Secondary battery

Abstract

To provide a secondary battery, equipped with a collector, which has a structure for maintaining the insulation quality between a tab group and a sealing plate.SOLUTION: A secondary battery comprises: an outer package 1 which houses an electrode body 3; an external terminal 10 which is provided outside a sealing plate 2 for sealing an opening of the outer package; a connection member 11, provided inside the sealing plate, which is connected to the external terminal; an insulation member 14 which is provided between the sealing plate and the connection member; and a collector 12, disposed inside the sealing plate, which is connected to the connection member and is also connected to a tab group 40a made up of a plurality of collector tabs extending from the electrode body. The tab group has a projecting portion where at least part of the collector tabs projects from the collector in the longitudinal direction of the sealing plate. The insulation member has an extension part 14c which extends at least between the projecting portion and the sealing plate, along the longitudinal direction of the sealing plate.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to secondary batteries. [Background technology]

[0002] A known current collecting structure for a secondary battery in which an electrode body is housed in an exterior body is one in which a current collecting tab extending from the electrode body toward the sealing plate of the exterior body is connected to an external terminal via the current collector.

[0003] In such a current collecting structure, Patent Document 1 discloses a configuration in which a positive electrode plate and a negative electrode plate are wound flatly with a separator interposed therebetween as an electrode body. The positive electrode plate and the negative electrode body are each formed in a band shape, and a plurality of positive and negative current collecting tabs are formed at a predetermined interval at one end in the width direction. When the positive electrode plate and the negative electrode plate are wound to form an electrode body, the plurality of positive and negative current collecting tabs are stacked at predetermined positions to form a tab group. The positive and negative tab groups are each bundled and connected to positive and negative current collectors, and the current collectors are further connected to external terminals, thereby forming a current collecting structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2018-534725 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above current collecting structure, an insulating member is disposed between the current collector and the sealing plate in order to electrically insulate the current collector connected to the external terminal from the sealing plate.

[0006] In order to increase the output of a secondary battery, it is effective to increase the width of the current collector tab in the longitudinal direction of the sealing plate. Increasing the width of the current collector tab also increases the area of ​​the current collector to which the tab group is connected. As a result, the tab group is disposed close to the longitudinal end of the current collector.

[0007] On the other hand, the multiple current collecting tabs are formed at predetermined intervals on one end of the positive and negative electrode plates so that they are stacked at a predetermined position when the electrode body is constructed by rolling the positive and negative electrode plates into a flat shape. However, the current collecting tabs may be stacked at a position shifted from the predetermined position due to variations in the thickness of the electrode plates, the curvature of the rolled electrode plates, the pressing direction when the rolled electrode body is pressed into a flat shape, and the like.

[0008] When the tab group is connected to the current collector with the current collector tabs misaligned, some of the current collector tabs may protrude from the current collector in the longitudinal direction of the sealing plate, which may result in the protruding portion of the current collector tab coming into contact with the sealing plate and causing a loss of insulation between the tab group and the sealing plate. [Means for solving the problem]

