Battery cells and battery modules containing them

Abstract

To provide a battery cell with improved gas discharge performance, and a battery module including the same.SOLUTION: A battery cell according to one aspect of the present invention includes: a battery case including an accommodation portion in which an electrode assembly is mounted, and a sealing portion formed by sealing an outer periphery of the accommodation portion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding out of the battery case via 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. A gas discharge guiding unit is inserted in the lead film, the sealing portion includes a first sealing portion located on the gas discharge guiding unit and a second sealing portion located at both sides of the first sealing portion, and based on a protruding direction of the electrode lead, a width of the first sealing portion is smaller than a width of the second sealing portion.SELECTED DRAWING: Figure 3

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 having improved gas discharge performance and a battery module including the same. This application claims priority based on Korean Patent Application No. 10-2021-0088728 filed on July 6, 2021 and Korean Patent Application No. 10-2022-0081996 filed on July 4, 2022, and all of the contents disclosed in the specifications and drawings of the applications are incorporated herein.

Background Art

[0002] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has been rapidly increasing. In particular, secondary batteries have attracted much attention not only as an energy source for mobile devices such as mobile phones, digital cameras, notebook computers, and wearable devices but also for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0003] Such secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is housed in a cylindrical or prismatic metal can depending on the shape of the battery case, and pouch-type batteries in which an electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet. Here, the electrode assembly housed in the battery case includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is a power generation element capable of charge and discharge, and is divided into a jelly roll type in which a separator is interposed between long sheet-type positive and negative electrodes coated with an active material and wound, and a stacked type in which a plurality of positive and negative electrodes are sequentially stacked with a separator interposed therebetween.

[0004] Among them, in particular, a pouch-type battery having 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 is increasingly used because of its low manufacturing cost, light weight, and easy deformation.

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

[0006] Referring to Figures 1 and 2, a conventional battery cell 10 includes a battery case 20 in which an electrode assembly 11 is housed in a storage section 21 and a sealing section 25 with an outer periphery that is sealed. The battery cell 10 also includes electrode leads 30 that are electrically connected to electrode tabs 15 included in the electrode assembly 11 and protrude to the outside of the battery case 20 through the sealing section 25, with a lead film 40 positioned between the upper and lower parts of the electrode leads 30 and the sealing section 25.

[0007] However, in recent years, with the increase in energy density of battery cells, there has been a problem in that the amount of gas generated inside the battery cells also increases. In the case of conventional battery cells 10, there are no components that can release the gas generated inside the battery cell, and there is a risk that a venting phenomenon will occur during long-term storage, in which the battery case 20 may rupture due to gas generation. Furthermore, battery cells damaged by the venting phenomenon can allow moisture to penetrate inside, causing side reactions, which leads to a decrease in battery performance and additional gas generation. Therefore, there is a growing need to develop battery cells that have improved the ability to release gas generated inside the battery cell to the outside. [Overview of the project] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is to provide a battery cell with improved gas emission performance and a battery module including the same.

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

[0010] A battery cell according to one aspect of the present invention includes a battery case including a housing portion into which an electrode assembly is attached, and a sealing portion 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; and a lead film located at least one of the upper and lower parts of the electrode lead in a portion corresponding to the sealing portion, wherein a gas discharge guide portion is inserted into the lead film, and the sealing portion includes a first sealing portion located on the gas discharge guide portion and second sealing portions located on both sides of the first sealing portion, and the width of the first sealing portion is narrower than the width of the second sealing portion with respect to the protruding direction of the electrode lead.

[0011] With respect to the direction perpendicular to the protruding direction of the electrode lead, the length of the first sealing portion may be longer than the length of the gas discharge induction portion.

[0012] The gas discharge induction section may be located at the center of the first sealing section.

[0013] The first sealing portion may have a pattern that is recessed relative to the second sealing portion.

[0014] The first sealing portion may have a pattern that is recessed outward with respect to the inside of the sealing portion.

[0015] A storage extension may be located between the first sealing portion and the storage portion.

[0016] With respect to the outside of the battery case, the end of the storage extension may be located outside the end of the storage portion.

[0017] The gas discharge guide portion extends along the protruding direction of the electrode lead, and the end of the gas discharge guide portion adjacent to the outside of the battery case may be covered and wrapped by the lead film.

[0018] The end portion of the gas discharge guiding portion adjacent to the inside of the battery case may be exposed inside the battery case.

[0019] A gas discharge path may be formed at the interface between the gas discharge guiding portion and the lead film.

[0020] The adhesive force between the gas discharge guiding portion and the lead film may be smaller than the adhesive force between the lead film and the electrode lead or the adhesive force between the lead film and the sealing portion.

[0021] The gas discharge guiding portion may be a film layer made of at least one of polyimide and polyethylene terephthalate.

[0022] The gas discharge guiding portion may be a coating layer made of a liquid resin.

[0023] <​​​​​​​​​​​​​​​​​​​​The moisture penetration amount of the lead film can be 0.02 g to 0.2 g in 10 years at 25°C and 50% RH.

[0029] The gas permeability of the gas discharge guiding part can be 40 barrer or more at 60°C.

[0030] A battery module according to another aspect of the present invention includes the battery cell described above.

Advantages of the Invention

[0031] According to an embodiment of the present invention, by providing a battery cell in which the length of the sealing part located on the gas discharge guiding part is relatively short and a battery module including the same, the gas discharge performance can be improved.

[0032] Specifically, according to an embodiment of the present invention, a gas discharge path can be formed at the interface between the gas discharge guiding part and the lead film, which not only makes the manufacturing process relatively easy, but also can effectively discharge the gas in the battery cell to the outside.

