JP5358194B2 - Cylindrical battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent breakage and firing of a cylindrical battery even when the internal pressure of the battery rises at an abnormal rate. <P>SOLUTION: The cylindrical battery 1a includes an upwardly-opened bottomed cylindrical metallic battery can 11 housing generation elements (21-23); and a sealing body 30a fitted to the opening of the can through a gasket 34 to seal the can. The sealing body includes a dish-like terminal plate 31a with the bottom surface upward, and a disk-like sealing plate 32 disposed below the terminal plate. The bottom surface 44 of the terminal plate includes a cutting edge 41 formed by bending a tongue piece formed by a V-shaped cutout 40 inside the battery can and an exhaust port 42 by the cutout part. A top end 47 of the cutting edge is located adjacently to the upper surface of the sealing plate so that it pierces the sealing plate when the sealing plate expands upward according to the rise of internal pressure in the battery can. The dish-like terminal plate includes a plurality of slit-like holes 50a formed to extend from the exhaust port to a peripheral part 46 of the bottom surface. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

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

  A typical example of a cylindrical battery that is an object of the present invention is a manganese dioxide-lithium lithium battery (CR type battery) using manganese dioxide as a positive electrode active material and metal lithium as a negative electrode active material. FIG. 6 shows the structure of a conventional CR battery. (A) is a top view when the said battery 1 is seen from upper direction, (B) is dd arrow sectional drawing in (A). Moreover, (C) is an enlarged view of the DD arrow cross section in (A). The CR type battery 1b shown in the figure is a bobbin type, and is formed into a hollow cylindrical shape with a bottomed cylindrical positive electrode can 11 having an opening at the top, and a positive electrode active material such as manganese dioxide together with a conductive aid such as graphite. The positive electrode mixture 21, the cylindrical negative electrode lithium 22, the cylindrical cup-shaped separator 23, and the sealing body 30 that also serves as a negative electrode terminal and hermetically seals the opening of the positive electrode can 11.

  The positive electrode can 11 is made of metal and serves as a battery case and a positive electrode current collector. On the lower bottom surface, a positive electrode terminal portion 12 that is convex outward is formed by pressing. Then, the positive electrode mixture 21, the separator 23, and the negative electrode lithium 22 are sequentially loaded in the positive electrode can 11, and the beading portion 10 is processed and formed around the opening to form a hollow cylindrical electrode body. Has been.

  The negative electrode lithium 22 is a rolled metal lithium plate, and one end of the negative electrode lead 33 is attached to a part of the negative electrode lithium 22 in advance. The negative electrode lead 33 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 inside (battery inside) of a disc-shaped sealing plate 32 made of a metal thin plate such as stainless steel constituting the sealing body 30. The sealing body 30 includes the sealing plate 32 and a negative electrode terminal plate 31 made of a metal such as stainless steel. The negative electrode terminal plate 31 has a dish shape having a flange around it, and is laminated with the sealing plate 32 in a state where the bottom surface is faced up and the dish is turned down to constitute the sealing body 30.

  The positive electrode can 11 is filled with a non-aqueous electrolyte (not shown), and the sealing body 30 is mounted together with the gasket 34 inside the opening of the positive electrode can 11 with the beading portion 10 as a seat, and the positive electrode can 11. The opening is fitted into the positive electrode can 11 by caulking (curling) inward.

  By the way, in the battery 1 having the above structure, a substantially V-shaped notch 40 is defined on the bottom surface 44 of the dish-shaped negative electrode terminal plate 31, and a tongue piece formed by the notch 40 is positive at the base end 49. The can 11 is bent inward. Thereby, the tongue piece becomes a cutting blade 41 having a sharp tip 47. The tip 47 is close to the sealing plate 32. In addition, by forming the cutting edge 41 on the bottom surface 44 of the negative electrode terminal plate 31, an acute-angled triangular hole (exhaust port) 43 that communicates the inside and the outside is opened.

  A small hole (a vent hole) 43 that communicates the inside and outside of the negative electrode terminal plate 31 is formed on a wall surface (peripheral surface) 45 with the periphery 46 of the bottom surface 44 of the dish-shaped negative electrode terminal plate 31 as an edge. The sealing plate 32 and the cutting edge 41 operate as an explosion-proof safety mechanism when gas is generated inside the battery 1 due to overdischarge or forced charging due to misuse of the battery 1 and the internal pressure rises. The exhaust port 42 serves as a passage (exhaust passage) for connecting the inside and outside of the positive electrode can 11 to discharge the gas to the outside. The vent hole 43 serves as an auxiliary exhaust passage.

