Alkaline cell

Abstract

To provide an alkaline cell in which a negative electrode mixture is less likely to leak.SOLUTION: An alkaline cell 1 includes: a bottomed cylindrical positive electrode can 2 having a positive electrode terminal disposed at a bottom surface; a cylindrical positive electrode mixture 3 provided inside the positive electrode can 2 and disposed coaxially with the positive electrode can 2; a cylindrical separator 7 provided on an inner peripheral side of the positive electrode mixture 3; a gelling negative electrode mixture 5 filled on the inner peripheral side of the separator 7; a current collector rod 6 inserted into the negative electrode mixture 5; a gasket 14 that supports the current collector rod 6 and closes an opening of the positive electrode can 2; a negative electrode terminal plate 12 that is disposed in an opening 18 of the positive electrode terminal 2 and disposed on an opposite side to the separator 7 across the gasket 14. The separator 7 has a certain region from an end on the negative electrode terminal plate 12 side to the positive electrode terminal side of the separator, as a contact region 30 that is in contact with the gasket 14. The contact region 30 curves inward with an end folded back towards the negative electrode mixture 5.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to alkaline batteries.

Background Art

[0002] An alkaline battery includes a bottomed cylindrical positive electrode can. Inside the positive electrode can, a separator formed in a cylindrical shape coaxial with the positive electrode can is provided. Inside the positive electrode can, a positive electrode mixture is provided outside the separator, and a gel-like negative electrode mixture is provided inside the separator. The alkaline battery includes a gasket that closes the opening of the positive electrode can.

[0003] In an alkaline battery, if the negative electrode mixture leaks outside the separator, it will short-circuit. Therefore, the end of the separator is brought into contact with the gasket to prevent the negative electrode mixture from leaking outside the separator between the separator and the gasket (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, for example, when the alkaline battery drops with the gasket side facing down and collides with the floor, the negative electrode mixture that has flowed to the gasket side may leak outside the separator between the separator and the gasket.

[0006] The disclosed technology aims to provide an alkaline battery in which the negative electrode mixture is less likely to leak.

Means for Solving the Problems

[0007] An alkaline battery according to one aspect of the present disclosure includes a positive electrode can having a bottomed cylindrical shape with a positive electrode terminal formed on the bottom surface, a cylindrical positive electrode mixture provided inside the positive electrode can and arranged coaxially with the positive electrode can, a cylindrical separator provided on the inner peripheral side of the positive electrode mixture, a gel-like negative electrode mixture filled on the inner peripheral side of the separator, a current collector rod inserted into the negative electrode mixture, a gasket that supports the current collector rod and closes the opening of the positive electrode can, and a negative electrode terminal plate provided at the opening of the positive electrode can on the opposite side of the separator with the gasket interposed therebetween. The separator has a contact region where a certain region from the end on the negative electrode terminal plate side to the positive electrode terminal side contacts the gasket. The contact region is curved inward and the end is folded back so as to face the negative electrode mixture side.

Advantages of the Invention

[0008] According to one aspect of the alkaline battery disclosed in the present application, an alkaline battery in which the negative electrode mixture is less likely to leak can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

[0010] Hereinafter, embodiments of the alkaline battery disclosed in the present application will be described in detail with reference to the drawings. Note that the battery disclosed in the present application is not limited by the following embodiments.

[0011] (Embodiment 1) <Schematic Configuration of Alkaline Battery> FIG. 1 is a cross-sectional view of the alkaline battery of Embodiment 1. The alkaline battery 1 of Embodiment 1 includes a positive electrode can 2, a positive electrode mixture 3, a negative electrode mixture 5, a current collector rod 6, a separator 7, a gasket 14, and a negative electrode terminal plate 12.

[0012] The positive electrode can 2 is formed of a conductor exemplified by a metal. The positive electrode can 2 is formed in a bottomed cylindrical shape and includes a side surface 15 and a bottom surface 16. The side surface 15 is formed in a cylindrical shape. The bottom surface 16 is formed integrally with the side surface 15 so as to close one end side of the side surface 15. A positive electrode terminal 17 is formed at the center of the bottom surface 16. The positive electrode terminal 17 is formed so as to protrude from the inside to the outside of the positive electrode can 2. The other end side of the positive electrode can 2 is an opening 18.

[0013] The positive electrode mixture 3 contains manganese dioxide MnO2, graphite C, an aqueous potassium hydroxide solution, and a binder. The binder contains, for example, a polymer compound and adheres powders formed of manganese dioxide MnO2 and graphite C to each other to form a solid. The positive electrode mixture 3 is formed in a cylindrical shape. The positive electrode mixture 3 is disposed inside the positive electrode can 2 such that the outer surface faces the inner peripheral surface of the side surface 15 of the positive electrode can 2. The positive electrode mixture 3 is in close contact with the positive electrode can 2 so that manganese dioxide MnO2 and graphite C are electrically connected to the positive electrode can 2.

