Battery cell and battery module including the same

Abstract

A battery cell according to an embodiment of the present invention includes: a battery case in which an electrode assembly is mounted in a receiving portion, the battery case including a sealing portion having a structure for sealing the periphery by heat melting; and an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case via the sealing portion; and a lead film located above and below the electrode lead at positions corresponding to the sealing portion. The lead film has a gas discharge portion extending from the inside of the battery case to the outside of the battery case, and the gas discharge portion is open toward the inside of the battery case.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2020-0147669 filed in Korea on November 6, 2020 and Korean Patent Application No. 10-2021-0142441 filed in Korea on October 25, 2021, the disclosures of which are incorporated herein by reference.

[0002] The present disclosure relates to a battery cell and a battery module including the same, and more particularly, to a battery cell having improved external exhaust of gas generated inside the battery cell and a battery module including the same. Background Art

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

[0004] According to the shape of the battery case, these secondary batteries are divided into: cylindrical batteries and prismatic batteries, in which the battery assembly is included in a cylindrical or prismatic metal can; and pouch batteries, in which the battery assembly is included in a pouch case of an aluminum laminate. Here, the battery assembly included in the battery case is a power element that includes a positive electrode, a negative electrode, and a separator inserted between the positive electrode and the negative electrode and can be charged and discharged, and 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, and a separator is inserted therebetween; in the stacked type, a plurality of positive electrodes and negative electrodes are sequentially stacked, and a separator is inserted therebetween.

[0005] Among these secondary batteries, in particular, pouch-shaped batteries in which a stacked or stacked / folded type battery assembly is included in a pouch-shaped battery case made of an aluminum laminate sheet are increasingly used due to low manufacturing cost, small weight, and easy modification.

[0006] Figure 1 is a top view showing a conventional battery cell. Figure 2 is along Figure 1 A cross-sectional view taken along the axis a-a'. Figure 1 and Figure 2, a conventional battery cell 10 includes a battery case 20 having a receiving portion 21 in which a battery assembly 11 is mounted and a sealing portion 25 formed by sealing the periphery of the battery case 20 by thermal fusion. Here, the battery cell 10 includes an electrode lead 30 protruding out of the battery case 20 via the sealing portion 25, and a lead film 40 is located between the upper and lower portions of the electrode lead 30 and the sealing portion 25.

[0007] However, as the energy density of battery cells has increased in recent years, there is a problem that the amount of gas generated inside the battery cell has also increased. In the case of a conventional battery cell 10, a component capable of discharging the gas generated inside the battery cell is not included, so exhaust may occur in the battery cell due to gas generation. In addition, moisture may penetrate into the battery cell damaged by exhaust, which may cause side reactions, and there is a problem of battery performance degradation and generation of additional gas. Therefore, there is a growing need to develop a battery cell that improves the external discharge of the gas generated inside the battery cell. Summary of the invention

[0008] Technical issues

[0009] The present disclosure is intended to solve the problems of the related art, and thus the present disclosure is directed to a battery cell providing improved external exhaust of gas generated inside the battery cell and a battery module including the battery cell.

[0010] The objectives to be solved by the present disclosure are not limited to the above-mentioned objectives, and those skilled in the art can clearly understand objectives not mentioned here based on this specification and the accompanying drawings.

[0011] Technical Solution

[0012] In one aspect of the present disclosure, a battery cell is provided, comprising: a battery case having a receiving portion and a sealing portion, a battery assembly being mounted in the receiving portion, the sealing portion being formed by sealing the periphery of the battery case by heat melting; an electrode lead being electrically connected to an electrode tab included in the battery assembly and protruding out of the battery case via the sealing portion; and a lead film being located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film comprises a gas discharge portion, the gas discharge portion being formed to extend from the interior of the battery case to the exterior of the battery case, and the gas discharge portion being open toward the interior of the battery case.

[0013] A front surface and both side surfaces of the gas discharge portion based on a protruding direction of the electrode lead may be closed.

[0014] The battery cell may further include an inner layer configured to cover at least a portion of a surface of the gas discharge portion.

[0015] The material of the inner layer may have a higher melting point than the material of the lead film and may not react with the electrolyte.

[0016] 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.

[0017] The lead film may have a width wider than that of the electrode lead.

[0018] The lead film may have a longer length than the sealing portion and a shorter length than the electrode lead.

