Secondary battery

Abstract

The present invention provides a secondary battery capable of increasing the number of electrode bodies of the secondary battery and increasing the battery capacity while suppressing an increase in the number of components. A secondary battery (1) provided with a plurality of electrode bodies (40) and two battery terminals (PS, NS), the plurality of electrode bodies (40) having tab groups (51, 56) extending from both end portions, the tab group (51) on one end side in the first direction among the electrode bodies (40) being different in position in a second direction orthogonal to the thickness direction when viewed in the first direction, and the tab group (51) on the other end side in the first direction among the electrode bodies (40) being different in position in the second direction orthogonal to the thickness direction when viewed in the first direction. The positions of the tab groups (56) on the other end side in the first direction in the electrode bodies (40) are different in the second direction. The battery terminals (PS, NS) have a plurality of electrode bonding portions (27c, 27d, 28c, 28d) formed on a single member, and each of the electrode bonding portions (27c, 27d, 28c, 28d) is bonded to each of the tab groups (51, 56) formed at a position that can be bonded to the electrode bonding portions (27c, 27d, 28c, 28d).

Description

TECHNICAL FIELD

[0001] The present application relates to a secondary battery. BACKGROUND

[0002] In the past, a secondary battery used in an electric vehicle, such as an electric automobile, which uses a motor as a drive source, has an electrode body, a case that houses the electrode body, a battery terminal that is mounted to the case and electrically connected to the electrode body, and the like. In such a secondary battery, for example, there is a case in which a plurality of electrode bodies are housed in the case in order to achieve high capacity. As such a secondary battery having a plurality of electrode bodies, a battery manufactured by a method disclosed in Patent Literature 1 has been proposed.

[0003] The battery described in Patent Literature 1 houses an electrode body group composed of three electrode bodies in a battery case, and the three electrode bodies are connected to a positive electrode terminal and a negative electrode terminal. Specifically, in the battery described in Patent Literature 1, inside the battery case, a current collecting portion of the positive electrode terminal is electrically connected to a positive electrode of each of the electrode bodies, and a current collecting portion of the negative electrode terminal is electrically connected to a negative electrode of each of the electrode bodies.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2023-97821 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the battery disclosed in Patent Literature 1, each of the current collecting portions of the positive electrode terminal and the negative electrode terminal (battery terminal) is composed of a member constituting a first current collecting portion and three members constituting second current collecting portions that are respectively joined to the first current collecting portion and the electrode bodies. That is, in this battery, for each of the electrode bodies connected to the terminal, one member constituting a second current collecting portion is also required. Thus, in the battery described in Patent Literature 1, the members constituting the second current collecting portions are increased or decreased in correspondence with the number of electrode bodies housed in the battery, and in order to increase the number of electrode bodies, an increase in the number of parts constituting the battery terminal cannot be avoided.

[0009] The present application has been made in view of the above actual circumstances, and an object thereof is to provide a secondary battery that can increase the number of electrode bodies of the secondary battery and increase the capacity of the battery while suppressing an increase in the number of parts.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] The secondary battery according to the present application is characterized by comprising a case having an opening, a lid body attached to the opening of the case, a plurality of electrode bodies each having a positive electrode member and a negative electrode member stacked with a separator interposed therebetween, and two battery terminals attached to the lid body, the plurality of electrode bodies each having a tab group in which the positive electrode member and the negative electrode member are stacked, the tab group being arranged in a thickness direction of the electrode body and housed in the case, the tab group extending from both ends in a first direction orthogonal to the thickness direction, the tab group on one end side in the first direction in each of the electrode bodies being different in position in a second direction orthogonal to the thickness direction, the tab group on the other end side in the first direction in each of the electrode bodies being different in position in the second direction, each of the two battery terminals having a plurality of electrode engaging portions formed in a single member, each of the electrode engaging portions of one of the battery terminals being formed at a position capable of engaging with the tab group on the one end side in the first direction of each of the electrode bodies, each of the electrode engaging portions of the other of the battery terminals being formed at a position capable of engaging with the tab group on the other end side in the first direction of each of the electrode bodies, and each of the electrode engaging portions being bent so as to overlap with an end surface of the electrode body in the first direction in a state where each of the electrode engaging portions engages with each of the tab groups formed at a position capable of engaging with the electrode engaging portion.

