Battery cell and manufacturing method therefor

Abstract

A battery cell according to an embodiment of the present invention may comprise: a first exterior material including a first metal layer and a resin layer attached to the inner surface of the first metal layer; a second exterior material including a second metal layer; an electrode assembly accommodated between the first exterior material and the second exterior material; an adhesive part by which the resin layer and the second metal layer are adhered to each other; a folded part folded such that the edge part of the second exterior material encompasses the edge part of the first exterior material; and a welding part in which the first metal layer and the second metal layer are welded in the folded part.

Description

Battery cell and method for manufacturing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0053477, filed April 22, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a battery cell in which an electrode assembly is accommodated between a first outer casing and a second outer casing, and a method for manufacturing the same.

[0005] Recently, secondary batteries have been attracting attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are being proposed as a solution to air pollution caused by existing gasoline and diesel vehicles that use fossil fuels.

[0006] While small mobile devices use one or two or three secondary batteries, medium and large devices such as electric vehicles use battery modules that electrically connect multiple secondary batteries or battery packs that electrically connect multiple battery modules to each other due to the need for high output and large capacity.

[0007] Among the currently commercialized secondary batteries, lithium secondary batteries are arguably the most sought-after. Lithium secondary batteries can be categorized into can-type, square-type, and pouch-type batteries based on the shape of their packaging. Among these, pouch-type batteries are widely used in medium- to large-sized battery modules due to their high energy density and ease of stacking.

[0008] Meanwhile, with the recent increase in demand for secondary battery modules installed in vehicles, customer demands for safety are steadily increasing. However, customers are demanding higher energy density within the limited space of secondary battery modules. This, in turn, increases safety risks related to battery cell fire and explosion.

[0009] Typically, pouch-type battery cells have a structure in which the electrode assembly is housed in a pouch-type battery case, with a seal formed at the edge of the case. If the battery cell exceeds a critical temperature due to abnormal overheating or other reasons, the temperature and internal pressure may rapidly increase, potentially leading to an explosion. This can result in a thermal runaway, in which flames rapidly spread to other surrounding battery cells.

[0010] To prevent or sufficiently delay this thermal runaway, it is necessary to implement a sealing section with high heat resistance and sealing strength.

[0011] The problem to be solved by the present invention is to provide a battery cell having a sealing portion with high heat resistance and sealing strength, and a method for manufacturing the same.

[0012] A battery cell according to an embodiment of the present invention may include a first outer material including a first metal layer and a resin layer attached to an inner surface of the first metal layer; a second outer material including a second metal layer; an electrode assembly accommodated between the first outer material and the second outer material; an adhesive portion in which the resin layer and the second metal layer are adhered to each other; a fold portion formed by folding an edge portion of the second outer material to surround an edge portion of the first outer material; and a weld portion in which the first metal layer and the second metal layer are welded in the fold portion.

[0013] The outer surface of the first metal layer can define the outer surface of the first outer material, and the inner surface of the second metal layer can define the inner surface of the second outer material.

[0014] The above welding portion may overlap the above bonding portion in the thickness direction of the first exterior material.

[0015] The resin layer may include a base resin layer; a first adhesive resin layer positioned on one side of the base resin layer and bonded to the first metal layer; and a second adhesive resin layer positioned on the other side of the base resin layer and bonded to the second metal layer at the bonding portion. The adhesion of the first adhesive resin layer and the second adhesive resin layer to metal may be higher than the adhesion of the base resin layer to metal.

[0016] The above base resin layer may have a lower strain than the first adhesive resin layer and the second adhesive resin layer.

[0017] In the above folding portion, the second metal layer can cover the ends of the resin layer and the first metal layer.

[0018] The above-mentioned folding portion may include a first folding portion folded to cover an end of the first outer material; and a second folding portion connected to the first folding portion and folded to contact the first metal layer. The welding portion may be formed in the second folding portion.

[0019] Each of the first metal layer and the second metal layer may include at least one material selected from the group consisting of stainless steel, copper, and titanium.

[0020] The above battery cell may further include an insulating layer covering the outer surfaces of the first metal layer and the second metal layer.

