Battery cell including sealing portion having embossed pattern and sealing block for manufacturing the same

Abstract

The present invention relates to a pouch-type battery case that houses an electrode assembly therein, wherein the pouch-type battery case has a sealing portion formed on an outer periphery surrounding an electrode assembly housing portion, and a battery cell in which an embossed pattern is formed on the entire sealing portion. This can improve the sealing strength of the pouch-type battery cell without adding a separate manufacturing process to the battery cell.

Description

[Technical field]

[0001] This application claims the benefit of priority to Korean Patent Application No. 2021-0138266 filed on October 18, 2021, and all contents disclosed in that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery cell including a sealing part having an embossed pattern formed thereon and a sealing block for manufacturing the same, particularly to a battery cell including a sealing part having an embossed pattern formed thereon to prevent the sealing part of a pouch-type battery cell from easily being vented and a sealing block for manufacturing the same. [Background technology]

[0003] Rechargeable lithium secondary batteries are widely used not only as energy sources for wireless mobile devices or wearable devices worn on the body, but also as energy sources for electric vehicles and hybrid electric vehicles, which are presented as alternatives to existing gasoline and diesel vehicles that cause air pollution.

[0004] Depending on the material and shape of the battery case, lithium secondary batteries can be classified into cylindrical battery cells and prismatic battery cells in which an electrode assembly is housed in a metal can, and pouch-type battery cells in which an electrode assembly is housed in a battery case made of a laminate sheet. The pouch-type battery cells have the advantages of being easily modified and having a high energy density.

[0005] In order to seal a pouch-type battery cell, a method is used in which a high-temperature sealing block is used to press the outer periphery of a battery case to form a sealing portion, but this sealing method creates a form in which venting is likely to occur when the internal pressure of the pouch-type battery cell increases.

[0006] Therefore, methods for improving the sealing performance of pouch-type battery cells have been attempted.

[0007] Patent Document 1 discloses an electricity storage device in which a sealed container body is formed from an exterior material for an electricity storage device in which a metal foil layer, a corrosion prevention treatment layer, and a sealant layer are laminated in that order, and the edges where the sealant layers are in contact with each other are heat-sealed to form a thin concave portion on the edge.

[0008] In Patent Document 1, a thin portion is formed in the heat-sealed sealed portion, so that the edges can be easily folded.

[0009] Patent Document 2 discloses a film-excased battery including an exterior film in which at least a heat-sealable resin layer and a metal thin film layer are laminated, the heat-sealable resin layer is placed on the inside to surround a battery element, and the peripheral joints are heat-sealed to seal the battery element, at least one fold is formed at the joint, and the thickness of the fold is thinner than the thickness around the fold at the joint.

[0010] Patent Document 2 forms a bend having a relatively small thickness at the joint of the exterior film, thereby preventing cracks from occurring at the bend due to the difference in elongation of the film on the inside and outside of the joint.

[0011] Patent Document 3 discloses a sealing device for performing pre-sealing in a pre-sealing and main sealing that are performed consecutively to seal a pouch-type battery case, the sealing device comprising a press that heats and presses one side and the other side of the outer periphery of a sheet member for a battery case against each other to form a pre-sealing part, and a pair of sealing blocks including a fixing part for fixing the sheet member, the press being formed with a sealing protrusion that protrudes outward, and the sealing protrusion has an outer end that is rounded on a vertical cross section.

[0012] In Patent Document 3, pre-sealing is performed prior to main sealing to reduce the occurrence of wrinkles on the outer surface of the battery cell.

[0013] However, these patent documents do not disclose any technology that can easily provide a structure that can improve the sealing strength of a pouch-type battery cell, and therefore, development of such technology is required. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] JP 2013-157286 A [Patent Document 2] Korean Patent Publication No. 2006-0064686 [Patent Document 3] Korean Patent Publication No. 2018-0028714 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention has been made to solve the above problems, and has an object to provide a battery cell including a sealing part having an embossed pattern so that a structure with improved sealing strength of the sealing part of a pouch-type battery cell can be applied in a simple manner. [Means for solving the problem]

[0016] To achieve this object, a battery cell according to the present invention includes a pouch-type battery case that houses an electrode assembly therein, and the pouch-type battery case may have a structure in which a sealing portion is formed on an outer periphery surrounding an electrode assembly housing portion, and an embossed pattern is formed over the entire sealing portion.

