Secondary battery

Abstract

The present disclosure relates to a secondary battery, which is entirely made of a multi-layer metal thin film to increase a total cross-sectional area, thereby improving a heat generation performance and facilitating bending. In an example, a secondary battery is disclosed, including: an electrode assembly having first and second electrode tabs exposed to both sides, respectively; a first current collector coupled to the first electrode tab of the electrode assembly; a case accommodating the electrode assembly and the first current collector and having both sides open; a first cover sealing an opening of one side of the case; and a first terminal coupled to the first current collector and exposed to an outside of the first cover, wherein the first current collector includes a first main plate in which a multi-layer metal thin film is overlapped and first sub-plates surrounding both ends of the first main plate in a longitudinal direction, respectively.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0178555, filed on December 14, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Some aspects of embodiments of this disclosure relate to secondary batteries. Background Technology

[0004] A secondary battery is an electrical storage system that provides relatively high energy density for storing electrical energy in the form of chemical energy. Unlike non-rechargeable primary batteries, secondary batteries are rechargeable and widely used in electronic devices such as smartphones, mobile phones, laptops, and tablet computers (e.g., portable electronic devices). Recently, with the increasing interest in electric vehicles to prevent or reduce environmental pollution, high-capacity secondary batteries are being adopted for use in electric vehicles. These secondary batteries typically possess characteristics such as relatively high energy density, relatively high output, and relatively high stability.

[0005] The information disclosed in this background section is only intended to enhance the understanding of the background of this invention, and therefore may contain information that does not constitute prior art. Summary of the Invention

[0006] Some aspects of embodiments of this disclosure include a secondary battery made entirely of multilayer metal films to increase the total cross-sectional area, thereby improving thermal performance and facilitating bending.

[0007] Furthermore, embodiments of this disclosure include a secondary battery that can prevent or reduce damage during soldering by wrapping the area of ​​the current collector connected to the terminals and electrode assembly with a metal thicker than the metal film.

[0008] These and other aspects and features of embodiments of this disclosure will be described in more detail, or will become apparent from the following description of some embodiments of this disclosure.

[0009] A secondary battery according to some embodiments of the disclosure can include an electrode assembly having first and second electrode tabs exposed to both sides, respectively; a first current collector coupled to the first electrode tab of the electrode assembly; a case accommodating the electrode assembly and the first current collector and having both sides open; a first cover sealing an opening of one side of the case; and a first terminal coupled to the first current collector and exposed to an outside of the first cover, wherein the first current collector includes a first main plate in which a plurality of metal thin films are overlapped and first sub-plates surrounding both ends of the first main plate in a longitudinal direction, respectively.

[0010] According to some embodiments, in the first current collector, the first sub-plate of one side can contact and be welded to the first electrode tab, and the first sub-plate of the other side can contact and be welded to the first terminal.

[0011] According to some embodiments, the first current collector can include a connection portion formed of the first main plate; a first tab coupling portion extending outward from one end of the connection portion, including the first main plate and the first sub-plate surrounding the first main plate, and coupled to the first electrode tab; and a first terminal coupling portion extending outward from the other end of the connection portion, including the first main plate and the first sub-plate surrounding the first main plate, and coupled to the first terminal.

[0012] According to some embodiments, in the first current collector, a surface on which the first tab coupling portion contacts and is welded to the first electrode tab and a surface on which the first terminal coupling portion contacts and is welded to the first terminal can be the same, and the connection portion can be bent at least once.

[0013] According to some embodiments, a thickness of the first sub-plate can be 2 to 5 times a thickness of the metal thin film of the first main plate.

[0014] According to some embodiments, the first main plate can be compressed in a state in which 4 to 10 metal thin films of 0.05 mm to 0.2 mm are overlapped.

[0015] According to some embodiments, the first terminal can include a first inner terminal plate located inside the first cover, a first outer terminal plate located outside the first cover, and a first terminal post coupled to the first inner terminal plate from the inside of the first cover, passing through the first cover, and coupled to the first outer terminal plate from the outside of the first cover.

[0016] According to some embodiments, in the first current collector, the first sub-plate can be coupled to one surface of the first inner terminal plate by welding.

[0017] According to some embodiments, the secondary battery can further include a second current collector coupled to the second electrode tab of the electrode assembly, a second cover sealing an opening of the other side of the case, and a second terminal coupled to the second current collector and exposed to the outside of the second cover.

