Battery cell and battery module including the same

Abstract

A battery cell according to one embodiment of the present invention includes: a battery case in which an electrode assembly is mounted in a receiving portion and which includes a sealing portion whose outer periphery is sealed by heat sealing; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case through the sealing portion; and a lead film located at a portion of at least one of the upper and lower parts of the electrode lead that corresponds to the sealing portion; the lead film has a gas exhaust portion formed therein that extends from the interior of the battery case toward the exterior of the battery case, and the gas exhaust portion is open toward the interior of the battery case.

Description

[Technical Field]

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0147669, filed November 6, 2020, and Korean Patent Application No. 10-2021-0142441, filed October 25, 2021, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a battery cell and a battery module including the same, and more particularly to a battery cell and a battery module including the same in which gas generated inside the battery cell is discharged to the outside with improved efficiency. [Background technology]

[0003] As technological development and demand for mobile devices increase, 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, laptop computers, and wearable devices, as well as for power devices such as electric bicycles, electric vehicles, and hybrid electric vehicles.

[0004] These secondary batteries are classified into cylindrical batteries and prismatic batteries, in which an electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which an electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, depending on the shape of the battery case. The electrode assembly housed in the battery case is a power generating element that can be charged and discharged and includes a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. The electrode assembly is classified into a jelly roll type, in which a long sheet-type positive electrode and a negative electrode coated with an active material are wound with a separator interposed between them, and a stack type, in which multiple positive electrodes and negative electrodes are stacked in sequence with a separator interposed between them.

[0005] Among these, pouch-type batteries, which have a structure in which a stack-type or stack / folding-type 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, small weight, and easy modification.

[0006] Figure 1 is a top view of a conventional battery cell. Figure 2 is a cross-sectional view taken along the a-a' axis in Figure 1. Referring to Figures 1 and 2, an electrode assembly 11 of a conventional battery cell 10 is mounted in a receiving portion 21, and includes a battery case 20 including a sealing portion 25 whose outer periphery is sealed by heat fusion. Electrode leads 30 protrude outward from the battery case 20 via the sealing portion 25, and lead films 40 are positioned between the upper and lower portions of the electrode leads 30 and the sealing portion 25.

[0007] However, as the energy density of battery cells has increased recently, there has been a problem of an increase in the amount of gas generated inside the battery cell. In the case of conventional battery cells 10, there is no component that can release gas generated inside the battery cell, and the battery cell may experience venting due to gas generation. Similarly, battery cells damaged by venting may allow moisture to penetrate the inside, causing side reactions, resulting in reduced battery performance and additional gas generation. As a result, there is an increasing need to develop battery cells that can improve the ability to release 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 and a battery module including the same, in which gas generated inside the battery cell is discharged to the outside with improved efficiency.

[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 this specification and the accompanying drawings. [Means for solving the problem]

[0010] A battery cell according to one embodiment of the present invention includes: a battery case in which an electrode assembly is mounted in a receiving portion and the battery case includes a sealing portion whose outer periphery is sealed by heat sealing; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case through the sealing portion; and a lead film located at a portion of at least one of an upper portion and a lower portion of the electrode lead corresponding to the sealing portion; wherein the lead film has a gas exhaust portion formed therein that extends outward from the interior of the battery case, and the gas exhaust portion is open toward the interior of the battery case.

[0011] The front and both side surfaces of the gas exhaust portion are closed based on the protruding direction of the electrode lead.

[0012] The gas discharge portion may further include an inner layer covering at least a portion of a surface of the gas discharge portion.

[0013] The material forming the inner layer has a higher melting point than the material forming the lead film, and does not react with the electrolyte.

[0014] The lead film may include a polyolefin-based material, and the inner layer may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material.

[0015] The lead film may have a width greater than that of the electrode lead.

[0016] The lead film may have a length greater than the length of the sealing portion and less than the length of the electrode lead.

[0017] The gas exhaust portion may have a width greater than that of the electrode lead.

