Secondary battery and method for manufacturing the same

Abstract

The secondary battery of the present invention includes a case that forms a housing portion for housing an electrode assembly and a sealing portion for sealing the housing portion, formed by joining upper and lower pouches, each having a protective layer, a metal layer, and an insulating layer arranged sequentially from the inside to the outside. The sealing portion includes a sealing region formed by joining the protective layer of the upper pouch and the protective layer of the lower pouch, a temporary attachment region formed by pulling out a portion of the protective layers of the upper and lower pouches located in the sealing region toward the housing portion, and an irregular region located between the temporary attachment region and the housing portion, having an irregular layer formed by a raised portion of the protective layer of the upper pouch or the protective layer of the lower pouch, the surface of which has a horizontal plane.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0089996 filed on July 11, 2023 and Korean Patent Application No. 10-2024-0091253 filed on July 10, 2024, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

[0002] Technical Field The present invention relates to a secondary battery capable of preventing dielectric breakdown of a seal portion of a pouch and a method of manufacturing the secondary battery.

Background Art

[0003] Generally, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged. Such secondary batteries are widely used in the field of advanced electronic devices such as mobile phones, notebook computers, and camcorders.

[0004] Also, the secondary battery is variously classified according to the structure of the electrode assembly. As an example, the secondary battery is classified into a stack type structure, a winding type (jelly roll type) structure, and a stack / folding type structure.

[0005] The secondary battery includes an electrode assembly, an electrolyte, and a case that houses the electrode assembly and the electrolyte. The electrode assembly includes one or more basic units, and the basic units have a structure in which a positive electrode and a negative electrode are alternately arranged with a separator interposed therebetween. Further, the case includes a housing portion that houses the electrode assembly and a seal portion that seals the housing portion.

[0006] On the other hand, as shown in FIG. 1, the case is formed by coupling an upper pouch 21 and a lower pouch 22, and the upper and lower pouches 21 and 22 have a film structure in which a protective layer 23, a metal layer 24, and an insulating layer 25 are arranged from the inside to the outside.

[0007] A method for manufacturing a secondary battery having such a structure includes the steps of preparing an electrode assembly, housing the electrode assembly in a case, sealing the edge of the case to form a seal, and folding the seal of the case with heat and pressure.

[0008] Here, the pouch sealing portion folding process refers to folding the sealing portion 30 of the case so that it overlaps in one or two layers.

[0009] On the other hand, in the seal portion formation process, the seal portion is formed with a seal region that seals the housing portion, a temporary adhesion region 32 formed by a part of the protective layer provided in the seal region being pulled out toward the housing portion, and an irregular region 33 in which an irregular layer 331 is formed by a part of the protective layer protruding.

[0010] However, the manufacturing method of the secondary battery, as shown in Figure 1, has a problem in that when folding the seal portion 30, cracks occur at the boundary line 3213 where the irregular layer 331 of the irregular region 33 and the protruding layer of the temporary bonding region 32 are formed, which causes the metal layer 24 to be exposed to the outside and dielectric breakdown to occur. In particular, there is a problem in that the irregular layer formed in the irregular region causes folding defects in the seal portion. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The present invention aims to provide a secondary battery and a method for manufacturing a secondary battery that can prevent cracking and dielectric breakdown in the temporary bonding region and the irregular region formed in the sealing portion of the pouch by heating and pressurizing the temporary bonding region and the irregular region, and in particular can improve the folding force of the sealing portion by adjusting the irregular layer of the irregular region. [Means for solving the problem]

[0012] The secondary battery of the present invention includes a case that forms a housing portion for housing an electrode assembly and a sealing portion for sealing the housing portion, formed by joining upper and lower pouches, each having a protective layer, a metal layer, and an insulating layer arranged sequentially from the inside to the outside. The sealing portion includes a sealing region formed by joining the protective layer of the upper pouch and the protective layer of the lower pouch, a temporary attachment region formed by pulling out a portion of the protective layers of the upper and lower pouches located in the sealing region toward the housing portion, and an irregular region located between the temporary attachment region and the housing portion, having an irregular layer formed by a raised portion of the protective layer of the upper pouch or the protective layer of the lower pouch. The surface of the irregular layer may have a horizontal plane.

