Battery cell, battery module including battery cell, and sealing device

Abstract

In a battery cell including an electrode assembly and a pouch case for sealing the electrode assembly together with an electrolyte, the pouch case includes a storage portion for storing the electrode assembly, and a sealing portion disposed on an outer periphery of the storage portion for sealing the electrode assembly, the sealing portion including a strong sealing section and a weak sealing section, and a vent path including an inlet located on an inner surface of the sealing portion to be connected to the storage portion, and an outlet located on an outer surface of the sealing portion to be integrally connected to the inlet, is formed by the weak sealing section.

Description

[Technical Field]

[0001] The present invention relates to a battery cell, a battery module including the battery cell, and a sealing device for manufacturing the battery cell, and more particularly to a battery cell and a battery module for smoothly discharging internal gas, and a sealing device for manufacturing such a battery cell.This application claims priority to Korean Patent Application No. 10-2022-0181114, filed on December 21, 2022, the entire contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] Secondary batteries, which are easily applicable to various products and have electrical properties such as high energy density, are commonly used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are powered by electrical sources. These secondary batteries are attracting attention as a new energy source for improving energy efficiency, as they are environmentally friendly in that they do not produce any by-products due to energy use, in addition to their main advantage of dramatically reducing the use of fossil fuels.

[0003] Among common secondary battery structures, pouch-type secondary batteries have a structure in which an electrode assembly is housed in a pouch case to form a battery cell. Conventional battery cells are tightly bonded to the entire upper and lower cases of the pouch case through a heat sealing process, which prevents proper ventilation even when internal gas is generated due to swelling, resulting in the problem of the generated internal gas remaining inside and accumulating.

[0004] Due to these issues, if an external impact or electrical short occurs while the swelling phenomenon is maintained or accelerated, a chemical chain reaction with the internal chemical composition may occur, causing a fatal defect in which the battery cell explodes.

[0005] Furthermore, in the case of conventional battery cells, if the pouch case cannot withstand the internal gas pressure and bursts, it is difficult to predict and control which part of the pouch case will burst and in which direction the gas will be released. Such uncontrollable venting can cause safety issues for the secondary battery. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a battery cell that can induce internal gas generated inside a pouch case to be vented in a specific direction from a specific location.

[0007] Another problem to be solved by the present invention is to provide a battery module including the same.

[0008] Another problem to be solved by the present invention is to provide a sealing device for manufacturing such a battery cell. [Means for solving the problem]

[0009] In order to solve the above problems, a battery cell according to one embodiment of the present invention includes an electrode assembly and a pouch case for sealing the electrode assembly together with an electrolyte, The pouch case includes: a receiving portion in which the electrode assembly is received; a sealing portion disposed on an outer periphery of the receiving portion and sealingly sealing the electrode assembly, The sealing portion includes a strong sealing section and a weak sealing section, and a vent path including an inlet located on an inner surface of the sealing portion to be connected to the storage portion, and an outlet located on an outer surface of the sealing portion to be integrally connected to the inlet is formed by the weak sealing section.

[0010] Gas generated in the storage section can be released to the outside of the storage section through the vent path.

[0011] The seal portion may have a first seal portion extending in a first direction and in which the vent path is formed, and a second seal portion extending in a second direction intersecting the first direction, and the vent path may include at least one length vent portion extending in the first direction and a width vent portion extending in the second direction and connected to the length vent portion.

[0012] The length of the first seal portion in the first direction may be greater than the length of the second seal portion in the second direction, and the length of the length vent portion in the first direction may be greater than the length of the width vent portion in the second direction.

[0013] The leads of the electrode assembly may protrude through the second seal portion.

[0014] The inlet may be located at one end of the first seal portion and the outlet may be located at the other end of the first seal portion.

[0015] The sealing portion may further include a third sealing portion extending in the first direction and a fourth sealing portion extending in the second direction, and the vent path may not be formed in the third sealing portion.

[0016] The sealing portion includes an inner resin layer, a metal layer covering the inner resin layer, and an outer resin layer covering the metal layer. The inner resin layer includes the vent path and an adhesive portion that contacts the vent path to seal the electrode assembly. The sealing strength of the vent path may be lower than the sealing strength of the adhesive portion.