[0019] The gas discharge portion may have a width wider than that of the electrode lead.

[0020] The lead film may include a first lead film and a second lead film, the first lead film may be located at an upper portion of the electrode lead, and the second lead film may be located at a lower portion of the electrode lead.

[0021] The electrode lead may be located between the first lead film and the second lead film, and the first lead film and the second lead film may be connected to each other.

[0022] An end portion of the gas discharge portion formed within the lead film may be positioned further outward than an outer surface of the battery case.

[0023] An end portion of the gas discharge portion that opens toward the interior of the battery case may be positioned more inwardly than an inner surface of the battery case.

[0024] In another aspect of the present disclosure, a battery module including the above-mentioned battery cell is also provided.

[0025] Beneficial Effects

[0026] According to an embodiment, since the present disclosure provides a battery cell including an electrode lead attached with a lead film having a maximum penetration area and a battery module including the same, external discharge of gas generated inside the battery cell may be improved.

[0027] The effects of the present disclosure are not limited to the above-mentioned effects, and effects not mentioned here will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1is a top view showing a conventional battery cell.

[0029] Figure 2 is along Figure 1 A cross-sectional view taken along the axis a-a'.

[0030] Figure 3 It is a top view showing the battery cell according to the present embodiment.

[0031] Figure 4 Yes means Figure 3 A three-dimensional view of electrode leads included in a battery cell.

[0032] Figure 5 is along Figure 4 A cross-sectional view taken along the axis c-c'.

[0033] Figure 6 is along Figure 4 A cross-sectional view taken along the axis d-d'.

[0034] Figure 7 is along Figure 3 A cross-sectional view taken along the axis b-b'.

[0035] Figure 8 It is shown in Figure 7 Diagram of the flow of gases generated inside a battery cell and discharged to the outside.

[0036] Fig. 9 is a diagram showing a cross section of a battery cell according to Experimental Example 1.

[0037] Fig.10 is a graph showing the measurement results of the gas pressure in the battery cell according to Experimental Example 2.

[0038] Reference numerals

[0039] 100: Battery Cell

[0040] 110: Battery components

[0041] 200: Battery housing

[0042] 210: Accommodation

[0043] 250: Sealing part

[0044] 300: Electrode lead

[0045] 400: Lead film

[0046] 410: Inner layer

[0047] 450: Gas emission section DETAILED DESCRIPTION

[0048] Hereinafter, with reference to the accompanying drawings, various embodiments of the present disclosure will be described in detail so as to be easily implemented by those skilled in the art. The present disclosure can be implemented in various different forms and is not limited to the embodiments described herein.

[0049] In order to clearly explain the present disclosure, parts irrelevant to the description are omitted, and the same or similar components have the same reference numerals throughout the specification.

[0050] In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for the convenience of description, the present disclosure is not necessarily limited to the drawings. In order to clearly indicate the various layers and regions in the drawings, the thickness is exaggerated. Moreover, in the drawings, for the convenience of explanation, the thickness of some layers and regions is exaggerated.

[0051] In addition, throughout the specification, when a workpiece “includes” a certain component, it means that other components may also be included, rather than excluding other components, unless otherwise stated.

[0052] In addition, throughout the specification, when a “top view” is mentioned, it means observing the target workpiece from above, and when a “cross-sectional view” is mentioned, it means observing a vertically cut portion of the target workpiece from the side.

[0053] Hereinafter, the pouch-shaped battery cell 100 according to an embodiment of the present disclosure will be described. However, here, the description will be based on one of the two side surfaces of the pouch-shaped battery cell 100, but it is not necessarily limited thereto, and the same or similar content may be described with the other side surface.

[0054] Figure 3 is a plan view showing a battery cell according to this embodiment.

[0055] Reference Figure 3 , the battery cell 100 according to this embodiment includes a battery case 200 , an electrode lead 300 , and a lead film 400 .

[0056] The battery case 200 includes a receiving portion 210 and a sealing portion 250, in which the battery assembly 110 is installed, and the sealing portion 250 is formed by sealing its periphery by heat melting. The battery case 200 may be a laminate including a resin layer and a metal layer. More specifically, the battery case 200 may be made of a laminate, and may include an outer resin layer forming the outermost layer, a barrier metal layer to prevent penetration of the material, and an inner resin layer for sealing.

