Secondary battery and battery pack including same

Abstract

A secondary battery according to an embodiment described in the present specification comprises: an electrode assembly extending in one direction; an exterior film that surrounds a portion of the electrode assembly; and a cap that surrounds the remainder of the electrode assembly. The cap includes: a cover part that covers one side of the electrode assembly in the extension direction; a connection part that is provided on the outer surface of the cover part and includes a plurality of coupling portions coupled to the exterior film; and a terminal part that is at least partially exposed to the outside of the cover part and electrically connected to the electrode assembly. The coupling portions of the connection part are connected so as to be rounded at the point where the coupling portions meet, thereby forming corner edges. The corner edges have a radius of curvature Rg of 0.1 mm to 1.5 mm, and have outer surfaces that permit bonding to the inner surface of the exterior film and inner surfaces that permit bonding to the outer surface of the cover part, and include a first layer having a first resin. The first resin includes a resin having a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C.

Description

Secondary battery and battery pack including the same

[0001] This specification relates to a secondary battery and a battery pack including the same.

[0002]

[0003] Recently, with rising energy prices due to the depletion of fossil fuels and growing concern over environmental pollution, the demand for eco-friendly alternative energy sources has become an indispensable factor for future life. Accordingly, research on various power generation technologies, such as solar, wind, and tidal power, is ongoing, and there is also significant interest in power storage devices, such as batteries, to utilize this generated electrical energy more efficiently.

[0004] Furthermore, as technological development and demand for battery-powered electronic mobile devices and electric vehicles increase, the demand for batteries as an energy source is rapidly rising, and accordingly, much research is being conducted on batteries capable of meeting various requirements.

[0005] Batteries that store electrical energy can generally be classified into primary and secondary batteries. Primary batteries are disposable, consumable batteries, whereas secondary batteries are rechargeable batteries manufactured using materials capable of repeating oxidation and reduction processes between the electric current and the material. For example, in a secondary battery, the power is charged when a reduction reaction is performed on the material by the electric current, and discharged when an oxidation reaction is performed; electricity is generated as this charging and discharging cycle is repeated.

[0006]

[0007] The embodiments of the present specification provide a secondary battery with fewer restrictions on shape, improved battery capacity, reduced amount of moisture entering from the outside, and improved structural stability.

[0008] Embodiments of the present specification provide a secondary battery with improved safety by controlling the direction in which gas or flame generated inside the secondary battery may be ejected.

[0009] The embodiments of this specification provide a secondary battery with excellent airtightness and durability by controlling the radius of curvature of the corner edge when sealing a connecting part capable of functioning as a gasket and an outer film, and by applying a resin having suitable melt flowability for sealing, thereby ensuring that there are no unsealed parts at the corner edge.

[0010]

[0011] [1] In one aspect, the secondary battery comprises an electrode assembly extending in one direction; an outer film covering a part of the electrode assembly; and a cap covering the remainder of the electrode assembly, wherein the cap comprises a cover portion covering one side of the extension direction of the electrode assembly; a connecting portion having a plurality of connecting portions provided on the outer surface of the cover portion and coupled with the outer film; and a terminal portion having at least a portion exposed to the outside of the cover portion and electrically connected to the electrode assembly, wherein the connecting portions of the connecting portion are rounded at the point where they meet to form a corner edge, and the corner edge has a radius of curvature Rg of 0.1 mm to 1.5 mm, an outer surface allowing coupling with the inner surface of the outer film and an inner surface allowing coupling with the outer surface of the cover portion, and comprises a first layer including a first resin, wherein the first resin comprises a resin having a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C.

[0012] [2] In the secondary battery of [1] above, the first resin has a melting point (T m It may include a resin having a temperature of 135°C to 150°C and a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C.

[0013] [3] In the secondary battery of [1] and / or [2] above, the first resin may include a modified polyolefin-based resin.

[0014] [4] In at least one of the secondary batteries of [1] to [3] above, the coupling portion of the connection portion may include a first layer that includes a first resin and allows coupling with the outer surface of the cover portion, and a second layer that includes a second resin, is laminated on the outer surface of the first layer, and allows coupling with the inner surface of the outer film.

[0015] [5] In the secondary battery of [4] above, the second resin has a melting point (T m A resin having a temperature of 120°C to 145°C, a resin having a melt flow rate (MFR) at 230°C of 5 g / 10 min to 18 g / 10 min, and a melting point (T m It may include a resin selected from the group consisting of resins having a temperature of 120°C to 145°C and a melt flow rate (MFR) at 230°C of 5 g / 10 min to 18 g / 10 min.

[0016] [6] In at least one of the secondary batteries of [1] to [5] above, the first resin and the second resin may satisfy at least one of the relationships selected from the following Equation 1 and the following Equation 2.

[0017] [Equation 1]

[0018] T m2 > T m1

[0019] T in Equation 1 above m1 is the melting point of the first resin, and T m2 is the melting point of the second resin, and the unit is °C, and

[0020] [Equation 2]

[0021] MFR2> MFR1

[0022] In the above Equation 2, MFR1 is the melt flow rate of the first resin and MFR2 is the melt flow rate of the second resin, and the unit is g / 10 min.

[0023] [7] In at least one of the secondary batteries of [4] to [6] above, the first resin may include a modified polyolefin resin, and the second resin may include an unoriented polyolefin resin.

[0024] [8] In at least one of the secondary batteries of [1] to [7] above, the outer circumferential surface of the cover portion extends in the circumferential direction of the electrode assembly, and the coupling portion may be provided on the outer circumferential surface of the cover portion.

[0025] [9] In at least one of the secondary batteries of [1] to [8] above, the cover portion is,

[0026] A cover portion having an outward-facing surface facing the outside of the electrode assembly; and an extension portion extending from the cover portion toward the electrode assembly, wherein the coupling portion may be provided on the outer surface of the extension portion.

[0027]

[0010] In the secondary battery of [9] above, the cover portion has a plate shape, and the extension portion may extend from the edge of the cover portion.

[0028]

[0011] In the secondary battery of [9] above, the radius of curvature of the cover edge formed at a position corresponding to the corner edge on the cover portion may be smaller than or equal to the radius of curvature of the corner edge.

[0029]

[0012] In at least one of the secondary batteries of [1] to

[0011] above, the outer film may have a certain flexibility so that it can be bent.

[0030]

[0013] In at least one of the secondary batteries of [1] to

[0012] above, the connecting portion may be provided on the outer surface of the cover portion, and may include a connecting portion provided on at least one of the outer surfaces of the cover portion excluding the outer surface of the cover portion where the connecting portion is provided.

[0031]

[0014] In the secondary battery of the above

[0013] , the connecting portion of the connecting portion may include a first layer having an outer surface that allows bonding with the inner surface of the outer film and an inner surface that allows bonding with the outer surface of the cover portion, and a first layer that includes a first resin.

[0032]

[0014] In the secondary battery of

[0012] and / or

[0013] above, the connecting portion of the connecting portion may include a first layer comprising a first resin and allowing bonding with the outer surface of the cover portion, and a second layer comprising a second resin that is laminated on the outer surface of the first layer and allowing bonding with the inner surface of the outer film.

[0033]

[0015] In another aspect, the battery pack comprises a secondary battery; and a packaging that accommodates the secondary battery, wherein the secondary battery comprises an electrode assembly extending in one direction; an outer film covering a portion of the electrode assembly; and a cap covering the remainder of the electrode assembly, wherein the cap comprises a cover portion covering one side of the extension direction of the electrode assembly; a connecting portion including a connecting portion provided on the outer surface of the cover portion and coupled with the outer film; and a terminal portion at least a portion of which is exposed to the outside of the cover portion and electrically connected to the electrode assembly, wherein the connecting portion of the connecting portion is rounded at the point where they meet to form a corner edge, and the corner edge is characterized by having a radius of curvature Rg of 0.1 mm to 1.5 mm.

[0034]

[0035] Since the secondary battery according to a preferred embodiment of the present invention does not have a process for forming an outer film, there are fewer restrictions on the shape in which the outer film accommodates the electrode assembly, the possibility of defects such as cracks occurring in the outer film is reduced, and the battery capacity can be improved.

[0036] In addition, the safety of the secondary battery can be improved by reducing the degree to which moisture and other substances penetrate from the outside into the inside of the secondary battery.

[0037] In addition, it has excellent sealing strength, superior airtightness, and robustness, allowing it to withstand internal pressure caused by gases generated inside the secondary battery up to a high level, thereby improving the durability of the secondary battery.

[0038] In addition, the terminal section and busbar can be electrically connected to the electrode assembly in various forms.

[0039] In addition, the structural stability of the secondary battery can be improved by the combination relationship and arrangement form of the connection part and the cover part, and through structural stability, the problem of venting to the cap part in the event of an explosive increase in internal pressure or flame eruption can be controlled.

[0040] In addition, the secondary battery can be efficiently electrically connected to the outside through the terminal portion penetrating the connection portion.

[0041] In addition, the outer part of the connection part can protect the cover part of the cover part from external contamination or impact.

[0042] In addition, the outer part and the connecting part are connected, so the bonding between the connecting part and the cover part can be improved.

[0043] In addition, since the cover portion is covered by the outer portion, the insulation between the cover portion and other components can be improved, and heat transfer can be suppressed in the event of thermal runaway.

[0044] In addition, since the cover portion is entirely surrounded by the connecting portion, the cap can be easily manufactured using an insert injection molding process.

[0045] The effects according to the present invention are not limited to those exemplified above, and various other effects are included in this specification.

[0046]

[0047] FIG. 1 is a perspective view of a battery pack according to an embodiment of the present invention viewed from above. In this case, the packaging is indicated by a dotted line, and the configuration visible through the packaging is indicated by a solid line.

[0048] FIG. 2 is a perspective view of a secondary battery according to the first embodiment of the present specification, viewed from above.

[0049] Figure 3 is an exploded perspective view of the secondary battery shown in Figure 2.

[0050] FIG. 4 is an exploded perspective view showing the state in which the connecting part and the cover part are combined in FIG. 3.

