Unit cell provided with a cap member and secondary battery including the same

Abstract

The present invention includes an electrode assembly in which a tab bundle and a round portion are formed, and a unit cell including a cap member provided in the vicinity of the round portion of the electrode assembly. The cap member includes a pair of first surfaces parallel to the upper and lower surfaces of the electrode assembly, a pair of second surfaces parallel to both side surfaces of the electrode assembly, one third surface connecting the pair of first surfaces and the pair of second surfaces, and an internal space formed by the pair of first surfaces, the pair of second surfaces, and the one third surface. The cap member includes an adhesion member that contacts the round portion of the electrode assembly. A through hole through which the tab bundle passes is formed in the third surface. The present invention relates to a secondary battery characterized by the above.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application Nos. 10-2023-0071471 and 10-2023-0180156, filed with the Korean Intellectual Property Office on June 2, 2023 and December 12, 2023, the contents of which are hereby incorporated by reference in their entirety into this application.

[0002] The present invention relates to a unit cell including a cap member and a secondary battery including the same.

Background Art

[0003] Due to air pollution caused by the use of fossil fuels and energy depletion, the demand for secondary batteries that can store electrical energy produced by the development of alternative energy is increasing.

[0004] Secondary batteries used as energy sources for various electronic devices that are indispensably used in modern society are increasing in required capacity due to the increasing usage and complexity of mobile devices and the development of electric vehicles, etc. To meet the needs of users, a large number of battery cells are arranged in relatively small-sized devices, while battery modules that electrically connect a large number of battery cells or battery packs including a large number of such battery modules are used in relatively large-sized vehicles, etc.

[0005] Such battery cells are manufactured in various structures for improving cell performance (see Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention provides a unit cell including a cap member capable of minimizing the generation of lithium by-products during charge and discharge by uniformly controlling the pressure applied to different positions of an electrode assembly, and a secondary battery including the same.

Means for Solving the Problems

[0008] The secondary battery according to the present invention includes an electrode assembly (100) having a tab bundle (110) and a rounded portion (130) formed at an end in the direction where the tab bundle (110) is located, and a unit cell including a cap member (200) near the rounded portion (130) of the electrode assembly (100). The cap member (200) includes a pair of first surfaces (210) parallel to the upper and lower surfaces of the electrode assembly (100), a pair of second surfaces (220) parallel to both side surfaces of the electrode assembly (100), a single third surface (230) connecting the pair of first surfaces (210) and the pair of second surfaces (220), and an adhesion member (240) provided in an internal space formed by the pair of first surfaces (210), the pair of second surfaces (220), and the single third surface (230) and contacting the rounded portion (130) of the electrode assembly (100). A through-hole (231) through which the tab bundle (110) passes is formed in the third surface (230).

[0009] In the secondary battery of the present invention, the adhesion member (240) is provided with a first space portion (S1) for gas collection.

[0010] The first space portion (S1) has a slit shape formed along the longitudinal direction of the adhesion member (240).

[0011] A first space portion (S1) for gas collection is provided between the third surface (230) and the adhesion member (240).

[0012] The cap member (200) is made of any one or more of an insulating rubber material and a chemical-resistant plastic material.

[0013] The cap member (200) is made of styrene-butadiene rubber or acrylonitrile-butadiene rubber.

[0014] In the secondary battery of the present invention, the unit cell includes a case (300) for accommodating the electrode assembly (100) in a state where the cap member (200) is provided.

[0015] In the secondary battery of the present invention, a plurality of the unit cells are stacked, and a second space portion (S2) is provided between the electrode assemblies (100).

[0016] A fixing member (A) is interposed between the first surfaces 210 so that the unit cells can be fixed to each other.

[0017] The fixing member (A) is an adhesive.

[0018] In the secondary battery of the present invention, the secondary battery is a battery module or a battery pack.

[0019] In the secondary battery of the present invention, a plurality of the unit cells are stacked.

