Battery cell and battery module comprising same

Abstract

A battery cell according to one embodiment of the present invention comprises: a battery case having a housing part in which an electrode assembly is mounted, and a sealing part formed by sealing the outer periphery of the housing part; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding to the outside of the battery case through the sealing portion; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, in which the lead film has a recessed portion recessed in an outward direction of the battery case and open toward an interior of the battery case, and the battery cell includes a coating layer on the gas discharge portion of the lead film and containing a fluorine-based polymer.

Description

[0001] This case is a divisional application, and its parent case is an application with an application date of January 20, 2023, application number 202380010704.4, and invention name "Battery cell and battery module including the battery cell". Technical Field

[0002] The present disclosure relates to a battery cell and a battery module including the battery cell, and more particularly, to a battery cell capable of discharging gas generated in the battery cell to the outside and a battery module including the battery cell. This application claims priority to Korean Patent Application No. 10-2022-0010160 filed in Korea on January 24, 2022, the disclosure of which is incorporated herein by reference. Background Art

[0003] As technology develops and demand for mobile devices increases, demand for secondary batteries as energy sources is rapidly increasing. Specifically, secondary batteries are attracting attention not only as energy sources for mobile devices such as mobile phones, digital cameras, laptop computers, and wearable devices, but also as energy sources for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0004] According to the shape of the battery case, these secondary batteries are classified into: cylindrical batteries and square batteries, in which the electrode assembly is included in a cylindrical or square metal can; and soft-pack batteries, in which the electrode assembly is included in a soft-pack case of an aluminum laminate. Here, the electrode assembly included in the battery case is a power element, which includes a positive electrode, a negative electrode, and a separator inserted between the positive electrode and the negative electrode, capable of charging and discharging, and is classified into a jelly roll type in which a long sheet-type positive electrode and a long sheet-type negative electrode coated with an active material are wound and a separator is inserted therebetween, and a stacked type in which a plurality of positive electrodes and a plurality of negative electrodes are stacked in sequence and a separator is inserted therebetween.

[0005] Among them, in particular, a pouch type battery in which a stacked or stacked / folded type electrode assembly is included in a pouch type battery case made of an aluminum laminate sheet is increasingly used due to low manufacturing cost, light weight, and easy change.

[0006] However, in recent years, as the energy density of battery cells has increased, there is a problem that the amount of gas generated inside the battery cells has also increased. In the case of conventional battery cells, a component capable of discharging the gas generated inside the battery cells is not included, so degassing may occur in the battery cells due to gas generation. In addition, moisture may penetrate into the battery cells damaged by degassing, which may cause side reactions, and there are problems of battery performance degradation and generation of additional gas.

[0007] In order to solve this problem, various methods have been devised to discharge the gas generated inside the battery cell to the outside of the battery cell, but there is a problem that the gas is released to the outside of the battery cell and moisture penetrates into the battery cell at the same time. Therefore, there is an increasing demand for developing a battery cell that can discharge the gas generated inside the battery cell to the outside and prevent moisture from penetrating into the battery cell. Summary of the invention

[0008] Technical issues

[0009] The present disclosure is directed to providing a battery cell which improves the external discharge amount of gas generated in the battery cell and is capable of preventing moisture from penetrating into the battery cell, and a battery module including the same.

[0010] The objects of the present disclosure are not limited to the above objects, and those skilled in the art can clearly understand such objects which are not mentioned herein from the present specification and the accompanying drawings.

[0011] Technical Solution

[0012] In one aspect of the present disclosure, a battery cell according to the following embodiments is provided.

[0013] In a first embodiment, a battery cell includes: a battery case having a receiving portion and a sealing portion, an electrode assembly is mounted in the receiving portion, and the sealing portion is formed by sealing the outer periphery of the receiving portion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding to the outside of the battery case through the sealing portion; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film has a recessed portion that is recessed in an outward direction of the battery case and is open toward the inside of the battery case, and the battery cell includes a coating layer located on a gas discharge portion of the lead film and containing a fluorine-based polymer.

[0014] In a second embodiment according to the first embodiment, the gas discharge portion of the lead film may be located outside the outer surface of the battery case.

[0015] In a third embodiment according to the first embodiment or the second embodiment, the recessed portion may include a first recessed portion and a second recessed portion, and a width of the second recessed portion may be greater than a width of the first recessed portion.

[0016] In a fourth embodiment according to the third embodiment, the second recessed portion is located at a position which may be farther from the portion accommodating the electrode assembly than the first recessed portion.

[0017] In the fifth embodiment according to the third embodiment or the fourth embodiment, a portion of the first recessed portion may be located in a region corresponding to the sealing portion.

[0018] In a sixth embodiment according to any one of the third to fifth embodiments, a portion of the second recessed portion may be located in a region not corresponding to the sealing portion.

[0019] In a seventh embodiment according to any one of the third to sixth embodiments, an end portion of the second recessed portion outside the battery case may be located outside an outer surface of the battery case.

[0020] In an eighth embodiment according to any one of the third to seventh embodiments, the second recessed portion may be located between an end portion of the sealing portion and an end portion of the lead film.