[0051] Figure 5 is a drawing showing a part of the cross-sectional view along A-A' of Figure 2.

[0052] Figure 6 is a drawing showing a part of the cross-sectional view along B-B' of Figure 2.

[0053] FIG. 7 is a perspective view of a secondary battery according to a second embodiment of the present specification, viewed from above.

[0054] Fig. 8 is an exploded perspective view of the secondary battery shown in Fig. 7.

[0055] Figure 9 is a drawing showing a part of the cross-sectional view along C-C' of Figure 7.

[0056] FIG. 10 is a partial cross-sectional view of a secondary battery according to the third embodiment of the present specification, cut along C-C' of FIG. 7.

[0057] FIG. 11 is a perspective view showing the sealing surface of the outer film and the connection part that are sealed by a vertical sealing device.

[0058] FIG. 12 is a perspective view showing the sealing surface of the outer film and the connection part that are sealed by a corner-type sealing device.

[0059] FIG. 13 is a partial cross-sectional view of a secondary battery (a first modified example of the coupling portion) according to the fourth embodiment of the present invention, cut along C-C' of FIG. 7.

[0060] FIG. 14 is a partial cross-sectional view of a secondary battery (a second modified example of the coupling portion) according to the fourth embodiment of the present invention, cut along C-C' of FIG. 7.

[0061] FIG. 15 is a partial cross-sectional view of a secondary battery (third modified example of the coupling portion) according to the fourth embodiment of the present invention, cut along C-C' of FIG. 7.

[0062]

[0063] The advantages and features of the secondary battery described in this specification, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the secondary battery described in this specification is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the invention is complete and to fully inform those skilled in the art of the scope of the invention, and the invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0064] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0065] The terms used herein are for describing the embodiments and are not intended to limit the invention relating to the secondary battery described herein. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0066] In this specification, when a part is described as including a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0067] In this specification, the description "A and / or B" means A, or B, or A and B.

[0068]

[0069] Secondary batteries can be classified into cylindrical cells, pouch cells, prismatic cells, etc., depending on their shape. Among these, pouch cells can be manufactured in a form in which an electrode assembly consisting of a positive electrode, a negative electrode, and a separator is stacked inside a pouch, and the outer part of the pouch is sealed.

[0070] Conventional pouch cells suffer from the problem of cracks occurring in the pouch film during the molding process, resulting in a large amount of discarded film after the degassing process. Furthermore, the molding depth is limited by the material properties of the pouch film, which consequently limits the increase in battery capacity. Moreover, since existing pouch cells are constructed by cup-molding the upper and lower cases using pouch film and sealing the outer surfaces of the two cases together, there is a problem in that there are limitations in controlling or predicting the venting direction of the cell in situations where abnormal cell behavior could lead to increased internal pressure or explosion.

[0071] The present invention provides a secondary battery with a shape that allows for improved battery capacity while having relatively few limitations on its shape, and furthermore, provides a secondary battery capable of controlling the direction of ejection when gas is released inside the cell or when a flame occurs.

[0072] Hereinafter, the secondary battery described in this specification will be explained in detail.

[0073] A secondary battery according to the present specification comprises at least one of the configurations described below and may comprise any combination of technically feasible configurations among the following configurations.

[0074]

[0075] FIG. 1 is a perspective view of a battery pack according to an embodiment of the present invention viewed from above. In this case, the packaging is indicated by a dotted line, and the configuration visible through the packaging is indicated by a solid line.

[0076] FIG. 1 discloses a battery pack according to one embodiment of the present invention. Referring to FIG. 1, the battery pack (1) according to one embodiment of the present invention may be a battery pack for charging and discharging electrical energy.

[0077] A battery pack (1) according to one embodiment of the present invention may include a secondary battery (3). In this case, the secondary battery (3) may be composed of a plurality of units. Meanwhile, the battery pack (1) may include a packaging (2) that accommodates a plurality of secondary batteries (3) inside. The packaging (2) may be configured to protect the secondary batteries (3) from external shock or contamination.

[0078] In this embodiment, the packaging (2) may be provided as a box-shaped structure. The packaging (2) may be made of metal or plastic having a certain rigidity. The packaging (2) may have a structure in which a plurality of plates are combined.

[0079] However, the shape or structure of the packaging (2) may be modified as needed. For example, at least one part of the packaging (2) may have a curved shape. Additionally, other parts may be additionally provided in the packaging (2). For example, the packaging (2) may be provided with a bus bar electrically connected to a plurality of secondary batteries (3) and / or a venting part that communicates the inside and outside of the packaging (2).

[0080]

[0081] Hereinafter, a secondary battery according to an embodiment of the present invention is described.

[0082] Embodiment 1

[0083] FIG. 2 is a perspective view of a secondary battery according to a first embodiment of the present invention viewed from above. FIG. 3 is an exploded perspective view of the secondary battery shown in FIG. 2. FIG. 4 is an exploded perspective view showing the state in which the connecting part and the cover part are combined in FIG. 3. FIG. 5 is a drawing showing a part of the cross-sectional view along A-A' of FIG. 2. FIG. 6 is a drawing showing a part of the cross-sectional view along B-B' of FIG. 2.

[0084] Referring to FIGS. 2 to 6, a secondary battery (3) according to the first embodiment of the present invention may include an electrode assembly (10), an outer film (20), and a cap (30). Below, each component of the secondary battery (3) will be described in more detail. For reference, the details of the first embodiment may be applied equally to other embodiments described later, provided they do not conflict with one another.

[0085]

[0086] electrode assembly

[0087] The electrode assembly (10) of the secondary battery (3) may include a positive electrode, a negative electrode, and a separator. Here, the separator may be placed between the positive electrode and the negative electrode to physically separate the positive electrode and the negative electrode. The electrode assembly (10) may be in a stacked form in which the positive electrode, the negative electrode, and the separator are stacked, or in a jelly-roll form in which the positive electrode, the negative electrode, and the separator are wound. The type or structure of the electrode assembly (10) is not particularly limited. The electrode assembly (10) may be extended in one direction (X-axis direction) and have a predetermined length.

[0088] Meanwhile, the electrode assembly (10) may be provided with an electrode tab (11) connected to the electrode. The electrode tab (11) may be provided separately or may be provided as part of a current collector constituting the electrode. For reference, if the electrode assembly (10) is an all-solid-state battery, a solid electrolyte may be provided instead of a separator.

[0089]

[0090] Exterior film

[0091] Referring to FIGS. 1 to 6, a secondary battery (3) according to a first embodiment of the present invention may include an outer film (20). The outer film (20) of the secondary battery (3) may be provided to wrap around a part of an electrode assembly (10). For example, the outer film (20) may be provided to wrap around a cap (30) and an electrode assembly (10) to be described later. According to a more embodiment, the outer film (20) may be combined with the cap (30) to form an internal space, and an electrode assembly (10) may be accommodated in the formed internal space.

[0092] As described in this embodiment, the outer film (20) may wrap around the electrode assembly (10) in a circumferential direction. The circumferential direction may be a direction that wraps around an axis (X-axis) parallel to the extension direction of the electrode assembly (10). The outer film (20) may be made of a material capable of deformation so as to wrap around the electrode assembly (10). For example, the outer film (20) may have a certain flexibility so as to be bent by an external force.

[0093] Additionally, the outer film (20) may be made of a non-stretchable material. Conventionally, a pouch film was molded to form a space for accommodating the electrode assembly. However, since the outer film (20) does not need to change its shape through molding, it may be made of a non-stretchable material. However, if necessary, the outer film (20) may have a certain degree of stretchability.

[0094] The outer film (20) of the secondary battery (3) may have a shape in which a sheet or film is rolled along the side of the electrode assembly (10). For example, the outer film (20) may be arranged to wrap around the side of the electrode assembly (10). At this time, the outer film (20) may be arranged to wrap around the electrode assembly (10) while the one end and the other end meet each other. Regarding the shape in which the one end and the other end of the outer film (20) meet each other, the one side of the one end and the other side of the other end may be joined so that they overlap and come into contact with each other (see FIG. 2). This is merely an example, and the shape in which the one end and the other end are joined to form a space for the outer film (20) to accommodate the electrode assembly (10) may vary.

[0095] Regarding the method of joining one end and the other end of the exterior film (20), the one end and the other end of the exterior film (20) may be joined to each other by heat sealing or by heat and pressure sealing. For example, the exterior film (20) may include a material having heat sealing properties.

[0096] As an example of the structure of the outer film (20), the outer film (20) may be formed in the form of a film. For example, the outer film (20) may be provided with a plurality of layers including a sealant layer, a barrier layer, and an insulating layer. For example, the outer film (20) may be arranged in the order of a sealant layer, a barrier layer, and an insulating layer from the inside close to the electrode assembly (10).

[0097] According to one embodiment, the sealant layer may include a material having heat-sealing properties so that one end and the other end of the exterior film (20) can be joined. For example, the sealant layer of the exterior film (20) may include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Mainly, polyolefin resins such as polypropylene (PP) or polyethylene (PE) may be used. Polypropylene (PP) may have excellent mechanical properties such as tensile strength, stiffness, surface hardness, wear resistance, and heat resistance, as well as chemical properties such as corrosion resistance.

[0098] The barrier layer may include a metal. For example, the metal of the barrier layer may be one or more materials selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), and aluminum (Al). As an example, the barrier layer may include stainless steel (STS). Additionally, the barrier layer may be made of an alloy such as an aluminum alloy.

[0099] The insulating layer may include an insulating material. The electrode assembly (10) can be insulated from the outside by the insulating layer. Thus, the insulating layer can prevent short circuits, etc., of the outer film (20). For example, the insulating layer may include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Mainly, polymers such as nylon resin or polyethylene terephthalate (PET) having wear resistance and heat resistance may be used.

[0100] Meanwhile, the outer film (20) may be arranged to wrap a part of the electrode assembly (10) and the cap (30) may be arranged to wrap the remainder of the electrode assembly (10). For example, if the outer film (20) is arranged to wrap the electrode assembly (10) along the side (or outer circumference) of the electrode assembly (10), an opening formed by the edges of the outer film (20) may be formed at both ends of the electrode assembly (10). At this time, the opening may be located on both sides in the extension direction (X-axis direction) of the electrode assembly (10).

