Secondary battery and method for manufacturing same

Abstract

The present invention relates to a secondary battery and a method for manufacturing same. The secondary battery according to an aspect of the present invention may comprise: a cap including a first surface, a second surface perpendicular or inclined to the first surface, and an edge connecting the first surface and the second surface; an electrode assembly of which one side is covered by the cap; and an exterior film including a sheet-shaped accommodation unit surrounding the electrode assembly in a circumferential direction, a first and a second extension unit extending from one periphery and the other periphery of the accommodation unit, respectively, and a coupling unit for coupling the first and second extension units. The coupling unit may be positioned to correspond to the edge.

Description

Secondary battery 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. 10-2024-0107846, filed August 12, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a secondary battery and a method for manufacturing the same, and more particularly, to a secondary battery capable of charging and discharging electric energy and a method for manufacturing the same.

[0005] Common types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These batteries are used not only in small products such as digital cameras, DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in larger products requiring high output, such as electric and hybrid vehicles, as well as in power storage devices that store surplus power or renewable energy, and as backup power storage devices.

[0006] At this time, the secondary battery includes an electrode assembly comprising a stacked positive electrode, negative electrode, and separator, a case housing the electrode assembly, and electrode leads for conducting current between the electrode assembly and the outside. These secondary batteries are sometimes referred to as cylindrical, square, or pouch-shaped, depending on the structure or shape of the case. The case requires certain functions for the operation of the secondary battery.

[0007] Recently, development has been underway for secondary battery cases, which include a pair of caps covering each side of the electrode assembly and an outer film surrounding the electrode assembly. These cases require sealing to prevent leakage of internal materials (e.g., electrolyte) and ensure safety.

[0008] The present invention has been devised to solve the above problems, and the object of the present invention is to provide a secondary battery with improved sealing properties and a method for manufacturing the same.

[0009] The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0010] According to one aspect of the present invention, a secondary battery is provided, comprising: a cap including a first surface, a second surface that is perpendicular or inclined to the first surface, and an edge connecting the first surface and the second surface; an electrode assembly covered on one side by the cap; and an outer film including a sheet-shaped receiving portion that circumferentially surrounds the electrode assembly, first and second extension portions extending from one edge and the other edge of the receiving portion, respectively, and a joining portion that joins the first and second extension portions, wherein the joining portion is positioned to correspond to the edge.

[0011] At this time, the above-mentioned joint can be in contact with the above-mentioned corner.

[0012] At this time, the corners can be formed to be rounded.

[0013] At this time, the connecting portion may be located in a section between a first point and a second point based on the cross-section of the corner, the first point may be a point where the corner and the first surface meet, and the second point may be a point where the corner and the second surface meet.

[0014] At this time, the section is a section from the third point to the fourth point, and when the length measured from the first point to the second point along the cross-section of the corner is referred to as the corner length, the third point may be spaced apart from the first point along the cross-section of the corner by 1 / 3 of the corner length, and the fourth point may be spaced apart from the first point along the cross-section of the corner by 2 / 3 of the corner length.

[0015] At this time, the cross-section of the corner may have a circular or elliptical arc shape.

[0016] At this time, the section is a section from the third point to the fourth point, and the third point may be spaced apart from the first point by 30 degrees based on the center of the circular or elliptical arc, and the fourth point may be spaced apart from the first point by 60 degrees based on the center of the circular or elliptical arc.

[0017] At this time, the electrode assembly may extend in a first direction, the cap may cover one side of the electrode assembly in the first direction, and the corner and the joint may extend along the first direction.

[0018] At this time, the caps may be configured as a pair and placed on each side of the electrode assembly, and the connecting portion may be configured as a pair to correspond to the caps.

[0019] At this time, the first extension portion may be parallel to the second extension portion.

[0020] At this time, the first surface may be perpendicular to the second surface.

[0021] At this time, the connecting portion can be formed by joining the first extension portion and the second extension portion to each other.

