Manganese dry cell

Abstract

The present disclosure provides a manganese dry cell in which an explosion-proof mechanism operates reliably even in a high-temperature environment. Disclosed is a manganese dry cell (100) comprising: a hollow cylindrical positive electrode mixture (1); a negative electrode can (4); a separator (3) disposed between the positive electrode mixture (1) and the negative electrode can (4); a positive electrode current collector (2) inserted into a hollow part of the positive electrode mixture (1); a positive electrode terminal plate electrically connected to the positive electrode current collector (2); a sealing body (5) insulating the positive electrode terminal plate and the negative electrode can (4) from one another; and an electrolyte. The sealing body (5) has: a tubular part that holds the positive electrode current collector (2); an outer circumferential part in contact with the inner wall of the negative electrode can (4); and a connecting part connecting the tubular part with the outer circumferential part. The positive electrode terminal plate has an annular part in contact with the connecting part. In a part of the circumferential direction, the connecting part has a first recess. A first space is formed between the annular part and the connecting part by the first recess, and a second space is formed between an upper surface perpendicular to the axis of the tubular part and the positive electrode terminal plate in at least a part of the circumferential direction.

Description

Manganese dry battery

[0001] The present invention relates to a manganese dry battery.

[0002] Manganese dry batteries have been widely used as power sources for electronic devices such as portable devices and information devices. A manganese dry battery generally includes a hollow cylindrical positive electrode mixture, a negative electrode can, a separator disposed between the positive electrode mixture and the negative electrode can, an electrolyte, and a positive electrode current collector inserted into the hollow portion of the positive electrode mixture. The opening of the battery can is closed by a positive electrode terminal plate electrically connected to the positive electrode current collector. The positive electrode terminal plate and the negative electrode can are sealed by a sealing member, with both being insulated from each other. The positive electrode mixture contains manganese dioxide.

[0003] Patent Document 1 discloses a manganese dry battery comprising: a cylindrical portion that holds a carbon rod; an outer cylindrical portion that is in close contact with the inner wall of a zinc can; and a sealing body having a connecting portion that connects the two; and a positive electrode terminal plate that fits onto the top of the carbon rod and has an outer peripheral portion bent into a U-shape in cross section, with the bent portion contacting the inner wall of the outer cylindrical portion on the connecting portion of the sealing body, the outer peripheral edge of the positive electrode terminal plate bent outward, and the bent portion fits into a groove provided in the inner wall of the outer cylindrical portion of the sealing body, and the outer cylindrical portion of the sealing body has an inclined portion that is inclined so that the outer periphery is thinner above the groove, and the open end of the zinc can is bent toward this inclined portion.

[0004] Japanese Patent Application Laid-Open No. 2001-6634

[0005] The manganese dry battery of Patent Document 1 has an annular thin-walled portion at the connecting portion of the sealing body to provide explosion protection (see Figure 5). When the internal pressure of the battery exceeds a predetermined threshold, the sealing body ruptures at the thin-walled portion, allowing gas to be released outside the battery.

[0006] Low-density polyethylene (LDPE), for example, is used as a sealing body material because it is inexpensive and has excellent fluidity during molding. However, sealing body materials such as LDPE often have a relatively large shrinkage rate during molding. Therefore, when a thin-walled portion is provided in the sealing body, the thickness of the thin-walled portion tends to vary greatly. As a result, the operating pressure of the explosion-proof mechanism may vary.

[0007] Furthermore, the material of the sealing body has a low melting point; for example, the heat resistance temperature of LDPE is about 70° C., and it softens at a relatively low temperature. Therefore, if an abnormality occurs, such as a short circuit, which causes an increase in the internal pressure of the battery as well as an increase in the internal temperature of the battery, the sealing body material may stretch without breaking even when pressure is applied to the thin-walled portion, and the explosion-proof mechanism may not function properly.

[0008] One aspect of the present invention is a battery comprising: a hollow cylindrical positive electrode mixture containing manganese dioxide; an anode can containing zinc; a separator disposed between the positive electrode mixture and the anode can; a positive electrode current collector inserted into the hollow portion of the positive electrode mixture; a positive electrode terminal plate electrically connected to the positive electrode current collector; a sealing body for insulating between the positive electrode terminal plate and the anode can; and an electrolyte, wherein the sealing body has a cylindrical portion for holding the positive electrode current collector; an outer peripheral portion in contact with an inner wall of the anode can; and a connecting portion connecting the positive electrode terminal plate and the positive electrode terminal plate, the positive electrode terminal plate being in contact with the connecting portion and having an annular portion centered on the axis of the cylindrical portion, the connecting portion having a first recess in a partial region along the circumferential direction of the connecting portion, the first recess forming a first space between the annular portion and the connecting portion, and a second space being formed between an upper surface perpendicular to the axis of the cylindrical portion and the positive electrode terminal plate in at least a partial region along the circumferential direction of the cylindrical portion.