[0018] The lead film may include a first lead film and a second lead film, the first lead film being positioned above the electrode lead, and the second lead film being positioned below the electrode lead.

[0019] The electrode lead is located between the first lead film and the second lead film, and the first lead film and the second lead film are connected to each other.

[0020] An end of the gas exhaust portion formed in the lead film may be located outside the outer surface of the battery case.

[0021] An end of the gas discharge portion that is open toward the inside of the battery case may be located inside the inner surface of the battery case.

[0022] A battery module according to another embodiment of the present invention may include the above-described battery cells. [Effects of the Invention]

[0023] According to an embodiment, the present invention provides a battery cell including an electrode lead to which a lead film with a maximized permeability area is attached, and a battery module including the same, thereby improving the discharge of gas generated inside the battery cell to the outside.

[0024] The effects of the present invention are not limited to those described above, and effects not mentioned will be clearly understood by those skilled in the art from this specification and the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a top view of a conventional battery cell. [Figure 2] FIG. 2 is a cross-sectional view taken along the a-a' axis in FIG. [Figure 3] FIG. 2 is a top view of the battery cell according to the present embodiment. [Figure 4] FIG. 4 is a perspective view of an electrode lead included in the battery cell of FIG. 3. [Figure 5] FIG. 5 is a cross-sectional view taken along the cc' axis in FIG. [Figure 6] FIG. 5 is a cross-sectional view taken along the dd' axis in FIG. [Figure 7] FIG. 4 is a cross-sectional view taken along the bb' axis in FIG. [Figure 8] 8 is a diagram showing the flow of gas generated inside the battery cell in FIG. 7 being discharged to the outside. [Figure 9] 1 is a cross-sectional view of a battery cell according to Experimental Example 1. [Figure 10] 10 is a graph showing the results of measuring the gas pressure inside a battery cell according to Experimental Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE INVENTION The present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0027] 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.

[0028] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, thicknesses are exaggerated to clearly show various layers and regions. In the drawings, the thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0029] Furthermore, throughout the specification, when a part "includes" a certain component, this does not mean that it excludes other components, but that it may further include other components, unless otherwise specified to the contrary.

[0030] Also, throughout the specification, when we say "on a plane," this means a top view of the target part, and when we say "on a cross section," this means a side view of a cross section cut vertically through the target part.

[0031] Hereinafter, a pouch battery cell 100 according to an embodiment of the present invention will be described. However, the description will be based on one side of the pouch battery cell 100, but the description is not limited to this, and the same or similar content will be used for the other side.

[0032] FIG. 3 is a top view of the battery cell according to this embodiment.

[0033] Referring to FIG. 3, the battery cell 100 according to this embodiment includes a battery case 200, an electrode lead 300, and a lead film 400.

[0034] The battery case 200 includes a sealing portion 250 in which the electrode assembly 110 is mounted in the receiving portion 210 and the outer periphery is sealed by heat sealing. The battery case 200 is a laminate sheet including a resin layer and a metal layer. More specifically, the battery case 200 is made of a laminate sheet and may be composed of an outer resin layer forming the outermost shell, a metal layer with barrier properties that prevents penetration of materials, and an inner resin layer for sealing.

[0035] The electrode assembly 110 may have a jelly roll type (wound type), stack type (layered type), or composite type (stack / folded type) structure. More specifically, the electrode assembly 110 may include a positive electrode, a negative electrode, and a separator disposed therebetween.

[0036] The following description will focus on the electrode lead 300 and the lead film 400.

[0037] FIG. 4 is a perspective view of an electrode lead included in the battery cell of FIG.

[0038] 3 and 4, the electrode lead 300 is electrically connected to an electrode tab (not shown) included in the electrode assembly 110 and protrudes outward from the battery case 200 via the sealing portion 250. In addition, the lead film 400 is located on at least one of the upper and lower portions of the electrode lead 300, in a portion corresponding to the sealing portion 250. As a result, the lead film 400 can improve the sealing between the sealing portion 250 and the electrode lead 300 while preventing short circuits from occurring in the electrode lead 300 during heat sealing.

