secondary batteries

Abstract

The present invention relates to a secondary battery, comprising: an electrode assembly having an electrode tab; an exterior material having a receiving portion for receiving the electrode assembly; and an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the exterior material, wherein the exterior material further includes an exposure hole opened to expose a portion of the electrode lead to the outside of the exterior material, and the electrode lead includes an exposed portion exposed to the outside of the exterior material through the exposure hole and a non-exposed portion connected to the exposed portion and covered by the exterior material so as not to be exposed to the outside of the exterior material, and the exposed portion may include a protruding portion protruding toward the outside of the exterior material beyond the non-exposed portion.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0146377, filed November 4, 2022, Korean Patent Application No. 10-2022-0146378, filed November 4, 2022, Korean Patent Application No. 10-2022-0146379, filed November 4, 2022, and Korean Patent Application No. 10-2023-0150797, filed November 3, 2023, and all contents disclosed in the documents of these Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a secondary battery. [Background technology]

[0003] In general, secondary batteries refer to batteries that can be charged and discharged, unlike primary batteries that cannot be recharged, and are widely used in electronic devices such as mobile phones, laptops, and camcorders, as well as electric vehicles. In particular, lithium secondary batteries have a larger capacity and higher energy density than nickel-cadmium batteries or nickel-metal hydride batteries, and therefore their use is rapidly increasing.

[0004] Depending on the shape of the battery case, secondary batteries can be divided into cylindrical batteries and prismatic batteries in which an electrode assembly is housed in a cylindrical or prismatic metal case, and pouch-type batteries in which an electrode assembly is housed in a pouch-type case made of a laminate sheet.

[0005] FIG. 1 illustrates an example of a pouch-type secondary battery. The pouch-type secondary battery 1 includes an electrode assembly 2 formed by alternately stacking electrodes and separators, and a pouch-type exterior material 20 in which the electrode assembly 2 is housed. Electrode tabs 15 may be connected to the electrodes of the electrode assembly 2. The electrode tabs 15 may be welded to each other in predetermined areas and then connected to an electrode lead 17 by welding. The exterior material 20 includes a housing portion 21 for housing the electrode assembly 2. The housing portion 21 of the exterior material 20 may be formed as one or two recessed portions. FIG. 1 illustrates an example of the housing portion 21 formed as two recessed portions. A sealing portion 23 (terrace) is formed around the periphery of the housing portion 21 by sealing.

[0006] Meanwhile, secondary batteries must be protected from ignition or explosion even when the internal temperature or pressure rises suddenly. Failure to prevent this can lead to problems such as thermal runaway and thermal propagation. However, because conventional pouch-type secondary batteries typically form the sealing portion 23 by heat sealing, the sealing strength of the sealing portion 23 is not strong enough to prevent or delay ignition or explosion. Furthermore, because the electrode lead 17 passes through the sealing portion 23 and is exposed to the outside of the exterior material 20, the portion of the sealing portion 23 through which the electrode lead 17 passes may have weaker sealing strength than other portions.

[0007] In particular, there has been a recent need for a pouch-type battery that vents only at specific points when exposed to extremely high temperatures (e.g., 1,000°C).In conventional pouch-type batteries, sealing portion 23 is generally formed by heat sealing between resin layers (which may be layers made of polypropylene) of exterior material 20, but when exposed to extremely high temperatures, the resin layer of sealing portion 23 melts, causing venting at unintended points, making it difficult to meet the above-mentioned need. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a secondary battery that can prevent or delay the occurrence of fire or explosion in the secondary battery even if the internal temperature or pressure rises suddenly in an extremely high temperature state by ensuring sufficient sealing strength of the sealing part.

[0009] Another object of the present invention is to provide a secondary battery in which the sealing portion of the exterior material does not have a portion through which an electrode lead passes, so that a portion with relatively low sealing strength is not formed in the sealing portion, and unintended venting does not occur in the sealing portion even at very high temperatures.

[0010] Furthermore, an object of the present invention is to provide a secondary battery that can reduce the withstand voltage by forming a sealing area inside the exterior material that has a sealing strength lower than that of the sealing part, so that even if the temperature becomes very high and the internal pressure rises suddenly, the sealing area inside the exterior material (i.e., the intended point) will be destroyed before the sealing part is destroyed.

[0011] Another object of the present invention is to provide a secondary battery in which electrode leads disposed inside the exterior packaging can be easily electrically connected to other parts.

[0012] Another object of the present invention is to provide a secondary battery in which the exterior material is not damaged by the electrode leads disposed inside the exterior material during the formation of the sealing portion. [Means for solving the problem]

[0013] In one example, a secondary battery includes an electrode assembly having an electrode tab, an outer casing having a receiving portion for receiving the electrode assembly, and an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the outer casing, wherein the outer casing further includes an exposure hole opened to expose a portion of the electrode lead to the outside of the outer casing, and the electrode lead includes an exposed portion exposed to the outside of the outer casing through the exposure hole and a non-exposed portion connected to the exposed portion and covered by the outer casing so as not to be exposed to the outside of the outer casing, and the exposed portion may include a protruding portion protruding toward the outside of the outer casing beyond the non-exposed portion.

