coin cell battery

Abstract

This invention provides a coin-type battery that further suppresses variations in pressure response and current-carrying characteristics, achieving both excellent electrical properties and safety in case of accidental ingestion. [Solution] A coin-type battery comprising a battery case 1 having a bottom plate portion 1a and a side portion 1b rising from the periphery of the bottom plate portion, a sealing plate 6 having a top plate portion 6a and a peripheral portion 6b extending inward from the top plate portion to the side portion, a gasket 5 compressed and interposed between the side portion and the peripheral portion, a power generation element sealed by the battery case, the sealing plate, and the gasket, and a pressure-sensitive conductive film 7 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 that holds 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 is greater than or equal to the thickness of the elastomer portion of the first elastomer layer, and the conductive wire is arranged in a single layer in the planar direction of the first elastomer layer.

Description

Technical Field

[0001] The present invention relates to coin-shaped batteries, and more particularly to coin-shaped batteries with enhanced safety against accidental ingestion.

Background Art

[0002] Coin-shaped batteries are widely used as power sources for small devices and memory backups. In a general coin-shaped battery, a power generation element including pellet-shaped positive and negative electrodes, a separator interposed between these electrodes, and an electrolytic solution is housed in an exterior body composed of a battery case, a sealing plate, and a gasket. The opening of the battery case is sealed by caulking the peripheral edge of the sealing plate through the gasket.

[0003] With the expansion of the applications of coin-shaped batteries, the number of accidental ingestion incidents has also increased, and the importance of countermeasures against accidental ingestion of coin-shaped batteries has grown. When a coin-shaped battery is taken into the body, the respective terminal surfaces of the battery case and the sealing plate come into contact with body fluid, causing a short circuit between the positive and negative electrodes. Due to this short circuit, a current accompanied by electrolysis of water flows, and the body fluid on the negative terminal side changes to an alkaline state. This alkaline body fluid damages living tissues such as the esophageal wall.

[0004] Patent Document 1 describes a technology to address the accidental ingestion of coin-type batteries. This technology uses a pressure-sensitive quantum tunneling composite coating (QTCC) film in which conductive microparticles with nanoscale roughness on their surface are dispersed in a polymer matrix such as silicone elastomer. When a pressure exceeding a threshold is applied to this pressure-sensitive coating film, the distance between the conductive microparticles decreases, and the quantum tunneling effect causes it to become conductive. Conversely, even if a pressure below the threshold is applied, the quantum tunneling effect is not obtained because the distance between the conductive microparticles is large, and an electrically insulating state is maintained. According to Patent Document 1, by covering at least one of the positive or negative terminals of a coin-type battery with such a pressure-sensitive coating film, the threshold for pressure-sensitive conductivity is made greater than the pressure experienced in the digestive tract of the human body. This is said to prevent a short circuit of the battery in the digestive tract when a coin-type battery is accidentally ingested.

[0005] Furthermore, the coin-type battery described in Patent Document 2 has a pressure-sensitive conductive film on its outer surface that contains conductive particles and has a specific layered structure. As a result, the coin-type battery has superior pressurized current conduction characteristics and superior safety in case of accidental ingestion compared to the one described in Patent Document 1. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent No. 9741975 [Patent Document 2] Japanese Patent Publication No. 2021-57113 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Coin-type batteries conduct electricity through pressure applied in the thickness direction, and it is necessary to suppress variations in pressure response and current conduction characteristics at the contact points with the terminals (external terminals) of the device. From this perspective, in coin-type batteries described in Patent Document 2, there is a growing need for even greater uniformity of the particle size of conductive particles with extremely high precision. However, conductive particles typically exhibit a particle size distribution, limiting their uniformity. While it's possible to reduce the particle size distribution by methods such as sieving, completely eliminating it is difficult. Under these circumstances, further minimizing the particle size distribution could lead to a decrease in the yield of conductive particles and a corresponding increase in the manufacturing cost of coin-type batteries. Therefore, there is room for improvement in coin-type batteries from the perspective of improving quality and enabling industrial mass production.

[0008] In view of the above, the present invention aims to provide a coin-type battery that further suppresses variations in pressure response and current-carrying characteristics, thereby achieving both excellent electrical characteristics and safety in case of accidental ingestion. [Means for solving the problem]

[0009] The above-mentioned problems of the present invention were solved by the following means. [1] A battery case having a base plate and side portions rising from the periphery of the base plate, A sealing plate having a top plate portion and a peripheral edge portion extending inward from the top plate portion to the side portion, A gasket is compressed and interposed between the side portion and the peripheral portion, The power generation element is sealed by the battery case, the sealing plate, and the gasket, A pressure-sensitive conductive film disposed on at least one of the outer surfaces of the battery case and the sealing plate, It has, The pressure-sensitive conductive film comprises a first elastomer layer that holds 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. A coin-type battery in which the thickness of the conductive wire is greater than or equal to the thickness of the elastomer portion of the first elastomer layer, and the conductive wire is arranged in a single layer in the planar direction of the first elastomer layer. [2] The coin-shaped 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-shaped battery according to [1] or [2], wherein the second elastomer layer is disposed in contact with at least one of the outer surfaces of the battery case and the sealing plate. [4] The coin-shaped battery according to [1] or [2], wherein the conductive wire in contact with the second elastomer layer protrudes more than the elastomer portion of the first elastomer layer toward the side opposite to the second elastomer layer. [5] The coin-shaped battery according to [1], wherein the conductive wires partially overlap and are formed in a lattice shape.

