Pouch-type battery case and pouch-type secondary battery

Abstract

To provide a pouch-type battery case and a pouch-type secondary battery, and more particularly to provide a pouch-type battery case and a pouch-type secondary battery that can increase the energy density relative to volume, have a beautiful appearance, and improve marketability.SOLUTION: A pouch-type battery case according to an embodiment of the present invention includes a cup portion that houses an electrode assembly formed by stacking electrodes and separators, the cup portion includes a plurality of die edges that connect a plurality of outer walls surrounding the periphery and a side or a gas vent portion, at least one of which is rounded with a curvature radius of 1 mm or less, and the depth of the cup portion is 6.5 mm or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0104228 filed on August 19, 2020, and Korean Patent Application No. 10-2021-0074472 filed on June 8, 2021, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery case and a pouch-type secondary battery, and more particularly to a pouch-type battery case and a pouch-type secondary battery that can increase the energy density per volume, have a beautiful appearance, and improve marketability. [Background technology]

[0003] Common types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These secondary batteries are used not only in small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in large products that require high output, such as electric vehicles and hybrid vehicles, as well as in power storage devices that store surplus generated power and renewable energy, and as backup power storage devices.

[0004] To manufacture such a secondary battery, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to form a positive electrode and a negative electrode, which are then stacked on both sides of a separator to form an electrode assembly of a predetermined shape, which is then housed in a battery case, filled with an electrolyte, and sealed.

[0005] Secondary batteries are classified into pouch types and can types depending on the material of the case that houses the electrode assembly. Pouch types house the electrode assembly in a pouch made of a flexible polymer material, while can types house the electrode assembly in a case made of metal or plastic.

[0006] The pouch, which is the case of a pouch-type secondary battery, is manufactured by pressing a flexible pouch film to form a cup portion. Once the cup portion is formed, an electrode assembly is placed in the receiving space of the cup portion and the sides are sealed to manufacture the secondary battery.

[0007] Drawing during press processing involves inserting a pouch film into a forming device such as a press and applying pressure to the pouch film with a punch to stretch it. However, when forming a cup portion in the pouch film, there are limitations to improving the radius of curvature and clearance of the cup edge. Furthermore, the volume ratio of the electrode assembly to the cup volume is small, and there is also a limit to reducing the size of the bat ears, resulting in a decrease in the volume-specific energy density of the secondary battery. Furthermore, there are limitations to achieving a sharp overall shape, resulting in a poor appearance and reduced marketability of the secondary battery. Prior art documents include Japanese Patent Registration No. 6022956. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a pouch-type battery case and a pouch-type secondary battery that can increase the energy density per volume, have a beautiful appearance, and improve marketability.

[0009] The objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned above will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0010] In order to solve the above problems, a pouch-type battery case according to an embodiment of the present invention has a cup portion formed therein to accommodate an electrode assembly formed by stacking electrodes and separators, the cup portion including a plurality of die edges connecting a plurality of outer walls surrounding the periphery and a side or gas vent portion, at least one of which is rounded with a curvature radius of 1 mm or less, and the depth of the cup portion is 6.5 mm or less.

[0011] At least one of the die edges may be rounded with a radius of curvature of 0.7 mm or less. The radius of curvature of the die edge may be 1 / 20 to 1 / 6 of the depth of the cup portion.

[0012] The cup portion may further include a plurality of punch edges that respectively connect the outer wall and the bottom, at least one of which is rounded with a curvature radius of 1 mm or less, and a thickness edge that connects two adjacent outer walls to each other.

[0013] Furthermore, the vertical distance between a die edge vertical line that passes through the boundary point between the die edge and the outer wall on the die edge side and is perpendicular to the bottom, and an edge vertical line that passes through the boundary point between the punch edge on the die edge side and the outer wall on the die edge side and is perpendicular to the bottom, may be 0.5 mm or less.

[0014] In addition, the thickness edge may be connected to two adjacent punch edges to form corners, and at least one of the corners may be rounded with a radius of curvature of 2 mm to 5 mm, and the radius of curvature may be larger than the radius of curvature of the thickness edge.

[0015] Also, within the corner, the radius of curvature can vary. The corner may have a larger radius of curvature at the center than at the periphery.

[0016] At least one of the punch edges may be rounded with a radius of curvature of 0.7 mm or less. The radius of curvature of the punch edge may be 1 / 20 to 1 / 6 of the depth of the cup portion.

[0017] The device may also include a first case and a second case each having a cup portion formed therein, and a bridge formed between the two cup portions, the bridge having a thickness of 2 mm or less.

[0018] The bridge may have a thickness of 1.4 mm or less. The bridge may have a thickness of 1 / 200 to 1 / 30 of the width of the electrode assembly.

[0019] The bridge may be rounded with a radius of curvature of 1 mm or less, or may be rounded with a radius of curvature of 0.7 mm or less.

[0020] The thickness of the bridge may also be the distance between two bridge perpendicular lines that pass through the boundary points of the bridge and the outer wall on the bridge side and are perpendicular to the bottom. The outer wall may have an inclination angle of 90° to 95° from the bottom.

[0021] In order to solve the above problems, a pouch-type secondary battery according to an embodiment of the present invention includes an electrode assembly formed by stacking electrodes and separators, and a pouch-type battery case having a cup portion formed therein for accommodating the electrode assembly, wherein the battery case includes a first case and a second case in which at least one of the cup portions is formed, and a folding portion that integrally connects the first case and the second case, wherein the width of the folding portion is 1 mm to 3.2 mm, and the depth of the cup portion is 6.5 mm or less.

[0022] The area of ​​the electrode assembly is 15,000 mm 2 ~100,000mm 2The folding portion may have a width of 1 mm to 1.6 mm. The folding portion may be formed to include a recessed groove on its inner side.

[0023] The battery case may also include a pair of protrusions that protrude outward with the groove between them, and the distance between the innermost part of the groove and the outermost part of the protrusions may be 0.8 mm or less.

[0024] The difference between the width of the cup portion and the width of the electrode assembly may be 2.5 mm or less. The difference between the width of the cup portion and the width of the electrode assembly may be 1.7 mm or less. The width of the cup portion may be the distance between the upper ends of the outer walls of the cup portion.

[0025] The cup portion may include a plurality of punch edges that connect the bottom portion to a plurality of outer walls surrounding the periphery, at least one of which is rounded with a radius of curvature of 1 mm or less; a plurality of die edges that connect the outer walls to the side or vent portion, at least one of which is rounded with a radius of curvature of 1 mm or less; and a thickness edge that connects two adjacent outer walls to each other.

[0026] Furthermore, the vertical distance between a die edge vertical line that passes through the boundary point between the die edge and the outer wall on the die edge side and is perpendicular to the bottom, and an edge vertical line that passes through the boundary point between the punch edge on the die edge side and the outer wall on the die edge side and is perpendicular to the bottom, may be 0.5 mm or less.

[0027] In addition, the electrode assembly may have one end of at least one of the electrodes positioned at a vertical distance of 0.75 mm or less from the edge perpendicular line, and the electrode assembly may have one end of at least one of the electrodes positioned at a vertical distance of 0.5 mm or less from the edge perpendicular line.

[0028] In addition, the separator may have a periphery protruding outward from the electrodes folded toward the opposite side of the bottom from one end of the electrodes.

[0029] The electrode assembly may include a plurality of electrodes and a plurality of separators, and the separator housed in the cup portion of the first case may have its peripheral portion folded toward the second case, and the separator housed in the cup portion of the second case may have its peripheral portion folded toward the first case. The peripheral portion of at least one separator may be folded to align with the peripheral portion of an adjacent separator.

[0030] At least one of the punch edges may be rounded with a radius of curvature of 0.7 mm or less. The radius of curvature of the punch edge may be 1 / 20 to 1 / 6 of the depth of the cup portion.

[0031] At least one of the die edges may be rounded with a radius of curvature of 0.7 mm or less. The radius of curvature of the die edge may be 1 / 20 to 1 / 6 of the depth of the cup portion. The outer wall may be inclined from the bottom at an angle of 90° to 95°.

[0032] In addition, the thickness edge may be connected to two adjacent punch edges to form corners, and at least one of the corners may be rounded with a radius of curvature of 2 mm to 5 mm, and the radius of curvature may be larger than the radius of curvature of the thickness edge.

[0033] The radius of curvature may vary within the corner, and the radius of curvature of the corner at the center may be greater than the radius of curvature of the periphery.

[0034] The device may further include bat ears protruding outward from both ends of the folding portion by a length of 1.5 mm or less. The angle formed between the folding portion and the inner edge of the bat ears may be greater than 151 degrees. Other specific features of the present invention are included in the detailed description and drawings. [Effects of the Invention]

[0035] According to an embodiment of the present invention, at least the following effects can be achieved: The radius of curvature and clearance of the edge of the cup part of the pouch-type battery case and the pouch-type secondary battery can be made smaller, and the thickness of the bridge can be made thinner, so the width of the folding part can be reduced, the volume of the electrode assembly can be increased, the size of the bat ears can be reduced, and the edge high phenomenon can be prevented, so the energy density relative to volume can be increased.

[0036] Furthermore, since the pouch-type battery case and pouch-type secondary battery can be manufactured with a sharp overall shape, the appearance of the secondary battery is beautiful and the marketability can be improved.

[0037] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included within the present specification. [Additional note 1] A cup portion is formed to accommodate an electrode assembly formed by stacking electrodes and separators, the cup portion includes a plurality of die edges that connect a plurality of outer walls surrounding the periphery and a side or vent portion, at least one of which is rounded with a radius of curvature of 1 mm or less; The pouch-type battery case has a depth of 6.5 mm or less. [Additional note 2] Item 2. The pouch-type battery case according to item 1, wherein at least one of the die edges is rounded with a curvature radius of 0.7 mm or less. [Additional note 3] 3. The pouch-type battery case according to claim 1 or 2, wherein the radius of curvature of the die edge is 1 / 20 to 1 / 6 of the depth of the cup portion. [Additional note 4] The cup portion is A plurality of punch edges respectively connecting the outer wall and the bottom, at least one of which is rounded with a curvature radius of 1 mm or less; 4. The pouch-type battery case according to any one of appended items 1 to 3, further comprising a thickness edge connecting two adjacent outer walls to each other. [Additional note 5] 5. The pouch-shaped battery case according to claim 4, wherein the vertical distance between a die edge vertical line that passes through a boundary between the die edge and the outer wall on the die edge side and is perpendicular to the bottom, and an edge vertical line that passes through a boundary between the punch edge on the die edge side and the outer wall on the die edge side and is perpendicular to the bottom, is 0.5 mm or less. [Additional note 6] The thickness edge is connected to two adjacent punch edges to form a corner; 5. The pouch-type battery case according to claim 4, wherein at least one of the corners is rounded with a radius of curvature of 2 mm to 5 mm, the radius of curvature being larger than the radius of curvature of the thickness edge. [Additional note 7] 7. The pouch-type battery case according to claim 6, wherein the radius of curvature changes within the corner. [Additional note 8] 8. The pouch-type battery case according to claim 7, wherein the corner has a larger radius of curvature at the center than at the periphery. [Additional note 9] 9. The pouch-type battery case according to any one of appended items 4 to 8, wherein at least one of the punch edges is rounded with a curvature radius of 0.7 mm or less. [Additional Note 10] 10. The pouch-type battery case according to any one of appended items 4 to 9, wherein the radius of curvature of the punch edge is 1 / 20 to 1 / 6 of the depth of the cup portion. [Additional Note 11] a first case and a second case each having the cup portion formed therein; a bridge formed between the two cup portions; 11. The pouch-type battery case according to any one of appended items 1 to 10, wherein the bridge has a thickness of 2 mm or less. [Additional Note 12] Item 12. The pouch-type battery case according to item 11, wherein the bridge has a thickness of 1.4 mm or less. [Additional Note 13] 13. The pouch-type battery case according to claim 11 or 12, wherein the bridge has a thickness that is 1 / 200 to 1 / 30 of the width of the electrode assembly. [Additional Note 14] 14. The pouch-type battery case according to any one of claims 11 to 13, wherein the bridge is formed to be rounded with a curvature radius of 1 mm or less. [Additional Note 15] Item 15. The pouch-type battery case according to item 14, wherein the bridge is rounded with a curvature radius of 0.7 mm or less. [Additional Note 16] The pouch-type battery case according to any one of appended items 11 to 15, wherein the thickness of the bridge is the distance between two bridge perpendicular lines that pass through the boundary between the bridge and the outer wall on the bridge side and are perpendicular to the bottom. [Additional Note 17] 17. The pouch-type battery case according to any one of appended items 1 to 16, wherein the outer wall has an inclination angle of 90° to 95° from the bottom. [Additional Note 18] an electrode assembly formed by stacking electrodes and separators; a pouch-type battery case having a cup portion for accommodating the electrode assembly therein, The battery case is a first case and a second case, at least one of which has the cup portion formed therein; a folding portion that integrally connects the first case and the second case, The folding portion has a width of 1 mm to 3.2 mm, A pouch-type secondary battery, wherein the depth of the cup portion is 6.5 mm or less. [Additional Note 19] Item 19. The pouch-type secondary battery according to item 18, wherein the electrode assembly has an area of ​​15,000 mm 2 to 100,000 mm 2 . [Additional Note 20] 20. The pouch-type secondary battery according to claim 18 or 19, wherein the folding portion has a width of 1 mm to 1.6 mm. [Additional Note 21] 21. The pouch-type secondary battery according to any one of claims 18 to 20, wherein the folding portion is formed to include a groove recessed inward. [Additional Note 22] the battery case includes a pair of protrusions that protrude outward with the groove therebetween, 22. The pouch-type secondary battery according to claim 21, wherein the distance between the innermost part of the groove and the outermost part of the protrusion is 0.8 mm or less. [Additional note 23] 23. The pouch-type secondary battery according to any one of claims 18 to 22, wherein the difference between the width of the cup portion and the width of the electrode assembly is 2.5 mm or less. [Additional note 24] 24. The pouch-type secondary battery according to claim 23, wherein the difference between the width of the cup portion and the width of the electrode assembly is 1.7 mm or less. [Additional note 25] 25. The pouch-type secondary battery according to claim 23, wherein the width of the cup portion is the distance between the upper ends of the outer walls of the cup portion. [Additional note 26] The cup portion is a plurality of punch edges that connect the plurality of outer walls and the bottom portion surrounding the periphery, at least one of which is rounded with a curvature radius of 1 mm or less; a plurality of die edges connecting the outer wall and the side or vent portion, at least one of which is rounded with a curvature radius of 1 mm or less; 26. The pouch-type secondary battery according to any one of claims 18 to 25, further comprising a thickness edge connecting two adjacent outer walls to each other. [Additional note 27] 27. The pouch-type secondary battery according to claim 26, wherein a vertical distance between a die edge vertical line that passes through a boundary point between the die edge and the outer wall on the die edge side and is perpendicular to the bottom, and an edge vertical line that passes through a boundary point between the punch edge on the die edge side and the outer wall on the die edge side and is perpendicular to the bottom, is 0.5 mm or less. [Additional note 28] 28. The pouch-type secondary battery according to claim 27, wherein the electrode assembly has one end of at least one of the electrodes positioned at a vertical distance of 0.75 mm or less from the edge vertical line. [Additional note 29] 29. The pouch-type secondary battery according to claim 28, wherein the electrode assembly has one end of at least one of the electrodes positioned at a vertical distance of 0.5 mm or less from the edge vertical line. [Additional note 30] 30. The pouch-type secondary battery according to any one of claims 26 to 29, wherein the separator has a peripheral portion that protrudes outward from the electrodes and is folded in a direction opposite to the bottom portion, with one end of the electrodes as a base. [Additional note 31] The electrode assembly includes a plurality of electrodes and a plurality of separators, The separator accommodated in the cup portion of the first case has the peripheral portion folded toward the second case, 31. The pouch-type secondary battery according to claim 30, wherein the separator housed in the cup portion of the second case has the peripheral portion folded toward the first case. [Additional note 32] 32. The pouch-type secondary battery according to claim 31, wherein the peripheral portion of at least one of the separators is folded in alignment with the peripheral portion of an adjacent separator. [Additional note 33] 33. The pouch-type secondary battery according to any one of claims 26 to 32, wherein at least one of the punch edges is rounded with a curvature radius of 0.7 mm or less. [Additional note 34] 34. The pouch-type secondary battery according to any one of claims 26 to 33, wherein the radius of curvature of the punch edge is 1 / 20 to 1 / 6 of the depth of the cup portion. [Additional note 35] 35. The pouch-type secondary battery according to any one of claims 26 to 34, wherein at least one of the die edges is rounded with a radius of curvature of 0.7 mm or less. [Additional note 36] 36. The pouch-type secondary battery according to any one of claims 26 to 35, wherein the radius of curvature of the die edge is 1 / 20 to 1 / 6 of the depth of the cup portion. [Additional note 37] 37. The pouch-type secondary battery according to any one of claims 26 to 36, wherein the outer wall is inclined from the bottom at an angle of 90° to 95°. [Additional note 38] The thickness edge is connected to two adjacent punch edges to form a corner; 38. The pouch-type secondary battery according to any one of claims 26 to 37, wherein at least one of the corners is rounded with a radius of curvature of 2 mm to 5 mm, the radius of curvature being larger than the radius of curvature of the thickness edge. [Additional note 39] Item 39. The pouch-type secondary battery according to item 38, wherein the radius of curvature changes within the corner. [Additional note 40] 40. The pouch-type secondary battery according to claim 39, wherein the corner has a larger radius of curvature at the center than at the periphery. [Additional note 41] 41. The pouch-type secondary battery according to any one of claims 18 to 40, further comprising bat ears formed to protrude outward from portions of both ends of the folding portion, the bat ears having a length of 1.5 mm or less. [Additional note 42] 42. The pouch-type secondary battery according to claim 41, wherein the angle formed by the folding portion and the inner edge of the bat ear is greater than 151 degrees. [Brief explanation of the drawings]

