Battery cell including a seal portion formed with an embossed pattern and a seal block for manufacturing a battery cell

Abstract

The present invention relates to a battery cell including a pouch-type battery case configured to accommodate an electrode assembly therein, wherein the pouch-type battery case is provided with a sealing portion at an outer circumference thereof surrounding an electrode assembly accommodation portion, and a pattern of embossing is formed on the sealing portion in all directions, whereby the sealing force of the pouch-type battery cell can be increased without adding a separate battery cell manufacturing process.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 2021-0138266, filed on October 18, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This invention relates to a battery cell including a sealing portion with an embossed pattern and a sealing block for manufacturing the battery cell. More specifically, this invention relates to a battery cell including a sealing portion with an embossed pattern and a sealing block for manufacturing the battery cell, wherein the embossed pattern is configured to prevent easy venting of the sealing portion of a pouch cell. Background Technology

[0003] Rechargeable and dischargeable lithium-ion batteries are widely used as an energy source for wireless mobile devices or wearable devices worn on the body, as well as for electric and hybrid vehicles as alternatives to existing gasoline and diesel vehicles that cause air pollution.

[0004] Based on the material and shape of the battery casing, lithium secondary batteries can be classified into cylindrical battery cells with electrode assemblies mounted in a metal can, prismatic battery cells with battery assemblies mounted in a metal can, or pouch battery cells with electrode assemblies mounted in a battery casing made of laminated sheets. Pouch battery cells have the advantages of being easily deformable and having high energy density.

[0005] To seal pouch cell batteries, a method is used that uses a high-temperature sealing block to compress the outer periphery of the battery casing to form a seal. However, if this sealing method is used, the pouch cell is prone to venting when the internal pressure increases.

[0006] Therefore, methods have been designed to improve the sealing performance of pouch cell batteries.

[0007] Patent Document 1 discloses an energy storage device configured such that in a sealed container formed by an energy storage device sheathing member comprising sequentially stacked metal foil layers, a corrosion-resistant layer, and a sealant layer, the edge portions of the sealant layers in contact with each other are sealed by heat sealing, and a thin recess is formed at the edge portions.

[0008] In Patent Document 1, a thin portion is formed at the sealing part formed by heat sealing, thereby making the edge portion easy to bend.

[0009] Patent document 2 discloses a film-coated battery including a covering film, which is configured such that at least a hot-melt resin layer and a metal thin film layer are stacked, the battery element is surrounded with the hot-melt resin layer facing inward, and the outer periphery of the joint is heat-fused to seal the battery element, wherein at least one bend is formed at the joint, and the thickness of the bend is less than the thickness of the joint around the bend.

[0010] In Patent Document 2, a curved portion with a relatively small thickness is formed at the joint of the coating film, thereby preventing cracks from forming at the curved portion due to the difference in the extension of the film on the inner and outer sides of the joint.

[0011] Patent document 3 discloses a sealing device for pre-sealing, which sequentially performs pre-sealing and main sealing to seal a pouch-type battery housing. The sealing device includes a press portion configured to heat and compress one and another surface of the outer periphery of a sheet member for the battery housing to form a pre-sealed portion and a pair of sealing blocks. Each sealing block includes a fixing portion configured to fix the sheet member. A sealing protrusion is formed outwardly on the press portion, and the outer end of the sealing protrusion is rounded when viewed in a vertical section.

[0012] In Patent Document 3, a pre-sealing is performed before the main seal, thereby reducing the formation of wrinkles on the outer surface of the battery cell.

[0013] However, the aforementioned patent documents do not propose a technology that can easily provide a structure that can increase the sealing force of pouch cell batteries; therefore, such a technology needs to be developed.

[0014] (Existing technical literature)

[0015] (Patent Document 1) Japanese Patent Application Publication No. 2013-157286 (August 15, 2013)

[0016] (Patent Document 2) Korean Patent Application Publication No. 2006-0064686 (April 18, 2006)

[0017] (Patent Document 3) Korean Patent Application Publication No. 2018-0028714 (March 19, 2018) Summary of the Invention

[0018] Technical issues

[0019] The present invention was made in view of the above problems. One object of the present invention is to provide a battery cell including a sealing portion formed with an embossed pattern, which allows for the application of a structure in which the sealing force of the sealing portion of the pouch battery cell is increased using a simple method.

