Bridge structure and secondary battery including same

Abstract

The present invention relates to a bridge structure, and specifically, the present invention provides a bridge structure for joining a first electrode assembly and a second electrode assembly that are stacked on each other, the bridge structure including: a first welded portion to which an electrode tab of the first electrode assembly is joined; a second welded portion to which an electrode tab of the second electrode assembly is joined and which is disposed in a diagonal direction oblique to the stacking direction of the first electrode assembly and the second electrode assembly relative to the first welded portion; and a connecting portion connecting the first welded portion and the second welded portion and extending in the diagonal direction.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application Nos. 10-2022-0105698, 10-2022-0105699, 10-2022-0105700, and 10-2023-0110485, filed on August 23, 2022, and all contents disclosed in the documents of these Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a bridge structure and a secondary battery including the same, and more particularly to a bridge structure capable of merging a plurality of electrode assemblies and a secondary battery including the same. [Background technology]

[0003] A secondary battery generally refers to a rechargeable battery that can be used not only in small home appliances such as mobile phones, laptops, and video cameras, but also as a power source for vehicles such as automobiles. One type of secondary battery that can be considered as a power source for automobiles is the lithium secondary battery. Lithium secondary batteries generally have high performance and high stability, and are manufactured using materials selected according to the desired characteristics, such as battery life, charge / discharge capacity, charge / discharge rate, temperature characteristics, and stability.

[0004] In particular, with the continuous improvement of electric vehicle technology, secondary batteries, one of the three core components of electric vehicles, play an important role in the performance of electric vehicles. Currently, as user demand for electric vehicles continues to increase, the demand for energy density of secondary batteries is also increasing. Regarding secondary batteries installed in electric vehicles, active research is being conducted to increase the energy density of secondary batteries in order to increase the driving range of electric vehicles.

[0005] In order to manufacture a secondary battery with a high energy density, it is advantageous to increase the thickness of the electrode assembly that is housed inside the secondary battery and generates electrical energy. However, as the thickness of the electrode assembly increases, the length of the electrode tabs protruding outward must be increased in order to connect them to electrode leads. If the electrode tabs are made of thin foil and are therefore easily damaged, such as torn by impact, the lifespan of the secondary battery may be shortened. Furthermore, if swelling occurs during use of the secondary battery, the tension applied to the electrode tabs increases, which may damage the electrode tabs. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a bridge assembly and a secondary battery that can combine multiple electrode assemblies to prevent the length of the electrode tabs from increasing, and that can reduce the impact on the electrode tabs even if swelling occurs in the electrode assemblies. [Means for solving the problem]

[0007] According to one embodiment of the present invention, there is provided a bridge structure for joining a first electrode assembly and a second electrode assembly stacked on each other, the bridge structure including: a first welded portion to which an electrode tab of the first electrode assembly is joined; a second welded portion to which an electrode tab of the second electrode assembly is joined and which is disposed in a diagonal direction oblique to the stacking direction of the first electrode assembly and the second electrode assembly relative to the first welded portion; and a connecting portion connecting the first welded portion and the second welded portion and extending in the diagonal direction.

[0008] The connector may further include deformation guides positioned at both ends of the connector and configured to induce a steeper inclination of the oblique direction of the connector when a force is applied thereto.

[0009] In addition, the deformation guiding portion may include a first deformation guiding portion configured to vary the angle between the first welding portion and the connecting portion, and a second deformation guiding portion configured to vary the angle between the second welding portion and the connecting portion.

[0010] The connecting portion may be bent in one direction relative to the first welded portion, and the second welded portion may be bent in another direction relative to the connecting portion. In addition, the bridge structure may include a metal material in which the deformation guide is elastically deformable.

[0011] Also, the first welded portion, the connecting portion, and the second welded portion may be formed from a single member that is continuously formed along the length direction. In addition, the connecting portion may electrically connect the first welded portion and the second welded portion.

[0012] Also, the first welded portion and the second welded portion may be formed parallel to each other. The semiconductor device may further include an electrode lead joined to either the first welded portion or the second welded portion.