[0013] The horizontal plane may be parallel to the protective layer of the upper pouch or the lower pouch.

[0014] The irregular layer may be raised by 0.01 to 2.0 mm relative to the protective layer of the upper pouch or the protective layer of the lower pouch.

[0015] The boundary between the temporary attachment region and the irregular region may be formed in a curved shape.

[0016] Multiple irregular layers are formed in the irregular region, and these multiple irregular layers may all have the same height.

[0017] On the other hand, the method for manufacturing a secondary battery of the present invention is a step of (a) manufacturing a case including upper and lower pouches having a structure in which a protective layer, a metal layer, and an insulating layer are sequentially arranged from the inside to the outside, and then housing an electrode assembly in a housing portion formed by the upper and lower pouches, and (b) sealing the edges of the upper and lower pouches to form a sealed portion, wherein the sealed portion is formed by a sealed area sealed with heat and pressure, and a part of the protective layer of the upper and lower pouches located in the sealed area is pulled out toward the housing portion. (c) a step of heating the temporary bonding area and the irregular area, which is located between the temporary bonding area and the housing, and which has an irregular layer formed by a part of the protective layer of the upper pouch or the protective layer of the lower pouch being raised; and (c) a step of heating the temporary bonding area and the irregular area at a set temperature for a set time to soften the temporary bonding area and the irregular area, and then pressing the upper and lower pouches located in the irregular area to adjust the irregular layer, wherein in step (c), the surface of the irregular layer may be adjusted to have a horizontal plane.

[0018] After step (c), the method may further include the step of (d) folding the sealing portion to correspond to the side surface of the housing portion, and then pressurizing the sealing portion toward the housing portion.

[0019] In step (c) above, the surface of the irregular layer may be adjusted to be parallel to the protective layer of the upper pouch or the lower pouch.

[0020] In step (c) above, the irregular layer is adjusted to have a set height based on the protective layer of the upper pouch or the protective layer of the lower pouch, and the set height may be 0.01 to 2.0 mm.

[0021] In step (c) above, the set temperature may be 100°C to 160°C, and the set time may be 0.3 seconds to 1.0 seconds.

[0022] In the step (c), the upper pouch and the lower pouch in the temporary attachment region and the irregular region may be heated at different temperatures.

[0023] The upper pouch is heated at 100°C to 140°C, and the lower pouch located below the upper pouch is heated at 120°C to 160°C. The lower pouch may be heated at a temperature higher than that of the upper pouch.

[0024] After the step (c), the plurality of irregular layers formed in the irregular region may all have the same height.

[0025] The step (c) may further include a step of inspecting whether the height of the irregular layer has a preset height value.

[0026] The step (b) may further include a step of folding the seal region so as to overlap.

Advantages of the Invention

[0027] In the secondary battery of the present invention, since the irregular layer in the irregular region formed in the seal portion has a horizontal surface, the seal portion can be folded more stably, and the occurrence of cracks and insulation breakdown between the temporary attachment region and the irregular region of the seal portion can be prevented.

