Pouch-type cell and method for forming its sealing part

Abstract

A pouch-type cell and a method for forming the sealing portion thereof are disclosed, in which the overall width of the pouch cell is maintained uniform from top to bottom by completely fixing the sealing portion of the pouch cell without using tape through molding using infrared heating. The pouch-type cell includes an electrode assembly receiving portion; and sealing portions located on both side ends of the electrode assembly receiving portion and protruding outward, the sealing portions including a folded portion at an end thereof, and the folded portion of the sealing portion forms an angle of 80° to 90° with the portion of the sealing portion excluding the folded portion without the aid of external force.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0115787 filed on August 31, 2021, and Korean Patent Application No. 10-2022-0093598 filed on July 28, 2022, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a pouch-type cell and a method for forming a sealing part thereof, and more particularly, to a pouch-type cell in which the entire width of the pouch cell is uniformly maintained from the upper part to the lower part by completely fixing the sealing part of the pouch cell without using a tape through molding using infrared heating, and a method for forming the sealing part thereof.

Background Art

[0003] As the technology development and demand related to mobile devices and automobiles have explosively increased, more research has been conducted on secondary batteries having high energy density, discharge voltage, and excellent output stability. Examples of such secondary batteries include lithium secondary batteries such as lithium-sulfur batteries, lithium-ion batteries, and lithium-ion polymer batteries. In addition, the secondary batteries as described above can be classified into cylindrical, prismatic, pouch-type, etc. according to their shapes, and among them, the interest and demand for pouch-type battery cells are gradually increasing. The pouch-type battery cell can be stacked with a high degree of integration, has a high energy density per unit weight, is inexpensive, and is easily deformable. Therefore, the pouch-type battery cell can be manufactured in various forms and sizes applicable to various mobile devices and automobiles.

[0004] A normal pouch-type battery cell has a sealing structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator is laminated and housed in a soft battery case (i.e., a stacked-type electrode assembly or a stacked / folding-type electrode assembly is housed in the battery case), and the end of the battery case has a sealing portion sealed by heat welding or the like. The soft packaging material sheet constituting the battery case is made of one or more of a resin layer and a metal layer, and by forming a sealing portion at its end, it not only prevents the electrode assembly from detaching to the outside but also plays a role of protecting from external impacts. The sealing portion of the battery case is formed in a shape protruding from the side surface of the battery cell.

[0005] FIG. 1 is an exploded perspective view of a normal pouch-type battery cell. Referring to FIG. 1, a normal pouch-type battery cell 10 includes an electrode assembly 30, electrode tabs 40 and 50 extending from the electrode assembly 30, electrode leads 60 and 70 welded to the electrode tabs 40 and 50, and a battery case 20 housing the electrode assembly 30. The electrode assembly 30 has a structure in which a positive electrode and a negative electrode are sequentially laminated with a separator interposed therebetween, and has a stacked or stacked / folding structure. The electrode tabs 40 and 50 extend from each electrode plate of the electrode assembly 30, and the electrode leads 60 and 70 are electrically connected to a plurality of electrode tabs 40 and 50 extending from each electrode plate, respectively, and a part thereof is exposed outside the battery case 20. Further, an insulating film 80 can be attached to a part of the upper and lower surfaces of the electrode leads 60 and 70 to enhance the sealing degree with the battery case 20 and at the same time ensure an electrically insulated state. The battery case 20 is generally made of a laminated sheet containing resin, metal, or a mixture thereof, provides a space capable of housing the electrode assembly 30, and has an overall pouch shape. In the case of the laminated electrode assembly 30 as shown in FIG. 1, the upper inner part of the battery case 20 can be separated from the electrode assembly 30 so that a plurality of positive electrode tabs 40 and a plurality of negative electrode tabs 50 can be combined together with the electrode leads 60 and 70.

[0006] Such a pouch-type battery cell goes through the process of housing the electrode assembly in a battery case, injecting an electrolyte, and then sealing it by heat fusion or the like. Finally, it goes through the process of vertically bending both outer peripheral surfaces of the battery cell or the heat fusion part (sealing part). Figure 2 is a schematic diagram of vertically bending and fixing the sealing part of a normal pouch-type battery cell. Conventionally, in order to vertically bend and fix the sealing part of a pouch-type battery cell, the steps as shown in Figure 2 were carried out.

