WO2014003185A1

WO2014003185A1 - Current collection structure of secondary cell

Info

Publication number: WO2014003185A1
Application number: PCT/JP2013/067929
Authority: WO
Inventors: 田中　明
Original assignee: 新神戸電機株式会社
Priority date: 2012-06-29
Filing date: 2013-06-28
Publication date: 2014-01-03
Also published as: JPWO2014003185A1; JP5858158B2

Abstract

The present invention provides a current collection structure of a secondary cell in which contact failure between a current collection tab and the terminal can be prevented while reducing the contact resistance with respect to the terminal. A tab laminate (7), obtained by laminating a plurality of current collection tabs (5) extending from an electrode plate group (3) and a current collector (9b) of the terminal (9), and a cover member (13) for sandwiching, with the current collector (9b), the tab laminate (7), are joined by friction stir welding. A tab storage part (15), which is provided with a structure for storing at least a part of the tab laminate (7) and preventing the current collection tabs (5) in the tab laminate (7) from sliding during friction stir welding, is formed on the current collector (9b) and/or the cover member (13).

Description

Secondary battery current collection structure

The present invention relates to a current collecting structure of a secondary battery in which a plurality of current collecting tabs extending from an electrode plate group are joined to a current collector of a terminal.

Non-aqueous electrolyte secondary batteries such as lithium-ion batteries are suitable for increasing the energy density, and thus include not only small electronic devices such as mobile phones and personal computers, but also hybrid electric vehicles (HEV) and electric vehicles (EV). ), Applications are expanding from mobile power sources such as forklifts and shovel cars to large storage batteries such as UPS (uninterruptible power supply), solar power generation and wind power generation. With such expansion of industrial applications, secondary batteries such as lithium ion batteries are required to have a large capacity and a large current. A secondary battery such as a lithium ion battery has a structure in which a plurality of current collecting tabs extending from an electrode plate group are electrically connected to a current collector of a terminal. In order to increase the capacity or current of the secondary battery having such a structure, the number of current collecting tabs to be stacked must be increased. However, if the number of stacked current collecting tabs is increased, heat is likely to be generated between the current collecting tabs or at the connecting portions between the current collecting tabs and the terminals. In the conventional secondary battery, in order to prevent heat generation due to such an increase in the number of stacked current collecting tabs, the current collecting tabs are connected to the terminals so that the electrical resistance of the connecting portion between the current collecting tabs and the terminals is as small as possible. A directly joined current collecting structure is adopted.

As a technique for directly joining a current collecting tab to a current collecting plate of a terminal, for example, in Patent Document 1, a concave portion formed in a current collecting plate of a terminal and a concave portion of a current collecting plate formed in a backing plate are fitted. A technique is disclosed in which a current collecting tab is arranged between the protruding portion and the projecting portion and is fixed with a screw. Patent Document 2 discloses a technique in which a plurality of current collecting tabs are sandwiched between a current collecting plate and a contact plate of a terminal, and these are welded with a laser. Further, Patent Document 3 discloses a technique in which a current collecting tab is sandwiched between a current collecting plate and a backing plate, and this is friction stir welded.

JP 2009-87612 A JP 2001-118561 A Japanese Patent No. 4586339

However, in the structure in which the current collecting tab is joined to the terminal by screw fixing as in Patent Document 1, since a large contact resistance is generated between the current collecting tab and the terminal, the electrical resistance of the connection portion is increased and a large current flows. There is a problem that the voltage drop at the time becomes large.

Further, in the structure in which the current collecting tab is connected to the terminal by laser welding as in Patent Document 2, the spatter generated during welding melts the separator or remains in the electrode group, causing a short circuit. In addition, when laser welding is used, since the laser beam diameter is usually as small as φ1 mm or less, it is not possible to obtain a sufficient bonding area for flowing a large current.

Furthermore, when friction stir welding as in Patent Document 3 is performed, the contact resistance can be reduced compared to mechanical joining such as screw fixation, and the joining width and joining area compared to joining by laser welding. However, in friction stir welding, a rotating tool is pressed against the stacked current collecting tabs, so thin foils are stacked and joined together like current collecting tabs. In the case of forming, in addition to the tearing of the foil and the generation of burrs around the joint, there are problems that the current collecting tab is displaced during the joint, resulting in poor contact.

An object of the present invention is to provide a current collecting structure for a secondary battery that can prevent a contact failure between a terminal and a current collecting tab while reducing a contact resistance between the current collector of the terminal and the current collecting tab. It is to provide.

Another object of the present invention is to provide a current collecting structure for a secondary battery in which friction stir welding between a current collector of a terminal and a current collecting tab is easy.

Still another object of the present invention is to provide a secondary battery suitable for increasing capacity and current.

The current collector structure of the secondary battery to be improved by the present invention includes a terminal having a current collector and a plurality of current collecting tabs extending from a group of electrode plates in which a plurality of electrode plates are laminated via a separator. And a metal cover member that sandwiches the tab stack group between the current collector and the tab stack group. The current collector, the tab stack group, and the cover member are joined by friction stir welding (FSW). Here, the friction stir welding means that at least two joining members are generated by frictional heat generated by pressing a pressed tool against at least two joining members while penetrating the tool into the joining member while rotating a tool having a projection at the tip. Is partially softened, and at least two joining members to be joined are integrated by plastic flow around the joint softened by the rotational force of the tool and kneading.

In the current collector structure of the secondary battery of the present invention, a tab storage portion is provided on at least one of the current collector and the cover member. The tab storage portion stores at least a part of the tab stack group and has a structure that prevents a plurality of current collecting tabs in the tab stack group from sliding during friction stir welding. When such a tab storage portion is provided on either the current collector or the cover member, a plurality of current collection tabs in the tab stack group are stored in the tab storage portion without sliding due to the rotational force applied from the tool. In this state, friction stir welding can be performed between the tab stack group and the current collector and between the tab stack group and the cover member. As a result, it is ensured that the adjacent current collecting tabs in the tab laminated group to be joined by friction stir welding, the tab laminated group and the current collector, and the tab laminated group and the cover member are joined. This can reduce the contact resistance of the joint. Therefore, according to the present invention, even when the number of stacked current collecting tabs is increased, the electrical resistance between adjacent current collecting tabs, between the tab laminated group and the current collector, and between the tab laminated group and the cover member is reduced. It is possible to prevent the occurrence of poor contact between the tab stack group and the current collector and between the tab stack group and the cover member. When the contact resistance at the contact portion decreases, the amount of heat generated at the contact portion decreases, so that the discharge current can be increased, and the capacity and current of the secondary battery can be increased. Further, by storing the tab stack group in the tab storage portion, it becomes easy to position the tab stack group at the time of friction stir welding. Therefore, a plurality of current collecting tabs are bonded to the output terminal using friction stir welding. Work becomes easy.

