JP5877724B2 - Sealing body for sealed battery, sealed battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sealed battery sealing body provided with a PTC element having a current protection function, a sealed battery equipped with the sealing body, and a manufacturing method thereof.

  Conventionally, an assembled battery is mounted as a power source for portable electric devices such as cameras and lights. In this type of battery pack, a plurality of batteries are connected in series to flow a large current, and a PTC (Positive Temperature Coefficient) element is used as a protective element (Patent Documents 1 and 2). Etc.). This PTC element usually has a low resistance, but its electrical resistance increases when a large current flows through the battery and the battery temperature rises. Therefore, if this PTC element is used, even if a circuit element or the like is short-circuited and a large current flows at the time of failure of the electric device, the battery current can be cut off.

  Moreover, in sealed batteries, such as a lithium primary battery, what sealed the battery by connecting a sealing body to the opening part of a battery can by laser welding is put into practical use. A conventional example of the sealing body 50 is shown in FIG. The sealing body 50 in FIG. 6 includes a sealing plate 51, a negative electrode terminal 54 attached to the central hole 52 of the sealing plate 51 via a resin packing 53, and a washer 55 for fixing the negative electrode terminal 54. Yes. In this sealing body 50, the negative electrode terminal 54 is sealed while maintaining the hermeticity by compressing the resin packing 53 by crimping the negative electrode terminal 54 by a rivet method with the washer 55 fitted in the lower end portion of the negative electrode terminal 54. It is fixed to the plate 51. Then, the battery is sealed by fitting the sealing body 50 into the opening of the battery can and laser welding the outer peripheral portion of the sealing plate 51.

  In Patent Documents 1 and 2 described above, a PTC element of a type externally attached to a battery terminal is disclosed. On the other hand, the present inventors are considering a product in which a PCT element is incorporated in a laser sealing type sealing body. A specific example is shown in FIG. In the sealing body 60 shown in FIG. 7, a disc-shaped PCT element 63 is disposed on a flange portion 62 provided at the upper end of the negative electrode terminal 61. Further, a cap member 64 is mounted so as to surround the PTC element 63, and the PCT element 63 is fixed by sandwiching the PTC element 63 between the cap member 64 and the flange portion 62.

JP 2000-340192 A Japanese Utility Model Publication No. 1-81870

  By the way, in the sealing body 60 having the configuration shown in FIG. 7, a large load is applied to the negative electrode terminal 61 when the negative electrode terminal 61 is caulked by the rivet method. For this reason, when the PCT element 63 is mounted on the upper part of the negative electrode terminal 61, the component strength cannot be maintained sufficiently. Moreover, if the compressive force at the time of caulking the negative electrode terminal 61 is weakened so that the PCT element 63 is not broken, sufficient component accuracy for maintaining the sealing performance cannot be obtained. For this reason, it is considered difficult to manufacture the sealing body 60 including the PTC element 63 as shown in FIG.

  This invention is made | formed in view of said subject, The objective is to provide the sealing body for sealed type batteries which can maintain a sealing performance fully while incorporating a PTC element. Another object is to provide a sealed battery that can be reliably sealed using a sealing body containing a PTC element. Furthermore, another object is to provide a method of manufacturing a sealed battery that can reduce manufacturing costs.

  Means [1] to [5] for solving the above problems are listed below.

  [1] A sealed battery sealing body that is attached to the opening by laser welding to seal the opening of the battery can, and is a metal that is provided to close the opening and has a through hole in the center. A sealing plate made of resin, a columnar terminal having a flange portion at one end which is fixed in the outer side of the can and fixed through a resin packing in a state of being inserted through the through hole of the sealing plate, and the flange A plate-like PTC element disposed in a part, a cap member whose outer peripheral end is bent so as to surround the PTC element, and the PTC element is sandwiched and fixed between the flange part, the cap member and the flange And a step formed between the outer peripheral end bent at the cap member and the flange portion is integrally formed with an insulating sheet interposed at a contact portion with the portion. Sealed battery for sealing body, characterized in that the are crowded filled.