[0021] The above battery cell may further include a venting induction portion in which the first metal layer and the second metal layer are not welded or are welded weakly than the weld portion in the folded portion.

[0022] A method for manufacturing a battery cell according to an embodiment of the present invention may include the steps of: preparing a first outer material including a first metal layer and a resin layer attached to an inner surface of the first metal layer, and a second outer material including a second metal layer; accommodating an electrode assembly between the first outer material and the second outer material; bonding the resin layer and the second metal layer to each other; forming a folded portion such that an edge portion of the second outer material surrounds an edge portion of the first outer material; and welding the first metal layer and the second metal layer at the folded portion.

[0023] The above battery cell manufacturing method may further include, after the welding step, a step of attaching or coating an insulating layer on the outer surface of the first metal layer and the second metal layer.

[0024] In the above welding step, the first metal layer and the second metal layer may be unwelded or lightly welded in a part of the folded portion.

[0025] According to a preferred embodiment of the present invention, the metal layers of the first and second outer layers are welded together to seal the battery cell, thereby maintaining the seal of the battery cell even at high temperatures and pressures and achieving high sealing strength. This delays explosion in the event of abnormal battery cell operation, and prevents or sufficiently delays thermal runaway, which can spread flames to other surrounding battery cells.

[0026] In addition, since the metal layers of the first outer material and the second outer material are in direct contact at the folded portion, the sealing quality and sealing strength of the weld can be improved without a separate process of removing the resin layer from the outer material.

[0027] In addition, the configurations according to preferred embodiments of the present invention may include effects that can be easily predicted by those skilled in the art.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0029] Figure 1 is an assembly diagram of a battery cell according to one embodiment of the present invention.

[0030] Figure 2 is a cross-sectional view showing the interior of a battery cell according to one embodiment of the present invention.

[0031] Figure 3 is a plan view of a battery cell according to one embodiment of the present invention.

[0032] Fig. 4 is a modified example of the battery cell illustrated in Fig. 2.

[0033] Figure 5 is a flowchart of a battery cell manufacturing method according to another embodiment of the present invention.

[0034] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0035] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0036] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0037] In the drawing, each component of a secondary battery according to one embodiment of the present invention is schematically illustrated, and the size of the component or the thickness of the line may be expressed somewhat exaggerated for the convenience of understanding.

[0038] FIG. 1 is an assembly diagram of a battery cell according to one embodiment of the present invention, and FIG. 2 is a cross-sectional diagram showing the interior of a battery cell according to one embodiment of the present invention.

[0039] A battery cell (10) according to one embodiment of the present invention may include a first outer material (110), a second outer material (120), and an electrode assembly (200).

[0040] The electrode assembly (200) may include an anode, a cathode, and a separator interposed between the anode and the cathode to insulate them. The type of the electrode assembly (10) is not limited. For example, the electrode assembly (200) may be a stacked electrode assembly in which the anode and the cathode are alternately stacked with the separator interposed therebetween. As another example, the electrode assembly (200) may be a jelly roll type electrode assembly in which sheet-shaped anodes and cathodes are rolled together with the separator interposed therebetween.

[0041] The first outer material (110) and the second outer material (120) can be sealed to contain the electrode assembly (200) together with the electrolyte, thereby forming a battery case.

[0042] The first exterior material (110) and the second exterior material (120) can be manufactured as separate members.

[0043] The first outer material (110) may include a first metal layer (111) and a resin layer (112) attached to the inner surface of the first metal layer (111). The first outer material (110) may be manufactured by forming a laminate sheet including the first metal layer (111) and the resin layer (112).

[0044] The second outer material (120) may include a second metal layer (121). The second outer material (120) may be manufactured by molding a sheet made of the second metal layer (121). However, the second outer material (120) may further include a resin layer (not shown) attached to the outer surface of the second metal layer (121).

[0045] The resin layer (112) can form the innermost layer of the first outer material (110). That is, the resin layer (112) can define the inner surface of the first outer material (110). The resin layer (112) of the first outer material (110) and the second metal layer (121) of the second outer material (120) can be bonded to each other to form an adhesive portion (140) to be described later.

