Secondary battery having multilayer electrode assembly and method for manufacturing same

Abstract

The present disclosure relates to a secondary battery having a structure in which a plurality of electrode assemblies are laminated and a method of manufacturing the same, and a technical problem to be solved is to propose a secondary battery having a structure in which a plurality of electrode assemblies are laminated in a single battery case, it can be used as an optional solution in applications in which secondary battery products are arranged to form battery modules / batteries. To this end, the secondary battery includes: a case of the secondary battery; a plurality of electrode assemblies stacked in the vertical direction and accommodated in the case, and electrode tabs formed on the plurality of electrode assemblies; a current collector connected to each of the electrode tabs of the plurality of stacked electrode assemblies; and a cap plate coupled to the case and equipped with a terminal connected to the current collector.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a secondary battery, and more particularly, to a secondary battery having a structure in which a plurality of electrode assemblies are stacked, and a method of manufacturing the same. BACKGROUND

[0002] In general, a secondary battery includes an electrode assembly accommodated inside a case, a current collector connected to electrode tabs (a positive electrode tab and a negative electrode tab) of the electrode assembly, and a terminal connected to the current collector and exposed to the outside. The electrode assembly is manufactured by winding or stacking a positive electrode plate, a negative electrode plate, and a separator. The current collector is connected to the electrode tabs formed on the positive electrode plate and the negative electrode plate of the electrode assembly and electrically connected to the terminal.

[0003] As electric vehicles and energy storage systems (ESS) are developed, the capacity of a secondary battery is increasing, and in response thereto, the capacity of a secondary battery can be increased in the form of a module or a pack in which a plurality of secondary batteries are assembled. In addition, a secondary battery in the form of a high-type cell, which increases capacity and has a form in which a vertical length (height) is greater than a horizontal length, is also used.

[0004] The above-described information disclosed in this BACKGROUND section is for enhancing the understanding of the background of the present disclosure, and as such, it can include information that does not constitute the related (or prior) art. SUMMARY

[0005] [TECHNICAL PROBLEM]

[0006] The present disclosure aims to provide a secondary battery having a structure in which a plurality of electrode assemblies are stacked in a single battery case, which can be used as an alternative solution in applications in which secondary battery products are arranged to form a battery module / pack.

[0007] Aspects and features of the present disclosure are not limited to those described above, and other aspects and features that are not specifically mentioned will be clearly understood by those skilled in the art from the following description of the present disclosure.

[0008] [TECHNICAL SOLUTION]

[0009] One aspect of the present disclosure, which solves the above-described technical problem, provides a secondary battery including: a case of a secondary battery; a plurality of electrode assemblies stacked in a vertical direction and accommodated in the case, and electrode tabs formed on the plurality of electrode assemblies; a current collector connected to each of the electrode tabs of the plurality of stacked electrode assemblies; and a cover plate bonded to the case and assembled with a terminal connected to the current collector.

[0010] Another aspect of the present application, which solves the above-described technical problem, provides a method of manufacturing a secondary battery, the method including: preparing a plurality of electrode assemblies; manufacturing a case in which the plurality of electrode assemblies are accommodated; manufacturing a current collector configured to connect the plurality of electrode assemblies to a terminal; manufacturing a cover plate fitted with the current collector and the terminal; and vertically stacking the plurality of electrode assemblies, connecting the current collector to each of the plurality of electrode assemblies, and connecting the plurality of electrode assemblies to the terminal at the cover plate.

[0011] [Advantageous Effects]

[0012] According to the present disclosure, by stacking a plurality of electrode assemblies within a single battery case to form a secondary battery, it is possible to be compatible with existing electrode assemblies, and thus effects of process simplification, reduction in material management burden, and reduction in production cost can be achieved.

[0013] Furthermore, since the secondary battery can be used as an alternative in applications such as electric trucks, which have conventionally used modules / groups by stacking secondary batteries in two or more layers, the secondary battery can contribute to lightening, downsizing, and price reduction of the related applications.

[0014] Effects of the present disclosure are not limited to the above-mentioned aspects and features, and other effects not specifically mentioned will be clearly understood by those skilled in the art from the following description of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0015] The following accompanying drawings attached to the present specification illustrate embodiments of the present disclosure and together with the present specification further describe aspects and features of the present disclosure. Accordingly, the present disclosure should not be construed as being limited to the drawings, in which:

[0016] Figure 1 is a top perspective view illustrating a prismatic secondary battery;

[0017] Figure 2 is a cross-sectional view taken along line I-I' of FIG. 1, which illustrates an internal structure of the secondary battery having a side tab structure; Figure 1

[0018] Figure 3 is a cross-sectional view taken along line I-I' of FIG. 2, which illustrates an internal structure of the secondary battery having a top tab structure; Figure 1

[0019] Figure 4 is a view illustrating a secondary battery (a high-type monomer) having a vertical length greater than a horizontal length;

[0020] Figure 5 and Figure 6 is a schematic view illustrating a configuration of a secondary battery according to one embodiment of the present disclosure, in which, Figure 5 is a cross-sectional view illustrating an assembled state, and​​Figure 6 is an exploded view illustrating a secondary battery before being accommodated in a case;

[0021] Figure 7 is a cross-sectional view illustrating a secondary battery including a current collector in a modified form compared to Figure 5 and Figure 6 is an equivalent circuit of a secondary battery according to one embodiment of the disclosure, illustrated in

[0022] Figure 8 is a cross-sectional view illustrating an internal portion of a secondary battery according to another embodiment of the disclosure; Figure 5

[0023] Figure 9 is an equivalent circuit diagram of a secondary battery, illustrated in Figure 8

[0024] Figure 10 is a cross-sectional view illustrating an internal portion of a secondary battery additionally including a third layer electrode assembly according to another embodiment of the disclosure;