[0014] In another example, the protrusion can protrude from the unexposed portion by at least the outer surface of the facing.

[0015] In yet another example, the protrusion may be spaced a predetermined distance from the edge of the exposure hole.

[0016] In yet another example, the secondary battery may further include an insulating member disposed in an empty space defined by the separation for electrical insulation between the protrusion and the exterior material.

[0017] In yet another example, the exterior material further includes an exterior material sealing portion formed to at least partially enclose the accommodating portion and an exposure hole sealing portion formed to enclose the exposure hole, and the sealing ability of the exterior material sealing portion may be higher than the sealing ability of the exposure hole sealing portion.

[0018] In yet another example, the exterior material sealing portion may be formed by welding, and the exposure hole sealing portion may be formed by fusion.

[0019] In yet another example, the exterior material may further include a first exterior material having a first metal layer, a second exterior material arranged opposite the first exterior material to form the accommodating portion together with the first exterior material and having a second metal layer, an exterior material sealing portion that hermetically connects the first and second exterior materials and is formed to at least partially enclose the accommodating portion, and an exposure hole sealing portion that is formed to enclose the exposure hole in an exposure hole exterior material, which is the exterior material in which the exposure hole is formed, of the first and second exterior materials.

[0020] In yet another example, the exterior material sealing portion may be formed by welding the first metal layer and the second metal layer.

[0021] In yet another example, the first exterior material further includes a first resin layer arranged inside the first metal layer, and the second exterior material further includes a second resin layer arranged inside the second metal layer and facing the first resin layer, and the exterior material sealing portion can be formed by welding the first and second metal layers together in a state where the first and second metal layers are in direct contact without the first and second resin layers.

[0022] In yet another example, the first and second metal layers can include stainless steel.

[0023] In yet another example, the secondary battery further includes an insulating film disposed between the exposure hole sheath material and the electrode lead to enclose a portion of the electrode lead exposed through the exposure hole, and the exposure hole sealing portion may be formed by fusing the insulating film with a resin layer of the exposure hole sheath material disposed opposite the insulating film.

[0024] In yet another example, the exterior material sealing portion may be formed to entirely enclose the accommodating portion except for a portion where the first and second exterior materials are connected to each other, and the electrode lead may be disposed inside the exterior material without passing through the exterior material sealing portion.

[0025] In yet another example, the electrode lead may extend in a direction transverse to an extension direction of the electrode tab and be disposed inside the exterior material.

[0026] In yet another example, the receiving portion may include an electrode assembly receiving portion that receives the electrode assembly, and an electrode lead receiving portion that receives at least a portion of the electrode lead.

[0027] In yet another example, the electrode assembly receiving portion may be pre-formed into a shape for receiving the electrode assembly before the electrode assembly is received therein, and the electrode lead receiving portion may be pre-formed into a shape for receiving the electrode lead before the electrode lead is received therein.

[0028] In yet another example, the electrode lead may be configured to be electrically connected to an electrode lead of another secondary battery via the protrusion.

[0029] In yet another example, the secondary battery further includes an insulating film disposed between the exposed hole sheath material and the electrode lead so as to enclose a portion of the electrode lead exposed through the exposed hole, and a surface treatment having a large surface roughness is partially formed on the surface of the electrode lead, and the formation region of the surface treatment may include a region of the surface of the electrode lead facing the insulating film.

[0030] In yet another example, a secondary battery includes an electrode assembly having an electrode tab, an outer casing having a receiving portion for receiving the electrode assembly, and an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the outer casing, and the outer casing may further include an exposure hole opened to expose at least a portion of the electrode lead to the outside of the outer casing.

[0031] In yet another example, the electrode lead may be configured to be electrically connected to an electrode lead of another secondary battery through the exposure hole.

[0032] In yet another example, the electrode lead may extend in a direction transverse to the extension direction of the electrode tab and may be disposed inside the exterior material such that the electrode tab is located at a center of the electrode lead based on the transverse direction.

[0033] In yet another example, the electrode tab may be bent toward one side of the electrode assembly so that one side of the electrode lead faces the one side of the electrode assembly from which the electrode tab protrudes.

[0034] In yet another example, the electrode tab may be bent toward the outermost surface so that one side of the electrode lead faces the outermost surface of the electrode assembly based on the direction in which the electrodes and separators of the electrode assembly are stacked.

[0035] In yet another example, a secondary battery includes an electrode assembly having an electrode tab, an outer casing having a housing portion for housing the electrode assembly, and an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the outer casing, wherein the housing portion may include an electrode assembly housing portion for housing the electrode assembly and an electrode lead housing portion for housing at least a portion of the electrode lead.

[0036] In yet another example, the sheath may further include a sheath sealing portion formed to at least partially enclose the accommodating portion, and the electrode lead accommodating portion may be located on the sheath sealing portion to accommodate the electrode lead and may be disposed inside the sheath.

[0037] In yet another example, a side of the electrode lead accommodating portion facing the electrode assembly accommodating portion may be connected to the electrode assembly accommodating portion, and the remaining side of the electrode lead accommodating portion may be surrounded by the exterior material sealing portion.

[0038] In yet another example, the outer covering may further include an exposure hole that is opened to expose at least a portion of the electrode lead to the outside of the outer covering.

