the battery's shelf life stability. One can measure the shelf-life stability by storing the product under normal storage conditions, and then routinely measuring the product performance. Alternatively, in some battery testing procedures, the shelf-life stability may be estimated by measuring the performance of the cell at about 60° C. with about 90% relative humidity. Twenty days under these conditions may approximate 1 year under ambient temperature and humidity. An approximated shelf life of 1 year or greater is advantageous in terms of mass production and manufacturability. The experiment above suggests that the exemplary battery cathode case may not undergo corrosion after storage for 133 days in an environment having a temperature of about 60° C. and about 90-100% relative humidity. Other experiments, such as Example 1bii, suggest that the same exemplary battery cathode case may deactivate in a conductive aqueous medium in a duration ranging from about 5 to about 15 minutes. The possible short deactivation time in a conductive aqueous medium in addition to the suggested stability at about 60° C. with about 90% relative humidity may be a unique aspect to this exemplary battery case design.
[0380] v) Exposure to Hydrated Porcine Esophageal Tissue
[0381] Commercial Maxell CR2032 control, lab-made control, and treatment example batteries were placed in porcine esophageal tissue and examined for changes in appearance and signs of visual damage. The frozen porcine esophageal samples were thawed in room temperature water for 12 hours before use, then rinsed with artificial saliva and placed in an artificial saliva bath at 37° C. The porcine esophageal tissue was cut into about 7 cm segments and the tubular samples were cut along the long axis to open the tissue to a flat sheet. The tissue samples were kept in the artificial salvia bath until the start of the experiment. Next, the batteries were placed with the anode facing down on the bottom layer of a segment of tissue, then the drip irrigation hose was placed on top of the esophagus section, and finally the tissue was folded over secured by a clamp to the irrigation board. The drip irrigation was set to 10 mL/15 min of 37° C. artificial saliva. About every 15 minutes, the clip was opened and the tissue was photographed for a total duration of 4 hours. Attempts to measure pH resulted in irregular and variable values, most likely due to the continuous flow of artificial saliva.
[0382] Exposure of the tissue to the lab-made control batteries resulted in a slower increase in visual damage compared to exposure to the commercial control, likely because of differences in impedance between the batteries (the impedance of the lab-made batteries is consistently more than twice that of the commercial control batteries). Despite these differences, the commercial control and the lab-made control began showing signs of visual damage within 60 minutes (
[0383] vi) Exposure to Hydrated Ham
[0384] Exposure of commercial Maxell CR2032 lithium control, lab-made control, and exemplary batteries to a slice of ham showed similar trends as seen in the saline immersion test. The ham samples were initially hydrated with about 3 ml of 0.85% saline solution in a shallow petri dish and the cells were placed with the anode facing down on the bottom layer of the ham. The slice of ham was folded over to cover the cell and a weight of 500 g was pressed on top of the ham. pH of the ham in direct contact with the center of the anode case was measured at 0, 10, 30 and 60 minutes by gently unfolding the ham, moving the battery aside, and touching pH paper strips to the ham where the center of the anode case had been. The battery was returned to the initial position after each measurement.
[0385] The 60-minute time point photographs displayed in
Example 2
[0386] A. Exemplary Materials Used in Examples 2-10 are Listed Below:
[0387] 1. Exemplary Foil and Foil Laminate Materials
[0388] Aluminum alloy 1100 temper O at a thickness of 9, 12.5, 17.5 and 25 microns (μm) wrapped around Aluminum alloy 1235 temper O at a thickness of 9, 12.5, 17.5 and 25 microns Wrapped around. Aluminum foil laminate with foil layer of 1145 aluminum foil at 8.89 micron thickness laminated to polyethylene terephthalate polymer film at 12.5 micron thickness (48 ga) with thermoset laminating adhesive epoxy based, 2 part formulation with varying cross-linker concentrations (brand name Lamart MF100).
[0389] Aluminum foil laminate with foil layer of 1145 aluminum foil at 8.89 micron thickness laminated to polyetherimide ULTEM film at 12.5 micron thickness (48 ga) with thermoset laminating adhesive epoxy based, 2 part formulation with varying cross-linker concentrations.
[0390] 2. Exemplary Thermoform Film Materials
[0391] Polymer material was thermoformed into plastic liner cups for the insulation layer. Example polymers used for this process include polyethylene terephthalate (brand name Mylar) at 36 μm, 50 μm thickness, polyetherimide (brand name ULTEM and Kapton) at 25 μm and 50 μm, perfluoroalkoxy polymer film, fluorinated ethylene propylene film and polyvinylidene fluoride film at 25 μm and 50 μm thickness.
[0392] 3. Exemplary Outer Cathode can Substrate Materials
[0393] The cathode “can” in the examples refers to the thicker stainless steel layer that typically makes up the outer conductive layer.
[0394] The cathode “case” refers to the whole cathode case construction, which includes the cathode can and any inserts affixed to the cathode can.
[0395] Cathode can substrates were made out of stainless steel SS304 or SS430 at 20 μm, 225 μm or 250 μm thickness.
[0396] The abo % e substrate materials were then stamped to specific dimensions designed to fit a CR2032 battery assembly to cover and crimp in an anode cup which will house the active portion of the coin cell.
