Pre-folding device for pouch-type batteries

Abstract

The disclosed invention relates to a pre-folding device for pouch-type batteries, and in one example, the pre-folding device for pouch-type batteries includes a main frame including a pair of columns and a horizontal bar connecting the upper parts of the columns, a rib fixedly installed below the horizontal bar across the pair of columns and having a flat forming protrusion at an upper end, a pusher support part including a linear drive part that moves up and down along the columns and is disposed above the rib, and a pusher installed on the pusher support part and aligned with the forming protrusion.

Description

Technical Field

[0001] The present invention relates to a pre-folding device for a pouch-type battery, and by performing pre-processing on a protruding bridge that connects two storage parts in which an electrode assembly is housed, it relates to a pre-folding device for a pouch-type battery that can improve the quality of the pouch-type battery and reduce defects.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0170400 filed on December 1, 2021, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0003] Technological development and demand for mobile devices have increased, and the demand for secondary batteries as an energy source to replace fossil fuels has also increased rapidly. As a result, many studies have been conducted on secondary batteries that can meet various requirements.

[0004] When looking at secondary batteries from the shape aspect of the battery case, they are typically classified into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is built into a pouch-type case made of an aluminum laminate sheet. And in terms of materials, there is a high demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries that are excellent in terms of high energy density, discharge voltage, and output stability.

[0005] Among these, pouch-type batteries are in high demand due to their advantages of having a thin thickness in terms of shape, being easy to stack, and being able to partially deform the shape. A pouch-type battery has a structure in which an electrode assembly and an electrolyte are built into a pouch-type laminate sheet capable of housing the electrode assembly, and the resin layer of the laminate sheet has the characteristic that it can be heat-sealed.

[0006] Figure 1 is a schematic diagram illustrating the folding process, which is one of the processes involved in manufacturing a conventional pouch-type battery. The folding process is a preliminary step before sealing the laminate sheet 1, which is folded in half and contains the electrode assembly 4. The laminate sheet 1 has two concave storage compartments 2 (also called "cups" in the industry) for housing the electrode assembly 4, and the subsequent sealing process is prepared by folding in half the intermediate protruding bridge 3 portion that forms the side wall of the two storage compartments 2.

[0007] However, with the advent of large-cell manufacturing for pouch-type batteries, the need to improve the conventional folding process arose. Specifically, as the capacity and size of pouch-type batteries increased, the thickness of the laminate sheet also increased by approximately 120% compared to conventional methods. This was a necessary change to ensure the pressure resistance of high-capacity pouch-type batteries, and the increased thickness of the laminate sheet affected the folding process.

[0008] The increased rigidity of the thicker laminate sheet prevented the intermediate bridge section forming the side walls of the two storage compartments from fully returning to its original state when folded in half during the folding process shown in Figure 1. As a result, the pointed end of the bridge, which did not return properly, pressed against the electrode assembly inside the storage compartment, disrupting the desirable alignment of the electrode assembly.

[0009] One solution to these problems involved folding the laminate sheet without the electrode assembly in half during a preliminary primary folding process, then returning it to its original state, and finally placing the electrode assembly into the storage compartment and folding it completely in half during a secondary folding process.

[0010] While weakening the bridge's rigidity through the primary folding process was effective in solving conventional problems, precisely folding an empty laminate sheet in half without the electrode assembly required designing a somewhat complex mechanism. Furthermore, the need for two folding processes increased the equipment area occupied by the folding device, leading to longer cycle times. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Korean Registered Patent No. 10-1603074 (Registered March 8, 2016) [Overview of the project] [Problems that the invention aims to solve]

[0012] The object of the present invention is to provide an apparatus that enables the folding of a pouch-type battery made of a thick laminate sheet material in only one main folding step, without the need for a preliminary primary folding step. [Means for solving the problem]

[0013] The present invention relates to a pre-folding device for pouch-type batteries. In one example, the pre-folding device for pouch-type batteries includes a main frame including a pair of columns and a horizontal bar connecting the upper parts of the columns; a rib fixedly installed below the horizontal bar across the pair of columns and having a forming projection with a flat upper end; a pusher support positioned above the rib and including a linear drive unit that moves vertically along the columns; and a pusher installed on the pusher support and aligned with the forming projection.

[0014] According to the pre-folding device for pouch-type batteries of the present invention, a laminate sheet including a bridge formed to protrude between two concave storage portions that house an electrode assembly is inserted so that the bridge fits into the forming protrusion, and as the pusher support portion descends, the pusher presses on the tip of the bridge, causing it to plastically deform and flatten.

