Secondary battery

Abstract

A secondary battery having improved structural stability is provided. The secondary battery includes: an electrode assembly including a plurality of negative electrodes each including a negative electrode tab and a plurality of positive electrodes alternately arranged with the plurality of negative electrodes and each including a positive electrode tab; a first current collector electrically connected to the negative electrode; and a first insulator disposed below the first current collector, in which the negative electrode tabs of at least some of the plurality of negative electrodes overlap at a first position to form a first negative electrode tab stack, and the negative electrode tabs of some other negative electrodes of the plurality of negative electrodes overlap at a second position different from the first position to form a second negative electrode tab stack, and the first insulator is disposed adjacent to the first negative electrode tab stack and the second negative electrode tab stack at the same time.

Description

Technical Field

[0001] This disclosure relates to secondary batteries. Background Technology

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries that can be repeatedly charged and discharged, and they are already used in various technological fields across the industry. Furthermore, in line with technological advancements and the growing demand for mobile devices, the demand for secondary batteries as an energy source has increased rapidly.

[0003] The information disclosed above in the art that forms the background of this disclosure is intended only to enhance the understanding of the background of this disclosure, and therefore may contain information that does not constitute related art. Summary of the Invention

[0004] This disclosure provides a secondary battery with improved structural stability.

[0005] However, the technical problems to be solved by this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the following description of this disclosure other problems not mentioned.

[0006] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments presented in this disclosure.

[0007] In one embodiment, a secondary battery includes an electrode assembly comprising a plurality of negative electrodes, each including a negative electrode terminal, and a plurality of positive electrodes, alternately arranged with the plurality of negative electrodes and each including a positive electrode terminal. The secondary battery also includes a first current collector electrically connected to the negative electrodes and a first insulator below the first current collector. The negative electrode terminals of at least some of the plurality of negative electrodes overlap at a first location to form a first negative electrode terminal stack, and the negative electrode terminals of some of the other negative electrodes overlap at a second location different from the first location to form a second negative electrode terminal stack. The first insulator is adjacent to the first and second negative electrode terminal stacks.

[0008] In this embodiment, the first insulator may include a bottom portion and a wall portion connected to the bottom portion to define the recessed portion, and the bottom portion may include a plurality of holes passing through the bottom portion.

[0009] In this embodiment, the first negative electrode terminal block stack and the second negative electrode terminal block stack can be non-overlapping with each other in the thickness direction of the electrode assembly.

[0010] In this embodiment, the negative electrode tabs of some other negative electrodes among the plurality of negative electrodes can form a third negative electrode tab stack that is different from the first negative electrode tab stack and the second negative electrode tab stack, and the first negative electrode tab stack, the second negative electrode tab stack and the third negative electrode tab stack can not overlap each other in the thickness direction of the electrode assembly.

[0011] In this embodiment, the first insulator may be adjacent to the first negative electrode terminal block stack, the second negative electrode terminal block stack, and the third negative electrode terminal block stack, and may have a step corresponding to the first negative electrode terminal block stack, the second negative electrode terminal block stack, and the third negative electrode terminal block stack in a plan view.

[0012] In this embodiment, the secondary battery may further include a separator located between each of the plurality of negative electrodes and each of the plurality of positive electrodes.

[0013] In this embodiment, the secondary battery may further include: a second current collector electrically connected to a plurality of positive electrodes; and a second insulator below the second current collector. The positive electrode tabs of at least some of the plurality of positive electrodes may overlap at a third position to form a first positive electrode tab stack, and the positive electrode tabs of the other positive electrodes may overlap at a fourth position different from the third position to form a second positive electrode tab stack. The second insulator may be adjacent to the first and second positive electrode tab stacks.

[0014] In this embodiment, the first positive electrode terminal block stack and the second positive electrode terminal block stack can be arranged to be substantially symmetrical with the first negative electrode terminal block stack and the second negative electrode terminal block stack.

[0015] In this embodiment, the second insulator may have a shape substantially the same as that of the first insulator.

[0016] In this embodiment, the secondary battery may further include a negative electrode current collector between the first negative electrode terminal block stack, the second negative electrode terminal block stack, and the first current collector. The negative electrode current collector may have a curved or bent shape to cover the front and upper portions of the first negative electrode terminal block stack and the front and upper portions of the second negative electrode terminal block stack. The negative electrode current collector may be welded to the front portions of the first and second negative electrode terminal block stacks, and the negative electrode current collector may be welded to the first current collector above the first and second negative electrode terminal block stacks.

[0017] In another embodiment, a secondary battery includes an electrode assembly comprising a plurality of negative electrodes, each including a negative electrode terminal, and a plurality of positive electrodes, alternately arranged with the plurality of negative electrodes and each including a positive electrode terminal. The secondary battery also includes a first current collector electrically connected to the electrode assembly and a first insulator below the first current collector. The negative electrode terminals of the plurality of negative electrodes overlap each other to form a plurality of negative electrode terminal stacks. The plurality of negative electrode terminal stacks are arranged at multiple locations in a direction perpendicular to the thickness direction of the electrode assembly and do not overlap each other. The first insulator is adjacent to the plurality of negative electrode terminal stacks and includes a bottom portion having a plurality of holes in the bottom portion.

[0018] In this embodiment, the first insulator may further include a wall portion that connects to the bottom portion and defines the recessed portion.

[0019] In this embodiment, each of the plurality of holes may have a honeycomb shape.

[0020] In this embodiment, the plurality of negative electrode terminal stacks may include three negative electrode terminal stacks, and the three negative electrode terminal stacks may not overlap each other in the thickness direction of the electrode assembly.

[0021] In this embodiment, the first insulator may be adjacent to the stack of three negative electrode terminals and may have a step corresponding to the stack of three negative electrode terminals in a plan view.

[0022] In this embodiment, the secondary battery may further include a separator located between each of the plurality of negative electrodes and each of the plurality of positive electrodes.

[0023] In this embodiment, the secondary battery may further include: a second current collector electrically connected to the electrode assembly; and a second insulator below the second current collector. Positive electrode tabs of a plurality of positive electrodes may overlap each other to form a plurality of positive electrode tab stacks. The plurality of positive electrode tab stacks may not overlap in the thickness direction of the electrode assembly, and the second insulator may be adjacent to the plurality of positive electrode tab stacks.

[0024] In this embodiment, the plurality of positive electrode terminal stacks can be arranged substantially symmetrically with the plurality of negative electrode terminal stacks.

[0025] In this embodiment, the second insulator may have a shape substantially the same as that of the first insulator.

