JP2015060705A - Method of manufacturing sealed battery and sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a sealed battery in which the edge of a safety valve and a terminal cap can be welded, by preventing occurrence of voids and blowholes and the sealed battery.SOLUTION: In a method of manufacturing a sealed battery 100 including a welding step for welding a terminal cap 212 and a safety valve 5, the terminal cap 212 includes an abutment surface 212A abutting against the surface at the edge 5A of the safety valve 5 on the terminal cap 212 side, and a flange 212B located around the abutment surface 212A. In the welding process, the edge 5A of the safety valve 5 and the flange 212B are welded, and a groove 212C for releasing the air when welding the edge 5A of the safety valve 5 and flange 212B is formed at least partially between the welding part at the edge 5A of the safety valve 5 and the abutment surface 212A of the terminal cap 212.

Description

  The present invention relates to a method for manufacturing a sealed battery and a sealed battery.

  The importance of a secondary battery is increasing as a power source mounted on a vehicle using electricity as a driving source, or a power source used for a personal computer, a portable terminal, or other electrical products. In particular, a sealed battery such as a lithium ion secondary battery that is lightweight and has a high energy density is preferable as a high-output power source for mounting on a vehicle.

  Generally, a lithium ion secondary battery is fitted to an electrode body, a battery case that houses the electrode body, a positive terminal and a negative terminal that are electrically connected to the electrode body, and an opening of the battery case And a sealing body. The positive electrode terminal and the negative electrode terminal are attached to the sealing body. And a lithium ion secondary battery is formed by fitting the said sealing body in the opening part of a battery case.

  Moreover, the positive electrode terminal and the negative electrode terminal have an external terminal arranged on the outer side of the casing made of the sealing body and the battery case, and an internal terminal arranged on the inner side of the casing. The internal terminal functions as a current collecting terminal that collects current from the electrode body.

  A safety valve is provided between the current collecting terminal and the external terminal. The safety valve is formed from a metal foil or the like. And the edge part of a safety valve is electrically connected with the terminal cap which comprises an external terminal, and the center part vicinity of the safety valve is electrically connected with the current collection terminal. When the pressure in the housing formed by the battery case and the sealing body rises due to malfunction of the secondary battery, the safety valve is pushed upward (sealing body side) by the pressure, and the current collecting terminal and the safety valve Is disconnected. Thereby, a current collection terminal and an external terminal are insulated.

  Further, the edge of the safety valve and the terminal cap are fixed by welding or bonding with a conductive adhesive. Patent Document 1 describes laser welding the edge of a safety valve and a terminal cap.

International Publication 2012/1477782

  However, when the edge of the safety valve and the terminal cap are welded by laser welding, there is a problem that voids or blowholes are generated in the welded portion.

  The present invention has been made in order to solve such a problem, and it is possible to prevent the generation of voids and blowholes and to manufacture a sealed battery capable of welding the edge of the safety valve and the terminal cap, and the sealing. It aims at providing a type battery.

  The method for manufacturing a sealed battery according to the first aspect of the present invention includes a welding step of welding the terminal cap and the safety valve. The terminal cap includes a contact surface that contacts a surface of the safety valve at an edge of the safety valve, and a flange portion positioned around the contact surface. In the welding process, the edge portion of the safety valve and the flange portion are welded. In addition, air escapes when welding the edge portion of the safety valve and the flange portion to at least a part between the welded portion of the edge portion of the safety valve and the contact surface of the terminal cap. A gap is formed.

  The sealed battery according to the second aspect of the present invention includes a terminal cap and a safety valve. The terminal cap includes a contact surface that contacts a surface of the safety valve at an edge of the safety valve, and a flange portion positioned around the contact surface. The edge of the safety valve is welded to the flange. In addition, air escapes when welding the edge portion of the safety valve and the flange portion to at least a part between the welded portion of the edge portion of the safety valve and the contact surface of the terminal cap. A gap is formed.

  It is possible to provide a sealed battery manufacturing method and a sealed battery that can prevent the generation of voids and blow holes and can weld the edge of the safety valve and the terminal cap.

