Battery cell and method for manufacturing a battery cell

Abstract

The present invention provides a battery cell and a method for manufacturing a battery cell having a structure that can reduce the thickness of the electrode tab bundle (electrode tab assembly) extending from the electrode assembly to the lead tab, thereby improving connectivity with the lead tab and providing a battery cell and a method for manufacturing a battery cell having a structure that allows the electrode assembly to be easily inserted into the case. A battery cell is provided which includes an electrode tab assembly comprising a plurality of electrode tabs stacked on one side from a plurality of electrode plates; a case housing the plurality of electrode plates; and lead tabs electrically connected to the electrode tab assembly and at least a portion of which is exposed outside the case, wherein the electrode tab assembly includes a first connection portion formed by welding at least a portion of the plurality of electrode tabs to each other; and a second connection portion extending from the first connection portion and welded to the lead tabs, wherein the number of electrode tabs constituting the second connection portion is less than the number of electrode tabs constituting the first connection portion.

Description

Technical Field

[0001] The present invention relates to a battery cell and a method for manufacturing the same.

Background Art

[0002] Unlike primary batteries, secondary batteries can be charged and discharged, and thus can be applied to various fields such as digital cameras, mobile phones, notebook computers, hybrid vehicles, and electric vehicles. Examples of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-hydrogen batteries. Recently, lithium-ion batteries have been widely used.

[0003] In the case of conventional lithium-ion batteries, copper, aluminum foil, etc. are used as metal current collectors on the negative electrode or the positive electrode, and a negative electrode or a positive electrode is produced by laminating a negative electrode active material or a positive electrode active material on both sides thereof.

[0004] In contrast, in the case of next-generation batteries such as lithium-sulfur batteries (Li-S batteries) and lithium-metal batteries (Li-Metal batteries), the negative electrode can be composed of lithium metal itself. In this case, by directly extending the lithium metal constituting the negative electrode plate to form a negative electrode tab, the thickness of the electrode tab may become relatively thicker than that of the electrode tab of a conventional lithium-ion battery.

[0005] As described above, a thick electrode tab hinders the connectivity with a lead tab and makes it difficult to house the electrode assembly inside a cell case. In particular, an electrode tab made of lithium metal has problems in that, during the welding process with a lead tab, it is spread by pressure, breaking the sealing between the lead tab and the cell case or causing a short circuit with the cell case.

[0006] Therefore, there is a need for a structure of a battery cell that can reduce the thickness of an electrode tab or an electrode tab bundle formed by gathering electrode tabs.

Summary of the Invention

[0007] The present invention was devised to solve at least some of the problems of the prior art described above, and provides a battery cell and a method for manufacturing a battery cell having a structure that can reduce the thickness of the electrode tab bundle (electrode tab assembly) extending from the electrode assembly to the lead tab.

[0008] Furthermore, an object of the present invention is to provide a battery cell and a method for manufacturing a battery cell having a structure that reduces the thickness of the electrode tab bundle (electrode tab assembly), improves connectivity with lead tabs, and allows the electrode assembly to be easily inserted into the case. [Means for solving the problem]

[0009] To achieve the above objective, embodiments of the present invention provide a battery cell comprising: an electrode tab assembly in which a plurality of electrode tabs extending to one side from each of a plurality of electrode plates are stacked; a case housing the plurality of electrode plates; and lead tabs electrically connected to the electrode tab assembly and at least a portion of which is exposed outside the case, wherein the electrode tab assembly comprises a first connection portion formed by welding at least a portion of the plurality of electrode tabs to each other; and a second connection portion extending from the first connection portion and welded to the lead tab, wherein the number of electrode tabs constituting the second connection portion is less than the number of electrode tabs constituting the first connection portion.

[0010] In the embodiment, the plurality of electrode tabs may include at least one first type electrode tab that forms a second connection; and at least one second type electrode tab that is shorter than one or more first type electrode tabs and forms a first connection together with one or more first type electrode tabs.

[0011] In the embodiment, at least one second type electrode tab cannot overlap with the lead tab in the stacking direction of the multiple electrode tabs.

[0012] In one embodiment, at least one second type electrode tab includes N different types of electrode tabs arranged at different positions in the width direction of a plurality of electrode plates, where N can be a natural number of 2 or more.

[0013] In this embodiment, N electrode tabs of different types can be welded together to different portions of at least one electrode tab of a first type.

[0014] In this embodiment, at least two of the N electrode tabs of different types may be arranged so as not to overlap each other in the stacking direction of the plurality of electrode tabs.

[0015] In this embodiment, the width of each of the N different types of electrode tabs may be less than or equal to 1 / N of the width of at least one first type of electrode tab.

[0016] In this embodiment, the first connection portion may be positioned between the second connection portion and a plurality of electrode plates.

[0017] In the embodiment, the multiple electrode tabs may be made of lithium or a lithium-containing alloy.

[0018] In one embodiment, a method for manufacturing a battery cell is provided, which includes an alignment step of aligning a plurality of electrode tabs extending to one side from a plurality of electrode plates to form an electrode tab assembly; a first welding step of ultrasonically welding a first region of the electrode tab assembly; and a second welding step of ultrasonically welding lead tabs to a second region of the electrode tab assembly, wherein the number of electrode tabs stacked in the second region is less than the number of electrode tabs stacked in the first region.

[0019] In the battery cell manufacturing method according to this embodiment, the first welding step may be performed before the second welding step.