[0039] In yet another example, the electrode tab may be bent toward one side of the electrode assembly such that one side of the electrode lead faces the one side of the electrode assembly from which the electrode tab protrudes, and the exposure hole may be formed in one side of the exterior material facing the other side of the electrode lead by bending the electrode tab.

[0040] In yet another example, the electrode tab may be bent toward the outermost surface such that one side of the electrode lead faces the outermost surface of the electrode assembly based on a stacking direction of the electrodes and separators of the electrode assembly, and the exposure hole may be formed in one side of the exterior material facing the other side of the electrode lead by bending the electrode tab. [Effects of the Invention]

[0041] According to the present invention, the electrode lead is disposed inside the exterior material and exposed through the exposure hole in the exterior material, so that the edge of the exterior material can be entirely sealed without forming a portion within the edge of the exterior material through which the electrode lead passes, thereby achieving high overall sealing of the exterior material.

[0042] In addition, according to the present invention, by forming the exterior material sealing portion with a relatively strong sealing strength, it is possible to prevent or delay the occurrence of fire or explosion in the secondary battery even if the temperature or pressure resistance of the secondary battery rises suddenly, and by forming the exposure hole sealing portion with a relatively weak sealing strength, it is possible to induce the exposure hole sealing portion to break first when the internal pressure of the secondary battery rises suddenly, and to reduce the pressure resistance before the exterior material sealing portion breaks (by generating venting at the intended point).

[0043] Furthermore, according to the present invention, the exterior sealing portion is formed by welding between metal layers with very high melting points, so the sealing strength of the exterior sealing portion is very high, and the sealing portion will not break even at very high temperatures.

[0044] Furthermore, according to the present invention, since the electrode lead includes a protrusion that protrudes toward the outside of the exterior material, the electrode lead can be easily electrically connected to other parts.

[0045] Furthermore, according to the present invention, since the electrode lead is accommodated in the electrode lead accommodating portion, damage to the sheath due to the electrode lead does not occur during the process of sealing the edge of the sheath to form the sheath sealing portion. [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 1 is a diagram illustrating an example of a pouch-type secondary battery. [Figure 2] 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention. [Figure 3] FIG. 3 is an exploded perspective view of the secondary battery of FIG. 2. [Figure 4] 3 is a cross-sectional view illustrating the layer structure of an exterior material of the secondary battery of FIG. 2. FIG. [Figure 5] 3 is a cross-sectional view illustrating the layer structure of an exterior material of the secondary battery of FIG. 2. FIG. [Figure 6] FIG. 2 is a perspective view illustrating a secondary battery according to a second embodiment of the present invention. [Figure 7] FIG. 7 is an exploded perspective view of the secondary battery of FIG. 6. [Figure 8] FIG. 8 is an exploded perspective view illustrating a first modified example of the secondary battery of FIG. 7. [Figure 9] FIG. 8 is an exploded perspective view illustrating a second modification of the secondary battery of FIG. 7. [Figure 10] FIG. 8 is an exploded perspective view illustrating a third modified example of the secondary battery of FIG. 7. [Figure 11]FIG. 8 is an exploded perspective view illustrating a fourth modified example of the secondary battery of FIG. 7. [Figure 12] FIG. 10 is a perspective view illustrating a secondary battery according to a third embodiment of the present invention. [Figure 13] FIG. 13 is an exploded perspective view of the secondary battery of FIG. [Figure 14] FIG. 13 is a cross-sectional view taken along line AA' in FIG. [Figure 15] FIG. 10 is a cross-sectional view illustrating another embodiment including an insulating member. [Figure 16] FIG. 2 is a perspective view illustrating electrical connections of the secondary battery according to the first embodiment. [Figure 17] FIG. 2 is a perspective view illustrating electrical connections of the secondary battery according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0047]

[0023] The present invention will now be described in detail with reference to the accompanying drawings, in which:

[0024] A preferred embodiment of the present invention will be described in detail so that those skilled in the art can easily implement the present invention; however, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0048] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the description or related known technologies that may obscure the gist of the present invention are omitted, and when referring to components in each drawing in this specification, the same or similar reference symbols are used throughout the specification for the same or similar components.

[0049] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0050] [Embodiment 1] FIG. 2 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention, and FIG. 3 is an exploded perspective view of the secondary battery of FIG. 2. As illustrated in FIGS. 2 and 3, a secondary battery 100 according to this embodiment may include an electrode assembly 110, an outer casing 130, and an electrode lead 150. Hereinafter, the secondary battery 100 of this embodiment will be described in detail, mainly with reference to FIG. 3. For reference, the contents related to the secondary battery of the first embodiment are equally applicable to the secondary batteries of the second and third embodiments described below, unless they are inconsistent with each other.

[0051] [Overall structure of secondary battery] 3, the electrode assembly 110 may be formed by alternately stacking electrodes and separators. The electrodes may include a positive electrode and a negative electrode. The electrode assembly 110 may include an electrode tab 111. A separate electrode tab may be connected to the electrode, or a part of a current collector constituting the electrode may be used as the electrode tab.