[0014] The negative electrode mixture 5 contains zinc powder, an aqueous potassium hydroxide solution, and a gelling agent, and is in a gel form. The negative electrode mixture 5 is disposed inside the positive electrode mixture 3. Note that the zinc powder contained in the negative electrode active material may be replaced with zinc alloy powder formed from a zinc alloy containing zinc.

[0015] The current collector rod 6 is formed of a conductor and is in a rod shape. The current collector rod 6 is inserted into the negative electrode mixture 5 from the opening 18 side along the central axis of the positive electrode can 2.

[0016] The separator 7 is formed of an insulator exemplified by vinylon, pulp, or the like. The separator 7 is formed in a bottomed cylindrical shape and includes a side surface 21 and a bottom surface 22. The side surface 21 is formed in a cylindrical shape. The bottom surface 22 closes one end side of the side surface 21.

[0017] The separator 7 is disposed inside the positive electrode can 2 such that the cylindrical side surface 21 is coaxial with the positive electrode can 2. Further, the bottom surface 22 of the separator 7 is in contact with the bottom surface 16 of the positive electrode can 2. The side surface 21 of the separator 7 is provided between the positive electrode mixture 3 and the negative electrode mixture 5. That is, inside the positive electrode can 2, the positive electrode mixture 3 is provided outside the separator 7, and the negative electrode mixture 5 is provided inside the separator 7. The negative electrode mixture 5 is insulated from the positive electrode mixture 3 and the positive electrode can 2 by the separator 7.

[0018] A contact region 30 is formed in a certain region on the positive electrode terminal side from the end portion on the negative electrode terminal plate 12 side of the cylindrical side surface 15 of the separator 7, where the contact region 30 contacts the gasket 14. FIG. 2 is an enlarged partial cross-sectional view of the portion A shown in FIG. 1. As shown in FIG. 2, the contact region 30 contacts the gasket 14 and is curved inward. Further, the end portion of the side surface 15 is folded back so as to face the negative electrode mixture 5 side.

[0019] An electrolytic solution is injected into the positive electrode can 2. The electrolytic solution is formed from an aqueous solution containing potassium hydroxide KOH. The electrolytic solution penetrates into the positive electrode mixture 3, the negative electrode mixture 5, and the separator 7.

[0020] The gasket 14 is formed of an insulator exemplified by nylon. The gasket 14 closes the opening 18 of the positive electrode can 2. The gasket 14 has a support portion 41, a valve portion 42, an outer peripheral portion 43, and a clamping portion 44.

[0021] FIG. 3 is a view of the gasket shown in FIG. 1 as seen from the negative electrode mixture side. The support portion 41 is provided at the center of the gasket 14. A hole 41a formed coaxially with the positive electrode can 2 is formed in the support portion 41. The current collector rod 6 is inserted into the hole 41a. By being inserted into the hole 41a, the current collector rod 6 is supported by the gasket 14.

[0022] The valve portion 42 is formed in an annular shape so as to surround the support portion 41. As shown in FIG. 2, the valve portion 42 is formed thinner than other portions of the gasket 14. The valve portion 42 is a portion that functions as a safety valve that breaks when the internal pressure of the alkaline battery 1 rises.

[0023] The outer peripheral portion 43 is formed in an annular shape so as to surround the valve portion 42. The outer peripheral portion 43 is formed thicker than the valve portion 42. On the inner surface 45 of the outer peripheral portion 43 facing the negative electrode mixture 5 side, a facing surface 46 is formed that is curved so that the cross-sectional shape is concave toward the negative electrode terminal plate 12 side. On the outer surface 47 of the outer peripheral portion 43 facing the negative electrode terminal plate 12 side, the cross-sectional shape of the back surface portion of the facing surface 46 is curved so as to protrude toward the negative electrode terminal plate 12. Therefore, in the region where the facing surface 46 is formed, the gasket 14 itself is bent so as to protrude toward the negative electrode terminal plate 12.

[0024] Hatching is applied to the portion where the facing surface 46 is formed in FIG. 3. The facing surface 46 is formed so as to extend in an annular shape coaxially with the positive electrode can 2. The range where the facing surface 46 is formed is preferably in the range of 15% to 65% of the radius R of the gasket 14 from the center of the gasket 14.

[0025] Also, the radius of curvature r of the facing surface 46 in the cross-sectional shape is preferably 10% or more of the radius R of the gasket 14.