[0020] Further, the secondary battery according to the present invention includes a tab bundle (110), an electrode assembly (100) having a round portion (130) formed at an end in the direction in which the tab bundle (110) is located, a case (300) for accommodating the electrode assembly (100), and a unit cell including a cap member (200) near an outer end of the case (300). The cap member (200) includes a pair of first surfaces (210) parallel to the upper and lower surfaces of the case (300), a pair of second surfaces (220) parallel to both side surfaces of the case (300), and one third surface (230) connecting the pair of first surfaces (210) and the pair of second surfaces (220). The third surface (230) is provided with a through hole (231) through which a tab bundle (110) or an electrode lead (120) extending from the electrode assembly (100) passes.

[0021] In the secondary battery of the present invention, the cap member is provided in an internal space formed by the pair of first surfaces, the pair of second surfaces, and the one third surface, and includes a contact member that contacts the end surface of the case.

[0022] The case is a pouch for a lithium secondary battery.

[0023] The electrode assembly has a basic structure of a lithium secondary battery including at least one positive electrode, a negative electrode, and a separator.

[0024] Further, in the secondary battery of the present invention, a plurality of the unit cells are stacked, and a third space portion (S3) is provided between the electrode assemblies (100).

[0025] A fixing member (A) is interposed between the first surfaces (210) so that the unit cells can be fixed to each other.

Advantages of the Invention

[0026] As described above, the secondary battery according to the present invention includes a cap member near the end of the electrode assembly, so that the pressure applied to the entire surface of the electrode assembly can be evenly controlled, and when the secondary battery is charged and discharged, lithium by-products can be minimized.

[0027] Since the cap member provided in the secondary battery according to the present invention has a space portion, it can also be used as a pocket for venting gas.

[0028] The cap member can clearly identify the outer shape boundary of the pouch-type unit cell, so that accurate stacking is possible and manufacturing defects can be reduced.

Brief Description of the Drawings

[0029]

Figure 1

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Figure 8

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Figure 13

Mode for Carrying Out the Invention

[0030] In a part of the accompanying drawings, the same reference numerals are given to corresponding components. Those skilled in the art will understand that this drawing clearly shows the elements simply, and is not necessarily illustrated to scale. For example, in order to assist the understanding of various embodiments, the dimensions of some elements shown in the drawings may be exaggerated compared to other elements. Also, elements of known technology that are useful or essential in commercially practicable embodiments are often not illustrated so as not to impede the gist of various embodiments of the present invention.

[0031] Hereinafter, based on the accompanying drawings, embodiments that enable a person having ordinary knowledge in the technical field to which the present invention pertains to easily implement the present invention will be described in detail. However, when explaining in detail the operating principle of a preferred embodiment of the present invention, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

[0032] Also, the same reference numerals are used for parts having similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where they are directly connected but also the case where they are indirectly connected with other elements interposed therebetween. Also, including a certain component means, unless otherwise specified to the contrary, not excluding other components and being able to further include other components.

[0033] FIG. 1 is an exploded perspective view of a battery cell according to the prior art. As shown in FIG. 1, the battery cell includes a case 10 in which a housing portion is formed, an electrode assembly 20 housed in the housing portion of the case 10, an electrode tab formed on the electrode assembly 20, an electrode lead 30 having one side connected thereto and the other side protruding outside the case 10, and an insulating film 40 located at a portion where the electrode tab and the electrode lead 30 are in contact.

[0034] In the manufacturing process of such a battery cell, for example, during the coating of the electrode active material, a sliding portion where the thickness of the active material at the electrode end is relatively thinner than that at the central portion inevitably occurs due to the fluidity of the slurry.

[0035] The secondary battery is frequently charged and discharged, and a pressure difference is generated in the electrode assembly due to the sliding portion, which is also a cause of generating Li by-products.