[0022] According to another aspect of the present invention, a method for manufacturing a secondary battery is provided, comprising: arranging a cap on one side of an electrode assembly, the cap including a first surface, a second surface perpendicular or inclined to the first surface, and an edge connecting the first surface and the second surface; surrounding the electrode assembly with a receiving portion of an outer film having a sheet shape; positioning first and second extension portions extending from one edge and the other edge of the receiving portion, respectively, to correspond to the edge; and forming a joining portion for joining the first extension portion and the second extension portion at a position corresponding to the edge.

[0023] At this time, a step of combining the first and second surfaces and the receiving portion may be further included.

[0024] At this time, the step of forming the above-mentioned joining portion may be performed before the step of joining the first and second surfaces and the receiving portion.

[0025] At this time, a step of forming an additional joining portion to join areas not joined by the joining portion in the first and second extension portions may be further included.

[0026] At this time, the additional coupling portion may extend along the edge of the receiving portion, and the coupling portion may be positioned at one end of the additional coupling portion.

[0027] At this time, in the step of forming the joint, heat or pressure may be applied to at least one of the first extension portion and the second extension portion.

[0028] According to one aspect of the present invention, since the connecting portion that connects the first and second extension portions extending from the receiving portion is positioned corresponding to the corners of the cap, the bonding force between the outer film and the cap can be enhanced. As a result, the sealing properties of the secondary battery can be improved.

[0029] The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the attached drawings.

[0030] FIG. 1 is a perspective view of a secondary battery according to one embodiment of the present invention viewed from above.

[0031] Figure 2 is a cross-sectional view according to II of Figure 1.

[0032] Figure 3 is a cross-sectional view according to II-II of Figure 1.

[0033] Figure 4 is an enlarged view of part A of Figure 3.

[0034] Figure 5 is a flowchart of a secondary battery manufacturing method according to one embodiment of the present invention.

[0035] FIG. 6 is a drawing for explaining a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0036] Preferred embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0037] 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.

[0038] 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.

[0039] Fig. 1 is a perspective view of a secondary battery according to one embodiment of the present invention, viewed from above. Fig. 2 is a cross-sectional view taken along line II of Fig. 1. Fig. 3 is a cross-sectional view taken along line II-II of Fig. 1. Fig. 4 is an enlarged view of part A of Fig. 3.

[0040] FIGS. 1 to 4 disclose a secondary battery according to one embodiment of the present invention. Referring to FIGS. 1 to 4, a secondary battery (1) according to one embodiment of the present invention may be formed by sealing an electrode assembly (10) for charging and discharging electric energy by a cap (20) and an outer film (40).

[0041] At this time, in the secondary battery (1) according to the present embodiment, the joining portion (46) that joins the first and second extension portions (44a, 44b) of the outer film (40) is located at the corner (28) of the cap (20), so that it can have high airtightness, insulation, and durability. Hereinafter, each component of the secondary battery (1) according to one embodiment of the present invention will be described in detail.

[0042] Referring to FIGS. 1 and 2, a secondary battery (1) according to one embodiment of the present invention may include an electrode assembly (10). The electrode assembly (10) may extend in a predetermined direction. Hereinafter, the direction is referred to as the longitudinal direction (X-axis direction) of the electrode assembly (10).

[0043] The electrode assembly (10) may be configured to perform a charge / discharge function. To this end, the electrode assembly (10) may have a structure in which a positive electrode, a separator, and a negative electrode are sequentially stacked. The electrode assembly (10) may be classified into a cylindrical shape, a stacked shape, or a stack-and-folding shape depending on its shape, but in the present embodiment, the type of the electrode assembly (10) is not particularly limited.

[0044] In this embodiment, the electrode assembly (10) may be provided with an electrode tab (11). The electrode tab (11) may be configured to conduct current from the electrode (positive electrode or negative electrode) of the electrode assembly (10) to the outside. The electrode tab (11) may extend from the electrode toward the outside of the electrode assembly (10). The electrode tab (11) may be coupled to a terminal (30) described below.