[0017] The thickness of the vent path may be greater than the thickness of the adhesive joint.

[0018] The metal layer may have a constant thickness, and the outer resin layer may have a constant thickness.

[0019] A battery module according to an embodiment of the present invention for solving the other problems described above includes the battery cells according to the embodiment of the present invention as described above and a module case that houses the battery cells, wherein inlets of the battery cells are aligned in one direction and outlets of the battery cells are aligned in the same direction.

[0020] A sealing device according to one embodiment of the present invention for solving the above-mentioned and other problems includes an upper sealing tool that applies pressure to a sealing portion included in the pouch case from above the sealing portion, and a lower sealing tool that applies pressure to the sealing portion from below the sealing portion included in the pouch case, and at least one of the upper sealing tool and the lower sealing tool has a step formed in it to correspond to a vent path including an inlet located on an inner surface of the sealing portion and an outlet located on an outer surface of the sealing portion to be integrally connected to the inlet.

[0021] The pressure applied to the seal portion by the region where the step is formed may be smaller than the pressure applied to the seal portion by the region where the step is not formed.

[0022] The body of at least one of the upper and lower sealing tools may be recessed in the surface that contacts the sealing portion to form the step, and the body thickness in the area where the step is formed may be smaller than the body thickness in the area where the step is not formed.

[0023] The seal portion may have a first seal portion extending in a first direction and in which the vent path is formed, and a second seal portion extending in a second direction intersecting the first direction, the vent path including at least one length vent portion extending in the first direction and a width vent portion extending in the second direction and connected to the length vent portion, and the step may be formed to correspond to the length vent portion and the width vent portion. [Effects of the Invention]

[0024] To achieve the above object, a battery cell according to an embodiment of the present invention may include an electrode assembly and a pouch case for sealing the electrode assembly together with an electrolyte. The pouch case may include a receiving portion for receiving the electrode assembly and a sealing portion disposed on an outer periphery of the receiving portion for sealing the electrode assembly. The sealing portion may have a vent path formed therein, the vent path including an inlet located on an inner surface of the sealing portion and connected to the receiving portion, and an outlet located on an outer surface of the sealing portion and integrally connected to the inlet.

[0025] Conventional battery cells have a problem in that internal gas generated due to swelling or the like cannot be properly discharged. However, the present invention can guide the internal gas to be vented in a specific direction through the vent path. Furthermore, by forming the vent path long along the long side of the pouch case, the cumulative flow rate until the internal gas is vented can be increased, and more internal gas can be trapped inside the pouch case. Furthermore, because the vent path is formed in the existing pouch case, no additional volume is required for the vent path, thereby making it possible to maximize the use of the margin volume of the battery cell.

[0026] In the battery module according to the present invention, the battery cells can be accommodated with the vent paths aligned, thereby guiding the internal gas of the battery cells to be vented in a specific direction, thereby improving the safety of the battery module.

[0027] The sealing device according to the present invention may include a sealing tool having a step formed therein corresponding to the vent path to be formed in the battery cell. By using the sealing device according to the present invention, the vent path can be easily formed in the battery cell.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a perspective view illustrating a battery cell according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of areas A and B in FIG. [Figure 3] FIG. 2 is a plan view illustrating the battery cell of FIG. [Figure 4] FIG. 4 is an enlarged plan view of region C in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line II' in FIG. [Figure 6] 2 is a perspective view for explaining a method for manufacturing the battery cell of FIG. 1. FIG. [Figure 7] FIG. 7 is a perspective view for explaining the sealing tool of FIG. 6. [Figure 8] 2 is a perspective view illustrating a battery module including the battery cell of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will become more apparent by describing in detail preferred embodiments of the present invention with reference to the accompanying drawings. The embodiments described herein are shown as examples to facilitate understanding of the invention, and it should be understood that the present invention can be implemented in various modifications different from the embodiments described herein. In addition, to facilitate understanding of the invention, the accompanying drawings are not drawn to scale, and the dimensions of some components may be exaggerated.

