WO2013106821A1

WO2013106821A1 - Lithium coin cell construction to mitigate damage from ingestion

Info

Publication number: WO2013106821A1
Application number: PCT/US2013/021430
Authority: WO
Inventors: Jingdong Guo; Weiwei Huang
Original assignee: Eveready Battery Company, Inc.
Priority date: 2012-01-13
Filing date: 2013-01-14
Publication date: 2013-07-18
Also published as: CN104170116A; EP2803096A1

Abstract

An electrochemical coin cell that includes an anode, and an anode terminal with a closed end that is configured as an electronic conductor and comprises a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution. The cell further includes a cathode, and a cathode terminal that includes a closed end that is configured as an electronic conductor and comprises a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution.

Description

LITHIUM COIN CELL CONSTRUCTION TO MITIGATE DAMAGE FROM INGESTION

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to the construction of electrochemical cells used in battery applications. More particularly, this invention relates to the use of terminal materials

(cans or cups) for electrochemical cells with a nominal open circuit voltage greater than 1.23 V, which is the theoretical voltage window for electrolysis of water (¾0). One aspect of this invention is the use of terminal materials for 3V lithium electrochemical cells (e.g., Li-Mn0₂ and

Li-CF_X) in a button or coin-type configuration to mitigate damage to human tissue upon inadvertent ingestion.

[0002] Incidences of accidental ingestion of batteries, particularly coin cells, by children and senior citizens appear to be increasing in frequency over the past few years. Children are also increasingly making use of electronic toys and devices powered by small batteries. Further, there are some recently reported cases of senior citizens who have inadvertently ingested small batteries after mistaking them for pills.

[0003] In some cases, ingested batteries have lodged in the esophagus leading to an

electrochemical interaction between the battery and human tissue. As reported in a joint letter by the National Electrical Manufacturers Association (NEMA) and National Capital Poison Center (NCPC), electrical current from the ingested battery leads to an electrolysis reaction of the saliva. One product of the reaction is the formation of hydroxide which can cause alkaline burns and perforations of the esophagus. Further, there appears to be a higher risk of injury associated with lithium cells because of their larger diameter and increased voltage relative to other button cell chemistries. However, the electrochemical mechanisms underlying the electrolysis and the cause of injuries associated with battery ingestion is not fully understood in the art.

[0004] For example, United States Patent No. 5,069,989 describes an alkaline battery cell design intended to avoid corrosion of the positive electrode by acidic gastric juices found in the stomach. Specifically, a corrosion -resistant container consisting of a stainless steel having more than 23% chrome is proposed, with the preferred embodiment having a nickel coating layer on the positive electrode can intended to prevent the release of hexachrome ions from the stainless steel.

[0005] Another, related issue addressed in the prior art focuses on mitigating the effects of

corrosion. As used herein, corrosion refers to unwanted electrochemical reactions occurring passively in ambient conditions and involving at least one component of the cell that, by design, was not originally intended to act as an active material. Perhaps the most common example of corrosion involves unwanted reactions to the cell container, typically by way of oxidation.

[0006] In particular, United States Patent No. 5, 478,670 discloses the use of a positive electrode case comprising a high-grade corrosion resistible stainless steel with a pitting index calculated based upon the content of chromium, molybdenum and nitrogen. This container material mitigates against corrosion along the interior of the positive container caused by anodization of aluminum in the presence of an orangic electrolyte at voltage between 2.0-2.8 volts. As such, use of the specified material eliminates the need for an aluminum coating on the interior of the electrode case.

[0007] It is therefore desirable to provide for an electrochemical cell construction that can

mitigate or delay damage to human tissue from inadvertent ingestion of the cell. It is also preferable to develop these new coin cell constructions without any detriment to the underlying functionality of the cell. Methods for designing, manufacturing and/or selling such coin cells, as well as methods for using cells in a manner which eliminates the dangers associated with accidental ingestion, are also desirable.

SUMMARY OF THE INVENTION

[0008] One aspect of the present invention is to provide an electrochemical cell that includes an anode, a cathode, an electrolyte and an anode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the anode terminal, the closed end of the anode terminal configured as an electronic conductor and comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution. The electrochemical cell further includes a cathode terminal comprising a closed end, an open end with a tenninal edge and a side wall extending between the closed and open ends of the cathode terminal, the closed end of the cathode terminal configured as of an electronic conductor and comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution. The cell also includes a gasket disposed and providing a seal between the anode terminal and the cathode terminal and a separator disposed between the anode and the cathode.

[0009] Another aspect of the present invention is to provide an electrochemical coin cell that includes an anode, a cathode, an electrolyte and an anode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the anode terminal, the closed end of the anode terminal configured as an electronic conductor and comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution. The electrochemical coin cell further includes a cathode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the cathode terminal, the closed end of the cathode terminal configured as an electronic conductor and comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution. The cell also includes a gasket disposed and providing a seal between the anode terminal and the cathode terminal, and a separator disposed between the anode and the cathode. The cell has a total cell external diameter of approximately 5-25 mm, and a total cell height of approximately 0.5-10 mm.

[0010] A further aspect of the present invention is to provide an electrochemical cell that

includes an electrolyte and an anode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the anode terminal, the closed end of the anode terminal configured as an electronic conductor and comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva- containing solution. The electrochemical cell further includes a cathode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the cathode terminal, the closed end of the cathode terminal configured as an electronic conductor and comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution. The cell also includes a gasket disposed and providing a seal between the anode terminal and the cathode terminal. The cell further includes an anode disposed in electrical connection with the anode terminal, the anode further comprising a material selected from the group consisting of lithium and lithium alloys, and a cathode disposed in electrical connection with the cathode terminal, the cathode further comprising manganese dioxide. The electrochemical cell also includes a separator disposed between the anode and the cathode.

[0011] An additional aspect of the present invention is to provide an electrochemical coin cell that includes an electrolyte and an anode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the anode terminal, the closed end of the anode terminal configured as an electronic conductor and comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva- containing solution. The electrochemical coin cell further includes a cathode terminal

comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the cathode terminal, the closed end of the cathode terminal configured as an electronic conductor and comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution. The cell also includes a gasket disposed and providing a seal between the anode terminal and the cathode terminal. The cell further includes an anode disposed in electrical connection with the anode terminal, the anode further comprising materials selected from the group consisting of lithium and lithium alloys, and a cathode disposed in electrical connection with the cathode terminal, the cathode further comprising manganese dioxide. The electrochemical coin cell also includes a separator disposed between the anode and the cathode. The electrochemical coin cell additionally includes a total cell external diameter of approximately 5-25 mm and a total cell height of approximately 0.5-10 mm.

[0012] These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the drawings:

[0014] Fig. 1 is a schematic of a lithium coin cell submersed in a saliva solution;

[0015] Fig. 2 is a perspective and cross-sectional view of a lithium-manganese dioxide

electrochemical coin cell, according to one embodiment;

[0016] Fig. 3 is a two-dimensional cross-sectional view of the electrochemical coin cell as

illustrated in Fig. 2;

[0017] Fig. 4 is a graph depicting the electrolysis current as a function of time for disc-shaped electrode couples submersed in synthetic saliva at 3V DC;

[0018] Fig. 4A is a graph depicting the solution pH level as a function of time for disc-shaped electrode couples submersed in synthetic saliva at 3V DC;

[0019] Fig. 5 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with Ni-plated electrodes submersed in synthetic saliva;

[0020] Fig. 5 A is a graph depicting the electrolysis current as a function of time for a lithium

CR2032 battery with Ni-plated electrodes submersed in synthetic saliva; [0021] Fig. 5B is a graph depicting the closed circuit voltage (CCV) as a function of time for a lithium CR2032 battery with Ni-plated electrodes submersed in synthetic saliva;

[0022] Fig. 6 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a stainless steel grade 316 positive electrode submersed in synthetic saliva;

[0023] Fig. 6A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a stainless steel grade 316 positive electrode submersed in synthetic saliva;

[0024] Fig. 7 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a stainless steel grade 430 positive electrode submersed in synthetic saliva;

[0025] Fig. 7A is a graph depicting CCV as a function of time for a lithium CR2032 battery with stainless steel grade 430 positive electrode submersed in synthetic saliva;

[0026] Fig. 8 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a stainless steel grade 304 positive electrode submersed in synthetic saliva;

[0027] Fig. 8A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a stainless steel grade 304 positive electrode submersed in synthetic saliva;

[0028] Fig. 9 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a stainless steel grade 304 positive electrode and 55 wt% Cu - 32 wt% Sn -

12 wt% Zn alloy negative electrode submersed in synthetic saliva;

[0029] Fig. 9A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a stainless steel grade 304 positive electrode and 55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy negative electrode submersed in synthetic saliva;

[0030] Fig. 10 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a titanium positive electrode submersed in synthetic saliva;

[0031] Fig. 1 OA is a graph depicting CCV as a function of time for a lithium CR2032 battery with a titanium positive electrode submersed in synthetic saliva;