[0045] A secondary battery (1) according to one embodiment of the present invention may include a cap (20). The cap (20) may be configured to seal and isolate the electrode assembly (10) from the outside. For bonding with an external film (40) described later, a predetermined resin layer may be provided on the outer surface of the cap (20).

[0046] At this time, in the present embodiment, the caps (20) may be configured as a pair and may be placed on each of the two sides in the longitudinal direction (X-axis direction) of the electrode assembly (10). Each of the two sides of the electrode assembly (10) may be covered by a pair of caps (20).

[0047] In this embodiment, the cap (20) may include a plate portion covering one side of the electrode assembly (10) and a side wall portion extending from the edge of the plate portion toward the electrode assembly (10). When viewed in the longitudinal direction (X-axis direction) of the electrode assembly (10), the side wall portion may have a square ring shape.

[0048] At this time, in the present embodiment, the cap (20) may include an outer surface (22). The outer surface (22) may be a surface facing the outside of the electrode assembly (10) among the two surfaces of the plate portion. The outer surface (22) may extend in a direction (Y-axis and Z-axis directions) perpendicular to the longitudinal direction (X-axis direction) of the electrode assembly (10).

[0049] Referring to FIGS. 2 to 4, in the present embodiment, the cap (20) may include a first surface (24), a second surface (26), a third surface, and a fourth surface. The first to fourth surfaces may be a portion of the outer surface of the side wall portion of the cap (20). The first to fourth surfaces may constitute the outer peripheral surface of the side wall portion.

[0050] More specifically, in the present embodiment, the first surface (24) may be a surface extending left and right (Y-axis direction) from the upper side (positive direction of the Z-axis) of the cap (20), the second surface (26) may be a surface extending up and down (Z-axis direction) from the right side (positive direction of the Y-axis) of the cap (20), the third surface may be a surface facing the first surface (24) from the lower side (negative direction of the Z-axis) of the cap (20), and the fourth surface may be a surface facing the second surface (26) from the left side (negative direction of the Y-axis) of the cap (20).

[0051] As illustrated, in this embodiment, the first side (24) and the second side (26) may be perpendicular to each other, and the first side (24) and the third side may be parallel to each other. However, the second side (26) and the third side may also be arranged to be inclined at a predetermined angle with respect to the first side (24).

[0052] Meanwhile, in the present embodiment, the cap (20) may include a corner (28). The corner (28) may be a portion connecting the first side (24) and the second side (26). One edge of the first side (24) and one edge of the second side (26) may extend parallel to each other in the longitudinal direction (X-axis direction) of the electrode assembly (10), and the corner (28) connecting these edges may also extend in the above direction (X-axis direction).

[0053] At this time, the edge (28) may be composed of a plurality of edges. One of the plurality of edges (28) may connect the first side (24) and the second side (24) as described above, another may connect the first side (24) and the fourth side, another may connect the second side (26) and the third side, and another may connect the third side and the fourth side.

[0054] In other words, based on Fig. 3, the plurality of corners (28) are configured in four numbers and can be provided respectively on the upper left, lower left, upper right, and lower right sides of the cap (20). Hereinafter, the corners (28) are described as being parts connecting the first side (24) and the second side (26).

[0055] At this time, referring to FIGS. 3 and 4, the corner (28) may be formed to be round. The cross-section of the corner (28) may have an arc shape with the center (C) located on the inside of the cap (20). The cross-section may be a cross-section perpendicular to the longitudinal direction (X-axis direction) of the electrode assembly (10). If necessary, the cross-section of the corner (28) may have a different shape. For example, the cross-section of the corner (28) may be formed as a convex curve such as an elliptical arc shape.

[0056] Meanwhile, in the present embodiment, the cap (20) has been described as including a plate portion and a side wall portion. However, the specific shape or structure of the cap (20) is not particularly limited as long as it can cover one side of the electrode assembly (10).

[0057] And, in this embodiment, since the side wall portion of the cap (20) has a square ring shape, the outer surface of the side wall portion is described as being composed of first to fourth surfaces and four corners connecting them. However, the number of surfaces or corners may be appropriately changed depending on the shape of the cap (20).