[0007] Specifically, conventionally, 1) the sealing part was thermocompression bonded by heat press (if necessary, after cutting the sealing part to an appropriate length and then performing thermocompression bonding), 2) the tip of the thermocompression-bonded sealing part was bent and formed at 90° using a separate rising block and a support base, 3) the tip of the sealing part bent at 90° was bent and formed at 90° again in the direction of the electrode assembly housing part using a separate block to overlap the sealing parts (a total of 180° bending and forming including the previous 90° bending and forming), 4) the overlapped sealing parts were thermocompression bonded by heat press, 5) after vertically positioning support bases on the upper and lower stages respectively between the overlapped sealing parts and the electrode assembly housing part, a separate block was positioned so as to face the outer surface of the lower support base with reference to the electrode assembly housing part, and this block was raised in the direction of the upper support base to bend and form the tip of the overlapped sealing part at 90° (a total of 270° bending and forming including the previous 180° bending and forming), 6) the tip of the overlapped sealing part bent at 90° was side-pressed by a separate block, and finally, 7) through the process of fixing the tip of the overlapped sealing part bent at 90° with tape, the sealing part of the battery cell was made to be adjacent to the electrode assembly housing part as much as possible.

[0008] Figure 3 is a schematic diagram of fixing the sealing part with tape in a normal pouch-type battery cell. However, as shown in Figure 3, when the sealing part is fixed with tape, as shown in Figure 3 and Table 1 below, a full-width difference inevitably occurs between the tape-attached parts (1, 3, 5 in Figure 3) and the tape-unattached parts (2, 4 in Figure 3).

[0009] [Table 1]

Table 1

[0010] If such a full-width difference occurs (in the above case, a difference of up to 1.4 mm occurs in the full width of the cell) and the full-width process control cannot be performed, when assembling the module, the error in the full width will be large and the cell will not fit into the module. Eventually, it is necessary to manually perform some cells, resulting in inevitable process losses. Therefore, a technology is required that can fundamentally solve the problems (i.e., process losses caused by the full-width difference of the pouch cell) when bending the sealing portion in the pouch-type cell.

Summary of the Invention

Problems to be Solved by the Invention

[0011] Therefore, an object of the present invention is to provide a pouch-type cell in which the full width of the pouch cell is uniformly maintained from the upper stage to the lower stage and a method for forming the sealing portion thereof by completely fixing the sealing portion of the pouch cell without using a tape through molding using infrared heating.

Means for Solving the Problems

[0012] To achieve the above object, the present invention includes an electrode assembly housing portion; and sealing portions respectively located at both side ends of the electrode assembly housing portion and protruding outward, the sealing portion includes a portion where the tip is folded, and the folded portion of the sealing portion forms a certain angle in the range of 80° to 90° with the portion of the sealing portion excluding the folded portion without the help of an external force. A pouch-type cell is provided.

[0013] Further, the present invention includes: (a) folding the tips of the sealing portions, which are respectively located at both side ends of the electrode assembly housing portion and protrude outward, toward the electrode assembly housing portion; (b) thermocompression bonding the folded sealing portions; (c) positioning an upper support base and a lower support base so as to face each other in a direction perpendicular to the upper and lower surfaces of the sealing portion between the folded sealing portions and the electrode assembly housing portion; and (d) positioning a block so as to face the outer surface of the lower support base with reference to the electrode assembly housing portion, and raising the block in the direction of the upper support base to bend and form the tip of the folded sealing portion toward the electrode assembly housing portion side. After any one or more of the steps (a), (b), and (d) are being executed or have been executed, the overlapped portion or the bent portion is heated with infrared rays. A method for forming a sealing portion of a pouch-type cell is provided, which is characterized in that.