[0057] In addition, the battery assembly 110 may have a jelly roll type (winding type), a stacked type (laminated type), or a composite type (stacked / folded type) structure. More specifically, the battery assembly 110 may include a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0058] Hereinafter, the electrode lead 300 and the lead film 400 will be mainly described.

[0059] Figure 4 It is shown that the Figure 3 A three-dimensional view of the electrode leads in a battery cell.

[0060] Reference Figure 3 and Figure 4 , the electrode lead 300 is electrically connected to an electrode tab (not shown) included in the battery assembly 110, and protrudes out of the battery case 200 via the sealing portion 250. In addition, the lead film 400 is located at a portion corresponding to the sealing portion 250 in at least one of the upper and lower portions of the electrode lead 300. Therefore, the lead film 400 can improve the sealing performance of the sealing portion 250 and the electrode lead 300 while preventing a short circuit from occurring in the electrode lead 300 during heat fusion.

[0061] In addition, the lead film 400 may have a wider width than the electrode lead 300. The lead film may have a longer length than the sealing portion and a shorter length than the electrode lead. Therefore, the lead film 400 may prevent the side surface of the electrode lead 300 from being exposed to the outside without interfering with the electrical connection of the electrode lead 300.

[0062] In addition, the lead film 400 may include a first lead film and a second lead film, the first lead film may be located at an upper portion of the electrode lead 300, and the second lead film may be located at a lower portion of the electrode lead 300. At this time, the electrode lead 300 may be thermally melted together with the sealing portion 250 in a state of being located between the first lead film and the second lead film, so that the first lead film and the second lead film may be connected to each other.

[0063] Therefore, the lead film 400 may prevent the side surface of the electrode lead 300 from being exposed to the outside, while improving the sealing performance of the sealing portion 250 and the electrode lead 300 .

[0064] Figure 5 is along Figure 4 A cross-sectional view taken along the axis c-c'. Figure 6 is along Figure 4 A cross-sectional view taken along the axis d-d'. Figure 7 is along Figure 3 A cross-sectional view taken along the axis b-b'.

[0065] Reference Figures 5 to 7, the lead film 400 includes a gas discharge portion 450 formed to extend from the inside of the battery case 200 to the outside of the battery case 200, and the gas discharge portion 450 is open toward the inside of the battery case 200. In addition, the front surface and two side surfaces of the gas discharge portion 450 based on the protruding direction of the electrode lead 300 may be closed. Here, the gas discharge portion 450 may refer to a portion of the lead film 400 where the remaining surfaces other than the surface opening toward the inside of the battery case 200 do not adhere to each other. In addition, the gas discharge portion 450 may have a wider width than the electrode lead 300.

[0066] Therefore, the gas generated inside the battery case 200 can flow in the gas discharge portion 450 of the lead film 400. In addition, when the pressure of the lead film 400 is higher than the predetermined pressure, the gas generated inside the battery case 200 can be discharged to the outside through the gas discharge portion 450. In addition, since the gas permeation area can be maximized through the gas discharge portion 450, the lead film 400 can discharge a large amount of gas.

[0067] In addition, the lead film 400 may further include an inner layer 410 covering at least a portion of the surface of the gas discharge portion 450. More preferably, the inner layer 410 may cover the entire surface of the gas discharge portion 450. Here, the inner layer 410 may be coated on the gas discharge portion 450, or may be manufactured as a separate film and attached to the gas discharge portion 450.

[0068] Therefore, even if the lead film 400 is heat-fused together with the sealing portion 250 in a state of being located in at least one of the upper and lower portions of the electrode lead 300 , the gas discharge portion 450 may be retained without being heat-fused by the inner layer 410 .

[0069] More specifically, the inner layer 410 may be made of a material having a higher melting point than the material of the lead film 400. In addition, the inner layer 410 may be made of a material that does not react with the electrolyte contained in the battery housing 200. For example, the lead film 400 may include a polyolefin-based material, and the inner layer 410 may include at least one material of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material. In addition, the inner layer 410 may include a getter material to increase gas permeability while minimizing water permeability. As an example, the getter material may be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silicon dioxide (SiO2), etc., but is not limited thereto, and any material that reacts with water (H2O) may be used.

