Coin battery

Abstract

A coin-shaped battery comprises: a battery case that has a bottom plate portion and a side portion that stands upright from the peripheral edge of the bottom plate portion; a sealing plate that has a top plate portion and a peripheral edge portion that extends from the top plate portion toward the inside of the side portion; a gasket that is compressed and interposed between the side portion and the peripheral edge portion; an electric power generation element that is sealed by the battery case, the sealing plate, and the gasket; and a pressure-sensitive electrically conductive film that is provided to an external surface of at least one of the battery case and the sealing plate, wherein the pressure-sensitive electrically conductive film has a first elastomer layer for holding an electrically conductive material and a second elastomer layer that is provided to at least one surface of the first elastomer layer and with which the electrically conductive material that is held by the first elastomer layer is in contact, the thickness of the electrically conductive material being equal to or more than the thickness of an elastomer portion of the first elastomer layer, and the electrically conductive material being provided in a single layer in a plane direction of the first elastomer layer.

Description

Coin cell battery

[0001] The present invention relates to a coin battery, and more particularly to a coin battery with improved safety against accidental ingestion.

[0002] Coin batteries are widely used as power sources for small devices, memory backup, etc. In a typical coin battery, a power generating element including pellet-shaped positive and negative electrodes, a separator interposed between these electrodes, and an electrolyte is housed in an exterior body composed of a battery case, a sealing plate, and a gasket, and the opening of the battery case is sealed by crimping it to the periphery of the sealing plate via the gasket.

[0003] As the use of coin-cell batteries expands, the number of accidental ingestion accidents is also increasing, making it increasingly important to take measures to prevent accidental ingestion of coin-cell batteries. When a coin-cell battery is ingested into the body, the terminal surfaces of the battery case and sealing plate come into contact with body fluids, causing a short circuit between the positive and negative terminals. This short circuit causes a current to flow due to the electrolysis of water, turning the body fluid on the negative terminal side alkaline. This alkaline body fluid can damage biological tissues such as the esophageal wall.

[0004] Patent Literature 1 describes a technology for preventing accidental ingestion of coin-shaped batteries. This technology uses a pressure-sensitive quantum tunneling composite coating (QTCC) film, in which conductive particles with nanoscale surface roughness are dispersed in a polymer matrix such as silicone elastomer. When pressure above a threshold is applied, the conductive particles in this pressure-sensitive coating film close together, becoming conductive due to the quantum tunneling effect. Conversely, when pressure below the threshold is applied, the conductive particles are too far apart to obtain the quantum tunneling effect, maintaining electrical insulation. According to Patent Literature 1, this pressure-sensitive coating film covers at least one of the positive and negative terminals of the coin-shaped battery, setting the pressure-sensitive conductivity threshold higher than the pressure experienced in the human digestive tract. This is said to prevent short-circuiting of the battery in the digestive tract if the coin-shaped battery is accidentally ingested.

[0005] The coin battery described in Patent Document 2 has a pressure-sensitive conductive film on its outer surface that contains conductive particles and has a specific laminated structure, which makes the coin battery superior in pressure-induced current-carrying characteristics to the one described in Patent Document 1, and also superior in safety in the event of accidental ingestion.

[0006] US Patent No. 9741975 JP 2021-57113 A

[0007] Coin batteries are electrically conductive when pressure is applied in the thickness direction, and it is necessary to suppress variations in pressure response and current-carrying characteristics at the contact points with the device terminals (external terminals). From this perspective, the coin batteries described in Patent Document 2 require extremely high precision in achieving uniform particle size for the conductive particles. However, conductive particles typically have a particle size distribution, which limits the degree of uniformity. While it is possible to narrow the particle size distribution width by, for example, sieving, it is difficult to completely eliminate it. Under these circumstances, further minimizing the particle size distribution width may result in a decrease in the yield in the preparation of conductive particles and, therefore, an increase in the manufacturing cost of coin batteries. Therefore, there is room for improvement in coin batteries from the perspective of improving quality and industrial mass production.

[0008] In view of the above, an object of the present invention is to provide a coin battery that further suppresses variations in pressure response and current conduction characteristics, and that combines excellent electrical characteristics with safety in the event of accidental ingestion.

[0009] The above-mentioned problems of the present invention have been solved by the following means: [1] A coin-shaped battery comprising: a battery case having a bottom plate and side portions rising from the peripheral edge of the bottom plate; a sealing plate having a top plate and peripheral portions extending from the top plate to the inside of the side portions; a gasket interposed and compressed between the side portions and the peripheral portions; a power-generating element sealed by the battery case, the sealing plate, and the gasket; and a pressure-sensitive conductive film disposed on the outer surface of at least one of the battery case and the sealing plate, wherein the pressure-sensitive conductive film has a first elastomer layer that holds a conductive wire, and a second elastomer layer that is disposed on at least one surface of the first elastomer layer and comes into contact with the conductive wire held by the first elastomer layer, wherein the thickness of the conductive wire is equal to or greater than the thickness of the elastomer portion of the first elastomer layer, and the conductive wire is disposed in a single layer in the planar direction of the first elastomer layer. [2] The coin battery according to [1], wherein the thickness of the conductive wire is greater than the thickness of the elastomer portion of the first elastomer layer. [3] The coin battery according to [1] or [2], wherein the second elastomer layer is disposed in contact with the outer surface of at least one of the battery case and the sealing plate. [4] The coin battery according to [1] or [2], wherein the conductive wire in contact with the second elastomer layer protrudes beyond the elastomer portion of the first elastomer layer toward the side opposite to the second elastomer layer. [5] The coin battery according to [1], wherein the conductive wires are partially overlapped to form a lattice pattern.

[0010] In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after it as the lower and upper limits.

[0011] The coin battery of the present invention further reduces variations in pressure response and current conduction characteristics, and can achieve both excellent electrical characteristics and safety in the event of accidental ingestion.

[0012] FIG. 1 is a schematic cross-sectional view showing the configuration of a typical coin battery. FIG. 2 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 3 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 4 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 5 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 6 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 7 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 8 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 9 is a schematic cross-sectional view showing a preferred configuration of the coin battery of the present invention. FIG. 10 is a schematic cross-sectional view showing a preferred configuration of the pressure-sensitive conductive film used in the present invention. FIGS. 11(A) to 11(C) are schematic plan views showing examples in which the conductive wires are linear in plan view and are arranged with their wire lengths aligned in the planar direction of the first elastomer layer. Fig. 11(D) is a schematic plan view showing an example in which the conductive wire is linear in plan view and arranged in various directions in the planar direction of the first elastomer layer. Figs. 11(E) and 11(F) are schematic plan views showing an example in which the conductive wire is curved in plan view and arranged in a concentric or spiral shape in the planar direction of the first elastomer layer. Figs. 11(G) and 11(H) are schematic plan views showing an example in which the conductive wire is curved in plan view and arranged in a concentric circle shape in the planar direction of the first elastomer layer, with some of the wire missing from the periphery. Fig. 11(I) is a schematic plan view showing an example in which the conductive wire is linear in plan view and arranged in a grid shape in the planar direction of the first elastomer layer. Fig. 12 is a schematic cross-sectional view showing a preferred embodiment of the pressure-sensitive conductive film used in the present invention. Fig. 13 is a schematic cross-sectional view showing a preferred embodiment of a pressure-sensitive conductive film used in the present invention. Fig. 14 is a schematic cross-sectional view showing a preferred embodiment of a pressure-sensitive conductive film used in the present invention.