[0033] According to another embodiment of the present invention, the sealing part includes a first sealing part and a second sealing part. By making the widths of the first sealing part and the second sealing part different, the sealing strength between the lead film and the sealing part is reduced, so that when the internal pressure rises, the lead film is easily peeled off from the gas discharge guiding part by the internal pressure, and a gas discharge path can be easily formed between the gas discharge guiding part and the lead film.

[0034] According to still another embodiment of the present invention, a portion not sealed by the first sealing part is formed on the lead film, so that the corresponding portion comes into direct contact with the internal gas when the internal pressure rises. Therefore, the lead film can be more easily peeled off from the gas discharge guiding part by the internal pressure.

[0035] According to yet another embodiment of the present invention, the gas discharge performance of the gas discharge guide section, the durability and airtightness of the lead film can be controlled by adjusting the shape of the gas discharge guide section. Furthermore, the manufacturing process can be simplified and costs reduced by changing the shape of the gas discharge guide section as needed.

[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 discharging gas generated inside the battery cell.

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

[0038] [Figure 1] This is a top view of a conventional battery cell. [Figure 2] This is a cross-sectional view along line a-a' in Figure 1. [Figure 3] This is a top view of a battery cell according to one embodiment of the present invention. [Figure 4] (a) is a magnified view of the dashed-dotted area in Figure 3, and (b) is a magnified view of the dashed-dotted area in Figure 3 according to another embodiment of the present invention. [Figure 5] This is a cross-sectional view of the battery cell in Figure 4(a) along line A-A' in Figure 3. [Figure 6] This diagram shows various shapes of gas discharge induction sections. [Figure 7] This is a magnified view of the area indicated by the dashed line in Figure 5. [Figure 8] Figure 7 shows the gas discharge path formed at the interface between the lead film and the gas discharge guide section. [Figure 9] Figure 7 shows the gas discharge path formed at the interface between the lead film and the gas discharge guide section. [Figure 10] Figure 9 is a perspective view showing the gas emission path. [Figure 11] This is a cross-sectional view of a battery cell according to another embodiment of the present invention, along line A-A' in Figure 3. [Figure 12] This figure shows an enlarged view of the area indicated by the dashed line in Figure 11. [Figure 13] Figure 12 shows the gas discharge path formed at the interface between the lead film and the gas discharge guide section. [Figure 14] Figure 12 shows the gas discharge path formed at the interface between the lead film and the gas discharge guide section. [Figure 15] In the comparative example, this figure shows an enlarged view of the area indicated by the dashed line in Figure 1. [Figure 16] In the comparative example, the cross-sectional view is along line a-a' in Figure 1. [Figure 17] This is a magnified view of the area indicated by the dashed line in Figure 16. [Modes for carrying out the invention]

[0039] Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily implement them. The present invention can be embodied in a variety of different forms and is not limited to the embodiments described below.

[0040] To clearly explain the present invention, parts unrelated to the description have been omitted, and the same or similar reference numerals have been used throughout the specification for identical or similar components.

[0041] Furthermore, the dimensions and thicknesses of each component shown in the illustrations are arbitrary for the sake of explanation, and therefore the present invention is not limited by the illustrations. In the drawings, the thicknesses are shown enlarged to clearly illustrate the various layers and regions. Also, in the drawings, the thicknesses of some layers and regions are exaggerated for the sake of explanation.

[0042] Furthermore, when a part of the specification "includes" a certain component, unless otherwise specified, this does not exclude other components, but rather means that it may include other components.

[0043] Furthermore, throughout the specification, "plan view" refers to a view of the subject area from above, and "section view" refers to a view of a cross-section of the subject area cut vertically, viewed from the side.

[0044] The following describes a battery cell according to an embodiment of the present invention. However, although the description here is based on one end of the battery cell, it is not necessarily limited to this, and the same or similar description may apply to the other end of the battery cell.

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

[0046] Referring to Figure 3, a battery cell 100 according to one embodiment of the present invention includes a battery case 200 including a housing 210 to which an electrode assembly 110 is attached, and a sealing portion 250 formed by sealing the outer periphery of the housing 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 portion 250; and a lead film 400 located on at least one of the upper and lower parts of the electrode lead 300, corresponding to the sealing portion 250. For example, the battery cell 100 may be a substantially rectangular plate-type cell having a longer side in the X-axis direction, a shorter side in the Y-axis direction, and a Z-axis direction that is shorter than the length of the X-axis or Y-axis. The electrode lead 300 may be formed on the shorter side of the battery cell 100. Such a battery cell 100 is an efficient structure for increasing energy density by accumulating in the Z-axis direction and stacking multiple battery cells 100 face to face.

[0047] The battery case 200 may consist of a laminate sheet including a resin layer and a metal layer. More specifically, the battery case 200 may consist of a laminate sheet comprising an outer resin layer forming the outermost shell, a barrier metal layer that prevents the passage of substances, and an inner resin layer for sealing.

[0048] The electrode assembly 110 may consist of a jelly roll type (winding type), a stacked type (stacked type), or a composite type (stacked / folded type). More specifically, the electrode assembly 110 may include a positive electrode, a negative electrode, and a separation membrane placed between them.

[0049] 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 portion 250. The lead film 400 is located on at least one of the upper and lower parts of the electrode lead 300, corresponding to the sealing portion 250. This prevents short circuits from occurring in the electrode lead 300 during heat fusion or press fusion together with the sealing portion 250, and improves the airtightness between the sealing portion 250 and the electrode lead 300.