[0025] Figure 11 is an equivalent circuit diagram of a secondary battery according to the embodiment illustrated in Figure 10

[0026] Figure 12 and Figure 13 are cross-sectional and exploded views illustrating another embodiment of a secondary battery including a multi-layer electrode assembly according to the disclosure;

[0027] Figure 14 is an exemplary view of a secondary battery module in which a secondary battery manufactured according to an embodiment of the disclosure is disposed;

[0028] Figure 15 is an exemplary view illustrating a secondary battery pack including a secondary battery module, illustrated in Figure 14

[0029] Figure 16 is a conceptual view of a vehicle including a secondary battery pack of Figure 15 DETAILED DESCRIPTION

[0030] ​​​​​Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims are not limited to being interpreted in a narrow sense according to their general or dictionary meanings, but should be interpreted as having meanings and concepts consistent with the technical ideas of the present disclosure based on the principle that the inventor can become his / her own lexicon compiler to appropriately define the concepts of the terms to describe his / her invention in the best way. The embodiments described in this specification and the configurations shown in the drawings are only some embodiments of the present disclosure and do not represent all aspects, features and embodiments of the present disclosure. Accordingly, it should be understood that there may be various equivalents and modifications that can replace or modify one or more embodiments or features described herein when submitting this application.

[0031] It should be further understood that the term "comprises" and its variations used in this specification specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0032] In the drawings, the sizes of various elements, layers, etc. may be exaggerated for clarity of illustration. Like reference numerals designate like elements.

[0033] Referring to two compared elements, features, etc. as "the same" may mean that they are "substantially the same." Thus, the phrase "substantially the same" may include variations that are considered low in the art, for example, 5% or less. Additionally, uniformity of a parameter in a predetermined region may imply uniformity from an average perspective.

[0034] Although the terms first, second, etc. are used to describe various components, these components are not limited to these terms. These terms are only used to distinguish one component from another component, and unless otherwise stated, the first component may of course also be the second component.

[0035] Throughout the specification, unless specifically stated otherwise, each element may be in the singular or in the plural.

[0036] Arranging an arbitrary element “on (or below)” or “over (under)” another element may mean that the arbitrary element may contact the upper surface (or lower surface) of the element, and another element may also be interposed between the element and any element located above (or below) the element.

[0037] Further, it will be understood that if a component is referred to as being “coupled,” “coupled,” or “connected” to another component, the elements may be directly “coupled,” “coupled,” or “connected” to each other or another component may be “interposed” between the components.

[0038] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, if describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure." If expressions such as "at least one of" and "any of" precede / follow a list of elements, they modify the entire list of elements and do not modify the individual elements in the list.

[0039] Throughout the specification, unless stated otherwise, if "A and / or B" is stated, it means A, B, or A and B, and unless stated otherwise, if "C to D" is stated, it means C or greater and D or less.

[0040] When a phrase such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group of A, B, and C," or "at least one selected from among A, B, and C" is used to label a list of elements A, B, and C, the phrase may refer to any and all appropriate combinations or subsets of A, B, and C, such as A, B, C, A and B, A and C, B and C, or A, B, and C.

[0041] As used herein, the term "use" and variations thereof may be considered synonymous with the term "utilize" and variations thereof, respectively. As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values ​​that those skilled in the art will recognize.

[0042] It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the example embodiments, the first element, first component, first region, first layer or first part discussed below can be referred to as the second element, second component, second region, second layer or second part.

[0043] For ease of description, spatially relative terms such as "below," "beneath," "below," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It should be understood that in addition to the orientation depicted in the figures, the spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is turned over, an element described as being "below" or "beneath" another element or feature would then be oriented "above" or "on" the other element or feature. Thus, the term "below" can encompass both above and below orientations.

[0044] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0045] Figure 1 is a top perspective view illustrating the exterior of the secondary battery.

[0046] The case 51 forms the overall appearance of the secondary battery and may be formed of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. In addition, the case 51 may provide a space for accommodating the electrode assembly therein.

[0047] The cap assembly 60 may include a cap plate 61 covering the opening of the housing 51, and the housing 51 and the cap plate 61 may be made of a conductive material. Here, the first terminal 62 and the second terminal 63 may be electrically connected to the internal positive electrode plate or the negative electrode plate and may be installed to pass through the cap plate 61 and protrude outward from the cap plate 61.

[0048] An electrolyte inlet 64 may be formed in the cap plate 61, a sealing plug may be installed in the electrolyte inlet 64, and a vent 66 may be installed, in which a notch 65 is formed. The vent 66 is used to discharge gas generated inside the secondary battery.

[0049] Figure 2 is a diagram showing the interior of a secondary battery according to a form Figure 1 The secondary battery shown may include an electrode assembly 40 , a first current collector 41 , a first terminal 62 , a second current collector 42 , a second terminal 63 , and a cap assembly 60 .

[0050] The electrode assembly 40 can be formed in the form of a stack in which a first electrode plate, a separator, and a second electrode plate formed in a plate or film shape are wound or stacked. When the electrode assembly 40 is a wound type (referred to as a pole core), the winding axis can be parallel to the longitudinal direction of the shell. Alternatively, the electrode assembly 40 can be a stacked type instead of a wound type. However, in the present disclosure, the shape of the electrode assembly 40 is not limited thereto. In addition, the electrode assembly 40 can be a Z-stacked electrode assembly in which the first electrode plate and the second electrode plate are inserted on both sides of the separator bent into a Z shape. In addition, the electrode assembly 40 can be housed inside the shell by stacking the long sides of one or more electrode assemblies adjacent to each other, and the number of electrode assemblies is not limited in the present disclosure. The first electrode plate of the electrode assembly 40 can be used as a negative electrode, and the second electrode plate of the electrode assembly 40 can be used as a positive electrode, and vice versa.