[0101] The cap (30) of the secondary battery (3) can be combined with an outer film (20) in a manner that covers the openings on both sides of the electrode assembly (10). Additionally, the electrode assembly (10) can be accommodated in the internal space formed by the outer film (20) and the cap (30).

[0102] The exterior film (20) can be combined with the cap (30). As an example of the method of combining the cap (30) and the exterior film (20), the cap (30) and the exterior film (20) can be combined by welding. Specifically, the connecting part (40) described later may include a metal material, and the exterior film (20) may include a metal layer that can be combined with the connecting part (40) by welding in the portion facing the connecting part (40).

[0103] As another example of a method of joining the cap (30) and the exterior film (20), the cap (30) and the exterior film (20) may be joined by sealing. Specifically, the connecting portion (40) may include a resin material that has adhesive properties by heat, and the exterior film (20) may include a resin layer that can be joined to the connecting portion (40) by heat and pressure in the portion facing the connecting portion (40). Here, the resin layer may include a material having heat-sealing properties as described above.

[0104] Conventional pouch cells formed a cup portion to accommodate an electrode assembly (10) by forming a sheet or film. During the forming process of the cup portion, the depth that could be formed was limited depending on the material characteristics of the sheet or film, and the capacity to accommodate the electrode assembly (10) was also limited. In addition, when forming a sheet or film, the thickness at the corners became the thinnest, and defects such as cracks frequently occurred. Furthermore, conventional pouch cells required a gas collection portion to collect gas during the degassing process to remove gas accumulated inside the pouch, and a large amount of the gas collection portion was removed and discarded after the degassing process.

[0105] In the secondary battery (3) according to the first embodiment of the present invention, since the outer film (20) can be used to fit the volume of the electrode assembly (10), there may be no limitation on the capacity that can accommodate the electrode assembly (10). In addition, since molding of the cup portion is not required, defects such as cracks in the outer film (20) can be prevented, and the material and thickness of the outer film (20) can be selected relatively freely. Furthermore, since the electrolyte injection and degassing processes can be carried out through the cap (30), no waste outer film (20) is generated, thereby improving the economic efficiency of the process.

[0106]

[0107] cap

[0108] Referring to FIGS. 2 to 6, the cap (30) of the secondary battery (3) according to the first embodiment of the present invention may include a connecting portion (40), a cover portion (50), and a terminal portion (60). In this embodiment, the cap (30) may seal the electrode assembly (10) together with the outer film (20). As a result, the discharge of gas or flames due to internal abnormal behavior phenomena may be guided (or concentrated) toward the outer film (20), thereby improving the stability of the secondary battery (3).

[0109] The connecting portion (40) of the cap (30) can be combined with the exterior film (20). Additionally, the cover portion (50) of the cap (30) is combined with the connecting portion (40) and may be provided so that a portion of it is exposed to the outside of the connecting portion (40). For example, one side of the cover portion (50) may be exposed to the outside of the connecting portion (40).

[0110] Here, the inner side of the connecting part (40) may refer to a part of the internal space formed by the cap (30) and the outer film (20), and the outer side of the connecting part (40) may refer to the space outside the cap (30) and the outer film (20).

[0111] Additionally, one side of the cover portion (50) exposed to the outside of the connection portion (40) may be an outward-facing surface (51a) facing outward. The outward-facing surface (51a) may be provided in the cover portion (51) of the cover portion (50) described later. The surface of the cover portion (51) facing the outward-facing surface (51a) may be named an inward-facing surface (51b). The inward-facing surface (51b) may be a surface facing the electrode assembly (10).

[0112] Referring to FIGS. 2 through 6, in this embodiment, the connecting portion (40) may include a connecting portion (41). The connecting portion (41) may be a portion that directly connects the cover portion (50) and the exterior film (20) described later. If necessary, the connecting portion (41) may be composed of a single layer containing one material, a single layer containing different materials, a plurality of layers each containing different materials, or a plurality of layers each containing different materials.

[0113] In this embodiment, the connecting portion (41) may be provided on the outer surface (54a) of the extension portion (54) in the cover portion (50). Here, the outer surface (54a) of the extension portion (54) may be a surface facing outward (or an outer perimeter surface). The connecting portion (41) may be provided between the extension portion (54) and the outer film (20) to connect them.

[0114] In this embodiment, the connecting portion (41) may be provided along the outer surface (54a) (or outer circumference) of the extension portion (54). As will be described later, since the extension portion (54) in this embodiment has a ring shape, the connecting portion (41) may also have a ring shape corresponding to the extension portion (54). At this time, the ring shape may be a shape viewed in the longitudinal direction (X-axis direction) of the electrode assembly (10). The shape of the connecting portion (41) may be appropriately modified according to the structure of the cover portion (50).

[0115] Additionally, in this embodiment, the connecting portion (40) may include an inner portion (43). The inner portion (43) may be provided on the inward surface (51b) of the cover portion (51). The inner portion (43) may cover the inward surface (51b) entirely. The inner portion (43) may have a plate shape having a predetermined thickness. Through this, heat transfer or moisture penetration through the cover portion (51) can be effectively suppressed. Meanwhile, a terminal hole (43a) may be provided in the inner portion (43). The terminal hole (43a) may be a hole through which the terminal portion (60), described later, passes.

[0116] Meanwhile, in this embodiment, the connecting portion (40) may include an extension portion side portion (44). The extension portion side portion (44) may be provided on the inner surface (54b) (or inner circumference surface) of the extension portion (54) in the cover portion (50) described later. At this time, the inner surface (54b) of the extension portion (54) may be a surface facing the outer surface (54a). The inner surface (54b) may be a surface facing inward.

[0117] In this embodiment, the extension-side portion (44) may be provided along the inner surface (54b) (or inner circumference) of the extension portion (54). At this time, as the extension portion (54) has a ring shape, the extension-side portion (44) may also have a ring shape corresponding to the extension portion (54). At this time, the ring shape may be a shape viewed in the longitudinal direction (X-axis direction) of the electrode assembly (10). The shape of the extension-side portion (44) may be appropriately modified according to the structure of the cover portion (50).

[0118] At this time, the extension side portion (44) and the inner portion (43) can be connected to each other. In other words, the extension side portion (44) can be extended from the inner portion (43). The extension side portion (44) can be extended from the edge portion of the inner portion (43). Through this, the rigidity reinforcement, moisture penetration prevention, and heat transfer suppression effects of the cap (30) by the connection portion (40) can be increased.

[0119]

[0120] connection part

[0121] The connecting part (40) and corner edge (45) according to an embodiment of the present invention will be described in more detail.

[0122] Referring to FIGS. 2 to 11, the connecting portion (40) includes a plurality of connecting portions provided on the outer surface of the cover portion (50) and coupled with the exterior film, and the connecting portions (41) of the connecting portion (40) can be rounded at the points where they meet to form a corner edge (45).

[0123] The connecting portion (41) of the above connecting portion (40) may be provided on the outer surface (54a) of the extension portion (54) of the cover portion (50), that is, the surface facing outward (or the outer circumference surface), and the first extension portion (55), the third extension portion (57), the second extension portion (56), and the fourth extension portion (58) may be connected sequentially, and each may be connected in a rounded manner at the connecting portion to form a corner edge (45).

[0124] According to one embodiment, the corner edge (45) has a radius of curvature Rg of about 0.1 mm to 1.5 mm as shown in FIG. 2. The connecting portion (40) can function to improve the bonding strength between the cover portion (50) and the outer film (20), but airtightness at the corner edge (45) portion may be an issue. Since sealing must be performed along a plurality of connecting portions (41) of the connecting portion (40) having a three-dimensional shape, rather than a sealing method in which the upper and lower surfaces of the pouch film are overlapped and heat and pressure are applied as in conventional pouch-type secondary batteries, a sealing method may be applied by heating / pressing each of the four sides as shown in FIG. 11, which will be described later, or by heating / pressing with an "L"-shaped sealing block using a corner-type sealing device as shown in FIG. 12.

[0125] However, this sealing method may result in unsealed portions or breakage of the outer film (20) depending on the radius of curvature Rg of the corner edge (45). Accordingly, the radius of curvature Rg of the corner edge (45) needs to be controlled to a range of about 0.1 mm to 1.5 mm. At the radius of curvature in the above range, the probability of breakage of the outer film (20) corresponding to the corner edge (45) is reduced, and a superior seal is formed, thereby improving airtightness.

[0126] The radius of curvature Rg of the corner edge (45) has a range of about 0.1 mm to 1.5 mm, for example, it may be about 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, or about 0.5 mm or more, and may also be about 1.4 mm or less, 1.3 mm or less, 1.2 mm or less, 1.1 mm or less, or about 1.0 mm or less. When the connecting part (40) is molded to satisfy this range, sufficient airtightness can be secured through sealing with the exterior film (20). In addition, as described above, the radius of curvature Rc of the cover edge (54d) of the cover part (50) may be smaller than or equal to the radius of curvature Rg of the corner edge (45).

[0127]

[0128] Terminal section

[0129] Meanwhile, as an example of a configuration for electrical connection with the outside, the cap (30) of the secondary battery (3) according to the first embodiment of the present invention may include a terminal portion (60). The terminal portion (60) may penetrate the connection portion (40) and the cover portion (50) and be exposed to the outside and inside of the connection portion (40), respectively. The terminal portion (60) may be electrically connected to the electrode assembly (10) at the portion exposed to the inside of the connection portion (40). Here, the electrical connection may include both a direct connection between the terminal portion (60) and the electrode assembly (10) and an indirect connection through another electrically conductive member. The portion of the terminal portion (60) exposed to the outside of the connection portion (40) may be electrically connected to the outside.

[0130] For electrical connection with the electrode assembly (10) and the outside, the terminal portion (60) may include an electrically conductive material. The terminal portion (60) may be arranged in a form protruding outward from the connection portion (40) (see FIG. 2). Thus, the secondary battery (3) can be electrically connected to the outside in a more diverse manner and can efficiently provide electrical energy to the outside.