[0013] [Coin Battery] A preferred embodiment of the coin battery of the present invention will be described with reference to the drawings. The drawings are explanatory diagrams for facilitating understanding of the present invention, and the sizes and relative dimensional relationships of the various components may be exaggerated for the sake of convenience and do not directly represent the actual relationships. Furthermore, the outer shapes and forms shown in these drawings are not limited to those specified in the present invention. In the present invention, the term "coin battery" also includes button-type batteries. That is, the shape and diameter of a coin-type battery are not particularly limited. For example, a button-type battery whose thickness is greater than its diameter is also included in the coin-type battery category.

[0014] FIG. 1 is a longitudinal cross-sectional view schematically illustrating the configuration of a typical coin battery. The coin battery shown in FIG. 1 has an exterior body composed of a battery case 1, a sealing plate 6, and a gasket 5. The battery case 1 has a bottom plate 1a and a side portion 1b rising from the periphery of the bottom plate 1a, and is a shallow, circular battery can in a plan view. The sealing plate 6 has a top plate 6a and a peripheral portion 6b extending from the top plate 6a to the inside of the side portion 1b of the battery case 1. The gasket 5 is interposed in a compressed state between the side portion 1b of the battery case 1 and the peripheral portion 6b of the sealing plate 6. In other words, the gasket 5 is disposed inside the side portion 1b of the battery case 1 and outside the peripheral portion 6b of the sealing plate 6, sealing the gap between the battery case 1 and the sealing plate 6. Furthermore, in order to electrically insulate the battery case 1 from the sealing plate 6, the gasket 5 is preferably disposed so as to cover the peripheral edge 6b of the sealing plate 6, including the end of the peripheral edge 6b.

[0015] The exterior housing contains a power generating element. The power generating element includes a positive electrode 2, a negative electrode 3, a separator 4, and an electrolyte (not shown). In the illustrated example, the positive electrode 2 is disposed in contact with the bottom plate 1a of the battery case 1. Therefore, the outer surface of the bottom plate 1a of the battery case 1 functions as a positive electrode terminal. On the other hand, the negative electrode 3 is disposed in contact with the top plate 6a of the sealing plate 6. Therefore, the outer surface of the top plate 6a of the sealing plate 6 functions as a negative electrode terminal.

[0016] 1, it is desirable to use a metal plate that is corrosion-resistant at the positive electrode potential as the material for forming the battery case 1. For example, in the case of a lithium battery, it is desirable to use stainless steel (SUS430, SUS444, SUS329J, etc.), titanium, a titanium alloy, etc. as the material for forming the battery case 1. It is desirable to form a nickel plating layer on the outer surface of the battery case.

[0017] In the embodiment shown in FIG. 1 , the material for forming the sealing plate 6 is not particularly limited as long as it functions as a negative electrode terminal. It is preferable to use a metal plate with a predetermined mechanical strength as the material for forming the sealing plate 6, and stainless steel (e.g., SUS304, SUS316, SUS430, etc.) is particularly suitable. Inexpensive metal plates such as ordinary steel or carbon steel can also be used. Ordinary steel refers to steel materials such as SS material, SM material, and SPCC material specified in JIS. Carbon steel refers to steel materials such as S10C, S20C, S30C, S45C, and S55C, which belong to alloy steels for mechanical structures. When ordinary steel or carbon steel is used, it is desirable to form a rust-preventive plating layer (e.g., a nickel plating layer) on the inner surface of the battery. Typically, a nickel plating layer is formed on both the inner and outer surfaces of a sealing plate made of ordinary steel or carbon steel. A nickel plating layer is also formed on the outer surface of a sealing plate made of stainless steel.

[0018] In the coin battery of the present invention, a pressure-sensitive conductive film (described later) is disposed on the outer surface of at least one of the battery case 1 and the sealing plate 6 (i.e., on at least one of the outer surfaces of the positive electrode terminal and the negative electrode terminal). The area covered by this pressure-sensitive conductive film can be appropriately set depending on the purpose, as long as the effects of the present invention are not impaired. Preferred examples of the arrangement of the pressure-sensitive conductive film will be described below.

[0019] <Arrangement of Pressure-Sensitive Conductive Film-1> As shown in Figure 2, a pressure-sensitive conductive film 7 can be provided in contact with the outer surface of the top plate portion 6a of the sealing plate 6. In this case, an insulating coating 8 must be applied to exposed areas of the sealing plate 6 other than the top plate portion 6a to prevent external short-circuiting in the event of accidental ingestion. This insulating coating 8 coats the outer surface of the side portion 6b of the sealing plate 6, which is located between the pressure-sensitive conductive film 7 and the gasket 5. From the perspective of more reliably preventing the intrusion of bodily fluids in the event of accidental ingestion, it is preferable that this insulating coating 8 be applied from the end of the pressure-sensitive conductive film 7 to the end of the side portion 1b of the battery case 1, covering both ends (this form is shown in Figure 2).

[0020] <Arrangement of Pressure-Sensitive Conductive Film-2> As shown in Fig. 3 , a configuration can be adopted in which the pressure-sensitive conductive film 7 directly covers the area between the outer surface of the top plate portion 6a of the sealing plate 6 and the portion of the outer surface of the peripheral edge portion 6b of the sealing plate 6 that is covered by the gasket 5. In this case, since there is no exposed portion of the outer surface of the sealing plate 6, treatment with the insulating coating 8 is not necessarily required. However, from the perspective of more reliably preventing the intrusion of bodily fluids and external short-circuiting in the event of accidental ingestion, it is preferable to apply the insulating coating 8 from the end of the pressure-sensitive conductive film 7 to the end of the side portion 1b of the battery case 1 so as to cover both ends (this configuration is shown in Fig. 3 ).

[0021] <Arrangement of Pressure-Sensitive Conductive Film - 3> As shown in Fig. 4, a pressure-sensitive conductive film 7 can be provided over the entire outer surface of the battery case 1 in contact with it. In this case, an insulating coating 8 must be applied to the edge of the side portion 1b of the battery case 1 to prevent an external short circuit in the event of accidental ingestion. This insulating coating 8 can be applied from the edge of the pressure-sensitive conductive film 7 to the peripheral edge 6b of the sealing plate 6, from the viewpoint of more reliably preventing the intrusion of bodily fluids and an external short circuit in the event of accidental ingestion. Alternatively, the insulating coating 8 can be applied from the edge of the pressure-sensitive conductive film 7 to the edge of the top plate portion 6a of the sealing plate 6, covering both ends (this form is shown in Fig. 4).

[0022] <Arrangement of Pressure-Sensitive Conductive Film-4> As shown in Figure 5, a pressure-sensitive conductive film 7 can be directly covering the outer surface of the battery case 1 and the area from the edge of the side portion 1b of the battery case 1 to partway through the gasket 5. In this case, since there is no exposed portion on the surface of the battery case 1, treatment with an insulating coating 8 is not necessarily required. However, from the perspective of more reliably preventing the intrusion of bodily fluids and external short circuits in the event of accidental ingestion, the insulating coating 8 can be provided from the edge of the pressure-sensitive conductive film 7 to the peripheral edge 6b of the sealing plate 6. Alternatively, the insulating coating 8 can be applied from the edge of the pressure-sensitive conductive film 7 to the edge of the top plate portion 6a of the sealing plate 6, i.e., covering both ends (this form is shown in Figure 5).