[0020] In the battery cell manufacturing method according to the embodiment, the electrode tab assembly includes at least one first type electrode tab that overlaps with the lead tabs in the stacking direction of the plurality of electrode tabs; and at least one second type electrode tab that is shorter in length than the at least one first type electrode tab and is bonded to the at least one first type electrode tab, wherein at least one first type electrode tab and at least one second type electrode tab are stacked together in a first region, and at least one first type electrode tab is stacked only in a second region.

[0021] In the battery cell manufacturing method according to the embodiment, at least one second type electrode tab includes at least one second-first type electrode tab and at least one second-second type electrode tab arranged at different positions in the width direction of a plurality of electrode plates, wherein the width of at least one second-first type electrode tab and the width of at least one second-second type electrode tab may be smaller than the width of at least one first type electrode tab.

[0022] In the battery cell manufacturing method according to the embodiment, at least one 2-1 type electrode tab and at least one 2-2 type electrode tab cannot overlap each other in the stacking direction of the plurality of electrode tabs.

[0023] In the method for manufacturing a battery cell according to the embodiment, the plurality of electrode tabs may be made of lithium or a lithium-containing alloy. [Effects of the Invention]

[0024] According to one embodiment, it is possible to provide a battery cell in which the thickness of the electrode tab bundle (electrode tab assembly) extending from the electrode assembly to the lead tab is significantly reduced.

[0025] Furthermore, according to one embodiment, it is possible to provide a battery cell having improved connectivity with lead tabs and a structure that allows the electrode assembly to be easily inserted into the case. [Brief explanation of the drawing]

[0026] [Figure 1] It is an exploded perspective view of a battery cell according to an embodiment. [Figure 2] It is a reference view showing the shape in which a plurality of electrode plates according to an embodiment are stacked. [Figure 3] It is a partial enlarged view for explaining a first type of electrode tab and a second type of electrode tab among some forms of the electrode tab according to an embodiment. [Figure 4] It is an exemplary cross-sectional view according to the I-I' portion of FIG. 2. [Figure 5] It is a reference view showing the shape in which a plurality of electrode plates according to a comparative form are stacked. [Figure 6] It is a cross-sectional view according to the II-II' portion of FIG. 5. [Figure 7] It is a reference view showing the shape in which a plurality of electrode plates according to another embodiment are stacked. [Figure 8] It is a partial enlarged view for explaining different types of electrode tabs of a plurality of electrode plates. [Figure 9] It is an exemplary cross-sectional view according to the III-III' portion of FIG. 7. [Figure 10] It is an exemplary cross-sectional view according to the IV-IV' portion of FIG. 7.

Best Mode for Carrying Out the Invention

[0027] Prior to the detailed description of the present invention, the terms and words used in this specification and the claims should not be construed as being limited to ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the terms as concepts in order to explain his own invention in the best way, they must be construed in meanings and concepts that conform to the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention. Thus, it should be understood that there may be various equivalents and modifications that can replace them at the time of this application.

[0028] The same reference numerals or symbols in the drawings attached to this specification indicate parts or components that perform substantially the same function. For the sake of explanation and understanding, different embodiments may also be described using the same reference numerals or symbols. That is, even if multiple drawings illustrate components with the same reference numerals, not all of the drawings necessarily represent a single embodiment.

[0029] In the following descriptions, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as “contains” or “constitutes” are intended to specify the existence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the existence or possibility of adding one or more different features, figures, stages, operations, components, parts, or combinations thereof.

[0030] Furthermore, in the following explanation, terms such as upper, top, lower, bottom, side, front, and rear are used based on the direction shown in the drawing, and it should be made clear beforehand that they may be used differently if the direction of the object in question is changed.

[0031] Furthermore, in this specification and claims, terms including ordinal numbers, such as "first," "second," etc., may be used to distinguish between components. Such ordinal numbers are used to distinguish identical or similar components from one another, and the use of such ordinal numbers should not restrict the meaning of the terms. For example, components combined with such ordinal numbers should not be restricted in terms of their order of use or arrangement by the numbers. Where necessary, the ordinal numbers may be used alternately with each other.

[0032] Embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the spirit of the present invention is not limited to the embodiments presented. For example, a person skilled in the art who understands the spirit of the present invention may propose other embodiments that fall within the scope of the spirit of the present invention through additions, modifications, or deletions of components, and these too would fall within the scope of the spirit of the present invention. In the drawings, the shape and size of elements, etc., may be exaggerated for clearer explanation.

[0033] Figure 1 is an exploded perspective view of a battery cell 1 according to an embodiment.

[0034] The battery cell 1 may include an electrode assembly 10 in which multiple electrode plates 11 and 12 are stacked, a case 30 in which the electrode assembly 10 is housed, and lead tabs 20 that are electrically connected to the electrode assembly 10 and a portion of which is exposed to the outside of the case 30.

[0035] The case 30 may include an electrode housing section 33 in which the electrode assembly 10 is housed and a sealing section 34 positioned along the edge of the electrode housing section 33. The electrode housing section 33 may be formed by joining an upper case 32 and a lower case 31 vertically and have an internal space in which the electrode assembly 10 is housed. The sealing section 34 is formed by crimping or heat-sealing the edges of the upper case 32 and the lower case 31 along the edge of the electrode housing section 33, thereby preventing foreign matter and moisture from outside the case 30 from flowing into the electrode assembly 10 housed inside the electrode housing section 33.

[0036] The case 30 may be a pouch-type case made of a flexible material. For example, the case 30 may be made of an aluminum laminate sheet. However, the case 30 of the battery cell 1 according to this embodiment may also be made of a can-type (or rectangular) case or a cylindrical case made of a metal material such as aluminum, in addition to the pouch-type case described above.

