JPWO2013031669A1 - Battery and manufacturing method thereof - Google Patents

Abstract

Provided is a battery having a joint part in which a pair of conductive members are connected by a crimping part and a welded part using a high energy ray, in which internal resistance fluctuations are suppressed and reliability is improved, and a method for manufacturing the battery. . A battery outer can, a power generation element, a sealing plate, a connection terminal attached to the sealing plate in an insulated state, and a current collector electrically connected to the power generation element and the connection terminal. And an external terminal 18 electrically connected to the connection terminal 13, and at least one of the current collector and the connection terminal 13 between the connection terminal 13 and the external terminal 18 is one member. Is fixed to the other member and welded to each other with high energy rays, the high energy ray welding regions 21 to 24 are in a direction intersecting the boundary between one member and the other member. Two or more overlapping weld spots 21a to 24c are formed. [Selection] Figure 6

Description

  The present invention relates to a battery including a joint portion in which a pair of conductive members are connected to each other by a caulking portion and a welded portion using high energy rays, and a method for manufacturing the same.

  In recent years, the environmental protection movement has increased, and emission regulations of exhaust gases that cause global warming such as carbon dioxide gas have been strengthened. Therefore, in the automobile industry, electric vehicles (EV) and hybrid electric vehicles (HEV) are actively developed in place of vehicles using fossil fuels such as gasoline, diesel oil, and natural gas. As such EV and HEV batteries, sealed batteries such as nickel-hydrogen secondary batteries and lithium ion secondary batteries are used. However, in recent years, lightweight and high-capacity batteries can be obtained. Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are increasingly used.

  In EV and HEV applications, not only environmental measures but also basic performance as an automobile, that is, advanced driving performance such as acceleration performance and climbing performance are required. In order to satisfy such a demand, not only simply increasing the battery capacity but also a high output battery is required. In general, batteries for EV and HEV are often used in which a power generation element is housed in a metal rectangular outer can or cylindrical outer can. However, when a high output discharge is performed, a large current is generated in the battery. In order to flow, it is necessary to reduce the resistance of the battery, to reduce the internal resistance as much as possible, and to prevent resistance variation. For this reason, various improvements have been made to achieve high reliability and low resistance in the terminal portion and the joint inside the battery.

  A mechanical caulking method has been conventionally used as a method for realizing a reduction in resistance in the terminal portion of these batteries and the joint inside the battery. However, with only mechanical caulking, electrical resistance changes with time in an environment with a lot of vibration such as EV and HEV. Therefore, as shown in Patent Documents 1 to 3 below, bonding by caulking is performed. The boundary part is welded with a high energy beam such as a laser. At this time, if the entire boundary portion is welded, the portion where the caulking force is applied melts and the caulking force becomes weak. Therefore, only a part of the boundary portion is welded with a high energy beam. Patent Documents 2 and 3 below show examples in which welding is performed with high energy rays so that a plurality of welding spots overlap each other for each of a plurality of regions along the boundary portion of the joint portion by caulking. ing.

  Among these, the method for forming the junction between the current collector and the terminal disclosed in Patent Document 2 below will be described with reference to FIG. 9 in the case where laser light is used as the high energy beam. FIG. 9A is a cross-sectional view showing the process of processing the tip of the crimped portion of the terminal disclosed in Patent Document 2 below, and FIG. 9B is a view showing a step of laser welding after the step of FIG. 9A. 9B is a plan view of FIG. 9B, and FIG. 9D is a plan view after laser welding is repeated a plurality of times so that a plurality of welding spots overlap each other.

  The junction 60 between the current collector and the terminal disclosed in Patent Document 2 below includes a cover plate 61 fixed to a battery outer body (not shown), an inner insulating sealing material 62, and an outer insulating sealing material. 63, a current collector 64 connected to the power generation element, and a rivet terminal 65. The inner insulating sealing material 62 and the outer insulating sealing material 63 have through holes and are arranged on both the inner and outer peripheral edge portions of the opening formed in the lid plate 61. The current collector 64 is disposed so as to overlap the inner insulating sealing material 62. The rivet terminal 65 has a caulking portion 65b protruding from the jaw portion 65a.

  Then, the joining portion 60 is configured such that the caulking portion 65 b of the rivet terminal 65 is connected to the outer insulating sealing material 63 from the outer peripheral side of the lid plate 61, the opening of the lid plate 61, the inner insulating sealing material 62, and the current collector 64 The rivet terminal 65 is assembled by penetrating the terminal hole, and then integrated by crimping the crimping portion 65b of the rivet terminal 65 so as to press the current collector 64. Next, a processing punch A having a concave portion complementary to the caulking portion 65b of the rivet terminal 65 and having an inclined portion A1 having a predetermined angle on the periphery of the concave portion is prepared. Then, the machining punch A is pushed so that the inclined portion A1 contacts the tip 65c of the caulking portion 65b, and the tip 65c of the caulking portion 65b is partially deformed, and as shown in FIG. It shape | molds so that the front-end | tip 65c may become a truncated cone part. Thereby, the shape of the front-end | tip 65c of the crimping | crimped part 65b is adjusted to an obtuse angle.

  Next, as shown in FIGS. 9B and 9C, laser spot welding is performed by irradiating the laser beam LB from the direction perpendicular to or near the upper surface of the truncated cone portion of the tip 65c of the crimping portion 65b. The irradiation range of the laser beam LB at this time is a region including at least the current collector 64 and the truncated cone portion of the tip 65c of the crimping portion 65b, and the truncated cone of the current collector 64 and the tip 65c of the crimping portion 65b. Butt welding between the two parts. By this laser spot welding, the energy of the laser beam irradiated to both the current collector 64 and the truncated cone portion 65c of the crimping portion 65b is transmitted evenly, and a good welding spot (nugget) 66 is formed in the welded portion. Is done.