[0052] The exterior material 130 may include a receiving portion 131 for receiving the electrode assembly 110. The exterior material 130 may be a pouch-type exterior material.

[0053] The outer casing 130 may be provided by sealing and joining first and second outer casings 141 and 142, which are arranged facing each other, when housed in the electrode assembly 110. The first and second outer casings 141 and 142 may be joined to each other while being provided separately, as shown in FIG. 3. In this case, the edges of the first and second outer casings 141 and 142 may be entirely sealed. This sealing may form an outer casing sealing portion 132 (see FIG. 2), which will be described later. Alternatively, the first and second outer casings may be formed as a part and a remainder of an outer casing that are arranged facing each other when one outer casing is folded, and then joined to each other (see FIG. 1). In this case, the remaining edges other than the part where the first and second outer casings are connected to each other, i.e., the part where one outer casing is folded, may be sealed. For reference, as described below, at least a portion of the electrode lead 150 can be disposed in the exterior material sealing portion 132, and when the edges of the first and second exterior materials 141, 142 are sealed with the electrode lead 150 sandwiched therebetween, a convex portion protruding outward due to the electrode lead 150, etc., can be formed on the first and second exterior materials 141, 142, as shown in FIG. 2.

[0054] The receiving portion 131 of the outer casing 130 may be pre-formed into a shape for receiving the electrode assembly 110 before the first and second outer casings 141 and 142 are combined. For example, the receiving portion 131 may include an electrode assembly receiving portion 131a that is pre-formed before the electrode assembly 110 is received therein. The receiving portion 131 may be formed by pressing one or all of the first and second outer casings 141 and 142, when they are film-shaped, with a punch to form an internal space, and then combining the outer casings 141 and 142 so that they face each other. FIG. 3 illustrates an example in which an internal space is formed in both the first and second outer casings 141 and 142. For reference, although FIGS. 2 and 3 illustrate a battery in which the receiving portion 131 is formed in both the first and second outer casings 141 and 142, the present embodiment may also be applied to a battery in which the receiving portion is formed in only one of the first and second outer casings. This also applies to other embodiments described below.

[0055] The electrode leads 150 may be connected to the electrode tabs 111 of the electrode assembly 110. The electrode leads 150 may be welded to the electrode tabs 111, which are welded to each other in predetermined areas, and connected to the electrode tabs 111.

[0056] The electrode lead 150 may be disposed inside the outer casing 130. In conventional secondary batteries, the electrode lead includes a portion disposed inside the outer casing and a portion extending outside the outer casing for electrical connection with other secondary batteries. However, the electrode lead 150 of the present embodiment does not need to include a portion extending outside the outer casing 130.

[0057] For example, the electrode lead 150 of this embodiment may be positioned inside the exterior material 130 so as not to deviate from the edge of the exterior material 130, as shown in Figures 2 and 3. If the first and second exterior materials 141, 142 have a portion where they are connected to each other, the exterior material sealing portion 132 may be formed to entirely surround the receiving portion 131 (see Figure 2) except for this connected portion (the secondary batteries of Figures 2 and 3 do not have such a portion), and the electrode lead 150 may be positioned inside the exterior material 130 without passing through the exterior material sealing portion 132 (although it may overlap with a portion).

[0058] For reference, the phrase "except for the portion where the first and second exterior materials are connected to each other" does not imply that the secondary battery of this embodiment "includes the portion where the first and second exterior materials are connected to each other." If there is no portion where the first and second exterior materials are connected to each other, there is no "excluded" portion, and therefore the exterior material sealing portion can be formed to enclose the entire accommodating portion.

[0059] Meanwhile, as shown in FIG. 2, the outer casing 130 of this embodiment may include an exposure hole 133 opened to expose at least a portion of the electrode lead 150 to the outside of the outer casing 130. The exposure hole 133 may be formed by cutting a portion of the outer casing 130 at a position corresponding to the electrode lead 150. For example, the exposure hole 133 may be formed by perforating the outer casing 130 during a process of forming the receiving portion 131 in the film-shaped outer casing 130, or before or after this process. FIG. 3 illustrates an example in which the exposure hole 133 is formed in each of the first and second outer casings 141 and 142. Even if the electrode lead 150 does not include a portion extending to the outside of the outer casing 130, the electrode lead 150 may be exposed to the outside of the outer casing 130 through the exposure hole 133.

[0060] In the secondary battery 100 of this embodiment, the electrode lead 150 is disposed inside the exterior casing 130 and exposed through the exposure hole 133 of the exterior casing 130, thereby enabling the entire edge of the exterior casing 130 to be sealed without forming a portion of the edge of the exterior casing 130 through which the electrode lead 150 passes. The portion of the edge of the exterior casing through which the electrode lead passes is a portion where the sealing between the first and second exterior casings may be weaker than other portions. Since the secondary battery 100 of this embodiment does not include such a portion, it is possible to form an overall high seal between the first and second exterior casings 141, 142. This can prevent or delay fire or explosion in the secondary battery 100 even if the temperature or pressure resistance of the secondary battery 100 suddenly increases, thereby preventing or delaying thermal runaway and thermal propagation.