[0010] In the present invention, the numerical range represented by "~" means a range including the numerical values described before and after as the lower limit value and the upper limit value. [Advantages of the Invention]

[0011] The coin-shaped battery of the present invention can further suppress variations in pressure response and electrical conduction characteristics, and can achieve both excellent electrical characteristics and safety in case of accidental ingestion. [Brief Description of the Drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of a general coin-shaped battery. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a preferred configuration of the coin-shaped battery of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a preferred configuration of the coin-shaped battery of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a preferred configuration of the coin-shaped battery of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a preferred configuration of the coin-shaped battery of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a preferred configuration of the coin-shaped battery of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a preferred form of the coin-shaped battery of the present invention. [Figure 8] FIG. 8 is a schematic cross-sectional view showing a preferred form of the coin-shaped battery of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a preferred form of the coin-shaped battery of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a preferred form of the pressure-sensitive conductive film used in the present invention. [Figure 11] FIGS. 11(A) to (C) are schematic plan views showing an example in which the shape of the conductive wire in plan view is linear and the conductive wires are arranged in the plane direction of the first elastomer layer with their wire lengths aligned with each other. FIG. 11(D) is a schematic plan view showing an example in which the shape of the conductive wire in plan view is linear and the conductive wires are arranged in various directions in the plane direction of the first elastomer layer. FIGS. 11(E) and (F) are schematic plan views showing an example in which the shape of the conductive wire in plan view is curved and the conductive wires are arranged in a concentric or spiral shape in the plane direction of the first elastomer layer. FIGS. 11(G) and (H) are schematic plan views showing an example in which the shape of the conductive wire in plan view is curved and the conductive wires are arranged in a concentric shape with some wire missing at the circumferential part in the plane direction of the first elastomer layer. FIG. 11(I) is a schematic plan view showing an example in which the shape of the conductive wire in plan view is linear and the conductive wires are arranged in a grid pattern in the plane direction of the first elastomer layer. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a preferred form of the pressure-sensitive conductive film used in the present invention. [Figure 13] FIG. 13 is a schematic cross-sectional view showing a preferred form of the pressure-sensitive conductive film used in the present invention. [Figure 14] FIG. 14 is a schematic cross-sectional view showing a preferred form of the pressure-sensitive conductive film used in the present invention.

Embodiments for Carrying Out the Invention

[0013] [Coin-shaped Battery] Preferred embodiments of the coin-type battery of the present invention will be described with reference to the drawings. Note that these drawings are explanatory diagrams to facilitate understanding of the present invention, and the sizes or relative sizes of the components may be altered for illustrative purposes, and do not necessarily reflect the actual relationships. Furthermore, the external appearance and shape shown in these drawings are not limited to matters specified in the present invention. In the present invention, "coin-type 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 with a thickness greater than its diameter is also included in the definition of a coin-type battery.

[0014] Figure 1 is a schematic longitudinal cross-sectional view showing the configuration of a typical coin-type battery. The coin-type battery shown in Figure 1 comprises an exterior body consisting of a battery case 1, a sealing plate 6, and a gasket 5. The battery case 1 has a bottom plate portion 1a and side portions 1b that rise from the periphery of the bottom plate portion 1a, and is a shallow, circular battery can in plan view. The sealing plate 6 has a top plate portion 6a and a peripheral edge portion 6b that extends from the top plate portion 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 edge 6b of the sealing plate 6. In other words, the gasket 5 is positioned inside the side portion 1b of the battery case 1 and outside the peripheral edge 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 and the sealing plate 6, it is preferable that the gasket 5 be positioned so as to cover the peripheral edge 6b of the sealing plate 6, including the end of the peripheral edge 6b.

[0015] The power generation element is housed inside the outer casing. The power generation 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 positioned in contact with the bottom plate portion 1a of the battery case 1. Therefore, the outer surface of the bottom plate portion 1a of the battery case 1 functions as a positive electrode terminal. On the other hand, the negative electrode 3 is positioned in contact with the top plate portion 6a of the sealing plate 6. Therefore, the outer surface of the top plate portion 6a of the sealing plate 6 functions as a negative electrode terminal.

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

[0017] In the configuration shown in Figure 1, the material used to form 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 (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, SM, and SPCC as specified in JIS. Carbon steel refers to steel materials such as S10C, S20C, S30C, S45C, and S55C, and belongs to alloy steels for machine structures. When using ordinary steel or carbon steel, it is desirable to form a rust-preventive plating layer (e.g., a nickel plating layer) on the inner surface of the battery. Typically, nickel plating layers are formed on both the inner and outer surfaces of the sealing plate made of ordinary steel or carbon steel. Nickel plating layers are also formed on the outer surface of the sealing plate made of stainless steel.

[0018] The coin-type battery of the present invention has a pressure-sensitive conductive film, described later, disposed on at least one of the outer surfaces of the battery case 1 and the sealing plate 6 (i.e., 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 according to the purpose, as long as it does not impair the effects of the present invention. Preferred examples of 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 portion 6a of the sealing plate 6. In this case, an insulating coating 8 must be applied to the exposed parts of the sealing plate 6 other than the top portion 6a to prevent external short circuits 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 viewpoint of more reliably preventing the intrusion of bodily fluids in the event of accidental ingestion, it is preferable to apply this insulating coating 8 so as to cover both ends from the end of the pressure-sensitive conductive film 7 to the end of the side portion 1b of the battery case 1 (this configuration is shown in Figure 2).

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

[0021] <Arrangement of pressure-sensitive conductive film - 3> As shown in Figure 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, the ends of the side portion 1b of the battery case 1 need to be coated with an insulating coating 8 to prevent external short circuits in the event of accidental ingestion. This insulating coating 8 can be provided from the end 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 external short circuits in the event of accidental ingestion. Alternatively, it can be applied from the end of the pressure-sensitive conductive film 7 to the end of the top plate portion 6a of the sealing plate 6, covering both ends (this configuration is shown in Figure 4).

[0022] <Arrangement of pressure-sensitive conductive film - 4> As shown in Figure 5, the outer surface of the battery case 1 and the area from the end of the side portion 1b of the battery case 1 to the middle of the gasket 5 can also be directly covered with the pressure-sensitive conductive film 7. In this case, since there are no exposed parts on the surface of the battery case 1, treatment with the insulating coating 8 is not necessarily required. However, from the viewpoint of more reliably preventing the intrusion of bodily fluids and external short circuits in the event of accidental ingestion, the coating can be applied from the end 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 end of the pressure-sensitive conductive film 7 to the end of the top plate portion 6a of the sealing plate 6, i.e., covering both ends (Figure 5 shows this configuration).

