Patent Publication Number: US-2022223950-A1

Title: Battery cell and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims benefit of priority to Korean Patent Application No. 10-2021-0004182 filed on Jan. 12, 2021 in the Korean Intellectual Property Office. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a battery cell and a method of manufacturing the same. 
     2. Description of Related Art 
     Unlike primary batteries, secondary batteries such as a battery cell may charge and discharge electricity, to be applied to devices within various fields such as digital cameras, mobile phones, notebook computers, hybrid vehicles, and electric vehicles. Examples of the secondary batteries include a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, a lithium secondary battery, and the like. 
     Such secondary batteries may be generally formed by stacking a cathode, a separator, and an anode. Materials thereof may be selected in consideration of a lifespan, charge/discharge capacity, temperature characteristics, stability, or the like of a battery. 
     Such secondary batteries may be classified into a pouch-type secondary battery and a can-type secondary battery, according to a material of a case accommodating an electrode assembly. In the pouch-type secondary battery, an electrode assembly may be accommodated in a pouch made of a soft polymer material having a non-uniform shape. In the can-type secondary battery, an electrode assembly may be accommodated in a case made of a material such as a metal, a plastic, or the like, having a constant shape. 
     A conventional pouch-type battery cell may include an accommodation portion for accommodating an electrode assembly, and a sealed portion formed by bonding a pouch. Accordingly, when the accommodation portion is formed to have a thin thickness, the sealed portion may be disposed to protrude from the accommodation portion externally. As such, when the sealed portion is disposed to protrude from the accommodation portion, there may be a problem in that interference between the sealed portion and other elements may occur in a process of manufacturing a battery module. 
     Accordingly, there may be a demand for a battery cell capable of minimizing the above-described interference. 
     SUMMARY 
     An aspect of the present disclosure is to provide a battery cell in which a sealed portion does not protrude from an accommodation portion externally, and a method of manufacturing the same. 
     According to an aspect of the present disclosure, a battery cell includes an accommodation portion accommodating an electrode assembly; and a sealed portion extending from a side surface of the accommodation portion externally, and being folded a plurality of times and fixed to be included within a thickness range of the accommodation portion, wherein the sealed portion includes a folded portion disposed to oppose the side surface of the accommodation portion and having a width narrower than the thickness range of the accommodation portion; and a connection portion connecting a center of the folded portion and the accommodation portion, wherein the folded portion includes at least one bent portion formed by folding the sealed portion by 180°. 
     In this embodiment, the folded portion may include a first bent portion formed by folding the sealed portion by 180°; and a second bent portion spaced apart from the first bent portion and formed by folding the sealed portion by 180°, wherein a distance between the first bent portion and the second bent portion may define the width of the folded portion. 
     In this embodiment, the width of the folded portion may be formed to be smaller than the thickness range of the accommodation portion by 2 mm or more. 
     In this embodiment, the connection portion may include a third bent portion formed by folding the sealed portion by 90°. 
     In this embodiment, the folded portion may include a fourth bent portion formed in a position opposing the third bent portion, wherein the fourth bent portion may be formed by folding the folded portion such that the folded portion approaches the accommodation portion. 
     In this embodiment, the thickness range of the accommodation portion may be formed in a range of 6 mm to 8 mm. 
     In this embodiment, the width of the sealed portion may be formed to be larger than the thickness range of the accommodation portion, in a planar state that is unbent. 
     In this embodiment, the folded portion may include a first folded portion and a second folded portion, separated by the first bent portion, and a third folded portion separated from the second folded portion by the second bent portion, wherein the first folded portion may be disposed such that at least a portion thereof is in contact with the third folded portion. 
     According to another aspect of the present disclosure, a method of manufacturing a battery cell, includes forming a sealed portion by bonding an edge of a first case and an edge of a second case in contact with each other; forming a first bent portion by folding the sealed portion by 180°; forming a third bent portion by folding the sealed portion by 90°; and forming a second bent portion by folding a portion between the first bent portion and the third bent portion by 180°. 
     In this embodiment, the method may further include forming a groove for bending in a position in which the first bent portion and the second bent portion are formed, after forming the sealed portion. 
     In this embodiment, the method may further include pressing the sealed portion with a high-temperature pressurizing device, after forming the second bent portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view schematically illustrating a pouch-type battery cell according to an embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view of  FIG. 1 , taken along line I-I′. 
         FIGS. 3 to 8  are views illustrating a method of manufacturing the battery cell of  FIG. 2 . 