Advantages of the Invention

[0014] The pouch-type cell and the method for forming a sealing portion thereof according to the present invention can completely fix the sealing portion of the pouch cell without using a tape through molding using infrared heating, thereby maintaining the entire width of the pouch cell uniformly from the upper stage to the lower stage and easily managing it within a specific dimension range. As a result, different from the conventional process in which the sealing portion is incompletely fixed using a tape, it is possible to reduce the manual production loss that occurs during the assembly of the module. Further, different from the conventional method, since a tape is not used, the manufacturing cost can be reduced, and there is also an advantage of excellent process capability (i.e., dispersion) of the entire width.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] FIG. 4 is a perspective view of a pouch-type cell according to the present invention, and FIG. 5 is a side cross-sectional view of a pouch-type cell according to the present invention. As shown in FIGS. 4 and 5, the pouch-type cell 100 according to the present invention includes an electrode assembly housing portion 120 and sealing portions 140 that are respectively located at both side ends of the electrode assembly housing portion 120 and protrude outward. The sealing portion 140 includes a portion 144 where the tip 142 is folded, and the folded portion 144 of the sealing portion 140 forms a certain angle in the range of 80° to 90° with a portion 146 of the sealing portion excluding the folded portion 144 without the help of an external force.

[0018] In order to be provided in a standardized module, the sealing portion (or wing, pouch region sealed on both side surfaces of the cell) of the pouch-type battery cell needs to be vertically bent and fixed so as to be located as adjacent to the electrode assembly housing portion side as possible. This is because if the overall width of the pouch-type battery cell is maintained uniformly from the upper part to the lower part, it can be provided in the module without separate manual work.

[0019] Regarding this, conventionally, in order to vertically bend and fix the sealing portion of the pouch-type battery cell, as shown in FIGS. 2 and 3, the method of fixing the bent sealing portion of the pouch-type battery cell with tape was followed. However, when using tape in this way, a full-width difference occurs between the tape-attached portion and the non-attached portion. If such a full-width difference occurs and the full-width process management cannot be carried out, a large error in the full width will occur during the assembly of the module, and the cell will not fit into the module. Eventually, it is necessary to perform some cells manually, so there is inevitably a process loss. To solve such problems, a plan of attaching tape to the entire sealing portion can be considered. However, in this case, not only will the tape material cost increase compared to the case where the tape is attached sporadically, but the process time will also become longer, and the problem of a decrease in the daily battery production volume will inevitably occur.

[0020] Therefore, the applicant of the present application invented a technique for uniformly maintaining and fixing the full width of the pouch-type battery cell from the upper stage to the lower stage by performing the second folding in the DSF (Double sided folding) process, that is, the process of folding the sealing portion twice to reduce and fix the full width as the finishing process of cell manufacturing, by using the "hot forming method using infrared heating".

[0021] That is, the present invention relates to a pouch-type cell in which the sealing portion of the pouch cell is completely fixed by a hot forming method using infrared heating, and the full width of the pouch cell is uniformly maintained from the upper stage to the lower stage, and is characterized by having the advantage that it can be provided in the module at once without any separate subsequent manual work.

[0022] The end of the electrode assembly housing portion 120 has a sealing structure with a sealing portion 140 sealed by heat fusion or the like. The flexible packaging material sheet constituting the electrode assembly housing portion 120 includes a resin layer and a metal layer, and by forming the sealing portion 140 at its end, it not only prevents the electrode assembly from detaching to the outside, but also serves to protect the electrode assembly from external impacts. Therefore, the sealing portion 140 is formed in a shape protruding from the side surface of the battery cell 100 (or pouch-type cell), and its material is also the same as that of the electrode assembly housing portion 120. The resin layer (or adhesive layer) constituting the electrode assembly housing portion 120 and the sealing portion 140 may contain polypropylene (PP), and the metal layer may contain aluminum, but is not limited thereto.

[0023] The electrode assembly housing portion 120 is where an electrode assembly including one or more unit cells including a positive electrode, a negative electrode, and a separator interposed therebetween is housed. There are no particular restrictions on its configuration, such as the top and bottom of the electrode assembly can have half cells, and it can follow the configuration of a normal electrode assembly. Also, the electrode assembly may be of a stack type or a stack / folding type. Further, as shown in FIG. 4, the positive electrode tab and the negative electrode tab may be located in opposite directions, but as shown in FIG. 1, the positive electrode tab and the negative electrode tab can be located together on only one of them, and their positions can be set variously depending on the type and purpose of the battery.