[0037] The electrode assembly 10 may have a structure in which a plurality of first electrode plates 11 and a plurality of second electrode plates 12 having opposite polarities are stacked with a separation membrane 13 in between.

[0038] The separation membrane 13 is interposed between the first electrode plate 11 and the second electrode plate 12 to prevent electrical short circuits between the first electrode plate 11 and the second electrode plate 12, and can be configured to be impregnated with an electrolyte so that ions can pass through. The separation membrane 13 can be made of a porous polymer film or a porous nonwoven fabric, etc. However, the material of the separation membrane 13 can be any material commonly used in lithium secondary batteries, in addition to the materials mentioned above, without any particular limitations.

[0039] Multiple first electrode plates 11 and multiple second electrode plates 12 may each be provided with electrode tabs 14. Electrode tabs 14 with the same polarity can come together to form an electrode tab assembly ET. Lead tabs 20, which act as terminals in the battery cell 1, may be combined with the electrode tab assembly ET, thereby electrically connecting the electrode assembly 10 and the lead tabs 20. Various welding methods, including ultrasonic welding, or physical fastening methods such as rivets can be applied to the combination of the electrode tab assembly ET and the lead tabs 20.

[0040] The lead tab 20 may be made of a conductive metallic material. For example, the lead tab 20 may be made of nickel (Ni), aluminum (Al), copper (Cu), and iron (Fe), or alloys containing these metals.

[0041] An insulating member 21 may be placed between the lead tab 20 and the case 30. For example, the insulating member 21 may be made of a material that has both insulating and adhesive properties, and may be joined to the sealing portion 34 of the case 30 while covering a portion of the lead tab 20, thereby ensuring electrical insulation between the lead tab 20 and the case 30 and preventing the sealing between the lead tab 20 and the sealing portion 34 from being impaired.

[0042] In this embodiment, the first electrode plate 11 and the second electrode plate 12 of the electrode assembly 10 may be electrode plates having opposite polarities. For example, if the first electrode plate 11 is a negative electrode plate, the second electrode plate 12 may be a positive electrode plate. (Or vice versa.)

[0043] The positive electrode plate may have a structure in which a positive electrode active material layer is formed on a metal current collector. For example, the positive electrode plate may be formed by coating a mixture of positive electrode active material, conductive material, and binder onto a current collector made of aluminum alloy material. In this case, the materials of the positive electrode active material, binder, conductive material, and current collector can be any known materials used in lithium secondary batteries without limitation.

[0044] The battery cell 1 according to this embodiment may consist of a lithium metal battery or a lithium sulfur battery, in which case the negative electrode plate may be made of a lithium metal sheet, unlike conventional negative electrode plates.

[0045] In conventional lithium-ion secondary batteries, the negative electrode plate may have a structure in which a negative electrode active material layer is formed on a metal current collector. For example, the negative electrode plate may be formed by coating a mixture of negative electrode active material, conductive material, and binder onto a current collector made of a copper alloy material.

[0046] In contrast, the negative electrode plate of the battery cell 1 according to this embodiment may have an integrated structure made of a lithium metal sheet. The lithium metal sheet is a flat sheet member made of lithium or a lithium alloy material, and the negative electrode plate and the negative electrode tab formed on one side of the negative electrode plate according to this embodiment can be realized by appropriately processing the shape of the lithium metal sheet.

[0047] Battery cell 1, which employs a negative electrode plate made of lithium metal sheet, can have a very high energy density because it eliminates the need for conventional negative electrode current collectors made of nickel (Ni), aluminum (Al), copper (Cu), etc.

[0048] However, if the negative electrode plate is made of lithium metal sheet, the wide electrode plate body facing the separation membrane 13 and the electrode tabs extending from it may be formed integrally and have the same thickness. This may cause the thickness of the electrode tab assembly ET, in which the electrode tabs are stacked, to increase to a degree corresponding to the thickness of the stacked negative electrode plates. The enlarged electrode tab assembly ET hinders the ease of welding during the welding process with the lead tabs 20, and it is difficult to properly bend the electrode tab assembly ET to accommodate the narrow space formed between the electrode assembly 10 and the sealing portion 34, thus making it difficult to house inside the case 30.

[0049] In particular, when the electrode tabs 14 are made of lithium metal, ultrasonic welding may be applied to the combination between the electrode tab assembly ET and the lead tabs 20. However, the lithium electrode tab assembly ET, which is enlarged due to the material properties of lithium, may be expanded during the ultrasonic welding process, potentially causing interference with other components of the battery cell 1. For example, the lithium electrode tab assembly ET may expand due to the pressure applied during the welding process, causing interference with the insulating member 21 that covers the lead tabs 20 and is in close contact with the case 30, thereby impairing the sealing of the case 30 and potentially causing an electrical short circuit between the negative electrode plate and the case 30.

[0050] To solve these problems, the electrode tab assembly ET according to the embodiment may be composed of multiple regions with different thicknesses. The structure of such an electrode tab assembly ET will be described in more detail below with reference to Figures 2 to 4.

[0051] Figure 2 is a reference diagram showing the shape in which multiple electrode plates 100 according to the embodiment are stacked.

[0052] Figure 3 is a partially enlarged view illustrating the first type electrode tab 120a and the second type electrode tab 120b, among several forms of the electrode tab according to the embodiment.

[0053] Figure 4 is an exemplary cross-sectional view relating to the I-I' portion of Figure 2.