[0020] Technical solution

[0021] To achieve the above objectives, the battery cell according to the present invention includes a pouch-type battery housing configured to house an electrode assembly inside, wherein the pouch-type battery housing has a sealing portion around its outer periphery surrounding the electrode assembly housing portion, and an embossed pattern is formed on the sealing portion in all directions.

[0022] The embossed pattern can be formed such that the relief when viewed from above the seal is an intaglio when viewed from below the seal, and the intaglio when viewed from above the seal is a relief when viewed from below the seal.

[0023] The embossed pattern can be formed such that when viewed from above the seal, relief and intaglio alternately repeat.

[0024] The embossed pattern can be formed at specified dimensions and intervals.

[0025] The spacing of the embossed pattern formed on the sealing part in the direction where the electrode lead protrudes can be smaller than the spacing of the embossed pattern formed on the sealing part in the direction where the electrode lead does not protrude.

[0026] The vertical cross-section of the embossed pattern can be polygonal, semi-circular, or semi-elliptical.

[0027] This invention provides a sealing block for manufacturing battery cells. Specifically, the sealing block includes an upper sealing block disposed above the sealing portion of a pouch battery cell and a lower sealing block disposed below the sealing portion of the pouch battery cell. The upper and lower sealing blocks are provided with recesses and protrusions, which are configured to engage with each other at corresponding positions on the upper and lower sealing blocks.

[0028] The protrusion can protrude toward the sealing portion of the pouch cell.

[0029] Alternatively, the protrusion can be configured such that the shape of the protrusion protruding upward toward the sealing portion of the pouch cell and the shape of the protrusion protruding downward toward the sealing portion of the pouch cell are alternately repeated.

[0030] The present invention provides a battery module comprising individual battery cells as unit cells.

[0031] Furthermore, the present invention can provide various combinations of the above-mentioned solutions.

[0032] Beneficial effects

[0033] As is evident from the above description, the battery cell according to the invention is configured such that an embossed pattern is formed over the entire sealing portion, thereby increasing the total surface area of ​​the sealing portion. Therefore, the contact area between the upper and lower housings can be increased, thereby increasing the sealing force of the battery cell.

[0034] Therefore, even when the pouch cell deforms, the seal can be prevented from opening, and even when the internal pressure of the cell increases, the cell explosion can be suppressed.

[0035] Furthermore, during the conventional battery cell manufacturing process, embossed patterns can be formed on the sealing part, so there is no need to add production facilities. Attached Figure Description

[0036] Figure 1 This is a perspective view of a battery cell according to the first embodiment.

[0037] Figure 2 This is a perspective view of a battery cell according to the second embodiment.

[0038] Figure 3 This is a vertical cross-sectional view of the sealing portion of a battery cell.

[0039] Figure 4 This is a vertical sectional view of the sealing block according to the third embodiment.

[0040] Figure 5 This is a vertical sectional view of the sealing block according to the fourth embodiment.

[0041] Figure 6 This is a graph showing the results of the structural simulation of the maximum deformation when an internal pressure of 0.01 MPa is applied to Experimental Example 1.

[0042] Figure 7 This is a graph showing the results of the structural simulation of the maximum deformation when an internal pressure of 0.01 MPa is applied to Experimental Example 2.

[0043] Figure 8 This is a graph showing the results of the maximum stress structure simulation when an internal pressure of 0.01 MPa is applied to Experimental Example 1.

[0044] Figure 9 This is a graph showing the results of the maximum stress structure simulation when an internal pressure of 0.01 MPa is applied to Experimental Example 2.

[0045] Figure 10 This is a graph showing the results of structural simulation of the maximum deformation when an internal pressure of 0.1 MPa is applied to Experimental Example 1.

[0046] Figure 11 This is a graph showing the results of structural simulation of the maximum deformation when an internal pressure of 0.1 MPa is applied to Experimental Example 2.

