Pouch sheet, pouch-type battery case, and method for manufacturing battery case

Abstract

The present invention relates to a pouch sheet, a pouch-type battery case, and a method for manufacturing the battery case. The pouch sheet, which is molded into the pouch-type battery case, comprises: a first polymer layer located at the outermost part of one side; a second polymer layer located at the outermost part of the other side; and a metal layer located between the first polymer layer and the second polymer layer, wherein the metal layer is located on one side of a neutral plane of the pouch sheet.

Description

Pouch sheet, pouch-type battery case and battery case manufacturing method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0118632, filed September 6, 2023, and Korean Patent Application No. 10-2024-0121124, filed September 5, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a pouch sheet, a pouch-type battery case, and a method for manufacturing a battery case.

[0005] In recent years, rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution have made the demand for eco-friendly alternative energy sources essential for future living. Research is continuing into various power generation technologies, such as solar, wind, and tidal power. Furthermore, significant interest is being focused on power storage devices, such as batteries, to more efficiently utilize the generated electricity.

[0006] Moreover, with the development of technology and increasing demand for battery-powered electronic mobile devices and battery-powered automobiles, the demand for batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on batteries that can meet various needs.

[0007] Batteries are attracting significant attention as an energy source for a variety of products, including mobile devices and electric vehicles. Secondary batteries, in particular, are an excellent energy source that can replace the use of existing fossil fuel-powered products. They are also gaining recognition as an eco-friendly energy source, as they produce no byproducts from energy use.

[0008] Meanwhile, secondary batteries are also attracting attention as a power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), which are being proposed as solutions to address air pollution issues caused by conventional gasoline and diesel vehicles that use fossil fuels. Specifically, these secondary batteries are utilized in battery packs containing multiple battery modules.

[0009] In the process of manufacturing a pouch battery case for secondary batteries, particularly pouch-type secondary batteries, the cup portion is formed. During this process, the case, particularly the metal layer contained within the case, undergoes stretching. In particular, bending of the metal layer occurs at the corners of the cup portion, and there is a concern that the metal layer may be excessively stretched as it receives additional tensile force due to the bending. This has led to a problem in that the pouch-type case cannot be formed deeper.

[0010] The present invention has been devised to solve the above problems, and a problem to be solved by the present invention is to provide a pouch sheet in which the metal layer is positioned inside the neutral surface of the pouch sheet, thereby preventing excessive elongation of the metal layer and improving formability.

[0011] Another problem to be solved by the present invention is to provide a pouch-type battery case manufactured using the pouch sheet and a manufacturing method thereof.

[0012] A pouch sheet according to an embodiment of the present invention can be formed into a pouch-shaped battery case. The pouch sheet includes a first polymer layer positioned at the outermost side on one side; a second polymer layer positioned at the outermost side on the other side; and a metal layer positioned between the first polymer layer and the second polymer layer, wherein the metal layer can be positioned at one side of a neutral surface of the pouch sheet.

[0013] The second polymer layer may comprise a plurality of layers that are separable from each other.

[0014] The second polymer layer may include a base layer; and a reinforcing layer covering the base layer from the outside and having a thickness thicker than the base layer.

[0015] The first polymer layer, the metal layer, and the base layer are laminated to each other, and the reinforcing layer can be detachably attached to the base layer.

[0016] The neutral surface of the pouch sheet from which the above reinforcing layer has been removed can pass through the above metal layer.

[0017] The thickness of the metal layer may be thicker than the thickness of the second polymer layer.

[0018] A pouch-type case according to an embodiment of the present invention may have a cup portion formed in a recess and a terrace portion positioned around the cup portion. In the pouch-type case, the cup portion and the terrace portion include a first polymer layer positioned at the innermost side; a second polymer layer positioned at the outermost side; and a metal layer positioned between the first polymer layer and the second polymer layer, wherein the metal layer may be positioned inside a neutral surface of the case.

[0019] A method for manufacturing a battery case according to an embodiment of the present invention comprises the steps of preparing a pouch sheet including a first polymer layer positioned at the innermost side, a second polymer layer positioned at the outermost side, and a metal layer positioned between the first polymer layer and the second polymer layer; and the step of forming a cup portion sunken into the pouch sheet, wherein the metal layer may be positioned inside a neutral surface of the pouch sheet.