[0031] FIG. 1 is a perspective view illustrating a battery cell according to one embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of areas A and B in FIG. 1, and FIG. 3 is a plan view illustrating the battery cell in FIG. 1.

[0032] 1 , a battery cell 10 according to one embodiment of the present invention may include an electrode assembly 100 and a pouch case 200. The battery cell 10 may have a rectangular shape including long sides extending in a first direction X and short sides extending in a second direction Y intersecting the first direction X, and may have a thickness in a third direction Z perpendicular to the first direction X and the second direction Y.

[0033] The electrode assembly 100 includes a negative electrode, a positive electrode, and a separator, and the negative electrodes and positive electrodes may be alternately arranged with a separator interposed between them. The electrode assembly 100 may be a stacked electrode assembly, a stack / folding electrode assembly, or a jelly roll type. For example, the stacked electrode assembly may have a structure in which positive electrodes and negative electrodes cut into predetermined sizes are stacked in order with a separator interposed therebetween. The stacked / folding electrode assembly may have a structure in which a bi-cell or full-cell in which predetermined units of positive electrodes and negative electrodes are stacked with a separator interposed therebetween is wound. The illustrated example is a jelly roll type, and the jelly roll type may have a structure in which a laminate of a positive electrode, a separator, and a negative electrode on a sheet is wound.

[0034] The electrode assembly 100 may also include a positive electrode tab extending from the positive electrode and a negative electrode tab extending from the negative electrode. The positive electrode tab and the negative electrode tab are connected to a positive electrode lead 110 and a negative electrode lead 120, respectively. The positive electrode lead 110 and the negative electrode lead 120 protrude externally and serve as electrodes of the electrode assembly 100, electrically connecting the electrode assembly 100 to external devices, etc. The illustrated example is a unidirectional battery. The positive electrode lead 110 and the negative electrode lead 120 protrude side by side from one side of the electrode assembly 100, protruding in one direction from the electrode assembly 100, thereby constituting a unidirectional battery. As another example, the positive electrode lead 110 and the negative electrode lead 120 protrude from opposing sides of the electrode assembly 100, protruding in both directions from the electrode assembly 100, thereby constituting a bidirectional battery.

[0035] The pouch case 200 can seal the electrode assembly 100 together with the electrolyte, and for this purpose, can include an upper case 210 and a lower case 220. The upper case 210 and the lower case 220 can each be made of separate cut sheet members, or can be made by folding a single connected sheet member.

[0036] 2, each of the upper case 210 and the lower case 220 may have a layered structure including an inner resin layer 211, a metal layer 212, and an outer resin layer 213. The metal layer 212 may cover the inner resin layer 211, and the outer resin layer 213 may cover the metal layer 212.

[0037] The inner resin layers 211 of the upper case 210 and the lower case 220 may abut against each other. To bond the inner resin layers 211 to each other, the inner resin layers 211 may be made of cast polypropylene (CPP) or polypropylene (PP).

[0038] The metal layer 212 may be formed of an aluminum thin film to protect the electrode assembly 100 and the electrolyte, complement the electrochemical properties of the battery cell 10, and improve heat dissipation. In this case, to ensure insulation between the battery cell 10 and the outside by the metal layer 212, the outer resin layer 213 may be formed of an insulating material such as polyethylene terephthalate (PET) resin or nylon resin.

[0039] 1 and 3, the pouch case 200 may be divided into a receiving portion SDP and a sealing portion SLP. The receiving portion SDP receives the electrode assembly 100, and the sealing portion SLP is disposed on the outer periphery of the receiving portion SDP, so that the upper case 210 and the lower case 220 contact each other to seal the electrode assembly 100.

[0040] The seal portion SLP may have a first seal portion SLP1 extending in a first direction X, a second seal portion SLP2 extending in a second direction Y intersecting the first direction X, a third seal portion SLP3 extending in the first direction X and facing the first seal portion SLP1, and a fourth seal portion SLP4 extending in the second direction Y and facing the second seal portion SLP2.