[0023] The insulating coating 8 shown in Figures 2 to 5 can be applied after the pressure-sensitive conductive film is placed on the coin-type battery, but the present invention is not limited to this embodiment. As for coating methods, for example, one method is to apply or spray a coating solution prepared by dissolving an insulating material in a solvent, and then form an insulating film by volatilizing the solvent.

[0024] As described above, it is preferable to provide an insulating coating 8 for arrangements 1 to 4 of the pressure-sensitive conductive film. On the other hand, by restricting the arrangement of the conductive wires responsible for the conductivity of the pressure-sensitive conductive film to a configuration in which they do not overlap (for example, the configurations shown in Figures 11(A) to (H)), it is possible to impart an anisotropic function to the pressure-sensitive conductive film, which prevents conduction in the planar direction even when pressure exceeds a threshold. Note that the above configuration in which they do not overlap may include some overlap that occurs unintentionally and accidentally. By using such an anisotropic pressure-sensitive conductive film, it is possible to more reliably prevent the intrusion of bodily fluids in the event of accidental ingestion and external short circuits simply by arranging this pressure-sensitive conductive film to cover a desired part of the battery surface, without providing an insulating coating 8. An example of such a configuration will be described below. Details regarding the arrangement of conductive wires to give the pressure-sensitive conductive film anisotropic function will be described later.

[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 and the end of the side portion 1b of the battery case 1 are integrally covered with the pressure-sensitive conductive film 7 so as to cover the end. In this configuration, as mentioned above, it is preferable to arrange the conductive wires so that they do not overlap each other. This is preferable because the pressure-sensitive conductive film 7 has an anisotropic function and does not conduct in the planar direction, thus more reliably preventing external short circuits in the event of accidental ingestion without the need for an insulating coating 8. (Figure 6 shows this configuration).

[0026] <Arrangement of pressure-sensitive conductive film - 6> As shown in Figure 7, the entire outer surface of the battery case 1 and the peripheral edge 6b of the sealing plate 6 can be integrally covered with the pressure-sensitive conductive film 7. In this configuration, as mentioned above, it is preferable to arrange the conductive wires so that they do not overlap with each other. This allows the pressure-sensitive conductive film 7 to have an anisotropic function. In this case, it is preferable to integrally cover the entire outer surface of the battery case 1 and the edge or vicinity of the top plate portion 6a of the sealing plate 6 with the pressure-sensitive conductive film 7. This is preferable because it can more reliably prevent external short circuits in the event of accidental ingestion without the need for an insulating coating 8.

[0027] The details of the pressure-sensitive conductive film's configuration will be described later, but when the pressure-sensitive conductive film is in contact with 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 the desired location, and a first elastomer layer 9 containing conductive wires can be provided as a single layer in the planar direction in the desired location on the second elastomer 10. An example of such a configuration is shown in Figures 8 and 9. Furthermore, in configurations where conductive wires are intentionally partially overlapped, such as the lattice-like configuration shown in Figure 11(I), it is more preferable to arrange an insulating coating 8, as shown in Figures 2-5, in addition to the second elastomer layer 10 which has an insulating coating function.

[0028] (Pressure-sensitive conductive film) The pressure-sensitive conductive film used in the present invention is in an insulating (high-resistance) state when no external pressure exceeding a certain level is applied, and can create a conductive (low-resistance) state in the film thickness direction when an external pressure exceeding a certain level is applied. The pressure-sensitive conductive film used in the present invention comprises a first elastomer layer that holds conductive wires, and a second elastomer layer disposed on at least one surface of the first elastomer layer, with at least some of the conductive wires held by the first elastomer layer in contact with it. 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-sensitive conductive film [Form 1]- A preferred example (Embodiment 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 Embodiment 1 has a first elastomer layer 9 that holds the conductive wire 11 (the first elastomer and the conductive wire 11 together are referred to as the first elastomer layer 9), and a second elastomer layer 10 disposed on the lower surface of the first elastomer layer 9 and in contact with 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-type battery). Note that some of the conductive wire 11 may not be in contact with the second elastomer layer 10. The conductive wire 11 has a thickness 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. However, some conductive wires 11 may not protrude from the elastomer portion of the first elastomer layer 9. Also, individual conductive wires 11 may include portions that do not protrude. From a manufacturing perspective, in Embodiment 1, the conductive wire 11 held by the first elastomer layer 9 and in contact with the second elastomer layer 10 may be partially included on the side of the second elastomer layer 10, but it is preferable that it does not protrude. Furthermore, it is preferable that the conductive wire 11 in contact with the second elastomer layer 10 protrudes from the elastomer portion of the first elastomer layer 9 toward the opposite side from the second elastomer layer 10. The "thickness" (d) of the conductive wire 11 refers to the height of the conductive wire 11 when its length 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 the cross-section of the conductive wire 11 in the thickness direction (the cross-section in the thickness direction along the wire width perpendicular to the wire length direction described later). If the cross-section of the conductive wire 11 in the thickness direction is circular, its diameter is the "thickness". In the case where the thicknesses of the conductive wires 11 are arranged in a state where they partially overlap 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 in the portion where the conductive wires 11 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 becomes greater than the "thickness" (d) of the portion that does not overlap, and the state of protrusion from the elastomer portion of the first elastomer layer 9 becomes more clearly defined.

[0030] In Embodiment 1, when a certain amount of pressure is applied to the pressure-sensitive conductive film 12 in the thickness direction (from top to bottom in Figure 10) by an external contact terminal (external terminal), the conductive wire 11 held in the first elastomer layer 9 penetrates the second elastomer layer 10, and the conductive base material 13 and the external terminal are electrically connected by the conductive wire 11. In other words, an electrical circuit of "external terminal - conductive wire 11 - conductive base material 13" is formed. The elastomer layer is not involved in the conductivity of this electrical circuit, and therefore the resistance does not depend on the applied pressure from the outside, thus achieving a low-resistance conductive state.