Brief Description of the Drawings

[0028] [Figure 1] It is a cross-sectional view showing a seal portion according to a conventional embodiment. [Figure 2] It is a perspective view showing a secondary battery according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view of FIG. 1. [Figure 4] It is an enlarged view of part A of FIG. 3. [Figure 5] It is a side view showing the folded state of the seal portion shown in FIG. 2. [Figure 6]This flowchart shows a method for manufacturing a secondary battery according to an embodiment of the present invention. [Figure 7] (a) This is a process diagram showing the steps for manufacturing the case and housing the electrode assembly. [Figure 8] (b) This is a process diagram showing the step of forming the seal portion of the case. [Figure 9] This is an enlarged view of section B in Figure 8. [Figure 10] (b) This is a process diagram showing the sealing portion folding step of the case sealing portion formation step. [Figure 11] (c) This is a process diagram showing the heating steps for the temporary bonding area and the irregular area of ​​the seal. [Figure 12] This is an enlarged view of section C shown in Figure 10. [Figure 13] (c) This is a cross-sectional view showing the seal portion after the heating step of the temporary bonding area and irregular area of ​​the seal portion has been completed. [Figure 14] (d) This is a process diagram showing the sealing section folding step. [Figure 15] This is a cross-sectional view showing multiple irregular layers formed in the irregular region of the seal. [Modes for carrying out the invention]

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described below. In the drawings, parts that are not relevant to the description have been omitted in order to clearly illustrate the present invention, and similar parts throughout the specification are denoted by similar reference numerals.

[0030] [Secondary battery according to an embodiment of the present invention] Figure 2 is a perspective view showing a secondary battery according to an embodiment of the present invention, Figure 3 is a cross-sectional view of Figure 1, and Figure 4 is an enlarged view of part A in Figure 3.

[0031] As shown in Figures 2 to 4, the secondary battery 1 according to an embodiment of the present invention includes an electrode assembly 11 and a case 12 that houses the electrode assembly 11.

[0032] electrode assembly The electrode assembly 11 has a structure in which electrodes and a separator membrane are arranged alternately, and the electrodes include a positive electrode and a negative electrode. That is, the electrode assembly 11 has a structure in which positive electrodes and negative electrodes are arranged alternately with a separator membrane interposed between them.

[0033] case The case 12 includes a housing portion 121 in which the electrode assembly 11 is housed, and a sealing portion 122 formed along the edge of the housing portion 121 to seal the housing portion 121.

[0034] On the other hand, case 12, as shown in Figure 2, is manufactured by assembling an upper pouch 13 and a lower pouch 14. That is, the upper pouch 13 includes an upper receiving recess 131 and an upper edge 132, and the lower pouch 14 includes a lower receiving recess 141 and a lower edge 142.

[0035] In a case 12 having such a structure, when the upper pouch 13 and the lower pouch 14 are arranged in correspondence, the upper receiving recess 131 and the lower receiving recess 141 are connected to form a receiving section 121, and the upper edge 132 and the lower edge 142 are sealed to form a sealing section 122. However, it is not limited to this, and it is also possible for the receiving recess to be formed in only one of the upper pouch 13 or the lower pouch 14.

[0036] Here, the upper pouch and the lower pouch consist of a pouch film in which a protective layer 12a, a metal layer 12b, and an insulating layer 12c are sequentially arranged from the inside to the outside of the case 12.

[0037] In other words, a protective layer 12a is located on the inner surface of the case 12, an insulating layer 12c is located on the outer surface, and a metal layer 12b is located in between.

[0038] On the other hand, the protective layer 12a is made of polypropylene. The metal layer 12b is made of aluminum. The insulating layer 12c is made of epoxy resin, fluororesin, and polyimide resin.

[0039] On the other hand, the sealing portion 122 of case 12, as shown in Figure 4, includes a sealing region 1221, a temporary adhesion region 1222, and an irregular region 1223.

[0040] The sealing region 1221 is formed by pressing the edge of the housing portion 121 with heat and pressure. The temporary sealing region 1222 may be formed by a portion of the protective layer of the upper and lower pouches located in the sealing region being pulled towards the housing portion 121. The irregular region 1223 is located between the temporary sealing region 1222 and the housing portion 121 and has an irregular layer 12231 formed by a portion of the protective layer of the upper pouch or the protective layer of the lower pouch rising or by a portion of the protective layer of the temporary sealing region flowing in.

[0041] Here, a boundary line 12223, which is a folded portion, is formed between the irregular layer and the protective layer or between the temporary bonding region and the irregular region (see Figure 9).