[0009] Another aspect of the present invention relates to a manganese dry battery including: a hollow cylindrical positive electrode mixture containing manganese dioxide; an anode can containing zinc; a separator disposed between the positive electrode mixture and the anode can; a positive electrode current collector inserted into the hollow portion of the positive electrode mixture; a positive electrode terminal plate electrically connected to the positive electrode current collector; a sealing body providing insulation between the positive electrode terminal plate and the anode can; and an electrolyte, wherein the sealing body has a cylindrical portion that holds the positive electrode current collector; an outer circumferential portion that contacts an inner wall of the anode can; and a connecting portion that connects the cylindrical portion to the outer circumferential portion, and the positive electrode terminal plate has an annular portion that contacts the connecting portion and is centered on the axis of the cylindrical portion, and a second recess in a partial region along the circumferential direction of the cylindrical portion, the second recess forming a second space between the upper surface of the cylindrical portion and the positive electrode terminal plate.

[0010] According to the present invention, it is possible to obtain a manganese dry battery whose explosion-proof mechanism operates reliably even in a high-temperature environment.

[0011] Fig. 2 is a partially cross-sectional front view of an example of a manganese dry battery according to an embodiment of the present disclosure. Fig. 3 is a schematic cross-sectional view enlarging the periphery of the opening of the battery can of the manganese dry battery shown in Fig. 1. Fig. 4 is a perspective cross-sectional view enlarging the upper part (the opening side of the battery can) of the manganese dry battery according to an embodiment of the present disclosure. Fig. 5 is a top view of a sealing body of the manganese dry battery according to an embodiment of the present disclosure, viewed from above. Fig. 6 is a schematic cross-sectional view enlarging the periphery of the opening of the battery can of a manganese dry battery with a conventional configuration.

[0012] Hereinafter, embodiments according to the present disclosure will be described using examples, but the present invention is not limited to the examples described below. In this specification, the expression "numeric value A to numerical value B" includes numerical value A and numerical value B, and can be read as "numerical value A or more and numerical value B or less." In the following description, when lower and upper limits are exemplified for numerical values ​​of specific physical properties or conditions, any of the exemplified lower limits can be arbitrarily combined with any of the exemplified upper limits, as long as the lower limit is not equal to or greater than the upper limit.

[0013] A manganese dry battery according to one embodiment of the present disclosure includes a positive electrode mixture, a negative electrode can, a separator, a positive electrode current collector, a positive electrode terminal plate electrically connected to the positive electrode current collector, a sealing member providing insulation between the positive electrode terminal plate and the negative electrode can, and an electrolyte. The positive electrode mixture includes manganese dioxide and is hollow cylindrical. The negative electrode can includes zinc. The separator is disposed between the positive electrode mixture and the negative electrode can. The positive electrode current collector is inserted into the hollow portion of the positive electrode mixture. The positive electrode mixture and the separator are impregnated with the electrolyte. The manganese dry battery may include other components (e.g., a sealing member, a terminal plate, etc.) as needed.

[0014] Here, the direction from the bottom of the negative electrode can toward the positive electrode terminal plate is defined as the upward direction of the manganese dry battery.

[0015] The sealing body has a cylindrical portion that holds the positive electrode current collector, an outer peripheral portion that contacts the inner wall of the negative electrode can, and a connecting portion that connects the cylindrical portion to the outer peripheral portion. The outer peripheral portion not only seals the gap between the positive electrode terminal plate and the negative electrode can, but also insulates the positive electrode terminal plate from the negative electrode can.

[0016] The positive electrode terminal plate has an annular portion that contacts the connecting portion of the sealing body and is centered on the axis of the cylindrical portion. However, the entire inner surface of the annular portion does not contact the connecting portion, and a gap (first space) may exist between the annular portion and the connecting portion in part of the inner surface of the annular portion.

[0017] In one embodiment, the coupling portion has a first recess in a circumferential region of the coupling portion, the first recess forming a first space between the annular portion and the coupling portion over a portion of the circumferential direction, and the first recess has a bottom surface extending to the tubular portion.

[0018] Furthermore, a second space may be formed between the upper surface of the cylindrical portion perpendicular to the axis of the cylindrical portion and the positive electrode terminal plate in at least a portion of the circumferential direction of the cylindrical portion. In this case, the second space may be disposed adjacent to at least a portion of the first space. For example, the second space may be disposed such that the circumferential angle at which the first space is formed overlaps with the circumferential angle at which the second space is formed in at least a portion of the angular range.

[0019] The first recess reduces the thickness of the connecting portion in a circumferential region. Furthermore, due to the presence of the first space, the connecting portion is lifted upward in the circumferential region where the connecting portion is thin, and the tubular portion connected to the connecting portion is therefore easily deformed by being lifted upward. As a result, when the pressure applied to the sealing body increases due to an increase in internal pressure, deformation of the connecting portion and the tubular portion is induced. When the internal pressure exceeds a certain threshold, the deformation of the connecting portion and the tubular portion causes the adhesion between the tubular portion and the positive electrode current collector to break, and gas is released through the broken portion. As a result, the sealing body functions as an explosion-proof valve that reliably operates even in high-temperature environments.

