JP2018166024A - Cylindrical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical battery capable of surely and promptly releasing an inner pressure after actuating an explosion-proof safety mechanism.SOLUTION: The present invention relates to a cylindrical battery 1a configured by mounting, to an upper opening of a bottomed cylindrical battery can 2 in which power generation elements (3, 4 and 5) are accommodated, a sealing body 10a consisting of a cup-shaped terminal plate 8a with which a flange part 81 is formed, and a disk-shaped sealing plate 7 through a sealing gasket 9. The sealing plate is abutted to a bottom face of the flange part of the terminal plate which is disposed while positioning a bottom part 82 at an upper side. The terminal plate includes a first cutting blade 85 configured by bending a tongue piece that is formed from a notch 83 on a bottom downwards, and an exhaust port 86. The terminal plate also includes a second cutting blade 85a configured by bending multiple notches 83a that are disposed at equal angle intervals on a peripheral side face 87, inwards and obliquely downwards and a ventilation hole 88a. A front end of the second cutting blade is positioned lower than a front end of the first cutting blade.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cylindrical battery in which a power generation element is housed in a bottomed cylindrical battery can, and more specifically to an explosion-proof safety mechanism for the cylindrical battery.

  As an example of a cylindrical battery that is a subject of the present invention, a bobbin-type lithium primary battery having a bottomed cylindrical battery can is given. FIG. 1 shows the structure of the bobbin-type lithium primary battery (hereinafter also referred to as a cylindrical battery 1). In the following description, when the direction of the cylindrical axis 100 of the bottomed cylindrical battery can 2 is defined as the vertical direction and the bottom direction of the battery can 2 is defined as the downward direction, FIG. FIG. 1B is a plan view when the cylindrical battery 1 is viewed from above. FIG. 1C is a cross-sectional view taken along the line bb in FIG. 1A. Here, the upper end side of the cylindrical battery 1 is shown enlarged. Note that FIG. 1A corresponds to a cross section taken along the line aa in FIG.

  As shown in FIG. 1A, the illustrated cylindrical battery 1 has a bottomed cylindrical battery can 2 that opens upward, and a positive electrode active material such as manganese dioxide, similar to a ring core, together with a conductive aid such as graphite. A positive electrode mixture 3 formed into a hollow cylindrical shape, a cylindrical negative electrode lithium 4, a cylindrical cup-shaped separator 5, a sealing body 10 that also serves as a negative electrode terminal and hermetically seals the opening of the battery can 2. . The battery can 2 is filled with a non-aqueous electrolyte.

The battery can 2 is made of metal and serves as a battery case and a positive electrode current collector. A terminal portion 21 of the positive electrode is formed on the lower bottom surface so as to protrude outward by pressing. Further, a beading portion 22 by drawing is formed around the vicinity of the opening. A positive electrode mixture 3 is press-fitted into the battery can 2, and a negative electrode lithium 4 is disposed inside the hollow cylindrical positive electrode mixture 3 via a separator 5.
The negative electrode lithium 4 is attached with one end of a negative electrode lead 6 that is formed of a strip-shaped metal thin plate and also serves as a negative electrode current collector. The other end is spot welded to the lower surface of a disc-shaped sealing plate 7 made of a metal thin plate such as stainless steel constituting the sealing body 10. The sealing body 10 includes the sealing plate 7 and a negative terminal plate 8 made of a metal such as stainless steel. The terminal plate 8 has a cup shape in which a hollow disc-shaped flange portion 81 is integrally formed around the opening, and is laminated with the sealing plate 7 with the bottom portion 82 facing upward like a faced cup. Has been.

  The sealing body 10 is mounted with the resin sealing gasket 9 inside the opening of the battery can 2 with the beading part 22 as a seat, and the upper end of the battery can 2 above the beading part 22 is caulked inward. The battery can 2 is fitted by curling.