[0041] For example, when the pouch case 200 has a rectangular shape, the first direction X may be the length direction forming the long sides of the pouch case 200, and the second direction Y may be the width direction forming the short sides of the pouch case 200. The positive electrode lead 110 and the negative electrode lead 120 protrude through the second seal portion SLP2.

[0042] In the illustrated example, the upper case 210 and the lower case 220 are separate sheet members, and therefore four-sided sealing is performed. When a single connected sheet member is folded for use, sealing can be omitted by bringing the side edges of the electrode assembly 100 into close contact with the folded portion, making it possible to achieve three-sided sealing. For example, the seal portion SLP can be configured with only the first seal portion SLP1, the second seal portion SLP2, and the fourth seal portion SLP4, without having the third seal portion SLP3.

[0043] Various materials can be used for the positive electrode, negative electrode, and electrolyte of a battery cell, and typically, lithium-based oxides are used for the positive electrode, carbon-based materials for the negative electrode, and organic solvent electrolytes containing lithium salts are used for the electrolyte. In this case, if the battery is overcharged or if a sudden change in the electrical environment occurs, electrolyte decomposition may occur at the positive electrode and lithium metal may precipitate at the negative electrode. The heat generated by these chemical reactions may generate gas inside the housing SDP.

[0044] In addition, organic solvents such as ethylene carbonate and propylene carbonate are used as electrolytes, and these organic solvents decompose at high temperatures to generate gases, which can increase pressure and cause swelling of the housing SDP. This swelling can not only cause an electrical short, but also poses a risk of leaking internal gases if the swollen battery is subjected to external impact, which can cause sparks and lead to fire.

[0045] In conventional battery cells, the heat sealing process is performed on the entire upper and lower cases of the pouch case, and the entire pouch case is tightly bonded. Therefore, even if internal gas is generated due to swelling or other factors, the location of the gas discharge cannot be adjusted, resulting in vents occurring at any position, which can lead to electrolyte leakage and the risk of fatal defects such as battery cell fire and explosion.

[0046] For this reason, it is important to predict and control the direction in which the pouch case of a battery cell will burst due to its inability to withstand the internal gas pressure and release the gas.

[0047] To solve the above-mentioned problems, a vent path (e.g., the vent path VP in FIG. 4 ) may be formed in the first seal portion SLP1 of the battery cell 10 according to the embodiment of the present invention. The first seal portion SLP1 includes a strong seal section and a weak seal section, and the vent path VP may be formed by the weak seal section. The strong seal section refers to a section that is sealed more strongly than the surrounding area, and the weak seal section refers to a section that is sealed less strongly than the surrounding area. The section that is sealed more strongly than the surrounding area is sealed with a sealing tool pressure that presses more strongly than the surrounding area. The section that is sealed more strongly than the surrounding area also has a greater seal strength (strength that spreads in both directions) of the sealing surface after sealing than the surrounding area. The section that is sealed less strongly than the surrounding area is sealed with a sealing tool pressure that presses less strongly than the surrounding area. The section that is sealed less strongly than the surrounding area also has a smaller seal strength of the sealing surface after sealing than the surrounding area. The strong seal section and the weak seal section are relative concepts, and the weak seal section refers to a section that is sealed less strongly than the strong seal section. For example, the weakly sealed section may be a section having a seal strength that is 60% to 80% of the seal strength of the strongly sealed section.

[0048] According to the present invention, the internal gas can be vented from a specific location in a specific direction via the vent path VP. If the vent location is random, safety issues such as electrolyte leakage may occur. According to the present invention, the vent location can be controlled to a specific location and direction of the battery cell 10, thereby improving safety.

[0049] Furthermore, as will be described later, by forming the vent path VP long along the long side direction of the seal portion SLP, it is possible to increase the cumulative flow rate until the internal gas is vented, and to trap more internal gas inside the pouch case 200. In other words, the venting time can be delayed, allowing the battery cell 10 to be used safely for a longer period of time.

[0050] Furthermore, because the vent path VP is formed in the existing pouch case 200 without providing a separate space for it, no additional volume is required for the vent path VP, thereby making it possible to make maximum use of the available volume of the battery cell 10. In other words, there is no need to provide a separate space in the storage section SDP to trap internal gas, and the storage section SDP can be filled with an electrode assembly 100 of the same size, so there is no loss of battery capacity.

