JP6890028B2 - Cylindrical battery - Google Patents

Description

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

An example of a tubular battery to which the present invention is intended is a bobbin-type lithium primary battery provided with a bottomed cylindrical battery can. FIG. 1 shows the structure of the bobbin-type lithium primary battery (hereinafter, also referred to as a tubular battery 1). In the following, assuming that the direction of the cylindrical shaft 100 of the bottomed cylindrical battery can 2 is the vertical direction and the bottom of the battery can 2 is the downward direction, each of the vertical directions is defined. Is a vertical cross-sectional view taken along the cross section including the cylindrical shaft 100, and FIG. 1B is a plan view of the cylindrical battery 1 when viewed from above. FIG. 1C is a cross-sectional view taken along the line bb in FIG. 1A, and here, the upper end side of the tubular battery 1 is enlarged and shown. Note that FIG. 1 (A) corresponds to the cross section taken along the line aa in FIG. 1 (B).

As shown in FIG. 1A, the illustrated tubular battery 1 resembles a ring core in which a bottomed cylindrical battery can 2 having an opening at the top and a positive electrode active material such as manganese dioxide are combined with a conductive auxiliary agent such as graphite. It is composed of 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 seals the opening of the battery can 2. .. The battery can 2 is filled with a non-aqueous electrolytic solution.

The battery can 2 is made of metal and also serves as a battery case and a positive electrode current collector. The terminal portion 21 of the positive electrode is formed on the lower bottom surface so as to protrude outward by press working. Further, a beading portion 22 is formed by drawing processing around the vicinity of the opening. Then, the positive electrode mixture 3 is press-fitted into the battery can 2, and the negative electrode lithium 4 is arranged inside the hollow cylindrical positive electrode mixture 3 via the separator 5.
One end of the negative electrode lead 6 which is formed of a strip-shaped thin metal plate and also serves as a negative electrode current collector is attached to the negative electrode lithium 4. The other end is spot-welded to the lower surface of a disk-shaped sealing plate 7 made of a thin metal plate such as stainless steel that constitutes the sealing body 10. The sealing body 10 is composed of the sealing plate 7 and a negative electrode terminal plate 8 made of a metal such as stainless steel. The terminal plate 8 has a cup shape in which a hollow disk-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 face down cup. Has been done.

The sealing body 10 is mounted with the beading portion 22 as a seat inside the opening of the battery can 2 together with the resin sealing gasket 9, and the upper end portion of the battery can 2 above the beading portion 22 is caulked inward. It is fitted to the battery can 2 by being (curled).

As shown in FIG. 1 (B), in the tubular battery 1 having the above structure, a substantially V-shaped notch 83 is defined at substantially the center of the bottom 82 of the cup-shaped terminal plate 8, and the notch 83 is formed. A tongue piece having a side end 84 connecting the ends of the tongue is bent downward at the base end 84. As a result, the tongue piece becomes a cutting edge 85 having a sharp tip. By forming the cutting edge 85 at the bottom 82 of the terminal plate 8, an acute-angled triangular hole (exhaust port) 86 that connects the inside and the outside is opened. Further, as shown in FIG. 1C, the inside and outside of the terminal plate 8 are communicated to the wall surface (peripheral side surface) 87 that is vertically hung downward from the peripheral edge of the bottom portion 82 of the terminal plate 8 and reaches the flange portion 81. Small holes (vent holes) 88 are formed.

The sealing plate 7 and the cutting edge 85 operate as an explosion-proof safety mechanism when gas is generated inside the tubular battery 1 and the internal pressure rises due to over-discharging or charging due to misuse of the tubular battery 1. The exhaust port 86 serves as a passage (exhaust passage) for communicating the inside and outside of the battery can 2 and discharging gas to the outside, and the ventilation hole 88 plays a role as an auxiliary exhaust passage.