[0050] Referring to Figure 3, the lead film 400 may have a wider width than the electrode lead 300. Here, the width of the lead film 400 refers to the maximum distance between one end and the other of the lead film 400 in the direction perpendicular to the protruding direction of the electrode lead 300 (X-axis direction) (Y-axis direction), and the width of the electrode lead 300 refers to the maximum distance between one end and the other of the electrode lead 300 in the direction perpendicular to the protruding direction of the electrode lead 300.

[0051] The lead film 400 may have a length that is longer than the length of the sealing portion 250 and shorter than the length of the electrode lead 300, with respect 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 the protruding direction of the electrode lead 300. The length of the sealing portion 250 means the maximum 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 distance between one end and the other end of the electrode lead 300 in the protruding direction of the electrode lead 300. As a result, the lead film 400 does not interfere with the electrical connection of the electrode lead 300 and prevents the sides of the electrode lead 300 from being exposed to the outside.

[0052] Figure 4(a) is an enlarged view of the dashed-dotted area in Figure 3, and Figure 4(b) is an enlarged view of the dashed-dotted area in Figure 3 according to another embodiment of the present invention.

[0053] Referring to Figures 3 and 4, the lead film 400 has a gas discharge guide section 450 inserted into it, and the sealing section 250 includes a first sealing section 251 located on the gas discharge guide section 450, and second sealing sections 255 located on both sides of the first sealing section 251. In other words, the second sealing sections 255 may be located in areas where the gas discharge guide section 450 is not located. More specifically, the first sealing section 251 and the second sealing sections 255 may be integrated with each other.

[0054] Referring to Figure 4, the width D1 of the first sealing portion 251 is narrower than the width D2 of the second sealing portion 255, with respect to the protruding direction of the electrode lead 300. Here, the width of the first sealing portion 251 refers to the maximum distance between one end and the other end of the first sealing portion 251 in the protruding direction of the electrode lead 300. The width of the second sealing portion 255 refers to the maximum distance between one end and the other end of the second sealing portion 255 in the protruding direction of the electrode lead 300. More specifically, the width D1 of the surface of the first sealing portion 251 that contacts the lead film 400 is narrower than the width D2 of the surface of the second sealing portion 255 that contacts the lead film 400. That is, with respect to the protruding direction of the electrode lead 300, at least a portion of the area of ​​the lead film 400 where the gas discharge guide portion 450 is located is not covered by the first sealing portion 251.

[0055] Referring to Figure 4, the length L1 of the first sealing portion 251 can be longer than the length L2 of the gas discharge guide portion 450, with respect to the direction perpendicular to the protruding direction of the electrode lead 300. Here, the length of the first sealing portion 251 refers to the maximum distance between one end and the other end of the first sealing portion 251 in a direction perpendicular to the protruding direction of the electrode lead 300. The length of the gas discharge guide portion 450 refers to the maximum distance between one end and the other end of the gas discharge guide portion 450 in a direction perpendicular to the protruding direction of the electrode lead 300. In other words, with respect to the direction perpendicular to the protruding direction of the electrode lead 300, at least a portion of the area of ​​the lead film 400 where the gas discharge guide portion 450 is located is not covered by the first sealing portion 251. More specifically, the gas discharge guide portion 450 can be located at the center of the first sealing portion 251. However, the location of the gas discharge guide section 450 is not limited to this, and any location within the first sealing section 251 is included in this embodiment.

[0056] Here, the length of the first sealing portion 251 can be adjusted by the degree of gas discharge in the gas discharge path, which will be described later, while maintaining the airtightness of the battery cell 100.

[0057] As described above, in the battery cell 100 according to this embodiment, the width D1 of the first sealing portion 251 located on the gas discharge guide portion 450 is formed to be relatively narrow with respect to the protruding direction of the electrode lead 300, so that at least a portion of the lead film 400 located on the gas discharge guide portion 450 is not sealed by the first sealing portion 251. In other words, the portion of the lead film 400 that is not sealed by the first sealing portion 251 may be exposed.

[0058] In other words, in the portion of the lead film 400 that is not sealed by the first sealing portion 251, the sealing strength of the sealing portion 250 is reduced, making it easier for the lead film 400 to peel off from the gas discharge guide portion 450 due to the internal pressure when the internal pressure rises, and a gas discharge path can be easily formed between the gas discharge guide portion 450 and the lead film 400.

[0059] Furthermore, as shown in Figure 4, the first sealing portion 251 in the sealing portion 250 may have a recessed pattern relative to the second sealing portion 255. For example, as shown in Figures 3 and 4(a), the first sealing portion 251 in the sealing portion 250 may have a recessed pattern toward the outside relative to the inside of the sealing portion 250. As another example, as shown in Figure 4(b), contrary to the first sealing portion 251 formed in Figures 3 and 4(a), the first sealing portion 251 may have a recessed pattern toward the inside relative to the outside of the sealing portion 250. In this case, the sealing portion 250 may include a recessed portion 250A in the first sealing portion 251. As another example, as shown in Figures 4(a) and 4(b), the first sealing portion of the sealing portion 250 may have both a pattern that is recessed outward with respect to the inside of the sealing portion 250 and a pattern that is recessed inward with respect to the outside of the sealing portion 250.

[0060] As described above, unlike the second sealing portion 255, the sealing portion 250 has a recessed pattern formed on the first sealing portion 251, so there are parts on the lead film 400 that are not sealed by the first sealing portion 251. In other words, the sealing strength between the lead film 400 and the sealing portion 250 is reduced, making it easier for the lead film 400 to peel off from the gas discharge guide portion 450 due to the internal pressure when the internal pressure rises, and making it easier for a gas discharge path to be formed between the gas discharge guide portion 450 and the lead film 400.