[0046] In more detail, the resin layer (112) may include a base resin layer (112a), a first adhesive resin layer (112b), and a second adhesive resin layer (112c). The first adhesive resin layer (112b) may be positioned on one side of the base resin layer (112a), and the second adhesive resin layer (112c) may be positioned on the other side of the base resin layer (112a). In more detail, the first adhesive resin layer (112b) and the second adhesive resin layer (112c) may be attached to both sides of the base resin layer (112a).

[0047] The base resin layer (112a) may have a lower strain than the first adhesive resin layer (112b) and the second adhesive resin layer (112c). Therefore, when heat and pressure are applied to the resin layer (112) to form the adhesive portion (140) described later, the base resin layer (112a) may not be excessively compressed and may maintain an appropriate thickness.

[0048] The first adhesive resin layer (112b) can be bonded to the first metal layer (111). By the first adhesive resin layer (112b), the first metal layer (111) and the resin layer (112) of the first exterior material (110) can be maintained in bond.

[0049] The second adhesive resin layer (112c) can be bonded to the second metal layer (121). By the second adhesive resin layer (112c), the resin layer (112) of the first outer material (110) and the second metal layer (121) of the second outer material (120) can be bonded to each other in the bonding portion (140) described later.

[0050] Therefore, the adhesion of the first adhesive resin layer (112b) and the second adhesive resin layer (112c) to metal may be higher than the adhesion of the base resin layer (112a) to metal.

[0051] For example, the base resin layer (112a) may include a PP (Polypropylene) material, preferably cross-linked PP, Random PP, or Homo PP. In addition, the first adhesive resin layer (112b) and the second adhesive resin layer (112c) may include a PP-g-MA (polypropylene-grafted-maleic anhydride) material. However, the present invention is not limited thereto, and a person skilled in the art will be able to appropriately select from among well-known materials that satisfy the characteristics required for the base resin layer (112a), the first adhesive resin layer (112b), and the second adhesive resin layer (112c) described above.

[0052] The first metal layer (111) can form the outermost layer of the first outer material (110). That is, the first metal layer (111) can define the outer surface of the first outer material (110).

[0053] The second metal layer (121) can form the innermost layer of the second outer material (120). That is, the second metal layer (121) can define the inner surface of the second outer material (120).

[0054] In addition, the first metal layer (111) of the first outer material (110) and the second metal layer (121) of the second outer material (120) can be welded to each other to form a welded portion (160) to be described later. This will be described in detail later.

[0055] Each of the first metal layer (111) and the second metal layer (121) may include at least one material selected from the group consisting of stainless steel (STS), copper, and titanium. Since the melting points of stainless steel, copper, and titanium are higher than 1000°C, the first outer material (110) and the second outer material (120) may have high heat resistance compared to the melting point of aluminum (Al) used in conventional battery cells, which is approximately 660°C.

[0056] Since the second metal layer (121) defines the inner surface of the second outer material (120), it can directly contact the electrolyte contained together with the electrode assembly (200) in the cup portion (C).

[0057] In this regard, in a conventional pouch-type battery case including an aluminum layer, when the innermost polymer layer (e.g., polypropylene (PP)) is destroyed, the aluminum layer is exposed to the electrolyte. Accordingly, the aluminum layer has a negative potential, and corrosion and moisture penetration of the aluminum layer due to the aluminum-lithium alloys (Al-Li alloys) reaction are accelerated, which causes a problem of deterioration in battery performance. On the other hand, since the second metal layer (121) of the present embodiment includes at least one material among stainless steel, copper, and titanium, the above reaction does not occur even when exposed to the electrolyte, so there is no problem.

[0058] The first outer material (110) and the second outer material (120) can provide a storage space capable of accommodating the electrode assembly (200). The first outer material (110) and the second outer material (120) can have an overall pouch shape, but are not limited thereto.

[0059] In more detail, at least one of the first outer material (110) and the second outer material (120) may be formed with a cup portion (C) that accommodates the electrode assembly (200). The cup portion (C) may be formed by a depression and may define a storage space in which the electrode assembly (200) is accommodated.