[0058] Referring again to FIGS. 1 and 2, a secondary battery (1) according to one embodiment of the present invention may include a terminal (30). The terminal (30) may be configured to mediate an electrical connection between the electrode assembly (10) and the outside. For this purpose, the terminal (30) may be made of a conductive material.

[0059] In this embodiment, the terminal (30) may include a body portion (32). The body portion (32) may penetrate the cap (20). The body portion (32) may pass through the outer surface (22) of the cap (20). The body portion (32) may have a cylindrical shape, but is not limited thereto.

[0060] In this embodiment, the terminal (30) may include an outer catch (34). The outer catch (34) may be provided on one side of the body (32). The one side may be a portion facing the outside of the electrode assembly (10).

[0061] At this time, the outer catch portion (34) may have a larger cross-sectional area than the body portion (32). As a result, the outer catch portion (34) may be caught on the outer surface (22) of the cap (20). Accordingly, the terminal (30) may be restricted from moving beyond a certain distance toward the electrode assembly (10).

[0062] In the present embodiment, the terminal (30) may include an inner hook portion (36). The inner hook portion (36) may be provided on the other side of the body portion (32). The other side may be a portion facing the electrode assembly (10). An electrode tab (11) may be coupled to the inner hook portion (36). For example, the electrode tab (11) may be welded to the outer surface of the inner hook portion (36), but is not limited thereto.

[0063] At this time, the inner catch portion (36) may have a larger cross-sectional area than the body portion (32). As a result, the inner catch portion (36) may be caught on the inner surface of the cap (20). At this time, the inner surface may be a surface facing the outer surface (22). Therefore, the terminal (30) may be restricted from moving outward of the electrode assembly (10) beyond a certain distance.

[0064] Referring to FIGS. 1 to 4, a secondary battery (1) according to one embodiment of the present invention may include an outer film (40). The outer film (40) may be configured to cover the remaining portion of the outer surface of the electrode assembly (10) that is not covered by the cap (20). Through this, the electrode assembly (10) may be sealed and isolated from the outside.

[0065] In this embodiment, the outer film (40) may include a receiving portion (42). The receiving portion (42) may have a sheet shape. The receiving portion (42) may surround the electrode assembly (10) in a circumferential direction. As a result, the electrode assembly (10) may be placed in a space separated from the outside.

[0066] At this time, the edge portion of the receiving portion (42) placed in the longitudinal direction (X-axis direction) of the electrode assembly (10) may be arranged so as to overlap at least a portion with the first to fourth surfaces of the cap (20). The edge portion may surround the cap (20) in the circumferential direction. The edge portion may be combined with the first to fourth surfaces, respectively.

[0067] For example, the edge portion of the receiving portion (42) may be pressed against the first to fourth surfaces by heat or pressure, respectively. At this time, the resin layer provided on the outer film (40) or the cap (20) may be melted, thereby bonding them to each other. Of course, the edge portion and the first to fourth surfaces may also be bonded to each other by a separate adhesive or the like interposed therebetween.

[0068] Meanwhile, in the present embodiment, the outer film (40) may include first and second extension portions (44a, 44b). The first extension portion (44a) may extend from one edge of the receiving portion (42), and the second extension portion (44b) may extend from the other edge of the receiving portion (42).

[0069] At this time, one edge and the other edge of the receiving portion (42) may be edges arranged in parallel in the circumferential direction of the electrode assembly (10). These one edge and the other edge may be provided along the longitudinal direction (X-axis direction) of the electrode assembly (10).

[0070] In this embodiment, the first and second extension portions (44a, 44b) can be extended to a predetermined length in the longitudinal direction (X-axis direction) of the electrode assembly (10). At this time, the first and second extension portions (44a, 44b) can be extended parallel to each other and overlap each other.