[0026] In this embodiment, the secondary battery may further include: a negative electrode current collector, welded to a plurality of negative electrode terminal block stacks. The negative electrode current collector may have a curved or bent shape to cover the front and upper portions of the plurality of negative electrode terminal block stacks, and the negative electrode current collector may be welded to the front portion of the plurality of negative electrode terminal block stacks, and a first current collector may be welded above the plurality of negative electrode terminal block stacks. Attached Figure Description

[0027] The following accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the contents described in these drawings:

[0028] Figure 1 This is a perspective view schematically illustrating a secondary battery according to an embodiment of the present disclosure;

[0029] Figure 2 It is a schematic example along Figure 1 A cross-sectional view of the section intercepted by line A-A';

[0030] Figure 3 It is an illustrative example. Figure 1 A perspective view of a portion of a secondary battery;

[0031] Figure 4 It is an illustrative example. Figure 1 A plan view of a portion of a secondary battery;

[0032] Figure 5 This is an illustrative example illustrating, according to one embodiment, the inclusion of Figure 1 A perspective view of the insulator in a secondary battery;

[0033] Figure 6 This is a perspective view schematically illustrating a secondary battery according to another embodiment of the present disclosure;

[0034] Figure 7 It is an illustrative example. Figure 6 A plan view of the upper part of the secondary battery;

[0035] Figure 8 This is an illustrative example including... Figure 6 A plan view of another embodiment of the insulator in a secondary battery; and

[0036] Figure 9 This is a perspective view schematically illustrating a secondary battery according to another embodiment of the present disclosure. Detailed Implementation

[0037] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general and dictionary meaning, but rather is interpreted based on the principle of allowing the inventors to appropriately define terms for best interpretation, and based on the meanings and concepts corresponding to the technical aspects of the present disclosure. Therefore, the embodiments disclosed in this specification and the configurations shown in the accompanying drawings are merely one of the most preferred embodiments of the present disclosure and do not represent all the technical ideas of the present disclosure. Thus, it should be understood that other equivalent substitutions and modifications can be made without departing from the scope of the present disclosure.

[0038] It will be further understood that the term "including or comprising" as used in this specification specifies the presence of the stated features, numbers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components and / or groups thereof.

[0039] Furthermore, for ease of understanding of this disclosure, the drawings are not drawn to scale, and the dimensions of some components may be exaggerated. Additionally, the same components may be given the same reference numerals in different embodiments.

[0040] The statement indicating that two comparison targets are equal to each other implies that the two comparison targets are "substantially" equal to each other. Therefore, substantial equality can include situations where there is a deviation considered low in the art (e.g., a deviation within 5%). Furthermore, a constant configuration of a particular parameter within a predetermined region can mean that the parameter is constant from an average perspective.

[0041] Although the terms first, second, etc., are used to describe different elements, these elements are not limited by these terms. These terms are used to distinguish one element from another, and unless stated otherwise, the first element can be the second element.

[0042] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0043] When an element is "above (or below)" or "on (or below)" another element, the element may be on the upper (or lower) surface of the other element, and there may be an intervening element between the element and another element above (or below) the element.

[0044] Furthermore, when an element is referred to as "connected," "linked," or "coupled" to another element, the element may be directly connected or linked to the other element. However, it should be understood that an intermediary element may exist between the two elements, or the two elements may be "connected," "linked," or "coupled" to each other through another element. Additionally, when one part is electrically connected to another part, this includes not only direct connections but also connections using another element in between.

[0045] Unless otherwise expressly stated, throughout this specification, "A and / or B" means A or B, or both A and B. That is, "and / or" includes all or any combination of the listed items. Unless otherwise expressly stated, "C to D" means C or greater and D or less.

[0046] The terminology used in this specification is for describing embodiments of this disclosure and is not intended to limit this disclosure.

[0047] Figure 1 This is a perspective view schematically illustrating a secondary battery according to an embodiment of the present disclosure.

[0048] refer to Figure 1 According to an embodiment of the present disclosure, a secondary battery 100 includes a housing 101 forming the exterior of the secondary battery 100 and a cover plate 104 connected to the housing 101 to seal the interior of the housing 101.

[0049] The housing 101 can form the exterior of the secondary battery 100 and can have an opening formed on one side to accommodate the electrode assembly. Figure 2 The shell 101 has a roughly hexahedral shape (110 in the figure). However, it is not limited to this and the shell 101 can have a variety of other shapes.

[0050] The housing 101 may contain a conductive metallic material, such as aluminum, aluminum alloy or nickel-plated steel.

[0051] Electrolyte and electrode assembly ( Figure 2 Together with 110, they are housed inside the housing 101, and the opening of the housing 101 can be sealed by the cover plate 104.

[0052] Electrode assembly ( Figure 2 110) can be formed by winding a stack of negative electrodes, diaphragms, and positive electrodes into a sheet or film shape, or by repeatedly stacking them. See below. Figure 2 Detailed description of electrode assembly ( Figure 2 (110 in the middle).

[0053] In the electrode assembly ( Figure 2 After the 110 in the housing 101 is contained therein, the opening on one side of the housing 101 can be sealed by the cover plate 140.

[0054] The cover plate 104 may be made of the same material as the housing 101. The cover plate 104 may be attached to one side of the housing 101 to seal the interior space of the housing 101. In one or more embodiments, after the cover plate 104 is placed on top of the housing 101, the cover plate 104 and the housing 101 may be welded along the edge of the cover plate 104 to form an airtight connection.

[0055] Cover plate 104 may include electrical connections to electrode assemblies ( Figure 2 The negative electrode terminal 102 and positive electrode terminal 103 of the housing 110). In one or more embodiments, the negative electrode terminal 102 may be electrically connected to the first current collector ( ) inside the housing 101. Figure 2 (61 in the middle). The positive electrode terminal 103 can be electrically connected to the second current collector inside the housing 101 ( Figure 3 (63 in the middle).

[0056] The cover plate 104 may include an exhaust port 105 configured to rupture in response to an internal pressure in the sealed housing 101 equal to or higher than a set pressure to release gas.

[0057] The cover plate 104 may include an electrolyte injection port 106. After the cover plate 104 is attached to one side of the housing 101 to seal the internal space of the housing 101, electrolyte can be injected into the sealed housing 101 through the electrolyte injection port 106.

[0058] Figure 2 It is a schematic example along Figure 1 A cross-sectional view of the section intercepted by line A-A', and Figure 3 It is an illustrative example. Figure 1 A perspective view of a portion of a secondary battery.

[0059] For ease of description, Figure 2 Only the electrode assembly 110, negative electrode terminal stacks 23 and 25, negative electrode current collector 50, and first current collector 61 are shown.