[0021] In a ninth embodiment according to any one of the third to eighth embodiments, the coating may be located on the second depressed portion.

[0022] In a tenth embodiment according to any one of the third to ninth embodiments, the first recessed portion may extend along a protruding direction of the electrode lead, and the second recessed portion may extend along a length direction of the sealing portion.

[0023] In an eleventh embodiment according to any one of the first to tenth embodiments, the fluorine-based polymer may include a polymer including a repeating unit derived from tetrafluoroethylene, vinyl fluoride, vinylidene fluoride, or two or more monomers thereof.

[0024] In a twelfth embodiment according to any one of the first to eleventh embodiments, the coating layer may have a thickness of 0.1 μm to 2 mm.

[0025] In a thirteenth embodiment according to any one of the first to twelfth embodiments, based on a protruding direction of the electrode lead, an inner surface of the recessed portion may be closed.

[0026] In a fourteenth embodiment according to the thirteenth embodiment, the battery cell may further include an inner layer configured to cover at least one of inner surfaces of the recessed portion of the lead film.

[0027] In the fifteenth embodiment according to the thirteenth embodiment, the melting point of the material of the inner layer may be higher than the melting point of the material of the lead film and the material of the inner layer may not react with the electrolyte.

[0028] In a sixteenth embodiment according to any one of the first to fifteenth embodiments, the lead film may include a polyolefin-based material.

[0029] In a seventeenth embodiment according to the fifteenth or sixteenth embodiment, the inner layer may include at least one material of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material.

[0030] In an eighteenth embodiment according to any one of the first to seventeenth embodiments, the recessed portion may be located on the electrode lead.

[0031] In a nineteenth embodiment according to any one of the first to eighteenth embodiments, a length of the lead film may be greater than a width of the electrode lead.

[0032] In a twentieth embodiment according to the nineteenth embodiment, the recessed portion may be located between an end portion of the electrode lead and an end portion of the lead film.

[0033] In a twenty-first embodiment according to any one of the first to twentieth embodiments, an end portion of the recessed portion that is open toward the inside of the battery case may be located further inward of the inner surface of the battery case.

[0034] In a twenty-second embodiment according to any one of the first to twenty-first embodiments, a width of a portion of the lead film covering the front surface of the recessed portion may be 2 mm or more based on a protruding direction of the electrode lead.

[0035] In the twenty-third embodiment according to any one of the first to twenty-second embodiments, the thickness of the portion of the lead film covering the upper surface of the recessed portion may be 100 μm to 300 μm.

[0036] In a twenty-fourth embodiment according to any one of the first to twenty-third embodiments, the air permeability of the lead film at 60° C. may be 20 Barrer to 60 Barrer.

[0037] In a twenty-fifth embodiment according to any one of the first to twenty-fourth embodiments, the moisture permeability of the lead film may be 0.02 g to 0.2 g for 10 years under the conditions of 25° C. and 50% RH.

[0038] In one aspect of the present disclosure, a battery module according to the following embodiments is also provided.

[0039] In a twenty-sixth embodiment, there is provided a battery module including the battery cell according to the first embodiment.

[0040] Beneficial Effects

[0041] Since the battery cell according to an embodiment of the present disclosure includes an electrode lead attached with a lead film having a recessed portion recessed in an outward direction of a battery case and opened toward the inside of the battery case, the external discharge amount of gas generated inside the battery cell can be increased.

[0042] Since the battery cell according to the embodiment of the present disclosure includes the coating layer on the gas discharge portion of the lead film and including a fluorine-based polymer, the amount of moisture permeation into the battery cell may be reduced without affecting the external discharge amount of gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings illustrate preferred embodiments of the present disclosure, and together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the accompanying drawings.

[0044] Figure 1 is a top view showing a battery cell according to an embodiment of the present disclosure.

[0045] Figure 2 It is shown Figure 1 A perspective view of an electrode lead included in a battery cell.

[0046] Figure 3 is along Figure 2 A cross-sectional view taken along the b-b' axis.

[0047] Figure 4 is along Figure 2 Cross-sectional view taken along the c-c' axis.

[0048] Figure 5 It is shown Figure 1 An enlarged view of the electrode lead portion in a battery cell.

[0049] Figure 6 It shows that according to Figure 5 (a) is an enlarged view of the electrode lead portion at the position of the sealing portion.

[0050] Figure 7 is along Figure 1 A cross-sectional view taken along the a-a' axis. DETAILED DESCRIPTION

[0051] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description is made, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms to obtain the best interpretation.

[0052] Therefore, the descriptions presented herein are only preferred examples for illustrative purposes, and are not intended to limit the scope of the present disclosure, and it should be appreciated that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0053] In order to clearly explain the present disclosure, parts irrelevant to the description are omitted, and the same or similar components are given the same reference numerals throughout the specification.

[0054] In addition, since the size and thickness of each component shown in the drawings are arbitrarily expressed for the convenience of description, the present disclosure is not necessarily limited to the drawings. In order to clearly express the various layers and regions in the drawings, the thickness is exaggerated. In addition, in the drawings, for the convenience of explanation, the thickness of some layers and some regions is exaggerated.