[0020] The upper surface of the cylindrical portion may have a second recess in a partial region along the circumferential direction of the cylindrical portion. The second recess may be provided along the outer periphery of the cylindrical portion. The second recess forms a second space. In this case, the cylindrical portion becomes more susceptible to deformation due to an increase in internal pressure, making it easier to exert an explosion-proof function and to control the valve operating pressure.

[0021] The second space present on the upper surface of the cylindrical portion provides a space that allows deformation such as lifting the cylindrical portion upward. As long as the second space is present, the first space is not necessarily required. However, it is preferable to have the first space and the second space in order to more easily induce upward deformation of the cylindrical portion and ensure activation of the explosion-proof mechanism. To increase the second space, a second recess may be formed to thin the axial thickness of the cylindrical portion in a portion of the circumferential direction, or the axial thickness of the cylindrical portion may be thinned so that the second space is formed around the entire circumference of the upper surface of the cylindrical portion.

[0022] The first space is preferably connected to the second space. In this case, the connecting portion deforms and bends upward as the internal pressure increases, which in turn induces upward deformation of the cylindrical portion. Therefore, the explosion-proof function is easily exerted by the increase in internal pressure, and the valve actuation pressure is easily controlled. The valve actuation pressure can be controlled to a desired value by adjusting, for example, the size or height of the first space and the second space (in other words, the depth of the first recess and the second recess), the circumferential angular range in which the first recess and the second recess are formed, and the like.

[0023] The first recess may be formed to occupy a predetermined angular range θ1 in the circumferential direction of the sealing body. The angular range θ1 may be, for example, in the range of 40° to 150°, and more preferably in the range of 90° to 150°.

[0024] The second recesses may be formed to occupy a predetermined angular range θ2 in the circumferential direction of the sealing body. The second recesses may be formed around the entire circumference of the sealing body (θ2=360°). The angular range θ2 may be, for example, in the range of 85° to 120°.

[0025] The first recess and the second recess may be arranged so that the angular range occupied by the first recess in the circumferential direction overlaps with the angular range occupied by the second recess in the circumferential direction, and the first recess and the second recess are adjacent to each other in the radial direction. Preferably, θ1 > θ2, and the entire second recess in the circumferential direction is covered by the first recess. In this case, the entire angular range occupied by the second recess in the circumferential direction is included in the angular range occupied by the first recess in the circumferential direction.

[0026] The angular ranges θ1 and θ2 may be such that θ1 is in the range of 40° to 150° and θ2 is in the range of 85° to 120°, and more preferably θ1 is in the range of 90° to 150° and θ2 is in the range of 85° to 120°.

[0027] When the sealing body is viewed from above (the side of the positive electrode terminal plate), a radial line connecting the center of the cylindrical portion (the position of the axis of the cylindrical portion) and the center of the first recess is defined as a first center line, and a radial line connecting the center of the cylindrical portion (the position of the axis of the cylindrical portion) and the center of the second recess is defined as a second center line. The center of the first recess is located at a position that bisects the angle range θ1. The center of the second recess is located at a position that bisects the angle range θ2. In other words, for example, when θ1 = 120°, the angle of the first recess with respect to the first center line is in the range of −60° to +60°. For example, when θ2 = 60°, the angle of the second recess with respect to the second center line is in the range of −30° to +30°. It is preferable that the first center line approximately coincides with the second center line. The angle between the first center line and the second center line may be, for example, 10° or less, or may be 5° or less.

[0028] When the sealing body is viewed from above (the side of the positive electrode terminal plate), the shape of the first recess is preferably symmetrical with respect to the first center line, and the shape of the second recess is preferably symmetrical with respect to the second center line.

[0029] A plurality of first recesses and a plurality of second recesses may be provided. In this case, it is sufficient that at least one of the plurality of first recesses or second recesses satisfies the relationship of θ1 or θ2 described above. However, in order to prevent a decrease in sealing strength, the number of first recesses and second recesses may be two or less, and one is preferred. If there is one first recess, the deformation force of the sealing body due to an increase in internal pressure is concentrated in one recess rather than being dispersed among multiple first recesses, making it easier to reliably operate the explosion-proof mechanism and to control the valve operating pressure.

[0030] The shape, depth, and radial width of the first and second recesses depend on the size of the battery and the valve actuation pressure, and are not particularly limited, but for example, in the case of an AAA manganese dry battery, the depth of the first recess may be 0.1 to 0.2 mm and the radial width may be 1.0 to 1.1 mm, and the depth of the second recess may be 0.1 to 0.4 mm and the radial width may be 1.0 to 1.2 mm.

