Battery cell and battery pack including same

Abstract

A battery cell according to an embodiment of the present invention comprises: an electrode assembly in which a first electrode, a second electrode, and a separator between the first electrode and the second electrode are sequentially stacked a plurality of times; a battery case accommodating the electrode assembly and extending in the longitudinal direction of the electrode assembly; at least two degassing holes formed on the outer surface of the battery case; and a cover part covering each of the at least two degassing holes, wherein the battery case is a prismatic case, and the degassing holes are covered by the cover part after the pressure inside the battery case becomes lower than atmospheric pressure in a state in which the degassing holes are opened.

Description

Battery cell and battery pack containing the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0096542, filed July 22, 2024, and Korean Patent Application No. 10-2025-0088460, filed July 2, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a battery cell and a battery pack including the same, and more particularly, to a battery cell having at least two degassing holes formed in a battery case and a battery pack including the same.

[0004] Secondary batteries, which boast high electrical properties such as high energy density and easy applicability across a wide range of product groups, are widely used not only in portable devices but also in electric or hybrid vehicles powered by electrical power sources, as well as in power storage devices. These batteries are attracting attention as a new energy source for environmental friendliness and energy efficiency, not only for their primary advantage of dramatically reducing fossil fuel use, but also because they produce no byproducts from energy use.

[0005] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are receiving attention for their advantages of being able to charge and discharge freely, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based secondary batteries.

[0006] In general, lithium secondary batteries can be classified into cylindrical or square secondary batteries in which the electrode assembly is built into a metal can, and pouch-type secondary batteries in which the electrode assembly is built into a pouch of an aluminum laminate sheet, depending on the shape of the outer packaging material.

[0007] At this time, the lithium secondary battery undergoes an activation process of charging and discharging several times while the electrode assembly is stored within the battery case, and a large amount of gas may be generated inside the lithium secondary battery during the activation process. At this time, in the case of pouch-type batteries, a degassing process is generally performed after the activation process to release the gas generated inside the battery case to the outside, and the gas inside the lithium secondary battery can be released to the outside through the degassing process.

[0008] However, conventional square batteries lack a degassing process, making it impossible to vent internal gas. This gas, in turn, reduces the long-term lifespan of secondary batteries. Therefore, there is a pressing need to develop a structure that facilitates the degassing process, even for square batteries.

[0009] The problem to be solved by the present invention relates to a battery cell having at least two degassing holes formed in a battery case and a battery pack including the same.

[0010] The problems to be solved by the present invention are not limited to the problems described above, and problems not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

[0011] According to one embodiment of the present invention, a battery cell comprises: an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are sequentially laminated multiple times; a battery case that houses the electrode assembly and extends along a longitudinal direction of the electrode assembly; at least two degassing holes formed on an outer surface of the battery case; and a cover part that covers each of the at least two degassing holes, wherein the battery case is a square case, and after a pressure inside the battery case is formed lower than atmospheric pressure in a state in which the degassing holes are open, the degassing holes are covered by the cover part.

[0012] The above at least two degassing holes may be respectively arranged at adjacent positions on both sides of the battery case.

[0013] It includes a pair of electrode terminals electrically connected to the first electrode and the second electrode, respectively, and the pair of electrode terminals may each protrude in the outer direction of the battery case.

[0014] Among the pair of electrode terminals, one of the at least two degassing holes may be positioned adjacent to an electrode terminal electrically connected to the first electrode, and the other of the at least two degassing holes may be positioned adjacent to an electrode terminal electrically connected to the second electrode.

[0015] The pair of electrode terminals may extend in opposite directions based on the longitudinal direction of the electrode assembly, the pair of electrode terminals may protrude outward from each end of the battery case, and the at least two degassing holes may be arranged at each end of the battery case.

[0016] The at least two degassing holes may be respectively arranged at positions spaced apart from each other on the upper portion of the pair of electrode terminals.

[0017] The pair of electrode terminals may each protrude from the upper portion of the battery case toward the outside of the battery case, and the at least two degassing holes may each be arranged on the upper portion of the battery case.