[0055] Furthermore, throughout the specification, when a portion “includes” a certain component, unless otherwise specified, it means that other components may also be included, rather than excluding other components.

[0056] Hereinafter, a soft pack battery cell according to an embodiment of the present disclosure will be described. However, here, the description will be based on one of the two sides of the soft pack battery cell, but is not necessarily limited thereto, and the same or similar content may be described in the case of the other side.

[0057] A battery cell according to an embodiment of the present disclosure includes: a battery case having a receiving portion and a sealing portion, an electrode assembly being mounted in the receiving portion, and the sealing portion being formed by sealing the outer periphery of the receiving portion; an electrode lead being electrically connected to an electrode tab included in the electrode assembly and protruding to the outside of the battery case through the sealing portion; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film has a recessed portion that is recessed in an outward direction of the battery case and is open toward the inside of the battery case, and the battery cell includes a coating layer located on a gas discharge portion of the lead film and containing a fluorine-based polymer.

[0058] Figure 1 is a top view showing a battery cell according to an embodiment of the present disclosure.

[0059] Reference Figure 1 , the battery cell 100 according to the present embodiment includes a battery case 200 , an electrode lead 300 , and a lead film 400 .

[0060] The battery case 200 includes a housing 210 for housing the electrode assembly 110 and a sealing portion 250 formed by sealing the periphery of the housing 210. The sealing portion 250 may be sealed by heat or laser. The battery case 200 may be a laminate including a resin layer and a metal layer. More specifically, the battery case 200 may be made of a laminate, and may include an outer resin layer forming the outermost layer, a barrier metal layer to prevent material penetration, and an inner resin layer for sealing.

[0061] In addition, the electrode assembly 110 may have a jelly roll type (wound type), a stacked type (laminated type), or a composite type (stacked / folded type) structure. More specifically, the electrode assembly 110 may include a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator may have a structure and material commonly used in the art.

[0062] Reference Figure 1 The electrode lead 300 is electrically connected to an electrode tab (not shown) included in the electrode assembly 110 , and protrudes to the outside of the battery case 200 through the sealing portion 250 .

[0063] Figure 2 It is shown Figure 1 A perspective view of an electrode lead included in a battery cell.

[0064] Reference Figure 2 The lead film 400 is located at a portion corresponding to the sealing part 250 in at least one of the upper and lower portions of the electrode lead 300. Therefore, the lead film 400 can improve the sealing performance of the sealing part 250 and the electrode lead 300 while preventing a short circuit from occurring in the electrode lead 300 during sealing.

[0065] Figure 3 is along Figure 2 A cross-sectional view taken along the b-b' axis. Figure 4 is along Figure 2 Cross-sectional view taken along the c-c' axis.

[0066] Reference Figure 3 and Figure 4 The lead film 400 has a recessed portion 450 recessed in an outward direction of the battery case 200, and the recessed portion 450 is open toward the inside of the battery case 200. In addition, the inner surface of the recessed portion 450 may be closed based on the protruding direction of the electrode lead 300.

[0067] Therefore, in the lead film 400, when the gas generated inside the battery housing 200 reaches a predetermined pressure or more, the gas can be discharged to the recessed portion 450, and the gas introduced into the recessed portion 450 can be discharged to the outside of the battery according to the pressure difference between the inside and the outside. In addition, since the recessed portion 450 of the lead film 400 is open to the inside, and the inner surface of the recessed portion that is recessed in the outward direction of the lead film 400 is closed, it has the advantage of also ensuring the airtightness and durability of the soft pack. In addition, the lead film 400 can maximize the air permeability area through the recessed portion 450, so that a large amount of gas can be discharged.

[0068] In addition, refer to Figure 3 and Figure 4 The lead film 400 may further include an inner layer 410 covering at least one of the inner surfaces of the recessed portion 450 .

[0069] For example, refer to Figure 3 (a) and Figure 4 (a), in the recessed portion 450, the inner layer 410 may cover the entire surface of the lead film 400. That is, the inner layer 410 may be formed on the entire inner surface of the recessed portion 450 except for the open surface.

[0070] Therefore, even if the lead film 400 is sealed together with the sealing part 250 in a state of being located on at least one of the upper and lower parts of the electrode lead 300 , the recessed part 450 may be maintained in an unsealed state by the inner layer 410 .

[0071] As another example, refer to Figure 3 (b) and Figure 4 (b), the inner layer 410 may cover the upper surface or the lower surface of the inner surface of the recessed part 450. That is, the inner layer 410 may be formed on at least one of the upper surface and the lower surface of the recessed part 450 facing each other.

[0072] Therefore, while minimizing the inner layer 410 formed in the recessed portion 450 of the lead film 400, the recessed portion 450 may be maintained in an unsealed state by the inner layer 410. Furthermore, the manufacturing process may be simplified and the cost may be reduced.

[0073] More specifically, the inner layer 410 may be made of a material having a higher melting point than that of the lead film 400. In addition, the inner layer 410 may be made of a material that does not react with the electrolyte contained in the battery case 200. Therefore, since the inner layer 410 is made of the above-mentioned material, the recessed portion 450 may be retained or kept blank without reacting with the electrolyte alone and causing heat fusion, heat deformation, etc. during the sealing process.