[0012] According to the above configuration, since the tabs of each of the electrode bodies can be engaged with the plurality of electrode engaging portions formed in a single member, even if the number of the electrode bodies is increased, the increase in the number of parts is suppressed. That is, according to the secondary battery of the present application, it is possible to increase the number of the electrode bodies while suppressing the increase in the number of parts, thereby increasing the capacity of the battery.

[0013] Further, the tab group on the one end side in the first direction in each of the electrode bodies and the electrode engaging portion formed at a position corresponding thereto are different in position in the second direction, and the tab group on the other end side in the first direction in each of the electrode bodies and the electrode engaging portion formed at a position corresponding thereto are different in position in the second direction. Thus, engagement of each of the tab groups with each of the electrode engaging portions can be performed by ultrasonic bonding using a horn and an anvil.

[0014] Further, the tab group on the one end side in the first direction in each of the electrode bodies and the electrode engaging portion formed at a position corresponding thereto are different in position in the second direction, and the tab group on the other end side in the first direction in each of the electrode bodies and the electrode engaging portion formed at a position corresponding thereto are different in position in the second direction. Thus, engagement of each of the tab groups with each of the electrode engaging portions can be performed by ultrasonic bonding using a horn and an anvil.

[0015] According to the above feature, in a thickness direction of the electrode body, the fixing axis of each electrode body becomes a state of not coinciding with the fixing axis of the other electrode body, and rotation of the electrode body around the fixing axis is suppressed by the other electrode body. Thus, in the secondary battery of the present application, the shaking of the electrode body is suppressed.

[0016] Further feature of the secondary battery of the present application is that, in the aforementioned battery terminal, a thin-walled portion is formed in a manner of being divided by regions in which each of the aforementioned electrode junctions is formed, in the aforementioned first direction.

[0017] According to the above feature, since the battery terminal is easily divided into a plurality of portions along the thin-walled portion, work efficiency at the time of disassembly of the secondary battery is improved.

[0018] Further feature of the secondary battery of the present application is that the aforementioned tab group is formed at a central portion in a thickness direction of each of the aforementioned electrode bodies, in the aforementioned first direction.

[0019] According to the above feature, the number of the tabs of the positive electrode member and the negative electrode member constituting the tab group is easily increased. Thus, the number of the tabs is increased to increase the conduction path, and the conduction path is shortened as a whole of the electrode members, so that a secondary battery with less current loss can be realized.

[0020] Effects of the Invention

[0021] As described above, according to the secondary battery of the present application, the number of the electrode bodies can be increased to increase the capacity of the battery while suppressing an increase in the number of parts. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is an exploded perspective view of a secondary battery according to an embodiment.

[0023] Figure 2 is a cross-sectional view showing a schematic structure of a secondary battery.

[0024] Figure 3 is a perspective view showing an electrode body with a portion expanded.

[0025] Figure 4 is a front view showing an electrode body.

[0026] Figure 5 is a front view for explaining a positional relationship between two electrode bodies and a current collecting terminal before ultrasonic bonding.

[0027] Figure 6 is a side view for explaining a positional relationship between two electrode bodies and a current collecting terminal at the time of ultrasonic bonding.

[0028] Figure 7is a perspective view showing a state in which two electrode bodies are assembled at the current collecting terminal.

[0029] Figure 8 is a perspective view showing the current collecting terminal relating to another embodiment.

[0030] Figure 9 is a side view showing the internal structure of the negative electrode side of the secondary battery relating to another embodiment. DETAILED DESCRIPTION

[0031] Hereinafter, a secondary battery relating to an embodiment of the present application will be described with reference to the drawings. Note that hereinafter, the secondary battery will be described taking the case where the secondary battery is a lithium-ion secondary battery. Furthermore, hereinafter, each description and each drawing will be appropriately simplified in order to make the description clear.