[0026] On the outer peripheral portion 43, a buffer portion 48 is provided on the outer peripheral side of the opposing surface 46. In the buffer portion 48, the gasket 14 itself is bent so as to protrude toward the positive electrode mixture 3.

[0027] The clamping portion 44 is formed in an annular shape so as to surround the outer peripheral portion 43. As shown in FIG. 2, the clamping portion 44 is sandwiched and held between the positive electrode can 2 and the negative electrode terminal plate 12. By sandwiching the clamping portion 44 between the positive electrode can 2 and the negative electrode terminal plate 12, the positive electrode can 2 and the negative electrode terminal plate 12 are electrically insulated.

[0028] The negative electrode terminal plate 12 is formed of a conductor exemplified by a metal. The negative electrode terminal plate 12 is provided at the opening 18 portion of the positive electrode can 2. More specifically, the negative electrode terminal plate 12 is provided on the opposite side of the separator 7 with the gasket interposed therebetween. A certain region from the portion overlapping the central axis of the cylindrical portion 15 of the positive electrode can 2 toward the outer periphery of the negative electrode terminal plate 12 serves as the negative electrode terminal 13. One end of the current collector rod 6 is joined to the negative electrode terminal plate 12.

[0029] <Regarding the process of forming the structure in which the contact portion is folded back> FIGS. 4 and 5 are diagrams showing the manufacturing process of the alkaline battery of Embodiment 1. As shown in FIG. 4, a current collector rod 6 inserted into a hole 41a formed in the gasket 14 is pre-joined to the negative electrode terminal plate 12. The negative electrode terminal plate 12 is inserted into the opening 18 portion of the positive electrode can 2 provided with the separator 7, the positive electrode mixture 3, and the negative electrode mixture 5 inside. As shown in FIG. 4, in the process of inserting the negative electrode terminal plate 12, the end portion of the side surface 21 of the separator 7 abuts against the opposing surface 46 of the gasket 14.

[0030] As shown in Fig. 5, when the negative electrode terminal plate 12 is further inserted, the 21 end portions on the side surface of the separator 7 are deformed and curved along the opposing surface 46. By further inserting the negative electrode terminal plate 12, as shown in Fig. 2, the contact region is curved and the end portion is folded back so as to face the negative electrode mixture 5 side. Also, in a state where the negative electrode terminal plate 12 is completely inserted, by compressing the opening 18 side of the positive electrode can 2 inward and bending the end portion inward, the alkaline battery 1 in the state shown in Fig. 2 in which the sandwiching portion 44 of the gasket 14 is sandwiched between the negative electrode terminal plate 12 and the positive electrode can 2 is obtained.

[0031] <Regarding leakage of the negative electrode mixture> In the alkaline battery 1 in which the gel-like negative electrode mixture 5 is provided inside the separator 7, for example, when it is dropped with the negative electrode terminal plate 12 side facing down and collides with the floor surface, the negative electrode mixture 5 that has flowed to the gasket 14 side may leak outside the separator 7 from between the separator 7 and the gasket 14. When the negative electrode mixture 5 leaks outside the separator 7, the negative electrode mixture 5 and the positive electrode mixture 3 come into contact with each other and a short circuit occurs.

[0032] Here, a comparative example of an alkaline battery will be described. Fig. 6 is a partially enlarged cross-sectional view showing an enlarged view of the contact portion between the separator and the gasket of the alkaline battery of Comparative Example 1. In the alkaline battery 101 of Comparative Example 1, the gasket 114 and the separator 107 are different from those of the alkaline battery 1 of Embodiment 1. Since there are no significant differences in other configurations, the same reference numerals are used. In the alkaline battery 101 of Comparative Example 1, the opposing surface for bending the separator is not formed on the inner surface 145 of the gasket 114. In the alkaline battery 101 of Comparative Example 1, the end portion of the separator 107 abuts on the recess 145a formed on the inner surface 145 of the gasket 114, but the end portion of the separator 7 is not curved.

[0033] FIG. 7 is an enlarged partial cross-sectional view showing the contact portion between the separator and the gasket of the alkaline battery of Comparative Example 2. In the alkaline battery 201 of Comparative Example 2, the gasket 214 and the separator 207 are different from those of the alkaline battery 1 of Embodiment 1. Since there are no significant differences in other configurations, the same reference numerals are used. In the alkaline battery 201 of Comparative Example 2, although the separator 207 contacts the inner surface 245 of the gasket 214 and is bent inward, the end portion is not folded back toward the negative electrode mixture 5 side.