It is preferable that the current collector of the terminal is provided with a slide prevention structure that prevents the cover member from sliding with respect to the current collector when performing friction stir welding from the cover member side. By providing such a slide blocking structure, it is possible to prevent displacement of the cover member with respect to the current collector of the terminal and the tab stack group housed in the tab housing portion. Therefore, while reducing the contact failure between the tab stack group and the current collector (while reducing the electrical resistance between the current collector tab and the current collector), the position of the current collector tabs during friction stir welding The effect of preventing misalignment (preventing poor contact between the current collecting tab and the current collector) can be reliably obtained. In addition, when the slide blocking structure is provided, the positioning of the cover member with respect to the current collector of the terminal and the tab stack group housed in the tab housing portion is facilitated, so that the friction stir welding operation is facilitated.

The structure of the tab storage part is any structure that stores at least a part of the tab stack group and prevents the plurality of current collecting tabs in the tab stack group from sliding during friction stir welding. May be adopted. Also, the slide blocking structure may be any structure as long as it prevents the cover member from sliding relative to the current collector. For example, the tab storage portion can be configured with a plurality of convex portions that prevent a plurality of current collecting tabs in the tab stack group from sliding. Further, the slide blocking structure can also be constituted by a plurality of convex portions that block the cover member from sliding relative to the current collector. However, if one or both of the tab storage portion and the slide blocking structure are configured as a convex portion, the size of the current collecting structure increases due to the presence of the convex portion, and the volume of the battery case may increase. In consideration of such a problem, it is preferable that both the tab storage portion and the slide blocking structure are constituted by recesses. In this case, the tab storage portion is constituted by a first recess formed on the surface of the terminal facing the current collector cover member, and the slide blocking structure is formed on the surface of the current collector facing the cover member. It can comprise by the made 2nd recessed part. Since such a recess is configured by utilizing the thickness of the terminal (or current collector), the size of the current collecting structure is not increased and the volume of the battery case is increased as compared with the case where the projection is formed. There is no need to do. Further, when the tab storage portion and the slide blocking structure are configured by such a recess, the movement of the plurality of current collecting tabs in the tab stack group is blocked by both side surfaces inside the first recess, and the second recess. Since the movement of the cover member is blocked by the inner side surfaces, it is possible to reliably prevent the displacement of the current collecting tab and the displacement of the cover member during friction stir welding.

When the depth dimension of the first recess constituting the tab storage portion is larger than the thickness dimension of the tab stack group, the tab stack group is placed between the tab stack group and the cover member in a state where the tab stack group is stored in the tab storage section. A gap is created. Further, when the depth dimension of the first recess constituting the tab storage portion and the thickness dimension of the tab stack group are the same, the tab stack group and the cover member in the state stored in the tab storage section are in sufficient contact with each other. Therefore, even if the friction stir welding is performed, there is a possibility that poor bonding occurs between the current collector, the tab stack group, and the cover member. Therefore, it is preferable that the depth dimension of the first recess is smaller than the thickness dimension of the tab stack group. When the depth dimension of the first recess is set to such a dimension, friction stir welding can be performed in a state where the tab stack group is compressed in the stacking direction, so that a plurality of current collecting tabs in the tab stack group They can be reliably bonded to each other, and the occurrence of defective bonding can be reliably prevented.

The first concave portion constituting the tab storage portion and the second concave portion constituting the slide blocking structure are formed in an intersecting state, and a welded portion by friction stir welding is formed along the second concave portion. Preferably, it is formed so as to completely traverse one recess. When the welded portion is formed in this way, a joining portion can be formed so as to completely traverse a plurality of current collecting tabs constituting the tab laminated group in the width direction, and between the current collector and the tab laminated group and the tab. Since no gap is formed between the current collecting tabs constituting the stacked group, the contact resistance at the contact portion can be reduced.

When multiple current collector tabs are joined to a current collector as one tab stack group at one location, the current collector tabs extending from the electrode plates are lengthened as the number of electrode plates increases. Need to be routed. Therefore, a plurality of current collecting tabs extending from a plurality of plates of the same polarity are divided into two to form two tab laminated groups, and these two tab laminated groups are separately joined to the current collector. Then, it can join to a collector, without making the length of a current collection tab so long. Even when the number of current collectors constituting one tab stack group is small (when the bending stress when deforming the tab stack group tends to concentrate on some of the current collector tabs in the tab stack group), the tab Since stress can be prevented from concentrating on some of the current collecting tabs in the stacked group, disconnection or short circuit of the current collecting tabs can be prevented.

In particular, when the present invention is applied to a non-aqueous electrolyte secondary battery such as a lithium ion battery, the non-aqueous electrolyte secondary battery has a plurality of electrode plates each provided with a current collecting tab via a separator. A positive electrode terminal including a current collector to which one or more tab laminated groups in which a plurality of current collecting tabs extending from a plurality of positive electrode plates in the electrode plate group are laminated are connected. A negative electrode terminal including a current collector to which one or more tab laminated groups formed by laminating a plurality of current collecting tabs extending from a plurality of negative electrode plates in the electrode plate group are connected, and a current collector A metal cover member that sandwiches the tab stack group therebetween, and a battery case that houses the battery components so that the positive electrode terminal portion of the positive electrode terminal and the negative electrode terminal portion of the negative electrode terminal are exposed. The current collector, the tab stack group, and the cover member are joined by friction stir welding.

In the secondary battery of the present invention, the above-described current collecting structure is adopted. That is, a tab storage unit having a structure that stores at least a part of the tab stack group and prevents a plurality of current collecting tabs in the tab stack group from sliding during friction stir welding includes a current collector and It is provided on at least one of the cover members. In the secondary battery having such a current collecting structure, the above-described effect of the current collecting structure can be obtained as it is. That is, even when the number of stacked current collecting tabs is increased, the contact resistance between the current collecting tabs and the current collector can be reduced while reducing the electrical resistance between the current collecting tabs and the current collector. . Therefore, since the current flowing between the current collecting tab and the output terminal can be increased, the capacity and current of the secondary battery can be increased.

Note that the positions of the positive electrode terminal and the negative electrode terminal of the secondary battery are arbitrary. For example, when configuring a rectangular secondary battery, the positive electrode terminal and the negative electrode terminal part are exposed so that the positive electrode terminal part and the negative electrode terminal part are respectively exposed from one of the pair of wall parts facing the battery case. What is necessary is just to determine the position of a terminal. In the case of constituting a cylindrical secondary battery, the positions of the positive electrode terminal and the negative electrode terminal may be determined so that the positive electrode terminal portion and the negative electrode terminal portion are exposed from a pair of opposing wall portions of the battery case. . With such a configuration, since the negative electrode current collecting tab and the positive electrode current collecting tab do not intersect on either side of the pair of wall portions facing each other in the battery case, it is possible to provide a secondary battery that is not easily short-circuited. .