  According to the invention described in Means 1, the sealing plate, the resin packing, the terminal, the PTC element, the cap member, and the insulating sheet are integrally formed. In this case, since it is not necessary to crimp the negative electrode terminal by the rivet method as in the prior art, the PTC element can be reliably incorporated in the sealing body without applying a large load to the PTC element. Further, since the step portion formed between the outer peripheral end bent in the cap member and the flange portion of the terminal is embedded in the resin packing, the length in the terminal axis direction can be shortened. Furthermore, since the contact area of the resin packing is increased in the sealing body, the sealing performance can be sufficiently improved. Moreover, since the sealing body of this invention does not need to use a washer like the case of the rivet system of a prior art, a number of parts reduces. Furthermore, the capacity in the battery can can be secured by the volume of the washer. For this reason, when the sealing body of this invention is used, the electrolyte solution and electrode active material in a battery can can be increased, and the discharge characteristic of a sealed battery can be improved.

  [2] The sealed battery sealing body according to [1], wherein the terminal is formed in a taper shape such that the diameter increases toward the end opposite to the flange portion.

  According to the invention described in the means 2, the tapered portion of the negative electrode terminal becomes a wedge and the negative electrode terminal is difficult to come out, and the component reliability of the sealing body is improved.

[3] In the means 1 or 2, the terminal is composed of the flange portion and a columnar portion other than the flange portion, and the columnar portion is formed to be non-circular when viewed in the axial direction. Sealing body for sealed battery characterized by the above.

According to the invention described in the means 3, since the columnar portion in the terminal is non-circular, the rotation of the terminal in the sealing body can be prevented, and the sealing performance is improved.

  [4] A sealed battery, wherein the opening of the battery can is sealed using the sealed battery sealing body according to any one of means 1 to 3.

  According to the invention described in the means 4, the opening of the battery can can be reliably sealed using the sealing body containing the PTC element.

  [5] A process for producing the sealed battery sealing body according to any one of means 1 to 3 by resin insert molding, and the sealing board is disposed in an opening of the battery can. And a step of sealing the battery can by laser welding the end of the battery.

  According to the invention described in means 5, the sealing body containing the PTC element is integrally formed by resin insert molding. Then, a sealing body is arrange | positioned at the opening part of a battery can, and a battery can is sealed by laser-welding the edge part of a sealing board. If it does in this way, the number of parts at the time of the assembly of a sealed battery can be decreased. In addition, since it is not necessary to attach the PTC element after the sealed battery is assembled, the productivity of the sealed battery can be improved and the manufacturing cost can be reduced.

  As described above in detail, according to the inventions described in the means 1 to 3, it is possible to provide a sealed battery sealing body that has a built-in PTC element and can maintain sufficient sealing performance. Further, according to the invention described in the means 4, the sealed battery can be reliably sealed using the sealing body containing the PTC element. According to the invention described in the means 5, the manufacturing cost of the sealed battery can be suppressed.

1 is a cross-sectional view of a main part illustrating a schematic configuration of a lithium primary battery according to an embodiment. The bottom view which shows the sealing body of one Embodiment. Sectional drawing which shows the sealing body of another embodiment. The bottom view which shows the sealing body of FIG. Sectional drawing which shows the sealing body of another embodiment. Sectional drawing which shows the sealing body of a prior art. Sectional drawing which shows the example at the time of incorporating a PTC element in the sealing body of a prior art.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part showing a schematic configuration of a lithium primary battery 10 (sealed battery) in the present embodiment.

  As shown in FIG. 1, a lithium primary battery 10 includes a bottomed cylindrical positive electrode can 11 (battery can), an electrode body 12 accommodated in the positive electrode can 11 together with a non-aqueous electrolyte, and a positive electrode can 11. And a sealing body 15 attached to the opening 13.

  The positive electrode can 11 is produced, for example, by press-molding a stainless steel plate into a bottomed cylindrical shape. The electrode body 12 is formed by laminating a belt-like positive electrode 21 and a belt-like negative electrode 22 via a separator 23 and winding them. The positive electrode 21 is formed by, for example, pressing a positive electrode material containing manganese dioxide on a stainless steel plate (positive electrode current collector) processed into a mesh shape and cutting it into a strip shape. The negative electrode 22 is formed, for example, by cutting a lithium-aluminum alloy plate into a strip shape.