[0074] In an embodiment of the present disclosure, the inner layer 410 may have a thickness of 100 μm or less.

[0075] In an embodiment of the present disclosure, the air permeability of the inner layer 410 may be greater than or equal to 40 Barrer. For example, the carbon dioxide permeability of the inner layer 410 may satisfy the above range. In this case, the gas can be discharged to the outside more easily.

[0076] For example, the inner layer 410 may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material. For example, the lead film 400 may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material that meets the above-mentioned air permeability value. The polyolefin-based material may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). The fluorine-based material may include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride. In addition, the inner layer 410 includes an air-intake material, so that air permeability can be improved and moisture permeability can be minimized. For example, the air-intake material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silicon dioxide (SiO2), etc., but is not limited thereto, and any material that reacts with water (H2O) may be used.

[0077] The inner layer 410 may include an adhesive material between the lead film 400 and the inner layer 410, or may be extruded together with the lead film 400 to adhere to the lead film 400. The adhesive material may include an acrylic type. Specifically, when the inner layer 410 is extruded together with the lead film 400, the air permeability of the inner layer 410 may be 40 Barrer or more.

[0078] Reference Figures 2 to 4 , the lead film 400 includes a first lead film and a second lead film, the first lead film may be located above the electrode lead 300, and the second lead film may be located below the electrode lead 300. At this time, the electrode lead 300 is sealed together with the sealing part 250 in a state of being located between the first lead film and the second lead film, so that the first lead film and the second lead film can be connected to each other.

[0079] Therefore, the lead film 400 may improve the sealing performance of the sealing part 250 and the electrode lead 300 while preventing the side surface of the electrode lead 300 from being exposed to the outside.

[0080] For example, in the lead film 400, the recessed portion 450 may be located in at least one of the first lead film and the second lead film. More specifically, in the lead film 400, the recessed portion 450 may be formed on the first lead film or the second lead film based on the electrode lead 300, or the recessed portion 450 may be formed on both the first lead film and the second lead film based on the electrode lead 300. However, the number of the recessed portions 450 is not limited to the above, and the recessed portions 450 may be formed in the lead film 400 in an appropriate number.

[0081] Therefore, the durability and airtightness of the lead film 400 can be controlled by adjusting the number of recessed parts 450 formed on the lead film 400. In addition, if necessary, the number of recessed parts 450 can be minimized to simplify the manufacturing process and reduce costs.

[0082] In one embodiment of the present disclosure, the air permeability of the lead film 400 may be 20 Barrer to 60 Barrer, or 30 Barrer to 40 Barrer at 60°C. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above range. In addition, based on a thickness of 200 μm of the lead film 400, the air permeability at 60°C may satisfy the above range. If the air permeability of the lead film 400 satisfies the above range, the gas generated inside the battery can be more effectively discharged.

[0083] In this specification, air permeability may be measured by ASTM F2476-20.

[0084] In one embodiment of the present disclosure, under the conditions of 25° C. and 50% RH, the moisture permeability of the lead film 400 may be 0.02 g to 0.2 g, or 0.02 g to 0.04 g, or 0.06 g, or 0.15 g for 10 years. If the moisture permeability of the lead film 400 satisfies the above range, moisture can be more effectively prevented from penetrating from the lead film 400.

[0085] In this specification, the moisture permeability (moisture permeability) can be measured by adopting the ASTM F 1249 method. At this time, the moisture permeability can be measured using an apparatus officially certified by MCOON.

[0086] In an embodiment of the present disclosure, the air permeability of the lead film 400 at 60° C. may be 20 Barrer to 60 Barrer, and the moisture permeability may be 0.02 g to 0.2 g for 10 years at 25° C. and 50% RH. When the air permeability and moisture permeability of the lead film 400 meet the above ranges, moisture can be more effectively prevented from penetrating from the outside while discharging the gas generated inside the battery.

[0087] In an embodiment of the present disclosure, the lead film 400 may include a polyolefin-based resin. For example, the lead film 400 may include a polyolefin-based resin that satisfies the above-mentioned air permeability value and / or moisture permeability value. The polyolefin-based resin may include one or more materials selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). The lead film 400 includes polypropylene, and the air permeability of the lead film 400 may be 20 Barrer to 60 Barrer at 60°C. In addition, the moisture permeability may be 0.06g to 0.15g. In this case, the gas generated inside the battery is more effectively discharged, and moisture can be easily prevented from penetrating from the outside.

[0088] In addition, since the lead film 400 is made of the above-mentioned material, the lead film 400 may maintain the airtightness of the battery cell 100 and prevent leakage of the internal electrolyte.

[0089] Figure 5It is shown Figure 1 An enlarged view of the electrode lead portion in a battery cell.

[0090] Reference Figure 5 , the coating layer 500 is located on the gas discharge portion of the lead film 400 .

[0091] When the recessed portion 450 is formed on the lead film 400 so that the gas generated inside the battery is discharged to the outside of the battery through the lead film 400, the lead film 400 has high permeability to substances outside the battery (such as moisture) due to the high air permeability of the lead film 400, so the substances outside the battery may be introduced into the battery. The coating 500 has low moisture permeability, so the amount of moisture that penetrates into the battery from the outside of the battery can be reduced.