[0047] Figure 12 This is a graph showing the results of the maximum stress structure simulation when an internal pressure of 0.1 MPa is applied to Experimental Example 1.

[0048] Figure 13 This is a graph showing the results of the maximum stress structure simulation when an internal pressure of 0.1 MPa is applied to Experimental Example 2. Detailed Implementation

[0049] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement these preferred embodiments. However, in describing the working principle of the preferred embodiments of the present invention, detailed descriptions of known functions and configurations included herein that would obscure the subject matter of the invention will be omitted.

[0050] Furthermore, throughout the accompanying drawings, the same reference numerals will be used to refer to components that perform similar functions or operations. Throughout the specification, when a component is referred to as being connected to another component, that component can be directly connected to the other component, or indirectly connected to the other component through yet another component. Moreover, unless otherwise stated, including a particular element does not mean excluding other elements, but rather that those elements may be included.

[0051] Furthermore, unless otherwise specified, descriptions of elements by limiting or adding details can be applied to all inventions and are not limited to specific inventions.

[0052] Furthermore, in the specification of this invention and the claims of this application, unless otherwise stated, the singular form is intended to include the plural form.

[0053] Furthermore, in the specification of this invention and the claims of this application, unless otherwise stated, "or" includes "and". Therefore, "including A or B" refers to three cases: including A, including B, and including both A and B.

[0054] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0055] Figure 1 This is a perspective view of a battery cell according to the first embodiment.

[0056] The battery cell 100 is a pouch cell, which includes a pouch cell housing 110 made of laminated sheet material. The pouch cell housing 110 includes an upper housing 111 and a lower housing 112 located below the upper housing 111. The upper housing 111 has an electrode assembly receiving portion 114 configured to house an electrode assembly formed therein.

[0057] The battery casing can be made of a laminate configured to consist of an outer resin layer, an air and moisture barrier metal layer, and a heat-fusible inner resin layer stacked together.

[0058] The outer resin layer is required to exhibit excellent resistance to the external environment; therefore, it needs to have greater than predetermined tensile strength and weather resistance. For example, the outer resin layer may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or oriented nylon.

[0059] The metal layer can be made of aluminum (Al) or an aluminum alloy so that, in addition to preventing the introduction of foreign matter such as gas and moisture or preventing electrolyte leakage, it also improves the strength of the battery casing.

[0060] A polymeric resin that exhibits heat-melting properties, low hygroscopicity to the electrolyte, and does not swell or corrode due to the electrolyte can be used as the inner resin layer. For example, the inner resin layer can be made of cast polypropylene (CPP) film.

[0061] The upper housing 111 and the lower housing 112 are in contact with each other at their outer periphery surrounding the electrode assembly housing. When the outer periphery is heated and pressurized, the inner resin layers of the upper housing and the lower housing melt and bond together to form a seal 115.

[0062] In the battery cell 100, the upper housing 111 and the lower housing 112 are connected to each other, and the sealing portion 115 is formed on the outer periphery in three directions other than the curved portion.

[0063] That is, the sealing portions formed on the outer periphery in three directions include sealing portions in the total width direction (W) and sealing portions in the total length direction (H) located at opposite ends of the battery cell, and embossed patterns 116 are formed on all sealing portions.

[0064] Embossed pattern 116 can be formed on all sealing parts, set at specified dimensions and intervals, so that all sealing parts have the same sealing force.

[0065] Alternatively, since the internal pressure increases to the maximum extent at the center of the total length direction (H) of the seal, an embossed pattern can be formed at smaller intervals on the center of the total length direction.

[0066] Alternatively, the electrode lead 120 extends outward from the battery casing at the sealing portion in the total width direction (W), and the sealing force of the electrode lead 120 at its protruding portion is further reduced. Therefore, to prevent the sealing force at the protruding portion of the electrode lead 120 from decreasing, the embossed pattern formed on the sealing portion in the direction in which the electrode lead 120 protrudes can be formed at smaller intervals than the embossed pattern formed on the sealing portion in the direction in which the electrode lead 120 does not protrude. This configuration can also be applied to unidirectional battery cells configured such that the electrode lead protrudes from the sealing portion in one direction.