[0024] The sealing portion 140 includes a portion 144 where the tip 142 is folded inward. This is a form obtained by the first folding during the DSF (Double sided folding) process and is a structural feature for maximizing the fixing force. Also, depending on the second folding during the DSF process, the overlapped portion 144 of the sealing portion 140 and the non-overlapped portion 146 of the remaining seal ring portion 140 form a certain angle without the help of an external force.

[0025] The present invention has a core feature particularly in this regard. The overlapping portion 144 of the sealing portion 140 and the non-overlapping portion 146 of the remaining sealing portion 140 (i.e., the sealing portion part excluding the overlapping portion) form a certain angle without the assistance of an external force such as tape fixation, and the entire sealing portion 140 continuing from the upper part to the lower part on both side faces of the pouch cell is in such a form. That is, the total longitudinal width including the electrode assembly accommodating portion 120 and the sealing portions 140 respectively located at both ends of the electrode assembly accommodating portion 120 is uniform from the upper part (or a single step part) to the lower part (or another step part). At this time, in the total width including the electrode assembly accommodating portion 120 and the sealing portion 140, the ratio of the longest width to the shortest width may be 95 to 100, preferably 97 to 100, and more preferably 99 to 100.

[0026] Also, the angle (inner angle) between the overlapping portion 144 of the sealing portion 140 and the non-overlapping portion 146 of the remaining sealing portion 140 is within the range of 80° to 90°. However, when bending exactly at 90° during manufacturing, it may be within the range of 85° to 90°, more preferably 87° to 90°.

[0027] And the overlapping portion 144 of the sealing portion 140 has a bending force at room temperature of 200 to 250 g / 1 cm, and there is also an advantage that the bending force is improved by about 2 to 2.5 times compared with the case where the overlapping portion 144 of the sealing portion 140 is bent and formed by a heating method using a general heat source instead of the infrared heating method (about 80 to 100 g / 1 cm). This is related to the materials (PP, PET) of the resin layers constituting the electrode assembly accommodating portion 120 and the sealing portion 140. According to the infrared heating method, it is due to the increase in the degree of curing of the resin layer compared with the case of the general heating method.

[0028] On the one hand, it is clarified that there are no particular restrictions on the length of the overlapped portion 144 of the sealing portion 140 and the length of the non-overlapped portion 146 of the remaining sealing portion 140, and they can be variable depending on the size and form of the module including the pouch cell inside.

[0029] Next, a method for forming the sealing portion of the pouch-type cell according to the present invention will be described. FIG. 6 is a process flow diagram sequentially showing how the sealing portion of the pouch-type cell according to an embodiment of the present invention is formed. Referring to FIG. 6, the method for forming the sealing portion of the pouch-type cell according to the present invention includes: (a) folding the tips 142 of the sealing portions 140, which are respectively located at both side ends of the electrode assembly housing portion 120 and protrude outward, in the direction of the electrode assembly housing portion 120; (b) thermocompression bonding the overlapped sealing portions 140; (c) positioning the upper support base 160 and the lower support base 170 so as to face each other in the vertical direction with respect to the upper and lower cross-sectional surfaces of the sealing portion between the overlapped sealing portions 140 and the electrode assembly housing portion 120; and (d) positioning the block 180 so as to face the outer surface of the lower support base 170 with respect to the electrode assembly housing portion 120, and raising the block 180 in the direction of the upper support base 160 to bend and form the tip 144 of the overlapped sealing portion (140) toward the electrode assembly housing portion (120). After any one or more of the steps (a), (b), and (d) are being executed or have been executed, the overlapped portion or the bent portion is heated with infrared rays.

[0030] First, in the step (a), the tip 142 of the sealing parts 140, which are located at both side ends of the electrode assembly housing part 120 and protrude outward, is folded in the direction of the electrode assembly housing part 120 (that is, the first folding). This is a preliminary process for the second folding (or the second bending and forming) in the step (d). The tip 142 of the sealing part 140 can be overlapped so as to be located at any one section of the remaining sealing part 140 that is not folded within a range that does not affect the second folding. However, considering the second folding, it is preferable to overlap the tip 142 of the sealing part 140 so that it is placed at about half the position of the remaining sealing part 140 that is not folded.