[0060] The electrode assembly 110 may include a negative electrode 20, a positive electrode 30, and a diaphragm 40 between the negative electrode 20 and the positive electrode 30.

[0061] Electrode assembly 110 can be manufactured by sequentially stacking negative electrode 20, diaphragm 40, and positive electrode 30 multiple times. However, it is not limited to this; electrode assembly 110 can also be manufactured as a core type by sequentially stacking negative electrode 20, diaphragm 40, and positive electrode 30 and then winding the stack. In one or more embodiments, electrode assembly 110 can be stacked. Furthermore, multiple electrode assemblies 110 electrically connected to each other can be housed inside housing 101.

[0062] The negative electrode 20 may include a portion coated with a negative electrode active material and an uncoated portion of the negative electrode without a negative electrode active material. The negative electrode 20 may include a metal foil such as copper, a copper alloy, nickel, or a nickel alloy.

[0063] The active material of the negative electrode can be carbon material (such as crystalline carbon, amorphous carbon, carbon composite material, carbon fiber), lithium metal, or lithium alloy.

[0064] The uncoated portion of the negative electrode may extend to one side to form a negative electrode tab 21. In one or more embodiments, the negative electrode tab 21 may be connected to the uncoated portion of the negative electrode by welding or the like. That is, the negative electrode 20 may include the negative electrode tab 21 and may be electrically connected to the first current collector 61 via the negative electrode tab 21.

[0065] The negative electrode tab 21 can be positioned so as not to overlap with the diaphragm 40. In one or more embodiments, when manufacturing the negative electrode 20, the negative electrode 20 can be cut such that the negative electrode tab 21 extends to one side, and the negative electrode tab 21 can protrude further to one side than the diaphragm 40 without requiring a separate additional manufacturing process.

[0066] Multiple negative electrode tabs 21 may be overlapped to form negative electrode tab stacks 23 and 25. That is, each of the multiple negative electrode tab stacks 23 and 25 may be a bundle of multiple negative electrode tabs 21 overlapping each other. In one or more embodiments, the multiple negative electrode tab stacks 23 and 25 may be welded to the negative electrode current collector 50, and the number of negative electrode tabs 21 included in each of the negative electrode tab stacks 23 and 25 may be set according to the welding power used during welding and the thickness of the negative electrode tabs 21.

[0067] Each of the plurality of negative electrode tab stacks 23 and 25 may protrude from the top of the electrode assembly 110 toward the first current collector 61 and may be electrically connected to the first current collector 61 via the negative electrode current collector plate 50.

[0068] In one or more embodiments, the plurality of negative electrode tab stacks 23 and 25 may include a first negative electrode tab stack 23 in which at least some of the negative electrode tabs 21 overlap at a first position, and a second negative electrode tab stack 25 in which the other negative electrode tabs 21 overlap at a second position different from the first position. The first negative electrode tab stack 23 and the second negative electrode tab stack 25 may not overlap each other in the thickness direction of the electrode assembly 110 (e.g., the first negative electrode tab stack 23 and the second negative electrode tab stack 25 may be offset or biased from each other in the length direction of the electrode assembly 110).

[0069] The negative electrode current collector 50 can be soldered to the front portion of multiple negative electrode terminal block stacks 23 and 25, so that the negative electrode 20 can be electrically connected to the negative electrode current collector 50.

[0070] The positive electrode 30 may include a portion coated with a positive electrode active material and an uncoated portion of the positive electrode, which is a region without a positive electrode active material. The positive electrode 30 may include a metal foil such as aluminum or an aluminum alloy.

[0071] The active material of the positive electrode can be a lithium-containing transition metal oxide, such as LiCoO2, LiNiO2, LiMnO2, LiMnO4, or lithium chalcogenide compounds.

[0072] The uncoated portion of the positive electrode may extend to one side to form a positive electrode tab. In one or more embodiments, the positive electrode tab may be connected to the uncoated portion of the positive electrode by welding or the like. That is, the positive electrode 30 may include a positive electrode tab and may be electrically connected to the second current collector 63 via the positive electrode tab.

[0073] The positive electrode tab may not overlap with the diaphragm 40. In one or more embodiments, when manufacturing the positive electrode 30, the positive electrode 30 may be cut such that the positive electrode tab extends to one side, and the positive electrode tab may protrude further to one side than the diaphragm 40 without requiring a separate additional manufacturing process.

[0074] Multiple positive electrode terminals can be overlapped to form positive electrode terminal stacks 33 and 35 (see Figure 6That is, each of the plurality of positive electrode tab stacks 33 and 35 may be a bundle of positive electrode tabs overlapping each other. In one or more embodiments, the plurality of positive electrode tab stacks 33 and 35 are connected to the positive electrode current collector 55 by welding, and the number of positive electrode tabs included in each of the positive electrode tab stacks 33 and 35 may be set according to the welding power used during welding and the thickness of the positive electrode tabs. In one or more embodiments, the number of positive electrode tabs included in a positive electrode tab stack 33 or 35 may be equal to the number of negative electrode tabs 21 included in a negative electrode tab stack 23 or 25.

[0075] Each of the plurality of positive electrode tab stacks 33 and 35 may protrude from the top of the electrode assembly 110 toward the second current collector 63 and may be electrically connected to the second current collector 63 via the positive electrode current collector 55.

[0076] In one or more embodiments, the plurality of positive electrode tab stacks 33 and 35 may include a first positive electrode tab stack 33 in which at least some of the positive electrode tabs overlap at a third position, and a second positive electrode tab stack 35 in which other positive electrode tabs overlap at a fourth position different from the third position. The first positive electrode tab stack 33 and the second positive electrode tab stack 35 may not overlap in the thickness direction of the electrode assembly 110 (e.g., the first positive electrode tab stack 33 and the second positive electrode tab stack 35 may be offset or biased from each other in the length direction of the electrode assembly 100). Furthermore, the first positive electrode tab stack 33 and the second positive electrode tab stack 35 may be arranged symmetrically or substantially symmetrically with the first negative electrode tab stack 23 and the second negative electrode tab stack 25.

[0077] The positive electrode current collector 55 can be soldered to the front portion of multiple positive electrode terminal block stacks 33 and 35, so that the positive electrode 30 can be electrically connected to the positive electrode current collector 55.

[0078] The separator 40 is a membrane located between the negative electrode 20 and the positive electrode 30 to prevent (or at least mitigate) electrical contact between the negative electrode 20 and the positive electrode 30 and to prevent (or at least mitigate) short circuits between the negative electrode 20 and the positive electrode 30, and to enable lithium ion migration.