[0015] In one embodiment of the present invention, the pusher is characterized in that it is a roller that moves along the longitudinal direction of the pusher support by driving the roller running section.

[0016] The roller can travel on the forming projection by driving the roller running section.

[0017] The system may further include a roller drive unit connected to the rotation axis of the roller and for rotationally driving the roller.

[0018] In another embodiment of the present invention, the pusher is a bar-shaped pusher having a length corresponding to the length of the forming projection.

[0019] Furthermore, the width of the pusher may be wider than the width of the upper end of the forming projection.

[0020] In one example, the linear drive unit may stop its downward movement when the power load applied during the downward movement of the pusher support unit reaches a reference value.

[0021] In another example, the pusher may be provided with a heating means for heating the pusher to a temperature range below the melting point of the thermoplastic resin forming the internal insulating layer of the laminate sheet.

[0022] When using the pre-folding device for the pouch-type battery having the above-described configuration, a pouch-type battery including an electrode assembly and a pouch-type battery case in which a storage portion for housing the electrode assembly protrudes on both sides in the thickness direction and edges of three surfaces excluding one corner forming the side wall of the storage portion are sealed by heat fusion can be provided, in which a flat portion plastically processed along the middle of the side wall of the storage portion is extended and formed.

Effects of the Invention

[0023] When using the pre-folding device for the pouch-type battery of the present invention having the above-described configuration, without the two folding steps of the conventional two-step folding process in which the laminate sheet is first folded in half in a preliminary primary folding step and then stretched back to the original state, and then the electrode assembly is placed in the storage portion and completely folded in half in a secondary folding step, the pouch-type battery can be manufactured with only one main folding step.

[0024] In particular, since the pre-folding device of the present invention extends and forms a flat portion plastically processed along the middle of the side wall of the storage portion of the pouch-type battery case, even when using a thick laminate sheet, the problem that the tip of the bridge that does not return properly to the original state presses the electrode assembly in the storage portion and disturbs the original alignment state does not occur.

[0025] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following detailed description.

Brief Description of the Drawings

[0026] [Figure 1] It is a drawing schematically showing a folding process for manufacturing a conventional pouch-type battery. [Figure 2] It is a drawing showing a first embodiment of the pre-folding device of the present invention. [Figure 3] It is a drawing explaining the operation of the pre-folding device of FIG. 2. [Figure 4]Figure 2 is a diagram illustrating the pre-folding and main-folding processes of a pouch using the pre-folding device shown. [Figure 5] This drawing illustrates a second embodiment of the pre-folding device of the present invention. [Modes for carrying out the invention]

[0027] The present invention can be modified in various ways and may have a variety of embodiments; therefore, specific embodiments will be described in detail below.

[0028] However, this should not be understood as limiting the present invention to any particular embodiment, but rather as including all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0029] In the present invention, terms such as "includes" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof as described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0030] Furthermore, in this invention, when a part such as a layer, film, region, or plate is described as being "on top" of another part, this includes not only the case where it is "directly on top" of the other part, but also the case where another part is located in between. Conversely, when a part such as a layer, film, region, or plate is described as being "below" another part, this includes not only the case where it is "directly below" the other part, but also the case where another part is located in between. Also, in this application, being "on top" may include being located not only at the top but also at the bottom.

[0031] The present invention relates to a pre-folding device for pouch-type batteries (hereinafter simply referred to as the "pre-folding device").

[0032] In one example, the pre-folding device comprises a main frame that forms the skeleton, ribs and pusher support sections installed on the main frame, and pushers installed on the pusher support sections.

[0033] The main frame includes a pair of columns and a horizontal bar connecting the tops of the columns. A rib is fixedly installed below the horizontal bar, across the pair of columns, and has a flattened forming projection at its upper end. A pusher support positioned above the rib includes a linear drive unit that moves vertically along the columns, and a pusher installed on the pusher support is aligned with the forming projection of the rib.

[0034] According to the pre-folding apparatus of the present invention, a laminate sheet including a bridge formed to protrude between two concave storage portions that accommodate an electrode assembly is inserted so that the bridge fits into the forming protrusion, and as the pusher support portion descends, the pusher presses on the tip of the bridge, causing it to plastically deform and flatten.

[0035] Using such a pre-folding device, pouch-type batteries can be manufactured by folding the laminate sheet in only one main folding step, eliminating the need for two folding steps as in the conventional method, where the laminate sheet is folded in half in a preliminary primary folding step, then unfolded back to its original state, and then the electrode assembly is placed in a storage compartment and completely folded in half in a secondary folding step.