[0031] The above-described structure of the positive electrode terminal plate and the sealing body enables a manganese dry battery with an explosion-proof function and with reliable valve operation even in a high-temperature environment. In the manganese dry battery of this embodiment, the material of the sealing body is not particularly limited, but may be low-density polyethylene (LDPE).

[0032] Conventional explosion-proof mechanisms include a thin-walled section formed by thinning a portion of the sealing body. In this configuration, when the internal pressure of the battery rises above a predetermined threshold, the thin-walled section ruptures due to stress caused by the increased internal pressure, allowing gas to escape. However, because LDPE has a relatively large shrinkage rate during molding, providing a thin-walled section in a sealing body made of LDPE can result in significant variations in the thickness of the thin-walled section, which can lead to variations in the valve actuation pressure when the thin-walled section ruptures. In addition, because LDPE has low heat resistance and tends to soften in high-temperature environments, stress applied to the thin-walled section can cause the LDPE to stretch without rupturing, resulting in insufficient valve actuation.

[0033] In contrast, the explosion-proof mechanism of the present embodiment utilizes the deformation of the sealing body, so the explosion-proof mechanism operates reliably even in high-temperature environments.In fact, in the manganese dry battery of the present embodiment, a sealing body material that is moderately easy to deform in high-temperature environments can be preferably used.

[0034] Preferred materials for the sealing body include LDPE, as well as polyolefin resins (excluding LDPE) such as polyethylene and polypropylene.

[0035] An example of an embodiment of the present disclosure will be specifically described below with reference to the drawings. The example described below may be modified based on the above description. Furthermore, the description of the example described below may be applied to the above embodiment.

[0036] Fig. 1 is a partially cross-sectional front view of a manganese dry battery (e.g., AAA type) of this embodiment. Fig. 2 is a schematic cross-sectional view enlarging the periphery of the opening of the battery can of the manganese dry battery shown in Fig. 1. Fig. 3 is a cross-sectional perspective view enlarging the upper part (the opening side of the battery can) of the manganese dry battery of this embodiment.

[0037] The manganese dry battery 100 shown in Figures 1 and 2 includes a positive electrode mixture 1, a positive electrode current collector 2, a separator 3, a negative electrode can 4, a sealing body (gasket) 5, a positive electrode terminal plate 11, and an electrolyte. The sealing body 5 and the positive electrode terminal plate 11 have the structures described above. Components other than the structures of the sealing body and the positive electrode terminal plate are not particularly limited, and materials other than those exemplified below may be used. For example, materials used in known manganese dry batteries may be used.

[0038] The negative electrode can 4 contains zinc and has a cylindrical shape with a bottom. The negative electrode can is formed, for example, from a metal containing zinc as a main component. The metal containing zinc as a main component may be a zinc alloy containing a trace amount (for example, about 10 to 1000 ppm) of indium or manganese. A cylindrical positive electrode mixture 1 is housed inside the negative electrode can 4.

[0039] For example, a mixture of powdered manganese dioxide, a powdered conductive agent such as acetylene black, and an electrolyte solution is used for the positive electrode mixture 1. The content of manganese dioxide in the positive electrode mixture 1 is preferably 40 to 60 mass %. The content of the conductive agent in the positive electrode mixture 1 is preferably 5 to 15 mass %.

[0040] A separator 3 is disposed between the positive electrode mixture 1 and the negative electrode can 4. The separator 3 may be, for example, an insulating porous sheet (e.g., kraft paper). Kraft paper coated with a glue material and dried may also be used. The glue material is prepared, for example, by dissolving cross-linked starch and a binder (e.g., polyvinyl acetate) in an alcohol-based solvent.

[0041] The separator 3 is disposed so that the surface coated with the adhesive faces the negative electrode can 4. The separator 3 contains an electrolyte. For example, an aqueous solution containing zinc chloride is used as the electrolyte. The electrolyte may be an aqueous solution in which zinc chloride and ammonium chloride are dissolved. The concentration of zinc chloride in the electrolyte may be in the range of 25 to 33 mass %.

[0042] A positive electrode current collector 2 is inserted into the hollow portion of the positive electrode mixture 1. The positive electrode current collector 2 is, for example, a porous carbon rod. The carbon rod has the size and shape used in manganese dry batteries. The carbon rod is manufactured by, for example, mixing a material containing a carbonaceous powder material and a binder, forming the mixed material into a rod, heating the resulting rod at a temperature at which the binder carbonizes, and then cutting the rod to a predetermined length. The density of the carbon rod varies depending on the molding conditions. Graphite (e.g., artificial graphite) can be used as the carbonaceous powder material. The carbonaceous powder material may contain graphite, carbon black, and / or coke. Examples of binders include pitch and tar.

[0043] A guard paper 9 is placed on top of the positive electrode mixture 1. The guard paper 9 has a circular shape with an opening, and the positive electrode current collector 2 is inserted into the opening of the guard paper 9.