  As shown in FIG. 1B, in the cylindrical battery 1 having the above-described structure, a substantially V-shaped notch 83 is defined substantially at the center of the bottom 82 of the cup-shaped terminal plate 8. A tongue piece having a base 84 as one side connecting the ends of the two is bent downward at the base 84. Thereby, the tongue piece becomes a cutting blade 85 having a sharp tip. Then, by forming this cutting blade 85 at the bottom portion 82 of the terminal plate 8, an acute-angled triangular hole (exhaust port) 86 that communicates the inside and the outside opens. Further, as shown in FIG. 1C, a wall surface (peripheral side surface) 87 that hangs downward from the periphery of the bottom portion 82 of the terminal plate 8 and reaches the flange portion 81 communicates the inside and outside of the terminal plate 8. A small hole (vent hole) 88 is formed.

  The sealing plate 7 and the cutting blade 85 operate as an explosion-proof safety mechanism when gas is generated inside the cylindrical battery 1 due to overdischarge or charging due to misuse of the cylindrical battery 1 and the internal pressure rises. The exhaust port 86 serves as a passage (exhaust passage) for connecting the inside and outside of the battery can 2 to discharge gas outward, and the vent hole 88 plays a role as an auxiliary exhaust passage.

  FIG. 2 shows the operation of the explosion-proof safety mechanism in the cylindrical battery 1 shown in FIG. FIG. 2 (A) shows the state of the sealing body 10 when the internal pressure rises, and FIG. 2 (B) is a diagram when the explosion-proof safety mechanism is activated. First, as shown in FIG. 2A, when the internal pressure rises, the sealing plate 7 bends so that a circular region having a diameter φ1 that is not in contact with the lower surface of the flange portion 81 of the terminal plate 8 swells upward. Then, as shown in FIG. 2B, when the sealing plate 7 further expands upward, the tip of the cutting blade 85 pierces the sealing plate 7 and opens a hole 70 in the sealing plate 7. As a result, a path (exhaust path) from the hole 70 to the exhaust port 86 is formed, and the gas in the cylindrical battery 1 escapes to the outside. A part of the gas is exhausted to the outside through an exhaust path from the hole 70 opened in the sealing plate 7 to the vent hole 88. The exhaust path is indicated by a thick arrow in the figure. In this way, the tubular battery 1 can be prevented from bursting. The pressure at which the explosion-proof safety mechanism operates is set, for example, to about 2.5 MPa to 3.5 MPa in a CR17450 type bobbin-type lithium primary battery.

  In addition, the following patent document 1 is described about the cylindrical battery provided with the explosion-proof safety mechanism of the aspect which opens a hole in a sealing board with a cutting blade. Non-Patent Document 1 below describes a bobbin-type lithium primary battery having an explosion-proof safety mechanism having the same structure.

JP 2010-186650 A

FDK Corporation, “High Capacity Cylindrical Lithium Primary Battery”, [online], [Search February 9, 2017], Internet <URL: http://www.fdk.co.jp/battery/lithium/lithium_cylindrical .html>

  In the conventional explosion-proof safety mechanism in a cylindrical battery, when the pressure in the battery can suddenly rises, the cutting blade breaks the sealing plate and the explosion-proof safety mechanism itself operates, but the break point depends on the contents of the battery. There was a possibility of being blocked. If the broken part is blocked by the contents of the battery, the internal pressure of the battery can cannot be quickly released. When the internal pressure rises explosively, there is a possibility that the contents of the battery and parts (sealing body, lead terminal, etc.) constituting the battery will be scattered.

  In addition, when the pressure in the battery can rises at a slow rate, the sealing plate bends at a slower rate, and even if the explosion-proof safety function is activated and the tip of the cutting blade pierces the sealing plate, In some cases, the blade gradually bites into the sealing plate, and the cutting blade itself becomes a plug that closes the broken portion. Even in such a case, the internal pressure of the battery can cannot be quickly released. Furthermore, the pressure continues to rise until the cutting blade bites deeply into the sealing plate and the sealing plate is torn, and when the sealing plate is torn, the contents may be ejected from the cut opening at a stroke.

  Therefore, an object of the present invention is to provide a cylindrical battery that can reliably and quickly release the internal pressure after the operation of the explosion-proof safety mechanism.