[0060] Hereinafter, as illustrated in FIGS. 1 and 2, a case in which a cup portion (C) is formed in the first outer material (110) and the second outer material (120) covers the cup portion (C) of the first outer material (110) will be described as an example. However, the present invention is not limited thereto. A cup portion (C) may be formed in the second outer material (120) and the first outer material (110) may cover the cup portion (C) of the second outer material (120). Alternatively, a cup portion (C) may be formed in each of the first outer material (110) and the second outer material (120), and the two cup portions (C) may be connected to each other to define a storage space in which the electrode assembly (200) is stored.

[0061] The first exterior material (110) and the second exterior material (120) may include an edge portion (110A) (120A). The edge portion (110A) (120A) may be referred to as a terrace portion.

[0062] The edge portion (110A) of the first outer material (110) may refer to an area located around the cup portion (C). The edge portion (120A) of the second outer material (120) may refer to an area facing the edge portion (110A) of the first outer material (110) and an area located further outside thereof.

[0063] The edge portion (110A) of the first outer material (110) and the edge portion (120A) of the second outer material (120) can be sealed to each other, and thus the electrode assembly (200) can be accommodated between the first outer material (110) and the second outer material (120).

[0064] Meanwhile, the battery cell (10) may include a folded portion (150) formed by folding the edge portion (120A) of the second outer material (120) to surround the edge portion (110A) of the first outer material (110).

[0065] In more detail, the edge portion (120A) of the second outer material (120) may be hemmed along the end of the edge portion (110A) of the first outer material (110). To this end, the edge portion (120A) of the second outer material (120) may be formed wider than the edge portion (110A) of the first outer material (110). In more detail, the edge portion (120A) of the second outer material (120) may be formed longer in the length and width directions than the edge portion (110A) of the first outer material (110).

[0066] The fold (150) can be formed along the perimeter of the battery cell (10).

[0067] The first line (L1) and the second line (L2) illustrated in Fig. 1 are exemplary lines showing the lines along which the edge portion (120A) of the second outer material (120) is folded.

[0068] The first line (L1) may be parallel to the length direction of the battery cell (10), and the second line (L2) may be parallel to the width direction of the battery cell (10). The first line (L1) and the second line (L2) may correspond to the end of the edge portion (110A) of the first outer material (110).

[0069] The first line (L1) and the second line (L2) can be folded sequentially or in reverse order. The corner portion where the first line (L1) and the second line (L2) overlap at the edge portion (120A) of the second outer material (120) can be double folded. However, this is not limited to this, and a person skilled in the art will be able to cut the corner portion into an appropriate shape.

[0070] In the folding portion (150), the second metal layer (121) can cover the ends of the resin layer (112) and the first metal layer (111).

[0071] In more detail, the folding portion (150) may include a first folding portion (151) folded to cover the end of the first outer material (110), and a second folding portion (152) folded to be connected to the first folding portion (151) and to be in contact with the first metal layer (111).

[0072] The first folding portion (151) may be formed by folding an outer portion of the edge portion (120A) of the second outer material (120). The end of the first outer material (110) may face the inner surface of the first folding portion (151).

[0073] The end of the first outer material (110) may be in contact with or adjacent to the inner surface of the first folded portion (151). However, this is not limited thereto, and a predetermined gap may be formed between the end of the first outer material (110) and the inner surface of the first folded portion (151).

[0074] The second folded portion (152) can be formed by folding an outer portion of the first folded portion (151). The inner surface of the second folded portion (152) can be in contact with the outer surface of the edge portion (110A) of the first outer material (110). Therefore, the second metal layer (121) forming the inner surface of the second folded portion (152) can be in contact with the first metal layer (111) forming the outer surface of the first outer material (110). Here, the first metal layer (111) and the second metal layer (121) in contact with each other can be welded to form a welded portion (160) to be described later. That is, the welded portion (160) can be formed in the second folded portion (152).

[0075] Meanwhile, the battery cell (10) may include an adhesive portion (140) and a welding portion (160).

