Method for manufacturing soft-pack type battery cell and soft-pack type battery cell manufactured thereby

Abstract

The present invention relates to a method for manufacturing a soft-pack type battery cell, comprising: housing an electrode assembly in a battery case made of a laminate; performing a primary sealing on the outer edge of the battery case; and performing a secondary sealing on at least a portion of the primary-sealed outer edge, wherein the sealing force of the sealing portion formed after the primary and secondary sealing is low, thereby guiding the venting position and venting time of the soft-pack type battery cell.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 2020-0152143, filed on November 13, 2020, and Korean Patent Application No. 2021-0155191, filed on November 11, 2021, the disclosures of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for manufacturing a soft-pack battery cell including a secondary seal, and the soft-pack battery cell manufactured thereby. More specifically, the present invention relates to a method for manufacturing a soft-pack battery cell, and the soft-pack battery cell manufactured thereby, which can adjust the sealing strength of the soft-pack battery cell to allow gas to be discharged from the soft-pack battery cell before the soft-pack battery cell explodes when the soft-pack battery cell expands due to an increase in its internal pressure, thereby ensuring the safety of the soft-pack battery cell. Background Art

[0003] Rechargeable lithium secondary batteries have been widely used as energy sources for wireless mobile devices and wearable devices, and have also been used as energy sources for electric vehicles.

[0004] Lithium secondary batteries may be classified into pouch-type secondary batteries made of a laminate, cylindrical secondary batteries made of a metal can, or square secondary batteries made of a metal can based on the kind or shape of an exterior member.

[0005] Since pouch-type secondary batteries can be manufactured in various sizes, are lightweight, and have high energy density, they are attracting attention as power sources for electric vehicles that require high-output, high-capacity energy.

[0006] In lithium secondary batteries, the temperature of electrode assemblies, electrical connection members, etc. may increase due to the heat generated during charging and discharging. At high temperatures, the electrolyte in the lithium secondary battery decomposes and generates gas, which causes the lithium secondary battery to swell. For battery packs configured so that multiple battery cells are fixed in a shell, the swollen battery cells are further pressurized in the limited shell, thereby increasing the risk of fire and explosion. The above problems can be prevented if the gas is discharged from the soft-pack type battery cell before the soft-pack type battery cell swells and explodes.

[0007] Soft-pack battery cells use a laminate with an internal adhesive layer as the battery case, and the outer edges of the battery case are sealed by heat fusion. When the laminate is heated and pressurized, the adhesive layer melts, thereby bonding the sealing portion of the upper and lower cases to each other. At this point, resin clumps of the internal adhesive layer form in the bonded portion, known as polymer balls or polymer balls.

[0008] When the size of the polymer ball is large, the sealing force of the battery case is high, so venting does not occur even when the internal pressure is high. A method is needed to adjust the sealing force as needed so that venting occurs under high pressure or explosion does not occur.

[0009] Patent Document 1 explains that when sealing a battery case made of a laminated film, it is possible to form a seal portion having different patterns depending on the heating temperature, pressurization pressure, and pressurization time of the sealing tool. Furthermore, the document explains that if at least one of the upper and lower sides of the end of the resin accumulation portion has a cross-sectional shape that tapers toward the resin accumulation portion, the breaking strength is reduced.

[0010] Patent document 2 relates to a method for manufacturing a polymer lithium secondary battery, wherein a sealing portion is formed on the edge of a casing film by heat fusion, at least a portion of the sealing portion serves as a safety valve, and the heat-melting temperature of the sealing area serving as the safety valve is lower than the heat-melting temperature of the sealing area not serving as the safety valve.

[0011] In Patent Document 2, a portion with low sealing force is formed at a portion of the outer edge of the battery case, thereby making it possible to prevent rupture of the secondary battery in advance.

[0012] Patent document 3 discloses a lithium ion polymer battery, which is configured so that a rupture side formed by ultrasonic fusion and ruptured when the internal pressure of the battery increases is provided on one side of a soft-pack outer shell member, and Patent document 4 discloses a soft-pack secondary battery, which is configured so that the sealing strength of one of a plurality of sealing surfaces formed at the outer edge of a soft-pack battery cell is low, and also discloses a method of controlling pressure, heat and temperature by adjusting process conditions or a method of adding a material capable of improving the sealing strength to other sealing surfaces other than a gas discharge portion as a method of forming the sealing strength differently.