One aspect of the present invention for achieving the above object is that a power generation element is housed in a bottomed cylindrical metal battery can that opens in a circular shape upward, and a resin seal is formed in the opening of the battery can. A cylindrical battery in which a sealing body is fitted through a gasket and the battery can is sealed,
The sealing body is made of a metal, and is composed of a cup-shaped terminal plate in which a hollow disk-shaped flange portion is formed at the edge of a circular opening, and a disk-shaped sealing plate made of a thin metal plate, While the terminal plate is disposed with the bottom portion facing upward, the sealing plate is disposed below the terminal plate in a state of contacting the lower surface of the flange portion,
The terminal plate includes a first cutting blade and an exhaust port formed in the bottom portion, and is provided at a plurality of positions at equiangular intervals on a circumferential side surface that is connected to the flange portion while being suspended downward from a peripheral edge of the bottom portion. A second cutting blade and a vent hole formed,
The first cutting blade is formed by bending a tongue piece cut away leaving one side as a base end downward toward the inside of the battery can at the base end,
The first exhaust port is opened as a mark that forms the first cutting blade,
The second cutting blade has a tongue piece that is cut out with one side along the circumference of the boundary between the flange portion and the peripheral side surface of the terminal plate as a base end at the base end of the battery can. Folded diagonally downward toward the inside,
The vent hole is opened as a mark forming the second cutting blade,
The tip of the second cutting blade is below the tip of the first cutting blade,
It is set as the cylindrical battery characterized by this.

  The cylindrical battery may be a cylindrical battery characterized in that the tip of the second cutting blade is located outside the inner periphery of the bottom portion when viewed from the vertical direction.

  The cylindrical battery of the present invention can reliably and quickly release the internal pressure after the operation of the explosion-proof safety mechanism, and has high safety. Other effects will be clarified in the following description.

It is a figure which shows an example of a cylindrical battery. It is a figure explaining operation | movement of the conventional explosion-proof safety mechanism in a cylindrical battery. It is a figure which shows the structure of the sealing body with which the cylindrical battery which concerns on the Example of this invention is provided. It is a figure explaining operation | movement of the explosion-proof safety mechanism in the cylindrical battery which concerns on an Example. It is a figure which shows the performance of the explosion-proof safety mechanism in the cylindrical battery which concerns on an Example.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that in the drawings used for the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. In some drawings, unnecessary symbols may be omitted in the description.

=== Example ===
<Structure of sealing body>
The basic configuration of the cylindrical battery according to the embodiment of the present invention is the same as that of the conventional cylindrical battery 1 shown in FIG. However, the structure of the sealing body is different from the conventional one. The principal part of the cylindrical battery 1a which concerns on FIG. 3 at the present Example was shown. FIG. 3A is a plan view of the cylindrical battery 1a of this embodiment as viewed from above, and FIG. 3B is a cross-sectional view taken along the line cc in FIG. The upper end side of the can 2 is shown enlarged.

  As shown in FIG. 3 (A), the terminal plate 8a in the cylindrical battery 1a of the present embodiment is formed by bending a triangular tongue piece formed by a V-shaped notch 83 in the bottom portion 82 downward. A blade 85 and an exhaust port 86 opened by forming the cutting blade 85 are formed. A plurality of air holes 88a are formed at equal angular intervals around the cylindrical shaft 100 from the peripheral side surface 87 of the terminal plate 8a to the flange portion 81 when viewed from above. In this example, it is formed at 8 positions at intervals of 45 °. Further, each vent hole 88a is formed by bending a tongue piece 85a formed by a V-shaped notch protruding upward, with one side along the circumference serving as a boundary between the peripheral side surface 87 and the flange portion 81 being a base end 84a. It has been opened by being.

  As shown in FIG. 3B, the boundary between the peripheral side surface 87 and the flange portion 81 is a curved surface, and the peripheral side surface 87 and the flange portion 81 are smoothly continuous through the boundary. The plurality of vent holes 88a have a triangular tongue 85a formed by a notch 83a having a base end 84a at the boundary and formed on the peripheral side surface 87, and obliquely downward with the base end 84a as a fold line. It opens as a folded mark. The tip of the tongue piece 85a is positioned below the tip of a cutting blade (hereinafter also referred to as a first cutting blade 85) provided on the bottom portion 82. And this tongue piece 85a is a cutting blade different from the 1st cutting blade 85 (henceforth the 2nd cutting blade 85a).