[0023] 2 to 5 can be applied after the pressure-sensitive conductive film is disposed on the coin battery, but the present invention is not limited to this. Examples of coating methods include a method in which a coating liquid prepared by dissolving an insulating material in a solvent is applied or sprayed, and then the solvent is volatilized to form an insulating film.

[0024] As described above, it is preferable to provide an insulating coating 8 for the pressure-sensitive conductive membrane arrangements 1 to 4. On the other hand, by restricting the arrangement of the conductive wires that provide the conductivity of the pressure-sensitive conductive membrane to a non-overlapping configuration (e.g., the configurations shown in Figures 11(A) to 11(H)), the pressure-sensitive conductive membrane can be endowed with an anisotropic function that prevents in-plane conduction even when pressure above a threshold is applied. Note that the non-overlapping configuration may include some unintentional, accidental overlap. By using such an anisotropic pressure-sensitive conductive membrane, simply by arranging the pressure-sensitive conductive membrane so that it covers a desired portion of the battery surface, it is possible to more reliably prevent the intrusion of bodily fluids and external short circuits in the event of accidental ingestion, even without providing an insulating coating 8. An example of such a configuration will be described below. The arrangement of the conductive wires that allows the pressure-sensitive conductive membrane to exhibit an anisotropic function will be described in detail below.

[0025] <Arrangement of Pressure-Sensitive Conductive Film - 5> In the arrangement of the pressure-sensitive conductive film shown in Figure 6, the entire portion of the sealing plate 6 exposed on the outer surface, extending from there to the edge of the side portion 1b of the battery case 1, is integrally covered with the pressure-sensitive conductive film 7 so as to cover said edge. As mentioned above, in this arrangement, it is preferable to arrange the conductive wires so that they do not overlap each other. This gives the pressure-sensitive conductive film 7 an anisotropic function and prevents conduction in the planar direction, which is preferable because it more reliably prevents external short circuits in the event of accidental ingestion without the need for an insulating coating 8 (this arrangement is shown in Figure 6).

[0026] <Arrangement of Pressure-Sensitive Conductive Film-6> As shown in FIG. 7 , a pressure-sensitive conductive film 7 can be used to cover the entire outer surface of the battery case 1, extending from the outer surface to the peripheral edge 6b of the sealing plate 6. In this configuration, as described above, it is preferable to arrange the conductive wires so that they do not overlap each other. This provides the pressure-sensitive conductive film 7 with an anisotropic function. In this case, it is preferable to cover the entire outer surface of the battery case 1, extending from the outer surface to the edge or vicinity of the top plate 6a of the sealing plate 6, with the pressure-sensitive conductive film 7. This is preferable because it can more reliably prevent an external short circuit in the event of accidental ingestion without applying an insulating coating 8.

[0027] Although the details of the pressure-sensitive conductive film will be described later, when the pressure-sensitive conductive film contacts the battery case or sealing plate via the second elastomer layer 10, the second elastomer layer 10 can be provided as an insulating coating in a desired location, and a first elastomer layer 9 containing conductive wires in a single layer in the planar direction can be provided in a desired location on the second elastomer layer 10. An example of such a configuration is shown in Figures 8 and 9. Note that, in a configuration in which the conductive wires are intentionally assembled so that they partially overlap each other, such as the lattice-like configuration shown in Figure 11(I), it is more preferable to provide an insulating coating 8 as shown in Figures 2 to 5 in addition to the second elastomer layer 10 that functions as an insulating coating.

[0028] (Pressure-sensitive conductive film) The pressure-sensitive conductive film used in the present invention is a pressure-sensitive conductive film that is in an insulating (high resistance) state when no external pressure of a certain level or more is applied, and can create a conductive (low resistance) state in the film thickness direction when an external pressure of a certain level or more is applied. The pressure-sensitive conductive film used in the present invention has a first elastomer layer that holds conductive wires, and a second elastomer layer that is arranged on at least one side of the first elastomer layer and contacts at least some of the conductive wires held by the first elastomer layer. The conductive wires are arranged in a single layer in the planar direction of the first elastomer layer. A preferred embodiment of the pressure-sensitive conductive film used in the present invention will be described.

[0029] - Pressure-Sensing Conductive Film [Form 1] - A preferred example (Form 1) of the pressure-sensitive conductive film used in the present invention will be described using the schematic cross-sectional view shown in Figure 10. The pressure-sensitive conductive film 12 of Form 1 includes a first elastomer layer 9 (the first elastomer and conductive wire 11 collectively referred to as the first elastomer layer 9) that holds the conductive wire 11, and a second elastomer layer 10 that is disposed on the underside of the first elastomer layer 9 and contacts the conductive wire 11. The second elastomer layer 10 functions as an insulating layer between the conductive wire 11 and the conductive substrate 13 (corresponding to the sealing plate or battery case of a coin-shaped battery). Note that some of the conductive wire 11 may not contact the second elastomer layer 10. The thickness of the conductive wire 11 is equal to or greater than the thickness of the elastomer portion of the first elastomer layer 9. As a result, the conductive wire 11 protrudes from the elastomer portion of the first elastomer layer 9. Note that some of the conductive wires 11 may not protrude from the elastomer portion of the first elastomer layer 9. Furthermore, individual conductive wires 11 may have portions that do not protrude. Considering manufacturing, in embodiment 1, the conductive wires 11 held by the first elastomer layer 9 and in contact with the second elastomer layer 10 may be partially included on the second elastomer layer 10 side, but preferably do not protrude. Furthermore, it is preferable that the conductive wires 11 in contact with the second elastomer layer 10 protrude beyond the elastomer portion of the first elastomer layer 9 toward the side opposite the second elastomer layer 10. The "thickness" (d) of the conductive wire 11 refers to the height of the conductive wire 11 when the wire length of the conductive wire 11 is arranged along the planar direction of the elastomer portion of the first elastomer layer 9. In other words, the "thickness" refers to the length along the thickness direction of the first elastomer layer 9 in a cross section of the conductive wire 11 in the thickness direction (a cross section along the wire width perpendicular to the wire length direction, as described below). When the cross section of the conductive wire 11 in the thickness direction is circular, the "thickness" is its diameter. Note that in a configuration in which the conductive wires 11 are arranged so that they partially overlap each other in the thickness direction (for example, overlapping in two layers), the "thickness" (d) of the conductive wire 11 refers to the length along the thickness direction of the portions of the conductive wires 11 that do not overlap each other in the thickness direction.In this case, the thickness of the portion where the thicknesses of the conductive wires 11 overlap in the thickness direction is greater than the “thickness” (d) of the portion where they do not overlap, and the state in which they protrude from the elastomer portion of the first elastomer layer 9 becomes more apparent.

[0030] In form 1, when a pressure equal to or greater than a certain level is applied from an external contact terminal (external terminal) in the thickness direction of pressure-sensitive conductive film 12 (from top to bottom in FIG. 10 ), conductive wire 11 held in first elastomer layer 9 breaks through second elastomer layer 10, and conductive wire 11 electrically connects conductive substrate 13 to the external terminal. In other words, an electrical circuit of "external terminal-conductive wire 11-conductive substrate 13" is formed. The elastomer layer is not involved in the conduction of this electrical circuit, and therefore the resistance does not depend on the external pressure, achieving a low-resistance conductive state.