[0079] The area of ​​the diaphragm 40 can be larger than the areas of the negative electrode 20 and the positive electrode 30. Correspondingly, the diaphragm 40 can protrude further toward the first current collector 61 and the second current collector 63 than the negative electrode 20 and the positive electrode 30.

[0080] The diaphragm 40 may be formed of polyethylene, polypropylene, or a composite membrane of polyethylene and polypropylene. However, in this disclosure, the material of the diaphragm 40 is not limited, and in some embodiments, a solid electrolyte may be used instead of the diaphragm 40.

[0081] In one or more embodiments, the negative electrode current collector 50 may be welded and electrically connected to each of the plurality of negative electrode tab stacks 23 and 25. According to one embodiment, the welding between the negative electrode current collector 50 and the plurality of negative electrode tab stacks 23 and 25 may be performed by laser welding.

[0082] The negative electrode current collector 50 may have a curved or bent shape to cover the front and upper portions of the first negative electrode terminal block stack 23 and the second negative electrode terminal block stack 25.

[0083] In one or more embodiments, since the first negative electrode terminal block stack 23 and the second negative electrode terminal block stack 25 do not overlap each other, the negative electrode current collector 50 may include a first negative electrode current collector 51 soldered to the first negative electrode terminal block stack 23 and a second negative electrode current collector 52 soldered to the second negative electrode terminal block stack 25.

[0084] In one or more embodiments, the surface of the first negative electrode current collector 51 can be welded to the front portion of the first negative electrode terminal block stack 23 by laser irradiation, and the surface of the second negative electrode current collector 52 can be welded to the front portion of the second negative electrode terminal block stack 25. Accordingly, the welding area can be increased due to surface welding, and the contact resistance between the negative electrode current collector 50 and the negative electrode terminal block stacks 23 and 25 can be reduced.

[0085] Because the multiple negative electrode tab stacks 23 and 25 do not overlap with the diaphragm 40 and protrude from the top of the electrode assembly 110, the negative electrode current collector 50 can be welded to each of the multiple negative electrode tab stacks 23 and 25 from the outside of the diaphragm 40. Therefore, although the welding power increases during the welding of the negative electrode current collector 50 and the multiple negative electrode tab stacks 23 and 25, damage to the diaphragm 40 from the laser used in the welding process can be prevented (or at least mitigated).

[0086] Furthermore, welding the negative electrode current collector 50 and multiple negative electrode terminal stacks 23 and 25 to the outside of the separator 40 can increase the welding power without the risk of damaging the separator 40 (or reduce the risk of damaging the separator 40). Therefore, welding can be performed with the thicker negative electrode current collector 50, thereby producing a secondary battery 100 that exhibits reduced heat generation during charging and discharging and is therefore conducive to fast charging.

[0087] Furthermore, unlike the existing welding between the current collector and the substrate, welding the negative electrode current collector 50 and multiple negative electrode terminal block stacks 23 and 25 to the outside of the diaphragm 40 can eliminate the forming process required in the process of welding the substrate, thereby preventing the generation of foreign matter and damage to the terminal blocks.

[0088] In one or more embodiments, the negative electrode current collector 50 has a curved or bent shape to cover the front and upper portions of the first negative electrode tab stack 23 and the front and upper portions of the second negative electrode tab stack 25, and the negative electrode current collector 50 can be soldered to a first current collector 61 above the plurality of negative electrode tab stacks 23 and 25.

[0089] In one or more embodiments, such as Figure 3 As shown, the area of ​​the upper surface of the first negative electrode current collector 51 located on the first negative electrode terminal block stack 23 can be equal to (or substantially equal to) the area of ​​the upper surface of the first negative electrode terminal block stack 23, and the area of ​​the upper surface of the second negative electrode current collector 52 located on the second negative electrode terminal block stack 25 can be equal to (or substantially equal to) the area of ​​the upper surface of the second negative electrode terminal block stack 25.

[0090] In one or more embodiments, the ends of the first negative electrode current collector 51 and the second negative electrode current collector 52 may be the same (or substantially the same) on the first negative electrode terminal block stack 23 and the second negative electrode terminal block stack 25, respectively. In one or more embodiments, although the bending points of the first negative electrode current collector 51 and the second negative electrode current collector 52 are different from each other, the ends of the first negative electrode current collector 51 and the second negative electrode current collector 52 may be the same (or substantially the same), thereby the area of ​​the upper surface of the first negative electrode current collector 51 may be larger than the area of ​​the upper surface of the second negative electrode current collector 52. Accordingly, a region may be formed in which the upper surfaces of the first negative electrode current collector 51 and the second negative electrode current collector 52 are continuously connected, thus the welding between the negative electrode current collector 50 and the first current collector 61 can be performed more easily.

[0091] The positive electrode current collector 55 can be electrically connected to each of the plurality of positive electrode terminal block stacks 33 and 35 by welding. According to one embodiment, the welding between the positive electrode current collector 55 and the plurality of positive electrode terminal block stacks 33 and 35 can be performed by laser welding.

[0092] The positive electrode current collector 55 may have a curved or bent shape to cover the front and upper portions of the first positive electrode terminal block stack 33 and the front and upper portions of the second positive electrode terminal block stack 35.

[0093] In one or more embodiments, since the first positive electrode terminal block stack 33 and the second positive electrode terminal block stack 35 do not overlap each other, the positive electrode current collector 55 may include a first positive electrode current collector 56 soldered to the first positive electrode terminal block stack 33 and a second positive electrode current collector 57 soldered to the second positive electrode terminal block stack 35.

[0094] In one or more embodiments, the surface of the first positive electrode current collector 56 can be welded to the front portion of the first positive electrode terminal block stack 33 by laser irradiation, and the surface of the second positive electrode current collector 57 can be welded to the front portion of the second positive electrode terminal block stack 35.

[0095] In one or more embodiments, because the plurality of positive electrode tab stacks 33 and 35 do not overlap with the diaphragm 40 and protrude from the top of the electrode assembly 110, the positive electrode current collector 55 can be welded to each of the plurality of positive electrode tab stacks 33 and 35 from the outside of the diaphragm 40. Therefore, although the welding power increases during the welding of the positive electrode current collector 55 and the plurality of positive electrode tab stacks 33 and 35, laser damage to the diaphragm 40 can be prevented (or at least mitigated).