It is a partial expanded sectional view of the secondary battery concerning Embodiment 1 of this invention. It is the top view which looked at the terminal cap concerning Embodiment 1 of this invention from the safety valve side. It is a III-III arrow sectional view of Drawing 3. It is a fragmentary sectional view which shows the welding part of the terminal cap concerning a comparative example, and a safety valve. It is a figure explaining the cause which a void and a blow hole generate | occur | produce in a welding start point by laser welding. It is a figure explaining the cause which a void and a blowhole generate | occur | produce in a temporary attachment part by laser welding. It is a X-ray CT image of the welding part of the terminal cap concerning a comparative example, and a safety valve. It is a X-ray CT image of the welding part of the terminal cap concerning a comparative example, and a safety valve. It is a X-ray CT image of the welding part of the terminal cap concerning Embodiment 1 of this invention, and a safety valve. It is a fragmentary sectional view which shows the welding part of the terminal cap concerning Embodiment 2 of this invention, and a safety valve. It is a fragmentary sectional view which shows the welding part of the terminal cap concerning Embodiment 3 of this invention, and a safety valve.

Embodiment 1
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged sectional view of a sealed battery 100 according to the first embodiment of the present invention. The sealed battery 100 is a sealed lithium ion secondary battery or the like. The sealed battery 100 includes an electrode body (not shown), a battery case (not shown), a sealing body 1, an electrode terminal 2, a first insulating member 3, a second insulating member 4, a safety valve 5, and the like. FIG. 1 is an enlarged cross-sectional view showing a mounting structure portion between the sealing body 1 and the electrode terminal 2 of the sealed battery 100.

  The electrode body is obtained by laminating a positive electrode sheet and a negative electrode sheet via a separator (not shown). The electrode body is wound into a flat shape and is accommodated in the battery case.

The battery case is a flat box-shaped member. And the wound electrode body and the nonaqueous electrolyte are accommodated in the battery case.
Moreover, the upper surface of the battery case is opened. The sealing body 1 is fitted in the opening of the battery case. In other words, the battery case and the sealing body 1 form a casing of the sealed battery 100.
Further, the sealing body 1 has a through hole portion into which a terminal cap 212 (described later) of the electrode terminal 2 can be inserted.
The battery case and the sealing body 1 are made of metal.

  The electrode terminal 2 is a positive electrode terminal and a negative electrode terminal, and is attached to the sealing body 1. The electrode terminal 2 is electrically connected to the electrode body. Moreover, the electrode terminal 2 has the external terminal 21 arrange | positioned on the outer side of the housing | casing which consists of the sealing body 1 and a battery case, and the internal terminal 22 arrange | positioned at the inner side of the said housing | casing. The internal terminal 22 functions as a current collecting terminal that collects current from the electrode body. The electrode terminal 2 is made of a conductive material.

  The external terminal 21 includes a main body 211, a terminal cap 212, and the like. The main body portion 211 has a through hole portion through which the terminal cap 212 can be inserted. The terminal cap 212 is a hollow rivet-shaped member.

  The first insulating member 3 is provided between the terminal cap 212 and the inner terminal 22 side surface of the sealing body 1 and the inner surface of the through hole portion of the sealing body 1. Further, the first insulating member 3 has a through hole portion through which the terminal cap 212 can be inserted.

  The second insulating member 4 is provided between the terminal cap 212 and the surface of the sealing body 1 on the external terminal 21 side. Further, the second insulating member 4 has a through hole portion through which the terminal cap 212 can be inserted.

  The first insulating member 3 and the second insulating member 4 are formed using a resin material as a main material. The first insulating member 3 and the second insulating member 4 prevent unnecessary current from flowing out from the external terminal 21.

  Then, the terminal cap 212 is caulked and fixed to the through hole portion of the main body portion 211, the through hole portion of the first insulating member 3, the through hole portion of the sealing body 1, and the through hole portion of the second insulating member 4. The main body 211, the first insulating member 3, the sealing body 1 and the second insulating member 4 are connected to each other. That is, the terminal cap 212 has a role of attaching the main body portion 211 to the sealing body 1.