[0018] According to some embodiments, the second current collector can include a second main plate in which a plurality of metal thin films are overlapped and second sub-plates respectively surrounding both ends of the second main plate in a longitudinal direction.

[0019] According to some embodiments, the thickness of the first sub-plate can be 0.1 mm or more. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a perspective view illustrating a secondary battery according to some embodiments of the disclosure.

[0021] Figure 2 is a cross-sectional view taken along line 2-2' in the secondary battery of Figure 1

[0022] Figure 3 is a perspective view illustrating a current collecting portion in the secondary battery of Figure 1

[0023] Figure 4 is a magnified cross-sectional view of part 4 in Figure 3 DETAILED DESCRIPTION

[0024] Hereinafter, aspects of some embodiments of the disclosure will be described in greater detail with reference to the accompanying drawings.

[0025] Aspects of some embodiments of the disclosure are provided to more completely explain the features of embodiments of the disclosure according to the present disclosure to a person skilled in the art, and the following examples can be modified in various other forms. However, the disclosure can be implemented in many different forms, and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that the disclosure will be thorough and complete, and will convey the aspects and features of the disclosure to a person skilled in the art.

[0026] Further, in the drawings, the size or thickness of various components can be exaggerated for clarity and convenience. The same reference numbers are used throughout the drawings to refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, it will be understood that when an element A is referred to as being "connected to" an element B, element A can be directly connected to element B or an intervening element C can be present between them such that element A and element B are indirectly connected to each other. ​​​

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when 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.

[0028] It will be understood that, although the terms first, second, etc. can be used herein to describe various elements, regions, layers and / or sections, these elements, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, region, layer and / or section from another element, region, layer and / or section. Thus, a first element, region, layer and / or section discussed below could be termed a second element, region, layer and / or section without departing from the teachings of the present disclosure.

[0029] For ease of description, spatial relative terms, such as "beneath", "below", "lower", "above", "upper" and the like, can be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the term "below" can encompass both an orientation of above and below. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative terms used herein interpreted accordingly.

[0030] Aspects of some embodiments of the present disclosure will now be described in more detail, by way of example only, with reference to the attached drawings, wherein:

[0031] Herein, throughout the specification, components having similar configurations and operations are given the same reference numerals. Also, it will be understood that when a part is referred to as being electrically coupled to another part, this includes not only the case where it is directly connected thereto, but also the case where it is connected thereto with another element interposed therebetween.

[0032] Referring to Figure 1 , a perspective view illustrating a secondary battery according to some embodiments of the present disclosure is shown. Referring to Figure 2 , a cross-sectional view taken along line 2-2' in the secondary battery of Figure 1 is shown.

[0033] As Figure 1 and Figure 2As illustrated, the secondary battery 100 can include an electrode assembly 110, a first current collector 120, a first terminal 130, a second current collector 140, a second terminal 150, a case 160, a first cover assembly 170, and a second cover assembly 180.

[0034] The electrode assembly 110 can be formed by winding or stacking a stack of a first electrode plate 111, a separator 113, and a second electrode plate 112 formed in a sheet or film form. When the electrode assembly 110 is a wound laminate, a winding axis can be parallel to a longitudinal direction of the case 160 (e.g., a direction in which the longest side extends) (i.e., a direction perpendicular to a longitudinal direction of the first cover assembly 170 and the second cover assembly 180). Alternatively, the electrode assembly 110 can be a stack type rather than a wound type, and embodiments according to the present disclosure are not limited to the shape of the electrode assembly 110 exemplified in Figure 1 and Figure 2 In addition, the electrode assembly 110 can be accommodated in the case 160 by stacking a plurality of electrode assemblies 110 such that their long sides are adjacent to each other, and embodiments according to the present disclosure are not limited to the number of electrode assemblies 110.

[0035] The first electrode plate 111 of the electrode assembly 110 can serve as a negative electrode, and the second electrode plate 112 can serve as a positive electrode. Of course, the reverse is also possible.