[0018] The at least two degassing holes may be positioned at positions spaced apart from each other at both ends of the upper portion of the battery case, with the pair of electrode terminals interposed therebetween.

[0019] The at least two degassing holes and the cover part may be welded together.

[0020] The above square case may be of a can type.

[0021] A battery pack according to another embodiment of the present invention may include the battery cell described above.

[0022] According to embodiments, the battery cell of the present invention and the battery pack including the same have at least two degassing holes formed in the battery case, so that gas generated inside the battery cell during the activation process can be discharged to the outside of the battery cell.

[0023] In addition, the battery cell of the present invention and the battery pack including the same are formed so that the pressure inside the battery case is lower than the atmospheric pressure, so that the degassing hole is covered by the cover part, thereby minimizing lithium plating occurring inside the battery cell.

[0024] The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

[0025] FIG. 1 is a perspective view showing a battery cell according to one embodiment of the present invention.

[0026] Fig. 2 is an exploded perspective view of a square case with the electrode assembly included in the battery cell of Fig. 1 omitted.

[0027] FIG. 3 is a top view showing an electrode assembly included in the battery cell of FIG. 1.

[0028] Figure 4 is a perspective view showing a battery cell according to another embodiment of the present invention.

[0029] Fig. 5 is an exploded perspective view of a square case with the electrode assembly included in the battery cell of Fig. 4 omitted.

[0030] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0031] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0032] Furthermore, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to the illustrated components. In the drawings, the thicknesses are enlarged to clearly represent various layers and regions. Furthermore, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0033] Additionally, throughout the specification, whenever a part is said to “include” a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0034] Additionally, throughout the specification, when we say "in plan", we mean when the target portion is viewed from above, and when we say "in cross section", we mean when the target portion is viewed from the side in a cross-section cut vertically.

[0035] Below, a battery cell (100) according to one embodiment of the present invention will be described.

[0036] Fig. 1 is a perspective view illustrating a battery cell according to one embodiment of the present invention. Fig. 2 is an exploded perspective view of a square case with a structure in which the electrode assembly included in the battery cell of Fig. 1 is omitted. Fig. 3 is a top view illustrating the electrode assembly included in the battery cell of Fig. 1.

[0037] Referring to FIGS. 1 to 3, a battery cell (100) according to one embodiment of the present invention includes an electrode assembly (170) in which a first electrode (140), a second electrode (150), and a separator (160) interposed between the first electrode (140) and the second electrode (150) are sequentially laminated multiple times; and a battery case (110) that houses the electrode assembly (170) and extends along the length of the electrode assembly (170). Here, the battery case (110) can accommodate an electrolyte together with the electrode assembly (170) therein.

[0038] Referring to FIGS. 1 to 3, the battery case (110) may refer to a hexahedral square case having a space capable of accommodating an electrode assembly (170). In other words, the battery case (110) may be a square case formed in a can type. For example, the battery case (110) may be formed of a heat-resistant metal such as aluminum (Al), nickel (Ni), iron (Fe), titanium (Ti), chromium (Cr), tungsten, etc. As another example, the battery case (110) may be formed of a heat-resistant metal such as aluminum (Al), nickel (Ni), iron (Fe), titanium (Ti), chromium (Cr), tungsten, etc., and the inner and / or outer surfaces of the battery case (110) may be treated with an insulating coating.

[0039] More specifically, the battery case (110) may include a main body case (111) having both ends open based on the longitudinal direction of the electrode assembly (170), and a side case (115) covering both ends of the battery case (110). However, the shape of the battery case (110) is not limited thereto, and the battery case (110) may be included in the present embodiment if it has a structure that can easily accommodate the electrode assembly (170) therein.

[0040] For example, the parts where the main body case (111) and the side case (115) are in contact with each other may be joined by a method such as welding, so that the interior of the battery case (110) can be sealed from the external environment. However, this is not limited to this, and any joining method that can seal the interior of the battery case (110) may be included in this embodiment.

