Battery cell and battery module including same

Abstract

According to one aspect of the present invention, a battery cell includes a battery case including a storage portion in which an electrode assembly is attached and a sealing portion formed by sealing an outer periphery of the storage 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 on at least one of an upper and lower portion of the electrode lead, a gas exhaust guide portion being inserted into the lead film, and the battery case includes a cover portion extending from the sealing portion, the cover portion being located on the lead film and protruding to the outside of the battery case.

Description

[Technical field]

[0001] The present invention relates to a battery cell and a battery module including the same, and more particularly to a battery cell with improved insulation performance and gas discharge performance and a battery module including the same. This application claims priority based on Korean Patent Application No. 10-2021-0088729 filed on July 6, 2021 and Korean Patent Application No. 10-2022-0081995 filed on July 4, 2022, and the contents disclosed in the specification and drawings of said applications are incorporated herein in their entirety. [Background technology]

[0002] As technological development and demand for mobile devices increases, the demand for secondary batteries as energy sources is rapidly increasing. In particular, secondary batteries are attracting much attention as energy sources for mobile devices such as mobile phones, digital cameras, laptops, and wearable devices, as well as for power devices such as electric bicycles, electric cars, and hybrid electric cars.

[0003] Such secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, according to the shape of the battery case. Here, the electrode assembly housed in the battery case is a power generating element that includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode and is capable of charging and discharging, and is classified into a jelly roll type in which a separator is interposed between a long sheet-type positive electrode and a negative electrode coated with an active material and wound up, and a stack type in which a plurality of positive electrodes and negative electrodes are stacked in sequence with a separator interposed between them.

[0004] Among these, pouch-type batteries, which have a structure in which a stacked or stacked / folded electrode assembly is housed in a pouch-type battery case made of an aluminum laminate sheet, are increasingly being used due to their low manufacturing cost, light weight, and ease of deformation.

[0005] FIG. 1 is a top view of a conventional battery cell, and FIG. 2 is a cross-sectional view taken along line a-a' of FIG.

[0006] 1 and 2, a conventional battery cell 10 includes a battery case 20 in which an electrode assembly 11 is housed in a housing 21 and the outer periphery is sealed by a sealing portion 25. The battery cell 10 also includes an electrode lead 30 that is electrically connected to an electrode tab 15 included in the electrode assembly 11 and protrudes to the outside of the battery case 20 through the sealing portion 25, and a lead film 40 is located between the upper and lower parts of the electrode lead 30 and the sealing portion 25.

[0007] However, in recent years, as the energy density of a battery cell increases, the amount of gas generated inside the battery cell also increases. In the case of a conventional battery cell 10, since no components capable of discharging gas generated inside the battery cell are included, there is a risk of a venting phenomenon occurring in which the battery case 20 bursts due to gas generation during long-term storage. Furthermore, a battery cell damaged by the venting phenomenon may allow moisture to penetrate into the inside, causing side reactions that lead to a decrease in battery performance and additional gas generation. Thus, there is an increasing need to develop a battery cell with improved ability to discharge gas generated inside the battery cell to the outside. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a battery cell having improved insulation performance and gas discharge performance, and a battery module including the same.

[0009] The problems to be solved by the present invention are not limited to the problems described above, and problems not mentioned will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. [Means for solving the problem]

[0010] According to one aspect of the present invention, a battery cell includes a battery case including a storage portion in which an electrode assembly is attached and a sealing portion formed by sealing an outer periphery of the storage 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 on at least one of an upper and lower portion of the electrode lead, a gas exhaust guide portion being inserted into the lead film, and the battery case includes a cover portion extending from the sealing portion, the cover portion being located on the lead film and protruding to the outside of the battery case.

[0011] The cover portion may be positioned on the gas exhaust guide portion.

[0012] The length of the cover part may be equal to or longer than the length of the gas discharge guiding part in a direction perpendicular to the protruding direction of the electrode lead.

[0013] The length of the cover part may be equal to or shorter than the length of the lead film in a direction perpendicular to the protruding direction of the electrode leads.

[0014] The gas discharge guide portion may be located at a portion corresponding to the center of the cover portion.

[0015] An end of the cover may be located outside an end of the lead film based on a protruding direction of the electrode lead.

[0016] Based on a protruding direction of the electrode lead, an end of the electrode lead may be located outside an end of the cover part.

[0017] The cover portion may be bent in a direction away from the lead film with respect to the sealing portion.

[0018] The gas discharge guiding portion may extend along a protruding direction of the electrode lead, and an end of the gas discharge guiding portion adjacent to an outside of the battery case may be covered with the lead film.

[0019] An end of the gas discharge guide portion adjacent to the inside of the battery case may be exposed to the inside of the battery case.

[0020] A gas exhaust path may be formed at an interface between the gas exhaust guide portion and the lead film.

[0021] An adhesive strength between the gas exhaust guide portion and the lead film may be smaller than an adhesive strength between the lead film and an electrode lead or an adhesive strength between the lead film and the sealing portion.

[0022] The gas discharge guide portion may be a film layer made of at least one of polyimide and polyethylene terephthalate.

[0023] The gas discharge guide portion may be a coating layer made of a liquid resin.

[0024] The gas exhaust guide may further include a getter material including at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO2), barium oxide (BaO), barium (Ba), and calcium (Ca).

[0025] The gas discharge guide may be located on the electrode lead, and an adhesive layer may be formed between the gas discharge guide and the electrode lead.

[0026] An adhesive strength between the gas discharge guide portion and the lead film may be smaller than an adhesive strength between the adhesive layer and the gas discharge guide portion and an adhesive strength between the adhesive layer and the electrode lead.

[0027] The adhesive layer may consist of an adhesive tape or an adhesive binder.

[0028] The gas permeability of the lead film may be 20 to 60 barrers at 60°C.

[0029] The lead film may have a moisture permeation amount of 0.02 g to 0.2 g over 10 years at 25° C. and 50% RH.

[0030] The gas discharge guide portion may have a gas permeability of 40 barrer or more at 60°C.

