Terminal structure for secondary battery and secondary battery having same

Abstract

The disclosed invention relates to a terminal structure for a secondary battery, and in one embodiment, the terminal structure comprises: a first conductive member having a protrusion with a circular cross-section; and a second conductive member having a through-hole into which the protruding portion of the first member is inserted, in which the protruding portion of the first member is inserted into the through-hole of the second member such that welding portions are formed along circular edges contacting each other.

Description

Technical Field

[0001] The present invention relates to a structure for electrically connecting an electrode assembly and an external terminal in a secondary battery.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0032901, filed on March 14, 2023, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] Unlike primary batteries, secondary batteries are rechargeable and can be miniaturized compared to their large capacity, which is why a lot of research has been done on secondary batteries in recent years. With the development of battery technology, the demand for mobile devices, and the rise of electric vehicles and energy storage systems (ESS) accompanied by growing awareness of the need to protect the environment, the demand for secondary batteries as power sources is increasing.

[0004] Secondary batteries can be classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries based on the shape of their battery cases. An electrode assembly mounted inside a secondary battery battery case is a rechargeable power generating device consisting of a laminated structure of electrodes and separators.

[0005] Electrode assemblies can be roughly divided into a winding type, a stacking type, and a stacking and folding type. In the winding type, a separator is inserted between a sheet-type positive electrode coated with an active material and a negative electrode and wound, in the stacking type, a plurality of positive electrodes and a plurality of negative electrodes are stacked in sequence with a separator inserted, and in the stacking and folding type, a stacked unit battery is wound with a long separator film.

[0006] The electrode assembly housed in the battery case is electrically connected internally to the negative terminal and the positive terminal exposed to the outside of the battery case. For example, the lead wire provided in the electrode assembly and the negative terminal and the positive terminal of the battery case may be interconnected by a bus bar.

[0007] Here, laser welding is used to connect the bus bars to the negative terminal and the positive terminal, which has caused many problems, including terminal corrosion due to excessive welding, heat damage and corrosion due to spatter generated by excessive welding, melting of lead tapes, melting of separators in the electrode assembly, and low voltage due to poor welding. Summary of the invention

[0008] Technical issues

[0009] The present invention is directed to providing a terminal structure for a secondary battery, which can solve a problem caused by excessive welding when welding a bus bar and an electrode terminal of a battery case.

[0010] However, the technical problems that the present invention is intended to solve are not limited to the above-mentioned problems, and other undisclosed challenges may be clearly understood by those skilled in the art from the description of the present invention provided below.

[0011] Technical Solution

[0012] The present invention relates to a terminal structure for a secondary battery. In one embodiment, the terminal structure includes: a conductive first component, which is provided with a protruding portion having a circular cross-section; and a conductive second component, which is provided with a through hole, and the protruding portion of the first component is inserted into the through hole of the second component, wherein the protruding portion of the first component is inserted into the through hole of the second component, and a welding portion is formed along a circular boundary that contacts each other.

[0013] The protruding portion may be inserted only a portion of the total depth of the through hole.

[0014] In an exemplary embodiment of the present invention, the through hole may be provided with an annular step portion which limits or indicates an insertion depth of the protruding portion.

[0015] For example, the step portion may be a reduced-type step portion that limits the insertion depth of the protruding portion.

[0016] Alternatively, the step portion may be an expanded step portion indicating the insertion depth of the protruding portion.

[0017] Also, the first member may be a terminal part provided on a cap plate covering a surface of the battery, and the second member may be a bus bar electrically connected to a lead of the electrode assembly.

[0018] At the same time, as a secondary battery including the above-mentioned terminal structure for a secondary battery, the present invention provides a secondary battery, which includes: an electrode assembly, the electrode assembly having a plurality of battery cells gathered in the electrode assembly and protruding with leads electrically connecting the plurality of battery cells; a battery box having at least one surface open to receive the electrode assembly; a cover plate, the cover plate closing the open surface of the battery box and having a positive terminal and / or a negative terminal; a first component, the first component being a conductive terminal part disposed on the cover plate and electrically connected to the positive terminal and / or the negative terminal; and a second component, the second component being a bus bar electrically connected to the leads of the electrode assembly.