[0039] Furthermore, the lead film 400 may have a width wider than that of the electrode lead 300. The lead film may have a length greater than that of the sealing portion and less than that of the electrode lead 300. Thus, the lead film 400 can prevent the side surfaces of the electrode lead 300 from being exposed to the outside without interfering with the electrical connection of the electrode lead 300.

[0040] The lead film 400 may include a first lead film and a second lead film, and the first lead film may be located on the upper side of the electrode lead 300, and the second lead film may be located on the lower side of the electrode lead 300. In this case, the electrode lead 300 is heat-sealed with the sealing part 250 while being located between the first lead film and the second lead film, and the first lead film and the second lead film are connected to each other.

[0041] Therefore, the lead film 400 can improve the sealing performance between the sealing part 250 and the electrode lead 300 while preventing the side surface of the electrode lead 300 from being exposed to the outside.

[0042] Fig. 5 is a cross-sectional view taken along the c-c' axis in Fig. 4. Fig. 6 is a cross-sectional view taken along the d-d' axis in Fig. 4. Fig. 7 is a cross-sectional view taken along the bb' axis in Fig. 3.

[0043] 5 to 7, the lead film 400 has a gas exhaust portion 450 formed therein that extends from the inside of the battery case 200 toward the outside of the battery case 200, and the gas exhaust portion 450 is open toward the inside of the battery case 200. The front and both side surfaces of the gas exhaust portion 450 are closed based on the protruding direction of the electrode lead 300. Here, the gas exhaust portion 450 refers to a portion of the lead film 400 where the remaining surfaces, excluding the surface that is open toward the inside of the battery case 200, are not bonded to each other. The gas exhaust portion 450 may have a width wider than that of the electrode lead 300.

[0044] As a result, the lead film 400 allows gas generated from inside the battery case 200 to flow within the gas exhaust portion 450. Furthermore, when the pressure in the lead film 400 reaches a predetermined level, the gas generated from inside the battery case 200 passes through the gas exhaust portion 450 and is exhausted to the outside. Furthermore, the gas permeation area of ​​the lead film 400 is maximized by the gas exhaust portion 450, allowing the lead film 400 to exhaust a large amount of gas.

[0045] The lead film 400 may further include an internal layer 410 that covers at least a portion of the surface of the gas exhaust portion 450. More preferably, the internal layer 410 covers the entire surface of the gas exhaust portion 450. Here, the internal layer 410 may be coated on the gas exhaust portion 450 or may be manufactured as a separate film and attached to the gas exhaust portion 450.

[0046] As a result, even if the lead film 400 is heat-sealed together with the sealing portion 250 while being positioned at least at one of the upper and lower portions of the electrode lead 300, the gas exhaust portion 450 is kept in a non-heat-sealed state by the inner layer 410.

[0047] More specifically, the internal layer 410 may be made of a material having a higher melting point than the material of the lead film 400. The internal layer 410 may also be made of a material that does not react with the electrolyte contained in the battery case 200. For example, the lead film 400 may include a polyolefin-based material, and the internal layer 410 may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material. The internal layer 410 may also include a getter material to increase gas permeability while minimizing water penetration. For example, the getter material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silica (SiO2), etc., but is not limited thereto, and any material that reacts with water (H2O) may be used.

[0048] As a result, the inner layer 410, being made of the aforementioned material, does not react with the electrolyte separately, and does not undergo heat fusion or thermal deformation during the high-temperature heat fusion process, thereby maintaining the space of the gas exhaust portion 450. That is, the inner surface of the gas exhaust portion 450 remains non-adhesive. Furthermore, when gas generated within the battery case 200 flows into the gas exhaust portion 450, the inner surfaces of the gas exhaust portion 450 are spaced apart from each other, allowing the gas that has flowed into the gas exhaust portion 450 to be easily discharged to the outside. Furthermore, as the lead film 400 is made of the aforementioned material, it can maintain the airtightness of the battery cell 100 and prevent leakage of the internal electrolyte.