[0031] A battery module according to another aspect of the present invention includes the above-described battery cells. Effect of the Invention

[0032] According to one embodiment of the present invention, a battery cell including a cover part in which a battery case extends from a sealing part and is positioned on a lead film, and a battery module including the same are provided, thereby improving insulation performance and gas discharge performance.

[0033] Specifically, according to one embodiment of the present invention, a gas exhaust path can be formed at the interface between the gas exhaust guide portion and the lead film, making the manufacturing process relatively easy and allowing gas within the battery cell to be effectively exhausted to the outside.

[0034] According to another embodiment of the present invention, since the cover is located outside the end of the lead film, the insulating performance for the end face of the cover can be improved. Even if a crack occurs in the gas exhaust path due to an increase in internal pressure of the battery case, the end face of the cover is located outside the gas exhaust path and does not come into contact with the electrolyte leaking to the outside of the gas exhaust path, thereby improving the insulating performance.

[0035] According to another embodiment of the present invention, the shape of the gas discharge guide portion can be adjusted to control the gas discharge performance of the gas discharge guide portion and the durability and airtightness of the lead film. Also, the shape of the gas discharge guide portion can be changed as necessary to simplify the manufacturing process and reduce costs.

[0036] According to yet another embodiment of the present invention, by setting the gas permeability and moisture penetration amount of the lead film within a predetermined range, it is possible to more effectively prevent moisture penetration from the outside while still allowing gas generated inside the battery cell to be discharged.

[0037] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from this specification and the accompanying drawings. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a top view of a conventional battery cell. [Diagram 2] FIG. 2 is a cross-sectional view taken along line a-a' in FIG. [Diagram 3] FIG. 2 is a top view of a battery cell according to one embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged view of the area surrounded by the two-dot chain line in FIG. [Diagram 5] FIG. 4 is a cross-sectional view taken along line AA' in FIG. [Figure 6] 11A to 11C are diagrams showing various shapes of the gas discharge guide portion; [Figure 7] 6 is an enlarged view of the area enclosed by the two-dot chain line in FIG. 5. [Figure 8] 8 is a diagram showing a gas discharge path formed at the interface between the lead film and the gas discharge guide portion in FIG. 7. FIG. [Figure 9] 9 is a diagram showing a state in which an electrolyte leaks due to a crack that has occurred in a part of the gas exhaust path in FIG. 8. FIG. [Figure 10] 4 is a cross-sectional view taken along line AA' of FIG. 3, showing a battery cell according to another embodiment of the present invention. [Figure 11]11 is an enlarged view of the area enclosed by the two-dot chain line in FIG. 10. FIG. [Figure 12] 12 is a diagram showing a gas discharge path formed at the interface between the lead film and the gas discharge guide portion in FIG. 11. FIG. [Figure 13] 13 is a diagram showing a state in which an electrolyte leaks due to a crack that has occurred in a part of the gas exhaust path in FIG. 12. FIG. [Figure 14] FIG. 2 is a cross-sectional view taken along line aa' in FIG. 1 in a comparative example. [Figure 15] 15 is an enlarged view of the region enclosed by the two-dot chain line in FIG. 14, showing how the electrolyte leaks due to a crack that has occurred in a part of the gas exhaust path in FIG. 14. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may, however, be embodied in various different forms and should not be construed as limited to the embodiments set forth herein.

[0040] In order to clearly describe the present invention, parts that are not relevant to the description will be omitted, and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0041] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not limited by the drawings. In the drawings, thicknesses are enlarged to clearly show various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0042] Furthermore, throughout the specification, when a part is described as "comprising" a certain component, this does not mean that other components are excluded, but that other components may also be included, unless otherwise specified.

[0043] Furthermore, throughout the specification, a "plan view" means a view of the subject part viewed from above, and a "cross-sectional view" means a view of a vertical cross-section of the subject part viewed from the side.

[0044] Hereinafter, a battery cell according to an embodiment of the present invention will be described. However, the description will be made based on one end of the battery cell, but the present invention is not limited thereto, and the same or similar description may be applied to the other end of the battery cell.

[0045] FIG. 3 is a top view of a battery cell according to one embodiment of the present invention.

[0046] The battery cell 100 according to an embodiment of the present invention includes a battery case 200 including a storage section 210 to which an electrode assembly 110 is attached and a sealing section 250 formed by sealing the outer periphery of the storage section 210, an electrode lead 300 electrically connected to an electrode tab 150 included in the electrode assembly 110 and protruding to the outside of the battery case 200 through the sealing section 250, and a lead film 400 located at a portion corresponding to the sealing section 250 at at least one of the upper and lower parts of the electrode lead 300. For example, the battery cell 100 may be a substantially rectangular plate-shaped cell by having a long side in the X-axis direction and a short side in the Y-axis direction, and being formed shorter in the Z-axis direction than the length of the X-axis or Y-axis. The electrode lead 300 may be formed on the short side of the battery cell 100. Such a battery cell 100 is an efficient structure for increasing energy density by integrating in the Z-axis direction and stacking a plurality of battery cells 100 face-to-face.

[0047] The electrode assembly 110 may have a jelly roll type (wound type), a laminate type (stack type), or a composite type (lamination / folding type) structure. More specifically, the electrode assembly 110 may include a positive electrode, a negative electrode, and a separator disposed therebetween.

[0048] The electrode lead 300 is electrically connected to the electrode tab 150 included in the electrode assembly 110, and protrudes to the outside of the battery case 200 through the sealing part 250. In addition, the lead film 400 is located at a portion corresponding to the sealing part 250 on at least one of the upper and lower parts of the electrode lead 300. Thus, the lead film 400, together with the sealing part 250, can prevent a short circuit from occurring in the electrode lead 300 during heat fusion or press fusion, and can improve the sealing property between the sealing part 250 and the electrode lead 300.