The safety valve 5 is provided between the external terminal 21 and the internal terminal 22. The safety valve 5 is formed from a metal foil. Further, the edge 5 </ b> A of the safety valve 5 is electrically connected to the terminal cap 212 of the external terminal 21. More specifically, the edge portion 5A of the safety valve 5 is welded to a flange portion 212B (described later) of the terminal cap 212. Further, the edge portion 5A and the flange portion 212B are welded to a depth reaching a groove portion 212C (described later). Thereby, the terminal cap 212 and the safety valve 5 are sealed.
The central portion 5B of the safety valve 5 is electrically connected to the internal terminal 22.
That is, the external terminal 21 is electrically connected to the internal terminal 22 through the safety valve 5.

  And when the pressure in the housing | casing formed from a battery case and the sealing body 1 rises by the malfunctioning etc. of the sealed battery 100, the safety valve 5 is pushed up by the said pressure (sealing body 1 side), The connection between the safety valve 5 and the internal terminal 22 is cut off. Thereby, the internal terminal 22 and the external terminal 21 are insulated. In other words, the safety valve 5 is a diaphragm formed from a metal foil.

FIG. 2 is a plan view of the terminal cap 212 as viewed from the safety valve 5 side (internal terminal 22 side). 3 is a cross-sectional view taken along arrow III-III in FIG. As shown in FIG. 2, the terminal cap 212 includes a contact surface 212A that contacts the surface of the edge portion 5A of the safety valve 5 on the terminal cap 212 side, and a flange portion 212B that is positioned around the contact surface 212A. .
As shown in FIGS. 2 and 3, the terminal cap 212 has a groove 212C formed in at least a part of the contact surface 212A. The groove 212C is continuous with the central hole 212D of the terminal cap 212.

  More specifically, in FIG. 2, the groove portion 212 </ b> C has a position corresponding to the temporary attachment portion X <b> 1 between the flange portion 212 </ b> B of the terminal cap 212 and the edge portion 5 </ b> A of the safety valve 5, and the flange portion 212 </ b> B of the terminal cap 212 and the safety valve 5. And a position corresponding to the welding start position X2 with the edge 5A. The temporary attachment portion X1 is a portion welded to temporarily fix the flange portion 212B of the terminal cap 212 and the edge portion 5A of the safety valve 5.

The groove 212C serves as a gap for air to escape from the welded portion between the edge 5A of the safety valve 5 and the flange 212B when the edge 5A of the safety valve 5 and the flange 212B are welded.
In other words, air escapes when welding the edge portion 5A of the safety valve 5 and the flange portion 212B to at least a portion between the welded portion of the edge portion 5A of the safety valve 5 and the contact surface 212A of the terminal cap 212. A gap is formed for this purpose.

  When the edge portion 5A of the safety valve 5 and the flange portion 212B are welded, if air enters the welded portion between the edge portion 5A of the safety valve 5 and the flange portion 212B, voids or blowholes are generated. Therefore, in the sealed battery 100 according to the first embodiment of the present invention, the gap is formed at least at a part between the welded portion of the edge 5A of the safety valve 5 and the contact surface 212A of the terminal cap 212. .

With reference to FIG. 4, the cause of the occurrence of voids and blowholes at the welded portion between the edge of the safety valve and the terminal cap will be described. FIG. 4 is a partial cross-sectional view showing a welded portion between the terminal cap 6 and the safety valve 7 according to the comparative example. In addition, the terminal cap 6 concerning a comparative example does not have a groove part in 6 A of contact surfaces.
As shown in FIG. 4, the end of the edge 7A of the safety valve 7 has a rounded shape due to punching. Therefore, a space Y is generated between the end of the edge 7 </ b> A of the safety valve 7 and the terminal cap 6. When the edge portion 7A of the safety valve 7 and the flange portion 6B of the terminal cap 6 are welded, the air in the space Y enters the welded portion. In FIG. 4, hatching is given to a portion surrounded by a thick frame in the welded portion.