[0044] The opening of the negative electrode can 4 is covered with a sealing member 5 and a positive electrode terminal plate 11. The positive electrode terminal plate 11 is made of, for example, a cap-shaped tin plate. Between the bottom of the positive electrode mixture 1 and the bottom of the negative electrode can 4, a bottom paper 13 is arranged to ensure insulation.

[0045] The sealing body 5 has a cylindrical portion 5a, an outer peripheral portion 5b, and a connecting portion 5c that connects the cylindrical portion 5a and the outer peripheral portion 5b. A cylindrical or rod-shaped positive electrode current collector 2 is inserted into the hollow portion of the cylindrical portion 5a. In this way, the cylindrical portion 5a holds the positive electrode current collector 2. The outer peripheral portion 5b contacts the inner wall of the negative electrode can 4.

[0046] The positive electrode terminal plate 11 has a protrusion 11a disposed in its center and a flat annular portion 11b disposed around the protrusion 11a. One end of the positive electrode current collector 2 is fitted into a recess formed inside the protrusion 11a, thereby electrically connecting the positive electrode current collector 2 and the positive electrode terminal plate 11. The annular portion 11b contacts the connecting portion 5c of the sealing body 5 at a portion of its inner surface.

[0047] The positive electrode terminal plate 11 has a rising portion 11c that extends from the annular portion 11b and rises upward, on the outer periphery side of the annular portion 11b. The upper end of the opening of the negative electrode can 4 is curled inward, and the tip of the upper end of the opening is crimped to the rising portion 11c via the outer periphery 5b of the sealing body 5, thereby sealing the space between the negative electrode can 4 and the positive electrode terminal plate 11. A groove 5x may be formed on the inner surface of the outer periphery 5b, and the tip of the upper end of the opening may be crimped to the rising portion 11c via the outer periphery 5b of the sealing body 5 with the end of the rising portion 11c fitted into the groove 5x.

[0048] The lower end portion, including the bottom portion, of the negative electrode can 4 is fitted into a cup-shaped negative electrode terminal 6, and the negative electrode can 4 and the negative electrode terminal 6 are electrically connected. The tubular portion of the cylindrical negative electrode can 4 and the side wall portion of the cup-shaped negative electrode terminal 6 are covered with an exterior label 10 made of a heat-shrinkable resin film as a base material. The upper end portion of the exterior label 10 covers the bent portion of the opening of the negative electrode can 4. The lower end portion of the exterior label 10 covers the underside of the negative electrode terminal 6.

[0049] As shown in FIG. 2 , the sealing body 5 has a recess (first recess) 51 in the connecting portion 5c. The recess 51 is formed along a portion of the circumferential direction, rather than along the entire circumference of the annular connecting portion 5c (see FIG. 3 ). As a result, the annular portion 11b does not contact the connecting portion 5c in the region where the recess 51 is located, and a space (first space) X is formed between the annular portion 11b of the positive electrode terminal plate 11 and the connecting portion 5c over a portion of the circumferential direction. The recess 51 reduces the thickness of the connecting portion 5c in the circumferential direction.

[0050] The sealing body 5 also has a recess (second recess) 52 on the upper surface of the tubular portion 5a of the sealing body 5. The recess 52 is formed along a portion of the circumference of the annular upper surface of the tubular portion 5a (see FIG. 3). As a result, the upper surface of the tubular portion 5a is separated from the positive electrode terminal plate 11 in the region where the recess 52 is arranged, and a space (second space) Y is formed between the upper surface of the tubular portion 5a and the protrusion 11a of the positive electrode terminal plate 11. The recess 52 makes the thickness of the tubular portion 5a thinner in a portion of the circumference. The thickness of the tubular portion 5a may be made thinner all around so that the space Y is formed all around the upper surface of the tubular portion 5a, as long as the sealing performance is not impaired.

[0051] The circumferential angular range in which the space X is formed and the circumferential angular range in which the space Y is formed may overlap in at least a part of the angular range. In the example of Fig. 2, a gap is formed between the outer peripheral side surface of the cylindrical portion 5a and the positive electrode terminal plate 11. In this case, the space X is in communication with the space Y through the gap.

[0052] Furthermore, due to the presence of the spaces X and Y, in some circumferential regions where the thickness of the connecting portion 5c is thin, the connecting portion 5c and the tubular portion 5a continuous with the connecting portion are easily deformed and lifted upward.