[0031] On the other hand, before performing the step (a), if necessary, the sealing parts in the unfolded state as shown in 1 and 2 of FIG. 2 can be thermocompression bonded by Heat Press, and one or more of the steps of bending the tip of the thermocompression-bonded sealing part by about 90° using a separate lifting block and a support base can be further performed. In particular, when the step of bending the tip of the sealing part in the unfolded state by about 90° is performed before the step (a), the sealing part 140 can be overlapped by folding it only by about 90° in the direction of the electrode assembly housing part 120 in the step (a).

[0032] Next, the step (b) is a step of thermocompression bonding the overlapped sealing parts 140 (not shown in FIG. 6). Considering the second folding, it is preferable to thermocompression bond the entire sealing part 140. At this time, there is no limitation on the means for thermocompression bonding the overlapped sealing parts 140. For example, a heat-block with a heat source built into the upper and lower parts of the overlapped sealing parts 140, or a heat-block that is itself heated, can be provided to perform thermocompression bonding simultaneously on the upper and lower parts of the overlapped sealing parts 140. However, it is preferable to use a heat-block with a built-in heat source to improve the heat transfer efficiency.

[0033] On the other hand, the temperature applied to the sealing portion 140 overlapped by the thermocompression bonding in the step (b) may be 160 to 220°C, preferably 180 to 200°C. If the temperature applied to the sealing portion 140 overlapped by the thermocompression bonding is less than 160°C, subsequent folding may not be smooth. If it exceeds 220°C, the PET layer or nylon layer located at the outermost contour of the sealing portion may peel off, and the insulation resistance characteristics may deteriorate due to the hardening of the sealing layer. Also, the time of the thermocompression bonding may be 0.1 to 2 seconds, preferably 0.5 to 1.5 seconds, and more preferably about 0.6 seconds. In this case, it is advantageous from the side of Tack balance, and it is possible to prevent the peeling and hardening phenomena due to excessive heat which is a side effect of IR heating.

[0034] Subsequently, in the step (c), in the vertical direction of the upper and lower surfaces of the sealing portion between the overlapped sealing portion 140 and the electrode assembly housing portion 120, the upper support base 160 is positioned at the upper stage, and the lower support base 170 is positioned at the lower stage. This is to enable the block 180 to stably rise and fall in the step (d) described later, and in particular, to enable the tip 144 of the overlapped sealing portion 140 to be pressure-bonded with the maximum force when the block 180 rises.

[0035] Furthermore, as shown in FIG. 6, the upper support base 160 may have a straight form like the lower support base 170. However, in view of the springback phenomenon at the tip, it may have a certain angle so that the tip 144 of the overlapped sealing portion 140 bends maximally toward the electrode assembly housing portion 120 side (that is, the upper support base 160 may have an inclined portion inclined in the direction of the electrode assembly housing portion 120 while going upward from the lower stage portion). In this case, the inner angle of the upper support base 160 (that is, the outer side direction with respect to the electrode assembly housing portion 120 reference) may be 90° to 150°.

[0036] On the one hand, it is preferable that the upper support base 160 and the lower support base 170 are made of a material excellent in thermal resistance and strength. In step (d), not only does the block 180 come into contact with the upper support base 160 and the lower support base 170, but also when the block 180 rises, it is side-pressed in the direction of the electrode assembly housing portion 120 or the direction of the support bases 160 and 170. Therefore, the upper support base 160 and the lower support base 170 may be made of heat-resistant stainless steel, heat-resistant ceramic, or heat-resistant polymer excellent in thermal resistance and strength.

[0037] In step (d), the block 180 is arranged so as to face the outer surface of the lower support base 170 with respect to the electrode assembly housing portion 120, and the block 180 is raised in the direction of the upper support base 160 to bend and form the tip 144 of the overlapped sealing portion 140 toward the electrode assembly housing portion 120 side. The block 180 may include a heat source inside, be heated by an external heat source, or be in a state of not generating heat.