[0031] In embodiment 1, conductive wire 11 is arranged in a single layer in the planar direction of first elastomer layer 9. Therefore, pressure applied in the thickness direction of pressure-sensitive conductive film 12 can quickly create a low-resistance conductive state in the film thickness direction. In the present invention, "conductive wire arranged in a single layer in the planar direction of the first elastomer layer" means that the conductive wire is arranged in a substantially single layer in the planar direction of the first elastomer layer. In other words, within a portion of the first elastomer layer, two or more conductive wires may be present in a state where they overlap in the thickness direction of the first elastomer layer (for example, a wire may be placed between the conductive wires, or two wires may overlap in the film thickness direction) as long as the effects of the present invention are not impaired. The form in which "the conductive wires are arranged in a single layer in the planar direction of the first elastomer layer" means that the conductive wires are arranged in a single layer without overlapping in the film thickness direction over 80% or more of the area of ​​the conductive wires observed in a planar view of the first elastomer layer 9, and it is also preferable that all of the conductive wires are arranged in a single layer without overlapping in the film thickness direction. However, in the form in which the conductive wires 11, 11 are arranged in a single layer as an integrated lattice-like unit as shown in Figure 11 (I), if the conductive wires 11 are arranged in a state where they partially overlap in the thickness direction (film thickness direction) (for example, overlapping in two layers), it is preferable that the conductive wires are arranged in a single layer without overlapping in the film thickness direction over 50 to 80% of the area of ​​the conductive wires observed in a planar view of the first elastomer layer 9.

[0032] As described above, the thickness (d) of the conductive wire 11 is equal to or greater than the thickness of the elastomer portion of the first elastomer layer 9. This allows the conductive wire 11 to protrude from the elastomer portion of the first elastomer layer 9. Protruding from the elastomer portion of the first elastomer layer 9 means that the conductive wire 11 is in a state where it can directly contact an external terminal (contact terminal). This includes cases where the thickness (d) of the conductive wire 11 and the thickness of the elastomer portion of the first elastomer layer 9 are the same. It is also preferable to set the thickness (d) of the conductive wire 11 to be greater than the total thickness of the elastomer portion of the first elastomer layer 9 and the second elastomer layer 10. This ensures reliable contact between the conductive wire 11 and the external terminal when a certain amount of pressure is applied to bring the conductive wire 11 into contact with the conductive substrate 13, thereby further suppressing fluctuations in resistance due to pressure changes.

[0033] When the applied pressure is released, the pressure-sensitive conductive film of Form 1 allows the combined elasticity of the first elastomer layer 9 and the second elastomer layer 10 to return the conductive wire 11 to the position it was in before the pressure was applied (the state shown in FIG. 10 ). As the conductive wire 11 returns to its position before the pressure was applied, the tear in the second elastomer layer 10 is also sealed by its own elasticity, allowing the film to recover to its initial insulating state. This recoverability is referred to as "self-repairability" in the present invention.

[0034] Because the pressure-sensitive conductive film 12 exhibits self-repairing properties, even when the coin battery is inserted or removed from an electronic device, an external short circuit can be prevented in the event of accidental ingestion, and when in use, a stable conductive state can be achieved against applied pressure to the terminals of the device.

[0035] Next, the conductive wire 11, the first elastomer layer 9, and the second elastomer layer 10 in the first embodiment will be described in more detail.

[0036] --Conductive wire 11-- The "wire" in conductive wire 11 refers to a conductive wire 11 having an aspect ratio (line length / line width) of 3 or more when observed in a planar view, more preferably 5 or more. This aspect ratio is the ratio of the line length to the line width (line length / line width) when observed in a planar view while the conductive wire 11 is held by the first elastomer layer 9. The line length refers to the length along the extension direction of the conductive wire 11. For example, if the conductive wire 11 has a linear shape, the line length is the linear length, and if the conductive wire 11 has a curved shape, the line length is the length along the curve. The line width refers to the length of the conductive wire 11 in a direction perpendicular to the line length. Note that, in the line length and line width observed in a planar view, the line length is the length in the extension direction passing through the center of the line width. The "planar observation" or "plan view" of the conductive wire 11 refers to observing from above the state in which the wire length of the conductive wire 11 is arranged along the planar direction of the elastomer portion of the first elastomer layer 9. If the conductive wire 11 cannot be seen with the naked eye due to the presence of the elastomer portion, the observation should be made excluding the covering elastomer portion.

[0037] Because the conductive wire 11 is integrally formed by stretching in the wire length direction, the variation in diameter (thickness) in the wire length direction is smaller than that of particles formed from independent materials. Therefore, when conducting current in a coin battery due to pressure in the thickness direction, the influence of differences in diameter (thickness) depending on the pressure applied can be significantly reduced. Furthermore, because the conductive wire 11 has a long wire length relative to its wire width, as shown by the aspect ratio described above, its placement stability in the first elastomer layer 9 is higher than that of particles. Therefore, the planar displacement of the conductive wire 11 when pressure is applied in the thickness direction can be reduced. Furthermore, even if external forces such as vibration or tilting are applied to the coin battery before use, the displacement of the conductive wire 11 can be reduced. This stabilizes the responsiveness of the pressure-sensitive conductive film 12, making it easier to conduct current in the height direction with more stability. Additionally, using wire rather than particles improves absolute strength and allows the external pressure force to be dispersed in the wire length direction. As a result, the present invention further reduces the risk of cracking or breakage when excessive external pressure is applied compared to particles, ensuring more stable electrical continuity. Furthermore, depending on the shape of the external terminals, using wire rather than particles can result in lower resistance at the wire's electrical connection points than at the multiple electrical connection points of particles, reducing the impact of heat generated by electrical continuity on the elastomer, thereby stabilizing response characteristics over the long term. As a result, the coin-type battery of the present invention further reduces variations in pressure response and electrical conduction characteristics, achieving excellent electrical characteristics.

[0038] The cross section of the conductive wire 11 in the thickness direction (cross section in the thickness direction along the line width) may have various shapes as long as the effects of the present invention are not impaired. For example, as described above, it may be circular, elliptical, or polygonal. In the case of a polygon, it is preferable that the number of sides is an even number from the viewpoint of placement stability in the first elastomer layer 9. When the cross section of the conductive wire 11 in the thickness direction is circular, its diameter is the line width observed in a planar view. When the cross section of the conductive wire 11 in the thickness direction is other than circular (for example, when it is elliptical or polygonal), the line width is the width as determined by observing the conductive wire 11 in a planar view with its line length aligned along the planar direction of the elastomer portion of the first elastomer layer 9. In this case, when the cross section of the conductive wire 11 in the thickness direction is elliptical, the major axis of the ellipse may be aligned not only in the planar direction but also in the thickness direction. When the cross section of the conductive wire 11 in the thickness direction is polygonal, the length of the longest line segment connecting one side or point of the polygon through the center to the opposing side or point may be arranged not only along the planar direction but also along the thickness direction. Also, when the conductive wire 11 is not circular and the arrangement surface along the planar direction is not uniform as described above, the "thickness" (d) of the conductive wire 11 defined above is the average value calculated when N = 3 or 5.