[0013] According to another embodiment of the present invention, there is provided a secondary battery including: a first electrode assembly having a first electrode tab formed thereon; a second electrode assembly having a second electrode tab formed thereon; the bridge structure; and a case accommodating the first electrode assembly, the second electrode assembly, and the bridge structure, wherein the bridge structure is for joining the stacked first electrode assembly and the second electrode assembly, and includes: a first welded portion to which the first electrode tab of the first electrode assembly is joined; a second welded portion to which the second electrode tab of the second electrode assembly is joined and which is disposed in a diagonal direction oblique to the stacking direction of the first electrode assembly and the second electrode assembly, and a connecting portion connecting the first welded portion and the second welded portion and extending in the diagonal direction. [Effects of the Invention]

[0014] The present invention can manufacture a thicker secondary battery by combining multiple electrode assemblies, thereby improving the energy density of the secondary battery. Furthermore, by disposing a bridge structure between the electrode lead and the electrode tab, the length of the electrode tab can be shortened, thereby preventing damage to the electrode tab that may occur due to the length of the electrode tab.

[0015] In addition, when swelling occurs in the secondary battery, the shape of the bridge structure elastically deforms, cushioning the impact applied to the electrode tabs, thereby reducing damage to the electrode tabs. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing a secondary battery according to a first embodiment of the present invention, in which a first electrode assembly and a second electrode assembly are joined by a bridge structure; [Figure 2] 2 is a view showing a state in which the first electrode assembly and the second electrode assembly are joined by a bridge structure, as viewed from the direction A in FIG. 1; [Figure 3] 1 is a perspective view showing a bridge structure according to a first embodiment of the present invention. [Figure 4a] 1 is a cross-sectional view showing a state in which a bridge structure is deformed by application of force according to a first embodiment of the present invention. FIG. [Figure 4b] 1 is a cross-sectional view showing a state in which a bridge structure is deformed by application of force according to a first embodiment of the present invention. FIG. [Figure 4c] 1 is a cross-sectional view showing a state in which a bridge structure is deformed by application of force according to a first embodiment of the present invention. FIG. [Figure 5a] FIG. 4 is a cross-sectional view showing a second embodiment of the bridge structure of the present invention. [Figure 5b] FIG. 10 is a cross-sectional view showing a third embodiment of the bridge structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in more detail below with reference to the drawings. However, the following drawings are provided to facilitate understanding of the present invention, and are merely one embodiment of the present invention, and the scope of the present invention is not limited to the scope described in the drawings. Furthermore, in the following drawings, the same reference numerals refer to the same components, and some components may be exaggerated, reduced, or omitted to facilitate understanding of the invention.

[0018] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0019] First embodiment Referring to FIGS. 1 to 3, as a first embodiment of the present invention, a bridge structure 10 of the present invention can include a first welded portion 100, a second welded portion 200, and a connecting portion 300.

[0020] The bridge structure 10 is arranged in the direction in which the electrode tabs T1, T2 of the stacked electrode assemblies J1, J2 are located so that the stacked first electrode assembly J1 and second electrode assembly J2 can be merged, and is joined to the electrode tabs T1, T2 of each of the multiple electrode assemblies J1, J2, thereby electrically connecting the multiple electrode assemblies J1, J2.

[0021] Furthermore, since the bridge structure 10 is not joined to the electrode tabs of a single thick electrode assembly, but is joined to the first electrode tab T1 of the first electrode assembly J1 and the second electrode tab T2 of the second electrode assembly J2, respectively, the electrode tabs T1, T2 of the first electrode assembly J1 and the second electrode assembly J2 can be formed to be shorter in length and joined.

[0022] The electrode assemblies J1 and J2 may have a structure in which a positive electrode current collector / positive electrode active material layer / separator / negative electrode active material layer / negative electrode current collector are stacked in this order. The positive electrode current collector includes a region coated with a positive electrode active material layer and an uncoated positive electrode uncoated region, and the positive electrode uncoated region may protrude outward from the electrode assembly to form a positive electrode tab. The negative electrode current collector includes a region coated with a negative electrode active material layer and an uncoated negative electrode uncoated region, and the negative electrode uncoated region may protrude outward from the electrode assembly to form a negative electrode tab. The separator is disposed between the positive electrode current collector and the negative electrode current collector to prevent contact between current collectors of opposite polarities.