[0096] Furthermore, by increasing the welding power without the risk of damaging the separator 40 (or reducing the risk of damaging the separator 40), each of the plurality of positive electrode terminal stacks 33 and 35 can be welded to the thicker positive electrode current collector 55. Accordingly, the contact resistance between the positive electrode current collector 55 and the positive electrode terminal stacks 33 and 35 can be reduced, thereby allowing the secondary battery 100 to be charged and discharged at high power, and enabling the manufacture of a secondary battery 100 that facilitates fast charging.

[0097] Furthermore, the positive electrode current collector 55 may have a curved or bent shape to cover the front and upper portions of the first positive electrode terminal block stack 33 and the front and upper portions of the second positive electrode terminal block stack 35, and may be soldered to the second current collector 63 above the plurality of positive electrode terminal block stacks 33 and 35.

[0098] In one or more embodiments, such as Figure 3 As shown, the area of ​​the upper surface of the first positive electrode current collector 56 located on the first positive electrode terminal block stack 33 can be equal to (or substantially equal to) the area of ​​the upper surface of the first positive electrode terminal block stack 33, and the area of ​​the upper surface of the second positive electrode current collector 57 located on the second positive electrode terminal block stack 35 can be equal to (or substantially equal to) the area of ​​the upper surface of the second positive electrode terminal block stack 35.

[0099] In one or more embodiments, the ends of the first positive current collector 56 and the second positive current collector 57 may be the same (or substantially the same) on the first positive electrode terminal block stack 33 and the second negative electrode terminal block stack 35, respectively. In one or more embodiments, although the bending points of the first positive current collector 56 and the second positive current collector 57 are different from each other, the ends of the first positive current collector 56 and the second positive current collector 57 may be the same (or substantially the same), thereby the area of ​​the upper surface of the first positive current collector 56 may be larger than the area of ​​the upper surface of the second positive current collector 57. Accordingly, the upper surfaces of the first positive current collector 56 and the second positive current collector 57 may be continuously connected, thus making the welding between the positive current collector 55 and the second positive current collector 63 easier to perform.

[0100] The shape of the positive electrode current collector 55 can be the same as (or substantially the same as) the shape of the negative electrode current collector 50.

[0101] The first current collector 61 can be located on the negative electrode current collector 50 and the first insulator 70a described below. The lower end of the first current collector 61 can be electrically connected to the negative electrode current collector 50 by soldering, and the upper end of the first current collector 61 can be electrically connected to the negative electrode terminal 102 (see below). Figure 1 ).

[0102] The second current collector 63 can be located on the positive electrode current collector 55 and the second insulator 70b described below. The lower end of the second current collector 63 can be electrically connected to the positive electrode current collector 55 by soldering, and the upper end of the second current collector 63 can be electrically connected to the positive electrode terminal 103 (see below). Figure 1 ).

[0103] The first insulator 70a may be located in the layer containing the plurality of negative electrode terminal stacks 23 and 25 between the electrode assembly 110 and the first current collector 61. The first insulator 70a may be adjacent to both the first negative electrode terminal stack 23 and the second negative electrode terminal stack 25.

[0104] In one or more embodiments, such as Figure 3 As shown, the two first insulators 70a can overlap with the first negative electrode terminal stack 23 and the second negative electrode terminal stack 25 respectively in the thickness direction of the electrode assembly 110.

[0105] In one or more embodiments where the first negative electrode current collector 51 extends further in the thickness direction of the electrode assembly 110 such that the ends of the first negative electrode current collector 51 and the second negative electrode current collector 52 are the same (or substantially the same), a first insulator 70a may overlap with the second negative electrode terminal block stack 25 in the thickness direction of the electrode assembly 110.

[0106] In one or more embodiments where the first negative electrode current collector 51 extends further in the thickness direction of the electrode assembly 110 such that the ends of the first negative electrode current collector 51 and the second negative electrode current collector 52 are the same (or substantially the same), the first insulator 70a may be further located below the negative electrode current collector 50. In one or more embodiments, a total of two first insulators 70a may be provided: one first insulator 70a may be located in the portion covered by the negative electrode current collector 50 to overlap with the first negative electrode tab stack 23 in the thickness direction of the electrode assembly 110, and the other first insulator 70a may be located in the portion not covered by the negative electrode current collector 50 but to overlap with the second negative electrode tab stack 25 in the thickness direction of the electrode assembly 100.

[0107] In one or more embodiments, the height of the first insulator 70a may be equal to (or substantially equal to) the sum of the length of the negative electrode terminal 21 and the thickness of the negative electrode current collector 50. The first insulator 70a may have a generally cuboid shape, but is not limited thereto, and may have various shapes depending on the number of negative electrode terminal stacks.

[0108] The two second insulators 70b can be arranged to overlap with the first positive electrode terminal stack 33 and the second positive electrode terminal stack 35 respectively in the thickness direction of the electrode assembly 110.

[0109] In one or more embodiments where the first positive electrode current collector 56 extends further in the thickness direction of the electrode assembly 110 such that the end of the first positive electrode current collector 56 is the same as (or substantially the same as) the end of the second positive electrode current collector 57, a second insulator 70b may overlap with the second positive electrode terminal block stack 35 in the thickness direction of the electrode assembly 110.

[0110] In one or more embodiments where the first positive electrode current collector 56 extends further in the thickness direction of the electrode assembly 110 such that the end of the first positive electrode current collector 56 is the same as (or substantially the same as) the end of the second positive electrode current collector 57, the second insulator 70b may be located below the positive electrode current collector 55. In one or more embodiments, a total of two second insulators 70b may be provided: one second insulator 70b may be located in the portion covered by the positive electrode current collector 55 to overlap with the first positive electrode tab stack 33 in the thickness direction of the electrode assembly 110, and the other second insulator 70b may be located in the portion not covered by the positive electrode current collector 55 but overlapping with the second positive electrode tab stack 35 in the thickness direction of the electrode assembly 100.

[0111] The shape and effect of the second insulator 70b may be the same as those of the first insulator 70a, and the position of the second insulator 70b may be the same as and / or symmetrical (or substantially symmetrical) to that of the first insulator 70a.

[0112] Figure 4 It is an illustrative example. Figure 1 A plan view of a portion of the secondary battery, and Figure 5 This is an illustrative example including... Figure 1 A perspective view of an embodiment of an insulator in a secondary battery.

[0113] exist Figure 4 and Figure 5 In the middle, the insulator has 70 fingers. Figure 3 Both the first insulator 70a and the second insulator 70b.

[0114] refer to Figure 4 and Figure 5 The insulator 70 may include a bottom portion 77 and a wall portion 78 connected to the bottom portion 77 to define the recessed portion G. Furthermore, the bottom portion 77 may include a plurality of holes 79 passing through it.

