JP4462944B2 - Alkaline battery - Google Patents

Description

  The present invention relates to an alkaline battery having a safety valve function that operates when the internal pressure of a battery abnormally increases.

  As shown in FIG. 4, a cylindrical alkaline dry battery called model number LR is loaded and stored with a power generation element 20 containing an alkaline electrolyte in a bottomed cylindrical metal positive electrode can 10 that also serves as a positive electrode terminal and a current collector. Has been. The power generation element 20 is formed of a positive electrode mixture 21, a separator 22, and a gelled negative electrode mixture 23 that are formed into a tubular shape.

  The positive electrode can 10 is sealed using a substantially dish-shaped metal negative electrode terminal plate 40 and a substantially disk-shaped resin gasket 50. The negative electrode terminal plate 40 is disposed at a position that closes the opening of the positive electrode can 10, and the gasket 50 is interposed between the negative electrode terminal plate 40 and the positive electrode can 10, whereby the inside of the positive electrode can 10 is hermetically sealed. ing. On the inner side (battery inner side) surface of the negative electrode terminal plate 40, a rod-shaped metal negative electrode current collector 30 inserted into the negative electrode mixture 23 is fixed vertically by spot welding or the like.

  Furthermore, the illustrated battery has a safety valve function. The safety valve function is formed by the thin portion 54 of the gasket 50 and the gas vent hole 41 of the negative electrode terminal plate 40. The gasket 50 is a resin molded product such as polypropylene or nylon (6 or 6,6 nylon). Packing part 52 interposed between the peripheral part and the peripheral part, intermediate partition part 53 interposed between the inner space part of negative electrode terminal plate 40 and the power generation space part in positive electrode can 10, and thin part 54 Are integrally formed. The thin portion 54 is formed in an annular portion between the boss portion 51 and the intermediate partition wall portion 53. The inner space of the negative electrode terminal plate 40 communicates with the outside (atmospheric pressure) through a gas vent 41 provided near the periphery of the negative electrode terminal plate 40.

FIGS. 5A and 5B show the operating state of the safety valve function. First, when the battery internal pressure is within the normal range, the gasket 50 hermetically isolates the inner space of the negative electrode terminal plate 40 from the inside of the battery, as shown in FIG. When the battery internal pressure rises abnormally, as shown in FIG. 5B, the gasket 50 is preliminarily broken in an annular shape at the thin wall portion 54, so that the generated gas in the battery is discharged from the gas vent hole 41 to the outside of the battery. The battery is prevented from bursting. In addition, the alkaline dry battery provided with this kind of safety valve function is disclosed by patent document 1, etc., for example.
JP-A-7-240195

  Alkaline batteries are widely used as power sources with the spread of portable electronic devices and cordless electronic devices. This alkaline battery has evolved with various devices as the devices progress. Even so, the demand for higher performance and higher reliability remains, and efforts are being made to meet these demands.

  A strong demand for the performance items of alkaline batteries is an increase in discharge capacity. The most effective measure for increasing the discharge capacity is to increase the amount of the power generation agent. The only way to increase this amount within the standard size is to increase the volume utilization efficiency inside the battery. For this purpose, it is necessary to reduce as much as possible the space that is not used for filling the power generating substance, that is, the non-filling space.

  On the other hand, it is an important issue to improve the operational reliability of the safety valve function for increasing the reliability of the alkaline battery. In order for the safety valve function to operate reliably, when the gasket 50 is broken due to an abnormal internal pressure, there is a ventilation path through which the generated gas in the battery causing the abnormal internal pressure is released to the outside. Must be formed reliably. However, as shown in FIG. 5B, when the broken gasket 50 is in close contact with the inside of the negative electrode terminal plate 40, the ventilation path leading to the vent hole 41 of the negative electrode terminal plate 40 is blocked. As a result, a malfunction may occur in which the safety valve function does not operate normally.

  As a countermeasure for avoiding the above-mentioned malfunction, it is conceivable to increase the distance between the gasket, particularly the intermediate partition wall and the negative terminal plate (for example, Patent Document 1). However, if the distance between the gasket and the negative electrode terminal plate is large, there arises a problem that improvement in battery performance is hindered due to a decrease in volume available for power generation inside the battery.

  As another means for preventing the above malfunction, as shown in FIG. 5C, a rib 55 protruding toward the negative electrode terminal plate 40 is integrally formed on the gasket 50 by molding, and the gasket 50 is formed by abnormal internal pressure. There has been proposed a configuration in which when the rib 55 is broken, the rib 55 is interposed between the gasket 50 and the negative electrode terminal plate 40 to ensure a vent path for degassing (Patent Document 2). However, this means has a problem that the shape of the gasket 50 is complicated, and the flow of the resin at the time of molding becomes non-uniform, making it difficult to obtain a gasket with stable characteristics with good reproducibility. It was.