[0051] The first electrode plate is formed by applying a first electrode active material such as graphite or carbon on a first electrode current collector (base plate) made of a metal foil such as copper, copper alloy, nickel, or nickel alloy, and can include a first electrode tab (or a first uncoated portion) which is a region where the first electrode active material is not applied. The first electrode tab 43 can be a passage for current flow between the first electrode plate and the first current collector 41. In some embodiments, the first electrode tab 43 can be formed by being cut in advance to protrude toward one side when the first electrode plate is manufactured, or can protrude further toward one side than the separator without separate cutting.

[0052] The second electrode plate is formed by applying a second electrode active material such as a transition metal oxide on a base plate made of a metal foil such as aluminum or aluminum alloy, and can include a second electrode tab 44 (or a second uncoated portion) which is a region where the second electrode active material is not applied. The second electrode tab 44 can be a passage for current flow between the second electrode plate and the second current collector 42. In some embodiments, the second electrode tab 44 can be formed by being cut in advance to protrude toward the other side when the second electrode plate is manufactured, and can protrude further toward the other side than the separator without separate cutting.

[0053] In some embodiments, the first electrode tab 43 can be located on a side surface of the right side of the electrode assembly 40, and the second electrode tab 44 can be located on a side surface of the left side of the electrode assembly 40 or on one surface in the same direction. Further, in some embodiments, the first electrode tab 43 and the second electrode tab 44 can be located at the upper portion of the electrode assembly 40.

[0054] Here, the left side, the right side, and the upper portion are described for convenience based on the secondary battery shown in FIG. 1, and the positions can vary when the secondary battery is rotated left and right or up and down. Figure 1

[0055] The separator serves to allow movement of lithium ions and prevent short circuiting between the first electrode plate and the second electrode plate. The separator can be made of, for example, a polyethylene film, a polypropylene film, a polyethylene polypropylene film.

[0056] The first electrode tab 43 of the first electrode plate and the second electrode tab 44 of the second electrode plate extend from both ends of the electrode assembly 40. In some embodiments, the electrode assembly 40 can be accommodated in the case 51 together with the electrolyte.

[0057] ​In the electrode assembly 40, the first and second electrode tabs 43 and 44 protruding toward both ends from the first and second electrode plates can be connected to the first and second current collectors 41 and 42, respectively, by welding. As described above, in some embodiments, when the first and second electrode tabs 43 and 44 are located at the upper portion of the electrode assembly 40, the first and second current collectors are located above the electrode assembly 40.

[0058] The first and second current collectors 41 and 42 can be connected to the first and second terminals 62 and 63, respectively, described in Figure 1 , through the connection members 67. In some embodiments, the outer surfaces of the connection members 67 can be threaded and fastened to the first and second terminals 62 and 63 by screw coupling. However, the present disclosure is not limited thereto, and the connection members 67 can be coupled to the first and second terminals 62 and 63 by riveting or welding.

[0059] As described above, in Figure 2 , the secondary battery has a structure in which the first and second electrode tabs 43 and 44 of the electrode assembly 40 are located on both sides of the secondary battery, and this structure is referred to as a side tab structure.

[0060] Figure 3 is an exemplary diagram illustrating a secondary battery having an internal structure different from that of Figure 2 . Figure 3 shows the following top tab structure in which the electrode assembly 40' is disposed to position the first and second electrode tabs 43' and 44' in the upper portion of the secondary battery.

[0061] In Figure 3 , the secondary battery having the top tab structure has a structure in which the first and second electrode tabs 43' and 44' of the electrode assembly 40' are located in the upper portion of the case 51', the first and second current collectors 41' and 42' are connected to the first and second electrode tabs 43' and 44', respectively, and the first and second terminals 62' and 63' connected to the current collectors 41' and 42', respectively, are mounted on the outer side of the cover plate 61'. The other components are similar to those of the secondary battery having the side tab structure shown in Figure 2 .

[0062] Figure 4 shows a secondary battery in a form in which the vertical length is greater than the horizontal length. A secondary battery having a relatively long vertical length in this way is also referred to as a "tall type monomer". Figure 4A high-type monomer having a top tab structure is schematically illustrated, in which the electrode tab 43' and the electrode tab 44" are located on the upper surface of the electrode assembly 40". Also, in the high-type monomer, the exhaust 66" can be installed at the bottom of the case 51" when the space is limited due to the short length of the cover plate 61", but the present disclosure is not limited thereto.

[0063] As shown in Figure 1 The high-type monomer can be alternatively used in applications (e.g., electric trucks, etc.) in which a "horizontal rectangular secondary battery" having a small length compared to a width is arranged in two or more layers to form a battery module / battery pack. However, because the vertical length of the internal electrode assembly increases in the high-type monomer, when the application-side tab structure is applied, there is a disadvantage in that the winding or stacking process of manufacturing the electrode assembly becomes more complicated, and the high-type monomer is difficult to be compatible with the electrode assembly for a horizontal rectangular battery. Also, when the top tab structure is applied to the high-type monomer, the utilization rate of the upper space of the battery can be reduced due to the electrode tabs, current collectors, and related members that should be located at the upper portion of the electrode assembly, and the battery capacity can be sacrificed.