[0038] The pressure applied to the overlapped sealing portion 140 through the block 180 may be 0.2 to 0.7 MPa, preferably 0.2 to 0.5 MPa. If the pressure applied to the overlapped sealing portion 140 is less than 0.2 MPa, since the force applied to the tip of the sealing portion is small, a problem may occur in that the tip of the sealing portion spreads due to elastic recovery (i.e., an excessive spring-back phenomenon). Also, when the pressure applied to the overlapped sealing portion 140 exceeds 0.7 MPa, cracks may be induced in the sealing layer within the sealing portion, causing problems in insulation resistance and insulation voltage.

[0039] Also, the crimping time using the block 180 may be 1 to 10 seconds, preferably 1 to 8 seconds. If the crimping time using the block 180 is less than 1 second, it may be difficult to ensure the minimum process time for fixing the sealing part, and there may be a problem that it is difficult to maintain the target shape. When the thermocompression bonding time using the block 180 exceeds 10 seconds, it may be difficult to ensure the process tack, and there may be a problem that it is difficult to ensure the insulation resistance and thickness due to the excessive thermocompression bonding time.

[0040] On the other hand, as described above, after any one or more of the steps (a), (b), and (d) are being executed or have been executed, a step of heating the overlapped part or the bent part with infrared rays is performed. This is a step for increasing the flexibility of the sealing part 140 and improving the fixing force, particularly when forming the sealing part (i.e., the second folding) performed in step (d). In the case of a general heating method for the sealing part, heat is concentrated only on the PET / nylon layer and the adhesive layer, which are the surfaces of the pouch or the sealing part, and the uniform heating and sealing of the PP layer are incomplete. However, when using infrared heating as in the present invention, there is an advantage that the PP layer can be heated in a short time and then pressurized.

[0041] The infrared heating may be near-infrared (N-IR) heating, mid-infrared (M-IR) heating, or far-infrared (F-IR) heating. Among these, mid-infrared heating is preferred in that it can heat the PP layer of the pouch in a short time and uniformly heat up to the inside of the pouch surface.

[0042] For example, the heating of the sealing part by the infrared rays can be carried out in various ways, such as during the progress of the step (a) or immediately after the progress, during the heat pressing of the overlapped sealing part 140 or immediately after the heat pressing (that is, between the step (b) and the step (c)), and when the block 180 is positioned, raising it in the direction of the upper support base 160 to bend and form the tip 144 of the overlapped sealing part 140 toward the electrode assembly housing part 120. However, as shown in FIG. 6, it is preferable that the infrared heating 200 is performed before bending and forming the tip 144 of the overlapped sealing part 140 toward the electrode assembly housing part 120. That is, in other words, it is preferable that the infrared heating 200 is performed before raising the block 180 in the direction of the upper support base 160.

[0043] Even if the infrared heating 200 is performed only for a very short time, the fixing force of the bent sealing part can be improved. That is, the time of the infrared heating 200 may be 1 to 2 seconds, and it is more preferable to heat as close to 1 second as possible. If the time of the infrared heating is less than 1 second, the flexibility of the sealing part due to the infrared heating is insufficient, and the bending and forming in the step (d) may be incomplete. Also, when the time of the infrared heating exceeds 2 seconds, peeling on the surface of the sealing part can be induced by an excessive heat source.

[0044] The temperature during such infrared heating 200 can be set accordingly so that the PP layer of the sealing part is 140 to 170 °C, preferably 150 to 160 °C (at this time, the temperature on the surface of the sealing part may be 160 to 220 °C). If the temperature of the PP layer of the sealing part is formed below 140 °C even after the infrared heating, the intended folding may not be performed. Also, if the temperature of the PP layer of the sealing part is formed at a temperature exceeding 170 °C even after the infrared heating, the fluidity increases and it may not be easy to ensure a uniform sealing thickness and insulation characteristics.

[0045] FIG. 7 is a process flow diagram sequentially showing a state of forming a sealing portion of a pouch-type cell according to another embodiment of the present invention. As shown in FIG. 7, in the method of forming the sealing portion of the pouch-type cell according to the present invention, after the step (d) of raising the block 180 in the direction of the upper support base 160 and bending and forming the tip 144 of the overlapped sealing portion 140 toward the electrode assembly housing portion 120, if necessary, a cooling block 220 (Cooling Block) may be applied to the outer surface outside the reference of the electrode assembly housing portion of the bent portion to pressurize and cool the outer surface.