<Operation of explosion-proof safety mechanism>
FIG. 4 shows the operating state of the explosion-proof safety mechanism using the cylindrical battery 1a of this embodiment. 4A to 4C show the transition of the operating state of the explosion-proof safety mechanism accompanying the increase in internal pressure, and only the sealing body 10a is shown here. First, as shown in FIG. 4A, when the internal pressure increases, the sealing plate 7 bends upward. At this time, since the second cutting blade 85a is bent obliquely downward from the base end 84a to the inside of the terminal plate 8a, the tip of the second cutting blade 85a is naturally formed on the sealing plate 7. It contacts the upper surface of the sealing plate 7 at a shallow angle at a position inside the contact area between the upper surface and the lower surface of the flange portion 81 of the terminal plate 8a. When the internal pressure further rises, the sealing plate 7 is restricted from being bent upward by the second cutting blade 85a in contact with the upper surface of the sealing plate 7, and is an area having a diameter φ2 inward of the contact area having the diameter φ1. Only can be deformed by internal pressure. That is, the sealing plate 7 receives the internal pressure in a smaller area than the conventional one, and the sealing plate 7 bends rapidly and greatly upward. Thereby, as shown in FIG. 3B, the first cutting blade 85 quickly breaks the sealing plate 7. That is, in the cylindrical battery according to the embodiment, the time from when the first cutting blade 85 abuts against the sealing plate 7 until it breaks can be shortened, and the battery before the contents close the break point 70 can be shortened. The gas in the can can be discharged outward. Of course, even when the internal pressure gradually rises at a slow speed, the internal pressure rapidly rises when the second cutting blade 85a comes into contact with the sealing plate 7, so that the first cutting blade 85 bites into the sealing plate 7 quickly. Accordingly, it is possible to prevent the first cutting blade 85 itself from becoming a plug that closes the broken portion 70. Even when the first cutting blade 85 closes the fractured portion 70 and the internal pressure further increases, as shown in FIG. 3C, the plurality of second cutting blades 85a push the sealing plate 7 at a plurality of locations. Break. Therefore, the internal pressure can be released before reaching a large internal pressure at which the contents are ejected or components are scattered. Further, a plurality of ventilation paths are secured by the plurality of breakage points 70a, the contents and the like are not concentrated at one place, and the ejection of the contents and the scattering of the parts can be more reliably suppressed.

  Thus, the cylindrical battery 1a of the present embodiment has a feature in the structure of the sealing body 10a, and when the explosion-proof safety mechanism operates, the internal pressure in the battery can 2 is reliably and promptly released. It is like that.

=== Safety test ===
Next, the cylindrical battery 1a according to this example shown in FIG. 3 was produced as a sample. Further, as a comparative example to the example, the conventional cylindrical battery 1 shown in FIG. 1 was also produced as a sample. The structure and structure other than the sealing bodies (10a, 10) in the samples of Examples and Comparative Examples are the same as those of the cylindrical battery 1 shown in FIG. 1, and here corresponds to the CR17450 type having a diameter of 17 mm and a height of 45.0 mm. A bobbin-type lithium battery was manufactured. Assuming that the cylindrical batteries (1a, 1) are misused in extremely severe situations, each sample is heated by a burner, and after the sample is completely discharged, a current of 1 A is further applied. And an abnormal charge test in which charging was performed at a current of 15 mA based on the UL standard. In each test, 15 samples of two types corresponding to each of the example and the comparative example were prepared. In each test, the number of individuals in which the contents in the battery can and the parts constituting the sealing body were scattered due to the increase in internal pressure was examined.

  Table 1 below shows the results of each test.

表１において、サンプル１は実施例に係る筒型電池１ａであり、サンプル２は比較例に係る筒型電池１である。この表１に示したように、実施例となるサンプル１は、各試験の全てにおいて、１５個の個体の内、内容物や部品が飛散した個体が一つもなかった。一方、比較例となるサンプル２では、加熱試験、強制放電試験、および異常充電試験のそれぞれについて、１５個中１個、２個、および１個の個体において内容物あるいは部品が飛散した。以上により本発明の実施例に係る筒型電池では、極めて高い安全性を有していることが確認できた。

In Table 1, sample 1 is a cylindrical battery 1a according to an example, and sample 2 is a cylindrical battery 1 according to a comparative example. As shown in Table 1, Sample 1 as an example did not have any individual in which the contents and parts were scattered among the 15 individuals in all the tests. On the other hand, in sample 2 as a comparative example, the contents or parts were scattered in one, two, and one individual out of fifteen for each of the heating test, forced discharge test, and abnormal charge test. From the above, it was confirmed that the cylindrical battery according to the example of the present invention has extremely high safety.