[0115] In manufacturing secondary batteries, using the minimum amount of electrolyte to minimize the battery's weight can be advantageous; however, if the electrode assembly 110 is not adequately impregnated with the electrolyte, the battery's performance may deteriorate. In one or more embodiments where the insulator 70 includes a plurality of holes 79 through the bottom portion 77, even if the electrolyte being injected splashes towards the electrodes, the splashed electrolyte can still pass through the holes 79 towards the electrode assembly (…). Figure 2 The 110) emission in the electrolyte prevents the secondary battery from deteriorating even when using the minimum (or substantially minimum) amount of electrolyte.

[0116] The plurality of holes 79 passing through the bottom portion 77 can have various shapes. In one or more embodiments, the holes 79 can have a circular shape, a narrow hole shape, or a honeycomb shape. In embodiments where the holes 79 have a narrow hole shape, the area of ​​the holes 79 can be maximized, thereby facilitating the discharge of electrolyte splashed toward the electrode assembly 110. Furthermore, in embodiments where the holes 79 have a honeycomb shape, the holes 79 can have a dense structure, which can improve the discharge efficiency of electrolyte splashed toward the electrode assembly 110 and can also improve the mechanical stability of the insulator 70.

[0117] In one or more embodiments, when the first current collector 61 is in the negative electrode current collector plate ( Figure 3When the second current collector 63 is on the positive electrode current collector 55, pressure may be applied to the diaphragm 40, which protrudes further toward the current collector 61 than the negative electrode 20 and the positive electrode 30, thereby causing damage to the diaphragm 40. However, when the insulator 70 including the recessed portion G is located on the electrode assembly ( Figure 3 When applied to 110), it is applied to the diaphragm ( Figure 2 The pressure in diaphragm 40 can be dispersed, thus preventing (or at least mitigating) damage to diaphragm 40.

[0118] In addition, the insulator 70 may have a shape corresponding to the multiple terminal block stacks, thereby protecting the multiple terminal block stacks from impact and preventing damage to the negative electrode terminal block 21 and / or the positive electrode terminal block that might otherwise occur during the assembly or use of the secondary battery 100.

[0119] Figure 6 This is a perspective view schematically illustrating a secondary battery according to another embodiment of the present disclosure. Figure 7 It is an illustrative example. Figure 6 A plan view of the upper part of the secondary battery, and Figure 8 This is an illustrative example including... Figure 6 A plan view of another embodiment of the insulator in a secondary battery.

[0120] refer to Figures 6 to 8 Multiple negative electrode tabs 21 may be overlapped to form negative electrode tab stacks 23, 25, and 27. The number of negative electrode tabs 21 included in each of the negative electrode tab stacks 23, 25, and 27 may depend on the welding power used and the thickness of the negative electrode tabs 21. The number of negative electrode tabs 21 included in each of the negative electrode tab stacks 23, 25, and 27 may be the same. In one or more embodiments, the negative electrode tab stacks 23, 25, and 27 may not overlap each other in the thickness direction of the electrode assembly 110 (e.g., the negative electrode tab stacks 23, 25, and 27 may be offset or offset in the length direction of the electrode assembly 110).

[0121] The negative electrode current collector 50 may have a curved or bent shape to cover the front and upper portions of the first negative electrode terminal block stack 23, the front and upper portions of the second negative electrode terminal block stack 25, and the front and upper portions of the third negative electrode terminal block stack 27, and may be soldered to the first current collector 61 (see Figure 3 ).

[0122] In one or more embodiments, since the first negative electrode terminal block stack 23, the second negative electrode terminal block stack 25 and the third negative electrode terminal block stack 27 do not overlap each other, the negative electrode current collector 50 may include a first negative electrode current collector 51 soldered to the first negative electrode terminal block stack 23, a second negative electrode current collector 52 soldered to the second negative electrode terminal block stack 25 and a third negative electrode current collector 53 soldered to the third negative electrode terminal block stack 27.

[0123] In one or more embodiments, a first negative electrode current collector 51 can be welded to the front portion of a first negative electrode terminal block stack 23 by laser, a second negative electrode current collector 52 can be welded to the front portion of a second negative electrode terminal block stack 25, and a third negative electrode current collector 53 can be welded to the front portion of a third negative electrode terminal block stack 27.

[0124] The area of ​​the upper surface of the first negative electrode current collector 51 located on the first negative electrode terminal block stack 23 can be equal to (or substantially equal to) the area of ​​the upper surface of the first negative electrode terminal block stack 23, the area of ​​the upper surface of the second negative electrode current collector 52 located on the second negative electrode terminal block stack 25 can be equal to (or substantially equal to) the area of ​​the upper surface of the second negative electrode terminal block stack 25, and the area of ​​the upper surface of the third negative electrode current collector 53 located on the third negative electrode terminal block stack 27 can be equal to (or substantially equal to) the area of ​​the upper surface of the third negative electrode terminal block stack 27.

[0125] In one or more embodiments, the ends of the first negative electrode current collector 51, the second negative electrode current collector 52, and the third negative electrode current collector 53 may be the same (or substantially the same) on the first negative electrode terminal block stack 23, the second negative electrode terminal block stack 25, and the third negative electrode terminal block stack 27. In one or more embodiments, although the bending points of the first negative electrode current collector 51, the second negative electrode current collector 52, and the third negative electrode current collector 53 are different from each other, the ends of the first negative electrode current collector 51, the second negative electrode current collector 52, and the third negative electrode current collector 53 may be the same (or substantially the same). Therefore, the area of ​​the upper surface of the first negative electrode current collector 51 may be larger than the area of ​​the upper surface of the second negative electrode current collector 52, and the area of ​​the upper surface of the second negative electrode current collector 52 may be formed to be larger than the area of ​​the upper surface of the third negative electrode current collector 53. Accordingly, an area can be formed in which the upper surface of the first negative electrode current collector 51, the upper surface of the second negative electrode current collector 52, and the upper surface of the third negative electrode current collector 53 are continuously connected, so that welding between the negative electrode current collector 50 and the first current collector 61 can be performed more easily.

[0126] The case of positive electrode 30 can be the same as that of negative electrode 20. Multiple positive electrode tabs can be overlapped to form positive electrode tab stacks 33, 35, and 37. The number of positive electrode tabs included in each of the positive electrode tab stacks 33, 35, and 37 can depend on the welding power and the thickness of the positive electrode tabs. The positive electrode tab stacks 33, 35, and 37 can be non-overlapping in the thickness direction of the electrode assembly 110 (e.g., the positive electrode tab stacks 33, 35, and 37 can be staggered or offset in the length direction of the electrode assembly 110).