[0032] Fig. 11 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a gold positive electrode and a nickel negative electrode submersed in synthetic saliva;

[0033] Fig. 1 1 A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a gold positive terminal and a nickel negative electrode submersed in synthetic saliva;

[0034] Fig. 12 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a gold positive electrode and a 55wt % Cu - 32 wt% Sn - 12% Zn alloy electrode submersed in synthetic saliva; [0035] Fig. 12A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a gold positive terminal and a 55wt % Cu - 32 wt% Sn - 12% Zn alloy negative electrode submersed in synthetic saliva;

[0036] Fig. 13 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a gold positive electrode and a grade 304 stainless steel negative electrode submersed in synthetic saliva;

[0037] Fig. 13 A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a gold positive terminal and a grade 304 stainless steel negative electrode submersed in synthetic saliva;

[0038] Fig. 14 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a grade S32750 duplex stainless steel positive electrode and a nickel negative electrode submersed in synthetic saliva;

[0039] Fig. 14A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a grade 2S32750 duplex stainless steel positive electrode and a nickel negative electrode submersed in synthetic saliva;

[0040] Fig. 15 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a grade S32750 duplex stainless steel positive electrode and a 55 wt% Cu -

32 wt% Sn - 12% Zn alloy negative electrode submersed in synthetic saliva;

[0041] Fig. 15 A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a grade S32750 duplex stainless steel positive electrode and a 55 wt% Cu - 32 wt% Sn -

12% Zn alloy negative electrode submersed in synthetic saliva;

[0042] Fig. 16 is a graph depicting the solution pH level as a function of time for a lithium

CR2032 battery with a grade S32750 duplex stainless steel positive electrode and a grade 304 stainless steel negative electrode submersed in synthetic saliva; and

[0043] Fig. 16A is a graph depicting CCV as a function of time for a lithium CR2032 battery with a grade S32750 duplex stainless steel positive electrode and a grade 304 stainless steel negative electrode submersed in synthetic saliva.

DETAILED DESCRIPTION

[0044] Rather than focusing on corrosion reactions, and particularly those believed to occur in the acidic environment of the stomach (as disclosed in the prior art), the inventors discovered the harm caused by ingested coin batteries occurred as a result of cells becoming lodged in the esophagus, where it may sustain prolonged exposure to saliva. Insofar as saliva is effectively a neutral aqueous solution comprised primarily of water, it is necessary to mitigate the effects of electrolysis of saliva occurring when the terminals of the lodged battery create a voltage, as will be described in greater details below. The inventors further determined that the phenomenon is particularly acute with relatively large coin battery sizes (i.e., those having a total cell external diameter of approximately 5-25 mm and a total cell height of approximately 0.5-10 mm; e.g., CR2016, CR2032, etc.) and/or in children or other persons who have an esophagus of comparatively small diameter.

[0045] Thus, the present invention is best understood with a review of the likely electrochemical reactions. The principal reaction is electrolysis of water because the following factors are present: (a) the coin cell itself supplies a DC voltage, ~3V OCV (open circuit voltage); (b) an ionic conductive media (saliva) connects the anode (+) and cathode (-) terminal; and (c) the two terminals and saliva conducting path complete a closed circuit for an electrolysis cell. If the voltage supply of the electrolysis cell is high enough to overcome the polarization and the 1.23V thermodynamic voltage window for water electrolysis, electrochemical reactions will occur. Indeed, the electrolysis reaction associated with the ingestion of lithium cells is likely more severe than the electrolysis associated with ingestion of alkaline cells. This is because the driving force (the difference in voltage between the cell voltage and theoretical water electrolysis voltage, 1.23 V) is much higher in the case of a 3V lithium cell than in the case of a 1.5V alkaline cell (3.0V-1.23V=1.77V in the case of a lithium cell vs. 1.5V-1.23V=0.27V in the case of an alkaline cell).

[0046] Significantly, the nomenclature for an electrolysis cell is the opposite of that used for a battery. Accordingly, the term "anode" (positive terminal) refers to the electrode subject to an oxidation reaction and the term "cathode" (negative terminal) refers to the electrode subject to the reduction reaction. Also, it should be noted that electrolysis requires application of voltage and, as such, provides a direct contrast to corrosion which typically occurs naturally under ambient conditions.

[0047] Fig. 1 helps illustrate the electrolysis reaction at issue. A simulated Li-Mn0₂

electrochemical coin cell 6 submerged in saliva solution 5. The principal reactions that occur when a cell having these same components is accidentally ingested and lodged in the esophagus of a human are shown, although the cell electrodes are shown as discrete parts. Specifically, cell 6 operates at approximately 3V DC and includes coin cell cup (e.g., the positive electrode container) 12, coin cell can (e.g., the negative electrode container) 20, anode 40 and cathode 50. The anode 40 and cathode 50 comprise materials specifically selected for their compatibility with an intended electrochemical reaction; for example, x Li + Mn0₂→ Li^Mn0₂, in which the Mn undergoes a reduction as the lithium ion enters into the crystal lattice.

[0048] The external surface of the coin cell cup 12 acts as the negative terminal (cathode in an electrolysis cell) and the external surface of the coin cell can 20 acts as the positive terminal (anode in an electrolysis cell). A hydrogen gas evolution reaction takes place on coin cell cup 12 by accepting electrons from battery anode 40, which in this case includes lithium. At the coin cell can 20 (anode in an electrolysis cell), multiple reactions such as metallic dissolution, oxygen gas evolution and possibly chloride oxidation occur and compete with one another. Charge neutrality in saliva solution 5 is preserved by the movement of anions 8 from the cell cup 12 (negative terminal) toward coin cell can 20 (positive terminal) and by the movement of cations 7 in the opposite direction. As metal from coin cell can 20 oxidizes, it loses electrons to battery cathode 50, which is manganese dioxide in this case. Ultimately, the final product at the coin cell can 20 depends on its potential and the solution pH is a consequence of the combined anode and cathode reactions. Further, the solution pH reflects real time product generated in the reaction zone between the esophagus and coin cell; therefore, the solution pH is localized and not necessarily reflective of the pH of the bulk solution (i.e., the remainder of the saliva which is not proximate to the reaction zone).

[0049] Possible electrochemical reactions on the coin cell cup 12 (negative terminal) are shown below when a 3 V lithium coin cell is immersed in a neutral or alkaline saliva solution. Note that the saliva is usually neutral.

(1) 2H₂0 + 2e^" -» H₂i + 20H^" E₀ = -0.83V

(2) 0₂ + 2H₂0 + 4e^" - 40H^' E₀ = -0.4V

[0050] Typically, reaction (1) dominates because the concentration of oxygen in the saliva is too low as the solubility of oxygen in water is limited. Either way, the production of hydroxyl ions (i.e., OH^") increases the pH of the saliva, potentially to a point that may cause alkaline burning of the esophagus. [0051] On occasion, saliva may be acidic in nature. In such situations, the reactions at the coin cell cup 12 are shown below:

(la) 2H⁺ + 2e^" ^ H₂† E_o = - 0.0V

(2a) 0₂ + 4H⁺ + 4e^" -» 2 H₂0 E₀ = 1.23 V

In either case, selection of materials for use at the negative terminal with high hydrogen gas evolution overpotential will shift the dominant reaction from (1) and (2) to (la) and (2a). This has the beneficial effect of reducing or eliminating the hydroxyl formation that can cause localized alkaline burning of esophageal tissues.

[0052] Possible electrochemical reactions on the coin cell can 20 (positive terminal) are shown below when a 3V lithium coin cell is immersed in saliva solution 5 and can 20 comprises nickel at least partially along its surface.

(3) 40ΡΓ - 4e^~ 0₂†+ 2H₂0

(4) Ni - 2e^" + 20FT ^ Ni(OH)₂

[0053] Reaction (4) usually dominates so that the metal constituents in coin cell can 20 tend to oxidize. Indeed, lithium electrochemical coin cell cans are typically nickel-plated, as exemplified by the oxidation of nickel in reaction (4). If coin cell can 20 is composed of other metals, e.g., stainless steel, the iron in these alloys likely will oxidize in a similar reaction. Once the metal surface of coin cell can 20 has been passivated (i.e., by formation of a dense oxide film on the bare metal surface), the oxygen evolution reaction (3) will likely dominate if the voltage is sufficiently high.

[0054] Moreover, as shown below in (3a) and (4a), dissolution of the metal can 20 is also a probable result if the ferrous base metal (normally some type of steel) is exposed and especially to the extent that hydroxide is present (e.g., by way of the aforementioned competing reactions) and/or in an acidic environment (e.g., by way saliva).