[0036] In view of the problems caused by the sliding part of the secondary battery as described above, the present invention provides a secondary battery that can evenly control the pressure applied to the entire surface of the electrode assembly by providing a cap member near the end of the electrode assembly, and can minimize the generation of lithium by-products during charging and discharging of the secondary battery.

[0037] Hereinafter, a unit cell including the cap member according to the present invention and a secondary battery including the same will be described with reference to the accompanying drawings.

[0038] FIG. 2 is an exploded perspective view of a unit cell according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view of the unit cell shown in FIG. 2.

[0039] Referring to FIGS. 2 and 3, the unit cell according to the first embodiment of the present invention includes an electrode assembly 100, a cap member 200, and a case 300.

[0040] According to one embodiment, the electrode assembly 100 can be composed of a jelly roll type electrode assembly having a structure in which a separator is interposed between a long sheet-shaped negative electrode and a positive electrode and then wound, a stack type electrode assembly composed of unit cells having a structure in which a rectangular positive electrode and a negative electrode are laminated with a separator interposed therebetween, a stack folding type electrode assembly in which the unit cells are wound by a long separation film, or a lamination stack type electrode assembly in which the unit cells are laminated with a separator interposed therebetween and adhered to each other.

[0041] For example, the negative electrode is manufactured by applying a slurry in which a negative electrode active material and a binder are mixed to a negative electrode current collector.

[0042] Examples of the negative electrode active material include carbon such as hard carbonized carbon and graphite-based carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O zMetal composite oxides such as (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Si-based materials which are Si, SiO, SiO2 alone or mixtures thereof, etc. can be used.

[0043] The positive electrode is manufactured by applying a slurry in which a positive electrode active material and a binder are mixed to a positive electrode current collector.

[0044] And as the positive electrode active material, layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2) or compounds substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x O4 (where x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; Ni-site type lithium nickel oxides represented by the chemical formula LiNi 1-x MxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); lithium manganese composite oxides represented by the chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc. can be mentioned, but it is not limited to only these.

[0045] On one hand, the negative electrode current collector and the positive electrode current collector are composed of a portion coated with a slurry in which an active material is mixed and a plain portion where no slurry is coated. The plain portion is cut to form or a separate conductive member is connected to the plain portion by ultrasonic welding or the like to form an electrode tab, and such electrode tabs are collected to form a tab bundle 110.

[0046] A pair of electrode leads 120 composed of a positive electrode lead and a negative electrode lead have a structure in which they are electrically connected to a tab bundle 110 composed of positive electrode tabs and negative electrode tabs of the electrode assembly 100 and then exposed to the outside of the case 300.

[0047] And at the end in the direction where the tab bundle 110 is located, since the loading becomes low due to the fluidity of the slurry-like active material and a sliding phenomenon occurs, a round portion 130 having a certain curvature is formed.

[0048] The cap member 200 according to an embodiment of the present invention is configured to make the pressure transmitted to the entire surface of the electrode assembly 100 uniform regardless of the position by being mounted so as to surround the round portion 130 of the electrode assembly 100 described above, for example, the round portion 130 at the end in the direction where the tab bundle 110 is located. On the other hand, the electrode assembly 100 described above can have a basic structure of a lithium secondary battery including at least one positive electrode, negative electrode, and separator.

[0049] Such a cap member 200 includes a first surface 210, a second surface 220, a third surface 230, and an adhesion member 240.

[0050] For example, the first surface 210 of the cap member 200 consists of a pair and is located parallel to the upper surface and the lower surface at the end when based on the entire length direction (Y-axis) of the electrode assembly 100. The second surface 220 of the cap member 200 consists of a pair and is located parallel to both side surfaces at the end when based on the entire width direction (X-axis) of the electrode assembly 100, and the third surface 230 is located parallel to the thickness direction (Z-axis) of the electrode assembly 100 and is connected to the pair of first surfaces 210 and the pair of second surfaces 220.