[0036] In particular, the pre-folding device extends a plastically formed flat section along the middle of the side wall of the storage compartment of the pouch-type battery case. This eliminates the problem of the pointed ends of the bridge, which do not return to their original shape properly, pressing against the electrode assembly inside the storage compartment and disrupting its original alignment, even when using thick laminate sheets.

[0037] The pre-folding device of the present invention will be described in detail below with reference to the attached drawings.

[0038] Figure 2 is a diagram illustrating a first embodiment of the pre-folding device 10 of the present invention, and Figure 3 is a diagram illustrating the operation of the pre-folding device 10.

[0039] Referring to Figure 2, the pre-folding device 10 of the present invention includes a main frame 100, ribs 200, a pusher support section 300, and a pusher 400.

[0040] The main frame 100 is the framework of the prefolding device 10 and includes a pair of vertically positioned columns 110 and a horizontal bar 120 connecting the upper parts of the columns 110. At the bottom of the main frame 100 is a support member 130 that supports the prefolding device 10, with a gap between the pair of columns 110.

[0041] The rib 200 corresponds to a transverse member that is fixedly installed below the horizontal bar 120, crossing a pair of columns 110. Both ends of the rib 200 are fixed and firmly supported on the columns 110, and the rib 200 is provided with a forming projection 210 with a flat upper end.

[0042] Above the rib 200, in other words, between the horizontal bar 120 and the rib 200, a pusher support 300 is positioned that can move vertically along the column 110. The pusher support 300 is coupled to a rail formed on the column 110 and is connected so as to be able to move linearly up and down. The vertical movement of the pusher support 300 is performed by a linear drive unit 310, such as a linear motor.

[0043] In the illustrated embodiment, the linear drive unit 310 is mounted on the pusher support unit 300, but the linear drive unit 310 can also be installed on the main frame 100. In this respect, the configuration is shown as being included in the pusher support unit 300, taking into consideration the function of the linear drive unit 310 to move the pusher support unit 300 up and down, and such equipment does not limit the mounting position of the linear drive unit 310 to the pusher support unit 300.

[0044] The pusher 400 is a component installed on the pusher support 300 and can be described as a type of pressurizing component. The pusher 400 is aligned with the forming projection 210 of the rib 200 located below it. That is, the pusher 400 uses the forming projection 210 as a kind of support base and pushes the tip of the bridge 534 of the laminate sheet 530 placed on the forming projection 210.

[0045] To explain this in detail with reference to Figure 4, in the pre-folding step, the laminate sheet 530 is molded into a form in which two concave storage sections 532 that house the electrode assembly 510 and a bridge 534 protruding between them. The bridge 534 is a folded connecting section that separates the two storage sections 532, and when the center of the bridge 534 expands 180 degrees, it forms the side wall 533 of the storage section 532 on the battery case 520.

[0046] The laminate sheet 530, formed in this shape, is fed into the pre-folding device 10 of the present invention by fitting the bridge 534 into the forming projection 210 of the rib 200. Once the laminate sheet 530 is fed into the pre-folding device 10 in this manner, as shown in Figure 3, the pusher support 300 descends toward the rib 200 by the operation of the linear drive unit 310, and the pusher 400 installed on the descended pusher support 300 presses on the tip of the bridge 534 fitted into the forming projection 210, causing it to plastically deform and flatten.

[0047] Here, it is preferable that the width of the pusher 400 is wider than the width of the upper end of the forming projection 210. In other words, the width of the flat portion 535 formed on the tip of the bridge 534 is designed to correspond to the width of the upper end of the forming projection 210, and the width of the pusher 400 that presses the bridge 534 placed on the forming projection 210 is made wider than the width of the upper end of the forming projection 210, so that the plastically deformed flat portion 535 has sufficient width. If necessary, the material of the pusher 400 can be made harder than the laminate sheet 530 but more brittle than the forming projection 210 to further improve the adhesion between the pusher 400 and the laminate sheet 530.

[0048] The above process corresponds to pre-folding as defined in the present invention, and such pre-folding is performed with the laminate sheet 530 not containing the electrode assembly 510. Furthermore, the pre-folding in the present invention is distinct from conventional primary folding, which involves folding the laminate sheet 530 in half, and should be understood as a plastic deformation process that creates a flat portion 535 as a preliminary step performed prior to the main folding.