  Next, in order to reproduce the situation in which the pressure in the battery can 2 gradually increases, the opening of the battery can 2 is sealed with a sealing body 10 similar to that of the conventional cylindrical battery 1 shown in FIG. A sample and a sample sealed with the sealing body 10a of the cylindrical battery 1a according to the example shown in FIG. 3 were produced. In each sample, a hole communicating with the inside and outside of the battery can 2 is formed, and compressed air is introduced into the battery can 2 from the hole so that the internal pressure of the battery can rises at a rate of 0.1 MPa / second, The explosion-proof safety mechanism was activated. That is, the sealing plate 7 was broken by the first cutting blade. Then, the introduction of compressed air was continued after the operation of the explosion-proof safety mechanism, and the relationship between the elapsed time from the operation time of the explosion-proof safety mechanism and the pressure in the battery can 2 was examined. The battery can 2 used here is also for a bobbin-type lithium primary battery (for example, CR14250 type) having an outer diameter of 14.5 mm and a height of 45.0 mm. Moreover, the positive electrode mixture 3 that supports the side surface of the cylindrical battery can 2 was accommodated in the battery can 2 so that the battery can 2 itself did not swell.

  FIG. 5 shows the relationship between the elapsed time starting from the operation point of the explosion-proof safety mechanism and the pressure in the battery can 2. In FIG. 5, the pressure in the battery can 2, which is the vertical axis of the graph, is the pressure when the explosion-proof safety mechanism is activated in the sample using the sealing body 10 of the conventional cylindrical battery 1 (“conventional example” in the figure). Is shown as a relative value with 100%.

  As shown in the figure, in the sample ("Example" in the figure) sealed with the sealing body 10a used in the cylindrical battery 1a of the example, the region where the sealing plate 7 can be bent is narrower than the conventional example. Therefore, the pressure at which the explosion-proof safety mechanism operates is higher than in the conventional example. However, after the operation of the explosion-proof safety mechanism, the pressure in the battery can 2 quickly decreased with the passage of time, and reached an atmospheric pressure equilibrium state in about 12 seconds. On the other hand, in the sample of the conventional example, the pressure when the explosion-proof safety mechanism is activated is maintained even after 20 seconds, and the internal pressure is not effectively released. As described above, in the cylindrical battery 1a according to the embodiment, even when the pressure in the battery can 2 gradually increases, the pressure is reliably and promptly released if the explosion-proof safety mechanism is activated. can do.

=== Ease of manufacturing ===
By the way, the terminal plates (8, 8a) of the cylindrical batteries (1, 1a) shown in FIGS. 1 and 3 are usually produced by pressing a disk-shaped metal plate. In the terminal plate 8a of the cylindrical battery 1a of the present embodiment, notches to be the first and second cutting blades (85, 85a) are formed in a disk-shaped metal plate, and the center of the terminal plate 8a is formed thereon. A cup with a flange portion 81 is formed by pressing with a punch having a predetermined diameter. Therefore, if a notch that becomes the second cutting edge 85a is formed inside the diameter of the punch, that is, the inner diameter φ3 of the bottom 82 of the terminal plate 8a shown in FIG. 3B (φ3> φ2), The tip of the second cutting blade 85a is bent upward. Therefore, after forming a disk-shaped metal plate in a cup shape, it is necessary to form the notch used as the 2nd cutting blade 85a in the peripheral side surface 87 of the terminal board 8a by a post process. This complicates the manufacturing process of the terminal plate 8a and may increase the manufacturing cost of the cylindrical battery 1a. Therefore, as shown in FIG. 3, if the terminal plate 8a is formed such that the tip position of the second cutting blade 85a is outside the inner diameter φ3 of the bottom portion 82 (φ3 <φ2), the flange portion 81 A cutout 83a is formed over the peripheral side surface 87, and a tongue piece formed by the cutout 83a only needs to be bent. The terminal plate 8a in the tubular battery 1a of the embodiment is replaced with the terminal plate 8 of the conventional tubular battery 1. It can be manufactured at a low cost by almost the same procedure.