[0042] Figure 5 is a side view showing the folded state of the seal portion shown in Figure 2.

[0043] On the other hand, as shown in Figure 5, the sealing portion 122 is folded in an overlapping manner to minimize the length of the sealing portion. For example, the sealing portion 122 may be primarily folded so that its length in the left-right direction in Figure 5 is halved, and then secondarily folded vertically to correspond to the side of the housing portion 121. In summary, the sealing portion 122 may be folded toward the housing portion 121, thereby being positioned on the side of the housing portion 121 or being in close contact and joined to it.

[0044] In this embodiment of the present invention, the secondary battery 1 has a flat horizontal surface 12231 on the surface of the irregular layer 12231 formed in the irregular region 1223 (the upper surface of the irregular layer in Figure 4). That is, in the secondary battery 1 according to the embodiment of the present invention, the irregular layer 12231 formed in the irregular region 1223 is flattened by pressing the irregular region 1223 with heat and pressure, thereby forming the surface of the irregular layer 12231 as a horizontal surface 122311. This makes it possible to reduce the thickness of the seal portion when folding the seal portion on which the irregular layer is formed, and thus increase the folding force of the seal portion.

[0045] In particular, when heat is applied to the secondary battery 1 according to the embodiment of the present invention by contact or non-contact, the irregular layer 12231 and the boundary line 12223 between the temporary bonding region 1222 and the irregular region 1223 can be softened, thereby preventing cracks from occurring at the boundary line 12223 when the seal portion 122 is folded. In particular, when the irregular region 1223 is crimped, a portion of the irregular layer 12231 flows into the boundary line 12223 side, thereby deforming the boundary line 12223 into a substantially curved shape, which can significantly prevent dielectric breakdown.

[0046] In other words, cracks and dielectric breakdown occur at the boundary line 12223, but by heating and pressing the seal portion 122 on which the irregular layer 12231 is formed, the boundary line 12223 can be removed, and as a result, cracks and dielectric breakdown can be prevented.

[0047] In summary, the secondary battery according to the present invention has a structure in which the irregular layer 12231 is reduced and there is no folded boundary line 12223 between the temporary bonding region 1222 and the irregular region 1223. In particular, the surface of the irregular layer 12231 has a horizontal surface. This prevents cracking and dielectric breakdown when the seal portion 122 is folded.

[0048] In particular, in the present invention, the irregular region 1223 on which the irregular layer 12231 is formed has a preset height, which may be 1.2 to 2.0 times the thickness of the sealing region 1221. On the other hand, the irregular region 1223 may have a height that is raised by 0.01 to 2.0 mm relative to the protective layer of the upper pouch or the protective layer of the lower pouch.

[0049] On the other hand, the irregular layer 12231 may be formed in multiple locations within the irregular region, and the multiple irregular layers have the same height and horizontal plane as a whole.

[0050] Therefore, the secondary battery 1 according to the embodiment of the present invention can prevent cracks from occurring in the temporary bonding region 1222 and the irregular region 1223 even when the sealing portion 122 of the case 12 is folded, and as a result, dielectric breakdown can be prevented.

[0051] The following describes a manufacturing method for producing a secondary battery according to an embodiment of the present invention.

[0052] [Method for manufacturing a secondary battery according to an embodiment of the present invention] Figure 6 is a flowchart showing a method for manufacturing a secondary battery according to an embodiment of the present invention; Figure 7 is a process diagram showing (a) the pouch manufacturing and electrode assembly housing step; Figure 8 is a process diagram showing (b) the pouch seal portion formation step; Figure 9 is an enlarged view of part B in Figure 8; Figure 10 is a process diagram showing the seal portion folding step of the pouch seal portion formation step (b); Figure 11 is a process diagram showing the heating step of the temporary bonding region and irregular region of the seal portion (c); Figure 12 is an enlarged view of part C in Figure 10; Figure 13 is a cross-sectional view showing the seal portion after the heating step of the temporary bonding region and irregular region of the seal portion has been completed (c); and Figure 14 is a process diagram showing the sealing portion folding step (d).