[0054] The multiple electrode plates 100 and lead tabs 20 described in Figures 2 to 4 may include all the technical features of the multiple electrode plates 11 and lead tabs 20 described in Figure 1. For example, the multiple first electrode plates 100 shown in Figures 2 to 4 are all electrode plates having the same polarity and may correspond to the negative electrode plates described in Figure 1 (on the other hand, the description of the multiple first electrode plates 100 shown in Figures 2 to 4 may also be applied to the positive electrode plates described in Figure 1).

[0055] Multiple first electrode plates 100 having the same polarity can be stacked in one direction with other multiple second electrode plates 12 having opposite polarity and a separation membrane 13 in between. For example, Figure 2 shows multiple first electrode plates 100 stacked in one direction in this manner (the second electrode plates 12 and separation membrane 13 are omitted in Figure 2).

[0056] The first electrode plate 100 may include electrode plate body portions 110a, 110b facing the separation membrane 13 and electrode tabs 120a, 120b protruding from the electrode plate body portions 110a, 110b toward the lead tab 20. For example, if a plurality of first electrode plates 100 are stacked in a first direction (e.g., the Z-axis direction), the electrode tabs 120a, 120b of the first electrode plate 100 may protrude from the electrode plate body portions 110a, 110b in a second direction (e.g., the Y-axis direction).

[0057] Multiple electrode tabs 120a, 120b protruding from multiple first electrode plates 100 can be stacked on top of each other to form an electrode tab assembly ET1, and at least a portion of this electrode tab assembly ET1 can be welded to a lead tab 20.

[0058] In the embodiment, the multiple first electrode plates 100 may include electrode plates of different types having electrode tabs 120a and 120b of different sizes. For example, referring to Figures 2 and 3, the multiple first electrode plates 100 may include one or more first type electrode plates 100a and one or more second type electrode plates 100b, each having first type electrode tabs 120a and second type electrode tabs 120b of different sizes.

[0059] In the drawing, the first type electrode plate 100a is shown with shading, but this is merely to facilitate the distinction between the first type electrode plate 100a and the second type electrode plate 100b in the drawing, and does not mean that the first type electrode plate 100a and the second type electrode plate 100b are made of different materials or surface shapes. For example, regardless of the presence or absence of shading in the drawing, both the first type electrode plate 100a and the second type electrode plate 100b can be made of lithium metal sheets.

[0060] Furthermore, although the drawing shows one first-type electrode plate 100a and two second-type electrode plates 100b stacked alternately, the stacking pattern of the first-type electrode plate 100a and the second-type electrode plate 100b is not limited to this, and they can be stacked in a variety of patterns as needed.

[0061] The second type electrode tab 120b of the second type electrode plate 100b may be smaller in size than the first type electrode tab 120a of the first type electrode plate 100a. For example, referring to Figure 3, the length L2 of the second type electrode tab 120b may be smaller than the length L1 of the first type electrode tab 120a. In this case, the width W2 of the second type electrode tab 120b may be the same as or even smaller than the width W1 of the first type electrode tab 120a, as shown in Figure 3 (however, the width W2 of the second type electrode tab 120b is not necessarily limited to being less than or equal to the width W1 of the first type electrode tab 120a, and may be even larger than the width W1 of the first type electrode tab 120a if necessary).

[0062] Due to the difference in length L1 between the first type electrode tab 120a and the second type electrode tab 120b, when multiple first electrode plates 100 are stacked, the first type electrode tab 120a may protrude even further than the second type electrode tab 120b.

[0063] Furthermore, due to these differences in length, the electrode tab assembly ET1 can be divided into multiple regions with different numbers of stacked electrode tabs 120a and 120b. For example, referring to Figure 4, the electrode tab assembly ET1 can be divided into a first region FA1 where both first-type electrode tabs 120a and second-type electrode tabs 120b are stacked, and a second region SA1 where only first-type electrode tabs 120a are stacked. In the first region FA1, all first-type electrode tabs 120a and second-type electrode tabs 120b are stacked, while in the second region SA1, only first-type electrode tabs 120a are stacked. Therefore, the number of electrode tabs 120a and 120b constituting the first region FA1 may be even greater than the number of electrode tabs 120a and 120b constituting the second region SA1.

[0064] In the first region FA1, a plurality of first-type electrode tabs 120a and a plurality of second-type electrode tabs 120b can be combined to form a first connection portion FC1. At this time, various welding methods, including ultrasonic welding and laser welding, or mechanical fastening methods utilizing rivets, can be applied to join the first-type electrode tabs 120a and the second-type electrode tabs 120b. For example, the first connection portion FC1 can be formed by ultrasonic welding, which applies pressure to the upper and / or lower surfaces of the first-type electrode tabs 120a and the second-type electrode tabs 120b when they are stacked and aligned.

[0065] In the second region SA1, multiple first-type electrode tabs 120a can be combined with each other to form a second connection SC1. A lead tab 20 may be combined with the second connection SC1. Various welding methods, including ultrasonic welding and laser welding, or mechanical fastening methods such as rivets can be applied to form the second connection SC1 and to the combination of the second connection SC1 and the lead tab 20.

[0066] In this case, with multiple first-type electrode tabs 120a aligned, the welding process may proceed after the lead tab 20 is fixed to the second region SA1, and the second connection part SC1 may be formed simultaneously with the combination with the lead tab 20. Alternatively, the multiple first-type electrode tabs 120a may first be welded together to form the second connection part SC1, and then the lead tab 20 may be welded to the second connection part SC1.

[0067] The second connector SC1 may extend from the first connector FC1 and come into contact with the lead tab 20. In other words, the first connector FC1 may be positioned between the second connector SC1 and the multiple electrode plates 100.