[0049] 3, the lead film 400 may have a width wider than that of the electrode lead 300. Here, the width of the lead film 400 means the maximum distance between one end and the other end of the lead film 400 in a direction (Y-axis direction) perpendicular to the protruding direction of the electrode lead 300 (X-axis direction), and the width of the electrode lead 300 means the maximum distance between one end and the other end of the electrode lead 300 in a direction perpendicular to the protruding direction of the electrode lead 300.

[0050] The lead film 400 may have a length longer than the sealing portion 250 and shorter than the electrode lead 300 based on the protruding direction of the electrode lead 300. Here, the length of the lead film 400 means the maximum value of the distance between one end and the other end of the lead film 400 in the protruding direction of the electrode lead 300. The length of the sealing portion 250 means 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 means 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. Thus, the lead film 400 does not interfere with the electrical connection of the electrode lead 300 and can prevent the side of the electrode lead 300 from being exposed to the outside.

[0051] The battery case 200 may be made of a laminate sheet including a resin layer and a metal layer. More specifically, the battery case 200 may be made of a laminate sheet and may be composed of an outer resin layer forming the outermost shell, a barrier metal layer preventing the passage of substances, and an inner resin layer for sealing. For example, the barrier metal layer may be made of an aluminum material.

[0052] Here, the battery case 200 may be manufactured by cutting the laminate sheet into a predetermined shape, and end surfaces of the outer resin layer, the barrier metal layer, and the inner resin layer may be exposed to the outside at the edge of the battery case 200. Here, the cutting method may be, but is not limited to, laser cutting, knife cutting, die punching, or the like, and a cutting method generally used when cutting a laminate sheet may also be included in this embodiment.

[0053] However, in the battery case 200, the barrier metal layer exposed at the edge of the battery case 200 may form an electric circuit and cause a fire if it comes into contact with an external substance or an electrolyte. Therefore, in this embodiment, it is necessary to ensure insulation for the barrier metal layer exposed at the edge of the battery case 200.

[0054] 4 is an enlarged view of the region enclosed by the two-dot chain line in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line AA' in FIG.

[0055] 4 and 5, in this embodiment, a gas discharge guide portion 450 is inserted into a lead film 400, and the battery case 200 may include a cover portion 270 extending from a sealing portion 250.

[0056] Here, the sealing part 250 and the cover part 270 may be integrated with each other. More specifically, in the battery case 200, the sealing part 250 may be formed between the storage part 210 and the cover part 270 by heat sealing or press sealing the storage part 210 and the cover part 270.

[0057] In addition, the cover part 270 may extend from the sealing part 250 and protrude to the outside of the battery case 200. More specifically, the cover part 270 may extend from the sealing part 250 located on the lead film 400. That is, the cover part 270 may be located on the lead film 400. Here, based on the sealing part 250, the cover part 270 may extend in the same direction as the direction in which the lead film 400 protrudes to the outside of the battery case 200.

[0058] Also, the cover portion 270 may be positioned on the gas discharge guiding portion 450. More specifically, the cover portion 270 may be positioned on the gas discharge guiding portion 450 with the lead film 400 interposed therebetween. In other words, the cover portion 270 may be positioned at a portion of the lead film 400 corresponding to a portion where the gas discharge guiding portion 450 is positioned. That is, the cover portion 270 may cover a portion of the lead film 400 where the gas discharge guiding portion 450 is positioned. When cutting the battery case 200, the cover portion 270 may be cut so as to be longer in the X-axis direction than the sealing portion 250, thereby providing the cover portion 270 that covers the portion where the gas discharge guiding portion 450 is positioned.

[0059] As an example, the gas discharge guiding portion 450 may be located at a portion corresponding to the center of the cover portion 270. In other words, the center line of the gas discharge guiding portion 450 and the center line of the cover portion 270 may coincide with each other.

[0060] As configured above, in this embodiment, the cover portion 270 is positioned on the gas discharge guide portion 450 of the lead film 400, and thus it is possible to cover the portion of the gas discharge path formed by the lead film 400 and the gas discharge guide portion 450 that is exposed to the outside of the battery case 200. In other words, the cut surface of the battery case 200 covers the gas discharge path portion.

[0061] 4, the length of the cover part 270 may be equal to or longer than the length of the gas exhaust guiding part 450 in a direction perpendicular to the protruding direction of the electrode lead 300. Here, the length of the cover part 270 means the maximum distance between one end and the other end of the cover part 270 in a direction perpendicular to the protruding direction of the electrode lead 300. The length of the gas exhaust guiding part 450 means the maximum distance between one end and the other end of the gas exhaust guiding part 450 in a direction perpendicular to the protruding direction of the electrode lead 300.

[0062] As a result, the cover portion 270 can cover the entire portion of the gas discharge guiding portion 450 in the lead film 400 that is located outside the battery case 200. In other words, the entire portion of the gas discharge path formed by the lead film 400 and the gas discharge guiding portion 450 that is exposed to the outside of the battery case 200 can be effectively covered.

[0063] As an example, the length of the cover part 270 may be equal to or shorter than the length of the lead film 400 with respect to a direction perpendicular to the protruding direction of the electrode lead 300. Here, the length of the lead film 400 means the maximum distance between one end and the other end of the lead film 400 in a direction perpendicular to the protruding direction of the electrode lead 300. That is, the cover part 270 may cover a part or the entirety of the portion where the lead film 400 is located.

[0064] As configured above, in this embodiment, the cover portion 270 has a size similar to that of the lead film 400, thereby effectively covering the portion where the gas discharge guide portion 450 is located while improving the space efficiency of the battery cell 100.

[0065] However, the size of the cover part 270 is not limited thereto, and any size that covers the portion where the gas discharge guide part 450 is located as described above can be included in this embodiment.

[0066] 4 and 5, with respect to the protruding direction of the electrode lead 300 as a reference, the end of the cover part 270 may be located outside the end of the lead film 400. In other words, the end of the cover part 270 extends from the sealing part 250 and may extend in a direction toward the outside beyond the end of the lead film 400.