[0009] The secondary battery according to the present disclosure comprises an electrode body having a positive electrode plate and a negative electrode plate, an exterior body having an opening and housing the electrode body, a sealing plate that seals the opening, an external terminal provided on the outside of the sealing plate, a connecting member provided on the inside of the sealing plate and connected to the external terminal, an insulating member provided between the sealing plate and the connecting member, and a current collector disposed on the inside of the sealing plate, connected to the connecting member, and connected to a tab group consisting of a plurality of current collecting tabs extending from the positive electrode plate and the negative electrode plate, wherein at least some of the current collecting tabs have protruding portions that protrude from the current collector in the longitudinal direction of the sealing plate, and the insulating member has an extending portion that extends along the longitudinal direction of the sealing plate, at least between the protruding portions and the sealing plate. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a secondary battery having a current collector, the secondary battery having a structure in which insulation is maintained between a tab group consisting of a plurality of current collecting tabs and a sealing plate. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view illustrating a schematic configuration of a secondary battery according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3A] FIG. 3A is a plan view of the positive electrode plate. [Figure 3B] FIG. 3B is a plan view of the negative electrode plate. [Figure 4A] FIG. 4A is a top view of the electrode assembly. [Figure 4B] FIG. 4B is a side view of the electrode body. [Figure 4C] FIG. 4C is a front view of the electrode body. [Diagram 5] FIG. 5 is an exploded perspective view of each component of the secondary battery excluding the exterior body and the electrode assembly. [Figure 6] FIG. 6 is an exploded perspective view of each component of the secondary battery excluding the exterior body and the electrode assembly. [Figure 7] FIG. 7 is a plan view showing a state in which the positive electrode tab group and the negative electrode tab group are connected to a positive electrode current collector and a negative electrode current collector. [Figure 8] FIG. 8 is a plan view showing a state in which a positive electrode external terminal, a negative electrode external terminal, a positive electrode connecting member, and a negative electrode connecting member are attached to the sealing plate. [Figure 9] FIG. 9 is a plan view showing a state in which the positive electrode current collector and the negative electrode current collector in the state shown in FIG. 7 are connected to the positive electrode connecting member and the negative electrode connecting member in the state shown in FIG. [Figure 10] FIG. 10 is an enlarged plan view of the positive electrode side in FIG. [Figure 11] FIG. 11 is an enlarged side view of the positive electrode side in FIG. [Figure 12] FIG. 12 is a perspective view of the sealing plate in FIG. 9 as viewed from below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the following embodiments. In addition, appropriate modifications are possible within the scope of the effects of the present disclosure.

[0013] Fig. 1 is a perspective view showing a schematic configuration of a secondary battery according to an embodiment of the present disclosure, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1.

[0014] As shown in Figs. 1 and 2, the secondary battery 100 in this embodiment includes an exterior body 1 having an opening and housing an electrode assembly 3, and a sealing plate 2 that seals the opening of the exterior body 1. The exterior body 1 and the sealing plate 2 are made of, for example, aluminum or an aluminum alloy. A positive electrode external terminal 10 and a negative electrode external terminal 20 are provided on the outside of the sealing plate 2. The electrode body 3 has a structure in which a positive electrode plate and a negative electrode plate are wound in a flat shape with a separator interposed therebetween. In this embodiment, the longitudinal direction of the sealing plate 2 refers to the direction indicated by the arrow A in Fig. 1.

[0015] Provided on the inner side of the sealing plate 2 are a positive electrode connection member 11 and a negative electrode connection member 21, which are connected to a positive electrode external terminal 10 and a negative electrode external terminal 20, respectively. Furthermore, provided on the inner side of the sealing plate 2 are a positive electrode current collector 12 and a negative electrode current collector 22, which are connected to the positive electrode connection member 11 and the negative electrode connection member 21, respectively.

[0016] The electrode body 3 has a positive electrode tab group 40a and a negative electrode tab group 50a consisting of a plurality of current collector tabs connected to the positive electrode plate and the negative electrode plate, respectively, at the end on the side of the sealing plate 2. In addition, the positive electrode tab group 40a and the negative electrode tab group 50a are connected to the positive electrode current collector 12 and the negative electrode current collector 22, respectively.

[0017] The positive electrode external terminal 10, the positive electrode connecting member 11, and the positive electrode current collector 12 are made of, for example, aluminum or an aluminum alloy. The negative electrode external terminal 20, the negative electrode connecting member 21, and the negative electrode current collector 22 are made of, for example, copper or a copper alloy.

[0018] Upper insulating members 13 and 23 are disposed between the sealing plate 2 and the positive electrode external terminal 10 and the negative electrode external terminal 20, respectively. Furthermore, insulating members 14 and 24 are disposed between the sealing plate 2 and the positive electrode connecting member 11 and the negative electrode connecting member 21, respectively. As a result, the positive electrode external terminal 10, the negative electrode external terminal 20, the positive electrode connecting member 11, and the negative electrode connecting member 21 are each electrically insulated from the sealing plate 2.