[0067] When viewed in a plane, the embossed pattern formed on the battery cell 100 is typically cylindrical or circular. However, there are no particular restrictions on the shape of the embossed pattern, as long as it increases the bonding area between the upper and lower housings. For example, the vertical cross-section of the embossed pattern can be polygonal, semi-circular, or semi-elliptical.

[0068] In this invention, an embossed pattern is formed to increase the adhesive area of ​​the battery casing on the sealing portion. The embossed pattern can be formed such that the embossed portion when viewed from above the sealing portion is a recessed portion when viewed from below the sealing portion, and the recessed portion when viewed from above the sealing portion is an embossed portion when viewed from below the sealing portion.

[0069] Figure 2 This is a perspective view of a battery cell according to the second embodiment.

[0070] Reference Figure 2 For ease of description, the upper housing 211 and the lower housing 212 of the pouch-type battery housing 210 constituting the battery cell 200 are shown as spaced apart from each other; however, the upper housing 211 and the lower housing 212 are in close contact with each other by thermal fusion.

[0071] The battery cell 200 is configured to have an electrode assembly receiving portion 214 formed in each of the upper housing 211 and the lower housing 212 to accommodate a bidirectional electrode assembly having electrode leads 220 protruding in opposite directions, which is more suitable for manufacturing high-capacity battery cells.

[0072] The battery cell 200 differs from the battery cell 100 in the shape of its embossed pattern. Specifically, when viewed in a plane, the embossed pattern 216 typically has a prism shape and a quadrilateral shape. Furthermore, the embossed pattern 216 extends to the end of the sealing portion. Therefore, the bonding area between the upper housing 211 and the lower housing 212 on the sealing portion 215 can be wider, thereby further improving the sealing force.

[0073] Meanwhile, the battery cell 200 is configured such that the embossed pattern formed on the sealing portion in the total width direction (W) and the embossed pattern formed on the sealing portion in the total length direction (H) are different from each other in size and spacing. Therefore, the size and spacing of the embossed pattern can be freely set to ensure the desired sealing force.

[0074] The description of battery cell 100 can be applied equally to other parts of battery cell 200, therefore, its detailed description will be omitted.

[0075] Figure 3 This is a vertical cross-sectional view of the sealing portion of a battery cell.

[0076] Reference Figure 3 Three types of embossed patterns are shown. For ease of understanding, the upper housing 211 and the lower housing 212 are shown as spaced apart from each other; however, these housings are not spaced apart but are in close contact with each other to form a seal.

[0077] Figure 3 The embossed pattern shown in (a) is configured such that the polygonal shape when viewed in a vertical section is formed with a specified size and a specified interval, such that the relief portion when viewed from above the seal is a recessed portion when viewed from below the seal, and such that the recessed portion when viewed from above the seal is a relief portion when viewed from below the seal.

[0078] Figure 3 The embossed pattern shown in (b) is configured such that when viewed in a vertical section, the polygonal shape is formed at a specified size and a specified interval, such that when viewed from above the seal, relief and intaglio are repeated alternately, and when viewed from below the seal, intaglio and relief are repeated alternately at positions corresponding to relief and intaglio.

[0079] Figure 3 The embossed pattern shown in (c) is configured such that the semicircular shape when viewed in a vertical section is formed with a specified size and a specified interval, such that the semicircular shape is embossed when viewed from above the seal, and such that the semicircular shape is recessed when viewed from below the seal.

[0080] The embossed patterns according to the present invention are not limited to Figure 3 The shapes shown are embossed, and the embossed patterns can be formed at various intervals while having various shapes.

[0081] Figure 4 This is a vertical sectional view of the sealing block according to the third embodiment.

[0082] Reference Figure 4 The sealing block according to the third embodiment is suitable for forming Figure 3The embossed pattern shown in (a). The sealing block according to the third embodiment includes: an upper sealing block 310 disposed above the sealing portion of the pouch cell; and a lower sealing block 320 disposed below the sealing portion of the pouch cell.