[0067] More specifically, the cover part 270 may be bent in a direction (Z-axis direction) away from the lead film 400 with respect to the sealing part 250. Here, the angle at which the cover part 270 is bent with respect to the sealing part 250 may be an angle generated when the sealing part 250 is fused. However, the angle at which the cover part 270 is bent with respect to the sealing part 250 may be adjusted to be smaller or larger than the angle generated when the sealing part 250 is fused, as necessary.

[0068] In this embodiment, the cover portion 270 is positioned outside the end of the lead film 400, so that the insulating performance against the end face of the cover portion 270 can be improved. That is, even if a crack occurs in the gas exhaust path due to an increase in the internal pressure of the battery case 200, the end face of the cover portion 270 is positioned outside the gas exhaust path, so that it does not come into contact with the electrolyte leaking to the outside of the gas exhaust path, and thus the insulating performance can be improved. In other words, by cutting the battery case 200 long at the gas exhaust path portion, the cut surface of the battery case 200 sufficiently covers the gas exhaust path, and even if the electrolyte leaks, the barrier metal layer exposed on the cut surface of the battery case 200 does not come into contact with the leaked electrolyte, so that the insulating performance can be maintained without forming an electric circuit.

[0069] Furthermore, based on the protruding direction of the electrode lead 300, the end of the electrode lead 300 may be located outside the end of the cover part 270. In other words, the end of the cover part 270 extends from the sealing part 250 and may extend shorter than the end of the electrode lead 300.

[0070] Thus, in this embodiment, the end of the electrode lead 300 is located outside the end of the cover portion 270, so that the cover portion 270 improves the insulating performance while not interfering with the electrical connection between the electrode lead 300 and other components.

[0071] 4 and 5, the gas discharge guiding portion 450 may extend along the protruding direction of the electrode lead 300. More specifically, in the gas discharge guiding portion 450, an end portion of the gas discharge guiding portion 450 adjacent to the outside of the battery case 200 may be covered with the lead film 400. In other words, the end portion of the gas discharge guiding portion 450 adjacent to the outside of the battery case 200 is not exposed to the outside of the battery case 200.

[0072] In addition, the end of the gas discharge guiding portion 450 adjacent to the inside of the battery case 200 may be exposed to the inside of the battery case 200. In other words, the end of the gas discharge guiding portion 450 adjacent to the inside of the battery case 200 may be located on the same vertical line as the end of the lead film 400, or may be located more inward of the battery case 200 than the end of the lead film 400.

[0073] In this way, in the lead film 400, the end of the gas discharge guiding portion 450 adjacent to the outside of the battery case 200 is not exposed to the outside of the battery case 200, thereby improving the sealing force of the battery case 200 by the lead film 400 and the sealing portion 250. Furthermore, in the lead film 400, the end of the gas discharge guiding portion 450 adjacent to the inside of the battery case 200 is exposed to the inside of the battery case 200, so that gas generated in the battery cell 100 can easily flow into the gas discharge path formed by the gas discharge guiding portion 450 and can be effectively discharged to the outside.

[0074] 5, the thickness H (height in the Z-axis direction) of the lead film 400 on the upper surface of the gas discharge guide portion 450 may be 100 μm to 300 μm or 100 μm to 200 μm. When the thickness H of the lead film 400 satisfies the above-mentioned range, the gas inside the battery case 200 is more easily discharged to the outside.

[0075] 5, the width W of the lead film 400 covering the front surface of the gas discharge guide portion 450 based on the protruding direction of the electrode lead 300 may be 2 mm or more, or 2 mm to 3 mm. When the width W of the lead film 400 satisfies the above-mentioned range, the lead film 400 can be prevented from being broken in the process of gas generated inside the battery case 200 being discharged to the outside.

[0076] In addition, the thickness D of the gas discharge guiding part 450 may be 50 μm to 150 μm. When the thickness of the gas discharge guiding part 450 satisfies the above-mentioned range, the gas inside the battery case 200 can be more easily discharged to the outside. FIG. 6 shows various shapes of the gas discharge guiding part. The gas discharge guiding part 450 may be formed in a predetermined pattern to discharge the gas inside the battery case 200.

[0077] For example, the gas discharge guide portion 450 may have a rectangular shape extending along the protruding direction of the electrode lead 300 as shown in Fig. 4. However, without being limited thereto, the gas discharge guide portion 450 may have various shapes such as a circular shape as shown in Fig. 6(a), an elliptical shape as shown in Fig. 6(b), a linear shape, a curved shape, etc.

[0078] As another example, the gas discharge inducing part 450 may include a first gas discharge inducing part 450a extending along the protruding direction of the electrode lead 300 as shown in FIG. 6(c), and a second gas discharge inducing part 450b extending in a direction perpendicular to the protruding direction of the electrode lead 300. In particular, the first gas discharge inducing part 450a and the second gas discharge inducing part 450b may be connected to each other. Here, the second gas discharge inducing part 450b may be located outside the sealing part 250 and inside the lead film 400 with respect to the sealing part 250 as shown in FIG. 6(c), or may be located inside the sealing part 250 and outside the lead film 400 with respect to the sealing part 250 as shown in FIG. 6(d). Alternatively, the second gas discharge inducing part 450b may be located both outside and inside the lead film 400 with respect to the sealing part 250 as shown in FIG. 6(e). However, the gas exhaust guiding part 450 is not limited to the above-mentioned shape, and may be inserted into the lead film 400 in an appropriate shape. By adjusting the shape of the gas exhaust guiding part 450 inserted into the lead film 400 in this manner, it is possible to control the gas exhaust performance of the gas exhaust guiding part 450 and the durability and airtightness of the lead film 400. In addition, by changing the shape of the gas exhaust guiding part 450 as necessary, it is possible to simplify the manufacturing process and reduce costs.

[0079] 4, one gas exhaust guide portion 450 may be included in the lead film 400. As another example, a plurality of gas exhaust guide portions 450 may be inserted into the lead film 400 and positioned spaced apart from each other.

