Battery cell and battery module including the same

Abstract

To provide: a battery cell with improved external emission of gas generated inside the battery cell; and a battery module including the same.SOLUTION: A battery cell includes: a battery case which has an accommodation portion receiving a battery assembly and includes a sealing portion structured with an outer periphery sealed by heat fusion; an electrode lead electrically connected to an electrode tab included in the battery assembly, the electrode lead protruding toward outside the battery case through the sealing portion; and a lead film positioned at a portion corresponding to the sealing portion on at least one of upper and lower sides of the electrode lead. The lead film includes a gas discharge portion formed to extend from inside the battery case toward outside the battery case, and the gas discharge portion is opened toward inside the battery case.SELECTED DRAWING: Figure 3

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 improved in terms of its ability to be discharged to the outside. [Background technology]

[0003] As technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting much attention not only for mobile devices such as mobile phones, digital cameras, laptop computers, and wearable devices, but also as an energy source for power devices such as electric bicycles, electric cars, and hybrid electric cars.

[0004] Such secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, according to the shape of the battery case. Here, the electrode assembly housed in the battery case is a power generating element capable of charging and discharging, which is composed of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode, 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 with a separator interposed therebetween, and a stack type in which a number of positive electrodes and negative electrodes are stacked in sequence with a separator interposed therebetween.

[0005] Among these, the use of pouch-type batteries, which have a structure in which a stack-type or stack / folding-type electrode assembly is built into a pouch-type battery case made of an aluminum laminate sheet, is gradually increasing due to their low manufacturing cost, small weight, easy modification, etc.

[0006] Fig. 1 is a top view of a conventional battery cell. Fig. 2 is a cross-sectional view taken along the a-a' axis in Fig. 1. Referring to Figs. 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 having an outer periphery sealed by heat fusion. Here, the battery case 20 includes electrode leads 30 protruding outward from 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 leads 30 and the sealing portion 25.

[0007] However, as the energy density of battery cells increases, there is a problem that the amount of gas generated inside the battery cell also increases. In the case of a conventional battery cell 10, since no components are included for discharging gas generated inside the battery cell, the battery cell may experience a venting phenomenon due to gas generation. Similarly, a battery cell damaged by the venting phenomenon may have problems such as moisture penetrating into the battery cell, causing side reactions, resulting in a decrease in battery performance and additional gas generation. As a result, there is an increasing need to develop a battery cell that has an improved ability to discharge gas generated inside the battery cell to the outside. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a battery cell 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 outer periphery is sealed by heat fusion; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding toward the outside of the battery case through the sealing portion; and a lead film located in 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 extending from the inside of the battery case toward the outside of the battery case, and the gas exhaust portion is open toward the inside 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 outlet may further include an inner layer covering at least a portion of a surface of the gas outlet.

[0013] The material constituting the inner layer has a higher melting point than the material constituting 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 a length of the sealing portion and less than a 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 on an upper portion of the electrode lead, and the second lead film being positioned on a lower portion of 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 an outer surface of the battery case.

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

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

[0023] According to an embodiment, the present invention provides a battery cell including an electrode lead having a lead film with a maximized transmission area attached thereto, 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 the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from this specification and the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a top view of a conventional battery cell. [Diagram 2] 2 is a cross-sectional view taken along the a-a' axis in FIG. [Diagram 3] FIG. 2 is a top view of a 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. [Diagram 5] 5 is a cross-sectional view taken along the cc' axis in FIG. 4. FIG. [Figure 6] 5 is a cross-sectional view taken along the dd' axis in FIG. 4. FIG. [Figure 7] 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] 13 is a graph showing the results of measuring the gas pressure inside a battery cell according to Experimental Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be embodied in various different forms and should not be construed as limited to the embodiments set forth herein, but rather may be practiced in a variety of ways, all without departing from the spirit or scope of the present invention.

[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 convenience of explanation, and the present invention is not necessarily limited to those shown. In the drawings, thicknesses are enlarged to clearly show various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0029] Furthermore, throughout the specification, when a part "includes" a certain component, this does not mean to exclude other components, but means that it may further include other components, unless specifically stated 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 across 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 given based on one side of the pouch battery cell 100, but the description is not limited thereto, and the same or similar content will be given in the case of 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 part 250 in which the electrode assembly 110 is mounted in the receiving part 210 and the outer periphery is sealed by heat fusion. 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 barrier metal layer preventing penetration of materials, and an inner resin layer for sealing.