FIG. 2 shows the operation of the explosion-proof safety mechanism in the tubular battery 1 shown in FIG. FIG. 2A shows the state of the sealing body 10 when the internal pressure rises, and FIG. 2B is a view 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 of φ1 that is not in contact with the lower surface of the flange portion 81 of the terminal plate 8 bulges upward. Then, as shown in FIG. 2B, when the sealing plate 7 further swells upward, the tip of the cutting blade 85 pierces the sealing plate 7 and makes 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 tubular battery 1 escapes to the outside. A part of the gas is exhausted to the outside through an exhaust path from the hole 70 formed in the sealing plate 7 to the ventilation 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 exploding. The pressure at which the explosion-proof safety mechanism operates is set to be about 2.5 MPa to 3.5 MPa in, for example, a CR17450 type bobbin-type lithium primary battery.

The following Patent Document 1 describes a tubular battery provided with an explosion-proof safety mechanism in which a hole is made in the sealing plate by a cutting edge. Further, Non-Patent Document 1 below describes a bobbin-type lithium primary battery provided with an explosion-proof safety mechanism having the same structure.

Japanese Unexamined Patent Publication No. 2010-186650

FDK Corporation, "High-capacity cylindrical lithium primary battery", [online], [Search on February 9, 2017], Internet <URL: http://www.fdk.co.jp/battery/lithium/lithium_cylindrical .html ＞

In the explosion-proof safety mechanism of a conventional tubular battery, when the pressure inside the battery can rises sharply, the cutting edge breaks the sealing plate and the explosion-proof safety mechanism itself operates, but the broken part 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 released quickly. If the increase in internal pressure is explosive, the contents of the battery and the parts that make up the battery (sealing body, lead terminals, etc.) may scatter.

In addition, when the pressure inside the battery can rises at a slow speed, the speed at which the sealing plate bends also slows down, and even if the explosion-proof safety function is activated and the tip of the cutting blade pierces the sealing plate, it cuts. The blade may gradually bite into the sealing plate, and the cutting blade itself may become like a plug that closes the broken part. Even in such a case, the internal pressure of the battery can cannot be released promptly. Further, the pressure continues to increase until the cutting edge bites deeply into the sealing plate and the sealing plate is torn, and when the sealing plate is torn, the contents may be ejected at once from the torn opening.

Therefore, an object of the present invention is to provide a tubular battery capable of reliably and promptly releasing the internal pressure after the explosion-proof safety mechanism is activated.

One aspect of the present invention for achieving the above object is that the power generation element is housed in a bottomed tubular metal battery can that opens circularly upward, and a resin seal is opened in the opening of the battery can. A tubular battery in which a sealing body is fitted via a gasket and the battery can is sealed.
The sealing body is made of metal, and is composed of a cup-shaped terminal plate in which a hollow disk-shaped flange portion is formed on the edge of a circular opening, and a disk-shaped sealing plate made of a thin metal plate. While the terminal plate is arranged with the bottom portion facing upward, the sealing plate is arranged below the terminal plate in a state where the sealing plate is in contact with the lower surface of the flange portion.
The terminal plate is provided with a first cutting edge and an exhaust port formed on the bottom portion, and is vertically provided downward from the peripheral edge of the bottom portion at a plurality of locations on the peripheral side surface connected to the flange portion at equal angular intervals. With a formed second cutting edge and vents,
In the first cutting edge, a tongue piece cut out leaving one side serving as a base end is bent downward toward the inside of the battery can at the base end.
The exhaust port is opened as a trace of forming the first cutting edge.
In the second cutting edge, a tongue piece cut out from one side along the circumference of the boundary between the flange portion of the terminal plate and the peripheral side surface thereof is formed at the proximal end of the battery can. It is bent diagonally downward toward the inside,
The vent is opened as a mark of forming the second cutting edge.
The tip of the second cutting edge is below the tip of the first cutting edge.
It is a tubular battery that is characterized by this.

The tubular battery may be a tubular battery characterized in that the tip of the second cutting edge is on the outer side of the inner circumference of the bottom when viewed from the vertical direction.