[0061] [Exterior material sealing section and exposed hole sealing section] 2, the exterior material 130 may include an exterior material sealing portion 132 formed to at least partially enclose the receiving portion 131. The exterior material sealing portion 132 may be formed by sealing together the edges of the first and second exterior materials 141, 142.

[0062] As shown in FIGS. 2 and 3 , when the first and second exterior materials 141 and 142 are provided separately, an exterior material sealing portion 132 may be formed around the entire edge of the first and second exterior materials 141 and 142. In this case, the exterior material sealing portion 132 may be formed to completely enclose the receiving portion 131. When the first and second exterior materials are provided by folding a single exterior material, the exterior material sealing portion may be formed around the edge of the first and second exterior materials excluding the folded portion. The exterior material sealing portion may also be formed at the boundary between the folded and unfolded portions, i.e., at both ends of the folded portion. In this case, the exterior material sealing portion may be formed to enclose only a portion of the receiving portion. In this embodiment, the exterior material sealing portion 132 may be formed by welding, as described below.

[0063] As shown in FIG. 2, the exterior material 130 may include an exposure hole sealing portion 134 formed to enclose the exposure hole 133 (see the dotted line portion in the enlarged view of FIG. 17). Because the exposure hole 133 is a portion that breaks the sealing of the exterior material 130 by the exterior material sealing portion 132, sealing of the exposure hole 133 may be necessary, and the exposure hole sealing portion 134 may be responsible for this. The exposure hole 133 may be formed in one or both of the first and second exterior materials 141, 142, and the exposure hole sealing portion 134 may be formed in the exterior material in which the exposure hole 133 is formed (hereinafter referred to as the "exposure hole exterior material") of the first and second exterior materials 141, 142. The exposure hole sealing portion 134 of this embodiment may be formed by fusion, for example, heat sealing, as described below.

[0064] In the secondary battery 100 of this embodiment, the sealing property of the exterior material sealing portion 132 may be higher than the sealing property of the exposure hole sealing portion 134. In the secondary battery 100 of this embodiment, the exterior material sealing portion 132 is formed with a relatively strong sealing strength, thereby preventing or delaying the occurrence of fire or explosion in the secondary battery 100 even if the temperature or withstand pressure of the secondary battery 100 suddenly increases, and the exposure hole sealing portion 134 is formed with a relatively weak sealing strength, thereby inducing destruction of the exposure hole sealing portion 134 first (i.e., causing venting at an intended point) when the internal pressure of the secondary battery 100 suddenly increases, thereby reducing the withstand pressure before the exterior material sealing portion 132 is destroyed.

[0065] [Detailed structure of exterior sealing part] As described above, the exterior material 130 may include a first exterior material 141 and a second exterior material 142 disposed opposite the first exterior material 141 to form the receiving portion 131 together with the first exterior material 141. As shown in FIG. 4, the first and second exterior materials 141 and 142 may include first and second metal layers 141a and 142a, respectively. The exterior material sealing portion 132, which hermetically bonds the first and second exterior materials 141 and 142, may be formed by welding these metal layers 141a and 142a, as shown in FIG. 5. The welding may be laser welding. The first metal layer 141a may include aluminum. Alternatively, the first metal layer 141a may include stainless steel. For example, the first metal layer 141a may be a layer formed of stainless steel. The second metal layer 142a may also include aluminum or stainless steel.

[0066] Recently, there has been a demand for pouch-type batteries that vent only at specific points when exposed to extremely high temperatures (e.g., 1,000°C).In conventional pouch-type batteries, the exterior sealing portion is generally formed by heat sealing between the resin layers of the exterior material (which can be layers made of polypropylene), and when exposed to extremely high temperatures, the resin layer melts, causing venting at unintended points.

[0067] However, when the exterior sealing portion is formed by welding between metal layers (especially stainless steel layers) with a very high melting point, as in the secondary battery 100 of this embodiment, the sealing strength of the exterior sealing portion is very high, so the sealing portion will not be destroyed even at very high temperatures. Furthermore, if the exterior sealing portion is formed by welding along the entire edge of the exterior material except for the portion where the first and second exterior materials are connected to each other, the above-mentioned effects can be further enhanced. When the withstand voltage of the secondary battery becomes very high, venting can be induced through the exposed hole sealing portion, which has a lower sealing strength than the exterior sealing portion.

[0068] As shown in FIG. 4, the first exterior material 141 may include a first resin layer 141b disposed inside the first metal layer 141a. The first resin layer 141b may be a layer made of polypropylene (PP). This also applies to the second resin layer 142b described below. The first resin layer 141b is required to have high insulation properties and corrosion resistance, and the first resin layer 141b may be made of another resin that meets these requirements. The second exterior material 142 may also include a second resin layer 142b disposed inside the second metal layer 142a and facing the first resin layer 141b.

[0069] The exterior material sealing portion 132 can be formed by welding the first and second metal layers 141a, 142a in direct contact with each other without the first and second resin layers 141b, 142b, as shown in Fig. 5. When the metal layers are directly welded without a resin layer, the sealing strength of the exterior material sealing portion 132 can be further increased.