It is a perspective view for demonstrating the secondary battery using the current collection structure of this invention. It is a perspective view which shows the basic composition (main part) of the current collection structure of this invention. It is the schematic which shows 1st Example of the current collection structure of this invention. It is a figure which shows the junction part of the electrical power collector in the current collection structure (1st Example) of FIG. 3, a current collection tab, and a cover member. FIG. 4 is a schematic process diagram illustrating a method of manufacturing the current collecting structure (first embodiment) of FIG. 3, wherein (A) shows a state before the cover member is arranged after the tab stack group is accommodated in the current collector. (B) is a figure which shows the state which is implementing friction stir welding. It is the schematic which shows 2nd Example of the current collection structure of this invention. It is a figure which shows the junction part of the electrical power collector in the current collection structure (2nd Example) of FIG. 6, a current collection tab, and a cover member. It is a schematic process drawing which shows the method of manufacturing the current collection structure (2nd Example) of FIG. 6, (A) is a state before arrange | positioning a cover member, after accommodating a tab lamination group in an electrical power collector. (B) is a figure which shows the state which is implementing friction stir welding. It is the schematic which shows 3rd Example of the current collection structure of this invention. It is a figure which shows the junction part of the electrical power collector in the current collection structure (3rd Example) of FIG. 9, a current collection tab, and a cover member. It is the schematic which shows 4th Example of the current collection structure of this invention. It is a figure which shows 5th Example of the current collection structure of this invention, Comprising: A junction part of a collector, a current collection tab, and a cover member. It is a figure which shows the aspect which coat | covered the junction part of the current collection tab with resin in the current collection structure (5th Example) of FIG. It is the schematic which shows the 6th Example of the current collection structure of this invention. It is a figure which shows the junction part of the electrical power collector in the current collection structure (6th Example) of FIG. 14, a current collection tab, and a cover member. It is a schematic process drawing which shows the method of manufacturing the current collection structure (6th Example) of FIG. 14, (A) is a state before arrange | positioning a cover member after accommodating a tab lamination | stacking group in an electrical power collector. (B) is a figure which shows the state which is implementing friction stir welding. It is the schematic which shows the 7th Example of the current collection structure of this invention. It is a figure which shows the junction part of the electrical power collector in the current collection structure (7th Example) of FIG. 17, a current collection tab, and a cover member. It is a figure which shows the structure of the electrical power collector (part which a current collection tab joins) in the current collection structure (7th Example) of FIG. (A) is a sectional view taken along line 20A-20A in FIG. 19, (B) is a sectional view taken along line 20B-20B in FIG. 19, and (C) is a sectional view taken along line 20C-20C in FIG. ) Is a cross-sectional view taken along line 20D-20D of FIG. FIG. 18 is a schematic process diagram illustrating a method of manufacturing the current collecting structure (seventh embodiment) in FIG. 17, wherein (A) shows a state before the cover member is arranged after the tab stack group is housed in the current collector. (B) is a figure which shows the state which is implementing friction stir welding. In FIG.20 (D), it is a figure which shows the state which accommodated the tab lamination | stacking group in the accommodating part. It is the schematic which shows 9th Example of the current collection structure of this invention. It is the schematic which shows 10th Example of the current collection structure of this invention. FIG. 25 is a schematic process diagram illustrating a method of manufacturing the current collecting structure (tenth embodiment) in FIG. 24, wherein (A) shows a state before the cover member is arranged after the tab stack group is stored in the current collector. (B) is a figure which shows the state which is implementing friction stir welding.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an example of an embodiment of a secondary battery of the present invention using the current collecting structure of the present invention, and FIG. 2 shows a basic configuration (main part) of the current collecting structure of the present invention. It is a perspective view. The secondary battery shown in FIG. 1 includes an electrode plate group 3 in which a plurality of electrode plates (negative electrode plate 3a and positive electrode plate 3b) are stacked in a battery case 1 via a separator (not shown) as a battery constituent element. It is stored. A lid 2 is laser welded to the battery case 1 in a state in which the battery components (electrode plate group 3 and the like) are accommodated. The lid 2 is provided with a liquid injection hole plug 4 that seals a liquid injection hole for injecting an electrolytic solution. The lid 2 is provided with a safety valve 6 for releasing the internal pressure of the battery case 1 during non-stationary conditions such as overcharging.

The battery case 1 has a rectangular shape with one side open so that a laminate in which rectangular electrode plates are stacked with a separator interposed therebetween can be accommodated. A laminated battery made of such a rectangular battery case does not have a winding axis or the like as compared with a cylindrical battery case in which a strip-shaped electrode plate or separator is wound in a columnar shape. Energy density can be increased. In this example, the battery case 1 is formed by impact press molding of an aluminum alloy. When the material of the battery case 1 is an aluminum metal, the battery case may be produced by die casting. The material of the battery case 1 may be stainless steel. The material of the battery case 1 is preferably a metal material such as aluminum or stainless steel from the viewpoint of increasing the mechanical strength. On the other hand, from the viewpoint of durability, not only a metal material but also a resin that is not eroded by an electrolytic solution (for example, a resin such as fluorine, polyethylene, polypropylene, epoxy, POM, PEEK, or BT resin) may be used. The resin-based battery case has an advantage of being lighter than the metal-based battery case because the density of the material is small. However, in the case of using a resin-based material, there are drawbacks such as that the resin is weak in strength and that the resin has poor heat dissipation due to its low thermal conductivity. Therefore, in consideration of these points, the battery case 1 may be mainly composed of a metal material and the surface thereof may be covered with the above-described resin.

The electrode plate group 3 includes an electrode plate (negative electrode plate 3a) in which a negative electrode active material layer is formed on the surface of a strip-shaped negative electrode current collector plate made of copper, a separator holding an electrolyte, and a strip-shaped positive electrode collector made of aluminum. The electrode plate (positive electrode plate 3b) having a positive electrode active material layer formed on the surface of the electric plate is alternately laminated. The dimensions such as the thickness of the electrode plate group 3 and the number of stacked layers are determined by the required battery capacity.

Each electrode plate (the negative electrode plate 3a and the positive electrode plate 3b) of the electrode plate group 3 includes a current collecting tab 5 extending from the negative electrode current collecting plate and a current collecting tab 5 extending from the positive electrode current collecting plate, respectively. A plurality of current collecting tabs 5 of a plurality of electrode plates (negative electrode plate 3 a) having the same polarity are laminated to constitute one or more tab laminated groups 7. Here, among the current collecting tabs 5 constituting the tab laminate group 7, the current collecting tab formed on the electrode plate (the negative electrode plate 3a) coated with the negative electrode active material constitutes the negative electrode current collecting tab, and the positive electrode active material The current collecting tab formed on the electrode plate (the positive electrode plate 3b) coated with sapphire constitutes the positive current collecting tab. Therefore, the term “current collector tab” means a general term for a negative electrode current collector tab and a positive electrode current collector tab. The number of current collecting tabs 5 constituting the tab stack group 7 is determined by the capacity. In a battery having a capacity of several tens Ah to several hundreds Ah, the number of current collecting tabs ranges from several tens to several hundreds. In this example, the number of current collecting tabs on the positive electrode plate is 232, and the number of current collecting tabs on the negative electrode plate is 236, thereby constituting a 100 Ah lithium ion secondary battery.