  Further, as shown in FIG. 9D, the current collector 64 is formed such that a plurality of welding spots 66 are formed so as to overlap each other along the truncated cone portion of the current collector 64 and the tip 65c of the caulking portion 65b. And the frustoconical portion of the tip 65c of the crimping portion 65b are butt welded.

JP 2009-076993 A JP 2008-251411 A JP 2010-033766 A JP 2008-066254 A

  When the formation of the joint as described in Patent Documents 2 and 3 is employed as a method for forming the terminal of the battery or the joint inside the battery, the internal resistance is reduced and there are many vibrations such as EV and HEV. Even under the environment, the electrical resistance hardly changes over time, and there is an excellent effect that high reliability and low internal resistance can be realized at the terminal portion and the joint inside the battery.

  However, in this method of forming the joint portion, the size of the crimped portion varies, and the position of the boundary portion between the crimped portion and the other member fluctuates. A challenge has arisen. In addition, aluminum-based metals or copper-based metals that are prone to solidification cracking are used for battery current collectors, connection terminals, external terminals, and the like. If the weld spot is formed so that multiple weld spots overlap each other along the boundary between the weld and another member, the next weld spot will completely overlap the crack that has occurred near the center of the weld spot. Therefore, there is a problem that cracks tend to remain in the joint portion. Such cracks in the welded part are difficult to be formed by continuous welding such as seam welding, but the terminal part of the battery and the joint part inside the battery are small in size. It is difficult to employ seam welding as a method for forming the joint inside the battery.

  The present invention has been made in order to solve the above-described problems, and in a battery including a joint portion in which a pair of conductive members are mechanically and electrically connected by a caulking portion and a welded portion by a high energy ray. An object of the present invention is to provide a battery in which resistance variation is suppressed and reliability is improved, and a method for manufacturing the same.

  In order to achieve the above object, a battery according to the present invention is a battery in which a pair of conductive members are fixed by caulking and a welded area welded to each other by a high energy ray is formed. Further, it is characterized in that it is formed by two or more overlapping welding spots in a direction crossing a boundary portion between one and the other of the pair of conductive members.

  In the battery of the present invention, two or more overlapping weld spots are formed in a direction intersecting the boundary portion between one member and the other member (the boundary line between the one member and the other member). Even if the position of the end portion of the caulking portion of one member varies, it can be reliably welded with the high energy beam across the one member and the other member. Therefore, according to the battery of the present invention, the pair of conductive members are connected by caulking and welding with a high energy beam, so that the internal resistance is reduced and the electrical resistance changes with time even in an environment with a lot of vibration. Is less likely to occur, and a highly reliable battery can be obtained.

  In addition, the battery of the present invention may be either a primary battery or a secondary battery, a cylindrical battery or a square battery, and a battery using a nonaqueous electrolyte and an aqueous electrolyte. Any of the batteries used is equally applicable. Furthermore, the welding area | region by the high energy ray in the battery of this invention is applicable to a positive electrode side and a negative electrode side.

  In the battery of the present invention, the exterior body, the power generation element housed in the exterior body, the sealing plate that seals the opening of the exterior body, and the sealing so as to penetrate the sealing plate A connection terminal attached to a plate, and the current generating element and a current collector electrically connected to the connection terminal, wherein the welding region is formed between the current collector and the connection terminal. It is good as it is.

  According to the battery of the present invention, the joint between the current collector and the connection terminal is connected by caulking and welding with a high energy ray, so that the internal resistance is reduced and the electric power can be obtained even in an environment with a lot of vibration. Resistance changes with time are less likely to occur, and a highly reliable battery can be obtained. In the battery of the present invention, the current collector may be caulked and fixed to the connection terminal, or the connection terminal may be caulked and fixed to the current collector. The battery of the present invention can also be applied to a battery having a built-in safety means such as a current interruption mechanism as a connection terminal. In addition, in the battery of this invention, a metal thing can be used as an exterior body, and a sealing board and a metal thing can also be used. If the sealing plate is made of metal, the connection terminal and the sealing plate may be electrically insulated with a gasket or an insulating plate.

  In the battery of the present invention, the exterior body, the power generation element housed in the exterior body, the sealing plate that seals the opening of the exterior body, and the sealing so as to penetrate the sealing plate A connection terminal attached to a plate, a current collector electrically connected to the power generation element and the connection terminal, and an external terminal electrically connected to the connection terminal, the welding region, It may be formed between the connection terminal and the external terminal, or between the current collector and the connection terminal, and between the connection terminal and the external terminal.

  According to the battery of the present invention, the connection between the connection terminal and the external terminal, or between the current collector and the connection terminal and between the connection terminal and the external terminal is fixed by caulking and welding with a high energy line. Thus, the internal resistance is reduced, and it is difficult for the electrical resistance to change with time even in an environment where there is a lot of vibration, and a battery with high reliability can be obtained. In the battery of the present invention, the connection terminal may be fixed to the external terminal by caulking, or the external terminal may be fixed to the connection terminal by caulking, and the connection terminal may be caulked to the current collector. While fixing and crimping to an external terminal, the current collector and the external terminal may be crimped to a connection terminal.

  In the battery of the present invention, the welding spot is formed in a state where three or more points overlap each other, one point on both ends is formed closer to one member, and at least one point on the intermediate side is one member. It is preferable that it is formed so as to straddle the boundary with the other member and that another point on both end sides is located on the other member side.

  In the battery of the present invention, even if the position of the end portion of the caulking portion of one member is shifted to one side of one member side or the other member side, it straddles between one member and the other member. Even if a small crack due to so-called solidification cracking occurs at the welding spot formed between one member and the other member, it can be reliably welded with a high energy beam. It is possible to prevent the residual welding spot from being left behind. Therefore, according to the battery of the present invention, it is possible to obtain a battery with higher internal resistance and less change in electrical resistance over time even in an environment with more vibrations and higher reliability.

  Moreover, in the battery of this invention, it is preferable that the last welding spot of the welding area | region by the said high energy ray is formed in the part only of the said one member, or the part only of the said other member.