[0019] In an exemplary embodiment of the present invention, an upper surface of the battery case constitutes an open surface, and the cover plate may be a top cover having a positive terminal and a negative terminal.

[0020] In one example, the step portion is a reduced-type step portion that limits an insertion depth of the protruding portion, and the welding portion may be formed along an edge of the protruding portion exposed with respect to the reduced-type step portion.

[0021] In another example, the step portion may be an expanded step portion indicating an insertion depth of the protruding portion, and the welding portion may be formed along a boundary of the expanded step portion and the protruding portion.

[0022] Beneficial Effects

[0023] The terminal structure for a secondary battery of the present invention having the above configuration prevents the problem of excessive welding caused by stacking the first member and the second member and spot welding at the center of the first member and the second member in the past by forming a welding portion along a circular boundary, where the protruding portion of the first member is inserted into the through hole of the second member and contacts each other. In other words, by performing welding along the contact surface of the protruding portion and the through hole, the welding quality is improved, and excessive welding is avoided by distributing welding heat along the circular boundary.

[0024] In addition, in an embodiment where the protrusion is inserted only a portion of the entire depth of the through hole, welding is performed from the inside of the through hole, thereby reducing the possibility of spatter generated during welding scattering toward the electrode assembly, thereby effectively protecting the electrode assembly that is easily damaged by overheating and thereby improving the quality of the secondary battery.

[0025] However, the technical effects of the present invention are not limited to those described above, and other effects not mentioned will be apparent to those of ordinary skill in the art from the description of the present invention set forth below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the following detailed description of the present invention, are used to further explain the technical concept of the present invention, and the present invention should not be construed as being limited to the contents shown in these drawings.

[0027] Figure 1 is a diagram illustrating an example of a prismatic battery to which the terminal structure for a secondary battery according to the present invention can be applied.

[0028] Figure 2 1 is a diagram illustrating a structure in which a first member and a second member are welded to each other.

[0029] Figure 3 1 is a diagram illustrating another structure in which a first member and a second member are welded to each other.

[0030] Figure 4 This is a diagram illustrating an embodiment in which the second member is provided with a reduced step portion.

[0031] Figure 5 It is a diagram illustrating an embodiment in which the second member is provided with an expanded step portion.

[0032] Figure 6 The terminal structure for a secondary battery of the present invention is applied to Figure 1 Figure 2 is an example of a prismatic battery.

[0033] Figure 7 The diagram shows the settings in Figure 6 FIG. 1 is a diagram of one embodiment of a cover plate in a prismatic battery.

[0034] Figure 8 It is illustrated in Figure 4 FIG. 1 is a diagram showing a structure in which a welding portion is formed on a reduced step portion.

[0035] Fig. 9 It is illustrated in Figure 5 FIG. 1 is a diagram showing a structure in which a welding portion is formed on an extended step portion. DETAILED DESCRIPTION

[0036] The present invention may have various modifications and various examples, and specific examples are shown in the drawings and described in detail in the specification.

[0037] However, it should be understood that the present invention is not limited to the specific embodiments, but includes all modifications, equivalents or substitutes within the spirit and technical scope of the present invention.

[0038] The terms "include", "comprising" and "having" used herein indicate the presence of features, numbers, steps, actions, parts or components, or a combination thereof, described in the specification, and it should be understood that the possibility of the presence or addition of one or more other features, numbers, steps, actions, parts, components, or a combination thereof is not precluded.

[0039] In addition, when a portion of a layer, film, region, or plate is disposed "on" another portion, this includes not only a case where the portion is directly disposed on the other portion, but also a case where a third portion is interposed therebetween. In contrast, when a portion of a layer, film, region, or plate is disposed "below" another portion, this includes not only a case where the portion is directly disposed below the other portion, but also a case where a third portion is interposed therebetween. In addition, in the present application, "on" may include not only a case where it is disposed on an upper portion, but also a case where it is disposed on a lower portion.

