Pouch-type battery case and manufacturing device thereof, pouch-type secondary battery

Abstract

A pouch-type battery case according to an embodiment of the present invention may accommodate an electrode assembly in which electrodes and separators are alternately stacked. The pouch-type battery case may include a pair of indented portions having an indented shape, a pair of terraces positioned around the pair of indented portions in an unfolded state of the battery case and inclined toward each other as they approach each other downward, and a bridge positioned between the pair of indented portions, connecting the pair of indented portions, and having a pair of connecting surfaces inclined toward each other as they approach each other upward from bottom surfaces of the pair of indented portions. When the battery case is unfolded, an angle formed by the pair of terraces may be an obtuse angle.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0048279, filed on April 14, 2021, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery case, a manufacturing apparatus therefor, and a pouch-type secondary battery. [Background technology]

[0003] Secondary batteries capable of repeated charging and discharging can be classified into cylindrical, prismatic, pouch, etc., depending on their manufacturing method or structure. Among these, pouch-type secondary batteries generally have a structure in which an electrode assembly having electrodes and separators alternately arranged is housed in a sheet-like pouch outer casing.

[0004] According to the prior art, to manufacture a pouch-type secondary battery, a pouch-type battery case is manufactured through a forming process in which a portion of a pouch sheet is compressed by an area corresponding to the area of ​​an electrode assembly to form a concave portion, and then the electrode assembly is placed in the concave portion and a sealing portion is formed by adhering portions of the battery case together.

[0005] The sealing portion, which is formed by adhering some areas of the pouch-type battery case together, is formed by adhering areas that are not pressurized during the forming process. Therefore, due to the difference in level between the sealing portion that has not been formed and the storage portion that has been formed, some areas of the sealing deviate from the width of the storage portion. Figure 1 shows that some areas of the sealing portion 3 formed on both sides of the length of a pouch-type secondary battery 1 manufactured using conventional technology protrude beyond the width of the recessed portion 2 that accommodates the electrode assembly.

[0006] Such protruding regions are generally called "butt-ears." The butt-ears increase dead space that does not contribute to energy capacity, resulting in a problem of reduced energy density of battery cells and secondary battery modules.

[0007] Furthermore, according to the conventional technology, there is a problem that void space occurs between the inner periphery of the recess 2 and the electrode assembly, which causes wrinkles in the battery case 2 after the degassing process. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, one object of the present invention is to provide a pouch-type battery case that reduces empty space not occupied by an electrode assembly, and a pouch-type secondary battery including the same.

[0009] Another problem to be solved by the present invention is to provide a manufacturing apparatus capable of manufacturing the pouch-type battery case. [Means for solving the problem]

[0010] A pouch-type battery case according to an embodiment of the present invention may accommodate an electrode assembly in which electrodes and separators are alternately stacked. The pouch-type battery case may include a pair of curved indentations, a pair of terraces positioned around the pair of indentations when the battery case is unfolded and inclined downward to approach each other, and a bridge positioned between the pair of indentations, connecting the pair of indentations, and having a pair of connecting surfaces inclined upward from bottom surfaces of the pair of indentations. The angle formed by the pair of terraces when the battery case is unfolded may be an obtuse angle.

[0011] In a state where the battery case is unfolded, bottom surfaces of the pair of recesses may be inclined in a direction away from each other as they extend upward.

[0012] When the battery case is unfolded, the angle formed by the pair of terraces may be 130 degrees to 170 degrees.

[0013] The pouch-type battery case may further include an inner edge connecting an inner periphery of the indentation to a bottom surface of the indentation, and an outer edge connecting an outer periphery of the indentation to the terrace, and the radius of curvature of the inner edge may be equal to or greater than the radius of curvature of the outer edge.

[0014] When the battery case is unfolded, the horizontal clearance between the inner edge and the outer edge may be 0.5 mm or less.

[0015] When the battery case is unfolded, a horizontal clearance between the inner edge and the outer edge may be 0.35 mm or less.

[0016] When the battery case is unfolded, a horizontal clearance between the inner edge and the outer edge may be equal to or less than a radius of curvature of the outer edge.

[0017] The pouch-type battery case may further include a bent portion that connects the pair of terraces and is rounded downward when the battery case is unfolded.

[0018] The bridge may further include a first connecting edge that connects the pair of connecting surfaces and is rounded upwardly. A height of a bottom end of the bending portion may be equal to or greater than a height of an top end of the first connecting edge.

[0019] When the battery case is unfolded, the bridge may further include a pair of second connecting edges that connect the pair of connecting surfaces to bottom surfaces of the pair of indentations and are rounded downwardly.

[0020] When the battery case is unfolded, a first distance can be measured from an imaginary line that passes through the boundary between the inner periphery of the recessed portion and the inner edge and is perpendicular to the terrace to the connecting surface in a direction aligned with the terrace, and a second distance that is shorter than the first distance can be measured from the imaginary line to the boundary between the terrace and the bending portion in a direction aligned with the terrace.

[0021] In a state where the pouch is unfolded, a length from a center of the bending portion to a boundary between the terrace and the bending portion may be shorter than a difference between the first distance and the second distance.

[0022] A pouch-type secondary battery according to an embodiment of the present invention may include an electrode assembly having a structure in which electrodes and separators are alternately stacked, and a pouch-type battery case having a storage compartment for accommodating the electrode assembly. The case may include a folding portion forming a portion of a peripheral surface of the storage compartment and a peripheral portion extending from another portion of the peripheral surface of the storage compartment. Corners of the peripheral portion may include a first corner adjacent to the folding portion, a second corner extending from the first corner in a direction opposite to the folding portion and having a thickness thinner than the first corner, and a border connecting the first corner and the folding portion and protruding beyond the first corner in a width direction of the storage compartment.

[0023] The first corner portion and the second corner portion may not protrude beyond the folding portion in the width direction of the storage portion.

[0024] The second corner may protrude further than the first corner in the width direction of the storage section.

[0025] The boundary portion may not protrude beyond the folding portion in the width direction of the storage portion.

[0026] The pouch-type secondary battery may further include an inner edge connecting an inner top surface or an inner bottom surface of the receiving portion to an inner periphery of the receiving portion, and an outer edge connecting an outer periphery of the receiving portion to the periphery, and a radius of curvature of the inner edge may be equal to or greater than the radius of curvature of the outer edge.