[0032] [Outline of secondary battery 1]

[0033] Reference will be made to Figure 1 and Figure 2 , an outline of the secondary battery 1 relating to the present embodiment will be described. Note that hereinafter, Figure 1 is an exploded perspective view of the secondary battery 1. Furthermore, Figure 2 is a cross-sectional view showing the schematic structure of the above-described secondary battery 1. Note that in the following description, the direction parallel to the height direction of the secondary battery 1 will be referred to as the Z-axis direction, the direction parallel to the winding axis direction of the electrode body 40 will be referred to as the X-axis direction, and the direction parallel to the thickness direction of the electrode body 40 will be referred to as the Y-axis direction. The Z-axis direction is the direction parallel to the up-down direction, and the X-axis direction and the Y-axis direction are directions orthogonal to each other and parallel to the horizontal direction. Note that in the present embodiment, the X-axis direction corresponds to the "first direction", and the Z-axis direction corresponds to the "second direction".

[0034] As shown in Figure 1 and Figure 2 , the secondary battery 1 includes a battery case 10 composed of a case main body 11 and a sealing plate 13, a battery terminal PS, NS composed of external terminals 25, 26 and current collecting terminals 27, 28 and mounted on the sealing plate 13, two electrode bodies 40, 40 electrically connected to the current collecting terminals 27, 28, and the like. The secondary battery 1 is a sealed secondary battery in which the two electrode bodies 40, the current collecting terminals 27, 28, and the like are housed inside the case main body 11, the opening of the case main body 11 is closed with the sealing plate 13, and an electrolyte solution is injected into the inside of the case main body 11.

[0035] [Structure of battery case 10]

[0036] As shown in Figure 1 and Figure 2As shown, the battery case 10 of the present embodiment is composed of a case main body 11 of a substantially rectangular parallelepiped shape with an upper opening and a closure plate 13 that closes the opening of the case main body 11. In the battery case 10 of the present embodiment, both the case main body 11 and the closure plate 13 are made of aluminum, but are not limited thereto. In the materials of the case main body 11 and the closure plate 13, various metals, alloys can be used. In the present embodiment, the case main body 11 corresponds to a "box body" and the closure plate 13 corresponds to a "cover body".

[0037] In the present embodiment, the closure plate 13 has a shape corresponding to the shape of the opening of the case main body 11 and is configured to be able to close the opening of the case main body 11. Specifically, the closure plate 13 of the present embodiment is composed of a flat plate member that is substantially rectangular in shape as viewed in the Z-axis direction. The closure plate 13 is provided with the positive electrode battery terminal PS on one end side in the long side direction (X-axis direction) and the negative electrode battery terminal NS on the other end side in the long side direction.

[0038] The details will be described later, but in the present embodiment, the outer peripheral edge portion 13a of the closure plate 13 and the opening edge portion 11a of the case main body 11 are laser-welded, and the opening of the case main body 11 is closed by the closure plate 13.

[0039] [Structure of electrode body 40]

[0040] Figure 3 is a perspective view showing the electrode body 40 with a portion expanded. Figure 4 is a front view showing the electrode body 40. As shown in Figure 3 and Figure 4 shown, the electrode body 40 is composed of a winding body obtained by winding the long-size belt-shaped positive electrode member 41 and the negative electrode member 46 in a state of being layered with the same belt-shaped separator 49 and compressing the winding body into a flat shape. In the present embodiment, the positive electrode member 41 is an aluminum foil and the negative electrode member 46 is a copper foil.

[0041] The positive electrode member 41 has a positive electrode coated portion 41a in which a positive electrode active material is coated on both surfaces, and has a positive electrode uncoated portion 41b in which the positive electrode active material is not coated, on the end portion on one side in the X-axis direction. In addition, the positive electrode member 41 has a plurality of positive electrode tabs 42 that extend outwardly from the end portion on one side in the X-axis direction at intervals from each other. Further, the intervals of the plurality of positive electrode tabs 42 from each other are set so that a positive electrode tab group 51 is formed on the lower side than the central portion in the height direction of the electrode body 40 after winding.

[0042] The negative electrode member 46 has a negative electrode coated portion 46a in which a negative electrode active material is applied to both surfaces, and a negative electrode uncoated portion 46b in which the negative electrode active material is not applied, at the end portion on the other side in the X-axis direction. Further, the negative electrode member 46 has a plurality of negative electrode tabs 47 extending outward from the end portion on the other side in the X-axis direction, at intervals from each other. In addition, the intervals of the plurality of negative electrode tabs 47 from each other are set so that a negative electrode tab group 56 is formed on the upper side of the central portion in the height direction of the electrode body 40 after winding.