[0076] The adhesive portion (140) may be formed by bonding the resin layer (112) of the first outer material (110) and the second metal layer (121) of the second outer material (120) to each other. In more detail, the resin layer (112) of the edge portion (110A) of the first outer material (110) may be bonded to the second metal layer (121) of the edge portion (120A) of the second outer material (120) to form the adhesive portion (140). Even more specifically, the second adhesive resin layer (112c) of the edge portion (110A) of the first outer material (110) may be bonded to the second metal layer (121) of the edge portion (120A) of the second outer material (120) to form the adhesive portion (140). The adhesive portion (140) may be formed by heat fusion, but is not limited thereto.

[0077] The adhesive portion (140) may be positioned inside the folding portion (150). The adhesive portion (140) may be formed long along the edge portion (110A) of the first outer material (110) and the edge portion (120A) of the second outer material (120).

[0078] The welded portion (160) can be formed by welding the first metal layer (111) and the second metal layer (121) at the folded portion (150). More specifically, the first metal layer (111) and the second metal layer (121), which are in contact with each other at the second folded portion (152), can be welded to each other to form the welded portion (160). The welded portion (160) can be formed by laser welding, but is not limited thereto.

[0079] Since the welding portion (160) is welded between the metal layers (111) and (121), it can have a higher sealing strength than the bonding portion (140). As a result, the sealing strength of the battery cell (10) can be significantly increased.

[0080] The weld (160) may be formed along the fold (150). The weld (160) may be formed along the perimeter of the battery cell (10).

[0081] The welded portion (160) may overlap with the bonded portion (140) in the thickness direction of the first outer material (110). The welded portion (160) may face the bonded portion (140) with the edge portion (110A) of the first outer material (110) interposed therebetween. More specifically, the bonded portion (140) may be formed on the inner surface of the edge portion (110A) of the first outer material (110), and the welded portion (160) may be formed on the outer surface.

[0082] As previously described, the first metal layer (111) can define the outer surface of the first outer material (110), and the second metal layer (121) can define the inner surface of the second outer material (120). Accordingly, the first metal layer (111) and the second metal layer (121) can be in direct contact at the folded portion (150), and the sealing quality and strength of the weld portion (160) can be formed high.

[0083] In this regard, it is well known that a conventional laminate sheet includes two polymer layers (e.g., polypropylene (PP) and polyethylene terephthalate (PET)) forming an outer surface and an inner surface, and a metal layer (e.g., aluminum (AL)) positioned between the two polymer layers. If it is assumed that a conventional laminate sheet is molded to manufacture the first and second outer layers, the polymer layers are positioned between the first metal layer of the first outer layer and the second metal layer of the second outer layer at the folded portion where the edge of the second outer layer is folded to wrap the edge of the first outer layer. Therefore, when the first metal layer and the second metal layer are welded to each other at the folded portion, the weldability is poor due to the polymer layers. In order to solve this problem, it is possible to consider performing a removal process for removing the polymer layers from the edge portions of the first and second outer layers, and then performing a welding process for welding the first metal layer and the second metal layer to each other, but there is a problem that the battery cell manufacturing process becomes complicated. On the other hand, the battery cell (1) of the present embodiment has the advantage of not requiring such a removal process.

[0084] Figure 3 is a plan view of a battery cell according to one embodiment of the present invention.

[0085] The battery cell (10) may further include a venting induction portion (170) in which the first metal layer (111) and the second metal layer (121) are not welded or are welded weaker than the weld portion (160) in the fold portion (150).

[0086] The venting guide (170) may be located at the folded portion (150). More specifically, along the circumferential direction of the battery cell (10), the welding portion (160) may be located at a part of the folded portion (150), and the venting guide (170) may be located at another part of the folded portion (150).

[0087] At least one venting induction member (170) may be provided along the perimeter of the battery cell (10). The battery cell (10) has the advantage of being easy to design appropriately the degree to which gas is discharged within the battery cell (10) by adjusting the length, number, position, etc. of the venting induction members (170).

[0088] Since the sealing strength of the adhesive portion (140) is lower than that of the weld portion (160), the adhesive portion (140) may be destroyed if the internal pressure of the battery cell (10) rises above a certain level. At this time, the gas within the battery cell (10) may be discharged to the outside of the battery cell (10) through the venting induction portion (170).