[0064] Figure 5 And Figure 6 A configuration of a secondary battery according to one embodiment of the present disclosure is schematically illustrated. Figure 5 is a cross-sectional view illustrating a state in which the electrode assembly 200 and the electrode assembly 300, the related members, and the cover plate 130 are assembled with the case 100. Figure 6 shows a state in which a plurality of electrode assemblies 200 and 300 are erected and vertically stacked, and the current collector 110 and the current collector 120 are connected to the electrode tabs 210, 310, 220, and 320 formed on both sides of the electrode assembly 200 and the electrode assembly 300 and to the terminals 140 and 150 on the outer surface (upper surface) of the cover plate 130 (a state before being built into the case 100).

[0065] As shown in Figure 5 And Figure 6 According to one embodiment of the present disclosure, the first layer electrode assembly 200 and the second layer electrode assembly 300 can be erected and vertically stacked in the case 100, as shown in

[0066] As shown in the drawings, the secondary battery of the present embodiment can be implemented in a side tab structure. For example, the first layer electrode assembly 200 can be disposed such that the first electrode tab 210 and the second electrode tab 220 of the first layer electrode assembly 200 are located on both side surfaces of the case 100. Similarly, the second layer electrode assembly 300 can be disposed such that the first electrode tab 310 and the second electrode tab 320 are located on both side surfaces of the case 100.

[0067] The first and second terminals 140 and 150 may be assembled with the cap plate 130 coupled to the upper portion of the case 100 and may be electrically connected to the first and second current collectors 110 and 120 , respectively.

[0068] The first current collector 110 may be connected to the first electrode tab 210 of the first layer electrode assembly 200 and the first electrode tab 310 of the second layer electrode assembly 300, and the uppermost portion of the first current collector 100 may be connected to the first terminal 140. Similarly, the second current collector 120 may be connected to the second electrode tab 220 of the first layer electrode assembly 200 and the second electrode tab 320 of the second layer electrode assembly 300, and the uppermost portion of the second current collector 120 may be connected to the second terminal 150.

[0069] The insulator 170 may be interposed between the first layer electrode assembly 200 and the second layer electrode assembly 300. The insulator 170 may perform an insulating role to enhance electrical insulation between the first layer electrode assembly 200 and the second layer electrode assembly 300 and prevent mutual heat transfer.

[0070] In one embodiment, the secondary battery can be Figure 5 The secondary battery may be implemented in the form of a tall cell as shown in FIG, and the vent 160 may be located at the bottom of the housing 100. However, the secondary battery may be implemented in a form other than a tall cell (e.g., Figure 2 The secondary battery is implemented as a horizontal rectangular form and is implemented as a secondary battery having a vent 160, the vent 160 being located at the upper portion of the secondary battery (see FIG. Figure 12 ).

[0071] exist Figure 5 In the embodiment, because the first layer electrode assembly 200 and the second layer electrode assembly 300 stacked vertically are compatible with existing single-layer electrode assemblies, each of the electrode assembly 200 and the electrode assembly 300 can be manufactured using the same existing manufacturing equipment. Here, each of the electrode assembly 200 and the electrode assembly 300 can be a wound type (referred to as a core) electrode assembly of electrode plates (including a positive electrode, a separator, and a negative electrode), or can be a stacked type or Z-stacked type electrode assembly of electrode plates.

[0072] Figure 7 It is an icon Figure 5 and Figure 6 FIG. 2 is an equivalent circuit of a secondary battery according to an embodiment of the present disclosure shown in FIG.

[0073] First, assume that the basic line resistance of the first current collector 110 connecting the first terminal 140 to the first layer electrode assembly 200 and the second layer electrode assembly 300 is r 1,1and the base line resistance of the second terminal 150 to the second current collector 120 of the first layer electrode assembly 200 and the second layer electrode assembly 300 is r 2,1 .

[0074] In structure, because the first layer electrode assembly 200 and the second layer electrode assembly 300 are vertically stacked as shown in Figure 5 and Figure 6 , the length of the first current collector 110 and the second current collector 120 extends from the second layer to the first layer, so that an additional line resistance r 1,2 can be added to the base line resistance r 1,1 of the first current collector 100, and an additional line resistance r 2,2 can be added to the base line resistance r 2,1 of the second current collector 120. That is, the line resistance from the first current collector 110 and the second current collector 120 to the second layer electrode assembly 300 can be r 1,1 and r 2,1 , and the line resistance to the first layer electrode assembly 200 can be [r 1,1 + r 1,2 ] and [r 2,1 + r 2,2 ].

[0075] As such, because the length of the current collectors on both sides extends in the vertical direction, the line resistance of the electrode assembly 200 and the electrode assembly 300 can accumulate as the current path increases. This can cause resistance imbalance between the first layer electrode assembly 200 and the second layer electrode assembly 300, resulting in current density difference and attenuation between the electrode assemblies.

[0076] To solve these problems and maintain resistance balance between the upper electrode assembly and the lower electrode assembly, according to one embodiment, each electrode assembly can be manufactured so that the resistance of the first layer electrode assembly 200 is different from that of the second layer electrode assembly 300. For example, the electrode assembly can be manufactured so that the resistance of the first layer electrode assembly 200 is smaller than that of the second layer electrode assembly 300. However, in other embodiments, the plurality of electrode assemblies can have the same resistance.

[0077] According to another embodiment for maintaining a resistance balance between the upper electrode assembly and the lower electrode assembly, each of the electrode assembly 200 and the electrode assembly 300 may be manufactured such that the number of electrode plate jellyrolls or the number of layers of the second-layer electrode assembly 300 is different from the number of electrode plate jellyrolls or the number of stacks of the first-layer electrode assembly 200. For example, the capacity of the electrode assembly may be the same, but the resistance of the electrode assembly may be increased by reducing the number of electrode plate jellyrolls or the number of stacks of the upper second-layer electrode assembly 300, and the capacity of the electrode assembly may be the same, but the resistance of the electrode assembly may be reduced by increasing the number of electrode plate jellyrolls or the number of stacks of the lower first-layer electrode assembly 200.