[0013] Patent Document 5 uses a method that applies heat and pressure to a primary heat seal using a sealing tool, and heats an area partially overlapping the primary seal area to fuse the area through secondary sealing (i.e., high-frequency sealing). Patent Document 5 is characterized by reducing the thickness of the housing through two-stage sealing, thereby reducing the overall seal width.

[0014] Patent Document 6 discloses a method for performing a secondary seal on a portion of the outer edge of a primary-sealed pouch-type battery case, wherein each of the primary and secondary seals is heat-sealed using a sealing tool. However, Patent Document 6 specifies that the preferred temperature range for the primary seal is approximately 180°C, while the preferred temperature range for the secondary seal is 15°C to 20°C, i.e., room temperature.

[0015] The reason why the temperature range of the secondary sealing is very low in Patent Document 6 is that the sealing region melted by the primary sealing needs to be cooled and solidified in order to improve the sealing strength.

[0016] As described above, various methods of guiding the venting of a battery case in a pouch-type battery cell have been proposed; however, a method of reducing the size of polymer balls that determine the sealing strength has not been specifically proposed.

[0017] Japanese Patent Publication No. 5463212 (January 24, 2014) (“Patent Document 1”)

[0018] Japanese Patent Application Publication No. 2000-100399 (April 7, 2000) ("Patent Document 2")

[0019] Korean Patent Publication No. 0889765 (March 13, 2009) (“Patent Document 3”)

[0020] Korean Patent Publication No. 1520152 (May 7, 2015) (“Patent Document 4”)

[0021] Korean Patent Publication No. 1883527 (July 24, 2018) (“Patent Document 5”)

[0022] Korean Patent Publication No. 1471765 (December 4, 2014) (“Patent Document 6”) Summary of the Invention

[0023] Technical issues

[0024] The present invention is proposed in view of the above problems, and an object of the present invention is to provide a method for manufacturing a soft-pack type battery cell capable of adjusting the sealing strength of the sealing portion of the soft-pack type battery cell to guide the exhaust of the soft-pack type battery cell in a desired direction, and a soft-pack type battery cell manufactured thereby.

[0025] Technical Solution

[0026] The method for manufacturing a soft-pack battery cell according to the present invention for achieving the above-mentioned purpose includes: housing an electrode assembly in a battery case made of a laminate; performing a primary sealing on the outer edge of the battery case; and performing a secondary sealing on at least a portion of the primary-sealed outer edge, wherein the primary and secondary sealing are performed by pressurizing the upper and lower cases using a high-temperature sealing tool, and the sealing temperature of the primary sealing is equal to or higher than the sealing temperature of the secondary sealing. Preferably, the sealing temperature of the primary sealing can be higher than the sealing temperature of the secondary sealing.

[0027] In the method for manufacturing a soft-pack type battery cell according to the present invention, the primary sealing temperature and the secondary sealing temperature may be greater than 130°C to 250°C and 50°C to less than 200°C, respectively, preferably 140°C to 220°C and 75°C to less than 160°C, more preferably 160°C to 200°C and 100°C to less than 130°C.

[0028] In the method of manufacturing the pouch-type battery cell according to the present invention, the primary sealing may be a process of sealing the entire outer edge of the battery case to thereby seal the battery case.

[0029] In the method for manufacturing a pouch-type battery cell according to the present invention, the secondary seal may seal at least one of at least a portion of the major axis seal portion, at least a portion of the minor axis seal portion, and a portion of a corner portion of the battery case.

[0030] In the method for manufacturing a pouch-type battery cell according to the present invention, the secondary seal may be a middle portion of a long-axis seal portion that seals the battery case.

[0031] In the method of manufacturing the pouch-type battery cell according to the present invention, the sealing time of the secondary sealing may be longer than the sealing time of the primary sealing.