[0080] In this manner, by adjusting the number of gas exhaust guiding parts 450 inserted in the lead film 400, it is possible to control the gas exhaust performance of the gas exhaust guiding parts 450 and the durability and airtightness of the lead film 400. In addition, it is possible to simplify the manufacturing process and reduce costs by minimizing the number of gas exhaust guiding parts 450 as necessary.

[0081] FIG. 7 is an enlarged view of the area enclosed by the two-dot dashed line in FIG. 5, FIG. 8 is a view showing a gas exhaust path formed at the interface between the lead film and the gas exhaust guide portion in FIG. 7, and FIG. 9 is a view showing electrolyte leakage due to a crack that has occurred in part of the gas exhaust path in FIG. 8.

[0082] 7 and 8, in the present embodiment, a gas exhaust path may be formed at the interface between the gas exhaust guide 450 and the lead film 400. More specifically, as shown in FIGS. 7 and 8, the gas exhaust path may refer to a space that is separated from at least a portion of the interface between the gas exhaust guide 450 and the lead film 400 by the pressure of gas generated in the battery case 200. In FIG. 8, the gas movement path is indicated by a dotted arrow. That is, as shown in the dotted arrow direction in FIG. 8, the gas exhaust path may refer to a path through which gas flows into a space separated from the interface between the gas exhaust guide 450 and the lead film 400 and is exhausted to the outside.

[0083] Here, the adhesive strength between the gas discharge inducing unit 450 and the lead film 400 may be smaller than the adhesive strength between the lead film 400 and the electrode lead 300 or the adhesive strength between the lead film 400 and the sealing unit 250. More specifically, when the pressure inside the battery case 200 increases due to gas generated in the battery cell 100, the adhesive strength at the interface between the gas discharge inducing unit 450 and the lead film 400 is relatively smaller than the adhesive strength between the lead film 400 and other components, so that at least a portion of the interface between the gas discharge inducing unit 450 and the lead film 400 may be separated from each other due to the pressure of the gas generated in the battery cell 100, as shown in FIG.

[0084] That is, in this embodiment, due to the relatively low adhesive strength between the gas discharge guide portion 450 and the lead film 400, the gas discharge guide portion 450 and the lead film 400 are peeled off from each other, and the gas inside the battery cell 100 flows into the gas discharge passage formed at the interface between the gas discharge guide portion 450 and the lead film 400, and the gas moves along the gas discharge passage and is finally discharged through the lead film 400. The gas that has flowed into the gas discharge passage can be discharged to the outside due to the pressure difference with the outside.

[0085] However, the gas exhaust path may include not only the case where the interface between the upper surface of the gas exhaust guiding portion 450 and the lead film 400 and the interface between the lower surface of the gas exhaust guiding portion 450 and the lead film 400 are both separated as shown in FIG. 8, but also the case where the interface between the upper surface of the gas exhaust guiding portion 450 and the lead film 400 or the interface between the lower surface of the gas exhaust guiding portion 450 and the lead film 400 are separated.

[0086] As an example, the gas exhaust guiding unit 450 may be a film layer made of at least one of polyimide (PI) and polyethylene terephthalate (PET). As another example, the gas exhaust guiding unit 450 may be a coating layer made of liquid resin. However, the shape or material of the gas exhaust guiding unit 450 is not limited thereto, and any shape or material that provides a relatively lower adhesive strength at the interface between the gas exhaust guiding unit 450 and the lead film 400 than the adhesive strength between the lead film 400 and other components may be included in this embodiment.

[0087] As described above, in the battery cell according to this embodiment, a gas exhaust path can be formed at the interface between the gas exhaust guiding portion 450 and the lead film 400 due to the relatively low adhesive strength between the gas exhaust guiding portion 450 and the lead film 400, which not only makes the manufacturing process relatively easy but also enables the gas within the battery cell 100 to be effectively exhausted to the outside.

[0088] 4 and 5, one end of the gas discharge guiding part 450 may be located more inward than the inner surface of the sealing part 250 based on the protruding direction of the electrode lead 300. In this specification, the inner surface of the sealing part 250 means an end of the sealing part 250 adjacent to the inside of the battery case 200, and being located more inward than the inner surface of the sealing part 250 means being located more inward than the inner surface of the sealing part 250. When one end of the gas discharge guiding part 450 is located more inward than the inner surface of the sealing part 250, gas can easily flow into the gas discharge guiding part 450 without being interfered with by the sealing part 250.

[0089] In addition, the other end of the gas discharge guiding part 450 may be located outside the outer surface of the sealing part 250 based on the protruding direction of the electrode lead 300. In this specification, the outer surface of the sealing part 250 means the end of the sealing part 250 adjacent to the outside of the battery case 200, and located outside the outer surface of the sealing part 250 means located outside the battery case 200 than the outer surface of the sealing part 250. For example, a gap P is provided between the outer surface of the sealing part 250 and the other end of the gas discharge guiding part 450. In this way, when the other end of the gas discharge guiding part 450 is located outside the outer surface of the sealing part 250, the gas that has flowed into the gas discharge guiding part 450 can be more easily discharged to the outside. For example, the other end of the gas discharge guiding part 450 is not interfered with by the sealing part 250, and the gas that has flowed into the gas discharge guiding part 450 can be more easily discharged to the outside.

[0090] As a result, gas generated inside the battery cell 100 flows toward the gas discharge guiding portion 450, and the gas that has flowed into the gas discharge guiding portion 450 is smoothly discharged to the outside as shown in Fig. 8. In addition, the amount of gas generated inside the battery cell 100 that is discharged to the outside also increases. In this way, gas generated inside the battery case 200 can more easily flow into the gas discharge guiding portion 450, and can be more easily discharged to the outside of the gas discharge guiding portion 450.