  As a means other than the above, by providing a non-thin portion in the middle of the thin portion, the movement when the gasket is broken due to abnormal internal pressure is reduced, and thereby the gas is released due to the gasket being in close contact with the negative electrode terminal plate. There is also a configuration for avoiding blockage of the route. However, this configuration, like the above, complicates the structure of the gasket, makes the resin flow non-uniform during molding, and further reduces the operating accuracy and reliability due to incomplete fracture of the gasket. There was also a problem of causing a drop.

The present invention has been made in view of the problems as described above, and the object thereof is excellent in mass production without hindering improvement of battery performance, without destabilizing the characteristics of the gasket. An object of the present invention is to provide a highly-reliable alkaline battery having a low-cost and highly reproducible configuration and capable of reliably operating a safety valve function when the battery internal pressure rises abnormally.
US Pat. No. 6,270,919

The means of the present invention is characterized by the following (1).
(1) a bottomed cylindrical positive electrode can also serving as a positive electrode terminal, a power generation element including an alkaline electrolyte housed in the positive electrode can, a substantially dish-shaped negative electrode terminal plate that closes an opening of the positive electrode can, A resin sealing gasket that is interposed between the negative electrode terminal plate and the positive electrode can and hermetically seals the inside of the positive electrode can, and when the internal pressure of the battery is abnormally increased, in the alkaline battery of the generated gas and a safety valve functions as escape to the outside from the gas vent holes formed in the negative terminal plate, the protrusion protruding to the gasket side in the negative electrode terminal plate is formed, the convex parts, when being broken by abnormal increase in battery internal pressure, to ensure ventilation path of the generated gas by interposed between the gasket and the negative electrode terminal plate.

For example, the following embodiments (2) to (6) are suitable for the above means.
(2) The alkaline dry battery according to (1), wherein the convex portion of the negative electrode terminal plate is formed in a non-annular shape.
(3) The alkaline dry battery according to (1) or (2), wherein the convex portion of the negative electrode terminal plate comprises a plurality of top portions.
(4) In the above (3), an alkaline dry battery characterized in that the heights and / or widths and the like of the tops are formed unevenly.
(5) The alkaline dry battery according to (1) or (2), wherein the convex portion of the negative terminal plate is formed in a table shape having a radial or irregular plane pattern.
(6) In any one of the above (1) to (5), the negative electrode terminal plate has a rod-shaped negative electrode current collector inserted into the negative electrode mixture of the power generation element vertically fixed on the inner surface thereof, The gasket is a resin molded product, and is interposed between a central boss portion that allows the negative electrode current collector to pass through in an airtight state, an opening of the positive electrode can, and a peripheral portion of the negative electrode terminal. A packing part, an intermediate partition part interposed between the inner space part of the negative electrode terminal plate and the power generation space part in the positive electrode can, and a thin part that induces a preceding fracture of the gasket are formed coaxially. An alkaline battery having a shape that does not have an axially asymmetric rib.

  Without hindering the improvement of battery performance, without destabilizing the characteristics of the gasket, and with a low-cost and highly reproducible configuration that is suitable for mass production, the safety valve function is activated when the battery internal pressure rises abnormally. A highly reliable alkaline dry battery that operates reliably can be provided.

  FIG. 1 shows a schematic cross section of an alkaline battery according to an embodiment of the present invention. The alkaline dry battery shown in the figure is a cylindrical alkaline dry battery called LR model number, and its basic configuration is the same as that shown in FIG. That is, a power generation element 20 containing an alkaline electrolyte is loaded in a bottomed cylindrical metal positive electrode can 10 that also serves as a positive electrode terminal and a current collector. The power generation element 20 is formed of a positive electrode mixture 21, a separator 22, and a gelled negative electrode mixture 23 that are formed into a tubular shape.

  The positive electrode can 10 is sealed using a substantially dish-shaped metal negative electrode terminal plate 40 and a substantially disk-shaped resin gasket 50. The negative electrode terminal plate 40 is disposed at a position that closes the opening of the positive electrode can 10, and the gasket 50 is interposed between the negative electrode terminal plate 40 and the positive electrode can 10, whereby the inside of the positive electrode can 10 is hermetically sealed. ing. On the inner surface (battery inner side) surface of the negative electrode terminal plate 40, a rod-shaped metal negative electrode current collector 30 inserted into the negative electrode mixture 23 is fixed vertically by spot welding or the like.