[0070] As shown in FIG. 4, the first exterior material 141 may include an outer resin layer 141c disposed on the outside of the first metal layer 141a. The second exterior material 142 may also include an outer resin layer 142c disposed on the outside of the second metal layer 142a. The outer resin layer may be a layer formed of polyethylene terephthalate (PET). The outer resin layer must protect the secondary battery and electrically insulate the secondary battery, and may be formed of other resins that meet these requirements. However, if the outer resin layer interferes with the formation of an exterior material sealing portion by welding the metal layer, the outer resin layer may not be provided at least in the area where the exterior material sealing portion is to be formed.

[0071] [Detailed structure of the exposed hole sealing part] As shown in FIG. 3, the secondary battery 100 of this embodiment may further include an insulating film 170 disposed between the electrode lead 150 and the exposed hole exterior materials 141 and 142, which are the exterior materials in which the exposed hole 133 is formed, among the first and second exterior materials 141 and 142. The insulating film 170 may be disposed only between the surface of the electrode lead 150 facing the exposed hole 133 and the exterior material in which the exposed hole 133 is formed. The insulating film 170 may be formed to enclose the portion of the electrode lead 150 exposed through the exposed hole 133 (see the enlarged view in FIG. 2). For example, the insulating film 170 may be formed in a rectangular frame shape. The exposed hole sealing portion 134 may be formed by fusing the insulating film 170 and a resin layer of the exposed hole exterior material 142 disposed opposite the insulating film 170, as shown in FIG. 2. In the case of the insulating film 170, one side can be sealed and coupled to the resin layer of the exposed hole sheath material 142 by fusion, and the other side can be sealed and coupled to the electrode lead 150 by fusion or adhesion.

[0072] A surface treatment portion 151 may be provided on the surface of the electrode lead 150 to improve bonding with the insulating film 170. This also applies to other embodiments / variations described later. The surface treatment portion 151 may be formed by subjecting the surface of the electrode lead 150 to mechanical treatment or chemical treatment. The mechanical treatment may be a laser irradiation method or a sandblasting method. The chemical treatment may be anodizing or etching. Such treatments may increase the surface roughness of the electrode lead 150.

[0073] 3, the surface treatment portion 151 may be formed only in a partial region of the surface of the electrode lead 150. The formation region of the surface treatment portion 151 may include a region of the surface of the electrode lead 150 that faces the insulating film 170. For example, the formation region of the surface treatment portion may be provided in a frame-shaped region that is formed when the insulating film 170 is projected onto the electrode lead 150. Alternatively, the formation region of the surface treatment portion 151 may be provided in a rectangular region that includes the region that is formed when the insulating film 170 is projected onto the electrode lead 150, as shown in FIG.

[0074] [Embodiment 2] FIG. 6 is a perspective view illustrating a secondary battery according to a second embodiment of the present invention, and FIG. 7 is an exploded perspective view of the secondary battery of FIG. 6. The secondary battery of the second embodiment differs from the secondary battery of the first embodiment in the structure of the housing portion. The secondary battery of the second embodiment will be described below, focusing on this difference. For reference, the contents relating to the secondary battery of the second embodiment can be similarly applied to the secondary battery of the first embodiment described above and the secondary battery of the third embodiment described below, unless they are inconsistent with each other.

[0075] 7, a secondary battery 200 according to this embodiment may include an electrode assembly 110, a housing 230, and an electrode lead 150. The electrode assembly 110 and the electrode lead 150 are as described above.

[0076] The outer casing 230 may include a receiving portion 231 for receiving the electrode assembly 110. The outer casing 230 may be a pouch-type outer casing. The outer casing 230 may be provided by sealingly joining first and second outer casings 241 and 242, which are arranged opposite each other, to each other while the electrode assembly 110 is received therein. The edges of the first and second outer casings 241 and 242 may be fully or partially sealed. This sealing may form an outer casing sealing portion 232 (see FIG. 6 ). The receiving portion 231 of the outer casing 230 may be pre-formed into a shape for receiving the electrode assembly 110 before the first and second outer casings 241 and 242 are joined together.

[0077] As shown in FIG. 6, the sheath 230 may include an exposure hole 233 that is opened to expose at least a portion of the electrode lead 150 to the outside of the sheath 230 .

[0078] The exterior material 230 may include an exposure hole sealing portion 234 formed to enclose the exposure hole 233. The exposure hole 233 may be formed in one or both of the first and second exterior materials 241 and 242, and the exposure hole sealing portion 234 may be formed in the exterior material (exposure hole exterior material) in which the exposure hole 233 is formed, of the first and second exterior materials 241 and 242.

[0079] The secondary battery 200 of this embodiment may include an insulating film 170 (see FIG. 7) disposed between the exposed hole outer casings 241, 242 and the electrode lead 150. The insulating film 170 is as described above.

[0080] 7, the receiving portion 231 of this embodiment may include an electrode assembly receiving portion 231a that receives the electrode assembly 110. The receiving portion 231 may include an electrode lead receiving portion 231b that receives at least a portion of the electrode lead 150. Depending on the shape of the receiving portion 231, a portion of the electrode lead 150 may be received in the electrode assembly receiving portion 231a together with the electrode assembly 110, and the remainder may be received in the electrode lead receiving portion 231b.