[0032] In the method for manufacturing a pouch-type battery cell according to the present invention, the sealing time of the secondary sealing may be 5 seconds or longer.

[0033] In the method for manufacturing the pouch-type battery cell according to the present invention, the pressure of the secondary sealing may be higher than the pressure of the primary sealing.

[0034] Furthermore, the present invention provides a pouch-type battery cell manufactured by the method for manufacturing the pouch-type battery cell.

[0035] In a battery cell according to the present invention, a soft-pack type battery cell may include a battery case made of a laminate including an outer resin layer, a metal layer, and an inner adhesive layer, and the thickness of the polymer balls in the sealing portion formed after primary sealing and secondary sealing may be 60% to 70% of the thickness of the polymer balls in the sealing portion formed after only primary sealing.

[0036] Here, the thickness of the polymer ball refers to the thickness of the thickest portion of the portion forming the polymer ball when observing a cross section of the pouch-type battery cell.

[0037] In addition, the thickness of the polymer balls in the primary sealing portion may be 220 μm to 300 μm, and the thickness of the polymer balls in the secondary sealing portion may be 130 μm to 170 μm.

[0038] A soft-pack type battery cell may include a battery case made of a laminate, which includes an outer resin layer, a metal layer and an inner adhesive layer, and at a connection portion where a sealing portion formed after primary sealing and secondary sealing is connected to an electrode assembly accommodating portion, a thickness of the inner adhesive layer in the sealing portion formed after primary sealing and secondary sealing may be less than 200% of a thickness of an inner adhesive layer outside the sealing portion.

[0039] In the battery cell according to the present invention, the sealing force of the sealing portion formed after primary sealing and secondary sealing are performed may be smaller than the sealing force of the sealing portion formed after only primary sealing is performed.

[0040] Furthermore, the present invention can provide all possible combinations of the above-mentioned solutions.

[0041] Beneficial effects

[0042] As apparent from the above description, in the present invention, a portion of the sealing portion of a soft-pack battery cell is doubly sealed to adjust the sealing force of the doubly sealed portion. Furthermore, in the present invention, a portion of the sealing portion of a soft-pack battery cell is doubly sealed to reduce the size of the aggregate balls formed in the doubly sealed portion. The reduced size of the aggregate balls reduces the sealing force, thereby enabling control of the venting position and timing of the soft-pack battery cell.

[0043] Since the self-exhaust can be guided before the pouch-type battery cell explodes, as described above, the pouch-type battery cell can be prevented from being ignited in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The manufacturing process of the soft-pack type battery cell according to the present invention is shown.

[0045] Figure 2 It is a partial vertical cross-sectional view of the soft-pack battery case.

[0046] Figure 3 This is a cross-sectional photo of the battery case after primary sealing is completed.

[0047] Figure 4 This is a cross-sectional photo of the battery case after secondary sealing is completed.

[0048] Figure 5 Shown are the lengths of the temporary connection areas formed by the polymeric balls after primary sealing (a) and secondary sealing (b).

[0049] Figure 6 The thickness of the polymeric spheres after primary sealing (a) and secondary sealing (b) is shown.

[0050] Figure 7 The sealing force measurement curve of Sample 1 is shown.

[0051] Figure 8 The sealing force measurement curve of Sample 2 is shown.

[0052] Figure 9 The sealing force measurement curve of Sample 3 is shown. DETAILED DESCRIPTION

[0053] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, when describing the working principles of the preferred embodiments of the present invention in detail, when a detailed description of known functions and configurations included in this document may obscure the subject matter of the present invention, the detailed description will be omitted.

[0054] In addition, the same reference numerals will be used throughout the drawings to refer to components that perform similar functions or operations. In the specification, when it is mentioned that a component is connected to another component, it can be said that the component can be directly connected to the other component or indirectly connected to the other component through another component. In addition, unless otherwise specified, the inclusion of a certain element does not mean that other elements are excluded, but rather that these elements may be further included.

[0055] Furthermore, the description of implementing elements by limitation or addition can be applied to all inventions unless otherwise specifically limited, and does not limit a specific invention.