[0027] A horizontal clearance between the inner edge and the outer edge may be equal to or less than the radius of curvature of the inner edge.

[0028] A pouch-type battery case manufacturing apparatus according to an embodiment of the present invention may form a pouch sheet placed on a die using a punch. The die may include a pair of mounting surfaces inclined upwardly and inclined away from each other, a pair of molding portions recessed or penetrating downward from the pair of mounting surfaces, and a center portion positioned between the pair of molding portions. The punch may include a pair of punching portions inserted into the pair of molding portions and having bottom surfaces that decrease in height as they approach each other. The angle formed by the pair of mounting surfaces may be an obtuse angle.

[0029] The angle formed by the pair of placement surfaces may be 130 degrees to 170 degrees.

[0030] The die may further include a die edge connecting an inner periphery of the forming portion to the mounting surface. The punch may further include a punching edge connecting an outer periphery of the punching portion to a bottom surface of the punching portion. The radius of curvature of the punching edge may be equal to or greater than the radius of curvature of the die edge.

[0031] The horizontal clearance between the die edge and the punching edge may be 0.5 mm or less.

[0032] A horizontal clearance between the die edge and the punching edge may be equal to or less than the radius of curvature of the die edge.

[0033] The center portion may include a pair of inclined surfaces that are inclined downward and away from each other.

[0034] The center portion may further include a center edge that connects the pair of inclined surfaces and is rounded upward.

[0035] The punched portion may further include a pair of side edges formed at a lower end of the bottom surface and rounded downwardly. [Effects of the Invention]

[0036] According to a preferred embodiment of the present invention, it is possible to eliminate the butt ear of a pouch-type secondary battery while minimizing the space not occupied by the electrode assembly, thereby increasing the energy density of the secondary battery. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a diagram showing the appearance of a conventional pouch-type secondary battery. [Figure 2] 1 is a perspective view showing an electrode assembly housed in a pouch-type battery case according to an embodiment of the present invention; [Figure 3] 1 is a plan view showing a pouch-type battery case according to an embodiment of the present invention in an unfolded state. [Figure 4] 1 is a vertical cross-sectional view showing a pouch-type battery case according to an embodiment of the present invention in an unfolded state. [Figure 5] 5 is an enlarged view of the bridge and its surroundings shown in FIG. 4. FIG. [Figure 6] FIG. 5 is a diagram for explaining the detailed configuration of the pouch-type battery case shown in FIG. [Figure 7] 1 is a cross-sectional view of a pouch-type battery case manufacturing apparatus according to an embodiment of the present invention. [Figure 8a] 1 is a first experimental example according to one embodiment of the present invention. [Figure 8b] 1 is a first experimental example according to one embodiment of the present invention. [Figure 9a] 10 is a second experimental example according to one embodiment of the present invention. [Figure 9b] 10 is a second experimental example according to one embodiment of the present invention. [Figure 10a] This is a first comparative example. [Figure 10b] This is a first comparative example. [Figure 11a] This is a second comparative example. [Figure 11b] This is a second comparative example. [Figure 12a] This is a third comparative example. [Figure 12b] This is a third comparative example. [Figure 13] 1 is a plan view of a pouch-type secondary battery according to an embodiment of the present invention; [Figure 14] 14 is an enlarged plan view showing a corner of the peripheral portion shown in FIG. 13 and its surroundings. FIG. [Figure 15] 14 is an enlarged perspective view of a corner of the peripheral portion shown in FIG. 13 and its surroundings. FIG. [Figure 16] FIG. 10 is a view showing a pouch-type battery case according to another embodiment of the present invention in an unfolded state. DETAILED DESCRIPTION OF THE INVENTION

[0038]

[0033] The present invention will now be described in detail with reference to the accompanying drawings, in which:

[0034] A preferred embodiment of the present invention will be described in detail so that those skilled in the art can easily implement the present invention; however, the present invention may be realized in various different forms and is not limited to the following embodiments.

[0039] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention will be omitted, and when referring to components in each drawing in this specification, the same or similar reference symbols will be used for the same or similar components throughout the specification.

[0040] Furthermore, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, in accordance with the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0041] FIG. 2 is a perspective view showing an electrode assembly housed in a pouch-type battery case according to one embodiment of the present invention, FIG. 3 is a plan view showing the pouch-type battery case according to one embodiment of the present invention in an unfolded state, and FIG. 4 is a vertical cross-sectional view showing the pouch-type battery case according to one embodiment of the present invention in an unfolded state.

[0042] The pouch-type secondary battery (hereinafter, “secondary battery”) according to the present invention may include a pouch-type battery case 10 (hereinafter, “case”) and an electrode assembly 20 .

[0043] The electrode assembly 20 may be formed by alternately stacking electrodes and separators.

[0044] The electrode assembly 20 may include electrode tabs 21. The electrode tabs 21 are connected to the positive and negative electrodes of the electrode assembly 20, respectively, and protrude from the electrode assembly 20 to the outside, thereby providing a path for electrons to move between the inside and outside of the electrode assembly 20.

[0045] The plurality of electrode tabs 21 connected to the positive electrode and the plurality of electrode tabs 21 connected to the negative electrode may protrude in different directions from the electrode assembly 20. However, this is not limited thereto, and the plurality of electrode tabs 21 connected to the positive electrode and the plurality of electrode tabs 21 connected to the negative electrode may protrude in the same direction from the electrode assembly 20 side by side.

[0046] An electrode lead 22 for supplying electricity to the outside of the secondary battery may be connected to the plurality of electrode tabs 21 by spot welding, etc. One end of the electrode lead 22 may be connected to the plurality of electrode tabs 21, and the other end may protrude outside the case 10.

[0047] A portion of the electrode lead 22 may be surrounded by an insulating portion 23. For example, the insulating portion 23 may include insulating tape. The insulating portion 23 may be positioned between a pair of terraces 200 of the case 10, which will be described later, and the pair of terraces 200 may be heat-sealed to each other in this state. In this case, a portion of the pair of terraces 200 may be heat-sealed to the insulating portion 23. Therefore, the insulating portion 23 prevents electricity generated from the electrode assembly 20 from flowing to the battery case 10 via the electrode lead 22, and maintains the sealing of the battery case 10.