[0081] As described above, the electrode lead 150 of this embodiment may be disposed inside the sheath 230. Correspondingly, the electrode lead accommodating portion 231b may also be disposed inside the sheath 230. For example, the electrode lead accommodating portion 231b may be positioned inside the sheath 230 so as not to extend beyond the edge of the sheath 230, as shown in FIG.

[0082] The electrode lead 150 may be disposed at least partially on the exterior material sealing portion 232 (see FIG. 6) inside the exterior material 230. However, if the electrode lead 150 is disposed between the first and second exterior materials 241 and 242 during the process of sealing the edge of the exterior material 230 to form the exterior material sealing portion 232, the electrode lead 150 may apply force to the inside of the first and second exterior materials 241 and 242 during sealing, potentially damaging the exterior materials 241 and 242. For example, the first and second resin layers 141b and 142b (see FIG. 4) of the exterior materials 241 and 242 may be damaged. In the case of the exterior materials 241 and 242 of this embodiment, the electrode lead 150 is accommodated in the electrode lead accommodating portion 231b arranged on the exterior material sealing portion 232, so the above-described problem may not occur.

[0083] 7, a side 231b1 of the electrode lead receiving portion 231b facing the electrode assembly receiving portion 231a may be connected to the electrode assembly receiving portion 231a. The remaining sides 231b2, 231b3, and 231b4 of the electrode lead receiving portion 231b may be surrounded by the exterior sealing portion 232. As a result, the electrode lead receiving portion 231b may be completely sealed from the outside of the exterior casing 230.

[0084] The electrode assembly receiving portion 231a may be pre-formed into a shape for receiving the electrode assembly 110 before the electrode assembly 110 is received therein. For example, the electrode assembly receiving portion 231a may be formed by compressing a film-shaped exterior material 230. The electrode lead receiving portion 231b may also be pre-formed into a shape for receiving the electrode lead 150 before the electrode lead 150 is received therein. The electrode lead receiving portion 231b may be formed by compressing the film-shaped exterior material 230 during the process of forming the electrode assembly receiving portion 231a, or before or after this process.

[0085] The electrode lead 150 may extend in a direction transverse to the extension direction of the electrode tab 111 and be disposed inside the sheath 230. For example, as shown in FIG. 7, the electrode lead 150 may be disposed in a direction (see D2 in FIG. 8) perpendicular to the extension direction (see D1 in FIG. 8) of the electrode tab 111. Here, the electrode lead receiving portion 231b may be formed to correspond to the arrangement direction of the electrode lead 150. By disposing the electrode lead 150 in the above manner, it is possible to minimize an increase in the size of the sheath 230 due to the electrode lead 150 being disposed inside the sheath 230.

[0086] [Modification of the second embodiment] The secondary battery of embodiment 2 can be modified as follows: The secondary battery of embodiment 1 can also be modified in the same manner except for the electrode lead housing portion.

[0087] 8 is an exploded perspective view illustrating a first modification of the secondary battery of FIG. 7. The electrode lead 250′ of the first modification extends in a direction (e.g., direction D2) intersecting the extension direction D1 of the electrode tab 111, and the electrode tab 111 may be disposed so as to be located at the center of the electrode lead 250′ based on the intersecting direction. The electrode lead receiving portion 231b′ may also be positioned correspondingly. The exposure hole 233′ may be provided in the first exterior material 241.

[0088] FIG. 9 is an exploded perspective view illustrating a second modification of the secondary battery of FIG. 7. The electrode tab 111″ of the second modification may be bent toward one side surface S1 of the electrode assembly 110 so that one side surface of the electrode lead 250″ faces the one side surface S1 of the electrode assembly 110 from which the electrode tab 111″ protrudes. Due to this bending, the other side surface of the electrode lead 250″ may be disposed to face one side surface S2 of the second exterior material 242 that defines the electrode assembly receiving portion 231a″. An exposure hole 233″ may be formed in one side surface S2 of the second exterior material 242 facing the other side surface of the electrode lead 250″. The electrode lead receiving portion 231b″ may also be formed correspondingly in one side surface S2 of the second exterior material 242. For reference, FIG. 9 illustrates a battery in which the receiving portion 231 is formed only in the second exterior material 242. Meanwhile, when the positive electrode tab and the negative electrode tab both protrude from the same side of the electrode assembly, the exposure holes may also be formed in the same side of the exterior material to correspond thereto.

[0089] FIG. 10 is an exploded perspective view illustrating a third modification of the secondary battery of FIG. 7. The electrode tab 111''' of the third modification may be bent toward the outermost side surface S3 of the electrode lead 250''' so that one side surface of the electrode lead 250''' faces the outermost side surface S3 of the electrode assembly 110 based on the stacking direction of the electrodes and separators of the electrode assembly 110 (see D3 in FIG. 8). By bending in this manner, the other side surface of the electrode lead 250''' may be disposed to face the upper side surface S4 of the exterior material 242. The exposure hole 233''' may be formed in the upper side surface S4 of the second exterior material 242 facing the other side surface of the electrode lead 250'''. The electrode lead receiving portion 231b''' may also be formed in the upper side surface S4 of the second exterior material 242 corresponding to the exposure hole 233'''. For reference, FIG. 10 illustrates a battery in which the receiving portion 231 is formed only in the second exterior material 242. Meanwhile, when the positive electrode tab and the negative electrode tab both protrude from the same side of the electrode assembly, the exposure holes may also be formed parallel to the upper side of the exterior material to correspond thereto.