[0023] The first weld 100 is located on one side of the bridge structure 10, and the first electrode tab T1 of the first electrode assembly J1 may be joined to one surface of the first weld 100 by welding, soldering, or the like. The first welding portion 100 may be formed in the shape of a flat plate having a predetermined width so that the first electrode tab T1 of the first electrode assembly J1 can be joined thereto.

[0024] The first weld 100 may be formed of a conductive metal material to electrically connect the first electrode tab T1 of the first electrode assembly J1 and the second electrode tab T2 of the second electrode assembly J2. The first weld 100 may be disposed parallel to the first electrode tab T1 of the first electrode assembly J1.

[0025] The second welding portion 200 is joined to the second electrode tab T2 of the second electrode assembly J2, and can be arranged in a diagonal direction oblique to the stacking direction of the first electrode assembly J1 and the second electrode assembly J2 relative to the first welding portion 100.

[0026] Since the second welding portion 200 is disposed in a diagonal direction oblique to the stacking direction of the first electrode assembly J1 and the second electrode assembly J2 relative to the first welding portion 100, the movement path of the welding equipment for welding the electrode tabs T1 and T2 of the electrode assemblies J1 and J2 to the first welding portion 100 and the second welding portion 200, respectively, can be simplified, and the space above the first welding portion 100 and the second welding portion 200 is opened, thereby improving the convenience of welding when the welding equipment performs welding.

[0027] The second welding portion 200 may be formed in the shape of a flat plate having a predetermined width so that the second electrode tab T2 of the second electrode assembly J2 can be joined thereto. The second weld 200 may be formed of a conductive metal material to electrically connect the first electrode tab T1 of the first electrode assembly J1 and the second electrode tab T2 of the second electrode assembly J2. The second weld 200 may be disposed parallel to the second electrode tab T2 of the second electrode assembly J2.

[0028] The connecting portion 300 connects the first welded portion 100 and the second welded portion 200 and may be formed to extend in a diagonal direction along the diagonal arrangement of the first welded portion 100 and the second welded portion 200 . The connecting portion 300 may be made of a conductive metal material so as to electrically connect the first welded portion 100 and the second welded portion 200 together.

[0029] The connecting portion 300 may be formed to be bent in one direction relative to the first welded portion 100, and the second welded portion 200 may be formed to be bent in the other direction relative to the connecting portion 300. Since they are bent in opposite directions, the first welded portion 100 and the second welded portion 200 may be arranged parallel to each other, and even if the inclination of the diagonal direction of the connecting portion 300 is deformed, the first welded portion 100 and the second welded portion 200 may be maintained parallel to each other.

[0030] The first welded portion 100, the connecting portion 300, and the second welded portion 200 can be formed from a single member that is continuously formed along the length direction. The bridge structure 10 is manufactured by bending a single member that is continuously formed along the length direction without a separate joining process, which reduces manufacturing costs and simplifies the manufacturing process.

[0031] The bridge structure 10 according to the present invention may further include a deformation guide 400 . The deformation guides 400 are located at both ends of the connecting part 300, and can guide the inclination of the oblique direction of the connecting part 300 to become steeper or gentler when a force is applied.

[0032] The bridge structure 10 may include a deformation guide 400 made of a metal material that is elastically deformable. Referring to FIG. 3, the deformation guide 400 may include a first deformation guide 410 and a second deformation guide 420 .

[0033] Referring to Figures 4a to 4c, the first deformation guide portion 410 is located at one end of the connecting portion 300 and can be configured to vary the angle (a) between the first welded portion 100 and the connecting portion 300.