(3a) Fe - 2e^" - Fe (in acidic media)

(4a) Fe - 2e^" + 20H^" -» Fe(OH)₂ (in alkaline media) [0055] Any combination of the cathodic processes in reactions (1) through (2a) and anodic processes in reactions (3) through (4a) can complete the electrolysis cell 6 depicted in Fig. 1. For example, the combination of (1) and (3) leads to the following electrolysis reaction in water (i.e., water splitting):

(5) 2H₂0 H₂† + 0₂† ΔΕ_ο = - 1.23 V

[0056] Note that electrolysis reaction (5) has a thermodynamic potential of 1.23 V and the

negative sign for ΔΕ₀ denotes that the reaction is not spontaneous. Consequently, a DC power source of at least 1.23 V is needed to initiate and sustain reaction (5) and, as depicted in Fig.l, coin cell 6 supplies 3V DC.

[0057] Furthermore, if the amount of sodium chloride (NaCl) in the saliva is relatively high, the following electrolysis reaction may occur instead of reaction (5) (discussed earlier):

(6) 2NaCl + 2H₂0 Cl₂† + H₂† + 2NaOH

In reaction (6), one of the products is sodium hydroxide (NaOH), another contributor to high solution pH and a potentially alkaline solution that may be capable of burning human tissue.

[0058] In sum, the conventional electrochemical coin cell 6 depicted in Fig. 1, and the reactions

(1) through (6) associated with its submersion in saliva 5, demonstrate that hydroxide ions are formed from some iteration of electrolysis. Thus, the burns and injuries caused when a coin cell becomes accidentally lodged in the esophagus is likely caused by the high saliva pH created during these reactions, although the reactions and corresponding impact on pH may be highly localized and difficult to detect if the pH is not measured in close proximity to the components at issue. Stated differently, because of mass transport limitations in the esophagus, a person with a lodged coin cell may experience different pH values for the tissue interacting with coin cell can 20 (positive terminal) and the tissue interacting with coin cell cup 12 (negative terminal), with higher pH solutions facing the negative terminal (i.e., coin cell cup 12 in Fig. 1) because of diffusion limitations of the liquids within the esophagus.

[0059] To the extent certain aspects of the invention and its underlying concepts involve saliva and/or saliva-based aqueous solutions, saliva can be represented by the following composition: 0.4g KCl; 0.4g NaCl; 0.906g CaCl₂; 0.560g Na₃PO₄- 12H₂O; 2 ml 10% H₃P0₄; 0.0016g Na₂S; lg urea; and a balance of de-ionized water to make 1 liter of solution. While this formulation is intended to approximate human saliva in a manner that is standardized, small variations and or actual human saliva may be used as substitutes although, in such instances, deviations from the representative formulation will be duly noted.

[0060] A first aspect of the invention is to mitigate or eliminate the damaging electrochemical mechanisms that may lead to injuries from inadvertent coin cell ingestion through the proper selection of materials and cell design considerations. For example, the new material

combinations for the exterior of the coin cells according to the invention hinder or prevent these reactions from occurring. Selecting these material combinations to mitigate or eliminate these electrochemical reactions is a complex endeavor, requiring a thorough understanding of the principal factors that affect the reaction and damage mechanisms. Additionally, the selections cannot be arbitrary and proper consideration must be given to the chemical compatibility, cost and ease of high speed and high volume manufacturing techniques inherent to the battery industry.

[0061] In one embodiment, the electrochemical coin cells disclosed according to the invention reduce the likelihood that the cathodic processes in reactions (1) and (2), or (la) and (2a), occur on the coin cell cup 12 in Fig. 1. Fundamental testing of the material combinations referenced for these novel cells substantiates this conclusion. For example, employing coin cell positive and negative terminal materials with high overpotential for the reactions in (1) and (2), and (la) and (2a), and/or increasing the overpotential for metallic oxidation (M - ne^"→ Mⁿ⁺, where M denotes a metallic material used for the positive terminal surface) reduces or eliminates these electrochemical reactions, keeping all other factors constant, including the ~3V DC from the coin cell itself.

[0062] Another approach is to select cell electrode materials that may be prone to dissolution, oxygen evolution and the production of insoluble, non-hydroxide reaction products (at least to a modest degree) when submersed in saliva under 3 VDC. Formation of such insoluble, non- hydroxide reaction products would occur preferentially or exclusively, thereby inhibiting the unwanted hydroxyl reactions noted above. In this approach, a sufficient amount of the selected material should be provided to insure that the base material (i.e., the material that is prone to electrolysis) is not exposed for substantial periods of time in which the coin cell might still be outputting a voltage above the desired or safe level, typically 2.8 volts or 2.0 volts. [0063] In another embodiment, the selected materials may be clad, coated or deposited on the cell and, more specifically, on surfaces of the cell that are likely to be exposed to saliva in the event of accidental ingestion. Formation of such coatings must be complete and uniform, as even small fissures, pin holes or other imperfections might provide sufficient reaction sites for the unwanted reactions to occur along the underlying base material. If complete coverage is not achieved or if the coating degrades in situ (i.e., owing to anodic bias, reaction with saliva, etc.), then such coatings will not be suitable. Ultimately, actual experimentation should be conducted, as the inventors have discovered that, while components made of solid gold exhibit the desired properties of the invention, gold coatings of 1.4 microns (approximately 56 microinches) may not be sufficient to provide consistent and repeatable performance.

[0064] As used throughout this specification, irrespective of whether in reference to the anode or the cathode container, the term "cladding" or "cladded layer" refers to a continuous, standalone layer of a material that is essentially free from any pin holes or other imperfections. Thus, as a non-limiting example, a titanium-cladded stainless steel would comprise a discrete layer of titanium that is attached to a stainless steel substrate through any variety of means (e.g., mechanical, chemical, adhesive, welding, etc.). Among other things, the use of cladded materials such as these enables the selection of a substrate that is better suited to a particular manufacturing process. Again, as a non-limiting example, the selected cladded-material might possess the desired overpotenial and other characteristics of an electrolysis-resistant container (as described throughout this specification) whereas the substrate might exhibit magnetic properties. Obviously, the orientation of the cladded-material versus the substrate will be such so that the exterior of the component/container will be consistent with the invention described herein, while at the same time, the inner-facing portions of the substrate will be compatible and non-reactive with the cell active materials and electrolyte.

[0065] Notably, the use of cladded-materials will result in an exposed edge, e.g., terminal edge

23 as shown in Figs. 2 and 3, where a cross-section including both the cladded layer and the substrate is potentially exposed in a manner that is not desired. In such cases, a sealant may be applied in order to block any unwanted reactions. For example, a polymeric sealant, and more preferably UV-curable sealants, can be applied around the rim and gasket area to cover the exposed edge.

[0066] Figs. 2 and 3 depict one arrangement for an electrochemical coin cell 10 that is well- suited to aspects and embodiments of the present invention, although the coin cell 10 may assume various alternative orientations and arrangements of components. Further, the specific devices and processes illustrated in the attached drawings and described herein are exemplary embodiments of the inventive concepts defined in the appended claims. Hence, precise dimensions and physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting except to the extent that such dimensions or characteristics are inherent to producing the desired reactions.

[0067] Electrochemical coin cell 10 includes an anode terminal 12 (i.e., the cell cap or cup) including a closed end 13, an open end 14 with a terminal edge 15, and side wall 16 extending between closed end 13 and open end 14 (Figs. 2 and 3). In the nomenclature of a battery, anode terminal 12 serves as the negative electrode for the coin cell 10. Further, anode terminal 12 is comprised of an electron-conducting material that is resistant to electrochemical reactions that form hydrogen gas upon exposure to saliva-containing solutions (e.g., saliva solution 5). For example, anode terminal 12 may be made of titanium metal, a titanium alloy, a copper-tin-zinc alloy (40-65 wt % Cu, 30-45 wt % Sn and 4-15 wt % Zn), nickel metal, stainless steel or another electronic conductor that has high hydrogen gas evolution overpotential. Further, materials for anode terminal 12 may be selected that possess an onset potential for hydrogen gas evolution in saliva in the approximate range of -0.66V to -1.96V vs. a standard hydrogen electrode (SHE). Preferably, the material selected for anode terminal 12 exhibits an onset potential for hydrogen gas evolution in saliva significantly lower than -0.66V and closer to -1.96V vs. SHE.

[0068] Alternatively, the exterior surface 17 of anode terminal 12 may be plated, coated,

sputtered, cladded, or otherwise covered with any of these metals. If exterior surface 17 is covered in this fashion, anode terminal 12 may contain a balance of material (e.g., grade 430 stainless steel) that is sufficiently magnetic to facilitate large-scale manufacturing (e.g., methods that rely on magnetically-driven pick-and-place fabrication methods employing robots). Another benefit of configuring exterior surface 17 with plated, coated, sputtered or cladded titanium metal or titanium alloys is that less of these relatively expensive materials are needed to effect the desired increase in hydrogen gas evolution overpotential compared to fabricating anode terminal 12 completely out of these materials.