  The gasket 50 includes a central boss 51 that allows the negative electrode current collector 30 to pass through in an airtight state, a packing 52 that is interposed between the opening of the positive electrode can 10 and the peripheral edge of the negative electrode terminal 40, An intermediate partition wall portion 53 and a thin wall portion 54 that are interposed between the inner space portion of the negative electrode terminal plate 40 and the power generation space portion in the positive electrode can 10 are integrally formed. The thin portion 54 is formed in an annular portion between the boss portion 51 and the intermediate partition wall portion 53.

  The gasket 50 is a resin molded product such as polypropylene or nylon (6 or 6,6 nylon), and the central boss portion 51, the packing portion 52, the intermediate partition wall portion 53, and the thin portion 54 are formed coaxially. And is formed in a shape having no axially asymmetric rib. Such a shape is suitable for making the flow of the resin smooth and uniform during molding and obtaining a gasket having stable characteristics with good reproducibility.

  FIG. 2 focuses on the part of the safety valve function which is a main part of the present invention. This safety valve function is shown in FIG. Forty gas vent holes 41 are formed. The inner space of the negative electrode terminal plate 40 communicates with the outside (atmospheric pressure) through a gas vent 41 provided near the periphery of the negative electrode terminal plate 40. The negative electrode terminal plate 40 is formed with a convex portion 42 protruding toward the gasket 50 side.

  Here, when the battery internal pressure rises abnormally due to gas generation inside the battery, as shown in FIG. 5B, the thin portion 54 is preliminarily broken by the abnormally increased internal pressure. As a result, the internally generated gas escapes through the gas vent hole 41 to the outside of the battery (atmosphere), thereby preventing the battery from bursting. At this time, the convex portion 42 of the negative electrode terminal plate 40 is interposed between the gasket 50 and the negative electrode terminal plate 40 when the gasket 50 is broken due to an abnormal increase in battery internal pressure. Ensure ventilation path.

  As described above, according to the above configuration, the gasket 50 that is broken in an annular shape due to the internal pressure of the battery is pushed and moved toward the negative electrode terminal plate 40 as shown in FIG. 40 has the convex portion 42 interposed therebetween. The convex portion 42 prevents the inside of the gasket 50, that is, the inside of the battery and the gas vent hole 41 of the negative electrode terminal plate 40 from being hermetically closed. In other words, the convex portion 42 is interposed between the gasket and the negative terminal plate, which are broken due to an abnormal increase in the internal pressure of the battery, so that a ventilation path for guiding the generated gas inside the battery to the vent hole 41 is secured. Thereby, a safety valve function can be operated reliably.

  The convex portion 42 can be formed together during the press working for producing the negative electrode terminal plate 40. This ensures that the safety valve function is ensured when the internal pressure of the battery rises abnormally, with a low-cost and highly reproducible configuration that is suitable for mass production without giving the gasket 50 complicated shapes such as ribs that destabilize its characteristics. Thus, a highly reliable alkaline battery that operates in a highly reliable manner can be configured.

  FIG. 3 is a perspective view showing an embodiment of the negative electrode terminal plate 40. In the same figure, (a) shows the conventional negative electrode terminal plate 40 which does not have the said convex part 42. FIG. (B)-(e) show the negative electrode terminal board 40 of this invention which has the said convex part 42, respectively.

  As shown in (b) to (e) of the figure, the convex portion 42 of the negative electrode terminal plate 40 is desirably formed in a shape that does not close in a ring shape, that is, in a non-ring shape. Further, as shown in (b) or (e) of the figure, the convex portion 42 may be a convex portion composed of a plurality of top portions 421 independent of each other. In this case, the operational reliability of the safety valve function can be further enhanced by ensuring that at least one of the top portions 421 secures a ventilation path when the gasket is broken. The plurality of top portions 421 may be arranged in circles at equal intervals as shown in (b), or may be arranged in an arc shape as shown in (e). If the heights and / or widths of the plurality of top portions 421 are formed non-uniformly, it is possible to further ensure the ventilation path when the gasket is broken.

  Even if the convex portion 42 is not formed by a plurality of top portions 421, for example, as shown in (c), even if it is formed by arc-shaped ribs 422, it is effective for enhancing the operation reliability of the safety valve function. Further, as shown in (d), the convex portion 42 may be formed in a trapezoidal shape having a radial or irregular plane pattern. The circle arrangement shown in (b) and the radial pattern shown in (d) are each axially symmetric, but this shape distributes the stress strain of the negative electrode terminal plate 40 evenly, thereby improving the dimensional accuracy and the like. It can contribute to characteristic stabilization.