  The sealing body 15 includes a sealing plate 31 made of a metal plate (for example, a stainless steel plate), a resin packing 32, a negative electrode terminal 33, a PTC element 34, a cap member 35, and an insulating ring 36. In the sealing body 15, a lead member 37 is welded to the lower end surface of the negative electrode terminal 33, and the negative electrode terminal 33 is electrically connected to the negative electrode 22 of the electrode body 12 through the lead member 37. Further, the positive electrode 21 of the electrode body 12 is electrically connected to the inner wall of the positive electrode can 11 via the lead member 38.

  The sealing plate 31 is formed in a disc shape according to the shape of the opening 13 of the positive electrode can 11, and a through hole 41 is formed in the center thereof. A negative electrode terminal 33 is fixed to the through hole 41 of the sealing plate 31 via a resin packing 32. As shown in FIGS. 1 and 2, the negative electrode terminal 33 is a columnar member having a flange portion 42 at one end portion (upper end portion in FIG. 1) arranged in the outer direction of the can. Is inserted through the center of the. The negative electrode terminal 33 of the present embodiment is formed in a tapered shape so that its diameter increases as it goes to the end (lower end) on the opposite side of the flange 42.

  The resin packing 32 is formed in a disc shape so as to fill a gap between the outer peripheral surface of the negative electrode terminal 33 and the inner peripheral surface of the through hole 41 and to cover the periphery of the through hole 41 in the sealing plate 31. More specifically, the resin packing 32 is tightly fixed to the sealing plate 31 so as to sandwich the front surface and the back surface of the peripheral portion of the through hole 41.

  The PTC element 34 has a disk shape having an element front surface and an element back surface, and a through hole 45 is formed at the center thereof. This PTC element 34 has a structure in which a conductive polymer material having a positive temperature characteristic is sandwiched between element electrodes (specifically, plate-like nickel electrodes), and the resistance value increases as the temperature rises. To do.

  The cap member 35 is formed in a cap shape using a conductive material such as a nickel-plated steel plate. Specifically, the cap member 35 has its outer peripheral end bent so as to surround the PTC element 34 by caulking, and the PTC element 34 is sandwiched and fixed between the flange part 42. In addition, the cap member 35 and the negative electrode terminal 33 are provided between the fitting portion between the cap member 35 and the flange portion 42, that is, between the inner portion of the bent outer peripheral end of the cap member 35 and the outer peripheral portion of the flange portion 42. Insulating ring 36 is interposed so that they are not directly connected to each other. The insulating ring 36 is formed in an annular shape using a thin insulating sheet, and is disposed in the cap member 35 in a state where the insulating ring 36 is bent in an L-shaped cross section. By providing the insulating ring 36, the negative electrode terminal 33 and the cap member 35 are connected via the PTC element 34. In this case, since the discharge current of the battery 10 flows through the PTC element 34, the PTC element 34 can prevent overcurrent.

  In the sealing body 15 of the present embodiment, the inner peripheral end of the insulating ring 36 interposed between the flange portion 42 and the cap member 35 projects inward from the bent outer peripheral end of the cap member 35. That is, the inner peripheral end of the insulating ring 36 and the outer peripheral end of the cap member 35 are arranged in steps on the lower surface of the flange portion 42. A stepped portion 47 formed between the outer peripheral end of the cap member 35 and the inner peripheral end of the insulating ring 36 and the flange portion 42 is embedded in the resin packing 32. In the sealing body 15, the members 31, 32, 33, 34, 35, and 36 are integrally formed by resin insert molding. And the outer peripheral part of the sealing board 31 in the sealing body 15 is contacting the inner peripheral surface of the positive electrode can 11, and the contact part is connected by laser welding. Thus, the inside of the lithium primary battery 10 is hermetically sealed by attaching the sealing body 15 to the opening 13 of the positive electrode can 11.

  Next, the manufacturing method of the lithium primary battery 10 of this Embodiment is demonstrated.