[0069] The electrochemical coin cell 10, as depicted in Figs. 2 and 3, also includes a cathode terminal 20 (i.e., the cell can) including a closed end 21, an open end 22 with a terminal edge 23, and a side wall 24 extending between closed end 21 and open end 22. Cathode terminal 20 serves as the positive electrode for the coin cell. In addition, cathode terminal 20 is comprised of an electron-conducting material resistant to metallic dissolution and electrochemical reactions that form oxygen gas upon exposure to saliva-containing solutions. In particular, cathode terminal 20 may be formed of titanium, a titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, or another electronic conductor that resists metallic dissolution upon an anodic bias and preferably has high oxygen gas evolution overpotential. Closed end 21 may also be provided with a composition comprising titanium metal, a titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, or another electronic conductor that resists metallic dissolution upon an anodic bias and preferably has high oxygen gas evolution overpotential. Further, materials for cathode terminal 20 may be selected that possess an onset potential for anodic reactions in saliva in the approximate range of +0.6V to +2.4V vs. SHE. Preferably, the material selected for cathode terminal 20 exhibits an onset potential for anodic reactions in saliva significantly higher than +0.6V and closer to +2.4V vs. SHE.

[0070] According to one embodiment, the closed end 21 contains a balance of grade 2 titanium.

In other embodiments, closed end 21 contains a balance of grade S32750 duplex stainless steel or gold. In addition, an exterior surface 25 of closed end 21 may be provided with a coating, plating, cladding, or other covering that consists essentially of titanium, a titanium alloy, titanium nitride, grade 304 stainless steel, grade S32750 duplex stainless steel or gold. If exterior surface 25 is plated, sputtered, coated, cladded or otherwise covered in this fashion, cathode terminal 20 may contain a balance of material (e.g., grade 430 stainless steel) that is sufficiently magnetic to facilitate large-scale manufacturing (e.g., methods that rely on magnetically-driven pick-and-place fabrication methods employing robots). Another benefit of configuring closed end 21 with an exterior surface 25 that is plated, coated, sputtered or cladded with titanium, gold or other suitable precious metals is that less of these relatively expensive materials are needed for the desired increased oxygen gas evolution overpotential and resistance to metallic dissolution compared to fabricating closed end 21 completely out of these materials.

[0071] Another metric for evaluating the effectiveness of a proposed material is anodic

polarization scanning in saliva, and particularly with reference to a material containing nickel (which is known to undergo the aforementioned, unwanted electrolysis when exposed to saliva at voltages in excess of 2.0 volts). Materials exhibiting less than 0.05 mA/cm² of current at 0.6 volts during the anodic polarization are desired, with materials exhibiting less than 0.03 mA/cm² being even more preferred. For the sake of comparison, nickel containing materials exhibit 0.86 mA/cm² of current at 0.6 volts, while solid gold exhibits only 0.03 mA/cm². Notably, gold- plated substrates exhibited varying levels of performance (from 0.05 mA/cm 2 to 0.52 mA/cm 2 at 0.6 volts), thereby providing further verification that actual experimentation with plated materials is useful before drawing conclusions as to their viability as candidate materials for this invention.

[0072] While localized pH levels are believed to be responsible for the injuries caused by

ingested cells, experimental results have demonstrated that measurement of pH values alone may be insufficient to determine the efficacy of any proposed solution. The inventors have determined that pH changes are sensitive to experimental conditions, including exposed surface area of the positive and negative terminals, quantity of saliva present and the means and location of the pH measurement device. Thus, any pH measurements are most useful when considered in a comparative context only. At present, the inventors are unaware of any published and standardized clinical test regimen for mimicking or quantifying the effect of coin cell ingestion on the human body.

[0073] Another means for evaluating the extent of unwanted electrolytic activity between the terminals when a "live" cell is placed in saliva is to quantify the amount of metal that has been dissolved into the saliva solution. As an example, elemental analysis by Inductively Coupled Plasma (ICP) mass spectrometry can be used to determine the presence of metallic species. In the same manner, such quantification measurements are also useful in determining the efficacy of coatings or cladded materials.

[0074] Coin cell 10 further includes a gasket 30 that provides a seal between anode terminal 12 and cathode terminal 20 (Figs. 2 and 3). The gasket 30 is typically made from an electrically nonconductive, elastomeric material, capable of providing a compressive seal between anode terminal 12 and cathode terminal 20. The material used for gasket 30 must also be selected with reference to its stability in the presence of an electrolyte, its resiliency and its resistance to cold flow. Suitable materials for gasket 30 include the following: nylon, polytetrafluoroethylene, fluorinated ethylene-propylene, chlorotrifiuoroethylene, perfluoroalkoxy polymer, polyvinyls, polyethylene, polypropylene, polystyrene, polysulfone and the like.

[0075] The electrochemical coin cell 10 also includes an electrolyte 34. Various materials can be employed for electrolyte 34 as understood by one with ordinary skill in the art. For example, electrolyte 34 may be composed of a composition of at least one lithium salt dissolved in an organic solvent or a blend of organic solvents. Suitable salts for use in lithium coin cells are lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonimide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, or their combination. Common organic solvents used in lithium coin cells are propylene carbonate and 1 ,2-dimethoxyethane.

[0076] The electrochemical cell 10 also has an anode 40 disposed in electrical connection with anode terminal 12. As understood by those with ordinary skill in the art, the anode 40 can be composed of various alkaline metals and their alloys with aluminum or magnesium provided that the composition is suitable for serving as an anode in an electrochemical cell. In one

embodiment, anode 40 is primarily composed of lithium material suitable as an anode in an electrochemical cell with a cathode that consists primarily of manganese dioxide.

Electrochemical cell 10 also includes cathode 50 arranged to be in electrical connection with cathode terminal 20. As also understood by those with ordinary skill in the art, cathode 50 can be composed of various materials suitable for use as a cathode in a lithium-based electrochemical cell. In one embodiment, cathode 50 is primarily composed of manganese dioxide.

[0077] Electrochemical coin cell 10 further includes a separator 38 disposed between anode 40 and cathode 50 for providing insulation therebetween. Separator 38 can be composed of any of a variety of polymeric materials, for example, that provide electrical insulation between anode terminal 12 and cathode terminal 20. For example, separator 38 may be formed from a polypropylene or polyethylene nonwoven film with thickness of -20-60 μπι.

[0078] As also demonstrated by Figs. 2 and 3, electrochemical cell 10 can be configured in a button- or coin-cell configuration with a total cell external diameter 54 and total cell height 58. The total cell external diameter 54 may be sized from -5-25 mm and the total cell height 58 may be -0.5-10 mm. It is generally understood that button or coin cells with these dimensions are most likely to lodge in the esophagus upon accidental ingestion. For example, electrochemical cell 10 may be made in a CR2016 configuration as defined by the International Electrotechnical Commission (IEC) with total cell external diameter 54 having a diameter of 20 mm and total cell height 58 having a thickness of 1.6 mm.

[0079] Another embodiment of the invention relates to an electrolysis-resistant lithium primary cell having an initial open circuit voltage in excess of 2.0 volts and, more preferably, in excess of 2.8 volts. Alternatively, the lithium primary cell has a nominal voltage of about 3.0 volts and/or of about 2.8 volts. The surface of the externally exposed components of this cell will comprise materials that possess the requisite hydrogen overpotential and/or other characteristics relating to electrolysis reactions, and more specifically unwanted electrolysis under exposure to saliva, as described above. All of the additional features, components and characteristics described in the preceding paragraphs above are applicable to this embodiment.

[0080] Another embodiment of the invention relates to an electrochemical cell having an open circuit voltage in excess 2.0 volts and, more preferably, in excess of 2.8 volts. Alternatively, the lithium primary cell has a nominal voltage of about 3.0 volts and/or of about 2.8 volts. The exposed exterior of the cell, and more specifically, the exterior surface of the negative electrode container and the positive electrode container, comprises materials that do not evolve hydroxide and/or otherwise cause electrolysis of the aqueous solution. For example, the materials for one or both of the negative and positive container exterioir(s) possess the requisite hydrogen overpotential and/or other characteristics relating to electrolysis reactions, and more specifically unwanted electrolysis under exposure to saliva, all as described in the preceding above. All of the additional features, components and characteristics described above are applicable to this embodiment.

[0081] Another aspect of the invention relates to a method of constructing and/or manufacturing of an electrolysis-resistant coin cell. The method comprises providing a negative electrode active material comprising lithium and , disposing said materials in separate halves of an electrically conductive container and providing a nonaqueous, organic liquid electrolyte prior to hermetically sealing the halves of the conductive container to create a battery. The compositions of the halves of the conductive container are selected to possess the requisite hydrogen overpotential and/or other characteristics relating to electrolysis reactions, and more specifically unwanted electrolysis under exposure to saliva, all as described above.