[0071] Referring to FIGS. 3 and 4, the outer film (40) of the secondary battery according to one embodiment of the present invention may include a joining portion (46). The joining portion (46) may be configured to join the first extension portion (44a) and the second extension portion (44b). Through this, the electrode assembly surrounded by the cap (20) and the outer film (40) may be isolated from the outside and sealed.

[0072] The joint portion (46) can be formed by applying heat or pressure to the first extension portion (44a) and the second extension portion (44b) that are arranged to overlap each other. The joint portion (46) can be formed as the resin layer provided on the outer surface of the first extension portion (44a) and the second extension portion (44b) is melted by the heat or pressure. Of course, the joint portion (46) can also be formed by a separate adhesive interposed between the first and second extension portions (44a, 44b).

[0073] At this time, the corner (28) of the cap (20) is a part where it is difficult to apply sufficient force, heat, or pressure for bonding due to its structural characteristics. By positioning the bonding portion (46) to correspond to this corner (28), leakage between the cap (20) and the outer film (40) can be prevented. Through this, the sealing property of the secondary battery can be improved.

[0074] In particular, in the present embodiment, the connecting portion (46) may be configured to be adjacent to the corner (28) of the cap (20). Through this, the connecting portion (46) can further enhance the sealing property of the secondary battery by more strongly connecting the corner (28) and the first and second extension portions (44a, 44b).

[0075] At this time, in the present embodiment, the connecting portion (46) may be provided along the extension direction (X-axis direction) of the edge (28). Through this, the first and second extension portions (44a, 44b) may be strongly connected along the entire length of the edge (28).

[0076] Meanwhile, referring to FIG. 4, in the present embodiment, the joint (46) may be positioned at a section (S) on the edge (28) based on the cross-section of the edge (28). Here, the cross-section of the edge (28) may be a cross-section along a plane (a plane including the Y-axis and the Z-axis) perpendicular to the longitudinal direction (X-axis direction) of the edge (28).

[0077] In the present embodiment, the section (S) may be located between a first point (P1) and a second point (P2). Here, the first point (P1) may be a point where the first surface (24) and the corner (28) meet, and the second point (P2) may be a point where the second surface (26) and the corner (28) meet. The first and second points (P1, P2) may be located on a cross-section of the corner (28).

[0078] At this time, the above section (S) may be a section from the third point (P3) to the fourth point (P4). Here, if the length measured from the first point (P1) to the second point (P2) along the cross-section of the corner (28) is referred to as the corner length (L), the third point (P3) may be a point spaced apart from the first point (P1) by 1 / 3 of the corner length (L).

[0079] Alternatively, the third point (P3) may be a point spaced apart from the first point (P1) by 2 / 5 of the edge length (L). Alternatively, the third point (P3) may be a point spaced apart from the first point (P1) by 3 / 7 of the edge length (L). Alternatively, the third point (P3) may be a point spaced apart from the first point (P1) by 1 / 2 of the edge length (L).

[0080] In other words, the third point (P3) may be a point spaced apart from the first point (P1) by a first angle (a1) based on the center (C) of the corner (28). Here, the center (C) of the corner (28) may be the center of an arc (or an elliptical arc) of the cross-section of the corner (28), and the first angle (a1) may be 30 degrees. Alternatively, the first angle (a1) may be 36 degrees. Alternatively, the first angle (a1) may be 39 degrees. Alternatively, the first angle (a1) may be 45 degrees.

[0081] Through this configuration, the joint (46) and the first point (P1) can be positioned at a predetermined distance, so that the joint (46) can more tightly fill the space between the outer film (40), the edge (28), and the first surface (24). Accordingly, the sealing property of the secondary battery can be further improved.

[0082] Meanwhile, in the present embodiment, the fourth point (P4) may be a point spaced apart from the first point (P1) by 2 / 3 of the edge length (L). Alternatively, the fourth point (P4) may be a point spaced apart from the first point (P1) by 3 / 5 of the edge length (L). Alternatively, the fourth point (P4) may be a point spaced apart from the first point (P1) by 4 / 7 of the edge length (L). Alternatively, the fourth point (P4) may be a point spaced apart from the first point (P1) by 1 / 2 of the edge length (L).