[0061] More preferably, the sealing portion 250 may have a pattern of first sealing portions 251 as shown in Figure 4(a), and the portion of the lead film 400 not sealed by the first sealing portions 251 may come into direct contact with the internal gas when the internal pressure rises. That is, the lead film 400 can be more easily peeled off from the gas discharge guide portion 450 by the internal pressure.

[0062] However, the pattern of the sealing portion 250 is not limited to this, and any pattern in which a portion of the sealing portion 250 is not sealed and a portion of the lead film 400 located on the gas discharge guide portion 450 is exposed may be included in this embodiment.

[0063] The following explanation will be based on the battery cell shown in Figure 4(a). Figure 5 is a cross-sectional view of the battery cell shown in Figure 4(a) along line A-A' in Figure 3.

[0064] Referring further to Figures 3, 4(a), and 5, the battery case 200 may further include a storage extension 210A. More specifically, in the battery case 200, the storage extension 210A may be located between the first sealing portion 251 and the storage portion 210. In other words, the storage extension 210A may be a region that extends in the direction in which the electrode lead 300 protrudes relative to the storage portion 210 and is connected to the end of the first sealing portion 251.

[0065] Furthermore, in the battery case 200, the end of the storage extension 210A may be located further out than the end of the storage section 210, with reference to the outside of the battery case 200. In other words, with reference to the inside of the battery case 200, the end of the storage section 210 is connected to the end of the second sealing section 255, and the end of the storage extension 210A is connected to the end of the first sealing section 251. In this case, with reference to the inside of the battery case 200, the end of the first sealing section 251 is located further out than the end of the second sealing section 255, which allows the end of the storage extension 210A to be located further out than the end of the storage section 210. At this time, with reference to the lead film 400, the angle at which the storage extension 210A is tilted may be smaller than the angle at which the storage section 210 is tilted.

[0066] As described above, the battery cell 100 according to this embodiment includes a storage extension 210A that is relatively longer than the length of the side surface of the storage section 210. This allows the lead film 400 to peel away from the gas discharge guide section 450 due to internal pressure in the space between the lead film 400 and the storage extension 210A, easily forming a gas discharge path between the gas discharge guide section 450 and the lead film 400.

[0067] Referring also to Figures 4 and 5, the gas discharge guide portion 450 may extend along the protruding direction of the electrode lead 300. More specifically, in the gas discharge guide portion 450, the end of the gas discharge guide portion 450 adjacent to the outside of the battery case 200 may be covered and wrapped by the lead film 400. In other words, the end of the gas discharge guide portion 450 adjacent to the outside of the battery case 200 is not exposed to the outside of the battery case 200.

[0068] Furthermore, the end of the gas discharge guide section 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 guide section 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 it may be located further inside the battery case 200 than the end of the lead film 400.

[0069] In this way, in the lead film 400, the end of the gas discharge guide portion 450 adjacent to the outside of the battery case 200 is not exposed to the outside of the battery case 200, and the sealing force of the battery case 200 by the lead film 400 and the sealing portion 250 can be improved. Furthermore, in the lead film 400, the end of the gas discharge guide portion 450 adjacent to the inside of the battery case 200 is exposed to the inside of the battery case 200, and gas generated in the battery cell 100 can easily flow into the gas discharge path formed by the gas discharge guide portion 450 and be effectively discharged to the outside.

[0070] Referring further to Figure 5, the thickness H (height in the Z-axis direction) of the lead film 400 on the upper surface of the gas discharge guide section 450 can be 100 μm to 300 μm or 100 μm to 200 μm. When the thickness H of the lead film 400 satisfies the above range, the gas inside the battery case 200 is discharged to the outside more easily.

[0071] Referring further to Figure 5, the width W of the lead film 400 covering the front surface of the gas discharge guide section 450, with respect to the protruding direction of the electrode lead 300, can be 2 mm or more, or 2 mm to 3 mm. When the width W of the lead film 400 satisfies the above range, it is possible to prevent the lead film 400 from tearing during the process in which the gas generated inside the battery case 200 is discharged to the outside.

[0072] Furthermore, the thickness D of the gas discharge guide portion 450 can be 50 μm to 150 μm. When the thickness of the gas discharge guide portion 450 satisfies the above range, gas inside the battery case 200 can be discharged to the outside more easily. Figure 6 shows various shapes of the gas discharge guide portion. The gas discharge guide portion 450 can be formed in a predetermined pattern to discharge gas inside the battery case 200.

[0073] As an example, the gas discharge guide section 450 may be rectangular in shape, extending along the protruding direction of the electrode lead 300, as shown in Figure 4. However, it is not limited to this, and the gas discharge guide section 450 may have various shapes, such as circular as in Figure 6(a), elliptical as in Figure 6(b), or linear, curved, and other shapes.

[0074] As another example, the gas discharge guide section 450 may include a first gas discharge guide section 450a extending along the protruding direction of the electrode lead 300, as shown in Figure 6(c), and a second gas discharge guide section 450b extending perpendicular to the protruding direction of the electrode lead 300. In particular, the first gas discharge guide section 450a and the second gas discharge guide section 450b may be connected to each other. Here, the second gas discharge guide section 450b may be located outside the sealing section 250 and inside the lead film 400 with respect to the sealing section 250, as shown in Figure 6(c), or inside the sealing section 250 and outside the lead film 400 with respect to the sealing section 250, as shown in Figure 6(d). Alternatively, the second gas discharge guide section 450b may be located both outside and inside the lead film 400 with respect to the sealing section 250, as shown in Figure 6(e). However, the gas discharge guide section 450 is not limited to the shape described above and can be inserted into the lead film 400 in a shape appropriate to the circumstances.