[0038] [Figure 1]1 is an assembly diagram of a secondary battery 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a pouch film 135 according to one embodiment of the present invention. [Figure 3] 1 is a schematic view of a molding device 2 according to one embodiment of the present invention. [Figure 4] FIG. 10 is an enlarged schematic view of a conventional cup portion 333 and a bridge 336. [Figure 5] FIG. 2 is an enlarged schematic view of a cup portion 133 and a bridge 136 according to an embodiment of the present invention. [Figure 6] FIG. 2 is an enlarged schematic view of a cup portion 133 and a gas vent portion 137 according to one embodiment of the present invention. [Figure 7] 1 is a schematic top view showing an electrode assembly 10 housed in a cup portion 133 according to an embodiment of the present invention. [Figure 8] FIG. 1 is a schematic diagram showing a conventional corner 364. [Figure 9] FIG. 1 is a schematic diagram illustrating a corner 164 according to one embodiment of the present invention. [Figure 10] 1 is a schematic diagram showing a state in which a battery case 13 according to an embodiment of the present invention is folded. [Figure 11] FIG. 2 is a schematic diagram showing a state in which a battery case 13 according to one embodiment of the present invention is folded. [Figure 12] FIG. 10 is an enlarged view of a groove 1391 formed in a battery case 13 according to one embodiment of the present invention. [Figure 13] 16 is an enlarged schematic view of a cup portion 133 and a die edge 1621 according to another embodiment of the present invention. FIG. [Figure 14] 10A and 10B are schematic diagrams illustrating a state in which a battery case 13a according to another embodiment of the present invention is folded. [Figure 15] FIG. 10 is a schematic diagram showing a battery case 13a according to another embodiment of the present invention in a folded state. [Figure 16] 13 is an enlarged view of a groove 1391a formed in a battery case 13 according to another embodiment of the present invention. FIG. [Figure 17] FIG. 10 is a schematic diagram showing the state of a conventional battery case 33 from above before a gas vent portion 337 is cut off. [Figure 18] 1 is a schematic diagram showing the state of a battery case 13 according to one embodiment of the present invention, viewed from above, before a gas vent portion 137 is cut off. [Figure 19] FIG. 1 is a block diagram of an inspection device 4 according to an embodiment of the present invention. [Figure 20] FIG. 10 is a schematic diagram showing a state in which the manufacturing of a secondary battery 1 is completed by cutting a gas vent portion 137 of a battery case 13 according to one embodiment of the present invention. [Figure 21] FIG. 10 is a schematic side view showing a conventional side 334 folded. [Figure 22] FIG. 10 is a schematic diagram showing a conventional side 334 folded from above. [Figure 23] FIG. 10 is a schematic side view of a folded side 134 according to an embodiment of the present invention. [Figure 24] 1 is a schematic diagram of a battery module 5 according to one embodiment of the present invention. [Figure 25] FIG. 10 is an enlarged front view showing a state in which a conventional secondary battery 3 is housed in a housing 51 of a battery module 5. [Figure 26] 1 is an enlarged side view showing a state in which a conventional secondary battery 3 is housed in a housing 51 of a battery module 5. FIG. [Figure 27] 1 is an enlarged front view showing a secondary battery 1 according to one embodiment of the present invention housed in a housing 51 of a battery module 5. FIG. [Figure 28] 1 is an enlarged side view showing a secondary battery 1 according to one embodiment of the present invention housed in a housing 51 of a battery module 5. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0039] The advantages and features of the present invention, as well as methods for achieving them, will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various different forms. The present embodiments are provided solely to ensure complete disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains. The present invention is defined solely by the scope of the claims. The same reference symbols refer to the same elements throughout the specification.

[0040] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in the sense commonly understood by those skilled in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless clearly defined otherwise.

[0041] The terms used in this specification are for the purpose of describing embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless otherwise specified in the wording. The words "comprises" and / or "comprising" used in this specification do not exclude the presence or addition of one or more other elements in addition to the elements mentioned.

[0042] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is an assembly diagram of a secondary battery 1 according to one embodiment of the present invention.

[0043] According to an embodiment of the present invention, the radius of curvature and clearance of the edge of the cup portion of the pouch-type battery case and pouch-type secondary battery can be made smaller, and the thickness of the bridge can be made thinner, thereby reducing the width of the folding portion, increasing the volume of the electrode assembly, reducing the size of the bat ears, and preventing the edge-high phenomenon, thereby increasing the energy density per volume.In addition, the pouch-type battery case and pouch-type secondary battery can be manufactured with an overall sharp shape, resulting in a beautiful appearance of the secondary battery and improved marketability.

[0044] To this end, a pouch-type battery case according to one embodiment of the present invention has a cup portion formed therein to accommodate an electrode assembly formed by stacking electrodes and a separator, and the cup portion includes a plurality of punch edges that respectively connect a plurality of outer walls surrounding the periphery with a bottom portion, at least one of which is rounded with a curvature radius of 1 mm or less, a plurality of die edges that connect the outer walls with a side or a gas vent portion, at least one of which is rounded with a curvature radius of 1 mm or less, and a thickness edge that connects two adjacent outer walls to each other, The vertical distance between a die edge vertical line passing through the boundary point between the die edge and the outer wall on the die edge side and perpendicular to the bottom, and an edge vertical line passing through the boundary point between the punch edge on the die edge side and the outer wall on the die edge side and perpendicular to the bottom, is 0.5 mm or less; the thickness edge is connected to two adjacent punch edges to form corners, at least one of which is rounded with a curvature radius of 2 mm to 5 mm, the curvature radius being larger than the curvature radius of the thickness edge; and the depth of the cup portion is 6.5 mm or less.

[0045] A pouch-type secondary battery according to one embodiment of the present invention includes an electrode assembly formed by stacking electrodes and separators, and a pouch-type battery case formed with a cup portion for accommodating the electrode assembly therein, wherein the battery case includes a first case and a second case in which at least one of the cup portions is formed, a folding portion that integrally connects the first case and the second case, and bat ears formed to protrude outward from both ends of the folding portion, and the cup portion includes a plurality of punch edges that respectively connect a plurality of outer walls surrounding the periphery to a bottom portion, at least one of which is rounded with a curvature radius of 1 mm or less, a plurality of die edges that connect the outer walls to a side or a gas vent portion, at least one of which is rounded with a curvature radius of 1 mm or less, and adjacent a thickness edge connecting the two outer walls to each other, wherein a vertical distance between a die edge vertical line passing through a boundary between the die edge and the outer wall on the die edge side and perpendicular to the bottom, and an edge vertical line passing through a boundary between the punch edge on the die edge side and the outer wall on the die edge side and perpendicular to the bottom, is 0.5 mm or less; the thickness edge connects two adjacent punch edges to form corners, at least one of which is rounded with a radius of curvature of 2 mm to 5 mm, the radius of curvature being larger than the radius of curvature of the thickness edge; the width of the folding portion is 1 mm to 3.2 mm; the length of the bat ear is 1 mm or less; the difference between the width of the cup portion and the width of the electrode assembly is 2.5 mm or less; and the depth of the cup portion is 6.5 mm or less.

[0046] The electrode assembly 10 is formed by alternately stacking electrodes 101 (shown in FIG. 5) and separators 102 (shown in FIG. 5). First, a slurry containing an electrode active material, a binder, and a plasticizer is applied to a positive electrode current collector and a negative electrode current collector to produce electrodes 101 such as a positive electrode and a negative electrode. Then, separators 102 are stacked between the electrodes 101 to form the electrode assembly 10. The electrode assembly 10 is inserted into a battery case 13, and the case is sealed after electrolyte is injected.

[0047] The electrode assembly 10 has an area of ​​15,000 mm 2 ~100,000mm 2 In particular, the electrode assembly 10 may have an overall width of 60 mm or more. In addition, the electrode assembly 10 may have a thickness of 6 mm or more in the stacking direction. Therefore, the electrode assembly 10 according to one embodiment of the present invention can provide a larger battery capacity than a typical small battery.

[0048] Specifically, the electrode assembly 10 includes two types of electrodes 101, a positive electrode and a negative electrode, and a separator 102 interposed between the electrodes 101 to insulate the electrodes 101 from each other. Examples of such electrode assemblies 10 include stacked, jelly roll, and stack-and-folded types. The two types of electrodes 101, i.e., the positive electrode and the negative electrode, are each constructed by applying an active material slurry to a metal foil or metal mesh electrode collector containing aluminum and copper. The active material slurry can typically be formed by stirring a granular active material, a conductive material, and the like in a solvent. The solvent is removed in a subsequent process.

[0049] As shown in FIG. 1, the electrode assembly 10 includes electrode tabs 11. The electrode tabs 11 are connected to the positive and negative electrodes of the electrode assembly 10, respectively, and protrude from the electrode assembly 10 to provide a path for electrons to move between the inside and outside of the electrode assembly 10. The electrode current collector of the electrode assembly 10 includes a portion coated with an electrode active material and an end portion, i.e., a plain portion, where the electrode active material is not coated. The electrode tabs 11 may be formed by cutting the plain portion or by connecting a separate conductive member to the plain portion by ultrasonic welding or the like. The electrode tabs 11 may protrude in different directions from the electrode assembly 10 as shown in FIG. 1, but are not limited thereto and may protrude in various directions, such as protruding side by side in the same direction from one side.

[0050] An electrode lead 12 that supplies electricity to the outside of the secondary battery 1 is connected to the electrode tab 11 of the electrode assembly 10 by spot welding or the like. A portion of the electrode lead 12 is surrounded by an insulating portion 14. The insulating portion 14 is located only on a side 134 of the battery case 13 where the first case 131 and the second case 132 are heat-sealed, and adheres the electrode lead 12 to the battery case 13. The insulating portion 14 prevents electricity generated from the electrode assembly 10 from flowing to the battery case 13 through the electrode lead 12, thereby maintaining the seal of the battery case 13. Therefore, the insulating portion 14 is made of a non-conductive material that does not conduct electricity well. Typically, the insulating portion 14 is made of insulating tape, which is easy to adhere to the electrode lead 12 and is relatively thin, but is not limited thereto and various materials may be used as long as they can insulate the electrode lead 12.

[0051] The electrode lead 12 has one end connected to the electrode tab 11 and the other end protruding out of the battery case 13. That is, the electrode lead 12 includes a positive electrode lead 121 having one end connected to the positive electrode tab 111 and extending in the direction in which the positive electrode tab 111 protrudes, and a negative electrode lead 122 having one end connected to the negative electrode tab 112 and extending in the direction in which the negative electrode tab 112 protrudes. Meanwhile, as shown in FIG. 1 , the other ends of both the positive electrode lead 121 and the negative electrode lead 122 protrude out of the battery case 13. This allows electricity generated inside the electrode assembly 10 to be supplied to the outside. In addition, because the positive electrode tab 111 and the negative electrode tab 112 protrude in various directions, the positive electrode lead 121 and the negative electrode lead 122 can also extend in various directions.

[0052] The positive electrode lead 121 and the negative electrode lead 122 may be made of different materials. That is, the positive electrode lead 121 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 122 may be made of the same copper (Cu) material as the negative electrode current collector, or a copper material coated with nickel (Ni). A portion of the electrode lead 12 protruding outside the battery case 13 serves as a terminal portion and is electrically connected to an external terminal.

[0053] The battery case 13 is a pouch manufactured by molding a pouch film 135 made of a flexible material, which houses the electrode assembly 10 therein. Hereinafter, the battery case 13 will be described as a pouch. When the flexible pouch film 135 is drawn using a punch 22 (shown in FIG. 6 ) or the like, a portion of the flexible pouch film 135 is stretched to form a cup portion 133 including a bag-shaped storage space 1331, thereby manufacturing the battery case 13.

[0054] The battery case 13 accommodates and seals the electrode assembly 10 such that a portion of the electrode lead 12 is exposed. As shown in FIG. 1, the battery case 13 includes a first case 131 and a second case 132. The first case 131 is formed with a cup portion 133 and is provided with an accommodation space 1331 that can accommodate the electrode assembly 10, and the second case 132 covers the accommodation space 1331 from above to prevent the electrode assembly 10 from falling out of the battery case 13. The first case 131 and the second case 132 may be manufactured with one side connected to each other as shown in FIG. 1, but are not limited thereto and may be manufactured in various ways, such as being separated from each other and separately manufactured.

[0055] When forming the cup portions 133 in the pouch film 135, only one cup portion 133 may be formed in one pouch film 135, but is not limited thereto, and two cup portions 133 may be formed adjacent to each other by draw molding in one pouch film 135. Then, as shown in Fig. 1, the cup portions 133 are formed in the first case 131 and the second case 132, respectively. In this case, the cup portions 133 formed in the first case 131 and the second case 132 may have the same depth D, but is not limited thereto, and the depths D may be different from each other.

[0056] In one embodiment of the present invention, the depth D of the cup portion 133 may be 3 mm or more and 6.5 mm or less. Therefore, the cup portion 133 according to one embodiment of the present invention can accommodate an electrode assembly 10 having a larger electrode capacity than a general small battery.

[0057] After the electrode assembly 10 is accommodated in the accommodation space 1331 defined in the cup portion 133 of the first case 131, the battery case 13 can be folded around the bridge 136 formed between the two cup portions 133 of the battery case 13 so that the two cup portions 133 face each other. The cup portion 133 of the second case 132 then accommodates the electrode assembly 10 from above. Therefore, because two cup portions 133 accommodate one electrode assembly 10, it is possible to accommodate an electrode assembly 10 that is thicker than when there is only one cup portion 133. Furthermore, because the first case 131 and the second case 132 are integrally connected to each other by folding the battery case 13, the number of sides 134 to be sealed during a subsequent sealing process can be reduced. This can improve the process speed and reduce the number of sealing processes.

[0058] Meanwhile, the battery case 13 may include a cup portion 133 having an accommodation space 1331 for accommodating the electrode assembly 10, and a gas vent portion 137 formed on a side of the cup portion 133 and discharging gas generated inside the cup portion 133 through a gas vent hole H. When the electrode assembly 10 is accommodated in the cup portion 133 of the battery case 13 and an electrolyte is injected, an activation process is performed, generating gas inside the battery case 13, and a gas venting process is performed to discharge the gas to the outside. The gas vent portion 137 will be described in detail later.

[0059] After the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and an insulating portion 14 is formed on a portion of the electrode lead 12, the electrode assembly 10 is accommodated in the accommodation space 1331 defined in the cup portion 133 of the first case 131, and the second case 132 covers the space from above. An electrolyte is then injected into the accommodation space, and the sides 134 extending outward from the cup portions 133 of the first case 131 and the second case 132 are sealed. The electrolyte transports lithium ions generated by an electrochemical reaction in the electrode 101 during charging and discharging of the secondary battery 1. The electrolyte may include a non-aqueous organic electrolyte solution, which is a mixture of lithium salt and high-purity organic solvents, or a polymer using a polymer electrolyte. The electrolyte may also include a sulfide-based, oxide-based, or polymer-based solid electrolyte, which may be flexible enough to be easily deformed by external force. This method allows the pouch-type secondary battery 1 to be manufactured.

[0060] 2 is a cross-sectional view of a pouch film 135 according to one embodiment of the present invention. The pouch, which is the battery case 13 of the pouch-type secondary battery 1 according to one embodiment of the present invention, is manufactured by drawing the pouch film 135. That is, the pouch film 135 is stretched using a punch 22 or the like to form a cup portion 133. According to one embodiment of the present invention, the pouch film 135 includes a sealant layer 1351, a moisture barrier layer 1352, and a surface protection layer 1353, as shown in FIG. 2, and may further include a drawing assistance layer 1354, if necessary.