[0043] The separator 49 is configured to insulate the positive electrode coated portion 41a of the positive electrode member 41 from the negative electrode coated portion 46a of the negative electrode member 46. In the separator 49, an ion-permeable and insulating material (for example, a porous insulating resin material or the like) can be used.

[0044] The electrode body 40 extends the positive electrode tab group 51 from the one end portion in the winding axis direction (X-axis direction), and extends the negative electrode tab group 56 from the other end portion. The positive electrode tab group 51 and the negative electrode tab group 56 are formed by layering the positive electrode tabs 42 and the negative electrode tabs 47 in layers when winding the positive electrode member 41 and the negative electrode member 46 in which a plurality of positive electrode tabs 42 and negative electrode tabs 47 are formed.

[0045] The positive electrode tab group 51 of the present embodiment extends from the portion in the one end portion of the electrode body 40, which is on the one side in the thickness direction (Y-axis direction) of the electrode body 40 and on the lower side than the central portion in the height direction (Z-axis direction) of the electrode body 40, as viewed in the winding axis direction (X-axis direction), along the winding axis direction. On the other hand, the negative electrode tab group 56 extends from the portion in the other end portion of the electrode body 40, which is on the one side in the thickness direction of the electrode body 40 and on the upper side than the central portion in the height direction of the electrode body 40, as viewed in the winding axis direction, along the winding axis direction. In addition, the positive electrode tab group 51 and the negative electrode tab group 56 are rectangular shapes in which the long side direction is parallel to the height direction of the electrode body 40, as viewed in the thickness direction of the electrode body 40.

[0046] In this way, the positive electrode tab group 51 of the electrode body 40 of the present embodiment, which extends from the one end portion in the X-axis direction, and the negative electrode tab group 56, which extends from the other end portion, are different in position in the height direction of the electrode body 40.

[0047] The secondary battery 1 of the present embodiment has two electrode bodies 40, which are housed in the case main body 11 in a state in which the one electrode body 40 is inverted upside down in the thickness direction (Y-axis direction). That is, in the present embodiment, the positive electrode tab groups 51 of the two electrode bodies 40 arranged in the thickness direction are staggered upside down in the position in the Z-axis direction, and similarly the negative electrode tab groups 56 are also staggered upside down in the position in the Z-axis direction (see FIG. 6). Figure 1 ​

[0048] 〔Positive electrode side and negative electrode side structures〕

[0049] In the present embodiment, the secondary battery 1 has, as the positive electrode side structure, a positive electrode battery terminal PS constituted by a positive electrode external terminal 25 and a positive electrode current collecting terminal 27, a positive electrode insulating member 29, and a positive electrode gasket 31. Further, the secondary battery 1 has, as the negative electrode side structure, a negative electrode battery terminal NS constituted by a negative electrode external terminal 26 and a negative electrode current collecting terminal 28, a negative electrode insulating member 30, and a negative electrode gasket 32.

[0050] Detailed explanations are omitted, but in the secondary battery 1 of the present embodiment, the positive electrode external terminal 25, the positive electrode current collecting terminal 27, and the negative electrode external terminal 26, the negative electrode current collecting terminal 28 are integrated by caulking to constitute each battery terminal PS, NS. In the present embodiment, both the positive electrode external terminal 25 and the positive electrode current collecting terminal 27 that constitute the positive electrode battery terminal PS are made of aluminum. On the other hand, with respect to the negative electrode battery terminal NS, the negative electrode external terminal 26 is made of aluminum, and the negative electrode current collecting terminal 28 is made of copper.

[0051] In the present embodiment, the positive electrode external terminal 25 and the negative electrode external terminal 26 are insulated from the sealing plate 13 by the positive electrode gasket 31 and the negative electrode gasket 32. Further, the positive electrode current collecting terminal 27 and the negative electrode current collecting terminal 28 are insulated from the sealing plate 13 by the positive electrode insulating member 29 and the negative electrode insulating member 30. Each battery terminal PS, NS is maintained airtight from the sealing plate 13 by each insulating member 29, 30 and each gasket 31, 32. In the present embodiment, each insulating member 29, 30 and each gasket 31, 32 are constituted by PFA resin, but are not limited thereto. The material of each insulating member 29, 30 and each gasket 31, 32 can have only insulating properties.