[0049] Once pre-folding is complete, the bridge 534 will have a flat surface 535 over its entire length. After pre-folding is complete, the electrode assembly 510 is housed in the storage section 532, and the main folding is performed, folding the bridge 534 in the opposite direction by 180 degrees. After the main folding is complete, the bridge 534, which was folded at 180 degrees, will spread out to form the side wall 533 of the storage section 532. However, when using the pre-folding device 10 of the present invention, the flat surface 535 formed by the tip of the bridge 534 eliminates the problem of the tip of the bridge 534 pushing out the electrode assembly 510 inside the storage section 532, as has happened in the past. In other words, because the flat surface 535 formed by the tip of the bridge 534 reduces its height from its initial state, and because the tip of the bridge 534 has already undergone plastic deformation, significant deformation does not occur during the main folding process. Therefore, even after the main folding is completed, the laminate sheet 530 that has undergone the preliminary folding of the present invention will not have the bridge 534 disrupt the alignment of the electrode assembly 510.

[0050] Using the pre-folding device 10 of the present invention, a pouch-type battery 500 having the following configuration can be provided. The morphological features of the pouch-type battery 500 according to the present invention can be seen in Figure 4.

[0051] The pouch-type battery 500 includes an electrode assembly 510 and a battery case 520. The battery case 520 has a housing portion 532 for housing the electrode assembly 510 that protrudes from both sides in the thickness direction, and three edges of the housing portion 532, excluding one edge that forms the side wall 533, are sealed by heat fusion. Here, the battery case 520 has a plastically formed flat portion 535 extending along the middle of the side wall 533 of the housing portion 532 (i.e., the side where the laminate sheets are connected without interruption). Such a side wall 533 of the housing portion 532 is the result of the tip of the bridge 534 being plastically flattened, and the flat portion 535 in the center of the bridge 534 maintains good alignment of the electrode assembly 510 and also improves the appearance quality.

[0052] Returning to Figure 2, the other configurations of the first embodiment will be described in detail as follows.

[0053] In the first embodiment, the pusher 400 is composed of a roller 410 that moves along the longitudinal direction of the pusher support 300 by the drive of the roller running section 412. The roller 410 has a rotation axis and can rotate (spin on its own axis), and the roller 410 that presses against the tip of the bridge 534 rotates along the direction (left-right direction in the drawing) across the column 110 by the drive of the roller running section 412. As a result, the roller 410, which is the pusher 400, plastically deforms the tip of the bridge 534 over its entire area.

[0054] The system may also further include a roller drive unit 414 that autonomously rotates the roller 410. The roller drive unit 414, connected to the rotation axis of the roller 410, rotates the roller 410 by power, and the powered-rotating roller 410 can press the tip of the bridge 534 more uniformly without being affected by external conditions (e.g., surface roughness or frictional force fluctuations).

[0055] The linear drive unit 310 may stop its downward movement when the load of the power supply applied during the downward movement of the pusher support unit 300 reaches a reference value. Of course, such control may be performed by a controller (not shown). The lower limit of the downward movement of the pusher support unit 300, in other words, the upper limit of the pressure that the pusher 400 exerts on the tip of the bridge 534, can be measured and controlled via various sensors. For example, if a strong load is applied to the linear drive unit 310 when the pusher support unit 300 is descending, it certainly means that the pusher 400 and the forming projection 210 are in contact and applying pressure without substantial movement of position, so the power supply applied to the linear drive unit 310 can be monitored to set a lower limit of its operation.

[0056] On the other hand, Figure 5 illustrates a pre-folding device 10 according to a second embodiment of the present invention.

[0057] In the second embodiment shown in Figure 5, the difference from the first embodiment described above is that the pusher 400 is a bar-shaped pusher 420 having a length corresponding to the length of the forming projection 210. That is, while the pusher 400 in the first embodiment is a roller 410, the pusher 400 in the second embodiment is a bar-shaped pusher 420 having a long bar shape.

[0058] If the pusher 400 is configured as a long bar-shaped pusher 420 corresponding to the length of the forming projection 210, the advantage arises that the configuration of the roller running section 412 and the roller driving section 414 included in the first embodiment becomes unnecessary. In other words, the configuration of the pre-folding device 10 becomes simpler, and the control content is also simplified as a result.

[0059] However, since a single downward movement of the bar-shaped pusher 420 must create a completely flat section 535 on the bridge 534, there may be some disadvantages in terms of the plastically deformed side of the bridge 534.

[0060] Taking this into consideration, the bar-shaped pusher 420 can also be configured such that its width is wider than the upper end width of the forming projection 210, and the material of the bar-shaped pusher 420 is harder than the laminate sheet 530 but more brittle than the forming projection 210.

[0061] Furthermore, if necessary, a heating means 430 for heating the bar-shaped pusher 420 may be provided. Raising the temperature of the bar-shaped pusher 420 can improve the moldability of the laminate sheet 530.