  First, the sealing body 15 is integrally formed by resin insert molding. Specifically, the negative electrode terminal 33 having the flange portion 42 is formed by crushing the wire using a press machine. In addition, a metal plate punched into a disk shape is prepared, and an insulating ring 36 formed in an annular shape using an insulating sheet is prepared. Further, a PTC element 34 is prepared and a sealing plate 31 is prepared. Then, the PTC element 34 is disposed on the upper surface of the flange portion 42 of the negative electrode terminal 33, and a metal plate is disposed so as to cover the PTC element 34. Thereafter, the insulating ring 36 is fitted into the back surface side of the flange portion 42, and the cap member 35 is formed by caulking the outer peripheral edge of the metal plate. Thus, the PTC element 34 is fixed by attaching the cap member 35 to the flange portion 42 of the negative electrode terminal 33. Here, in order to improve the connectivity of the PTC element 34, the contact surface between the element surface and the cap member 35 and the contact surface between the element back surface and the flange portion 42 may be connected by solder, a conductive adhesive, or the like. .

  Next, the negative electrode terminal 33 on which the PTC element 34 and the cap member 35 are mounted and the sealing plate 31 are inserted into predetermined positions in the insert molding die. Then, a resin material to be the resin packing 32 is injected into the mold and insert molding is performed to integrally form the sealing body 15.

  Also, a positive electrode 21, a negative electrode 22, and a separator 23 formed in a strip shape are prepared, and lead members 37 and 38 are pressure-bonded to the end of the positive electrode 21 and the end of the negative electrode 22. And the positive electrode 21 and the negative electrode 22 are piled up via the separator 23, and the electrode body 12 is formed by winding them. Further, the electrode body 12 is accommodated in the positive electrode can 11, the lead member 38 of the positive electrode 21 is welded to the inner wall of the positive electrode can 11, and the lead member 37 of the negative electrode 22 is connected to the lower end surface of the negative electrode terminal 33 in the sealing body 15. To weld connection.

  Next, a nonaqueous electrolytic solution is injected into the positive electrode can 11, and the sealing body 15 is fitted into the opening 13 of the positive electrode can 11. Thereafter, the positive electrode can 11 is hermetically sealed by laser welding the outer peripheral portion of the sealing body 15 (sealing plate 31). The lithium primary battery 10 of FIG. 1 is manufactured through the above steps.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) The sealing body 15 of the present embodiment is integrally formed by resin insert molding. When the sealing body 15 is formed in this way, the PTC element 34 can be reliably incorporated without applying a large load to the PTC element 34. Further, in the sealing body 15, the stepped portion 47 formed between the outer peripheral end of the cap member 35 and the inner peripheral end of the insulating ring 36 and the flange portion 42 is embedded in the resin packing 32. The length of can be reduced. Furthermore, since the contact area of the resin packing 32 in the sealing body 15 increases, the sealing performance can be sufficiently improved. Moreover, since the sealing body 15 does not need to use the washer 55 as in the case of the conventional rivet method, the number of parts is reduced. Furthermore, the capacity in the positive electrode can 11 can be secured by the volume of the washer 55. For this reason, the electrolyte solution and electrode active material in the positive electrode can 11 can be increased, and the discharge characteristics of the lithium primary battery 10 can be enhanced.

  (2) In the sealing body 15 of the present embodiment, the negative electrode terminal 33 is formed in a tapered shape so that the diameter increases toward the end on the opposite side of the flange portion 42. When the negative electrode terminal 33 is formed in this way, the tapered side wall portion becomes a wedge and the negative electrode terminal 33 is difficult to be removed, and the component reliability of the sealing body 15 is improved.

  (3) In the present embodiment, since the sealing body 15 incorporating the PTC element 34 is integrally formed, the number of parts when assembling the battery can be reduced. Moreover, since it is not necessary to attach the PTC element 34 after the lithium primary battery 10 is assembled, the productivity of the lithium primary battery 10 can be improved and the manufacturing cost can be reduced.

  In addition, you may change embodiment of this invention as follows.

  -In the sealing body 15 of the said embodiment, you may change the shape of the negative electrode terminal 33. FIG. FIG. 3 shows a specific example thereof. As shown in FIG. 3, the negative electrode terminal 33 </ b> A in the sealing body 15 </ b> A has a flange portion 42 at the upper end similarly to the above embodiment, and is formed in a tapered shape so that the diameter increases toward the lower end. Furthermore, the negative electrode terminal 33A has a concave portion 48 (hollow portion) that opens at the center of the end face of the flange portion 42, and the concave portion 48 extends in the terminal axis direction. Further, the negative electrode terminal 33A is formed to be elliptical when viewed from the axial direction (see FIG. 4). Thus, by making the negative electrode terminal 33A elliptical, rotation of the negative electrode terminal 33A in the circumferential direction can be restricted, and the sealing performance of the sealing body 15A can be improved. As a result, it is possible to avoid the problem that water enters through the gap between the negative electrode terminal 33 and the resin packing 32 and the battery performance deteriorates. The negative electrode terminal 33A is formed, for example, by pressing a plate material. In the press working, a non-circular negative electrode terminal such as an elliptical shape can be easily formed. Further, in the negative electrode terminal 33, a convex portion or a concave portion may be provided on the outer peripheral surface to form a non-circular terminal, and the rotation of the negative electrode terminal 33 may be restricted.