[0051] Hereinafter, the structure of the vent path of the battery cell according to an embodiment of the present invention will be described in more detail with reference to FIGS.

[0052] 4 is an enlarged plan view of region C in FIG. 3, and FIG. 5 is a cross-sectional view taken along line II' in FIG.

[0053] 3 and 4, the first seal portion SLP1 may have a vent path VP formed therein, the vent path VP including an inlet IP, a first length vent portion LVP1, a first width vent portion WVP1, a second length vent portion LVP2, a second width vent portion WVP2, a third length vent portion LVP3, and an outlet OP. The vent path VP may include an inlet IP and an outlet OP integrally connected to the inlet IP. In an embodiment, the length vent portion of the vent path VP may extend in the first direction X and may be included in the vent path VP, and the width vent portion of the vent path VP may extend in the second direction Y and be connected to the length vent portion. The number and positions of the length vent portions and width vent portions may be changed as needed. In an embodiment, the length of the first seal portion SLP1 in the first direction X is greater than the length of the second seal portion SLP2 in the second direction Y. In this case, the length of the length vent portion in the first direction X is greater than the length of the width vent portion in the second direction Y.

[0054] The first to third length vent portions LVP1, LVP2, and LVP3 may have the same length and width. The first width vent portion WVP1 and the second width vent portion WVP2 may also have the same length and width. By making the first to third length vent portions LVP1, LVP2, and LVP3 have the same length and width and the first width vent portion WVP1 and the second width vent portion WVP2 have the same length and width, the vented internal gas can apply pressure to the vent path VP evenly, thereby improving the safety of the battery cell 10.

[0055] In one embodiment, the seal portion SLP includes a first seal portion SLP1 and a third seal portion SLP3 in the longitudinal direction of the battery cell 10. The vent path VP may be formed only in the first seal portion SLP1. That is, the third seal portion SLP3 may not have a vent path formed therein. By forming the vent path VP through which the internal gas is vented only in the first seal portion SLP1, the internal gas can be guided to be vented in a specific direction. However, the present invention is not limited thereto, and the vent path VP may be further formed in the second seal portion SLP2, the third seal portion SLP3, and / or the fourth seal portion SLP4 as necessary.

[0056] In the first sealing part SLP1 in which the vent path VP is formed, the portion excluding the vent path VP can be defined as the adhesive part ADS. The vent path VP and the adhesive part ADS are included in the inner resin layer 211 of the sealing part SLP. The adhesive part ADS contacts the vent path VP and can seal the electrode assembly 100.

[0057] In one embodiment, the seal strength of the vent path VP may be less than the seal strength of the adhesive joint ADS. The vent path VP may be a weakly sealed section, and the adhesive joint ADS may be a strongly sealed section. For example, the seal strength of the vent path VP may be 60% to 80% of the seal strength of the adhesive joint ADS. As an example, the seal strength of the adhesive joint ADS may be 0.2 MPa to 0.5 MPa, and the seal strength of the vent path VP may be 0.12 MPa to 0.4 MPa.

[0058] By making the sealing strength of the vent path VP relatively weaker than that of the surrounding area, the internal gas can be induced to vent along the vent path VP. Specifically, when internal gas is generated and condenses in the storage portion SDP, the internal gas opens the inlet IP of the vent path VP, which has a relatively low sealing strength, and the internal gas remains in the space, relaxing the internal pressure. As further gas is generated and the internal pressure increases, the first length vent portion LVP1 connected to the inlet IP is opened, allowing the internal gas to move into the space and relax the internal pressure. As further gas is generated, the gas moves sequentially through the first width vent portion WVP1, the second length vent portion LVP2, the second width vent portion WVP2, and the third length vent portion LVP3, as described above, thereby relaxing the internal pressure and finally venting to the outside through the outlet OP. In this way, the gas generated in the storage portion SDP is released to the outside of the storage portion SDP via the vent path VP.