[0034] The first deformation inducing portion 410 may be formed in a region where the connecting portion 300 is bent in one direction relative to the first welded portion 100. Since the first deformation inducing portion 410 is formed in a region including a bent structure, which is a region where stress is concentrated, when force is applied to the first welded portion 100 or the connecting portion 300, the first deformation inducing portion 410 is deformed, and the deformation of the first deformation inducing portion 410 can change the angle (a) between the connecting portion 300 and the first welded portion 100.

[0035] When swelling occurs in the secondary battery and the electrode assembly expands and deforms, applying force to the bridge structure 10, the angle (a) between the connecting portion 300 and the first welded portion 100 decreases (see FIG. 4a), and when the expanded electrode assembly contracts and applies force to the bridge structure 10, the angle (a) between the connecting portion 300 and the first welded portion 100 increases (FIG. 4c). In other words, the bridge structure 10 can buffer the impact received by the electrode tabs T1, T2 by changing the separation distance between the electrode tabs T1, T2 in response to the expansion and contraction of the electrode assembly.

[0036] Referring to FIGS. 4a to 4c, the second deformation guide 420 may be provided at the other end of the connecting portion 300 so that the angle (b) between the second welded portion 200 and the connecting portion 300 can be varied.

[0037] The second deformation inducing part 420 may be formed in a region where the connecting part 300 is bent in the opposite direction relative to the second welded part 200. Since the second deformation inducing part 420 is formed in a region including a bent structure, which is a region where stress is concentrated, when force is applied to the second welded part 100 or the connecting part 300, the second deformation inducing part 420 is deformed, and the deformation of the second deformation inducing part 420 can change the angle (b) between the connecting part 300 and the second welded part 200.

[0038] When swelling occurs in the secondary battery and the electrode assembly expands and deforms, applying force to the bridge structure 10, the angle (b) between the connecting portion 300 and the second welded portion 200 decreases (see FIG. 4a), and when the expanded electrode assembly contracts and applies force to the bridge structure 10, the angle (b) between the connecting portion 300 and the second welded portion 200 increases (FIG. 4c). In other words, the bridge structure 10 can buffer the impact received by the electrode tabs T1, T2 by changing the separation distance between the electrode tabs T1, T2 in response to the expansion and contraction of the electrode assembly.

[0039] When a secondary battery is used, repeated charging and discharging gradually causes the secondary battery to deteriorate, which can lead to a swelling phenomenon in which the secondary battery expands and contracts. When swelling occurs, the electrode assemblies J1 and J2 housed inside the secondary battery may expand and deform. This deformation of the electrode assemblies J1 and J2 may apply excessive force to the electrode tabs T1 and T2 connected to the electrode lead L, which may damage the electrode tabs T1 and T2 and cause a short circuit. When swelling occurs in the secondary battery, the bridge structure 10 according to the present invention deforms to accommodate the deformation of the electrode assemblies J1 and J2, thereby absorbing the impact on the electrode tabs T1 and T2 connected to the bridge structure 10.

[0040] Furthermore, since the deformation induction portion 400 of the bridge structure 10 contains an elastically deformable metal material, when the electrode assemblies J1 and J2 that have expanded due to the swelling phenomenon contract again to a certain extent, the elastic restoring force of the deformation induction portion allows the bridge structure 10 to restore its deformed shape to the extent that the electrode assemblies J1 and J2 have contracted (see Figures 4a to 4c).

[0041] In addition, when swelling occurs in the secondary battery and the first electrode assembly J1 or the second electrode assembly J2 expands, the angle of the connecting part 300 arranged in the diagonal direction can change. As the angle of the connecting part 300 changes, the first welded part 100 and the second welded part 200 move in the horizontal and vertical directions, minimizing the impact on the electrode tabs T1 and T2.

[0042] The bridge structure 10 may further include an electrode lead L joined to either the first welded portion 100 or the second welded portion 200. The electrode lead L may be joined by being welded to either the first welded portion 100 or the second welded portion 200.

[0043] The electrode lead L can be directly joined to the electrode tabs T1 and T2, but by joining the electrode lead L to either the first weld 100 or the second weld 200 of the bridge structure 10 to form an integrated structure, the bridge structure 10 can be quickly joined to the electrode tabs T1 and T2 of the electrode assemblies J1 and J2.