[0049] 7, an end of the gas exhaust portion 450 formed in the lead film 400 may be located outside the outer surface of the battery case 200. In addition, an end of the gas exhaust portion 450 that is open toward the inside of the battery case 200 may be located inside the inner surface of the battery case 200.

[0050] As a result, the lead film 400 can maximize the area of ​​the gas exhaust portion 450 and the area of ​​the inner layer 410 to which the gas generated inside the battery case 200 is exposed. In addition, the permeation area of ​​the gas generated inside the battery case 200 is maximized, allowing a large amount of gas to be exhausted.

[0051] FIG. 8 is a diagram showing the flow of gas generated inside the battery cell in FIG. 7 being discharged to the outside.

[0052] 5 to 8, gas generated from inside the battery cell 100 of Fig. 7 flows toward the gas exhaust portion 450 of the lead film 400. At this time, the gas exhaust portion 450 expands toward the top and bottom compared to Fig. 7 due to the gas inside the battery cell 100. Also, as shown in A of Fig. 8, when the gas inside the battery cell 100 reaches a predetermined pressure or higher, the gas inside the battery cell 100 is exhausted to the outside through the gas exhaust portion 450.

[0053] As a result, compared to FIG. 2, the gas exhaust portion 450 is located in the lead film 400, which maximizes the area through which gas can pass through the interior of the battery cell 100, thereby maximizing the amount of gas generated inside the battery cell 100 that can be exhausted to the outside.

[0054] A battery module according to another embodiment of the present invention includes the above-described battery cell. Meanwhile, one or more battery modules according to this embodiment may be packaged in a pack case to form a battery pack.

[0055] The battery module and the battery pack including the same can be applied to various devices, including transportation means such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and can be applied to various devices that can use the battery module and the battery pack including the same, which also fall within the scope of the present invention.

[0056] The present invention will be described below with more specific examples. However, the following examples are provided for illustrative purposes only and the scope of the present invention is not limited thereto.

[0057] <Example> A battery cell was manufactured in which an electrode assembly was mounted in a receiving portion within a battery case, and the outer periphery of the battery case was sealed by heat sealing. Here, electrode tabs included in the electrode assembly were electrically connected to electrode leads, and the electrode leads protruded outward from the battery case through the sealing portion. A lead film was attached to the upper part of the electrode lead at a position corresponding to the sealing portion, and a gas exhaust portion extending from the inside of the battery case to the outside of the battery case was formed within the lead film.

[0058] <Comparative Example> A battery cell was manufactured in the same manner as in the example, except that no separate gas exhaust portion was formed in the lead film.

[0059] <Experimental Example 1 - CT image> For the battery cell of the example, a CT scan was performed focusing on the sealing portion where the lead film and electrode lead were located, and a CT image of the corresponding portion was obtained as shown in FIG.

[0060] Figure 9 is a drawing showing a cross section of a battery cell according to Experimental Example 1. In the example battery cell, (a) of Figure 9 is a CT image of the cross section of the lead film and electrode lead before the internal pressure of the example battery cell increases, and (b) of Figure 9 is a CT image of the cross section of the lead film and electrode lead after gas is injected into the example battery cell and the internal pressure of the example battery cell increases.

[0061] 9(a), it can be seen that before the internal pressure of the battery cell of the example increases, no change is observed around the gas exhaust portion formed in the lead film. However, as the internal pressure of the battery cell of the example increases, it can be seen that the gas exhaust portion formed in the lead film moves apart in the vertical direction (in the direction of the arrows) as shown in FIG. 9(b).