[0051] In summary, the cap member 200 has an internal space formed by the first surface 210, the second surface 220, and the third surface 230, and has a hexahedral shape with one side open.

[0052] The third surface 230 is provided with a through-hole 231 that is cut open to a certain width so that the tab bundle 110 of the electrode assembly 100 can pass through and protrude to the outside.

[0053] According to one embodiment, the contact member 240 of the cap member 200 is provided in the internal space formed by the first surface 210, the second surface 220, and the third surface 230 of the cap member 200, and is configured to be in close contact with the entire surface of the round portion 130 of the electrode assembly 100. Therefore, one surface of the contact member 240 of the cap member 200 is formed in the same outer shape as the round portion 130 so as to accommodate the round portion 130 of the electrode assembly 100, and the remaining surfaces of the contact member 240 have a shape that is in contact with the first surface 210, the second surface 220, and the third surface 230 of the cap member 200.

[0054] Since the cap member 200 composed of the first surface 210, the second surface 220, the third surface 230, and the contact member 240 surrounds the vicinity of the end of the electrode assembly 100, it can be made of any one or more of an insulating rubber material and a chemical-resistant plastic material.

[0055] The insulating rubber material can be, for example, styrene-butadiene rubber or acrylonitrile-butadiene rubber, but is not limited thereto as long as it is a material that can perform the same function.

[0056] Also, the chemical-resistant plastic material can be, for example, a material containing any one or more of polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), and polyolefin, but is not limited thereto as long as it is a material that can perform the same function.

[0057] On the one hand, after attaching the cap member 200 to the end of the electrode assembly 100 and then housing them in the case 300, it is not necessary to use a separate adhesive member for fixing the cap member 200. However, when applying an adhesive to the inner surface of the contact member 240, the contact member 240 can be securely fixed by the round portion 130.

[0058] By providing the cap member 200 having the above-described configuration at the round portion 130 of the electrode assembly 100, the pressure deviation generated depending on the position of the electrode assembly 100 can be reduced, and as a result, the generation of lithium by-products that may occur during charging and discharging of the secondary battery can be minimized.

[0059] The case 300 can be composed of an upper case and a lower case, and a pocket-shaped accommodating portion is formed to accommodate the electrode assembly 100 with the cap member 200 attached.

[0060] Such a case 300 forms the accommodating portion using a laminate sheet composed of an outer resin layer, a metal layer, and an inner resin layer.

[0061] The outer resin layer is located on the outer contour of the case 300. Such an outer resin layer can use a heat-resistant polymer excellent in tensile strength, moisture permeability prevention, and air permeability prevention so as to ensure heat resistance and chemical resistance while protecting the electrode assembly 100. As an example, nylon or polyethylene terephthalate can be used.

[0062] The metal layer 120 in contact with the outer resin layer corresponds to a barrier layer that prevents moisture and various gases from penetrating into the battery from the outside. As a material for such a metal layer, an aluminum thin film that is lightweight and excellent in formability can be used.

[0063] And since the inner resin layer is in direct contact with the electrode assembly 100, it must have insulation and electrolytic resistance, and also must have sealing properties, for example, the sealing portion where the inner layers are thermally bonded to each other must have excellent thermal bonding strength for sealing with the outside.

[0064] As materials for such an internal resin layer, polyolefin resins such as polypropylene, polyethylene, polyethylene acrylic acid, polybutylene, etc., which are excellent in chemical resistance and have good sealing properties, polyurethane resins, and polyimide resins can be selected, but are not limited thereto, and polypropylene excellent in mechanical physical properties such as tensile strength, rigidity, surface hardness, impact resistance, and chemical resistance can be used.

[0065] For example, in the unit cell of FIG. 2, it is shown that both the upper case and the lower case are provided with accommodating portions, and there are four sealing surfaces for sealing these upper case and lower case. However, not only can the accommodating portion be provided only in the upper case or the lower case, but it can also be configured such that the sealing surface is three by connecting one surface of the upper case and one surface of the lower case to each other.

