Method for manufacturing a battery

Abstract

Provided are a welding structure and a method for manufacturing the same, a battery and a method for manufacturing the same. The method for manufacturing a welding structure formed by joining metal members (10, 20) includes a step of bringing the metal members (10, 20) into contact with each other to form a space (SP) surrounded by the metal members (10, 20). A pressure relief port (20h1) is formed in at least one of the metal members (10, 20) between the metal members (10, 20). The method for manufacturing the welding structure further includes: performing a suction operation on the space (SP) through the pressure relief port (20h1) to reduce the pressure in the space (SP), so that a first portion (11a) of the metal member (10) contacts a second portion (21a) of the metal member (20), or the distance between the first portion (11a) and the second portion (21a) is smaller than the case where the space (SP) is not depressurized; and a step of welding the first portion (11a) and the second portion (21a) to each other in a state where the space (SP) has been depressurized.

Description

Technical Field

[0001] The present disclosure relates to a welded structure and a method for manufacturing the same, and a battery and a method for manufacturing the same. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2019-181496 discloses a laser welding method capable of easily joining metal plates to each other even when the gap generated between the metal plates is large. Summary of the Invention

[0003] In the present disclosure, there are provided a welded structure in which metal members are more sufficiently joined to each other and a method for manufacturing the same, and a battery in which electrode terminals of battery cells are more sufficiently joined to each other and a method for manufacturing the same.

[0004] The method for manufacturing a welded structure according to the present disclosure is a method for manufacturing a welded structure in which a first metal member and a second metal member are joined to each other by welding, and includes a step of bringing the first metal member and the second metal member into contact with each other to form a space surrounded by the first metal member and the second metal member. Among them, a reduced pressure port is formed between the first metal member and the second metal member or in at least one of the first metal member and the second metal member. The method for manufacturing the welded structure further includes: performing a suction operation on the space through the reduced pressure port to reduce the pressure of the space, so that a first portion of the first metal member contacts a second portion of the second metal member, or the distance between the first portion of the first metal member and the second portion of the second metal member is smaller than the case where the space is not depressurized; and a step of welding the first portion of the first metal member and the second portion of the second metal member to each other in a state where the space has been depressurized.

[0005] In the method for manufacturing the welded structure, the first metal member may be formed of copper and the second metal member may be formed of aluminum.

[0006] In the method for manufacturing the welded structure, laser light traveling from the side of the second portion of the second metal member toward the side of the first portion of the first metal member may be irradiated onto the outer surface of the second metal member, so that the first portion of the first metal member and the second portion of the second metal member are welded to each other.

[0007] In the method for manufacturing the above-described welded structure, the first metal member may have a bottom plate portion and a peripheral wall portion surrounding the periphery of the bottom plate portion. The space is formed by being partitioned by the bottom plate portion, the peripheral wall portion, and the second metal member. A convex portion is provided on the bottom plate portion, and the convex portion protrudes from the bottom plate portion. The distal end of the convex portion in the protruding direction defines the first portion, and the portion of the second metal member facing the first portion defines the second portion.

[0008] The method for manufacturing a battery according to the present disclosure includes: a step of laminating a first battery unit having a first electrode terminal and a second battery unit having a second electrode terminal; and a step of forming a welded structure in which the first electrode terminal as the first metal member and the second electrode terminal as the second metal member are welded to each other by using the method for manufacturing the above-described welded structure according to the present disclosure.

[0009] In the method for manufacturing the above-described battery, when the direction in which the first battery unit and the second battery unit are laminated is defined as the lamination direction and the direction intersecting the lamination direction is defined as the intersecting direction, the first electrode terminal may have: a first protruding portion that protrudes from the main body portion of the first battery unit in the intersecting direction; a first bent portion formed at the distal end of the first protruding portion in the protruding direction; and a first joint portion that extends from the first bent portion along a direction parallel to the lamination direction. The second electrode terminal may have: a second protruding portion that protrudes from the main body portion of the second battery unit in the intersecting direction; a second bent portion formed at the distal end of the second protruding portion in the protruding direction; and a second joint portion that extends from the second bent portion along a direction parallel to the lamination direction. The first joint portion and the second joint portion are welded to each other to form the above-described welded structure.