[0062] Therefore, when a gas exhaust portion is formed in the lead film of a battery cell as in this embodiment, when the internal pressure of the battery cell increases, the gas exhaust portion moves apart in the vertical direction, causing gas inside the battery cell to flow into the gas exhaust portion. In other words, it can be confirmed that the gas exhaust portion included in the battery cell of this embodiment serves as a gas exhaust path for the battery cell.

[0063] <Experimental Example 2 - Gas pressure measurement inside a battery cell> The gas pressure inside the battery cells of the example and comparative example was measured over time, and the results are shown in Figure 10. In the example battery cell, the initial internal pressure of the battery cell was 1 atmosphere.

[0064] FIG. 10 is a graph showing the results of measuring the gas pressure inside the battery cell according to Experimental Example 2.

[0065] 10, it can be seen that the battery cell according to the comparative example has an initial internal pressure of 1 atmosphere and the internal pressure decreases relatively little over time. In contrast, it can be seen that the battery cell according to the present embodiment has an initial internal pressure of 1 atmosphere and the internal pressure decreases relatively much over time. In other words, it can be seen that the battery cell according to the present embodiment effectively releases internal gas to the outside through the gas exhaust part formed in the lead film over time.

[0066] As described above, the battery cell according to this embodiment has a gas exhaust portion formed in the lead film, and it can be confirmed that when the pressure inside the battery cell increases, gas can be easily exhausted to the outside through the gas exhaust portion.

[0067] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0068] 100: Battery cell 110: Electrode assembly 200: Battery case 210: Storage area 250: Sealing part 300: Electrode lead 400: Lead film 410:Inner layer 450: Gas exhaust section

Claims

1. a battery case including a sealing part in which the electrode assembly is mounted in a housing part and whose outer periphery is sealed by heat fusion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding toward an outside of the battery case through the sealing portion; a lead film located at a portion corresponding to the sealing portion on at least one of an upper portion and a lower portion of the electrode lead, the lead film has a gas exhaust portion formed therein that extends from the inside of the battery case toward the outside of the battery case, the gas exhaust port is open toward the inside of the battery case, When gas generated in the battery case flows into the gas exhaust portion, inner surfaces of the gas exhaust portion are spaced apart from each other in the vertical direction, The gas exhaust unit exhausts the gas to the outside through the lead film when the gas inside the battery cell reaches a predetermined pressure or higher.

2. The battery cell according to claim 1 , wherein a front surface and both side surfaces of the gas exhaust portion are closed relative to a protruding direction of the electrode lead.

3. The battery cell according to claim 1 , further comprising an inner layer covering at least a portion of the surface of the gas discharge portion.

4. 4. The battery cell according to claim 3, wherein the material forming the inner layer has a higher melting point than the material forming the lead film and is insensitive to the electrolyte.

5. the lead film includes a polyolefin-based material, The battery cell according to claim 3 or 4, wherein the inner layer includes at least one material selected from the group consisting of polyolefin-based, fluorine-based, and porous ceramic-based materials.

6. The battery cell according to claim 1 , wherein the lead film has a width greater than that of the electrode lead.

7. The battery cell according to claim 1 , wherein the lead film has a length greater than a length of the sealing portion and less than a length of the electrode lead.

8. The battery cell according to claim 6 , wherein the gas discharge portion has a width greater than that of the electrode lead.

9. the lead film includes a first lead film and a second lead film; the first lead film is located on top of the electrode lead, The battery cell according to claim 1 , wherein the second lead film is located below the electrode lead.

10. The battery cell according to claim 9 , wherein the electrode lead is located between the first lead film and the second lead film, and the first lead film and the second lead film are connected to each other.

11. The battery cell according to claim 1 , wherein an end of the gas discharge portion formed in the lead film is positioned outside an outer surface of the battery case.

12. The battery cell according to claim 1 , wherein an end of the gas discharge portion that is open toward the inside of the battery case is located inside an inner surface of the battery case.

13. A battery module comprising the battery cell according to any one of claims 1 to 12.

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