[0040] The present invention relates to a terminal structure for a secondary battery. In one example, the terminal structure includes: a conductive first component, the first component is provided with a protruding portion having a circular cross-section; and a conductive second component, the second component is provided with a through hole, and the protruding portion of the first component is inserted into the through hole of the second component, wherein the protruding portion of the first component is inserted into the through hole of the second component, and a welding portion is formed along a circular boundary that contacts each other.

[0041] Preferably, the protruding portion may be inserted only a portion of the entire depth of the through hole.

[0042] The terminal structure for a secondary battery of the present invention having the above configuration prevents the problem of excessive welding caused by stacking the first member and the second member and spot welding at the center of the first member and the second member in the past by forming a welding portion along a circular boundary, where the protruding portion of the first member is inserted into the through hole of the second member and contacts each other. In other words, by performing welding along the contact surface of the protruding portion and the through hole, the welding quality is improved, and excessive welding is avoided by distributing welding heat along the circular boundary.

[0043] In addition, in an embodiment where the protrusion is inserted only a portion of the entire depth of the through hole, welding is performed from the inside of the through hole, thereby reducing the possibility of spatter generated during welding scattering toward the electrode assembly, thereby effectively protecting the electrode assembly that is easily damaged by overheating and thereby improving the quality of the secondary battery.

[0044] Invention

[0045] Hereinafter, a specific embodiment of the terminal structure for a secondary battery according to the present invention will be described in detail with reference to the accompanying drawings. For reference, unless otherwise specified, the front to back, top and bottom, left and right directions of the designated relative positions used in the following description are for the purpose of understanding the present invention and refer to the directions shown in the accompanying drawings.

[0046] [First embodiment]

[0047] Figure 1 is a diagram illustrating an example of a prismatic battery to which a terminal structure for a secondary battery (hereinafter simply referred to as a “terminal structure”) according to the present invention can be applied. Figure 1 The prismatic battery shown in FIG. 1 is an exemplary embodiment of a unidirectional battery, i.e., one in which the positive terminal 132 and the negative terminal 134 are disposed on the same side. Figure 1 The terminal structure for a secondary battery according to the present invention relates to a welding structure of a bus bar 150 and a positive terminal 132 and / or a negative terminal 134, and before describing the overall configuration of an exemplified prismatic battery, the terminal structure of the present invention that can be applied to various forms of secondary batteries 100 will be described in detail.

[0048] Figure 2is a diagram illustrating a structure in which a conductive first member 10 and a second member 20 are welded to each other. For example, the first member 10 may be a terminal component 140 provided on a cap plate 130 covering one side of a battery, and the second member 20 may be a bus bar 150 electrically connected to a lead 114 of an electrode assembly 110. Alternatively, the first member 10 may be a bus bar 150, and the second member 20 may be a terminal component 140. And, for electrical connection, both the first member 10 and the second member 20 are made of a conductive material.

[0049] The first member 10 is provided with a protruding portion 12 having a circular cross section, and the second member 20 is provided with a through hole 22 into which the protruding portion 12 is inserted. Of course, the protruding portion 12 and the through hole 22 may have other shapes than a circular cross section, such as an elliptical or polygonal cross section, but for ease of processing and welding, it is preferred that the protruding portion 12 and the through hole 22 are made circular.

[0050] Reference Figure 2 , the first member 10 has a protruding portion 12 inserted into the through hole 22 of the second member 20, thereby generating a circular contact boundary. The welded portion 30 formed by laser welding is along the circular boundary, whereby the first member 10 and the second member 20 are joined along the circumferential surface in contact with each other. The welding action occurs over the entire circumferential surface, thereby ensuring uniform welding quality and avoiding the problem of over-welding because excessive welding heat is not generated.

[0051] Figure 3 1 is a diagram illustrating another structure in which the conductive first member 10 and the second member 20 are welded to each other. In the coupling of the first member 10 and the second member 20, the protruding portion 12 is inserted only a portion of the entire depth of the through hole 22, and the welding portion 30 is annularly formed inside the through hole 22 along the contact boundary of the first member 10 and the second member 20. By performing laser welding inside the through hole 22, heat spatter from the welding process is less likely to scatter to the surrounding area, and the problem of melting the lead tape or separator of the thermosensitive electrode assembly 110 is significantly reduced.