[0092] The coating layer 500 is located on the gas discharge portion of the lead film 400 and can reduce the amount of moisture permeation from the outside of the battery to the inside of the battery while having little effect on the discharge of gas inside the battery to the outside of the battery.

[0093] In an embodiment of the present disclosure, the coating 500 may have a thickness of 0.1 μm to 2 mm. When the thickness of the coating 500 satisfies the above range, it is easier to reduce the amount of moisture permeation from the outside of the battery to the inside of the battery, while having little effect on the discharge of gas from the inside of the battery to the outside of the battery. For example, when the thickness of the coating 500 is 0.1 μm to 200 μm, the gas discharge amount may be more than 1 cc / day, while reducing the amount of moisture permeation from the outside of the battery into the battery. In addition, when the coating 500 has a thickness of 200 μm to 2 mm, the gas discharge amount may be less than 1 cc / day, while reducing the amount of moisture permeation from the outside of the battery into the battery.

[0094] The coating layer 500 includes a fluorine-based polymer. The fluorine-based polymer has high air permeability and low water permeability, and thus is suitable as a material for the coating layer 500.

[0095] In an embodiment of the present disclosure, the fluorine-based polymer may include repeating units derived from a polymer containing tetrafluoroethylene, vinyl fluoride, vinylidene fluoride, or two or more monomers thereof. For example, the fluorine-based polymer may include polymers such as polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

[0096] The coating layer 500 may be formed by coating a fluorine-based polymer on the gas discharge portion of the lead film 400 through spray coating or vapor deposition, but the method of forming the coating layer 500 on the gas discharge portion of the lead film 400 is not limited thereto.

[0097] Reference Figure 5, the recessed portion 450 may include a first recessed portion 451 and a second recessed portion 455, and the width of the second recessed portion 455 may be greater than the width of the first recessed portion 451. In the present specification, the width of the second recessed portion 455 refers to the maximum value of the distance between one end and the other end of the second recessed portion 455 in a direction orthogonal to the protruding direction of the electrode lead 300, and the width of the first recessed portion 451 refers to the maximum value of the distance between one end and the other end of the first recessed portion 451 in a direction orthogonal to the protruding direction of the electrode lead 300.

[0098] When the recess 450 includes a first recess 451 and a second recess 455 having different widths, the curvature of the lead film 400 that expands outward due to pressure when gas is introduced from the relatively narrow first recess 451 is smaller than the curvature of the lead film 400 that expands due to pressure when gas is introduced from the relatively wide second recess 455, and thus the stress applied to the interface between the lead film 400 and the electrode lead 300 is smaller, and thus the durability of the lead film 400 can be more easily improved.

[0099] Reference Figure 5 , the second recessed portion 455 may be located at a position farther away from the portion accommodating the electrode assembly 110 than the first recessed portion 451. At this time, the second recessed portion 455 may be used to discharge the gas generated inside the battery housing 200 to the outside of the battery housing 200, and since the width of the second recessed portion 455 is wider than the width of the first recessed portion 451, the area of ​​the gas discharged to the outside is further increased, so it is easier to increase the gas discharge amount. In addition, the relatively narrow first recessed portion 451 can be used as a channel for the gas generated inside the battery housing 200 to be introduced into the recessed portion 450, and the durability of the lead film 400 can be increased.

[0100] Reference Figure 5 , a portion of the first recessed portion 451 may be located at a position corresponding to the sealing portion 250. For example, a portion of the first recessed portion 451 may be located at a position corresponding to the sealing portion 250, and the second recessed portion 451 may be located farther away from a portion where the electrode assembly 110 is accommodated than the first recessed portion 451.

[0101] Reference Figure 5 , a portion of the second recessed portion 455 may be located at a position not corresponding to the sealing portion 250. For example, when the second recessed portion 455 is located farther from the portion where the electrode assembly 110 is accommodated than the first recessed portion 451, a portion of the second recessed portion 455 may be located at a position not corresponding to the sealing portion 250.

[0102] In this case, as the area of ​​the second recessed part 455 not corresponding to the sealing part 250 increases, the area in which the gas inside the battery case 200 is discharged to the outside of the battery case 200 may increase.

[0103] In an embodiment of the present disclosure, the width of the lead film 400 may be greater than the width of the sealing portion 250, but may be less than the length of the electrode lead 300. In this specification, the width of the lead film 400 refers to the maximum value of the distance between one end and the other end of the lead film in the protruding direction of the electrode lead 300. The width of the sealing portion 250 refers to the maximum value of the distance between one end and the other end of the sealing portion 250 in the protruding direction of the electrode lead 300. The length of the electrode lead 300 refers to the maximum value of the distance between one end and the other end of the electrode lead 300 in the protruding direction of the electrode lead 300. In this case, the second recessed portion 455 may be located between the end of the sealing portion 250 and the end of the lead film 400. For example, the second recessed portion 455 may be located as a whole at a position that does not correspond to the sealing portion 250.

[0104] In the lead film 400 , the recessed portion 450 may be formed in various shapes.