[0019] The sealing plate 2 is provided with a liquid injection hole (not shown) for injecting an electrolyte, and the liquid injection hole is sealed with a sealing member 30. The sealing plate 2 is provided with a gas exhaust valve 31, and when the pressure inside the exterior body 1 reaches or exceeds a predetermined value, the gas inside the exterior body 1 is exhausted to the outside through the ruptured gas exhaust valve 31. An insulating electrode body holder 6 is disposed between the exterior body 1 and the electrode body 3.

[0020] Next, a method for assembling the secondary battery in this embodiment and details of each component will be described with reference to FIGS. 3A to 9. FIG.

[0021] FIG. 3A is a plan view of the positive electrode plate 4. The positive electrode plate 4 is configured such that a positive electrode mixture layer containing a positive electrode active material is formed on both sides of a positive electrode core. A plurality of positive electrode current collector tabs 4a protrude from the edge of the positive electrode plate 4 at a predetermined interval. The positive electrode current collector tabs 4a may be a part of the positive electrode core or may be other members. The positive electrode core is made of, for example, aluminum foil or aluminum alloy foil. The positive electrode active material is made of, for example, a lithium transition metal composite oxide or the like.

[0022] FIG. 3B is a plan view of the negative electrode plate 5. The negative electrode plate 5 has a configuration in which a negative electrode mixture layer containing a negative electrode active material is formed on both sides of a negative electrode core. A plurality of negative electrode current collector tabs 5a protrude from the edge of the negative electrode plate 5 at a predetermined interval. The negative electrode current collector tabs 5a may be a part of the negative electrode core or may be other members. The negative electrode core is made of, for example, copper foil or copper alloy foil. The negative electrode active material is made of, for example, a carbon material or a material containing silicon.

[0023] 4A to 4C show an electrode assembly 3 formed by winding a positive electrode plate 4 and a negative electrode plate 5 in a flat shape with a separator interposed between them. Here, Fig. 4A is a top view of the electrode assembly 3, Fig. 4B is a side view of the electrode assembly 3, and Fig. 4C is a front view of the electrode assembly 3.

[0024] As shown in Figures 4A to 4C, a positive electrode tab group 40a and a negative electrode tab group 50a extend from the end sides of the electrode assembly 3. The positive electrode tab group 40a and the negative electrode tab group 50a are configured by stacking a plurality of positive electrode current collector tabs 4a and a plurality of negative electrode current collector tabs 5a at predetermined positions when the electrode assembly 3 is constructed by rolling the positive electrode plate 4 and the negative electrode plate 5 in a flat shape. The positive electrode tab group 40a and the negative electrode tab group 50a have their tips bundled together and connected to a positive electrode current collector 12 and a negative electrode current collector 22, which will be described later.

[0025] 5 and 6 are exploded perspective views of the components of the secondary battery excluding the exterior body 1 and the electrode body 3. Here, Fig. 5 is an exploded perspective view seen from above the sealing plate 2, and Fig. 6 is an exploded perspective view seen from below the sealing plate 2. Note that, although the components on the positive electrode side will be described below, the components on the negative electrode side basically have the same configuration.

[0026] 5 and 6, a positive electrode external terminal 10 and an upper insulating member 13 are disposed on the upper side of the sealing plate 2. In addition, an insulating member 14, a positive electrode connecting member 11, and a positive electrode current collector 12 are disposed on the lower side of the sealing plate 2.

[0027] The positive electrode external terminal 10 has a cylindrical protruding portion 10a. The upper insulating member 13, the sealing plate 2, the insulating member 14, and the positive electrode connecting member 11 are provided with through holes 13a, 2a, 14a, and 11a that penetrate the protruding portion 10a of the positive electrode external terminal 10, respectively.

[0028] The sealing plate 2 has a liquid injection hole 2b for injecting an electrolyte solution, and a gas exhaust valve 31 for exhausting gas inside the exterior body 1. The insulating member 14 has an opening 14b at a position that does not block the liquid injection hole 2b.