  The operation of the explosion-proof safety mechanism in the conventional bobbin type battery 1 will be specifically described. First, the sealing plate 32 swells upward as the internal pressure rises, and the tip 47 of the cutting blade 41 pierces the sealing plate 32 and the sealing plate 32 Make a hole in. Thereby, a path (exhaust path) from this hole to the exhaust port 43 is formed, and the gas inside the battery 1 escapes to the outside. A part of the gas is exhausted outside through an exhaust path from the hole to the vent hole 43. In this way, the battery 1 can be prevented from bursting.

  In the conventional cylindrical battery, when the internal pressure in the battery can explosively rises at an unexpected speed, the sealing plate is torn when the cutting blade pierces the sealing plate. Then, the cut sealing plate may expand so as to be greatly bent toward the exhaust port, and the expanded portion may block the exhaust port. FIG. 7 shows the operating state of the explosion-proof safety mechanism when such an explosive internal pressure rises. In this figure, the expanded sectional view of the sealing body 30 is shown. First, when gas is generated in the positive electrode can (battery can) 11 and the internal pressure rises, the sealing plate 32 expands upward, contacts the tip 47 of the cutting blade 41, and a hole 35 is opened in the sealing plate 32 (A). If the generation of gas is explosive, the sealing plate 32 is divided from the hole 35 with the cutting edge 41 as a boundary. Then, without being exhausted to the outside through the exhaust port 42, the divided sealing plate 32 is bent toward the exhaust port 42 at a stretch using the peripheral portion of the disk fitted to the positive electrode can 11 as a fulcrum, Stick to the back side 48 of the bottom surface 44. As a result, the largest exhaust passage is blocked (B). When such an explosive internal pressure rises, solids such as positive electrode mixture and separator fragments are also ejected. Therefore, even if the exhaust port 42 is not completely blocked by the sealing plate 32, it remains in the exhaust port 42. This solid matter concentrates in a slight gap, and the exhaust port 42 is completely blocked. Of course, the vent hole 43 having a small diameter is also blocked.

  In such a state, as indicated by an arrow 60, the gas generated in the battery is eventually guided above the sealing plate 32 from the hole 35 formed in the sealing plate 32 by the cutting blade 41, and eventually. Only the space (halftone dot portion) 36 between the terminal plate 31 and the sealing plate 32 having no exhaust passage is used as a buffer region, and a further increase in internal pressure cannot be suppressed. As a result, there is a possibility of a very dangerous situation where the battery bursts or ignites.

  Therefore, even if the gas explosively occurs in the battery and the pressure in the battery can rises at an unexpected abnormal speed, the present invention reliably releases the internal pressure to the outside of the battery, It aims at providing the cylindrical battery provided with the advanced safety mechanism which prevents ignition.

  In order to achieve the above object, the present invention is characterized in that a power generation element is housed in a bottomed cylindrical metal battery can that opens upward, and a sealing member is fitted to the opening of the battery can via a gasket. A cylindrical battery in which the battery can is sealed, and the sealing body includes a metal dish-shaped terminal plate with the upper surface as a bottom surface, and a disk-shaped metal disposed below the terminal plate. The plate-like terminal plate is bent so that a tongue piece formed by a substantially V-shaped notch on the bottom surface is erected in a substantially vertical direction inside the battery can. And a substantially triangular opening formed on the trace of the cutting blade as an exhaust port, and the tip of the cutting blade is close to the upper surface of the sealing plate to increase the internal pressure in the battery can. When the sealing plate is expanded upward, the sealing plate penetrates. Is configured so that, on the bottom surface of the dish-shaped terminal plate was a cylindrical battery with a slit-shaped opening extending towards the periphery of the bottom surface from the exhaust port is formed at least one.

  Alternatively, it may be a cylindrical battery in which at least one linear groove extending from the exhaust port toward the peripheral edge of the bottom surface is formed on the inner surface of the battery on the bottom surface of the dish-shaped terminal plate. And in the said plate-shaped terminal board, the vent hole which connects the front and back of the said terminal plate is drilled in the peripheral surface which forms the side wall surface of the said dish, and the said vent hole is arrange | positioned in the extension direction of the said groove | channel. It is more preferable to use a cylindrical battery. Further, the groove may extend to the peripheral surface, and the vent hole may be open to the bottom on the tip side of the groove.

  According to the cylindrical battery of the present invention, even if the internal pressure rises at an unexpected abnormal speed, the internal pressure can be surely released to the outside of the battery, and the battery can be prevented from bursting or firing. Can be secured. In addition, the extremely high safety can be achieved only by changing the structure of the terminal board. When manufacturing the battery, no separate parts or processes are required, and the increase in manufacturing cost can be suppressed to a very low level.