[0039] The conductive wires 11 are arranged with their wire lengths oriented in the planar direction of the first elastomer layer 9. The shape of the conductive wires 11 in a planar view and their arrangement in the planar direction of the first elastomer layer 9 may vary within the scope of the present invention. For example, as shown in Figures 11(A) to 11(C), the conductive wires 11 may be linear in a planar view and arranged with their wire lengths aligned with one another in the planar direction of the first elastomer layer 9. This allows for easier and more regular arrangement of the conductive wires than conductive particles. Stable response characteristics can be achieved without misalignment, cracks, or breaks in response to various external terminal shapes and external stress strengths and directions. Anisotropy can also be ensured. As shown in Figure 11(D), the conductive wires 11 may be linear in a planar view and arranged in various directions in the planar direction of the first elastomer layer 9. This increases the degree of freedom in placement, making it easier to randomly arrange the conductive wires compared to conductive particles. Furthermore, there is no misalignment, cracking, or breakage in response to the strength or direction of external stress, resulting in stable response characteristics. Anisotropy can also be ensured. As shown in FIGS. 11(E) and 11(F), the conductive wires 11 may be curved in plan view and arranged in a concentric or spiral pattern in the planar direction of the first elastomer layer 9. Alternatively, as shown in FIGS. 11(G) and 11(H), the conductive wires 11 may be arranged in a concentric pattern in plan view, with a shape that does not form a closed circle (e.g., a Landolt ring-like shape). This allows for easier, more regular arrangement of the conductive wires compared to conductive particles. This is particularly effective when establishing electrical continuity through external terminals in the circumferential direction of a coin-type battery. The longer wire length increases absolute strength and the larger arrangement area. This results in stable response characteristics without misalignment, cracking, or breakage in response to various external terminal shapes and the strength or direction of external stress. In addition, the heat dissipation during conduction is improved, reducing the thermal effect and ensuring long-term response stability. Anisotropy can also be ensured. As shown in FIG. 11(I), the conductive wires 11 may be linear in plan view and arranged in a grid pattern in the planar direction of the first elastomer layer 9.This allows for easier grid-like arrangement of conductive wires than other types of conductive wire. Because the wires are longer, overlapping portions between wires are added, resulting in higher absolute strength and a larger layout area. This eliminates misalignment, cracks, or breakages caused by various external terminal shapes and external stress strengths and directions, resulting in stable response characteristics. Furthermore, improved heat dissipation during conduction reduces thermal effects and ensures long-term response stability. In this grid-like arrangement, the overlapping grid portions may be configured such that the thicknesses of the conductive wires 11 overlap in the thickness direction (film thickness direction) (e.g., two-tiered configuration) or such that the conductive wires are connected at the same height in the thickness direction (e.g., a single-tiered configuration similar to a lattice door).

[0040] The cross section of the conductive wire 11 in the thickness direction is preferably a perfect circle. A perfect circle can be confirmed by magnification observation, etc. In the present invention, "perfect circle" refers to a circle, and includes not only a perfect circle but also an approximately circular shape that can be recognized as a circle at a glance. The "perfect circle" is indicated by circularity. The circularity is the ratio of the length of the shortest line segment to the length of the longest line segment among multiple line segments that pass through the center of the cross section of the conductive wire 11 in the thickness direction and connect two points on the outer edge. The maximum circularity is 1 (i.e., 100%), and the closer the circularity is to 1, the closer it is to a perfect circle. When the conductive wire 11 is a perfect circle, the circularity is preferably 0.80 to 1.0, and more preferably 0.90 to 1.0. The "perfect circle" may also be defined by the circularity shown below. The circularity can be determined based on the cross section of the conductive wire 11 in the thickness direction. The circularity is expressed as 1, with the numerical value decreasing as the shape becomes more complex. The circularity can be calculated using the following formula: Circularity = 4π × (area) ÷ (perimeter) ２ For example, for a perfect circle with a radius of 10, the circularity = 4π x (10 x 10 x π) ÷ (10 x 2 x π) ２" = 1 (maximum value). In other words, in terms of circularity, a perfect circle is the least complex shape. Incidentally, the circularity of a square is 0.785, and the circularity of an equilateral triangle is approximately 0.604, meaning that an equilateral triangle is a more complex shape than a square. The circularity of the conductive wire 11 is preferably 0.7 to 1.0. The circularity and circularity of the conductive wire 11 can be measured by the following method. The wire can be cut and measured from cross-sectional observation, or they can be measured from non-destructive cross-sectional observation using X-ray CT.

[0041] The material for the conductive wire 11 is not particularly limited as long as it can ensure conductivity. Examples include metal wire and metal-coated wire. Metal wire can be formed by stretching along the wire length, which allows for more accurate and cost-effective diameter uniformity than particle materials. Metal-coated wire can be produced by plating a metal onto the metal-coated wire substrate fabricated by the above-described method, allowing for more accurate and cost-effective diameter uniformity than particle materials. Furthermore, the conductive wire 11 can be made from recycled waste materials. Recycling waste materials can further reduce costs and contribute to reducing environmental impact. Examples of metal wire include various materials used as conductive wires, such as Au, Ag, Cu, Fe, Al, Ni, Pd, platinum, stainless steel, and alloys of these metals. Examples of metal-coated wires that can be used include copper-silver-coated wire, steel-zinc-coated wire, piano wire-zinc-coated wire, steel-nickel-coated wire, and piano wire-nickel-coated wire. Considering cost and conductive performance, glass-silver coated wire, silica-silver coated wire, etc. are preferred. As conductive non-metallic wire, carbon fiber and conductive fibers made by kneading conductive carbon into polyester or nylon are preferred. In order to ensure stable contact between the conductive wire and the battery during device use, Ni-based metal wire, the same as the nickel plating on the outer surface of the battery, is preferred for the conductive wire 11. Furthermore, some additives or other metals may be included to enhance conductivity, etc.

[0042] As described above, conductive wire 11 is typically formed by stretching it along its length, allowing for extremely small variations in its diameter (thickness). From this perspective, the thickness (d) of conductive wire 11 is preferably 10≦d≦200 μm, and more preferably 20≦d≦100 μm. As described above, thickness (d) is a value measured on a cross section of conductive wire 11 in the thickness direction. Having a thickness (d) of 10 μm or more improves the handleability of conductive wire 11 and allows conductive wire 11 to be more reliably arranged in a desired single layer in the planar direction. The thickness (d) of conductive wire 11 is preferably 20 μm or more, and more preferably 30 μm or more. On the other hand, having a thickness (d) of conductive wire 11 of 50 μm or less allows the total thickness of pressure-sensitive conductive film 7 to be reduced, thereby improving applicability to coin-type batteries. Coin-type batteries have predetermined size standards (thickness, diameter) to accommodate the devices in which they are used. From the viewpoint of ensuring battery capacity while keeping the size within the standard tolerance, the thickness (d) of the conductive wire 11 is more preferably 50 μm or less, and even more preferably 30 μm or less. The above description of the conductive wire 11 is also preferably applied to embodiments 2 to 4 described below.