[0053] A method for manufacturing a secondary battery according to an embodiment of the present invention, as shown in Figure 6, includes (a) a step of manufacturing a pouch and housing an electrode assembly, (b) a step of forming a seal portion of the pouch, (c) a step of heating the temporary bonding area and irregular area of ​​the seal portion, and (d) a step of folding the seal portion.

[0054] (a) Pouch manufacturing and electrode assembly housing step (a) In the pouch manufacturing and electrode assembly housing step, a case 12 including an upper pouch 13 and a lower pouch 14 is manufactured, as shown in Figure 7. The case 12 thus manufactured, referring to Figure 3, comprises a housing section 121 for housing the electrode assembly 11 and a sealing section 122 for sealing the housing section 121.

[0055] In other words, the pouch manufacturing method involves preparing upper and lower pouch films in which a protective layer 12a, a metal layer 12b, and an insulating layer 12c are alternately laminated. Next, corresponding receiving recesses are formed in the upper pouch film and the lower pouch film to manufacture the upper pouch 13 and the lower pouch 14. Then, the upper and lower pouches are placed vertically to manufacture a case. At this time, the upper receiving recess of the upper pouch 13 and the lower receiving recess of the lower pouch 14 are connected to form a receiving section 121, and the upper edge of the upper pouch 13 and the lower edge of the lower pouch 14 are connected to form a sealing section 122.

[0056] Once the case 12 is manufactured in this manner, the electrode assembly 11 is housed in the housing section 121 of the case 12.

[0057] On the other hand, as shown in Figure 4, the protective layer 12a, the metal layer 12b, and the insulating layer 12c are arranged sequentially from the inside to the outside of the case 12. That is, the protective layer 12a is located on the inner surface of the case 12, the insulating layer 12c is located on the outside, and the metal layer 12b is located in between.

[0058] (b) Step of forming the seal portion of the pouch (b) In the pouch seal formation step, as shown in Figure 8, the edges of the case 12 are pressed together with heat and pressure to form a seal portion 122. Here, the seal portion 122 includes a seal area 1221 that seals the housing portion 121 by pressing with heat and pressure, a temporary attachment area 1222 formed by a part of the protective layer 12a located in the seal area 1221 being pulled out and protruding toward the housing portion, and an irregular area 1223 located between the temporary attachment area 1222 and the housing portion 121, having an irregular layer 12231 formed by a part of the protective layer of the upper pouch or the protective layer of the lower pouch being raised or by the protective layer of the temporary attachment area flowing in.

[0059] Here, the temporary adhesion region 1222 refers to the region formed by the inflow of the protective layer 12a of the seal region 1221, as shown in Figure 9. In this region, the protective layer that flows into the temporary adhesion region 1222 irregularly protrudes, thereby forming the protruding layer 12221.

[0060] Furthermore, the irregular region 1223 is formed when a portion of the protective layer of the upper pouch or the protective layer of the lower pouch bulges, or when the protective layer of the temporary adhesion region flows in.

[0061] Here, the irregular layer 12231 may have a convex shape or an irregularly protruding shape. However, the irregular layer 12231 increases the thickness of the seal portion 122, which may cause folding defects when the seal portion 122 is folded. In particular, a portion with a nearly folded shape may occur at the boundary line 12223 between the irregular region 1223 and the temporary bonding region 1222, and a crack may occur in this portion, exposing the metal layer to the inside of the housing, which may cause dielectric breakdown.

[0062] On the other hand, (b) the pouch seal portion formation step further includes a seal region folding step, as shown in Figure 10, in which the seal region 1221 of the seal portion 122 is folded so that it overlaps in half. That is, in the seal region folding step, the seal region is folded so that it overlaps in half, and then joined by pressing with heat and pressure. In the seal portion formation step, the seal region 1221 of the seal portion 122 can be folded.