[0056] Furthermore, in the description and claims of the present invention, unless otherwise stated, the singular form is intended to include the plural form.

[0057] In addition, in the description and claims of the present invention, unless otherwise specified, "or" includes "and". Therefore, "including A or B" refers to three cases, namely, the case including A, the case including B, and the case including A and B.

[0058] The present invention relates to a method for manufacturing a pouch-type battery cell in which the outer edge of the battery case is sealed by applying heat and pressure. Primary and secondary sealing are performed to ensure the force required to seal the outer edge of the battery case and to guide exhaust gas at specific portions of the outer edge. Furthermore, the present invention enables adjustment of the sealing force through the primary and secondary sealing processes.

[0059] It is well known that when sealing soft-pack batteries, the sealing force increases with the number of sealing cycles. The present invention is based on the fact that the sealing force can be controlled by controlling the size of the polymer balls and can be reduced by secondary sealing.

[0060] That is, a primary seal portion with high sealing force can be formed at the entire outer edge of the battery case by primary sealing, and a portion of the primary seal portion can be deformed by secondary sealing to form a secondary seal portion with low sealing force. In addition, in the present invention, a structure can be obtained in which the sealing force is increased by changing the secondary sealing conditions.

[0061] Specifically, the method for manufacturing a soft-pack type battery cell according to the present invention includes: accommodating an electrode assembly in a battery case made of a laminate, primarily sealing an outer edge of the battery case, and secondarily sealing at least a portion of the primarily sealed outer edge.

[0062] The laminate may be configured to have a laminate structure in which an outer resin layer, an air and moisture barrier metal layer, and a hot-melt inner adhesive layer are stacked, and may further include adhesive layers between the outer resin layer and the metal layer and between the metal layer and the inner adhesive layer.

[0063] The outer resin layer needs to exhibit excellent resistance to the external environment and therefore needs to exceed predetermined tensile strength and weather resistance. In this regard, the polymer resin constituting the outer resin layer may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or oriented nylon, which exhibit excellent tensile strength and weather resistance.

[0064] The metal layer may be made of aluminum (Al) or an aluminum alloy to exhibit a function of improving the strength of the battery case in addition to the function of preventing the introduction of foreign matter (such as gas and moisture) or leakage of the electrolyte. Examples of aluminum alloys may include alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, and 3105. These materials may be used alone or in combination of two or more thereof.

[0065] A polymer resin that exhibits heat-melting properties, has low hygroscopicity to the electrolyte, and does not swell or is not corroded by the electrolyte may be used as the inner adhesive layer. Specifically, the inner adhesive layer may be made of cast polypropylene (CPP).

[0066] Figure 1 The manufacturing process of the soft-pack type battery cell according to the present invention is shown.

[0067] Reference Figure 1 The electrode assembly 110 is housed in the battery case 101, and a primary sealing tool 200 is used to seal the entire outer edge of the battery case 101 to form a primary sealing portion 220. Subsequently, a secondary sealing tool 300 is used to perform secondary sealing on a portion of the primary sealing portion 220 to form a secondary sealing portion 320.

[0068] Primary sealing is the process of sealing the battery casing to prevent material from moving between the exterior and interior of the battery casing, wherein the entire outer edge of the battery casing is sealed.

[0069] The pouch-type battery case may be composed of a first case having an electrode assembly receiving portion formed therein and a second case coupled to an upper portion of the first case. Alternatively, the electrode assembly receiving portion may be formed in both the first case and the second case.

[0070] The first housing and the second housing may be separated from each other, or may be bent in a state in which corresponding ends thereof are coupled to each other so that the first housing and the second housing are sealed.

[0071] exist Figure 1 In the battery case, an electrode assembly accommodating portion is formed in each of the first shell 101 and the second shell 102, and the first shell 101 and the second shell 102 are bent in a state of being combined with each other, wherein a sealing portion may not be formed at the bent portion, or a sealing portion narrower than the rest of the outer edge may be formed at the bent portion.