[0127] The positive electrode terminal stacks 33, 35 and 37 can be arranged to be the same as and / or symmetrical (or substantially symmetrical) to the negative electrode terminal stacks 23, 25 and 27, respectively.

[0128] The positive electrode current collector 55 may have a curved or bent shape to cover the front and upper portions of the first positive electrode terminal block stack 33, the front and upper portions of the second positive electrode terminal block stack 35, and the front and upper portions of the third positive electrode terminal block stack 37, and may be soldered to the second current collector 63 over the plurality of positive electrode terminal block stacks 33, 35, and 37 (see Figure 3 ).

[0129] In one or more embodiments, since the first positive electrode terminal block stack 33, the second positive electrode terminal block stack 35 and the third positive electrode terminal block stack 37 do not overlap each other, the positive electrode current collector 55 may include a first positive electrode current collector 56 soldered to the first positive electrode terminal block stack 33, a second positive electrode current collector 57 soldered to the second positive electrode terminal block stack 35 and a third positive electrode current collector 58 soldered to the third positive electrode terminal block stack 37.

[0130] In one or more embodiments, a first positive electrode current collector 56 can be welded to the front portion of a first positive electrode terminal block stack 33 by laser, a second positive electrode current collector 57 can be welded to the front portion of a second positive electrode terminal block stack 35, and a third positive electrode current collector 58 can be welded to the front portion of a third positive electrode terminal block stack 37.

[0131] The positive electrode current collector 55 may have the same and / or symmetrical (or substantially symmetrical) shape as the negative electrode current collector 50.

[0132] refer to Figure 6 and Figure 7 The first insulator 71a can be in the layer containing the multiple negative electrode terminal stacks 23, 25 and 27 in the electrode assembly 110 and the first current collector 61 (see Figure 3Between the first insulator 71a and the third negative electrode terminal stack 27, the first insulator 71a may be arranged adjacent to the first negative electrode terminal stack 23, the second negative electrode terminal stack 25, and the third negative electrode terminal stack 27, and may have a multi-step shape with steps between the wider and narrower portions. In one embodiment, the steps of the first insulator 71a may correspond to the first negative electrode terminal stack 23, the second negative electrode terminal stack 25, and the third negative electrode terminal stack 27 in a plan view.

[0133] In one or more embodiments, two first insulators 71a may be arranged to overlap with the first negative electrode tab stack 23, the second negative electrode tab stack 25, and the third negative electrode tab stack 27 in the thickness direction of the electrode assembly 110. In one or more embodiments where the first negative electrode current collector 51 and the second negative electrode current collector 52 extend further in the thickness direction of the electrode assembly 110 such that the ends of the first negative electrode current collector 51, the second negative electrode current collector 52, and the third negative electrode current collector 53 are the same (or substantially the same), a first insulator 71a having a multi-stage shape may overlap with the second negative electrode tab stack 25 and the third negative electrode tab stack 27 in the thickness direction of the electrode assembly 100.

[0134] In one or more embodiments where the first negative electrode current collector 51 and the second negative electrode current collector 52 extend further in the thickness direction of the electrode assembly 110 such that the ends of the first negative electrode current collector 51, the second negative electrode current collector 52, and the third negative electrode current collector 53 are the same (or substantially the same), refer to Figure 6 and Figure 7 The first insulator 71a may be located below the negative electrode current collector 50. That is, a total of two first insulators 71a may be provided: one first insulator 71b may be located in the portion covered by the negative electrode current collector 50 to overlap with the first negative electrode terminal block stack 23 and the second negative electrode terminal block stack 25 in the thickness direction of the electrode assembly 110, and the other first insulator 71a may be located in the portion not covered by the negative electrode current collector 50 but to overlap with the second negative electrode terminal block stack 25 and the third negative electrode terminal block stack 27 in the thickness direction of the electrode assembly 100.

[0135] The height of the first insulator 71a can be equal to (or substantially equal to) the sum of the length of the negative electrode terminal 21 and the thickness of the negative electrode current collector 50.

[0136] The second insulator 71b may have a stepped, multi-tiered shape to be adjacent to the first positive electrode pad stack 33, the second positive electrode pad stack 35, and the third positive electrode pad stack 37 in the layer containing the plurality of positive electrode pad stacks 33, 35, and 37. Depending on the arrangement of the plurality of positive electrode pad stacks 33, 35, and 37, the second insulator 71b may have the same (or substantially the same) shape as the first insulator 71a and be symmetrical (or substantially symmetrical) to the first insulator 71a.

[0137] The insulator 71, including the first insulator 71a and the second insulator 71b, may include a bottom portion 77 and a wall portion 78 connected to the bottom portion 77 to define the recessed portion G. The first insulator 71a may include a shorter portion 712 positioned adjacent to the second negative electrode tab stack 25 and a longer portion 711 positioned adjacent to the first negative electrode tab stack 23 or the third negative electrode tab stack 27. The second insulator 71b may include a shorter portion 712 positioned adjacent to the second positive electrode tab stack 35 and a longer portion 711 positioned adjacent to the first positive electrode tab stack 33 or the third positive electrode tab stack 37.

[0138] The first insulator 71a and the second insulator 71b can have the same effects as the first insulator 70a and the second insulator 70b described above, such as improving mechanical stability and preventing (or at least mitigating) damage to the diaphragm 40.

[0139] Figure 9 This is a perspective view schematically illustrating a secondary battery according to another embodiment of the present disclosure.

[0140] refer to Figure 9 The secondary battery 100 according to an embodiment may include an electrode assembly 110, a negative electrode current collector 50 and a positive electrode current collector 55, a first current collector 61 and a second current collector 63, an insulator 71, and an insulating tape 80. When assembling or using the secondary battery 100, the insulating tape 80 may be attached to secure the electrode assembly 110, the negative electrode current collector 50 and the positive electrode current collector 55, and the insulator 71.

[0141] The insulating tape 80 can be attached to the top, bottom, left, and right sides of the electrode assembly 110 to cover the thickness of the electrode assembly 110. Furthermore, in embodiments where the negative electrode 20 and positive electrode 30 each have three terminal block stacks, when the upper portion of the electrode assembly 110 is secured with the insulating tape 80, the insulating tape 80 can be attached such that it begins from the front surface of the electrode assembly 110, passes through the front and upper portions of the first negative electrode current collector 51 to cover the rear surface of the electrode assembly 110, and / or begins from the front surface of the electrode assembly 100, passes through the front and upper portions of the first insulator 71a, and passes through the upper portion of the third negative electrode current collector 53 to cover the rear surface of the electrode assembly 110. In one or more embodiments, the insulating tape 80 can be attached in the same and / or symmetrical manner with respect to the positive electrode 30.