[0063] On the other hand, the seal region 1221 may be folded after the temporary bonding region and irregular region heating steps, rather than during the seal formation step.

[0064] The method for manufacturing a secondary battery of the present invention includes (c) a heating step of the temporary bonded region and the disordered region in order to prevent cracking and dielectric breakdown.

[0065] In other words, in the temporary bonding region and irregular region heating step, heating the temporary bonding region 1222 and the irregular region 1223 softens the irregular layer and protective layer contained in the temporary bonding region and the irregular region. As a result, it is possible to prevent cracks and dielectric breakdown from occurring at the boundary between the irregular layer and the protective layer when the seal portion is folded.

[0066] In summary, (c) In the heating step of the temporary bonding region and the irregular region, the hardened irregular layer and the protective layer are softened, thereby preventing cracks from forming between the irregular layer and the protective layer even when the seal portion 122 is folded, and as a result, dielectric breakdown can be prevented.

[0067] The following describes in more detail the (c) heating steps for the temporary deposition region and the disordered region, with reference to the attached drawings.

[0068] (c) Heating step of the temporary deposit area and irregular area (c) In the heating step of the temporary bonding region and the irregular region, as shown in Figures 11 to 13, the temporary bonding region 1222 and the irregular region 1223 are heated using the heater 17 at a predetermined temperature and time. This softens the irregular layer and protective layer contained in the temporary bonding region 1222 and the irregular region 1223. As a result, even if the temporary bonding region 1222 and the irregular region 1223 are bent, the irregular layer and protective layer are softened, preventing the occurrence of cracks.

[0069] Here, the preset temperature may be between 100°C and 160°C. That is, if the temporary bonding region 1222 and the disordered region 1223 are heated at a temperature of 100°C or lower, the temperature transferred to the disordered layer will be low (below 100°C), which presents a problem as it will not be possible to effectively soften the disordered layer. Also, if the temporary bonding region 1222 and the disordered region 1223 are heated at a temperature of 160°C or higher, unintended deformation may occur in the disordered layer due to the high temperature.

[0070] The preset time may be between 0.3 seconds and 1.0 second. In other words, if the temporary deposition region 1222 and the disordered region 1223 are heated for 0.3 seconds or less, there is a problem that the disordered layer located in the disordered region 1223 cannot be sufficiently heated. Also, if the temporary deposition region 1222 and the disordered region 1223 are heated for 1.0 second or more, the disordered layer can be sufficiently softened, but there is a problem that unnecessary energy is consumed.

[0071] On the other hand, (c) the heating step of the temporary bonding region and the disordered region may further include a step of adjusting the height (thickness) of the disordered layer 12231 of the disordered region 1223 by pressing both surfaces of the heated disordered region 1223 using the pressure block 18, as shown in Figure 12.

[0072] In other words, as shown in Figure 12, the irregular region thickness adjustment process involves pressing both surfaces of the heated irregular region 1223 with the pressure block 18. This presses and compresses the irregular layer, thereby adjusting its height (thickness). Specifically, the irregular layer can be adjusted to have a set height relative to the protective layer of the upper pouch or the protective layer of the lower pouch.

[0073] More specifically, when pressure is applied to both surfaces of the heated irregular region 1223, the irregular layer becomes thinner due to the pressure, while a portion of the irregular layer flows into the protective layers of the upper and lower pouches, increasing the thickness of the protective layers of the upper and lower pouches. This has the effect of increasing the thickness between the irregular layer and the protective layers of the upper and lower pouches, thereby preventing the occurrence of cracks and dielectric breakdown.

[0074] Therefore, the irregular region thickness adjustment step can adjust the thickness of the entire irregular layer in the irregular region 1223 to be uniform, preferably so that the entire irregular protective layer has the same thickness.

[0075] On the other hand, the set height may be 0.01 to 2.0 mm. Here, the set height may vary depending on the pressure acting on the irregular region.