[0068] Since the first connection part FC1 is formed by stacking both the first type electrode tab 120a and the second type electrode tab 120b, its thickness D1 can be even thicker than the thickness D2 of the second connection part SC1, which is made up of only the first type electrode tab 120a.

[0069] For example, referring to Figure 4, the second type electrode tab 120b, which forms the first connection FC1 together with the first type electrode tab 120a, may be configured so as not to overlap with the lead tab 20 in the stacking direction of the electrode tabs 120a and 120b (for example, in the Z-axis direction). As a result, the thickness of the second connection SC1 may be smaller than the thickness of the first connection FC1 by a thickness corresponding to the stacking thickness of the second type electrode tab 120b.

[0070] With this structure, the first type electrode tab 120a forming the second connection SC1 is welded to the lead tab 20 and directly electrically connected to the lead tab 20, whereas the second type electrode tab 120b forming part of the first connection FC1 can be electrically connected to the lead tab 20 via the first type electrode tab 120a.

[0071] Thus, according to the electrode tab assembly ET1 of this embodiment, the thickness of the second region SA1 that is combined with the lead tab 20 is formed to be thin, so the thickness of the electrode tab assembly ET1 can be partially reduced. In particular, the thickness of the second connecting portion SC1 that is combined with the lead tab 20 can be significantly reduced, which increases the ease of welding with the lead tab 20 and allows the electrode assembly 10a to be easily deformed to match the internal shape of the case (30 in Figure 1) while connected to the lead tab 20, thus increasing the ease of inserting the electrode assembly 10a into the case.

[0072] In particular, when the first electrode plate 100 is made of lithium metal sheets, only a portion of the lithium electrode tabs having a thickness corresponding to the thickness of the electrode plate body portions 110a and 110b (i.e., the first type electrode tab 120a) can be connected to the lead tab 20, while the other portion (i.e., the second type electrode tab 120b) can be connected to the electrode tab connected to the lead tab 20 (i.e., the first type electrode tab 120a), thereby ensuring easy connection to the lead tab 20 without hindering the electrical conductivity of the electrode tab assembly ET1. Furthermore, since the thickness of the second connection portion SC1 connected to the lead tab 20 is much smaller than the thickness of the stacked lithium metal electrode plates, it is possible to prevent the lithium metal electrode tabs from expanding during the welding process and causing interference with other components of the battery cell, such as the insulating member 21 of the lead tab 20.

[0073] Below, we will describe the battery cell having the aforementioned electrode tab assembly ET1 from the perspective of its manufacturing method.

[0074] First, an alignment step is performed in which multiple electrode plates 100 that constitute a part of the electrode assembly 10a of the battery cell are aligned to form an electrode tab assembly ET1 composed of multiple electrode tabs 120a and 120b extending from the multiple electrode plates 100.

[0075] The electrode tab assembly ET1 can be welded to the lead tab 20 through a welding process. The welding process may include a first welding stage in which a first region FA1 of the electrode tab assembly ET1 is welded, and a second welding stage in which the lead tab 20 is welded to a second region SA1 of the electrode tab assembly ET1. Various welding methods may be applied in the first and second welding stages, but for example, ultrasonic welding may be applied.

[0076] The first welding stage may be performed before the second welding stage. That is, the first welding stage may be performed first to form the first connection FC1 and complete the electrical connection between the multiple electrode tabs 120a and 120b, after which the second welding stage may be performed on the portion of the first type electrode tab 120a corresponding to the second region SA1 to form the second connection SC1 and complete the electrical connection between the electrode tab assembly ET1 and the lead tab 20.

[0077] After the first welding stage, the multiple first type electrode tabs 120a are aligned close to each other, which can further increase the ease of welding with the lead tab 20. Therefore, the first welding step can also serve as a kind of pre-welding for the easy welding of the lead tab 20 and the electrode tab assembly ET1.

[0078] Through the welding process, the lead tab 20 and the electrode assembly 10a can be combined and electrically connected to each other. The connected electrode assembly 10a and lead tab 20 can be housed inside the case (30 in Figure 1) during the casing stage. During the casing stage, the electrode assembly 10a is placed in the electrode housing portion (33 in Figure 1) of the case 30, and the case 30 is crimped or heat-fused along the end of the electrode housing portion 33 to form a sealing portion (34 in Figure 1). At this time, an insulating member 21 is placed between the lead tab 20 and the case 30, thereby electrically insulating the lead tab 20 and the case 30 from each other and ensuring the airtightness of the lead tab 20 portion.

[0079] In the following, the difference in thickness of the electrode tab assembly between the embodiment and the comparative embodiment will be explained with reference to the comparative embodiment shown in Figures 5 and 6.

[0080] Figure 5 is a reference diagram showing the shape in which multiple electrode plates 200 related to the comparative configuration are stacked.

[0081] Figure 6 is a cross-sectional view relating to the section II-II' of Figure 5.

[0082] The multiple electrode plates 200 in the comparative configuration described in Figures 5 and 6 are identical in all features except for the shape of the electrode tabs 220 when compared with the first electrode plate 100 described in Figures 2 to 4. For example, as shown in Figure 5, the multiple electrode plates 200 in the comparative configuration may have electrode tabs 220 of the same size, thereby allowing all of the lead tabs 20 to overlap in the stacking direction of the multiple electrode plates 200 (for example, in the Z-axis direction).

[0083] As a result, the thickness of the portion of each electrode plate 200 that is connected to the lead tab 20 is the same as the sum of the thicknesses of each electrode tab 220.