[0010] The welded structure according to the present disclosure includes a first metal member and a second metal member joined to the first metal member by welding. The first metal member and the second metal member are in contact with each other to form a space surrounded by the first metal member and the second metal member. A pressure relief port is formed in at least one of the first metal member and the second metal member or between the first metal member and the second metal member. The first metal member has a bottom plate portion and a peripheral wall portion surrounding the periphery of the bottom plate portion. The space is formed by being partitioned by the bottom plate portion, the peripheral wall portion, and the second metal member. A convex portion is provided on the bottom plate portion, and the convex portion protrudes from the bottom plate portion. The distal end of the convex portion in the protruding direction and the portion of the second metal member facing the distal end are welded to each other.

[0011] The battery according to the present disclosure includes: a first battery unit having a first electrode terminal; and a second battery unit having a second electrode terminal and laminated on the first battery unit. The welding structure according to the present disclosure is formed by welding the first electrode terminal as the first metal member and the second electrode terminal as the second metal member to each other.

[0012] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention understood in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FIG. is a perspective view showing welding structures 30a and 30b formed by the first battery unit 1 and the second battery unit 2 included in the battery 100.

[0014] Figure 2 FIG. is a perspective view showing a state in which the first battery unit 1 and the second battery unit 2 included in the battery 100 are separated from each other.

[0015] Figure 3 FIG. is a perspective view of a cross-section viewed along line III-III in Figure 1 .

[0016] Figure 4 FIG. is a perspective view showing a situation when the electrode terminal 10 and the electrode terminal 20 are joined by welding.

[0017] Figure 5 FIG. is a cross-sectional view viewed along line V-V in Figure 3 .

[0018] Figure 6 FIG. is a cross-sectional view viewed along line VI-VI in Figure 3 .

[0019] Figure 7 FIG. is a cross-sectional view viewed along line VII-VII in Figure 3 .

[0020] Figure 8 FIG. is a cross-sectional view for explaining a manufacturing method of the welding structure of Comparative Example 1.

[0021] Figure 9 FIG. is a cross-sectional view for explaining a manufacturing method of the welding structure of Comparative Example 2.

[0022] Figure 10 FIG. is a cross-sectional view for explaining a manufacturing method of the welding structure of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of the present disclosure will be described below. In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of the present disclosure is not necessarily limited to such number, quantity, etc. Regarding each component, unless otherwise specified, it is not necessarily essential for the present disclosure. Sometimes the same reference numerals are attached to the same components and equivalent components without repeated description.

[0024] [Battery 100]

[0025] Figure 1 It is a perspective view showing the welding structures 30a and 30b formed by the first battery unit 1 and the second battery unit 2 included in the battery 100. The battery 100 can be mounted on vehicles such as hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles.

[0026] The battery 100 includes a first battery unit 1 and a second battery unit 2 laminated on the first battery unit 1. The number of battery units included in the battery 100 is not particularly limited. As an example of the battery unit, a lithium-ion battery is cited, for example. Figure 2 It is a perspective view showing a state in which the first battery unit 1 and the second battery unit 2 included in the battery 100 are separated from each other.

[0027] Figure 1 、 Figure 2 In it, the lamination direction AR, which is the direction in which the first battery unit 1 and the second battery unit 2 are laminated, is shown by an arrow. Figure 1 In it, the crossing direction CR (here, as an example, an orthogonal direction), which is the direction crossing the lamination direction AR, is also shown by an arrow. In other drawings ( Figures 3 to 10 ), the lamination direction AR and the crossing direction CR defined here are also shown.

[0028] The first battery unit 1 includes a main body portion 1a, an electrode terminal 10 (first electrode terminal), and an electrode terminal 18 ( Figure 2 ). The first battery unit 1 is, for example, a laminated type unit. Although detailed illustration is omitted, in the main body portion 1a of the first battery unit 1, a power generation element is constituted by laminating a plurality of electrode bodies, and the power generation element is sealed together with an electrolyte by a laminate film, and the main body portion 1a as a whole has a flat shape. The electrode terminal 10 protrudes from one side of the main body portion 1a in the crossing direction CR, and the electrode terminal 18 protrudes from the other side of the main body portion 1a in the crossing direction CR.

