Method for sealing pouch-type battery cell, and pouch-type battery cell

Abstract

The method for sealing a pouch-type battery cell, according to the present invention, is characterized in that at least one of the upper surface of a primary sealing part and the lower surface of the primary sealing part is adhered to a bent surface of a pouch exterior material, formed by bending, at a portion where the primary sealing part and the bent part intersect.

Description

Sealing method for pouch-type battery cells and pouch-type battery cells

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0025677, filed on February 22, 2024.

[0002] The present invention relates to a method for sealing a pouch-shaped battery cell and a pouch-shaped battery cell manufactured by the sealing method.

[0003]

[0004] Secondary batteries are widely used as power sources for mobile devices such as cell phones, laptops, and camcorders. The use of lithium secondary batteries, in particular, is rapidly increasing due to their high operating voltage and high energy density per unit weight.

[0005] These lithium secondary batteries mainly use lithium oxide as the positive electrode active material and carbon material as the negative electrode active material, and are generally classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the type of electrolyte used, and are also classified into cylindrical, prismatic, and pouch-type secondary batteries depending on the external shape of the battery. In terms of battery shape, there is a high demand for prismatic and pouch-type secondary batteries that can be applied to products such as mobile phones due to their thin thickness.

[0006] A pouch-type secondary battery is structured such that an electrode assembly is embedded in a pouch outer material made of a laminate sheet including a metal layer (e.g., aluminum). That is, the pouch-type secondary battery is manufactured by forming a cup portion for mounting the electrode assembly in the laminate sheet, and then thermally fusing a separate laminate sheet or an extended laminate sheet separated from the laminate sheet while the electrode assembly is mounted in the cup portion.

[0007] In the case of a detachable pouch outer material, since two units of laminate sheets are joined by overlapping and sealing each other, during the manufacturing process of the secondary battery, the cups on both sides must be overlapped in the correct position with the electrode assembly built in. If the electrode assembly is not installed in the correct position, an internal short circuit will occur, so a separate guide device is required, which increases the manufacturing cost. In addition, since the two units of laminate sheets are joined on four sides to form a sealing portion, all four sides come into contact with the atmosphere, which greatly increases the possibility of air inflow during long-term use, and thus has the problem of shortening the life of the battery.

[0008] To solve these problems, many technologies have been introduced for methods of overlapping a single laminate sheet formed with two cup portions by folding and sealing the three-sided openings.

[0009] Fig. 1 is a top view of a pouch outer material of a conventional sealing pouch-type battery cell. Fig. 2 is a cross-sectional schematic diagram of a step-by-step method for sealing a pouch-type battery cell using the pouch outer material of Fig. 1, corresponding to cross-section II-II' of Fig. 1. Fig. 3 is a top view of a pouch-type battery cell manufactured using the same method as Fig. 2. Fig. 4 is a photograph of a portion of a battery cell manufactured according to a conventional method for sealing a pouch-type battery cell.

[0010] First, referring to (a) of FIG. 1 and FIG. 2, two cup parts (133a, 133b) of perfectly corresponding shapes and sizes are formed on a pouch outer material (13) of one unit so as to be spaced apart by a predetermined distance (d) greater than the thickness of the electrode assembly (10).

[0011] Next, as in (b) of FIG. 2, with the electrode assembly (10) mounted on the cup portion (133a or 133b) on one side, the central portion (F) between the cup portions (133a, 133b) is folded as in (c) of FIG. 2, the cup portions (133a, 133b) are covered as in (d) of FIG. 2, and the open portions of the remaining three sides except for the folded portion are sealed (S), thereby manufacturing a pouch-type battery cell (1) as in FIG. 3.

[0012] The pouch-shaped battery cell (1) sealed by this conventional sealing method has a protruding portion (W) instead of a flat folded portion, as shown in (d) of Fig. 2. In addition, the pouch-shaped battery cell (1) sealed by this conventional sealing method has a corner portion (CS) where the sealing portion and the folded portion intersect, as shown in Fig. 4, that has a bat ear protruding outward from the battery cell (10). If the protruding portion (W) or the bat ear increases in size, it has disadvantages in terms of utilization of the internal space of the battery module or battery pack and cooling.

[0013] Accordingly, there is a need to develop a technology for sealing pouch-type battery cells that prevents the formation of bat ears or protrusions at the corners where the sealing portion and the bending portion intersect.

[0014]

[0015] The technical idea of ​​the present invention is to provide a sealing method in which the sealing portion does not protrude outward from the battery cell, particularly at the intersection of the sealing portion and the bending portion, and a pouch-shaped battery cell having such a shape, without having bat ears.

[0016]

[0017] According to exemplary embodiments of the present invention for solving the above-described problem, a method for sealing a pouch-type battery cell includes a placement step of arranging an electrode assembly on a pouch outer case so that side surfaces of the electrode assembly correspond between two fold lines located at the center of the pouch outer case; and a primary sealing step of forming a primary seal by sealing open portions other than an open portion facing a fold portion among three open portions while the pouch outer case is folded so that the pouch outer case surrounds the electrode assembly; and in the primary sealing step, at least one of an upper surface of the primary sealing portion and a lower surface of the primary sealing portion is adhered to a folded surface of the pouch outer case formed by folding at a portion where the primary sealing portion and the folded portion intersect.

[0018] In exemplary embodiments, the folded surface may be formed by folding twice along the two fold lines.

[0019] In exemplary embodiments, the folded surface may have a flat surface along the side of the electrode assembly.

[0020] In exemplary embodiments, the first sealing step may be performed while the folded surface of the pouch outer material is in close contact with the side surface of the electrode assembly.