The electrode plate (positive electrode plate 3b) having the positive electrode active material layer formed on the surface of the positive electrode current collector plate is produced as follows. As a lithium-containing oxide (positive electrode active material), lithium manganate powder, carbon powder as a conductive material, and polyvinylidene fluoride (hereinafter abbreviated as PVDF) as a binder are mixed, and this is mixed with N-methylpyrrolidone (dispersing solvent). Hereinafter, an appropriate amount of NMP) is added, and the mixture is sufficiently kneaded and dispersed to prepare a slurry. This slurry is applied to both surfaces of a 20 μm-thick strip-shaped aluminum foil to be a positive electrode plate by transfer and dried, and the aluminum foil coated with the positive electrode active material is wound up as a strip-shaped roll-shaped electrode plate having a length of several hundred meters. . Next, a strip-shaped electrode plate is pulled out from the roll-shaped electrode plate, and is wound into a roll shape as a tab-shaped electrode plate with tabs formed by a tab-forming cutting machine. Next, a roll-shaped electrode plate is obtained by compressing with a predetermined press pressure by a roll press machine having a heated roll and winding it into a roll shape. Next, a strip-shaped electrode plate is drawn out from the roll-shaped electrode plate and cut into a predetermined width by a cutting device to obtain a rectangular electrode plate (positive electrode plate 3b) having a positive electrode active material layer.

On the other hand, in order to produce an electrode plate (negative electrode plate 3a) having a negative electrode active material layer formed on the surface of the negative electrode current collector plate, first, a carbon material (negative electrode active material) and PVDF are mixed as a binder, and an appropriate amount of NMP is mixed. In addition, the slurry is sufficiently kneaded and dispersed. This slurry is applied onto both sides of a 10 μm thick copper foil to be a metal current collector by transfer, dried, and wound up as a rolled electrode plate. The subsequent tab formation process and subsequent steps are the same as the positive electrode manufacturing process. When the positive and negative plates with tabs cut to a predetermined width and the separator are stacked, the electrode plate group 3 is formed.

Among the electrode plate groups 3, the electrode plate group 3 on which the above-described negative electrode plate is laminated is connected to the negative electrode terminal 9, and the electrode plate group 3 on which the above-described positive electrode plate is laminated is connected to the positive electrode terminal 11. The negative electrode terminal 9 and the positive electrode terminal 11 are each fixed to the lid body 2 by screwing a nut 8 into the tip of a screwed terminal portion that penetrates the lid body 2. The negative electrode terminal 9 and the positive electrode terminal 11 protrude from the same surface (the lid body 2 in this embodiment) of the case of the secondary battery. Thereby, since the wiring to the negative electrode terminal 9 and the positive electrode terminal 11 in the battery case 1 is accommodated toward one surface, there is an advantage that a space for wiring can be reduced. The negative electrode terminal 9 includes an exposed portion 9a that is exposed to the outside of the lid body 2 and forms an external output terminal portion, and a terminal base portion 9b that is housed in the battery case 1 and forms a current collector. Yes. Connected to the terminal base (current collector) 9b is a tab laminate group 7 extending from a plurality of electrode plates (negative electrode plate 3a) in the electrode plate group 3. On the other hand, the positive electrode terminal 11 is exposed to the outside of the lid 2 and forms an external output terminal portion 11a, and a terminal (not shown) that is housed inside the battery case 1 and forms a positive electrode current collector. And a base. A tab laminated group 7 extending from a plurality of electrode plates (positive electrode plate 3b) in the electrode plate group 3 is connected to a terminal base (current collector) of the positive electrode. In this example, the planar contour shape of the terminal base (the negative terminal base 9b and the positive terminal base not shown) constituting the current collector is rectangular, but these terminal bases may be cylindrical or columnar, A part of the shape may be a curved surface.

FIG. 2 shows the basic structure of the current collecting structure on the negative electrode side. As shown in FIG. 2, the main part of the current collecting structure includes a tab stack group 7 including a negative electrode terminal 9 and a plurality of current collecting tabs 5, and a metal cover member 13. In this current collection structure, the tab laminated group 7 is joined by friction stir welding (FSW) while being sandwiched between the terminal base 9b of the negative electrode terminal 9 and the cover member 13. As a result, the terminal base 9b, the tab laminated group 7, and the cover member 13 are joined by friction stir welding. In addition, the material of the negative electrode terminal 9 is a copper-based material as in the material of the negative electrode plate (Note that the material of the positive electrode terminal 11 is an aluminum-based material as in the material of the positive electrode plate). . As the material of the cover member 13, a copper-based material was used on the negative electrode terminal 9 side in the same manner as the negative electrode plate (an aluminum-based material was used on the positive electrode terminal 11 side in the same manner as the positive electrode plate). That is, the cover member 13 for bonding to the negative electrode terminal 9 is formed of a copper-based material, and the cover member 13 for bonding to the positive electrode terminal 11 is formed of an aluminum-based material. Moreover, the thickness of the cover member 13 was 1 mm for both the negative electrode and the positive electrode. However, the thickness of the cover member 13 may be selected as appropriate depending on the number of current collecting tabs 5 to be joined, and is usually set to 0.5 mm to 2 mm.

Next, the current collecting structure of the present invention will be described in detail. 3 is a schematic view showing a first embodiment of the current collecting structure, and FIG. 4 is a joint portion of the current collector, the current collecting tab, and the cover member in the current collecting structure (first embodiment) of FIG. FIG. 5 is a schematic process diagram showing a method of manufacturing the current collecting structure (first embodiment) of FIG. 3, and in particular, FIG. 5 (A) houses the tab stack group in the current collector. FIG. 5B is a diagram illustrating a state before the cover member is disposed, and FIG. 5B is a diagram illustrating a state in which the friction stir welding is performed. In these figures, as members of the current collecting structure, a part of the electrode plate group 3 (a plurality of electrode plates 3a), a part of the tab stack group 7 (a plurality of current collecting tabs 5), and a terminal 9 (exposed). Only the negative electrode terminal 9) including the portion 9a and the current collector 9b and the cover member 13 are shown, and the other members (battery case 1, lid 2, etc.) are not shown.