  The cause of the occurrence of voids and blowholes at the welding start position will be described with reference to FIG. FIG. 5 is a view schematically showing the edge portion 7A of the safety valve 7 and the flange portion 6B of the terminal cap 6 at the welding start position. In FIG. 5, a portion surrounded by a thick frame is shown with hatching. As shown in FIG. 5, since the welding start position is substantially the same as the welding end position, air is trapped. Therefore, voids and blow holes are generated at the welding start position.

  The cause of the occurrence of voids and blow holes in the tacking portion will be described with reference to FIG. FIG. 6 is a diagram schematically showing the edge portion 7A of the safety valve 7 and the flange portion 6B of the terminal cap 6 in the temporary attachment portion. In FIG. 6, hatching is given to a portion surrounded by a thick frame in the welded portion. As shown in FIG. 6, the welding progresses, and the welded portion approaches the tacking portion, thereby causing air containment. For this reason, voids and blow holes are generated in the tacking portion.

  In FIG. 7, the X-ray CT image which imaged the welding part of the terminal cap 6 concerning the comparative example and the safety valve 7 from the sealing body side is shown. Moreover, the X-ray CT image imaged from the VIII-VIII arrow direction of FIG. 7 is shown in FIG. FIG. 9 shows an X-ray CT image obtained by imaging the welded portion between the terminal cap 212 and the safety valve 5 according to the first embodiment from the sealing body 1 side.

  As shown in FIG. 7, in the comparative example, voids are generated at the tacking portion X1 and the welding start position X2. Further, it can be seen from FIG. 8 that at the welding start position X2, air is contained in the welded portion between the edge portion 7A of the safety valve 7 and the flange portion 6B of the terminal cap 6 to generate a void.

  On the other hand, as shown in FIG. 9, no voids or blowholes are generated in the welded portion between the terminal cap 212 and the safety valve 5 according to the first embodiment.

Next, a method for manufacturing the sealed battery 100 according to the first embodiment of the present invention will be briefly described.
First, an active material, a binder, a conductive additive, a solvent, and the like are kneaded using a kneader to prepare an electrode mixture paste (kneading step).
Next, after applying the electrode mixture paste on the current collector, it is dried to produce a positive electrode sheet and a negative electrode sheet (coating drying process).
Next, a positive electrode sheet, a negative electrode sheet, and a separator are laminated to form a laminate, and the laminate is wound to produce an electrode body (winding step).

  Next, the electrode terminal 2, the first insulating member 3, the second insulating member 4 and the safety valve 5 are attached to the sealing body 1 (first assembling step). At this time, the edge 5A of the safety valve 5 and the flange 212B of the terminal cap 212 are welded using laser welding (welding process). At this time, since the groove 212C is formed on the contact surface 212A of the terminal cap 212, air escapes through the groove 212C when welding the edge 5A of the safety valve 5 and the flange 212B of the terminal cap 212. It is possible to prevent air from being trapped in the welded portion. Therefore, generation | occurrence | production of a void and a blowhole can be prevented and the edge part 5A of the safety valve 5 and the terminal cap 212 can be welded.

The edge 5A of the safety valve 5 and the flange 213B of the terminal cap 212 are welded over the entire circumference of the terminal cap 212. Thereby, the airtightness of the sealed battery 100 can be ensured.
The welded structure between the edge 5A of the safety valve 5 and the flange 213B of the terminal cap 212 is a so-called butt weld structure, not a lap weld or fillet weld structure.

Next, the electrode terminal 2 and the electrode body are electrically connected, and the sealing body 1 to which the electrode body, the electrode terminal 2, the first insulating member 3, the second insulating member 4 and the safety valve 5 are attached is connected to the battery. It fits into the opening of the case and is fixed by welding or the like (second assembly step). Thereby, an electrode body etc. are accommodated in a battery case.
Next, after injecting a nonaqueous electrolyte from the inlet of the sealing body 1 (injection process), the sealed battery 100 is manufactured through a plurality of manufacturing processes such as a charge / discharge process and an aging process.