[0061] The sealant layer 1351 is made of a first polymer and is formed as the innermost layer, allowing direct contact with the electrode assembly 10. Here, the innermost layer refers to the layer located most closely to the moisture barrier layer 1352 when facing the electrode assembly 10. The battery case 13 is manufactured by drawing the laminated pouch film 135 using a punch 22 or the like, stretching a portion of the film to form a cup portion 133 including a bag-shaped receiving space 1331. The electrode assembly 10 is then placed in the receiving space 1331, and an electrolyte is then injected. The first case 131 and the second case 132 are then brought into contact with each other and thermocompressed to the sides 134, thereby adhering the sealant layers 1351 to each other and sealing the pouch. In this case, the sealant layer 1351 must be insulating because it comes into direct contact with the electrode assembly 10, and corrosion-resistant because it also comes into contact with the electrolyte. Furthermore, it must have high sealing properties because it must completely seal the interior and prevent material transfer between the interior and exterior. That is, the sides 134 where the sealant layers 1351 are bonded together must have excellent thermal adhesive strength. Generally, the first polymer used to form the sealant layer 1351 may be one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. In particular, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are commonly used. Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, and excellent chemical properties such as corrosion resistance, and is therefore mainly used to manufacture the sealant layer 1351. Furthermore, it may be made of unstretched polypropylene (Cated Polypropylene), acid-modified polypropylene, or polypropylene-butylene-ethylene terpolymer.Here, the acid-modified polypropylene may be MAH PP (Maleic Anhydride Polypropylene). Also, the sealant layer 1351 may have a single film structure made of any one material, or a composite film structure formed by layers of two or more materials.

[0062] The moisture barrier layer 1352 is laminated between the surface protective layer 1353 and the sealant layer 1351 to ensure the mechanical strength of the pouch, block the ingress and egress of gas or moisture outside the secondary battery 1, and prevent electrolyte leakage. The moisture barrier layer 1352 may be made of an aluminum alloy thin film. The aluminum alloy thin film can ensure a certain level of mechanical strength while being lightweight, and can ensure the electrochemical properties of the electrode assembly 10 and the electrolyte, as well as heat dissipation.

[0063] More specifically, the aluminum alloy thin film according to one embodiment of the present invention may have a grain size of 10 to 13 μm, preferably 10.5 to 12.5 μm, and more preferably 11 to 12 μm. When the grain size of the aluminum alloy thin film satisfies this range, the forming depth can be increased without generating pinholes or cracks during cup forming.

[0064] Such an aluminum alloy thin film may contain one or more metal elements other than aluminum, such as iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), and zinc (Zn).

[0065] The surface protective layer 1353 is made of a second polymer and is formed as the outermost layer. It protects the secondary battery 1 from external friction and impact while electrically insulating the electrode assembly 10 from the outside. Here, the outermost layer refers to the layer located most recently in the opposite direction from the moisture barrier layer 1352 toward the electrode assembly 10. The second polymer used to form the surface protective layer 1353 may be one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. In particular, it is preferable to use a polymer such as polyethylene terephthalate (PET), which is primarily abrasion-resistant and heat-resistant. The surface protective layer 1353 may have a single film structure made of any one material or a composite film structure formed by layers of two or more materials.

[0066] On the other hand, PET is inexpensive, durable, and has excellent electrical insulation properties, but it also has poor adhesion to aluminum, which is often used for the moisture barrier layer 1352, and its behavior when stretched by applying stress differs from that of the other material. Therefore, if the surface protective layer 1353 and the moisture barrier layer 1352 are directly bonded, the surface protective layer 1353 and the moisture barrier layer 1352 may peel off during draw forming. This can cause the moisture barrier layer 1352 to be stretched unevenly, resulting in a problem of reduced formability.

[0067] According to one embodiment of the present invention, the battery case 13 may further include a stretching assist layer 1354 made of a third polymer and laminated between the surface protective layer 1353 and the moisture barrier layer 1352. The stretching assist layer 1354 is laminated between the surface protective layer 1353 and the moisture barrier layer 1352 and prevents the surface protective layer 1353 and the moisture barrier layer 1352 from peeling off when they are stretched. The third polymer from which the stretching assist layer 1354 is made may be one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. In particular, nylon resin is preferably used as the third polymer because nylon resin easily adheres to polyethylene terephthalate (PET) of the surface protective layer 1353 and behaves similarly when stretched to the aluminum alloy of the moisture barrier layer 1352. The stretching assist layer 1354 may have a single film structure made of any one material, or a composite film structure formed by layers of two or more materials.

[0068] Meanwhile, the pouch film 135 according to the present invention may have a total thickness of 160 μm to 200 μm, preferably 180 μm to 200 μm. When the thickness of the pouch film 135 satisfies this range, it is possible to increase the molding depth while minimizing the reduction in the battery accommodating space and the deterioration in sealing durability due to an increase in the pouch thickness.

[0069] 3 is a schematic diagram of a forming device 2 according to one embodiment of the present invention. The forming device 2 for forming the pouch film 135 according to one embodiment of the present invention includes a die 21 on whose upper surface the pouch film 135 is placed, and a punch 22 that is disposed above the die 21 and descends to form the pouch film 135. The die 21 includes a forming portion 211 that is recessed inward from its upper surface, and the punch 22 inserts the pouch film 135 into the forming portion 211 and draws and forms the cup portion 133.

[0070] According to one embodiment of the present invention, when forming a pouch film 135 using the forming apparatus 2, as shown in Fig. 3, two forming portions 211 are formed adjacent to each other in the die 21, and a partition wall 212 may be formed between the two forming portions 211. When the punch 22 is inserted into both forming portions 211 to draw-form the pouch film 135, a total of two cup portions 133 are formed in the first case 131 and the second case 132, one in each case, corresponding to the two forming portions 211, and a bridge 136 may also be formed between the two cup portions 133, corresponding to the partition wall 212.

[0071] The bridge 136 may serve as a reference when folding the battery case 13 later. After the secondary battery 1 is manufactured, the bridge 136 may form a folding portion 139 (shown in FIG. 11) on one side of the secondary battery 1. The folding portion 139 integrally connects the first case 131 and the second case 132 to each other, thereby reducing the number of sides 134 to be sealed during a subsequent sealing process. This improves the process speed and reduces the number of sealing processes. In this regard, as the width of the folding portion 139 is smaller, the space 17 (shown in FIG. 5) between the outer wall 138 of the cup portion 133 (shown in FIG. 5) and the electrode assembly 10 also becomes smaller, thereby reducing the overall volume of the secondary battery 1 and increasing the energy density per volume.

[0072] The width of the folding portion 139 is proportional to the thickness t (shown in FIG. 5 ) of the bridge 136. Because the bridge 136 is formed corresponding to the partition wall 212, the thickness t of the bridge 136 is proportional to the thickness of the partition wall 212. Therefore, when forming the pouch film 135, it is preferable to minimize the thickness t of the bridge 136, and therefore it is preferable to minimize the thickness of the partition wall 212 as well. However, if the partition wall 212 is formed too high while being thin, the partition wall 212 may be damaged during the draw-forming process. In particular, conventional dies have a bottom, which poses a problem in that gas present in the space between the pouch film 135 and the forming portion 211 cannot be discharged when the punch 22 forms the pouch film 135. Therefore, in recent years, by removing the bottom from such dies, gas present in the space between the pouch film 135 and the forming portion 211 can be easily discharged, but there is a problem in that the height of the partition wall 212 is formed too high. 3, a reinforcing portion 2121 having a thickness greater than that of the partition wall 212 may be formed below the partition wall 212. The reinforcing portion 2121 may be formed below the depth D of the cup portion 133 formed in the battery case 13, at a position that will not damage the partition wall 212. The exact position of the reinforcing portion 2121 may be determined experimentally depending on the thickness of the partition wall 212, the material of the partition wall 212, the pressure of the punch 22, the depth D of the cup portion 133 to be formed, etc.

[0073] 4 is an enlarged schematic view of a conventional cup portion 333 and bridge 336. Conventionally, even when manufacturing battery cases and secondary batteries, there has been a limit to how sharp the overall shape can be.

[0074] Specifically, conventionally, there has been a limit to reducing the radius of curvature of the edge 36 of the cup portion 333. The edge 36 of the cup portion 333 includes a punch edge 361 formed corresponding to the edge 221 of the punch 22 (shown in FIG. 3) and a die edge 362 (shown in FIG. 8) formed corresponding to the edge 213 of the die 21 (shown in FIG. 3).

[0075] The punch edge 361 connects the multiple outer walls 338 surrounding the periphery of the cup portion 333 to the bottom portion 3332. If the edge 221 of the punch 22 is not rounded, the edge 221 of the punch 22 becomes sharp, which causes stress to concentrate on the punch edge 361 of the cup portion 333 when forming the pouch film 135, resulting in a problem of cracks being easily generated. In addition, the die edge 362 connects the multiple outer walls 338 to the side 134 or the vent portion 137. If the edge 213 of the die 21 is not rounded, the edge of the die 21 becomes sharp, which causes stress to concentrate on the die edge 362 of the cup portion 333 when forming the pouch film 135, resulting in a problem of cracks being easily generated. Here, "rounded" means that a curved surface is formed to have a curvature, and such a curved surface may have only a constant curvature, but is not limited thereto and may have a non-constant curvature. In this specification, "the punch edge 161, the die edge 162, the bridge 136, etc. are formed to be rounded with a specific curvature" means that not only those having the specific curvature as a whole, but also those having the specific curvature only in at least a portion.

[0076] To solve the above problem, as shown in Fig. 4, the edge 221 of the punch 22 and the edge 213 of the die 21 are rounded, and the punch edge 361 and the die edge 362 of the cup portion 333 are rounded. This makes it possible to disperse the stress concentrated on the punch edge 361 and the die edge 362 of the cup portion 333 to some extent.

[0077] However, even if punch edge 361 and die edge 362 of cup portion 333 are formed to be rounded, cracks occur in punch edge 361 and die edge 362 of cup portion 333 when radius of curvature R2' of punch edge 361 and radius of curvature of die edge 362 are formed to be smaller than depth D' of cup portion 333. For example, in the past, cracks could occur in pouch film 135 when radius of curvature R2' of punch edge 361 and radius of curvature of die edge 362 of cup portion 333 were formed to be 2 mm or less if depth D' was set to about 7 mm or more when one cup portion 333 was formed, or when depth D' was set to about 6.5 mm or more when two cup portions 333 were formed.

[0078] Furthermore, when two cup portions 133 are formed, a partition wall 212 must be present in the die 21 in order to form the bridge 136. However, conventionally, when the depth D' of the cup portion 333 is formed deep (for example, 6.5 mm or more), there is a limit to how thin the bridge 336 can be formed. That is, if the partition wall 212 is also formed to a certain thickness or less in order to form the bridge 336 to a certain thickness or less, the partition wall 212 is formed sharply, which causes a problem of cracks occurring in the bridge 336.

[0079] To solve this problem, as shown in FIG. 4, the partition wall 212 is rounded, and the bridge 336 is formed with a rounded shape. This makes it possible to disperse stress concentrated on the bridge 336 to some extent. In particular, when the radius of curvature R1' of the bridge 336 is constant, the radius of curvature R1' corresponds to half the thickness t' of the bridge 336. For example, when the radius of curvature R1' of the bridge 336 is formed to be approximately 1 mm, the thickness t' of the bridge 336 is formed to be approximately 2 mm.

[0080] However, even if the bridge 336 is formed to be rounded, if the depth D' of the cup portion 333 is formed deep, cracks will occur in the bridge 336 if the thickness t' of the bridge 336 is small. For example, if the depth D' of the cup portion 333 is formed to be approximately 6.5 mm or more, there is a problem in that cracks will occur in the bridge 336 when the radius of curvature R1' of the bridge 336 is formed to be 1 mm or less, that is, when the thickness t' of the bridge 336 is formed to be 2 mm or less.

[0081] Furthermore, the clearance CL' was quite large, limiting the ability to form the outer wall 338 of the cup portion 333 nearly vertically. The clearance CL refers to the vertical distance between the inner wall of the forming portion 211 of the die 21 and the outer wall of the punch 22. In fact, there is a slight difference in size between the forming portion 211 of the die 21 and the punch 22, which is the clearance CL. If the clearance CL is too small, the distance between the inner wall of the forming portion 211 and the outer wall of the punch 22 becomes too small. As a result, the pouch film 135 may not be inserted into the forming portion 211, or friction may be too great, damaging the pouch film 135. Conversely, if the clearance CL is too large, the inclination angle of the outer wall 338 of the cup portion 333 increases, increasing the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10. Therefore, when forming the pouch film 135, an appropriate size of clearance CL must be set.

[0082] The bridge 336 is formed to correspond to the partition wall 212 of the die 21, and the punch edge 361 is formed to correspond to the edge 221 of the punch 22. Therefore, the clearance CL′, which is the vertical distance between the inner wall of the forming portion 211 of the die 21 and the outer wall of the punch 22, can be represented by the vertical distance between the bridge 336 and the punch edge 361 in the battery case 33.

[0083] Specifically, as shown in FIG. 4 , a bridge vertical line V1' and an edge vertical line V2' are shown imaginary. The bridge vertical line V1' is a virtual vertical line that passes through a boundary point P1' between the bridge 336 and the outer wall 338 on the bridge 336 side and is perpendicular to the bottom 3332. The edge vertical line V2' is a virtual vertical line that passes through a boundary point P2' between the punch edge 361 on the bridge 336 side and the outer wall 338 on the bridge 336 side and is perpendicular to the bottom 3332. The bridge vertical line V1' corresponds to the inner wall of the forming portion 211 of the die 21, particularly the inner wall of the partition wall 212, and the edge vertical line V2' corresponds to the outer wall of the punch 22. Therefore, the vertical distance between the bridge vertical line V1' and the edge vertical line V2' is the clearance CL' that appears in the battery case 33.

[0084] However, in the past, when the depth D' of the cup portion 333 was formed deep (for example, 6.5 mm or more), a problem occurred in that cracks were likely to occur in the pouch film 135 when the clearance CL was reduced to 0.5 mm or less. As described above, in the past, when the depth D' of the cup portion 333 was formed deep (for example, 6.5 mm or more), there was a limit to how much the clearance CL' could be reduced, so the outer wall 338 of the cup portion 333 was formed with an inclination angle of more than 95° from the bottom 3332. In other words, there was a limit to how much the outer wall 338 of the cup portion 333 could be formed nearly vertically, with an inclination angle of 95° or less.

[0085] Meanwhile, there is a limit to how much the radius of curvature R2' of the edge of the cup portion 333 can be improved, which reduces the volume of the electrode assembly 10 accommodated in the cup portion 333. Specifically, as shown in Fig. 4, in the conventional technology, when the electrode assembly 10 is positioned too close to the outer wall 338 of the cup portion 333 due to the large radius of curvature R2' of the punch edge 361 of the cup portion 333, the electrode 101 of the electrode assembly 10 is damaged by the punch edge 361 of the cup portion 333. That is, one end of the electrode 101 containing metal is positioned on the punch edge 361 of the cup portion 333, which causes the one end of the electrode 101 to deform and be damaged in contact with the punch edge 361 of the cup portion 333.

[0086] To solve this problem, in the past, when the electrode assembly 10 was inserted into the cup portion 333, the electrode assembly 10 was spaced apart from the outer wall 338 of the cup portion 333 to a certain extent. First, a reference vertical line V3' perpendicular to the bottom 3332 was imaginarily drawn, with the vertical distance g' from the edge vertical line V2' being 0.75 mm, particularly 0.5 mm. As shown in FIG. 4, the electrode assembly 10 was then inserted so that one end of the electrode 101 was positioned outside the reference vertical line V3'. This provided a certain degree of space between the electrode 101 and the outer wall 338 of the cup portion 333, preventing damage to the electrode 101. However, this increased the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10, reducing the volume ratio of the electrode assembly 10 to the volume of the cup portion 333, resulting in a problem of a reduced energy density per volume of the secondary battery 3. Furthermore, the volume of unnecessary space inside the cup portion 333 increases, which causes the electrode assembly 10 to move inside the cup portion 333 before the sides are sealed.

[0087] In the electrode assembly 10, the electrodes 101 have high rigidity and are not easily deformed by external forces, whereas the separators 102 have high flexibility and are easily deformed by external forces. Direct contact between adjacent electrodes 101 can cause a short circuit, so to prevent this, the separators 102 are formed larger than the electrodes 101. Therefore, when the electrode assembly 10 is formed, the separators 102 also have peripheral portions 1021 that protrude outward from the electrodes 101. Conventionally, the electrode assembly 10 is housed at a certain distance from the outer wall 338 of the cup portion 333, which can cause the peripheral portions 1021 of the separators 102 to wrinkle or fold randomly, exposing the electrodes 101 to the outside and increasing the likelihood of a short circuit.

[0088] Thus, conventionally, when the depth D' of the cup portion 333 is formed deep (for example, 6.5 mm or more), there is a limit to the improvement of the thickness t' of the bridge 336, the radius of curvature R2' of the edge 361 of the cup portion 333, and the clearance CL'. Furthermore, the volume ratio of the electrode assembly 10 is small compared to the volume of the cup portion 333, and unnecessary volume in the secondary battery 3 is also large, resulting in a decrease in the volume-specific energy density. Furthermore, because the outer wall 338 of the cup portion 333 is not formed nearly vertically and the radius of curvature R2 of the edge 361 of the cup portion 333 is also large, there is a limit to the ability to manufacture a sharp overall shape, resulting in problems such as an unattractive appearance of the secondary battery 3 and reduced merchantability.