The current collecting structure shown in FIG. 3 shows the current collecting structure on the negative electrode terminal 9 side in FIG. In the first embodiment, the current collector 9b is provided with a tab storage portion 15. The tab storage portion 15 includes a planar contact portion 15a that contacts the current collecting tab 5 positioned on the outermost side of the tab stack group 7, and a convex portion 15b that includes a contact surface extending in a direction orthogonal to the contact portion 15a. It is configured. The convex portion 15b has a width of 1 mm, and is provided at the end of the current collector 9b so that most of the surface of the current collector 9b of the terminal 9 becomes the contact portion 15a. As shown in FIG. 5A, the facing surface 7a facing the current collector 9b of the tab stack group 7 is in contact with the contact portion 15a, and the end portion 7b of the tab stack group 7 is one side surface of the convex portion 15b. A part of the tab stack group 7 is stored in the tab storage portion 15 so as to come into contact with the contact surface made of Then, as shown in FIG. 5B, the cover member 13 is disposed so that the tab stack group 7 partially stored in the tab storage portion 15 is sandwiched between the current collector 9b. In order to prevent the positional relationship between the terminal 9, the current collecting tab 5, and the cover member 13 from being shifted as much as possible, the current collecting tab 5 and the cover member 13 are connected to the terminal 9 by a jig ( (Not shown). In this state, the tip of the tool 16 is pressed against the cover member 13 while rotating the cylindrical tool 16 for friction stir welding from the cover member 13 side, and a plurality of sheets constituting the cover member 13 and the tab stack group 7 are formed. In a state where the current collecting tab 5 and the current collector 9b are partially softened and plastically flowed, the tool 16 is linearly moved to perform friction stir welding. The insertion depth of the tip of the cylindrical tool 16 was set to a depth reaching the current collector 9b of the terminal 9. A cylindrical tool 16 having a tip diameter of 8 mm was selected. In the friction stir welding, in a state where the current collector 9b, the tab laminated group 7 and the cover member 13 are in contact with each other, the tab laminated group 7 in the direction perpendicular to the extending direction of the tab laminated group 7 (the width direction of the tab laminated group 7). The cylindrical tool 16 was moved in a straight line so as to completely cross the line, and a welded portion 17 (joint portion between the current collector 9b, the tab stack group 7 and the cover member 13) was formed. In this embodiment, as shown in FIG. 4, the length L of the welded portion (joint portion) 17 is longer than the width dimension of the tab stack group 7 (current collecting tab 5), but depending on the required current density. The length of the welding part 17 can be made shorter than the width dimension of the tab lamination | stacking group 7 (current collection tab 5). When such friction stir welding is performed, a welded portion 17 that completely joins the current collector 9b, the tab stack group 7, and the cover member 13 is formed. At this time, the convex portion 15 b prevents the plurality of current collecting tabs 5 in the tab stack group 7 from sliding against the pressing force by the friction stir welding. When such a tab storage portion 15 is provided in the current collector 9 b of the terminal 9, friction stir welding is performed between the tab stack group 7 and the current collector 9 b in a state where the tab stack group 7 is stored in the tab storage portion 15. be able to. As a result, the effect of performing friction stir welding (the effect of reducing the contact resistance between the tab stack group and the current collector and the contact resistance between the tab stack group and the cover member) is also convex even if the friction stir welding is performed. The effect which prevents the current collection tab 5 sliding by the part 15b is also acquired. Therefore, as in the first embodiment, even if the number of stacked current collecting tabs 5 is increased, the current collecting tabs 5 and the current collectors are reduced while reducing the electrical resistance between the current collecting tabs 5 and the current collectors 9b. The poor contact with 9b can be reduced. Therefore, by adopting the current collecting structure of the first embodiment, the bonding area between the current collecting tabs 5 in the tab laminated group 7 and the bonding area between the tab laminated group 7 and the current collector 9b are increased. The resistance of the welded portion is reduced, and the capacity and current of the secondary battery can be increased. Further, since the tab stack group 7 is housed in the tab housing portion 15, positioning of the current collecting tab 5 is facilitated when friction stir welding is performed. Therefore, the current collecting tab 5 is joined to the terminal 9 using friction stir welding. Work becomes easier.

In addition to the convex portion 15b of the above-described embodiment, a pair of convex portions may be provided along a pair of opposing sides of the contact portion 15a located on both sides of the convex portion 15b as shown by a broken line in FIG. When such a structure is employed, the sliding prevention effect of the tab stack group 7 can be maximized.

6 is a schematic view showing a second embodiment of the current collecting structure, and FIG. 7 is a joint portion of the current collector, the current collecting tab, and the cover member in the current collecting structure (second embodiment) of FIG. FIG. 8 is a schematic process diagram showing a method of manufacturing the current collecting structure (second embodiment) of FIG. 6 [FIG. 6 (A) houses the tab stack group in the current collector. FIG. 6B is a diagram showing a state before the cover member is disposed, and FIG. 6B is a diagram showing a state in which the friction stir welding is performed. 6 to 8, the parts common to those in FIGS. 3 to 5 are denoted by the same reference numerals as those in FIGS. 3 to 5 plus 100, and the description thereof is omitted. . Also, in FIGS. 6 to 8, as components of the current collecting structure, a part of the electrode plate group 103 (a plurality of electrode plates 103a), a part of the tab stack group 107 (a plurality of current collecting tabs 105), Only the terminal 109 (the negative terminal 109 including the exposed portion 109a and the current collector 109b) and the cover member 113 are shown, and the other members (battery case, lid, etc.) are not shown.

The current collecting structure (second example) shown in FIG. 6 also shows the current collecting structure on the negative electrode terminal side in the same manner as the current collecting structure (first example) shown in FIG. In this second embodiment, the tab laminated group 107 is divided into two tab laminated groups 107 in which a plurality of current collecting tabs 105 extending from a plurality of electrode plates (negative electrode plate 103a) having the same polarity as the electrode plate group 103 are respectively laminated. It is divided. Specifically, as shown in FIG. 6, the electrode plate group 103 is divided in half, and 116 positive electrode current collecting tabs and 118 negative electrode current collecting tabs extend from each divided electrode plate group 103. ing. Two tab laminated groups 107 are configured by bundling these current collecting tabs 105 for each electrode plate group. The tab storage portion 115 provided on the current collector 109b is composed of two contact portions 115a with which the tab stack group 107 contacts, and a convex portion 115b protruding in a direction orthogonal to the two contact portions 115a. The convex portion 115b is provided at the substantially central portion of the current collector 9b of the terminal 9 so as to separate the two contact portions 115a. In this second embodiment, as shown in FIG. 8 (A), the opposing surfaces 107a of the two tab laminate groups 107 facing the current collector 109b are in contact with the two contact portions 115a, respectively, and each tab laminate group. A part of each tab stack group 107 is stored in the tab storage portion 115 so that the end portion 107b of the 107 contacts the side surface of the convex portion 115b. Then, as shown in FIG. 8B, the cover member 113 is disposed so that the tab stack group 107, a part of which is stored in the tab storage portion 115, is sandwiched between the current collector 109b, and the cover member 113 is disposed. When the friction stir welding is performed while rotating the friction stir welding (FSW) tool 116 from the side, the welded portion 117 that joins the current collector 109b, the tab stack group 107, and the cover member 113 is formed. At this time, the convex portion 115 b prevents the plurality of current collecting tabs 105 in the tab stack group 107 from sliding against the pressing force by the friction stir welding. As described above, when the two tab laminated groups 107 are configured to be separately bonded to the current collector 109b, the joint portion between the current collector 109b and the current collector tab 105 can be dispersed in two places. As a result, the current collecting tab 105 extending from each electrode plate 103a can be joined to the current collector without lengthening the length. Further, even when the number of current collecting sheets constituting one tab laminated group is small, the bending stress when the tab laminated group 107 is deformed is concentrated on some of the current collecting tabs 105 in the tab laminated group 107. Since it can prevent, the disconnection and short circuit of the current collection tab 105 can be prevented.