[0091] Further, as shown in FIG. 8, the gas flowing into the gas discharge guiding portion 450 can be more easily discharged in the Z-axis direction through the lead film 400 on the gas discharge guiding portion 450. For example, when the other end of the gas discharge guiding portion 450 is located outside the outer surface of the sealing portion 250, the gas flowing into the gas discharge guiding portion 450 can be discharged in the Z-axis direction from the lead film 400 portion between the other end of the gas discharge guiding portion 450 and the outer surface of the sealing portion 250. As described above, the thickness H of the lead film 400 on the upper surface of the gas discharge guiding portion 450 can be 100 μm to 300 μm, and the width W of the lead film 400 covering the front surface of the gas discharge guiding portion 450 based on the protruding direction of the electrode lead 300 can be 2 mm or more or 2 mm to 3 mm. When the other end of the gas discharge guiding portion 450 is located outside the outer surface of the sealing portion 250 as described above, the gas can be discharged along the Z-axis direction, which is a relatively thin portion of the lead film 400, so that the gas can be more easily discharged. In this way, when discharging gas, if the entire gas discharge path is covered by the sealing part 250, the gas cannot be discharged smoothly. Therefore, by providing a gap P between the outer surface of the sealing part 250 and the other end of the gas discharge guide part 450 as described above, it is possible to facilitate the gas discharge.

[0092] 9, in the present embodiment, the gas discharge path formed at the interface between the gas discharge guide portion 450 and the lead film 400 may cause cracks in a portion of the lead film 400 after a certain period of time. More specifically, if gas inside the battery cell 100 continuously flows in and out of the gas discharge path, the end of the lead film 400 adjacent to the outside of the battery case 200 may become structurally weak. Even if the width W of the lead film 400 covering the front surface of the gas discharge guide portion 450 is set to 2 mm or more to prevent the lead film 400 from breaking, cracks may occur in the lead film due to continuous use of the battery cell 100. In such a case, the electrolyte 50 inside the battery cell 100 may leak out from the cracks.

[0093] 7 to 9, in the battery cell 100 according to this embodiment, the cover portion 270 may be located outside the end of the lead film 400, and the end of the cover portion 270 may be located outside the end of the gas exhaust path. As a result, in this embodiment, even if a crack occurs and the electrolyte 50 leaks, the electrolyte leaking to the outside of the gas exhaust path will not come into contact with the end face of the cover portion 270.

[0094] 9, even if electrolyte 50 leaks from a crack, the leaked electrolyte is located on the inner resin layer side of cover part 270 and is unlikely to reach the barrier metal layer exposed at the end face of cover part 270. In other words, the barrier metal layer exposed at the end face of cover part 270 does not come into contact with the electrolyte leaking to the outside of the gas exhaust path, preventing the formation of an electric circuit between the barrier metal layer and the electrolyte, thereby improving insulation performance and safety.

[0095] Also, the gas exhaust guiding unit 450 may further include a material having a function of absorbing or adsorbing moisture flowing in from the outside or hydrofluoric acid generated inside. More specifically, the gas exhaust guiding unit 450 may further include a getter material. Here, the getter material may mean a material that can be exhausted by using the action of gas being adsorbed by a chemically activated metal film. As an example, the getter material may include at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO2), barium oxide (BaO), barium (Ba), and calcium (Ca). As another example, the getter material may have a metal organic framework (MOF) structure. However, the getter material is not limited thereto and may include all types of materials generally classified as getter materials.

[0096] In this manner, in the present embodiment, the gas exhaust guiding unit 450 further includes a material capable of absorbing or adsorbing moisture or hydrofluoric acid, so that the gas exhaust guiding unit 450 can more easily exhaust gas generated inside the battery cell 100 to the outside while further minimizing the penetration of moisture or hydrofluoric acid flowing into the inside of the battery cell 100 from the outside of the battery cell 100.

[0097] In an embodiment of the present invention, the gas discharge guiding unit 450 may have a gas permeability of 40 barrer or more at 60° C. For example, the carbon dioxide permeability of the gas discharge guiding unit 450 may satisfy the above range.

[0098] For example, the gas discharge guide 450 may include at least one of polyolefin-based, fluorine-based, and porous ceramic-based materials that satisfy the above-mentioned gas permeability range. The polyolefin-based material may include one or more materials selected from the group consisting of polypropylene, polyethylene, and polyvinyldifluoride (PVDF). The fluorine-based material may include one or more materials selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

[0099] In one embodiment of the present invention, the gas permeability of the lead film 400 may be 20 to 60 Barrer, or 30 to 40 Barrer at 60° C. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above-mentioned range. Here, the gas permeability may satisfy the above-mentioned range at 60° C., based on the case where the thickness H of the lead film 400 is 200 μm. When the gas permeability of the lead film 400 satisfies the above-mentioned range, gas generated inside the battery cell can be more effectively discharged.

[0100] As used herein, gas permeability may be measured by ASTM F2476-20.

[0101] In an embodiment of the present invention, the moisture permeation amount of the lead film 400 may be 0.02g to 0.2g, or 0.02g to 0.04g, or 0.06g, or 0.15g, over 10 years at 25°C and 50% RH. When the moisture permeation amount of the lead film 400 satisfies the above range, the permeation of moisture entering from the lead film 400 can be more effectively prevented.

[0102] In one embodiment of the present invention, the lead film 400 may have a gas permeability of 20 to 60 Barrers at 60° C. and a moisture permeation amount of 0.02 g to 0.2 g over 10 years at 25° C. and 50% RH. When the gas permeability and moisture permeation amount of the lead film 400 satisfy the above-mentioned ranges, it is possible to more effectively prevent moisture permeation from the outside while discharging gas generated inside the battery cell 100.

[0103] The amount of moisture permeation of the lead film 400 may be measured according to ASTM F 1249. At this time, the measurement may be performed using an officially certified device from MCOON.

[0104] In one embodiment of the present invention, the lead film 400 may be made of an adhesive composition including at least one of a polyolefin-based material, an epoxy, and polyvinyl chloride (PVC). The polyolefin-based material may be polyethylene (PE), polypropylene (PP), etc. For example, the lead film 400 may include polyethylene, polypropylene, etc. that meets the above-mentioned gas permeability and / or moisture penetration values.

[0105] Furthermore, by making the lead film 400 from the above-mentioned material, the airtightness of the battery cell 100 can be maintained and leakage of the internal electrolyte can be prevented.