  Even if a minute crack is generated due to solidification cracking in the welding spot, the crack can be eliminated at the next overlapping welding spot other than the final welding spot. Therefore, if the last welding spot is a part of only one member or a part of the other member, even if a crack remains in the last welding spot, one member and the other member There is no crack in the joint portion, and one member and the other member can be reliably connected. For this reason, according to the battery of the present invention, the above-described effect can be achieved better.

  In the battery of the present invention, the two or more overlapping welding spots are preferably formed from the crimped member side of the pair of conductive members toward the other member side. .

  The end of the crimped member in a state where it is not welded to the other member is hard to escape the applied heat and hits the joint in a state where only the crimped member is irradiated with high energy rays. Since the effect of preheating the end portion of the crimped member is increased, the member is melted with a small amount of heat input. Therefore, like the battery of the present invention, the high energy beam is scanned from the crimped member toward the other member, and the end of the crimped member is melted and connected to the other member. However, the power of the high energy beam to irradiate is less than the case where the other member side and the caulked side member are connected by scanning the high energy ray from the other member side toward the caulked member side. It will be over. Note that the scanning direction of the high energy beam can be easily determined from the overlap state of the welding spots.

  Moreover, in the battery of this invention, it is preferable that the said welding area | region is formed in multiple places along the boundary of the said crimped member.

  According to the battery of the present invention, if the mechanical area and electrical conductivity of the joint portion between one member and the other member are insufficient at a single welding region with a high energy beam, welding with a high energy beam is performed. It can be improved by having a plurality of regions. However, if there are too many welding areas with high energy rays, the areas where the caulking force was applied will melt and the caulking force will weaken, so the welding areas with multiple high energy rays should not overlap. It is preferable.

  Moreover, in the battery of this invention, it is preferable that the said welding area | region is formed in the symmetrical position along the boundary of the said crimped member.

  According to the battery of the present invention, when a force is applied to the crimping portion, a force is applied evenly to the welding region by the high energy ray, so that the strength of the joint portion between one member and the other member is increased, A battery with higher reliability can be obtained.

  In the battery of the present invention, the pair of conductive members can be applied to those made of an aluminum-based metal.

  A current collector, a connection terminal, an external terminal and the like made of an aluminum-based metal are often used particularly on the positive electrode side of a lithium ion secondary battery. Aluminum-based metals have a larger thermal expansion than steel and the like, and thus are liable to cause solidification cracking. In the battery of the present invention, even when the pair of conductive members are made of an aluminum-based metal, the above-described effect is satisfactorily achieved.

  In the battery of the present invention, the crimped member may be formed by deforming a cylindrical shape before the crimping by spinning caulking.

  In many cases, a large amount of force cannot be applied to the caulking portion in order to suppress deformation around the caulking portion. When a cylindrical member is subjected to spinning caulking, one member and the other member can be firmly caulked and fixed without applying a large force, but the spread of the caulking portion tends to vary. For this reason, it is generally difficult to combine spinning caulking and a welding method that concentrates high energy rays that are likely to cause poor welding due to misalignment in a small area. According to the battery of the present invention, the welding region by the high energy beam is formed by two or more overlapping welding spots in the direction intersecting the boundary between one member and the other member. Even if the position of the caulking boundary due to caulking changes, it becomes difficult to cause poor welding.

  In the battery according to the present invention, the crimped member may be formed by deforming a crisp pin shape before crimping.

  When the shape of the crimping portion is a cotter pin shape, it can be easily crimped and the dimensional stability of the crimping portion is improved, but the crimping strength is reduced. According to the battery of the present invention, not only the caulking fixing part but also the welding region by the high energy ray is formed, so that the internal resistance is reduced and the electrical resistance changes with time even in an environment with a lot of vibration. It becomes difficult to obtain a battery with high reliability.

  Further, in the battery of the present invention, the crimped member is in a through hole having a tapered counterbore hole formed in one member of the pair of conductive members, and is opposite to the counterbore hole. Therefore, it is preferable that the other member of the pair of conductive members is inserted and deformed so that the other member is in contact with the counterbore hole.

  When the tapered counterbore hole is formed in the through hole formed in one member, the heat capacity of the portion of the one member in which the tapered counterbore hole is formed becomes small. Therefore, according to the battery of the present invention, the balance with the heat capacity of the other member to be caulked becomes good, and a welded portion with a high energy beam of good quality can be obtained. Changes are less likely to occur and a battery with higher reliability can be obtained.

  In addition, unevenness occurs on the surface of the welding spot in the welded part using high energy rays. If the uneven surface does not protrude from the surface of one member in side view, the surface of one member is apparently flat. As a result, the dimensional stability is improved. If the present invention is applied when the spinning caulking is adopted for the other member, the dimensional stability and adhesion between the spinning caulking portion and the tapered counterbore hole are improved, and a higher quality battery is obtained. Is obtained. For example, when one of the counterbored holes is an external terminal, the surface of one of the members can be made flat so that it can be used for measuring equipment used for inspection and testing of battery quality and characteristics. This is preferable because the terminal can be stably contacted.

  In the battery of the present invention, a stepped portion having a diameter larger than the diameter of the tapered counterbore hole may be formed on the tapered counterbore hole side.

  In the welding region where the welding spot is formed by the high energy beam, the surface of the welding surface is uneven. If the uneven surface is within the stepped portion, the uneven surface of the welding region is one member when viewed from the side. Since the surface of the other member is not exposed, the surface of the other member appears to be a flat surface, and the dimensional stability is improved. In addition, the large-diameter stepped portion can suppress the spatter generated by the irradiation of high energy rays from being scattered outside the aperture.

  In order to achieve the above object, the battery manufacturing method of the present invention is a battery manufacturing method in which a pair of conductive members are fixed by caulking and welded regions are formed by welding with high energy beams. And caulking one of the pair of conductive members with respect to the other, and then scanning a high energy line in a direction intersecting a boundary portion between the one and the other of the pair of conductive members. To form a welding region consisting of two or more overlapping welding spots.