[0034] FIG. 8 is a diagram showing the results of the drop test of the alkaline battery of Embodiment 1 and the alkaline battery of the comparative example. In the drop test, the alkaline batteries 1, 101, and 201 were dropped from a height of 1.5 m with the negative electrode terminal plate 12 facing downward. The number of drops for one sample was 10 times.

[0035] As shown in FIG. 8, a voltage drop occurred in some samples of the alkaline battery 101 of Comparative Example 1 and the alkaline battery 201 of Comparative Example 2. On the other hand, no voltage drop occurred in all samples of the alkaline battery 1 of Embodiment 1.

[0036] FIG. 9 is a diagram showing the results of the vibration test of the alkaline battery of Embodiment 1 and the alkaline battery of the comparative example. In the vibration test, a single vibration that changes at a rate of 1 Hz / min between 10 and 65 Hz was applied to the alkaline batteries 1, 101, and 201. Three-directional vibrations in the side-facing direction, the positive electrode terminal direction, and the negative electrode terminal direction were applied to one sample.

[0037] As shown in FIG. 9, a voltage drop occurred in some samples of the alkaline battery 101 of Comparative Example 1 and the alkaline battery 201 of Comparative Example 2. On the other hand, no voltage drop occurred in all samples of the alkaline battery 1 of Embodiment 1.

[0038] From the results of the drop test and the vibration test, it is considered that in the alkaline batteries 101 and 201 of Comparative Examples 1 and 2, the negative electrode mixture 5 leaked outside the separators 107 and 207 in some samples, causing a short circuit.

[0039] On the other hand, in the alkaline battery 1 of Example 1, voltage drop has not occurred in all samples, and it is considered that the negative electrode mixture 5 has not leaked outside the separator 7.

[0040] <Effect> In the alkaline battery 1 of Embodiment 1, a positive electrode can 2 having a bottomed cylindrical shape with a positive electrode terminal 17 formed on the bottom surface 16, a cylindrical positive electrode mixture 3 provided inside the positive electrode can 2 and arranged coaxially with the positive electrode can 2, a cylindrical separator 7 provided on the inner peripheral side of the positive electrode mixture 3, a gel-like negative electrode mixture 5 filled on the inner peripheral side of the separator 7, a current collector rod 6 inserted into the negative electrode mixture 5, a gasket 14 that supports the current collector rod 6 and closes the opening 18 of the positive electrode can 2, and a negative electrode terminal plate 12 provided at the opening 18 of the positive electrode can 2 on the opposite side of the separator 7 with the gasket 14 interposed therebetween. The separator 7 has a contact region 30 where a certain region from the end on the negative electrode terminal plate 12 side to the positive electrode terminal 17 side contacts the gasket 14. The contact region 30 is curved inward and the end is folded back so as to face the negative electrode mixture 5 side. Thereby, even when the negative electrode mixture 5 flows toward the gasket 14, it is possible to prevent the negative electrode mixture 5 from leaking outside the separator 7 through the gap between the separator 7 and the gasket 14. Thereby, it is possible to prevent the occurrence of a short circuit caused by the leakage of the negative electrode mixture 5 outside the separator 7.

[0041] Also, on the inner surface 45 of the outer peripheral surface of the gasket 14 facing the negative electrode mixture side, a facing surface 46 that extends annularly coaxially with the positive electrode can 2 and is curved so that the cross-sectional shape is concave on the negative electrode terminal plate 12 side is formed, and the contact region 30 contacts the facing surface 46. The curved facing surface 46 can curve the separator 7 in contact with the facing surface 46 inward so that the end faces the negative electrode mixture 5 side.

[0042] Further, the gasket 14 has a support portion 41 into which the current collector rod 6 is inserted to support the current collector rod 6, an annular valve portion 42 formed around the support portion 41, and an outer peripheral portion 43 formed thicker than the valve portion 42 and provided annularly on the outer periphery of the valve portion 42. The opposing surface 46 is formed on the outer peripheral portion 43. In the gasket 14, the back surface portion of the opposing surface 46 is curved so that the cross-sectional shape is convex toward the negative electrode terminal plate 12. Due to the curved shape of the opposing surface 46 and the curved shape of its back surface portion, the gasket itself is bent so as to be convex toward the negative electrode terminal plate 12 in the region where the opposing surface 46 is formed. The portion where the opposing surface 46 is formed and bent is easily deflectable in the radial direction. Here, in the manufacturing process of the alkaline battery 1, as described above, the opening 18 side of the positive electrode can 2 is compressed inward. At this time, the valve portion 42 formed thinner than other portions may be broken by the compression pressure. However, by the portion where the opposing surface 46 is formed and bent deflecting in the radial direction, the compression force applied to the valve portion 42 can be reduced, and the valve portion 42 can be prevented from breaking.