[0075] By adjusting the shape of the gas discharge guide section 450 inserted into the lead film 400 in this way, the gas discharge performance of the gas discharge guide section 450, as well as the durability and airtightness of the lead film 400, can be controlled. Furthermore, by changing the shape of the gas discharge guide section 450 as needed, the manufacturing process can be simplified and costs can be reduced.

[0076] As an example, one gas discharge guide unit 450 may be included in the lead film 400, as shown in Figure 4. As another example, multiple gas discharge guide units 450 may be inserted into the lead film 400 and positioned spaced apart from each other.

[0077] By adjusting the number of gas discharge guide sections 450 inserted into the lead film 400 in this way, the gas discharge performance of the gas discharge guide sections 450 and the durability and airtightness of the lead film 400 can be controlled. Furthermore, the number of gas discharge guide sections 450 can be minimized as needed to simplify the manufacturing process and reduce costs. Figure 7 is an enlarged view of the dashed-dotted line region in Figure 5, and Figures 8 and 9 show the gas discharge path formed at the interface between the lead film and the gas discharge guide section in Figure 7. Figure 10 is a perspective view showing the gas discharge path in Figure 9. In Figures 8 and 10, the gas movement path is indicated by a dotted arrow.

[0078] Referring to Figures 7 to 9, in this embodiment, a gas discharge path can be formed at the interface between the gas discharge guide portion 450 and the lead film 400. More specifically, as shown in Figure 7, the portion of the lead film 400 not sealed by the first sealing portion 251 can be pressurized by the internal gas when the internal pressure of the battery cell 100 increases. The portion of the lead film 400 not sealed by the first sealing portion 251 will move in the direction of the thick arrow in Figure 7, even with a small internal pressure. Subsequently, as shown in Figure 8, the interface between the lead film 400 and the gas discharge guide portion 450 will peel off, and the peeled portion 400A of the lead film 400 may be located adjacent to the storage extension portion 210A.

[0079] Subsequently, as pressure is further applied to the interface between the peeled portion 400A of the lead film 400 and the gas discharge guide portion 450, at least a portion of the interface between the lead film 400 and the gas discharge guide portion 450 separates, as shown in Figure 9. Thus, the gas discharge path may mean the space created by the gas discharge pressure generated in the battery case 200, where at least a portion of the interface between the gas discharge guide portion 450 and the lead film 400 is separated. That is, as shown in the direction of the dotted arrow in Figure 9, the gas discharge path may mean a path through which gas flows into the space created by the separation of the interface between the gas discharge guide portion 450 and the lead film 400 and is discharged to the outside.

[0080] Here, the adhesive force between the gas discharge guide section 450 and the lead film 400 may be smaller than the adhesive force between the lead film 400 and the electrode lead 300 or between the lead film 400 and the sealing section 250. More specifically, when the pressure inside the battery case 200 increases due to the gas generated in the battery cell 100, the adhesive force at the interface between the gas discharge guide section 450 and the lead film 400 is relatively smaller than the adhesive force between the lead film 400 and other components. As a result, as shown in Figures 8 and 9, at least a portion of the interface between the gas discharge guide section 450 and the lead film 400 may separate from each other due to the pressure of the gas generated in the battery cell 100.

[0081] In other words, in this embodiment, due to the relatively low adhesive force between the gas discharge guide portion 450 and the lead film 400, 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 as the two separate, and the gas moves along the gas discharge passage and is eventually 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.

[0082] Furthermore, in this embodiment, as shown in Figure 10, the lead film 400 located on the gas discharge guide section 450 includes a portion that is not sealed by the first sealing section 251. Therefore, the lead film 400 can be easily peeled off from the gas discharge guide section 450 even at relatively low internal pressure. In other words, in this embodiment, the gas discharge path is easily formed, and the gas discharge performance is further improved.

[0083] However, the gas discharge path may include not only the case where at least a portion of the interface between the upper surface of the gas discharge guide section 450 and the lead film 400 is separated, as shown in Figure 9, but also the case where at least a portion of the interface between the lower surface of the gas discharge guide section 450 and the lead film 400 is separated together. For example, the gas discharge guide section 450 may be a film layer made of at least one of polyimide (PI) and polyethylene terephthalate (PET). As another example, the gas discharge guide section 450 may be a coating layer made of liquid resin. However, the form of the gas discharge guide section 450 or the material constituting it is not limited thereto, and any form or material in which the adhesive force at the interface between the gas discharge guide section 450 and the lead film 400 is relatively lower than the adhesive force between the lead film 400 and other components may be included in this embodiment.

[0084] Thus, in this embodiment, due to the relatively low adhesive force between the gas discharge guide portion 450 and the lead film 400, a gas discharge path can be formed at the interface between the gas discharge guide portion 450 and the lead film 400. This not only simplifies the manufacturing process but also allows for effective discharge of gas from within the battery cell 100 to the outside.

[0085] Referring further to Figures 4 and 5, with reference to the protruding direction of the electrode lead 300, one end of the gas discharge guide portion 450 may be located inside the inner surface of the sealing portion 250. In this specification, the inner surface of the sealing portion 250 means the end of the sealing portion 250 adjacent to the interior of the battery case 200, and being located inside the inner surface of the sealing portion 250 means being located inside the battery case 200 beyond the inner surface of the sealing portion 250. When one end of the gas discharge guide portion 450 is located inside the inner surface of the sealing portion 250, gas flows easily into the gas discharge guide portion 450 without interference from the sealing portion 250.