[0072] Figure 1 The primary sealing tool 200 shown in FIG. 1 is configured to have a quadrangular ring shape to seal the entire outer edge of the battery case. However, the present invention is not limited thereto. Figure 1 The primary and secondary sealing tools are shown as being disposed only above the sealing portion of the battery case, and the primary and secondary lower sealing tools, which are disposed below the sealing portion of the battery case to overlap with the primary and secondary sealing tools, are omitted. Each of the primary and secondary lower sealing tools may have a size and shape corresponding to that of a corresponding one of the primary and secondary sealing tools, or may be formed in the shape of a support member larger than that of the corresponding one of the primary and secondary sealing tools.

[0073] Furthermore, the primary sealing tool and the primary lower sealing tool may be disposed in a straight line above and below only one of the four outer edge sealing portions of the battery case so as to seal only the sealing portion.

[0074] In the primary and secondary sealing, high temperature sealing tools are used to pressurize the upper and lower shells. The sealing temperature of the primary seal is equal to or higher than the sealing temperature of the secondary seal.

[0075] Specifically, the primary sealing temperature and the secondary sealing temperature may be greater than 130 to 250°C and 50 to less than 200°C, preferably 140 to 220°C and 75 to less than 160°C, more preferably 160 to 200°C and 100 to less than 130°C, respectively.

[0076] Alternatively, the primary sealing temperature may be 160°C to 200°C, and the secondary sealing temperature may be 100°C to 200°C, preferably 100°C to 140°C.

[0077] In the primary sealing step, the inner adhesive layers of the first shell and the second shell are melted and bonded to each other. The primary sealing temperature may be equal to or higher than the melting temperature of the adhesive layer.

[0078] When the outer edge of the battery case is sealed at high temperature, as described above, polymer balls, which are blocks of polymer resin constituting the inner adhesive layer, are formed at a portion of the interface between the first and second cases connected to the electrode assembly receiving part.

[0079] As the size of the polymer ball increases, the exhaust pressure of the battery case increases. Therefore, in the present invention, a sealing portion having a high bonding force is formed at the entire outer edge of the battery case by high-temperature primary sealing.

[0080] At the same time, the present invention can arbitrarily form a portion with low sealing force at a portion of the seal as a technique for guiding the venting position and timing of the pouch-type battery cells. Conversely, even when a high sealing force is required, it can be controlled through the structure according to the present invention.

[0081] Specifically, low-temperature secondary sealing is performed on a portion of the primary sealing portion that has already been sealed, where venting is desired to occur in order to form a vent portion having a low sealing force.

[0082] In the secondary sealing step, the size of the polymerized balls is reduced, thereby reducing the sealing force of the sealing portion where the secondary sealing has been performed.

[0083] Generally, outgassing is more likely to occur at the long-axis seals of pouch-type battery cells than at the short-axis seals. If outgassing occurs at any of the four seals in the battery case, secondary sealing can be performed to further seal at least one of the long-axis seals in the battery case.

[0084] When the vent is narrow, the pressure is more concentrated, allowing venting to occur quickly. In addition, when the secondary seal is performed in the middle of the long axis seal of the battery case, the internal pressure of the battery cell is concentrated in the middle of the long axis seal, which may cause venting to occur most quickly.

[0085] In a specific example, the secondary sealing time may be longer than the primary sealing time. Specifically, the secondary sealing time may be 5 seconds or more, more specifically 8 seconds or more. In addition, the primary sealing time may be 4 seconds or less, specifically 3 seconds or less.

[0086] As described above, since the primary seal is pressurized at high temperature, the internal adhesive layer is melted to a degree that fully ensures sealing even with a short pressurization time. In contrast, since the secondary seal is pressurized at low temperature, it is necessary to ensure that the polymer balls have time to melt and spread widely. To achieve this, a longer pressurization time is required. The portion of the polymer balls that will form the temporary connection area is widely distributed along the shell through the secondary seal. However, due to the relatively low temperature, no temporary connection area is formed, and only the thickness of the polymer balls is reduced, thereby reducing the sealing force.

[0087] In another specific example, the pressure of the secondary seal can be higher than that of the primary seal. That is, in the secondary seal pressurized at low temperature, a higher pressure is used than in the primary seal to reduce the size of the polymerized ball.