[0021] In exemplary embodiments, the portion where the first sealing portion and the bending portion intersect may be sealed in an “L” shape.

[0022] In exemplary embodiments, the pouch outer shell may have a cup portion that is recessed inward from the plane of the pouch outer shell only on one side of the two fold lines, based on a second direction perpendicular to the first direction, which is the extension direction of the two fold lines. At this time, the other side of the two fold lines may have a flat shape based on the second direction. At this time, the cup portion may be a hat-shaped cup portion whose recessed depth is constant along the second direction.

[0023] In exemplary embodiments, the pouch outer material includes a first pouch outer material having the cup portion and a second pouch outer material not having the cup portion, and in the first sealing step, the second pouch outer material can be adhered to the folded surface.

[0024] In exemplary embodiments, the pouch outer material may have cup portions recessed internally from the plane of the pouch outer material on one side and the other side of the two fold lines, respectively, with respect to a second direction perpendicular to the first direction, which is the extension direction of the two fold lines, and one cup portion may be an inclined cup portion whose recessed depth increases as it gets farther from the fold line with respect to the second direction, and the other cup portion may be a hat-shaped cup portion whose recessed depth is constant along the second direction.

[0025] In exemplary embodiments, the pouch outer material includes a first pouch outer material having the hat-shaped cup portion and a second pouch outer material having the inclined cup portion, and in the first sealing step, the second pouch outer material can be adhered to the folded surface.

[0026] In exemplary embodiments, the distance between the two bending lines may correspond to the thickness of the electrode assembly, which is the length of the side of the electrode assembly.

[0027] A method for sealing a pouch-shaped battery cell according to exemplary embodiments may further include an electrolyte injection step of injecting an electrolyte into the interior of a pouch outer material through a third opening opposite the folded portion; and a second sealing step of sealing the third opening.

[0028] According to exemplary embodiments, a pouch-type battery cell includes a pouch outer case having an electrode assembly and an electrolyte embedded therein, a sealing portion heat-sealed along an edge of the pouch outer case; and a folded surface formed by folding the pouch outer case twice along two fold lines so that the pouch outer case wraps around one of the side surfaces of the electrode assembly; wherein the sealing portion includes a primary sealing portion parallel to a second direction perpendicular to a first direction which is an extension direction of the fold lines; and a secondary sealing portion facing the fold lines based on the second direction; wherein at least one of an upper surface of the primary sealing portion and a lower surface of the primary sealing portion is bonded to the folded surface at a portion where the primary sealing portion and the folded surface intersect.

[0029] In exemplary embodiments, the portion where the first sealing portion and the folded surface intersect may be sealed in an “L” shape.

[0030] In exemplary embodiments, the folded surface of the pouch outer material does not have a protrusion that protrudes outward from the plane of the folded surface.

[0031]

[0032] According to exemplary embodiments of the present invention, the bending portion has a flat bending surface, and at least one of the upper surface of the sealing portion and the lower surface of the sealing portion is bonded to the bending surface at the corner sealing portion where the sealing portion and the bending portion intersect, so that the formation of bat ears or protrusions, which is a problem of the prior art, can be prevented.

[0033] According to exemplary embodiments of the present invention, the corner sealing portion, which is the area where the sealing portion and the bending portion intersect, is sealed in an "L" shape to prevent the formation of bat ears or protrusions. In addition, by controlling the sealing strength of the "L"-shaped sealed portion, direct gas venting through the corner sealing portion can be induced in abnormal situations.

[0034] According to exemplary embodiments of the present invention, the folded surface of the pouch outer case corresponding to the thickness surface of the electrode assembly is flat, and the folded surface does not have a protrusion or bat ear protruding from the plane of the folded surface, so that unnecessary space is eliminated, thereby maximizing the electrode assembly area within the pouch outer case. Accordingly, there is an effect of improving the energy density of the cell. In addition, as a result of increasing the specific surface area of ​​the battery cell in contact with the cooling member in the battery pack or battery module unit, the cooling efficiency can be improved.

[0035] According to exemplary embodiments of the present invention, a portion of the pouch outer material that was consumed in the protrusion or bat ear in the conventional technology can contribute to increasing the space of the gas pocket portion around the terrace portion.

[0036] According to exemplary embodiments of the present invention, the pouch outer material is bent into a "ㄷ" shape to cover the thickness of the electrode assembly. This facilitates the sealing of the corners in an "L" shape. Furthermore, since there is no need to form a recessed groove in the pouch outer material to accommodate the thickness of the electrode assembly, damage to the pouch outer material caused by stress generated during the recessed groove forming process can be reduced.

[0037]

[0038] Figure 1 is a top view of the pouch outer material of a conventional pouch-type secondary battery.

[0039] Fig. 2 is a cross-sectional schematic diagram of a conventional pouch-type battery cell sealing method, corresponding to the II-II' cross-section of Fig. 1.

[0040] Figure 3 is a top view of a pouch-shaped battery cell manufactured using the same method as Figure 2.

[0041] Figure 4 is a photograph of a portion of a battery cell manufactured according to a conventional pouch-type battery cell sealing method.

[0042] FIG. 5 is a flowchart illustrating a sealing method of a pouch-type battery cell according to exemplary embodiments.

[0043] Figure 6 is an assembly diagram of a pouch-type battery cell according to exemplary embodiments.

[0044] FIG. 7 is a cross-sectional view of a pouch outer material according to exemplary embodiments, taken along line AA of FIG. 6.

[0045] Fig. 8 is a cross-sectional view showing an electrode assembly arranged on the pouch outer material of Fig. 7.