[0017] The embossed pattern may have a shape in which the engraved portion when viewed from above the sealing part has a shape in which the engraved portion when viewed from below, and a shape in which the engraved portion when viewed from above has a shape in which the engraved portion when viewed from below.

[0018] The embossed pattern may be formed such that, when viewed from above the sealing portion, raised and recessed patterns are alternately repeated.

[0019] The embossed patterns may be formed at regular sizes and intervals.

[0020] The interval of the embossed pattern formed on the sealing portion on a side where the electrode lead protrudes may be narrower than the interval of the embossed pattern formed on the sealing portion on a side where the electrode lead does not protrude.

[0021] The vertical cross section of the embossed pattern may be polygonal, semicircular or semi-elliptical.

[0022] The present invention provides a sealing block for manufacturing the battery cell, and more particularly, the sealing block may include an upper sealing block disposed on an upper portion of a pouch-type battery cell sealing part, and a lower sealing block disposed on a lower portion of the pouch-type battery cell sealing part, and the upper sealing block and the lower sealing block may have a structure in which grooves and protrusions are formed at corresponding positions to engage with each other.

[0023] The protrusion may protrude toward the pouch-type battery cell sealing portion.

[0024] The protrusions may be arranged in an alternating manner such that they protrude upward and downward toward the pouch-type battery cell sealing portion.

[0025] The present invention provides a battery module including the battery cell as a unit battery.

[0026] Moreover, the present invention can also be provided in the form of a combination of various means for solving the above problems. Effect of the Invention

[0027] As described above, the battery cell according to the present invention has an embossed pattern formed over the entire sealing portion, which increases the total surface area of ​​the sealing portion and therefore increases the adhesive area between the upper case and the lower case, thereby improving the sealing strength of the battery cell.

[0028] Therefore, even if the shape of the pouch-type battery cell is deformed, the sealing portion can be prevented from easily opening, and even if the internal pressure of the battery cell increases, the battery cell can be prevented from exploding.

[0029] In addition, since the embossed pattern can be formed on the sealing portion during the conventional battery cell manufacturing process, there is no need to install additional production facilities. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a battery cell according to a first embodiment. [Diagram 2] FIG. 11 is a perspective view of a battery cell according to a second embodiment. [Diagram 3] FIG. 4 is a vertical cross-sectional view of the battery cell sealing portion. [Figure 4] FIG. 10 is a vertical cross-sectional view of a sealing block according to a third embodiment. [Diagram 5] FIG. 10 is a vertical cross-sectional view of a sealing block according to a fourth embodiment. [Figure 6] FIG. 13 is a diagram showing the results of a structural simulation of the maximum deformation amount when an internal pressure of 0.01 MPa is applied to Experimental Example 1. [Figure 7] FIG. 13 is a diagram showing the results of a structural simulation of the maximum deformation amount when an internal pressure of 0.01 MPa is applied to Experimental Example 2. [Figure 8]FIG. 13 is a diagram showing the results of a structural simulation of maximum stress when an internal pressure of 0.01 MPa is applied to Experimental Example 1. [Figure 9] FIG. 13 is a diagram showing the results of a structural simulation of maximum stress when an internal pressure of 0.01 MPa is applied to Experimental Example 2. [Figure 10] FIG. 13 is a diagram showing the results of a structural simulation of the maximum deformation amount when an internal pressure of 0.1 MPa is applied to Experimental Example 1. [Figure 11] FIG. 13 is a diagram showing the results of a structural simulation of the maximum deformation amount when an internal pressure of 0.1 MPa is applied to Experimental Example 2. [Figure 12] FIG. 13 is a diagram showing the results of a structural simulation of maximum stress when an internal pressure of 0.1 MPa is applied to Experimental Example 1. [Figure 13] FIG. 13 is a diagram showing the results of a structural simulation of maximum stress when an internal pressure of 0.1 MPa is applied to Experimental Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, in which a person having ordinary skill in the art to which the present invention pertains can easily carry out the present invention. However, in describing the operation principle of the preferred embodiment of the present invention in detail, detailed description of related well-known functions or configurations will be omitted if it is determined that such detailed description may unnecessarily obscure the gist of the present invention.