[0043] Furthermore, the variation in the diameter (thickness) of each conductive wire 11 in the wire length direction is also extremely small. As a result, the variation in the thickness (d) of the conductive wire 11 in the wire length direction is also extremely small. From this viewpoint, the ratio of the minimum diameter to the maximum diameter (minimum diameter / maximum diameter) in the diameter (thickness) of each conductive wire 11 in the wire length direction is preferably 0.85 or more, more preferably 0.90 or more. The maximum diameter and minimum diameter can be measured using the same method as for the thickness (d).

[0044] Here, we will explain a more preferred embodiment of the pressure-sensitive conductive film using the conductive wire 11, namely, an anisotropic pressure-sensitive conductive film, applicable to the present invention. An anisotropic pressure-sensitive conductive film typically does not have an electrical circuit that crosses the surface of the pressure-sensitive conductive film, but rather conducts pressure in the film thickness direction. However, in the present invention, for example, in the cases of the pressure-sensitive conductive film arrangements 5 and 6 described above, as can be understood from these arrangements, it is sufficient that only the portion arranged on the gasket exhibits anisotropic conductivity. Such a pressure-sensitive conductive film is also a form of an anisotropic pressure-sensitive conductive film in the present invention. A specific example of such a pressure-sensitive conductive film is a form in which, when a coin-type battery is viewed from above, a doughnut-shaped anisotropic conductive portion exists with an area equal to or larger than the gasket portion exposed on the surface. Furthermore, in the present invention, an anisotropic pressure-sensitive conductive film using conductive wires may have anisotropic conductivity, except for arrangements with intentional overlaps such as a lattice pattern. To achieve anisotropic conductivity, the conductive wires do not contact each other in the plane direction, either under load or load, and no electrical circuit is formed in the plane direction. The distance between adjacent non-contacting conductive wires is preferably 10 μm to 400 μm, more preferably 20 to 200 μm, and even more preferably 30 to 100 μm. Compared to conductive particles, conductive wires are less likely to shift, making it possible to reduce the distance between the wires. When the conductive wires 11 are regularly arranged as shown in Figures 11(A) to 11(C) and 11(E) to 11(H) above, the spacing between adjacent conductive wires 11, 11, as the shortest distance between the centers of the wire width of each conductive wire 11, is preferably at least twice the wire width, more preferably at least 2.5 times the wire width. This prevents contact with adjacent wires even when the shape of the wire is deformed by pressure, ensuring anisotropy.

[0045] Here, a method for measuring the resistance change of the pressure-sensitive conductive film due to the applied pressure will be described below.

[0046] The resistance change of the pressure-sensitive conductive film due to the applied pressure can be measured by, for example, attaching the film to a metal plate and applying a terminal from above using the DC or AC method. The DC method is affected by heat generation depending on the measurement time, making it difficult to obtain stable values, so the AC method is preferable. In addition, in order to reliably confirm the influence of the contact surface with the coin battery, the AC method (1KH) is used with the pressure-sensitive conductive film attached to the coin battery. Ｚ ) is preferable. It is preferable to measure at several locations. For example, three locations in total, including the center of the film and two locations near the outermost periphery, and preferably two more locations between the center and the outermost periphery, for a total of five or more locations. Other locations may also be measured, but film uniformity can also be confirmed by measuring at regular intervals, for example, 1 mm intervals. To confirm anisotropic conductivity, the positive electrode case or sealing plate near the crimped portion is measured. Without anisotropy, the resistance value will be lower than that of the battery alone. The applied load is 0.1 to 10 N, preferably 0.3 to 7 N, and more preferably 0.5 to 5 N.

[0047] The resistance value of a battery with a pressure-sensitive conductive film measured using the above-described measurement method is preferably 500 Ω or more, more preferably 1000 Ω or more, under near-unloaded conditions (e.g., 0.01 N). At pressures above a threshold, the resistance value is preferably 50 Ω or less, more preferably 30 Ω or less, and even more preferably 10 Ω or less. Alternatively, the resistance value of a battery without a pressure-sensitive conductive film can be measured in advance, and the resistance value can be subtracted from the resistance value of a battery with a pressure-sensitive conductive film to evaluate the resistance value of the pressure-sensitive conductive film. The resistance value based on this difference is preferably 10 Ω or less, more preferably 5 Ω or less, and even more preferably 2 Ω or less, above a threshold pressure. The resistance of a typical coin-type battery varies depending on its size, but is typically around 3 Ω to 40 Ω.

[0048] First Elastomer Layer 9 The first elastomer layer 9 supports the conductive wire 11 and provides self-repairing properties. Various elastomers, such as silicone-based, acrylic-based, and urethane-based elastomers, can be used for the first elastomer layer 9. Regarding the physical properties of the first elastomer layer 9, the 100% modulus of the elastomer portion constituting the first elastomer layer 9 is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1.0 MPa or more. By ensuring that the 100% modulus of the elastomer portion constituting the first elastomer layer 9 is 0.1 MPa or more, the self-repairing properties can be more reliably exhibited, and by increasing the 100% modulus, the self-repairing properties can be further enhanced. The 100% modulus of the elastomer portion constituting the first elastomer layer 9 is typically 10.0 MPa or less, and practically 7.0 MPa or less. The 100% modulus is the stress value at 100% elongation (2x elongation) of an elastomer obtained by a tensile test in accordance with JIS K 6251, and refers to the value obtained by dividing the tensile load by the cross-sectional area of ​​the test piece before the test. The 100% modulus of the elastomer portion constituting the first elastomer layer 9 is preferably in the range of 0.1 to 10.0 MPa, more preferably 0.5 to 7.0 MPa, and even more preferably 1.0 to 7.0 MPa.

[0049] The height of the conductive wire 11 protruding from the elastomer surface of the first elastomer layer 9 is preferably less than half (1 / 2d or less) of the thickness (d) of the conductive wire 11, and more preferably less than half (preferably 4 / 9d or less) of the thickness (d) of the conductive wire 11. By setting the protrusion height to such a value, the conductive wire 11 can be more securely held within the first elastomer layer 9, further enhancing self-repairing properties. Furthermore, the height of the conductive wire 11 protruding from the elastomer surface of the first elastomer layer 9 is preferably 1 / 20d or more, and more preferably 1 / 10d or more. This more reliably ensures high responsiveness upon contact with an external terminal. Furthermore, the protruding height of the conductive wire 11 is preferably greater than the thickness of the second elastomer layer.

[0050] The volume resistivity of the elastomer portion of the first elastomer layer 9 is preferably 1×10 ８ Ω cm or more, more preferably 1×10 １０ It is Ω·cm or more.

[0051] The thickness of the elastomer portion of the first elastomer layer 9 can be set appropriately taking into consideration the thickness (d) of the conductive wire 11, self-repair performance, etc. For example, it can be 5 to 100 μm, more preferably 10 to 100 μm, and even more preferably 20 to 100 μm. This preferred layer thickness is also preferably applied to embodiments 2 to 4 described below.

[0052] --Second Elastomer Layer 10-- The second elastomer layer 10 is a layer that ensures electrical insulation until exposed to a certain pressure. It also works in conjunction with the first elastomer layer to achieve self-repairing properties. The second elastomer layer 10 preferably has a tensile strength of 0.05 MPa or more. By making the tensile strength of the second elastomer layer 10 0.05 MPa or more, the second elastomer layer 10, which has been broken by the conductive wire 11, can be more reliably restored when the pressure is released. Furthermore, the tensile strength of the second elastomer layer 10 is preferably 8.0 MPa or less. By making the tensile strength 8.0 MPa or less, the second elastomer layer 10 can be more reliably broken by the conductive wire 11 when pressure is applied. The tensile strength is the maximum tensile force recorded when a test specimen is pulled until it breaks, as measured in accordance with JIS K 6251, divided by the cross-sectional area of ​​the test specimen before the test.