[0078] According to another embodiment for maintaining resistance balance between the upper electrode assembly and the lower electrode assembly, the first electrode assembly 200 and the second electrode assembly 300 may use the same number of electrode plate jellyrolls or stacks, but the shape of the current collector may be modified. This embodiment is shown in FIG. Figure 8 middle.

[0079] and Figure 5 Compared with the implementation method, Figure 8 The secondary battery shown in FIG has a modified current collector shape. Specifically, the first current collector connecting the first terminal 140 to the first electrode assembly 200 and the second electrode assembly 300 may include: a main line 114 connected to the first terminal 140; a first branch line 112 branching from one end of the main line 114 and connected to the first electrode tab 310 of the second electrode assembly 300; and a second branch line 113 branching from one end of the main line 114 and connected to the first electrode tab 210 of the first electrode assembly 200. The point where the first branch line 112 and the second branch line 113 branch from the main line 114 is shown as a branch point 116.

[0080] Specifically, the second current collector connecting the second terminal 150 to the first layer electrode assembly 200 and the second layer electrode assembly 300 may include: a main line 124 connected to the second terminal 100; a first branch line 122 branching from one end of the main line 124 and connected to the second electrode tab 320 of the second layer electrode assembly 300; and a second branch line 123 branching from one end of the main line 124 and connected to the second electrode tab 220 of the first layer electrode assembly 200. The points at which the first branch line 122 and the second branch line 123 branch from the main line 124 are shown as branch points 126.

[0081] Despite Figure 8 The structures of the first current collector and the second current collector have been conceptually described in detail, but in actual implementations, a structure may be designed in which the space occupied by these current collectors in the case is minimized.

[0082] Figure 9 is a secondary battery to which the same first current collector and second current collector as the structure shown in Figure 8 is an equivalent circuit diagram of a secondary battery to which the same first current collector and second current collector as the structure shown in

[0083] Because the first branch line 112 and the second branch line 113 branch from the main line 114 connected to the first terminal 140 at the same length, only the basic line resistance r 1,1 In the branch lines 112 and 113 connected to the first electrode assembly 200 and the second electrode assembly 300, respectively, only the individual line resistance can exist, but there is no line resistance imbalance between the first electrode assembly 200 and the second electrode assembly 300.

[0084] In addition, on the opposite side, because the first branch line 122 and the second branch line 123 branch from the main line 124 connected to the second terminal 150 at the same length, only the basic line resistance r 2,1 In the branch lines 122 and 123 connected to the first electrode assembly 200 and the second electrode assembly 300, respectively, only the individual line resistance can exist, but there is no line resistance imbalance between the first electrode assembly 200 and the second electrode assembly 300.

[0085] Figure 10 is a cross-sectional view illustrating the inside of a secondary battery additionally including a third electrode assembly according to another embodiment of the disclosure. The third electrode assembly 400 is additionally stacked on the above-described first electrode assembly 200 and the second electrode assembly 300.

[0086] The first current collector 110 can be connected to the first electrode tab 210 of the first electrode assembly 200, the first electrode tab 310 of the second electrode assembly 300, and the first electrode tab 410 of the third electrode assembly 400, and the uppermost part of the first current collector can be connected to the first terminal 140. Similarly, the second current collector 120 can be connected to the second electrode tab 220 of the first electrode assembly 200, the second electrode tab 320 of the second electrode assembly 300, and the second electrode tab 420 of the third electrode assembly 400, and the uppermost part of the second current collector 120 can be connected to the second terminal 150.

[0087] The insulator 170 can be interposed between the first electrode assembly 200 and the second electrode assembly 300, and the insulator 172 can be interposed between the second electrode assembly 300 and the third electrode assembly 400. As described above, these insulators 170 and 172 serve for electrical and thermal insulation between the electrode assemblies 200, 300, and 400.

[0088] Figure 11is a cross-sectional view illustrating a secondary battery according to Figure 10 is an equivalent circuit diagram of the secondary battery according to the embodiment shown in FIG. 1.

[0089] Because the first, second, and third layer electrode assemblies 200 are stacked in the vertical direction, the lengths of the first and second current collectors 110 and 120 extend from the third layer to the first layer. Accordingly, additional line resistances r 1,2 and r 1,3 may be added to the base line resistance r 1,1 of the first current collector 110, and additional line resistances r 2,2 and r 2,3 may be added to the base line resistance r 2,1 of the second current collector 120.

[0090] As described above, as a method of solving the resistance imbalance problem between the electrode assemblies 200, 300, and 400 due to the accumulation of line resistance caused by the increase in the lengths of the two current collectors on both sides, each of the electrode assemblies 200, 300, and 400 can be manufactured such that the number of electrode plate winders or stacks of the third layer electrode assembly 400 is different from the number of electrode plate winders or stacks of the second layer electrode assembly 300 and the number of electrode plate winders or stacks of the first layer electrode assembly 200. For example, by increasing the number of electrode plate winders or stacks from the upper layer toward the lower layer, the resistance can be reduced while maintaining the same capacity. That is, [the number of electrode plate winders or stacks of the third layer electrode assembly 400] < [the number of electrode plate winders or stacks of the second layer electrode assembly 400] < [the number of electrode plate winders or stacks of the first layer electrode assembly 400] is satisfied.

[0091] Figure 12 and Figure 13 is a cross-sectional view illustrating yet another embodiment of a secondary battery according to the present disclosure including a multi-layer electrode assembly.

[0092] This embodiment shows that the spirit of the present disclosure is implemented in a horizontal rectangular secondary battery (see Figure 1 and Figure 2 ), rather than in the above-described high-type monomer-type secondary battery (see Figure 4 , Figure 5 and Figure 6 ).