[0084] Referring to both Figure 4 and Figure 6, when electrode tabs of the same thickness t are stacked from nine electrode plates, each extending from the other, to form an electrode tab assembly in both embodiments and comparative embodiments, the thickness D3 of the portion to which the lead tab 20 is connected in the comparative electrode tab assembly is 9t, whereas in the embodiment electrode tab assembly ET1, the thickness of the portion to which the lead tab 20 is connected (i.e., the second connection portion SC1) is 3t, confirming that the thickness is reduced to 1 / 3.

[0085] In other words, according to the structure of the electrode tab assembly ET1 according to this embodiment, the thickness of the portion to which the lead tabs 20 are connected can be significantly reduced compared to an electrode tab assembly structure, such as the comparative embodiment, which is composed entirely of lead tabs 20 and electrode tabs 220 that overlap in the stacking direction.

[0086] On the other hand, in another embodiment, the second type of electrode plate can be divided into N electrode tabs of different types formed at different positions. The structure of the electrode tab assembly according to other embodiments will be described below with reference to Figures 7 to 10.

[0087] Figure 7 is a reference diagram showing a configuration in which multiple electrode plates 300 are stacked according to another embodiment.

[0088] Figure 8 is a partially enlarged view illustrating the different types of electrode tabs 320a, 320b1, and 320b2 of the multiple electrode plates 300.

[0089] Figure 9 is an exemplary cross-sectional view relating to the section III-III' of Figure 7.

[0090] Figure 10 is an illustrative cross-sectional view relating to the IV-IV' portion of Figure 7.

[0091] The multiple first electrode plates 300 described in Figures 7 to 10 include all the technical features of the first electrode plate 100 described in Figures 2 to 4, except for those relating to the electrode tabs 120a and 120b; therefore, explanations that overlap with Figures 2 to 4 can be omitted.

[0092] In the embodiment, the multiple first electrode plates 300 may include first type electrode plates 300a and second type electrode plates 300b1, 300b2 having electrode tabs 320a, 320b1, 320b2 formed of different sizes from each other. For example, referring to Figures 7 and 8, the lengths L2a, L2b and widths W2a, W2b of the second type electrode tabs 320b1, 320b2 of the second type electrode plates 300b1, 300b2 may be even smaller than the length L1 and width W1 of the first type electrode tab 320a of the first type electrode plate 300a.

[0093] In summary, the second type of electrode plate can consist of N electrode plates of different types, each having N electrode tabs of different types formed at different positions (where N can be a natural number greater than or equal to 2). For example, multiple second type electrode plates may have N electrode tabs of different types protruding from different positions along the width direction (e.g., the X-axis direction) of the first electrode plate 300.

[0094] Figures 7 to 10 illustrate embodiments in which N is 2. Referring to Figure 8, the second type of electrode plates 300b1 and 300b2 may include a second-first type electrode plate 300b1 and a second-second type electrode plate 300b2, each having a second-first type electrode tab 320b1 and a second-second type electrode tab 320b2 that protrude from different positions at the ends of the electrode plate body portions 310b1 and 310b2, respectively.

[0095] In a state where the second type electrode plates 300b1 and 300b2 are stacked, the second-first type electrode tab 320b1 and the second-second type electrode tab 320b2 may be positioned at different locations from each other along the width direction (e.g., the X-axis direction) of the electrode plate body portions 310b1 and 310b2. For example, referring to Figure 7, in a state where multiple second type electrode plates 300b1 and 300b2 are stacked, the second-first type electrode tab 320b1 and the second-second type electrode tab 320b2 may be positioned at different locations from each other along the width direction (X-axis direction) of the second type electrode plates 300b1 and 300b2, and configured so that at least a portion of the second type electrode plates 300b1 and 300b2 do not overlap each other in the stacking direction (Z-axis direction).

[0096] In this case, N electrode tabs 320b1, 320b2 of different types can be welded to different parts of the first type electrode tab 320a, respectively. That is, N electrode tabs 320b1, 320b2 of different types can be arranged at different positions along the width direction of the electrode plate body portions 310b1, 310b2 and stacked so as to face different parts of the first type electrode tab 320a, and can be welded to different parts of the first type electrode tab 320a through a welding process that forms the first connection portion FC2.

[0097] At least two of the N electrode tabs 320b1, 320b2 of different types can be arranged so as not to overlap each other in the stacking direction (e.g., Z-axis direction) of the electrode tab assembly ET2. For example, referring to Figures 7 and 10, the 2-1 type electrode tab 320b1 and the 2-2 type electrode tab 320b2 can be arranged so as not to overlap each other in the stacking direction (Z-axis direction) of the electrode tab assembly ET2 (or the stacking direction of the 2 type electrode plates 300b1, 300b2). As a result, as shown in Figure 10, the 2-1 type electrode tab 320b1 and the 2-2 type electrode tab 320b2 can be arranged on the same layer by stacking the electrode tabs.

[0098] In this case, the widths W2a and W2b of each of the N different types of electrode tabs 320b1 and 320b2 can be set to be 1 / N or less of the width W1 of at least one first type electrode tab 320a. For example, referring to Figures 8 and 10, the widths W2a of the second-first type electrode tab 320b1 and the widths W2b of the second-second type electrode tab 320b2 can be formed to be less than half the width W1 of the first type electrode tab 320a, so that when the first type electrode tab 320a and the second type electrode tabs 320b1 and 320b2 are stacked, the ends on both sides of the second type electrode tabs 320b1 and 320b2 in the width direction (X-axis direction) cannot protrude further than the first type electrode tab 320a. In this structure, when the electrode tabs are stacked, the relatively smaller second-type electrode tabs 320b1 and 320b2 are located within the area of ​​the relatively larger first-type electrode tab 320a. Therefore, during the process of inserting the electrode tab assembly ET2 into the case 30, it is possible to prevent the smaller electrode tabs (i.e., the second-type electrode tabs 320b1 and 320b2) from being damaged or from interfering with adjacent electrode tabs of opposite polarity and other components inside the case (30 in Figure 1).