[0032] In addition, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where the part is directly connected to another part, but also the case where the part is indirectly connected via another element between the two parts. In addition, when a part includes a certain component, it does not mean that the other component is excluded, but that the part may further include the other component, unless otherwise specified.

[0033] Furthermore, descriptions that limit or add specific elements are applicable to all inventions and are not limited to a particular invention unless otherwise specified.

[0034] Furthermore, throughout the description of the present invention and the claims, the singular includes the plural unless otherwise stated.

[0035] In addition, throughout the description of the present invention and the claims, unless otherwise specified, "or" includes "and." Therefore, "including A or B" means three cases: including A, including B, or including both A and B.

[0036] The invention will now be explained with reference to the drawings and in conjunction with detailed embodiments.

[0037] FIG. 1 is a perspective view of a battery cell according to a first embodiment.

[0038] The battery cell 100 is a pouch-type battery cell including a pouch-type battery case 110 made of a laminate sheet. The pouch-type battery case 110 includes an upper case 111 in which an electrode assembly receiving portion 114 for receiving an electrode assembly is formed, and a lower case 112 located below the upper case 111.

[0039] The battery case may be made of a laminate sheet in which an outer resin layer, an air- and moisture-blocking metal layer, and a heat-sealable inner resin layer are laminated.

[0040] The outer resin layer must have excellent resistance to the external environment, and therefore must have a tensile strength and weather resistance equal to or greater than a certain value. For example, the outer resin layer may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or oriented nylon.

[0041] The metal layer may be made of aluminum (Al) or an aluminum alloy so as to improve the strength of the battery case in addition to preventing the inflow of foreign matter such as gas and moisture or the leakage of the electrolyte.

[0042] The inner resin layer may be made of a polymer resin that has heat scalability, low hygroscopicity to the electrolyte, and is not expanded or eroded by the electrolyte, for example, a non-oriented polypropylene film (CPP).

[0043] The upper case 111 and the lower case 112 contact each other at the outer periphery surrounding the electrode assembly housing portion, and when the outer periphery is heated and pressed, the internal resin layer of the upper case and the internal resin layer of the lower case melt and bond to form a sealing portion 115.

[0044] The battery cell 100 has an upper case 111 and a lower case 112 connected to each other, and a sealing portion 115 is formed on the outer periphery of three sides excluding the bent portion.

[0045] That is, the sealing portions formed on the outer peripheries of the three sides are sealing portions in the width direction W at both ends of the battery cell and in the length direction H of the battery cell, and the embossed patterns 116 are formed on all the sealing portions.

[0046] In order to equalize the sealing force of all the sealing parts, the embossed patterns 116 may be formed at a uniform size and intervals in all the sealing parts.

[0047] Alternatively, since the internal pressure increases most significantly at the center of the sealing portion in the overall length direction H, the intervals of the embossed patterns may be narrower at the center of the overall length direction H.

[0048] Alternatively, the electrode lead 120 extends from the sealing portion in the full-width direction W to the outside of the battery case, and the sealing force is relatively reduced at the portion where the electrode lead 120 protrudes. Therefore, in order to prevent the sealing force from being reduced at the portion where the electrode lead 120 protrudes, the interval of the embossed pattern formed in the sealing portion on the side where the electrode lead 120 protrudes may be narrower than the interval of the embossed pattern formed in the sealing portion on the side where the electrode lead 120 does not protrude. This configuration is also applicable to a unidirectional battery cell in which the electrode lead protrudes from the sealing portion in one direction.