[0131] The structure of the terminal portion (60) is described in more detail below. The terminal portion (60) of the cap (30) according to the first embodiment of the present invention may extend from the inner side of the connecting portion (40) to the outer side of the connecting portion (40). At this time, the terminal portion (60) may be formed to have a constant cross-sectional area in the longitudinal direction. For example, the terminal portion (60) may have a cylindrical or rectangular shape. Here, a terminal portion (60) having a rectangular shape is described as an example. A terminal portion (60) having a constant cross-sectional area in the longitudinal direction may have relatively excellent ease of manufacturing.

[0132] The electrode assembly (10) may include electrodes and a separator stacked side by side. At this time, the terminal portion (60) may have one surface and the other surface formed at both ends of the portion exposed to the inside of the connection portion (40) based on the stacking direction of the electrodes and the separator, formed as flat surfaces. Referring to FIG. 4, the one surface and the other surface formed at both ends of the terminal portion (60) may be surfaces that contact the electrode tab (11) of the electrode assembly (10). Due to this shape, the terminal portion (60) can be connected more efficiently to the electrode tab (11).

[0133] In addition, when the secondary battery (3) includes a plurality of electrode assemblies (10), the electrode tabs (11) of the plurality of electrode assemblies (10) can each be electrically connected to one side and the other side of the terminal portion (60). Through this, the secondary battery (3) can efficiently increase the battery capacity.

[0134] In addition to the shape described in the first embodiment of the present invention, the terminal portion (60) may have various shapes for efficient electrical connection. Meanwhile, although not shown in detail in the drawings, a gasket may be provided on the outer periphery of the terminal portion (60). The gasket may be configured to prevent leakage of the electrolyte. The gasket may be interposed between the outer periphery of the terminal portion (60) and the cover portion (50). The gasket may be made of a polymer material such as plastic or rubber.

[0135] Below, the structure of the cover part (50) is explained in more detail.

[0136] As an example of a configuration to improve the structural stability of the cap (30), the cover portion (50) of the cap (30) according to the first embodiment of the present invention may have at least a portion embedded in the connecting portion (40). In this regard, the cover portion (50) of the cap (30) may include a cover portion (51) and an extension portion (54).

[0137] The cover portion (51) of the cover portion (50) may be located on one side in the longitudinal direction (X-axis direction) of the electrode assembly (10). The cover portion (51) may cover the said one side of the electrode assembly (10). The cover portion (51) may have a square plate shape, but the shape of the cover portion (51) is not particularly limited as long as it can partially cover the electrode assembly (10).

[0138] The outward-facing surface (51a) of the cover portion (51) may be provided to be exposed to the outside of the connection portion (40). Here, the outward-facing surface (51a) may be a surface among the outer surfaces of the cover portion (51) that faces the outside of the electrode assembly (10). At this time, the outward-facing surface (51a) of the cover portion (51) may be positioned on the same plane as one surface of the connection portion (40). For example, the outward-facing surface (51a) may be positioned on the same plane as one surface of the coupling portion (41) of the connection portion (40) described later. Of course, the outward-facing surface (51a) may be located further outward than the one surface of the coupling portion (41).

[0139] With this configuration, space utilization can be improved when arranging multiple secondary batteries (3). Here, the outward-facing surface (51a) may refer to a surface facing forward (positive direction of the X-axis) from the cover portion (51) based on FIG. 6, and one surface of the coupling portion (41) may refer to an end surface facing forward (positive direction of the X-axis).

[0140] The extension portion (54) of the cover portion (50) may extend toward the electrode assembly (10). That is, the extension portion (54) may extend from the cover portion (51) toward the electrode assembly (10). For example, the extension portion (54) may be provided such that the end surface (54c) on the side of the electrode assembly (10) is exposed to the inside of the connection portion (40). In this case, the extension portion (54) may extend from the edge of the cover portion (51).

[0141] Referring to FIGS. 5 and 6, the extension portion (54) of the cover portion (50) may be formed in multiple numbers. Here, at least one extension portion (54) may be provided such that the end surface (54c) on the side of the electrode assembly (10) is exposed to the inside of the connection portion (40). For example, among the multiple extension portions (54) extending from the cover portion (51) toward the electrode assembly (10), some may be embedded in the connection portion (40), and other portions may be exposed to the inside of the connection portion (40).

[0142] However, in the first embodiment of the present invention, the case in which all of the plurality of extension parts (54) are exposed to the inside of the connecting part (40) is described as an example. For example, the plurality of extension parts (54) may include first to fourth extension parts (55 to 58).

[0143] Referring to FIGS. 5 and 6, the first and second extension portions (55, 56) may extend parallel to each other from both sides in the width direction (Y-axis direction) of the cover portion (51). The first extension portion (55) and the second extension portion (56) may be arranged at a predetermined distance in the width direction. At this time, the width direction (Y-axis direction) may be a direction perpendicular to the direction in which the electrode and separator are stacked (Z-axis direction). The first and second extension portions (55, 56) may have a partition (or plate) shape having a predetermined thickness.

[0144] The third and fourth extension portions (57, 58) may extend parallel to each other from both sides in the height direction (Z-axis direction) of the cover portion (51). The third extension portion (57) and the fourth extension portion (58) may be arranged at a predetermined distance in the height direction. At this time, the height direction (Z-axis direction) may be a direction parallel to the direction (Z-axis direction) in which the electrode and separator are stacked. The third and fourth extension portions (57, 58) may have a partition (or plate) shape having a predetermined thickness.

[0145] At this time, the first to fourth extension portions (55 to 58) can be connected to each other. As a result, when viewed in the longitudinal direction (X-axis direction) of the electrode assembly (10), the first to fourth extension portions (55 to 58) can have an overall ring shape. In other words, the first to fourth extension portions (55 to 58) can have a ring shape that follows the circumferential direction of the electrode assembly (10). At this time, the ring shape may be a shape viewed in the longitudinal direction (X-axis direction) of the electrode assembly (10).

[0146] Referring to FIG. 5, the end surface (54c) of the extension portion (54) exposed to the inside of the connection portion (40) can be positioned at a predetermined distance from the electrode assembly (10). Thus, damage to the electrode assembly (10) caused by the extension portion (54) can be prevented.

[0147] Meanwhile, in this embodiment, the extension portion (54) is described as being composed of the first to fourth extension portions (55 to 58). However, if necessary, the extension portion (54) may be configured to include only some of the first to fourth extension portions (55 to 58). For example, the extension portion (54) may be composed of the first and second extension portions (55, 56) and configured to be open in the height direction (Z-axis direction).

[0148] Referring to FIGS. 2 to 6, the extension portion (54) can be embedded in the connection portion (40) in a manner that fits into a groove formed in the connection portion (40). The connection portion (40) and the cover portion (50) can be combined by fitting a part of the cover portion (51) and the extension portion (54) into the connection portion (40) (see FIGS. 2 to 6). At this time, the connection portion (40) and the extension portion (54) can be bonded to each other by heat sealing. Additionally, the connection portion (40) and the extension portion (54) can be bonded to each other through an adhesive applied between them. Here, the type and application form of the adhesive for bonding the connection portion (40) and the extension portion (54) can vary. For example, the adhesive may be composed of a material with relatively high hydrophobicity.

[0149] When the connecting part (40) and the extension part (54) are bonded by sealing, the connecting part (40) may include a resin material that is adhesive by heat. That is, the resin material of the connecting part (40) that is adhesive by heat melts, and the connecting part (40) can be bonded to the extension part (54) by pressure. Through this, the connecting part (40) and the cover part (50) can be combined.

[0150] Meanwhile, although not described in detail in the present invention, the cap (30) may further include an electrolyte injection port for injecting an electrolyte or a gas discharge port for discharging gas during a degassing process.

[0151] According to the first embodiment of the present invention, the cap (30) of the secondary battery (3) may cover the electrode assembly (10) with a connecting portion (40) and a cover portion (50) in which at least a portion is embedded in the connecting portion (40). Depending on the material of the connecting portion (40), moisture or the like from the outside of the connecting portion (40) may penetrate into the inside of the connecting portion (40). The penetration of moisture may cause defects in the secondary battery (3).

[0152] According to the first embodiment of the present invention, the cap (30) of the secondary battery (3) may cover the electrode assembly (10) together with the connecting portion (40) by including a cover portion (50) containing a material with excellent water resistance, such as metal. Accordingly, the cap (30) may reduce the surface area of ​​the connecting portion (40) through which moisture can penetrate. Additionally, since at least a portion of the cover portion (50) is arranged in a shape embedded in the connecting portion (40), it may be difficult for moisture to penetrate between the cover portion (50) and the connecting portion (40). Therefore, the secondary battery (3) according to the first embodiment of the present invention can reduce the amount of moisture penetrating into the interior, thereby reducing the phenomenon where problems occur in the performance of the secondary battery (3).

[0153] In addition, the cap (30) of the secondary battery (3) according to the first embodiment of the present invention may be arranged such that the extended portion (54) of the cover portion (50) is embedded in the connecting portion (40). Accordingly, since the connecting portion (40) restricts the movement of the cover portion (50) and prevents the cover portion (50) from detaching, the structural stability of the secondary battery (3) can be improved.

[0154] In addition, the cap (30) of the secondary battery (3) includes a terminal portion (60), so it can be efficiently electrically connected to the outside. Furthermore, the terminal portion (60) can be connected to various types of electrode assemblies (10) through variations in shape and arrangement, and can be efficiently connected to electrode tabs (11) even when the number of electrode tabs (11) increases.

[0155] Although not described in detail in this embodiment, the cap (30) may further include a gas discharge member (not shown) for discharging gas inside the secondary battery (3) or a venting member (not shown) for inducing venting to occur in a specific direction.

[0156]

[0157] Embodiment 2

[0158] FIG. 7 is a perspective view of a secondary battery according to a second embodiment of the present invention viewed from above. FIG. 8 is an exploded perspective view of the secondary battery shown in FIG. 7. FIG. 9 is a drawing showing a part of a cross-sectional view along C-C' of FIG. 7.