[0089] When the first metal layer (111) and the second metal layer (121) are not welded to each other in the folding portion (150) to form a venting induction portion (170), the gas inside the battery cell (10) can be discharged to the outside of the battery cell (10) through the space between the first metal layer (111) and the second metal layer (121) of the venting induction portion (170).

[0090] In the case where the first metal layer (111) and the second metal layer (121) are weakly welded to each other in the folding portion (150) to form a venting induction portion (170), if the internal pressure of the battery cell (10) increases, the weak welding may be destroyed, and the gas inside the battery cell (10) may be discharged to the outside of the battery cell (10) through the space between the first metal layer (111) and the second metal layer (121) of the venting induction portion (170).

[0091] Directional venting, in which gas is discharged in a preset direction, can be implemented by the venting induction unit (170). This prevents the battery cell (10) from exploding and thermal runaway, in which flames spread to other surrounding battery cells due to the explosion, can be prevented.

[0092] Fig. 4 is a modified example of the battery cell illustrated in Fig. 2.

[0093] The battery cell (10) may further include an insulating layer (130) covering the outer surfaces of the first metal layer (111) and the second metal layer (121).

[0094] The insulating layer (130) may be provided after the welding portion (160) is formed. The insulating layer (130) may be attached or coated on the outer surfaces of the first metal layer (111) and the second metal layer (121). By the insulating layer (130), the battery cell (10) may maintain insulation from other battery cells or components in the vicinity.

[0095] Figure 5 is a flowchart of a battery cell manufacturing method according to another embodiment of the present invention.

[0096] Hereinafter, the manufacturing method of the battery cell (10) described above will be described as another embodiment of the present invention.

[0097] A battery cell manufacturing method according to another embodiment of the present invention comprises a step (S10) (hereinafter, preparation step) of preparing a first outer material (110) including a first metal layer (111) and a resin layer (112), and a second outer material (120) including a second metal layer (121), a step (S20) (hereinafter, accommodation step) of accommodating an electrode assembly (200) between the first outer material (110) and the second outer material (120), a step (S30) (hereinafter, adhesion step) of bonding the resin layer (112) and the second metal layer (121) to each other, a step (S40) (hereinafter, folding step) of forming a folded portion (150) so that an edge portion (120A) of the second outer material (120) surrounds an edge portion (110A) of the first outer material (110), and a step (S40) (hereinafter, folding step) of forming a folded portion (150) in which the electrode assembly (200) is accommodated between the first outer material (110) and the second outer material (120). It may include a step (S50) of welding the first metal layer (111) and the second metal layer (121) (hereinafter, welding step).

[0098] In the preparation step (S10), a cup portion (C) may be sunken-molded into at least one of the first outer material (110) and the second outer material (120). In addition, the edge portion (120A) of the second outer material (120) may be formed wider than the edge portion (110A) of the first outer material (110).

[0099] In the acceptance step (S20), when the electrode assembly (200) is accommodated in the cup portion (C), the edge portion (110A) of the first outer material (110) and the edge portion (120A) of the second outer material (120) can be in contact with each other. As a result, the electrode assembly (200) can be accommodated between the first outer material (110) and the second outer material (120). At this time, the edge portion (120A) of the second outer material (120) can protrude outward from the edge portion (110A) of the first outer material (110).

[0100] In the bonding step (S30), the resin layer (112) of the edge portion (110A) of the first outer material (110) can be bonded to the second metal layer (121) of the edge portion (120A) of the second outer material (120). To this end, the edge portion (110A) of the first outer material (110) and the edge portion (120A) of the second outer material (120) can be heat-sealed while in contact with each other.

[0101] In the folding step (S40), the edge portion (120A) of the second outer material (120) can be folded to wrap around the end of the edge portion (110A) of the first outer material (110), and a folding portion (150) can be formed. The first metal layer (111) and the second metal layer (121) can come into contact at the folding portion (150).

[0102] In the welding step (S50), the first metal layer (111) and the second metal layer (121) can be welded at the folded portion (150), and a welded portion (160) can be formed. The welded portion (160) can be formed along the circumferential direction of the battery cell (10).