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

It is a figure which shows an example of a tubular battery. It is a figure explaining the operation of the conventional explosion-proof safety mechanism in a tubular battery. It is a figure which shows the structure of the sealing body included in the tubular battery which concerns on embodiment of this invention. It is a figure explaining the operation of the explosion-proof safety mechanism in the tubular battery which concerns on Example. It is a figure which shows the performance of the explosion-proof safety mechanism in the tubular battery which concerns on Example.

Examples of the present invention will be described below with reference to the accompanying drawings. In the drawings used in the following description, the same or similar parts may be designated by the same reference numerals and duplicate description may be omitted. Depending on the drawing, unnecessary reference numerals may be omitted in the description.

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

As shown in FIG. 3A, the terminal plate 8a in the tubular battery 1a of the present embodiment is a cut formed by bending a triangular tongue piece formed by a V-shaped notch 83 at the bottom 82 downward. An exhaust port 86 opened by forming the blade 85 and the cutting blade 85 is formed. Further, a plurality of ventilation holes 88a are formed around the cylindrical shaft 100 at equal angular intervals 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 eight locations at intervals of 45 °. Further, each vent hole 88a has a base end 84a on one side along the circumference which is a boundary between the peripheral side surface 87 and the flange portion 81, and the tongue piece 85a formed by an upwardly convex V-shaped notch is bent. It is open because it was done.

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 ventilation holes 88a have a triangular tongue piece 85a formed by a notch 83a formed over the peripheral side surface 87 while having a base end 84a at the boundary thereof, and the triangular tongue piece 85a faces diagonally downward with the base end 84a as a folding line. It opens as a trace of being bent. Further, the tip of the tongue piece 85a is located below the tip of the cutting blade (hereinafter, also referred to as the first cutting blade 85) provided on the bottom portion 82. The tongue piece 85a is a cutting blade different from the first cutting blade 85 (hereinafter, also referred to as a second cutting blade 85a).

<Operation of explosion-proof safety mechanism>
FIG. 4 shows the operating state of the explosion-proof safety mechanism using the tubular battery 1a of this embodiment. FIGS. 4 (A) to 4 (C) show the transition of the operating state of the explosion-proof safety mechanism as the internal pressure rises, and here, only the sealing body 10a is shown. First, as shown in FIG. 4A, when the internal pressure rises, the sealing plate 7 bends upward. At this time, since the second cutting edge 85a is bent diagonally downward from the base end 84a toward the inside of the terminal plate 8a, the tip of the second cutting edge 85a is naturally formed by the sealing plate 7. It contacts the upper surface of the sealing plate 7 at a shallow angle at a position inward of the contact area between the upper surface and the lower surface of the flange portion 81 of the terminal plate 8a. Then, when the internal pressure further increases, the sealing plate 7 is restricted from bending upward by the second cutting edge 85a in contact with the upper surface of the sealing plate 7, and the area having a diameter of φ2 inside the contact area having a diameter of φ1 is restricted. 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 flexes upward rapidly and greatly. As a result, as shown in FIG. 3B, the first cutting edge 85 quickly breaks the sealing plate 7. That is, in the tubular battery of the embodiment, the time from when the first cutting edge 85 abuts on the sealing plate 7 until it breaks can be shortened, and the battery before the contents close the broken portion 70. The gas in the can can be released to the outside. Of course, even when the internal pressure gradually rises at a slow speed, the internal pressure rises rapidly when the second cutting edge 85a comes into contact with the sealing plate 7, so that the first cutting edge 85 quickly bites into the sealing plate 7. Thereby, it is possible to prevent the first cutting edge 85 itself from becoming a plug that closes the fractured portion 70. Even if the first cutting edge 85 closes the fractured portion 70 and the internal pressure further increases, as shown in FIG. 3C, the plurality of second cutting edges 85a form the sealing plate 7 at a plurality of locations. Break. Therefore, the internal pressure can be released before reaching a large internal pressure such that the contents are ejected or the parts are scattered. In addition, a plurality of systems of ventilation paths are secured by the plurality of fracture points 70a, the contents and the like are not concentrated in one place, and the ejection of the contents and the scattering of parts can be more reliably suppressed.