[0083] In other words, the fourth point (P4) may be a point spaced apart from the first point (P1) by a second angle (a2) based on the center (C) of the corner (28). Here, the second angle (a2) may be 60 degrees. Alternatively, the second angle (a2) may be 54 degrees. Alternatively, the second angle (a2) may be 51 degrees. Alternatively, the second angle (a2) may be 45 degrees.

[0084] Through this configuration, the joint (46) and the second point (P2) can be positioned at a predetermined distance, so that the joint (46) can more tightly fill the space between the outer film (40), the edge (28), and the second surface (26). Accordingly, the sealing property of the secondary battery can be further improved.

[0085] Below, a battery pack according to one embodiment of the present invention is described.

[0086] A battery pack according to one embodiment of the present invention may include at least one secondary battery and packaging for accommodating the secondary battery. In this case, the secondary battery may be a secondary battery according to one embodiment of the present invention described above.

[0087] In this embodiment, the packaging may include a housing having a body shape for accommodating a secondary battery. The housing may be provided with at least one support frame for supporting the secondary battery.

[0088] At this time, the housing may be equipped with a bus bar for energizing the secondary battery contained within it with the outside, a vent plug for connecting the inside and outside, and the like. The structure and shape of such packaging may be appropriately modified as needed.

[0089] Hereinafter, a method for manufacturing a secondary battery according to one embodiment of the present invention (hereinafter referred to as a manufacturing method) is described.

[0090] A manufacturing method according to one embodiment of the present invention may be a method for manufacturing a secondary battery according to one embodiment of the present invention described above. Of course, this manufacturing method is not limited to manufacturing only the secondary battery described above. Figure 5 is a flowchart of a method for manufacturing a secondary battery according to one embodiment of the present invention. Figure 6 is a diagram illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0091] Referring to FIGS. 1, 2, and 5, in a manufacturing method according to one embodiment of the present invention, a cap (20) can be placed on one side of an electrode assembly (10) (S10). Here, the cap (20) placed in step S10 can be configured identically to the cap (20) of the secondary battery (1) according to one embodiment of the present invention.

[0092] At this time, in step S10, the cap (20) may be placed on one side of the electrode assembly (10) in the longitudinal direction (X-axis direction). If the caps (20) are configured as a pair, a pair of caps (20) may be placed on each of the two sides of the electrode assembly (10) in the longitudinal direction (X-axis direction).

[0093] Next, in a manufacturing method according to one embodiment of the present invention, an electrode assembly (10) is surrounded by a receiving portion (42) of an outer film (40) having a sheet shape (S20). At this time, in step S20, as the receiving portion (42) surrounds the electrode assembly (10), the edge portion of the receiving portion (42) and the outer peripheral surface of the cap (20) may be arranged to overlap each other. In other words, the edge portion of the receiving portion (42) may surround the outer peripheral surface of the cap (20).

[0094] Here, the edge portion of the receiving portion (42) may be a edge portion located on one side of the length direction (X-axis direction) of the electrode assembly (10), and the outer peripheral surface of the cap (20) may include the first to fourth surfaces.

[0095] Next, in a manufacturing method according to one embodiment of the present invention, an electrode assembly (10) is surrounded by a receiving portion (42) (S20), and a first extension portion (44a) and a second extension portion (44b) extending from one edge and the other edge of the receiving portion (42) are positioned corresponding to a corner (28) of a cap (20) (S30). Here, the order of steps S20 and S30 is not particularly limited.

[0096] At this time, positioning the first and second extensions (44a, 44b) corresponding to the corner (28) in step S30 means positioning the part of the extensions (44a, 44b) closest to the receiving part (42) adjacent to the corner (28).

[0097] Referring to FIGS. 1, 3, and 6, in a manufacturing method according to one embodiment of the present invention, the first and second extension parts (44a, 44b) are positioned at the corners (28) (S30), and a joining part (46) is formed at a position corresponding to the corners (28) (S40). The joining part (46) is configured to join the first extension part (44a) and the second extension part (44b).