         FIGS. 9 to 13  are views illustrating a method of manufacturing a battery cell according to another embodiment of the present disclosure. 
         FIGS. 14 to 17  are views illustrating a method of manufacturing a battery cell according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Prior to the detailed description of the present disclosure, terms or words used in the specification and claims, described below, should not be construed as being limited to their ordinary or dictionary meanings, and the inventors should develop their own inventions in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present disclosure, based on the principle that it may be appropriately defined as a concept of a term for explanation. Therefore, it should be understood that since embodiments described in the specification and configurations illustrated in the drawings may be only the most preferred embodiments of the present disclosure, and do not represent all the technical ideas of the present disclosure, there may be various equivalents and variations to be replaced at the time of filing the present disclosure. 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same components in the accompanying drawings may be denoted by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present disclosure will be omitted. For the same reason, some components may be exaggerated, omitted, or schematically illustrated in the accompanying drawings, and a size of each of the components does not fully reflect an actual size thereof. 
     For example, in the present specification, expressions of “upper,” “upper side,” “upper portion,” “lower,” “lower side,” “lower portion,” “side,” “side surface,” and the like may be described with reference to the drawings, and are noted in advance that if a direction of an object is changed, it may be expressed differently. 
       FIG. 1  is a perspective view schematically illustrating a pouch-type battery cell according to an embodiment of the present disclosure, and  FIG. 2  is a cross-sectional view of  FIG. 1 , taken along line I-I′. 
     Referring to  FIGS. 1 and 2 , a battery cell  10  according to this embodiment may include an electrode assembly  12  and a case  11  accommodating the electrode assembly  12 . 
     The battery cell  10  according to this embodiment may be a rechargeable secondary battery, and may include a lithium ion (Li-ion) battery or a nickel metal hydride (Ni-MH) battery. The nickel metal hydride battery may be a secondary battery using nickel for a positive electrode, a hydrogen storage alloy for a negative electrode, and an aqueous alkali solution as an electrolyte. The nickel metal hydride battery may have relatively large capacity per unit volume, and may thus be used as an energy source for electric vehicles (EVs) and hybrid vehicles (HEVs), and used in various fields such as energy storage or the like. 
     The battery cell  10  may have a pouch-type structure. 
     The case  11  may be, for example, used by insulating a surface of a metal layer made of aluminum. The insulation may include applying modified polypropylene, which is a polymer resin, for example, cast polypropylene (CPP), and forming a resin material such as nylon or polyethylene terephthalate (PET) on an outer surface thereof. 
     The case  11  may include an accommodation portion  204  for providing an accommodation space  13  therein. The electrode assembly  12  may be accommodated in the accommodation space  13  in the case  11 . In addition, electrode leads  15  may protrude from the case  11 . 
     The electrode assembly  12 , together with an electrolyte, may be accommodated in the accommodation portion of the case  11 . The case  11  may be formed by contacting a first case  11   b  and a second case  11   a , and then bonding an edge of the first case  11   b  and an edge of the second case  11   a  to seal the accommodation space  13 . As such, the accommodation portion  204  may be completed. A thermal fusion method may be used as a method of bonding the edges, but may not be limited thereto. Hereinafter, a portion in which the edges are bonded may be referred to as a sealed portion  202 . 
     The sealed portion  202  may be formed to form a flange extending from the accommodation portion  204  externally, and thus the sealed portion  202  may be disposed along an outer edge of the accommodation portion  204 . 
     In this embodiment, the sealed portion  202  may be divided into a first sealed portion  2021  in which the electrode lead  15  is disposed, and a second sealed portion  2022  in which the electrode lead  15  is not disposed. Therefore, the second sealed portion  2022  of this embodiment may comprehensively refer to a sealed portion in which the electrode lead  15  is not disposed, among sealed portions provided in various types of battery cells not illustrated in the present disclosure. 
     In this embodiment, the case  11  may be formed by forming a single sheet of exterior material. More specifically, after forming one or two accommodation spaces  13  in one exterior material, the battery cell  10  may be completed by folding the exterior material such that the accommodation spaces  13  form one space. 
     Therefore, in the battery cell  10  of this embodiment, it is not necessary to form the sealed portion  202  on a side surface (a lower surface in  FIG. 1 ) on which the exterior material is folded. Therefore, in this embodiment, the sealed portion  202  may only be provided on three side surfaces among four side surfaces forming the outer edge of the accommodation portion  204 , and the sealed portion may not be disposed on any one side surface of the outer edge of the accommodation portion  204  (the lower surface in  FIG. 1 ). 