[0020] The second polymer layer may include a base layer; and a reinforcing layer that covers the base layer from the outside and has a thickness thicker than the base layer.

[0021] The above battery case manufacturing method may further include a step of removing the reinforcing layer after the step of forming the cup portion.

[0022] The step of preparing the above pouch sheet may include the step of preparing a sheet in which the first polymer layer, the metal layer, and the base layer are laminated; and the step of covering the base layer from the outside with the reinforcing layer.

[0023] According to a preferred embodiment of the present invention, the neutral plane of the pouch sheet in the thickness direction may not pass through the metal layer. Therefore, when the pouch sheet is bent, the metal layer is subjected to a compressive force as a whole, which may reduce the elongation of the metal layer. This has the effect of preventing the risk of cracks occurring in the metal layer and improving the formability of the pouch sheet.

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0025] Figure 1 is a perspective view of a pouch sheet according to Example 1 of the present invention.

[0026] Figure 2 is a cross-sectional view of the pouch sheet illustrated in Figure 1.

[0027] Figure 3 is a schematic diagram showing the tensile force received when the pouch sheet illustrated in Figure 2 is formed.

[0028] Fig. 4 is a cross-sectional view of the pouch sheet from which the reinforcing layer of Fig. 2 has been removed.

[0029] FIG. 5 is a perspective view illustrating a pouch-shaped battery case manufactured by molding a pouch sheet according to Example 1 of the present invention.

[0030] FIG. 6 is a schematic diagram showing a state before a pressurizing device used in a battery case manufacturing method according to Example 2 of the present invention presses a pouch sheet.

[0031] FIG. 7 is a schematic diagram showing how a pouch-type battery case is manufactured by pressing a pouch sheet using the pressurizing device illustrated in FIG. 6.

[0032] Figure 8 is a perspective view showing the state of Figure 7.

[0033] Figure 9 is a flowchart of a method for manufacturing a battery case according to Example 2 of the present invention.

[0034] Figure 10 is a flowchart illustrating detailed steps of step S10 in the flowchart of Figure 9.

[0035] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0036] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0037] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0038] Example 1

[0039] Hereinafter, a pouch sheet (10) and a pouch-type battery case (20) according to Example 1 of the present invention will be described in detail with reference to FIGS. 1 to 5.

[0040] FIG. 1 is a perspective view of a pouch sheet according to Example 1 of the present invention, FIG. 2 is a cross-sectional view of the pouch sheet illustrated in FIG. 1, FIG. 3 is a schematic diagram illustrating a tensile force received when the pouch sheet illustrated in FIG. 2 is formed, FIG. 4 is a cross-sectional view of the pouch sheet of FIG. 2 from which the reinforcing layer has been removed, and FIG. 5 is a perspective view illustrating a pouch-shaped battery case manufactured by forming the pouch sheet according to Example 1 of the present invention.

[0041] Referring to FIGS. 1 to 3, a pouch sheet (10) according to the present invention can be formed into a pouch-shaped battery case (20). The pouch sheet (10) according to the present invention can be formed into a multilayer structure. The pouch sheet (10) can include a first polymer layer (11), a second polymer layer (12), and a metal layer (13). In addition, the pouch sheet (10) can further include a nylon layer, etc.

[0042] The first polymer layer (11) may be positioned on the outermost side of the pouch sheet (10). For example, the first polymer layer (11) may include, but is not limited to, a PP (Polypropylene) material. The first polymer layer (11) may be in contact with the metal layer (13).

[0043] The second polymer layer (12) may be positioned on the outermost side of the pouch sheet (10). For example, the second polymer layer (12) may include, but is not limited to, a PET (Polyethylene Terephthalate) material. The second polymer layer (12) may be in contact with the metal layer (13). Alternatively, a stretching auxiliary layer (not shown) may be provided between the second polymer layer (12) and the metal layer (13). For example, the stretching auxiliary layer may include a nylon material.

[0044] The metal layer (13) may be positioned between the first polymer layer (11) and the second polymer layer (12). For example, the metal layer (13) may include aluminum, but is not limited thereto.