[0105] Reference Figure 5 , the first recessed portion 451 may extend along the protruding direction of the electrode lead 300, and the second recessed portion 455 may extend along the length direction of the sealing portion 250. In this specification, the length direction of the sealing portion 250 refers to a direction orthogonal to the protruding direction of the electrode lead 300. However, the shape of the recessed portion 450 is not limited to the above shape, and the recessed portion 450 may be formed in an appropriate shape within the lead film 400.

[0106] Reference Figure 5 , one end of the first recessed portion 451 is open to the outside of the battery case 200, and the other end of the first recessed portion 451 may be connected to the second recessed portion 455. More specifically, the first recessed portion 451 and the second recessed portion 455 may be formed integrally with each other. That is, the second recessed portion 455 may be used as a gas outlet for the gas introduced into the recessed portion 450 to be discharged to the outside, and the first recessed portion 451 is used as a gas inlet for the gas generated in the battery case 200 to be introduced.

[0107] Reference Figure 5 , the coating 500 may be located on the second recessed portion 455. As another example, the coating 500 may also be located on the boundary line between the first recessed portion 451 and the second recessed portion 455. Since the second recessed portion 455 is used as a gas outlet for the gas inside the battery to be discharged to the outside, when the coating 500 is located on the second recessed portion 455, the amount of moisture permeation into the battery cell can be more easily reduced without affecting the external discharge amount of the gas.

[0108] More specifically, the coating layer 500 may extend along the length direction of the second recessed portion 455. Here, the length of the second recessed portion 455 refers to the maximum value of the distance between one end and the other end of the second recessed portion 455 in a direction orthogonal to the protruding direction of the electrode lead 300. In addition, the length of the coating layer 500 may be equal to or greater than the length of the second recessed portion 455. In the present specification, the length of the coating layer 500 may refer to the maximum value of the distance between one end and the other end of the coating layer 500 in a direction orthogonal to the protruding direction of the electrode lead 300.

[0109] In addition, the width of the coating layer 500 may be equal to or greater than the width of the second recessed portion 455. Here, the width of the second recessed portion 455 refers to the maximum value of the distance between one end and the other end of the second recessed portion 455 in the protruding direction of the electrode lead 300. The width of the coating layer 500 refers to the maximum value of the distance between one end and the other end of the coating layer 500 in the protruding direction of the electrode lead 300.

[0110] However, the size of the coating layer 500 is not limited to the above-mentioned size, and the coating layer 500 may be formed in an appropriate size within the lead film 400 .

[0111] Reference Figure 5 , the recessed portion 450 may be formed at various positions based on the electrode lead 300 .

[0112] For example, Figure 5 As shown in (a), in the lead film 400, the recessed portion 450 may be located on the electrode lead 300. More specifically, the recessed portion 450 may be formed at a position corresponding to the center of the electrode lead 300.

[0113] As another example, Figure 5 As shown in (b), the length of the lead film 400 may be greater than the width of the electrode lead 300, and the recessed portion 450 may be located between the end of the electrode lead 300 and the end of the lead film 400. In this specification, the length of the lead film 400 refers to the maximum value of the distance between one end and the other end of the lead film 400 in a direction orthogonal to the protruding direction of the electrode lead 300, and the width of the electrode lead 300 refers to the maximum value of the distance between one end and the other end of the electrode lead 300 in a direction orthogonal to the protruding direction of the electrode lead 300. In other words, in the lead film 400, the recessed portion 450 may be formed at a position avoiding the electrode lead 300. However, the position of the recessed portion 450 is not limited to the above position, and the recessed portion 450 may be formed at an appropriate position within the lead film 400.

[0114] Therefore, the durability and airtightness of the lead film 400 can be controlled by adjusting the position where the recess 450 is formed on the lead film 400. In addition, if necessary, the size of the recess 450 can be adjusted according to the position of the recess 450, thereby simplifying the manufacturing process and reducing costs.

[0115] Reference Figure 5 , the end of the lead film 400 opened toward the inside of the recessed portion 450 is formed adjacent to the end of the lead film 400, and the end of the lead film 400 recessed toward the outside may be located between the end of the sealing portion 250 and the end of the lead film 400. In addition, the end of the recessed portion 450 recessed toward the outside may be spaced apart from the end of the sealing portion 250 by a predetermined distance or may be located adjacent thereto.

[0116] Figure 6 It shows that according to Figure 5 (a) is an enlarged view of the electrode lead portion at the position of the sealing portion.

[0117] As an example, compare Figure 6 (a) and Figure 6 (b) It can be confirmed that even if the position where the sealing portion 250 contacts the lead film 400 is changed, it has no influence on the end of the recessed portion 450 that is recessed toward the outside.

[0118] Therefore, in the present embodiment, within the error range according to the positions of the lead film 400 and the sealing portion 250 generated during the sealing process, the end of the recessed portion 450 that is recessed toward the outside can be uniformly maintained in the area located outside the battery case 200, and the area where the gas in the battery case 200 can be introduced and discharged to the outside of the recessed portion 450 can also be maintained uniform. Therefore, there is an advantage that the gas discharge effect of the recessed portion 450 can be maintained.