[0052] In the present embodiment, each current collecting terminal 27, 28 is bent from a plate-shaped member, and has a base portion 27a, 28a that is caulked to each external terminal 25, 26, a main portion 27b, 28b that is continuous with the base portion 27a, 28a, and a first electrode joint portion 27c, 28c and a second electrode joint portion 27d, 28d that are continuous with the main portion 27b, 28b. That is, two electrode joint portions 27c, 27d, 28c, 28d in each current collecting terminal 27, 28 are formed in a single member.

[0053] In the present embodiment, each of the current collecting tabs 27, 28 is substantially rectangular in shape as viewed in the Z-axis direction, and is disposed on the lower surface side of the sealing plate 13 with the base portion 27a, 28a along the horizontal direction. The main portion 27b, 28b of each of the current collecting tabs 27, 28 is a portion that is substantially rectangular in shape as viewed in the X-axis direction, and extends from the end portion of the base portion 27a, 28a toward the lower side in the Z-axis direction, and is disposed between the electrode body 40 and the end side wall of the case main body 11.

[0054] The two electrode engaging portions 27c, 27d, 28c, 28d of each of the current collecting tabs 27, 28 are formed at positions that can engage with the tab groups 51, 56 of the electrode body 40. Specifically, each of the electrode engaging portions 27c, 27d, 28c, 28d before the assembly of the electrode body 40 is a portion that is substantially rectangular in shape as viewed in the Y-axis direction, and extends from both side edge portions in the main portion 27b, 28b in the X-axis direction, the first electrode engaging portion 27c, 28c is formed on the upper side from the center in the Z-axis direction, and the second electrode engaging portion 27d, 28d is formed on the lower side from the center in the Z-axis direction. The tab groups 51, 56 are engaged with the faces (engaging faces) on the outer sides of each of the electrode engaging portions 27c, 27d, 28c, 28d in the Y-axis direction. As will be described later, the two electrode engaging portions 27c, 27d, 28c, 28d of each of the current collecting tabs 27, 28 are bent in a state where each of the electrode engaging portions 27c, 27d, 28c, 28d engages with the corresponding tab group 51, 56, so that the engaging portions of each of the electrode engaging portions 27c, 27d, 28c, 28d and each of the tab groups 51, 56 overlap with the end face of the electrode body 40 in the X-axis direction (see Figure 2 and Figure 7 ).

[0055] Next, a method of assembling the two electrode bodies 40 to each of the current collecting tabs 27, 28 will be described with reference to Figures 5-7 Figure 5 is a front view for explaining the positional relationship between the two electrode bodies 40 and each of the current collecting tabs 27, 28 before ultrasonic bonding. Figure 6 is a side view for explaining the positional relationship between the two electrode bodies 40 and each of the current collecting tabs 27, 28 at the time of ultrasonic bonding. Figure 7 is a perspective view showing a state where the two electrode bodies 40 are assembled to each of the current collecting tabs 27, 28. In Figure 7 , the structures of the sealing plate 13, the external terminals 25, 26, and the like are omitted from the drawing.

[0056] First, as shown in Figure 5 ​As shown, the two electrode bodies 40 are arranged on the respective current collector terminals 27 and 28 attached to the sealing plate 13 so that the electrode joints 27 c, 27 d, 28 c, and 28 d and the tab groups 51 and 56 corresponding to the electrode joints 27 c, 27 d, 28 c, and 28 d face each other in the Y-axis direction. That is, the positive electrode current collector terminal 27 is arranged so that the positive electrode tab group 51 of one electrode body 40 faces the second electrode joint 27 d, and the positive electrode tab group 51 of the other electrode body 40 faces the first electrode joint 27 c. Furthermore, the negative electrode current collector terminal 28 is arranged so that the negative electrode tab group 56 of one electrode body 40 faces the first electrode joint 28 c, and the negative electrode tab group 56 of the other electrode body 40 faces the second electrode joint 28 d.