[0048] Meanwhile, the case 10 can accommodate the electrode assembly 20 .

[0049] In this specification, the term "unfolded state of case 10" can refer to the state of case 10 when the predetermined adhesive or sealing that existed on case 10 is removed to unfold case 10 and then left as is without applying any artificial force to case 10. Alternatively, it can refer to the state immediately before deformation of terrace 200, which will be described later, occurs due to the unfolding action of gradually unfolding case 10 by applying an external force to case 10 after the predetermined adhesive or sealing that existed on case 10 is removed.

[0050] That is, the "unfolded state of the case 10" may refer to the state of the case 10 after it has been manufactured through a forming process and before it is folded.

[0051] The configuration of the case 10 will be described in detail below, based on the case 10 in its unfolded state.

[0052] The case 10 can include a pair of indentations 100 having an indented shape, a pair of terraces 200 positioned around the pair of indentations 100, and a bridge 150 positioned between the pair of indentations 100.

[0053] Each indentation 100 may be substantially cup-shaped. More specifically, each indentation 100 may indent a predetermined depth W (see FIG. 5) from a terrace 200 (described later) to form an indented space S1.

[0054] Of the recessed space S1 formed by the pair of recessed portions 100, a portion adjacent to the side 210 of the terrace 200 described below can form a void space that is not occupied by the electrode assembly 20 when the case 10 is sealed.

[0055] Preferably, the indentation depths of the pair of indentations 100 may be the same. In this case, the pair of indentations 100 may have symmetrical shapes.

[0056] However, the present invention is not limited thereto, and the pair of indentations 100 may be formed to have different indentation depths. In this case, the pair of indentations 100 may have asymmetric shapes.

[0057] The bottom surfaces 101 of the pair of indentations 100 may be formed to be inclined in a direction in which they approach each other as they go downward. The bottom surfaces 101 of the pair of indentations 100 may be connected to each other by a bridge 150, which will be described later.

[0058] The bottom surface 101 of the indentation 100 and the inner periphery 102a (see FIG. 8a) may be connected by an inner edge 114, and the outer periphery of the indentation 100 and a terrace 200 (described later) may be connected by an outer edge 115. The inner edge 114 and the outer edge 115 may be rounded curved surfaces having a predetermined radius of curvature.

[0059] The pair of terraces 200 may be located around the pair of indentations 100. The pair of terraces 200 may be formed with an inclination such that they approach each other as they go downward. More specifically, each terrace 200 may be formed alongside the bottom surface 101 of each indentation 100.

[0060] The angle θ formed by the pair of terraces 200 may be an obtuse angle. More specifically, the angle θ formed by the pair of terraces 200 may be 130 degrees to 170 degrees. This has the advantage of minimizing the space not occupied by the electrode assembly 20 after the case 10 is sealed, and preventing but-ears from occurring after the case 10 is sealed.

[0061] If the angle θ is less than 130 degrees, the free space may increase, and if the angle θ is more than 170 degrees, butt-ear may occur or excessive wrinkles may occur around the bending portion 300.

[0062] The angle α formed between the terrace 200 and the peripheral surface 102 of the indentation 100 may be an obtuse angle.

[0063] Each terrace 200 may have a substantially U-shape. More specifically, each terrace 200 may include a side 210 located on the opposite side of the bridge 150 across the indentation 100 and extending parallel to the bridge 150, and a pair of extensions 220 extending from both ends of the side 210 in the inclined direction of the terrace 200.

[0064] The pair of terraces 200 may be connected to each other by a bending portion 300. More specifically, the bending portion 300 may connect the lower ends of the extension portions 220 to each other.

[0065] The bending portion 300 may be formed to be rounded and convex downwards, so that the lower ends of the terraces 200 can be connected to each other without bending.

[0066] Therefore, the pair of terraces 200 can form a substantial "V" shape together with the bending portion 300.

[0067] The bridge 150 is located between the pair of indentations 100 and can connect the pair of indentations 100 to each other. The bridge 150 can connect the indentation spaces S1 of the pair of indentations 100 to each other.

[0068] More specifically, the bridge 150 may include a pair of connecting surfaces 151 formed at an angle approaching each other as they move upward from the bottom surfaces 101 of the pair of indentations 100, a first connecting edge 152 connecting the pair of connecting surfaces to each other, and a pair of second connecting edges 153 connecting the connecting surfaces 151 to the bottom surfaces 101 of the indentations 100.

[0069] The lower end of each connecting surface 151 may be connected to the bottom surface 101 of the indentation 100 by a second connecting edge 153. The upper ends of the pair of connecting surfaces 151 may be connected to each other by a first connecting edge 152.

[0070] Furthermore, each connecting surface 151 can cover on one side the indentation space S1 of the indentation 100. More specifically, the indentation space S1 can be defined by the bottom surface 101 and the surrounding surface 102 of the indentation 100 and the connecting surface 151 of the bridge 150.

[0071] The first connecting edge 152 may be formed to be rounded and convex upward, so that the upper ends of the pair of connecting surfaces 151 can be connected continuously without being bent.

[0072] Each second connecting edge 153 may be rounded and convex downward, so that the bottom surface 101 of the indentation 100 and the lower end of the connecting surface 151 can be connected continuously without bending.

[0073] Therefore, the bottom surfaces 101 of the pair of indentations 100 can form a substantial "W" shape together with the bridge 150.

[0074] 5 is an enlarged view of the bridge and its periphery shown in FIG. 4, and FIG. 6 is a view for explaining the detailed configuration of the pouch-type battery case shown in FIG.

[0075] The bending portion 300, the first connecting edge 152, the second connecting edge 153, the inner edge 114 and the outer edge 115 may be formed as curved surfaces having predetermined radii of curvature (R1 to R5), and it is preferable that each of the radii of curvature (R1 to R5) is maintained constant.

[0076] However, the present invention is not limited thereto, and each of the radii of curvature (R1 to R5) may be variable depending on the position. In this case, the radii of curvature (R1 to R5) may refer to the average radii of curvature of the bending portion 300, the first connecting edge 152, the second connecting edge 153, the inner edge 114, and the outer edge 115.