1 is a structural diagram of a cylindrical battery in a first embodiment of the present invention. It is the figure which showed the structure of the sealing body in the said 1st Example, and the operation principle of an explosion-proof safety mechanism. It is a block diagram of the terminal board in other embodiment of the said 1st Example. It is the figure which showed the structure of the sealing body in the 2nd Example of this invention, and the operation principle of an explosion-proof safety mechanism. It is the figure which showed the structure of the sealing body in the 3rd Example of this invention, and the operation principle of an explosion-proof safety mechanism. It is a structural diagram of a conventional cylindrical battery. It is a figure which shows the state which the explosion-proof safety mechanism in the conventional cylindrical battery operate | moved incompletely.

  The basic structure of the cylindrical battery in the embodiment of the present invention is substantially the same as that of the conventional bobbin battery 1 shown in FIG. 6, and a power generation element (21-21) is placed in a cylindrical metal positive electrode can 11 opened upward. 23) is accommodated, and the positive electrode can 11 is sealed by fitting the sealing body 30 into the opening. However, the battery of the present embodiment is provided with an extremely reliable explosion-proof safety mechanism that can surely exhaust the generated gas in the positive electrode can 11 against an explosive increase in internal pressure, which has been a problem in conventional batteries. Yes.

=== First Embodiment ===
FIG. 1 shows the structure of the cylindrical battery in the first embodiment of the present invention. (A) is a top view from above, (B) is a side sectional view, and shows a cross section taken along the line AA in (A). The battery 1a according to this embodiment has the same basic configuration as that of the conventional battery 1, except that a slit-like hole 50a is defined in the bottom surface 44 of the dish-shaped negative electrode terminal plate 31a. It is different from the battery 1. In this example, three slit-shaped holes 50a extending radially from the exhaust port 42 toward the peripheral edge 46 of the bottom surface 44 of the negative electrode terminal plate 31a are formed.

  FIG. 2 shows the operation of the explosion-proof safety mechanism in the first embodiment. (A) is the top view which looked at the sealing body 30a from upper direction, (B) is the aa arrow directional cross-sectional view in (A). When gas is explosively generated inside the battery 1a, the sealing plate 32 expands upward almost instantly, and the tip 47 of the cutting blade 41 opens the hole 35 therein. However, unlike the conventional battery 1, the plurality of slit-shaped holes 50a are sufficiently opened as exhaust passages, and the gas can be exhausted at a speed commensurate with the increasing speed of the internal pressure. For example, even if a part of the sealing plate 32 sticks to the back side 48 of the bottom surface 44 of the negative electrode terminal plate 31a, the bottom surface 44 of the terminal plate 31a extends from the exhaust port 43 at the substantially center of the bottom surface 44 to the peripheral edge 46. Since a plurality of slit-shaped holes 50a are formed, any one of the exhaust passages 43 and the slit-shaped holes 50a survives. Even if a part of the slit-shaped hole is covered with the sealing plate 31, a part of the slit-shaped hole 50a, particularly, the vicinity of the peripheral edge 46 of the bottom surface 44 of the terminal plate 31a survives as an exhaust passage. Thereby, an exhaust path 60a for quickly exhausting the gas is secured, and the battery 1a can be prevented from being ruptured or ignited.

  Here, the performance of the explosion-proof safety mechanism was compared between the conventional cylindrical battery 1 and the cylindrical battery 1a in the first embodiment. In the comparison, the cylindrical battery (invention product) 1a in the first embodiment shown in FIG. 1 and the conventional cylindrical battery (conventional product) 1 shown in FIG. 6 were prepared as samples. The size was a CR8 type, and the inventive product 1a and the conventional product 1 all had the same structure except for the presence or absence of slit-like holes 50a in the negative electrode terminal plates (31a, 31). The plate-shaped negative electrode terminal plates (31a, 31) are made of stainless steel having a thickness of 0.4 mm, and air holes 43 having a diameter of about 0.5 mm are formed at two opposite positions on the peripheral surface 45 of the plate. It has been drilled. Moreover, the slit-shaped hole 50a in the invention has a width of 1 mm and extends to the peripheral edge 46 of the bottom surface 44 of the negative electrode terminal plate 31a.