[0076] On the other hand, the surface of the irregular layer 12231 is adjusted to have a horizontal surface. This is because the irregular layer is also pressed together when the upper and lower pouches are pressed, causing the surface of the irregular layer 12231 to change to a horizontal surface. This minimizes the thickness of the secondary battery when the seal portion 122, which will be described later, is folded.

[0077] In particular, the surface of the irregular layer 12231 is adjusted to be parallel to the protective layer of the upper pouch or the lower pouch.

[0078] On the other hand, the upper and lower surfaces of the temporary bonding region 1222 and the irregular region 1223 are heated at different temperatures. That is, because the thickness of the protective layer on the upper and lower parts of the temporary bonding region 1222 and the irregular region 1223 is different, the upper and lower surfaces of the temporary bonding region 1222 and the irregular region 1223 are heated at different temperatures. This allows the protective layer of the entire temporary bonding region 1222 and the irregular region 1223 to be stably softened.

[0079] For example, the upper surface is heated to 100°C to 140°C, and the lower surface is heated to 120°C to 160°C, with the lower surface being heated to a higher temperature than the upper surface. This is because a thick, irregular protective layer is formed on the lower surface of the temporary bonding region 1222, requiring the lower surface to be heated to a higher temperature than the upper surface.

[0080] On the other hand, the temporary bonding region 1222 and the irregular region 1223 are heated in a non-contact manner using an infrared lamp in the heater 17. This allows the irregular layer to be heated stably without damaging the temporary bonding region 1222 and the irregular region 1223. Of course, the temporary bonding region 1222 and the irregular region 1223 can also be heated in a contact manner using the heater.

[0081] (c) The temporary bonding region heating step may further include adjusting the thickness of the irregular protective layer in the temporary bonding region and then checking whether the thickness of the irregular layer in the temporary bonding region 1222 has a predetermined thickness value.

[0082] In other words, the inspection process involves using an infrared camera 16 to fluoroscopically photograph an irregular region 1223 with an adjusted irregular layer thickness, and then measuring the thickness of the irregular layer in the fluoroscopically photographed image to obtain a measurement value. Next, the measurement value is compared with a preset thickness value, and if the measurement value falls within the preset thickness value, it is determined to be normal; if it falls outside, it is determined to be defective.

[0083] Here, the pre-set thickness value may vary depending on the material, size, and application product of the pouch.

[0084] On the other hand, as shown in Figure 15, when multiple irregular layers are formed in an irregular region, after step (c), the multiple irregular layers formed in the irregular region have the same height overall. That is, the multiple irregular layers have regular heights and horizontal surfaces, which can increase the folding force of the seal portion.

[0085] (d) Seal section folding step (d) In the sealing portion folding step, referring to Figure 14, the irregular layer of the irregular region 1223 is folded so as to correspond to the side surface of the housing portion 121, and then the sealing portion 122 is pressed toward the housing portion 121. On the other hand, the sealing portion 122 may be positioned on the side of the housing portion 121 or it may be bonded to it.

[0086] Alternatively, protective tape 15 may be applied so as to surround the seal portion 122.

[0087] Once the above steps are completed, a finished secondary battery 1 can be manufactured.

[0088] The scope of the present invention is shown by the appended claims rather than by the above detailed description, and various embodiments are possible derived from the meaning and scope of the claims and the concept of equivalents thereof. [Explanation of Symbols]

[0089] 1 Secondary battery 11 Electrode assembly 12 cases 13 Top pouch 14. Bottom pouch 12a protective layer 12b Metal layer 12c insulating layer 121 Storage Unit 122 Seal part 1221 Seal area 1222 Temporary Attachment Area 12221 Projection layer 1223 Irregular area 12231 Irregular layer 122311 Horizontal plane 12223 Boundary Line 13 Top pouch 131 Upper recess 132 Upper edge 14. Bottom pouch 141 Lower housing recess 142 Lower edge 15 Protective tape 16 Infrared Cameras 17 Heater 18 Pressure Block