[0077] Meanwhile, the inner edge 114 and the outer edge 115 may form a predetermined clearance CL in the horizontal direction. More specifically, the clearance CL may refer to the horizontal distance between a boundary P2 between the inner periphery 102a of the indentation 100 (see FIG. 8a) and the inner edge 114, and a boundary P3 between the outer periphery 102b of the indentation 100 and the outer edge 115.

[0078] The clearance CL may be equal to or less than the radius of curvature R5 of the outer edge 115.

[0079] The clearance CL may be 0.5 mm or less, preferably 0.35 mm or less. The clearance CL may also be equal to or greater than the thickness of the pouch sheet P that is the base material of the case 10. That is, the clearance CL may be equal to or greater than the thickness of the terrace 200. As an example, the clearance CL may be 0.15 mm or greater.

[0080] This minimizes the space that is not occupied by the electrode assembly 20 after the case 10 is sealed, and also reduces the risk of cracks occurring during the forming process for forming the case 10.

[0081] If the clearance CL is greater than 0.5 mm, the free space may increase excessively. Conversely, if the clearance CL is smaller than the thickness of the terrace 200, cracks may occur during the forming process for forming the case 10.

[0082] Furthermore, the radius of curvature R4 of the inner edge 114 may be equal to or greater than the radius of curvature R5 of the outer edge 115.

[0083] The larger the radii of curvature R4, R5 of the inner edge 114 and the outer edge 115, the more the space not occupied by the electrode assembly 20 can be reduced after the case 10 is sealed. However, if the radii of curvature R4, R5 are too large, there is a limit to how sharp the shape of the case 10 can be manufactured, which can result in a less attractive appearance of the secondary battery 3 and a lower marketability. Therefore, it is preferable to appropriately design the radii of curvature R4, R5 of the inner edge 114 and the outer edge 115.

[0084] On the other hand, a virtual line VL can be defined that passes through the boundary P3 between the inner periphery 102a of the indentation portion 100 and the inner edge 114 and is perpendicular to the terrace 200. In this case, in the direction aligned with the terrace 200, the distance from the virtual line VL to the connecting surface 151 of the bridge 150 can be a first distance L1, and the distance from the virtual line VL to the boundary P1 between the terrace 200 and the bending portion 300 can be a second distance L2.

[0085] The second distance L2 may be shorter than the first distance L1. More specifically, the length L3 from the center of the bending portion 300, i.e., the lowest end, to the boundary P1 between the terrace 200 and the bending portion 300 may be shorter than the difference between the first distance L1 and the second distance L2. That is, the difference between the first distance L1 and the second distance L2 may be longer than half the length of the bending portion 300.

[0086] Therefore, when the case 10 is sealed after the bottom end of the bending portion 300 is folded, butt ears do not occur in the case 10.

[0087] In addition, the height of the bottom end of the bending portion 300 may be equal to or greater than the height of the top end of the first connecting edge 152 of the bridge 150 .

[0088] That is, the bending portion 300 and the first connecting edge 152 may form a predetermined step D in the vertical direction, or the bottom end of the bending portion 300 and the top end of the first connecting edge 152 may be located on the same horizontal plane so that the step D is 0. The step D may be called a forming depth.

[0089] FIG. 7 is a cross-sectional view of a pouch-type battery case manufacturing apparatus according to one embodiment of the present invention.

[0090] The pouch-type battery case manufacturing apparatus (hereinafter referred to as "manufacturing apparatus") according to the present invention may include a die 410 on which a pouch sheet P is placed, and a punch 420 that punches the pouch sheet P above the die 410. The manufacturing apparatus may further include a stripper 430 that fixes the pouch sheet P above the die 410.

[0091] The pouch sheet P may be the base material of the case 10. The pouch sheet P may be placed on the die 410 in an unfolded state or in a partially folded state.

[0092] The stripper 430 can be positioned around the punch 420. That is, the stripper 430 can accommodate at least a portion of the punch 420 and have an opening 432 that penetrates vertically.

[0093] The stripper 430 may be configured to be able to move up and down independently of the punch 420 .

[0094] At least one of the die 410 and the punch 420 may be configured to be movable up and down so that the distance between them can be changed.

[0095] For example, the die 410 may be raised with the pouch sheet P placed thereon, and the pouch sheet P may be fixed between the die 410 and the stripper 430. In this state, the die 410 may be further raised together with the stripper 430, and the pouch sheet P may be punched by the punch 420, thereby forming the case 10 described above.

[0096] As another example, the stripper 430 may descend before the punch 420, thereby fixing the pouch sheet P in a state in which it is placed on the die 410. In this state, the punch 420 may descend and punch the pouch sheet P, thereby forming the case 10 described above.

[0097] Each component of the manufacturing apparatus will be described in more detail below.

[0098] The die 410 may include a pair of mounting surfaces 411 that are inclined in a direction that separates them as they go upward, a pair of forming portions 412 that are recessed or penetrated downward from the pair of mounting surfaces 411, and a center portion 413 located between the pair of forming portions 412.

[0099] The pair of mounting surfaces 411 may form at least a part of the upper surface of the die 410. Each mounting surface 411 may be located around each molding portion 412. The pair of mounting surfaces 411 may be formed to be inclined in a direction such that they approach each other as they go downward.

[0100] The angle formed by the pair of mounting surfaces 411 may be an obtuse angle, and may correspond to the angle θ formed by the pair of terraces 200 of the case 10. In other words, the angle formed by the pair of mounting surfaces 411 may be 130 degrees to 170 degrees, and may be the same as or similar to the angle θ formed by the pair of terraces 200.

[0101] The lower ends of the pair of placement surfaces 411 may be connected to each other by a curved surface that is convex downward, and the curved surface may have a shape and a radius of curvature that correspond to the bending portion 300 of the case 10. More specifically, the radius of curvature of the curved surface may be the same as the radius of curvature R1 of the bending portion 300 or may be the same as the radius of curvature R1 of the bending portion 300 plus the thickness of the pouch sheet P.