  Further, in the battery manufacturing method of the present invention, the battery includes an exterior body, a power generation element housed in the exterior body, a sealing plate that seals an opening of the exterior body, and the sealing plate. A connection terminal attached to the sealing plate so as to pass through the power generation element, and a current collector electrically connected to the power generation element and the connection terminal. You may form between the said connection terminals.

  Further, in the battery manufacturing method of the present invention, the battery includes an exterior body, a power generation element housed in the exterior body, a sealing plate that seals an opening of the exterior body, and the sealing plate. A connection terminal attached to the sealing plate so as to pass through, a current collector electrically connected to the power generation element and the connection terminal, and an external terminal electrically connected to the connection terminal, The welding region may be formed between the current collector and the connection terminal and between the connection terminal and the external terminal.

  In the battery manufacturing method of the present invention, the number of the welding spots in the welding region may be three or more. Moreover, in the battery manufacturing method of the present invention, the last welding spot of the welding region by the high energy ray may be formed only on the one member or only on the other member. In the battery manufacturing method of the present invention, the two or more overlapping welding spots may be formed from the crimped member side of the pair of conductive members toward the other member side. . Furthermore, in the battery manufacturing method of the present invention, the crimped member may be deformed by spinning caulking using a cylindrical shape before caulking.

  According to the battery manufacturing method of the present invention, the battery of the present invention that exhibits the above-described effects can be easily manufactured.

FIG. 1A is a perspective view in which an external terminal of a prismatic nonaqueous electrolyte secondary battery common to Examples and Comparative Examples is omitted, and FIG. 1B is an exploded perspective view of a connection terminal portion. It is a disassembled perspective view which shows the state which attaches an external terminal to a connection terminal. It is sectional drawing which shows the state which crimps and fixes a connecting terminal to an external terminal by spinning caulking. 4A is a plan view showing a state in which the connection terminal is inserted into the hole of the external terminal, FIG. 4B is a cross-sectional view taken along line IVB-IVB in FIG. 4A, and FIG. 4D is a cross-sectional view taken along the line IVD-IVD in FIG. 4C. 5A is a plan view when a single welding spot is formed in Comparative Example 1, FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. 5A, and FIG. 5C is a single welding spot in Comparative Example 2. 5D is a cross-sectional view taken along the line VD-VD in FIG. 5C. 6A is a plan view when the welding region of Example 1 is formed, FIG. 6B is a cross-sectional view taken along line VIB-VIB of FIG. 6A, and FIG. 6C is a state where the welding region of Example 2 is formed. FIG. 6D is a cross-sectional view taken along the line VID-VID in FIG. 6C. 7A is a plan view when a single welding spot is formed in Comparative Example 3, FIG. 7B is a cross-sectional view taken along the line VIIB-VIIB in FIG. 7A, and FIG. 7D is a cross-sectional view taken along the line VIID-VIID in FIG. 7C. FIG. 8A is a partial cross-sectional view of the first modification, FIG. 8B is a plan view before caulking of the second modification, and FIG. 8C is a caulking and welding region of the second modification. It is a top view of a state. FIG. 9A is a cross-sectional view showing a processing step of the tip of a crimped portion of a conventional terminal, FIG. 9B is a view showing a laser welding step after the step of FIG. 9A, and FIG. 9C is a plan view of FIG. FIG. 9D is a plan view after laser welding is repeated a plurality of times so that a plurality of welding spots overlap each other.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings by way of examples and comparative examples. However, the embodiment described below exemplifies a connection form between a connection terminal and an external terminal in a prismatic nonaqueous electrolyte secondary battery for embodying the technical idea of the present invention. It is not intended to specify only the connection form between the connection terminal and the external terminal, and the present invention is also applicable to the connection form between the current collector inside the battery and the connection terminal. Further, the present invention is not limited to prismatic nonaqueous electrolyte secondary batteries, but also for primary batteries and secondary batteries, for both cylindrical batteries and prismatic batteries, and for nonaqueous batteries. The present invention is equally applicable not only to a battery using an electrolyte but also to a battery using an aqueous electrolyte. In the present invention, either a laser beam or an electron beam can be used as the high energy beam used for welding. In the following, the laser beam will be described as a representative example.

  First, a prismatic nonaqueous electrolyte secondary battery as a battery common to Examples and Comparative Examples will be described with reference to FIG. 1A is a perspective view in which the external terminals of the rectangular nonaqueous electrolyte secondary battery common to the examples and the comparative examples are omitted, and FIG. 1B is an exploded perspective view of the connection terminal portion. In FIG. 1A, the gasket 15 is not shown.

  This rectangular non-aqueous electrolyte secondary battery 10 includes a flat power generation element (both not shown) in which a positive electrode plate and a negative electrode plate are wound or stacked with a separator interposed therebetween. The battery outer can 11 is enclosed inside and sealed with a sealing plate 12. And the positive electrode connection terminal 13 and the negative electrode connection terminal 14 are provided in the state insulated from the sealing plate 12 with the gasket 15 and the insulating member 16 so that the sealing plate 12 might be penetrated.

  Here, the configuration of the power generation element used in the prismatic nonaqueous electrolyte secondary battery 10 will be briefly described. The positive electrode plate is coated with a positive electrode active material mixture and rolled after drying so that a positive electrode core exposed portion in which the strip-shaped aluminum foil is exposed is formed on both surfaces of the positive electrode core made of aluminum foil. It is produced by. Further, the negative electrode plate is coated with a negative electrode active material mixture so that a negative electrode core exposed portion where the strip-shaped copper foil is exposed is formed on both surfaces of the negative electrode core made of copper foil, and after drying It is produced by rolling. The flat power generation element is made of a microporous material made of polyolefin such that the positive electrode plate and the negative electrode plate are positioned at both ends in the winding axis direction so that the positive electrode core exposed portion and the negative electrode core exposed portion are located respectively. It is produced by winding or laminating in a flat shape via a separator.