[0046] Fig. 9 is a cross-sectional view showing the appearance of the pouch outer material being bent in Fig. 8.

[0047] Fig. 10 is a cross-sectional view showing the pouch outer material in Fig. 8 folded.

[0048] Fig. 11 is a top view showing the pouch outer material in Fig. 8 folded.

[0049] Figure 12 is a top view of a pouch-type battery cell after performing the first sealing step.

[0050] FIG. 13 is an enlarged view of the AA' cross-section of portion C of FIG. 11 for explaining the first sealing step according to exemplary embodiments.

[0051] FIG. 14 is an enlarged view of the BB' cross-section of portion C of FIG. 11 for explaining the first sealing step according to exemplary embodiments.

[0052] Figure 15 is an assembly diagram of a pouch-type battery cell according to other embodiments.

[0053] FIG. 16 is a flowchart illustrating a sealing method of a pouch-type battery cell according to exemplary embodiments.

[0054] FIG. 17 is a perspective view of a pouch-type battery cell according to exemplary embodiments of the present invention.

[0055] Figure 18 is a top view of Figure 17.

[0056]

[0057] [Explanation of symbols]

[0058] 1: Pouch-type battery cell

[0059] 10: Electrode assembly

[0060] T: Thickness of the electrode assembly

[0061] 11: Electrode tab

[0062] 111: Positive tab

[0063] 112: Negative tab

[0064] 12: Electrode leads

[0065] 121: Positive lead

[0066] 122: Negative lead

[0067] 14: Insulation

[0068] 13: Pouch outer material

[0069] 131: First pouch outer material

[0070] 132: Second pouch outer material

[0071] 133: Cup

[0072] 1341, 1342: First sealing

[0073] 1343: Second Seal

[0074] 1341c, 1342c: Corner sealing

[0075] FS: Folding surface

[0076] 50: Sealing tool

[0077]

[0078] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0079] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0080] Therefore, it should be understood that the embodiments described in the present disclosure and the configurations illustrated in the drawings are merely the most preferred embodiments of the present disclosure and do not represent all of the technical ideas of the present disclosure, and that there may be various equivalents and modified examples that can replace them at the time of filing of the present disclosure.

[0081] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0082] In this specification, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0083] Since the embodiments of the present disclosure are provided to more fully explain the present invention to those skilled in the art, the shapes and sizes of components in the drawings may be exaggerated, omitted, or schematically illustrated for clearer explanation. Accordingly, the sizes and proportions of each component do not fully reflect the actual sizes or proportions.

[0084] In this specification, the first and second bend lines are bending lines along which the pouch outer material is to be bent.

[0085]

[0086] (Example 1)

[0087] FIG. 5 is a flowchart for explaining a sealing method (hereinafter referred to as “sealing method”) of a pouch-type battery cell according to exemplary embodiments. FIG. 6 is an assembly diagram of a pouch-type battery cell according to exemplary embodiments. FIG. 7 is a cross-sectional view taken along line AA of FIG. 6 of a pouch outer case according to exemplary embodiments. FIG. 8 is a cross-sectional view showing an electrode assembly arranged on the pouch outer case of FIG. 7. FIG. 9 is a cross-sectional view showing an appearance of the pouch outer case being bent in FIG. 8. FIG. 10 is a cross-sectional view showing an appearance of the pouch outer case being bent in FIG. 8. FIG. 11 is a top view showing an appearance of the pouch outer case being bent in FIG. 8.

[0088] A sealing method according to exemplary embodiments of the present invention is a method of placing an electrode assembly on a unit of pouch outer material having a single cup portion formed thereon, folding the pouch outer material to overlap each other, and sealing three openings.

[0089] Referring to FIG. 5, a sealing method according to exemplary embodiments of the present invention may include a placement step (P10) and a primary sealing step (P20).

[0090] The above-described placement step (P10) is a step of placing the electrode assembly (10) on the pouch outer case (13). Specifically, in the above-described placement step (P10), the electrode assembly (10) can be placed on the pouch outer case so that the side of the electrode assembly corresponds between two bending lines (F1, F2) located at the center of the pouch outer case (13).

[0091] The above pouch outer material (13) may be formed of a laminate sheet including a metal layer and a resin layer. In some embodiments, the laminate sheet may be an aluminum laminate sheet.

[0092] In some embodiments, the pouch outer shell (13) may be formed of a core made of a metal layer, a heat-sealing layer formed on one surface of the core, and an insulating layer formed on the other surface of the core. The heat-sealing layer acts as an adhesive layer using a polymer resin, such as modified polypropylene, for example, cast polypropylene (CPP), and the insulating layer may be formed of a resin material such as nylon or polyethylene terephthalate (PET), but the structure and material of the pouch outer shell are not limited thereto.

[0093] The above pouch outer material (13) has a cup portion (133) that is recessed internally from the plane of the pouch outer material (13) in order to accommodate the electrode assembly (10). The pouch outer material (13) can be manufactured by forming the cup portion (133) by deep-drawing a flexible laminate sheet using a die and a punch. In addition, the pouch outer material (13) accommodates and seals the electrode assembly (10) so that a portion of the electrode lead (12), i.e., the terminal portion, is exposed.