[0102] A pressure surface 431 constituting at least a part of the bottom surface of the stripper 430 may be formed alongside the placement surface 411 of the die 410. Therefore, the edge of the pouch sheet P can be crimped between the pressure surface 431 of the stripper 430 and the placement surface 411 of the die 410, and can be formed as the terrace 200 of the case 10.

[0103] Meanwhile, each forming portion 412 of the die 410 may be cup-shaped and indented downward from the mounting surface 411, or may be open and penetrate downward. A punching portion 421 (described later) of the punch 420 is inserted into the forming portion 412 to punch the indented portion 100 of the case 10.

[0104] If forming portion 412 is open, air can be discharged through the opening during the punching operation of punch 420, which has the advantage of improving the formability of case 10.

[0105] The upper end of the inner periphery of the forming portion 412 and the placement surface 411 may be connected by a die edge 418 .

[0106] The die edge 418 may have a shape and a radius of curvature corresponding to the outer edge 115 of the case 10. More specifically, the radius of curvature of the die edge 418 may be the same as or similar to the radius of curvature R5 of the outer edge 115. Thus, the outer edge 115 may be formed by the die edge 418.

[0107] The center portion 413 can be located between the pair of molded portions 412. The center portion 413 can have a shape corresponding to the bridge 150 of the case 10.

[0108] More specifically, the center portion 413 may include a pair of inclined surfaces 414 that are inclined toward each other as they go upward, and a center edge 415 that connects the pair of inclined surfaces 414 to each other.

[0109] Each inclined surface 414 may cover one side of the interior space of the shaped portion 412. More specifically, the interior space of the shaped portion 412 may be defined by the inner periphery of the shaped portion 412 and the inclined surface 414 of the center portion 413.

[0110] The upper ends of the pair of inclined surfaces 414 may be connected to each other by a center edge 415. The center edge 415 may be formed to be convexly rounded upward. Therefore, the center edge 415 can connect the upper ends of the pair of inclined surfaces 414 so that they are continuously connected without being folded.

[0111] The center edge 415 may have a shape and a radius of curvature corresponding to the first connecting edge 152 of the case 10. More specifically, the radius of curvature of the center edge 415 may be the same as or similar to the radius of curvature R2 of the first connecting edge 152.

[0112] The height of the uppermost end of the center edge 415 may be equal to or lower than the height of the lowermost end of the curved surface connecting the pair of placement surfaces 411 .

[0113] Meanwhile, the punch 420 may include a pair of punching portions 421 that are inserted into the pair of forming portions 412 of the die 410 .

[0114] The pair of punching portions 421 can be separated from each other, and in this case, the opposing surfaces 423 of the pair of punching portions 421 can face each other.

[0115] However, the present invention is not limited to this, and a configuration in which a pair of punching portions 421 are connected to each other within a range that does not interfere with the center portion 413 of the die 410 is also possible.

[0116] Each punching portion 421 may have a shape corresponding to the indentation 100 of the case 10. That is, the bottom surfaces 422 of the pair of punching portions 421 may be formed to be inclined in a direction in which the height decreases as they approach each other.

[0117] Bottom surfaces 422 of the pair of punching portions 421 may be formed to be inclined in a direction aligned with the mounting surface 411 of the die 410. In other words, the angle formed by the bottom surfaces 422 of the pair of punching portions 421 can correspond to the angle θ formed by the pair of mounting surfaces 200 of the case 10.

[0118] That is, the angle formed by the bottom surfaces 422 of the pair of punching portions 421 may be an obtuse angle, more specifically, 130 degrees to 170 degrees.

[0119] A part of the pouch sheet P can be pressed by a punching portion 421 of a punch 420 inserted into a forming portion 412 of a die 410 and can be formed as the indentation portion 100 of the case 10.

[0120] The bottom surface 422 of the punching portion 421 and the lower end of the outer periphery may be connected by a punching edge 427. The outer periphery of the punching portion 421 may face the inner periphery of the stripper 430.

[0121] The punching edge 427 may have a shape and a radius of curvature corresponding to the inner edge 114 of the case 10. More specifically, the radius of curvature of the punching edge 427 may be the same as or similar to the radius of curvature R4 of the inner edge 114. Thus, the inner edge 114 may be formed by the punching edge 427.

[0122] The radius of curvature R4 of the inner edge 114 of the case 10 is equal to or greater than the radius of curvature R5 of the outer edge 115 , so that the radius of curvature of the punching edge 427 can be equal to or greater than the radius of curvature of the die edge 418 .

[0123] Similarly to the horizontal clearance CL between the inner edge 114 and the outer edge 115 of the case 10, the horizontal clearance between the punching edge 427 and the die edge 418 may be 0.5 mm or less, preferably 0.35 mm or less.

[0124] Furthermore, since the horizontal clearance CL between the inner edge 114 and the outer edge 115 is less than the radius of curvature R5 of the outer edge 115, the horizontal clearance between the punching edge 427 and the die edge 418 can be less than the radius of curvature of the die edge 418.

[0125] Furthermore, the bottom surface 422 and the lower end of the opposing surface 423 of the punching portion 421 may be connected by a side edge 424. That is, the side edge 424 may be formed at the lower end of each bottom surface 422.

[0126] The side edge 424 may have a downwardly convex rounded shape. The side edge 424 may have a shape and radius of curvature corresponding to the second connecting edge 153 of the case 10. More specifically, the radius of curvature of the side edge 424 may be the same as or similar to the radius of curvature R3 of the second connecting edge 153.

[0127] Therefore, a portion of the pouch sheet P can be formed as the bridge 150 of the case 10 by the center portion 413 of the die 410 and the side edge 424 of the punch 420 .

[0128] 8a and 8b are a first experimental example according to one embodiment of the present invention, FIGS. 9a and 9b are a second experimental example according to one embodiment of the present invention, FIGS. 10a and 10b are a first comparative example, FIGS. 11a and 11b are a second comparative example, and FIGS. 12a and 12b are a third comparative example.

[0129] 8a and 9a show first and second experimental examples in which the angle θ between the pair of terraces 200 of the case 10 is 140 degrees, and the horizontal clearances CL between the inner edge 114 and the outer edge 115 are 0.35 mm and 0.5 mm, respectively. In the first and second experimental examples, the angle θ between the pair of terraces 200 of the case 10 is 140 degrees, the radius of curvature R4 of the inner edge 114 is 2.0 mm, and the radius of curvature R5 of the outer edge 115 is 1.5 mm, which are the same.