[0082] Another aspect of the invention is the provision and/manufacture of an electrolysis

resistant battery to avoid injuries associated with ingestion of said battery, as well as a method of for avoiding injuries caused by battery ingestion. In these aspects, any of the aforementioned battery designs and constructions may be provided. At their core, the inventive method involves manufacturing an electrolysis resistant battery and providing said battery for sale and/or use by a consumer.

[0083] As used throughout this specification, duplex stainless steel is any dual phase steel

exhibiting both ferritic and austenitic crystal structure. Any reference to particular grades should be presumed to be with reference to the standards published by ASTM International, unless the context indicates some other reference known to those having ordinary skill in the field of metallurgy. In view of the foregoing, as well as all of the information contained in the examples below, an electrochemical coin cell having ANY combination of the following traits is contemplated:

• an anode and, more preferably, an anode disposed in electrical connection with the anode terminal;

• the anode comprising a material selected from the group consisting of lithium and lithium alloys;

• a cathode and, more preferably, a cathode disposed in electrical connection with the cathode terminal;

• the cathode comprising manganese dioxide;

• an electrolyte and, more preferably, an electrolyte comprising a nonaqueous material capable of facilitating electrochemical reactions producing an open circuit voltage in excess of at least 2.8 volts or a nominal voltage of 3.0 volts;

• a gasket and, more preferably, a gasket disposed and providing a seal between the anode terminal and the cathode terminal;

• a separator disposed between the anode and the cathode and, more preferably, also

providing electrical insulation between the anode and the cathode;

• a total cell external diameter of between 5 and 25 mm and a total cell external height of between 0.5 and 10 mm;

• an anode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the anode terminal, wherein the closed end of the anode terminal: (a) is configured as an electronic conductor and comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution and/or (b) consists essentially of an electronic conductor resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution;

• a cathode terminal comprising a closed end, an open end with a terminal edge and a side wall extending between the closed and open ends of the cathode terminal, the closed end of the cathode terminal: (a) is configured as an electronic conductor and comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution and/or (b) consists essentially of an electronic conductor resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution;

wherein the closed end of the anode terminal comprises or consists essentially of a material with substantial hydrogen gas evolution overpotential during exposure to the saliva-containing solution and, more preferably, wherein the material with substantial hydrogen gas evolution overpotential during exposure to the saliva-containing solution exhibits an onset potential for hydrogen gas evolution in the saliva-containing solution in the range of approximately -0.66V to -1.96V versus a standard hydrogen electrode; wherein the closed end of the anode terminal comprises or consists essentially of a material that conducts electrons and is resistant to reactions forming hydrogen gas during exposure to the saliva-containing solution and, more preferably, wherein the material with substantial hydrogen gas evolution overpotential during exposure to the saliva- containing solution exhibits an onset potential for hydrogen gas evolution in the saliva- containing solution in the range of approximately -0.66V to -1.96V versus a standard hydrogen electrode;

wherein the closed end of the cathode terminal comprises or consists essentially of a material that resists metallic dissolution and has substantial oxygen gas evolution overpotential during exposure to the saliva-containing solution and, more preferably, wherein the material that resists metallic dissolution and has substantial oxygen gas evolution overpotential during exposure to the saliva-containing solution exhibits an onset potential for anodic reactions in the saliva-containing solution in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode;

wherein the closed end of the cathode terminal comprises or consists essentially of a material that conducts electrons and is resistant to reactions causing metallic dissolution and forming oxygen gas during exposure to the saliva-containing solution and, more preferably, wherein the material that resists metallic dissolution and has substantial oxygen gas evolution overpotential during exposure to the saliva-containing solution exhibits an onset potential for anodic reactions in the saliva-containing solution in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode;

wherein the closed end of the anode terminal consists essentially of titanium metal, a titanium alloy, nickel metal, stainless steel or a copper-tin- zinc alloy containing 30 to 45% tin and 4 to 15% zinc alloying elements by weight; • wherein the closed end of the cathode terminal consists essentially of materials selected from the group consisting of titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold and boron-doped diamond;

• wherein the closed end of the cathode terminal consists essentially of grade 2 titanium, grade 304 stainless steel, grade S32750 duplex stainless steel or gold; and

• wherein the closed end of the cathode terminal further comprises a base consisting

essentially of stainless steel or magnetic stainless steel, and an outer surface consisting essentially of titanium metal, a titanium alloy, or titanium nitride.

Additionally, in view of the foregoing and the information contained in the examples below, an electrochemical coin cell having ANY combination of the following traits is contemplated:

• internal components including an anode, a separator and a cathode capable of producing an output open circuit voltage of at least 2.8 voltage in the presence of a non-aqueous electrolyte;

• a flat cylindrical container encasing the internal components having an external diameter between 5 and 25 millimeters and an external height of between 0.5 and 10 millimeters, the container comprising an anode terminal casing and a cathode terminal casing with an electrically insulating gasket disposed therebetween;

• wherein the anode terminal casing has an internal surface which maintains electrical contact with the anode and an external surface comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution;

• wherein the cathode terminal casing has an internal surface which maintains electrical contact with the cathode and an external surface comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva- containing solution;

• wherein the anode includes an active material consisting essentially of lithium or a lithium-based alloy and the cathode includes an active material comprising manganese dioxide;

• wherein the external surface of the anode terminal casing exhibits an onset potential for hydrogen gas evolution in the saliva-containing solution in the range of approximately - 0.66V to -1.96V versus a standard hydrogen electrode; • wherein the external surface of the anode terminal casing is selected from the group consisting of: titanium metal, a titanium alloy, nickel metal, stainless steel and a copper- tin-zinc alloy containing 30 to 45% tin and 4 to 15% zinc alloying elements by weight;

• wherein the external surface of the cathode material casing exhibits an onset potential for anodic reactions in the saliva-containing solution in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode;

• wherein the external surface of the cathode terminal casing is selected from the group consisting of: titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold and boron-doped diamond;

• wherein the external surface of the cathode terminal casing is selected from the group consisting of: grade 2 titanium, grade 304 stainless steel, duplex stainless steel and gold; and

• wherein the duplex stainless steel is ASTM grade S32750.

Additionally, in view of the foregoing and the information contained in the examples below, a method of manufacturing a coin-shaped battery having an external diameter of 5-25 millimeters and an external height of 0.5-10 millimeters that is resistant to electrolysis when placed in an aqueous solution initially having a neutral pH, having ANY combination of the following traits is contemplated:

• disposing an anode material comprising lithium or lithium alloy inside of a container having an anode terminal, wherein the entire external surface of the anode terminal is made from a material that is resistant to reactions forming hydrogen gas when the final, manufactured cell is submerged;

• disposing a cathode material inside of a container having a cathode terminal, wherein the entire external surface of the cathode terminal is made from a material that is resistant to metallic dissolution and reactions forming oxygen gas when the final, manufactured cell is submerged;

• positioning a separator and insulating gasket between anode and the cathode and sealing the container to create a final, manufactured cell;

• wherein the external surface of the anode terminal is selected to exhibit an onset

potential for hydrogen gas evolution when the final, manufactured cell is submerged in the range of approximately -0.66V to -1.96 V versus a standard hydrogen electrode; • wherein the external surface of the cathode terminal is selected to exhibit an onset

potential for anodic reactions when the final, manufactured cell is submerged in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode;

• wherein the external surface of the cathode terminal is selected from the group consisting of: titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold and boron-doped diamond;

• wherein the external of the cathode terminal is selected from the group consisting of: grade 2 titanium, grade 304 stainless steel, duplex stainless steel and gold;

• wherein the anode terminal is made from a cladded material; and

• wherein the cathode terminal is made from a cladded material.

[0087] Finally, in view of the foregoing and the information contained in the examples below, a a coin-shaped battery having an external diameter of 5-25 millimeters and an external height of 0.5-10 millimeters that is resistant to electrolysis when placed in an aqueous solution initially having an initial pH of 7.0 or less, has ANY combination of the following traits is contemplated:

• an exposed surface of an anode terminal consisting essentially of: titanium metal, a

titanium alloy, nickel metal, stainless steel, a copper-tin-zinc alloy containing 30 to 45% tin and 4 to 15% zinc alloying elements by weight or combinations thereof;

• an exposed surface of a cathode terminal consisting essentially of: titanium metal,

titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, grade 2 grade 304 stainless steel, grade S32750 duplex stainless steel or combinations thereof; and

• further comprising an anode active material having lithium and a cathode active material having manganese dioxide.

[0088] The nature of the invention, its use and advantages are further demonstrated in the

following examples that compare the results from electrolysis tests of conventional

electrochemical cells to novel cells constructed by the inventors. These novel cells are examples of the present invention and reflect the inventors' discovery of the electrochemical mechanisms underlying the damage caused by inadvertent coin cell ingestion and lodging in the esophagus. EXAMPLE 1

[0089] A bench-top electrolysis cell was fabricated for the purpose of assessing pH and current generation as a function of time for mock-ups of electrodes consistent with the anode and cathode terminal materials used in conventional electrochemical cells and terminals configured as examples of the present invention. Positive and negative electrodes to simulate cathode and anode terminals of an electrochemical cell, respectively, were prepared as discs, each with an estimated exposed area of 3.5 cm². This area is approximately equal to the external area of CR20xx (e.g., CR2032, CR2016, etc.) lithium electrochemical coin cell configurations. For testing, the disc electrodes were configured in an assembly facing each other. Two layers of separator material were then placed between the disc electrodes and a pH probe was placed near the negative electrode to measure the pH changes during the test.