[0397] B. PVD 3-8 Micron Al Layer on ULTEM Thermoform Cup Prototype
[0398] A schematic depicting the manufacture of a battery in accordance with this example is depicted in
[0399] When immersed in 0.85 wt % saline solution, the exposed Al coated around the rim edge of the cathode oxidized to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranged from 30 sec to 4 mins based on the thickness of the Al PVD coating and the height of the exposed Al layer as show % n in Table 5.
TABLE-US-00005 TABLE 5 The physical properties and deactivation times for Al PVD example batteries. Cathode Can SS304 with PVD Cathode Total PVD thermoform Can thermoform PVD insert Initial Time to Thickness thickness Thermoform resistance OCV Deactivate (mm) (mm) Mass (g) (mohm) (V) (mins) 0.250 0.054 0.033 37 2.96 4.0 0.250 0.055 0.032 22 2.97 2.0 0.250 0.047 0.031 26 3.08 0.8 0.250 0.052 0.033 21 2.98 2.0 0.200 0.052 0.0029 27 3.03 0.5 0.200 0.053 0.030 32 3.07 1.0 0.200 0.064 0.033 38 2.97 2.0 0.200 0.058 0.034 42 3.01 3.5 0.200 0.052 0.032 30 3.05 1.0 0.200 0.051 0.031 67 2.97 2.0
Example 3. Laminate Double-Fold Insert with Full Flange Folded Down Prototype
[0400] A schematic depicting the manufacture of a battery in accordance with this example is depicted in
[0401] As in previous samples, when immersed in 0.85 wt % saline solution, the exposed Al foil around the rim edge of the cathode 2119c oxidized to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranges from 3-20 mins based on the height of the exposed Al foil fold.
Example 4. Laminate 4 Tab Insert and Thermoform Support Prototype
[0402] Schematics depicting the manufacture of a battery according to this example are shown in
[0403] As in previous samples, when immersed in 0.85 wt % saline solution, the exposed Al foil around the rim edge of the cathode oxidized to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranged from 3-10 mins based on the height and thickness of the exposed Al foil fold.
Example 5. Al Foil 4 Tab Insert and Thermoform Insulating Support Prototype
[0404] An Al foil was stamped into the shape described in
[0405] As in previous samples, when immersed in 0.85 wt % saline solution, the exposed Al foil around the rim edge of the cathode oxidizes to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranges from 3-20 mins based on the height and thickness of the exposed Al foil fold.
Example 6. Laminate 4 Tab Insert and Channeled Cathode can Prototype
[0406] As depicted in
[0407] When immersed in 0.85 wt % saline solution, the exposed Al foil from the 4 extended tabs oxidized to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranged from 3-20 mins based on the width, length, and thickness of the exposed laminate tabs.
Example 7. Al Foil 4 Tab Insert and Channeled Cathode can Prototype
[0408] An Al 12.5 μm foil 2320 was stamped into the shape illustrated in
[0409] When immersed in 0.85 wt % saline solution, the exposed Al foil from the 4 extended tabs oxidized to greatly increase the resistance of the battery and stop the electrolysis of the saline solution. The deactivation time ranged from 3-20 mins based on the width, length, and thickness of the exposed Al foil tabs.
Example 8. Trilaminate with Adjusted Crosslinker Levels Prototype
[0410] A tri-laminate material according to
[0411] The tri-laminate was stamped into the cathode can. The bridge was formed by pinching the Al foil layer into the SS304 outer cathode can during the crimping process. The bridge can be further secured by using solder or ultrasonic welding to help join the Al SS304 before or after the crimping step.
[0412] As in previous samples, when immersed in 0.85 wt % saline solution, the exposed Al foil around the rim edge of the cathode oxidized to greatly increase the resistance of the battery and stop the electrolysis sis of the saline solution. The deactivation time ranged from 3-20 mins based on the amount and thickness of the exposed Al foil.
Example 9. SS304 and Kapton Laminate that is PVD Coated Prototype
[0413] A to layer laminate of fully annealed, draw quality SS304 sheet roll and Kapton (PEI) film were joined by a laminating adhesive. The thickness combinations include 200 μm SS304/50 μm Kapton, 225 μm SS304/25 μm Kapton, and 250 μm SS304/25 μm Kapton. The amount of crosslinker was optimized to obtain strong adhesion while also maintaining flexibility so the material could be stamped without delaminating. If the crosslinking level was too high, the laminating adhesive became brittle and delaminated during the stamping process, especially along the walls of the can where the material is drawn the deepest
[0414] The Kapton/SS304 laminate was then stamped into cathode cans and a 3-10 μm layer of Al was deposited by PVD. The ULTEM layer did not warp and maintained its size and shape after going through the PVD process and the laminating adhesive maintained the bond between the stainless steel and Kapton layers.
Example 10. Dykor Encapsulation Prototype
[0415] Starting with a 200 μm stainless steel cathode can, about a 50-100 μm layer of Dykor is coated as the insulating layer (similar to that exemplified in
EQUIVALENTS
[0416] The foregoing written specification is sufficient to enable one skilled in the art to practice the embodiments. The foregoing description and Examples detail certain embodiments and describes the best mode contemplated by the inventors. It will be appreciated, however, that no matter how detailed the foregoing may appear in text, the embodiment may be practiced in many ways and should be construed in accordance with the appended claims and any equivalents thereof.