[0086] Furthermore, with reference to the protruding direction of the electrode lead 300, the other end of the gas discharge guide portion 450 may be located outside the outer surface of the sealing portion 250. In this specification, the outer surface of the sealing portion 250 means the end of the sealing portion 250 adjacent to the outside of the battery case 200, and being located outside the outer surface of the sealing portion 250 means being located outside the battery case 200 beyond the outer surface of the sealing portion 250. For example, a gap P is provided between the outer surface of the sealing portion 250 and the other end of the gas discharge guide portion 450. When the other end of the gas discharge guide portion 450 is located outside the outer surface of the sealing portion 250 in this way, the gas that has flowed into the gas discharge guide portion 450 can be discharged to the outside more easily. For example, the other end of the gas discharge guide portion 450 is not interfered with by the sealing portion 250, and the gas that has flowed into the gas discharge guide portion 450 can be discharged to the outside more easily.

[0087] As a result, the gas generated inside the battery cell 100 flows towards the gas discharge guide section 450, and the gas that flows into the gas discharge guide section 450 is smoothly discharged to the outside as shown in Figure 9. In addition, the amount of gas generated inside the battery cell 100 discharged to the outside is also increased. In this way, the gas generated inside the battery case 200 flows more easily into the gas discharge guide section 450, and can be discharged even more easily to the outside of the gas discharge guide section 450.

[0088] Furthermore, as shown in Figure 9, the gas flowing into the gas discharge guide section 450 can be more easily discharged in the Z-axis direction through the lead film 400 on the gas discharge guide section 450. For example, if the other end of the gas discharge guide section 450 is located outside the outer surface of the sealing section 250, the gas flowing into the gas discharge guide section 450 can be discharged in the Z-axis direction from the portion of the lead film 400 between the other end of the gas discharge guide section 450 and the outer surface of the sealing section 250. As described above, the thickness H of the lead film 400 on the upper surface of the gas discharge guide section 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 guide section 450 can be 2 mm or more or 2 mm to 3 mm, with respect to the protruding direction of the electrode lead 300. As described above, if the other end of the gas discharge guide section 450 is located outside the outer surface of the sealing section 250, the gas will be discharged along the Z-axis direction, which is the relatively thinner portion of the lead film 400, making gas discharge easier. Furthermore, when discharging gas, if the entire gas discharge path is covered by the sealing portion 250, gas discharge will not be smooth. Therefore, as described above, providing a gap P between the outer surface of the sealing portion 250 and the other end of the gas discharge guide portion 450 has the effect of facilitating gas discharge.

[0089] Furthermore, the gas discharge induction section 450 may further include a substance having the function of absorbing or adsorbing moisture flowing in from the outside or hydrofluoric acid generated internally. More specifically, the gas discharge induction section 450 may further include a getter material. Here, a getter material can mean a material that can be exhausted using the action of gas adsorption 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 to this and may include all types of materials generally classified as getter materials.

[0090] Thus, in this embodiment, by further including a substance that can absorb or adsorb moisture or hydrofluoric acid in the gas discharge induction unit 450, the gas discharge induction unit 450 can more easily discharge gas generated inside the battery cell 100 to the outside while further minimizing the penetration of moisture or hydrofluoric acid flowing from the outside of the battery cell 100 into the inside of the battery cell 100.

[0091] In one embodiment of the present invention, the gas permeability of the gas discharge induction unit 450 may be 40 bars or more at 60°C. For example, the carbon dioxide permeability of the gas discharge induction unit 450 may satisfy the above range.

[0092] For example, the gas discharge induction section 450 may include at least one material from among polyolefin-based, fluorine-based, and porous ceramic-based materials that satisfies the above-mentioned range of gas permeability. 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.

[0093] In one embodiment of the present invention, the gas permeability of the lead film 400 may be 20 to 60 bars or 30 to 40 bars at 60°C. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above range. Also, the gas permeability may satisfy the above 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 range, gas generated inside the battery cell can be discharged more effectively.

[0094] In this specification, gas permeability can be measured using ASTM F2476-20.

[0095] In one embodiment of the present invention, the amount of moisture permeation through 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 amount of moisture permeation through the lead film 400 satisfies the above range, it is possible to more effectively prevent the penetration of moisture flowing in from the lead film 400.

[0096] In one embodiment of the present invention, the lead film 400 has a gas permeability of 20 to 60 bars at 60°C, and a moisture penetration amount of 0.02 g to 0.2 g over 10 years at 25°C and 50% RH. When the gas permeability and moisture penetration amount of the lead film 400 satisfy the above ranges, it is possible to more effectively prevent moisture penetration from the outside while discharging gas generated inside the battery cell 100.

[0097] The amount of moisture permeation in the lead film 400 can be measured using the ASTM F 1249 method. This measurement can be performed using equipment officially certified by MCOON.

[0098] In one embodiment of the present invention, the lead film 400 may consist of an adhesive composition comprising at least one of a polyolefin-based material, epoxy, and polyvinyl chloride (PVC). The polyolefin-based material may be polyethylene (PE), polypropylene (PP), etc. For example, the lead film 400 may contain polyethylene, polypropylene, etc., that satisfy the above-mentioned gas permeability and / or moisture penetration values.

[0099] Furthermore, by making the lead film 400 from the materials described above, the airtightness of the battery cell 100 can be maintained, and leakage of the internal electrolyte can also be prevented.

[0100] The following describes a battery cell according to another embodiment of the present invention. However, since the description of the battery cell 100 described above can be applied to the battery cell according to this embodiment, the gas discharge guide portion 450 inserted into the lead film 400 will be described as the main difference from the battery cell 100.

[0101] Figure 11 is a cross-sectional view of a battery cell according to another embodiment of the present invention, along line A-A' in Figure 3.