[0130] 10a shows a first comparative example in which the horizontal clearance CL between the inner edge 114 and the outer edge 115 is set to 1 mm. That is, in the first comparative example, only the clearance CL is increased compared to the first and second experimental examples.

[0131] 8b and 9b, when one terrace 200 is rotated so that it is horizontal, the horizontal clearances CL between the inner edge 114 and the outer edge 115 on the one terrace 200 side are measured to be 1.09 mm and 1.25 mm, respectively. That is, when the cases 10 according to the first and second experimental examples are folded and sealed to form secondary batteries, the horizontal clearances CL between the inner edge 114 and the outer edge 115 are measured to be 1.09 mm and 1.25 mm, respectively.

[0132] In contrast, in the case of the first comparative example, when one terrace 200 is rotated so that it is horizontal, as shown in Fig. 10b, the horizontal clearance CL between the inner edge 114 and the outer edge 115 on the one terrace 200 side is measured to be 1.78 mm. In other words, when the case 10 according to the first comparative example is folded and sealed to form a secondary battery, the horizontal clearance CL between the inner edge 114 and the outer edge 115 is measured to be 1.78 mm.

[0133] That is, it can be seen that the smaller the clearance CL between the inner edge 114 and the outer edge 115, the smaller the empty space not occupied by the electrode assembly 20.

[0134] 11a shows a second comparative example in which the angle θ between a pair of terraces 200 of the case 10 is 120 degrees and the horizontal clearance CL between the inner edge 114 and the outer edge 115 is 0.5 mm. That is, in the second comparative example, only the angle θ is reduced compared to the second experimental example.

[0135] 11b, when one terrace 200 is rotated so that it is horizontal, the horizontal clearance CL between the inner edge 114 and the outer edge 115 on the one terrace 200 side is measured to be 1.9 mm. That is, when the case 10 according to the second comparative example is folded and sealed to form a secondary battery, the horizontal clearance CL between the inner edge 114 and the outer edge 115 is measured to be 1.9 mm.

[0136] That is, it can be seen that the larger the angle θ between the pair of terraces 200, the smaller the empty space that is not occupied by the electrode assembly 20.

[0137] However, as mentioned above, if the angle θ is too large, butt-ears may occur or excessive wrinkles may occur around the bending portion 300, so it is preferable that the angle θ is 130 degrees to 170 degrees.

[0138] On the other hand, FIG. 12a shows a third comparative example in which the radius of curvature R4 of the inner edge 114 and the radius of curvature R5 of the outer edge 115 in the second comparative example shown in FIG. 11a are reduced to 1.0 mm.

[0139] 12b, when one terrace 200 is rotated so that it is horizontal, the horizontal clearance CL between the inner edge 114 and the outer edge 115 on the one terrace 200 side is measured to be 2.53 mm. That is, when the case 10 according to the third comparative example is folded and sealed to form a secondary battery, the horizontal clearance CL between the inner edge 114 and the outer edge 115 is measured to be 2.53 mm.

[0140] That is, it can be seen that the larger the radii of curvature R4, R5 of the inner edge 114 and the outer edge 115, the smaller the free space not occupied by the electrode assembly 20. However, as mentioned above, if the radii of curvature R4, R5 are excessively large, there is a limit to how sharp a shape the case 10 can be manufactured into, which results in an unattractive appearance of the secondary battery 3 and a decrease in merchantability. Therefore, it is preferable to appropriately design the radii of curvature R4, R5 of the inner edge 114 and the outer edge 115.

[0141] FIG. 13 is a plan view of a pouch-type secondary battery according to one embodiment of the present invention, FIG. 14 is a plan view showing an enlarged view of a corner of the peripheral part and its surroundings shown in FIG. 13, and FIG. 15 is a perspective view showing an enlarged view of the corner of the peripheral part and its surroundings shown in FIG. 13.

[0142] With the electrode assembly 20 (see FIG. 2) disposed between the pair of recesses 100 of the case 10, the bending portion 300 is folded to seal the pair of terraces 200 together, thereby forming a secondary battery according to an embodiment of the present invention.

[0143] The secondary battery may include a receiving portion that receives the electrode assembly 20 (see FIG. 2), a folding portion that forms a part of the peripheral surface of the receiving portion, and a peripheral portion that extends from another part of the peripheral surface of the receiving portion.

[0144] More specifically, the storage portion is formed by a pair of communicating indentations 100, and will be hereinafter referred to as "100" for convenience, which is the same reference numeral as the indentation 10. The folding portion is formed by folding a bridge 150, and will be hereinafter referred to as "150" for convenience, which is the same reference numeral as the bridge 150. The surrounding portion is formed by a pair of attached terraces 200, and will be hereinafter referred to as "200" for convenience, which is the same reference numeral as the terraces.

[0145] Therefore, in the secondary battery according to the embodiment of the present invention, the inner edge 114 (see FIG. 6) can connect the inner top surface or the inner bottom surface of the storage portion 100 to the inner periphery of the storage portion 100. Also, the outer edge 115 (see FIG. 6) can connect the outer periphery of the storage portion 100 to the periphery portion 200.

[0146] As described above, the radius of curvature R4 of the inner edge 114 may be greater than or equal to the radius of curvature R5 of the outer edge 115, and the horizontal clearance CL between the inner edge 114 and the outer edge 115 may be smaller than the radius of curvature R4 of the inner edge 114.

[0147] This can be confirmed by disassembling the secondary battery itself, but is not limited to this and can also be confirmed by methods such as CT (Computerized Tomography), MRI (Magnetic Resonance Imaging), X-Ray, etc. By using such methods, the above-mentioned characteristics of case 10 can be confirmed without disassembling the secondary battery.

[0148] Meanwhile, the peripheral portion 200 may include a long side portion formed by the sides 210 of the pair of terraces 200 adhering to each other, and a short side portion formed by the extensions 220 of the pair of terraces 200 adhering to each other. Hereinafter, the long side portion will be denoted by the same reference numeral "210" as the side 210, and the short side portion will be denoted by the same reference numeral "220" as the extension 220.