[0041] Referring to FIG. 3, the electrode assembly (170) may be a stacking type electrode assembly in which a first electrode (140), a second electrode (150), and a separator (160) interposed between the first electrode (140) and the second electrode (150) are alternately stacked. However, the present invention is not limited thereto, and in a structure in which the first electrode (140) and the second electrode (150) are stacked, the separator (160) may be interposed between the first electrode (140) and the second electrode (150), and may be a stacking-folding type electrode assembly in which the separator (160) is folded in a form that surrounds the first electrode (140) and / or the second electrode (150).

[0042] Referring to FIG. 3, the first electrode (140) may include a first electrode current collector (141) and a first electrode active material layer (145) formed on the upper and lower surfaces of the first electrode current collector (141), and the second electrode (150) may include a second electrode current collector (151) and a second electrode active material layer (155) formed on the upper and lower surfaces of the second electrode current collector (151).

[0043] Here, the first electrode (140) may be a positive electrode and the second electrode (150) may be a negative electrode. When the first electrode (140) is a positive electrode, the first electrode current collector (141) may correspond to a positive electrode current collector, and the first electrode active material layer (145) may correspond to a positive electrode active material layer. In addition, when the second electrode (150) is a negative electrode, the second electrode current collector (151) may correspond to a negative electrode current collector, and the second electrode active material layer (155) may correspond to a negative electrode active material layer. However, the present invention is not limited thereto, and the opposite case may also be included in the present embodiment.

[0044] The first electrode (140) may include a first electrode tab (141t), and the second electrode (150) may include a second electrode tab (151t). More specifically, the first electrode tab (141t) is a region on the upper or lower surface of the first electrode current collector (141) where the first electrode active material layer (145) is not formed, and may be positioned at one end of the first electrode current collector (141). In addition, the second electrode tab (151t) is a region on the upper or lower surface of the second electrode current collector (151) where the second electrode active material layer (155) is not formed, and may be positioned at one end of the second electrode current collector (151).

[0045] Accordingly, the battery cell (100) according to the present embodiment includes an electrode assembly (170) in which a first electrode (140), a second electrode (150), and a separator interposed between the first electrode (140) and the second electrode (150) are sequentially laminated multiple times, so that more parallel connections between the electrodes can be made, thereby effectively implementing a reduction in resistance, and has the advantage that the space utilization rate and battery capacity inside the battery case (110) can be further improved.

[0046] However, the shape of the electrode assembly (170) built into the battery cell (100) according to the present embodiment is not limited thereto, and a case in which a jelly roll-type electrode assembly is wound with a first electrode sheet, a second electrode sheet, and a separator sheet disposed between the first electrode sheet and the second electrode sheet may also be included in the present embodiment.

[0047] Referring to FIGS. 1 to 3, the battery cell (100) according to the present embodiment includes a pair of electrode terminals (120) electrically connected to a first electrode (140) and a second electrode (150), respectively, and the pair of electrode terminals (120) may each protrude in the outer direction of the battery case (110). For example, when the first electrode (140) is a positive electrode, one of the pair of electrode terminals (120) may be a positive terminal, and when the second electrode (150) is a negative electrode, the other of the pair of electrode terminals (120) may be a negative terminal. However, the present invention is not limited thereto, and the opposite case may also be included in the present embodiment.

[0048] More specifically, one electrode terminal of the pair of electrode terminals (120) may be electrically connected to the first electrode tab (141t) of the first electrode (140), and the other electrode terminal of the pair of electrode terminals (120) may be electrically connected to the second electrode tab (151t) of the second electrode (150). For example, one electrode terminal of the pair of electrode terminals (120) and the first electrode tab (141t) and the second electrode tab (151t) may be welded to each other, respectively.

[0049] Referring to FIG. 1, a pair of electrode terminals (120) extend in opposite directions based on the longitudinal direction of the electrode assembly (170), and a pair of electrode terminals (120) protrude from each end of the battery case (110) in the outward direction of the battery case (110).

[0050] Here, the two ends of the battery case (110) may refer to both sides of the battery case (110) positioned based on the longitudinal direction of the electrode assembly (170). In other words, the two ends of the battery case (110) may refer to the side cases (115).