[0119] Figure 7 is along Figure 1 A cross-sectional view taken along the a-a' axis.

[0120] Reference Figure 7 , the gas generated inside the battery cell 100 may be discharged to the recessed portion 450 of the lead film 400 . Here, since the recessed portion 450 is open to the inside, the pressure inside the recessed portion 450 may be the same as the pressure inside the battery case 200 .

[0121] The pressure inside the recessed portion 450 is higher than the pressure outside the battery cell 100, and the resulting pressure difference can act as a driving force for the gas. Therefore, the gas introduced into the recessed portion 450 can be easily discharged to the outside. In addition, the external discharge amount of the gas generated inside the battery cell 100 can also be increased. At this time, the gas generated inside the battery case 200 can be discharged along the Z-axis direction through the recessed portion 450 and the lead film 400 covering the upper surface of the recessed portion.

[0122] Reference Figure 7 , the gas discharge portion of the lead film 400 may be located outside the outer surface of the battery case 200. In this specification, the outer surface of the battery case 200 refers to the end of the sealing portion 250 of the battery case 200 outside the battery.

[0123] In addition, the end of the recessed portion 450 opened toward the inside of the battery case 200 may be located further inside than the inner surface of the battery case 200. In this specification, the inner surface of the battery case 200 refers to the end of the sealing portion 250 of the battery case 200 inside the battery.

[0124] Therefore, the lead film 400 may maximize the area of ​​the recessed portion 450 , thereby maximizing the permeation area of ​​the gas generated inside the battery case 200 , so that a large amount of gas may be discharged.

[0125] For example, when the recessed end of the recessed portion 450 is positioned further outward than the outer surface of the battery case 200 , gas may be discharged from the recessed portion 450 along the Z-axis direction through the lead film 400 between the recessed end of the recessed portion 450 and the outer surface of the battery case 200 .

[0126] In one embodiment of the present disclosure, the air permeability of the lead film 400 at 60°C may be 20 Barrer to 60 Barrer, or 30 Barrer to 40 Barrer. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above range. In addition, based on a thickness of 200 μm of the lead film 400, the air permeability at 60°C may satisfy the above range. If the air permeability of the lead film 400 satisfies the above range, the gas generated inside the secondary battery can be more effectively discharged.

[0127] In this specification, air permeability may be measured by ASTM F2476-20.

[0128] In one embodiment of the present disclosure, under the conditions of 25°C and 50% RH, the moisture permeability of the lead film 400 may be 0.02g to 0.2g, or 0.02g to 0.04g, or 0.06g or 0.15g for 10 years. If the moisture permeability of the lead film 400 satisfies the above range, moisture can be more effectively prevented from penetrating from the lead film 400.

[0129] In an embodiment of the present disclosure, the lead film 400 may have an air permeability of 20 to 60 Barrer at 60° C., and a moisture permeability of 0.02 to 0.2 g at 25° C. and 50% RH for 10 years. When the air permeability and moisture permeability of the lead film 400 meet the above ranges, moisture can be more effectively prevented from penetrating from the outside while discharging gas generated inside the battery.

[0130] The moisture permeability of the lead film 400 may be measured by adopting the ASTM F1249 method. At this time, the moisture permeability may be measured using an apparatus officially certified by MCOON.

[0131] In an embodiment of the present disclosure, the lead film 400 may include a polyolefin-based resin. For example, the lead film 400 may include a polyolefin-based resin that satisfies the above-mentioned air permeability value and / or moisture permeability value. The polyolefin-based resin may include one or more materials selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). The lead film 400 includes polypropylene, and the air permeability of the lead film 400 may be 20 Barrer to 60 Barrer at 60°C. In addition, the moisture permeability may be 0.06g to 0.15g. In this case, the gas generated inside the battery is more effectively discharged, and moisture can be easily prevented from penetrating from the outside.

[0132] In addition, since the lead film 400 is made of the above-mentioned material, the lead film 400 can maintain the airtightness of the battery cell 100 and prevent leakage of the internal electrolyte.

[0133] Reference Figure 7 , the coating layer 500 is located on the gas discharge portion of the lead film 400. The coating layer 500 is located on the gas discharge portion of the lead film 400 and can reduce the amount of moisture permeation from the outside of the battery to the inside of the battery, while having little effect on the discharge of gas from the inside of the battery to the outside of the battery.

[0134] Reference Figure 7 , the thickness H of the upper surface of the lead film 400 covering the recessed portion 450 may be 100 μm to 300 μm, or 100 μm to 200 μm. When the thickness H of the upper surface of the lead film 400 covering the recessed portion 450 satisfies the above range, the gas inside the battery housing 200 can be more easily discharged to the outside. In this specification, the upper surface of the recessed portion 450 refers to the lead film 400 between the recessed portion 450 and the electrode lead 300.

[0135] Reference Figure 7, based on the protruding direction of the electrode lead 300, the width W of the front surface of the lead film 400 covering the recessed portion 450 may be 2 mm or more, or 2 mm to 3 mm. In this specification, the width of the front surface of the lead film 400 surrounding the recessed portion 450 refers to the maximum value of the distance between the recessed end of the recessed portion 450 and the outer end of the battery case 200 of the lead film 400. When the width W of the front surface of the lead film 400 surrounding the recessed portion 450 satisfies the above range, it is easier to prevent the lead film 400 from being torn during the process of discharging the gas generated inside the battery case 200 to the outside.