[0046] The cooling block 220 is a means capable of further improving the fixing force of the sealing portion formed by infrared heating, and may include a cooling source inside, or may be cooled through an external cooling source. The temperature of the cooling block 220 may be 10°C or less. If the temperature of the cooling block 220 exceeds 10°C, the performance of cooling cannot be expected, and there may be no advantage in using the cooling block 220.

[0047] Also, the pressure applied to the overlapped sealing portion through the cooling block 220 may be 0.2 to 0.7 MPa, preferably 0.2 to 0.5 MPa. Also, the crimping time using the cooling block 220 may be 1 to 10 seconds, preferably 1 to 8 seconds. If the crimping time using the cooling block 220 is less than 1 second, there may be no advantage in using the cooling block 220, and if it exceeds 10 seconds, a decrease in insulation resistance characteristics can be induced.

Example

[0048] On the one hand, through the above description and drawings, only the sealing part (i.e., the main sealing part) located on one side of the pouch cell has been described, but it is clarified that the sealing parts located on the remaining sides can also be formed into the same form through the same process. In addition, although the forming method of the pouch-type cell and its sealing part according to the present invention has been described above with reference to specific embodiments, the present invention is not limited thereto, and it should be noted that various modifications are possible within the scope of the present invention and the scope of the technical idea. Furthermore, hereinafter, in order to assist in the clear understanding of the present invention, the embodiments implemented above will be compared with comparative examples that deviate from the scope of the present invention.

[0049] [Example 1] Manufacturing of a pouch-type cell with a uniform overall width First, after preparing a pouch-type cell containing an electrode assembly in which a plurality of unit cells including a positive electrode, a negative electrode, and a separator are stacked, the sealing parts located at both side ends of the pouch-type cell were cut to an appropriate length. Next, the remaining sealing parts were thermocompression bonded by hot pressing, and the tip of the thermocompression-bonded sealing part was bent and formed at 90° using a separate lifting block and a support base. Subsequently, the tip of the sealing part bent and formed at 90° was bent and formed in the direction of the electrode assembly housing part to stack the sealing parts, and then the stacked sealing parts were thermocompression bonded. Subsequently, an upper support base and a lower support base were positioned respectively at the upper and lower stages between the stacked sealing parts and the electrode assembly housing part. Subsequently, after positioning a block so as to face the outer surface of the lower support base with reference to the electrode assembly housing part, mid-infrared (M-IR, Philips) was radiated to the sealing part at a temperature of 180°C for 1 second to heat it. Finally, the block was lifted in the direction of the upper support base to bend and form the tip of the stacked sealing part toward the electrode assembly housing part side, and the stacked sealing parts bent and formed on the electrode assembly housing part side were fixed vertically with reference to the cross-section on the cell side.

[0050] [Example 2] Manufacturing of a pouch-type cell with a uniform overall width After facing a cooling block cooled to 7°C in the outer direction with respect to the electrode assembly housing part of the stacked sealing part bent and fixed perpendicularly to the cell side cross-section reference, the sealing part of the pouch-type cell was formed in the same manner as in Example 1, except that pressure was applied in the direction of the electrode assembly housing part for 3 seconds.

[0051] [Comparative Example 1] Manufacture of pouch-type cell The sealing part of the pouch-type cell was formed in the same manner as in Example 1, except that no mid-infrared rays were radiated to the sealing part.

[0052] [Comparative Example 2] Manufacture of pouch-type cell The sealing part of the pouch-type cell was formed in the same manner as in Example 1, except that instead of radiating mid-infrared rays to the sealing part, heat was provided to the sealing part for 1.5 seconds with a heating body equipped with a general heat source at a temperature of 180°C.

[0053] [Test Example 1] Evaluation of full-width process capability (dispersion) For each of the pouch-type cells in which the sealing part was formed in Example 1, 2 and Comparative Example 1, the full width at a total of 7 locations (including the taping part where the deviation of the full width is large based on the standard of a normal pouch-type cell where the sealing part is attached with tape, the non-taping part, and both ends of the cell, etc.) was measured, and the full-width process capability (that is, dispersion) was evaluated (a total of 5 cells were measured).