     In this embodiment, since the electrode leads  15  may be disposed to oppose each other in opposite directions, the two electrode leads  15  may be respectively disposed on the sealed portions  202  formed on different side surfaces. Therefore, the sealed portion  202  may include two first sealed portions  2021  in which the electrode lead  15  is disposed, and one second sealed portion  2022  in which the electrode lead  15  is not disposed. 
     Since the sealed portion  202  should tightly seal the accommodation space  13 , when an area of the sealed portion  202  is excessively small, it may be difficult to secure bonding reliability. Therefore, the sealed portion  202  needs to be formed to have a predetermined width or more. 
     The present applicant confirmed by an experiment that minimum bonding reliability is ensured only when a width W 1  of the sealed portion  202  is formed to be 6.5 mm or more, in a planar state in which the sealed portion  202  is unbent, as illustrated in  FIG. 3 . Therefore, in this embodiment, the width W 1  of the sealed portion  202  may be formed to be 6.5 mm or more. For example, the width W 1  of the sealed portion  202  may be formed to be larger than a thickness range T of the accommodation portion  204 . When a thickness of the battery cell  10  is 6.5 mm or less, the sealed portion  202  may be formed to have a width of 6.5 mm or more. 
     An entire region of the sealed portion  202  may be formed as a bonding region, but is not limited thereto. Only a portion of the sealed portion  202  may be formed as the bonding region. In this case, a remaining region other than the bonding region may be disposed outside the accommodation portion  204  in an overlapping form, without the exterior materials being bonded to each other. 
     To minimize a volume occupied by the sealed portion  202  in a battery module, the sealed portion  202  may be formed to have a shape, folded at least once. More specifically, in the battery cell  10  according to this embodiment, the second sealed portion  2022  in which the electrode lead  15  is not disposed, among the sealed portions  202 , may be configured to be folded a plurality of times. 
     The second sealed portion  2022  may be folded to reduce an area of the battery cell  10 . In addition, when a plurality of battery cells  10  are stacked in the battery module, the second sealed portion  2022  may be disposed within the thickness range T of the battery cell  10 , to suppress contact or interference with other battery cells  10 , disposed adjacent to each other. 
     To this end, the second sealed portion  2022  of this embodiment may be folded in an overlapping form by bending at least once by 180°, to minimize the width W 1  of the second sealed portion  2022 . 
     In addition, the second sealed portion  2022  may be bent and folded at least once by 90° or more. Therefore, the second sealed portion  2022  may be disposed in close contact with the accommodation portion  204 . 
     To this end, the second sealed portion  2022  of this embodiment may include a folded portion  2022   a  disposed side by side in a thickness direction of the accommodation portion  204  and having a width, smaller than the thickness range T of the accommodation portion  204 , and a connection portion  2022   b  connecting the folded portion  2022   a  and the accommodation portion  204 . 
     The folded portion  2022   a  may be formed to have a width, smaller than the thickness range T of the accommodation portion  204 , through a first bent portion C 1  and a second bent portion C 2 , to be described later, may be disposed to face a side surface of the accommodation portion  204 , and may be disposed side by side in the thickness direction of the accommodation portion  204 . 
     The first bent portion C 1  and the second bent portion C 2  may be respectively arranged on width direction both sides of the folded portion  2022   a . Therefore, a width W 2  of the folded portion  2022   a  may be defined as a distance between the first bent portion C 1  and the second bent portion C 2 , to be described later, or a width of a second folded portion F 2  to be described later. 
     The connection portion  2022   b  may connect the folded portion  2022   a  and the accommodation portion  204 , and may include a third bent portion C 3  to be described later. The connection portion  2022   b  may connect a center of the folded portion  2022   a  to the accommodation portion  204 . More specifically, the connection portion  2022   b  may be bent by 90° by the third bent portion C 3  at a width direction center of the folded portion  2022   a , to be connected to the accommodation portion  204 . 
     In a process of manufacturing the battery cell  10 , the width W 2  of the folded portion  2022   a  may have a deviation due to a tolerance in manufacturing the same. Therefore, in the battery cell  10  according to this embodiment, as illustrated in  FIG. 2 , the width W 2  of the folded portion  2022   a  may be smaller than the thickness range T of the accommodation portion  204 . 
     More specifically, the folded portion  2022   a  may be disposed to be spaced apart from two planes P 1  and P 2  defining the thickness range T of the battery cell  10  by a predetermined distance. 