[0053] The second elastomer layer 10 is required to have electrical insulation properties, and its volume resistivity is preferably 1×10 ８ Ω cm or more, more preferably 1×10 １０ It is Ω·cm or more.

[0054] The thickness of the second elastomer layer 10 can be set appropriately taking into consideration the thickness of the conductive wire, insulating performance, etc. For example, it can be 0.1 to 100 μm, more preferably 1 to 80 μm, and even more preferably 2 to 50 μm. This preferred layer thickness is also preferably applied to embodiments 2 to 4 described below.

[0055] In the pressure-sensitive conductive film used in the present invention, the relationship between the thickness of the elastomer portion of the first elastomer layer and the thickness of the second elastomer layer can be appropriately set. From the viewpoint of achieving both low-resistance, rapid pressure-sensitive conductivity and self-repairing properties at a higher level, it is preferable that the thickness of the elastomer portion of the first elastomer layer is thicker than the thickness of the second elastomer layer.

[0056] The pressure-sensitive conductive film used in the present invention can have a thin second elastomer layer, which is a great advantage in improving the performance of the coin battery of the present invention and reducing dimensional constraints on the battery. The technical effects obtained by forming the second elastomer layer thin will be explained below in comparison with the technology described in Patent Document 1.

[0057] In the pressure-sensitive quantum tunnel composite coating (QTCC) described in Patent Document 1, a load is applied to a button battery in a dry state (without liquid) using a flat, fixed-area terminal (electrode), and the battery voltage is monitored using a direct current (DC) method. In the case of a button battery alone (without QTCC), the battery voltage (closed-circuit voltage) increases rapidly at a load of 1 N / sq cm after the terminal (electrode) contacts the battery, and then remains constant. In contrast, in the case of a button battery with a QTCC coating on its surface, the battery voltage (closed-circuit voltage) gradually increases over a displacement range of 0.1 to 0.2 mm once the load exceeds 25 N / sq cm. At a load of 100 N / sq cm, the battery voltage reaches a value equivalent to that of a button battery alone (without QTCC), and then remains constant. This indicates that the resistance of the QTCC membrane itself changes as the membrane thickness decreases by 0.1 to 0.2 mm within the load range of 25 N / sq cm to 100 N / sq cm. Some terminals in actual devices have sharp tips, and when concentrated and strong pressure is applied to only one area, the membrane thickness in that area becomes locally thin, resulting in electrical continuity and an anisotropic conductive state. In this anisotropic conductive state, current concentrates in the local conductive area, causing deterioration of the resin components of the membrane due to Joule heat. In contrast, the pressure-sensitive conductive membrane used in the present invention can be designed to have an ultrathin second elastomer layer, thereby enabling instantaneous formation of an electrical circuit from "external terminal - conductive wire - battery terminal" upon application of pressure. Moreover, the change in resistance due to load can be suppressed to a virtually negligible level. Furthermore, because the pressure-sensitive conductive membrane used in the present invention does not experience extreme current concentration like QTCC, it is possible to fully utilize battery performance even when applied to a variety of devices. Furthermore, the pressure-sensitive conductive film of the present invention has few restrictions on thickness and can be made thin to any desired thickness, thereby preventing limitations on battery capacity and dimensional influences when mounting the film on a device.

[0058] In the pressure-sensitive conductive film used in the present invention, the first elastomer layer and the second elastomer layer may contain pigments, dyes, etc. in order to confirm the quality of the coating state during layer formation. If the coating state can be confirmed by illuminating the film surface with a black light that emits long-wavelength ultraviolet rays (wavelength 315-400 nm, UVA, Ultraviolet A), it becomes easy to confirm the coating state of the film, which cannot be confirmed with normal light.

[0059] Regarding the material of the insulating coating 8, the insulating coating 8 may be made of an elastomer material, similar to the first and second elastomer layers. For example, rubber-based materials such as styrene butadiene rubber, butadiene rubber, butyl rubber, and fluorine-containing rubber may be used. Furthermore, the insulating coating material may contain a pigment or dye to check the coating condition of the insulating coating 8. It is preferable to illuminate the surface of the insulating coating with a black light that emits long-wavelength ultraviolet rays (wavelength 315-400 nm, UVA, Ultraviolet A) to check the coating condition, as this makes it easier to check the coating condition of the insulating coating.

[0060] --Manufacture of Pressure-Sensitive Conductive Film 12-- First, the second elastomer 10 can be formed by a coating method. For example, a second elastomer-containing liquid prepared by dissolving or dispersing the second elastomer in a solvent is applied to a release sheet and then dried to form the second elastomer layer 10. This second elastomer layer 10 can also be formed by applying a solution prepared by dissolving a UV-curable or thermosetting second elastomer precursor in a solvent, if necessary, to a release sheet, drying the solution as necessary, and then subjecting the solution to a curing reaction (addition reaction, condensation reaction, etc.) using UV light or heat. Note that if the second elastomer or its precursor is a low-viscosity liquid, dissolving or dispersing it in a solvent and drying it are not necessary. The thickness of the formed second elastomer layer 10 is preferably 0.1 to 100 μm, more preferably 1 to 80 μm, and even more preferably 2 to 50 μm.

[0061] Next, a first elastomer layer 9 is formed on the second elastomer layer 10. At this time, conductive wires 11 are placed on the second elastomer layer 10. This placement can be achieved by mounting using a mounter used for board mounting, dropping or placing wires on a substrate with a hole pattern formed using a mask, or pressing the surface of the second elastomer layer 10 of the battery against conductive wires 11 that have already been arranged in a regular pattern. In the case of a grid, placement is simply performed. Alternatively, wiring, in which a wiring pattern is directly drawn on the substrate, or a multi-wire system in which wiring is the basic process, can also be used. Next, for example, a first elastomer-containing liquid, obtained by dissolving or dispersing a first elastomer in a solvent, is applied to the second elastomer layer 10 and dried to form the first elastomer layer 9 on the second elastomer layer 10. The first elastomer-containing liquid can also be a solution obtained by dissolving a UV-curable or heat-curable first elastomer precursor in a solvent, as needed. In this case, after drying, a curing reaction (addition reaction, condensation reaction, etc.) can be carried out using ultraviolet light or heat to obtain the first elastomer layer 9 on the second elastomer layer 10. If the first elastomer or its precursor itself is a low-viscosity liquid, dissolution or dispersion in a solvent and drying are not necessary. In this case, the coating film formed on the second elastomer layer 10 can be cured using ultraviolet light or heat to obtain the first elastomer layer 9 on the second elastomer layer 10. The thickness of the elastomer portion of the formed first elastomer layer 9 is preferably 5 to 100 μm, more preferably 10 to 100 μm, and even more preferably 20 to 100 μm. The pressure-sensitive conductive film 12 thus obtained can be cut into a shape to be attached to the conductive substrate 13 of a coin battery (e.g., the top plate portion 6 a of the sealing plate), peeled off from the release sheet, and attached to the conductive substrate 13 so that the second elastomer layer and the conductive substrate 13 are in contact. In this way, a coin battery equipped with pressure-sensitive conductive film 12 can be obtained.