FIG. 9 is a schematic view showing a third embodiment of the current collecting structure of the present invention, and FIG. 10 shows a current collector, a current collecting tab, a cover member in the current collecting structure (third embodiment) in FIG. It is a figure which shows these junction parts. 9 and FIG. 10, parts common to those in FIG. 3 and FIG. 4 are given the same reference numerals as those in FIG. 3 and FIG. . In the third embodiment, the number of positive current collecting tabs in each electrode group was 58, and the number of negative current collecting tabs was 59. The number of current collecting tabs of the positive electrode and the negative electrode respectively corresponds to half of the second embodiment. In friction stir welding, the diameter of a cylindrical tool (not shown) was 4 mm. The width dimension of the cover member 213 is adjusted to a dimension in which the side of the cover member 213 from which the current collecting tab 205 is led out is arranged on the inner side of the side surface of the terminal 209. Otherwise, the third example was manufactured under the same conditions as the second example. In this way, a battery more compact than the second embodiment can be manufactured using the terminal 109 of FIG. 6 (second embodiment) as it is.

FIG. 11 is a schematic view showing a fourth embodiment of the current collecting structure of the present invention. In this figure, parts common to those in FIG. 3 are given the same reference numerals as those in FIG. In the first to third embodiments (FIGS. 3, 6 and 9), the

tab storage portions

15 and 115 are arranged on the side opposite to the exposed

portions

9a, 109a and 209a side of the

terminal base portions

9b, 109b and 209b. In the fourth embodiment (FIG. 11), the tab storage portion 315 is provided on the exposed portion 309a side of the terminal base portion 309b. In such a structure, the surface of the terminal base portion 309b on the exposed portion 309a side constitutes the contact portion 315a of the tab storage portion 315, and the exposed portion 309a constitutes the convex portion 315b of the tab storage portion 315. Therefore, in the fourth embodiment, the tab storage portion 315 can be configured without processing the terminals 9.

FIG. 12 is a view showing a joint portion of a current collector, a current collection tab, and a cover member in the fifth embodiment of the current collection structure of the present invention. In this figure, the parts common to those in FIG. 4 are given the same reference numerals as those in FIG. The current collecting structure of the fifth embodiment is a current collecting structure used for a 100 Ah battery as in the first embodiment. In the first embodiment, during the friction stir welding, the cylindrical tool 16 is linearly moved in the width direction of the tab stack group 7 (longitudinal direction of the cover member 13) and joined, whereas in FIG. In the fifth embodiment, a cylindrical tool (not shown) is inserted into a predetermined position of the cover member 413, and after reaching the depth of the terminal 409, is pulled up at the same position as the inserted position. This operation was performed three times while changing the position in the same cover member 413 to form the joints 417 (three

joints

417a, 417b, 417c) shown in FIG. When such friction stir welding was performed, burrs generated during welding could be reduced as compared with the first example.

In addition, in the 5th Example of FIG. 12, as shown in FIG. 13, the surface of the junction part 417 (three

junction parts

417a, 417b, 417c) is covered with the resin 419. In FIG. By covering the surface of the joint portion 417 with the resin 419 in this way, burrs generated at the time of joining are also covered with the resin 419. Therefore, it is possible to make it difficult for an operator to be injured during battery assembly. Such a structure can be used not only in the fifth embodiment but also in other embodiments of the present invention.

14 is a schematic view showing a sixth embodiment of the current collecting structure, and FIG. 15 is a joint portion of the current collector, the current collecting tab and the cover member in the current collecting structure (sixth embodiment) of FIG. FIG. 16 is a schematic process diagram showing a method of manufacturing the current collecting structure (sixth embodiment) of FIG. 14 [FIG. 16A houses the tab stack group in the current collector. FIG. 16B is a diagram illustrating a state before the cover member is disposed, and FIG. 16B is a diagram illustrating a state in which the friction stir welding is performed. 14 to FIG. 16, parts common to those in FIG. 3 to FIG. 5 are given the same reference numerals as those in FIG. 3 to FIG. . In the current collecting structure shown in FIG. 6 (second embodiment), the two cover members 113 are joined to the two tab laminated groups 107 connected to one terminal 109 (current collector 109b). On the other hand, in the current collecting structure (sixth embodiment) shown in FIG. 14, one cover member 513 is joined to two tab stacked groups 507 connected to one terminal 509 (current collector 509 b). Yes. In this example, as shown in FIG. 16A and FIG. 16B, one end 507b of each tab stack group 507 stored in the tab storage portion 515 and one convex portion 515b of the tab storage portion 515 are provided. The cover member 513 was covered, and the friction stir welding was performed so that the end portion 507b of each tab laminated group 507 was joined to the current collector 509b. Thus, when two tab lamination groups 507 are joined by one cover member 513, the number of parts can be reduced compared to the second embodiment (a configuration in which two joint portions are provided using two cover members 113). In addition to being able to reduce the number of joints in the friction stir welding, the time required for the friction stir welding process can be shortened. Moreover, since each electrode plate group 503 of the same pole is joined by the same joining part 517, the bias | biasing of the electric current which flows into each electrode board group by the variation in the electrical resistance of a junction part can be decreased.

FIG. 17 is a schematic view showing a seventh embodiment of the current collecting structure of the present invention, and FIG. 18 shows a current collector, a current collecting tab, a cover member in the current collecting structure (seventh embodiment) in FIG. 19 is a diagram showing the current collector in a state where the current collecting tab and the cover member are not joined in FIG. 18, and FIGS. 20A to 20D are terminals. 609 is a cross-sectional view of the terminal 609 shown by cutting each part of FIG. 609, and FIG. 21 is a schematic process diagram showing a method of manufacturing the current collecting structure (seventh embodiment) of FIG. ) Is a diagram showing a state before the cover member is arranged after the tab stack group is housed in the current collector, and FIG. 21B is a diagram showing a state in which the friction stir welding is performed. 17 to FIG. 21, parts common to those in FIG. 3 to FIG. 5 are given the same reference numerals as those in FIG. 3 to FIG. . In the seventh embodiment, as shown in FIG. 18, FIG. 19 and FIG. 20A, the tab storage portion 615 is constituted by a concave portion 621 (first concave portion). In this example, in addition to the tab storage portion 615 that stores the tab stack group 607, a slide blocking structure 623 that stores the cover member 613 is further provided [see FIGS. 19 and 20B to 20D]. The slide blocking structure 623 includes a recess 625 (second recess). The depth dimension of the concave portion 625 (second concave portion) constituting the slide blocking structure 623 is greater than the depth dimension of the concave portion 621 (first concave portion) constituting the tab storage portion 615, and the thickness dimension of the tab stack group 607. [See FIG. 20D]. The slide blocking structure 623 has a function of blocking the cover member 613 from sliding relative to the current collector 609b when performing friction stir welding from the cover member 613 side. That is, the slide blocking structure 623 can prevent the displacement of the cover member 613 with respect to the current collector 609b of the terminal 609 and the tab stack 607 stored in the tab storage portion 615 (the current collector tab 605 and the current collector). 609b can prevent poor contact). Further, since the cover member 613 can be easily positioned with respect to the current collector 609b of the terminal 609 and the tab stack group 607 housed in the tab housing portion 615, the tab member 613 is used to laminate the tabs during the friction stir welding. The operation | work which joins the group 607 to the electrical power collector 609b becomes easy.