[0036] The first electrode plate 111 can be formed by coating a first electrode active material (such as graphite or carbon) on a first electrode current collector formed of a metal foil (such as copper, a copper alloy, nickel, or a nickel alloy), and can include a first electrode tab 111a (or a first uncoated portion) that is a region to which the first electrode active material is not applied. The first electrode tab 111a can serve as a current passage between the first electrode plate 111 and the first current collector 120. According to some embodiments, when the first electrode plate 111 is manufactured, the first electrode tab 111a can be formed by being cut in advance to protrude to one side, and can be integrally formed with the first electrode plate 111. According to some embodiments, a plurality of first electrode tabs 111a can be gathered and then coupled by spot welding. According to some embodiments, in the first electrode plate 111, the first electrode tab 111a of the first electrode plate 111 can protrude to one side more than the separator 113 without a separate cutting process. Here, a separate metal plate (electrode tab) can be coupled to the first electrode tab 111a of the first electrode plate 111 exposed to one side of the electrode assembly 110 by welding, or the first current collector 120 can be directly coupled to the first electrode tab 111a of the electrode assembly 110 by welding.

[0037] The second electrode plate 112 can be formed by coating a second electrode active material such as a transition metal oxide on a second electrode current collector formed of a metal foil such as aluminum or an aluminum alloy, and can include a second electrode tab 112a (or a second uncoated portion) which is a region to which the second electrode active material is not applied. The second electrode tab 112a can serve as a current passage between the second electrode plate 112 and the second current collector 140. According to some embodiments, when the second electrode plate 112 is manufactured, the second electrode tab 112a can be formed by being cut in advance to protrude to one side, and can be integrally formed with the second electrode plate 112. According to some embodiments, a plurality of second electrode tabs 112a can be gathered and then coupled by spot welding, and a separate metal plate that can serve as an electrode tab can be welded and coupled to the spot-welded second electrode tab 112a. According to some embodiments, in the second electrode plate 112, the second electrode tab 112a of the second electrode plate 112 can protrude more to the other side than the separator 113 without a separate cutting process. Here, a separate metal plate (electrode tab) can be coupled by welding to the second electrode tab 112a exposed to the other side of the electrode assembly 110, or the second current collector 140 can be directly coupled by welding to the second electrode tab 112a of the electrode assembly 110.

[0038] According to some embodiments, the first electrode tab 111a and the second electrode tab 112a can be respectively exposed to opposite sides of the electrode assembly 110. According to some embodiments, the first electrode tab 111a can be located on the left end side of the electrode assembly 110, and the second electrode tab 112a can be located on the right end side of the electrode assembly 110. Here, for ease of explanation, the left and right sides are designated based on the secondary battery 100 shown in FIGS. 1A and 1B, and the positions can change when the secondary battery 100 is rotated left and right or up and down. Figure 1 and Figure 2 According to some embodiments, the first electrode tab 111a and the second electrode tab 112a can be respectively exposed to opposite sides of the electrode assembly 110. According to some embodiments, the first electrode tab 111a can be located on the left end side of the electrode assembly 110, and the second electrode tab 112a can be located on the right end side of the electrode assembly 110. Here, for ease of explanation, the left and right sides are designated based on the secondary battery 100 shown in FIGS. 1A and 1B, and the positions can change when the secondary battery 100 is rotated left and right or up and down. Figure 1 and Figure 2 The various components will now be described in greater detail with respect to the secondary battery 100 shown in FIGS. 2A and 2B.

[0039] According to some embodiments, the separator 113 can be located between the first electrode plate 111 and the second electrode plate 112 to prevent or reduce the short-circuiting situation and enable the movement of lithium ions, and can include a polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. In addition, the separator 113 can be replaced with an inorganic solid electrolyte that does not require a liquid or gel electrolyte, such as a sulfide-based, oxide-based, or phosphate-based electrolyte.

[0040] The first and second current collectors 120 and 140, which are electrically connected to the first electrode tabs 111a of the first electrode plates 111 and the second electrode tabs 112a of the second electrode plates 112, respectively, can be located at both ends of the electrode assembly 110. According to some embodiments, the electrode assembly 110 can be accommodated together with an electrolyte in the case 160.

[0041] According to some embodiments, the electrolyte can include a lithium salt (such as LiPF6 or LiBF4) in an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). In addition, the electrolyte can be in a liquid or gel state. According to some embodiments, when an inorganic solid electrolyte is used, the electrolyte can be omitted.