[0031] In Embodiment 1, the conductive wire 11 is arranged in a single layer in the planar direction of the first elastomer layer 9. Therefore, the pressure-sensitive conductive film 12 can quickly create a low-resistance current-conducting state in the film thickness direction by applying pressure in the thickness direction. In this invention, "conductive wires are arranged in a single layer in the planar direction of the first elastomer layer" means that the conductive wires are arranged substantially in a single layer in the planar direction of the first elastomer layer. That is, to the extent that the effects of this invention are not impaired, two or more conductive wires may overlap in the thickness direction of the first elastomer layer in a part of the first elastomer layer (for example, a wire may be resting between conductive wires, or two wires may overlap in the film thickness direction). The form in which "conductive wires are arranged in a single layer in the planar direction of the first elastomer layer" means that in the area of ​​conductive wires observed in a planar view of the first elastomer layer 9, 80% or more of the area is arranged in a single layer without overlapping in the film thickness direction, and it is also preferable that all conductive wires are arranged in a single layer without overlapping in the film thickness direction. However, as shown in Figure 11(I), in a configuration where the conductive wires 11, 11 are arranged in a single layer as a single, lattice-like unit, if the thickness of the conductive wires 11 partially overlaps in the thickness direction (film thickness direction) (for example, in a two-tiered arrangement), it is preferable that 50 to 80% of the area of ​​the conductive wires observed in plan view of the first elastomer layer 9 is arranged in a single layer without overlapping in the film thickness direction.

[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. As a result, the conductive wire 11 protrudes 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 the external terminal (contact terminal). That is, this includes the case 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. Furthermore, it is 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. By doing so, when the conductive wire 11 is pressed above a certain level and in contact with the conductive substrate 13, contact between the conductive wire 11 and the external terminal can be reliably ensured, and fluctuations in resistance due to pressure changes can be further suppressed.

[0033] In the pressure-sensitive conductive film of Form 1, when the applied pressure is released, the combined elasticity of the first elastomer layer 9 and the second elastomer layer 10 allows the conductive wire 11 to return to its position before pressurization (the state shown in Figure 10). As the conductive wire 11 returns to its position before pressurization, any tears in the second elastomer layer 10 are sealed by its own elasticity, restoring the initial insulating state. This recovery property is referred to as "self-healing property" in this invention.

[0034] Because the pressure-sensitive conductive film 12 exhibits self-healing properties, even when the coin-type battery is inserted into or removed from an electronic device, it prevents external short circuits in the event of accidental ingestion, while maintaining a stable conductive state in response to the pressure applied to the device's terminals during use.

[0035] Next, we will explain in more detail the conductive wire 11, the first elastomer layer 9, and the second elastomer layer 10 in Embodiment 1.

[0036] --Conductive wire 11-- The term "wire" in "conductive wire 11" refers to a conductive wire 11 whose aspect ratio (wire length / wire width) in plan view is 3 or greater, more preferably 5 or greater. This aspect ratio is the ratio of wire length to wire width (wire length / wire width) when the conductive wire 11 is held in the first elastomer layer 9 and observed in plan view. The wire length refers to the length of the conductive wire 11 along its extension direction. For example, if the conductive wire 11 is straight, its straight length is the wire length; if the conductive wire 11 is curved, its length along the curve is the wire length. The wire width refers to the length of the conductive wire 11 in the direction perpendicular to the wire length. In plan view observation of the wire length and wire width, the wire length is the length in the extension direction passing through the center of the wire width. "Plan view observation" or "plan view" of the conductive wire 11 refers to observing the conductive wire 11 from above with its length aligned along the planar direction of the elastomer portion of the first elastomer layer 9. If the conductive wire 11 cannot be visually observed due to the presence of the elastomer portion, the observation shall be made excluding the covering elastomer portion.

[0037] Since the conductive wire 11 is integrally formed by stretching in the length direction, the variation in diameter (thickness) in the length direction is smaller than that of particle bodies formed from separate materials. Therefore, when current is generated by pressurizing in the thickness direction in a coin-type battery, the influence of differences in diameter (thickness) at the pressurizing location can be significantly reduced. Furthermore, as shown in the aspect ratio described above, the conductive wire 11 has a wire length relative to its wire width, resulting in higher positional stability in the first elastomer layer 9 compared to the particle form. This reduces the displacement of the conductive wire 11 in the planar direction when subjected to pressure in the thickness direction. Additionally, even if external forces such as vibration or tilting are applied to the coin-type 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 for the current-conducting operation due to pressure in the height direction to occur more stably. In addition, using a wire instead of particles improves absolute strength and allows the pressure to be dispersed along the wire length. As a result, in this invention, the risk of cracking or breakage when excessive pressure is applied is further reduced compared to the particle form, ensuring more stable conductivity. Moreover, depending on the shape of the external terminal, using a wire instead of particles results in lower resistance at the wire's conductivity points compared to the multiple conductivity points of particles, reducing the impact of heat generation due to conductivity on the elastomer, thus stabilizing the response characteristics over a long period. As a result, the coin-type battery of the present invention can further suppress variations in pressure response and current-carrying characteristics, thereby achieving excellent electrical properties.

[0038] The shape of the cross-section in the thickness direction of the conductive wire 11 (the cross-section in the thickness direction along the wire width) can be varied as long as it does not impair the effects of the present invention. For example, as mentioned above, it can be circular, elliptical, or polygonal. In the case of a polygon, it is preferable that the number of sides be even from the viewpoint of arrangement stability in the first elastomer layer 9. If the cross-section of the conductive wire 11 in the thickness direction is circular, its diameter is the line width observed in plan view as described above. If the cross-section of the conductive wire 11 in the thickness direction is other than circular (for example, elliptical or polygonal), the line width is the width observed in plan view when the conductive wire 11 is positioned with its length aligned along the planar direction of the elastomer portion of the first elastomer layer 9. In this case, if 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 along the planar direction but also along the thickness direction. If 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 in the polygon to the opposite side or point passing through the center may be aligned not only along the planar direction but also along the thickness direction. Furthermore, if 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 as defined above shall be the average value calculated with N=3 or 5.