[0090] The finished electrode assembly was then immersed in a synthetic saliva solution

prepared with the following composition: 0.4g KC1; 0.4g NaCl; 0.906g CaCl₂; 0.560g

Na₃P0₄- 12H₂0; 2 ml 10% H₃P0₄; 0.0016g Na₂S; lg urea; and a balance of de-ionized water to make 1 liter of synthetic saliva solution. The chloride concentration of this synthetic saliva solution was equivalent to a 0.03M chloride solution. Electrolysis was then initiated using an EG&G 273 A potentiostat to apply 3.0V DC voltage across the electrode couples. No stirring was employed to assist mass transfer, the location of the pH probe was kept constant and the tests were run for about 80 minutes.

[0091] Table 1 below lists the electrode couples tested under this set-up. The Ni(+)/Ni(-) couple was designated the control because typical Li-Mn0₂ electrochemical cells employ anode and cathode terminals with nickel plating. Titanium and grade 304 stainless steel positive electrodes were chosen as these materials resist anodic dissolution and possess high oxygen evolution overpotential with respect to reactions (3) and (4). Other baseline tests and theoretical analyses suggested that a copper-tin-zinc alloy (40-65 wt% Cu, 30-45 wt% Sn and 4-15 wt% Zn) as the negative electrode would also stop or mitigate the deleterious electrolysis reactions. The copper- tin-zinc alloy tested here was in the form of Miralloy®-plated (a trademark for certain of Umicore Galvanotechnik Gmbh's (a/k/a Umicore Electroplating) plating compositions) steel, the Miralloy® plating having the following approximate composition: 55 wt% Cu, 32 wt% Sn and 12 wt% Zn. TABLE 1

[0092]

[0093] Referring to Fig. 4, current is shown in amps (A) as a function of elapsed time (minutes) for each of the couples in Table 1 after they were immersed in the synthetic saliva solution and subjected to 3.0V DC. As Fig. 4 demonstrates, electrolysis current for the Ni(+)/Ni(-) control couple quickly stabilized at 22-25 mA. After the testing had been completed, the solution was greenish with some white precipitates, indicating dissolved nickel ions and some nickel oxides. As shown in Fig. 4A, the pH of the saliva solution with the Ni(+)/Ni(-) electrodes quickly rose to a maximum of pH level of -13, demonstrating that the saliva had high alkalinity and might be capable of burning human tissue.

[0094] Conversely, as shown in Fig. 4, the electrolysis current for the Ti(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy-plated steel(-) couple is significantly reduced to less than 1 mA. The solution for this test remained clear after the testing had been completed. Indeed, as shown in Fig. 4A, the pH of the saliva solution with the Ti(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy- plated steel(-) couple only slightly rose to a pH level of -7.5 after 60 minutes on test. Thus, the use of this electrode system in the electrochemical coin cell 10 dramatically reduced the electrolysis in this test.

[0095] For its part, the 304 stainless steel(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy-plated steel(-) couple reduced the electrolysis current below that observed for the Ni(+)/Ni(-) couple and above the Ti(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy-plated steel(-) couple (Fig. 4). The solution for this couple included brownish precipitates, likely indicative of dissolution of iron from the stainless steel in the electrode. Fig. 4A also demonstrates that the pH of the saliva solution with the 304 stainless steel(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy-plated steel(-) couple rose significantly during the duration of the test to a pH level of-13 after 80 minutes on test. That being said, the rate of pH increase for the 304 stainless steel(+)/55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy-plated steel(-) couple was lower than that of the Ni(+)/Ni(-) couple. Consequently, the use of this system in the electrochemical coin cell 10 likely will delay an increase in solution pH from the electrolysis, potentially providing more time for a person to receive medical attention associated with accidental coin cell ingestion.

EXAMPLE 2

[0096] In this example, a bench-top electrolysis cell was fabricated for the purpose of assessing pH and closed circuit voltage (CCV) drop as a function of time for mock-ups of electrodes connected to an actual lithium electrochemical coin cell (CR2032) immersed in a synthetic saliva solution similar to that of Example 1. A marginal decrease in cell CCV for a mock-up of a given electrode configuration is likely indicative of a system that will mitigate esophagus damage. Similarly, marginal changes to saliva solution pH during and after the duration of the test also likely point to a system that will mitigate esophagus damage from battery/human tissue electrolysis.

[0097] The electrode materials studied in this example are listed below in Table 2.

TABLE 2

Electrode terminal materials

titanium grade 2

stainless steel grade 316

stainless steel grade 304

stainless steel grade 430

nickel (control)

Cu-Sn-Zn alloy-plated (~ 55 wt%

Cu, 32 wt% Sn and 12% Zn) steel

[0098] The materials listed in Table 2 were cut into small strips (0.156 in x 1 in) for use as electrodes. Note that the configuration in Example 2 with nickel positive and negative electrodes serves as the control because typical lithium electrochemical coin cells are fabricated with a nickel-plated stainless steel can and cup. In addition, synthetic saliva was prepared according to the formula used in Example 1.

[0099] The electrolysis cell used in this example consisted of two electrode strips immersed

0.3125 in deep into the saliva solution. The distance between the electrodes was set at -0.5 in. The total amount of saliva used in the cell was 5 ml. The electrodes for each test configuration (see Table 3 below) were connected to an un-discharged lithium CR2032 coin cell that served as the power source for electrolysis of the saliva. Cell voltage was measured using a DAQ Book 56 Data Acquisition System. A Corning pH meter (Model 350) with a micro pH probe (Accumet from Cole-Parmer catalog# S-55500-45) was placed near the surface of the negative electrode to record the pH of the saliva during the test. The initial cell OCV was -3.2-3.3 V and the synthetic saliva had an initial pH level of -6.

[00100] In this example, the duration of the test was set at approximately 90 minutes for each electrode couple tested that ultimately produced a significantly alkaline synthetic saliva solution (pH~12) near the negative electrode. For those electrode couples tested that produced only minor changes to the solution pH level near the negative electrode, the test was run longer with a duration of at least 5-6 hours. After the completion of a test run for a particular electrode configuration, a new set of electrodes, saliva solution (5 ml), and CR2032 coin cell were used for the next run. Table 3 below provides a summary of the tested electrodes, solution pH (at 15, 90 and 400 minutes) and cell CCV (at 90 and 400 minutes). Further, in Table 3, "n" corresponds to the number of times the particular electrode combination was tested.

TABLE 3

[00101]

13 SS 304 Ti 1 ~ 6 4-6 4-6 >3.1V >3.1V

14 Ti SS 304 1 4-5 8 n/a <2.8V n/a

15 Ni Ti 2 ~ 6 4-6 4-6 >3.1V >3.1V

55 wt% Cu ~ 32

wt% Sn 12

16 Ti 1 ~ 6 4-6 4-6 >3.1V >3.1V wt% Zn alloy- plated steel

[00102] As demonstrated in Table 3 and Figs. 5, 5A and 5B, the control CR2032 lithium coin cell with nickel-plated electrodes (Ni(+)/Ni(-)) experienced significant electrolysis upon submersion in synthetic saliva. The pH level of the saliva near the negative electrode was -5.7 at the beginning of the test and increased rapidly to a pH level of 12.2 after 15 minutes (Fig. 5).

Thereafter, the pH level of the solution leveled off and remained relatively constant for the duration of the test. The electrolysis current for the Ni(+)/Ni(-) control couple was 3.2mA at the beginning of the test, increased to 4mA after 20 minutes and remained at 4mA for the duration of the test (Fig. 5A).

[00103] Although the electrolysis current level for the Ni(+)/Ni(-) couple in this example was lower (4mA) than the electrolysis current level observed for the Ni(+)/Ni(-) test couple depicted in Fig. 4 from Example 1 (22-25 mA), the results for this example are indicative of significant electrolysis. Indeed, gas evolution near the negative electrode (hydrogen gas) was observed as soon as the test was initiated. Also, the solution in the vicinity of the positive electrode appeared green after the test had been completed, likely indicative of nickel cation formation. In addition, the positive electrode itself had been significantly corroded with a large, greenish deposit, likely Ni(OH)₂. Still further, Fig. 5B shows that the closed circuit voltage (CCV) for the Ni(+)/Ni(-) couple tested in this example dropped appreciably to a level below 3.0V within a few minutes of testing and to a level below 2.8V within 30 minutes of testing.