  Using the negative electrode terminal plate 40 shown in FIGS. 3A to 3E, five types of LR20 alkaline batteries A to E were made on a trial basis. In this case, the negative electrode terminal plate 40 shown in FIG. 3A was used in combination with the gasket 50 with the rib 55 shown in FIG. 5C to constitute a sealing portion and a safety valve function. Each of the negative electrode terminal plates 40 with the convex portions 42 shown in FIGS. 3B to 3E was used in combination with the gasket 50 without the rib 55 to constitute a sealing portion and a safety valve function.

=== Experiment 1: Test of gasket defect rate =================
In producing the above five types of prototype batteries A to E, first, a gasket produced by resin molding was observed and measured for cracks, retraction, voids, presence / absence of discoloration, breaking pressure of the thin portion, etc., and the defective rate investigated. The cracks, retraction, voids, and discoloration were judged visually. The breaking pressure was judged by measurement, and the result was within ± 10% of the target pressure.

=== Experiment 2: Safety test =================
Next, in order to compare and examine the effect of changing the shape of the negative electrode terminal, safety tests of the above five types of prototype batteries (LR20) A to E were performed. A is a conventional dry battery, and B to E are the battery of the present invention.

The results of Experiment 1 and Experiment 2 are summarized in Table 1.

  As described above, the present invention has been described based on the typical embodiments. However, the present invention can have various modes other than those described above. For example, the convex part 42 of the negative electrode terminal plate 40 can be variously modified in addition to the above.

  Without hindering the improvement of battery performance, without destabilizing the characteristics of the gasket, and with a low-cost and highly reproducible configuration that is suitable for mass production, the safety valve function is activated when the battery internal pressure rises abnormally. A highly reliable alkaline dry battery that operates reliably can be provided.

It is sectional drawing which shows one Embodiment of the alkaline dry battery with a safety valve function by this invention. It is an abbreviated sectional view showing an embodiment of a safety valve functional part of an alkaline dry battery by the present invention. It is a perspective view which shows various embodiment of the negative electrode terminal plate which makes the principal part of this invention. It is sectional drawing which shows the structural example of the conventional alkaline dry battery with a safety valve function. It is an abbreviated sectional view showing a configuration example of a conventional safety valve function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Positive electrode can 20 Electric power generation element 21 Positive electrode mixture 22 Separator 23 Gel-like negative electrode mixture 30 Negative electrode current collection 40 Negative electrode terminal board 41 Gas vent hole 42 Convex part 421 Top part 422 Arc-shaped rib 50 Gasket 51 Central boss part 52 Packing part 53 Middle Partition part 54 Thin part 55 Rib (conventional)

Claims (6)

A bottomed cylindrical positive electrode can also serving as a positive electrode terminal, a power generation element containing an alkaline electrolyte housed in the positive electrode can, a substantially dish-shaped negative electrode terminal plate for closing the opening of the positive electrode can, and the negative electrode terminal A resin sealing gasket interposed between the plate and the positive electrode can to hermetically seal the inside of the positive electrode can, and a gas generated in the battery by breaking the gasket into an annular shape when the internal pressure of the battery abnormally increases In the alkaline dry battery with a safety valve function that escapes from the vent hole formed in the negative electrode terminal plate to the outside, a convex portion protruding to the gasket side is formed on the negative electrode terminal plate, and the convex portion is An alkaline dry battery characterized in that when it is ruptured due to an abnormal increase in internal pressure of the battery, an air passage for the generated gas is secured by being interposed between the gasket and the negative electrode terminal plate.   2. The alkaline dry battery according to claim 1, wherein the convex portion of the negative electrode terminal plate is formed in a non-annular shape.   3. The alkaline dry battery according to claim 1, wherein the convex portion of the negative electrode terminal plate is composed of a plurality of top portions.   5. The alkaline dry battery according to claim 4, wherein the heights and / or widths of the plurality of top portions are formed unevenly.   3. The alkaline dry battery according to claim 1, wherein the convex portion of the negative electrode terminal plate is formed in a base shape having a radial or irregular plane pattern. 6. The negative electrode terminal plate according to claim 1, wherein a rod-shaped negative electrode current collector inserted into the negative electrode mixture of the power generation element is vertically fixed on an inner surface of the negative electrode terminal plate, and the gasket is a resin molded product. A central boss that allows the negative electrode current collector to pass through in an airtight state, a packing portion that is interposed between the opening of the positive electrode can and the peripheral edge of the negative electrode terminal, and A rib that is axially asymmetric with an intermediate partition wall interposed between the inner space of the negative electrode terminal plate and the power generation space in the positive electrode can, and a thin wall that induces a preceding fracture of the gasket. An alkaline dry battery characterized by having no shape.

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