[0066] Also, although it is shown that a pair of electrode tabs are located in both directions, this is only an example, and it can be a unidirectional unit cell in which a pair of electrode tabs are located in the same direction. Here, two through-holes can be formed in one surface of the cap member 200.

[0067] FIG. 4 is a perspective view showing a first modification of the cap member attached to the unit cell according to the first embodiment of the present invention, and FIG. 5 is a cross-sectional view of the cap member shown in FIG. 4.

[0068] Referring to FIGS. 4 and 5 for explanation, the first modification of the cap member is similar to the cap member of the first embodiment described in FIGS. 2 and 3 except for some shapes. Therefore, only the configuration different from the first embodiment will be described below.

[0069] The cap member 200 according to the first modification example is formed such that the third surface 230 and the contact member 240 are separated by a certain distance, so that a first space portion S1 is formed between the third surface 230 and the contact member 240. Such a first space portion S1 can be utilized as a space for collecting gas generated during charging and discharging of the secondary battery, so that it has the advantages of reducing the pressure deviation applied to the electrode assembly and delaying or preventing the case from being damaged due to gas expansion.

[0070] FIG. 6 is a perspective view showing a second modification example of the cap member 200 attached to the unit cell according to the first embodiment of the present invention, and FIG. 7 is a cross-sectional view of the cap member shown in FIG. 6.

[0071] Referring to FIGS. 6 and 7, the second modification example of the cap member 200 is similar to the cap member of the first embodiment described with reference to FIGS. 2 and 3 except for some shapes. Therefore, only the configuration different from the first embodiment will be described below.

[0072] The contact member 240 of the cap member 200 according to the second modification example is provided with a first space portion S1. For example, by providing a slit-shaped first space portion S1 along the longitudinal direction of the contact member 240, it is possible to provide a gas collection function generated during charging and discharging of the secondary battery and reduce the pressure deviation applied to the electrode assembly.

[0073] FIG. 8 is a first illustration of a cross-sectional view of a secondary battery showing a state in which unit cells according to the first embodiment of the present invention are stacked.

[0074] Referring to FIG. 8, a plurality of unit cells described with reference to FIGS. 2 and 3 can be stacked to form a battery module or a battery pack.

[0075] Since the cap member 200 is accommodated together inside the case 300, not only is the total thickness of each unit cell uniform, but also the outer shape boundary of the unit cell is clear, and the stacking process for the battery module and the battery pack is easy.

[0076] FIG. 9 is a second illustration of a cross-sectional view of a secondary battery showing a state in which unit cells according to a second modification of the first embodiment of the present invention are stacked. A plurality of unit cells described with reference to FIGS. 6 and 7 described above can be stacked to form a battery module or a battery pack. For example, in the stacking structure of the unit cell according to the second modification illustrated in FIG. 9, the cap member 200 having a form including a slit-shaped first space portion S1 along the longitudinal direction of the cap member 200, for example, the adhesion member 240 described with reference to FIGS. 6 and 7 is applied. Therefore, similar to the case of FIG. 8, it is possible to reduce the pressure deviation applied to the electrode assembly together with the gas collection function generated during charging and discharging of the secondary battery.

[0077] FIG. 10 is a third illustration of a cross-sectional view of a secondary battery showing a state in which unit cells according to the first embodiment of the present invention are stacked.

[0078] The secondary battery of the third illustration is a battery module or a battery pack composed of a case 300 surrounding a plurality of unit cells in which the cap member 200 of the first embodiment described with reference to FIGS. 2 and 3 is mounted on the electrode assembly 100.

[0079] On the other hand, between the first surfaces where the cap members 200 are in close contact with each other, a fixing member A, for example, an adhesive, can be interposed to fix the unit cells adjacent to each other.

[0080] In the case of the secondary battery according to the third illustration as described above, a second space portion S2 is formed between the unit cells depending on the thickness of the cap member 200. Therefore, when swelling occurs, it can be utilized not only as a buffer space but also as a gas collection space.