[0029] The positive electrode current collector 12 has, along the longitudinal direction of the sealing plate 2, a first connection region 12a connected to the positive electrode tab group 40a, and a second connection region 12b connected to the positive electrode connection member 11. The positive electrode current collector 12 also has a step portion 12c between the first connection region 12a and the second connection region 12b, and the first connection region 12a is located closer to the sealing plate 2 than the second connection region 12b. The positive electrode current collector 12 has a notch portion 12d at a position that does not block the liquid injection hole 2b.

[0030] In addition, since the insulating member 24 and the negative electrode current collector 22 on the negative electrode side are not positioned in a position that blocks the liquid injection hole 2b, they do not have any portions corresponding to the opening 14b and the cutout portion 12d provided in the insulating member 14 and the positive electrode current collector 12.

[0031] FIG. 7 is a plan view showing a state in which positive electrode tab groups 40a, 40b and negative electrode tab groups 50a, 50b provided on two electrode bodies 3a, 3b having the same configuration, are connected to a positive electrode current collector 12 and a negative electrode current collector 22.

[0032] Specifically, as shown in Fig. 7, two electrode bodies 3a, 3b are arranged so that the positive electrode tab groups 40a, 40b and the negative electrode tab groups 50a, 50b face each other. Then, the positive electrode tab groups 40a, 40b and the negative electrode tab groups 50a, 50b are arranged on the first connection region 12a of the positive electrode current collector 12 and the first connection region 22a of the negative electrode current collector 22, and the positive electrode tab groups 40a, 40b and the negative electrode tab groups 50a, 50b are welded to the positive electrode current collector 12 and the negative electrode current collector 22 at welding points 60, 70. The welding can be performed using, for example, ultrasonic welding, resistance welding, laser welding, or the like.

[0033] The two electrode assemblies 3a, 3b are housed in the exterior body 1 in a state in which the positive electrode tab groups 40a, 40b and the negative electrode tab groups 50a, 50b are folded so that the electrode assemblies 3a, 3b are arranged in parallel to each other.

[0034] FIG. 8 is a plan view of the sealing plate 2, viewed from below, showing the state in which the positive electrode external terminal 10, the negative electrode external terminal 20, the positive electrode connecting member 11, and the negative electrode connecting member 21 are assembled to the sealing plate 2. As shown in FIG.

[0035] 5 and 6, the upper insulating member 13, the sealing plate 2, the insulating member 14, and the positive electrode connecting member 11 are arranged with the through holes 13a, 2a, 14a, and 11a provided therein aligned with each other. Then, the protruding portion 10a of the positive electrode external terminal 10 is inserted into the through holes 13a, 2a, 14a, and 11a, and the tip portion of the protruding portion 10a is crimped onto the positive electrode connecting member 11 to fix the positive electrode external terminal 10 and the positive electrode connecting member 11 to the sealing plate 2. The positive electrode external terminal 10 and the positive electrode connecting member 11 may be further welded to each other at the crimped portion.

[0036] The insulating member 14 has a recess 14d, and the positive electrode connection member 11 is fitted into the recess 14d. A part of the recess 14d is exposed from the positive electrode connection member 11, and a positive electrode current collector 12, which will be described later, is fitted into the exposed portion.

[0037] FIG. 9 is a plan view showing a state in which the positive electrode current collector 12 and the negative electrode current collector 22 shown in FIG. 7 are connected to the positive electrode connecting member 11 and the negative electrode connecting member 21 shown in FIG.

[0038] 9, the positive electrode current collector 12 is welded to the positive electrode connecting member 11 at the second connection region 12b with the first connection region 12a fitted into the recess 14d of the insulating member 14. The welding can be performed by using, for example, laser welding or the like.

[0039] 3A, 3B, and 4A to 4C, the positive electrode current collecting tabs 4a and the negative electrode current collecting tabs 5a are formed at predetermined intervals on one end of the positive electrode plate 4 and the negative electrode plate 5 so that they are stacked at predetermined positions when the electrode body 3 is constructed by rolling the positive electrode plate 4 and the negative electrode plate 5 in a flat shape. However, they may be stacked at positions shifted from the predetermined positions due to variations in the thicknesses of the positive electrode plate 4 and the negative electrode plate 5, the curvature of the electrode body 3, the pressing direction when the rolled electrode body 3 is pressed in a flat shape, and the like.