=== Other Embodiments ===
In the above embodiment, the second cutting blades 85a are formed at eight positions at equal angular intervals. However, the second cutting blades only need to be present at a plurality of positions at equal angular intervals. Even if 85a is formed, the tip of the second cutting blade 85a contacts the sealing plate 7 earlier than the tip of the first cutting blade as the internal pressure increases. And the contact location is inward from the contact area | region of the flange part 81 and the sealing board 7. FIG. Therefore, the internal pressure can be quickly released in the same manner as the operation shown in FIG. Of course, even if the internal pressure further increases, the second cutting blade 85a breaks the sealing plate 7, so that neither the ejection of contents nor the scattering of parts occurs.

  As for the upper limit of the number of second cutting blades 85a, the larger the number, the closer the tip of the second cutting blade 85a comes into contact with the sealing plate 7 in a circular shape, and the sealing plate 7 is bent. Bias is less likely to occur. As a result, the pressure variation at which the explosion-proof safety mechanism operates is more uniform. On the other hand, the strength of the terminal plate 8a is reduced, and the manufacturing cost is also increased by providing more second cutting blades 85a. Therefore, the number of the second cutting blades 85a may be set as appropriate according to the strength of the terminal plate 8a, the manufacturing cost, and the like.

  The cylindrical battery 1a according to the above embodiment was a bobbin-type lithium primary battery. Of course, the cylindrical battery according to the embodiment has a spiral type lithium as long as the structure and structure of the sealing body are the same as those of the embodiment. It may be a primary battery, another type of battery (such as an alkaline battery) having a different power generation principle, a secondary battery, or the like. The embodiment according to the present invention can also be applied to, for example, a battery in which a circular opening is formed on the end face of a rectangular tube-shaped battery can.

1 cylindrical battery (bobbin-type lithium primary battery), 2 battery cans, 3 positive electrode mixture,
4 negative lithium, 5 separator, 7 sealing plate, 8, 8a terminal plate,
9 Sealing gasket, 10, 10a Sealing body, 70, 70a Broken part (hole),
81 flange of terminal plate, 82 bottom of terminal plate, 83, 83a notch,
84, 84a The base end of the notch, 85 cutting blade (first cutting blade), 85a second cutting blade,
86 exhaust port, 87 peripheral surface of terminal board, 88 vent hole

Claims (2)

A power generation element is housed in a bottomed cylindrical metal battery can that opens in a circular shape upward, and a sealing body is fitted to the opening of the battery can via a resin sealing gasket. Is a sealed cylindrical battery,
The sealing body is made of a metal, and is composed of a cup-shaped terminal plate in which a hollow disk-shaped flange portion is formed at the edge of a circular opening, and a disk-shaped sealing plate made of a thin metal plate, While the terminal plate is disposed with the bottom portion facing upward, the sealing plate is disposed below the terminal plate in a state of contacting the lower surface of the flange portion,
The terminal plate includes a first cutting blade and an exhaust port formed in the bottom portion, and is provided at a plurality of positions at equiangular intervals on a circumferential side surface that is connected to the flange portion while being suspended downward from a peripheral edge of the bottom portion. A second cutting blade and a vent hole formed,
The first cutting blade is formed by bending a tongue piece cut away leaving one side as a base end downward toward the inside of the battery can at the base end,
The first exhaust port is opened as a mark that forms the first cutting blade,
The second cutting blade has a tongue piece that is cut out with one side along the circumference of the boundary between the flange portion and the peripheral side surface of the terminal plate as a base end at the base end of the battery can. Folded diagonally downward toward the inside,
The vent hole is opened as a mark forming the second cutting blade,
The tip of the second cutting blade is below the tip of the first cutting blade,
A cylindrical battery characterized by that.   2. The cylindrical battery according to claim 1, wherein a tip of the second cutting blade is located on an outer side of an inner periphery of the bottom portion when viewed from above and below.

Images