[0042] The first current collector 120 can be formed of a metal and can electrically connect the first electrode plates 111 and the first terminal 130 to each other. Referring to Figure 3 , a perspective view of the first current collector 120 is shown before being connected between the first electrode plates 111 and the first terminal 130 in the secondary battery 100 of Figure 1 . Referring to Figure 4 , an enlarged view of four portions of the first current collector 120 is shown to illustrate Figure 3 . Hereinafter, the configuration of the first current collector 120 will be described in more detail with reference to Figure 3 and Figure 4 .

[0043] The first current collector 120 can include a first main plate 121 having a substantially rectangular plate shape with a plurality of metal thin films overlapped therein and first sub-plates 122 surrounding regions (for example, set or predetermined regions) of both ends of the first main plate 121 in a longitudinal direction, respectively.

[0044] The first main plate 121 can be formed by stacking or winding a plurality of first metal thin films 121z and then compressing. For example, the first main plate 121 can be formed by completely compressing a metal thin film of 0.05 mm to 0.2 mm in a state in which 4 to 10 metal thin films are overlapped. Here, it can be difficult to manufacture a metal thin film having a thickness of less than 0.05 mm, and when the thickness of the metal thin film exceeds 0.2 mm, the ductility of the first main plate 121 having a plurality of overlapped metal thin films can be deteriorated. In addition, when the first main plate 121 has less than four metal thin films overlapped with each other, the first current collector 120 can be broken or damaged due to a decrease in rigidity. In addition, when the first main plate 121 using more than 10 metal thin films is overlapped, the capacity of the secondary battery 100 can be decreased due to an unnecessary increase in volume of the first current collector 120.

[0045] Here, the first metal thin film 121z for forming the first main plate 121 can be made of copper or a copper alloy. The first main plate 121 can have a plurality of first metal thin films 121z overlapped, and thus have a thickness (e.g., a set or predetermined thickness). The first main plate 121 can include one flat surface 121x and another flat surface 121y opposite to the one surface 121x. Also, the first main plate 121 can have an outermost first metal thin film 121z located on each of the one surface 121x and the other surface 121y, and edges of the plurality of overlapped first metal thin films 121z can be exposed through four side surfaces connecting the one surface 121x and the other surface 121y.

[0046] The first sub plate 122 has a substantially rectangular plate shape, and can surround both sides of the first main plate 121 facing each other. That is, two first sub plates 122 can wrap a one-side region and another one-side region facing the one-side region, located at both ends of the first main plate 121 in a longitudinal direction, respectively. A lateral length of each of the first sub plates 122 can be equal to a lateral length of the first main plate 121. That is, each of the first sub plates 122 can cover both the one surface 121x and the other surface 121y in the one-side region of the first main plate 121, and can cover both the one surface 121x and the other surface 121y in the other one-side region. For example, when the first main plate 121 is of a type in which a plurality of first metal thin films 121z are wound, the first sub plate 122 can cover a side surface of the first main plate 121 that is rounded by the winding. In the first current collector 120, the first sub plate 122 on one side can contact and be welded to the first electrode tab 111a, and the first sub plate 122 on the other side can contact and be welded to the first terminal 130.

[0047] Each of the first sub plates 122 can include a first region 122a covering the one surface 121x of the first main plate 121, a second region 122b covering the other surface 121y of the first main plate 121, and a third region 122c connecting the first region 122a and the second region 122b. For example, the first region 122a and the second region 122b in the first sub plate 122 can have the same size, but the size can be changed in various ways without being limited thereto.

[0048] The first sub plate 122 can be attached and fixed to the one-side region and the other one-side region of the first main plate 121 by ultrasonic welding or resistance welding of the first region 122a and the second region 122b in a state in which the first main plate 121 is interposed between the first region 122a and the second region 122b. That is, the first sub plate 122 can be attached and fixed to the one-side region and the other one-side region of the first main plate 121 by welding, respectively.

[0049] The thickness of the first sub-plate 122 can be greater than the thickness of the one piece of the first metal thin film 121z included in the first main plate 121. For example, the thickness of the first sub-plate 122 can be 2 to 5 times the thickness of the first metal thin film 121z. Also, the thickness of the first sub-plate 122 can be 0.1 mm or more. Here, when the thickness of the first sub-plate 122 is less than twice the thickness of the first metal thin film 121z or less than 0.1 mm, damage can occur in the first sub-plate 122 or the first main plate 121 when the first sub-plate 122 or the first main plate 121 is coupled to the first electrode tab 111a and / or the first terminal 130 by welding. Also, when the thickness of the first sub-plate 122 is greater than 5 times the thickness of the first metal thin film 121z, the capacity of the secondary battery 100 having only the same area can be reduced due to unnecessary thickness increase.