[0049] The embossed pattern formed on the battery cell 100 has an overall cylindrical shape and a circular shape when viewed from above. However, the shape of the embossed pattern is not particularly limited as long as it increases the bonding surface area between the upper case and the lower case. For example, the vertical cross section of the embossed pattern may be polygonal, semicircular, or semi-elliptical.

[0050] In the present invention, since the embossed pattern is formed for the purpose of increasing the adhesive area of ​​the battery case at the sealing part, the embossed pattern may be formed such that a portion that is embossed when viewed from above the sealing part becomes an engraved form when viewed from below, and a portion that is engraved when viewed from above becomes an embossed form when viewed from below.

[0051] FIG. 2 is a perspective view of a battery cell according to the second embodiment.

[0052] Referring to FIG. 2, in the battery cell 200, the upper case 211 and the lower case 212 constituting the pouch-type battery case 210 are shown separated from each other for convenience of explanation, but the upper case 211 and the lower case 212 are in intimate contact with each other by heat fusion.

[0053] The battery cell 200 has a configuration in which a bidirectional electrode assembly in which electrode leads 220 protrude in opposite directions is housed, and has a structure in which an electrode assembly housing portion 214 is formed in each of the upper case 211 and the lower case 212, which may be a configuration more suitable for manufacturing a high-capacity battery cell.

[0054] The battery cell 200 is different from the battery cell 100 in the shape of the embossed pattern. Specifically, the embossed pattern 216 has an overall rectangular prism shape and a rectangular shape on a plane. In addition, the embossed pattern 216 is formed up to the end of the sealing part. Therefore, the adhesive surface between the upper case 211 and the lower case 212 in the sealing part 215 can be made wider, thereby improving the sealing force.

[0055] Meanwhile, since the battery cell 200 has a shape in which the embossed pattern formed on the sealing portion in the width direction W and the embossed pattern formed on the sealing portion in the length direction H have different sizes and intervals, the size and intervals of the embossed pattern can be freely set so as to secure a desired level of sealing force.

[0056] In addition, the description of the battery cell 200 can be similarly applied to the description of the battery cell 100, so detailed description thereof will be omitted.

[0057] FIG. 3 is a vertical cross-sectional view of the battery cell sealing portion.

[0058] Referring to FIG. 3, three types of embossed patterns are shown, and for ease of understanding, the upper case 211 and the lower case 212 are shown as being separated from each other, but they form a sealing portion in a state of being in close contact with each other without any separation between them.

[0059] The embossed pattern in FIG. 3(a) is formed in the shape of polygons of a certain size and interval on a vertical cross section, and the embossed portion when viewed from above the sealing part appears as a carved portion when viewed from below, and the carved portion when viewed from above the sealing part appears as a embossed portion when viewed from below.

[0060] The embossing pattern in FIG. 3(b) is formed in a polygonal shape of a certain size and interval on a vertical cross section, and when viewed from above the sealing part, it has a shape in which carved and engraved patterns are alternately repeated, and when viewed from below the sealing part at the positions corresponding to the carved and engraved patterns, it has a shape in which carved and carved patterns are alternately repeated, respectively.

[0061] The embossed pattern in FIG. 3(c) is formed in a semicircular shape at a certain size and interval on a vertical cross section, and has a carved shape when viewed from above the sealing part, and has a carved shape when viewed from below.

[0062] The embossed pattern according to the present invention is not limited to the shape shown in FIG. 3, but may be formed in various shapes and intervals.

[0063] FIG. 4 is a vertical cross-sectional view of a sealing block according to a third embodiment.

[0064] 4, the sealing block according to the third embodiment has a shape suitable for forming the embossed pattern of (a) of Fig. 3. The sealing block according to the third embodiment includes an upper sealing block 310 disposed at the upper part of the pouch-type battery cell sealing part, and a lower sealing block 320 disposed at the lower part of the pouch-type battery cell sealing part.