[0062] Furthermore, in the manufacture of a coin battery, the pressure-sensitive conductive film 12 can also be formed directly on the conductive substrate 13 such as the battery case 1 or the sealing plate 6. In this case, instead of using the release sheet described above, the second elastomer layer 10 and the first elastomer layer 9 are formed in sequence in the same manner as described above on the surface of the coin battery where pressure-sensitive conductivity is desired to be exhibited.

[0063] From the viewpoint of shortening the time required for forming the layers, it is preferable to use an ultraviolet-curable or heat-curable elastomer precursor for forming the first and second elastomer layers.

[0064] Another preferred embodiment of the pressure-sensitive conductive film used in the present invention will be described.

[0065] - Pressure-Sensitive Conductive Film [Mode 2] - Another example (Mode 2) of the pressure-sensitive conductive film 12 used in the present invention is shown in Figure 12. In Mode 2, before pressure is applied by an external terminal or the like, at least a portion of the conductive wire 11 held by the first elastomer layer 9 is in contact with the conductive substrate 13. A second elastomer layer 10 is provided on the side of the conductive wire 11 opposite the conductive substrate 13. While the second elastomer layer 10 ensures insulation, when pressure is applied by the external terminal in a vertical direction toward the conductive substrate 13 to a certain level or more, the second elastomer layer 10 directly above the conductive wire 11 is broken by the external terminal, achieving good electrical continuity. Furthermore, as with Mode 1, the pressure exhibits self-healing properties when the pressure is released. The pressure-sensitive conductive film of Mode 2 can be formed appropriately in accordance with the method for forming each layer of the pressure-sensitive conductive film of Mode 1.

[0066] - Pressure-Sensing Conductive Film [Configuration 3] - Another example (Configuration 3) of the pressure-sensitive conductive film 12 used in the present invention is shown in Figure 13. In Configuration 3, second elastomer layers 10 are provided on both sides of a first elastomer layer 9 holding a conductive wire 11, and these two second elastomer layers 10 contact both ends of at least some of the conductive wires. While the second elastomer layers 10 ensure insulation, when pressure is applied vertically toward the conductive substrate 13 by an external terminal to a certain level, the second elastomer layer 10 directly above the conductive wire 11 is broken by the external terminal, and the conductive wire 11 also breaks through the second elastomer layer on the conductive substrate 13 side, achieving good electrical continuity. Furthermore, as with Configuration 1, the pressure-sensitive conductive film exhibits self-healing properties when released. The pressure-sensitive conductive film of Configuration 3 can be formed as appropriate using the same methods for forming each layer of the pressure-sensitive conductive film of Configuration 1.

[0067] - Pressure-Sensing Conductive Film [Mode 4] - Another example (Mode 4) of the pressure-sensitive conductive film 12 used in the present invention is shown in Figure 14. Mode 4 is a pressure-sensitive conductive film in which the surface of the conductive wire 11 protruding from the first elastomer layer 9 in Mode 1 is coated with the second elastomer layer 10. This configuration more reliably ensures insulation when not under a predetermined pressure. Mode 4 is a configuration in which the conductive wire 11 in Mode 1 is coated with the constituent material of the second elastomer layer. Here, in the present invention, the "first elastomer layer" and the "second elastomer layer" are distinguished not by the difference in material but by the difference in function in achieving the effects of the present invention. Therefore, in Mode 4, the conductive wire 11 is coated with the constituent material of the second elastomer layer 10, but only a portion of this coating constitutes the second elastomer layer 10. That is, of the coating layer, the portion that protrudes from the elastomer portion of first elastomer layer 9 in the thickness direction of pressure-sensitive conductive film 12 (in FIG. 14, the coating layer that covers the portion of conductive wire 11 that protrudes from the elastomer portion of first elastomer layer 9) is second elastomer layer 10, and the other layered portion (the coating layer portion covered with the first elastomer) constitutes first elastomer layer 9. Therefore, in FIG. 14, second elastomer layer 10 arranged on first elastomer layer 9 exists in a state where it is divided by the elastomer portion of the first elastomer layer in the planar direction. The pressure-sensitive conductive film of form 4 can be formed appropriately in accordance with the method for forming each layer of the pressure-sensitive conductive film of form 1.

[0068] The above describes the form of the pressure-sensitive conductive film, but the pressure-sensitive conductive film used in the present invention is not limited to the above form as long as it satisfies the provisions of the present invention, and various modifications of each of the above forms can be applied as the pressure-sensitive conductive film of the coin battery of the present invention.

[0069] The coin battery of the present invention, whose pressure-sensitive conductive film has the above-described specific structure and exhibits self-repairing properties, can effectively prevent damage to a living body caused by accidentally swallowing the coin battery, even if the coin battery is removed from a device after being attached to the device. Furthermore, the configuration in which the conductive wire is disposed in a single layer within the first elastomer layer further reduces variations in pressure response and electrical conductivity, resulting in excellent electrical characteristics. That is, under pressure above a certain level, a low-resistance electrical conductivity state can be quickly achieved, and extreme current concentration is unlikely to occur.

[0070] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0071] This application claims priority based on Japanese Patent Application No. 2024-152422, filed on September 4, 2024, the contents of which are incorporated herein by reference as part of the present specification.

[0072] The coin battery according to the present invention can be used in a variety of devices and has great industrial value.

[0073] REFERENCE SIGNS LIST 1 Battery case 1a Bottom plate portion 1b Side portion 2 Positive electrode 3 Negative electrode 4 Separator 5 Gasket 6 Sealing plate 6a Top plate portion 6b Peripheral portion 7 Pressure-sensitive conductive film 8 Insulating coating 9 First elastomer layer 10 Second elastomer layer 11 Conductive wire 12 Pressure-sensitive conductive film 13 Conductive substrate (battery case or sealing plate of coin-shaped battery)

Claims

1. A coin-type battery comprising: a battery case having a bottom plate and a side portion rising from the periphery of the bottom plate; a sealing plate having a top plate and a periphery portion extending inward from the top plate to the side portion; a gasket compressed and interposed between the side portion and the periphery portion; a power generation element sealed by the battery case, the sealing plate, and the gasket; and a pressure-sensitive conductive film disposed on at least one outer surface of the battery case and the sealing plate, wherein the pressure-sensitive conductive film comprises a first elastomer layer holding a conductive wire and a second elastomer layer disposed on at least one surface of the first elastomer layer and in contact with the conductive wire held by the first elastomer layer, the thickness of the conductive wire being greater than or equal to the thickness of the elastomer portion of the first elastomer layer, and the conductive wire being arranged in a single layer in the planar direction of the first elastomer layer.

2. The coin battery according to claim 1, wherein the thickness of the conductive wire is greater than the thickness of the elastomer portion of the first elastomer layer.

3. The coin battery according to claim 1 or 2, wherein a second elastomer layer is disposed in contact with the outer surface of at least one of the battery case and the sealing plate.

4. A coin battery as described in claim 1 or 2, wherein the conductive wire in contact with the second elastomer layer protrudes beyond the elastomer portion of the first elastomer layer toward the side opposite the second elastomer layer.

5. The coin battery according to claim 1, wherein the conductive wires are partially overlapped and formed in a lattice pattern.

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