[0088] In order to explain the changes of the sealing portion according to the primary seal and the secondary seal according to the present invention, Figure 2 A partial vertical cross-sectional view of the soft pack battery case is shown in FIG.

[0089] Reference Figure 2 The soft-pack type battery case is composed of a first case 101 and a second case 102 manufactured by molding a laminate, which is configured to have a structure in which outer resin layers 101a and 102a, metal layers 101b and 102b, and inner adhesive layers 101c and 102c are stacked in sequence.

[0090] Figure 2 (a) shows the soft pack type battery case before sealing, Figure 2 (b) shows the state where the soft pack type battery case is sealed once, Figure 2 (c) shows a state where the pouch-type battery case is secondarily sealed. Figure 2 (c) shows the case where the sealing force is reduced by secondary sealing.

[0091] Specifically, in Figure 2 In the primary sealing portion 220 shown in (b), the internal adhesive layer 101c of the first shell 101 and the internal adhesive layer 102c of the second shell 102 are melted and bonded to each other to become one body. In addition, since the internal adhesive layers 101c and 102c are pressurized by the primary sealing tool, Figure 2 The sum of the thicknesses of the internal adhesive layers 101c and 102c shown in (b) is less than Figure 2 The sum of the thicknesses of the internal adhesive layers shown in (a).

[0092] That is, the inner adhesive layer in the primary sealing part 220 is pressurized by the primary sealing tool, whereby the inner adhesive layer is pushed in a direction toward the electrode assembly receiving part 105 to form the aggregate ball 108 .

[0093] Furthermore, the secondary sealing is a process of pressurizing the primary sealing portion 220 at a low temperature to form the secondary sealing portion 320 , and the size of the polymerized balls 108 in the secondary sealing portion 320 is significantly reduced.

[0094] Therefore, the sealing force of the secondary sealing portion 320 is reduced.

[0095] The reason for this is that pressure is applied in a state where the inner adhesive layer and the polymer balls are heated by the temperature of the secondary sealing tool, so that the polymer balls are widely spread.

[0096] The soft-pack type battery cell manufactured by the manufacturing method of the soft-pack type battery cell includes a primary sealing portion formed by only a primary seal and a secondary sealing portion formed by the primary seal and the secondary seal, wherein the thickness of the internal adhesive layer at the connection portion where the secondary seal portion is connected to the electrode assembly accommodating portion in the secondary seal portion can be less than 200% of the thickness of one internal adhesive layer outside the sealing portion.

[0097] In addition, since the sealing strength of the secondary sealing portion is lower than that of the primary sealing portion, when the internal pressure of the pouch-type battery cell increases, venting may first occur in the secondary sealing portion.

[0098] Hereinafter, the present invention will be described with reference to the following examples. These examples are provided only to facilitate understanding of the present invention and should not be construed as limiting the scope of the present invention.

[0099] <Comparative Example>

[0100] Three battery cases were prepared, Sample 1, Sample 2, and Sample 3, each of which was made of a laminate comprising a modified polyolefin layer (a hot-melt resin) as an inner adhesive layer, an aluminum layer as a metal layer, and polyethylene terephthalate as an outer resin layer. The sum of the thicknesses of the upper and lower cases of the battery case of Sample 1, with the outer edges of the upper and lower cases facing each other, was 137 μm.

[0101] In order to seal the outer edges of the upper case and the lower case of the battery case of Sample 1, a sealing temperature of 0.03 kgf / cm was applied at a sealing temperature of 185°. 2 Apply pressure for 3 seconds to perform a seal.

[0102] A photograph of the battery case of Sample 1 after completing the primary sealing is shown in FIG. Figure 3 In. Reference Figure 3 The measured height of the aggregated spheres was 248.74 μm.

[0103] Changes in the length of the temporary connection region and the thickness of the polymerized ball of each of the plurality of battery cases were observed under the same conditions as those of Samples 1, 2, and 3. Figure 5 Shows the length of the temporary connection area formed by the polymeric balls after the primary seal (a) and the secondary seal (b), Figure 6 The thickness of the polymeric spheres after primary sealing (a) and secondary sealing (b) is shown.