[0099] Furthermore, by arranging N electrode tabs 320b1 and 320b2 of different types so that they do not overlap each other in the stacking direction of the electrode tab assembly ET2, the thickness of the first connection portion FC2 of the electrode tab assembly ET2 can be further reduced.

[0100] In particular, according to the structure of the N different types of electrode tabs 320b1 and 320b2 described above, the thickness of the first connection portion FC2 of the electrode tab assembly ET2 according to the embodiment can be significantly reduced compared to the first connection portion FC1 of the electrode tab assembly ET1 according to the embodiment shown in Figures 2 to 4.

[0101] First, referring to Figure 9, in the first region FA2 of the electrode tab assembly ET2, multiple first-type electrode tabs 320a and multiple second-type electrode tabs 320b1 and 320b2 can be combined to form the first connection portion FC2. At this time, various welding methods, including ultrasonic welding and laser welding, or mechanical fastening methods using rivets, can be applied to join the first-type electrode tabs 320a and the second-type electrode tabs 320b1 and 320b2.

[0102] In the second region SA2 of the electrode tab assembly ET2, multiple first-type electrode tabs 320a can be combined with each other to form a second connection SC2. A lead tab 20 may be combined with the second connection SC2. Various welding methods, including ultrasonic welding and laser welding, or mechanical fastening methods such as rivets can be applied to form the second connection SC2 and to the combination of the second connection SC2 and the lead tab 20.

[0103] The second type of electrode tabs 320b1 and 320b2 can be arranged so as not to overlap with the lead tabs 20 in the stacking direction (e.g., the Z-axis direction) of the electrode tab assembly ET2, thereby allowing the number of electrode tabs constituting the second region SA2 and the second connection SC2 to be smaller than the number of electrode tabs constituting the first region FA2 and the first connection FC2. This is the same as the characteristics of the second type of electrode tab 120b described in Figures 2 to 4, and therefore, a description thereof can be found in Figures 2 to 4.

[0104] Continuing the explanation with reference to Figure 9, the 2-1 type electrode tab 320b1 and the 2-2 type electrode tab 320b2 included in the second type electrode tabs 320b1 and 320b2 are arranged so as not to overlap each other in the stacking direction (e.g., the Z-axis direction) of the electrode tab assembly ET2, and can therefore be placed on the same layer at the first connection part FC2. For example, as shown in Figure 9, when the first type electrode plate 300a, the 2-1 type electrode plate 300b1, and the 2-2 type electrode plate 300b2 are repeatedly stacked in order, the 2-1 type electrode tab 320b1 and the 2-2 type electrode tab 320b2 are arranged side by side along the upper surface of the first type electrode tab 320a at the first connection part FC2 of the electrode tab assembly ET2, and can therefore form the same layer.

[0105] As a result, when electrode tabs of the same thickness t are stacked from nine first electrode plates 100 and 300, respectively, to form electrode tab assemblies ET1 and ET2, the thickness of the first connection part FC1 according to the embodiment shown in Figure 4 is 9t, while the thickness D4 of the first connection part FC2 according to the embodiment shown in Figure 9 may be 6t. In other words, by arranging N electrode tabs of different types between two adjacent first type electrode tabs 320a on the same layer, the thickness of the first connection part FC2, which combines the first type electrode tab 320a and the second type electrode tabs 320b1 and 320b2, can be significantly reduced.

[0106] As a result, during the ultrasonic welding process of the first connection part FC2, the electrode tabs constituting the first connection part FC2 expand and can be more reliably prevented from interfering with other parts such as the insulating material of the lead tab 20. In addition, in the electrode tab assembly ET2, the thickness D4 of the first connection part FC2 connecting the lead tab 20 and the multiple electrode plates 300 is significantly reduced, greatly increasing the ease of welding the first connection part FC2. Furthermore, the electrode tab assembly ET2 can be easily deformed to match the internal shape of the case 30 while connected to the lead tab 20, thereby increasing the insertability of the case 30.

[0107] As shown in Figure 9, the thickness D5 of the second connection portion SC2, which is formed by stacking the first type electrode tabs 320a, may be the same as the thickness of the second connection portion SC2 shown in Figure 4, which is 3t. That is, the electrode tab assembly ET2 according to the embodiments of Figures 7 to 10 may have a structure in which the thickness of the first connection portion FC2 and the second connection portion SC2 gradually decreases.

[0108] On the other hand, in terms of the manufacturing method of the battery cell, the formation of the electrode tab assembly ET2 shown in Figure 9 can be similarly performed using the lamination stage, the first welding stage, and the second welding stage described in Figures 2 to 4. Therefore, a detailed explanation of this can be found in the explanations in Figures 2 to 4.

[0109] Figures 7 to 10 illustrate embodiments in which the second type of electrode tabs 320b1 and 320b2 are divided into two distinct types of electrode tabs, i.e., embodiments in which N is 2. However, this is merely illustrative, and in other embodiments, N may be 3 or more. For example, the second type of electrode tab may include three distinct types of electrode tabs, i.e., a 2-1 type electrode tab, a 2-2 type electrode tab, and a 2-3 type electrode tab.