[0081] In addition, since a plurality of unit cells including each electrode assembly 100 and the cap member 200 are accommodated in a single case 300, not only can the manufacturing cost be reduced, but also the energy density can be improved by reducing the overall weight.

[0082] Moreover, although not shown in the drawings, it is also possible to configure a battery module or a battery pack by stacking a plurality of unit cells in which the cap member 200 according to the first modification or the second modification is attached to the electrode assembly.

[0083] FIG. 11 is an exploded perspective view of a unit cell according to a second embodiment of the present invention, and FIG. 12 is a cross-sectional view of a secondary battery showing a state in which the unit cells according to the second embodiment of the present invention are stacked.

[0084] The unit cell according to the second embodiment of the present invention is similar to the unit cell according to the first embodiment described with reference to FIGS. 2 and 3, except for the position of the cap member 200, and thus the description of the same configuration will be omitted.

[0085] In the unit cell of the second embodiment, the cap member 200 is located near the outer end of the case 300. Here, the case 300 can be a pouch of a lithium secondary battery according to one embodiment.

[0086] Such a cap member 200 includes a first surface 210, a second surface 220, a third surface 230, and an adhesion member 240. For example, the first surface 210 of the cap member 200 consists of a pair and is positioned parallel to the upper surface and the lower surface at the end when based on the entire length direction (Y-axis) of the case 300. The second surface 220 of the cap member 200 consists of a pair and is positioned parallel to each of the both side surfaces at the end when based on the entire width direction (X-axis) of the case 300, and the third surface 230 of the cap member 200 is positioned parallel to the thickness direction (Z-axis) of the case 300 and is connected to the pair of first surfaces 210 and the pair of second surfaces 220.

[0087] In summary, the cap member 200 has a hexahedral shape with an empty interior and one side open, formed by the first surface 210, the second surface 220, and the third surface 230.

[0088] The third surface 230 of the cap member 200 is provided with a through-hole 231 cut open to a certain width so that the tab bundle 110 and the electrode lead 120 of the electrode assembly 100 pass through and are exposed to the outside.

[0089] The adhesion member 240 of the cap member 200 is provided in the internal space formed by the first surface 210, the second surface 220, and the third surface 230, and is in close contact with the entire end surface of the case 300. Therefore, one surface of the adhesion member 240 has the same outer shape as the end of the case 300, and the remaining surfaces have a shape in contact with the first surface 210, the second surface 220, and the third surface 230.

[0090] When a plurality of unit cells in a state where the cap member 200 is mounted near the outer end of the case 300 are stacked to form a battery module or a battery pack, a third space portion S3 is formed between the unit cells depending on the thickness of the cap member 200.

[0091] Such a third space portion S3 can not only be utilized as a buffer space when swelling occurs, but also acts as a heat insulating layer, so that heat transfer between the unit cells can be minimized.

[0092] On the other hand, between the first surfaces where the cap members 200 are in close contact with each other, a fixing member A, for example, an adhesive, can be interposed to fix the unit cells located adjacent to each other.

[0093] FIG. 13 is a perspective view of a unit cell according to a third embodiment of the present invention. The unit cell according to the third embodiment of the present invention has a structure similar to that of the unit cell according to the second embodiment described in FIG. 11 except for the structure of the cap member 200.

[0094] In the unit cell according to the third embodiment, a pair of cap members 200 are positioned to be in close contact with each other near both outer ends of the case 300, and one or more connecting members 400 for connecting a part of the pair of cap members 200 to each other can be provided.

[0095] The connecting member 400 is a structure for preventing the cap members 200 from detaching by connecting a pair of cap members 200 to each other, and can be made of the same material as the cap members 200, and is not particularly limited as long as a pair of cap members 200 can be connected to each other, such as taping, clipping, hooking, or an adhesive.