[0040] Fig. 10 is an enlarged plan view showing the positive electrode side in Fig. 9. Note that in Fig. 10, electrode bodies 3a and 3b are omitted.

[0041] 10, the multiple positive electrode current collector tabs 4a, 4b (three are shown in FIG. 10) constituting the positive electrode tab groups 40a, 40b are stacked while being shifted from each other in the longitudinal direction of the sealing plate 2. Therefore, in the positive electrode tab groups 40a, 40b, at least some of the positive electrode current collector tabs 4a, 4b have a portion (protruding portion) that protrudes from the positive electrode current collector 12 (first connection region 12a) in the longitudinal direction of the sealing plate 2.

[0042] In particular, when the width of the positive electrode current collector tabs 4a, 4b in the longitudinal direction of the sealing plate 2 is increased in order to increase the output of the secondary battery, the first connection region 12a of the positive electrode current collector 12 to which the positive electrode tab groups 40a, 40b are connected also becomes wider. As a result, the positive electrode tab groups 40a, 40b are disposed close to the longitudinal end of the positive electrode current collector, so that the protruding portions of the positive electrode tab groups 40a, 40b become larger. Also, when the joints 60, 60 between the positive electrode current collector 12 and the positive electrode tab groups 40a, 40b are located closer to the end of the positive electrode current collector 12 than the step portion 12c in the first connection region 12a, the protruding portions of the positive electrode tab groups 40a, 40b become larger.

[0043] In this embodiment, the insulating member 14 has an extension portion 14c that extends between the protruding portions of the positive electrode tab groups 40a, 40b and the sealing plate 2 in the longitudinal direction of the sealing plate 2. Therefore, the extension portion 14c also protrudes from the positive electrode current collector 12 in the longitudinal direction of the sealing plate 2.

[0044] According to this embodiment, by providing the extending portion 14c on the insulating member 14, it is possible to prevent the protruding portions of the positive electrode tab groups 40a, 40b from contacting the sealing plate 2. This makes it possible to provide a secondary battery having a structure that maintains insulation between the positive electrode tab groups 40a, 40b and the sealing plate 2. In particular, even if the width of the positive electrode current collecting tabs 4a, 4b in the longitudinal direction of the sealing plate 2 is increased, it is possible to prevent the protruding portions of the positive electrode tab groups 40a, 40b from contacting the sealing plate 2, so that it is possible to provide a secondary battery having a high output and a structure that maintains insulation between the positive electrode tab groups 40a, 40b and the sealing plate 2.

[0045] In this embodiment, the insulating member 24 on the negative electrode side also has a similar configuration, so a secondary battery with a structure that maintains insulation between the negative electrode tab groups 50a, 50b and the sealing plate 2 can be provided.

[0046] 11 and 12 are an enlarged side view of the positive electrode side in Fig. 9, and a perspective view seen from below the sealing plate 2. Note that electrode assemblies 3a, 3b, positive electrode tab groups 40a, 40b, and negative electrode tab groups 50a, 50b are omitted in Figs.

[0047] 11 and 12, the positive electrode collector 12 is welded to the positive electrode connection member 11 in a state in which the first connection region 12a to which the positive electrode tab groups 40a, 40b are connected is fitted into the recess 14d of the insulating member 14. The surface of the first connection region 12a facing the electrode bodies 3a, 3b and the surface of the extension portion 14c of the insulating member 14 facing the electrode bodies 3a, 3b are flush with each other. This makes it possible to prevent the positive electrode collector tabs 4a, 4b from being subjected to an excessive load even if they are disposed across the positive electrode collector 12 (first connection region 12a) and the insulating member 14 (extension portion 14c).

[0048] 11 and 12, a gap S is provided between the sealing plate 2 and the extending portion 14c, which makes it possible to reduce the weight and cost of the insulating member 14.