[0110] In this case, the 2-1 type electrode tabs, the 2-2 type electrode tabs, and the 2-3 type electrode tabs can be arranged so as not to overlap each other in the stacking direction of the electrode tab assembly, as explained through Figures 7 to 10. As N increases, the number of 2 type electrode tabs arranged in the same layer along the upper surface of the 1 type electrode tab 320a increases, so that even when stacking a large number of electrode plates, the thickness of the electrode tab assembly can be made sufficiently thin.

[0111] According to the battery cell 1 of this embodiment, the thickness of the electrode tab assemblies ET1 and ET2 extending to one side of the multiple electrode plates 100 and 300 can be reduced, thereby increasing the ease of welding the lead tabs 20 and the electrode tab assemblies ET1 and ET2. Furthermore, the reduction in the thickness of the electrode tab assemblies ET1 and ET2 makes it easier to insert the electrode assembly into the case 30.

[0112] In particular, when multiple electrode plates 100, 300 and electrode tab assemblies ET1, ET2 extending from multiple electrode plates 100, 300 are all made of lithium metal, the structure of first type electrode tabs 120a, 320a and second type electrode tabs 120b, 320b1, 320b2 having different lengths from each other significantly reduces the thickness of the portion of the electrode tab assemblies ET1, ET2 that is combined with the lead tab 20, ensuring ease of ultrasonic welding with the lead tab 20, while simultaneously preventing the lithium metal electrode tabs from spreading during the ultrasonic welding process, causing interference with other parts and hindering the sealing of the case 30.

[0113] Furthermore, according to the embodiment of the battery cell 1, the plurality of second-type electrode tabs are composed of N different types of electrode tabs 320b1, 320b2 formed at different positions along the width direction of the electrode plate, thereby reducing the overall thickness of the electrode tab assembly ET2. This further increases the insertability of the case 30 of the electrode assembly 10b and more reliably prevents short circuits with adjacent electrode tabs of opposite polarity and interference with other components.

[0114] Although various embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be obvious to anyone with average knowledge of the art that various modifications and variations are possible as long as they do not deviate from the technical idea of ​​the present invention as described in the claims. Furthermore, some components of the above-described embodiments may be omitted, and each embodiment may be combined with others.

Claims

1. An electrode tab assembly in which multiple electrode tabs are stacked, each extending to one side from multiple electrode plates, A case in which the plurality of electrode plates are housed, Includes lead tabs electrically connected to the electrode tab assembly, at least a portion of which is exposed outside the case, The electrode tab assembly is A first connecting portion is formed by welding together at least a portion of the plurality of electrode tabs, It includes a second connecting portion that extends from the first connecting portion and is welded to the lead tab, A battery cell in which the number of electrode tabs constituting the second connection portion is smaller than the number of electrode tabs constituting the first connection portion.

2. The aforementioned multiple electrode tabs are At least one first type electrode tab forming the second connection portion, The battery cell according to claim 1, comprising at least one second type electrode tab that is shorter than the at least one first type electrode tab and together with the at least one first type electrode tab forms the first connection.

3. The battery cell according to claim 2, wherein the at least one second type electrode tab does not overlap with the lead tab in the stacking direction of the plurality of electrode tabs.

4. The at least one second type electrode tab is, The plurality of electrode plates include N electrode tabs of different types that are arranged at different positions in the width direction, The battery cell according to claim 2, wherein N is a natural number of 2 or more.

5. The battery cell according to claim 4, wherein the N electrode tabs of different types are each welded to different portions of at least one electrode tab of the first type.

6. The battery cell according to claim 4, wherein at least two of the N electrode tabs of different types are arranged so as not to overlap each other in the stacking direction of the plurality of electrode tabs.

7. The battery cell according to claim 5, wherein the width of each of the N different types of electrode tabs is 1 / N or less of the width of at least one first type of electrode tab.

8. The battery cell according to claim 1, wherein the first connection portion is disposed between the second connection portion and the plurality of electrode plates.

9. The battery cell according to any one of claims 1 to 8, wherein the plurality of electrode tabs are made of lithium or a lithium-containing alloy.

10. Alignment step: Aligning multiple electrode tabs extending to one side from multiple electrode plates to form an electrode tab assembly, A first welding step involves ultrasonically welding a first region of the electrode tab assembly, The process includes a second welding step of ultrasonically welding a lead tab to a second region of the electrode tab assembly, A method for manufacturing a battery cell, wherein the number of electrode tabs stacked in the second region is smaller than the number of electrode tabs stacked in the first region.

11. The method for manufacturing a battery cell according to claim 10, wherein the first welding step is performed before the second welding step.

12. The electrode tab assembly is At least one first type electrode tab overlapping the lead tab in the stacking direction of the plurality of electrode tabs, It includes at least one second type electrode tab that is shorter in length than the at least one first type electrode tab and is coupled to the at least one first type electrode tab, In the first region, at least one first type electrode tab and at least one second type electrode tab are stacked together. The method for manufacturing a battery cell according to claim 10, wherein only the at least one of the first type electrode tabs is stacked in the second region.

13. The at least one second type electrode tab includes at least one second-first type electrode tab and at least one second-second type electrode tab, which are arranged at different positions in the width direction of the plurality of electrode plates. The method for manufacturing a battery cell according to claim 12, wherein the width of the at least one second-first type electrode tab and the width of the at least one second-second type electrode tab are narrower than the width of the at least one first type electrode tab.

14. The method for manufacturing a battery cell according to claim 13, wherein the at least one second-first type electrode tab and the at least one second-second type electrode tab do not overlap each other in the stacking direction of the plurality of electrode tabs.

15. The method for manufacturing a battery cell according to any one of claims 10 to 14, wherein the plurality of electrode tabs are made of lithium or a lithium-containing alloy.

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