  In the sealing bodies 15 and 15A of the above embodiment, the PTC element 34 is disposed on the upper surface of the flange portion 42 of the negative terminals 33 and 33A. However, the present invention is not limited to this. For example, the PTC element 34 may be disposed on the lower surface of the flange portion 42 as in the sealing body 15B shown in FIG. In the sealing body 15B, an insulating sheet 49 is provided between the lower surface of the cap member 35 and the upper surface of the flange portion 42 so that the cap member 35 and the flange portion 42 do not directly contact each other. Also in the sealing body 15B, a stepped portion 47A is formed between the outer peripheral end bent at the cap member 35 and the flange portion 42, and the stepped portion 47A is embedded in the resin packing 32. Even if it does in this way, since the sealing body 15B containing the PTC element 34 can be formed integrally, the assembly | attachment property of the lithium primary battery 10 improves.

  In the above embodiment, the lithium primary battery 10 is embodied. However, other sealed batteries such as a nickel-hydrogen battery and a lithium secondary battery may be embodied.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.

  (1) The sealed battery sealing body according to any one of the means 1 to 3, wherein the PTC element is formed in a disk shape having a through hole in a central portion.

  (2) The sealed battery sealing body according to any one of the means 1 to 3, wherein the terminal is formed in an elliptical shape when viewed in the axial direction.

  (3) The sealed battery sealing body according to any one of the means 1 to 3, wherein the sealing body has a recess opening in the center of the end face of the flange portion and extending in the axial direction of the terminal.

  (4) The sealed battery seal according to any one of the means 1 to 3, wherein a convex portion or a concave portion for restricting circumferential rotation is provided on the outer peripheral surface of the terminal. body.

DESCRIPTION OF SYMBOLS 10 ... Lithium primary battery as a sealed battery 11 ... Positive electrode can as a battery can 13 ... Opening part 15,15A, 15B ... Sealing body 31 ... Sealing plate 32 ... Resin packing 33, 33A ... Negative electrode terminal as a terminal 34 ... PTC element 35 ... Cap member 36 ... Insulating ring made of insulating sheet 41 ... Through hole in sealing plate 42 ... Flange portion 47, 47A ... Stepped portion 49 ... Insulating sheet

Claims (5)

A sealed battery sealing body attached to the opening by laser welding to seal the opening of the battery can,
A metal sealing plate provided to close the opening and having a through hole in the center;
A columnar terminal having a flange portion at one end which is fixed through a resin packing in a state of being inserted into the through hole of the sealing plate and arranged in the outer direction of the can,
A plate-like PTC element disposed on the flange portion;
A cap member whose outer peripheral end is bent so as to surround the PTC element, and the PTC element is sandwiched and fixed between the flange part,
An insulating sheet interposed at a contact portion between the cap member and the flange portion is integrally formed, and a step portion formed between the outer peripheral end bent at the cap member and the flange portion is the resin. A sealed battery sealing body characterized by being embedded in a packing made of metal.   2. The sealed battery sealing body according to claim 1, wherein the terminal is formed in a tapered shape so that a diameter thereof increases toward an end portion on the opposite side of the flange portion. 3. The terminal according to claim 1, wherein the terminal includes the flange portion and a columnar portion other than the flange portion, and the columnar portion is formed in a noncircular shape when viewed in the axial direction. The sealing body for sealed batteries described in 1.   A sealed battery, wherein an opening of a battery can is sealed using the sealed battery sealing body according to any one of claims 1 to 3. A step of producing the sealed battery sealing body according to any one of claims 1 to 3 by resin insert molding;
And a step of sealing the battery can by placing the sealing body in the opening of the battery can and laser-welding the end of the sealing plate.

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