  And the forced overdischarge test was done about the said invention product 1a and the conventional product 1. FIG. In the test, first, each sample was discharged at a constant current of 1 mA to a nominal capacity of 2,600 mAhr to obtain a fully discharged product. Next, a time when a current of 20 mA, 30 mA, and 40 mA is supplied by a 12 V power source to cause forced overdischarge and the nominal capacity is divided by each current value is 2600/20 = 130 h, 2600 / 30≈87 h, 2600/40 = The time after 65 hours is the discharge completion time. Each sample was allowed to stand at room temperature for 7 days from the completion of the discharge. The test result was determined by the presence or absence of rupture / ignition during this standing period. In the test, five samples were prepared for both the inventive product 1a and the conventional product 1 for each of the three current values under the forced overdischarge condition.

Table 1 shows the test results.

  In the samples forcibly discharged at 20 mA and 30 mA after complete discharge, the invention product 1a and the conventional product 1 were not ruptured or ignited in all five samples. However, in the sample subjected to forced overdischarge at 40 mA, which is an extremely extreme condition, four of the five samples of the conventional product 1 burst and ignited. On the other hand, in the invention product 1a, no bursting deterioration occurred in all samples. Therefore, it was confirmed that the cylindrical battery 1a in the first example of the present invention has extremely high safety.

=== About the number of slits and the aperture ratio ===
Unlike the general dry battery, the cylindrical battery (1, 1a) shown as the conventional example or the first embodiment has a lead terminal attached to the bottom surface 44 of the negative electrode terminal plate (31, 31a) by spot welding or the like. In many cases, it is used in the Therefore, in the cylindrical battery 1a in the first embodiment, in addition to the exhaust port 42 which is a trace of the cutting blade 41, the slit-shaped hole 50a is formed in the negative terminal plate 31a. If the number is increased or the opening area of the slit-shaped hole 50a is increased, there is no place to attach the lead terminal. Further, if the number of slit-like holes 50a is too large or the opening area is too large, the strength of the negative electrode terminal plate 31a is lowered. Therefore, when forming the slit-shaped holes 50a, it is necessary to set the number and aperture ratio in consideration of the mounting location and strength of the lead terminals.

  In the experiment, even when five slit-like holes 50a are formed like the terminal plate 31a-2 shown in FIG. 3 and about 30% of the area of the bottom surface 44 of the negative electrode terminal plate 31a-2 is opened, the lead terminal It was possible to attach the material, and the strength was not a problem in practice. When the cutting blade 41 makes a hole in the sealing plate 32 due to the increase in internal pressure, a large force is applied to the base end 49 of the cutting blade 41. Therefore, the base end 49 of the cutting blade 41 needs a certain width. In the example shown in FIGS. 1 to 3, one slit-shaped hole 51 among the plurality of slit-shaped holes 50 a is not connected to the exhaust port 42, and is cut out in a long and narrow rectangular shape. Thereby, the width of the base end 49 is secured. In addition, although it is more preferable that there are a plurality of slit-like holes 50a, one may be sufficient, and the exhaust path 60a can be secured as long as one of the slit-shaped holes 50a communicates with the exhaust port.

=== Second Embodiment ===
FIG. 4 shows the structure of the sealing body 30b in the cylindrical battery according to the second embodiment of the present invention together with the operation principle of the explosion-proof safety mechanism. (A) is a top view when the said sealing body 30 is seen from upper direction, (B) is a bb arrow directional cross-sectional view in (A). In the second embodiment, instead of the slit-like hole 50a in the first embodiment, a groove 50b communicating with the exhaust port 42 is formed on the back side 48 of the bottom surface 44 of the negative electrode terminal plate 31b. In the illustrated example, the planar shape of the groove 50b is the same as the slit-shaped hole 50a in the negative electrode terminal plate 31a in the first embodiment, and the peripheral edge 46 of the bottom surface 44 of the negative electrode terminal plate 31b from the exhaust port 42 with a width of about 1 mm. Three of them are formed radially toward the surface. And with respect to the thickness of the terminal board 31b of 0.4 mm, the depth of the groove 50b is 0.15 mm.

  In the second embodiment, the exhaust passage at the time of gas generation is the same exhaust port 42 and vent hole 43 as the conventional battery 1. Therefore, when gas is explosively generated, the sealing plate 32 covers the exhaust port 42 as in the conventional battery 1. However, in the second embodiment, since the groove 50b communicating with the exhaust port 42 is formed, the gas ejected from the hole 35 opened in the sealing plate 32 by the cutting blade 41 toward the bottom surface 44 of the terminal plate 31b It is guided to the exhaust port 42 through a groove 50 b formed on the back side 48 of the bottom surface 44. That is, even if the sealing plate 32 covers the entire opening surface of the exhaust port 42, the gas exhaust path 60b is secured. Thereby, the possibility of rupture and ignition can be made extremely low. Actually, when the above-mentioned forced overdischarge test was actually conducted using a CR8 type battery in which the negative electrode terminal plate 31a in the first embodiment was changed to the terminal plate 31b in the second embodiment as a sample, In the forced overdischarge test, there were no samples that burst or ignited.