[0050] The first current collector 120 can include a connection portion 120a constituted only of the first main plate 121, and a first tab coupling portion 120b and a first terminal coupling portion 120c extending outward from both ends of the connection portion 120a and constituted of the first main plate 121 and the first sub-plate 122 surrounding the first main plate 121. In other words, a region to which the first sub-plate 122 of the first main plate 121 is coupled can be referred to as the first tab coupling portion 120b. Also, another region to which the first sub-plate 122 of the first main plate 121 is coupled can be referred to as the first terminal coupling portion 120c.

[0051] In the first current collector 120, the first tab coupling portion 120b can be in contact with the first electrode tab 111a of the electrode assembly 110 and coupled to the first electrode tab 111a of the electrode assembly 110 by welding. Also, in the first current collector 120, the first terminal coupling portion 120c can be in contact with the first terminal 130 and coupled to the first terminal 130 by welding. Also, in the first current collector 120, a surface in contact with the first electrode tab 111a and a surface in contact with the first terminal 130 can be one and the same surface. Also, in the first current collector 120, the first tab coupling portion 120b and the first terminal coupling portion 120c on the other surface opposite the one surface can face each other. That is, the connection portion 120a of the first current collector 120 can be bent at least once.

[0052] In the first current collector 120, the connection portion 120a is composed of the first main plate 121 made of the multi-layer metal thin film 120z, and thus can be easily bent. Also, in the first current collector 120, the first tab coupling portion 120b and the first terminal coupling portion 120c are shaped such that the first main plate 121 made of the multi-layer metal thin film 120z is surrounded by the first sub plate 122, thereby preventing or reducing a case in which the multi-layer metal thin film 120z is damaged during welding. Also, in the first current collector 120, the first main plate 121 made of the multi-layer metal thin film 120z can increase the total cross-sectional area, thereby improving heat generation performance.

[0053] The first terminal 130 can be formed of metal, and can be electrically connected to the first current collector 120. According to some embodiments, the first terminal 130 can be coupled to the first current collector 120 and can be exposed to the outside of the first cover plate 171 which will be described below. According to some embodiments, the first terminal 130 can include a first inner terminal plate 131, a first terminal post 132, and a first outer terminal plate 133.

[0054] Here, the first inner terminal plate 131 can be located at the inside of the first cover plate 171, and the first outer terminal plate 133 can be located at the outside of the first cover plate 171. Of course, the first coupling member 172 can be further interposed between the first outer terminal plate 133 and the first cover plate 171. Also, the first gasket 173 can be further interposed between the first terminal post 132 and the first cover plate 171, and between the first inner terminal plate 131 and the first cover plate 171. Also, the first terminal post 132 can pass through the first cover plate 171 to be coupled to the first outer terminal plate 133 from the outside of the first cover plate 171, and to be coupled to the first inner terminal plate 131 from the inside of the first cover plate 171. In an embodiment, an insulating member can be provided between the left end side of the electrode assembly 110 and the inner surface of the first cover plate 171.

[0055] The first inner terminal plate 131 can be in contact with and coupled to the first terminal coupling portion 120c of the first current collector 120 on one surface located at the right side. The first inner terminal plate 131 can include a terminal hole 131a passing through between one surface and another surface. Of course, the terminal hole 131a can be formed to correspond to the diameter of the first terminal post 132.

[0056] The first terminal post 132 can be fitted and coupled to the terminal hole 131a of the first inner terminal plate 131. For example, the first terminal post 132 can be fixed on one surface while being inserted into the terminal hole 131a of the first inner terminal plate 131 by riveting and / or welding. The first terminal coupling portion 120c (e.g., the first sub plate 122) of the first current collector 120 can be coupled to one surface of the first inner terminal plate 131 coupled to the first terminal post 132 by welding.