[0051] Additionally, a pair of electrode terminals (120) protruding outwardly from the battery case (110) can be electrically connected to electrical elements outside the battery cell (100).

[0052] Accordingly, the battery cell (100) according to the present embodiment has a pair of electrode terminals (120) protruding in both directions, so that the assembly process and components for forming an electrical connection structure between the electrode tabs (131t, 151t) and the electrode terminals (310, 350) can be simplified.

[0053] Referring to FIGS. 1 and 2, terminal insertion holes (115h) may be formed at each end of the battery case (110). Here, the both ends of the battery case (110) may refer to side cases (115). The terminal insertion holes (115h) may be formed at one end of the battery case (110) where one of the pair of electrode terminals (120) is located and at the other end of the battery case (110) where the other of the pair of electrode terminals (120) is located.

[0054] Here, a pair of electrode terminals (120) may each pass through a terminal insertion hole (115h) and protrude outward from the side case (115). At this time, a separate gasket (not shown) may be placed between each of the pair of electrode terminals (120) and the terminal insertion hole (115h).

[0055] Accordingly, in the battery cell (100) according to the present embodiment, contact between the side case (115) of the battery case (110) corresponding to the metal member and the pair of electrode terminals (120) can be prevented, while the insulation between the side case (115) of the battery case (110) and the pair of electrode terminals (120) can be further improved.

[0056] Referring to FIGS. 1 and 2, the battery cell (100) according to the present embodiment includes at least two degassing holes (130h) formed on the outer surface of the battery case (110) and a cover part (130) that covers each of the at least two degassing holes (130h).

[0057] More specifically, the degassing hole (130h) and the cover part (130) may have corresponding shapes. For example, as shown in FIGS. 1 and 2 , the degassing hole (130h) and the cover part (130) may have a circular shape. However, the present invention is not limited thereto, and any shape that allows the gas inside the battery cell (100) to be easily discharged while also allowing the battery cell (100) to be easily sealed may be included in the present embodiment.

[0058] For example, the degassing hole (130h) and the cover part (130) may be welded to each other. More specifically, the space between the degassing hole (130h) and the cover part (130) is sealed by welding, so that the cover part (130) can be completely embedded within the degassing hole (130h).

[0059] In this way, in the battery cell (100) according to the present embodiment, since the degassing hole (130h) and the cover part (130) are welded to each other, the bond between the degassing hole (130h) and the cover part (130) may not burst even at a pressure of 5 bar or more. That is, even if the pressure inside the battery cell (100) increases, the cover part (130) can prevent the inside of the battery cell (100) from being exposed to the atmosphere, and can prevent the inside of the battery cell (100) from being degraded by coming into contact with the atmosphere.

[0060] As another example, the cover portion (130) may be made of a taping material or a polypropylene resin (PP resin) material that covers the degassing hole (130h). More specifically, the space between the degassing hole (130h) and the cover portion (130) may be sealed, and the cover portion (130) may be removed as needed during the process and then the degassing hole (130h) may be resealed.

[0061] In this way, in the battery cell (100) according to the present embodiment, since the cover part (130) is made of a taping material or a polypropylene resin (PP resin) material, the degassing hole (130h) can be opened and closed as needed in the process. That is, when the degassing hole (130h) is open, the electrolyte can be injected or degassed through the degassing hole (130h), and when the degassing hole (130h) is closed, an activation process can be performed, so there is an advantage in that the degassing hole (130h) can be recycled in a deteriorated battery cell (100).

[0062] In the battery cell (100) according to the present embodiment, after the pressure inside the battery case (110) is formed to be lower than the atmospheric pressure while the degassing hole (130h) is open, the degassing hole (130h) is covered with the cover part (130). In other words, while the degassing hole (130h) is open, the gas inside the battery cell (100) can be discharged to the outside of the battery cell (100) through the degassing hole (130h). Thereafter, after the gas inside the battery cell (100) is sufficiently discharged, the pressure inside the battery cell (100) can be adjusted to a negative pressure state lower than the atmospheric pressure, and while the inside of the battery cell (100) is at the negative pressure, the degassing hole (130h) can be covered with the cover part (130).