[0052] Furthermore, according to an embodiment of the present invention, the through hole 22 may be provided with a step 24 that limits the insertion depth of the protruding portion 12. Depending on the shape of the step 24, the step 24 may physically limit the insertion depth of the protruding portion 12, or may be used to indicate how deep the protruding portion 12 can be inserted. By the configuration of the step 24, it is ensured that the protruding portion 12 is inserted only a portion of the entire depth of the through hole 22.

[0053] Figure 4The diagram shows the configuration of the reduced step portion 24-1 that physically limits the insertion depth of the protruding portion 12. The reduced step portion 24-1 is formed in a form in which the middle diameter in the insertion direction of the protruding portion 12 into the through hole 22 is sharply reduced, thereby limiting the insertion depth of the protruding portion 12 blocked by the reduced step portion 24-1.

[0054] Figure 5 The configuration of the expanded step portion 24-2 indicating the insertion depth of the protruding portion 12 is illustrated. Figure 4 In contrast to the reduced step portion 24-1, Figure 5 The expanded step portion 24-2 is formed so that the approximately middle diameter of the expanded step portion 24-2 in the direction in which the protruding portion 12 is inserted into the through hole 22 increases sharply. Although the expanded step portion 24-2 does not physically limit the insertion depth of the protruding portion 12, the expanded step portion 24-2 indirectly limits the insertion depth by visually indicating the point at which the surface of the expanded step portion 24-2 coincides with the surface of the protruding portion 12. Although the expanded step portion 24-2 is not as effective as the reduced step portion 24-1 in limiting the insertion depth, the expanded step portion 24-2 is advantageous in terms of welding quality and productivity because the expanded step portion 24-2 allows sufficient welding space.

[0055] [Second Embodiment]

[0056] In the second embodiment of the present invention, an exemplary embodiment in which the terminal structure described in the first embodiment is applied to the secondary battery 100 is described. Figure 6 This diagram shows the application of prismatic batteries—— Figure 1 A secondary battery 100 is a diagram showing an example of a terminal structure for a secondary battery of the present invention. Figure 6 In the embodiment, the first member 10 is a conductive terminal part 140 provided on a cap plate 130 covering one side of the battery, and the second member 20 corresponds to a bus bar 150 electrically connected to the lead 114 of the electrode assembly 110 .

[0057] Figure 6The prismatic battery of the embodiment includes: an electrode assembly 110 having a plurality of battery cells 112 and leads 114 protruding from the battery cells 112 and electrically connecting the battery cells 112; a battery case 120 having at least one surface opened to receive the electrode assembly 110; and a cover plate 130 closing the open surface of the battery case 120. The cover plate 130 may be provided with a positive terminal 132 and / or a negative terminal 134. The prismatic battery shown is a unidirectional battery in which the upper surface of the battery case 120 is an open surface, and the cover plate 130 closing the open surface includes a top cover 130' having a positive terminal 132 and a negative terminal 134. Although not shown, in the case of a bidirectional battery in which the positive terminal 132 and the negative terminal 134 are respectively provided on each side of the prismatic battery, each cover plate will be provided with a positive terminal 132 or a negative terminal 134 as a side cover.

[0058] Here, the first member 10 as the conductive terminal part 140 is disposed on the cap plate 130 for being electrically connected to the positive terminal 132 and / or the negative terminal 134, and the second member 20 as the bus bar 150 electrically connects the first member 10 to the lead 114 of the electrode assembly 110. For example, Figure 7 As shown in , in the case where a prismatic battery is configured to have an electrode assembly 110 arranged and connected on both sides of a single cover plate 130 (also referred to as a butterfly structure due to its symmetrical shape), the leads 114 of the two electrode assemblies 110 are arranged to have the same polarity as each other, and the paired leads 114 are joined to a bus bar 150 serving as the second component 20 by ultrasonic welding or the like, and each bus bar 150 is joined to the first component 10 by laser welding or the like, as the terminal structure in the first embodiment.