[0104] Reference Figures 3 to 6 , it was observed that the length of the temporary connection area did not change significantly even after the primary and secondary sealing was performed. However, it was observed that the thickness of the polymer ball changed after the primary and secondary sealing, and thus the sealing force changed.

[0105] Reference Figures 3 to 6 The thickness of the polymer balls in the primary sealing portion is 220 μm to 290 μm, and the thickness of the polymer balls in the secondary sealing portion is 150 μm to 170 μm.

[0106] Samples 2 and 3 were subjected to primary sealing under the same conditions as those for the primary sealing of Sample 1.

[0107] The sealing force curve obtained by measuring the sealing force of sample 1 three times is Figure 7 The solid line shows that the sealing force curve obtained by measuring the sealing force of sample 2 twice is shown in FIG. Figure 8 The solid line shows that the sealing force curve obtained by measuring the sealing force of sample 3 twice is shown in FIG. Figure 9 Indicated by solid line.

[0108] The following Table 1 shows the average value of the peak value of the sealing force curve of each sample. In Table 1, for the comparative example, only one sealing was performed on Sample 1, Sample 2, and Sample 3.

[0109] <Example 1>

[0110] Sample 1 of the comparative example was prepared and a 40 kgf / cm 2 The force is applied to a portion of the outer edge of the primary seal for 8 seconds as a secondary seal.

[0111] The photo of the battery case of sample 1 after the secondary sealing is completed is as follows: Figure 4 shown.

[0112] Reference Figure 4 The height of the polymerized spheres was measured to be 134.96 μm. Therefore, it can be seen that the size of the polymerized spheres after secondary sealing is about 45% smaller than that after only one sealing.

[0113] The sealing force curve obtained by measuring the sealing force of sample 1 three times after secondary sealing is Figure 7 The dashed line is shown in FIG. 1 and the following Table 1 shows the peak value average of the sealing force curves of three measurements.

[0114] <Example 2>

[0115] Sample 2 of the comparative example was prepared, and secondary sealing was performed at a sealing temperature of 185° C. for 3 seconds without applying pressure.

[0116] The sealing force curve obtained by measuring the sealing force of sample 2 twice after secondary sealing is Figure 8 The dashed line is shown in FIG. 1 and the following Table 1 shows the peak value average of the sealing force curves of the two measurements.

[0117] <Example 3>

[0118] Sample 3 of the comparative example was prepared and a pressure of 40 kgf / cm was applied at a sealing temperature of 185°C. 2 The force is applied for 3 seconds as a secondary seal.

[0119] The sealing force curve obtained by measuring the sealing force of sample 3 twice after secondary sealing is Figure 9 The dashed line is shown in FIG. 1 and the following Table 1 shows the peak value average of the sealing force curves of the two measurements.

[0120] In order to measure the sealing force of the battery cases manufactured according to Comparative Example and Examples 1 to 3, a peel strength measurement experiment was performed as follows, and the results are shown in Table 1 below.

[0121] <Experimental Example>

[0122] Measurement of peel strength

[0123] The battery cases produced according to Comparative Example and Examples 1 to 3 were peeled at a speed of 250 mm / min and an angle of 180 degrees using a TA instrument (model: Texture Analyzer) manufactured by Stable Micro System, and the force required at this time was measured.

[0124] [Table 1]

[0125]

[0126] Referring to Table 1 above, it can be seen that for Sample 1, the sealing force when only one sealing is performed is higher than the sealing force after further performing a secondary sealing.

[0127] At the same time, it can be seen that for samples 2 and 3, the sealing force after further performing a secondary seal is higher than the sealing force when only one seal is performed.

[0128] Therefore, it can be seen that, as in the present invention, when the secondary sealing is performed at a temperature lower than the primary sealing temperature, the sealing force is smaller than the sealing force when only the primary sealing is performed. Figure 3 and Figure 4As shown, in the case where the primary and secondary sealing are performed and the secondary sealing temperature is lower than the primary sealing temperature, the size of the polymerized balls is significantly reduced, thereby reducing the sealing force.