[0063] Accordingly, in the battery cell (100) according to the present embodiment, the gas generated inside the battery cell (100) through the activation process can be easily discharged to the outside of the battery cell (100) through the degassing hole (130h).

[0064] In addition, since the inside of the battery cell (100) can be maintained in a negative pressure state, a phenomenon in which a small amount of gas generated while charging and discharging is performed after activation of the battery cell (100) is trapped inside the electrode assembly (170) can be prevented, and lithium plating that may occur around the trapped gas can be prevented.

[0065] That is, when the inside of the battery cell (100) is in a negative pressure state, gas generated inside the electrode assembly (170) can be released to the outside of the electrode assembly (170) due to the pressure difference, so that gas trapped inside the electrode assembly (170) can be minimized, and lithium plating can also be effectively prevented.

[0066] At least two degassing holes (130h) may be respectively arranged at adjacent positions on both sides of the battery case (110). More specifically, at least two degassing holes (130h) are respectively arranged at both ends of the battery case (110). In other words, at least two degassing holes (130h) may be respectively arranged at the side cases (115) of the battery case (110). However, the present embodiment is not limited to the case where the at least two degassing holes (130h) include two degassing holes (130h) as in FIGS. 1 and 2, and a case where two or more degassing holes (130h) are respectively arranged at adjacent positions on both sides of the battery case (110) may also be included in the present embodiment, unlike FIGS. 1 and 2.

[0067] For example, as shown in FIGS. 1 and 2, among a pair of electrode terminals (120), at least one of the two degassing holes (130h) may be disposed at a position adjacent to an electrode terminal electrically connected to a first electrode (140), and the other of the at least two degassing holes may be disposed at a position adjacent to an electrode terminal electrically connected to a second electrode (150). Here, the at least two degassing holes (130h) may be disposed at positions spaced apart from each other on the upper portions of the pair of electrode terminals (120). In other words, the at least two degassing holes (130h) may be positioned at the upper portions of the pair of electrode terminals (120) in the side case (115) of the battery case (110) at positions where leakage of the electrolyte contained inside the battery cell (100) is prevented while avoiding each of the pair of electrode terminals (120).

[0068] Accordingly, in the battery cell (100) according to the present embodiment, since at least two degassing holes (130h) are respectively arranged on both sides of the battery case (110), gas inside the battery cell (100) can be discharged in both directions.

[0069] In addition, in a battery cell (100) in which electrode terminals (120) are respectively arranged at both ends of an electrode assembly (170), there is an advantage in that the negative pressure inside the battery cell (100) can be more evenly maintained as at least two degassing holes (130h) are respectively arranged along the length direction of the electrode assembly (170).

[0070] In addition, since the battery cell (100) according to the present embodiment includes an electrode assembly (170) having a laminated structure in which a first electrode (140), a second electrode (150), and a separator are laminated multiple times, gas generated from the electrode assembly (170) can be released in various directions rather than being released in a specific direction, and gas inside the battery cell (100) can be easily discharged through at least two degassing holes (130h) formed on both sides of the battery case (110).

[0071] Fig. 4 is a perspective view showing a battery cell according to another embodiment of the present invention. Fig. 5 is an exploded perspective view of a square case with a structure in which the electrode assembly included in the battery cell of Fig. 4 is omitted.

[0072] Referring to FIGS. 4 and 5, the battery cell (200) according to the present embodiment can be described mostly in the same manner as the battery cell (100) according to FIGS. 1 to 3 described above, and only the parts that are different from the above-described contents of the battery cell (100) of FIGS. 1 to 3 will be additionally described.

[0073] Referring to FIGS. 4 and 5, a pair of electrode terminals (220) protrude from the upper portion of the battery case (210) toward the outside of the battery case (210), and at least two degassing holes (230h) are respectively arranged on the upper portion of the battery case (210). More specifically, the at least two degassing holes (230h) are located at positions spaced apart from each other at both ends of the upper portion of the battery case (210) and are located at positions spaced apart from each other.