[0057] Next, the electrode joining portions 27c, 27d, 28c, 28d are joined to the tab groups 51, 56. Specifically, the electrode joining portions 27c, 27d, 28c, 28d are brought into contact with the mutually opposing surfaces of the tab groups 51, 56, and ultrasonically joined to the tab groups 51, 56 using a horn H and anvil A.

[0058] Here, in the secondary battery 1 of this embodiment, on both the positive and negative sides, the tab groups 51, 56 of the electrode body 40 on one side and the electrode joints 27d, 28c facing thereto are offset vertically in the Z-axis direction from the tab groups 51, 56 of the electrode body 40 on the other side and the electrode joints 27c, 28d facing thereto.

[0059] Therefore, if Figure 6 As shown, for example, on the negative electrode side, there is a space on the side of the first electrode joint 28c and the second electrode joint 28d that is not opposite to the negative electrode tab group 56. Therefore, the anvil A can be pushed against the first electrode joint 28c of the negative electrode current collector terminal 28, and the horn H can be pushed against the negative electrode tab group 56 (located at the negative electrode tab group 56) of the electrode body 40 on one side. Figure 6 The negative electrode tab group 56 on the upper right of the electrode body 40 is pressed and ultrasonic vibrations are applied in the horizontal direction by the horn, thereby joining the first electrode joint 28c to the negative electrode tab group 56 of the electrode body 40 on one side. Similarly, the second electrode joint 28d and the negative electrode tab group 56 of the electrode body 40 on the other side can also be joined by ultrasonic bonding using the horn H and the anvil A. In addition, although not shown in the figure, there is a space on the positive side of the first electrode joint 27c and the second electrode joint 27d that is not opposite to the positive electrode tab group 51. Therefore, the electrode joints 27c and 27d of the positive current collector terminal 27 can be joined to the positive electrode tab group 51 by ultrasonic bonding using the horn H and the anvil A.

[0060] Then, in a state where each electrode joint portion 27c, 27d, 28c, 28d is joined to each tab group 51, 56, it is bent so that each joint portion overlaps with the end face of the electrode body 40 in the X-axis direction. Specifically, each electrode joint portion 27c, 27d of the positive collector terminal 27 is bent so that the surface opposite to the side facing the positive tab group 51 abuts against the side face of the main portion 27b. In addition, each electrode joint portion 28c, 28d of the negative collector terminal 28 is bent so that the surface opposite to the side facing the negative tab group 56 abuts against the side face of the main portion 28b. Thus, as Figure 7 As shown, two electrode bodies 40 are assembled to the current collecting terminals 27 and 28 .

[0061] In this manner, the secondary battery 1 of this embodiment can join the tab groups 51 and 56 of the two electrode bodies 40 to the electrode joining portions 27 c, 27 d, 28 c, and 28 d of the current collector terminals 27 and 28, each formed of a single component. This allows the number of electrode bodies 40 to be increased while suppressing an increase in the number of parts, thereby increasing the battery capacity.

[0062] In the secondary battery 1 of this embodiment, the positions of the positive electrode tab group 51 and the negative electrode tab group 56 of each electrode body 40 in the Z-axis direction are different. Furthermore, the electrode joints 27c, 27d, 28c, and 28d are fixed to the positive electrode tab group 51 and the negative electrode tab group 56 in the Z-axis direction of each electrode body 40. Figure 2 As shown, the fixed axis P1 of one electrode body 40 extends obliquely upward from the positive electrode tab group 51 toward the negative electrode tab group 56 when viewed in the Y-axis direction, and the fixed axis P2 of the other electrode body 40 extends obliquely downward from the positive electrode tab group 51 toward the negative electrode tab group 56 when viewed in the Y-axis direction. In other words, each fixed axis P1 and P2 extends obliquely with respect to the X-axis direction between the positive electrode tab group 51 and the negative electrode tab group 56 of each electrode body 40, with fixed axis P1 intersecting fixed axis P2. Therefore, rotation about the fixed axis of each electrode body 40 is suppressed by the other electrode body 40. Thus, in the secondary battery 1 of this embodiment, shaking of each electrode body 40 is suppressed. In addition, in this embodiment, the positive electrode tab group 51 of each electrode body 40 corresponds to the "tab group on one end side in the first direction," and the negative electrode tab group 56 corresponds to the "tab group on the other end side in the first direction."