[0159] In the following, a detailed description of the configuration identical to that of the secondary battery (3) (shown in FIG. 2) according to the first embodiment of the present invention is omitted, and the differences between the first embodiment and the second embodiment are described in detail.

[0160] Referring to FIGS. 7 to 9, the secondary battery (103) according to the second embodiment of the present invention may differ from the secondary battery (3) (shown in FIG. 2) according to the first embodiment in terms of the shape of the connecting part (140), the shape of the terminal part (160), the presence or absence of a bus bar (170), and the method of combining the configuration. The secondary battery (103) according to the second embodiment of the present invention may include an electrode assembly (10), an outer film (20), and a cap (130).

[0161] In this embodiment, the outer film (20) of the secondary battery (103) may have a shape in which a sheet or film is rolled along the side of the electrode assembly (10). For example, the outer film (20) may be arranged to wrap around the side of the electrode assembly (10). At this time, the outer film (20) may be arranged to wrap around the electrode assembly (10) while the one end and the other end meet each other. Regarding the shape in which the one end and the other end of the outer film (20) meet each other, one side of the one end and one side of the other end may be joined so that they overlap and come into contact with each other (see FIG. 7). This is merely an example, and the shape in which the one end and the other end are joined to form a space for the outer film (20) to accommodate the electrode assembly (10) may vary.

[0162] Referring to FIGS. 7 through 9, the cap (130) of the secondary battery (103) may include a connecting portion (140), a cover portion (50), and a terminal portion (160). The connecting portion (140) of the cap (130) may be combined with an outer film (20), and the cover portion (50) of the cap (130) may be combined with the connecting portion (140) so that a portion thereof is exposed to the outside of the connecting portion (140). The terminal portion (160) of the cap (130) may be positioned to penetrate the connecting portion (140) and the cover portion (50). Additionally, one end and the other end of the terminal portion (160) may be exposed to the outside and inside of the connecting portion (140).

[0163] Below, each component of the cap (130) is described in more detail.

[0164] In this embodiment, the cover portion (50) may be configured in the same way as the cover portion of the secondary battery according to the first embodiment. The cover portion (50) may include a cover portion (51) and an extension portion (54). One side of the cover portion (51) may be positioned to be exposed to the outside of the connection portion (140). Hereinafter, the one side is named the outward-facing surface (51a), and the surface facing the outward-facing surface (51a) is named the inward-facing surface (51b). The inward-facing surface (51b) may be a surface facing the electrode assembly (10).

[0165] In this embodiment, the extension portion (54) may be embedded in the connecting portion (140). For example, one end of the extension portion (54) may not be exposed to the inside of the connecting portion (140). To this end, the connecting portion (140) may include an end portion (145) provided at the end of the extension portion (54) to connect the extension portion side portion (44) and the connecting portion (41). The end portion (145) may be a portion that covers the end surface (54c) of the extension portion (54).

[0166] This structure ensures not only the structural stability of the cap (30) but also the stability of the joint portion (41) where the cap (30) and the outer film (20) are sealed. For example, the advantage of being able to control the venting direction can be expected. If the extension portion (54) is completely embedded by the connecting portion (140) and there is no exposed portion on the inside, the possibility of the joint portion (41) being separated from the extension portion (54) of the cover portion (50) can be eliminated.

[0167] For example, in a situation where the internal pressure of the secondary battery (3) rises rapidly and the internal gas is ejected explosively, or where flames are ejected to the outside due to a fire, since there are no cracks in the direction of the cap (30) through which flames or gas can be ejected, it is possible to control the vent so that it does not occur in the direction of the cap (30). Therefore, there is an advantage in that the heat transfer phenomenon that may occur due to the vent occurring in the direction of the cap (30) while assembled into a battery pack can be resolved.

[0168] In this embodiment, the end portion (145) may have a ring shape corresponding to the shape of the extension portion (54). In this case, the ring shape may be the shape viewed in the extension direction (X-axis direction) of the electrode assembly (10).

[0169] Meanwhile, in this embodiment, the end portion (145) can be connected to the connecting portion (41) and the extension portion (44), respectively. As a result, the extension portion (54) can be completely buried by the connecting portion (140). With this configuration, moisture penetration into the space in which the electrode assembly (10) is accommodated can be further suppressed. This is because a certain gap through which moisture can penetrate may occur in the joint portion between the outer surface (54a) of the extension portion (54) and the connecting portion (41), and this gap is blocked by the end portion (145).

[0170] In addition, with the above configuration, the discharge of gas or flame can be directed toward the outer film (20) in abnormal situations such as an increase in internal pressure or an explosion. This is because the gap between the outer surface (54a) of the extension part (54) and the joining part (41) is blocked by the end part (145), thereby suppressing the discharge of gas or flame through the cap (130).

[0171] As such, in the second embodiment of the present invention, the extension portion (54) is arranged in a form that is entirely embedded in the connection portion (140), so the structural stability of the cap (30) can be improved, and the direction of gas or flame discharge can be effectively controlled. In addition, there is no protruding shape on the other surface of the connection portion (140) facing the electrode assembly. A part of the busbar (170), which will be described later, can be arranged in this portion.

[0172] Regarding the structure of the terminal portion (160) of the cap (130), the terminal portion (160) may include a body portion (161), an outer portion (162), and an inner portion (163). For example, the outer portion (162) may be connected to one end of the body portion (161), and the inner portion (163) may be connected to the other end.

[0173] The body portion (161) of the terminal portion (160) may be positioned to penetrate the connection portion (140) and the cover portion (50). That is, the outer circumference of the body portion (161) may come into contact with the connection portion (140) and the cover portion (50). A predetermined gasket may be provided on the outer circumference of the body portion (161) to prevent leakage of electrolyte.

[0174] The outer portion (162) of the terminal portion (160) may be exposed to the outside of the connection portion (140). Thus, when the secondary battery (103) is electrically connected to the outside to provide electrical energy, the outer portion (162) may be connected to the outside. The inner portion (163) of the terminal portion (160) may be exposed to the inside of the connection portion (140). Thus, the inner portion (163) may be electrically connected to the electrode assembly (10).

[0175] Meanwhile, the outer portion (162) and inner portion (163) of the terminal portion (160) according to the second embodiment of the present invention may be formed with a cross-sectional area larger than that of the body portion (161). Referring to FIG. 9, the terminal portion (160) can be fitted into the connecting portion (140) and the cover portion (50) by means of the outer portion (162) and the inner portion (163). Accordingly, separation of the terminal portion (160) can be prevented, thereby improving the structural stability of the cap (130).

[0176] According to the second embodiment of the present invention, the body portion (161), the outer portion (162), and the inner portion (163) of the terminal portion (160) may each have a roughly cylindrical shape. For example, the body portion (161), the outer portion (162), and the inner portion (163) may have a shape in which the cross-section is roughly circular. This is merely one example, and the body portion (161), the outer portion (162), and the inner portion (163) may have a shape in which the cross-section has a different shape.

[0177] As previously explained, the inner portion (163) of the terminal portion (160) extending to the inner side of the connection portion (140) can be electrically connected to the electrode assembly (10). Here, the electrical connection may include both a direct connection between the inner portion (163) and the electrode assembly (10) and an indirect connection through another electrically conductive member.

[0178] When the inner portion (163) and the electrode assembly (10) are directly connected, the electrode tab (11) of the electrode assembly (10) may be connected to the inner portion (163). Additionally, when the inner portion (163) and the electrode assembly (10) are indirectly connected, the secondary battery (103) may include a busbar (170) as an example of an electrically conductive member serving as an intermediary.

[0179] The busbar (170) is positioned between the connecting portion (140) and the electrode assembly (10) to connect the inner portion (163), which is exposed to the inside of the connecting portion (140), with the electrode assembly (10). The busbar (170) may be made of metal to be electrically conductive. Additionally, the busbar (170) may be positioned in various shapes depending on the extended length of the inner portion (163).

[0180] As an example of a configuration for efficient placement, a busbar (170) according to a second embodiment of the present invention may include a first metal part (171), a second metal part (172), a third metal part (173), and a fourth metal part (174).

[0181] Referring to FIG. 9, the first metal part (171) may come into contact with the connecting part (140) and the inner part (163). One side of the first metal part (171) facing the connecting part (140) may be positioned to come into contact with the connecting part (140). Additionally, the other side of the first metal part (171) facing the inner part (163) may be positioned to come into contact with the inner part (163). In this regard, the first metal part (171) may have a roughly plate shape and a hole may be formed in the center. The body part (151) of the terminal part (160) may pass through the hole of the first metal part (171), and the other side of the first metal part (171) facing the inner part (163) may come into contact with the inner part (163). For example, the first metal part (171) of the bus bar (170) may be positioned to catch on the inner part (163) so that movement toward the electrode assembly (10) is restricted by the inner part (163). Thus, effective fixation of the bus bar (170) is possible. Meanwhile, the terminal part (160) includes a metal material, and the inner part (163) of the terminal part (160) and the first metal part (171) may be joined together through welding.

[0182] The second metal part (172) may extend from the first metal part (171) toward the electrode assembly (10). At this time, the second metal part (172) may extend in a direction approximately orthogonal to the extension direction of the first metal part (171). Additionally, one surface of the second metal part (172) facing the connecting part (140) may come into contact with the connecting part (140).

[0183] The third metal part (173) may extend from the second metal part (172) toward the outer film (20). At this time, the third metal part (173) may extend in a direction approximately orthogonal to the extension direction of the second metal part (172). For example, the third metal part (173) may extend in a direction away from the inner part (163). Additionally, one surface of the third metal part (173) facing the connecting part (140) may come into contact with the connecting part (140).

[0184] The fourth metal part (174) may extend from the third metal part (173) toward the electrode assembly (10). Additionally, one side of the fourth metal part (174) facing the outer film (20) may come into contact with the outer film (20).