[0074] Accordingly, in the battery cell (200) according to the present embodiment, since at least two degassing holes (130h) are respectively arranged on both sides of the upper surface of the battery case (210), the electrolyte inside the battery cell (200) can be effectively prevented from leaking, while the gas inside the battery cell (200) can be discharged in both directions.

[0075] In addition, in a battery cell (100) in which a pair of electrode terminals (220) are respectively arranged at both ends of an electrode assembly (not shown), there is an advantage in that the negative pressure inside the battery cell (200) can be more evenly maintained as at least two degassing holes (230h) are respectively arranged along the length direction of the electrode assembly (170).

[0076] In addition, since the battery cell (100) according to the present embodiment includes an electrode assembly (170) having a laminated structure in which a first electrode (140), a second electrode (150), and a separator are laminated multiple times, gas generated from the electrode assembly (170) can be released in various directions rather than being released in a specific direction, and gas inside the battery cell (100) can be easily discharged through at least two degassing holes (130h) arranged on both sides of the upper surface of the battery case (110).

[0077] A battery pack according to another embodiment of the present invention may include the battery cells described above. Meanwhile, the battery pack according to the present embodiment may be formed by directly packaging one or more of the battery cells described above within a pack case, or by manufacturing the battery cells as battery modules and then packaging them within a pack case.

[0078] The battery pack described above can be applied to various devices. These devices include electric bicycles, electric vehicles, hybrid vehicles, and other transportation vehicles. However, the present invention is not limited thereto and can be applied to various devices that utilize battery packs, which also fall within the scope of the present invention.

[0079] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0080] [Explanation of symbols]

[0081] 100, 200: Battery cells

[0082] 110, 210: Battery case

[0083] 111, 211: Body case

[0084] 115, 215: Side case

[0085] 115h, 211h: Electrode terminal hole

[0086] 120, 220: Electrode terminals

[0087] 130, 230: Cover

[0088] 130h, 230h: Degassing hole

[0089] 140: First electrode

[0090] 150: Second electrode

[0091] 160: Membrane

[0092] 170: Electrode assembly

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are sequentially laminated multiple times; A battery case having the electrode assembly built in and extending along the length of the electrode assembly; At least two degassing holes formed on the outer surface of the battery case; and Including a cover part that covers each of the at least two degassing holes, The above battery case is a square case, A battery cell in which the pressure inside the battery case is formed to be lower than atmospheric pressure while the degassing hole is open, and the degassing hole is covered with the cover part.

2. In paragraph 1, A battery cell in which at least two degassing holes are respectively arranged at adjacent positions on both sides of the battery case.

3. In paragraph 1, It comprises a pair of electrode terminals electrically connected to the first electrode and the second electrode, respectively, A battery cell in which the above pair of electrode terminals each protrude in the outer direction of the battery case.

4. In paragraph 3, Among the above pair of electrode terminals, One of the at least two degassing holes is positioned adjacent to an electrode terminal electrically connected to the first electrode, A battery cell wherein another of the at least two degassing holes is positioned adjacent to an electrode terminal electrically connected to the second electrode.

5. In paragraph 2, The pair of electrode terminals extend in opposite directions relative to the longitudinal direction of the electrode assembly, The above pair of electrode terminals protrude outward from each end of the battery case, A battery cell in which at least two degassing holes are respectively arranged at both ends of the battery case.

6. In paragraph 5, A battery cell in which at least two degassing holes are respectively arranged at positions spaced apart from each other on the upper portion of the pair of electrode terminals.

7. In paragraph 2, The above pair of electrode terminals each protrude outward from the upper portion of the battery case, A battery cell in which at least two degassing holes are each arranged on the upper portion of the battery case.

8. In paragraph 7, The battery cells, wherein the at least two degassing holes are positioned at positions spaced apart from each other at both ends of the upper portion of the battery case, with the pair of electrode terminals interposed therebetween.

9. In paragraph 1, A battery cell in which at least two degassing holes and the cover portion are welded together.

10. In paragraph 1, The above square case is a battery cell made of a can type.

11. A battery pack including the battery cell of paragraph 1.

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