[0059] For example, Figure 8 It is illustrated in Figure 4 FIG. 2 is a diagram showing a structure in which a welding portion 30 is formed on the reduced step portion 24-1. Figure 8 As shown in FIG. 1 , the welding portion 30 may be formed along the edge of the protruding portion 12 exposed relative to the reduced step portion 24-1. Alternatively, in the case of the expanded step portion 24-2 indicating the insertion depth of the protruding portion 12, the welding portion 30 may be formed along the joint of the expanded step portion 24-2 and the protruding portion 12, as shown in FIG. Fig. 9 As shown in . Figure 8 and Fig. 9 The terminal structure of the thermosensitive electrode assembly 110 is formed by forming a welding portion 30 in an annular shape along the contact boundary between the first member 10 and the second member 20 inside the through hole 22. By performing laser welding from inside the through hole 22, the scattering of heat spatter generated during the welding process to the surrounding area is reduced, thereby eliminating the problem of melting the lead tape or separator of the thermosensitive electrode assembly 110.

[0060] The present invention has been described in more detail above with reference to the accompanying drawings and embodiments. However, it should be understood that the configuration shown in the accompanying drawings or embodiments described herein is only one embodiment of the present invention and does not represent all technical concepts of the present invention, and when submitting this disclosure, there may be various equivalents and modifications that can replace them.

[0061] Reference numerals

[0062] 10: First component

[0063] 12: Protrusion

[0064] 20: Second component

[0065] 22: Through hole

[0066] 24: Steps

[0067] 24-1 Reduced step section

[0068] 24-2 Extended step section

[0069] 30: Welding part

[0070] 100: Secondary battery

[0071] 110: Electrode assembly

[0072] 112: Battery Cell

[0073] 114: Lead

[0074] 120: Battery box

[0075] 130: Cover

[0076] 130': Top Plate

[0077] 132: Positive terminal

[0078] 134: Negative terminal

[0079] 140: Terminal parts

[0080] 150: Busbar

Claims

1. A terminal structure for a secondary battery, comprising: a conductive first member provided with a protruding portion having a circular cross-section, and a conductive second member, the second member being provided with a through hole into which the protruding portion of the first member is inserted, wherein The protruding portion of the first member is inserted into the through hole of the second member, and a welding portion is formed along a circular boundary contacting each other.

2. The terminal structure for a secondary battery according to claim 1, wherein: The protrusion is inserted only a portion of the total depth of the through hole.

3. The terminal structure for a secondary battery according to claim 2, wherein: The through hole is provided with an annular step portion which limits or indicates the insertion depth of the protruding portion.

4. The terminal structure for a secondary battery according to claim 3, wherein: The step portion is a reduced-type step portion that limits an insertion depth of the protruding portion.

5. The terminal structure for a secondary battery according to claim 3, wherein: The step portion is an expanded step portion indicating an insertion depth of the protruding portion.

6. The terminal structure for a secondary battery according to claim 1, wherein: The first member is a terminal component provided on a cover plate covering the surface of the battery, and The second member is a bus bar electrically connected to a lead of the electrode assembly.

7. A secondary battery comprising the terminal structure for a secondary battery according to any one of claims 1 to 6, the secondary battery comprising: an electrode assembly having a plurality of battery cells gathered therein and having protruding leads electrically connecting the plurality of battery cells; a battery case having at least one surface opened to receive the electrode assembly; a cover plate, the cover plate closing the open surface of the battery case and having a positive terminal and / or a negative terminal; The first member is a conductive terminal component disposed on the cover plate and electrically connected to the positive terminal and / or the negative terminal; as well as The second member is a bus bar electrically connected to the lead of the electrode assembly.

8. The secondary battery according to claim 7, wherein The upper surface of the battery case constitutes the open surface, and The cover plate is a top cover having a positive terminal and a negative terminal.

9. The secondary battery according to claim 7, wherein The step portion is a reduced step portion that limits the insertion depth of the protruding portion, The welding portion is formed along an edge of the protruding portion that is exposed relative to the reduced step portion.

10. The secondary battery according to claim 7, wherein The step portion is an extended step portion indicating an insertion depth of the protruding portion, and The welding portion is formed along a boundary of the expanded step portion and the protruding portion.

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