[0096] In the above, the present invention has been described based on the embodiments. However, it will be understood that those skilled in the art or those having ordinary knowledge in the art can make various modifications and changes to the present invention without departing from the spirit and technical scope of the present invention described in the claims to be described later. Therefore, the technical scope of the present invention is not limited to the content described in the detailed description of the specification, but must be determined by the claims.

Explanation of Reference Numerals

[0097] 100 Electrode assembly 110 Tab bundle 120 Electrode lead 130 Round portion 200 Cap member 210 First surface 220 Second surface 230 Third surface 231 Through-hole 240 Adhesive member 300 Case 400 Connecting member A Fixed member S Space portion S1 First space portion S2 Second space portion S3 Third space portion

Claims

1. A secondary battery including an electrode assembly having a tab bundle and a round portion formed at an end in the direction where the tab bundle is located, and a unit cell having a cap member near the round portion of the electrode assembly, wherein the cap member includes a pair of first surfaces parallel to the upper and lower surfaces of the electrode assembly, a pair of second surfaces parallel to both side surfaces of the electrode assembly, one third surface connecting the pair of first surfaces and the pair of second surfaces, and a close contact member provided in an internal space formed by the pair of first surfaces, the pair of second surfaces, and the one third surface and contacting the round portion of the electrode assembly, and a through hole through which the tab bundle passes is formed in the third surface. A secondary battery.

2. The secondary battery according to claim 1, wherein the close contact member includes a first space portion for gas collection.

3. The secondary battery according to claim 2, wherein the first space portion has a slit shape formed along the longitudinal direction of the close contact member.

4. The secondary battery according to claim 1, wherein a first space portion for gas collection is provided between the third surface and the close contact member.

5. The secondary battery according to claim 1, wherein the cap member is made of any one or more of an insulating rubber material and a chemical-resistant plastic material.

6. The secondary battery according to claim 5, wherein the cap member is made of styrene butadiene rubber or acrylonitrile butadiene rubber.

7. The secondary battery according to claim 1, wherein the unit cell includes a case for accommodating the electrode assembly in a state where the cap member is provided.

8. The secondary battery according to any one of claims 1 to 7, wherein a plurality of the unit cells are stacked, and a second space portion is provided between the electrode assemblies.

9. The secondary battery according to claim 8, wherein a fixing member is interposed between the first surfaces so that the unit cells can be fixed to each other.

10. The secondary battery according to claim 9, wherein the fixing member is an adhesive.

11. The secondary battery according to claim 10, wherein the secondary battery is a battery module or a battery pack.

12. The secondary battery according to claim 7, wherein a plurality of the unit cells are stacked.

13. A secondary battery including a unit cell including an electrode assembly having a tab bundle and a round portion formed at an end in the direction in which the tab bundle is located, a case for accommodating the electrode assembly, and a cap member provided near an outer end of the case. The cap member includes a pair of first surfaces parallel to the upper and lower surfaces of the case, a pair of second surfaces parallel to both side surfaces of the case, and one third surface connecting the pair of first surfaces and the pair of second surfaces. The secondary battery, wherein the third surface is provided with a through-hole through which a tab bundle or an electrode lead extending from the electrode assembly passes.

14. The secondary battery according to claim 13, wherein the cap member is provided in an internal space formed by the pair of first surfaces, the pair of second surfaces, and the one third surface, and includes a contact member that is in close contact with an end surface of the case.

15. The secondary battery according to claim 14, wherein the case is a pouch for a lithium secondary battery.

16. The secondary battery according to claim 13, wherein the electrode assembly has a basic structure of a lithium secondary battery including at least one positive electrode, a negative electrode, and a separator.

17. The secondary battery according to claim 13, wherein a plurality of the unit cells are stacked, and a third space portion is provided between the electrode assemblies.

18. The secondary battery according to claim 17, wherein a fixing member is interposed between the first surfaces so that the unit cells can be fixed to each other.

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