  According to the sealed battery 100 and the manufacturing method of the sealed battery 100 according to the first embodiment of the present invention described above, the welded portion of the edge 5A of the safety valve 5 and the contact surface 212A of the terminal cap 212 are arranged. A gap for air to escape when welding the edge portion 5 </ b> A of the safety valve 5 and the flange portion 212 </ b> B of the terminal cap 212 is formed in at least a part of the gap. Therefore, when the edge 5A of the safety valve 5 and the flange 212B of the terminal cap 212 are welded, air can escape through the gap, and air can be prevented from being contained in the welded portion. Therefore, generation | occurrence | production of a void and a blowhole can be prevented and the edge part 5A of the safety valve 5 and the terminal cap 212 can be welded.

Specifically, the gap is a groove portion 212 </ b> C formed in at least a part of the contact surface 212 </ b> A of the terminal cap 212. More specifically, the terminal cap 212 is a hollow rivet-shaped member, and the groove portion 212 </ b> C is continuous with the central hole portion 212 </ b> D of the terminal cap 212.
Thereby, when welding the edge part 5A of the safety valve 5 and the flange part 212B of the terminal cap 212, air can escape more suitably through the groove part 212C.

Further, the groove portion 212C has a position corresponding to the temporary attachment portion X1 between the flange portion 212B and the edge portion 5A of the safety valve 5, and a position corresponding to the welding start position X2 between the flange portion 212B and the edge portion 5A of the safety valve 5. Is provided.
Thereby, when welding the edge 5A of the safety valve 5 and the flange 212B of the terminal cap 212, voids and blowholes are generated at the temporary attachment portion X1 and the welding start position X2, which are locations where air is more easily contained. Occurrence can be prevented.

Embodiment 2. FIG.
The sealed battery according to the second embodiment of the present invention is different from the sealed battery according to the first embodiment only in the structure of the terminal cap 213. For this reason, the same components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 10 is a partial cross-sectional view showing a welded portion between the terminal cap 213 and the safety valve 5 according to the second embodiment of the present invention. As shown in FIG. 10, the terminal cap 213 includes a groove 213 </ b> C on the contact surface 213 </ b> A over the entire circumference of the terminal cap 213. The terminal cap 213 is a hollow rivet-shaped member, and only the position and shape of the groove 213C are different from the terminal cap 212 according to the first embodiment.

Further, in the terminal cap 213 according to the second embodiment, the groove portion 213C and the central hole portion of the terminal cap 213 are arranged at predetermined positions on the contact surface 213A so that the groove portion 213C is continuous with the central hole portion of the terminal cap 213. The groove part which connects and may be formed.
In addition, since the manufacturing method of the sealed battery concerning Embodiment 2 is the same as the manufacturing method of the sealed battery concerning Embodiment 1, the description is abbreviate | omitted.

According to the sealed battery and the manufacturing method of the sealed battery according to the second embodiment described above, the same effects as those of the sealed battery 100 and the manufacturing method of the sealed battery 100 according to the first embodiment can be obtained. it can.
That is, when welding the edge portion 5A of the safety valve 5 and the flange portion 213B of the terminal cap 213, air can escape to the groove portion 213C, and air can be prevented from being trapped in the welded portion. Therefore, generation | occurrence | production of a void and a blowhole can be prevented and the edge part 5A and the terminal cap 213 of the safety valve 5 can be welded.

Embodiment 3 FIG.
The sealed battery according to the third embodiment of the present invention differs from the sealed battery according to the first embodiment only in the structure of the safety valve 50 and the terminal cap 214. For this reason, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 11 is a partial cross-sectional view showing a welded portion between the terminal cap 214 and the safety valve 50 according to the third embodiment of the present invention.
As shown in FIG. 11, the terminal cap 213 is different from the terminal cap 212 according to the first embodiment only in that there is no groove on the contact surface 214A. That is, the terminal cap 214 is a hollow rivet-shaped member, a contact surface 214A that contacts the surface of the edge portion 50A of the safety valve 50 on the terminal cap 214 side, and a flange portion 214B that is positioned around the contact surface 214A. .