[0185] Meanwhile, one end of the fourth metal part (174) can be connected to the electrode assembly (10). For example, one end of the fourth metal part (174) can be connected to the electrode tab (11) of the electrode assembly (10). In this regard, the second metal part (172), the third metal part (173), and the fourth metal part (174) can be formed as a pair. Here, a plurality of electrode tabs (11) of the electrode assembly (10) can each be connected to a relatively nearby fourth metal part (174). Thus, even if the number of electrode tabs (11) increases as the secondary battery (103) includes a plurality of electrode assemblies (10), the fourth metal part (174) can be efficiently connected to the electrode tabs (11).

[0186] According to the second embodiment of the present invention, the busbar (170) may be positioned in contact with the outer film (20) or the cap (130). Thus, the structural stability of the secondary battery (103) can be improved. Additionally, since the busbar (170) includes a first metal part (171), a second metal part (172), a third metal part (173), and a fourth metal part (174), it can be applied in various forms depending on the number, arrangement, shape, etc. of the electrode assembly (10).

[0187] The shape of the busbar (170) described in the present invention is merely one example. Accordingly, the shape and arrangement of the busbar (170) may vary.

[0188]

[0189] Embodiment 3

[0190] FIG. 10 is a partial cross-sectional view of a secondary battery according to a third embodiment of the present invention, cut along C-C' of FIG. 7.

[0191] The electrode assembly, outer film, cap cover portion, terminal portion, and bus bar of the secondary battery (203) according to the third embodiment of the present invention may be configured to be identical or similar to the electrode assembly, outer film, cap cover portion, terminal portion, and bus bar of the secondary battery (103) (shown in FIGS. 7 to 9) according to the second embodiment of the present invention.

[0192] Referring to FIG. 10, in a secondary battery (203) according to a third embodiment of the present invention, the connecting portion (240) of the cap (230) may further include an outer portion (242). The outer portion (242) may be configured to cover an outward-facing surface (51a) facing the outside of the electrode assembly (10) among the outer surfaces of the cover portion (51). As a result, the outward-facing surface (51a) and the inward-facing surface (51b) of the cover portion (51) may be covered by the outer portion (242) and the inner portion (43), respectively. That is, the cover portion (51) may be entirely embedded in the connecting portion (240).

[0193] In this embodiment, the outer portion (242) may have a plate shape that covers the entire outward surface (51a). Through this, the cover portion (50) can be protected from external impact and contamination. However, the shape of the outer portion (242) is not particularly limited as long as it can cover the outward surface (51a).

[0194] Meanwhile, in this embodiment, the edge portion of the outer portion (242) may be connected to the connecting portion (41). The outer portion (242) may be provided integrally with the connecting portion (41). The outer portion (242) may be made of the same material as the connecting portion (41).

[0195] Through this, the cover portion (50) can be completely surrounded by the connecting portion (240), so the bonding between the connecting portion (240) and the cover portion (50) can be improved. In addition, since the gap between the connecting portion (41) and the outer surface (54a) of the extension portion (54) is blocked by the outer portion (242), moisture penetration into the space in which the electrode assembly (10) is housed can be very effectively suppressed.

[0196] Meanwhile, in this embodiment, the body portion (161) of the terminal portion (160) may pass through the cover portion (50) and the inner portion (43) and penetrate the outer portion (242). The outer portion (162) of the terminal portion (160) may be provided at the end of the body portion (161). Here, the end of the body portion (161) may be a portion facing the outer portion (242).

[0197] At this time, the outer part (162) may have a larger cross-sectional area than the body part (161). As a result, since one side of the outer part (162) may be caught on the outer part (242), the movement (or detachment) of the terminal part (160) may be restricted.

[0198] In this embodiment, since the outward surface (51a) of the cover portion (50) is covered by the outer portion (242), not only is durability and bonding improved, but insulation between the terminal portion (160) and other components can also be improved. Additionally, in the event of thermal runaway, heat transfer can be suppressed by the outer portion (242).

[0199] Furthermore, in this embodiment, since the cover portion (50) made of a metal material is surrounded by the connecting portion (240), the cap (230) can be easily manufactured by an insert injection molding process. Through this, the productivity of the secondary battery can be improved, the manufacturing process can be simplified, and the manufacturing cost can be reduced.

[0200]

[0201] Embodiment 4

[0202] FIG. 11 is a partial cross-sectional view of a secondary battery according to the fourth embodiment of the present invention, cut along C-C' of FIG. 7. Referring to FIG. 11, the electrode assembly (10), outer film (20), cover portion (50), terminal portion (160), and bus bar (170) of the secondary battery (303) according to the fourth embodiment of the present invention may be configured to be identical or similar to the electrode assembly, outer film, cover portion, terminal portion, and bus bar of the secondary battery according to the second embodiment.

[0203] At this time, the connecting portion (340) in the cap (330) of the secondary battery (303) according to the fourth embodiment of the present invention may include a connecting portion (41). In addition, the outward surface (51a) and inward surface (51b) of the cover portion (51) and the inner surface (54b) and end surface (54c) of the extension portion (54) may not be covered by the connecting portion (340).

[0204] In other words, the outward surface (51a), the inward surface (51b), the inner surface (54b), and the end surface (54c) may be exposed. Of course, if necessary, the inward surface (51b), the inner surface (54b), and / or the end surface (54c) may be covered at least partially by the busbar (170).

[0205] In this embodiment, the connecting portion (340) may have a ring shape that surrounds the outer surface (54a) (or outer circumference) of the extension portion (54). As such, in this embodiment, the connecting portion (340) can be simply and compactly constructed with only the connecting portion (41). Accordingly, the secondary battery (303) can achieve rigidity reinforcement by the cover portion (50) while being lightweight.

[0206]

[0207] connection part

[0208] Variations of the connecting portion (40, 140, 240, 340) according to embodiments 1 to 4 of the present invention, for example, variations of the connecting portion (41) and the corner edge (45) of the connecting portion (40), are described in more detail. The description of the variations may be applicable to all embodiments 1 to 4 according to the present invention and may include variations possible to those skilled in the art.

[0209]

[0210] Example of modification of the joint part

[0211] First, referring to FIG. 13, the connecting portion (41) of the connecting portion (340) according to embodiment 4 of the present invention may, as a first variation, include a first layer (41a) having an outer surface that allows connection with the inner surface of the outer film (20) and an inner surface that allows connection with the outer surface of the cover portion (50).

[0212] The first resin included in the first layer (41a) above may be a material that facilitates the bonding of the cover portion (50) and the exterior film (20), and, for example, may be characterized by including a resin having a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C.

[0213] The connection portion (40, 340) between the cover portion (50) and the exterior film (20) can play an important role in maintaining airtightness when sealing the cover portion (50) and the exterior film (20). In order to prevent unsealed portions from occurring when sealing this portion, the radius of curvature of the corner edge is controlled as described above, but the success or failure of the sealing may also depend on what material is applied to the first layer (41a) applied to the joint portion (41) of the connection portion (40, 340). The first layer (41a) includes a first resin, and the melt flow rate of the first resin may be 4 g / 10 min to 14 g / min. Preferably, it may be 5 g / 10 min or more, or 6 g / 10 min or more, and may also be 13 g / 10 min or less, or 12 g / 10 min or less.

[0214] The melt flow rate is a measure of how good the flowability of the resin is in the molten state. During sealing, the resin melts and heat-fuses to the contact surface; at this time, performance such as sealing strength and whether unsealed areas occur may vary depending on the melt flow rate of the resin. Sealing the case of a secondary battery is a process of applying high heat for a very short period of time, and since it melts and solidifies instantaneously, the melt flow characteristics can affect the sealing effect. Accordingly, it may be necessary to select a first resin having such a melt flow rate and apply it to the first layer.

[0215] Also, the first resin has a melting point (T mIt may include a resin having a temperature of 135°C to 150°C and a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C. When the first resin having the above properties is applied to the first layer (41a), it has excellent heat resistance and can withstand heat fusion at high temperatures without change in appearance, thereby securing excellent sealing strength and having excellent durability in response to the increase in internal pressure caused by gas generated inside the secondary battery.

[0216] For example, the first resin may include a modified polyolefin-based resin. The first resin may be included in the first layer in an amount exceeding 50 weight%, for example, 70 weight% or more, 80 weight% or more, or 90 weight% or more, and may be applied as the first resin alone, and when mixed, the remainder may be a suitable resin such as another polyolefin-based resin.

[0217] The above-mentioned modified polyolefin resin may be modified by an acid or a siloxane, for example, by an acid, and more preferably may be a polyolefin copolymerized with a monomer containing acrylic acid or post-treated with an acid. For example, it may be acid-modified polypropylene or acid-modified polyethylene, plasma-treated polypropylene or polyethylene may be applied, or it may include acid-modified polypropylene. When such a modified polyolefin is applied, the functional groups introduced by the modification improve the bonding strength with the surface of the metal, which may be more advantageous for the adhesion between the metal and the resin. Considering that a metal may be applied as the material of the cover portion (50), the resin described above may be applied as the connecting portion (40).

[0218] Referring to FIG. 14, the connecting portion (41) of the connecting portion (340) may, as a second variation, include a first layer (41a) that includes a first resin and allows connection with the outer surface of the cover portion (50), and a second layer (41b) that includes a second resin, is laminated on the outer surface of the first layer, and allows connection with the inner surface of the exterior film (20).

[0219] For example, the first resin included in the first layer (41a) is as described above, and the second resin included in the second layer (41b) may include a resin selected from the group consisting of a resin having a melting point (Tm) of 120°C to 145°C, a resin having a melting flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C, and a resin having a melting point (Tm) of 120°C to 145°C and a melting flow rate (MFR) of 5 g / 10 min to 18 g / 10 min at 230°C.

[0220] As another example, the first resin and the second resin may satisfy at least one selected from the relationship of Formula 1 and the relationship of Formula 2 below.

[0221] [Equation 1]

[0222] Tm2> Tm1

[0223] In the above Equation 1, Tm1 is the melting point of the first resin and Tm2 is the melting point of the second resin, and the unit is °C.

[0224] [Equation 2]

[0225] MFR2> MFR1

[0226] In the above Equation 2, MFR1 is the melt flow rate of the first resin and MFR2 is the melt flow rate of the second resin, and the unit is g / 10 min.