  Among these, the positive electrode core exposed portion is connected to the positive electrode connecting terminal 13 via the positive electrode current collector, and the negative electrode core exposed portion is connected to the negative electrode connecting terminal 14 via the negative electrode current collector. The positive electrode connection terminal 13 and the negative electrode connection terminal 14 are each fixed to the sealing plate 12 via an insulating member. In this rectangular nonaqueous electrolyte secondary battery 10, a flat power generation element is inserted into a rectangular battery outer can 11, and then a sealing plate 12 is laser welded to the opening of the battery outer can 11, and then an electrolyte solution is injected. The non-aqueous electrolyte is injected from a hole (not shown), and the electrolyte injection hole is sealed.

  Here, a specific configuration of the positive electrode connection terminal 13 and the negative electrode connection terminal 14 will be described. Usually, the positive electrode current collector and the positive electrode connection terminal 13 are formed of an aluminum-based metal such as aluminum or an aluminum alloy. Although the current collector and the negative electrode connection terminal 14 are different from each other in that they are formed of a copper-based metal such as copper or a copper alloy, other configurations are substantially the same. To explain.

  As shown in FIG. 1A, the positive electrode connection terminal 13 is connected to a cylindrical first caulking member 13b formed on one side of the flange portion 13a and an external terminal formed on the other end side of the flange portion 13a. And a cylindrical second caulking member 13c for fixing. The cylindrical first caulking member 13b is assembled by being inserted into openings formed in the gasket 15, the sealing plate 12, the insulating member 16, and the positive electrode current collector 17, respectively.

  In this assembled state, the second caulking member 13c is placed on a jig (not shown) so that the second caulking member 13c faces downward, and the caulking is performed so that the diameter of the first caulking member 13b expands in the same direction from the front end side. At the same time, the first caulking member 13b of the positive electrode connection terminal 13 and the positive electrode current collector 17 are firmly connected electrically and mechanically by laser welding as appropriate. It should be noted that the caulking and laser welding between the first caulking member 13b of the positive electrode connecting terminal 13 and the positive electrode current collector 17 are performed in accordance with the second caulking member 13c of the positive electrode connecting terminal 13 and the external terminal described in detail below. 18 (refer to FIG. 2), since it can be performed in the same manner as the caulking and laser welding between them, a specific description is omitted here.

  With respect to the positive electrode connection terminal 13 of the prismatic nonaqueous electrolyte secondary battery 10 thus manufactured, an external terminal attachment process common to the examples and the comparative examples will be described with reference to FIGS. FIG. 2 is an exploded perspective view showing a state in which the external terminal is attached to the connection terminal. FIG. 3 is a cross-sectional view showing a state in which the connection terminal is caulked and fixed to the external terminal by spinning caulking. 4A is a plan view showing a state in which the connection terminal is inserted into the hole of the external terminal, FIG. 4B is a cross-sectional view taken along line IVB-IVB in FIG. 4A, and FIG. 4C is a plan view showing a state where spinning caulking is performed. 4D is a cross-sectional view taken along the line IVD-IVD in FIG. 4C. In FIG. 2, insulating members such as the gasket 15 are not shown.

  The positive external terminal 18 used here has a Z-fitting shape, is made of the same aluminum-based metal as the positive connection terminal 13, and has openings 18 a and 18 b on both ends. Among them, the opening 18a on the upper end side is for connecting the plurality of rectangular nonaqueous electrolyte secondary batteries 10 in series and parallel or to connect with external wiring, and the opening 18b on the lower end side is connected to the positive electrode connection terminal 13. It is for connecting. A tapered counterbore 18c is formed in the upper part of the opening 18b on the lower end side so that the inner diameter of the opening 18b is increased.

  First, when the cylindrical second caulking member 13c is inserted into the opening 18b on the lower end side of the positive electrode external terminal 18 from below, the state shown in FIGS. 4A and 4B is obtained. In this state, spinning caulking is performed using the spinning caulking jig 20 as shown in FIG. 3 such that the diameter of the cylindrical second caulking member 13c is increased from the upper side. The spinning caulking jig 20 is processed so that the tip end portion 20a has a reduced diameter, and rotates around an axis φ2 that is eccentric from the central axis φ1 of the cylindrical second caulking member 13c. The caulking member 13c is driven to rotate about the central axis φ1. Thereby, the tip end side of the cylindrical second caulking member 13c is expanded and caulked and fixed to the surface of the tapered counterbore hole 18c of the positive electrode external terminal 18, resulting in the state shown in FIGS. 4C and 4D.

  According to this spinning caulking, the tip side of the cylindrical second caulking member 13c of the positive electrode connection terminal 13 is firmly caulked to the surface of the tapered counterbore hole 18c of the positive electrode external terminal 18 without applying a large force. Since it can be fixed, a large force is not applied to the gasket 15 and the insulating member 16 (see FIG. 1B), and it is difficult to break.

  Next, laser welding between the positive electrode connection terminal 13 and the positive electrode external terminal 18 integrated by spinning caulking will be described with reference to FIGS. 5A is a plan view at the time of forming a single welding spot in Comparative Example 1, FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. 5A, and FIG. FIG. 5D is a cross-sectional view taken along line VD-VD in FIG. 5C. 6A is a plan view when the welding region of Example 1 is formed, FIG. 6B is a cross-sectional view taken along the line VIB-VIB of FIG. 6A, and FIG. 6C is a welding region of Example 2. 6D is a cross-sectional view taken along line VID-VID in FIG. 6C.

  First, a phenomenon that occurs when spot welding is performed at one point by laser welding will be described with reference to FIG. 5A is a plan view at the time of forming a single welding spot corresponding to Comparative Example 1 in which the crimped portion is formed relatively uniformly. 5B is a cross-sectional view taken along line VB-VB in FIG. 5A. FIG. 5C is a plan view showing a state in which a single welding spot corresponding to Comparative Example 2 in which crimping portions are formed unevenly is formed. 5D is a cross-sectional view taken along line VD-VD in FIG. 5C. 5A to 5D, the same components as those in FIGS. 4A to 4D are denoted by the same reference numerals, and detailed description thereof is omitted.