[0149] The long side 210 may extend in the length direction of the receiving unit 100, and the short side 220 may extend in the width direction of the receiving unit 100.

[0150] The peripheral portion 200 may be sealed by heat sealing, that is, the peripheral portion 200 may have a sealing portion formed thereon that extends along the peripheral portion.

[0151] More specifically, each short side 220 may include a sealing portion 221 and a non-sealing portion 222 .

[0152] The sealing portion 221 may be formed long in the length direction of the short side portion 220. A part of the sealing portion 221 may be formed by fusing a pair of extension portions 220 to each other, and another part may be formed by fusing the extension portion 220 to the insulating portion 23 (see FIG. 2) surrounding the electrode lead 22.

[0153] The non-sealing portion 222 may be formed long in the length direction of the short side portion 220 and positioned more inward than the sealing portion 221. This is because if the sealing portion 221 is too close to the receiving portion 100, the electrode tab 21 (see FIG. 2) of the electrode assembly 20 may be damaged during the heat sealing process.

[0154] That is, the non-sealing portion 222 may be located between the sealing portion 221 and the receiving portion 100. The electrode tab 21 (see FIG. 2) of the electrode assembly 20 may be located in the non-sealing portion 222.

[0155] Therefore, the corner of the short side 220 on the folding portion 150 side may include a corner 221a of the sealing portion 221 and a corner 222a of the non-sealing portion 222. The corner on the folding portion 150 side may refer to a corner formed when the bending portion 300 of the case 10 is folded.

[0156] Hereinafter, for convenience of explanation, the corner of the non-sealing portion 222 will be named a first corner 222a, and the corner of the sealing portion 221 will be named a second corner 221a.

[0157] The first corner 222a may be adjacent to the folding portion 150. The first corner 222a may be slightly curved or wrinkled rather than being straight, but is not limited thereto.

[0158] The second corner 221a may extend in the opposite direction from the folding portion 150 at the first corner 222a. That is, the first corner 222a may be located between the second corner 221a and the folding portion 150.

[0159] The second corner 221a has a linear shape and can have a thickness thinner than the first corner 222a. The second corner 221a may protrude further than the first corner 222a in the width direction of the storage section 100. This is because the first corner 222a is a corner of the non-sealing section 222, while the second corner 221a is a corner of the sealing section 221.

[0160] The first corner 222a and the second corner 221a may not protrude beyond the folding section 150 in the width direction of the storage section 100. In other words, the first corner 222a and the second corner 221a may not protrude beyond an imaginary line VL2 that contacts the folding section 150 and extends linearly in the length direction of the folding section 150. Furthermore, the second corner 221a may be closer to the imaginary line VL2 than the first corner 222a.

[0161] That is, in conventional secondary batteries, the portion corresponding to the second corner 221a protrudes from the folding portion 150 to form a butt-ear, but the secondary battery according to the present invention does not have a butt-ear due to the configuration of the case 10 described above.

[0162] In addition, the corner of the short side 220 on the folding part 150 side may further include a boundary part 223 connecting the first corner 222 a and the folding part 150 .

[0163] The boundary portion 223 is located between the first corner portion 222a and the folding portion 150, and can protrude beyond the first corner portion 222a in the width direction of the storage portion 100.

[0164] It is preferable that the boundary portion 223 does not protrude beyond the folding portion 150 in the width direction of the storage portion 100. More specifically, the degree of protrusion of the boundary portion 223 may vary depending on the step D (see FIG. 6) between the bending portion 300 and the first connecting edge 152 described above, and therefore it is preferable to design an appropriate step D.

[0165] FIG. 16 is a diagram showing a pouch-type battery case according to another embodiment of the present invention in an unfolded state.

[0166] Below, the overlapping content with the above content will be cited, and the differences will be mainly explained.

[0167] The peripheral surface of each indentation 100 may include an extension surface located opposite the bridge 150 and extending in the length direction of the indentation 100, and a pair of side surfaces 103 extending from both ends of the extension surface in the width direction of the indentation 100 and connected to the connecting surface 151.

[0168] The region 154 where the side surface 103 and the connecting surface 151 of the bridge 150 are connected may be formed as a curved surface having a predetermined radius of curvature, thereby reducing wrinkles that may occur around the connecting portion 150 when the case 10 is sealed.

[0169] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations are possible by a person having ordinary knowledge in the technical field to which the present invention pertains, without departing from the essential characteristics of the present invention.

[0170] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0171] The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0172] 10: Case 20: Electrode assembly 100: (case) recess, (secondary battery) storage area 114: Inner Edge 115: Outer Edge 150: (case) bridge, (secondary battery) folding part 151: Connecting surface 152: First connecting edge 153: Second connecting edge 200: Terrace (of the case), surrounding area (of the secondary battery) 210: Side (of case), long side (of secondary battery) 220: (case) extension, (secondary battery) short side 221: Sealing section 221a:Second corner 222: Non-sealing part 222a: 1st corner 223: Boundary 300: Bending section 410: Die 411: Placement surface 412: Molding section 413: Center section 420: Punch 422: Punching section 423:Connection part 414, 424: Inclined surface 415, 425: Center edge 416, 426: Side edge 417: Lower Edge 418: Die Edge 427: Punching Edge

Claims

1. A pouch-type battery case that houses an electrode assembly in which electrodes and separators are alternately stacked, a pair of indented portions having an indented shape; a pair of terraces that are located around the pair of indentations when the pouch-type battery case is unfolded and that are inclined in directions that approach each other as they approach the indentations; a bridge located between the pair of indentations, connecting the pair of indentations, and having a pair of connecting surfaces formed inclined in directions approaching each other as they move from the bottom surfaces of the pair of indentations toward the terrace, When the pouch-type battery case is unfolded, the angle formed by the pair of terraces is an obtuse angle; In a folded state of the pouch-type battery case, the recessed portion protrudes outward beyond the terrace in the lateral direction of the pouch-type battery case.

2. The pouch-type battery case according to claim 1 , wherein bottom surfaces of the pair of recesses are inclined in directions that move away from each other as they go upward when the pouch-type battery case is unfolded.