[0098] To this end, heat or pressure may be applied to a first region (S1) corresponding to the corner (28) among several portions of the first extension portion (44a) or the second extension portion (44a, 44b). Accordingly, the resin layer provided on the outer surface of the first and second extension portions (44a, 44b) or the cap (20) may be melted, and a joining portion (46) that joins the cap (20) and the outer film (40) may be formed.

[0099] In this way, according to the manufacturing method according to one embodiment of the present invention, since a joining portion (46) is formed at the corner (28) of the cap (20), the sealing property between the outer film (40) and the cap (20) can be improved.

[0100] At this time, if the caps (20) are configured as a pair, the first region (S1) to which heat or pressure is applied in step S40 may also be provided on each of the longitudinal sides of the electrode assembly (10).

[0101] At this time, a first region (S1) to which heat or pressure is applied to form a joint (46) in step S40 may be provided along the extension direction (X-axis direction) of the edge (28). The length of the first region (S1) may correspond to the length of the edge (28). Through this, since the joint (46) can be formed over the entire section of the edge (28), the sealing property of the secondary battery can be further improved.

[0102] Meanwhile, in the present embodiment, the joint portion (46) has been described as being formed by melting the resin layer of the extension portion (44a, 44b) or the cap (20). However, the joint portion (46) may be composed of other materials as needed. For example, the joint portion (46) may be composed of a predetermined adhesive, and the first region (S1) may be defined as the region where the adhesive is applied.

[0103] Next, in a manufacturing method according to one embodiment of the present invention, a joining part (46) that joins the first and second extension parts (44a, 44b) is formed (S40), and a receiving part (42) and a cap (20) are joined (S50).

[0104] At this time, according to the present embodiment, since the relative positions of the cap (20) and the outer film (40) are fixed to some extent by the joint (46) formed in step S40, step S50 can be performed more easily.

[0105] Meanwhile, in step S50, a predetermined amount of heat or pressure may be applied to the second region (S2) to combine the cap (20) and the receiving portion (42). Here, the second region (S2) may be a region where the edge portion of the receiving portion (42) and the outer peripheral surface of the cap (20) are arranged to overlap each other.

[0106] Accordingly, the resin layer provided on the outer surface of the cap (20) or the receiving portion (42) is melted, and the two components can be combined. Of course, if necessary, a separate adhesive may be applied to the second region (S2) to combine the receiving portion (42) and the cap (20).

[0107] Referring to FIGS. 5 and 6, in a manufacturing method according to one embodiment of the present invention, a receiving portion (42) and a cap (20) are combined (S50), and an additional joining portion is formed to join an area not joined by a joining portion (46) in the first and second extension portions (44a, 44b) (S60). Here, the order of steps S50 and S60 is not particularly limited.

[0108] For this purpose, heat or pressure may be applied to the third region (S3) at step S60. Of course, a separate adhesive may be applied to the third region (S3) to join the first and second extensions (44a, 44b).

[0109] At this time, the third region (S3) may be a region provided along the edge of the receiving portion (42). Here, the edge may be a edge from which the first or second extension portion (44a, 44b) extends among the edges of the receiving portion (42). The edge may extend along the longitudinal direction (X-axis direction) of the electrode assembly (10).

[0110] The additional joint formed by the S60 step may extend along the edge of the receiving portion (42). Furthermore, joint portions (46) may be provided on both longitudinal sides of the additional joint portion. Through this, the first extension portion (44a) and the second extension portion (44b) may be joined as a whole, and sealing of the secondary battery may be achieved.

[0111] Meanwhile, the third region (S3) may partially overlap the first region (S1). Alternatively, the third region (S3) may include the first region (S1). In other words, the connecting portion (46) and the additional connecting portion may be connected to each other. This may further enhance the sealing properties of the secondary battery.