[0070] Therefore, since the inner layer 410 is made of the above-mentioned material, the inner layer 410 will not react with the electrolyte alone, and will not cause heat melting, thermal deformation, etc. during the high-temperature heat melting process, so that the gas discharge portion 450 can remain blank. That is, the inner surface of the gas discharge portion 450 can remain in a non-adhesive state. In addition, when the gas generated in the battery housing 200 flows into the gas discharge portion 450, the inner surfaces of the gas discharge portion 450 can be spaced apart from each other, so that the gas introduced into the gas discharge portion 450 can be easily discharged to the outside. In addition, since the lead film 400 is made of the above-mentioned material, the lead film 400 can maintain the airtightness of the battery cell 100 and can also prevent leakage of the internal electrolyte.

[0071] Reference Figure 7 , the end of the gas discharge portion 450 formed in the lead film 400 may be positioned at a position further outside than the outer surface of the battery case 200. In addition, the end of the gas discharge portion 450 opening toward the inside of the battery case 200 may be positioned at a position further inside than the inner surface of the battery case 200.

[0072] Therefore, the lead film 400 can maximize the area of ​​the gas discharge portion 450, thereby maximizing 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 can be maximized, so that a large amount of gas can be discharged.

[0073] Figure 8 It is shown in Figure 7 Diagram of the flow of gases generated inside a battery cell and discharged to the outside.

[0074] Reference Figures 5 to 8 ,exist Figure 7 The gas generated inside the battery cell 100 may flow toward the gas discharge portion 450 of the lead film 400. Figure 7 In contrast, the gas exhaust portion 450 may be expanded upward and downward by the gas inside the battery cell 100. Figure 8 As shown in A in FIG. 1 , when the gas inside the battery cell 100 exceeds a predetermined pressure, the gas inside the battery cell 100 may be discharged to the outside through the gas discharge portion 450 .

[0075] Therefore, with Figure 2 In contrast, since the gas discharge portion 450 is located on the lead film 400 , the permeation area of ​​the gas inside the battery cell 100 is also maximized, and thus the amount of gas discharged to the outside may also be maximized.

[0076] A battery module according to another embodiment of the present disclosure includes the above-mentioned battery cell. In addition, one or more battery modules according to this embodiment may be packaged in a battery pack case to form a battery pack.

[0077] The battery module and the battery pack including the battery module can be applied to various devices. These devices can be transportation tools such as electric bicycles, electric vehicles, hybrid electric vehicles, etc., but the present disclosure is not limited thereto, and the present disclosure can be applied to various devices that can use the battery module and the battery pack including the battery module, which is also within the scope of the present disclosure.

[0078] Hereinafter, the contents of the present disclosure will be described through more specific embodiments, but the following embodiments are used to illustratively describe the present disclosure, and the scope of the present disclosure is not limited thereto.

[0079] <Example>

[0080] A battery cell is manufactured as follows: the battery cell includes a battery case having a housing portion in which a battery assembly is mounted and a sealing portion formed by sealing the periphery of the battery case by heat-melting. Here, an electrode tap included in the battery assembly is electrically connected to an electrode lead, and the electrode lead protrudes out of the battery case via the sealing portion. At this time, a lead film is attached to a position corresponding to the sealing portion in the upper portion of the electrode lead, and a gas discharge portion extending from the inside of the battery case to the outside of the battery case is formed in the lead film.

[0081] <Comparison example>

[0082] A battery cell was manufactured in the same manner as in Example, except that a separate gas discharge portion was not formed in the lead film.

[0083] <Experimental Example 1-CT Scan Image>

[0084] For the battery cell of this example, CT is taken with the sealing portion where the lead film and the electrode lead are located as the center, and a CT image of the corresponding portion is obtained, such as Fig. 9 shown.

[0085] Fig. 9 is a diagram showing a cross section of a battery cell according to Experimental Example 1. In the battery cell of the example, Fig. 9 (a) is a CT image of a cross section of a lead film and an electrode lead before the internal pressure of a battery cell in the example is increased, and Fig. 9 (b) is a CT image of a cross section of the lead film and the electrode lead after the internal pressure of the battery cell in the example is increased by injecting gas into the battery cell in the example.