As described above, the tubular battery 1a of the present embodiment is characterized by the structure of the sealing body 10a, and when the explosion-proof safety mechanism operates, the internal pressure in the battery can 2 is surely and promptly released. It has become like.

=== Safety test ===
Next, the tubular battery 1a according to the present embodiment shown in FIG. 3 was prepared as a sample. Further, as a comparative example with respect to the examples, the conventional tubular battery 1 shown in FIG. 1 was also produced as a sample. The configurations and structures of the samples of Examples and Comparative Examples other than the sealing bodies (10a and 10) are the same as those of the tubular battery 1 shown in FIG. 1, and here, they correspond 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 tubular batteries (1a, 1) are misused in extremely harsh conditions, each sample is heated by a burner, and after the sample is completely discharged, a current of 1 A is further applied. A forced discharge test was conducted to discharge the battery, and an abnormal charge test was performed to charge the battery with a current of 15 mA based on the UL standard. In each test, 15 samples of 2 types corresponding to each of the examples and comparative examples were prepared. Then, 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 the internal pressure was examined.

The results of each test are shown in Table 1 below.

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 tubular battery 1a according to an embodiment, and sample 2 is a tubular battery 1 according to a comparative example. As shown in Table 1, in the sample 1 as an example, none of the 15 individuals had scattered contents or parts in all of the tests. On the other hand, in Sample 2, which is a comparative example, the contents or parts were scattered in 1, 2, and 1 of 15 individuals in each of the heating test, the forced discharge test, and the abnormal charge test. From the above, it was confirmed that the tubular battery according to the embodiment of the present invention has extremely high safety.

Next, in order to reproduce the situation in which the pressure inside the battery can 2 gradually increases, the opening of the battery can 2 is sealed with the same sealing body 10 as the conventional tubular battery 1 shown in FIG. A sample and a sample sealed with the sealing body 10a of the tubular battery 1a according to the example shown in FIG. 3 were prepared. Further, in each sample, a hole connecting the inside and the outside is formed in the battery can 2, 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 / sec. The explosion-proof safety mechanism was activated. That is, the sealing plate 7 was broken by the first cutting edge. Then, the introduction of compressed air was continued even after the explosion-proof safety mechanism was activated, and the relationship between the elapsed time from the time when the explosion-proof safety mechanism was activated and the pressure inside the battery can 2 was investigated. As the battery can 2, a battery can 2 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 was used. Further, the positive electrode mixture 3 that supports the side surface of the cylindrical battery can 2 is housed in the battery can 2 so that the battery can 2 itself does not swell.

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

As shown in the figure, in the sample sealed with the sealing body 10a used for the tubular battery 1a of the embodiment (“Example” in the figure), the region in which the sealing plate 7 can be bent is narrower than that of the conventional example. Therefore, the pressure at which the explosion-proof safety mechanism operates is higher than in the conventional example. However, after the explosion-proof safety mechanism was activated, the pressure inside the battery can 2 quickly decreased with the passage of time, and reached an equilibrium state with the atmospheric pressure 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 tubular battery 1a according to the embodiment, even when the pressure in the battery can 2 gradually rises, the pressure is surely and promptly released if the explosion-proof safety mechanism is activated. can do.