[0029] The second battery unit 2 includes a main body portion 2a, an electrode terminal 20 (second electrode terminal), and an electrode terminal 28 ( Figure 2)。The second battery unit 2 is, for example, a laminated type unit. Although detailed illustrations are omitted, in the main body 2a of the second battery unit 2, a power generation element is formed by laminating a plurality of electrode bodies, and the power generation element is sealed with a composite film, and the main body 2a as a whole has a flat shape. The electrode terminal 20 protrudes from one side of the main body 2a in the crossing direction CR, and the electrode terminal 28 protrudes from the other side of the main body 2a in the crossing direction CR.

[0030] [Welding structures 30a, 30b]

[0031] The battery 100 includes welding structures 30a, 30b ( Figure 1 ). The welding structures 30a, 30b are formed by joining the electrode terminal 10 of the first battery unit 1 and the electrode terminal 20 of the second battery unit 2 to each other by welding.

[0032] The electrode terminal 10 functions as the first metal member in the welding structures 30a, 30b. The electrode terminal 10 is, for example, a negative electrode terminal and is formed of copper. The electrode terminal 20 functions as the second metal member in the welding structures 30a, 30b. The electrode terminal 20 is, for example, a positive electrode terminal and is formed of aluminum. Only one of the welding structures 30a, 30b may be formed in the battery 100.

[0033] Figure 3 To be along Figure 1 in the III-III line of the perspective cross-sectional view. In Figure 1 , the state where the electrode terminals 10, 20 are joined to each other by welding is shown. On the other hand, for ease of explanation, in Figure 3 , the state before the electrode terminals 10, 20 are joined to each other by welding is shown.

[0034] (Electrode terminal 10 (the first metal member))

[0035] The electrode terminal 10 (refer to Figure 1 , Figure 2 ) has: a first protruding portion 10a that protrudes from the main body 1a of the first battery unit 1 in the crossing direction CR; a first bending portion 10b formed at the tip of the first protruding portion 10a in the protruding direction; and a first joining portion 10c that extends from the first bending portion 10b along a direction parallel to the lamination direction AR. The electrode terminal 10 as a whole has a substantially L-shaped cross-sectional shape, and both the first protruding portion 10a and the first joining portion 10c are formed in a substantially flat plate shape. The first protruding portion 10a and the first joining portion 10c are connected to each other in a state of being bent at an angle of about 90° at the position of the first bending portion 10b.

[0036] The electrode terminal 10 further has a bottom plate portion 10c1 ( Figure 2 , Figure 3) and a peripheral wall portion 10c2 surrounding the bottom plate portion 10c1. Here, both the bottom plate portion 10c1 and the peripheral wall portion 10c2 are formed in the first joint portion 10c of the electrode terminal 10. In the first joint portion 10c, a part of the first joint portion 10c is recessed toward the side opposite to the crossing direction CR (the direction approaching the main body portion 1a) to form the bottom plate portion 10c1 and the peripheral wall portion 10c2.

[0037] Moreover, convex portions 10t1, 10t2 are provided on the bottom plate portion 10c1 by molding or the like, and the convex portions 10t1, 10t2 protrude from the bottom plate portion 10c1 along the crossing direction CR (the direction away from the main body portion 1a). The tip portion of the convex portion 10t1 in the protruding direction defines the first portion 11a, and is joined to the second joint portion 20c of the electrode terminal 20 by welding. The tip portion of the convex portion 10t2 in the protruding direction defines the first portion 11b, and is joined to the second joint portion 20c of the electrode terminal 20 by welding.

[0038] (Electrode terminal 20 (second metal member))

[0039] The electrode terminal 20 (refer to Figures 1 to 3 ) has: a second protruding portion 20a that protrudes from the main body portion 2a of the second battery cell 2 in the crossing direction CR; a second bent portion 20b formed at the tip of the second protruding portion 20a in the protruding direction; and a second joint portion 20c that extends from the second bent portion 20b along a direction parallel to the stacking direction AR. The electrode terminal 20 as a whole has a substantially L-shaped cross-sectional shape, and both the second protruding portion 20a and the second joint portion 20c are formed in a substantially flat plate shape. The second protruding portion 20a and the second joint portion 20c are connected in a state where they are bent at an angle of about 90° at the position of the second bent portion 20b.