[0086] Reference Fig. 9(a), it can be confirmed that before the internal pressure of the battery cell in the example increases, there is no significant change centered on the gas discharge portion formed on the lead film. However, as the internal pressure of the battery cell in the example increases, it can be seen that the gas discharge portion formed in the lead film is spaced apart in the vertical direction (arrow direction), as shown in FIG. Fig. 9 as shown in (b).

[0087] Therefore, as in this example, if a gas discharge portion is formed in the lead film of the battery cell, when the internal pressure of the battery cell increases, the gas discharge portion is vertically spaced apart so that the gas inside the battery cell can be introduced into the gas discharge portion. That is, it can be seen that the gas discharge portion included in the battery cell of this example serves as a gas discharge path of the battery cell.

[0088] <Experimental Example 2-Measurement of Gas Pressure in Battery Cell>

[0089] For the batteries in the examples and comparative examples, the changes in the gas pressure inside the battery cells over time were measured. The results are shown in Fig.10 In the battery cell of this example, the initial internal pressure of the battery cell is 1 atm.

[0090] Fig.10 is a graph showing the measurement results of the gas pressure in the battery cell according to Experimental Example 2.

[0091] Reference Fig.10 , it can be confirmed that, in the battery cell according to the comparative example, in a state where the initial internal pressure is 1 atm, the internal pressure decreases relatively less with the passage of time. In contrast, in the battery cell according to this example, it can be seen that, in a state where the initial internal pressure is 1 atm, the internal pressure decreases relatively significantly with the passage of time. That is, in the battery cell according to this example, it can be confirmed that the internal gas is effectively discharged to the outside through the gas discharge portion formed in the lead film with the passage of time.

[0092] Therefore, in the battery cell according to this example, since the gas discharge portion is formed in the lead film, it can be confirmed that when the pressure inside the battery cell increases, the gas is easily discharged to the outside through the gas discharge portion.

[0093] Although the preferred embodiments of the present disclosure have been described in detail above, the scope of rights of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure defined in the appended claims also fall within the scope of rights of the present disclosure.

Claims

1. A battery cell, comprising: a battery case having a housing portion in which a battery assembly is mounted and a sealing portion formed by sealing an outer periphery of the battery case by thermal fusion; an electrode lead electrically connected to an electrode tab included in the battery assembly and protruding out of the battery case via the sealing portion; as well as a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein the lead film includes a gas discharge portion formed to extend from the inside of the battery case to the outside of the battery case, wherein a front surface and two side surfaces of the gas discharge portion based on a protruding direction of the electrode lead are closed, the gas discharge portion opens toward the interior of the battery case in a direction opposite to the protruding direction of the electrode lead, wherein, when the gas generated in the battery case flows into the gas discharge portion, the two side surfaces of the gas discharge portion are spaced apart from each other, wherein the gas generated inside the battery case flows inside the gas discharge portion, and when the pressure of the lead film is higher than a predetermined pressure, the gas generated inside the battery case passes through the gas discharge portion to be discharged to the outside through the lead film.

2. The battery cell according to claim 1, wherein: The lead film further comprises: An inner layer is configured to cover at least a portion of a surface of the gas discharge portion.

3. The battery cell according to claim 2, wherein: The inner layer covers the entire surface of the gas discharge portion.

4. The battery cell according to claim 2, in, The material of the inner layer has a higher melting point than the material of the lead film and does not react with the electrolyte.

5. The battery cell according to claim 4, in, The lead film comprises a polyolefin-based material, and The inner layer includes at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material.

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

7. The battery cell according to claim 6, in, The length of the lead film is greater than the length of the sealing portion and smaller than the length of the electrode lead.

8. The battery cell according to claim 6, in, The width of the gas discharge portion is greater than the width of the electrode lead.

9. The battery cell according to claim 1, in, The lead film includes a first lead film and a second lead film, The first lead film is located on the upper portion of the electrode lead, and The second lead film is located at the lower part of the electrode lead.

10. The battery cell according to claim 9, in, 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 10, in, The electrode lead is thermally fused together with the sealing portion while being located between the first lead film and the second lead film, so that the first lead film and the second lead film are connected to each other.

12. The battery cell according to claim 1, in, An end portion of the gas discharge portion formed within the lead film is positioned further outward than an outer surface of the battery case.

13. The battery cell according to claim 12, in, An end portion of the gas discharge portion that opens toward the interior of the battery case is positioned more inward than an inner surface of the battery case.

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

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