[00104] Also note that the differences between the electrolysis current levels for the control

Ni(+)/Ni(-) couples tested in this example and the prior example depicted in Figs. 4 and 5A can be explained by the differences in electrode surface area between the tests. In Example 1 (Fig. 4), the negative electrode surface area was ~3.5 cm² (a disc electrode) whereas in the test outlined in Example 2, the electrode surface area was -0.67 cm² (a strip electrode). The dimensions of the portion of the strip electrode immersed in saliva outlined in Example 2 are 0.008 in (thickness) x 0.156 in (width) x 0.3125 in (length), resulting in an exposed surface area of 0.67 cm² (0.156 in x 0.3125 in x 2 + 0.3125 in x 0.008 in x 2 + 0.156 in x 0.008 in x 1 = 0.104 in²; and 0.104 in² x 2.54 cm²/in² = 0.67 cm²). Consequently, more electrode surface area was in contact with the synthetic saliva in the tests detailed in Example 1 and, accordingly, the

electrolysis current level was appreciably higher for those tests.

[00105] Figs. 6 and 6A (and Table 3) depict the results from the electrolysis testing of lithium

CR2032 cells with a stainless steel grade 316 (SS 316) positive electrode and a nickel, stainless steel grade 430 or stainless steel grade 304 negative electrode. Similarly, Figs. 7 and 7A depict the electrolysis testing of CR2032 cells with a stainless steel grade 430 (SS 430) positive electrode and stainless steel grade 304 negative electrode. In particular, Figs. 6 and 7

demonstrate that the pH levels increased for all of the SS 316 positive electrode and SS 430 couples in this group, but not as quickly as the control Ni(+)/Ni(-) couple (compare to Fig. 5). However, the pH increased for all of the couples to a pH level above 1 1 in 40-50 minutes of testing, indicating electrolysis of the synthetic saliva. In addition, Fig. 6A shows that the CCV for cells tested with SS 316 positive electrodes dropped during the duration of the test, but not to the extent observed for the Ni(+)/Ni(-) couple (compare to Fig. 5B). Further, Fig. 7A shows that the CCV for cells tested with SS 430 positive electrodes dropped during the duration of the test, and at a rate comparable to that of the Ni(+)/Ni(-) couple. Overall, therefore, stainless steel grade 316 and 430 as positive electrode materials offer some benefit over nickel plating insofar as they delay the increase in saliva pH. In turn, this delay associated with an increase to pH may give a person more time to seek medical attention upon accidental ingestion of a coin cell.

[00106] As demonstrated in Figs. 8, 8A, 9 and 9A (and Table 3), the electrolysis testing of

lithium CR2032 cells with a stainless steel grade 304 (SS 304) positive electrode and a nickel, stainless steel grade 430, stainless steel grade 304 or 55 wt% Cu - 32 wt% Sn - 12 wt% Zn alloy negative electrode produced results comparable to those shown in Figs. 6, 6A, 7 and 7A for the SS 316 and SS 430 positive electrode systems. Figs. 8 and 9 show that the pH levels increased for all of the SS 304 positive electrode couple combinations tested in this group (see Table 3), but not as quickly as the Ni(+)/Ni(-) control group depicted in Fig. 5. Similarly, Figs. 8A and 9A demonstrate that the CCV for cells tested with SS 304 positive electrodes dropped through the duration of the test but, again, not to the extent observed for the Ni(+)/Ni(-) couples.

[00107] Furthermore, the solution pH levels for all SS 304 positive electrode groups tested did not rise above a pH level of 9 until at least 15 minutes of testing (Figs. 8 and 9). This is somewhat in contrast to a few of the results from the SS 316 positive electrode and SS 430 positive test groups that yielded a rapid increase in pH to a pH level above 1 1 after 15 minutes on test (see Figs. 6 and 7 test groups - SS 316(+)/SS 304(-), SS 316(+)/Ni(-), 2^nd run and SS 430(+)/SS 304(-)). For example, both the second run of the SS 316 positive electrode and nickel negative electrode configuration and the SS 430 positive electrode and SS 304 negative electrode configuration yielded a pH level of ~1 1.5 after only 15 minutes on test. Consequently, SS 304 positive electrode coin cell systems appear to perform slightly better than coin cell systems with SS 316 or SS 430 positive electrodes, and much better than coin cell systems with nickel positive electrodes.

[00108] Finally, Figs. 10 and 10A (and Table 3) depict the electrolysis testing results for CR2032 lithium coin cells with a titanium positive electrode (Ti(+)) immersed in synthetic saliva. For this test group, the titanium positive electrode signifies the use of titanium as the positive coin cell can itself or as a coating on the exterior surface of the can. As demonstrated by Fig. 10, the pH of the saliva near the surface of the negative terminal did not increase above 7 for all coin cells tested with titanium as the positive electrode material. Consequently, the use of titanium as a positive electrode in a lithium coin cell configuration mitigates the electrolysis of synthetic saliva. Indeed, at the duration of these tests, about 400 to 500 minutes, the pH levels in the synthetic saliva remained below a pH level of 7 and above a pH level of 4. Because many common foods are acidic with pH levels well below 4 (e.g., pH = 3.2-4.0 for cherries; pH = 2.9- 3.3 for apples), the fact that the saliva pH for some of these tests ended up near 4 is not a significant concern.

[00109] Similarly, Fig. 10A demonstrates that lithium coin cells with a Ti(+) electrode

configuration do not appreciably drop in CCV after immersion in synthetic saliva. After many hours on test, these cells with titanium positive electrodes maintained 3.1V - a drop of only 0.1V from the beginning of the test. As before, these results point to the use of titanium as a positive electrode to mitigate esophagus damage from accidental ingestion of a coin cell battery.

EXAMPLE 3

[00110] In this example, a bench-top electrolysis cell was employed again for the purpose of assessing pH and closed circuit voltage (CCV) drop as a function of time for mock-ups of electrodes connected to an actual lithium electrochemical coin cell (CR2032) immersed in a synthetic saliva solution. The testing configuration used for this example and saliva solution were the same as that employed for Example 2. The electrode materials tested here are listed below in Table 4. Various combinations of these materials were configured and subjected to bench-top testing in the manner described earlier in connection with Example 2. Here, gold and duplex stainless steel grade S32750 were selected as the positive electrode candidate materials because when configured in test coupons and subjected to an anodic bias, they exhibited a high onset potential before appreciable current levels were observed. Grade S32750 (e.g., SAF 2507^® made by Avesta Polarit AB on license from AB Sandovik Steel) duplex stainless steel has the following typical composition: Fe - 0.02%C - 0.27%N - 25%Cr - 7%Ni - 4%Mo. The "duplex" aspect of grade S32570 stainless steel is its dual, ferritic/austenitic microstructure that gives it both high strength and corrosion resistance in many environments.

TABLE 4

Table 5 below provides a summary of the results from testing the six combinations of positive and negative electrode materials listed in Table 4. Table 5 also includes the results from the earlier testing of the Ti(+)/Ni(-) and Ni(+)/Ni(-) electrode couples in Example 2 as favorable and control electrode couples for purposes of comparison. In addition, Figs. 11-13A depict closed circuit voltage as a function of time and pH level as a function of time for lithium CR2032 batteries with gold positive electrodes with nickel, 55 wt% Cu - 32 wt% Sn -12 wt% Zn alloy- plated steel and grade 304 stainless steel negative electrodes immersed in synthetic saliva solutions. Similarly, Figs. 14-16A depict closed circuit voltage as a function of time and pH level as a function of time for lithium CR2032 batteries with grade S32750 duplex stainless steel positive electrodes with nickel, 55 wt% Cu - 32 wt% Sn -12 wt% Zn alloy-plated steel and grade 304 stainless steel negative electrodes immersed in synthetic saliva solutions.

TABLE 5

Au Ni 6.7 7.3 2.951

55 Cu-32 Sn-12

Au Zn 5.4 5.3 3.037

Duplex S32750 SS304 8.5 7.2 2.91 1

Duplex S32750 Ni 10 9.3 2.873

55 Cu-32 Sn-12

Duplex S32750 Zn 4.6 6.7 2.953

Ni Ni 12.1 12.3 2.715

Ti Ni 6 5.8 3.208

[00112] Table 5 and Figs. 1 1 -13 A demonstrate that synthetic saliva-submersed lithium cells in a

CR2032 configuration with gold positive electrodes exhibit very little evidence of reaction products that may lead to esophageal injuries upon accidental ingestion. The pH levels observed during these tests were generally below pH=8. Only the Au(+)/Ni(-) couple reached a level of about pH=8.2 at about ~35 minutes of exposure for a brief period up to ~45 minutes of exposure. The battery CCV decreased somewhat during testing for the Au(+) electrodes, indicating that some reactions were proceeding during saliva submersion. However, it appeared that oxygen evolution at the Au(+) electrode and hydrogen evolution at the negative electrodes were the primary reactions, not the potentially damaging hydroxide formation reactions.