[0106] Hereinafter, a battery cell according to another embodiment of the present invention will be described. However, since most of the description of the battery cell 100 described above can be applied to the battery cell according to this embodiment, the gas discharge guide unit 450 will be mainly described as a difference from the battery cell 100.

[0107] FIG. 10 is a cross-sectional view taken along line AA' of FIG. 3 in a battery cell according to another embodiment of the present invention.

[0108] 4 and 10, in this embodiment, unlike FIG. 5, a gas exhaust guiding part 450' may be located on the electrode lead 300'. More specifically, a separate lead film 400' is not located between the gas exhaust guiding part 450' and the electrode lead 300'. That is, the gas exhaust guiding part 450' may be inserted into one surface of the lead film 400' adjacent to the electrode lead 300' and may be located in contact with the electrode lead 300'. In other words, in this embodiment, the gas exhaust guiding part 450' may be attached or fixed onto the electrode lead 300', and then the lead film 400' may cover the outer surface of the gas exhaust guiding part 450'.

[0109] Since the gas exhaust guide portion 450' is positioned adjacent to the electrode lead 300', the thickness of the lead film 400' covering the gas exhaust guide portion 450' is relatively reduced, which has the advantage of reducing manufacturing costs and simplifying the manufacturing process.

[0110] Also, an adhesive layer 470' may be formed between the gas exhaust guiding portion 450' and the electrode lead 300'. Here, the adhesive layer 470' may extend along the interface between the gas exhaust guiding portion 450' and the electrode lead 300'. In this case, the adhesive layer 470' may be formed on the entire or part of the interface between the gas exhaust guiding portion 450' and the electrode lead 300'.

[0111] For example, the adhesive layer 470′ may be an adhesive tape or an adhesive binder, but is not limited thereto and may be any material having adhesive properties capable of fixing the gas exhaust guide unit 450′ and the electrode lead 300′ together.

[0112] In this manner, the gas discharge guiding unit 450' is stably fixed to the electrode lead 300' by the adhesive layer 470'. That is, by forming the adhesive layer 470' having a relatively high adhesive strength between the gas discharge guiding unit 450' and the electrode lead 300', peeling due to an increase in the internal pressure of the battery cell 100 can be prevented, and the sealing strength of the battery cell 100 can be further improved.

[0113] Fig. 11 is an enlarged view of the region enclosed by the two-dot chain line in Fig. 10, and Fig. 12 is a view showing a gas exhaust path formed at the interface between the lead film and the gas exhaust guide part in Fig. 11. Fig. 13 is a view showing electrolyte leakage due to a crack that has occurred in part of the gas exhaust path in Fig. 12.

[0114] 11 to 13, in this embodiment, a gas discharge path may be formed at the interface between the gas discharge guide portion 450' and the lead film 400', similarly to Figs. 7 to 9. However, in this embodiment, unlike Figs. 7 to 9, the gas discharge guide portion 450' is located in contact with the electrode lead 300', and an adhesive layer 470' is formed between the gas discharge guide portion 450' and the electrode lead 300', so that no gas discharge path is formed at the interface between the gas discharge guide portion 450' and the electrode lead 300'. In Fig. 12, the gas movement path is indicated by a dotted arrow.

[0115] More specifically, in this embodiment, the adhesive strength between the gas discharge guide portion 450' and the lead film 400' is smaller than the adhesive strength between the adhesive layer 470' and the gas discharge guide portion 450' and / or the adhesive strength between the adhesive layer 470' and the electrode lead 300'.

[0116] More specifically, in this embodiment, when the pressure inside the battery cell 100 increases, the adhesive strength at the interface between the gas discharge guide portion 450' and the lead film 400' is relatively weaker than the adhesive strength between the lead film 400' and other components, so that at least a portion of the interface between the gas discharge guide portion 450' and the lead film 400' may be separated from each other due to the internal pressure of the battery cell 100, as shown in FIG. 12.

[0117] Furthermore, in this embodiment, the adhesive strength at the interface between the gas discharge guide portion 450' and the lead film 400' is smaller than the adhesive strength between the gas discharge guide portion 450' and the adhesive layer 470' and / or the adhesive strength between the adhesive layer 470' and the electrode lead 300', so that peeling off at the interface between the gas discharge guide portion 450' and the electrode lead 300' can be prevented when the internal pressure of the battery cell 100 increases.

[0118] That is, in this embodiment, only the interface between the gas exhaust guide 450' and the lead film 400' is peeled off to form a gas exhaust path, so that it is possible to increase the sealing strength of the battery cell 100 while maintaining the gas exhaust performance of the gas exhaust path. In addition, due to the high sealing strength, the vent pressure when gas generated within the battery cell 100 is exhausted to the outside is also increased, thereby improving safety.

[0119] Furthermore, in this embodiment, the gas exhaust path is formed only at the interface between the gas exhaust guide portion 450' and the lead film 400', and the gas exhaust path can guide the electrolyte 50 inside the battery cell 100 to be exhausted to the cover portion 270 side even if a crack occurs as shown in FIG. 13, thereby further improving insulation performance and safety.

[0120] The following description will focus on battery cells according to comparative examples of the present invention. The comparative examples will be described in comparison with the embodiments shown in Figures 3 to 9, but they can also be described in a similar manner in comparison with the embodiments shown in Figures 10 to 13.

[0121] Fig. 14 is a cross-sectional view taken along a-a' in Fig. 1 in a comparative example. Fig. 15 is an enlarged view of the region enclosed by the two-dot chain line in Fig. 14, showing leakage of the electrolyte due to a crack that has occurred in a part of the gas exhaust path in Fig. 14.

[0122] 14 and 15, the battery cell 10 according to the comparative example is the same as the battery cell 10 of FIGs. 1 and 2, except for the inclusion of a gas discharge guiding unit 45 as in the embodiment of the present invention. The following description will focus on the gas discharge guiding unit 45.