[0102] Referring to Figures 3 and 11, this embodiment differs from Figure 5 in that the gas discharge guide portion 450' may be located on the electrode lead 300'. More specifically, there is no separate lead film 400' between the gas discharge guide portion 450' and the electrode lead 300'. That is, the gas discharge guide portion 450' is 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, this embodiment may have a structure in which the lead film 400' covers the outer surface of the gas discharge guide portion 450' after it has been attached or fixed to the electrode lead 300'.

[0103] Because the gas discharge guide section 450' is positioned adjacent to the electrode lead 300', the thickness of the lead film 400' covering the gas discharge guide section 450' is also relatively reduced, which has the advantage of reducing manufacturing costs and simplifying the manufacturing process.

[0104] Furthermore, an adhesive layer 470' may be formed between the gas discharge guide portion 450' and the electrode lead 300'. Here, the adhesive layer 470' may extend along the interface between the gas discharge guide portion 450' and the electrode lead 300'. In this case, the adhesive layer 470' may be formed on the entire interface between the gas discharge guide portion 450' and the electrode lead 300' or on a part thereof.

[0105] For example, the adhesive layer 470' may consist of an adhesive tape or an adhesive binder. However, it is not limited to this, and any material having adhesive properties capable of fixing the gas exhaust guide portion 450' and the electrode lead 300' can be applied without limitation.

[0106] As a result, the gas discharge guide portion 450' is stably fixed to the electrode lead 300' by the adhesive layer 470'. In other words, by forming an adhesive layer 470' with relatively high adhesive strength between the gas discharge guide portion 450' and the electrode lead 300', delamination 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 also be further improved.

[0107] Figure 12 is an enlarged view of the dashed-dotted area in Figure 11, and Figures 13 and 14 show the gas discharge path formed at the interface between the lead film and the gas discharge guide section in Figure 12. In Figures 13 and 14, the gas movement path is indicated by a dotted arrow.

[0108] Referring to Figures 12 to 14, in this embodiment, a gas discharge path can be formed at the interface between the gas discharge guide portion 450' and the lead film 400', similar to Figures 7 to 10. However, unlike Figures 7 to 10, in this embodiment, the gas discharge guide portion 450' is positioned 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'. Therefore, no gas discharge path is formed at the interface between the gas discharge guide portion 450' and the electrode lead 300'.

[0109] More specifically, in this embodiment, the adhesive force between the gas discharge guide portion 450' and the lead film 400' is smaller than the adhesive force between the adhesive layer 470' and the gas discharge guide portion 450' and / or the adhesive force between the adhesive layer 470' and the electrode lead 300'.

[0110] More specifically, in this embodiment, when the pressure inside the battery cell 100 increases, the adhesive force at the interface between the gas discharge guide portion 450' and the lead film 400' is relatively smaller than the adhesive force between the lead film 400' and other components. As a result, the portion of the lead film 400 that is not sealed by the first sealing portion 251 moves in the direction of the thick arrow in Figure 12, even with a small internal pressure. Therefore, as shown in Figure 13, at least a portion of the interface between the gas discharge guide portion 450' and the lead film 400' can separate from each other due to the internal pressure of the battery cell 100.

[0111] Furthermore, in this embodiment, since the adhesive force at the interface between the gas discharge guide portion 450' and the lead film 400' is smaller than the adhesive force between the gas discharge guide portion 450' and the adhesive layer 470' and / or the adhesive force between the adhesive layer 470' and the electrode lead 300', it is possible to prevent the interface between the gas discharge guide portion 450' and the electrode lead 300' from peeling off when the internal pressure of the battery cell 100 increases.

[0112] In other words, in this embodiment, only the interface between the gas discharge guide section 450' and the lead film 400' peels off to form a gas discharge path, thus increasing the sealing strength of the battery cell 100 while maintaining the gas discharge performance through the gas discharge path. Furthermore, the increased sealing strength also leads to a higher vent pressure when gas generated inside the battery cell 100 is discharged to the outside, further improving safety.

[0113] Furthermore, in this embodiment, the high adhesive strength between the gas discharge guide portion 450' and the adhesive layer 470', along with the peelable portion 400A' of the lead film 400, and / or the high adhesive strength between the adhesive layer 470' and the electrode lead 300', allows for easier peeling of the interface between the lead film 400' and the gas discharge guide portion 450', even at relatively low internal pressures. In other words, this embodiment has the advantage of allowing for easier formation of the gas discharge path and improved gas discharge performance. The following description will focus on battery cells according to comparative examples of the present invention. In the case of comparative examples, the description will be made in comparison with the embodiments shown in Figures 3 to 10, but the description can also be made in comparison with the embodiments shown in Figures 11 to 14.

[0114] Figure 15 is an enlarged view of the dashed-dotted line region in Figure 1 in the comparative example. Figure 16 is a cross-sectional view of the comparative example along the line a-a' in Figure 1. Figure 17 is an enlarged view of the dashed-dotted line region in Figure 16.

[0115] Referring to Figures 15 to 17, the comparative example battery cell 10 is identical to the battery cell 10 in Figures 1 and 2, except for the configuration which includes a gas discharge induction unit 45 as in the embodiment of the present invention. The gas discharge induction unit 45 will be described in detail below.

[0116] Referring to Figures 15 and 17, in the comparative example, the battery cell 10 has a sealing portion 25 formed on the lead film 40 where the gas discharge guide portion 45 is located. Unlike Figures 3 to 10, the width of the sealing portion 25 is constant regardless of its position. As a result, the entire lead film 40 located on the gas discharge guide portion 45 is sealed by the sealing portion 25.