Further, as in the seventh embodiment, if the tab storage portion 615 is configured by the concave portion 621 (first concave portion) and the slide prevention structure 623 is configured by the concave portion 625 (second concave portion), the terminal 609 (or the collecting member) is formed. Since the tab storage portion 615 and the slide blocking structure 623 can be configured without increasing the size of the electric body 609b), it is not necessary to increase the volume of the battery case. Further, the movement of the current collecting tab 605 in the tab stack group 607 is blocked by the recess 621 (first recess) constituting the tab storage portion 615, and the recess 625 (second recess) constituting the slide blocking structure 623 is formed. ) Prevents the movement of the cover member 613. Therefore, even when the tab stack group 607 and the cover member 613 are subjected to a rotational force by the cylindrical tool 616 during friction stir welding, the position of the current collection tab 605 relative to the current collector 609b is shifted. And the positional deviation of the cover member 613 can be reliably prevented [see FIGS. 21A and 21B].

Further, in the seventh embodiment, as shown in FIGS. 18 to 21, a recess 621 (first recess) constituting the tab storage portion 615 and a recess 625 (second recess) constituting the slide blocking structure 623. Therefore, there is no gap between the tab stack group 607 and the cover member 613 during the friction stir welding, and most of the tab stack group 607 is in the tab storage portion 615 during the friction stir welding. Since the tab stack group 607 can be reliably brought into contact with the cover member 613 in the housed state, poor bonding between the current collector 609b and the tab stack group 607 can be prevented.

In the seventh embodiment, as shown in FIGS. 18 to 21, the recess 621 (first recess) constituting the tab storage portion 615 and the recess 625 (second recess) constituting the slide blocking structure 623 are further provided. Is formed in an intersecting state and is formed so that the joint (welded part) 617 by friction stir welding completely crosses the concave part 621 (first concave part) along the concave part 625 (second concave part). Has been. With such a configuration, a joint (welded portion) 617 is formed in which the tab laminate group 607 and the current collector 609b are completely joined in the width direction of the tab laminate group 607 (a plurality of current collecting tabs 605). Can do. Further, by forming such a joint 617, no gap is formed between the current collector 609b and the tab stack group 607 and between the plurality of current collector tabs 605 constituting the tab stack group 607. The contact resistance between the current collector 609b and the tab stack group 607 can be reduced.

Note that FIG. 22 is an enlarged view of the cross-sectional view of FIG. 20D and shows a state in which the tab stack group 607 is stored in the tab storage portion 615 (recess 621). As shown in this figure, the depth dimension d of the concave portion 621 (first concave portion) constituting the tab storage portion 615 is smaller than the thickness dimension t of the tab stack group 607. In other words, the thickness dimension t of the tab stack group 607 is larger than the depth dimension d of the recess 621 (first recess). Thereby, when the cover member 613 is disposed in the concave portion 625 (second concave portion) constituting the slide prevention structure 623, there is no gap between the tab stack group 607 and the cover member 613, and the friction stirring is performed. Friction stir welding can be performed in a state where most of the tab stack group 607 is housed in the tab storage portion 615 when joining, so that it is possible to reliably prevent a poor connection between the current collector 609b and the tab stack group 607. Can be prevented.

FIG. 23 is a schematic view showing a ninth embodiment of the current collecting structure of the present invention. As shown in FIG. 1, when configuring a rectangular secondary battery, the negative electrode terminal portion and the positive electrode terminal portion are respectively exposed from either one of the pair of wall portions facing each other of the battery case. The positions of the negative electrode terminal and the positive electrode terminal are determined. On the other hand, as shown in FIG. 23, the negative terminal 709 (exposed portion 709a and terminal base 709b) and the positive terminal 711 (exposed portion 711a and so on) are exposed from a pair of opposing wall portions of a battery case (not shown). The position of the terminal base 711b) is defined. By disposing the negative electrode terminal 709 and the positive electrode terminal 711 in this manner, the negative electrode current collecting tab and the positive electrode current collecting tab do not intersect on the bottom surface side or the lid side of the battery case, and thus a secondary battery that is difficult to be short-circuited can be provided. it can. Further, such a current collecting structure can be employed for a cylindrical secondary battery because the negative electrode terminal 709 and the positive electrode terminal 711 are respectively exposed from the pair of wall portions facing each other of the battery case.

FIG. 24 is a schematic view showing a tenth embodiment of the current collecting structure of the present invention. FIG. 25 is a schematic process diagram showing a part of the process of the method of manufacturing the current collecting structure (tenth embodiment) of FIG. 24 [FIG. 25A is a tab stack group in the tab storage portion of the current collector. FIG. 25 (B) is a diagram showing a state in which friction stir welding is performed after storing the cover member and before placing the cover member. In this example, the negative terminal 809 and the positive terminal 811a are exposed from the upper wall (cover 802) of the pair of facing walls of the battery case 801, respectively. The position is fixed.

Terminal base portions

809b and 811b of the negative electrode terminal 809 and the positive electrode terminal 811 are disposed inside the battery case 801 and the lid portion 802, and a pair of

side walls

801a and 801a facing the battery case 801 from the negative electrode terminal portion 809a and the positive electrode terminal portion 811a. First current collector halves 809b and 811b extending in the direction of 801b are formed. The second

current collector halves

809d and 811d are connected to the first current collector halves 809b and 811b (

terminal bases

809b and 811b). One end of each of the second

current collector halves

809d and 811d is connected to the

ends

809c and 811c of the first current collector halves 809b and 811b, and a pair of battery cases 801 is connected to the

ends

809c and 811c. Of the pair of opposing wall portions of the battery case 801 and extending toward the lower wall portion (bottom portion 801c). The second

current collector halves

809d and 811d are provided with through

holes

809e and 811e (see FIG. 25). In this example, the electrode plate group 803 is housed in the battery case 801 in a posture in which the electrode plate direction is directed in a direction in which the lid portion 802 and the bottom portion 801c of the battery case 801 face each other. Two tab laminated groups 807 extending from a plurality of electrode plates (the negative electrode plate 803a and the positive electrode plate 803b) in the electrode plate group 3 have through