[0142] According to embodiments of this disclosure, an insulator is located between the current collector and the electrode assembly to distribute pressure on the electrode assembly, thereby preventing (or at least mitigating) damage to the separator and improving the structural stability of the secondary battery.

[0143] Furthermore, by soldering the current collector to a stack of multiple terminal blocks, charging / discharging and fast charging can be performed at high output.

[0144] However, the effects that can be achieved through this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the above description of the invention other technical effects not mentioned.

[0145] Therefore, this disclosure has been described with reference to the embodiments shown in the accompanying drawings; however, these are merely examples, and those skilled in the art will understand that various modifications and variations of the embodiments can be made therefrom. Thus, the true scope of the invention should be determined by the technical concept of the appended claims.

Claims

1. A secondary battery comprising: an electrode assembly including a plurality of negative electrodes each including a negative electrode tab and a plurality of positive electrodes arranged alternately with the plurality of negative electrodes and each including a positive electrode tab; a first current collector electrically connected to the negative electrodes; and a first insulator under the first current collector, wherein the negative electrode tabs of at least some of the plurality of negative electrodes overlap in a first position to form a first negative electrode tab stack, and the negative electrode tabs of some other of the plurality of negative electrodes overlap in a second position different from the first position to form a second negative electrode tab stack, and wherein the first insulator is adjacent to the first negative electrode tab stack and the second negative electrode tab stack.

2. The secondary battery of claim 1, wherein the first insulator includes a bottom portion and a wall portion connected to the bottom portion to define a recessed portion, and wherein the bottom portion includes a plurality of holes through the bottom portion.

3. The secondary battery of claim 1, wherein the first negative electrode tab stack and the second negative electrode tab stack do not overlap each other in a thickness direction of the electrode assembly.

4. The secondary battery of claim 1, wherein: the negative electrode tabs of some other of the plurality of negative electrodes form a third negative electrode tab stack different from the first negative electrode tab stack and the second negative electrode tab stack, and the first negative electrode tab stack, the second negative electrode tab stack, and the third negative electrode tab stack do not overlap each other in a thickness direction of the electrode assembly.

5. The secondary battery of claim 4, wherein the first insulator is adjacent to the first negative electrode tab stack, the second negative electrode tab stack, and the third negative electrode tab stack, and wherein the first insulator includes steps corresponding to the first negative electrode tab stack, the second negative electrode tab stack, and the third negative electrode tab stack in a plan view.

6. The secondary battery of claim 1, further comprising: a separator between each of the plurality of negative electrodes and each of the plurality of positive electrodes.

7. The secondary battery of claim 1, further comprising: a second current collector electrically connected to the plurality of positive electrodes; and a second insulator under the second current collector, wherein the positive electrode tabs of at least some of the plurality of positive electrodes overlap in a third position to form a first positive electrode tab stack, and wherein the positive electrode tabs of other of the plurality of positive electrodes overlap in a fourth position different from the third position to form a second positive electrode tab stack, and wherein the second insulator is adjacent to the first positive electrode tab stack and the second positive electrode tab stack. ​ ​ 8.The secondary battery of claim 7, wherein the first and second positive electrode tab stack are symmetrical with the first and second negative electrode tab stack. 9.The secondary battery of claim 7, wherein the second insulator has a shape identical to that of the first insulator. 10.The secondary battery of claim 1, further comprising: a negative electrode current collector plate between the first and second negative electrode tab stack and the first current collector, wherein the negative electrode current collector plate has a curved shape to cover a front portion and an upper portion of the first negative electrode tab stack and a front portion and an upper portion of the second negative electrode tab stack, wherein the negative electrode current collector plate is welded to the first and second negative electrode tab stack at the front portion of the first negative electrode tab stack and the front portion of the second negative electrode tab stack, and wherein the negative electrode current collector plate is welded to the first current collector on the upper portion of the first negative electrode tab stack and the upper portion of the second negative electrode tab stack. 11.A secondary battery comprising: an electrode assembly including a plurality of negative electrodes each including a negative electrode tab and a plurality of positive electrodes arranged alternately with the plurality of negative electrodes and each including a positive electrode tab; a first current collector electrically connected to the electrode assembly; and a first insulator under the first current collector, wherein the negative electrode tabs of the plurality of negative electrodes overlap each other to form a plurality of negative electrode tab stacks, wherein the plurality of negative electrode tab stacks are arranged at a plurality of positions in a direction perpendicular to a thickness direction of the electrode assembly and do not overlap each other, wherein the first insulator is adjacent to the plurality of negative electrode tab stacks, and wherein the first insulator includes a bottom portion and has a plurality of holes in the bottom portion. 12.The secondary battery of claim 11, wherein the first insulator further includes a wall portion connected to the bottom portion and defining a recessed portion. 13.The secondary battery of claim 11, wherein each of the plurality of holes has a honeycomb shape. 14.The secondary battery of claim 11, wherein the plurality of negative electrode tab stacks include three negative electrode tab stacks, and wherein the three negative electrode tab stacks do not overlap each other in the thickness direction of the electrode assembly. 15.The secondary battery of claim 14, wherein the first insulator is adjacent to the three negative electrode tab stacks and has steps corresponding to the three negative electrode tab stacks in a plan view. 16.The secondary battery of claim 11, further comprising a separator between each of the plurality of negative electrodes and each of the plurality of positive electrodes. 17.The secondary battery of claim 11, further comprising: ​ a second current collector electrically connected to the electrode assembly; and a second insulator under the second current collector, wherein positive electrode tabs of the plurality of positive electrodes overlap each other to form a plurality of positive electrode tab stacks, wherein the plurality of positive electrode tab stacks do not overlap in the thickness direction of the electrode assembly, and wherein the second insulator is adjacent to the plurality of positive electrode tab stacks. 18.The secondary battery of claim 17, wherein the plurality of positive electrode tab stacks are symmetrical with the plurality of negative electrode tab stacks. 19.The secondary battery of claim 17, wherein the second insulator has a shape identical to a shape of the first insulator. 20.The secondary battery of claim 11, further comprising: a negative electrode current collector plate welded to the plurality of negative electrode tab stacks, wherein the negative electrode current collector plate has a curved shape to cover a front portion and an upper portion of the plurality of negative electrode tab stacks, and wherein the negative electrode current collector plate is welded to the front portion of the plurality of negative electrode tab stacks and is welded to the first current collector on the upper portion of the plurality of negative electrode tab stacks.

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