=== Ease of manufacture ===
By the way, the terminal plates (8, 8a) of the tubular 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 tubular battery 1a of the present embodiment, notches serving as first and second cutting blades (85, 85a) are formed in the disk-shaped metal plate, and the center of the terminal plate 8a is formed on the notches. It is press-processed with a punch having a predetermined diameter to form a cup shape having a flange portion 81. Therefore, when the diameter of the punch, that is, the notch forming the second cutting edge 85a is formed inside the inner diameter φ3 of the bottom 82 of the terminal plate 8a shown in FIG. 3 (B) (φ3> φ2), the second The tip of the cutting edge 85a of No. 2 bends upward. Therefore, it is necessary to form a notch to be the second cutting edge 85a on the peripheral side surface 87 of the terminal plate 8a in a post-process after forming the disk-shaped metal plate into a cup shape. Therefore, the manufacturing process of the terminal plate 8a becomes complicated, and the manufacturing cost of the tubular battery 1a may increase. Therefore, as shown in FIG. 3, if the terminal plate 8a is formed so that the tip position of the second cutting edge 85a is outside the inner diameter φ3 of the bottom portion 82 (φ3 <φ2), the flange portion 81 can be used. It is only necessary to form a notch 83a over the peripheral side surface 87 and bend the tongue piece formed by the notch 83a, and the terminal plate 8a in the tubular battery 1a of the embodiment is used with the terminal plate 8 of the conventional tubular battery 1. It can be produced inexpensively by almost the same procedure.

=== Other Examples ===
In the above embodiment, the second cutting blades 85a are formed at eight locations at equal angle intervals, but it is sufficient that the second cutting blades are at a plurality of locations at equal angle intervals, for example, the second cutting blades are formed at only two locations at 180 ° intervals. Even if the 85a is formed, the tip of the second cutting edge 85a comes into contact with the sealing plate 7 before the tip of the first cutting edge as the internal pressure increases. The contact point is inward from the contact area between the flange portion 81 and the sealing plate 7. 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 edge 85a breaks the sealing plate 7, so that the contents do not spurt out or the parts do not scatter.

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

The tubular battery 1a according to the above embodiment was a bobbin type lithium primary battery, but of course, the tubular battery according to the embodiment is a spiral type lithium if 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 having a different power generation principle (alkaline battery, etc.), a secondary battery, or the like. Further, the embodiment according to the present invention can be applied to, for example, a battery in which a circular opening is formed in the end face of a square tubular battery can.

1 Cylindrical battery (bobbin type lithium primary battery), 2 Battery can, 3 Positive electrode mixture,
4 Negative electrode lithium, 5 Separator, 7 Seal plate, 8,8a terminal plate,
9 Sealing gasket, 10,10a Sealing body, 70,70a Breaking point (hole),
81 terminal plate flange, 82 terminal plate bottom, 83, 83a notch,
84,84a Notch base end, 85 cutting edge (first cutting edge), 85a second cutting edge,
86 Exhaust port, 87 Terminal plate peripheral side, 88 Vent

Claims (2)

A power generation element is housed in a bottomed tubular metal battery can that opens in a circular shape upward, and a sealing body is fitted into the opening of the battery can via a resin sealing gasket. Is a sealed tubular battery
The sealing body is made of metal, and is composed of a cup-shaped terminal plate in which a hollow disk-shaped flange portion is formed on the edge of a circular opening, and a disk-shaped sealing plate made of a thin metal plate. While the terminal plate is arranged with the bottom portion facing upward, the sealing plate is arranged below the terminal plate in a state where the sealing plate is in contact with the lower surface of the flange portion.
The terminal plate is provided with a first cutting edge and an exhaust port formed on the bottom portion, and is vertically provided downward from the peripheral edge of the bottom portion at a plurality of locations on the peripheral side surface connected to the flange portion at equal angular intervals. With a formed second cutting edge and vents,
In the first cutting edge, a tongue piece cut out leaving one side serving as a base end is bent downward toward the inside of the battery can at the base end.
The exhaust port is opened as a trace of forming the first cutting edge.
In the second cutting edge, a tongue piece cut out from one side along the circumference of the boundary between the flange portion of the terminal plate and the peripheral side surface thereof is formed at the proximal end of the battery can. It is bent diagonally downward toward the inside,
The vent is opened as a mark of forming the second cutting edge.
The tip of the second cutting edge is below the tip of the first cutting edge.
Cylindrical battery characterized by that. The tubular battery according to claim 1, wherein the tip of the second cutting edge is on the outer side of the inner circumference of the bottom when viewed from the vertical direction.

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