[0093] The second layer electrode assembly 300' is stacked on the first layer electrode assembly 200' in the form of a jellyroll, electrode plates are wound on the jellyroll, and the insulator 170' can be interposed between the second layer electrode assembly 300' and the first layer electrode assembly 200'.

[0094] The first current collector 110' may be connected to the first electrode tab 210' of the first layer electrode assembly 200 and the first electrode tab 310' of the second layer electrode assembly 300, and the uppermost portion of the first current collector 100' may be connected to the first terminal 140'. In addition, the second current collector 120' may be connected to the second electrode tab 220' of the first layer electrode assembly 200' and the second electrode tab 320 of the second layer electrode assembly 300', and the uppermost portion of the second current collector 120' may be connected to the second terminal 150'.

[0095] In this embodiment, Figure 5 Different from the high-type monomer type, it can be seen that the exhaust member 160' is installed in the upper cover plate 130'.

[0096] Even in the present embodiment, a resistance imbalance problem may occur due to the extension of the length of the current collector 110' and the current collector 120', and measures for the resistance imbalance problem are similar to the above-mentioned measures. That is, each of the electrode assembly 200' and the electrode assembly 300' can be manufactured so that the number of electrode plate windings of the second layer electrode assembly 300' is different from the number of electrode plate windings of the second layer battery assembly 200'. For example, the capacity of the electrode assembly can be the same, but the resistance of the electrode assembly can be increased by reducing the number of electrode plate windings of the upper second layer electrode assembly 300', and the capacity of the electrode assembly can be the same, but the resistance of the electrode assembly can be reduced by increasing the number of electrode plate windings of the lower first layer electrode assembly 200'. In addition, as Figure 8 As shown in FIG, the first layer electrode assembly 200 ′ and the second layer electrode assembly 300 ′ having the same number of windings may be used, and the shape of the current collector may be modified.

[0097] The above embodiments are examples of a two-layer stack of two electrode assemblies and a three-layer stack of three electrode assemblies, but the spirit of the present disclosure can be generalized to stack N layers of two or more electrode assemblies of any number N. Those skilled in the art can easily form an N-layer stacking structure of N electrode assemblies and the structures of current collectors and related components based on the N-layer stacking structure.

[0098] Now, a method for manufacturing a secondary battery according to the present disclosure will be described. As described above, the method for manufacturing a secondary battery according to the present disclosure can be easily inferred from the secondary battery structure in which N electrode assemblies are vertically stacked in N layers inside a housing. Therefore, the following description of the manufacturing method will be briefly made with reference to the previously described drawings and related content.

[0099] The method of manufacturing a secondary battery of the present disclosure can include preparing a plurality of electrode assemblies including electrode tabs, manufacturing a case in which the plurality of electrode assemblies are accommodated, manufacturing a current collector connected to the electrode tabs of the plurality of electrode assemblies and configured to connect the electrode tabs to terminals, manufacturing a cover plate fitted with the current collector and the terminals, stacking the plurality of electrode assemblies in a vertical direction, connecting the current collector to the electrode tabs, connecting the plurality of electrode assemblies to the terminals on the cover plate, accommodating the vertically stacked electrode assemblies and the current collector in the case, and coupling the cover plate to the case.

[0100] Each operation will be described.

[0101] In the preparation of the plurality of electrode assemblies, the electrode assemblies can be manufactured as jelly-roll type (polar core), stacked type, or Z-stacked type electrode assemblies. The electrode tabs of the electrode assemblies can be formed to provide a secondary battery having a side tab structure, but the present disclosure is not limited thereto.

[0102] The electrode assemblies can be manufactured such that the capacities of the plurality of electrode assemblies are the same, but the present disclosure is not limited thereto. The resistances of the electrode assemblies can be different for each electrode assembly. For example, the electrode assemblies can be manufactured such that the resistance of the electrode assembly located at a lower layer is smaller than the resistance of the electrode assembly located at an upper layer. However, in other embodiments, the resistances of the plurality of electrode assemblies can be the same. The number of electrode plate winding bodies or stacks in the electrode assemblies can be different for each electrode assembly. For example, the number of electrode plate winding bodies or stacks of the electrode assembly located at the upper layer can be smaller than the number of electrode plate winding bodies or stacks of the electrode assembly located at the lower layer. However, in other embodiments, the number of electrode plate winding bodies or stacks of the plurality of electrode assemblies can be the same.

[0103] In the manufacturing of the case, the case can be a secondary battery case having an extended vertical length with respect to a horizontal length, referred to as a case for a high type monomer (see Figure 4 ), but the present disclosure is not limited thereto. For example, the case can be a case of a horizontal rectangular secondary battery as shown in Figure 2 (see Figure 12 and Figure 13 ).

[0104] In the manufacturing of the current collector, the current collector can be connected to the electrode tabs of the plurality of electrode assemblies to connect the corresponding electrode tabs to external terminals. The current collector can be formed as a pair of current collectors to be connected to the electrode tabs and can be manufactured to have an extended length corresponding to the vertical height of the multi-layer stacked electrode assemblies (see Figure 5 , Figure 6 and Figure 10 ) formed on both sides of the plurality of vertically stacked electrode assemblies. In other embodiments, as Figure 8As shown in FIG. 1, the current collector can include a main wire connected to the terminal, and branch wires branched from the main wire and connected to the electrode tabs of each electrode assembly.

[0105] In the manufacturing of the cover plate for assembling the current collector and the terminal, the cover plate can or can not include a vent (for example, in the case of a high type monomer). Also, a pouring inlet can be formed in the cover plate for pouring electrolyte into the cover plate after the cover plate is attached to the case.