[0053] As the internal pressure of the battery increases, the upward pressure on the sealing body increases, and a force that tends to deform the sealing body is applied to the connecting portion and the tubular portion. In this case, in the manganese dry battery 100 of this embodiment, the presence of space X makes a thin region of the connecting portion 5c (thin region) more susceptible to upward deformation, and as a result, the tubular portion 5a adjacent to the thin region is also more susceptible to upward deformation. Furthermore, the presence of space Y makes the tubular portion 5a adjacent to the thin region thinner, so that the tubular portion 5a adjacent to the thin region is more susceptible to upward deformation force than other regions of the tubular portion 5a. As a result, when the internal pressure exceeds a predetermined threshold, the connecting portion 5c and the tubular portion 5a, which are thin in thickness, deform upward. As a result, their adhesion to the positive electrode current collector is broken, and gas is released through the broken portion. In this way, the explosion-proof mechanism is activated.

[0054] Furthermore, when space X and space Y are connected, the thin-walled region of connecting portion 5c of sealing body 5 is deformed so as to bend upward as the internal pressure increases, and this bending deformation tends to induce deformation in which tubular portion 5a is lifted upward. Therefore, the tubular portion is more likely to deform as the internal pressure increases, the explosion-proof mechanism operates reliably, and the valve operating pressure is easier to control.

[0055] 4 is a top view of the sealing body 5 shown in FIGS. 1 and 2 as viewed from above (the side not facing the positive electrode mixture layer). In FIG. 4, the sealing body 5 is in an unloaded state with no pressure being applied to the outer peripheral portion 5b. In the example of FIG. 4, the recesses 51 and 52 are each formed in a portion of the circumferential direction. The recess 52 may be formed so as to be adjacent to the recess 51 in the radial direction and to cover the recess 51 in the circumferential direction. In FIG. 4, the angular range θ1 occupied by the recess 51 in the circumferential direction is larger than the angular range θ2 occupied by the recess 52 in the circumferential direction (θ1 > θ2).

[0056] The angular range θ1 that the recess 51 occupies in the circumferential direction within the sealing body 5 may be, for example, in the range of 40° to 150°, and more preferably in the range of 90° to 150°.

[0057] The angular range θ2 that recess 52 occupies in the circumferential direction within sealing body 5 is not limited, and recess 52 may be formed around the entire circumference of the sealing body (θ2=360°) or may be formed on a portion of the circumference of the sealing body. When recess 52 is formed on a portion of the circumference of the sealing body, angular range θ2 may be, for example, in the range of 85° to 120°.

[0058] The shape, depth and radial width of the recesses 51 and 52 depend on the size of the battery and the valve operating pressure, and are not particularly limited.

[0059] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0060] (Technology 1) A battery comprising: a hollow cylindrical positive electrode mixture containing manganese dioxide; an anode can containing zinc; a separator arranged between the positive electrode mixture and the anode can; a positive electrode current collector inserted into a hollow portion of the positive electrode mixture; a positive electrode terminal plate electrically connected to the positive electrode current collector; a sealing body providing insulation between the positive electrode terminal plate and the anode can; and an electrolyte; wherein the sealing body has a tubular portion that holds the positive electrode current collector, an outer circumferential portion that contacts an inner wall of the anode can, and a connecting portion that connects the tubular portion and the outer circumferential portion; the positive electrode terminal plate has an annular portion that contacts the connecting portion and is centered on the axis of the tubular portion; and the connecting portion has a first recess in a partial region along the circumferential direction of the connecting portion, and the first recess forms a first space between the annular portion and the connecting portion; a second space is formed between an upper surface of the cylindrical portion perpendicular to the axis of the cylindrical portion and the positive electrode terminal plate in at least a partial region along the circumferential direction of the cylindrical portion.

[0061] (Technology 2) The manganese dry battery according to Technology 1, wherein the upper surface of the cylindrical portion has a second recess in a partial region along a circumferential direction of the cylindrical portion, and the second recess forms the second space.

[0062] (Technology 3) The manganese dry battery according to Technology 2, wherein a circumferential angle range θ1 in which the first recesses are formed is in the range of 40° to 150°, and a circumferential angle range θ2 in which the second recesses are formed is in the range of 85° to 120°.

[0063] (Technology 4) The manganese dry battery according to Technology 3, wherein a circumferential angle θ1 at which the first recess is formed is in the range of 90° to 150°.

[0064] (Technology 5) The manganese dry battery according to Technology 3 or 4, wherein θ1>θ2 is satisfied, and the second recess is covered by the first recess in the circumferential direction.

[0065] (Technology 6) The manganese dry battery according to any one of Technologies 1 to 5, wherein the first space is in communication with the second space.

[0066] (Technology 7) The manganese dry battery according to any one of Technologies 1 to 6, wherein the sealing body contains low-density polyethylene.

[0067] a cathode terminal plate electrically connected to the cathode current collector; a sealing body providing insulation between the positive electrode terminal plate and the negative electrode can; and an electrolyte; wherein the sealing body has a cylindrical portion that holds the positive electrode current collector, an outer circumferential portion that contacts an inner wall of the negative electrode can, and a connecting portion that connects the cylindrical portion and the outer circumferential portion; the positive electrode terminal plate has an annular portion that contacts the connecting portion and is centered on the axis of the cylindrical portion; and a second recess in a partial region along the circumferential direction of the cylindrical portion on an upper surface that is perpendicular to the axis of the cylindrical portion, and the second recess forms a second space between the upper surface of the cylindrical portion and the positive electrode terminal plate.