[0083] The upper sealing block 310 and the lower sealing block 320 are configured to engage with each other at corresponding positions on the upper and lower sealing blocks. A recessed portion 340 is formed based on the sealing surface 301, and a protruding portion 330 is formed based on the sealing surface 302.

[0084] When the sealing portion of a pouch cell is positioned between the upper sealing block 310 and the lower sealing block 320, and the sealing portion is pressurized and heated, a... Figure 3 The embossed pattern shown in (a). The protrusion 330 may protrude toward the sealing portion of the pouch cell.

[0085] Figure 5 This is a vertical sectional view of the sealing block according to the fourth embodiment.

[0086] Reference Figure 5 The sealing block according to the fourth embodiment is suitable for forming Figure 3 The embossed pattern shown in (b). The sealing block according to the fourth embodiment includes: an upper sealing block 410 disposed above the sealing portion of the pouch cell; and a lower sealing block 420 disposed below the sealing portion of the pouch cell.

[0087] The upper sealing block 410 and the lower sealing block 420 are configured to engage with each other at corresponding positions on the upper and lower sealing blocks. A recessed portion 440 is formed based on the sealing surface 401, and a protruding portion 430 is formed based on the sealing surface 401.

[0088] The protrusion 430 is configured such that the portion of the sealing portion protruding upward toward the pouch cell and the portion of the sealing portion protruding downward toward the pouch cell are alternately repeated, and the recess 440 is formed in the sealing blocks facing each other so as to engage with the protrusion 430.

[0089] In the battery cell according to the present invention, the sealing force of the sealing portion is increased. Therefore, in a battery module including the battery cell as a unit cell, the battery cell will not vent even under high internal pressure. Therefore, the safety of the battery module can be improved.

[0090] The invention will be described below with reference to examples. These examples are provided only to facilitate a better understanding of the invention and should not be construed as limiting the scope of the invention.

[0091] <Experimental Example 1>

[0092] A soft-pack battery cell is prepared and its outer periphery is sealed, thereby forming an embossed pattern on the entire sealed area.

[0093] <Experimental Example 2>

[0094] A soft-pack battery cell is prepared, and the outer periphery of the soft-pack battery cell is sealed so that the sealing part is flat.

[0095] <Measurement of Maximum Deformation and Maximum Stress 1>

[0096] The maximum deformation and maximum stress of each battery cell manufactured according to Experimental Examples 1 and 2 were measured while an internal pressure of 0.01 MPa was applied. The structural simulation results of the maximum deformation of Experimental Example 1 are shown below. Figure 6 In the simulation of the maximum deformation structure in Experiment Example 2, the results are shown in... Figure 7 In addition, the results of the maximum stress structure simulation in Experimental Example 1 are shown in... Figure 8 In the simulation of the maximum stress structure in Experiment Example 2, the results are shown in... Figure 9 middle.

[0097] Meshfree, a CAE tool developed by Midas IT Co., Ltd., is used to perform structural simulations. Three-dimensional shapes are created using SolidWorks as a CAD program, and then Meshfree is used to perform structural simulations on each shape.

[0098] Reference Figure 6 and Figure 7 The maximum deformation in Experiment 1 was approximately 0.03 mm, and the maximum deformation in Experiment 2 was approximately 0.04 mm.

[0099] Reference Figure 8 and Figure 9 The maximum stress in Experiment 1 was approximately 8.8 N / mm². 2 The maximum stress in Experiment 2 was approximately 11.3 N / mm². 2 .

[0100] Among them, Experiment 1, in which an embossed pattern is formed on the entire sealing part, shows a smaller maximum deformation than Experiment 2, in which the sealing part is flat. Therefore, it can be seen that the soft-pack battery cell with an embossed pattern formed on its entire sealing part has a more rigid structure with less deformation in response to an increase in internal pressure.

[0101] Furthermore, when the same internal pressure was applied, the maximum stress in Experimental Example 1 was measured to be less than that in Experimental Example 2. Therefore, it can be seen that the pouch cell with an embossed pattern formed on its entire sealing surface can withstand greater internal pressure.

[0102] The results above show that when an embossed pattern is formed on the entire sealed portion of a pouch cell, the sealing force increases.