[0106] In the vertical layering of the plurality of electrode assemblies, the connection of the current collector to the electrode tabs, and the connection of the plurality of electrode assemblies to the terminal on the cover plate, among the surfaces of the cover plate, the current collector can be located on a surface of the cover plate facing the inside of the case, and the terminal can be located on an outer surface of the cover plate (see FIG. 1, understanding the connection relationship between the electrode tabs of the electrode assembly, the current collector, the terminal, and the cover plate). Figure 5 、 Figure 6 and Figure 12 When the electrode assemblies are layered, an insulator can be interposed between the electrode assemblies.

[0107] Hereinafter, appropriate materials that can be used for the secondary battery according to the embodiments of the disclosure will be described.

[0108] As the positive electrode active material, a compound capable of reversibly intercalating / deintercalating lithium (for example, a lithiated intercalation compound) can be used. For example, at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0109] The composite oxide can be a lithium transition metal composite oxide, and examples thereof can include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel manganese-based oxide, or combinations thereof.

[0110] As an example, a compound represented by any one of the following formulas can be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, O≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2);Li a FePO4(0.90≤a≤1.8).

[0111] In the above formula: A is Ni, Co, Mn or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; and L 1 It is Mn, Al or a combination thereof.

[0112] A positive electrode for a lithium secondary battery may include a substrate and a positive electrode active material layer formed on the substrate. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0113] The content of the positive electrode active material is in the range of about 90 wt% to about 99.5 wt% based on 100 wt% of the positive electrode active material layer, and the content of the binder and the conductive material is in the range of about 0.5 wt% to about 5 wt% based on 100 wt% of the positive electrode active material layer, respectively.

[0114] The substrate can be aluminum (Al), but is not limited thereto.

[0115] The negative electrode active material can include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, lithium metal alloy, a material capable of doping and undoping lithium, or a transition metal oxide.

[0116] The material capable of reversibly intercalating / deintercalating lithium ions can be a carbon-based negative electrode active material, which can include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon can include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon can include soft carbon, hard carbon, pitch carbide, meso-phase pitch carbide, sintered coke, etc.

[0117] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used as the material capable of doping and undoping lithium. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-based alloy, or a combination thereof.

[0118] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0119] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core including crystalline carbon and silicon particles, and an amorphous carbon coating layer on the surface of the core.

[0120] The negative electrode for a lithium secondary battery can include a substrate and a negative electrode active material layer disposed on the substrate. The negative electrode active material layer can include a negative electrode active material, and can further include a binder and / or a conductive material.

[0121] For example, the negative electrode active material layer can include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0122] A non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof can be used as the binder. When the aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity can be further included.

[0123] As the negative electrode substrate, one selected from a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a conductive metal coated polymer substrate, and a combination thereof can be used.

[0124] The electrolyte for the lithium secondary battery can include a non-aqueous organic solvent and a lithium salt.

[0125] The non-aqueous organic solvent serves as a medium through which ions participating in the electrochemical reaction of the battery can move.

[0126] The non-aqueous organic solvent can be a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and can be used alone or in a combination of two or more.

[0127] Further, when a carbonate-based solvent is used, a mixture of a cyclic carbonate and a chain carbonate can be used.

[0128] Depending on the type of the lithium secondary battery, a separator can be present between the first electrode plate (e.g., negative electrode) and the second electrode plate (e.g., positive electrode). As the separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multi-layer film including two or more layers thereof can be used.

[0129] The separator can include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof on one or both surfaces of the porous substrate.

[0130] The organic material can include a polyvinylidene fluoride-based polymer or a (meth)acrylic acid polymer.

[0131] The inorganic material can include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and a combination thereof, but is not limited thereto.

[0132] The organic material and the inorganic material can be mixed in one coating layer, or can be in the form of a coating layer including (or containing) the organic material and a coating layer including (or containing) the inorganic material stacked with each other.

[0133] Figure 14 is an exemplary view of a secondary battery module in which a secondary battery manufactured according to the manufacturing method according to the disclosure is disposed. According to an increase in capacity of a secondary battery for driving an electric vehicle, a secondary battery module is manufactured by arranging and connecting a plurality of secondary battery cells in a lateral and / or vertical direction. A plurality of secondary batteries can be arranged in a space formed by a pair of end plates 71a and 71b facing each other and a pair of side plates 72a and 72b facing each other. The arrangement of the secondary batteries can be designed to achieve a desired voltage and current specification.

[0134] Figure 15 is illustrated as being formed by applying the prismatic secondary battery module shown in Figure 14 An example of a secondary battery pack 80 formed by applying the prismatic secondary battery module shown in FIG. 1 to an actual product (e.g., a vehicle) can be manufactured by housing a plurality of secondary battery modules into a battery pack housing designed to be installed in an actual product. The battery pack housing can include fasteners and power outlets required to be installed in a product. In Figure 11 In FIG. 1, for convenience of illustration, relevant elements such as bus bars for electrical connection of the secondary batteries, a cooling unit, and external terminals are omitted.

[0135] The secondary battery pack can be installed in a vehicle. The vehicle can be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle can be a four-wheel drive or a two-wheel drive vehicle. Figure 16 is a diagram for describing a vehicle including the secondary battery pack shown in Figure 15 In FIG. 1, for convenience of illustration, relevant elements such as bus bars for electrical connection of the secondary batteries, a cooling unit, and external terminals are omitted. Figure 16 A secondary battery pack 80 installed at a lower portion of a vehicle body of a vehicle V according to an embodiment of the present disclosure is illustrated. The vehicle V is operated by receiving electric power from the secondary battery pack 80 according to an embodiment of the present disclosure.