[0059] In one embodiment, the inlet IP may be located on an inner surface of the first sealing portion SLP1 so as to be connected to the storage portion SDP. The inner surface of the first sealing portion SLP1 points to the side of the first sealing portion SLP1 closer to the electrode assembly 100. The first length vent portion LVP1 may be connected to the inlet IP and extend in the first direction X. The first width vent portion WVP1 may be connected to the first length vent portion LVP1 and extend in the second direction Y. The second length vent portion LVP2 may be connected to the first width vent portion WVP1 and extend in the first direction X. The second width vent portion WVP2 may be connected to the second length vent portion LVP2 and extend in the second direction Y. The third length vent portion LVP3 may be connected to the second width vent portion WVP2 and extend in the first direction X. The outlet OP may be connected to the third length vent portion LVP3 and be located on an outer surface of the first sealing portion SLP2. The outer surface of the first seal portion SLP1 also refers to the side farther from the electrode assembly 100 in the first seal portion SLP1.

[0060] In this case, the length in the first direction X of the first longitudinal vent portion LVP1 may be greater than the length in the second direction Y of the first width vent portion WVP1.

[0061] In one embodiment, the inlet IP may be located at one end of the first seal portion SLP1 in the length direction, and the outlet OP may be located at the other end opposite to the one end of the first seal portion SLP1. In other words, the vent path VP may be defined with an odd number of length vent portions (e.g., first to third length vent portions LVP1, LVP2, and LVP3 shown in FIG. 4) or an even number of width vent portions (e.g., first and second width vent portions WVP1 and WVP2 shown in FIG. 4).

[0062] The length of the first length vent portion LVP1 in the first direction X is greater than the length of the first width vent portion WVP1 in the second direction Y, and the inlet IP and outlet OP are located at both ends of the first seal portion SLP1, respectively, thereby increasing the maximum cumulative flow rate value of the vented internal gas and enabling more internal gas to be trapped inside the pouch case 200.

[0063] 4 and 5, the first sealing part SLP1 may have a layered structure including an inner resin layer 211, a metal layer 212, and an outer resin layer 213.

[0064] In one embodiment, the inner resin layer 211 may include a vent path VP and an adhesive portion ADS. In other words, the vent path VP may be formed in the inner resin layer 211. In a cross-sectional view, the thickness of the vent path VP may be greater than the thickness of the adhesive portion ADS. This allows the sealing strength of the vent path VP to be smaller than the sealing strength of the adhesive portion ADS. For example, the thickness of the vent path VP may be 105% to 120% of the thickness of the adhesive portion ADS.

[0065] Before sealing, the thickness of the inner resin layer 211 included in each of the upper case 210 and the lower case 220 may be the same and constant. When heat is applied during sealing, the inner resin layer 211 of the upper case 210 and the inner resin layer 211 of the lower case 220, which are in contact with each other, melt and become fluid. If more pressure is applied to one part at this time, the fluidized inner resin layer 211 moves and gathers on the side where less pressure is applied, which may result in a difference in thickness of the inner resin layer 211 after sealing is complete. The thickness of the inner resin layer 211 is thin in parts where more pressure is applied during sealing, and thick in parts where less pressure is applied. The parts where more pressure is applied during sealing are strong sealed sections, and the parts where less pressure is applied are weak sealed sections.

[0066] In one embodiment, the thickness of the metal layer 212 and the thickness of the outer resin layer 213 may each be constant, so that when the vent path VP is formed toward the upper case 210, a step may be formed on the top surface of the upper case 210, as shown in FIG.

[0067] However, the present invention is not limited to this. In embodiments of the present invention, various structures can be applied that can achieve a relatively low sealing strength of the vent path VP. For example, in other embodiments, the vent path VP can be formed toward the lower case 220, and in other embodiments, the vent path VP can be formed in both the upper case 210 and the lower case 220.

[0068] FIG. 6 is a perspective view illustrating a method for manufacturing the battery cell of FIG. 1, and FIG. 7 is a perspective view illustrating the sealing tool of FIG.

[0069] 6 and 7, the battery cell 10 is composed of an electrode assembly 100 and a pouch case 200. The electrode assembly 100 includes the general structure of a secondary battery cell, such as an electrode current collector and an electrode tab. First and second electrode leads 110 and 120, which function as electrodes of the secondary battery, may be attached to the electrode tabs of corresponding polarities by welding or the like.