[0068] (Technology 9) The manganese dry battery according to Technology 8, wherein the connecting portion has a first recess in a partial region along the circumferential direction of the connecting portion, and the first recess forms a first space between the annular portion and the connecting portion.

[0069] (Technology 10) The manganese dry battery according to Technology 8 or 9, wherein the first space is in communication with the second space.

[0070] (Technology 11) The manganese dry battery according to any one of Technologies 8 to 10, wherein the sealing body contains low-density polyethylene.

[0071] EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0072] Example 1 (Manufacturing of Manganese Dry Battery) A sealing body 5 having the structure shown in FIG. 3 was fabricated. The sealing body 5 had a central through-hole with a diameter of 3.0 mm, a cylindrical portion 5a with a radial width of 1.2 mm, a connecting portion 5c with a radial width of 1.2 mm, and an outer peripheral portion 5b with a radial width of 0.85 mm, resulting in a disk-like shape with an overall diameter of 9.5 mm. The recess 51 (first recess) had a depth of 0.19 mm and a radial width of 1.01 mm, and was angled from -20° to +20° relative to the radial centerline (θ1 = 40°). The recess 52 (second recess) had a depth of 0.39 mm and a radial width of 1.2 mm (the same as the width of the cylindrical portion 5a), and was angled from -60° to +60° relative to the radial centerline (θ2 = 120°).

[0073] The sealing body was made of low density polyethylene (LDPE), and was molded using a predetermined mold to produce a sealing body having the above-mentioned shape, thereby obtaining sealing body C1.

[0074] The sealing body C1 was used to fabricate an AAA-size manganese dry battery having the configuration shown in Fig. 1, thereby obtaining a manganese dry battery A1 of Example 1. Eighty manganese dry batteries A1 were fabricated and subjected to the following evaluations.

[0075] (Evaluation 1) In an environment of 45°C, four manganese dry batteries A1 were connected in series, and one of the four manganese dry batteries was short-circuited with the positive and negative terminals connected in reverse, to conduct a short-circuit test. After that, the manganese dry battery with the reversed polarity was removed, and it was confirmed whether the explosion-proof mechanism had been activated.

[0076] The 40 manganese dry batteries were divided into 10 groups, and the above short circuit test was performed 10 times (N=10). The number m of manganese dry batteries whose explosion-proof mechanism did not work and whose sealing body exploded was calculated, and m / N was used as the evaluation target.

[0077] (Evaluation 2) A short circuit test similar to that in Evaluation 1 was carried out in an environment of 60°C, and the number m of manganese dry batteries whose sealing bodies had burst was determined and similarly evaluated.

[0078] Examples 2 to 4, Comparative Examples 1 and 2 In the production of the sealing body, the angle range in which the recesses 51 and 52 are formed was changed from that in Example 1.

[0079] In Example 2, recess 51 was formed at an angle of -45° to +45° relative to the radial center line (θ1 = 90°), and recess 52 was formed at an angle of -42.5° to +42.5° relative to the radial center line (θ2 = 85°), thereby obtaining sealing body C2. Using sealing body C2, a AAA manganese dry battery was produced in the same manner as in Example 1, thereby obtaining manganese dry battery A2 of Example 2. Manganese dry battery A2 was similarly evaluated.

[0080] In Example 3, recess 51 was provided at an angle of -75° to +75° relative to the radial center line (θ1 = 150°), and recess 52 was provided at an angle of -42.5° to +42.5° relative to the radial center line (θ2 = 85°), thereby obtaining sealing body C3. Using sealing body C3, a AAA manganese dry battery was produced in the same manner as in Example 1, thereby obtaining manganese dry battery A3 of Example 3. Manganese dry battery A3 was similarly evaluated.

[0081] In Example 4, no recess 51 was provided (θ1 = 0°), and recess 52 was provided at an angle ranging from −42.5° to +42.5° with respect to the center line in the radial direction (θ2 = 85°), thereby obtaining sealing body C4. Using sealing body C4, a AAA manganese dry battery was produced in the same manner as in Example 1, thereby obtaining manganese dry battery A4 of Example 4. Manganese dry battery A4 was similarly evaluated.

[0082] In Comparative Example 1, no recess 52 was provided (θ2 = 0°), and recess 51 was provided at an angle ranging from −20° to +20° with respect to the radial center line (θ1 = 40°), thereby obtaining sealing body C5. Using sealing body C5, an AAA manganese dry battery was produced in the same manner as in Example 1, thereby obtaining manganese dry battery B1 of Comparative Example 1. Manganese dry battery B1 was evaluated in the same manner.