  In laser welding, the positive electrode connection terminal 13 and the positive electrode external terminal 18 are integrated and placed on a jig (not shown), and the jig is rotated about the central axis φ by 90 °, for example. Four-point spot welding is automatically performed. Note that the central axis φ of the jig coincides with the central axis φ1 of the cylindrical second caulking member 13c (see FIG. 3). In this case, the irradiation position of the laser beam LB is fixed in advance so that the tip side of the second caulking member 13 c and the tapered counterbore hole 18 c of the positive electrode external terminal 18 are simultaneously irradiated.

  Then, when the leading end side of the cylindrical second crimping member 13c of the positive electrode connection terminal 13 is fixed to the surface of the tapered counterbore hole 18c of the positive electrode external terminal 18 by spinning caulking, it is shown in FIGS. 5A and 5B. As described above, since the laser beam LB is simultaneously irradiated to the tip side of the second crimping member 13c and the tapered counterbore 18c of the positive external terminal 18, favorable welding spots 21 to 24 are formed. .

  However, the spinning caulking can firmly fix the member to be caulked and the other member without applying a large force, but has the property that the spread of the caulking portion tends to vary. In addition, since the variation of the dimension of such a crimping process part is due to the plastic deformation of the raw material to be crimped, even when other crimping processes are employed, it similarly occurs.

  For this reason, for example, as shown in FIGS. 5C and 5D, there is a case in which the caulking portion at the right end portion in FIG. In this case, since the irradiation position of the laser beam LB is fixed in advance, the laser beam LB is on the distal end side of the second crimping member 13c of the positive electrode connection terminal 13 in the portion where the spread of the crimped portion at the right end portion in FIG. In some cases, only the tapered counterbore hole 18c of the positive electrode external terminal 18 is irradiated.

  In such a state, the welding spot 24 at the right end portion of FIG. 5C is formed only in the tapered counterbore 18c of the positive external terminal 18 as shown in FIG. In the meantime, no welding spot is formed, and the effect of laser welding is not achieved. Here, an example is shown in which the extent of the caulking portion due to spinning caulking has been reduced. However, when the extent of the caulking portion due to spinning caulking has become large, conversely, welding is performed only on the positive electrode connection terminal 13. A spot is formed, and a welding spot is not formed in the tapered counterbore hole 18 c of the positive electrode external terminal 18.

  The problem due to the dimensional variation of the caulking portion is that the tip side of the second caulking member 13 of the positive electrode connection terminal 13 of the conventional example and the tapered counterbore hole 18c of the positive electrode external terminal 18 as shown in FIG. 9D. It is not possible to solve this problem by forming a plurality of welding spots that overlap each other along the boundary. The reason is that the weld spot formation position is automatically corrected by detecting the boundary position between the tip end side of the second crimping member 13 of the positive electrode connection terminal 13 and the tapered counterbore hole 18 c of the positive electrode external terminal 18. Because it is not something.

  Therefore, in the present invention, as shown in FIGS. 6A and 6B, from the second caulking member 13c side of the positive electrode connection terminal 13 to beyond the tip end side thereof, the tapered counterbore hole 18c side of the positive electrode external terminal 18 is provided. In the meantime, two or more overlapping welding spots are formed by scanning the irradiation position of the laser beam LB. 6A and 6B show a case where the tip end side of the cylindrical second caulking member 13c of the positive electrode connection terminal 13 is fixed to the surface of the tapered counterbore hole 18c of the positive electrode external terminal 18 without variation by spinning caulking. 6C and 6D show a case where the expansion of the crimped portion at the right end portion of FIG. 6C is small.

  In the example shown in FIG. 6A and FIG. 6B corresponding to the first embodiment, the first welding spot 21a is formed so as to be positioned only on the second crimping member 13c side of the first welding spot 21a positive electrode connection terminal 13 by irradiation with the first laser beam LB. Next, the irradiation position of the laser beam LB is shifted to the tapered counterbore 18c side so that the second welding spot BR> G21b is overlapped with the first welding spot 21a, and the laser beam LB is further formed. The first welding region 21 is formed by shifting the irradiation position to the positive electrode external terminal 18 side and forming the third welding spot 21c so as to overlap the second welding spot 21b. Such welding regions 21 to 24 by laser light are formed, for example, at four locations so that the respective welding regions 21 to 24 are in symmetrical positions. In this case, the pitch of the welding spots is preferably about 50 to 200 μm so that the degree of overlap is appropriate.

  In this case, as shown in FIG. 6C and FIG. 6D corresponding to Example 2, the first welding spots 21a to 24a and the third welding spots 21c to 24c in the respective welding regions 21 to 24 are respectively positive electrode connection terminals. 13, the second welding spots 21 b to 24 b are located on the second caulking member 13 c side of the positive electrode connecting terminal 13 and the positive electrode external terminal 18. It is formed across both sides.

  In such a state, even if there is a variation in the position of the tip side of the cylindrical second caulking member 13c of the positive electrode connection terminal 13 due to spinning caulking, the positive electrode connecting terminal 13 and the positive electrode member 13c side and the positive electrode A welding spot can be reliably formed between the external terminals 18. Therefore, according to the prismatic nonaqueous electrolyte secondary battery described in Examples 1 and 2 including the welding regions 21 to 24 as illustrated in FIGS. 6A to 6D, the positive electrode connection terminal 13 and the positive electrode external terminal 18 Since the joint between the two is firmly fixed by caulking and welding with the laser beam LB, the internal resistance is reduced, and the electrical resistance is less likely to change over time even in an environment where there is a lot of vibration. A high prismatic nonaqueous electrolyte secondary battery is obtained.