[0070] 6(a), the electrode assembly 100 can be housed in a housing portion SDP of a pouch case 200 so that a portion of the positive electrode lead 110 and a portion of the negative electrode lead 120 of the electrode assembly 100 are exposed to the outside. In addition, an electrolyte can be injected into the housing portion SDP.

[0071] Then, as shown in FIG. 6(b), when the electrode assembly 100 is stored in the storage portion SDP, the upper case 210 and the lower case 220 can be brought closer to each other so that the positive electrode lead 110 and the negative electrode lead 120 are exposed to the outside, thereby forming the outer shape of the sealing portion SLP.

[0072] 6(c), the outer peripheries of the upper case 210 and the lower case 220 can be sealed by a heat sealing process. The heat sealing process can be performed by applying heat and pressure to the seal portion SLP using a sealing device ST.

[0073] For example, the sealing device ST may include an upper sealing tool UST having a shape corresponding to the upper case 210 of the first sealing part SLP1, and a lower sealing tool LST having a shape corresponding to the lower case 220 of the first sealing part SLP1. The upper sealing tool UST can apply pressure to the first sealing part SLP1 from above the first sealing part SLP1, and the lower sealing tool LST can apply pressure to the first sealing part SLP1 from below the first sealing part SLP1.

[0074] The upper case 210 and the lower case 220 may be disposed between the upper sealing tool UST and the lower sealing tool LST, and heat and pressure may be applied to form the seal portion SLP. At least one of the upper sealing tool UST and the lower sealing tool LST may have a step formed therein corresponding to the vent path VP described above with reference to Fig. 4. The body of at least one of the upper sealing tool UST and the lower sealing tool LST may have a recessed surface that contacts the seal portion SLP to form a step.

[0075] As shown in Figure 7, steps STP may be formed in the upper sealing tool UST to correspond to the vent paths VP described above with reference to Figure 4. For example, the steps STP may be formed to correspond to the inlet IP, first length vent portion LVP1, first width vent portion WVP1, second length vent portion LVP2, second width vent portion WVP2, third length vent portion LVP3, and outlet OP described above with reference to Figure 4.

[0076] In one embodiment, the body thickness of the upper seal tool UST in the region where the step STP is formed may be smaller than the body thickness of the upper seal tool UST in the region where the step STP is not formed. For example, the lower surface of the upper seal tool UST in the region where pressure is applied to the vent path VP may be formed higher than the lower surface of the upper seal tool UST in the region where pressure is applied to the adhesive part ADS. As a result, the pressure applied to the first seal portion SLP1 by the region where the step STP is formed may be smaller than the pressure applied to the first seal portion SLP1 by the region where the step STP is not formed.

[0077] While the surface of a conventional sealing tool that comes into contact with a pouch case is generally flat, the sealing tool of the present invention has steps formed so that the height varies depending on the position, thereby making it possible to adjust the sealing pressure and therefore the sealing strength depending on the position.In this way, by using the sealing device ST of the present invention, a vent path VP can be easily formed in the battery cell 10.

[0078] FIG. 8 is a perspective view for explaining a battery module including the battery cell of FIG.

[0079] 8, a battery module 1 according to an embodiment of the present invention may include the battery cells 10 described with reference to FIG. 1 and a module case MC that houses the battery cells 10.

[0080] Small mobile devices use one or two to four battery cells per device, whereas medium- to large-sized devices such as automobiles require high output and large capacity. Therefore, medium- to large-sized battery modules are used, which include a cell stack in which multiple battery cells are electrically connected. A battery module 1 manufactured by electrically connecting battery cells 10 can be used as such a medium- to large-sized battery module. The battery cells 10 are connected to each other so as to ensure the required power depending on the application requiring the power of such a battery module 1.

[0081] In a battery module 1 according to one embodiment, the battery cells 10 can be housed in a module case MC with their vent paths VP aligned. As shown in FIG. 8 , the inlets IP of the battery cells 10 can be aligned in one direction, and the outlets OP can be aligned in the same direction. This allows the internal gas in the battery cells 10 to be guided to vent in a specific direction. This improves the safety of the battery module 1.