[0063] [Other Implementation Methods]

[0064] 〔1〕 In the above-described embodiments, the configuration in which each electrode joining portion 27c, 27d, 28c, 28d of each current collecting tab 27, 28 extends from the edge portion of the main portion 27b, 28b in the X-axis direction has been described, but the configuration is not limited to this. The shape of each current collecting tab is not particularly limited as long as it has a plurality of electrode joining portions.

[0065] Figure 8 is a perspective view showing a current collecting tab 60 according to another embodiment. The current collecting tab 60 can also have, for example, the shape shown in Figure 8 . The current collecting tab 60 has a base portion 60a, a main portion 60b continuous with the base portion 60a, a first electrode joining portion 60c standing up between a pair of slits S1 formed with one edge portion of the main portion 60b as a starting end, and a second electrode joining portion 60d standing up between a pair of slits S2 formed with the other edge portion of the main portion 60b as a starting end.

[0066] Further, in the current collecting tab 60, thin wall portions 61, 62 are formed so as to divide a region R1 in which the first electrode joining portion 60c is formed and a region R2 in which the second electrode joining portion 60d is formed, in observation in the X-axis direction. Specifically, in the current collecting tab 60, the thin wall portions 61, 62 extending from the terminal end of each slit S1, S2 to the edge portion of the main portion 60b are formed.

[0067] Even if this current collecting tab 60 is used, it is possible to increase the number of electrode bodies while suppressing an increase in the number of parts, thereby increasing the capacity of the battery, and it is possible to ultrasonically join each electrode joining portion 60c, 60d to each tab group 51, 56 using the horn H and the anvil A. Further, the current collecting tab 60 is easily divided along the thin wall portions 61, 62, and the current collecting tab 60 is separated from the two electrode bodies 40 by the thin wall portions 61, 62. Therefore, if the current collecting tab 60 is used, the work efficiency at the time of disassembling the secondary battery is improved.

[0068] 〔2〕 In the above-described embodiments, the configuration in which each tab group 51, 56 extends from the portion of each end portion of the electrode body 40, which is located on one side in the thickness direction (Y-axis direction) of the electrode body 40, in observation in the winding axis direction (X-axis direction) has been described, but the configuration is not limited to this. Figure 9 is a side view showing the internal configuration of the negative electrode side of a secondary battery according to another embodiment. For example, as shown in Figure 9Also, as shown in FIG. 1, the negative tab group 56 can extend from the central portion in the thickness direction (Y-axis direction) of the electrode body 40 as viewed in the winding axis direction (X-axis direction). If so, the number of negative tabs 47 of the negative members 46 constituting the negative tab group 56 can be easily increased. Thus, the number of tabs can be increased to increase the conduction path, and the conduction path can be shortened as a whole of the members, so that a secondary battery with less current loss can be achieved. Also, the same applies to the positive tab group 51, and the positive tab group 51 can also extend from the central portion in the thickness direction (Y-axis direction) of the electrode body 40 as viewed in the winding axis direction (X-axis direction).

[0069] Also, in the configuration in which each tab group extends from the central portion in the thickness direction (Y-axis direction) of the electrode body as viewed in the winding axis direction (X-axis direction), the current collecting terminal 60 is preferably used in comparison with the current collecting terminals 27 and 28. In the current collecting terminals 27 and 28, the electrode engaging portions 27c, 27d, 28c, and 28d extend from the edge portions on both sides in the main portions 27b and 28b in the X-axis direction. Thus, in the case where the current collecting terminals 27 and 28 are used, the size of the main portions 27b and 28b has to be reduced, and the conduction path is narrowed. In contrast, if the current collecting terminal 60 is used, the reduction in the size of the main portion 60b can be suppressed in comparison with the case where the current collecting terminals 27 and 28 are used, and the conduction path can be widened.

[0070] 〔3〕 In the above-described embodiment, the configuration in which two electrode bodies 40 are provided is described, but the configuration is not limited to this. The number of electrode bodies can be three or more. In this case, if the number of electrode engaging portions of the current collecting terminal is increased in correspondence with the number of electrode bodies, the number of electrode bodies can be increased while the increase in the number of parts is suppressed.