[0089] FIG. 5 is an enlarged schematic view of the cup portion 133 and bridge 136 according to one embodiment of the present invention, and FIG. 6 is an enlarged schematic view of the cup portion 133 and vent portion 137 according to one embodiment of the present invention.

[0090] According to one embodiment of the present invention, the volume of the electrode assembly 10 can be increased by forming the depth D of the cup portion 133 to be 6.5 mm or less, further reducing the thickness t of the bridge 136, and further reducing the radius of curvature R2 and clearance CL of the edge 16 of the cup portion 133. This also reduces unnecessary volume in the secondary battery 1, thereby increasing the energy density per volume. Furthermore, since the pouch-type battery case 13 and the pouch-type secondary battery 1 can be manufactured with an overall sharp shape, the appearance of the secondary battery 1 is excellent and its merchantability can be improved.

[0091] To this end, the pouch-type battery case 13 according to one embodiment of the present invention has a cup portion 133 formed therein to accommodate the electrode assembly 10 formed by stacking the electrodes 101 and the separators 102, and the cup portion 133 may include a plurality of punch edges 161 connecting a plurality of outer walls 138 surrounding the periphery to a bottom portion 1332, a plurality of die edges 162 connecting the outer walls 138 to the sides 134 or the gas vent portion 137, and a thickness edge 163 connecting two adjacent outer walls 138 to each other.

[0092] At least one of the punch edges 161 and at least one of the die edges 162 may be rounded with a radius of curvature R2 of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. If the radius of curvature R2 of each edge 161, 162 is smaller than 1 / 20 of the depth D of the cup portion 133, stress may be excessively concentrated on each edge 161, 162, causing cracks, whereas if the radius of curvature R2 of each edge 161, 162 is larger than 1 / 6 of the depth D of the cup portion 133, the cup portion 133 may not be formed sharply, resulting in a decrease in energy density.

[0093] Specifically, at least one of the punch edges 161 may be rounded with a curvature radius R2 of 1 mm or less, and at least one of the die edges 162 may be rounded with a curvature radius R2 of 1 mm or less.

[0094] A vertical distance CL between a die edge vertical line V4, which passes through boundary points P1 and P3 between the die edge 162 and the outer wall 138 adjacent to the die edge 162 and is perpendicular to the bottom 1332, and an edge vertical line V2, which passes through boundary points P2 and P4 between the punch edge 161 adjacent to the die edge 162 and the outer wall 138 adjacent to the die edge 162 and is perpendicular to the bottom 1332, is 0.5 mm or less. The thickness edge 163 is connected to two adjacent punch edges 161 to form corners 164, at least one of which may be rounded with a curvature radius R3 of 2 mm to 5 mm, the curvature radius R3 being greater than the curvature radius of the thickness edge. The depth D of the cup portion 133 may be 6.5 mm or less.

[0095] The cup portion 133 is formed by shaping a flexible pouch film 135 using a punch 22 or the like. The cup portion 133 is surrounded by a plurality of outer walls 138 and a bottom portion 1332, and the space formed by the outer walls 138 and the bottom portion 1332 serves as a storage space 1331 for storing the electrode assembly 10.

[0096] The outer wall 138 of the cup portion 133 surrounds the periphery of the cup portion 133 and defines the shape of the cup portion 133. A plurality of outer walls 138 are formed around the periphery of the cup portion 133, and are also formed on the bridge 136 side, the gas vent portion 137 side (described later), and the electrode lead 12 side. The upper end of each of these outer walls 138 faces the open portion of the cup portion 133, and the lower end faces the bottom 1332.

[0097] Meanwhile, as described above, the edge 16 of the cup portion 133 includes a punch edge 161 formed corresponding to the edge 221 of the punch 22 and a die edge 162 formed corresponding to the edge 213 (shown in FIG. 3) of the die 21. The side 134 and the vent portion 137 are formed outward from the upper end of the outer wall 138, and the die edge 162 connects the upper end of the outer wall 138 to the side 134 or the vent portion 137, respectively. The punch edge 161 also connects the lower end of the outer wall 138 to the bottom portion 1332, respectively.

[0098] Since the cup portion 133 has a plurality of outer walls 138, the cup portion 133 also has a plurality of edges 16 formed thereon, the number of which corresponds to the number of outer walls 138. That is, if the cup portion 133 is formed in a rectangular shape, four outer walls 138 of the cup portion 133 are formed, and therefore four punch edges 161 and four die edges 162 are formed. According to one embodiment of the present invention, the depth D of the cup portion 133 is formed to be 6.5 mm or less, and at least one punch edge 161 of the cup portion 133 may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less.

[0099] In particular, according to one embodiment of the present invention, two cup portions 133 are formed in one pouch film 135, and a bridge 136 is also formed between the two cup portions 133. Then, as shown in Fig. 5, among the plurality of punch edges 161, a punch edge 1611 on the bridge 136 side connecting the outer wall 1381 on the bridge 136 side and the bottom portion 1332 facing the bridge 136 side may be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1611 on the bridge 136 side may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less. 6, among the plurality of punch edges 161, a punch edge 1612 on the die edge 162 side connecting the outer wall 1382 on the die edge 162 side facing the die edge 162 formed on the vent portion 137 or the electrode lead 12 to the bottom portion 1332 may also be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1612 on the die edge 162 side may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less. In this case, it is preferable that the inclination be continuous at boundary points P2 and P4 between the punch edge 161 and the outer wall 138.

[0100] For this reason, the edge 221 of the punch 22 can also be rounded with a predetermined radius of curvature. Here, the radius of curvature of the edge 221 of the punch 22 may be a numerical value obtained by subtracting the thickness of the pouch film 135 itself from the radius of curvature R2 of the punch edge 161. For example, if the thickness of the pouch film 135 is 0.2 mm, and the radius of curvature of the edge 221 of the punch 22 is 0.5 mm or less, the radius of curvature R2 of the punch edge 161 is 0.7 mm or less.

[0101] According to one embodiment of the present invention, when such a punch 22 draws and forms the pouch film 135 so that the depth D of the cup portion 133 is 6.5 mm or less, cracks can be prevented from occurring in the punch edge 161 of the cup portion 133.

[0102] Meanwhile, the upper end of the outer wall 138 faces the opening of the cup portion 133, and the side 134 and the vent portion 137 extend outside the cup portion 133. In this case, as shown in Fig. 6, the cup portion 133 may further include a plurality of die edges 162 connecting the upper end of the outer wall 138 to the side 134 or the vent portion 137, respectively. At least one of the die edges 162 may also be rounded with a radius of curvature of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one of the die edges 162 may be rounded with a radius of curvature of 1 mm or less, particularly 0.7 mm or less.

[0103] For this reason, the edge 213 of the die 21 can also be rounded with a predetermined radius of curvature. Here, the radius of curvature of the edge 213 of the die 21 may be a value obtained by subtracting the thickness of the pouch film 135 itself from the radius of curvature R2 of the punch edge 161. For example, if the thickness of the pouch film 135 is 0.2 mm, and the radius of curvature of the edge 213 of the die 21 is 0.5 mm or less, the radius of curvature of the die edge 162 is 0.7 mm or less.

[0104] In particular, as described above, two cup portions 133 may be formed in one pouch film 135, and a bridge 136 may also be formed between the two cup portions 133. That is, the pouch-type battery case 13 according to one embodiment of the present invention includes a first case 131 and a second case 132, each of which has a cup portion 133 formed therein that accommodates an electrode assembly 10 formed by stacking an electrode 101 and a separator 102, and a bridge 136 formed between the two cup portions 133. Since the bridge 136 is also formed corresponding to the partition wall 212 of the die 21, the bridge 136 may be one type of die edge 162.

[0105] According to one embodiment of the present invention, the formability of the pouch film 135 is improved, so that the bridges 136 may have a thickness of 1 / 200 to 1 / 30 of the width of the electrode assembly 10. If the thickness t of the bridges 136 is less than 1 / 200 of the width of the electrode assembly 10, stress may be excessively concentrated on the bridges 136, causing cracks, whereas if the thickness t of the bridges 136 is more than 1 / 30 of the width of the electrode assembly 10, the bridges 136 may not be formed sharply, resulting in a decrease in energy density.

[0106] Specifically, the thickness t of the bridge 136 can be formed to be 2 mm or less, and particularly 1.4 mm or less. Here, the thickness t of the bridge 136 is preferably the distance between two boundary points P1 between the bridge 136 and the outer wall 1381 on the bridge 136 side, as shown in FIG. 5 . Specifically, it is preferably the distance between two bridge perpendicular lines V1 that pass through the boundary points P1 between the bridge 136 and the outer wall 1381 on the bridge 136 side, respectively, and are perpendicular to the bottom 1332. Therefore, when the bridge 136 has a constant radius of curvature, the radius of curvature of the bridge 136 can correspond to half the thickness t. That is, the radius of curvature of the bridge 136 may be 1 mm or less, and particularly 0.7 mm or less.

[0107] For this reason, the partition wall 212 of the forming unit 211 may be rounded to a predetermined radius of curvature. In this case, it is preferable that the slope is continuous at the boundary point P1 between the bridge 136 and the outer wall 1381 on the bridge 136 side. Here, the radius of curvature of the upper surface of the partition wall 212 of the forming unit 211 may be a value obtained by subtracting the thickness of the pouch film 135 itself from the radius of curvature of the bridge 136. For example, if the thickness of the pouch film 135 is 0.2 mm, and the radius of curvature of the upper surface of the partition wall 212 is 0.5 mm or less, the radius of curvature of the bridge 136 is 0.7 mm or less.

[0108] According to an embodiment of the present invention, even if the radius of curvature of the edge 213 of the die 21 is reduced and the thickness of the partition 212 is thinned, the depth D of the cup portion 133 can be formed to be 6.5 mm or less, thereby preventing cracks from easily occurring in the die edge 162 and the bridge 136. The bridge 136 may have a fan-shaped cross section, and the more the outer wall 138 of the cup portion 133 is formed to be closer to vertical, the more the cross section may have a shape closer to a semicircle.

[0109] Furthermore, as the formability of the pouch film 135 is improved, the clearance CL can be reduced to 0.5 mm or less, and all of the outer walls 138 can be formed nearly vertical. For example, as shown in Fig. 5, among the outer walls 138, the outer wall 1381 on the bridge 136 side can be formed nearly vertical. That is, the clearance CL, which is the vertical distance between a bridge vertical line V1 that passes through a boundary point P1 between the bridge 136 and the outer wall 1381 on the bridge 136 side and is perpendicular to the bottom 1332, and an edge vertical line V2 that passes through a boundary point P2 between the punch edge 1611 on the bridge 136 side and the outer wall 1381 on the bridge 136 side and is perpendicular to the bottom 1332, may be 0.5 mm or less, particularly 0.35 mm or less.

[0110] 6, the outer wall 1382 of the plurality of outer walls 138 on the die edge 162 side may also be formed nearly vertical. That is, a clearance CL, which is a vertical distance between a die edge vertical line V4 that passes through a boundary point P3 between the die edge 162 and the outer wall 1382 on the die edge 162 side and is perpendicular to the bottom 1332, and an edge vertical line V2 that passes through a boundary point P4 between the punch edge 1612 on the die edge 162 side and the outer wall 1382 on the die edge 162 side and is perpendicular to the bottom 1332, may be 0.5 mm or less, and in particular 0.35 mm or less.

[0111] As a result, the depth D of the cup portion 133 can be formed to be 6.5 mm or less, and the outer wall 138 of the cup portion 133 can be inclined from the bottom 1332 at an angle of 90° to 95°. Even if the outer wall 138 is formed nearly vertically at an angle of 90° to 93°, it is possible to prevent cracks from occurring in the battery case 13. In addition, since the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10 is also reduced, the energy density per volume of the secondary battery 1 can also be increased.

[0112] On the other hand, since the radius of curvature R2 of the punch edge 161 of the cup portion 133 can be further reduced, damage to the electrode 101 of the electrode assembly 10 can be prevented even if the electrode assembly 10 is positioned very close to the outer wall 138 of the cup portion 133.

[0113] To this end, a manufacturing method of a pouch-type secondary battery 1 according to one embodiment of the present invention may include the steps of: laminating an electrode 101 and a separator 102 to form an electrode assembly 10; manufacturing a pouch-type battery case 13 by molding a pouch film 135 to form a cup portion 133; accommodating the electrode assembly 10 in an accommodating space 1331 of the cup portion 133; and manufacturing a pouch-type secondary battery 1 by sealing a side 134 formed extending outward from the cup portion 133.

[0114] In particular, in the step of housing the electrode assembly 10, the difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 may be 2.5 mm or less, and particularly 1.7 mm or less. Here, the width EW of the electrode assembly 10 may refer to the width of the electrode 101. That is, the peripheral portion 1021 of the separator 102 protruding beyond the electrode 101 may be excluded from the calculation of the width EW.

[0115] In addition, the electrode assembly 10 can be stored so that at least one end of the electrode 101 passes through the boundary point P2 between the punch edge 161 and the outer wall 138 and is positioned at a vertical distance g of 0.75 mm, particularly 0.5 mm or less, from an edge vertical line V2 perpendicular to the bottom 1332.

[0116] Specifically, as shown in FIGS. 5 and 6 , an imaginary edge perpendicular line V2 is shown, passing through boundary point P2 between the punch edge 161 and the outer wall 138 and perpendicular to the bottom 1332. The electrode assembly 10 is then housed so that at least one end of the electrode 101 is positioned at a vertical distance g of 0.75 mm or less, particularly 0.5 mm or less, from the edge perpendicular line V2. More specifically, an imaginary reference perpendicular line V3 is shown, perpendicular to the bottom 1332 and at a vertical distance g of 0.75 mm, particularly 0.5 mm, from the edge perpendicular line V2. Since the radius of curvature R2 of the punch edge 161 may be 0.7 mm or less, the reference perpendicular line V3 may pass through the center of curvature C of the punch edge 161. The electrode assembly 10 is then housed so that one end of the electrode 101 is positioned between the edge perpendicular line V2 and the reference perpendicular line V3. This may be confirmed by disassembling the secondary battery 1 itself, but is not limited thereto, and may be confirmed by various methods without disassembling the secondary battery 1, such as computerized tomography (CT), magnetic resonance imaging (MRI), or X-ray. This can further increase the volume ratio of the electrode assembly 10 to the volume of the cup portion 133 while preventing damage to the electrode 101, thereby improving the energy efficiency relative to volume. In addition, since unnecessary volume inside the cup portion 133 is reduced, movement of the electrode assembly 10 inside the cup portion 133 can be prevented.

[0117] Furthermore, since the electrode assembly 10 can be accommodated so as to be positioned very close to the outer wall 138 of the cup portion 133, the separator 102 does not wrinkle or fold randomly. As shown in Fig. 5, a peripheral portion 1021 of the separator 102 that protrudes outward from the electrode 101 can be folded from one end of the electrode 101 toward the opposite direction of the bottom portion 1332. The electrode assembly 10 is formed by stacking the electrode 101 and the separator 102, and multiple electrodes 101 and multiple separators 102 can be formed. When the battery case 13 includes a first case 131 and a second case 132, and the bridge 136 of the battery case 13 is folded and the upper portion of the electrode assembly 10 is housed in the cup portion 133, the peripheral portion 1021 of the separator 102 housed in the cup portion 133 of the first case 131 may be folded toward the second case 132, and the peripheral portion 1021 of the separator 102 housed in the cup portion 133 of the second case 132 may be folded toward the first case 131. As a result, the peripheral portions 1021 of the separators 102 are folded in an aligned manner, thereby maintaining order. In addition, the separator 102 covers the electrodes 101 so that they are not exposed to the outside, thereby preventing short circuits from occurring.

[0118] More specifically, before the electrode assembly 10 is placed in the cup portion 133, the width of the separator 102 may be wider than the width CW of the cup portion 133. Therefore, during the process of placing the electrode assembly 10 in the cup portion 133, the peripheral portion 1021 of the separator 102 may contact the inner peripheral edge of the cup portion 133 and be folded in a certain direction.

[0119] The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 may be as small as 2.5 mm or less, particularly 1.7 mm or less. Therefore, a process may be required to easily fold the peripheral portion 1021 of the separator 102 when the electrode assembly 10 is accommodated in the cup portion 133.

[0120] Therefore, the step of accommodating the electrode assembly 10 in the receiving space 1331 of the cup part 133 may include a process of pressing the electrode assembly 10 into the cup part 133. As a result, compared to the conventional method of placing the electrode assembly 10 in a cup part, the separator 102 can be folded in a certain direction while maintaining a small difference between the width CW of the cup part 133 and the width EW of the electrode assembly 10, thereby allowing the electrode assembly 10 to be easily and reliably accommodated in the receiving space 1331 of the cup part 133.

[0121] In addition, the step of accommodating the electrode assembly 10 in the receiving space 1331 of the cup portion 133 may further include a process of folding each corner (vertex) of the plurality of separators 102 in the electrode assembly 10 by heat and pressure before pressing the electrode assembly 10 into the cup portion 133. This process may be performed by using a separate sealing tool to fold each corner (vertex) of the plurality of separators 102 so that they converge to the center of the electrode assembly 10 in the stacking direction.