[0035] In addition, the electrode assembly 110 may have a jelly roll type (wound type), stack type (lamination type), or composite type (stack / folding 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 part 250. In addition, the lead film 400 is located in a portion corresponding to the sealing part 250 in at least one of the upper and lower parts of the electrode lead 300. Thus, the lead film 400 can improve the sealing property between the sealing part 250 and the electrode lead 300 while preventing the occurrence of a short circuit in the electrode lead 300 during heat fusion.

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

[0040] Also, 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 together 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] Accordingly, the lead film 400 can improve the sealing performance between the sealing portion 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 extending 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. In addition, 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 except for the surface that is open toward the inside of the battery case 200 are not bonded to each other. In addition, the gas exhaust portion 450 may have a width wider than that of the electrode lead 300.

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

[0045] Also, the lead film 400 may further include an internal layer 410 covering 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 with the sealing portion 250 while being positioned at least on either the upper or lower portion of the electrode lead 300, the gas exhaust portion 450 is preserved in a state where it is not heat-sealed due to 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 constituting the lead film 400. Also, the internal layer 410 may 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. Also, the internal layer 410 may include a getter material to increase gas permeability while minimizing moisture infiltration. 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, since the inner layer 410 is made of the above-mentioned material, it does not react with the electrolyte, and heat fusion or thermal deformation does not occur during the high-temperature heat fusion process, and the gas exhaust part 450 maintains a space. That is, the inner surface of the gas exhaust part 450 is maintained in a non-adhesive state. Also, when gas generated in the battery case 200 flows into the gas exhaust part 450, the inner surfaces of the gas exhaust part 450 are separated from each other, so that the gas that has flowed into the gas exhaust part 450 can be easily discharged to the outside. Also, since the lead film 400 is made of the above-mentioned material, it is possible to 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 maximize 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 in 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, since the gas exhaust portion 450 is located in the lead film 400, the permeation area of ​​the gas inside the battery cell 100 is maximized, thereby maximizing the exhaust of gas generated from inside the battery cell 100 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 of the 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 battery module may be applied to various devices, such as vehicles including electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and may be applied to various devices that can use the battery module and the battery pack including the battery module, which are also within the scope of the present invention.

[0056] The present invention will be described below with reference to 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, an electrode tab included in the electrode assembly was electrically connected to an electrode lead, and the electrode lead protruded toward the outside of the battery case via the sealing portion. In this case, a lead film was attached to an upper portion 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 toward 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 a separate gas exhaust portion was not formed in the lead film.

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

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

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

[0062] As a result, in the case where a gas exhaust portion is formed in the lead film of the battery cell as in this embodiment, when the internal pressure of the battery cell increases, the gas exhaust portion is separated in the vertical direction, so that the gas inside the battery cell flows 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 internal gas pressure of the battery cells of the example and comparative example was measured over time, and the results are shown in Figure 10. In the battery cell of the example, 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. As shown in FIG.

[0065] 10, it can be seen that the battery cell according to the comparative example has an internal pressure that decreases relatively little over time when the initial internal pressure is 1 atmosphere. In contrast, it can be seen that the battery cell according to the present embodiment has an internal pressure that decreases relatively much over time when the initial internal pressure is 1 atmosphere. In other words, it can be seen that the battery cell according to the present embodiment effectively discharges internal gas to the outside through the gas discharge 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 a preferred embodiment of the present invention has 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 section 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 storage part and the 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 part; 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, the lead film is formed with a gas exhaust portion extending from the inside of the battery case toward the outside of the battery case, The gas exhaust portion is formed from the lead film.

2. The battery cell according to claim 1 , wherein the gas exhaust portion is open toward the inside of the battery case, and a front surface and both side surfaces of the gas exhaust portion are closed based on 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 a surface of the gas exhaust portion.

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

5. The battery cell according to claim 3 or 4, wherein the internal layer is coated on the gas exhaust portion, or is manufactured as a separate film and attached to the gas exhaust portion.

6. The inner layer is water (H ２ 6. The battery cell of claim 1 , further comprising a getter material that reacts with O.

7. The battery cell according to claim 1 , wherein when gas generated inside the battery case flows into the gas exhaust portion, inner surfaces of the gas exhaust portion are separated from each other.

8. The battery cell according to claim 6 , wherein the gas exhaust 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 the upper portion of the electrode lead, the second lead film is located under the electrode lead, The battery cell according to claim 1 , wherein the gas exhaust portion is formed in each of the first lead film and the second lead film.

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 exhaust portion formed in the lead film is located outside an outer surface of the battery case.

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

13. The battery cell according to claim 1 , wherein the lead film is heat-sealed together with the sealing portion, and the gas exhaust portion is stored in a non-heat-sealed state and is left blank.

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

Images