[0040] The portion of the second joint portion 20c of the electrode terminal 20 that faces the tip portion of the convex portion 10t1 defines the second portion 21a, and is joined to the above-mentioned first portion 11a of the electrode terminal 10 by welding. The portion of the second joint portion 20c of the electrode terminal 20 that faces the tip portion of the convex portion 10t2 defines the second portion 21b, and is joined to the above-mentioned first portion 11b of the electrode terminal 10 by welding.

[0041] The electrode terminal 20 is also formed with pressure relief ports 20h1, 20h2. Here, the pressure relief ports 20h1, 20h2 are formed to penetrate the second joint portion 20c of the electrode terminal 20 in the thickness direction. Here, in the longitudinal direction of the first joint portion 10c and the second joint portion 20c (i.e., the direction orthogonal to the stacking direction AR and the crossing direction CR), the positions of the pressure relief ports 20h1, 20h2 and the convex portions 10t1, 10t2 are offset.

[0042] (Space SP)

[0043] The electrode terminal 10 and the electrode terminal 20 are arranged in contact with each other, and a space SP surrounded by the electrode terminal 10 and the electrode terminal 20 is formed therebetween. Here, the space SP is partitioned and formed by the bottom plate portion 10c1 of the electrode terminal 10, the peripheral wall portion 10c2 of the electrode terminal 10, and the second joint portion 20c of the electrode terminal 20( Figure 1 , Figure 3 ). It is also possible to continuously or intermittently provide a sponge or an adhesive extending in a ring shape on the surfaces of these members in a state where they are in contact with each other, so as to form a space SP with higher airtightness.

[0044] (Welding marks 31a, 31b)

[0045] As Figure 1 shown, a convex portion 10t1 is provided on the electrode terminal 10, and the top portion (the first portion 11a) of the convex portion 10t1 in the protruding direction is arranged opposite to the second portion 21a of the second joint portion 20c of the electrode terminal 20. In a state where no suction-based decompression as described later is performed, a design can be adopted in which the first portion 11a abuts against the second portion 21a. The first portion 11a in the electrode terminal 10 and the second portion 21a in the electrode terminal 20 are welded to each other, whereby they are joined to each other and a welding mark 31a is formed on the outer surface 20s of the second joint portion 20c of the electrode terminal 20.

[0046] Similarly, a convex portion 10t2 is provided on the electrode terminal 10, and the top portion (the first portion 11b) of the convex portion 10t2 in the protruding direction is arranged opposite to the second portion 21b of the second joint portion 20c of the electrode terminal 20. In a state where no suction-based decompression as described later is performed, a design can be adopted in which the first portion 11b abuts against the second portion 21b. The first portion 11b in the electrode terminal 10 and the second portion 21b in the electrode terminal 20 are welded to each other, whereby they are joined to each other and a welding mark 31b is formed on the outer surface 20s of the second joint portion 20c of the electrode terminal 20.

[0047] (Manufacturing method)

[0048] The manufacturing methods of the welding structures 30a and 30b are as follows. As Figure 2 shown, the first battery unit 1 and the second battery unit 2 are prepared, and as Figure 3 (and Figure 1 ) shown, the first battery unit 1 and the second battery unit 2 are stacked. By bringing the electrode terminal 10 (the first metal member) into contact with the electrode terminal 20 (the second metal member), a space SP surrounded by the electrode terminal 10 and the electrode terminal 20 is formed.

[0049] Figure 4 A perspective view showing a situation when the electrode terminal 10 and the electrode terminal 20 are joined by welding. Figures 5 to 7 Respectively, sectional views taken along the Figure 3 V-V line, VI-VI line, and VII-VII line in Figures 5 to 7 The sectional structure showing the position of the bottom plate portion 10c1 (in other words, the space SP) of the first joint portion 10c passing through the electrode terminal 10. In particular, Figure 5 The sectional structure showing the position passing through the pressure relief port 20h2. Figure 6 The sectional structure showing the position not passing through the convex portions 10t1, 10t2 and the pressure relief ports 20h1, 20h2. Figure 7 The sectional structure showing the position passing through the convex portion 10t2.