[0122] That is, the electrode assembly 10 can be inserted into the cup portion 133 with the four corners of the separator 102 already aligned. Thus, the electrode assembly 10 can be smoothly inserted into the receiving space 1331 of the cup portion 133.

[0123] As described above, according to one embodiment of the present invention, the improved formability of the pouch film 135 allows the thickness t of the bridge 136 to be made thinner, and the radius of curvature R2 and clearance CL of the edge 16 of the cup portion 133 to be made smaller, thereby increasing the volume of the electrode assembly 10. Therefore, unnecessary volume in the secondary battery 1 is also reduced, thereby increasing the energy density per volume. Furthermore, the pouch-type battery case 13 and the pouch-type secondary battery 1 can be manufactured with an overall sharp shape, resulting in a beautiful appearance of the secondary battery 1 and improved merchantability.

[0124] 7 is a schematic top view illustrating the electrode assembly 10 accommodated in the cup portion 133 according to an embodiment of the present invention. According to an embodiment of the present invention, as described above, the radius of curvature R2 of the punch edge 161 of the cup portion 133 can be further reduced, and therefore the electrode assembly 10 is accommodated so that one end of the electrode 101 is positioned between the edge perpendicular line V2 and the reference perpendicular line V3. Therefore, even if the electrode assembly 10 is positioned very close to the outer wall 138 of the cup portion 133, damage to the electrode 101 of the electrode assembly 10 can be prevented.

[0125] The edge perpendicular line V2 and the reference perpendicular line V3 may also be shown on the punch edge 1611 on the bridge 136 side, and on the punch edge 1612 on the die edge 162 side. The vertical distance g between such edge perpendicular line V2 and the reference perpendicular line V3 may be 0.75 mm, particularly 0.5 mm.

[0126] Furthermore, since the battery case 13 has two cup portions 133 and a bridge 136, a bridge vertical line V1 can be formed on one side of the cup portion 133 and a die edge vertical line V4 can be formed on the other side. The vertical distance CL between the bridge vertical line V1 and the edge vertical line V2 may be 0.5 mm or less, particularly 0.35 mm or less, and the vertical distance CL between the die edge vertical line V4 and the edge vertical line V2 may also be 0.5 mm or less, particularly 0.35 mm or less.

[0127] However, if only one cup portion 133 is formed in the battery case 13, no bridge exists. However, since die edges 162 are formed on both sides of the cup portion 133, die edge vertical lines V4 can be shown on both sides of the cup portion 133.

[0128] When two cup portions 133 are formed in the battery case 13, the width CW of the cup portion 133 can be regarded as the vertical distance from the bridge vertical line V1 to the die edge vertical line V4. However, when only one cup portion 133 is formed, the width CW of the cup portion 133 can also be regarded as the vertical distance between the two die edge vertical lines V4.

[0129] The bridge vertical line V1 and the die edge vertical line V4 both pass through the upper end of the outer wall 138 of the cup portion 133. Therefore, according to one embodiment of the present invention, the width CW of the cup portion 133 may be the vertical distance between the upper ends of the outer walls 138 on both sides of the cup portion 133. The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 may be 2.5 mm or less, particularly 1.7 mm or less. And, as described above, the width EW of the electrode assembly 10 may be 60 mm or more.

[0130] In the battery case 13, the width CW of the cup portion 133 can be determined by measuring the vertical distance between the upper ends of the outer walls 138 of the cup portion 133. In the secondary battery 1, the width CW can be determined by using a laser displacement sensor or the like to determine the position between the upper ends of the outer walls 138 from outside the cup portion 133 and calculating the distance between the two positions. In this case, a laser displacement sensor or the like irradiates a laser from outside the cup portion 133 and moves from the side 134 toward the die edge 162 and the outer wall 138. When a point where the displacement changes suddenly is detected, that point can be recognized as the upper end of the outer wall 138. The above describes one example of a method for measuring the width CW of the cup portion, and the scope of the present invention is not necessarily limited to this measurement method. Any cup width CW that falls within the scope of the claims and the spirit of the present invention can be the cup width CW defined in the present invention.

[0131] 8 is a schematic diagram showing a conventional corner 364, and FIG. 9 is a schematic diagram showing a corner 164 according to one embodiment of the present invention. The edge 16 of the cup portion 133 includes not only a punch edge 161 and a die edge 162, but also a thickness edge 163 connecting two adjacent outer walls 138 of the cup portion 133, as shown in FIG. 9. The thickness edge 163 is formed in the thickness direction of the cup portion 133 and is formed by stretching the pouch film 135 between a corner of the forming portion 211 of the die 21 and a corner of the punch 22 when the pouch film 135 is stretched. At least one of the thickness edges 163 may also be rounded.

[0132] The radius of curvature of the thickness edge 163 may be the same as or different from the radius of curvature R2 of the two adjacent punch edges 161, i.e., the first punch edge 1613 and the second punch edge 1614. For example, as described above, while the depth D of the cup portion 133 is formed to be 6.5 mm or less, at least one punch edge 161 may be rounded with a radius of curvature of 1 mm or less, particularly 0.7 mm or less, and at least one thickness edge 163 may be rounded with a radius of curvature of 0.5 mm to 5 mm, particularly 0.5 mm to 2 mm. Conventionally, when the thickness edge 363 is rounded with a radius of curvature of 5 mm or less, particularly 2 mm or less, stress may be concentrated in the thickness edge 363 of the cup portion 333, which may result in cracks. However, according to one embodiment of the present invention, cracks may be prevented from occurring in the thickness edge 163 of the cup portion 133. In this case, one of the first punch edge 1613 and the second punch edge 1614 may be a punch edge 1611 on the bridge 136 side, and the other may be a punch edge (not shown) on the electrode lead 12 side. Alternatively, one of the two may be a punch edge 1612 on the die edge 162 side, and the other may be a punch edge (not shown) on the electrode lead 12 side.

[0133] As shown in Fig. 9, the thick edge 163 is connected to two adjacent punch edges 161, i.e., a first punch edge 1613 and a second punch edge 1614, to form a corner 164. Conventionally, as shown in Fig. 8, all of the edges 221 of the punch 22 are rounded with the same radius of curvature, and as a result, the corners (not shown) of the punch 22 are also naturally rounded with the same radius of curvature. Therefore, when the pouch film 135 is formed using such a punch 22 and stretched, the corner 364 is also naturally rounded with the same radius of curvature as the punch edge 361.

[0134] However, when the pouch film 135 is stretched, there is a problem in that stress is concentrated at the corner 364. In particular, since the corner 364 is formed by the intersection of three edges 361, it is stretched more than the punch edge 361 or the thickness edge 363, and therefore stress is concentrated more at the corner 364 than at the punch edge 361 or the thickness edge 363. Therefore, there is a problem in that the pouch film 135 is stretched too much, and a whitening phenomenon occurs in which certain parts turn white just before cracks occur, which makes it more likely for cracks to occur.

[0135] Therefore, according to one embodiment of the present invention, as shown in FIG. 12, at least one of the corners 164 is also formed to be rounded, and the radius of curvature of such corner 164 may be greater than or equal to the radius of curvature of at least one of the punch edge 161 and the thickness edge 163.

[0136] Specifically, according to an embodiment of the present invention, the radius of curvature may vary within the corner 164. That is, the radius of curvature of the center 1641 of the corner 164 may be different from the radius of curvature of the peripheral portion 1642 of the corner 164. In particular, the radius of curvature of the center 1641 of the corner 164 may be greater than the radius of curvature of the peripheral portion 1642 of the corner 164. For example, the radius of curvature of the peripheral portion 1642 of the corner 164 may be the same as the radius of curvature of at least one of the punch edge 161 and the thickness edge 163 because the peripheral portion 1642 is relatively adjacent to the first punch edge 1613, the second punch edge 1614, and the thickness edge 163. In contrast, the radius of curvature of the center 1641 of the corner 164 may be greater than the radius of curvature of at least one of the punch edge 161 and the thickness edge 163 because the center 1641 is relatively far from the first punch edge 1613, the second punch edge 1614, and the thickness edge 163. That is, the corner 164 may have a radius of curvature equal to or greater than the radius of curvature of at least one of the punch edge 161 and the thickness edge 163 .

[0137] Therefore, the radius of curvature of the corner 164 may gradually increase from the peripheral portion 1642 of the corner 164 to the center portion 1641 of the corner 164. As described above, since the radius of curvature is not constant but varies within the corner 164, the center portion 1641 of the corner 164 may have an aspherical shape rather than a precise spherical shape.

[0138] Unlike the punch edge 161, the corner 164 must be clearly defined not only in terms of the radius of curvature but also in terms of the area within the cup portion 133. If the area within the cup portion 133 within which the corner 164 is formed is too narrow, the pouch film 135 may be excessively stretched, resulting in problems such as whitening or cracking. In contrast, if the area within the cup portion 133 within which the corner 164 is formed is too wide, the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10 may be reduced, thereby increasing the energy density per volume of the secondary battery 1. Therefore, according to one embodiment of the present invention, as shown in FIG. 12 , the corner 164 may be formed within 2 mm to 3.5 mm from the thick edge 163 in the length direction lc of the cup portion 133, 2 mm to 3.5 mm from the thick edge 163 in the width direction wc of the cup portion 133, and 2 mm to 3.5 mm from the punch edge 161 in the thickness direction dc of the cup portion 133. The area where the corner 164 is formed may gradually increase as the depth D of the cup portion 133 increases.

[0139] By forming the corners 164 of the cup portion 133 as described above, stress concentrated at the corners 164 can be further dispersed, thereby preventing problems such as whitening and cracks.

[0140] FIG. 10 is a schematic diagram showing how a battery case 13 according to one embodiment of the present invention is folded, and FIG. 11 is a schematic diagram showing how a battery case 13 according to one embodiment of the present invention is folded.

[0141] When the two cup portions 133 are formed in the pouch film 135, the first case 131 and the second case 132 of the battery case 13 each have a cup portion 133. After the electrode assembly 10 is accommodated in the receiving space 1331 of the cup portion 133 of the first case 131, the bridge 136 formed between the two cup portions 133 of the battery case 13 is folded so that the two cup portions 133 face each other, as shown in FIG. 10 . By folding the bridge 136, a folding portion 139 is formed on one side of the secondary battery 1. An electrolyte is then injected inside, and the sides 134 extending outward from the cup portions 133 of the first case 131 and the second case 132 are sealed, thereby manufacturing a pouch-type secondary battery 1 as shown in FIG. 11 .

[0142] The pouch-type secondary battery 1 according to one embodiment of the present invention thus manufactured includes an electrode assembly 10 formed by stacking an electrode 101 and a separator 102, and a pouch-type battery case 13 having a cup portion 133 formed therein for accommodating the electrode assembly 10. The cup portion 133 may include a plurality of punch edges 161 connecting a plurality of outer walls 138 surrounding the periphery and a bottom portion 1332. At least one of the punch edges 161 may be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one of the punch edges 161 may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less. The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 may be 2.5 mm or less, particularly 1.7 mm or less. The electrode assembly 10 may have at least one end of the electrode 101 positioned at a vertical distance g of 0.75 mm, particularly 0.5 mm or less, from an edge vertical line V2 that passes through a boundary point P2 between the punch edge 161 and the outer wall 138 and is perpendicular to the bottom 1332. The battery case 13 may include a first case 131 and a second case 132, each having at least one cup portion 133 formed therein, and a folding portion 139 that integrally connects the first case 131 and the second case 132.

[0143] When the battery case 13 is folded to manufacture the secondary battery 1, the bridge 136 becomes the folding section 139, and therefore the folding section 139 integrally connects the first case 131 and the second case 132 in the secondary battery 1. The punch edge 1611 on the bridge 136 side becomes the punch edge 1611 on the folding section 139 side, and the outer wall 1381 on the bridge 136 side becomes the outer wall 1381 on the folding section 139 side.

[0144] Among the plurality of punch edges 161, a punch edge 1611 on the folding portion 139 side, which connects the outer wall 1381 on the folding portion 139 side and the bottom portion 1332 toward the folding portion 139 side, may be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1611 on the folding portion 139 side may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less. In the electrode assembly 10, at least one end of the electrode 101 may be positioned between an edge vertical line V2 that passes through a boundary point P2 between the punch edge 161 and the outer wall 138 and is perpendicular to the bottom portion 1332, and a reference vertical line V3 that is perpendicular to the bottom portion 1332 and has a vertical distance g of 0.75 mm, particularly 0.5 mm, from the edge vertical line V2. As described above, such a reference vertical line V3 can pass through the center of curvature C of the punch edge 161.

[0145] FIG. 12 is an enlarged view of a groove 1391 formed in a battery case 13 according to one embodiment of the present invention. According to one embodiment of the present invention, as described above, when the battery case 13 is folded to manufacture the secondary battery 1, the bridge 136 may take the form of the folding portion 139. Specifically, when the battery case 13 is folded, the rounded shape of the bridge 136 also unfolds to a certain extent, and a trace of the bridge 136 remains on the secondary battery 1, and this trace may become the folding portion 139. Therefore, the bridge 136 and the folding portion 139 of the battery case 13 may correspond to each other.

[0146] For example, if the rounded shape of the bridge 136 does not fully unfold in a plane, the folding portion 139 is formed to include a groove 1391 recessed into the inside of the secondary battery 1, as shown in Fig. 12. In this case, the folding portion 139 has a smaller curvature than the bridge 136, and therefore can have a larger radius of curvature.

[0147] Because the bridge 136 has a curved surface and the outer wall 1381 on the bridge 136 side has a flat shape, the deformation amounts are different. Therefore, when the battery case 13 is folded, the outer wall 1381 on the bridge 136 side deforms relatively more, while the bridge 136 deforms relatively less, only to the extent that its rounded shape unfolds to a certain extent. Then, when the battery case 13 is folded, as shown in FIG. 12 , the amount of change in the slope switches between increasing and decreasing around the boundary point P1. That is, the boundary point P1 becomes an inflection point. Therefore, the folding portion 139 can be formed on the curved surface between the two boundary points P1, i.e., the two inflection points.

[0148] Furthermore, if the rounded shape of the bridge 136 is not fully developed on a plane, the two boundary points P1, i.e., the portions corresponding to the two inflection points, may protrude outward to form protrusions. That is, the protrusions may be formed as a pair of protrusions protruding outward with the folding portion 139, more specifically, the groove 1391, interposed therebetween.

[0149] Alternatively, even if the rounded shape of bridge 136 is fully unfolded on a plane, the boundary point P1 between bridge 136 and the outer wall 1381 on the bridge 136 side will form two lines (not shown) on secondary battery 1, and folding portion 139 will be formed on the plane between these two lines.

[0150] The folding portion 139 can also be seen with the naked eye from the exterior of the secondary battery 1. As described above, the thickness t of the bridge 136 is preferably the distance between the two boundary points P1 between the bridge 136 and the outer wall 1381 on the bridge 136 side, and therefore the width FW of the folding portion 139 is the distance between the two boundary points P1. That is, when the rounded shape of the bridge 136 is not fully unfolded on a plane, the width FW of the folding portion 139 is the distance between the two boundary points P1, i.e., the two inflection points. Alternatively, when the rounded shape of the bridge 136 is fully unfolded on a plane, the width FW of the folding portion 139 is the distance between the two boundary points P1, i.e., the two lines.

[0151] The width FW of the folding portion 139 may be 1 mm to 3.2 mm, particularly 1 mm to 1.6 mm, without exceeding the length of the bridge 136. As described above, the width FW of the folding portion 139 may be measured directly using a ruler, or may be measured using a magnifying glass, a 3D camera, or a laser 2D line sensor, and may be measured in various ways without limitation.

[0152] In the past, the thickness t' of the bridge 336 was large and the width of the folding portion 339 was also large, resulting in a large space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10. However, according to one embodiment of the present invention, the width FW of the folding portion 139 can be reduced, thereby reducing the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10. As a result, the energy density per volume of the secondary battery 1 can be increased.

[0153] In addition, in the past, the protrusions protruded significantly outward due to the poor formability of the pouch film. However, according to one embodiment of the present invention, the protrusions can protrude relatively less, thereby improving the flatness of the folding portion 139 or the outer wall 1381 on the folding portion 139 side.

[0154] Specifically, the distance p between the innermost portion of the groove 1391 and the outermost portion of the protrusion can be defined as the flatness. In the case of a conventional battery case, the flatness is 1 mm or more, and even up to 1.5 mm. In contrast, according to an embodiment of the present invention, the flatness p can be 0.8 mm or less, preferably 0.3 mm or less. As a result, the energy density per volume of the secondary battery 1 can be further increased.

[0155] 13 is an enlarged schematic view of a cup portion 133 and a die edge 1621 according to another embodiment of the present invention. According to one embodiment of the present invention, two molding portions 211 are formed adjacent to each other in the die 21, and a partition wall 212 may be formed between the two molding portions 211. Therefore, when the pouch film 135 is formed, two cup portions 133 are formed in one pouch film 135, and a bridge 136 is also formed between the two cup portions 133. That is, one cup portion 133 is formed in each of the first case 131 and the second case 132.