[0043] Further, the gasket 14 has a buffer portion 48 bent so as to be convex toward the positive electrode mixture 3 on the outer peripheral side of the opposing surface 46. The bent buffer portion 48 is easily deflectable in the radial direction. Therefore, in addition to the portion where the opposing surface 46 is formed and bent, the buffer portion 48 also deflects in the radial direction, so that the compression force applied to the valve portion 42 can be reduced, and the valve portion 42 can be prevented from breaking. Note that if there is a portion where the opposing surface 46 is formed and bent, the effect of reducing the compression force applied to the valve portion 42 can be obtained even if the buffer portion 48 is not provided.

[0044] Also, if the radius of curvature r of the opposing surface 46 in the cross-sectional shape is 10% or more of the radius R of the gasket 14, it becomes difficult for the negative electrode mixture 5 to reach the gap between the separator 7 and the gasket 14.

[0045] Also, if the range in which the opposing surface 46 is formed in the radial direction is in the range from 15% to 65% of the radius R of the gasket 14 from the center of the gasket 14, it becomes difficult for the negative electrode mixture 5 to reach the gap between the separator 7 and the gasket 14.

[0046] <Modification Example> FIG. 10 is a cross-sectional view of an alkaline battery according to a modification example of Embodiment 1. As shown in FIG. 10, the back surface portion of the opposing surface 46 in the gasket 14 may not be curved. In this case, since the portion where the opposing surface 46 is formed is not bent, the effect of reducing the compressive force applied to the valve portion 42 by the deflection of the portion where the opposing surface 46 is formed is lost. However, if the buffer portion 48 is provided, the compressive force applied to the valve portion 42 can be reduced by the buffer portion 48 bending, thereby preventing the valve portion 42 from breaking.

Description of Reference Numerals

[0047] 1 Alkaline battery 2 Positive electrode can 3 Positive electrode mixture 5 Negative electrode mixture 6 Current collector rod 7 Separator 12 Negative electrode terminal plate 13 Negative electrode terminal 14 Gasket 15 Side surface 16 Bottom surface 17 Positive electrode terminal 18 Opening 21 Side surface 22 Bottom surface 30 Contact area 41 Support portion 41a Hole 42 Valve portion 43 Outer peripheral portion 44 Clamping portion 45 Inner surface 46 Opposing surface 47 Outer surface 48 Buffer portion 101, 201 Alkaline battery 107, 207 Separator 114, 214 Gasket 245 Inner surface

Claims

1. A positive electrode can having a bottomed cylindrical shape with a positive electrode terminal formed on the bottom surface, a cylindrical positive electrode mixture provided inside the positive electrode can and arranged coaxially with the positive electrode can, a cylindrical separator provided on the inner peripheral side of the positive electrode mixture, a gel-like negative electrode mixture filled on the inner peripheral side of the separator, a current collector rod inserted into the negative electrode mixture, a gasket that supports the current collector rod and closes the opening of the positive electrode can, a negative electrode terminal plate provided at the opening of the positive electrode can and on the opposite side of the separator with the gasket interposed therebetween, and comprising: a contact region where a certain region from the end on the negative electrode terminal plate side to the positive electrode terminal side of the separator contacts the gasket, The contact region is curved inward and is folded back so that the end faces the negative electrode mixture side. An alkaline battery.

2. On the surface of the outer peripheral surface of the gasket facing the negative electrode mixture side, an opposing surface is formed that extends in an annular shape coaxially with the positive electrode can and is curved so that the cross-sectional shape is concave on the negative electrode terminal plate side, The alkaline battery according to claim 1, wherein the contact region contacts the opposing surface.

3. The gasket has a support portion into which the current collector rod is inserted and that supports the current collector rod, an annular valve portion formed around the support portion, and an outer peripheral portion formed thicker than the valve portion and provided annularly on the outer periphery of the valve portion, The opposing surface is formed on the outer peripheral portion, In the gasket, the back surface portion of the opposing surface is curved so that the cross-sectional shape is convex toward the negative electrode terminal plate. The alkaline battery according to claim 2.

4. The alkaline battery according to claim 3, wherein the gasket has a buffer portion bent so as to be convex toward the positive electrode mixture on the outer peripheral side of the opposing surface.

5. The alkaline battery according to claim 2, wherein the radius of curvature of the opposing surface in the cross-sectional shape is 10% or more of the radius of the gasket.

6. The alkaline battery according to claim 2, wherein the range in which the opposing surface is formed in the radial direction is in the range of 15% to 65% of the radius of the gasket from the center of the gasket.

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