[0045] On the cross-section of the pouch sheet (10), some parts in the thickness direction may be subjected to tensile force due to bending, and other parts may be subjected to compressive force due to bending. In addition, on the cross-section of the pouch sheet (10), there may exist a point where neither tensile force nor compressive force is applied, and a virtual plane corresponding to this point may be defined as a neutral plane (14). In other words, the neutral plane (14) may be a virtual plane corresponding to a point where neither tensile force nor compressive force due to bending of the pouch sheet (10) is applied.

[0046] Accordingly, the tensile force or compressive force applied to the cross-section of the pouch sheet (10) due to bending becomes 0 at the neutral plane (14), as shown in FIG. 3, and increases as it moves away from the neutral plane (14) along the thickness direction of the pouch sheet (10).

[0047] This neutral plane (14) may not coincide with the mid-plane passing through the geometric center of the pouch sheet (10) in the thickness direction. This is because the pouch sheet (10) is a composite material including multiple layers having different materials.

[0048] The metal layer (13) may be positioned on one side of the neutral plane (14) of the pouch sheet (10). In other words, the neutral plane (14) of the pouch sheet (10) may not pass through the metal layer (13). More specifically, the metal layer (13) may be positioned on a side that receives a compressive force due to bending, based on the neutral plane (14) of the pouch sheet (10). In addition, the first polymer layer (11) may be positioned on a side that receives a compressive force due to bending, and the second polymer layer (12) may be positioned on a side that receives a tensile force, based on the neutral plane (14).

[0049] In this regard, in the process of forming the cup portion (21) on the pouch sheet (10), the portion forming the edge of the cup portion (21) on the pouch sheet (10) is bent, and the pouch sheet (10) is subjected to tensile force and compressive force due to this bending. As described above, since the metal layer (13) is located on one side of the neutral surface (14) of the pouch sheet (10), a compressive force is applied to the metal layer (13) due to the bending, and the elongation of the metal layer (13) may be reduced.

[0050] This has the advantage of improving the formability of the pouch film (10). Improved formability means that the cup portion (21) can be formed more deeply.

[0051] Meanwhile, the second polymer layer (12) may include a plurality of layers laminated one upon another. The plurality of layers may be detachably attached to one another. More specifically, the plurality of layers may include a base layer (121) and a reinforcing layer (122).

[0052] The reinforcing layer (122) may be positioned on the outside of the base layer (121). The reinforcing layer (122) may be detachably attached to the outside of the base layer (121). The base layer (121) and the reinforcing layer (122) may have the same material. However, this is not limited to this, and the base layer (121) and the reinforcing layer (122) may also have different materials.

[0053] Accordingly, the reinforcing layer (122) may not come into contact with the metal layer (13). The reinforcing layer (122) may protect the base layer (121) and the metal layer (13) from scratches or marks that may occur during the forming process of the pouch sheet (10).

[0054] The first polymer layer (11), the metal layer (13), and the base layer (121) are laminated to each other, and the reinforcing layer (122) can be detachably attached to the base layer (121). Accordingly, the reinforcing layer (122) can be easily removed after the molding of the cup portion (21) is completed. Accordingly, the thickness of the finished battery case (20) can be prevented from increasing due to the reinforcing layer (13), and there is an advantage in that a secondary battery having a high energy density can be manufactured.

[0055] Due to the reinforcing layer (122), the neutral surface (14) of the pouch sheet (10) may not pass through the metal layer (13). On the other hand, as illustrated in FIG. 4, the neutral surface (14') of the pouch sheet (10') from which the reinforcing layer (122) has been removed may pass through the metal layer (13). In this state, when forming a cup portion (21) on the pouch film (10), there is a risk that a portion of the outer side in the thickness direction of the metal layer (13) may be excessively elongated and cracks may occur because it receives tensile force due to bending.

[0056] That is, by the reinforcing layer (122), the position of the neutral surface (14) can be moved to the outside in the thickness direction of the pouch sheet (10). As a result, the elongation of the metal layer (13) can be reduced and the formability of the pouch sheet (10) can be improved.