[0050] In the manufacturing method of the welding structures 30a, 30b, a suction device 60 ( Figure 5 ) is provided with a conduit or nozzle for the pressure relief ports 20h1, 20h2, and the space SP is decompressed by performing a suction operation on the space SP through the pressure relief ports 20h1, 20h2 ( Figure 4 , Figure 5 arrow SC).

[0051] As Figure 6 , Figure 7 shown, the internal pressure of the space SP becomes smaller than the atmospheric pressure, and thus a force in the direction of bringing them closer to each other is generated between the first joint portion 10c and the second joint portion 20c ( Figure 6 , Figure 7 arrow PS). Accordingly, the first portion 11a of the electrode terminal 10 can be made to contact more strongly with the second portion 21a of the electrode terminal 20, or the distance between the first portion 11a of the electrode terminal 10 and the second portion 21a of the electrode terminal 20 can be made smaller than in the case where the space SP is not decompressed.

[0052] In the state where the space SP has been decompressed, as Figure 4 , Figure 7 shown, the first portion 11a of the electrode terminal 10 and the second portion 21a of the electrode terminal 20 are welded to each other. Here, the laser LS traveling from the side of the second portion 21a of the electrode terminal 20 toward the side of the first portion 11a of the electrode terminal 10 is irradiated onto the outer surface 20s of the electrode terminal 20, whereby the first portion 11a of the electrode terminal 10 and the second portion 21a of the electrode terminal 20 are welded to each other. For example, compared with the electrode terminal 10 formed of copper, the thermal energy of the laser is first supplied to the electrode terminal 20 with a lower melting point formed of aluminum, and the electrode terminal 20 is welded to the electrode terminal 10.

[0053] [Function and Effect]

[0054] In the case of joining two metal members by welding, it is preferable to minimize the gap between the metal members, and more specifically, the gap between the parts to be welded. In addition, it is preferable that the gap (solidification shrinkage amount) between the metal members does not change each time welding is performed.

[0055] In the above-described embodiment, in a state where the electrode terminals 10 and 20 are in contact with each other, a space SP is formed between the electrode terminals 10 and 20, and the space SP is decompressed by the decompression ports 20h1 and 20h2 (Pascal's principle), so that the size of the above-described gap and the deviation of the gap can be made smaller. By optimizing the degree of decompression and the intensity of the laser, it is easy to improve the welding quality. Therefore, according to the above-described embodiment, a welding structure in which the metal members are more sufficiently joined to each other, a manufacturing method thereof, a battery in which the electrode terminals of the battery unit are more sufficiently joined to each other, and a manufacturing method thereof can be obtained.

[0056] Figure 8 It is a cross-sectional view for explaining a manufacturing method of a welding structure of Comparative Example 1. As Figure 8 shown, in the case of performing resistance welding, for example, two metal members (electrode terminals 10 and 20) are clamped and positioned by terminal members 41 and 42 for supplying voltage, so that the size of the gap and the deviation of the gap can be made smaller. However, since a space corresponding to the thickness DT of the terminal member 42 needs to be ensured for the space between the first joint portion 10c and the main body portion 1a and the space between the second joint portion 20c and the main body portion 2a ( Figure 8 ), it is difficult to miniaturize the entire device.

[0057] According to the above-described embodiment, the terminal members 41 and 42 are not required to be arranged, and the electrode terminals 10 and 20 can be joined to each other in a non-contact manner by laser welding. Therefore, compared with the case of Comparative Example 1 shown in Figure 8 , the entire device can be miniaturized. The concept disclosed in the above-described embodiment is not limited to a structure in which the joint surfaces of the first joint portion 10c and the second joint portion 20c extend parallel to the stacking direction AR, and can also be applied to a structure in which the joint surfaces of the first joint portion 10c and the second joint portion 20c intersect (for example, are orthogonal) to the stacking direction AR.