[0057] The first terminal post 132 can have a columnar shape, and can protrude and extend to the outside of the first cover plate 171. Also, the first terminal post 132 can have a flange 132a formed at the outside of the first cover plate 171 to prevent or reduce a case in which the first terminal post 132 is detached from the first cover plate 171. The first terminal post 132 can be fitted and coupled to the terminal hole 133a of the first outer terminal plate 133 from the outside with respect to the first cover plate 171, and can be inserted and coupled to the terminal hole 131a of the first inner terminal plate 131 from the inside. Here, the flange 132a can be positioned between the first outer terminal plate 133 and the first cover plate 171.

[0058] The first outer terminal plate 133 can include a terminal hole 133a that penetrates between one surface and another surface. The outer extension of the first terminal post 132 can be inserted into the terminal hole 133a of the first outer terminal plate 133 to be coupled thereto. For example, the first terminal post 132 can be fixed on the other surface positioned on the left by riveting and / or welding while being inserted into the terminal hole 133a of the first outer terminal plate 133 from the outside of the first cover plate 171. The first outer terminal plate 133 can have one side surface positioned on the right, and can face the outer surface of the first cover plate 171. Of course, an insulating member (e.g., the first coupling member 172) for insulation can be interposed between one surface of the first outer terminal plate 133 and the outer surface of the first cover plate 171.

[0059] The first inner terminal plate 131, the first terminal post 132, and the first outer terminal plate 133 serving as the first terminal 130 can be made of copper or a copper alloy. In the first terminal 130, the first outer terminal plate 133 and the first terminal post 132 can be exposed and protrude to the outside of the first cover plate 171. Also, the first terminal post 132 and the first inner terminal plate 131 can be electrically connected to the first current collector 120 inside the first cover plate 171.

[0060] Here, one surface of the first inner terminal plate 131 can face the left end side surface of the electrode assembly 110. Of course, the first current collector 120 can be interposed between one surface of the first inner terminal plate 131 and the left end side surface of the electrode assembly 110 to electrically connect the first terminal 130 and the first electrode tab 111a of the electrode assembly 110 to each other.

[0061] The second current collector 140 can include a second main plate having a substantially rectangular plate shape in which a plurality of metal thin films are overlapped, and second sub-plates surrounding regions (e.g., set or predetermined regions) of both ends of the second main plate in the longitudinal direction, respectively. Also, the second main plate can be formed by stacking or winding the plurality of metal thin films and then compressing. Also, the second current collector 140 can include a connection portion 140a composed of only the second main plate, and a second tab coupling portion 140b and a second terminal coupling portion 140c extending outward from both ends of the connection portion 140a and composed of the second main plate and the second sub-plates surrounding the second main plate.

[0062] The second current collector 140 can have the same shape and structure as the first current collector 120. However, the second current collector 140 can be coupled to the electrode assembly 110 and the second terminal 150, thereby being symmetrical to the first current collector 120 with respect to the electrode assembly 110. Also, the second current collector 140 can be made of aluminum or an aluminum alloy.

[0063] The second terminal 150 can be formed of a metal and can be electrically connected to the second current collector 140. According to some embodiments, the second terminal 150 can include a second inner terminal plate 151, a second terminal post 152, and a second outer terminal plate 153.

[0064] Here, the second inner terminal plate 151 can be located inside the second cover plate 181, and the second outer terminal plate 153 can be located outside the second cover plate 181. Of course, the second gasket 183 can be further interposed between the second outer terminal plate 153 and the second cover plate 181. Also, the second gasket 183 can be further interposed between the second terminal post 152 and the second cover plate 181 and between the second inner terminal plate 151 and the second cover plate 181. Also, the second terminal post 152 can pass through the second cover plate 181 to be coupled to the second outer terminal plate 153 from the outside of the second cover plate 181, and to be coupled to the second inner terminal plate 151 from the inside of the second cover plate 181. In an embodiment, an insulating member can be provided between the right end side of the electrode assembly 110 and the inner surface of the second cover plate 181.

[0065] The second terminal 150 can have the same shape and structure as the first terminal 130. However, the second terminal 150 can be coupled to the electrode assembly 110 through the second current collector 140, thereby being symmetrical to the first terminal 130 with respect to the electrode assembly 110. Also, the second terminal 150 can be made of aluminum or an aluminum alloy.