[0057] The thickness (L2) of the reinforcing layer (122) may be thicker than the thickness (L1) of the base layer (121). As a result, the neutral surface (14) can be moved sufficiently so as not to pass through the metal layer (13).

[0058] The thickness (L2) of the reinforcing layer (122) may have the same effect as the thickness (L3) of the metal layer (13) when the thickness (L3) of the metal layer (13) is 60 µm. For example, when the thickness (L3) of the metal layer (13) is 60 µm, the maximum depth at which the pouch sheet (10) is formed is the same whether the thickness (L2) of the reinforcing layer (122) is 25 µm or 50 µm. Therefore, there is no need to inevitably increase the thickness of the reinforcing layer (122) when the thickness is 60 µm or greater.

[0059] The thickness (L3) of the metal layer (13) may be thicker than the thickness (L1+L2) of the second polymer layer (12).

[0060] Meanwhile, a pouch-shaped battery case (20) according to the present invention can be manufactured by forming a cup portion (21) on a pouch film (10). That is, the pouch-shaped battery case (20) can be manufactured using the same contents as those of the pouch film (10) described above, except for its shape.

[0061] In more detail, the pouch-shaped battery case (20) according to the present invention may have a sunken cup portion (21) and a terrace portion (22) located around the periphery of the cup portion (21).

[0062] The cup portion (21) and the terrace portion (22) may include a first polymer layer (11), a second polymer layer (12), and a metal layer (13). The metal layer (13) may be located inside the neutral surface (14) of the case (20). Here, the inside may mean the side where the cup portion (21) is sunken.

[0063] Example 2

[0064] Hereinafter, a method for manufacturing a battery case according to Example 2 of the present invention will be described in detail with reference to FIGS. 6 to 10.

[0065] FIG. 6 is a schematic diagram showing a state before a pressing device used in a battery case manufacturing method according to Embodiment 2 of the present invention presses a pouch sheet, FIG. 7 is a schematic diagram showing a state in which a pouch-type battery case is manufactured by pressing a pouch sheet by the pressing device shown in FIG. 6, FIG. 8 is a perspective view showing the state of FIG. 7, FIG. 9 is a flowchart of a battery case manufacturing method according to Embodiment 2 of the present invention, and FIG. 10 is a flowchart showing detailed steps of step S10 in the flowchart of FIG. 9.

[0066] The battery case manufacturing method according to the present invention can manufacture a pouch-type battery case (20) using a pressurizing device (30).

[0067] The method for manufacturing a battery case according to the present invention may include a step (S10) of preparing a pouch sheet (10) and a step (S20) of forming a cup portion (21).

[0068] The pouch sheet (10) may include a first polymer layer (11) positioned at the innermost side, a second polymer layer (12) positioned at the outermost side, and a metal layer (13) positioned between the first polymer layer (11) and the second polymer layer (12).

[0069] In the step (S20) of forming the cup portion (21), the pouch sheet (10) can be pressed by the pressurizing device (30) to form the sunken cup portion (21). That is, the pouch sheet (10) can be formed into a pouch-shaped case (20) by the pressurizing device (30).

[0070] The pressurizing device (30) may include a die (31), a stripper (32), and a punch (33). In the step (S10) of preparing a pouch sheet (10), the pouch sheet (10) may be placed between the die (31) and the stripper (32). The pouch sheet (10) may be fixed by the die (31) and the stripper (32).

[0071] In the step (S20) of forming the cup portion (21), the pouch sheet (10) can be formed by the die (31), the stripper (32), and the punch (33). More specifically, the pouch sheet (10) can be fixed by the die (31) and the stripper (32), and the cup portion (21) can be formed by the punch (33). At this time, the punch (33) can be lowered to form the cup portion (21). Alternatively, the punch (33) can be fixed, and the die (31) and the stripper (32) can be raised to form the cup portion (21).

[0072] An edge (211) of the cup portion (21) can be formed at the part where the edge of the punch (33) and the pouch sheet (10) come into contact.

[0073] In the step (S20) of forming the cup portion (21), a tensile force may be applied to the second polymer layer (12) and a compressive force may be applied to the metal layer (13) due to bending occurring at the edge (211) of the cup portion (21).