     In this case, the above-described separation distance, spaced apart, may be defined based on a thickness of the folded portion  2022   a . In this embodiment, a thickness of the second sealed portion  2022  may be 0.3 mm to 0.4 mm. When the second sealed portion  2022  is folded by 180° to form the folded portion  2022   a , the thickness of the folded portion  2022   a  may be formed to be about 0.6 mm to 0.8 mm. Therefore, in consideration of lifting of a portion to be bonded, a maximum thickness of the folded portion  2022   a  may be considered to be approximately 1 mm. 
     Therefore, in the battery cell  10  of this embodiment, both sides of the folded portion  2022   a  may be spaced apart from the two planes P 1  and P 2  by 1 mm or more, and thus the width W 2  of the folded portion  2022   a  may be defined as a smaller range by 2 mm or more, compared to the thickness range T of the accommodation portion  204 . 
     The second sealed portion  2022  of this embodiment may include the first, second, and third bent portions C 1 , C 2 , and C 3 . In addition, the folded portion  2022   a  may include a first folded portion F 1  and a second folded portion F 2 , divided by the first bent portion C 1 , and a third folded portion F 3  that may be distinguished from the second folded portion F 2  by the second bent portion C 2 . 
     The first bent portion C 1  may be a portion in which the second sealed portion  2022  is folded along a first bending line L 1 , and the second sealed portion  2022  may be bent by 180° in the first bent portion C 1 . Therefore, the first bent portion C 1  may be folded in such a manner that the first folded portion F 1  overlaps the second folded portion F 2 , based on the first bending line L 1 . 
     The second bent portion C 2  may be a portion in which the second sealed portion  2022  is folded along a second bending line L 2 , and the second sealed portion  2022  may be bent and folded by 180°, like the first bent portion C 1 . Therefore, the second bent portion C 2  may be folded in such a manner that the third folded portion F 3  overlaps the second folded portion F 2 , based on the second bending line L 2 . 
     The third bent portion C 3  may be a portion in which the second sealed portion  2022  is folded along a third bending line L 3 , and the second sealed portion  2022  may be bent and folded by 90°. 
     Therefore, the second sealed portion  2022  of this embodiment may be folded by 180° along the first bending line L 1  and the second bending line L 2 , respectively, and may be folded by 90° along the third bending line L 3 . Therefore, an overall angle at which the second sealed portion  2022  is bent may be 450° by adding up the first bent portion C 1  (180°), the second bent portion C 2  (180°), and the third bent portion C 3  (90°). 
     Referring to  FIG. 2  in which the sealed portion  202  has been formed, the first bent portion C 1  and the second bent portion C 2  in the folded portion  2022   a  may be arranged in opposite directions to each other. In addition, the third bent portion C 3  may be located between the first bent portion C 1  and the second bent portion C 2 . 
     In addition, the second sealed portion  2022  of this embodiment may be disposed to be bisected by a plane P 3  (hereinafter, referred to as a first reference plane) in which the first case  11   b  and the second case  11   a  are in contact. Therefore, as illustrated in  FIG. 2 , a portion of the second sealed portion  2022  may be disposed on one side of the first reference plane P 3  (e.g., in an upper portion), and a remaining portion thereof may be on the other side of the first reference plane P 3  (e.g., in a lower portion). 
     When the first, second, and third folded portions F 1 , F 2 , and F 3  are not arranged to be in close contact, a volume of the battery cell in a plane direction may increase. Therefore, the battery cell  10  of this embodiment may fold the sealed portion at 180° to bring the first, second, and third folded portions F 1 , F 2 , and F 3  into close contact as much as possible, to minimize a thickness of the folded portion  2022   a.    
     In conventional battery cells having a thick thickness, a folded portion may be disposed on only one side of a first reference plane P 3 , among both sides thereof, because a thickness T of each of the battery cells is sufficiently thick, compared to a width of the folded portion. Therefore, the folded portion may be disposed within a range T/2 corresponding to half of a thickness range T of each of the battery cells. This configuration may have a problem in that it is difficult to apply to a thin battery cell having a thickness T of the battery cell of 8 mm or less. 
     According to this embodiment, since the width W 2  of the folded portion  2022   a  should be formed in a range smaller than the thickness range T of the battery cell  10  by 2 mm or more, in a thin battery cell  10  in which the thickness T of the battery cell  10  is 8 mm, the width W 2  of the folded portion  2022   a  should be defined to be 6 mm or less. 