[0044] Second embodiment Referring to FIG. 5 a , as a second embodiment of the present invention, the bridge structure 10 of the present invention may include a first welded portion 110 , a second welded portion 210 , and a connecting portion 310 .

[0045] The first welding portion 110 is formed in the shape of a flat plate having a predetermined width so that the first electrode tab T1 of the first electrode assembly J1 can be joined thereto, and may be made of a conductive metal material.

[0046] The second welding portion 210 is joined to the second electrode tab T2 of the second electrode assembly J2, and can be arranged in a diagonal direction oblique to the stacking direction of the first electrode assembly J1 and the second electrode assembly J2 relative to the first welding portion 110.

[0047] The second welding portion 210 may be formed in the shape of a flat plate having a predetermined width so that the second electrode tab T2 of the second electrode assembly J2 can be joined thereto. The second weld 210 can be formed from a conductive metallic material.

[0048] The connecting portion 310 may connect an end of the first welded portion 110 and an end of the second welded portion 210. The connecting portion 310 may be formed to extend in a direction perpendicular to the first welded portion 110. The connection portion 310 may be made of a conductive metal material so as to electrically connect the first weld portion 110 and the second weld portion 210 together.

[0049] The connecting portion 310 may be formed by being bent in one direction relative to the first welded portion 110, and the second welded portion 210 may be formed by being bent in the other direction relative to the connecting portion 310. Since they are bent in opposite directions, the first welded portion 110 and the second welded portion 210 may be formed parallel to each other.

[0050] When swelling occurs in the electrode assemblies J1 and J2, the connecting portion 310, which is formed by extending in the vertical direction, may deform from a vertical angle to an oblique angle, causing the first welded portion 110 and the second welded portion 210 to move away from each other, thereby preventing damage to the joined electrode tabs T1 and T2.

[0051] Third embodiment Referring to FIG. 5 b , as a third embodiment of the present invention, the bridge structure 10 of the present invention may include a first welded portion 120 , a second welded portion 220 , and a connecting portion 320 .

[0052] The first welding portion 120 is formed in the shape of a flat plate of a predetermined width so that the first electrode tab T1 of the first electrode assembly J1 can be joined, and the first welding portion 120 can be made of a conductive metal material.

[0053] The second welding portion 220 is joined to the second electrode tab T2 of the second electrode assembly J2, and can be arranged in a diagonal direction oblique to the stacking direction of the first electrode assembly J1 and the second electrode assembly J2 or oblique to the stacking direction relative to the first welding portion 120. The second welding portion 220 may be formed in the shape of a flat plate having a predetermined width so that the second electrode tab T2 of the second electrode assembly J2 can be joined thereto.

[0054] The second weld 220 may be formed of a conductive metal material to electrically connect the first electrode tab T1 of the first electrode assembly J1 and the second electrode tab T2 of the second electrode assembly J2. The second weld 220 may be disposed parallel to the second electrode tab T2 of the second electrode assembly J2.

[0055] The connecting portion 320 may connect between an end of the first weld portion 120 and an end of the second weld portion 220. The connecting portion 320 may form an acute angle with the first weld portion 120 and the second weld portion 220. Thus, the first weld portion 120, the second weld portion 220, and the connecting portion 320 may be formed in a "Z" shape.

[0056] The connection portion 320 may be made of a conductive metal material so as to electrically connect the first weld portion 120 and the second weld portion 220 together. The connecting portion 320 is formed to be bent in one direction relative to the first welding portion 120, and the second welding portion 220 is formed to be bent in the other direction relative to the connecting portion 320, and since they are bent in opposite directions, the first welding portion 120 and the second welding portion 220 can be formed parallel to each other.

[0057] When swelling occurs in the electrode assemblies J1 and J2, the connecting portion 320, which forms a predetermined angle with respect to the first welded portion 120 and the second welded portion 220, changes direction to a steeper inclination, thereby increasing the vertical distance between the first welded portion 120 and the second welded portion 220. This causes the first welded portion 120 and the second welded portion 220 to move away from each other, preventing damage to the electrode tabs T1 and T2 joined thereto.