[0071] 〔4〕 In the above-described embodiment, the configuration in which the positive tab group 51 and the negative tab group 56 of each electrode body 40 are different in position in the Z-axis direction is described, but the configuration is not limited to this. The positive tab group and the negative tab group of each electrode body can be the same in position in the Z-axis direction. If, for example, the secondary battery has two electrode bodies as in the above-described embodiment, the positive tab group and the negative tab group of one electrode body can be arranged on the upper side from the center in the Z-axis direction, and the positive tab group and the negative tab group of the other electrode body can be arranged on the lower side from the center in the Z-axis direction. In this case, the positive tab groups of the two electrode bodies arranged in the thickness direction are staggered in position in the Z-axis direction, and the same applies to the negative tab groups.

[0072] 〔5〕 In the above-described embodiment, the electrode body 40 is described as being in the form of a wound body, but is not limited to such a form. The electrode body 40 is not particularly limited as long as it has a configuration of a positive electrode tab group and a negative electrode tab group, and various configurations used in general sealed secondary batteries can be adopted.

[0073] In addition, the structure disclosed in the above-described embodiment (including other embodiments, the same hereinafter) can be combined with the structure disclosed in other embodiments and applied, as long as there is no contradiction, and the embodiments disclosed in the present specification are examples, and the embodiments of the present application are not limited thereto, and can be appropriately changed within a range not departing from the object of the present application.

[0074] Explanation of Reference Signs

[0075] 1: Secondary battery

[0076] 11: Case main body (box)

[0077] 13: Sealing plate (cover)

[0078] 40: Electrode body

[0079] 41: Positive electrode member

[0080] 42: Positive electrode tab

[0081] 46: Negative electrode member

[0082] 47: Negative electrode tab

[0083] 49: Partition member

[0084] 51: Positive electrode tab group

[0085] 56: Negative electrode tab group

[0086] PS: Positive battery terminal (battery terminal)

[0087] NS: Negative battery terminal (battery terminal)

[0088] 27, 28: Current collecting terminal

[0089] 27c, 28c: First electrode joint (one of a plurality of electrode joints)

[0090] 27d, 28d: Second electrode joint (one of a plurality of electrode joints)

Claims

1. A secondary battery comprising a case having an opening, a cover mounted on the opening of the case, a plurality of flat electrode bodies formed by stacking positive and negative electrode members with separators interposed therebetween, and two battery terminals mounted on the cover, wherein: The aforementioned multiple electrode bodies The positive electrode member and the negative electrode member are stacked together to form a tab group, which is arranged in the thickness direction of the electrode body and housed in the box. The tab group extends from both ends in a first direction perpendicular to the thickness direction. When viewed in the first direction, the positions of the tab groups on one end side in the first direction of each electrode body in a second direction orthogonal to the thickness direction are different, and the positions of the tab groups on the other end side in the first direction of each electrode body in the second direction are different; The two aforementioned battery terminals Each of the plurality of plate-shaped electrode joints is formed on a single component. Each of the electrode-jointing portions of the battery terminal on one side is formed at a position capable of joining to the tab group on one end side of each of the electrode bodies in the first direction, and each of the electrode-jointing portions of the battery terminal on the other side is formed at a position capable of joining to the tab group on the other end side of each of the electrode bodies in the first direction; When each of the aforementioned electrode joining portions is joined to each of the aforementioned tab groups formed at a position capable of joining with the electrode joining portion, the joining portions between each of the aforementioned electrode joining portions and each of the aforementioned tab groups are bent so that they overlap with the end face of the aforementioned electrode body in the aforementioned first direction when observed in the aforementioned first direction.

2. The secondary battery according to claim 1, wherein The tab group on one end side in the first direction of each electrode body and the tab group on the other end side in the first direction are positioned differently in the second direction.

3. The secondary battery according to claim 1, wherein In the battery terminal, the thin-walled portion is formed so as to partition the region where each of the electrode-jointing portions is formed when viewed in the first direction.

4. The secondary battery according to any one of claims 1 to 3, wherein The tab group is formed at a center portion in a thickness direction of each of the electrode bodies when viewed in the first direction.

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