[0039] The conductive wire 11 is positioned with its length oriented in the planar direction of the first elastomer layer 9. The shape of the conductive wire 11 in plan view and its arrangement in the planar direction of the first elastomer layer 9 can be varied as long as they do not impair the effects of the present invention. For example, as shown in Figures 11(A) to (C), the conductive wire 11 may have a linear shape in plan view, and the conductive wires 11 may be arranged in the planar direction of the first elastomer layer 9 with their wire lengths aligned. This allows for easier and more regular arrangement of conductive wires compared to conductive particles. Stable response characteristics can be obtained without deviations, cracks, or fractures in response to various external terminal shapes and the strength and direction of external stress. Anisotropy can also be ensured. As shown in Figure 11(D), the conductive wire 11 may have a linear shape in plan view, and the conductive wire 11 may be arranged in various orientations in the planar direction of the first elastomer layer 9. This increases the degree of freedom in arrangement, allowing the conductive wires to be arranged more easily and randomly than conductive particles. In addition, stable response characteristics can be obtained without displacement, cracks, or fractures in response to the strength and direction of external stress. Furthermore, anisotropy can also be ensured. As shown in Figures 11(E) and (F), the conductive wire 11 may have a curved shape in plan view, and the conductive wire 11 may be arranged concentrically or spirally in the planar direction of the first elastomer layer 9. Alternatively, as shown in Figures 11(G) and (H), the conductive wire 11 may have a shape in plan view that does not form a closed circle (for example, a shape similar to a Landolt ring), and may be arranged concentrically. These methods allow for easier and more regular arrangement of conductive wires compared to conductive particles. This is particularly effective when conductivity is established via external terminals in the circumferential direction of a coin-type battery. As the wire length increases, the absolute strength increases, and the arrangement area also increases. This results in stable response characteristics without deviation, cracks, or fractures in response to various external terminal shapes and the strength and direction of external stresses. Furthermore, the heat dissipation of heat generated during conductivity is improved, reducing thermal effects and ensuring long-term response stability. Anisotropy can also be ensured. As shown in Figure 11(I), the conductive wire 11 may have a linear shape in plan view, and the conductive wires 11 may be arranged in a grid pattern in the planar direction of the first elastomer layer 9. This makes it easier to arrange the conductive wires in a grid pattern compared to other conductive wires. As the length of the wires increases, the overlapping portions of the wires are also added, resulting in higher absolute strength and a larger arrangement area. This allows for stable response characteristics without displacement, cracks, or breaks in response to various external terminal shapes and the strength and direction of external stresses. Furthermore, the heat dissipation of heat generated during conduction is improved, reducing thermal effects and ensuring long-term response stability. In this grid arrangement, the form of the overlapping portions of the grid may be either a form in which the thicknesses of the conductive wires 11 overlap in the thickness direction (film thickness direction) (for example, a form where they overlap in two layers), or a form in which the conductive wires are connected at the same height position in the thickness direction (a form where they are connected in a single layer three-dimensionally, like a lattice door).

[0040] The cross-section of the conductive wire 11 in the thickness direction is preferably circular. Circularity can be determined by magnified observation, etc. In this invention, "circular" refers to being circular, and includes not only perfectly circular shapes but also approximately circular shapes that can be recognized as circular at a glance. The aforementioned "perfectly circular" is indicated by the degree of roundness. This degree of roundness is the ratio of the length of the shortest line segment to the length of the longest line segment among a plurality of line segments that pass through the center of the cross-section in the thickness direction of the conductive wire 11 and connect two points on the outer edge. The degree of roundness is 1 (i.e., 100%), and the closer the degree of roundness is to 1, the closer it is to a perfect circle. When the conductive wire 11 is perfectly round, the degree of roundness is preferably 0.80 to 1.0, and more preferably 0.90 to 1.0. Furthermore, the aforementioned "perfectly circular shape" may be defined by the degree of circularity shown below. The degree of circularity can be determined based on the cross-section in the thickness direction of the conductive wire 11. The degree of circularity has a maximum value of 1, and the more complex the shape, the smaller the value. The degree of circularity can be calculated using the following formula. Roundness = 4π × (area) ÷ (perimeter) 2 For example, in the case of a perfect circle with a radius of 10, the degree of circularity = "4π × (10 × 10 × π) ÷ (10 × 2 × π)" 2 The value of '' is 1 (maximum value). In other words, in terms of circularity, a perfect circle is the simplest 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 between 0.7 and 1.0. The roundness and circularity of the conductive wire 11 can be measured by the following methods: by cutting the wire and measuring from cross-sectional observation, or by non-destructive cross-sectional observation using X-ray CT.

[0041] The material of the conductive wire 11 is not particularly limited as long as it can ensure conductivity. Examples include metal wires and metal-coated wires. Metal wires can be formed by stretching along the length of the wire, making it possible to achieve uniformity of diameter with greater precision and at a lower cost than with granular materials. Metal-coated wires can be made by coating a metal-coated wire base material with metal by plating on a metal wire produced by the above method, making it possible to achieve uniformity of diameter with greater precision and at a lower cost than with granular materials. Furthermore, the conductive wire 11 can also be made from recycled waste materials. Reusing waste materials can lead to greater cost reduction and contribute to reducing environmental impact. Examples of metal wires include various materials used as conductive wires, such as Au, Ag, Cu, Fe, Al, Ni, Pd, platinum, stainless steel, and alloys of the aforementioned metals. Examples of metal-coated wires include copper-silver coated wires, steel-zinc coated wires, piano wire-zinc coated wires, steel-nickel coated wires, and piano wire-nickel coated wires. Considering cost and conductivity, glass-silver coated wires and silica-silver coated wires are preferred. As conductive non-metallic wires, carbon fibers and conductive fibers made by kneading conductive carbon into polyester or nylon are preferred. For the conductive wire 11, a Ni-based metal wire, similar to the nickel plating on the battery's outer surface, is preferred due to the contact stability between the conductive wire and the battery during device use. Furthermore, some additives or other metals may be included to enhance conductivity.