[0066] The case 160 can have a substantially hollow cuboid shape in which openings 161, 162 are formed at both sides. The electrode assembly 110 coupled to the first current collector 120 and the second current collector 140 can be inserted into the case 160 through the openings 161, 162.

[0067] The first cover assembly 170 can be coupled to the left side opening 161 of the case 160. According to some embodiments, the first cover assembly 170 can include a first cover plate 171, a first coupling member 172, and a first gasket 173. The first cover plate 171 can have a flat square plate shape to seal the left side opening 161 of the case 160. The first cover plate 171 can include a terminal hole 171a passing through between an outer surface and an inner surface. The first terminal post 132 can pass through the terminal hole 171a of the first cover plate 171 to be coupled to the first cover plate 171. Also, the first terminal post 132 can be coupled to the first outer terminal plate 133 on the left side of the first cover plate 171 and can be coupled to the first inner terminal plate 131 on the right side of the first cover plate 171. Here, the first inner terminal plate 131 and a portion of the right side of the first terminal post 132 can be located inside the case 160.

[0068] The first coupling member 172 can be interposed between the outer surface of the first cover plate 171 and the first outer terminal plate 133. The first coupling member 172 can be in close contact with the first cover plate 171 and can also be in close contact with the first gasket 173. The first coupling member 172 can be made of an insulating material and can insulate the first cover plate 171 and the first outer terminal plate 133 from each other and insulate the first cover plate 171 and the first terminal post 132 from each other.

[0069] Also, the first gasket 173 can be made of an insulating material and can be formed between the first cover plate 171 and the first terminal 130 to seal a space between the first cover plate 171 and the first terminal 130. That is, the first gasket 173 can be interposed between the first cover plate 171 and the first terminal post 132 and between the first cover plate 171 and the first inner terminal plate 131. The first gasket 173 can prevent or reduce a case in which external moisture penetrates into the secondary battery 100, or can prevent or reduce a case in which electrolyte solution contained in the secondary battery 100 leaks.

[0070] Also, after the electrode assembly 110 having the first current collector 120 coupled thereto is accommodated in the case 160, the first cover plate 171 coupled to the first terminal 130 can seal the opening of the case 160. Of course, before the first cover plate 171 seals the case 160, the first terminal coupling portion 120c of the first current collector 120 and the first inner terminal plate 131 of the first terminal 130 can be coupled to each other by welding. Also, after the first current collector 120 is coupled to the first terminal 130, the connection portion 120a of the first current collector 120 can be relatively easily bent, and thus the first cover plate 171 can be relatively easily coupled to the opening 161 of the case 160.

[0071] The second cover assembly 180 can be coupled to the right side opening 162 of the case 160. According to some embodiments, the second cover assembly 180 can include a second cover plate 181, a second coupling member 182, and a second gasket 183. The second cover assembly 180 can have the same shape and structure as the first cover assembly 170. In addition, the coupling shape and structure of the second cover assembly 180 and the second terminal 150 can be the same as the coupling shape and structure of the first cover assembly 170 and the first terminal 130. However, the coupling shape of the second cover assembly 180 and the second terminal 150 can be symmetrical with respect to the coupling shape of the first cover assembly 170 and the first terminal 130 with respect to the case 160. According to some embodiments, the second cover plate 181 can seal the right side opening 162 of the case 160.

[0072] In the secondary battery 100, the first cover assembly 170 coupled to the first terminal 130 can be coupled to the opening of one side of the case 160, and the second cover assembly 180 coupled to the second terminal 150 can be coupled to the opening of the other side of the case 160, such that the first terminal 130 and the second terminal 150 are located at both sides of the case 160. The secondary battery 100 includes the first terminal 130 and the second terminal 150 provided at both sides (e.g., opposite sides), respectively, and when a plurality of secondary batteries 100 are combined in a module form, the cooling member can be coupled to the upper and lower regions of the case 160, respectively, thereby reducing degradation of the secondary battery 100 and improving cooling performance.

[0073] For example, in a case where the long sides of a plurality of secondary batteries 100 are arranged to face each other, the battery module can electrically connect the first terminal and / or the second terminal respectively exposed to both sides (e.g., opposite sides).