[0136] Although the present disclosure has been described above with respect to embodiments thereof, the present disclosure is not limited thereto. Various modifications and changes can be made thereto by those skilled in the art which fall in the spirit of the present disclosure as defined by the appended claims and their equivalents.

[0137] <Description of Reference Numerals>

[0138] 40, 40' and 40": electrode assembly, 41 and 41': first current collector, 42 and 42': second current collector, 43, 43' and 43": first electrode tab, 44, 44' and 44": second electrode tab, 50: lid assembly, 51, 51' and 51": housing, 60: lid assembly, 61, 61' and 61": lid plate, 62 and 62': first terminal, 63 and 63': second terminal, 64: electrolyte inlet, 65: notch, 66 and 66": exhaust member, 67: connecting member, 71a and 71b: end plate, 72a and 72b: side plate, 80: secondary battery pack, 100: housing, 110 and 110': first current collector, 112: first branch line, 113: second branch line, 114: main line, 116: branch point, 120 and 120': second current collector, 122: first branch line, 113: second branch line, 124: main line, 126: branch point, 130 and 130': lid plate, 140 and 140': first terminal, 150 and 150': second terminal, 160 and 160': exhaust member, 170, 170' and 172: insulator, 200 and 200': first layer electrode assembly, 210 and 210': first electrode tab, 220 and 220': second electrode tab, 300 and 300': second layer electrode assembly, 310 and 310': first electrode tab, 320 and 320': second electrode tab, 400: third layer electrode assembly, 410: first electrode tab, 420: second electrode tab, r 1,1 : basic line resistance of first current collector 110, r 1,2 : additional line resistance of first current collector 110, r 1,3 : additional line resistance of first current collector 110, r 2,1 : basic line resistance of second current collector 120, r 2,2 : additional line resistance of second current collector 120, r 2,3 : additional line resistance of second current collector 120, V: vehicle.

Claims

1. A secondary battery comprising: a case of a secondary battery; a plurality of electrode assemblies stacked in a vertical direction and accommodated in the case, and electrode tabs formed on the plurality of electrode assemblies; a current collector connected to each of the electrode tabs of the plurality of stacked electrode assemblies; and a cover plate coupled to the case and fitted with a terminal connected to the current collector. The electrode assembly is one of a jelly-roll type, a stacked type, and a Z-stacked type electrode assembly.

2. The secondary battery according to claim 1, wherein The plurality of electrode assemblies include electrode assemblies having the same capacity.

3. The secondary battery according to claim 1, wherein The plurality of electrode assemblies include electrode assemblies having different resistances.

4. The secondary battery according to claim 1, wherein The resistance of the electrode assembly located at a lower layer is less than the resistance of the electrode assembly located at an upper layer.

5. The secondary battery according to claim 4, wherein The plurality of electrode assemblies include electrode assemblies having different numbers of one of electrode plate jelly-rolls and stacked bodies.

6. The secondary battery according to claim 1, wherein Among the plurality of electrode assemblies, the number of one of the electrode plate jelly-rolls and the stacked bodies of the electrode assembly located at the upper layer is less than the number of one of the electrode plate jelly-rolls and the stacked bodies of the electrode assembly located at the lower layer.

7. The secondary battery according to claim 6, wherein The current collector is connected to the electrode tabs formed on the plurality of electrode assemblies stacked in the vertical direction and extends in the vertical direction.

8. The secondary battery according to claim 1, wherein The current collector includes:

9. The secondary battery according to claim 1, wherein a main line connected to the terminal fitted with the cover plate; and a plurality of branch lines branched from the main line and connected one-to-one to the electrode tabs of the plurality of electrode assemblies. An insulator is located between the electrode assemblies stacked in the vertical direction.

10. The secondary battery of claim 1, further comprising: 11.A method of manufacturing a secondary battery, comprising: preparing a plurality of electrode assemblies; manufacturing a case in which the plurality of electrode assemblies are accommodated; manufacturing a current collector configured to connect the plurality of electrode assemblies to a terminal; manufacturing a cover plate fitted with the current collector and the terminal; and stacking the plurality of electrode assemblies in a vertical direction, connecting the current collector to each of the plurality of electrode assemblies, and connecting the plurality of electrode assemblies to the terminal at the cover plate. The preparing of the plurality of electrode assemblies includes manufacturing one of a jelly-roll type, a stacked type, and a Z-stacked type electrode assembly. The preparing of the plurality of electrode assemblies includes manufacturing electrode assemblies having the same capacity.

12. The method of claim 11, wherein, The preparing of the plurality of electrode assemblies includes manufacturing electrode assemblies having different resistances.

13. The method of claim 11, wherein, The resistance of the electrode assembly located at a lower layer is less than the resistance of the electrode assembly located at an upper layer.

14. The method of claim 11, wherein, The preparing of the plurality of electrode assemblies includes manufacturing electrode assemblies having different numbers of one of electrode plate jelly-rolls and stacked bodies.

15. The method of claim 14, wherein, The number of one of the electrode plate jelly-rolls and the stacked bodies of the electrode assembly located at the upper layer is less than the number of one of the electrode plate jelly-rolls and the stacked bodies of the electrode assembly located at the lower layer.

16. The method of claim 1, wherein, The manufacturing of the current collector includes manufacturing a current collector connected to electrode tabs formed on the plurality of electrode assemblies stacked in the vertical direction and extending in the vertical direction.

17. The method of claim 16, wherein, ​ 18. The method of claim 11, wherein, ​ 19. The method of claim 11, wherein, The manufacturing of the current collector includes manufacturing a main wire connected to the terminal assembled with the cover plate and a plurality of branch wires branched from the main wire and connected to the electrode tabs of the plurality of electrode assemblies.

20. The method of claim 11, further comprising: An insulator is provided between the electrode assemblies stacked in the vertical direction.

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