[0054] As a result of the evaluation, the pouch-type cell of Example 1 in which the infrared rays were radiated to vertically bend and form the sealing part had a standard deviation of the full width of about 0.40 mm, and the pouch-type cell of Example 2 further pressed with a cooling block had a standard deviation of the full width of only about 0.38 mm. On the other hand, the pouch-type cell of Comparative Example 1 that did not utilize both infrared rays and a cooling block had a standard deviation of the full width of about 0.83 mm, and a standard deviation more than twice that of Examples 1 and 2 occurred. Therefore, since the pouch-type cells of Examples 1 and 2 have a dispersion that gathers around the average value compared to the pouch-type cell of Comparative Example 1, they are excellent in the quality of the full width, have a low defective rate, and are easy to manage, so it can be seen that they are superior in terms of process capability.

[0055] [Test Example 2] Evaluation of Bending Force of Sealing Part For each of the pouch-type cells manufactured in Example 1 and Comparative Example 2, the bending force of the overlapped part in the sealing part was measured. For the measurement, a UTM (model name: HD-B609B-S) was used, and the same external force was applied to the overlapped part in the sealing part at room temperature to observe the degree of bending.

[0056] As a result of measuring the bending force for the overlapped part in the sealing part of each pouch-type cell as described above, it was confirmed that the pouch-type cell of Example 1 in which the infrared rays were radiated to bend and form the sealing part showed a bending force of about 232 g / 1 cm for the overlapped part of the sealing part. On the other hand, the pouch-type cell of Comparative Example 2 in which the sealing part was bent and formed with a heating body equipped with a general heat source showed a bending force of about 93 g / 1 cm for the overlapped part of the sealing part, and it was not easy to easily bend it with a weak force and maintain verticality.

Explanation of Reference Signs

[0057] 100: Pouch-type cell 120: Electrode assembly housing part 140: Sealing part 160: Upper support base 170: Lower support base 180: Block 200: Infrared heating 220: Cooling block

Claims

1. (a) Folding the tips of the sealing parts, which are respectively located at both side ends of the electrode assembly housing part and protrude outward, in the direction of the electrode assembly housing part; (b) Thermocompression bonding the folded sealing parts; (c) Positioning an upper support base and a lower support base so as to face each other in a direction perpendicular to the upper and lower cross-sectional surfaces of the sealing part between the folded sealing part and the electrode assembly housing part; and (d) Positioning a block so as to face the outer surface of the lower support base with reference to the electrode assembly housing part, and raising the block in the direction of the upper support base to bend and form the tip of the folded sealing part toward the electrode assembly housing part side; including A method for forming a sealing part of a pouch-type cell, wherein after any one or more of the steps (a), (b), and (d) are being executed or have been executed, the folded part or the bent part is heated with infrared rays.

2. The method for forming a sealing part of a pouch-type cell according to Claim 1, wherein the heating with infrared rays is selected from the group consisting of near-infrared (N-IR) heating, mid-infrared (M-IR) heating, and far-infrared (F-IR) heating.

3. The method for forming a sealing part of a pouch-type cell according to Claim 1, wherein the heating with infrared rays is mid-infrared heating.

4. The method for forming a sealing part of a pouch-type cell according to Claim 1, wherein the heating with infrared rays is performed before raising the block in the direction of the upper support base in the step (d).

5. The method for forming a sealing part of a pouch-type cell according to Claim 1, wherein the heating with infrared rays is performed for 1 to 2 seconds.

6. After the tip of the folded sealing part in the step (d) is bent and formed toward the electrode assembly housing part side, the folded part of the sealing part forms a certain angle in the range of 80° to 90° with the non-folded part of the remaining sealing part without the assistance of an external force. The method for forming a sealing part of a pouch-type cell according to any one of Claims 1 to 5.

7. The method for forming a sealing part of a pouch-type cell according to Claim 1, wherein the method for forming the sealing part further includes, after the step (d), applying a cooling block to the outer surface of the electrode assembly housing part on the outer side of the bent part to pressurize and cool the outer surface.

8. The method for forming a sealing portion of the pouch-type cell according to claim 7, wherein the cooling block pressurizes an outer surface of the bent portion at a temperature of 10°C or lower and a pressure of 0.2 to 0.7 MPa for 1 to 10 seconds.

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