[0103] In the welding step (S50), the first metal layer (111) and the second metal layer (121) may be unwelded or lightly welded in a portion of the folded portion (150), and a venting induction portion (170) may be formed. The light welding means having a sealing strength weaker than the sealing strength of the welded portion (160). More specifically, along the circumferential direction of the battery cell (10), a welded portion (160) may be formed in a portion of the folded portion (150), and a venting induction portion (170) may be formed in another portion.

[0104] Meanwhile, although not shown in FIG. 5, the battery cell manufacturing method may further include a step of attaching or coating an insulating layer (130) on the outer surfaces of the first metal layer (111) and the second metal layer (121). This step may be performed after the welding step (S50). As a result, the sealing quality of the welded portion (160) can be prevented from being lowered by the insulating layer (130), and the battery cell (10) can be reliably insulated from the surroundings.

[0105] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0106] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0107] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0108] [Explanation of symbols]

[0109] 10: Battery cell 110: First outer material

[0110] 111: First metal layer 112: Resin layer

[0111] 112a: Base resin layer 112b: First adhesive resin layer

[0112] 112c: Second adhesive resin layer 120: Second exterior material

[0113] 121: Second metal layer 130: Insulating layer

[0114] 140: Adhesive part 150: Folding part

[0115] 151: First fold 152: Second fold

[0116] 160: Welding section 170: Venting guide section

[0117] 200: Electrode assembly

Claims

1. A first outer material including a first metal layer and a resin layer attached to the inner surface of the first metal layer; A second outer covering material including a second metal layer; An electrode assembly accommodated between the first outer material and the second outer material; An adhesive portion in which the resin layer and the second metal layer are adhered to each other; A folded portion formed by folding the edge portion of the second outer material to wrap around the edge portion of the first outer material; and A battery cell including a welded portion in which the first metal layer and the second metal layer are welded in the above-described folded portion.

2. In paragraph 1, The outer surface of the first metal layer can define the outer surface of the first outer material, A battery cell in which the inner surface of the second metal layer defines the inner surface of the second outer material.

3. In paragraph 1, The above welding part is a battery cell that overlaps the adhesive part in the thickness direction of the first outer material.

4. In paragraph 1, The above resin layer is, Base resin layer; A first adhesive resin layer located on one side of the base resin layer and bonded to the first metal layer; and A second adhesive resin layer is located on the other side of the base resin layer and is bonded to the second metal layer at the bonding portion, A battery cell in which the adhesion of the first adhesive resin layer and the second adhesive resin layer to metal is higher than the adhesion of the base resin layer to metal.

5. In paragraph 4, A battery cell wherein the base resin layer has a lower strain than the first adhesive resin layer and the second adhesive resin layer.

6. In paragraph 1, In the above folding portion, the second metal layer is a battery cell that covers the ends of the resin layer and the first metal layer.

7. In paragraph 1, The above folding part is, A first folded portion folded to cover the end of the first outer material; and A second folded portion is connected to the first folded portion and is folded to contact the first metal layer, The above welding part is a battery cell formed in the second folding part.

8. In paragraph 1, A battery cell wherein each of the first metal layer and the second metal layer comprises at least one material selected from the group consisting of stainless steel, copper, and titanium.

9. In paragraph 1, A battery cell further comprising an insulating layer covering the outer surfaces of the first metal layer and the second metal layer.

10. In paragraph 1, A battery cell further comprising a venting induction portion in which the first metal layer and the second metal layer are not welded or are welded weakly than the weld portion in the above-described folding portion.

11. A step of preparing a first outer material including a first metal layer and a resin layer attached to the inner surface of the first metal layer, and a second outer material including a second metal layer; A step of accommodating an electrode assembly between the first outer material and the second outer material; A step of bonding the resin layer and the second metal layer to each other; A step of forming a folded portion so that the edge portion of the second outer material wraps around the edge portion of the first outer material; and A battery cell manufacturing method comprising a step of welding the first metal layer and the second metal layer at the above-mentioned folding portion.

12. In paragraph 11, A battery cell manufacturing method further comprising, after the welding step, a step of attaching or coating an insulating layer on the outer surface of the first metal layer and the second metal layer.

13. In paragraph 11, A battery cell manufacturing method in which, during the above welding step, the first metal layer and the second metal layer are not welded or lightly welded in a part of the folded portion.

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