[0227] When the above-mentioned connecting part (340) is composed of a double layer, the bonding strength with the cover part (50) and the bonding strength with the exterior film (20) can be increased compared to when it is composed of a single layer, and thereby there is an advantage in that a higher sealing strength can be secured. For example, if a resin with a higher melting point or a higher melting flow rate than the first resin applied to the first layer (41a) is included as the second resin in the second layer (41b), the physical properties can be more similar to those of the exterior film (20), and as a result, not only can the sealing processability be improved, but the bonding strength by thermal fusion can also be expected, so that the sealing strength can be increased and the durability against the resulting increase in internal pressure can be greatly improved.

[0228] For example, the first resin included in the first layer (41a) is as described above, and the second resin included in the second layer (41b) may be, for example, a polyolefin resin. The difference between the polyolefin resin and the first resin may be whether a modifier is introduced, and the second resin may be an unmodified polyolefin resin, and may include, for example, polypropylene or polyethylene, may be a homopolymer thereof, or may be a block copolymer or random copolymer copolymerized with a small amount of comonomer. In addition, when the second resin is included in the second layer, its content may be the same as when the first resin is included in the first layer.

[0229] The above polyolefin resin may be, for example, an unoriented polyolefin resin. The above unoriented polyolefin resin is manufactured by casting without stretching in a specific direction during the manufacturing or processing process, and compared to an oriented polyolefin resin, it is flexible, does not tear in a specific direction, and can be processed relatively easily. However, since the above connecting part (40) can be manufactured by insert injection together with the cover part (50) and a certain level of rigidity may be required due to the characteristics of the cap (30), an unoriented polyolefin resin and an oriented polyolefin resin can be appropriately selected by considering the physical properties of each resin according to the required degree.

[0230] Referring to FIG. 15, the connecting portion (41) of the connecting portion (340) may, in a third variation, include a first layer (41a) containing a first resin and allowing connection with the outer surface of the cover portion (50), a second layer (41b) containing a second resin and allowing connection with the inner surface of the outer film (20), and a third layer (41c) containing a third resin and disposed between the first layer (41a) and the second layer (41b).

[0231] For example, the first resin and the second resin are as described above, and the third resin may include a resin selected from the group consisting of a resin having a melting point (Tm) of 145°C to 170°C, a resin having a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 230°C, and a resin having a melting point (Tm) of 145°C to 170°C and a melt flow rate (MFR) of 2 g / 10 min to 4 g / 10 min at 230°C.

[0232] As another example, the first resin, second resin, and third resin may satisfy one or more selected from the relationship of Equation 3 and the relationship of Equation 4 below.

[0233] [Equation 3]

[0234] Tm3> Tm2> Tm1

[0235] In the above Equation 3, Tm1 is the melting point of the first resin, Tm2 is the melting point of the second resin, and Tm3 is the melting point of the third resin, with the unit being °C.

[0236] [Equation 4]

[0237] MFR2 > MFR1 > MFR3

[0238] In the above Equation 4, MFR1 is the melt flow rate of the first resin, MFR2 is the melt flow rate of the second resin, and MFR3 is the melt flow rate of the third resin, and the unit is g / 10 min.

[0239] When the above-mentioned connecting part (340) is composed of a triple layer, the third layer (41c) provided between the first layer (41a) and the second layer (41b) can be selected to have a higher melting point and a lower melting flow rate than the other layers. In this case, the deformation of the connecting part (40) due to heat can be minimized, thereby ensuring not only sealing strength but also insulation.

[0240] The third resin that can be applied to the third layer (41c) may be selected, for example, as a resin that satisfies the melting point and melt flow rate ranges within the same type of resin range as the second resin, and for example, the third resin may be selected as a homopolyolefin resin that is a single polymer.

[0241] According to embodiments 1 to 4 of the present invention, the connecting portion (40, 140, 240, 340) is provided on one side of the cover portion (50), and may include a connecting portion (242, 43, 44, 145) provided on at least one side of the cover portion (50) excluding the side of the cover portion (50) where the connecting portion (41) is provided (e.g., outer surface (54a)), such as an inner surface (54b), end surface (54c), outward surface (51a), and inward surface (51b)).

[0242] The connecting portion (242, 43, 44, 145) of the above connecting portion (40, 140, 240, 340) may include a first layer having an inner surface that allows connection with one side of the cover portion, and includes a first resin, as in the first modified example of the above connecting portion (41).

[0243] Additionally, the connecting portion (242, 43, 44, 145) of the connecting portion (40, 140, 240, 340) may include a first layer comprising a first resin and allowing connection with one side of the cover portion, and a second layer comprising a second resin and laminated on the outer surface of the first layer.

[0244] Additionally, the connecting portion (242, 43, 44, 145) of the connecting portion (40, 140, 240, 340) may include a first layer comprising a first resin and allowing connection with one surface of the cover portion, a second layer comprising a second resin and disposed at the outermost edge, and a third layer comprising a third resin and disposed between the first layer and the second layer.

[0245] More specifically, the connecting portion (40) further comprises a connecting portion covering one side of the cover portion (50) in addition to the connecting portion (41), and the connecting portion may include an inner portion (43) provided on the inward surface (51b) of the cover portion (51) of the cover portion (50) as in Embodiment 1 of FIG. 5, and an extension portion side portion (44) provided on the inner surface (54b) (or inner circumference surface) of the extension portion (54) of the cover portion (50). The inner portion (43) and the extension portion side portion (44) may be applied as variations identical or different from the first to third variations of the connecting portion (41) independently of the connecting portion (41), and in general, the same variations may be applied in that the cap (30) is manufactured by insert injection.

[0246] As another example, the connecting portion (40) further comprises a connecting portion covering one side of the cover portion (50) in addition to the connecting portion (41), and the connecting portion may include an inner portion (43) provided on the inward surface (51b) of the cover portion (51) of the cover portion (50) as in the embodiment 2 shown in FIG. 9, an extension portion side portion (44) provided on the inner surface (54b) (or inner circumference surface) of the extension portion (54) of the cover portion (50), and an end portion side portion (145) covering the end surface (54c) of the extension portion (54) of the cover portion (50). The inner part (43), the extension part (44), and the end part (145) may be applied as variations identical or different from the first to third variations of the joining part (41) independently of the joining part (41), and in general, the same variations may be applied in that the cap (30) is manufactured by insert injection.

[0247] As another example, the connecting portion (40) further comprises a connecting portion covering one side of the cover portion (50) in addition to the connecting portion (41), and the connecting portion may include an inner portion (43) provided on the inward surface (51b) of the cover portion (51) of the cover portion (50) as in the embodiment 3 shown in FIG. 10, an extension portion side portion (44) provided on the inner surface (54b) (or inner circumference surface) of the extension portion (54) of the cover portion (50), an end portion side portion (145) covering the end surface (54c) of the extension portion (54) of the cover portion (50), and an outer portion (242) covering the outward surface (51a) facing the outside of the electrode assembly (10) among the outer surfaces of the cover portion (51) of the cover portion (50). The inner part (43), the extension part (44), the end part (145), and the outer part (242) may be applied as variations identical or different from the first to third variations of the joining part (41) independently of the joining part (41), and in general, the same variations may be applied in that the cap (30) is manufactured by insert injection.

[0248]

[0249] Manufacturing method

[0250] A method for manufacturing a secondary battery according to embodiments 1 to 4 of the present specification will be described below with reference to FIGS. 2 to 4.

[0251] The above manufacturing method may include the step (S1) of assembling an electrode assembly (10) and an outer film (20) that wraps a part of the electrode assembly (10); and the step (S2) of sealing a cap (30) that wraps the remainder of the electrode assembly (10) by placing it in contact with the outer film (20).

[0252] At this time, the cap (30) may include, as described above, a cover portion (50) covering one side of the extension direction of the electrode assembly (10), a connecting portion (40) including a plurality of connecting portions (41) provided on the outer surface of the cover portion (50) and coupled with the outer film (20), and a terminal portion (60) at least a portion of which is exposed to the outside of the cover portion (50) and electrically connected to the electrode assembly (10), and the cap (30) may be positioned so that the connecting portion (41) of the connecting portion (40) and the outer film (20) come into contact.

[0253] In the above manufacturing method, the sealing between films of the outer film (20), the manufacturing of a cap including a cover portion (50), a connecting portion (40), and a terminal portion (60), and the accommodation of the electrode assembly (10) can be performed in the same manner as described in the description of each component, and since the operation and function are substantially the same, a detailed description is omitted.

[0254] The above S2 step may further include a step of injecting an electrolyte, and since this has also been described in the section regarding the specific description of the cover part (50), the details thereof are omitted.

[0255] In the above S2 step, the sealing may be influenced by the sealing pressure and temperature, as well as the melting point, melt flow rate, and radius of curvature of the corner edge (45) of the resin applied to the joint portion (41) of the connection portion (40). Since the characteristics of the resin applied here and the radius of curvature of the corner edge (45) have been described above, a detailed explanation thereof is omitted.

[0256] In the above S2 step, sealing can be performed at 200°C to 270°C, for example, at 210°C or higher, 220°C or higher, 230°C or higher, and also at 260°C or lower, or at 250°C or lower. In the case of satisfying the above range, appropriate heat supply is provided to match the melt flow rate of the first resin, second resin and / or third resin of the aforementioned connecting part (40), so that sufficient sealing strength can be secured.

[0257] In the above S2 step, the pressure may be 0.05 MPa to 1.20 MPa based on surface pressure, for example, 0.06 MPa or more, 0.10 MPa or more, 0.13 MPa or more, or 0.15 MPa or more, and may also be 1.00 MPa or less, 0.90 MPa or less, or 0.80 MPa or less. The above surface pressure may be defined as the ratio of the sum of the force pressing the sealing block and gravity with respect to the sealing area, and when the surface pressure is controlled to satisfy the above range, an improvement in pressure resistance performance can be expected by securing sufficient sealing strength.