3. 2. The pouch-type battery case according to claim 1, wherein the angle formed by the pair of terraces is 130 degrees to 170 degrees when the pouch-type battery case is unfolded.

4. an inner edge connecting the inner periphery of the indentation portion and the bottom surface of the indentation portion; an outer edge connecting the outer periphery of the indentation and the terrace, The pouch-type battery case according to claim 1 , wherein the radius of curvature of the inner edge is equal to or greater than the radius of curvature of the outer edge.

5. 5. The pouch-type battery case according to claim 4, wherein when the pouch-type battery case is unfolded, a horizontal clearance between the inner edge and the outer edge is 0.5 mm or less.

6. 5. The pouch-type battery case according to claim 4, wherein when the pouch-type battery case is unfolded, a horizontal clearance between the inner edge and the outer edge is 0.35 mm or less.

7. 5. The pouch-type battery case according to claim 4, wherein when the pouch-type battery case is unfolded, a horizontal clearance between the inner edge and the outer edge is equal to or less than a radius of curvature of the outer edge.

8. With the pouch-type battery case unfolded, The pair of terraces are connected to each other, and the bending portion is rounded downward, and The bridge further includes a first connecting edge that connects the pair of connecting surfaces and is rounded upwardly and convexly. The pouch-type battery case according to claim 4 , wherein the height of the bottom end of the bent portion is equal to or greater than the height of the top end of the first connecting edge.

9. When the pouch-type battery case is unfolded, the bridge is The pouch-type battery case according to claim 8 , further comprising a pair of second connecting edges that connect the pair of connecting surfaces to bottom surfaces of the pair of recessed portions and are rounded downwardly.

10. With the pouch-type battery case unfolded, With respect to an imaginary line that passes through the boundary between the inner periphery of the indentation and the inner edge and is perpendicular to the terrace, a first distance from the virtual line to the connecting surface in a direction aligned with the terrace; The pouch-type battery case according to claim 8 , wherein a second distance from the imaginary line to a boundary between the terrace and the bent portion in a direction aligned with the terrace is shorter than the first distance.

11. With the pouch-type battery case unfolded, The pouch-type battery case according to claim 10 , wherein the length from the center of the bent portion to the boundary between the terrace and the bent portion is shorter than the difference between the first distance and the second distance.

12. an electrode assembly in which electrodes and separators are alternately stacked; A pouch-type secondary battery comprising: the pouch-type battery case according to claim 1 .

13. an electrode assembly having a structure in which electrodes and separators are alternately stacked; a pouch-type battery case having a storage portion that houses the electrode assembly, The pouch-type battery case includes: a folding portion that forms a part of the surrounding surface of the storage portion; a surrounding portion expanded at another part of the surrounding surface of the storage portion, The corners of the surrounding portion are a first corner portion adjacent to the folding portion; a second corner portion extending in a direction opposite to the folding portion at the first corner portion and having a thickness thinner than that of the first corner portion; a boundary portion connecting the first corner portion and the folding portion and protruding from the first corner portion in a width direction of the storage portion, a pouch-type secondary battery, wherein, when the pouch-type battery case is folded, the folding portion protrudes outward beyond the peripheral portion in the lateral direction of the pouch-type battery case.

14. The pouch-type secondary battery according to claim 13 , wherein the first corner and the second corner do not protrude beyond the folding portion in the width direction of the storage portion.

15. The pouch-type secondary battery according to claim 13 or 14, wherein the second corner portion protrudes more than the first corner portion in the width direction of the storage portion.

16. The pouch-type secondary battery according to claim 13 , wherein the boundary portion does not protrude beyond the folding portion in the width direction of the storage portion.

17. an inner edge connecting the inner top surface or the inner bottom surface of the storage section to the inner periphery of the storage section; an outer edge connecting the outer periphery of the storage portion and the peripheral portion; The pouch-type secondary battery according to claim 13 , wherein the radius of curvature of the inner edge is equal to or greater than the radius of curvature of the outer edge.

18. The pouch-type secondary battery according to claim 17 , wherein a horizontal clearance between the inner edge and the outer edge is equal to or less than a radius of curvature of the outer edge.

19. A pouch-type battery case manufacturing apparatus that uses a punch to form a pouch sheet placed on a die, The die is A pair of placement surfaces inclined in directions that move apart from each other as they go upward; a pair of molding portions recessed downward from or penetrating the pair of mounting surfaces; a center portion located between the pair of molding portions, The punch is a pair of punching portions inserted into the pair of forming portions and having bottom surfaces inclined in a direction in which the height decreases as the punching portions approach each other; the angle formed by the pair of mounting surfaces is an obtuse angle, a pouch-type battery case manufacturing device, wherein, when the pouch-type battery case is folded, the recessed portion formed by the molding portion protrudes outward in the lateral direction of the pouch-type battery case beyond the bridge formed by the center portion.

20. 20. The pouch-type battery case manufacturing apparatus according to claim 19, wherein the angle formed by the pair of mounting surfaces is 130 degrees to 170 degrees.

21. the die further includes a die edge connecting an inner periphery of the molding portion and the placement surface; The punch further includes a punching edge connecting an outer periphery of the punching portion and a bottom surface of the punching portion, 21. The pouch-shaped battery case manufacturing apparatus according to claim 19, wherein the radius of curvature of the punching edge is equal to or greater than the radius of curvature of the die edge.

22. 22. The pouch-shaped battery case manufacturing apparatus according to claim 21, wherein a horizontal clearance between the die edge and the punching edge is 0.5 mm or less.

23. The pouch-shaped battery case manufacturing apparatus according to claim 21 , wherein a horizontal clearance between the die edge and the punching edge is equal to or less than a radius of curvature of the die edge.

24. The center portion is The pouch-type battery case manufacturing apparatus according to claim 19, comprising a pair of inclined surfaces that are inclined downwardly and away from each other.

25. The center portion is The pouch-shaped battery case manufacturing apparatus according to claim 24 , further comprising an upwardly rounded center edge connecting the pair of inclined surfaces.

26. The punching portion is The pouch-shaped battery case manufacturing apparatus according to claim 19 , further comprising a pair of side edges formed at a lower end of the bottom surface and rounded downward in a convex shape.

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