[0042] As mentioned above, the conductive wire 11 is usually formed by stretching it along its length, and it is possible to control the variation in its diameter (thickness) to an extremely small extent. From this viewpoint, the thickness (d) of the conductive wire 11 is preferably 10 ≤ d ≤ 200 μm, and more preferably 20 ≤ d ≤ 100 μm. As mentioned above, the thickness (d) is a value measured in the cross-section in the thickness direction of the conductive wire 11. A thickness (d) of 10 μm or more improves the handling of the conductive wire 11 and allows for more reliable arrangement of the conductive wire 11 in a desired single layer in the planar direction. The thickness (d) of the conductive wire 11 is preferably 20 μm or more, and more preferably 30 μm or more. On the other hand, a thickness (d) of 50 μm or less of the conductive wire 11 reduces the total thickness of the pressure-sensitive conductive film 7, thereby improving its applicability to coin-type batteries. Coin-type batteries have size specifications (thickness, diameter) to accommodate the devices they are used in. From the viewpoint of ensuring battery capacity while keeping the size within the tolerance of the specifications, a thickness (d) of 50 μm or less of the conductive wire 11 is more preferably, and more preferably 30 μm or less. The above description of the conductive wire 11 is also preferably applicable to embodiments 2 to 4 described later.

[0043] Furthermore, the variation in the diameter (thickness) of individual conductive wires 11 along the wire length is also extremely small. As a result, the variation in the thickness (d) of the conductive wires 11 along the wire length is also extremely small. From this viewpoint, it is preferable that the ratio of the minimum diameter to the maximum diameter (minimum diameter / maximum diameter) of individual conductive wires 11 along the wire length be 0.85 or more, and more preferably 0.90 or more. These maximum and minimum diameters can be measured by the same method as the thickness (d).

[0044] Regarding an anisotropic pressure-sensitive conductive film, which is a more preferred form of the pressure-sensitive conductive film using the conductive wire 11 described above, an applicable form to the present invention will be described here. In an anisotropic pressure-sensitive conductive film, an electrical circuit is not usually formed that crosses the plane direction of the pressure-sensitive conductive film, and the pressurized portion conducts in the direction of film thickness. However, in the present invention, for example, in the cases of arrangements 5 and 6 of the pressure-sensitive conductive film described above, as can be understood from their forms, it is sufficient that only the portion placed 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 concrete image of such a pressure-sensitive conductive film is that, when a coin-type battery is viewed from above, an anisotropic conductive portion exists in a donut shape with an area equivalent 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, excluding arrangements that intentionally overlap, such as a grid, may have anisotropic conductivity. Anisotropic conductivity means that conductive wires do not come into contact with each other in the planar direction, both under no load and under load, and that no electrical circuits are formed in the planar 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 prone to slippage, making it possible to reduce the distance between wires. When the conductive wires 11 are arranged regularly as shown in Figures 11(A) to (C) and (E) to (H), the spacing between adjacent conductive wires 11, 11 is preferably at least twice the wire width, and more preferably at least 2.5 times, as the shortest distance between the centers of the wire widths of each conductive wire 11. This ensures that even if the shape of the wire deforms due to pressure, it will not come into contact with the adjacent wire, thus ensuring anisotropy.

[0045] The following describes the method for measuring the resistance change of a pressure-sensitive conductive film due to applied pressure.

[0046] The resistance change of a pressure-sensitive conductive film due to applied pressure can be measured, for example, by attaching the film to a metal plate and applying terminals from above using either a DC or AC method. With the DC method, stable values ​​cannot be obtained due to the influence of heat generation depending on the measurement time, so the AC method is preferable. Furthermore, to reliably confirm the influence of the contact surface with the coin-type battery, the AC method (1 kHz) can be used with the pressure-sensitive conductive film placed on the coin-type battery. Z It is preferable to measure at the following locations. It is preferable to perform measurements at several locations. For example, a total of three locations: the center of the film and two locations near the outermost edge, preferably a total of five or more locations including two additional locations between the center and the outermost edge of the film. Measurements may be taken at other locations, but measuring at regular intervals, for example, 1 mm intervals, allows for confirmation of the uniformity of the film. To confirm anisotropic conductivity, measure the positive electrode case or sealing plate near the crimped portion. If there is no anisotropy, the resistance value will be lower than that of the battery alone. The applied pressure should be 0.1 to 10 N, preferably 0.3 to 7 N, and more preferably 0.5 to 5 N.

[0047] The resistance of a battery with a pressure-sensitive conductive film, measured using the measurement method described above, is preferably 500Ω or more, more preferably 1000Ω or more, under near-no-load conditions (e.g., 0.01N). Under pressures above the threshold, it is preferably 50Ω or less, more preferably 30Ω or less, and even more preferably 10Ω or less. Alternatively, the resistance of a battery without a pressure-sensitive conductive film can be measured beforehand, and this resistance can be subtracted from the resistance of a battery with a pressure-sensitive conductive film to evaluate the resistance of the pressure-sensitive conductive film. The resistance value based on this difference is preferably 10Ω or less, more preferably 5Ω or less, and even more preferably 2Ω or less, at or above the threshold pressure. The resistance of a typical coin-type battery varies depending on its size, but is usually around 3Ω to 40Ω.

[0048] --First elastomer layer 9-- The first elastomer layer 9 is a layer that holds the conductive wire 11 and also provides self-healing properties. Various elastomers such as silicone-based, acrylic-based, and urethane-based elastomers can be used for the first elastomer layer 9. Furthermore, 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 higher, more preferably 0.5 MPa or higher, and even more preferably 1.0 MPa or higher. By setting the 100% modulus of the elastomer portion constituting the first elastomer layer 9 to 0.1 MPa or higher, self-healing properties can be more reliably exhibited, and by increasing the 100% modulus, self-healing properties can be further enhanced. The 100% modulus of the elastomer portion constituting the first elastomer layer 9 is usually 10.0 MPa or lower, and it is practical to set it to 7.0 MPa or lower. The 100% modulus is the stress value at 100% elongation (2x elongation) of the 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 preferred range for the 100% modulus of the elastomer portion constituting the first elastomer layer 9 is 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 portion of the conductive wire 11 that protrudes from the elastomer surface of the first elastomer layer 9 is preferably half or less of the thickness (d) of the conductive wire 11 (1 / 2d or less), and more preferably less than half of the thickness (d) of the conductive wire 11 (preferably 4 / 9d or less). By setting the protrusion height in this manner, the conductive wire 11 can be more reliably held within the first elastomer layer 9, and its self-healing properties can be further enhanced. Furthermore, the height of the portion of the conductive wire 11 that protrudes from the elastomer surface of the first elastomer layer 9 is preferably 1 / 20d or more, and more preferably 1 / 10d or more. This ensures a higher level of responsiveness when in contact with an external terminal. Moreover, it is preferable that the protrusion height of the conductive wire 11 is 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 × 10⁻⁶. 8 It is greater than or equal to Ω·cm, and more preferably 1 × 10⁻⁶10 It is greater than or equal to Ω·cm.