  Note that such overlapping welding spots are directed in the radial direction from the center axis φ side of the jig, that is, from the center side of the cylindrical second caulking member 13c of the positive electrode connection terminal 13 to the positive electrode external terminal 18. It is good to form toward the side. The reason is that the heat applied by the laser beam LB is difficult to escape from the end portion of the positive electrode connection terminal 13 that is not welded to the positive electrode external terminal 18, so that only the positive electrode connection terminal 13 is irradiated with the laser beam LB. In this state, the effect of preheating the end portion of the positive electrode connection terminal 13 corresponding to the joint portion is increased, so that the melting is performed with a small amount of heat input. Therefore, the laser beam LB is scanned from the positive electrode connection terminal 13 side toward the tapered counterbore hole 18 c of the positive electrode external terminal 18 to melt the end portion of the positive electrode connection terminal 13, and the tapered counterbore hole of the positive electrode external terminal 18. In the case of connecting to 18c, the laser beam LB is scanned from the tapered counterbored hole 18c side of the positive electrode external terminal 18 toward the positive electrode connecting terminal 13 side, and the tapered counterbore hole 18c of the positive electrode external terminal 18 and the positive electrode connecting terminal are scanned. Therefore, the power of the laser beam LB to be irradiated can be smaller than that in the case where the power source 13 is connected.

  In Examples 1 and 2, an example in which three overlapped welding spots in each of the welding regions 21 to 24 are formed is shown. However, if the number is two or more, a good effect can be obtained. Play. However, if there are two each, the first welding spot and the last welding spot of each welding region are respectively only on the second crimping member 13c side of the positive electrode connection terminal 13 or the tapered counterbore hole of the positive electrode external terminal 18 It becomes impossible to make it the state located only in the 18c side. For this reason, the number of overlapped welding spots in each welding region is preferably 3 or more, but it is useless even if it is too much, so it is preferable to keep the number around 4 each.

  In addition, the number of each welded area can have a certain effect even at one place. However, if the mechanical strength and electrical conductivity of the joint are insufficient, it is assumed that there are a plurality of places. Depending on the number of regions, the mechanical strength and electrical conductivity of the joint can be improved. However, even if there are too many welding areas, the caulking force is weakened by melting the portion where the caulking force was applied. It is preferable.

  Furthermore, when the plurality of welding regions are formed so as to be symmetrical around the second crimping member 13c of the positive electrode connection terminal 13, when a force is applied to the crimping portion, overlapping welding spots are formed. Since the force is evenly applied to the region, the strength of the joint between the positive electrode connection terminal 13 and the positive electrode external terminal 18 is further increased.

  Next, the case where the micro crack accompanying solidification is formed in the welding spot will be described with reference to FIG. 7A is a plan view when forming a single welding spot corresponding to Comparative Example 3, FIG. 7B is a cross-sectional view taken along the line VIIB-VIIB in FIG. 7A, and FIG. 7C corresponds to Example 3. FIG. 7D is a cross-sectional view taken along the line VIID-VIID of FIG. 7C.

  For example, when a metal having a large coefficient of thermal expansion such as an aluminum-based metal is used as the positive electrode connection terminal 13 and the positive electrode external terminal 18, the single welding spot is solidified as shown in the welding spot 24 of FIG. 7A. Accompanying this, a minute crack 25 may be formed. In a single welding spot corresponding to Comparative Example 3 shown in FIG. 7A, such a microcrack 25 of the welding spot 24 does not disappear, so that the mechanical strength of the welding spot becomes small.

  On the other hand, in the welding region 24 shown in FIG. 7B corresponding to Example 3, even if a minute crack is formed in the first welding spot as it solidifies, the weld crack portion is formed in an overlapped state thereafter. Disappears due to the welding spot. Even if a minute crack is formed in the last welding spot as it solidifies, the last welding spot is formed on the tapered counterbore 18c of the positive electrode external terminal 18, so that the positive electrode connection terminal 13 and the positive electrode external The mechanical strength and electrical resistance of the joint between the terminals 18 are not affected.

  In the above-described Examples 1 to 3, an example in which a tapered counterbore 18c is formed on the upper side of the opening 18b of the positive electrode external terminal 18 is shown. However, such a tapered counterbore hole is used. When the one formed with 18c is used, the portion of the positive external terminal 18 where the tapered counterbore hole is formed has a small heat capacity. Therefore, the heat capacity of the cylindrical second caulking member 13c of the positive electrode connecting terminal 13 to be crimped And a good quality welding spot can be obtained. In addition, the welding spot formed by the laser beam LB has irregularities on the surface. If the irregularity surface cannot be seen from the surface of the positive electrode external terminal 18 in a side view, the apparent positive external terminal 18 The surface remains flat and dimensional stability is improved.

  Further, by forming this large-diameter stepped portion, it is possible to suppress the spatter generated by the irradiation of the high energy ray from being scattered outside the opening 18 b of the positive electrode external terminal 18. Therefore, it is possible to prevent the spatter from adhering to the surface of the positive electrode external terminal 18 and to make the surface of the positive electrode external terminal 18 flat with more certainty. As a result, the measurement terminal of the device used for the inspection / test of the quality and characteristics of the battery can be brought into stable contact with the surface of the positive electrode external terminal 18. Such an effect is not limited to the form formed by two or more overlapping welding spots in the direction intersecting the boundary between one and the other of the pair of conductive members as in the present invention, but the prior art. As described above, a continuous welded portion or weld spot is formed along the boundary between one and the other of the pair of conductive members.

  Further, in the present invention, as shown in FIG. 8A which is a partial sectional view of the first modification, the upper end side of the tapered counterbore hole as the positive electrode external terminal 18 is larger than the diameter of the counterbore hole 18c. You may use the thing in which the level | step-difference part 18d of diameter is formed. By adopting such a configuration, even if unevenness is generated on the surface of the welding spot formed by the laser beam LB, the uneven surface of the welding region 26 formed by this welding spot is the side of the positive electrode external terminal 18 in a side view. If it cannot be visually recognized from the surface, the surface of the apparent positive external terminal 18 remains a flat surface, and the dimensional stability is improved.