[0065] The upper sealing block 310 and the lower sealing block 320 are formed to have a structure in which they are engaged with each other at corresponding positions. That is, a groove 340 that is recessed based on the sealing surface 301, and a protrusion 330 that protrudes based on the sealing surface 301 are formed.

[0066] Therefore, when the sealing portion of the pouch-type battery cell is disposed between the upper sealing block 310 and the lower sealing block 320 and pressed and heated, an embossed pattern as shown in Fig. 3(a) is formed. Here, the protrusion 330 may have a shape that protrudes toward the sealing portion of the pouch-type battery cell.

[0067] FIG. 5 is a vertical sectional view of a sealing block according to a fourth embodiment.

[0068] 5, the sealing block according to the fourth embodiment has a shape suitable for forming the embossed pattern of FIG 3(b). The sealing block according to the fourth embodiment includes an upper sealing block 410 disposed on the upper part of the pouch-type battery cell sealing part, and a lower sealing block 420 disposed on the lower part of the pouch-type battery cell sealing part.

[0069] The upper sealing block 410 and the lower sealing block 420 are formed with a structure that engages with each other at corresponding positions. That is, a groove portion 440 that is recessed based on the sealing surface 401, and a protrusion portion 430 that protrudes based on the sealing surface 401 are formed.

[0070] The protrusions 430 are arranged in an alternating pattern with shapes that protrude upward and shapes that protrude downward toward the sealing portion of the pouch-type battery cell, and a groove 440 is formed in the opposing sealing block to engage with the protrusions 430.

[0071] Since the battery cell according to the present invention has an improved sealing force of a sealing portion, in a battery module including the battery cell as a unit battery, the battery cell cannot be vented even under higher internal pressure, thereby improving the safety of the battery module.

[0072] The present invention will be described below with reference to examples, which are provided for easier understanding of the present invention and are not intended to limit the scope of the present invention.

[0073] <Experimental Example 1> A pouch-type battery cell was prepared and sealed such that an embossed pattern was formed around the entire outer perimeter sealing portion.

[0074] <Experimental Example 2> A pouch-type battery cell was prepared and sealed with the outer peripheral sealing portion in a flat configuration.

[0075] <Maximum deformation and maximum stress measurement 1> An internal pressure of 0.01 MPa was applied to the battery cells manufactured in Experimental Examples 1 and 2 to measure the maximum deformation and maximum stress. The structural simulation result of the maximum deformation in Experimental Example 1 is shown in Fig. 6, and the structural simulation result of the maximum deformation in Experimental Example 2 is shown in Fig. 7. Furthermore, the structural simulation result of the maximum stress in Experimental Example 1 is shown in Fig. 8, and the structural simulation result of the maximum stress in Experimental Example 2 is shown in Fig. 9.

[0076] The structure simulation was carried out using a CAE tool called Meshfree by Midas. After creating 3D shapes using the Solidworks program as a CAD program, the structure simulation was carried out for each shape using Meshfree.

[0077] 6 and 7, the maximum deformation amount in Experimental Example 1 is about 0.03 mm, and the maximum deformation amount in Experimental Example 2 is about 0.04 mm.

[0078] 8 and 9, the maximum stress in Experimental Example 1 was about 8.8 N / mm 2 The maximum stress in Experimental Example 2 was approximately 11.3 N / mm 2 It is.

[0079] As described above, experimental example 1, in which an embossed pattern was formed over the entire sealing portion, showed a smaller maximum deformation amount than experimental example 2, in which a flat sealing portion was formed. This shows that the pouch-type battery cell in which an embossed pattern was formed over the entire sealing portion has a stiffer structure with less deformation due to increased internal pressure.

[0080] In addition, when the same pressure resistance was applied, the maximum stress was measured to be smaller in Experimental Example 1 than in Experimental Example 2. Therefore, it can be confirmed that the pouch-type battery cell structure in which the embossed pattern is formed over the entire sealing part can withstand a larger increase in internal pressure.