[0112] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0113] [Explanation of symbols]

[0114] 1: Secondary battery 10: Electrode assembly

[0115] 20: Cap 30: Terminal

[0116] 40: Outer film L: Edge length

[0117] C: Center P1: First point

[0118] P2: Second point P3: Third point

[0119] P4: Fourth point

Claims

1. A cap comprising a first surface, a second surface perpendicular to or inclined with respect to the first surface, and an edge connecting the first surface and the second surface; An electrode assembly having one side covered by the cap; and An outer film including a sheet-shaped receiving portion that surrounds the electrode assembly in a circumferential direction, first and second extension portions extending from one edge and the other edge of the receiving portion, respectively, and a joining portion that joins the first and second extension portions, A secondary battery, wherein the above-mentioned connecting portion is positioned corresponding to the above-mentioned corner.

2. In paragraph 1, The above-mentioned connecting portion is a secondary battery that is in contact with the above-mentioned corner.

3. In paragraph 1, The above corners are formed to be round, secondary batteries.

4. In paragraph 1, The above-mentioned joint is located in a section between the first point and the second point based on the cross-section of the corner, The above first point is the point where the corner and the first surface meet, The second point is a secondary battery where the corner and the second surface meet.

5. In paragraph 4, The above section is the section from point 3 to point 4, When the length measured from the first point to the second point along the cross section of the above edge is called the edge length, The third point is spaced apart from the first point by 1 / 3 of the length of the edge along the cross-section of the edge, The fourth point is a secondary battery, spaced apart from the first point by 2 / 3 of the length of the edge along the cross-section of the edge.

6. In paragraph 4, A secondary battery having a cross-section of the above corner having a circular or elliptical arc shape.

7. In paragraph 6, The above section is the section from point 3 to point 4, The third point is spaced 30 degrees apart from the first point based on the center of the circular or elliptical arc, The fourth point is a secondary battery spaced 60 degrees apart from the first point based on the center of the circular or elliptical arc.

8. In paragraph 1, The above electrode assembly extends in the first direction, The above cap covers one side of the first direction of the electrode assembly, A secondary battery, wherein the corner and the connecting portion extend along the first direction.

9. In paragraph 1, The above caps are configured as a pair and are placed on each side of the electrode assembly, A secondary battery, wherein the above-mentioned connecting portion is configured as a pair corresponding to the above-mentioned cap.

10. In paragraph 1, A secondary battery, wherein the first extension portion is parallel to the second extension portion.

11. In paragraph 1, A secondary battery, wherein the first surface is perpendicular to the second surface.

12. In paragraph 1, A secondary battery, wherein the above-mentioned connecting portion is formed by joining the first extension portion and the second extension portion to each other.

13. A step of placing a cap on one side of an electrode assembly, the cap including a first surface, a second surface perpendicular or inclined to the first surface, and an edge connecting the first surface and the second surface; A step of surrounding the electrode assembly with a receiving portion of an outer film having a sheet shape; A step of positioning first and second extensions extending from one edge and the other edge of the receiving portion, respectively, corresponding to the corners; and A method for manufacturing a secondary battery, comprising a step of forming a joining portion for joining the first extension portion and the second extension portion at a position corresponding to the corner.

14. In paragraph 13, A method for manufacturing a secondary battery, further comprising the step of combining the first and second surfaces and the receiving portion.

15. In paragraph 14, A method for manufacturing a secondary battery, wherein the step of forming the above-mentioned bonding portion is performed before the step of bonding the first and second surfaces and the receiving portion.

16. In paragraph 14, A method for manufacturing a secondary battery, further comprising the step of forming an additional bonding portion to bond an area not bonded by the bonding portion in the first and second extension portions.

17. In paragraph 16, The above additional connecting portion extends along the edge of the receiving portion, A method for manufacturing a secondary battery, wherein the above-mentioned connecting portion is located at one end of the additional connecting portion.

18. In paragraph 13, A method for manufacturing a secondary battery, wherein in the step of forming the above-mentioned joint, heat or pressure is applied to at least one of the first extension portion and the second extension portion.

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