  Further, as shown in FIG. 11, the edge 50A of the safety valve 50 is bent in a direction away from the contact surface 214A. Thereby, a gap is formed between the welded portion of the edge portion 50 </ b> A of the safety valve 50 and the contact surface 214 </ b> A of the terminal cap 214.

Further, in the terminal cap 214 according to the third embodiment, the gap and the central hole of the terminal cap 214 are arranged at predetermined positions on the contact surface 214A so that the gap is continuous with the central hole of the terminal cap 214. The groove part which connects and may be formed.
In addition, since the manufacturing method of the sealed battery concerning Embodiment 3 is the same as the manufacturing method of the sealed battery concerning Embodiment 1, the description is abbreviate | omitted.

According to the sealed battery and the manufacturing method of the sealed battery according to the third embodiment described above, the same effects as the sealed battery 100 and the manufacturing method of the sealed battery 100 according to the first embodiment can be obtained. it can.
That is, when welding the edge portion 50A of the safety valve 50 and the flange portion 214B of the terminal cap 214, air can escape into the gap, and air can be prevented from being contained in the welded portion. Therefore, generation of voids and blowholes can be prevented, and the edge portion 50A of the safety valve 50 and the terminal cap 214 can be welded.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Sealing body 2 Electrode terminal 21 External terminal 211 Main body part 212, 213, 214 Terminal cap 212A, 213A, 214A Contact surface 212B, 213B, 214B Flange part 212C, 213C Groove part 212D Central hole part 22 Internal terminal 3 First terminal Insulating member 4 Second insulating member 5, 50 Safety valve 5A, 50A Edge 100 Sealed battery X1 Temporary attachment X2 Welding start position

Claims (12)

A method for producing a sealed battery including a welding step of welding a terminal cap and a safety valve,
The terminal cap includes a contact surface that comes into contact with a surface on the terminal cap side of an edge portion of the safety valve, and a flange portion positioned around the contact surface,
In the welding step, the edge of the safety valve and the flange are welded,
A gap for air to escape when welding the edge portion of the safety valve and the flange portion is at least partly between the welded portion of the edge portion of the safety valve and the contact surface of the terminal cap. A method of manufacturing a sealed battery that is formed.   The method for manufacturing a sealed battery according to claim 1, wherein the gap is a groove formed in at least a part of the contact surface of the terminal cap.   The method for manufacturing a sealed battery according to claim 2, wherein the terminal cap is a hollow rivet-shaped member, and the groove is continuous with a central hole of the terminal cap.   The groove portion is provided at a position corresponding to a temporary attachment portion between the flange portion and the edge portion of the safety valve, and a position corresponding to a welding start position between the flange portion and the edge portion of the safety valve. The method for producing a sealed battery according to claim 2 or 3.   The method of manufacturing a sealed battery according to claim 1, wherein the gap is a groove formed on the contact surface over the entire circumference of the terminal cap.   2. The method for manufacturing a sealed battery according to claim 1, wherein the gap is formed by bending the edge of the safety valve in a direction away from the contact surface. A sealed battery comprising a terminal cap and a safety valve,
The terminal cap includes a contact surface that comes into contact with a surface on the terminal cap side of an edge portion of the safety valve, and a flange portion positioned around the contact surface,
The edge of the safety valve is welded to the flange;
A gap for air to escape when welding the edge portion of the safety valve and the flange portion is at least partly between the welded portion of the edge portion of the safety valve and the contact surface of the terminal cap. A sealed battery is formed.   The sealed battery according to claim 7, wherein the gap is a groove formed in at least a part of the contact surface of the terminal cap.   The sealed battery according to claim 8, wherein the terminal cap is a hollow rivet-shaped member, and the groove portion is continuous with a central hole portion of the terminal cap.   The groove portion is provided at a position corresponding to a temporary attachment portion between the flange portion and the edge portion of the safety valve, and a position corresponding to a welding start position between the flange portion and the edge portion of the safety valve. The sealed battery according to claim 8 or 9.   The sealed battery according to claim 7, wherein the gap is a groove formed in the contact surface over the entire circumference of the terminal cap.   The sealed battery according to claim 7, wherein the gap is formed by bending the edge of the safety valve in a direction away from the contact surface.