     Therefore, when a width (W 1  of  FIG. 3 ) of the second sealed portion  2022  is formed to be 6.5 mm or more, and the folded portion is disposed only on either of both sides of the first reference plane P 3  as in the prior art, a width of the folded portion may be entirely formed to be 3 mm or more, not to be included in the thickness range T of the accommodation portion  204 . 
     This problem may be further exacerbated when the thickness T of the battery cell  10  is 6 mm. Therefore, the battery cell  10  of this embodiment may be configured such that the connection portion  2022   b  is connected to the accommodation portion  204  at the center of the folded portion  2022   a.    
     Next, a method for manufacturing a battery cell according to this embodiment will be described. 
       FIGS. 3 to 8  are views illustrating a method of manufacturing the battery cell of  FIG. 2 , and illustrate a method of manufacturing a battery cell  10  having a thickness of 8 mm. 
     First, referring to  FIG. 3 , in a method of manufacturing a battery cell according to this embodiment, a sealed portion  202  may be formed by bonding edges in which a first case  11   b  and a second case  11   a  are in contact by a method such as thermal fusion or the like. In this process, the sealed portion  202  may be formed in a planar shape, and may be disposed on a first reference plane P 3 , as described above. 
     As described above, in this embodiment, a second sealed portion  2022  may be formed to have a width W 1  of 6.5 mm or more in an unbent state thereof. 
     Subsequently, bending grooves G 1 , G 2 , and G 4  may be formed to form first to third bent portions C 1 , C 2 , and C 3 . 
     Based on the second sealed portion  2022 , as illustrated in  FIG. 4 , a third bending line L 3  may be disposed closest to an accommodation portion  204 , and a first bending line L 1  may be disposed farthest from the accommodation portion  204 . Therefore, a second bending line L 2  may be disposed between the third bending line L 3  and the first bending line L 1 . 
     In a method of manufacturing a battery cell according to this embodiment, as illustrated in  FIG. 4 , the second sealed portion  2022  may be processed to form the bending grooves G 1 , G 2 , and G 4  in positions in which the second sealed portion  2022  are bent. Pressing may be used for processing the bending grooves G 1 , G 2 , and G 4 , but is not limited thereto. The bending grooves G 1 , G 2 , and G 4  may be provided to facilitate bending of the second sealed portion  2022 . Therefore, as long as the second sealed portion  2022  is easily bent, the bending grooves G 1 , G 2 , and G 4  are not limited in shape or structure. 
     In this embodiment, although formation of first and second bending grooves G 1  and G 2  corresponding to the first and second bending lines L 1  and L 2  are illustrated, a third bending groove may be also additionally formed in a position corresponding to the third bending line L 3 , as necessary. 
     As illustrated in  FIG. 4 , the second sealed portion  2022  may be to be divided into first, second, and third folded portions F 1 , F 2 , and F 3  by the first and second bending grooves G 1  and G 2 . 
     Subsequently, as illustrated in  FIG. 5 , first, the first folded portion F 1  may be bent by 180°, based on the first bending line L 1 , to form the first bent portion C 1 . In this case, the first bent portion C 1  may be formed by bending the second sealed portion  2022  along the first bending groove G 1  such that portions of a first surface of the second sealed portion  2022  are in contact. 
     The first folded portion F 1 , overlapping the second folded portion F 2  by the first bent portion C 1 , may be spaced apart from the second and third bending lines L 2  and L 3  by a predetermined distance. Therefore, the first folded portion F 1  may not affect a process of forming the second and third bent portions C 2  and C 3 , thereafter. 
     Next, as illustrated in  FIG. 6 , the second sealed portion  2022  may be bent by 90°, based on the third bending line L 3 , to form the third bent portion C 3 . The third bent portion C 3  may be formed by bending the second sealed portion  2022  in a direction in which a second surface of the second sealed portion  2022  approaches the accommodation portion  204 . 
     Therefore, the second sealed portion  2022  may be disposed on a second reference surface P 4 , orthogonal to the first reference surface P 3 . In this case, the second reference plane P 4  may mean a plane disposed in a thickness direction of the battery cell  10 . 
     Then, as illustrated in  FIG. 7 , the second sealed portion  2022  may be bent by 180°, based on the second bending line L 2 , to form the second bent portion C 2  and a folded portion  2022   a . As the second bent portion C 2  is formed, the folded portion  2022   a  may be disposed to oppose a side surface of the accommodation portion  204  in a form bisected by the first reference plane P 3 . 