[0094] Referring to FIGS. 6 and 7, two fold lines, namely a first fold line (F1) and a second fold line (F2), are positioned at the center of the pouch outer case (13). The first and second fold lines (F1, F2) extend along the first direction (X direction), which is the extension direction of the long side of the electrode assembly (10), and are parallel to each other. It is preferable that the mutual separation distance between the first and second fold lines (F1) and the second fold line (F2) correspond to the thickness (T) of the electrode assembly, which is the length of the side of the electrode assembly (10). If the mutual separation distance between the first and second fold lines (F1, F2) is too small compared to the thickness (T) of the electrode assembly, the accommodation space at the folded portion becomes narrower compared to the volume of the electrode assembly, which may result in damage to the pouch outer case or failure to seal, which is not preferable. If the distance between the first and second bend lines (F1, F2) is too large compared to the thickness (T) of the electrode assembly, unnecessary excess space is formed on the bend surface, which may cause a protrusion to be formed on the bend surface, which is not desirable.

[0095] Referring to FIGS. 7 to 10, the pouch outer shell (13) can be folded twice along two centrally positioned fold lines (F1, F2) to wrap the electrode assembly (10). A fold surface (FS) is formed by being folded twice along the two fold lines (F1, F2). The fold surface (FS) can have a flat surface along the side of the electrode assembly (10). Accordingly, in the first sealing step (P20) described below, at least one of the upper surface of the first sealing portion and the lower surface of the first sealing portion is easily bonded to the fold surface of the pouch outer shell formed by the fold at the portion where the first sealing portion and the fold portion intersect, and further, it is easy to seal the portion where the first sealing portion and the fold portion intersect in an "L" shape.

[0096] The above pouch outer material (13) can be divided into a first pouch outer material (131) located on one side of the two fold lines (F1, F2) based on the second direction (Y direction) perpendicular to the first direction (X direction) which is the extension direction of the two fold lines (F1, F2); and a second pouch outer material (132). When the pouch outer material (13) is folded twice along the two fold lines (F1, F2), the first pouch outer material (131) and the second pouch outer material (132) can face each other with the electrode assembly (10) interposed therebetween.

[0097] In some embodiments, the pouch outer case (13) may be provided with a cup portion (133) that is recessed internally from the plane of the pouch outer case (13) only on one side of the two fold lines (F1, F2) in a second direction (Y direction) perpendicular to the first direction (X direction) which is the extension direction of the two fold lines (F1, F2). The cup portion (133) becomes a receiving space in which the electrode assembly (10) is accommodated. The cup portion (133) may be a hat-shaped portion in which the recess depth (t) is constant along the second direction (Y direction). In the hat-shaped cup portion (133), the recess depth may be in the range of 1 / 3 to 2 / 3, specifically 1 / 2 to 2 / 3, of the thickness (T) of the electrode assembly. In the above pouch outer material (13), the other side of the two bending lines (F1, F2) with respect to the second direction (Y direction) may be a flat surface. That is, the first pouch outer material (131) occupying approximately half of the pouch outer material (13) has a cup portion (133), and the second pouch outer material (132) occupying the remaining half of the pouch outer material (13) is a flat surface without a cup portion. When a pouch outer material (130) having these characteristics is selected and sealed according to the present invention, bat ears can be effectively prevented.

[0098] In the above arrangement step (P10), the electrode assembly (10) is placed on the pouch outer case (13) so that the side surface of the electrode assembly (10), i.e., the thickness surface of the electrode assembly (10), is in contact with the plane between the two fold lines (F1, F2). Then, the pouch outer case (13) is folded so that the electrode assembly (10) does not fall out of the pouch outer case (13) and the electrode assembly (10) is accommodated in the receiving space of the cup portion (133).

[0099] In some embodiments, the pouch outer material (13) may be extended relatively long on the outside of the cup portion (133). The outside of the cup portion (133) becomes a gas pocket portion. When the length (GL) of the gas pocket portion is relatively long, the electrolyte can be easily injected, and problems such as the electrolyte overflowing due to a worker's mistake during the electrolyte injection process can be solved. Gas is generated during the activation process of the battery, and the gas generated during the activation process can be captured in the gas pocket portion.

[0100] The electrode assembly (10) may be a laminated structure having two electrodes, such as a positive electrode and a negative electrode, and a separator interposed between the electrodes or disposed on the left or right side of one of the electrodes to mutually insulate the electrodes. The laminated structure may be formed in various forms without limitation, such as a positive electrode and a negative electrode of a predetermined specification being laminated with a separator interposed therebetween, or being wound in the form of a jelly roll. The two electrodes each have a structure in which an active material slurry containing an electrode active material is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper. The active material slurry may typically be formed by stirring a granular active material, an auxiliary conductor, a binder, a plasticizer, etc. in a state in which a solvent is added. The solvent is removed in a subsequent process.

[0101] The electrode assembly (10), as illustrated in FIG. 6, includes an electrode tab (Electrode Tab, 11); and an electrode lead (12). The electrode tab (11) is connected to the positive and negative electrodes of the electrode assembly (10), respectively, and protrudes to the outside of the electrode assembly (10) to serve as a path through which electrons can move between the inside and the outside of the electrode assembly (10). The current collector of the electrode assembly (10) is composed of a portion where an electrode active material is applied and a terminal portion where the electrode active material is not applied, i.e., a non-coated portion. The electrode tab (11) may be formed by cutting the non-coated portion or by connecting a separate conductive member to the non-coated portion by ultrasonic welding, etc. As illustrated in FIG. 6, the electrode tabs (11) may protrude in different directions from the electrode assembly (10), but are not limited thereto, and may also protrude in parallel in the same direction from one side.