[0051] The thickness of the elastomer portion of the first elastomer layer 9 can be appropriately set considering the thickness (d) of the conductive wire 11, self-healing 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 later.

[0052] --Second elastomer layer 10-- The second elastomer layer 10 is a layer that ensures electrical insulation until it is subjected to a certain pressure. It also works in conjunction with the first elastomer layer to achieve self-healing properties. The second elastomer layer 10 preferably has a tensile strength of 0.05 MPa or more. By setting the tensile strength of the second elastomer layer 10 to 0.05 MPa or more, the second elastomer layer 10 that has been torn by the conductive wire 11 can be more reliably restored when the pressurized state is released. Alternatively, the tensile strength of the second elastomer layer 10 is preferably 8.0 MPa or less. By setting the tensile strength to 8.0 MPa or less, the second elastomer layer 10 can be more reliably penetrated by the conductive wire 11 when pressurized. Tensile strength is defined as the maximum tensile force recorded when the 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 testing.

[0053] The second elastomer layer 10 is required to have electrical insulation properties, and its volume resistivity is preferably 1 × 10⁻⁶. 8 It is greater than or equal to Ω·cm, and more preferably 1 × 10⁻⁶ 10 It is greater than or equal to Ω·cm.

[0054] The thickness of the second elastomer layer 10 can be appropriately set considering the thickness of the conductive wire, insulation 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 later.

[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 set as appropriate. From the viewpoint of achieving a higher level of both low-resistance, rapid pressure-sensitive conductivity and self-healing properties, it is preferable that the thickness of the elastomer portion of the first elastomer layer is greater than the thickness of the second elastomer layer.

[0056] The pressure-sensitive conductive film used in the present invention can be in a form in which the second elastomer layer is thinned, which is a great advantage in improving the performance of the coin-type battery of the present invention and reducing the constraints on the dimensions of the battery. The technical effects obtained by forming the second elastomer layer thinly 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-type battery using terminals (electrodes) of a fixed area on a planar surface while the battery is in a dry state (without liquid), and the battery voltage is monitored using a DC method. In the case of a button cell battery alone (without QTCC), the battery voltage (closed-circuit voltage) rises sharply at a load of 1 N / sq cm after the terminals (electrodes) make contact with the battery, and then remains constant thereafter. On the other hand, in a button cell battery with QTCC placed on the surface, the battery voltage (closed-circuit voltage) gradually increases in the displacement range of 0.1 to 0.2 mm from around a load of 25 N / sq cm, and at a load of 100 N / sq cm, it reaches a battery voltage value equivalent to that of a button cell battery alone (without QTCC), and then remains constant thereafter. From this, it can be seen that in QTCC, the resistance of the film itself changes as the film thickness decreases by 0.1 to 0.2 mm within the load range of 25 N / sq cm to 100 N / sq cm. In actual equipment terminals, the tips are sometimes pointed, and if a small area is pressed hard, the film thickness in that area becomes locally thinner, causing conductivity and resulting in an anisotropic conductive state. In such an anisotropic conductive state, current concentrates in the localized conductive area, and Joule heating can cause deterioration of the resin portion that makes up the film. In contrast, with the pressure-sensitive conductive film used in the present invention, the second elastomer layer can be designed to be an ultrathin film, and as a result, an electrical circuit consisting of "external terminal - conductive wire - battery terminal" can be instantaneously formed by pressurization. Moreover, it is possible to suppress the change in resistance due to load to a level where it hardly occurs. Furthermore, since the pressure-sensitive conductive film used in this invention does not cause extreme current concentration like QTCC, it is possible to fully utilize battery performance even when applied to various devices. In addition, the pressure-sensitive conductive film of this invention has fewer thickness constraints, and its thickness can be made into a desired thin film. Therefore, it is possible to prevent limitations on battery capacity and dimensional effects when attaching it to 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., to confirm the quality of the coating during layer formation. If the film surface is illuminated with a black light emitting long-wavelength ultraviolet light (wavelength 315-400 nm, UVA, Ultraviolet A) to confirm the quality of the coating, it becomes easy to check the coating condition of the film, which cannot be seen with normal light.

[0059] Regarding the materials for the insulating coating 8 described above, elastomer materials can be used for the constituent materials of the insulating coating 8, 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 can be used. In addition, pigments and dyes may be included in the insulating coating material to check the coating condition of the insulating coating 8. It is preferable to allow the insulating coating surface to be illuminated with a black light emitting long-wavelength ultraviolet light (wavelength 315-400 nm, UVA, Ultraviolet A) to check the quality of the coating, as this makes it easier to check the coating condition of the insulating coating.

[0060] --Manufacturing of pressure-sensitive conductive film 12-- First, the second elastomer 10 can be formed by a coating method. For example, a liquid containing a second elastomer, obtained by dissolving or dispersing a second elastomer in a solvent, is applied to a release sheet and dried to form a second elastomer layer 10. This second elastomer layer 10 can also be formed by applying a solution obtained by dissolving an ultraviolet-curable or thermosetting second elastomer precursor in a solvent as needed to a release sheet, drying it as needed, and then curing it with ultraviolet light or heat (addition reaction, condensation reaction, etc.). If the second elastomer or its precursor is a low-viscosity liquid, dissolution or dispersion in a solvent and drying 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. Placement methods include mounting using a mounter used for substrate mounting, dropping or placing wires onto a mask with a pre-formed pattern of holes, and pressing the surface of the second elastomer layer 10 of the battery onto pre-arranged conductive wires 11. In the case of a grid, placement is simply done. Alternatively, it is possible to draw a wiring pattern directly on the substrate using a wiring pattern, or to use a multi-wire system with this wiring pattern as the basic process. Next, for example, a first elastomer-containing liquid, obtained by dissolving or dispersing the 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 above-mentioned first elastomer-containing liquid may also be a solution obtained by dissolving an ultraviolet-curable or thermosetting 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 by ultraviolet light or heat to obtain the first elastomer layer 9 on the second elastomer layer 10. Furthermore, if the first elastomer or its precursor itself is a low-viscosity liquid, dissolution or dispersion in a solvent and drying are not required. In this case, the coating film formed on the second elastomer layer 10 can be cured by 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 obtained in this way can be cut into a shape that can be attached to the conductive substrate 13 of the coin-type battery (for example, the top plate portion 6a of the sealing plate), peeled off 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-type battery equipped with the pressure-sensitive conductive film 12 can be obtained.