[0117] Referring to Figure 17, in the comparative example battery cell 10, as described above, the lead film 40 located on the gas discharge guide portion 45 is entirely sealed by the sealing portion 25. Therefore, at relatively low internal pressures, the interface between the lead film 40 and the gas discharge guide portion 45 is less likely to peel off due to the gas inside the battery cell 10. In other words, in the case of the comparative example battery cell 10, a relatively high internal pressure is required to form a gas discharge path at the interface between the lead film 40 and the gas discharge guide portion 45, which may reduce the gas discharge performance and safety of the battery cell 10.

[0118] In contrast, as shown in Figures 3 to 10, in this embodiment, the battery cell 100 has a first sealing portion 251 located on the gas discharge guide portion 450, with a width D1 narrower than the second sealing portion 255, and the lead film 400 located on the gas discharge guide portion 450 includes a portion that is not sealed by the first sealing portion 251. That is, unlike the comparative example, in this embodiment, the portion of the lead film 400 that is not sealed by the first sealing portion 251 is in direct contact with the gas inside the battery cell 100, and the lead film 400 can be easily peeled off from the gas discharge guide portion 450 even at relatively low internal pressure. In other words, this embodiment has the advantage that the gas discharge path can be formed more easily and the gas discharge performance can be further improved.

[0119] A battery module according to another embodiment of the present invention includes the battery cells described above. Alternatively, one or more battery modules according to this embodiment may be packaged in a pack case to form a battery pack.

[0120] The battery modules and battery packs containing them described above can be applied to a variety of devices. Such devices may be means of transport such as electric bicycles, electric vehicles, and hybrid vehicles, but the present invention is not limited thereto and is applicable to a variety of devices that can use battery modules and battery packs containing them, and this also falls within the scope of the present invention.

[0121] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it goes without saying that various modifications and improvements by those skilled in the art using the basic concepts of the present invention claimed in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0122] 100: Battery cell 110: Electrode assembly 200: Battery case 210: Storage compartment 250: Sealing section 300: Electrode Leads 400: Lead film 450: Gas discharge induction section

Claims

1. A battery case including a storage section into which an electrode assembly is attached, and a sealing section formed by sealing the outer periphery of the storage section, An electrode lead is electrically connected to an electrode tab included in the electrode assembly and protrudes to the outside of the battery case through the sealing portion, The electrode lead includes, at least one of the upper and lower parts, a lead film located in the portion corresponding to the sealing portion, A gas discharge guide section is inserted into the lead film. The sealing portion includes a first sealing portion located on the gas discharge guide portion and second sealing portions located on both sides of the first sealing portion. With respect to the protruding direction of the electrode lead, the width of the first sealing portion is narrower than the width of the second sealing portion. The gas discharge guide portion extends along the protruding direction of the electrode lead, the end of the gas discharge guide portion adjacent to the outside of the battery case is covered and encased in the lead film, and the end of the gas discharge guide portion adjacent to the inside of the battery case is exposed inside the battery case. A battery cell in which the gas inside the battery case is discharged to the outside of the battery case by passing through the lead film.

2. The battery cell according to claim 1, wherein the length of the first sealing portion is longer than the length of the gas discharge induction portion, with reference to the direction perpendicular to the protruding direction of the electrode lead.

3. The battery cell according to claim 1, wherein the first sealing portion is recessed with respect to the second sealing portion and has a pattern that is recessed outward with respect to the inside of the sealing portion.

4. The battery cell according to claim 1, wherein a storage extension is located between the first sealing portion and the storage portion.

5. The battery cell according to claim 4, wherein, with reference to the outside of the battery case, the end of the storage extension is located outside the end of the storage portion.

6. The battery cell according to claim 4, wherein the lead film peels off from the gas discharge guide portion in the space between the lead film and the storage extension portion due to the pressure of the gas inside the battery case.

7. The battery cell according to claim 4, wherein a portion of the lead film that is not sealed by the first sealing portion is exposed, and the portion of the lead film that is not sealed by the first sealing portion is pressurized by the gas pressure inside the battery case, causing the interface between the lead film and the gas discharge guide portion to peel off, and the peeled portion of the lead film is located adjacent to the storage extension portion.

8. The battery cell according to claim 1, wherein the other end of the gas discharge guide portion is located outside the outer surface of the sealing portion, and the gas that has flowed into the gas discharge guide portion is discharged in the lead film portion between the other end of the gas discharge guide portion and the outer surface of the sealing portion, along a direction perpendicular to the protruding direction of the electrode lead.

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

10. The battery cell according to claim 9, wherein the adhesive force between the gas discharge induction portion and the lead film is less than the adhesive force between the lead film and the electrode lead or the adhesive force between the lead film and the sealing portion.

11. The battery cell according to claim 9, wherein the gas discharge path is a space in which at least a portion of the interface between the gas discharge guide portion and the lead film is separated from each other by the pressure of the gas inside the battery case.

12. The battery cell according to claim 9, wherein the gas discharge induction section is a coating layer made of liquid resin.

13. The battery cell according to claim 9, wherein the gas discharge induction section further comprises a getter material comprising at least one of calcium oxide (CaO), lithium chloride (LiCl), silica (SiO2), barium oxide (BaO), barium (Ba), and calcium (Ca).

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

15. The battery cell according to claim 14, wherein the adhesive force between the gas discharge induction portion and the lead film is less than at least one of the adhesive force between the adhesive layer and the gas discharge induction portion and the adhesive force between the adhesive layer and the electrode lead.

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

17. The battery cell according to claim 1, wherein the amount of moisture penetrated by the lead film is 0.02 g to 0.2 g over 10 years at 25°C and 50% RH.

18. The battery cell according to claim 1, wherein the gas permeability of the gas discharge induction section is 40 bars or more at 60°C.

19. A battery module comprising the battery cell described in claim 1.

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