[0156] According to another embodiment of the present invention, only one molding portion 211 is formed in the die 21, and no partition wall is present. Therefore, when the pouch film 135 is molded, one cup portion 133 is formed in one pouch film 135, and no bridge is present. That is, the cup portion 133 is formed only in the first case 131.

[0157] According to another embodiment of the present invention, the depth D of the cup portion 133 may be formed to be 6.5 mm or less, and at least one punch edge 161a of the cup portion 133 may be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one punch edge 161a of the cup portion 133 may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less. This can prevent cracks from easily occurring in the punch edge 161a of the cup portion 133.

[0158] 13, among the plurality of punch edges 161a, a punch edge 1611a on the second case 132a side connecting an outer wall 1381a on the second case 132a side and the bottom portion 1332 facing the second case 132a side may be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1611a on the second case 132a side may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less.

[0159] Furthermore, the punch edge 1612 on the die edge 162 side may also be rounded with a radius of curvature of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1612 on the die edge 162 side may be rounded with a radius of curvature of 1 mm or less, particularly 0.7 mm or less. In this case, it is preferable that the inclination is continuous at a boundary point P2 between the punch edge 161a and the outer wall 138.

[0160] Hereinafter, the description of other embodiments of the present invention that overlap with the description of one embodiment of the present invention will be omitted, but this is for the convenience of explanation and is not intended to limit the scope of the rights.

[0161] FIG. 14 is a schematic diagram showing a state in which a battery case 13a according to another embodiment of the present invention is folded, and FIG. 15 is a schematic diagram showing a state in which a battery case 13a according to another embodiment of the present invention is folded.

[0162] The upper end of the outer wall 138 faces the opening of the cup portion 133, and the second case 132a, the side 134, and the vent portion 137 extend outside the cup portion 133. In this case, the die edge 162 connecting the upper end of the outer wall 138 to the second case 132a, the side 134, or the vent portion 137 may also be rounded with a curvature radius of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the die edge 162 may be rounded with a curvature radius of 1 mm or less, particularly 0.7 mm or less.

[0163] That is, according to another embodiment of the present invention, as shown in Fig. 14, there is no bridge in the battery case 13a, and the die edge 1621 connects the cup portion 133 of the first case 131 and the second case 132a to each other. To this end, the edge 213 of the die 21 may be rounded with a curvature radius obtained by subtracting the thickness of the pouch film 135 from the die edge 162. For example, if the thickness of the pouch film 135 is 0.2 mm, the edge 213 of the die 21 may be rounded with a curvature radius of 0.8 mm or less, particularly 0.5 mm or less.

[0164] Furthermore, the clearance CL may be reduced to 0.5 mm or less, so that the outer wall 138 of the cup portion 133 is nearly vertical. For example, as shown in Fig. 13, the clearance CL, which is the vertical distance between a die edge vertical line V4 that passes through a boundary point P1 between the die edge 1621 and the outer wall 1381a on the second case 132a side and is perpendicular to the bottom 1332, and an edge vertical line V2 that passes through a boundary point P2 between the punch edge 1611a on the second case 132a side and the outer wall 1381a on the second case 132a side and is perpendicular to the bottom 1332, may be 0.5 mm or less, particularly 0.35 mm or less.

[0165] In addition, the electrode assembly 10 can be stored so that one end of the electrode 101 is positioned between the edge vertical line V2 and a reference vertical line V3 that is perpendicular to the bottom 1332 and has a vertical distance of 0.75 mm, particularly 0.5 mm, from the edge vertical line V2.

[0166] Therefore, according to another embodiment of the present invention, the depth D of the cup portion 133 is formed to be 6.5 mm or less, and the outer wall 138 of the cup portion 133 is formed nearly vertically with an inclination angle of 90° to 95°, particularly 90° to 93°, from the bottom 1332. This prevents damage to the electrode 101, and further increases the volume ratio of the electrode assembly 10 compared to the volume of the cup portion 133, thereby improving the energy efficiency relative to volume.

[0167] 16 is an enlarged view of a groove 1391a formed in a battery case 13a according to another embodiment of the present invention. According to this embodiment, when the battery case 13a is folded to manufacture a secondary battery 1a, the die edge 1621 on the second case 132a side becomes the folding portion 139a. Specifically, when the battery case 13a is folded, the rounded shape of the die edge 1621 also unfolds, and a trace of the die edge 1621 remains on the secondary battery 1a, which becomes the folding portion 139a. Therefore, the die edge 1621 on the second case 132a side of the battery case 13a corresponds to the folding portion 139a.

[0168] For example, if the rounded shape of the die edge 1621 does not fully unfold into a plane, the folding portion 139a will be formed to include a recess 1391a that is recessed into the inside of the secondary battery 1a, as shown in Fig. 19. In this case, the folding portion 139a may have a smaller curvature than the die edge 1621 and therefore a larger radius of curvature.

[0169] Because the die edge 1621 has a curved surface and the outer wall 1381a on the die edge 1621 side has a flat shape, the deformation amounts are different. Therefore, when the battery case 13 is folded, the outer wall 1381a on the die edge 1621 side deforms relatively more, while the die edge 1621 deforms relatively less, only enough to allow its rounded shape to unfold to a certain extent. Then, when the battery case 13 is folded, as shown in FIG. 19, the amount of change in the slope switches between increasing and decreasing around the boundary point P1. That is, the boundary point P1 becomes an inflection point. Therefore, the folding portion 139a is formed on the curved surface between the two boundary points P1, i.e., the two inflection points.

[0170] Alternatively, even if the rounded shape of the die edge 1621 is fully unfolded in a plane, the boundary point P1 between the die edge 1621 and the outer wall 1381 on the second case 132a side and the boundary point between the die edge 1621 and the second case 132a form two lines (not shown) on the secondary battery 1a, and the folding portion 139a is formed on the plane between these two lines. The width FW of the folding portion 139 does not exceed the length of the die edge 1621 and may be 1 mm to 3.2 mm, and particularly 1 mm to 1.6 mm.

[0171] FIG. 17 is a schematic diagram showing a conventional battery case 33 from above before the gas vent portion 337 is cut. The bridge 136 of the battery case 13 is folded to form a folding portion 139 on one side of the secondary battery 1, and this folding portion 139 integrally connects the first case 131 and the second case 132. The battery case 13 is formed by draw-molding a pouch film 135. During this process, not only the cup portion 133 is stretched in a limited manner, but also the surrounding sides 134 of the cup portion 133 are slightly stretched overall. Therefore, when the bridge 136 is folded, the slightly stretched portions of the sides 134 accumulate and visibly protrude outward from both ends of the folding portion 139. This is called a bat ear 35 or 15.

[0172] The size of the bat ears 35 varies depending on the thickness t' of the bridge 336, the clearance CL', the radius of curvature R2' of the punched edge 361 of the cup portion 333, and the depth D' of the cup portion 333. That is, the thicker the thickness t' of the bridge 336, the larger the clearance CL', and the larger the radius of curvature R2' of the punched edge 361 of the cup portion 333, the larger the size of the bat ears 35. However, in the past, there was a limit to how much the thickness t' of the bridge 336, the radius of curvature R2' of the punched edge 361 of the cup portion 333, and the clearance CL' could be improved. Therefore, as shown in FIG. 17, the size of the bat ears 35 was formed to be quite large, and there was also a limit to how much it could be reduced.

[0173] If the bat ears 35 are made larger, unnecessary volume of the secondary battery 3 increases, resulting in a discrepancy between the design values ​​and actual values ​​of the shape and size of the secondary battery 3. Therefore, when assembling the secondary battery 3 into the battery module 5 (shown in FIG. 24), assembly is not easy, and there is a problem that the size of the secondary battery 3 must be designed small from the beginning, taking into account the bat ears 35. In addition, there is a problem that the energy density per volume decreases as the volume of the secondary battery 3 increases.

[0174] Meanwhile, as described above, the pouch-type battery case 13 according to one embodiment of the present invention includes a cup portion 133 having an accommodating space 1331 for accommodating the electrode assembly 10, and a gas vent portion 137 formed on one side of the cup portion 133 and for discharging gas generated inside the cup portion 133 through a gas vent hole H.

[0175] Then, a formation process and a degassing process can be performed during the process of sealing the side 134. Specifically, after the electrode assembly 10 is housed in the cup portion 133, the edge 1371 included in the degassing portion 137 of the battery case 13 can be opened, and the remaining side 134 can be sealed. Once the edge 1371 of the battery case 13 is opened to form an opening, an electrolyte solution can be injected into the battery case 13 through the opening.

[0176] After the electrolyte is poured into the battery case 13, the gas vent portion 137 is primarily sealed to form the temporary seal portion 1340. Since the gas vent portion 137 will be secondarily sealed later to form the seal portion 1341, the temporary seal portion 1340 is preferably formed in a position close to the edge 1371 of the gas vent portion 137.

[0177] Thereafter, an activation process (formation process) can be performed. The activation process (formation process) is a process for finally completing charging so that the secondary battery 1 can supply power. Since the activation process is performed after the temporary seal portion 1340 is formed and the battery case 13 is completely sealed, the charging rate is high, gas is quickly discharged, and the production of the secondary battery 1 can be completed within a specified process time.

[0178] After the activation process is completed, gas is generated inside the battery case 13. Therefore, a vent hole H is punched in the vent portion 137 of the battery case 13. The gas is discharged from the inside of the battery case 13 to the outside through the vent hole H. At this time, as the gas is easily discharged, the injected electrolyte may leak through the vent hole H. To prevent this, the vent hole H is preferably punched in a position close to the temporary seal portion 1340. After the vent hole H is punched, a degassing process is performed to discharge the gas to the outside of the battery case 13.

[0179] When the gas vent hole H is punched out, the interior of the battery case 13 is opened again, and the electrolyte inside may leak to the outside. Therefore, the boundary between the cup portion 133 and the gas vent portion 137 is secondarily sealed to form the seal portion 1341. In this case, the seal portion 1341 is preferably formed between the cup portion 133 and the gas vent hole H, and particularly preferably formed in a position close to the cup portion 133.

[0180] In this way, the vent holes H must be punched and the primary and secondary seals must be performed while the activation and venting processes are being performed. Furthermore, when mass-producing secondary batteries 1, it is necessary to centrally manage the specifications and quality of the secondary batteries 1. For this purpose, the battery case 13 or the secondary battery 1 can be inspected using an inspection device 4 (shown in FIG. 19) that includes a vision sensor 41.

[0181] Conventionally, there has been a limit to how well the battery case 33 and secondary battery 3 can be manufactured to have a sharp overall shape. Therefore, when the battery case 33 is photographed using a vision sensor, there are large errors in the size and position of each component.

[0182] Specifically, once the secondary batteries 1 are manufactured, the electrode leads 12 of the secondary batteries 1 can be connected to one another to manufacture a battery module 5 (shown in FIG. 24). For this reason, the positions of the electrode leads 12 formed on the secondary batteries 1 must all be consistent. Conventionally, the electrodes 101 are positioned at a certain distance from the outer wall 338 of the cup portion 333, which allows the electrode assembly 10 to move within the cup portion 333 before the side 134 is sealed. Therefore, when secondary batteries 3 are mass-produced, even if the volumes of the cup portion 333 and the electrode assemblies 10 are consistent, the positions of the electrode assemblies 10 and the electrode leads 12 vary slightly. Therefore, the positions of the electrode leads 12 must be accurately measured using the inspection device 4.

[0183] Furthermore, in order to punch out the gas vent hole H in the correct position and size and to perform the primary and secondary seals in the correct position and size, the position of the gas vent portion 137 must be accurately measured. Additionally, in order to efficiently manage the overall quality of a plurality of secondary batteries 1, the positions of various components of the battery case 13 or secondary battery 1, such as the side 134, folding portion 139, and insulating portion 14 protruding from the battery case 13, and even the width between the cup portions 133 must be accurately measured.

[0184] To measure the position of a component, a specific reference line must be established, and the vertical distance from the reference line to the component to be measured must be measured. For example, when the electrode assembly 10 moves within the cup portion 333, it generally moves to the left or right of the reference shown in FIG. 17, i.e., toward the folding portion 339 and the vent portion 337. Therefore, to measure the position of the electrode lead 12, the position of the left or right edge of the electrode lead 12 must be measured, and a reference parallel to the left or right edge must be established to measure the vertical distance to the left or right edge.

[0185] However, in the past, because the outer wall 338 of the cup portion 333 was not formed nearly vertically and the radius of curvature R2' of the punch edge 361 of the cup portion 333 was also large, when the battery case 33 was photographed using the vision sensor 41, the punch edge 361 of the cup portion 333 did not appear clearly in the image, as shown in Figure 20. Therefore, the position of the above-mentioned components could not be measured using the punch edge 361 of the cup portion 333 as a reference, so the bat ears 35 close to the punch edge 361 were set as a reference, or the punch edge 361 of the cup portion 333 was manually set by the user.

[0186] However, since the bat ears 35 are formed by folding the bridge 136 while the peripheral side 134 of the cup portion 133 is also slightly stretched overall, the size of the bat ears 35 varies slightly for each of the multiple secondary batteries 1. As a result, even if the position of the above components is measured using a vision sensor, the size of the reference bat ears 35 varies, resulting in a large deviation in the position of the components between the secondary batteries 3, making quality control difficult.

[0187] In particular, even if the positions of the electrode leads 12 are measured by photographing the battery case 33 using a vision sensor, the positions of the electrode leads 12 vary slightly, making it difficult to connect the electrode leads 12 to manufacture the battery module 5. In addition, when stacking a plurality of secondary batteries 1 sequentially or aligning them in a row to manufacture the battery module 5, the position of the cup portion 333 is not accurate, resulting in a problem of poor alignment of the plurality of secondary batteries 1.

[0188] Furthermore, when manufacturing a battery module 5 by housing the secondary battery 3 in a separate housing 51 (shown in Figure 24), there is a problem that, due to the large deviation in the measurement values, the design tolerance is set unnecessarily large when designing the housing 51, which also reduces the energy density per volume of the battery module 5.

[0189] Figure 18 is a schematic diagram showing the state of a battery case 13 according to one embodiment of the present invention before cutting the gas vent portion 137, as viewed from above, and Figure 19 is a block diagram of an inspection device 4 according to one embodiment of the present invention.

[0190] 18, the formability of the pouch film 135 is improved, so that the thickness t of the bridge 136 can be made thinner, and the radius of curvature R2 and clearance CL of the punched edge 1611 of the cup portion 133 can be made smaller, thereby further reducing the size of the bat ears 15. Therefore, the secondary battery 1 can be easily assembled into the battery module 5, and unnecessary volume of the secondary battery 1 can be reduced, thereby increasing the energy density per volume.

[0191] 18, the punch edge 1611 of the cup portion 133 clearly appears in the image of the battery case 13, so the inspection device 4 can automatically set the punch edge 161 of the cup portion 133 as the reference line ST, and can accurately measure the distance to various components of the battery case 13 or secondary battery 1 based on the punch edge 161 of the cup portion 133, and can even accurately measure the width CW between the cup portions 133. As a result, the positions of the components of the battery case 13 or secondary battery 1 can be accurately measured, reducing measurement errors and deviations between secondary batteries 1.

[0192] To this end, the inspection device 4 for a battery case 13 or a secondary battery 1 according to one embodiment of the present invention includes a vision sensor 41 that photographs the battery case 13 to acquire an image of the battery case 13 or the secondary battery 1, an outline extraction unit 421 that extracts an outline of the configuration of the battery case 13 or the secondary battery 1 from the image, an image analysis unit 422 that analyzes the image and detects the outline corresponding to the punch edge 161 of the cup portion 133 in the battery case 13, which is provided with an accommodating space 1331 that accommodates the electrode assembly 10, a reference line setting unit 423 that sets the outline corresponding to the punch edge 161 as a reference line ST, and a distance calculation unit 424 that calculates the distance from the reference line ST to the configuration.

[0193] An inspection method for a battery case 13 or a secondary battery 1 according to one embodiment of the present invention using such an inspection device 4 includes the steps of: a vision sensor 41 photographing the battery case 13 and acquiring an image of the battery case 13 or the secondary battery 1; an outline extraction unit 421 extracting an outline of the configuration of the battery case 13 or the secondary battery 1 from the image; an image analysis unit 422 analyzing the image and detecting the outline corresponding to the punch edge 161 of the cup portion 133 in the battery case 13, which is provided with an accommodating space 1331 for accommodating the electrode assembly 10; a reference line setting unit 423 setting the outline corresponding to the punch edge 161 as a reference line ST; and a distance calculation unit 424 calculating the distance from the reference line ST to the configuration.

[0194] Specifically, as shown in FIG. 19, the inspection device 4 includes a vision sensor 41 and a control unit 42. These components are interconnected and capable of communicating with each other via a bus (not shown). All components included in the control unit 42 can be connected to the bus via at least one interface or adapter, or directly connected to the bus. The bus may also be connected to other subsystems in addition to the components described above. Such buses include a memory bus, a memory controller, a peripheral bus, and a local bus.