[0062] However, a hot bar-shaped pusher 420 may melt the thermoplastic resin that forms the internal insulating layer of the laminate sheet 530. Therefore, it is preferable for the heating means 430 to heat the bar-shaped pusher 420 to a temperature range below the melting point of the internal insulating layer of the laminate sheet 530.

[0063] For example, the laminate sheet 530 may have a three-layer structure including an aluminum thin film layer, a first resin layer formed on the inside facing the electrode assembly 510 relative to the aluminum thin film layer, and a second resin layer formed on the outside relative to the aluminum thin film layer (not shown). The first resin layer may be made of polypropylene (PP) resin as a thermoplastic resin forming the internal insulating layer, and the second resin layer may be polyethylene terephthalate (PET) resin. The first resin layer made of polypropylene has an even lower melting point than the second resin layer for tight bonding of the laminate sheet 530. For example, the melting point of polypropylene (PP) resin is about 170°C, which is about 100°C lower than that of polyethylene terephthalate (PET) resin.

[0064] Thus, if the internal insulating layer of the laminate sheet 530 is made of polypropylene (PP) resin, it is preferable that the heating means 430 heats the bar-shaped pusher 420 at a temperature lower than the melting point of polypropylene (PP) resin, which is 170°C, for example, in the range of 100 to 140°C.

[0065] Here, the heating means 430 has been described as being provided in the bar-shaped pusher 420 of the second embodiment, but the heating means 430 could also be provided in the roller 410, which is the pusher 400 of the first embodiment. Therefore, the above description of the heating means 430 should be understood as meaning that it is more useful for the heating means 430 to be provided in the bar-shaped pusher 420 of the second embodiment.

[0066] The present invention has been described in more detail above through the drawings and embodiments. However, the configurations described in the drawings or embodiments described herein are merely one embodiment of the present invention and do not represent the entire technical concept of the present invention. It should be understood that there are various equivalents and modifications that can be substituted for them at the time of filing this application. [Explanation of symbols]

[0067] 10: Pre-folding device 100: Mainframe 110: Column 120: Horizontal bar 200: Rib 210: Forming protrusion 300: Pusher support part 310: Linear drive part 400: Pusher 410: Roller 412: Roller running section 414: Roller drive section 420: Bar-shaped pusher 430: Heating means 500: Pouch-type battery 510: Electrode assembly 520: Battery case 530: Laminating sheet 532: Storage compartment 533: Side wall 534: Bridge 535: Flat area [Industrial applicability]

[0068] The present invention is useful as a molding apparatus for laminate sheets that form cases for pouch-type secondary batteries.

Claims

1. A main frame including a pair of columns and a horizontal bar connecting the upper parts of the pair of columns, A rib is fixedly installed below the horizontal bar, crossing the pair of columns, and having a flat-ended forming projection at its upper end, A linear drive unit that moves vertically along the pair of columns, and a pusher support unit positioned above the rib, A pusher installed on the pusher support portion and aligned with the forming projection portion, A pre-folding device for pouch-type batteries, including [the specified component].

2. A laminate sheet including a bridge formed to protrude between two concave storage sections that house an electrode assembly is inserted such that the bridge fits into the forming protrusion. The pre-folding device for a pouch-type battery according to claim 1, wherein the downward movement of the pusher support portion causes the pusher to press against the tip of the bridge, thereby plastically deforming it into a flat shape.

3. The aforementioned pusher, The pre-folding device for a pouch-type battery according to claim 2, wherein the roller moves along the longitudinal direction of the pusher support by driving the roller running section.

4. The pre-folding device for a pouch-type battery according to claim 3, wherein the roller travels on the forming projection by the drive of the roller travel section.

5. The pre-folding device for a pouch-type battery according to claim 4, further comprising a roller drive unit connected to the rotation axis of the roller and for rotating the roller.

6. The aforementioned pusher, The pre-folding device for a pouch-type battery according to claim 2, wherein the bar-shaped pusher has a length corresponding to the length of the forming projection.

7. The pre-folding device for a pouch-type battery according to claim 2, wherein the width of the pusher is wider than the width of the upper end of the forming projection.

8. The pre-folding device for a pouch-type battery according to claim 2, wherein the linear drive unit stops the downward movement when the power load applied during the downward movement of the pusher support unit reaches a reference value.

9. The pre-folding device for a pouch-type battery according to claim 2, further comprising a heating means for heating the pusher.

10. The pre-folding device for a pouch-type battery according to claim 9, wherein the heating means heats the pusher to a temperature range below the melting point of the thermoplastic resin forming the internal insulating layer of the laminate sheet.

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