[0103] <Measurement of Maximum Deformation and Maximum Stress 2>

[0104] The maximum deformation and maximum stress of each battery cell manufactured according to Experimental Examples 1 and 2 were measured while an internal pressure of 0.1 MPa was applied. The structural simulation results of the maximum deformation of Experimental Example 1 are shown below. Figure 10 In the simulation of the maximum deformation structure in Experiment Example 2, the results are shown in... Figure 11 In addition, the results of the maximum stress structure simulation in Experimental Example 1 are shown in... Figure 12 In the simulation of the maximum stress structure in Experiment Example 2, the results are shown in... Figure 13 middle.

[0105] The structural simulation was performed using the same method as in the measurement of maximum deformation and maximum stress 1.

[0106] Reference Figures 10 to 13 The maximum deformation in Experiment 1 was approximately 0.25 mm, and the maximum deformation in Experiment 2 was approximately 0.37 mm. The maximum stress in Experiment 1 was approximately 84 N / mm². 2 The maximum stress in Experiment 2 was approximately 111 N / mm². 2 .

[0107] Among them, Experiment 1, in which an embossed pattern is formed on the entire sealing part, exhibits a smaller maximum deformation and maximum stress than Experiment 2, in which the sealing part is flat.

[0108] Therefore, when an embossed pattern is formed on the entire sealed portion of a pouch cell, the pouch cell can have a more rigid structure and maintain sealing force even when the internal pressure increases significantly.

[0109] Those skilled in the art will recognize that, based on the above description, various applications and modifications can be made within the scope of this invention.

[0110] (Description of reference numerals in the attached diagram)

[0111] 100, 200: Single battery cell

[0112] 110, 210: Soft-pack battery casing

[0113] 111, 211: Upper shell

[0114] 112, 212: Lower shell

[0115] 114, 214: Electrode assembly housing

[0116] 115, 215: Sealing part

[0117] 116, 216: Embossed patterns

[0118] 120, 220: Electrode leads

[0119] 301, 401: Sealing surfaces

[0120] 310, 410: Upper sealing block

[0121] 320, 420: Lower sealing block

[0122] 330, 430: convex part

[0123] 340, 440: concave part

[0124] H: Direction of total length

[0125] W: Overall width direction

Claims

1. A battery cell comprising a pouch-type battery casing configured to house electrode assemblies internally, wherein, The soft-pack battery casing has a sealing portion around the outer periphery of the electrode assembly housing, and An embossed pattern is formed on the sealing portion in all directions. The spacing of the embossed patterns formed on the sealing portion in the direction where the electrode leads protrude is smaller than the spacing of the embossed patterns formed on the sealing portion in the direction where the electrode leads do not protrude.

2. The battery cell of claim 1, wherein, The embossed pattern is formed such that the relief when viewed from above the sealing portion is an intaglio when viewed from below the sealing portion, and the intaglio when viewed from above the sealing portion is a relief when viewed from below the sealing portion.

3. The battery cell of claim 2, wherein, The embossed pattern is formed such that the relief and the intaglio repeat alternately when viewed from above the seal.

4. The battery cell of claim 1, wherein, The embossed pattern is formed at specified dimensions and intervals.

5. The battery cell of claim 1, wherein, The vertical cross-section of the embossed pattern is polygonal, semi-circular, or semi-elliptical.

6. A sealing block for manufacturing a battery cell according to any one of claims 1 to 5, the sealing block comprising: An upper sealing block is positioned above the sealing portion of a soft-pack battery cell; as well as The lower sealing block is located below the sealing portion of the soft-pack battery cell. The upper sealing block and the lower sealing block are provided with a recess and a convex part, and the recess and the convex part are configured to engage with each other at corresponding positions of the upper sealing block and the lower sealing block.

7. The seal block of claim 6, wherein, The protrusion protrudes toward the sealing portion of the pouch cell.

8. The seal block of claim 6, wherein, The protrusion is configured such that a shape protruding upward toward the sealing portion of the pouch cell and a shape protruding downward toward the sealing portion of the pouch cell are alternately repeated.

9. A battery module comprising a battery cell as a unit cell according to any one of claims 1 to 5.

Images