[0195] The vision sensor 41 captures an image by photographing a specific area and receiving an image signal for the specific area. To this end, the vision sensor 41 typically includes an imaging element such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) image sensor. In particular, the vision sensor 41 according to one embodiment of the present invention can photograph the battery case 13 after the bridge 136 of the battery case 13 is folded, and capture an image of each component of the battery case 13 or the secondary battery 1. Here, the components include the cup portion 133, the gas vent portion 137, the electrode leads 12, the bat ears 15, the side 134, the folding portion 139, and the insulating portion 14. The secondary battery 1 is then manufactured by later cutting the gas vent portion 137. Therefore, when the vision sensor 41 photographs the battery case 13 before cutting the gas vent portion 137, it can obtain images of the battery case 13 and the electrode lead 12, etc., and when the vision sensor 41 photographs the battery case 13 after cutting the gas vent portion 137, it can obtain an image of the secondary battery 1.

[0196] The control unit 42 receives the image signal acquired by the vision sensor 41 and determines the position of each component of the battery case 13 or the secondary battery 1 from the image signal. The control unit 42 includes an outline extraction unit 421, an image analysis unit 422, a reference line setting unit 423, and a distance calculation unit 424. The control unit 42 is preferably a CPU (Central Processing Unit), an MCU (Micro Controller Unit), or a DSP (Digital Signal Processor), but is not limited thereto and various logic operation processors can be used.

[0197] The outline extraction unit 421 extracts the outline of each component of the battery case 13 or the secondary battery 1 from the image received from the vision sensor 41. In this case, the outline extraction unit 421 may extract the outline of all components appearing in the image, but is not limited thereto. Alternatively, a region of interest (ROI) may be set in a portion of the image and only the outline of components appearing within the ROI may be extracted. To extract the outline, information about the pixels of the image is first extracted, and a commonly used gradient formula may be used for this purpose. The outlines of the battery case 13 and the electrode leads 12 are revealed through the extracted pixel information.

[0198] According to an embodiment of the present invention, the radius of curvature R2 and clearance CL of the punch edge 161 of the cup portion 133 can be made smaller, and the outer wall 138 of the cup portion 133 can be made nearly vertical, so that the gradient of pixel information corresponding to the punch edge 161 of the cup portion 133 is large in the image. Therefore, the boundary between the outline and the background is clear, and the outline corresponding to the punch edge 161 of the cup portion 133 can be clearly extracted.

[0199] The image analysis unit 422 analyzes the image to detect an outline corresponding to the punch edge 161 of the cup portion 133 in the battery case 13. To this end, the image analysis unit 422 can detect the outline corresponding to the punch edge 161 of the cup portion 133 by matching the extracted outline information with pre-stored reference outline information of the punch edge 161 of the cup portion 133. In this case, the image analysis unit 422 can match the two pieces of information using a template matching technique.

[0200] The reference line setting unit 423 may set the outline corresponding to the punch edge 161 as the reference line ST. Because the cup portion 133 includes a plurality of punch edges 161, a plurality of outlines corresponding to the punch edges 161 are also extracted. At this time, in order to accurately measure the position of each component of the battery case 13 or the secondary battery 1, it is preferable that the reference line setting unit 423 sets the outline corresponding to the punch edge 161 closest to the component to be measured as the reference line ST among the plurality of punch edges 161. Furthermore, as described above, since the position of a component must be determined by measuring the vertical distance from the reference line ST, the reference line setting unit 423 may set the outline corresponding to the punch edge 161 parallel to the edge of the component to be measured as the reference line ST among the plurality of punch edges 161.

[0201] For example, in order to punch the vent hole H and perform the primary and secondary sealing, the inspection device 4 must measure the position of the vent portion 137. In this case, the reference line setting unit 423 can set the reference line ST to the outline of the punch edge 1612 on the die edge 162 side, which is close to the vent portion 137 and parallel to the edge 1371 included in the vent portion 137, among the multiple punch edges 161.

[0202] Then, for example, in order to inspect whether the positions of all the electrode leads 12 are consistent, the inspection device 4 must measure the positions of the electrode leads 12. In this case, the reference line setting unit 423 may set the outline of the electrode lead 12 side corresponding to the punch edge 1611 on the folding portion 139 side, which is close to the electrode lead 12 and parallel to the left or right edge of the electrode lead 12, among the multiple punch edges 161, as the reference line ST.

[0203] Furthermore, in order to measure the width between the cup portions 133, the reference line setting unit 423 may set the outline of any one of the outlines of two punch edges 161 among the multiple punch edges 161 that correspond to the boundary of the width of the cup portions 133 as the reference line ST.

[0204] That is, the reference line setting unit 423 can set various outlines as the reference line ST without any restrictions, as long as the positions of the components of the battery case 13 or the secondary battery 1 can be measured accurately.

[0205] The distance calculation unit 424 calculates the distance from the reference line ST to each component of the battery case 13 or the secondary battery 1 in the image. For example, when an outline corresponding to the punch edge 1612 on the die edge 162 side is set as the reference line ST, the distance calculation unit 424 may calculate the distance from the reference line ST to an edge included in the gas vent portion 137. Alternatively, when an outline corresponding to the punch edge 1611 on the folding portion 139 side is set as the reference line ST, the distance calculation unit 424 may calculate the distance from the reference line ST to one edge of the electrode lead 12, or may calculate the distance to the outline corresponding to the punch edge 1612 on the die edge 162 side.

[0206] The distance calculation unit 424 can use pre-stored information on the relationship between the number of pixels of an image and the actual distance. That is, the distance calculation unit 424 can count the distance from the reference line ST to each feature in the image in terms of the number of pixels, and then calculate the actual distance corresponding to the counted number of pixels using pre-stored information on the relationship between the number of pixels of an image and the actual distance.

[0207] The inspection device 4 may further include a storage unit 44. The storage unit 44 stores programs for processing and controlling the operation of the inspection device 4, as well as various data or received signals generated during the execution of each program. In particular, the storage unit 44 may store reference information for the battery case 13 so that the image analysis unit 422 can detect an outline corresponding to the punch edge 1611 of the cup portion 133. Here, the reference information for the battery case 13 may include reference outline information for the punch edge 1611 of the cup portion 133 and reference information for the distance to the battery case 13 or the components of the secondary battery 1. This information may be directly stored in the storage unit 44 by a user, or the inspection device 4 may generate and store the reference information through repeated learning. The storage unit 44 may also store information regarding the relationship between the number of pixels in an image and the actual distance so that the distance calculation unit 424 can calculate the actual distance from the reference line ST to each component. The storage unit 44 may also store inspection result information for the battery case 13 to be inspected. The storage unit 44 may be built into the inspection device 4 or may be provided as a separate storage server. The storage unit 44 includes a non-volatile memory device and a volatile memory device, the non-volatile memory device being a NAND flash memory that is small in volume, light in weight, and resistant to external shocks, and the volatile memory device may be a DDR SDRAM.

[0208] The control unit 42 may further include a defect determination unit 425 that determines whether the battery case 13 to be inspected is defective. The defect determination unit 425 can compare reference information for the battery case 13 stored in the storage unit 44 with the inspection result information for the battery case 13 to be inspected. If the inspection result information is within the error range of the reference information, the battery case 13 is determined to be normal. On the other hand, if the inspection result information is outside the error range of the reference information, the battery case 13 is determined to be defective.

[0209] Meanwhile, the inspection device 4 may further include a display unit 43 that receives an image signal and displays it. The display unit 43 receives the image signal and displays it to a user. When the outline extraction unit 421 extracts the outline of the battery case 13, the outline is displayed on the image so that a user can check it through the display unit 43. The display unit 43 may use various types of displays, such as a liquid crystal display (LCD), an organic liquid crystal display (OLED), a cathode ray tube (CRT), or a plasma display panel (PDP). The display unit 43 is connected to a bus via a video interface, and data transmission between the display unit 43 and the bus may be controlled by a graphic controller.

[0210] The inspection device 4 may further include an alarm unit 45 that generates an alarm when the defect determination unit 425 determines that the battery case 13 is defective. When generating an alarm, it is preferable to generate the alarm audibly or visually, such as by lighting a lamp or sounding an alarm, so that the user can intuitively know the alarm.

[0211] The components of the vision sensor 41, control unit 42, storage unit 44, and display unit 43 described above may be realized by software such as a task, class, subroutine, process, object, execution thread, or program executed in a predetermined area of ​​memory, or by hardware such as an FPGA (field-programmable gate array) or ASIC (application-specific integrated circuit), or may be a combination of the software and hardware. The components may be included in a computer-readable storage medium, or may be partially distributed across multiple computers.

[0212] Each block may represent a module, segment, or portion of code that includes one or more executable instructions for performing a specific logical function. In some alternative implementations, the functions described in the blocks may occur out of order. For example, two blocks shown one after the other may actually be performed substantially simultaneously, or the blocks may sometimes be performed in reverse order depending on the functions involved.

[0213] When using the inspection device 4 according to one embodiment of the present invention, the punch edge 1611 of the cup portion 133 is clearly visible, allowing the inspection device 4 to automatically set the punch edge 161 of the cup portion 133 as the reference line ST, and accurately measure the distance to each component of the battery case 13 using the punch edge 1611 of the cup portion 133 as a reference. For example, the size and position of the gas vent portion 137 can be measured, and even after the production of the secondary battery 1 is complete, the size and position of the cup portion 133, electrode lead 12, bat ears 15, sides 134, folding portion 139, and insulating portion 14 can be accurately determined. This makes it easy to determine whether the secondary battery 1 is defective, and allows efficient and centralized management of the specifications and quality of secondary batteries 1, even when mass-produced.

[0214] In particular, since the positions of the electrode leads 12 can be accurately measured, the electrode leads 12 can be easily connected when manufacturing the battery module 5. In addition, since the positions of the cup portions 333 can be accurately measured, the alignment of the secondary batteries 1 can be improved when stacking the secondary batteries 1 sequentially or aligning them in a row to manufacture the battery module 5.

[0215] 20 is a schematic diagram showing the completion of the manufacture of a secondary battery 1 by cutting the gas vent portion 137 of the battery case 13 according to one embodiment of the present invention. After the battery case 13 is secondarily sealed to form the seal portion 1341, a cut line CT is set on the outside of the seal portion 1341 and the gas vent portion 137 is cut. As a result, as shown in FIG. 20, the length of the gas vent portion 137 is shortened, thereby reducing the volume of the secondary battery 1. Through the above process, the manufacture of the pouch-type secondary battery 1 is completed.

[0216] Meanwhile, the side 134 remaining after cutting the gas vent 137 does not have the electrode lead 12 protruding from it among the multiple sides 134. However, if the side 134 is left as is after being sealed, the overall volume of the secondary battery 1 increases. Therefore, it is preferable to fold the side 134 to reduce the energy density relative to the volume.

[0217] 20, the side 134 may include a sealed portion 1341 and an unsealed portion 1342. The sealed portion 1341 is located relatively outside and is a sealed area, while the unsealed portion 1342 is located relatively inside and is an unsealed area.

[0218] Specifically, when forming the seal portion 1341 by secondarily sealing the battery case 13, the seal portion 1341 may not be directly connected to the cup portion 133 but may be spaced apart to a certain extent. To seal the side 134, heat and pressure must be applied to the side 134 using a separate sealing tool (not shown). However, if the side 134 is sealed with such a sealing tool in close contact with the cup portion 133, the sealant layer 1351 located inside the side 134 may partially melt and leak toward the electrode assembly 10, contaminating the electrode assembly 10. Furthermore, heat from the sealing tool may be transferred to the electrode assembly 10, potentially damaging it. Therefore, it is preferable to seal the side 134 with the sealing tool spaced apart from the cup portion 133 to a certain extent. In this case, the portion sealed by the sealing tool becomes the seal portion 1341, and the portion not sealed due to the separation of the sealing tool from the cup portion 133 becomes the unsealed portion 1342.

[0219] FIG. 21 is a schematic side view of the conventional side 334 after folding, and FIG. 22 is a schematic top view of the conventional side 334 after folding.

[0220] In the past, when the side 334 was folded, the side 334 was not fixed and would unfold again at a predetermined angle. Specifically, as described above, the pouch film 135 is formed by laminating the sealant layer 1351, moisture barrier layer 1352, stretching assist layer 1354, and surface protection layer 1353. Among these, the sealant layer 1351 contains a first polymer, particularly polypropylene (PP), and therefore has high flexibility and elasticity. Therefore, when the side 134 is folded, it has a strong restoring force to return to its original state. In contrast, since the moisture barrier layer 1352 is made of metal, particularly an aluminum alloy, after the side 334 is folded, it exceeds its elastic deformation limit and has a strong restoring force to maintain the folded state.

[0221] Conventional pouch films have a moisture barrier layer with a thickness of approximately 30 to 50 μm and a sealant layer with a thickness of approximately 60 to 100 μm. That is, the moisture barrier layer is significantly thinner than the sealant layer. Therefore, the restoring force is greater than the storage force, and the side 334 is not fixed and is unfolded again at a predetermined angle. This poses a problem in that the side 334 increases the unnecessary volume of the secondary battery 3.

[0222] To solve this problem, a separate tape 38 is attached to the side 334 as shown in Figures 21 and 22. In particular, the tape 38 is attached to both the outer surface of the bottom 3332 of the cup portion 333 and the side 334, thereby fixing the side 334 to the cup portion 333 and preventing it from being unfolded again. However, this method has the problem of increasing the overall thickness of the secondary battery 3 due to the thickness of the tape 38 itself, as shown in Figure 21. In addition, an additional process of attaching the tape 38 is required after the process of folding the side 334, which takes a lot of time, increases the number of processes, and reduces the manufacturing yield of the secondary battery 3.

[0223] Meanwhile, during the degassing process, the internal pressure of the cup portion 133 decreases as gas is discharged from the inside of the battery case 13 to the outside. Conventionally, the electrode assembly 10 is disposed at a certain distance from the outer wall 338 of the cup portion 333. Therefore, as the internal pressure of the cup portion 333 decreases, the volume of the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10 also decreases, which can cause deformation of the outer wall 338 or the bottom 3332 of the cup portion 333. In particular, as shown in FIG. 21 , as the outer wall 338 on the folding portion side of the secondary battery 3 sinks inward, the punch edge 361 on the folding portion 339 side of the cup portion 333 protrudes outward, resulting in an edge-high phenomenon. This edge-high phenomenon increases the unnecessary thickness of the secondary battery 3, resulting in a decrease in the energy density per volume. In addition, the outer wall 338 on the folding section 339 side of the cup section 333 is deformed, which causes a problem of the appearance of the secondary battery 3 being unattractive and reducing its marketability. Furthermore, there is also the problem that the edge-high phenomenon causes the bat ears 15 to increase in size and become more noticeable.

[0224] 23 is a schematic side view showing the folded side 134 according to one embodiment of the present invention. According to one embodiment of the present invention, the pouch film 135 has a moisture barrier layer 1352 with a thickness of 50 to 70 μm and a sealant layer 1351 with a thickness of 70 to 100 μm, making the moisture barrier layer 1352 thicker than conventional pouch films. Therefore, when the side 134 is folded, the preservative strength is further increased, and it is possible to prevent the side 134 from being unfolded again without the need to attach another tape 38.

[0225] To this end, a secondary battery 1 according to one embodiment of the present invention includes an electrode assembly 10 formed by stacking an electrode 101 and a separator 102, and a pouch-type battery case 13 having a cup portion 133 for accommodating the electrode assembly 10 therein. The pouch-type battery case 13 includes a side 134 extending outward from the cup portion 133. The side 134 includes a sealed portion 1344 located relatively outward and sealed, and an unsealed portion 1345 located relatively inward and unsealed. The side 134 is not attached to the cup portion 133 and is folded at the unsealed portion 1345.

[0226] That is, as shown in FIG. 23 , after the side 134 of the secondary battery 1 is folded toward the cup portion 133, the side 134 is not attached to the cup portion 133 and remains folded, not unfolded. In this case, the side 134 may be folded at an angle of 85° to 95°, particularly at an angle of 88° to 92°. The side 134 may be folded adjacent to the cup portion 133, so that the side 134 may contact the outer wall 138 of the cup portion 133. In particular, as described above, the side 134 may include a sealed portion 1341 disposed relatively outward and sealed, and an unsealed portion 1342 disposed relatively inward and unsealed. When the side 134 is folded, it is preferable that the unsealed portion 1342, which is relatively closer to the cup portion 133, be folded. This can further reduce unnecessary volume of the secondary battery 1. However, even in this case, the side 134 and the cup part 133 are not bonded to each other, but the restoring force of the side 134 is increased to maintain the folded state.

[0227] When two cup portions 133 are formed in the pouch film 135, the depth D of the cup portion 133 may be thinner than when one cup portion 133 is formed. As described above, this is because the cup portion 133 is not stretched in a concentrated manner, but the side 134 surrounding the cup portion 133 is also stretched finely as a whole. However, if the width of the side 134 is longer than the depth D of the cup portion 133, the outer end 1343 of the side 134 may protrude further outward than the bottom 1332 of the cup portion 133 when the side 134 is folded only once.