[0258] The above secondary battery can be sealed with an outer film (20) and a bonding part (41) in the manner shown in FIGS. 11 and 12, and the aforementioned sealing temperature and pressure (surface pressure) can be considered when sealing using such a sealing block. As described above, while the conventional method of applying heat and pressure from both directions only considered the maximum amount of heat that the resin can withstand, the present method of applying heat and pressure from one direction can consider not only the maximum amount of heat that the material of the sealing part can withstand, but also the minimum amount of heat or pressure to secure an appropriate level of sealing strength.

[0259]

[0260] Examples and Comparative Examples

[0261] Hereinafter, embodiments and comparative examples regarding the connecting portion (41) and corner edge (45) of the connecting portion (340) are described so that a person skilled in the art to which the present invention pertains can easily implement it. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0262]

[0263] Example 1

[0264] An exterior film having a polyethylene terephthalate / nylon / aluminum alloy thin film / polypropylene film structure was prepared by laminating a polyethylene terephthalate (PET) film with a width of 266 mm, a length of 50 m, and a thickness of 12 μm and a nylon film with a width of 266 mm, a length of 50 m, and a thickness of 25 μm on one side of an aluminum alloy thin film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm on the other side, and laminating a polypropylene film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm on the other side. Here, the polyethylene terephthalate film and the nylon film are the substrate layer, the aluminum alloy thin film is the gas barrier layer, and the polypropylene film is the sealant layer.

[0265] Next, the joint portion (41) of the cover portion (50) and the connecting portion (40) having the shape as in Fig. 5, etc., was prepared by insert injection using an aluminum metal plate and a polypropylene resin, respectively, having a radius of curvature and a melt flow rate (MFR) as described in Table 1 below.

[0266] An electrode assembly was prepared by simulating the assembly of a negative electrode, a positive electrode, and a porous polyethylene separator in a stacking manner, and after wrapping it with the outer film (20), a secondary battery of the form shown in FIG. 2 was manufactured using a cap (30) including a cover part (50), a connecting part (40), and a terminal part (60). At this time, the sealing of the joint part (41) of the outer film (20) and the connecting part (40) was performed for 5 seconds under conditions of 240°C and 0.6 MPa.

[0267]

[0268] Examples 2 and 3, Comparative Examples 1 to 3

[0269] A secondary battery was manufactured using the same method as in Example 1 above, except for the secondary battery specifications and sealing specifications listed in Table 1.

[0270]

[0271] Experimental Example 1: Sealing Performance Evaluation

[0272] For the above-mentioned manufactured secondary battery, an external appearance evaluation was conducted to determine whether the outer film of the sealed portion was damaged. Additionally, the entire manufactured secondary battery was submerged in a water-filled tank, and air was injected into the battery to check for the formation of bubbles in the sealed portion, thereby evaluating whether any unsealed portions were present. For each case, O was indicated if damage occurred or if bubbles formed, and X was indicated if the opposite was true.

[0273]

[0274] Rg (mm) Melt Flow Rate (MFR) (g / 10 min) Presence of Outer Film Damage Presence of Unsealed Area Example 10.18XX Example 21.012XX Example 31.56XX Comparative Example 10.0512OX Comparative Example 22.58XO Comparative Example 31.52.2XO

[0275] Referring to Table 1 above, it can be seen that in Examples 1 to 3, where a value between 0.1 mm and 1.5 mm was applied as the radius of curvature of the corner edge of the connection part, there was no film damage and no unsealed portion occurred. However, in Comparative Example 1, the radius of curvature was too small, so the edge was sharp and damaged the outer film, and in Comparative Example 2, the radius of curvature was too large, so heating and pressurization through proper sealing were not performed on the edge portion, resulting in an unsealed portion. Additionally, in the case of Comparative Example 3, although the radius of curvature was satisfied, it was found that there was a problem of an unsealed portion occurring because the melt flow rate was not satisfied.

[0276]

[0277] [Explanation of the symbol]

[0278] 1: Battery pack 2: Packaging

[0279] 3, 103, 203, 303: Secondary battery 10: Electrode assembly

[0280] 11: Electrode tab 20: Exterior film

[0281] 30, 130, 230, 330: Cap 40, 140, 240, 340: Connector

[0282] 41: Connecting part 41a: First layer

[0283] 41b: 2nd floor 41c: 3rd floor

[0284] 242: Outer part

[0285] 43: Medial part 44: Extension side part

[0286] 45: Corner edge

[0287] 145: End side part 50: Cover part

[0288] 51: Cover part 51a: Outward surface

[0289] 51b: Inward surface 54: Extension part

[0290] 54a: Outer 54b: Inner

[0291] 54c: End surface 54d: Cover edge

[0292] 55: First extension section 56: Second extension section

[0293] 57: Third extension section 58: Fourth extension section

[0294] 60, 160: Terminal section 161: Body section

[0295] 162: Lateral part 163: Medial part

[0296] 170: Busbar 171: First metal part

[0297] 172: Second metal part 173: Third metal part

[0298] 174: 4th metal part

[0299] 80: Ceiling block

[0300] Rg: Corner edge curvature radius

Claims

1. Electrode assembly extended in one direction; An outer film covering a portion of the electrode assembly; and It includes a cap that encloses the remainder of the electrode assembly, and The above cap is, A cover portion covering one side in the extension direction of the above electrode assembly; A connecting portion comprising a plurality of connecting portions provided on the outer surface of the above-mentioned cover portion and coupled with the above-mentioned exterior film; and It includes a terminal portion that is at least a portion of which is exposed to the outside of the cover portion and is electrically connected to the electrode assembly, and The joining portion of the above connecting part is, They are connected in a rounded manner at the points where they meet to form a corner edge, and the corner edge has a radius of curvature Rg of 0.1 mm to 1.5 mm, and It has an outer surface that allows bonding with the inner surface of the above-mentioned exterior film and an inner surface that allows bonding with the outer surface of the above-mentioned cover portion, and includes a first layer comprising a first resin. A secondary battery comprising a resin having a melt flow rate (MFR) of 4 g / 10 min to 14 g / 10 min at 230°C, wherein the first resin is a resin.

2. In Claim 1, The first resin above has a melting point (T m A secondary battery comprising a resin having a temperature of 135°C to 150°C and a melt flow rate (MFR) at 230°C of 4 g / 10 min to 14 g / 10 min.

3. In Claim 1, The above first resin comprises a modified polyolefin-based resin, in a secondary battery.

4. In Claim 1, The joining portion of the above connecting part is, A first layer comprising a first resin and allowing bonding with the outer surface of the cover portion, and A secondary battery comprising a second resin, a second layer laminated on the outer surface of the first layer and allowing bonding with the inner surface of the outer film.

5. In Claim 4, The above second resin has a melting point (T m A resin having a temperature of 120°C to 145°C, a resin having a melt flow rate (MFR) at 230°C of 5 g / 10 min to 18 g / 10 min, and a melting point (T m A secondary battery comprising a resin selected from the group consisting of resins having a temperature of 120°C to 145°C and a melt flow rate (MFR) at 230°C of 5 g / 10 min to 18 g / 10 min.

6. In Claim 4, The above first resin and second resin are, A secondary battery satisfying at least one selected from the relationship of Equation 1 below and the relationship of Equation 2 below: [Equation 1] T m2 > T m1 In Equation 1 above, T m1 is the melting point of the first resin, and T m2 is the melting point of the second resin, and the unit is °C, and [Equation 2] MFR2> MFR1 In the above Equation 2, MFR1 is the melt flow rate of the first resin and MFR2 is the melt flow rate of the second resin, and the unit is g / 10 min.

7. In Claim 4, The first resin above includes a modified polyolefin-based resin, and The above second resin comprises a non-oriented polyolefin-based resin, in a secondary battery.

8. In Claim 1, The outer periphery surface of the above cover portion extends in the periphery direction of the electrode assembly, and The above-mentioned coupling portion is a secondary battery provided on the outer circumference surface of the above-mentioned cover portion.

9. In Claim 1, The above cover part is, A cover portion having an outwardly facing surface facing the outside of the electrode assembly; and It includes an extension portion extending from the above cover portion toward the electrode assembly side, and The above-mentioned connecting portion is a secondary battery provided on the outer surface of the above-mentioned extension portion.

10. In Claim 9, The above cover portion has a plate shape, The above-mentioned extension portion is a secondary battery extending from the edge of the above-mentioned cover portion.

11. In Claim 9, A secondary battery in which the radius of curvature of a cover edge formed at a position corresponding to the corner edge on the cover portion is smaller than or equal to the radius of curvature of the corner edge.

12. In Claim 1, The above-mentioned exterior film has a certain flexibility to allow it to be bent, and is a secondary battery.

13. In Claim 1, The above connecting part is, A secondary battery comprising a connecting portion provided on the outer surface of the cover portion, excluding the outer surface of the cover portion on which the coupling portion is provided, and a connecting portion provided on at least one of the outer surfaces of the cover portion.

14. In Claim 13, The connecting part of the above connecting part is, A secondary battery comprising a first layer including a first resin, the first layer having an outer surface that allows bonding with the inner surface of the outer film and an inner surface that allows bonding with the outer surface of the cover portion.

15. In Claim 13, The connecting part of the above connecting part is, A first layer comprising a first resin and allowing bonding with the outer surface of the cover portion, and A secondary battery comprising a second resin, a second layer laminated on the outer surface of the first layer and allowing bonding with the inner surface of the outer film.

16. Secondary battery; and It includes a packaging that accommodates the above secondary battery, and The above secondary battery is, Electrode assembly extended in one direction; An outer film covering a portion of the electrode assembly; and It includes a cap that encloses the remainder of the electrode assembly, and The above cap is, A cover portion covering one side in the extension direction of the above electrode assembly; A connecting portion comprising a plurality of connecting portions provided on the outer surface of the above-mentioned cover portion and coupled with the above-mentioned exterior film; and It includes a terminal portion in which at least a portion is exposed to the outside of the cover portion and is electrically connected to the electrode assembly, and The joining portions of the above-mentioned connecting parts are connected in a rounded manner at the point where they meet to form corner edges, and The above corner edge is a battery pack having a radius of curvature Rg of 0.1 mm to 1.5 mm.

Images