[0058] Fourth embodiment Referring to FIG. 1, as a fourth embodiment of the present invention, a secondary battery of the present invention may include a first electrode assembly J1, a second electrode assembly J2, a bridge structure 10, and a case (not shown).

[0059] A case (not shown) can accommodate the first electrode assembly J1, the second electrode assembly J2, and the bridge structure 10, and the first electrode assembly J1 and the second electrode assembly J2 can be joined to the bridge structure 10 and electrically connected. The bridge structure 10 is for joining a first electrode assembly J1 and a second electrode assembly J2 that are stacked on top of each other, and may include first welds 100, 110, 120 to which a first electrode tab T1 of the first electrode assembly J1 is joined, second welds 200, 210, 220 to which a second electrode tab T2 of the second electrode assembly J2 is joined and which are disposed in a diagonal direction oblique to the stacking direction of the first electrode assembly J1 and the second electrode assembly J2 relative to the first welds 100, 110, 120, and connecting portions 300, 310, 320 that connect the first welds 100, 110, 120 and the second welds 200, 210, 220 and extend in the diagonal direction. A detailed description of the bridge structure 10 may be substituted for the descriptions of the first to third embodiments described above.

[0060] Although the present technology has been described above using the embodiments, the present technology is not limited thereto. The above-described embodiments can be modified or changed without departing from the spirit and scope of the present technology, and a person skilled in the art would understand that such modifications and changes also belong to the present technology. [Explanation of symbols]

[0061] 10: Bridge structure 100, 110, 120: First weld 200, 210, 220: Second weld 300, 310, 320: Connection part 400: Deformation induction section 410: First deformation guidance section 420: Second deformation guidance section J1: 1st electrode assembly J2: Second electrode assembly T1: First electrode tab T2: Second electrode tab L: Electrode lead

Claims

1. A bridge structure for joining the first electrode assembly and the second electrode assembly stacked on each other, a first welding portion to which an electrode tab of the first electrode assembly is joined; a second welded portion to which an electrode tab of the second electrode assembly is joined, the second welded portion being disposed in a diagonal direction with respect to the first welded portion with respect to a stacking direction of the first electrode assembly and the second electrode assembly; a connecting portion that connects the first welded portion and the second welded portion and extends in the diagonal direction; a bridge structure including:

2. The bridge structure according to claim 1 , further comprising deformation guides positioned at both ends of the connecting portion and configured to guide the connecting portion to deform so that the inclination of the diagonal direction becomes steeper when a force is applied.

3. The deformation guide portion is a first deformation guide provided so that an angle between the first welded portion and the connecting portion can be varied; The bridge structure according to claim 2 , further comprising: a second deformation guide portion provided so that an angle between the second weld portion and the connecting portion can be varied.

4. The connecting portion is bent in one direction relative to the first welded portion, The bridge structure according to claim 3 , wherein the second welded portion is bent in another direction relative to the connecting portion.

5. The bridge structure according to claim 2 , wherein the deformation guide includes an elastically deformable metal material.

6. The bridge structure according to claim 1 , wherein the first weld portion, the connecting portion, and the second weld portion are formed from a single member formed continuously along a length direction.

7. The bridge structure according to claim 1 , wherein the connecting portion electrically connects the first weld portion and the second weld portion.

8. The bridge structure of claim 1 , wherein the first weld and the second weld are formed parallel to each other.

9. The bridge structure of claim 1 , further comprising an electrode lead joined to one of the first weld or the second weld.

10. a first electrode assembly having a first electrode tab formed thereon; a second electrode assembly having a second electrode tab formed thereon; a bridge structure; Including, The bridge structure includes: a first welded portion to which a first electrode tab of the first electrode assembly is joined; a second welded portion to which a second electrode tab of the second electrode assembly is joined, the second welded portion being disposed in a diagonal direction with respect to the first welded portion with respect to a stacking direction of the first electrode assembly and the second electrode assembly; a connecting portion that connects the first welded portion and the second welded portion and extends in the diagonal direction; A secondary battery comprising:

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