[0136] A battery module according to another embodiment of the present disclosure includes the above-mentioned battery cell. Meanwhile, one or more battery modules according to the present embodiment may be packaged in a battery pack case to form a battery pack.

[0137] The battery module and the battery pack including the battery module can be applied to various devices. These devices can be transportation tools such as electric bicycles, electric vehicles, hybrid electric vehicles, etc., but the present disclosure is not limited thereto, and the present disclosure can be applied to various devices that can use the battery module and the battery pack including the battery module, which also fall within the scope of the present disclosure.

[0138] Although the preferred embodiments of the present disclosure are described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure defined in the appended claims also fall within the scope of the present disclosure.

[0139] Description of Reference Numerals

[0140] 100: Battery cell

[0141] 110: Electrode assembly

[0142] 200: Battery housing

[0143] 210: Accommodation

[0144] 250: Sealing part

[0145] 300: Electrode lead

[0146] 400: Lead film

[0147] 410: Inner layer

[0148] 450: Depression

[0149] 451: First recessed portion

[0150] 455: Second recessed portion

[0151] 500: Coating

Claims

1. A battery cell, comprising: A battery case having a housing portion and a sealing portion, wherein the electrode assembly is mounted in the housing portion and the sealing portion is formed by sealing the outer periphery of the housing portion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding to the outside of the battery case through the sealing portion; as well as a lead film located at a portion corresponding to the sealing portion in at least one of the upper portion and the lower portion of the electrode lead, wherein the lead film has a recessed portion that is recessed in an outward direction of the battery housing and opens toward the interior of the battery housing, and The battery cell includes a coating layer on a gas discharge portion of the lead film and including a fluorine-based polymer.

2. The battery cell according to claim 1, wherein: The gas discharge portion of the lead film is located outside the outer surface of the battery case.

3. The battery cell according to claim 1, wherein: The recessed portion includes a first recessed portion and a second recessed portion, and The width of the second recessed portion is greater than the width of the first recessed portion.

4. The battery cell according to claim 3, wherein: The second recessed portion is located at a position farther from a portion accommodating the electrode assembly than the first recessed portion.

5. The battery cell according to claim 3, wherein: A portion of the first recessed portion is located in a region corresponding to the sealing portion.

6. The battery cell according to claim 3, wherein: A portion of the second recessed portion is located in a region not corresponding to the sealing portion.

7. The battery cell according to claim 3, wherein: An end portion of the second recessed portion outside the battery case is located outside the outer surface of the battery case.

8. The battery cell according to claim 3, wherein: The second recessed portion is located between an end portion of the sealing portion and an end portion of the lead film.

9. The battery cell according to claim 3, wherein: The coating is located on the second recessed portion.

10. The battery cell according to claim 3, wherein: The first recessed portion extends along a protruding direction of the electrode lead, and The second recessed portion extends along a length direction of the sealing portion.

11. The battery cell according to claim 1, wherein: The fluorine-based polymer includes a polymer including a repeating unit derived from tetrafluoroethylene, vinyl fluoride, vinylidene fluoride, or two or more monomers thereof.

12. The battery cell according to claim 1, wherein: The thickness of the coating is 0.1 μm to 2 mm.

13. The battery cell according to claim 1, wherein: Based on the protruding direction of the electrode lead, the inner surface of the recessed portion is closed.

14. The battery cell according to claim 13, further comprising: An inner layer is configured to cover at least one of the inner surfaces of the recessed portion of the lead film.

15. The battery cell according to claim 14, wherein: The material of the inner layer has a higher melting point than the material of the lead film, and the material of the inner layer does not react with an electrolyte.

16. The battery cell according to claim 1, wherein: The lead film includes a polyolefin-based material.

17. The battery cell according to claim 15, wherein: The inner layer includes at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material.

18. The battery cell according to claim 1, wherein: The recessed portion is located on the electrode lead.

19. The battery cell according to claim 1, wherein: The length of the lead film is greater than the width of the electrode lead.

20. The battery cell according to claim 19, wherein: The recessed portion is located between an end portion of the electrode lead and an end portion of the lead film.

21. The battery cell according to claim 1, wherein: An end portion of the recessed portion that is open toward the interior of the battery case is located further inward than an inner surface of the battery case.

22. The battery cell according to claim 1, wherein: The width of a portion of the lead film covering the front surface of the recessed portion is 2 mm or more based on a protruding direction of the electrode lead.

23. The battery cell according to claim 1, wherein: A portion of the lead film covering an upper surface of the recessed portion has a thickness of 100 μm to 300 μm.

24. The battery cell according to claim 1, wherein: The lead film has an air permeability of 20 Barrer to 60 Barrer at 60°C.

25. The battery cell according to claim 1, wherein: The moisture permeability of the lead film is 0.02 g to 0.2 g over 10 years under the conditions of 25° C. and 50% RH. 26 . A battery module comprising the battery cell according to claim 1 .

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