Claims

1. The case includes an upper and lower pouch, each having a protective layer, a metal layer, and an insulating layer arranged sequentially from the inside to the outside, which are joined together to form a housing section for housing an electrode assembly, and a sealing section for sealing the housing section. The aforementioned sealing portion is A sealing region formed by the bonding of the protective layer of the upper pouch and the protective layer of the lower pouch, A temporary adhesion region is formed when a portion of the protective layer of the upper and lower pouch located in the sealing region is pulled out toward the housing portion, It includes an irregular region located between the temporary attachment region and the housing portion, having an irregular layer formed by a part of the protective layer of the upper pouch or the protective layer of the lower pouch being raised, The surface of the aforementioned disordered layer has a horizontal plane, a secondary battery.

2. The secondary battery according to claim 1, wherein the horizontal plane is parallel to the protective layer of the upper pouch or the lower pouch.

3. The secondary battery according to claim 1, wherein the irregular layer is raised by 0.01 to 2.0 mm relative to the protective layer of the upper pouch or the protective layer of the lower pouch.

4. The secondary battery according to claim 1, wherein the boundary between the temporary bonding region and the irregular region is formed in a curved shape.

5. Multiple irregular layers are formed in the irregular region, The secondary battery according to any one of claims 1 to 4, wherein the plurality of irregular layers have the same height overall.

6. (a) A step of manufacturing a case including upper and lower pouches having a structure in which a protective layer, a metal layer, and an insulating layer are arranged sequentially from the inside to the outside, and then housing an electrode assembly in the housing formed by the upper and lower pouches, (b) A step of sealing the edges of the upper and lower pouches to form a sealed portion, wherein the sealed portion includes a sealed area sealed by heat and pressure, a temporary area formed by a portion of the protective layer of the upper and lower pouches located in the sealed area being pulled out toward the housing, and an irregular area located between the temporary area and the housing, having an irregular layer formed by a portion of the protective layer of the upper pouch or the protective layer of the lower pouch being raised. (c) The process includes heating the temporary bonding region and the irregular region at a set temperature for a set time to soften the temporary bonding region and the irregular region, and then pressing the upper and lower pouches located in the irregular region to adjust the irregular layer. A method for manufacturing a secondary battery, wherein in step (c), the surface of the irregular layer is adjusted to have a horizontal plane.

7. The method for manufacturing a secondary battery according to claim 6, further comprising the step of (d) after step (c) above, folding the seal portion to correspond to the side surface of the housing portion, and then pressurizing the seal portion toward the housing portion.

8. The method for manufacturing a secondary battery according to claim 6, wherein in step (c), the surface of the irregular layer is adjusted to be parallel to the protective layer of the upper pouch or the lower pouch.

9. In step (c) above, the irregular layer is adjusted to have a set height based on the protective layer of the upper pouch or the protective layer of the lower pouch, The method for manufacturing a secondary battery according to claim 6, wherein the set height is 0.01 to 2.0 mm.

10. The method for manufacturing a secondary battery according to claim 6, wherein in step (c), the set temperature is 100°C to 160°C and the set time is 0.3 seconds to 1.0 second.

11. The method for manufacturing a secondary battery according to claim 6, wherein in step (c), the upper pouch and the lower pouch of the temporary bonding region and the irregular region are heated at different temperatures.

12. The method for manufacturing a secondary battery according to claim 11, wherein the upper pouch is heated to 100°C to 140°C, the lower pouch located below the upper pouch is heated to 120°C to 160°C, and the lower pouch is heated to a higher temperature than the upper pouch.

13. The method for manufacturing a secondary battery according to claim 6, wherein, after step (c), the plurality of irregular layers formed in the irregular region have the same height overall.

14. The method for manufacturing a secondary battery according to claim 6, wherein step (c) further includes a step of checking whether the height of the irregular layer has a predetermined height value.

15. The method for manufacturing a secondary battery according to any one of claims 6 to 14, wherein step (b) further comprises folding the sealing regions so that they overlap.

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