[0058] Figure 9 It is a cross-sectional view for explaining a manufacturing method of a welding structure of Comparative Example 2. In the case of performing laser welding, there is still room for discussion on the following scheme: using a pressing member 43 to apply a pressing force only from one side to the first joint portion 10c and the second joint portion 20c to make the above-described gap smaller. Accordingly, the entire device can be miniaturized. However, as Figure 10As shown, when a pressing force is applied only from one side using a mechanical means such as the pressing member 43, compared with the case of the embodiment, a deviation in the gap caused by single-end contact or stress concentration is likely to occur.

[0059] According to the above-described embodiment, by utilizing the action based on Pascal's principle of pressure reduction, a negative pressure can be generated in the entire space SP substantially evenly. Furthermore, compared with the case of Comparative Example 2 described above, the size of the gap and the deviation of the gap can be made smaller.

[0060] In the above-described embodiment, two pressure reduction ports 20h1 and 20h2 are provided in the electrode terminal 20, but the pressure reduction port may be one, and it may be provided in the electrode terminal 10, or pressure reduction ports may be provided in both of the electrode terminals 10 and 20. Additionally, it may be that a part of the electrode terminal 10 overlaps with a part of the electrode terminal 20 to form a pressure reduction port therebetween.

[0061] Although the embodiments of the present invention have been described, it should be understood that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown by the claims, and it is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A manufacturing method of a battery, comprising: a step of laminating a first battery cell having a first electrode terminal and a second battery cell having a second electrode terminal; and a step of forming a welding structure in which the first electrode terminal and the second electrode terminal are welded to each other by a manufacturing method using a welding structure, wherein in a case where the direction in which the first battery cell and the second battery cell are laminated is defined as the lamination direction and the direction crossing the lamination direction is defined as the crossing direction, the first electrode terminal has: a first protruding portion protruding from the main body portion of the first battery cell in the crossing direction; a first bending portion formed at the tip of the first protruding portion in the protruding direction; and a first joint portion extending from the first bending portion along a direction parallel to the lamination direction, and the second electrode terminal has: a second protruding portion protruding from the main body portion of the second battery cell in the crossing direction; a second bending portion formed at the tip of the second protruding portion in the protruding direction; and a second joint portion extending from the second bending portion along a direction parallel to the lamination direction, the first joint portion of the first electrode terminal has a bottom plate portion and a peripheral wall portion surrounding the periphery of the bottom plate portion, and a convex portion is provided on the bottom plate portion, the convex portion protrudes from the bottom plate portion, and the tip portion of the convex portion in the protruding direction defines a first portion, and a portion of the second joint portion of the second electrode terminal that faces the first portion defines a second portion, the manufacturing method of the welding structure comprises: a step of bringing the first portion of the first electrode terminal into contact with the second portion of the second electrode terminal to form an airtight space separated by the bottom plate portion, the peripheral wall portion, and the second joint portion of the second electrode terminal; a decompression port is formed between the first joint portion of the first electrode terminal and the second joint portion of the second electrode terminal or in at least one of the joint portions of the first joint portion of the first electrode terminal and the second joint portion of the second electrode terminal, the manufacturing method of the welding structure further comprises: a step of performing a suction operation on the airtight space through the decompression port to decompress the airtight space, so that the first portion of the first electrode terminal contacts the second portion of the second electrode terminal, or the distance between the first portion of the first electrode terminal and the second portion of the second electrode terminal is smaller than the case where the airtight space is not decompressed; and a step of welding the first portion of the first electrode terminal and the second portion of the second electrode terminal to each other in a state where the airtight space has been decompressed.

2. The manufacturing method of a battery according to claim 1, wherein the first electrode terminal is formed of copper, the second electrode terminal is formed of aluminum.

3. The manufacturing method of a battery according to claim 1 or 2, wherein Irradiate the outer surface of the second electrode terminal with a laser traveling in a direction from the side of the second portion of the second electrode terminal toward the side of the first portion of the first electrode terminal, thereby welding the first portion of the first electrode terminal to the second portion of the second electrode terminal to each other.

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