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

[0063] From the viewpoint of shortening the layer formation time, it is preferable to use UV-curable or thermosetting elastomer precursors 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 [Form 2]- Figure 12 shows another example (Embodiment 2) of the pressure-sensitive conductive film 12 used in the present invention. In Embodiment 2, before pressurization 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 to the conductive substrate 13. While the second elastomer layer 10 ensures insulation, when a certain amount of pressure is applied perpendicularly toward the conductive substrate 13 by an external terminal, the second elastomer layer 10 directly above the conductive wire 11 is punctured by the external terminal, achieving good conductivity. Also, similar to Embodiment 1, it exhibits self-recovery properties when the pressurized state is released. The pressure-sensitive conductive film of form 2 can be formed appropriately in accordance with the method for forming each layer of the pressure-sensitive conductive film of form 1.

[0066] -Pressure-sensitive conductive film [Form 3]- Figure 13 shows yet another example (Embodiment 3) of the pressure-sensitive conductive film 12 used in the present invention. In Embodiment 3, a second elastomer layer 10 is provided on both sides of the first elastomer layer 9 that holds the conductive wire 11, and these two second elastomer layers 10 are in contact with at least some of both ends of the conductive wire. While the second elastomer layer 10 ensures an insulating state, when pressure is applied above a certain level in a perpendicular direction toward the conductive substrate 13 side by an external terminal, the second elastomer layer 10 directly above the conductive wire 11 is pierced by the external terminal, and the second elastomer layer on the conductive substrate 13 side is also pierced by the conductive wire 11, thereby achieving a good conductive state. Furthermore, similar to Embodiment 1, it exhibits self-recovery properties when the pressurized state is released. The pressure-sensitive conductive film of form 3 can be formed appropriately in accordance with the method for forming each layer of the pressure-sensitive conductive film of form 1.

[0067] -Pressure-sensitive conductive film [Form 4]- Figure 14 shows yet another example (Embodiment 4) of the pressure-sensitive conductive film 12 used in the present invention. Embodiment 4 is a pressure-sensitive conductive film in which the surface of the conductive wire 11 protruding from the first elastomer layer 9 in Embodiment 1 is covered with a second elastomer layer 10. With this configuration, insulation can be more reliably ensured when not under a predetermined pressure. Embodiment 4 is an embodiment in which the conductive wire 11 is covered with the constituent material of the second elastomer layer in Embodiment 1. Here, in the present invention, the "first elastomer layer" and the "second elastomer layer" are not distinguished by differences in material, but rather by differences in function in the manifestation of the effects of the present invention. Therefore, in Embodiment 4, the conductive wire 11 is covered with the constituent material of the second elastomer layer 10, but only a part of the covering constitutes the second elastomer layer 10. That is, of the covering layer, the portion that protrudes from the elastomer portion of the first elastomer layer 9 in the thickness direction of the pressure-sensitive conductive film 12 (in Figure 14, the covering layer that covers the portion of the conductive wire 11 that protrudes from the elastomer portion of the first elastomer layer 9) is the second elastomer layer 10, and the other layered portion (the covering layer portion covered by the first elastomer) constitutes the first elastomer layer 9. Therefore, in Figure 14, the second elastomer layer 10 placed on the first elastomer layer 9 exists in a state where it is divided in the planar direction by the elastomer portion of the first elastomer layer. 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] Although the above describes the form of the pressure-sensitive conductive film, the pressure-sensitive conductive film used in the present invention is not limited to the above forms 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-type battery of the present invention.

[0069] The coin-type battery of the present invention has a pressure-sensitive conductive film with the above-described specific structure and exhibits self-healing properties, so even if it is removed after being installed in a device, it can effectively suppress damage to the body caused by accidental ingestion of the coin-type battery. Furthermore, the configuration in which the conductive wire is arranged in a single layer within the first elastomer layer further suppresses variations in pressure response and current-carrying characteristics, enabling the expression of excellent electrical properties. In other words, under pressure above a certain level, a low-resistance current-carrying state can be quickly achieved, and extreme current concentration is less likely to occur. [Industrial applicability]

[0070] The coin-type battery according to the present invention can be used in a variety of devices and has great industrial value. [Explanation of Symbols]

[0071] 1 Battery case 1a Bottom plate part 1b Side 2 Positive electrode 3 negative electrode 4 Separators 5 Gasket 6 Sealing plate 6a Top panel 6b Peripheral area 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 for coin-type batteries)

Claims

1. A battery case having a base plate and side portions rising from the periphery of the base plate, A sealing plate having a top plate portion and a peripheral edge portion extending inward from the top plate portion to the side portion, A gasket compressed and interposed between the side portion and the peripheral portion, The power generation element is sealed by the battery case, the sealing plate, and the gasket, A pressure-sensitive conductive film disposed on at least one outer surface of the battery case and the sealing plate, It has, The pressure-sensitive conductive film comprises a first elastomer layer that holds 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. A coin-type battery in which the thickness of the conductive wire is greater than or equal to the thickness of the elastomer portion of the first elastomer layer, and the conductive wire is arranged in a single layer in the planar direction of the first elastomer layer.

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

4. The coin-type battery according to claim 1 or 2, wherein the conductive wire in contact with the second elastomer layer protrudes from the elastomer portion of the first elastomer layer toward the opposite side of the second elastomer layer.

5. The coin-type battery according to claim 1, wherein the conductive wires partially overlap and are formed in a grid pattern.

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