[0102] An electrode lead (12) may be connected to an electrode tab (11) of an electrode assembly (10) by a method such as spot welding. In addition, a portion of the electrode lead (12) may be surrounded by an insulating portion (14). The insulating portion (14) is positioned limited to a sealing portion (1341, 1342) where the first pouch outer material (131) and the second pouch outer material (132) of the pouch outer material (13) are heat-sealed, and is adhered to the first and second pouch outer materials (13). In addition, it prevents electricity generated from the electrode assembly (10) from flowing to the pouch outer material (13) through the electrode lead (12), and maintains the sealing of the pouch outer material (13). Therefore, the insulating portion (14) is made of a non-conductive material that does not conduct electricity well. In general, as the insulating part (14), an insulating tape that is easy to attach to the electrode lead (12) and has a relatively thin thickness is often used, but it is not limited thereto and various materials can be used as long as they can insulate the electrode lead (12).

[0103] The electrode lead (12) may extend in opposite directions or in the same direction depending on the formation positions of the positive tab (111) and the negative tab (112). The positive lead (121) and the negative lead (122) may have different materials. That is, the positive lead (121) may be made of the same aluminum (Al) material as the positive plate, and the negative lead (122) may be made of the same copper (Cu) material as the negative plate or a copper material coated with nickel (Ni). In addition, a portion of the electrode lead (12) protruding outside the battery case (13) becomes a terminal portion and is electrically connected to an external terminal.

[0104] When 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 stored inside the pouch outer material.

[0105] Referring to Fig. 11, when the pouch outer material (13) is bent to wrap the electrode assembly (10), three sides of the rectangular pouch outer material (13) except for the bent portion (FP) become open portions (OP1 to OP3). The inside and outside of the pouch outer material (13) are connected through the open portions (OP1 to OP3). For convenience of explanation, the left open portion with respect to the first direction (X direction) is referred to as the first open portion (OP1), the right open portion with respect to the first direction (X direction) is referred to as the second open portion (OP2), and the open portion opposite to the bent portion (FP) with respect to the second direction (Y direction) is referred to as the third open portion (OP3).

[0106] The above first sealing step (P20) may be a step of forming a first sealing portion by sealing the remaining openings (OP1, OP2) except for the third opening (OP3) facing the folded portion (FP) among the three openings (OP1 to OP3). In the above first sealing step (P20), the pouch outer material (13) may be folded to surround the electrode assembly (10), and the first opening (OP1) and the second opening (OP2) may be sealed by a sealing tool.

[0107] Referring to FIGS. 9 and 10, after the side surface of the electrode assembly (10) is placed between the first and second fold lines (F1, F2), the first sealing step (P20) is performed while the pouch outer material (13) is folded. In the first sealing step (P20), the pouch outer material (13) is folded along the first fold line (F1) and the second fold line (F2) to form a “ㄷ” shape. When the pouch outer material (13) is folded upward along the first fold line (F1) and the second fold line (F2), as illustrated in FIG. 10, the first pouch outer material (131) and the second pouch outer material (132) face each other, and the electrode assembly (10) is accommodated in the accommodation space provided therein, and the pouch outer material (13) wraps the electrode assembly (10).

[0108] After the pouch outer material (13) is folded twice in this way, a first sealing step (P20) is performed to seal the first and second openings (OP1, OP2). The sealing method is not particularly limited as long as it can seal the first and second pouch outer materials (131, 132) facing each other. As a non-limiting example, the first sealing step (P20) can be performed by heat-sealing the first pouch outer material (131) and the second pouch outer material (132) by using a sealing tool configured to apply heat and pressure to them while they are in a state of being overlapped with each other.

[0109] In exemplary embodiments, the first sealing step (P20) may be performed while the folded surface (FS) of the pouch outer case (13) is in close contact with the side surface of the electrode assembly (10). According to the present disclosure, since the folded surface (FS) has a flat surface, the folded surface (FS) of the pouch outer case (13) is easily in close contact with the side surface of the electrode assembly (10). In addition, when the first sealing step is performed while the folded surface (FS) of the pouch outer case (13) is in close contact with the side surface of the electrode assembly (10), an excess space between the folded surface (FS) of the pouch outer case (13) and the electrode assembly (10) is minimized, thereby preventing the pouch outer case (13) from protruding outward from the folded portion (FP) of the pouch outer case (13) in the second direction (Y direction) based on the folded portion.

[0110] Fig. 12 is a top view of a pouch-type battery cell after performing the first sealing step. Fig. 13 is an enlarged view of the cross-section AA' of portion C of Fig. 11 for explaining the first sealing step according to exemplary embodiments. Fig. 14 is an enlarged view of the cross-section BB' of portion C of Fig. 11 for explaining the first sealing step according to exemplary embodiments.

[0111] Referring to FIGS. 12 to 14, in the first sealing step (P20), at the point where the first sealing portion (1341, 1342) and the folded portion (FP) intersect, at least one of the upper surface of the first sealing portion (1341, 1342) and the lower surface of the first sealing portion (1341, 1342) is bonded to the folded surface (FS) of the pouch outer material formed by folding. In the past, since the sealing was performed in a "ㅡ" shape by bonding only the upper surface of the primary sealing portion and the lower surface of the primary sealing portion at the intersection of the primary sealing portion (1341, 1342) and the folded portion (FP), bat ears were formed. However, according to the present invention, since at least one of the upper surface of the primary sealing portion (1341, 1342) and the lower surface of the primary sealing portion (1341, 1342) is bonded to the folded surface (FS), bat ears are not formed. In addition, at the intersection of the primary sealing portion (1341, 1342) and the folded portion (FP), the primary sealing portion (1341, 1342) does not protrude outwardly of the waveguide-type battery cell with respect to the first direction (X direction) and the second direction (Y direction).