[0074] The cup portion (21) may have a receiving space in which an electrode assembly is received. In the step (S20) of forming the cup portion (21), elongation mainly occurs in the cup portion (21), and the terrace portion (22) is fixed by the die (31) and the stripper (32) described later, so that the elongation may be relatively small. In particular, the elongation may be relatively large at the edge (211) of the cup portion (21). Therefore, the thickness of the cup portion (21), particularly the thickness of the edge (211), may be relatively thinner than the thickness of the terrace portion (22).

[0075] The step (S10) of preparing a pouch sheet may include a step (S11) of preparing a sheet in which a first polymer layer (11), a metal layer (13), and a base layer (121) are laminated, and a step (S12) of covering the base layer (121) from the outside with a reinforcing layer (122).

[0076] That is, the second polymer layer (12) may include a base layer (121) and a reinforcing layer (122) that covers the base layer (121) from the outside and has a thickness thicker than the base layer (121).

[0077] Since the reinforcing layer (122) cannot be removed when laminated together with the first polymer layer (11), the metal layer (13) and the base layer (121), the reinforcing layer (122) can be detachably attached to the base layer (121).

[0078] The method for manufacturing a battery case according to the present invention may further include a step (S30) of removing a reinforcing layer (122) after the step (S20) of forming a cup portion (21). By removing the reinforcing layer (122), there is an effect of reducing the overall thickness of the pouch-type battery case (20).

[0079] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0080] [Explanation of symbols]

[0081] 10: Pouch sheet 11: First polymer layer

[0082] 12: Second polymer layer 121: Base layer

[0083] 122: Reinforcement layer 13: Metal layer

[0084] 14: Neutral surface 20: Pouch-type battery case

[0085] 21: Cup section 22: Terrace section

[0086] 221: Edge 30 (of the cup): Pressurizing device

[0087] 31: Die 32: Stripper

[0088] 33: Punch

Claims

1. In a pouch sheet formed into a pouch-type battery case, A first polymer layer located at the outermost side; a second polymer layer located at the outermost side; and A metal layer positioned between the first polymer layer and the second polymer layer, The above metal layer is a pouch sheet located on one side of the neutral surface of the pouch sheet.

2. In paragraph 1, The second polymer layer is a pouch sheet comprising a plurality of layers that are separable from each other.

3. In paragraph 1, The second polymer layer, base layer; and A pouch sheet covering the base layer from the outside and including a reinforcing layer having a thickness thicker than the base layer.

4. In paragraph 3, The first polymer layer, the metal layer and the base layer are laminated to each other, The above reinforcing layer is a pouch sheet detachably attached to the base layer.

5. In paragraph 3, The neutral surface of the pouch sheet from which the above reinforcing layer has been removed is the pouch sheet passing through the metal layer.

6. In paragraph 1, A pouch sheet having a thickness of the metal layer that is thicker than the thickness of the second polymer layer.

7. In a pouch-shaped case having a sunken cup portion and a terrace portion located around the cup portion, The above cup portion and the above terrace portion, A first polymer layer located at the innermost side; a second polymer layer positioned at the outermost side; and A metal layer positioned between the first polymer layer and the second polymer layer, A pouch-shaped battery case in which the metal layer is located inside the neutral surface of the case.

8. A step of preparing a pouch sheet including a first polymer layer positioned at the innermost side, a second polymer layer positioned at the outermost side, and a metal layer positioned between the first polymer layer and the second polymer layer; and Including a step of forming a cup portion sunken into the above pouch sheet, A method for manufacturing a battery case, wherein the metal layer is located inside the neutral surface of the pouch sheet.

9. In paragraph 8, The second polymer layer, base layer; and A method for manufacturing a battery case, comprising a reinforcing layer covering the base layer from the outside and having a thickness thicker than the base layer.

10. In paragraph 9, A method for manufacturing a battery case, further comprising a step of removing the reinforcing layer after the step of forming the cup portion.

11. In paragraph 9, The steps for preparing the above pouch sheet are: A step of preparing a sheet in which the first polymer layer, the metal layer, and the base layer are laminated; and A method for manufacturing a battery case, comprising a step of covering the base layer from the outside by the reinforcing layer.

Images