[0081] These results show that the sealing strength is improved when an embossed pattern is formed over the entire sealing portion of a pouch-type battery cell.

[0082] <Maximum deformation and maximum stress measurement 2> An internal pressure of 0.1 MPa was applied to the battery cells manufactured in Experimental Examples 1 and 2 to measure the maximum deformation and maximum stress, and the structural simulation result of the maximum deformation in Experimental Example 1 is shown in Fig. 10, and the structural simulation result of the maximum deformation in Experimental Example 2 is shown in Fig. 11. Furthermore, the structural simulation result of the maximum stress in Experimental Example 1 is shown in Fig. 12, and the structural simulation result of the maximum stress in Experimental Example 2 is shown in Fig. 13.

[0083] The structural simulation was performed in the same manner as that used in the maximum deformation and maximum stress measurement 1.

[0084] 10 to 13, the maximum deformation amount in Experimental Example 1 is about 0.25 mm, and the maximum deformation amount in Experimental Example 2 is about 0.37 mm. The maximum stress in Experimental Example 1 is about 84 N / mm 2 The maximum stress in Experimental Example 2 was approximately 111 N / mm 2 It is.

[0085] Thus, Example 1, in which an embossed pattern was formed over the entire sealing portion, showed a smaller maximum deformation amount and a smaller maximum stress than Example 2, in which a flat sealing portion was formed.

[0086] Therefore, when an embossed pattern is formed over the entire sealing portion of a pouch-type battery cell, not only does it have a stronger structural form, but it can also maintain its sealing force even when the internal pressure increases more.

[0087] Those skilled in the art will appreciate that various applications and modifications within the scope of the present invention will be possible based on the above content. [Explanation of symbols]

[0088] 100, 200 battery cells 110, 210 Pouch-type battery case 111, 211 Upper case 112, 212 Lower case 114, 214 Electrode assembly storage section 115, 215 Sealing part 116, 216 embossed patterns 120, 220 Electrode Lead 301, 401 sealing surface 310, 410 Upper sealing block 320, 420 Lower sealing block 330, 430 protrusion 340, 440 Groove H Full length direction W Full width direction

Claims

1. The battery includes a pouch-type battery case that houses the electrode assembly therein, The pouch-type battery case has a sealing portion formed on an outer periphery surrounding an electrode assembly receiving portion, The entire sealing part has an embossed pattern on the remaining part except for the electrode lead. A battery cell, in which an interval between the embossed patterns formed on the sealing portion on the side where the electrode lead protrudes is narrower than an interval between the embossed patterns formed on the sealing portion on the side where the electrode lead does not protrude, to prevent a reduction in sealing force at the sealing portion on the side where the electrode lead protrudes compared to a sealing portion on the side where the electrode lead does not protrude.

2. 2. The battery cell according to claim 1, wherein the embossed pattern has a recessed shape when viewed from below the sealing portion and a recessed shape when viewed from above the sealing portion.

3. The battery cell according to claim 2 , wherein the embossed pattern is formed such that raised and recessed patterns are alternately repeated when viewed from above the sealing portion.

4. The battery cell according to claim 1 , wherein the embossed patterns are formed at regular sizes and intervals.

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

6. A sealing block for manufacturing a battery cell according to any one of claims 1 to 5, The pouch-type battery cell sealing unit includes an upper sealing block disposed on an upper portion of the pouch-type battery cell sealing unit, and a lower sealing block disposed on a lower portion of the pouch-type battery cell sealing unit, The upper sealing block and the lower sealing block have grooves and protrusions formed at their corresponding positions, except for portions facing the electrode leads, so as to engage with each other.

7. The sealing block according to claim 6 , wherein the protrusion protrudes toward the pouch-type battery cell sealing portion.

8. The sealing block of claim 6 , wherein the protrusions are arranged in an alternating pattern of upwardly protruding portions and downwardly protruding portions toward the pouch-type battery cell sealing portion.

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

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