[0082] Although the present invention has been described above using limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0083] 1 Battery Module 10 battery cells 100 electrode assembly 110 First electrode lead 120 Second electrode lead 200 pouch cases 210 Upper Case 211 Internal resin layer 212 Metal layer 213 Outer resin layer 220 Lower Case

Claims

1. A battery cell including an electrode assembly and a pouch case for sealing the electrode assembly, The pouch case includes: a receiving portion in which the electrode assembly is received; a sealing portion disposed on an outer periphery of the receiving portion and sealingly sealing the electrode assembly, a battery cell, wherein the sealing portion includes a strong sealing section and a weak sealing section, and a vent path is formed by the weak sealing section, the vent path including an inlet located on an inner surface of the sealing portion to be connected to the storage portion, and an outlet located on an outer surface of the sealing portion to be integrally connected to the inlet.

2. The battery cell according to claim 1 , wherein gas generated in the storage portion is released to the outside of the storage portion through the vent path.

3. The sealing portion is a first seal portion extending in a first direction and having the vent path formed therein; a second seal portion extending in a second direction intersecting the first direction, The vent path is at least one longitudinal vent extending in the first direction; The battery cell of claim 1 , further comprising: a width vent portion extending in the second direction and connected to the length vent portion.

4. a length of the first seal portion in the first direction is greater than a length of the second seal portion in the second direction; The battery cell according to claim 3 , wherein the length of the longitudinal vent portion in the first direction is greater than the length of the width vent portion in the second direction.

5. The battery cell according to claim 3 , wherein the lead of the electrode assembly protrudes through the second sealing portion.

6. the inlet is located at one end of the first seal portion; The battery cell according to claim 3 , wherein the outlet is located at the other end of the first seal portion.

7. The sealing portion is a third seal portion extending in the first direction; a fourth seal portion extending in the second direction, The battery cell according to claim 3 , wherein the third seal portion does not have the vent path formed therein.

8. the sealing portion includes an inner resin layer, a metal layer covering the inner resin layer, and an outer resin layer covering the metal layer, the inner resin layer includes the vent path and an adhesive portion that contacts the vent path and seals the electrode assembly; The battery cell according to claim 1 , wherein the vent path has a seal strength that is lower than the seal strength of the adhesive portion.

9. The battery cell of claim 8 , wherein the thickness of the vent path is greater than the thickness of the adhesive portion.

10. the thickness of the metal layer is constant; The battery cell according to claim 8 , wherein the thickness of the outer resin layer is constant.

11. The battery cell according to claim 1; a module case that houses the battery cells; the inlets of the battery cells are aligned side by side in one direction; The battery module, wherein each of the outlets of the battery cells are aligned in the one direction.

12. In a sealing device for sealing a pouch case, an upper sealing tool that applies pressure to the seal portion included in the pouch case from above the seal portion; a lower sealing tool that applies pressure to the seal portion from below the seal portion included in the pouch case, At least one of the upper sealing tool and the lower sealing tool has: A seal device, the seal device having a step formed to correspond to a vent path including an inlet located on an inner surface of the seal portion and an outlet located on an outer surface of the seal portion so as to be integrally connected to the inlet.

13. The sealing device according to claim 12 , wherein the pressure applied to the seal portion by the region where the step is formed is smaller than the pressure applied to the seal portion by the region where the step is not formed.

14. 14. The sealing device according to claim 13, wherein the body of at least one of the upper sealing tool and the lower sealing tool is recessed in a surface that contacts the sealing portion to form the step, and the body thickness in the area where the step is formed is smaller than the body thickness in the area where the step is not formed.

15. The sealing portion is a first seal portion extending in a first direction and having the vent path formed therein; a second seal portion extending in a second direction intersecting the first direction, the vent path includes at least one length vent portion extending in the first direction and a width vent portion extending in the second direction and connected to the length vent portion; The sealing device of claim 12 , wherein the step is formed to correspond to the length vent portion and the width vent portion.

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