[0112] As described above, the sealing method according to the present invention can prevent the occurrence of a protruding phenomenon such as bat ears by a simple process of sealing so that the folded portion (FP) of the pouch outer material (13) forms a folded surface (FS), and at least one of the upper surface of the primary sealing portion (1341, 1342) and the lower surface of the primary sealing portion (1341, 1342) is adhered to the folded surface (FS) of the pouch outer material formed by the fold at the intersection of the primary sealing portion (1341, 1342) and the folded portion (FP). As a result, the size of the battery cell can be reduced, the height of the battery cell stack obtained by stacking the battery cells upright can be reduced, and the height of the battery module formed by storing the battery cell stack in a frame can also be reduced, thereby increasing the energy density of the battery module or battery pack. Additionally, as the space between the battery cell and the frame is reduced, the amount of heat-dissipating resin injected into that space can be reduced, which can also lead to cost savings.

[0113] Referring to FIGS. 11 to 14, the first sealing step (P20) for forming the first sealing portion (1341, 1342) may be performed by a sealing tool (50). The sealing tool (50) may include a first sealing block (51) for pressing the first pouch outer material (131) corresponding to the upper surface of the first sealing portion (1341, 1342); a second sealing block (52) for pressing the second pouch outer material (132) corresponding to the lower surface of the first sealing portion (1341, 1342); and a third sealing block (53) for pressing the folded surface (FS). The first sealing block (51) and the second sealing block (52) may be configured to be movable along the Z direction, and the third sealing block (53) may be configured to be movable along the Y direction.

[0114] In order to form the first sealing portion (1341, 1342), first, the first pouch outer material (131) and the second pouch outer material (132) are placed between the first sealing block (51) and the second sealing block (52) in a mutually overlapping state. Then, the folding surface (FS) is placed between the second sealing block (52) and the third sealing block (53). Next, with the first sealing block (51) positioned on the first pouch outer material (131) and the third sealing block (53) positioned on the folding surface (FS), the second sealing block (52), which is positioned below the second pouch outer material (132) based on the Z direction, is moved so as to come into contact with the first sealing block (51) and the third sealing block (53). And, when the first pouch outer material (131), the second pouch outer material (132) and the folded surface (FS) interposed therebetween are heat-pressed, the second pouch outer material (132) corresponding to the lower surface of the first sealing portion (1341, 1342) is bonded to the first pouch outer material (131) and the folded surface (FS). Accordingly, the corner sealing portion (1341c, 1342c), which is the portion where the first sealing portion (1341, 1342) and the folded portion (FP) intersect, can be sealed in an "L" shape as illustrated in FIG. 17.

[0115] Here, among the first pouch outer material (131) and the second pouch outer material (132), it is preferable that the second pouch outer material (132) not having a cup portion is adhered to the folded surface (FS). Since the first pouch outer material (131) having the cup portion (133) formed there is a step (t) from the bottom portion (133b) of the cup portion to the first sealing portion with respect to the Z direction, a protrusion may be formed when the first pouch outer material (131) is moved downward with respect to the Z direction in order to adhere the first pouch outer material (131) to the folded surface (FS). On the other hand, since the second pouch outer material (132) not having a cup portion is flat, even if the second pouch outer material (132) is moved upward with respect to the Z direction in order to adhere the first pouch outer material (132) to the first folded surface (FS), no protrusion is formed.

[0116] According to the present invention, the corner sealing portions (1341c, 1342c) are sealed in an "L" shape so that bat ears are not formed. In addition, at the portion where the primary sealing portions (1341, 1342) and the folded portion (FP) intersect, the primary sealing portions (1341, 1342) do not protrude outwardly of the pouch-shaped battery cell in the second direction (Y direction). When sealing in an "L" shape, if the sealing strength is adjusted, a pouch-shaped battery cell having a structure that facilitates gas venting through the corner sealing portions (1341c, 1342c) under abnormal conditions can be provided.

[0117] FIG. 16 is a flowchart illustrating a method for sealing a pouch-type battery cell according to exemplary embodiments. Referring to FIG. 17, the sealing method according to exemplary embodiments may further include, after the first sealing step (P20), an electrolyte injection step (P30); and a second sealing step (P40).

[0118] Referring to Fig. 11, the electrolyte injection step (P30) may be a step of injecting the electrolyte into the interior of the pouch outer case through the third opening (OP3) facing the folded portion (FP). In the first sealing step (P20), since the third opening (OP3) was not sealed, the third opening (OP3) is open so that the interior and exterior of the pouch outer case (13) are in communication. Therefore, the electrolyte can be injected into the interior of the pouch outer case (13) through the third opening (OP3).

[0119] Once the electrolyte injection is completed, a second sealing step (P40) is performed to seal the unsealed third opening (OP3). The second sealing step (P40) may utilize any sealing method generally known in the art. Through the second sealing step (P40), the first pouch outer material (131) and the second pouch outer material (132) facing each other can be heat-sealed to form a seal.

[0120] After performing the above-mentioned second sealing step (P40), an activation process may be performed. The activation process is a process of inducing an electrochemical reaction in the pouch-type battery cell to make it usable.