=== Third embodiment ===
In the second embodiment, the vent hole 43 is formed as an auxiliary exhaust passage as in the conventional battery 1. The third embodiment of the present invention is an embodiment in which exhaust is promoted by actively utilizing the vent holes 43. FIG. 5 shows the structure of the sealing body 30c of the cylindrical battery in the third embodiment together with the operating principle of the explosion-proof safety mechanism. (A) is a top view of the sealing body 30, (B) is side sectional drawing, and has shown the cc arrow cross section in (A). (C) is a modification of the third embodiment, and shows a side sectional view of the sealing body 32.

  In the third embodiment, a radial groove 50b is formed on the back side 48 of the bottom surface 44 of the negative electrode terminal plate 31c, as in the second embodiment. However, the third embodiment is different in that the vent hole 43 is arranged in the extending direction of the groove 50b. By adopting such a configuration, the gas filled in the space 36 between the sealing plate 32 and the terminal plate 31c is guided to the groove 50c as well as the vent hole 43 as in the exhaust path 60c shown in the drawing. When guided, the gas in the battery can can be discharged more quickly. Of course, as in the modification shown in (C), the groove 50c extends from the center of the bottom surface 44 of the plate-like terminal board 31c to the peripheral surface 46 via the bottom surface peripheral edge 45, and at the tip in the extending direction. The vent hole 43 may be disposed, and the vent hole 43 may be opened at the bottom on the tip side of the groove 50c.

1, 1a Cylindrical battery 11 Positive electrode can (battery can)
21 Positive electrode mixture 22 Negative electrode lithium 23 Separator 30, 30a-30c Sealing body 31, 31a, 31a-2, 31b, 31c Terminal plate 32 Sealing plate 34 Gasket 35 Hole 40 Notch 41 Cutting blade 42 Exhaust port 43 Vent hole 44 Terminal plate Bottom surface 45 peripheral surface of terminal board 50a slit-like hole 50b, 50c groove 60a-60c exhaust path

Claims (4)

A cylinder in which a power generation element is housed in a bottomed cylindrical metal battery can that opens upward, and a sealing body is fitted into the opening of the battery can via a gasket so that the battery can is sealed. Battery
The sealing body is composed of a metal dish-shaped terminal plate with the upper surface as a bottom surface, and a sealing plate made of a disk-shaped metal thin plate disposed below the terminal plate,
The dish-shaped terminal plate includes a cutting blade formed by bending a tongue piece formed by a substantially V-shaped notch on a bottom surface so as to be erected in a substantially vertical direction inside the battery can. With a substantially triangular opening of the trace that formed
The tip of the cutting blade is close to the upper surface of the sealing plate, and is configured to penetrate the sealing plate when the sealing plate expands upward as the internal pressure increases in the battery can,
At least one or more slit-like holes extending from the exhaust port toward the peripheral edge of the bottom surface are formed on the bottom surface of the dish-shaped terminal plate. A cylindrical shape in which a power generation element is housed in a bottomed cylindrical metal battery can that opens upward, and the battery can is sealed by fitting a sealing body through a gasket to the opening of the battery can. A battery,
The sealing body is composed of a metal dish-shaped terminal plate with the upper surface as a bottom surface, and a sealing plate made of a disk-shaped metal thin plate disposed below the terminal plate,
The dish-shaped terminal plate includes a cutting blade formed by bending a tongue piece formed by a substantially V-shaped notch on a bottom surface so as to be erected in a substantially vertical direction inside the battery can. With a substantially triangular opening of the trace that formed
The tip of the cutting blade is close to the upper surface of the sealing plate, and is configured to penetrate the sealing plate when the sealing plate expands upward as the internal pressure increases in the battery can,
At least one or more linear grooves extending from the exhaust port toward the peripheral edge of the bottom surface are formed on the inner surface of the battery on the bottom surface of the dish-shaped terminal plate.   In the dish-shaped terminal plate, a vent hole communicating the front and back of the terminal plate is formed on the peripheral surface forming the side wall surface of the dish, and the vent hole is disposed in the extending direction of the groove. The cylindrical battery according to claim 2.   4. The cylindrical battery according to claim 3, wherein the groove extends to the peripheral surface, and the air hole is opened at a bottom of the groove on the tip side.

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