[0123] 14, in the battery cell 10 according to the comparative example, a sealing portion 25 is formed on the lead film 40 where the gas discharge guide portion 45 is located, and unlike FIGS. 3 to 9, no separate component is provided extending from an end of the sealing portion 25. That is, the end face of the sealing portion 25 is exposed to the outside, and in particular, the end face of the sealing portion 25 may be located on a gas discharge path formed by the lead film 40 and the gas discharge guide portion 45.

[0124] 15, even in the case of the battery cell 10 according to the comparative example, after a certain period of time, as shown in FIG. 9, a crack may occur in part of the lead film 40, and the electrolyte 50 inside the battery cell 10 may leak out through the crack.

[0125] However, in the case of the battery cell 10 according to the comparative example, since the end face of the sealing portion 25 is located on the gas exhaust path formed by the lead film 40 and the gas exhaust guide portion 45, the end face of the sealing portion 25 and the electrolyte leaking from outside the gas exhaust path may come into contact with each other as shown in Fig. 15. That is, the barrier metal layer exposed at the end face of the sealing portion 25 may come into contact with the electrolyte leaking from outside the gas exhaust path, and an electric circuit may be formed between the barrier metal layer and the electrolyte, which may cause a fire or otherwise significantly reduce safety.

[0126] 3 to 9, in the battery cell 100 according to the present embodiment, the cover portion 270 extends from the sealing portion 250 located on the gas discharge guide portion 450, and the end of the cover portion 270 may be located outside the end of the gas discharge path. That is, unlike the comparative example, in the present embodiment, even if a crack occurs in a part of the lead film 400, the electrolyte leaking from the crack does not come into contact with the end of the cover portion 270, so that it is possible to prevent an electric circuit from being formed between the end of the cover portion 270 and the electrolyte, and it is also possible to improve insulation performance and safety.

[0127] A battery module according to another embodiment of the present invention includes the above-mentioned battery cell. Meanwhile, one or more of the battery modules according to the present embodiment may be packaged in a pack case to form a battery pack.

[0128] The above-mentioned battery module and the battery pack including the same may be applied to various devices. Such devices may be means of transportation such as electric bicycles, electric cars, hybrid cars, etc. However, the present invention is not limited thereto, and the battery module and the battery pack including the same may be applied to various devices that can use the battery module, and these are also within the scope of the present invention.

[0129] Although a preferred embodiment of the present invention has been described in detail above, it goes without saying that 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 as claimed in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0130] 100: Battery cell 110: Electrode assembly 200: Battery case 210: Storage section 250: Sealing part 270: Cover part 300: Electrode lead 400: Lead film 450: Gas exhaust induction section

Claims

1. a battery case including a receiving portion in which the electrode assembly is mounted and a sealing portion formed by sealing an 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 part; and a lead film located at an upper portion and a lower portion of the electrode lead corresponding to the sealing portion, A gas exhaust guide portion is inserted into the lead film, the battery case includes a cover portion extending from the sealing portion, the cover portion is located on the lead film and protrudes to an outside of the battery case, a battery cell in which an end of the cover portion is positioned outside an end of the lead film with respect to a protruding direction of the electrode lead.

2. The battery cell according to claim 1 , wherein the cover portion is located on the gas discharge guide portion.

3. The battery cell according to claim 2 , wherein the gas discharge guide portion is located at a portion corresponding to a center of the cover portion.

4. The battery cell according to claim 2 , wherein a length of the cover portion is equal to or longer than a length of the gas discharge guiding portion in a direction perpendicular to a protruding direction of the electrode lead.

5. The battery cell according to claim 4 , wherein a length of the cover portion is equal to or shorter than a length of the lead film with respect to a direction perpendicular to a protruding direction of the electrode lead.

6. The battery cell according to claim 1 , wherein an end of the electrode lead is positioned outside an end of the cover portion with respect to a protruding direction of the electrode lead.

7. The battery cell according to claim 1 , wherein the cover portion is bent in a direction away from the lead film with respect to the sealing portion.

8. 2. The battery cell according to claim 1, wherein the gas discharge guide portion extends along a protruding direction of the electrode lead, and an end portion of the gas discharge guide portion adjacent to an outside of the battery case is covered and wrapped with the lead film.

9. The battery cell according to claim 8 , wherein an end of the gas discharge guide portion adjacent to an inner side of the battery case is exposed to the inside of the battery case.

10. The battery cell according to claim 1 , wherein a gas discharge path is formed at an interface between the gas discharge guide portion and the lead film.

11. The battery cell of claim 10 , wherein an adhesive force between the gas discharge guide portion and the lead film is smaller than an adhesive force between the lead film and an electrode lead or an adhesive force between the lead film and the sealing portion.

12. The battery cell according to claim 11 , wherein the gas discharge guide portion is a film layer made of at least one of polyimide and polyethylene terephthalate.

13. The battery cell according to claim 11 , wherein the gas discharge guide portion is a coating layer made of a liquid resin.

14. The gas exhaust guide portion is made of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO ２ 12. The battery cell of claim 11, further comprising a getter material comprising at least one of: barium oxide (BaO), barium (Ba), and calcium (Ca).

15. The battery cell according to claim 1 , wherein the gas discharge guide portion is located on the electrode lead, and an adhesive layer is formed between the gas discharge guide portion and the electrode lead.

16. The battery cell of claim 15 , wherein an adhesive strength between the gas discharge guide portion and the lead film is smaller than at least one of an adhesive strength between the adhesive layer and the gas discharge guide portion and an adhesive strength between the adhesive layer and the electrode lead.

17. 17. The battery cell of claim 16, wherein the adhesive layer comprises an adhesive tape or an adhesive binder.

18. 2. The battery cell according to claim 1, wherein the gas permeability of the lead film is 20 to 60 barrers at 60°C.

19. 2. The battery cell according to claim 1, wherein the amount of moisture permeation into the lead film is 0.02 g to 0.2 g at 25° C. and 50% RH for 10 years.

20. The battery cell according to claim 1 , wherein the gas discharge guide portion has a gas permeability of 40 barrer or more at 60° C.

21. A battery module comprising the battery cell according to claim 1.

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