[0074] In addition, the secondary battery 100 includes the first terminal 130 and the second terminal 150 provided at both sides, respectively, and when a plurality of secondary batteries 100 are combined in a module form, a charging / discharging current flows in both directions from each terminal, thereby reducing degradation due to the charging / discharging current. In addition, when a plurality of secondary batteries 100 are combined in a module form, the respective terminals can be connected in both directions, thereby increasing space utilization.

[0075] As described above, in the secondary battery of the disclosure, since the current collector is made of a multi-layer metal thin film, the total cross-sectional area can be increased, thereby relatively improving heat generation performance and facilitating bending.

[0076] In addition, by wrapping the area of the current collector connected to the terminal and the electrode assembly with a metal thicker than the metal thin film, the secondary battery of the disclosure can prevent or reduce damage during welding.

[0077] Further, the secondary battery of the present disclosure includes first and second terminals on both sides, respectively, and thus, even when a plurality of secondary batteries are combined in a module form, the cooling member can be coupled to the upper and lower regions of the case, respectively, thereby preventing or reducing deterioration of the secondary battery and improving cooling performance.

[0078] Further, the secondary battery of the present disclosure includes first and second terminals on both sides, respectively, and when a plurality of secondary batteries are combined in a module form, a charge / discharge current flows from two directions along each terminal, thereby reducing deterioration due to the charge / discharge current and improving space utilization.

[0079] While aspects of some embodiments are described to implement a secondary battery according to the present disclosure, it should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of examples should not be construed as limiting upon the scope of the present disclosure, which is defined by the claims and their equivalents.

Claims

1.A secondary battery comprising: an electrode assembly having first and second electrode tabs exposed to opposite sides of the electrode assembly, respectively; a first current collector coupled to the first electrode tab of the electrode assembly; a case accommodating the electrode assembly and the first current collector and having opposite sides that are open; a first cover sealing an opening of one of the opposite sides of the case; and a first terminal coupled to the first current collector and exposed to an outside of the first cover, wherein the first current collector includes: a first main plate in which a plurality of metal thin films are overlapped; and first sub plates surrounding both ends of the first main plate in a longitudinal direction, respectively, the both ends of the first main plate being coupled to the first electrode tab and the electrode assembly through the first sub plates, respectively. 2.The secondary battery of claim 1, wherein in the first current collector, the first sub plate on one side contacts and is welded to the first electrode tab, and the first sub plate on the other side contacts and is welded to the first terminal. 3.The secondary battery of claim 1, wherein the first current collector includes: a connection portion formed of the first main plate; a first tab coupling portion extending outward from one end of the connection portion, including the first main plate and the first sub plate surrounding the first main plate, and coupled to the first electrode tab; and a first terminal coupling portion extending outward from the other end of the connection portion, including the first main plate and the first sub plate surrounding the first main plate, and coupled to the first terminal. 4.The secondary battery of claim 3, wherein in the first current collector, a surface on which the first tab coupling portion contacts and is welded to the first electrode tab is the same as a surface on which the first terminal coupling portion contacts and is welded to the first terminal, and the connection portion is bent at least once. 5.The secondary battery of claim 1, wherein a thickness of the first sub plate is 2 to 5 times a thickness of the metal thin films of the first main plate. 6.The secondary battery of claim 1, wherein the first main plate is compressed in a state in which 4 to 10 metal thin films of 0.05 mm to 0.2 mm are overlapped. 7.The secondary battery of claim 1, wherein the first terminal includes: a first inner terminal plate inside the first cover; a first outer terminal plate outside the first cover; and a first terminal post coupled to the first inner terminal plate from an inside of the first cover, passing through the first cover, and coupled to the first outer terminal plate from an outside of the first cover. 8.The secondary battery of claim 7, wherein in the first current collector, the first sub plate is coupled to one surface of the first inner terminal plate by welding. 9.The secondary battery of claim 1, further comprising: a second current collector coupled to the second electrode tab of the electrode assembly; a second cover sealing an opening of the other side of the case; and a second terminal coupled to the second current collector and exposed to an outside of the second cover. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A second terminal coupled to the second current collector and exposed to an outside of the second cover plate. 10.The secondary battery of claim 9, wherein the second current collector comprises: a second main plate in which a plurality of layers of metal thin films are overlapped; and second sub-plates respectively surrounding both ends of the second main plate in the longitudinal direction. 11.The secondary battery of claim 1, wherein a thickness of the first sub-plate is 0.1mm or more.

Images