[0083] In Comparative Example 2, sealing body C6 was obtained without providing recesses 51 and 52 (θ1 = 0°, θ2 = 0°). As shown in FIG. 5 , sealing body C6 had a thin-walled portion 5t with a thickness of 0.2 mm formed around the entire periphery of connecting portion 5c. Using sealing body C6, an AAA manganese dry battery was fabricated in the same manner as in Example 1, to obtain manganese dry battery B2 of Comparative Example 2. Manganese dry battery B2 was similarly evaluated.

[0084] The evaluation results are shown in Table 1. Manganese dry batteries A1 to A4 are manganese dry batteries according to the present invention, and manganese dry batteries B1 and B2 are comparative examples. Table 1 also shows the presence or absence of the first and second spaces in each battery, and the angle ranges θ1 and θ2 of the recesses, along with the evaluation results.

[0085]

[0086] As shown in Table 1, the explosion-proof mechanism of manganese dry batteries A1 to A4, which had the second space, was able to operate stably. In manganese dry batteries A1 to A3, by providing the first space by recess 51 (first recess) in addition to the second space, the explosion-proof mechanism was able to operate reliably in an environment of 45°C.

[0087] In the manganese dry batteries A2 to A3 in which the angle range θ1 in which the recess 51 is provided is set to the range of 90° to 150°, the explosion-proof mechanism was able to operate reliably even in an environment of 60°C.

[0088] The present invention can be used in manganese dry batteries.

[0089] REFERENCE SIGNS LIST 1 Positive electrode mixture 2 Positive electrode current collector 3 Separator 4 Negative electrode can 5 Sealing body (gasket) 5a Cylindrical portion 5b Outer periphery 5c Connecting portion 5x Groove 51, 52 Recessed portion 6 Negative electrode terminal 9 Flange paper 10 Outer packaging label 11 Positive electrode terminal 11a Convex portion 11b Annular portion 11c Raised portion 13 Bottom paper 100 Manganese dry battery

Claims

1. A manganese dry battery comprising: a hollow cylindrical positive electrode mixture containing manganese dioxide; a negative electrode can containing zinc; a separator disposed between the positive electrode mixture and the negative electrode can; a positive electrode current collector inserted into the hollow portion of the positive electrode mixture; a positive electrode terminal plate electrically connected to the positive electrode current collector; a sealing body insulating between the positive electrode terminal plate and the negative electrode can; and an electrolytic solution, wherein the sealing body has a cylindrical portion holding the positive electrode current collector, an outer peripheral portion contacting the inner wall of the negative electrode can, and a connecting portion connecting the cylindrical portion and the outer peripheral portion, the positive electrode terminal plate contacts the connecting portion and has an annular portion centered on the axis of the cylindrical portion, in a partial region along the circumferential direction of the connecting portion, the connecting portion has a first recess, and a first space is formed between the annular portion and the connecting portion by the first recess, and in at least a partial region along the circumferential direction of the cylindrical portion, a second space is formed between the upper surface perpendicular to the axis of the cylindrical portion and the positive electrode terminal plate.

2. The manganese dry battery according to claim 1, wherein in a partial region along the circumferential direction of the cylindrical portion, the upper surface of the cylindrical portion has a second recess, and the second recess forms the second space.

3. The manganese dry battery according to claim 2, wherein the circumferential angular range θ1 in which the first recess is formed is in the range of 40° to 150°, and the circumferential angular range θ2 in which the second recess is formed is in the range of 85° to 120°.

4. The manganese dry battery according to claim 3, wherein the circumferential angle θ1 in which the first recess is formed is in the range of 90° to 150°.

5. The manganese dry battery according to claim 3 or 4, satisfying θ1 > θ2, and in the circumferential direction, the second recess is covered by the first recess.

6. The manganese dry battery according to any one of claims 1 to 4, wherein the first space communicates with the second space.

7. The manganese dry battery according to any one of claims 1 to 4, wherein the sealing body contains low-density polyethylene.

8. A manganese dry battery comprising: a hollow cylindrical positive electrode mixture containing manganese dioxide; a negative electrode can containing zinc; a separator disposed between the positive electrode mixture and the negative electrode can; a positive electrode current collector inserted into the hollow portion of the positive electrode mixture; a positive electrode terminal plate electrically connected to the positive electrode current collector; a sealing body insulating between the positive electrode terminal plate and the negative electrode can; and an electrolytic solution, wherein the sealing body has a cylindrical portion for holding the positive electrode current collector, an outer peripheral portion contacting the inner wall of the negative electrode can, and a connecting portion connecting the cylindrical portion and the outer peripheral portion, the positive electrode terminal plate contacts the connecting portion and has an annular portion centered on the axis of the cylindrical portion, and in a partial region along the circumferential direction of the cylindrical portion, the upper surface perpendicular to the axis of the cylindrical portion has a second recess, and the second recess forms a second space between the upper surface of the cylindrical portion and the positive electrode terminal plate.

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