[0129] It can be seen from Examples 2 and 3 that when the secondary sealing temperature is equal to or higher than the primary sealing temperature, the sealing force increases, from which it can be seen that the effect of temperature is greater than that of pressurization.

[0130] Those skilled in the art to which the present invention pertains will appreciate that, based on the above description, various applications and modifications are possible within the scope of the present invention.

[0131] (Explanation of Reference Numerals)

[0132] 101: First shell

[0133] 101a, 102a: External resin layer

[0134] 101b, 102b: Metal layer

[0135] 101c, 102c: Internal adhesive layer

[0136] 102: Second shell

[0137] 105: Electrode assembly accommodating portion

[0138] 108: Polymerization Ball

[0139] 110: Electrode assembly

[0140] 200: One-time sealing tool

[0141] 220: Primary sealing part

[0142] 300: Secondary sealing tool

[0143] 320: Secondary sealing part

[0144] Industrial Applicability

[0145] The present invention relates to a method for manufacturing a soft-pack type battery cell, comprising: housing an electrode assembly in a battery case made of a laminate; performing a primary sealing on the outer edge of the battery case; and performing a secondary sealing on at least a portion of the primary-sealed outer edge, wherein the sealing force of the sealing portion formed after the primary and secondary sealing is low, thereby guiding the exhaust position and exhaust time of the soft-pack type battery cell, and therefore the present invention has industrial applicability.

Claims

1. A method for manufacturing a soft-pack battery cell, comprising: housing the electrode assembly in a battery case made of a laminate; Performing a primary seal on the outer edge of the battery housing; and Performing a secondary seal on at least a portion of the primary sealed outer edge, wherein the primary sealing and the secondary sealing are performed by pressurizing the upper shell and the lower shell using a high temperature sealing tool, and The sealing temperature of the primary seal is higher than the sealing temperature of the secondary seal, wherein the sealing force of the sealing portion formed after performing the primary sealing and the secondary sealing is smaller than the sealing force of the sealing portion formed after performing only the primary sealing, wherein the secondary sealing is performed on a portion of the primary sealing portion that has already been sealed, where venting is desired to occur so as to form a vent portion having a low sealing force, and In the secondary sealing step, the size of the polymeric spheres is reduced.

2. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The sealing temperature of the primary seal is greater than 130°C to 250°C, and The sealing temperature of the secondary seal is 50°C to less than 200°C.

3. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The primary sealing is a process of sealing the entire outer edge of the battery case to thereby seal the battery case.

4. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The secondary seal seals at least one of at least a portion of the major axis seal portion, at least a portion of the minor axis seal portion, and a portion of a corner portion of the battery case.

5. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The secondary seal seals the middle portion of the long axis seal portion of the battery housing.

6. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The sealing time of the secondary seal is longer than the sealing time of the primary seal.

7. The method for manufacturing a soft-pack type battery cell according to claim 6, wherein: The sealing time of the secondary seal is more than 5 seconds.

8. The method for manufacturing a soft-pack type battery cell according to claim 1, wherein: The pressure of the secondary seal is higher than the pressure of the primary seal. 9 . A soft-pack type battery cell manufactured by the method for manufacturing a soft-pack type battery cell according to claim 1 .

10. The soft-pack type battery cell according to claim 9, wherein: The soft pack type battery cell includes a battery case made of a laminate including an outer resin layer, a metal layer, and an inner adhesive layer, and The thickness of the polymerized balls in the sealing portion formed after the primary sealing and the secondary sealing are performed is 60% to 70% of the thickness of the polymerized balls in the sealing portion formed after only the primary sealing is performed.

11. The soft-pack type battery cell according to claim 9, wherein: The soft pack type battery cell includes a battery case made of a laminate including an outer resin layer, a metal layer, and an inner adhesive layer, and The thickness of the polymerized balls in the sealed portion formed after only one sealing is 220 μm to 290 μm, and The thickness of the polymerized balls in the sealing portion formed after further secondary sealing is 150 μm to 170 μm.

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