  Further, in the present invention, as shown in FIGS. 8B and 8C, which are a plan view before caulking and a plan view in a state where caulking and welding areas are formed in the second modified example, The caulking portion may be a split pin-shaped caulking portion 13d. When such a configuration is adopted, it can be easily caulked and the dimensional stability of the caulking portion is improved. On the other hand, the caulking strength is smaller than that in the case of spinning caulking, but further, since the welding region 26 is formed by the laser beam LB, the internal resistance is reduced and the electrical resistance changes with time even in an environment with a lot of vibration. This makes it difficult to obtain a battery with high reliability.

  Furthermore, although not shown in the drawings, the present invention can be applied to those having a well-known buckling caulking portion as the caulking portion, and as disclosed in Patent Document 4 as the positive electrode connecting terminal 13. The present invention is also applicable to a device incorporating a safety means such as a current interruption mechanism.

10: prismatic nonaqueous electrolyte secondary battery 11: battery outer can 12: sealing plate 13: positive electrode connection terminal 13a: collar 13b: first caulking member 13c: second caulking member 13d: split pin caulking member 14 : Negative electrode connection terminal 15: Gasket 16: Insulating member 17: Positive electrode current collector 18: Positive electrode external terminal 18 a: Opening on the upper end side 18 b: Opening on the lower end side 18 c: Tapered counterbore hole 18 d: Stepped portion 20: Spinning Caulking jig 20a: Tip portion (of spinning caulking jig) 21: Welding area 21a-21d: Welding spot 22: Welding area 22a-22d: Welding spot 23: Welding area 23a-23d: Welding spot 24: Welding area 24a- 24d: Welding spot 25: Minute crack 26: Welding area

Claims (20)

A battery in which a welding region is formed in which a pair of conductive members are caulked and welded to each other by high energy rays,
The battery is characterized in that the welding region is formed by two or more overlapping welding spots in a direction intersecting a boundary portion between one and the other of the pair of conductive members. The battery is attached to the sealing plate so as to penetrate the sealing plate, the power generation element housed inside the outer packaging, the sealing plate that seals the opening of the outer packaging, and the sealing plate. A connection terminal; and a current collector electrically connected to the power generation element and the connection terminal,
The battery according to claim 1, wherein the welding region is formed between the current collector and the connection terminal. The battery is attached to the sealing plate so as to penetrate the sealing plate, the power generation element housed inside the outer packaging, the sealing plate that seals the opening of the outer packaging, and the sealing plate. A connection terminal, a current collector electrically connected to the power generation element and the connection terminal, and an external terminal electrically connected to the connection terminal,
The welding region is formed between the connection terminal and the external terminal, or between the current collector and the connection terminal and between the connection terminal and the external terminal. The battery according to claim 1.   The welding spot is formed in a state where three or more points overlap each other, one point on both ends is formed closer to one member, and at least one point on the intermediate side straddles the boundary between one member and the other member. 2. The battery according to claim 1, wherein the battery is formed such that another point on both ends is located on the other member side.   5. The battery according to claim 4, wherein the last welding spot of the welding area by the high energy ray is formed in a portion of only the one member or a portion of only the other member.   2. The battery according to claim 1, wherein the two or more overlapping welding spots are formed from a crimped member side of the pair of conductive members toward the other member side. .   The battery according to claim 1, wherein the welding region is formed at a plurality of locations along a boundary of the crimped member.   The battery according to claim 7, wherein the welding region is formed at a symmetrical position along a boundary of the crimped member.   The battery according to claim 1, wherein each of the pair of conductive members is made of an aluminum-based metal.   2. The battery according to claim 1, wherein the crimped member is formed by deforming a cylindrical shape before crimping by spinning caulking. 3.   2. The battery according to claim 1, wherein the crimped member is formed by deforming one having a cotter pin shape before crimping. 3.   The crimped member is formed in a through hole having a tapered counterbore hole formed in one member of the pair of conductive members, and from the side opposite to the counterbore hole, The battery according to claim 1, wherein the other member is inserted and deformed so that the other member contacts the counterbore hole.   The battery according to claim 12, wherein a step portion having a diameter larger than the diameter of the tapered counterbore hole is formed on the tapered counterbore hole side. A method for manufacturing a battery in which a welding region is formed in which a pair of conductive members are fixed by caulking and welded to each other by a high energy beam,
Two or more points are obtained by caulking one of the pair of conductive members with respect to the other, and then scanning a high energy beam in a direction intersecting the boundary between one and the other of the pair of conductive members. A method for manufacturing a battery, comprising forming a welding region consisting of overlapping welding spots. The battery is attached to the sealing plate so as to penetrate the sealing plate, the power generation element housed inside the outer packaging, the sealing plate that seals the opening of the outer packaging, and the sealing plate. A connection terminal; and a current collector electrically connected to the power generation element and the connection terminal.
The battery manufacturing method according to claim 14, wherein the welding region is formed between the current collector and the connection terminal. The battery is attached to the sealing plate so as to penetrate the sealing plate, the power generation element housed inside the outer packaging, the sealing plate that seals the opening of the outer packaging, and the sealing plate. A connection terminal, a current collector electrically connected to the power generation element and the connection terminal, and an external terminal electrically connected to the connection terminal,
The method for manufacturing a battery according to claim 14, wherein the welding region is formed between the current collector and the connection terminal and between the connection terminal and the external terminal.   The battery manufacturing method according to claim 14, wherein the number of the welding spots in the welding region is three or more.   18. The method for manufacturing a battery according to claim 14, wherein the last welding spot of the welding area by the high energy ray is formed only on the one member or only on the other member.   18. The weld spot having two or more overlapping points is formed from a crimped member side of the pair of conductive members toward the other member side. 18. Battery manufacturing method.   18. The battery manufacturing method according to claim 14, wherein the crimped member is deformed by spinning caulking using a cylindrical shape before caulking.