     A method of manufacturing a battery cell according to this embodiment may further include pressing the folded portion  2022   a  externally to bring the folded portion  2022   a  into close contact with the accommodation portion  204 , as illustrated in  FIG. 8 . 
     When the bending the sealed portion is completed in the state illustrated in  FIG. 7 , phenomenon in which the folded portion does not maintain a right angle with the first reference plane and is widened with an obtuse angle may occur, due to a change with time in resin layer constituting the battery case. 
     To prevent this phenomenon, the manufacturing method of this embodiment may additionally perform an operation of adhering the folded portion  2022   a  to the accommodation portion  204 . 
     In this operation, a high-temperature pressurizing device  90  may press the folded portion  2022   a  toward the accommodation portion  204  and may supply heat to the folded portion  2022   a . Due to this, a width of the folded portion  2022   a  may be reduced, and a shape of the folded portion  2022   a  may be maintained in a state in close contact with the accommodation portion  204  as much as possible. 
     In this operation, the folded portion  2022   a  may be further bent along a fourth bending line L 4 . In this operation, the fourth bending line L 4  may be disposed along the first reference plane P 3 . Therefore, the folded portion  2022   a  may be bent along the fourth bending line L 4  such that both side portions thereof is disposed close to the accommodation portion  204 . 
     To this end, as illustrated in  FIG. 4 , in forming the bending grooves G 1 , G 2 , and G 4 , a fourth bending groove G 4  may be formed together. 
     Even though a battery cell  10  having a thin thickness is manufactured in a battery cell and a method of manufacturing the same according to this embodiment, configured as described above, since a sealed portion  202  may be disposed within a thickness range T of the battery cell  10 , interference between the battery cells  10  may be prevented when a battery module is manufactured. 
       FIGS. 9 to 13  are views illustrating a method of manufacturing a battery cell according to another embodiment of the present disclosure, and illustrate a method of manufacturing a battery cell having a thickness of 6 mm. 
     This embodiment may be configured similarly to the above-described embodiment, but has a difference in view that it further includes a fifth bending groove G 5 . Therefore, a detailed description of a configuration similar to the above-described embodiment will be omitted. 
     The fifth bending groove G 5  may be formed in a position farthest from an accommodation portion  204 . In addition, a separation distance between a first bending groove G 1  and the fifth bending groove G 5  may be formed to be the same as a separation distance between the first bending groove G 1  and a fourth bending groove G 4 . 
     Therefore, when a second sealed portion  2022  is bent in a process of forming a first bent portion C 1 , as illustrated in  FIG. 10 , the fifth bending groove G 5  may be disposed to overlap the fourth bending groove G 4 . Therefore, in the process of  FIG. 13  of bending a folded portion  2022   a  along a fourth bending line L 4  by a high-temperature pressurizing device  90 , a first folded portion F 1  may be bent, together with a second folded portion F 2 . 
     To this end, the fifth bending groove G 5  may be formed to be concave in a direction, opposite to the fourth bending groove G 4 . 
     Also, as illustrated in  FIG. 12 , when a second bent portion C 2  is formed, at least a portion of the first folded portion F 1  may be disposed to contact the third folded portion F 3 . Therefore, in this embodiment, the folded portion  2022   a  may be formed in a state in which three layers overlap along a first reference plane P 3 . A configuration of the present disclosure is not limited thereto. 
       FIGS. 14 to 17  are views illustrating a method of manufacturing a battery cell according to another embodiment of the present disclosure. 
     This embodiment may be configured similarly to the embodiment of  FIG. 2  described above, but has a difference in view that a first bent portion C 1  is not included. Therefore, a detailed description of a configuration similar to the above-described embodiment will be omitted. 
     A folded portion  2022   a  of this embodiment may include only a second bent portion C 2 . Therefore, as illustrated in  FIG. 16 , the folded portion  2022   a  of this embodiment may consist of only a second folded portion F 2  and a third folded portion F 3 , and a width W 2  of the folded portion  2022   a  may be defined as a width of the second folded portion F 2 . 
     Similar to the above-described embodiments, a connection portion  2022   b  may be disposed at a center of the folded portion  2022   a , to be connected to an accommodation portion  204 . 
     According to an embodiment of the present disclosure, even when a battery cell having a thin thickness is manufactured, since a sealed portion is disposed within a thickness range of a battery cell, interference between battery cells may be prevented when a battery module is manufactured. 
     While example embodiments have been illustrated and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present disclosure as defined by the appended claims.