[00113] The results for the tests conducted with grade S32750 stainless steel as the positive

electrode are also depicted in Figs. 14-16A and Table 4 above. The S32750(+)/55 Cu-32 Sn-12 Zn alloy-plated steel(-) couple performed best, with a pH level that did not exceed pH=8 and a minimal decrease in CCV during immersion in the synthetic saliva solution. The other two couples, S32750(+)/Ni(-) and S32750(+)/SS304(-), generally exhibited a pH level below pH=10 and stayed near or below pH=9 (i.e., minimal alkalinity) for most of the duration of the immersion testing. A slightly larger decrease in CCV was observed for these couples compared to the S32750(+)/55 Cu-32 Sn-12 Zn alloy-plated steel(-) couple.

[00114] After the duration of the testing for the S32750(+)/SS304(-), S32750(+)/Ni(-) and

S32750(+)/55 Cu-32 Sn-12 Zn alloy-plated steel(-) couples, the synthetic saliva solution appeared red or brownish in color, likely indicative of metallic dissolution of the S32750 electrode itself. In view of these results, post-testing solution observations, and the

electrochemical reactions (1) through (6) outlined earlier, it is very likely that these electrode couples are subject to anodic dissolution and oxygen evolution, but not the formation of quantities of hydroxide ions capable of causing esophageal damage. Instead, the dissolution reactions appear to produce non-hydroxide-containing chlorides, phosphates and/or sulfides. Accordingly, the use of S32750 as a positive electrode in lithium coin cells should reduce or mitigate the damage mechanisms associated with accidental coin cell ingestion.

Advantageously, grade S32750 stainless steel is magnetic, making it a good positive electrode material choice from a coin cell manufacturability standpoint.

EXAMPLE 4

] In this example, full size CR2016 cells were constructed using various different materials as described in Tables 6A and 6B below, with each table representing a separate experiment. Unless noted to the contrary, identical components, materials and dimensions were used across all lots to enable comparisons between the cells constructed in this example. Similarly, the same instruments, methods and saliva solution as the previous examples were employed. Gold foil was purchased from Sigma Aldrich, and plated materials were procured from Electro-spec. The duplex steel grade for this example was SS2507 from AvestaPolarit (ASTM S32750). As noted above, the pH values are instructive for comparison purposes of the different lots considered in this example only. Also, particularly with respect to the results in Table 6A, it is believed that some variability was observed owing to difficulties in obtaining consistent pH measurements. In view of these difficulties, the second experiment shown in Table 6B was conducted after the methodology was further refined. Also, in both Tables 6A and 6B a few duplicative results (i.e., lots having the same positive negative casings) have been omitted for the sake of brevity and, in the case of Table 6B, one of the duplicated lots involved a Duplex (+)/SS304(-) lot in which problems were incurred both in the construction of the cell and the uniformity of the pH for the synthetic saliva.

TABLE 6A

TABLE 6B

[00116] Generally speaking, cells that exhibited neutral or acidic pH values over a prolonged period of time are considered to be excellent candidates for the invention. Owing to perceived imperfections in the plating process, all gold-plated lots performed poorly, along with the "control" nickel lots, and reached a high pH (>10) within a matter of ten minutes. In contrast, duplex stainless steel proved to be a strong candidate even when coupled to a nickel negative electrode. This result was rather unexpected, but shows extreme promise insofar as duplex stainless steel and nickel plated steels are easily adapted to high speed manufacturing. As demonstrated in the prior examples, titanium also proves to be a promising material.

[00117] In sum, the electrochemical coin cell 10 advantageously mitigates or reduces the adverse electrolysis-related effects from accidental ingestion of the cell. It should be appreciated that other types of cells (e.g., cells with a nominal open circuit voltage greater than 1.23 V, including Li-ion electrochemical cells with an open circuit voltage above 4V) benefitting from this invention may employ different anode and cathode chemistries, and/or varying geometries.

[00118] While the invention has been described in detail herein in accordance with certain

embodiments, many modifications and changes to them may be effected by those skilled in the art without departing from the spirit of the invention. Accordingly, the scope of the appended claims shall not be limited by way of the details and instrumentalities describing the embodiments shown herein.

Claims

CLAIMS What is claimed is:

1. An electrochemical coin cell comprising:

internal components including an anode, a separator and a cathode capable of producing an output open circuit voltage of at least 2.8 voltage in the presence of a non-aqueous electrolyte; a flat cylindrical container encasing the internal components having an external diameter between 5 and 25 millimeters and an external height of between 0.5 and 10 millimeters, the container comprising an anode terminal casing and a cathode terminal casing with an electrically insulating gasket disposed therebetween;

wherein the anode terminal casing has an internal surface which maintains electrical contact with the anode and an external surface comprising a material that is resistant to reactions forming hydrogen gas during exposure to a saliva-containing solution; and

wherein the cathode terminal casing has an internal surface which maintains electrical contact with the cathode and an external surface comprising a material that is resistant to metallic dissolution and reactions forming oxygen gas during exposure to the saliva-containing solution.

2. The electrochemical cell according to claim 1, wherein the anode includes an active material consisting essentially of lithium or a lithium-based alloy and the cathode includes an active material comprising manganese dioxide.

3. The electrochemical cell according to claim 1 , wherein the external surface of the anode terminal casing exhibits an onset potential for hydrogen gas evolution in the saliva-containing solution in the range of approximately -0.66V to -1.96V versus a standard hydrogen electrode.

4. The electrochemical cell according to claim 3, wherein the external surface of the anode terminal casing is selected from the group consisting of: titanium metal, a titanium alloy, nickel metal, stainless steel and a copper-tin-zinc alloy containing 30 to 45% tin and 4 to 15% zinc alloying elements by weight.

5. The electrochemical cell according to claim 3, wherein the external surface of the cathode material casing exhibits an onset potential for anodic reactions in the saliva-containing solution in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode.

6. The electrochemical cell according to claim 5, wherein the external surface of the cathode terminal casing is selected from the group consisting of: titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold and boron-doped diamond.

7. The electrochemical cell according to claim 5, wherein the external surface of the cathode terminal casing is selected from the group consisting of: grade 2 titanium, grade 304 stainless steel, duplex stainless steel and gold.

8. The electrochemical cell according to claim 7, wherein the duplex stainless steel is ASTM grade S32750.

9. A method of manufacturing a coin-shaped battery having an external diameter of 5-25 millimeters and an external height of 0.5-10 millimeters that is resistant to electrolysis when placed in an aqueous solution initially having a neutral pH, the method comprising:

disposing an anode material comprising lithium or lithium alloy inside of a container having an anode terminal, wherein the entire external surface of the anode terminal is made from a material that is resistant to reactions forming hydrogen gas when the final, manufactured cell is submerged;

disposing a cathode material inside of a container having a cathode terminal, wherein the entire external surface of the cathode terminal is made from a material that is resistant to metallic dissolution and reactions forming oxygen gas when the final, manufactured cell is submerged; and

positioning a separator and insulating gasket between anode and the cathode and sealing the container to create a final, manufactured cell.

10. The method according to claim 9, wherein the external surface of the anode terminal is selected to exhibit an onset potential for hydrogen gas evolution when the final, manufactured cell is submerged in the range of approximately -0.66V to -1.96V versus a standard hydrogen electrode.

1 1. The method according to claim 9, wherein the external surface of the cathode terminal is selected to exhibit an onset potential for anodic reactions when the final, manufactured cell is submerged in the range of approximately +0.6V to +2.4V versus a standard hydrogen electrode.

12. A battery made according to the method of claim 9.

13. The battery of claim 12, wherein the external surface of the cathode terminal is selected from the group consisting of: titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold and boron-doped diamond.

14. The battery according to claim 12, wherein the external of the cathode terminal is selected from the group consisting of: grade 2 titanium, grade 304 stainless steel, duplex stainless steel and gold.

15. The method according to claim 9, wherein the anode terminal is made from a cladded material.

16. The method according to claim 9, wherein the cathode terminal is made from a cladded material.

17. A coin-shaped battery having a nominal voltage of at least 3.0 volts, an external diameter of 5-25 millimeters and an external height of 0.5-10 millimeters that is resistant to electrolysis when completely submerged in an aqueous solution having an initial pH of 7.0 or less, the coin- shaped battery comprising:

an exposed surface of an anode terminal consisting essentially of: titanium metal, a titanium alloy, nickel metal, stainless steel, a copper-tin-zinc alloy containing 30 to 45% tin and 4 to 15% zinc alloying elements by weight or combinations thereof; and an exposed surface of a cathode terminal consisting essentially of: titanium metal, titanium alloy, titanium nitride, tantalum, niobium, stainless steel, gold, boron-doped diamond, grade 2 grade 304 stainless steel, grade S32750 duplex stainless steel or combinations thereof.

18. The battery according to claim 17, further comprising an anode active material having lithium and a cathode active material having manganese dioxide.