[0049] 2, in this embodiment, the first connection region 12a of the positive electrode current collector 12 is located closer to the sealing plate 2 than the second connection region 12b. This allows the end of the electrode body 3 on the sealing plate 2 side to be closer to the sealing plate 2. As a result, the capacity of the secondary battery can be increased.

[0050] Although the present disclosure has been described above with reference to the preferred embodiments, such description is not intended to be limiting, and various modifications are possible.

[0051] For example, in the above embodiment, the positive electrode external terminal 10 and the positive electrode connecting member 11 are configured as separate members, but they may be integrally formed from the same member. Similarly, the negative electrode external terminal 20 and the negative electrode connecting member 21 are configured as separate members, but they may be integrally formed from the same member.

[0052] In the above embodiment, the electrode bodies 3a and 3b are configured such that the positive electrode plate 4 and the negative electrode plate 5 are wound with a separator interposed therebetween, but a structure in which a plurality of positive and negative electrode plates are stacked with a separator interposed therebetween may also be used. This is because, even in an electrode body having a stacked structure, the plurality of current collecting tabs provided on each positive and negative electrode plate are stacked in a mutually shifted state, and some of them may protrude from the positive and negative current collectors.

[0053] In the above embodiment, an example has been described in which two electrode bodies 3a, 3b are housed in the exterior body 1, but one electrode body or three or more electrode bodies may be used.

[0054] The type of the secondary battery in this embodiment is not particularly limited, and it can be applied to, for example, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries. [Explanation of symbols]

[0055] 1 Exterior body 2 Sealing plate 2b Liquid injection hole 3, 3a, 3b electrode body 4 Positive plate 4a, 4b Positive electrode current collecting tab 5 Negative plate 5a, 5b Negative electrode current collecting tab 6 Electrode holder 10 Positive external terminal 10a Protrusion 11 Positive electrode connecting member 12 Positive electrode current collector 12a First connection area 12b Second connection area 12c Step 12d Cutout 13, 23 Upper insulating member 13a, 2a, 14a, 11a through hole 14, 24 Insulating material 14b opening 14c extension 14d Recess 20 Negative external terminal 21 Negative electrode connecting member 22 Negative electrode current collector 22a First connection area 30 Sealing member 31 Gas exhaust valve 40a, 40b Positive electrode tab group 50a, 50b Negative electrode tab group 60, 70 Welding points 100 Secondary battery

Claims

1. An electrode assembly including a positive electrode plate and a negative electrode plate; An exterior body having an opening and housing the electrode assembly; A sealing plate that seals the opening; an external terminal provided on the outside of the sealing plate; a connection member provided inside the sealing plate and connected to the external terminal; an insulating member provided between the sealing plate and the connecting member; a current collector disposed inside the sealing plate, connected to the connection member, and connected to a tab group including a plurality of current collecting tabs extending from the positive electrode plate and the negative electrode plate; A secondary battery comprising: At least some of the current collecting tabs in the tab group have protruding portions that protrude from the current collector in the longitudinal direction of the sealing plate, The insulating member has an extension portion that extends along a longitudinal direction of the sealing plate and at least between the protruding portion and the sealing plate.

2. The secondary battery according to claim 1 , wherein a surface of the collector facing the electrode body at a portion to which the tab group is connected and a surface of the insulating member facing the electrode body at the extending portion are flush with each other.

3. The secondary battery according to claim 1 , wherein a gap is provided between the sealing plate and the extending portion.

4. the current collector has a first connection region connected to the tab group and a second connection region connected to the connection member, and has a step portion between the first connection region and the second connection region; The secondary battery according to claim 1 , wherein the first connection region is located closer to the sealing plate than the second connection region.

5. The secondary battery according to claim 4 , wherein a joint between the current collector and the tab group is located closer to the end of the current collector than the step portion is in the first connection region.

6. The secondary battery according to claim 1 , wherein the external terminal and the connection member are integrally formed from the same material.

7. The secondary battery according to claim 1 , wherein the electrode assembly has a structure in which the positive electrode plate and the negative electrode plate are wound with a separator interposed therebetween.

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