[0121] In exemplary embodiments, the activation process may include a pre-aging process; a formation process; an aging process; and a degassing process. The pre-aging process is a process of storing and aging the pouch-type battery cell in a space where constant temperature and humidity can be maintained to ensure sufficient impregnation of the electrolyte into the electrode assembly. The formation process is a process of initially charging the pouch-type battery cell until a predetermined depth of charge is reached to form an SEI film on the negative electrode. The formation process may include a process of pressurizing the pouch-type battery cell simultaneously with charging, immediately after charging, or before / after charging to prevent trapping of gases generated during the charging process and deformation of the electrode assembly. Since a pressurizing jig is typically used to pressurize the pouch-type battery cell, when the initial charging is performed using a pressurizing jig, this is also referred to as jig formation. The aging process is a process of storing and aging the battery cell in a space to stabilize the formed pouch-type battery cell. The above degassing process may be a process of discharging internal gas by cutting a portion of the gas pocket portion of the pouch-type battery cell to discharge the gas generated during the formation and aging processes to the outside of the battery cell. After the exhaust of the internal gas is complete, a resealing process may be performed to remove the gas pocket portion and reseal the removed portion. However, the above series of activation processes is not limited to the above-described content, and various technologies in the secondary battery field disclosed at the time of filing of the present application may be employed.

[0122]

[0123] (Example 2)

[0124] Figure 15 is an assembly diagram of a pouch-type battery cell according to other embodiments.

[0125] A sealing method according to exemplary embodiments of the present invention is a method of placing an electrode assembly on a single unit pouch outer material having two cup portions formed thereon, folding the pouch outer material to overlap each other, and sealing three openings.

[0126] Referring to FIG. 15, the pouch outer shell (13) has cup portions (1331, 1332) that are recessed internally from the plane of the pouch outer shell on one side and the other side of the two fold lines (F1, F2), respectively, based on the second direction (Y direction) perpendicular to the first direction, which is the extension direction of the two fold lines (F1, F2). One cup portion (1332) is an inclined cup portion whose recessed depth gradually increases as it gets farther away from the fold lines (F1, F2) based on the second direction (Y direction), and the other cup portion (1332) is a hat-shaped cup portion whose recessed depth is constant along the second direction.

[0127] When the pouch outer material (13) includes an inclined cup portion, the slope of the bottom surface is relatively gentle, so the stress applied to the pouch outer material (13) during the formation of the cup portion can be reduced.

[0128] The sealing method according to the second embodiment is different from the first embodiment in the shape of the pouch outer cover (13). Except for the shape of the pouch outer cover (13), the description of the sealing method according to the first embodiment can be applied to the second embodiment. For example, at a portion where the first sealing portion and the folded portion intersect, at least one of the upper surface of the first sealing portion and the lower surface of the first sealing portion can be adhered to the folded surface of the pouch outer cover formed by folding. In exemplary embodiments, the portion where the first sealing portion and the folded portion intersect is sealed in an "L" shape.

[0129] In order to prevent the formation of bat ears or protrusions when the pouch outer material (13) has two cup portions, it is preferable that at least one of the two cup portions be an inclined cup portion. Referring to Fig. 15, at the intersection of the first sealing portion (1341, 1342) and the folded portion, the second pouch outer material (132) having the inclined cup portion (1332) is flat, so that in the first sealing step, the second pouch outer material (132) can be adhered to the folded surface without the formation of bat ears or protrusions.

[0130] In the above-described regular cup portion (1332), the deepest indentation depth is a portion corresponding to a corner portion furthest from the bending line (F1, F2) in the second direction (Y direction), and the depth may be in the range of 1 / 3 to 2 / 3, specifically 1 / 2 to 2 / 3, of the electrode assembly thickness (T). In the above-described hat-shaped cup portion (1331), the indentation depth may be in the range of 1 / 3 to 2 / 3, specifically 1 / 2 to 2 / 3, of the electrode assembly thickness (T). When the two cup portions (1331, 1332) face each other and the primary sealing portions (1341, 1342) of the pouch outer material (13) are sealed, the electrode assembly (10) is accommodated in the cup portions (1331, 1332).

[0131] The above pouch outer material (13) includes a first pouch outer material (131) having the hat-shaped cup portion (1331) and a second pouch outer material (132) having the inclined cup portion (1332). In the first sealing step (P20), the second pouch outer material (132) having the inclined cup portion (1332) is adhered to the folded surface. In this case, the bat-ear prevention effect is more excellent compared to the case where the first pouch outer material (131) is adhered to the folded surface.

[0132] According to the present invention, bat ears or protrusions are not formed in the corner sealing portions (1341c, 1342c) where the primary sealing portions (1341, 1342) and the folded portion (FP) intersect. In addition, when the corner sealing portions (1341c, 1342c) are sealed in an L" shape, a pouch-type battery cell having a structure that facilitates venting of gas through the corner sealing portions (1341c, 1342c) in abnormal conditions by controlling the sealing strength can be provided.

[0133]

[0134] (Example 3)

[0135] Fig. 17 is a perspective view of a pouch-type battery cell according to exemplary embodiments of the present invention. Fig. 18 is a top view of Fig. 17.

[0136] Referring to FIGS. 6, 17 and 18, a pouch-type battery cell (1) has an electrode assembly (10) and an electrolyte (not shown) built into the interior of a pouch outer case (13). The pouch-type battery cell (1) has a sealing portion (134; 1341 to 1343) heat-sealed along an edge of the pouch outer case (13); and a fold surface (FS) formed by folding the pouch outer case (13) twice along two fold lines (F1, F2) so that the pouch outer case (13) wraps around one of the sides of the electrode assembly (10).

[0137] The above sealing portion includes a primary sealing portion (1341, 1342) that is parallel to a second direction (Y direction) perpendicular to a first direction (X direction) that is an extension direction of the bending line (F1, F2); and a secondary sealing portion (1343) that faces the bending line (F1, F2) based on the second direction. The primary sealing portions (1341, 1342) are portions sealed in the first sealing step (P20) described above, and may have a predetermined width length based on the first direction. The secondary sealing portion (1343) is a portion sealed in the second sealing step (P40) described above, and may have a predetermined width length based on the second direction (Y direction).