holes

809e and 811e formed in the second current

collector half portions

809d and 811d. The divided tab

laminated groups

807A and 807B having the tip divided into two in a state of passing through are provided. The two divided tab stacked

groups

807A and 807B are bent along

joint surfaces

809f and 811f on the side opposite to the surface facing the electrode plate group 803 of the second

current collector half

809d and 811d. [FIG. 25 (A)]. Then, the divided tab stacked

groups

807A and 807B are sandwiched between the cover member 813 and the second current

collector half portions

809d and 811d, and are subjected to the second current collector by friction stir welding as described above. It is joined to the joining

surfaces

809f and 811f of the

body half parts

809d and 811d and the cover member 813 [FIG. 25 (B)]. In this example, a tab storage portion 815 is configured by the through

holes

809e and 811e and the

joint surfaces

809f and 811f. In such a structure, even if a rotational force from the tool is applied to the tab stack group 807 during friction stir welding, the tab stack group 807 is supported at the corners between the through

holes

809e and 811e and the

joint surfaces

809f and 811f. Therefore, the plurality of current collecting tabs 805 in the tab stacking group 807 are not slid by the rotational force applied from the tool, but are stored in the tab storage unit 815 and the tab stacking group 807 and the current collector (second The

current collector halves

809d and 811d) and the tab stack group 807 and the cover member 813 can be joined by friction stir welding. Further, according to such a structure, a structure in which the negative electrode current collecting tab and the positive electrode current collecting tab do not cross each other (a current collecting structure that is difficult to be short-circuited) can be adopted for the square secondary battery.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments and examples. That is, the dimensions, materials, shapes, relative positions, and the like of the components described in the above-described embodiments can be changed based on the technical idea of the present invention unless otherwise specified. is there.

According to the present invention, at least one part of the tab stack group is accommodated in at least one of the current collector and the cover member, and a plurality of current collector tabs in the tab stack group slide at the time of friction stir welding. Since the tab storage portion having the blocking structure is provided, the friction stir welding between the tab stack group and the current collector can be performed in a state where the tab stack group is stored in the tab storage portion. As a result, the friction stir welding reduces the contact resistance between the tab stack group and the current collector, and at the same time prevents the current collecting tab from sliding during the friction stir welding. Even if the number of stacked tabs is increased, the contact failure between the current collecting tab and the current collector can be reduced while reducing the electrical resistance between the current collecting tab and the current collector.

DESCRIPTION OF SYMBOLS 1 Battery case 3 Electrode plate group 3a, 3b Electrode plate 5 Current collection tab 7 Tab laminated group 9 Terminal (negative electrode terminal)
11 terminals (positive terminal)
13 Cover member 15 Tab storage part 17 Welded part (joint part)
621 recess (first recess)
623 Slide blocking structure 625 Concave portion (second concave portion)

Claims

A terminal having a current collector;
A tab laminate group in which a plurality of current collecting tabs are laminated extending from an electrode plate group in which a plurality of electrode plates are laminated via a separator;
A metal cover member that sandwiches the tab stack group with the current collector,
A current collector structure for a secondary battery in which the current collector, the tab laminate group, and the cover member are joined by friction stir welding,
At least one of the tab stack group is accommodated in at least one of the current collector and the cover member, and the plurality of current collection tabs in the tab stack group slide during the friction stir welding. Tab storage with a structure to prevent
When the friction stir welding is performed from the cover member side, a slide blocking structure that prevents the cover member from sliding relative to the current collector is provided in the current collector,
The tab storage portion is composed of a first recess formed on a surface of the current collector facing the cover member,
The slide blocking structure comprises a second recess formed on a surface of the current collector facing the cover member,
The depth dimension of the first recess is smaller than the thickness dimension of the tab stack group,
The first recess and the second recess are formed in an intersecting state,
A weld is formed by the friction stir welding so as to completely cross the first recess along the second recess,
The electrode plate group includes two tab lamination groups including a plurality of current collecting tabs extending from a plurality of electrode plates of the same polarity,
The current collection structure of a secondary battery, wherein the two tab laminate groups are separately joined to the current collector.
A terminal having a current collector;
A tab laminate group in which a plurality of current collecting tabs are laminated extending from an electrode plate group in which a plurality of electrode plates are laminated via a separator;
A metal cover member that sandwiches the tab stack group with the current collector,
A current collector structure for a secondary battery in which the current collector, the tab laminate group, and the cover member are joined by friction stir welding,
At least one of the tab stack group is accommodated in at least one of the current collector and the cover member, and the plurality of current collection tabs in the tab stack group slide during the friction stir welding. A current collecting structure for a secondary battery, characterized in that a tab storage portion having a structure for preventing the battery is provided.
The current collector is provided with a slide prevention structure that prevents the cover member from sliding relative to the current collector when the friction stir welding is performed from the cover member side. The collector structure of the secondary battery as described.
The tab storage portion is composed of a first recess formed on a surface of the current collector facing the cover member,
The current collection structure for a secondary battery according to claim 3, wherein the slide blocking structure includes a second recess formed on a surface of the current collector facing the cover member.
The current collecting structure of the secondary battery according to claim 4, wherein a depth dimension of the first recess is smaller than a thickness dimension of the tab stack group.
The first recess and the second recess are formed in an intersecting state,
The current collector structure of the secondary battery according to claim 4, wherein a weld portion is formed by the friction stir welding so as to completely cross the first recess along the second recess.
The electrode plate group includes two tab lamination groups including a plurality of current collecting tabs extending from a plurality of electrode plates of the same polarity,
The current collecting structure for a secondary battery according to claim 2, 3, 4, 5, or 6, wherein the two tab laminate groups are separately joined to the current collector.
A plurality of electrode plates each having a current collecting tab, and a group of electrode plates laminated via a separator;
A positive electrode terminal including a current collector to which one or more tab laminated groups formed by laminating a plurality of the current collecting tabs extending from a plurality of positive electrode plates in the electrode plate group are connected;
A negative electrode terminal including a current collector to which one or more tab laminated groups formed by laminating a plurality of the current collecting tabs extending from a plurality of negative electrode plates in the electrode plate group are connected;
A metal cover member that sandwiches the tab stack group with the current collector;
A battery case containing a battery component so as to expose a positive electrode terminal portion of the positive electrode terminal and a negative electrode terminal portion of the negative electrode terminal;
The current collector, the tab laminate group, and the cover member are non-aqueous electrolyte secondary batteries formed by friction stir welding,
At least one of the tab stack group is accommodated in at least one of the current collector and the cover member, and the plurality of current collection tabs in the tab stack group slide during the friction stir welding. The non-aqueous-electrolyte secondary battery characterized by the above-mentioned. The tab storage part provided with the structure which blocks | prevents is provided.
The non-aqueous electrolyte secondary battery according to claim 8, wherein the positive electrode terminal portion and the negative electrode terminal portion are exposed from a pair of opposing wall portions of the battery case.