[0228] Therefore, when two cup portions 133 are formed in the pouch film 135, a double side folding (DSF) method can be used in which the side 134 is folded twice, as shown in FIG. 23 . Specifically, the side 134 may include a first folding portion 1344 and a second folding portion 1345. The first folding portion 1344 is a portion folded relatively closer to the outer edge 1343, and the second folding portion 1345 is a portion folded relatively closer to the cup portion 133. Therefore, the side 134 may be primarily folded based on the first folding portion 1344, and then the side 134 may be secondarily folded based on the second folding portion 1345. In this case, the first folding portion 1344 may be located at the sealed portion 1341 of the side 134, and the second folding portion 1345 may be located at the unsealed portion 1342 of the side 134. The side 134 may be folded at an angle of 170° to 180°, particularly 180°, at the first folding portion 1344. The side 134 may be folded at an angle of 85° to 95°, particularly 88° to 92°, at the second folding portion 1345. This prevents the outer end 1343 of the side 134 from protruding further outward than the bottom 1332 of the cup portion 133.

[0229] Meanwhile, according to one embodiment of the present invention, the electrode assembly 10 can be positioned very close to the outer wall 138 of the cup part 133, thereby reducing unnecessary volume of the cup part 133. Therefore, even if the internal pressure of the cup part 133 is reduced by performing a degassing process, deformation of the outer wall 138 or the bottom part 1332 of the cup part 133 can be prevented. That is, as shown in FIG. 23, the edge-high phenomenon can be prevented, and therefore the energy density per volume does not decrease.

[0230] FIG. 24 is a schematic diagram of a battery module 5 according to one embodiment of the present invention. Medium- to large-sized electronic devices such as automobiles require large output power and therefore require many secondary batteries 1. A battery module 5 can be manufactured to allow such secondary batteries 1 to be easily moved and installed. When multiple secondary batteries 1 are installed in such a battery module 5, electricity can be stably supplied to the outside.

[0231] Meanwhile, as electricity is produced from the electrode assembly 10 of the secondary battery 1, a chemical reaction occurs between the electrodes 101 and the electrolyte, generating heat during this process. However, if the ambient temperature rises excessively due to the heat, there is a problem that the circuits of the electrical equipment in which the secondary battery 1 is installed may malfunction or the lifespan of the electrical equipment may be shortened. Therefore, the battery module 5 includes a cooling system for cooling the secondary battery 1. Cooling systems are broadly divided into water-cooled systems that use cooling water and air-cooled systems that use air. Among these, water-cooled systems are more widely used because they have higher cooling efficiency than air-cooled systems.

[0232] The cooling system includes a cooling plate that directly cools the secondary battery 1, and a separate flow path is formed inside the cooling plate, allowing the coolant to flow. The thinner and longer the flow path, the larger the surface area, and the greater the cooling efficiency.

[0233] To manufacture a battery module 5, a plurality of secondary batteries 1 are first manufactured, and then these secondary batteries 1 are connected to one another and housed in a housing 51. At this time, the secondary batteries 1 may be stacked in a line. As shown in Fig. 24, when the secondary batteries 1 are housed in the housing 51, the long side of the secondary batteries 1 faces downward, and a cooling plate (not shown) may be formed on the underside of the housing 51. Therefore, the cooling plate cools the long side of the secondary batteries 1, thereby increasing cooling efficiency.

[0234] Meanwhile, a folding portion 139 is formed on one side of the secondary battery 1 by folding the bridge 136, and a side 134 is formed on the other side, which is the area remaining after the gas vent portion 137 is cut off. However, if the cooling plate cools the side where the side 134 is formed among the multiple surfaces of the secondary battery 1, the cooling efficiency may decrease because the side 134 increases the distance between the cooling plate and the electrode assembly 10. Therefore, it is preferable that the cooling plate cools the side where the folding portion 139 is formed among the longer sides of the secondary battery 1. For this reason, when the secondary battery 1 is inserted into the housing 51, the folding portion 139 may be inserted in a direction toward the cooling plate, i.e., downward.

[0235] FIG. 25 is an enlarged front view showing a conventional secondary battery 3 housed in a housing 51 of a battery module 5, and FIG. 26 is an enlarged side view showing a conventional secondary battery 3 housed in a housing 51 of a battery module 5.

[0236] As described above, there has been a limit to reducing the size of the bat ears 35 in the past. Also, in the past, the angle θ′ formed between the folding portion 339 and the inner edge 35a of the bat ears 35 was set to 151 degrees or less.

[0237] Here, the angle θ′ may refer to the angle formed between a virtual first line L1 corresponding to the folding portion 339 and a virtual second line L2 corresponding to the inner edge 35a of the bat ear 35. In particular, the first line L1 and the second line L2 may be determined by image analysis. For example, the first line L1 and the second line L2 may be extracted by connecting a plurality of edge points identified within a region of interest (ROI) in a vision device. Therefore, even if the folding portion 339 or the inner edge 35a of the bat ear 35 is partially bent or curved, the first line L1 and the second line L2 may be clearly defined. Since such image analysis is a well-known technique, a detailed description thereof will be omitted.

[0238] 25, when the secondary battery 3 is housed in the housing 51, the bat ears 35 create a large gap d' (e.g., greater than 1.5 mm) between the housing 51 and the folding portion 339. This gap d' can impede the cooling of the cooling plate, reducing cooling efficiency. To address this issue, a heat transfer material 52 is injected into the space between the cooling plate and the folding portion 339 of the secondary battery 1, allowing the cooling plate to cool the folding portion 339 through the heat transfer material 52.

[0239] However, if the size of the bat ears 15 is large, a large amount of the heat transfer material 52 must be injected, which increases the cost, and the large distance d' between the cooling plate and the folding portion 139 still results in low cooling efficiency.

[0240] Furthermore, when the venting process is performed through the vent hole H, the internal pressure of the battery case 33 decreases, and as a result, the folding portion 339 of the battery case 33 comes into close contact with the electrode assembly 10, as shown in Figure 26. However, in the past, there was a limit to how much the clearance CL' could be reduced, and the width of the folding portion 339 was also large. This resulted in a large space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10, which reduced the energy density per volume of the secondary battery 3. Furthermore, the distance between the electrode assembly 10 and the thermal grease 52 also increased, which further reduced the cooling efficiency.

[0241] Figure 27 is an enlarged front view showing a secondary battery 1 according to one embodiment of the present invention housed in a housing 51 of a battery module 5, and Figure 28 is an enlarged side view showing a secondary battery 1 according to one embodiment of the present invention housed in a housing 51 of a battery module 5.

[0242] A pouch-type secondary battery 1 according to one embodiment of the present invention includes an electrode assembly 10 formed by stacking electrodes 101 and separators 102, and a pouch-type battery case 13 having a cup portion 133 for accommodating the electrode assembly 10 therein. The battery case 13 includes a first case 131 and a second case 132, at least one of which has the cup portion 133 formed therein, a folding portion 139 that integrally connects the first case 131 and the second case 132, and bat ears 15 that protrude outward from portions of both ends of the folding portion 139, and the bat ears 15 have a length d of 1.5 mm or less.

[0243] In addition, the angle θ formed between the folding portion 139 and the inner edge 15a of the bat ear 15 may be greater than 151 degrees. The angle θ may also be less than 180 degrees. If the angle θ is 180 degrees, it may indicate that the bat ear 15 does not exist.

[0244] Here, the angle θ may refer to the angle formed by an imaginary first line L1 corresponding to the folding portion 139 and an imaginary second line L2 corresponding to the inner edge 15a of the bat ear 15. The above description applies to the first line L1 and the second line L2.

[0245] A battery module 5 according to one embodiment of the present invention includes a pouch-type secondary battery 1 in which an electrode assembly 10 formed by stacking electrodes 101 and separators 102 is housed inside a cup portion 133 formed in a pouch-type battery case 13, and a housing 51 in which the secondary battery 1 is housed, and the battery case 13 includes a first case 131 and a second case 132 each having the cup portion 133 formed therein, a folding portion 139 that connects the first case 131 and the second case 132 together, and bat ears 15 formed to protrude outward from a portion of both ends of the folding portion 139, and the bat ears 15 have a length d of 1.5 mm or less.

[0246] As described above, the bat ears 15 are formed by folding the bridge 136 and protruding outward from portions of both ends of the folding portion 139. According to one embodiment of the present invention, the length of the bat ears 15 may be 1.5 mm or less, and particularly 1 mm or less. The length of the bat ears 15 may be measured from the outer wall 1381 on the folding portion 139 side to the outermost end of the bat ears 15. In this case, as described above, the outer wall 1381 on the folding portion 139 side may have an inclination angle of 90° to 95° from the bottom 1332 due to the clearance CL. In consideration of this, as an example of measuring the length of the bat ears, the length of the bat ears 15 may be measured from the outermost protruding portion of the outer wall 1381 on the folding portion 139 side to the outermost end of the bat ears 15.

[0247] The length of bat ears 15 may be measured by directly contacting secondary battery 1 using a ruler or vernier caliper, or may be measured in a non-contact manner using a laser displacement sensor or a vision sensor.

[0248] The above is an example of a method for measuring bat ear length, and the scope of the present invention is not necessarily limited to the above measurement method. Any bat ear length that falls within the scope of the claims and the spirit of the present invention can be considered as the bat ear length defined in the present invention.

[0249] According to one embodiment of the present invention, the depth D of the cup portion 133 can be formed to be 6.5 mm or less, the thickness t of the bridge 136 can be made thinner, and the radius of curvature R2 and clearance CL of the punch edge 1611 of the cup portion 133 can be made smaller.

[0250] As a result, the length d of the bat ears 15 can be further reduced to 1.5 mm or less, particularly 1 mm or less. Therefore, as shown in Fig. 27, the gap d between the housing 51 and the folding portion 139 can be narrowed to 1.5 mm or less. As a result, the thickness of the thermal grease 52 inside the housing 51 can be 1.5 mm or less, and the amount of the thermal transfer material 52 injected can be further reduced, resulting in cost savings and increased cooling efficiency.

[0251] 28, the clearance CL can be further reduced, and the width FW of the folding portion 139 can also be reduced. This reduces the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10, thereby increasing the energy density per volume of the secondary battery 1. Furthermore, the distance between the electrode assembly 10 and the thermal grease 52 is reduced, thereby further improving cooling efficiency.

[0252] Those skilled in the art will understand that the present invention can be embodied in other specific forms without changing the technical spirit or essential characteristics thereof. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims set forth below rather than the above detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention. [Explanation of symbols]

[0253] 1: Secondary battery 2: Molding equipment 3: Conventional secondary batteries 4: Inspection equipment 5: Battery module 10: Electrode assembly 11: Electrode tab 12: Electrode lead 13: Battery case 14: Insulation section 15:Bat ears 16: Edge 17: Space 21: Die 22: Punch 33: Conventional battery case 35: Traditional bat ears 36: Conventional Edge 37: Traditional space 38: Conventional tape 41: Vision sensor 42: Control unit 43: Display section 44: Storage area 45: Alarm section 51: Housing 52: Thermal grease 101: Electrode 102: Separator 111: Positive electrode tab 112: Negative electrode tab 121: Positive lead 122: Negative electrode lead 131: First Case 132: Second Case 133: Cup part 134: Side 135: Pouch film 136: Bridge 137: Gas vent 138: Exterior wall 139: Folding section 161: Punch Edge 162: Die Edge 163: Thickness Edge 164: Corner 211: Molding section 212: Bulkhead 213: Die Edge 221: Edge of the Punch 333: Conventional cup part 334: Conventional side 336: Conventional bridge 337: Conventional gas vent 338: Conventional exterior wall 339: Conventional folding section 361: Conventional punch edge 362: Conventional die edge 421: Outline extraction section 422: Image Analysis Department 423: Reference line setting section 424: Distance calculation section 425: Defect judgment department 1021: Periphery 1331: Containment Space 1332: Bottom 1333: Exterior wall 1340:Temporary Seal Section 1341: Seal part 1342: Unsealed part 1343: Outer edge 1344: First Folding Section 1345: Second Folding Section 1351: Sealant layer 1352: Moisture barrier layer 1353: Surface protective layer 1354: Stretched auxiliary layer 1371: Edge 1381: Bridge side exterior wall 1382: Outer wall on the gas vent side 1391: Groove 1611:Punched edge on bridge side 1612: Punch edge on the gas vent side 1613: First punch edge 1614: Second punch edge

Claims

1. an electrode assembly formed by stacking electrodes and separators; a pouch-type battery case having a cup portion formed therein to accommodate the electrode assembly, The battery case is a first case and a second case, at least one of which has the cup portion formed therein; a folding portion that integrally connects the first case and the second case, The folding portion has a width of 1 mm to 3.2 mm; The depth of the cup portion is 6.5 mm or less, When the battery case is folded, bat ears are formed protruding outward from parts of both ends of the folding portion.

2. The area of ​​the electrode assembly is 15,000 mm ２ ~100,000 mm ２ 2. The pouch-type secondary battery according to claim 1, wherein

3. The pouch-type secondary battery according to claim 1, wherein the folding portion has a width of 1 mm to 1.6 mm.

4. The pouch-type secondary battery according to claim 1 , wherein the folding portion is formed to include a recessed groove on its inner side.

5. the battery case includes a pair of protrusions that protrude outward with the groove therebetween, 5. The pouch-type secondary battery according to claim 4, wherein the distance between the innermost part of the groove and the outermost part of the protrusion is 0.8 mm or less.

6. The pouch-type secondary battery of claim 1 , wherein a difference between a width of the cup portion and a width of the electrode assembly is 2.5 mm or less.

7. The pouch-type secondary battery according to claim 6 , wherein a difference between a width of the cup portion and a width of the electrode assembly is 1.7 mm or less.

8. The pouch-type secondary battery according to claim 6 , wherein the width of the cup portion is a distance between upper ends of both outer walls of the cup portion.

9. The cup portion is a plurality of punch edges each connecting a plurality of outer walls and a bottom portion surrounding the periphery, at least one of which is rounded with a curvature radius of 1 mm or less; a plurality of die edges connecting the outer wall and the side or vent portion, at least one of which is rounded with a curvature radius of 1 mm or less; 2. The pouch-type secondary battery according to claim 1, further comprising: a thickness edge connecting two adjacent outer walls to each other.

10. 10. The pouch-type secondary battery according to claim 9, wherein a vertical distance between a die edge vertical line that passes through a boundary point between the die edge and the outer wall on the die edge side and is perpendicular to the bottom, and an edge vertical line that passes through a boundary point between the punch edge on the die edge side and the outer wall on the die edge side and is perpendicular to the bottom, is 0.5 mm or less.

11. The pouch-type secondary battery according to claim 10 , wherein the electrode assembly has one end of at least one of the electrodes positioned at a vertical distance of 0.75 mm or less from the edge vertical line.

12. The pouch-type secondary battery according to claim 11 , wherein the electrode assembly has one end of at least one of the electrodes positioned at a vertical distance of 0.5 mm or less from the edge vertical line.

13. The pouch-type secondary battery according to claim 9 , wherein the separator has a periphery that protrudes outward from the electrodes and is folded toward the opposite side of the bottom from one end of the electrodes.

14. The electrode assembly includes a plurality of electrodes and a plurality of separators, The separator accommodated in the cup portion of the first case has the peripheral portion folded toward the second case, The pouch-type secondary battery according to claim 13 , wherein the separator housed in the cup portion of the second case has the peripheral portion folded toward the first case.

15. The pouch-type secondary battery according to claim 14 , wherein the periphery of at least one separator is folded in alignment with the periphery of an adjacent separator.

16. The pouch-type secondary battery according to claim 9 , wherein at least one of the punch edges is rounded with a curvature radius of 0.7 mm or less.

17. 10. The pouch-type secondary battery according to claim 9, wherein the radius of curvature of the punch edge is 1 / 20 to 1 / 6 of the depth of the cup portion.

18. The pouch-type secondary battery according to claim 9 , wherein at least one of the die edges is rounded with a curvature radius of 0.7 mm or less.

19. 10. The pouch-type secondary battery according to claim 9, wherein the radius of curvature of the die edge is 1 / 20 to 1 / 6 of the depth of the cup portion.

20. 10. The pouch-type secondary battery according to claim 9, wherein the outer wall is inclined from the bottom at an angle of 90° to 95°.

21. the thickness edge is connected to two adjacent punch edges to form a corner; 10. The pouch-type secondary battery according to claim 9, wherein at least one of the corners is rounded with a radius of curvature of 2 mm to 5 mm, the radius of curvature being larger than the radius of curvature of the thickness edge.

22. 22. The pouch-type secondary battery according to claim 21, wherein the radius of curvature changes within the corner.

23. The pouch-type secondary battery according to claim 22 , wherein the corner has a larger radius of curvature at the center than at the periphery.

24. The pouch-type secondary battery according to any one of claims 1 to 23, further comprising bat ears formed to protrude outward from portions of both ends of the folding portion, the bat ears having a length of 1.5 mm or less.

25. The pouch-type secondary battery according to claim 24 , wherein an angle formed between the folding portion and an inner edge of the bat ear is greater than 151 degrees.

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