[0138] Referring to FIGS. 13 and 14, at the intersection of the primary sealing portions (1341, 1342) and the folded surface (FS), at least one of the upper surface (131) of the primary sealing portion and the lower surface (132) of the primary sealing portion is bonded to the folded surface (FS). In preferred embodiments, the intersection of the primary sealing portions (1341, 1342) and the folded surface (FS) is sealed in an "L" shape.

[0139] The pouch-shaped battery cell (1) according to exemplary embodiments of the present invention does not have bat ears since the corner sealing portion (1341c, 1342c), which is the portion where the primary sealing portion (1341, 1342) and the folded surface (FS) intersect, has the above-described characteristics.

[0140] In the pouch-shaped battery cell (1) according to exemplary embodiments of the present invention, the folded surface (FS) of the pouch outer case (13) does not have a protrusion that protrudes outward from the plane of the folded surface. That is, since the folded surface (FS) has a flat shape, it is advantageous for cooling. In addition, since unnecessary space such as the protrusion is eliminated, the electrode assembly area within the pouch outer case can be maximized, thereby having the effect of improving the energy density of the cell.

[0141] Since the above pouch outer material (13) and electrode assembly (10) have been described in detail above, redundant descriptions will be omitted.

[0142]

[0143] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

Claims

1. A placement step of placing the electrode assembly on the pouch outer material so that the side of the electrode assembly corresponds between two bending lines located at the center of the pouch outer material; and A first sealing step of forming a first sealing portion by sealing the remaining openings except for the opening facing the folded portion among the three openings while the pouch outer material is folded so that the pouch outer material surrounds the electrode assembly; including; In the above first sealing step, A sealing method for a pouch-shaped battery cell, characterized in that at least one of the upper surface of the first sealing portion and the lower surface of the first sealing portion is bonded to the folded surface of a pouch outer material formed by folding at a portion where the first sealing portion and the folded portion intersect.

2. A method for sealing a pouch-shaped battery cell in the first paragraph, wherein the folded surface is formed by folding twice along the two fold lines.

3. In paragraph 1, A method for sealing a pouch-shaped battery cell, wherein the above-mentioned folded surface has a flat surface along the side of the electrode assembly.

4. In paragraph 1, The above first sealing step is, A method for sealing a pouch-shaped battery cell, wherein the folded surface of the pouch outer material is in close contact with the side surface of the electrode assembly.

5. In paragraph 1, A method for sealing a pouch-shaped battery cell, wherein the sealing is performed in an “L” shape at the intersection of the first sealing portion and the bending portion.

6. In paragraph 1, The above pouch outer material is, A sealing method for a pouch-shaped battery cell having a cup portion recessed internally from the plane of a pouch outer material on only one side of the two bending lines, based on a second direction perpendicular to a first direction which is an extension direction of the two bending lines.

7. In paragraph 6, A sealing method for a pouch-shaped battery cell, wherein the other side of the two bending lines is a flat shape based on the second direction.

8. In paragraph 6, A method for sealing a pouch-type battery cell, wherein the cup portion is a hat-shaped cup portion having a constant indentation depth along the second direction.

9. In paragraph 6, The above pouch outer material includes a first pouch outer material having the cup portion and a second pouch outer material not having the cup portion, A method for sealing a pouch-shaped battery cell, wherein, in the first sealing step, the second pouch outer material is adhered to the folded surface.

10. In paragraph 1, The above pouch outer material is, With respect to the second direction perpendicular to the first direction, which is the extension direction of the two bending lines, a cup portion is provided on one side and the other side of the two bending lines, respectively, which is recessed internally from the plane of the pouch outer material, One cup portion is an inclined cup portion whose indentation depth increases as it gets farther from the bending line based on the second direction, The remaining one cup is a hat-shaped cup with a constant indentation depth along the second direction. Sealing method for pouch-type battery cells.

11. In paragraph 10, The above pouch outer material includes a first pouch outer material having the hat-shaped cup portion and a second pouch outer material having the inclined cup portion, A method for sealing a pouch-shaped battery cell, wherein, in the first sealing step, the second pouch outer material is adhered to the folded surface.

12. In paragraph 1, A method for sealing a pouch-shaped battery cell, characterized in that the distance between the two bending lines corresponds to the thickness of the electrode assembly, which is the length of the side of the electrode assembly.

13. In paragraph 1, An electrolyte injection step for injecting an electrolyte into the interior of the pouch outer material through a third opening opposite to the above-mentioned bending portion; and A method for sealing a pouch-shaped battery cell, further comprising a second sealing step of sealing the third opening.

14. A pouch-shaped battery cell having an electrode assembly and an electrolyte built into the interior of a pouch outer material, a sealing portion heat-sealed along an edge of the pouch outer material, and a folded surface formed by folding the pouch outer material twice along two fold lines so that the pouch outer material wraps one of the sides of the electrode assembly; The above sealing portion includes a primary sealing portion parallel to a second direction perpendicular to a first direction which is an extension direction of the bending line; and a secondary sealing portion facing the bending line based on the second direction. A pouch-shaped battery cell, wherein at least one of the upper surface of the first sealing portion and the lower surface of the first sealing portion is bonded to the folded surface at a portion where the first sealing portion and the folded surface intersect.

15. In paragraph 14, A pouch-shaped battery cell sealed in an “L” shape at the intersection of the above primary sealing portion and the above folding surface.

16. In paragraph 14, A pouch-shaped battery cell, characterized in that the folded surface of the above pouch outer material does not have a protrusion protruding outward from the plane of the folded surface.

Images