[0090] FIG. 11 is an exploded perspective view illustrating a fourth modification of the secondary battery of FIG. 7. The electrode tabs 111'''' in the fourth modification may all protrude from the same surface of the electrode assembly 110. For example, the positive electrode tab and the negative electrode tab may all protrude from the same surface of the electrode assembly 110 and be spaced apart from each other. Correspondingly, the electrode lead receiving portion 231b'''' and the exposure hole 233'''' may be arranged as shown in FIG. 11.

[0091] [Embodiment 3] FIG. 12 is a perspective view illustrating a secondary battery according to embodiment 3 of the present invention, and FIG. 13 is an exploded perspective view of the secondary battery of FIG. 12. The secondary battery of embodiment 3 differs from the secondary battery of embodiment 1 in the structure of the electrode leads. The secondary battery of embodiment 3 will be described below, focusing on this difference. For reference, the contents relating to the secondary battery of embodiment 3 are equally applicable to the secondary batteries of embodiments 1 and 2 described above, unless they are inconsistent with each other.

[0092] 13, a secondary battery 300 according to this embodiment may include an electrode assembly 110, an outer casing 330, and an electrode lead 350. The electrode assembly 110 is as described above.

[0093] The outer casing 330 may include a receiving portion 331 for receiving the electrode assembly 110. The outer casing 330 may be a pouch-type outer casing. The outer casing 330 may be provided by first and second outer casings 341 and 342 arranged opposite each other and hermetically joining them to each other while receiving the electrode assembly 110. The edges of the first and second outer casings 341 and 342 may be sealed entirely or partially. This sealing may form an outer casing sealing portion 332 (see FIG. 12).

[0094] As shown in FIG. 12, the sheath 330 may include an exposure hole 333 that is opened to expose at least a portion of the electrode lead 350 to the outside of the sheath 330 .

[0095] The exterior material 330 may include an exposure hole sealing portion 334 formed to enclose the exposure hole 333 .

[0096] The secondary battery 300 of this embodiment may include an insulating film 170 (see FIG. 13) disposed between the exterior materials 341 and 342 and the electrode lead 350.

[0097] 13, the receiving portion 331 of this embodiment may include an electrode assembly receiving portion 331a that receives the electrode assembly 110. The receiving portion 331 may include an electrode lead receiving portion 331b that receives at least a portion of the electrode lead 350.

[0098] The electrode lead 350 of this embodiment can be disposed inside the outer casing 230. Correspondingly, the electrode lead accommodating portion 331b can also be disposed inside the outer casing 330.

[0099] The electrode lead 350 of this embodiment will be described in detail with reference to Fig. 14. Fig. 14 is a cross-sectional view taken along line AA' in Fig. 12.

[0100] The electrode lead 350 may include an exposed portion 350a and a non-exposed portion 350b. The exposed portion 350a is a portion of the electrode lead 350 that is exposed to the outside of the sheath 342 through the exposure hole 333. The non-exposed portion 350b is another portion of the electrode lead 350 that is connected to the exposed portion 350a and is covered by the sheath 342 and is not exposed to the outside of the sheath 342.

[0101] The exposed portion 350a may include a protrusion 350c that protrudes further outward from the exterior covering 342 than the non-exposed portion 350b. The protrusion 350c may protrude from the non-exposed portion 350b at least to the outer surface (see P) of the exterior covering 342. Figure 14 illustrates an example of a protrusion 350c that protrudes further than the outer surface (see P) of the exterior covering 342.

[0102] The protrusion 350c can be formed by compressing a portion of the exposed portion 350a, as shown in Fig. 14. After imagining a rectangular region on the electrode lead 350, the protrusion 350c shown in Fig. 13 can be formed by compressing this rectangular region. Two opposing sides of the rectangular region can also be cut open before or during compression. Alternatively, the electrode lead 350 can be bent into the cross-sectional shape shown in Fig. 14 to form the protrusion. Alternatively, the protrusion can be formed by adding a separate member.

[0103] When the protrusion 350c is formed by compressing or bending the exposed portion 350a of the electrode lead 350, the protrusion 350c may be all or part of the exposed portion 350a and may form a single body with the non-exposed portion 350b. For example, the protrusion 350c may be part of the exposed portion 350a extending integrally from the non-exposed portion 350b, or may have a U-shaped cross section by including a vertical extension portion extending toward the exposure hole 333 and a horizontal extension portion extending horizontally integrally from the vertical extension portion.

[0104] For reference, when forming a surface treatment portion on the electrode lead 350 (see surface treatment portion 151 in Figure 3), the surface treatment portion can be formed on the surface of the electrode lead 350 by laser etching or the like, an insulating film can be fused onto the surface treatment portion, and a part of the electrode lead 350 can be pressed or bent into a U-shape to form the protrusion 350c.

[0105] In order to electrically connect the electrode lead 350 to other parts through the exposure hole 333, it is preferable that a portion of the electrode lead 350 protrudes outward from the exterior of the exterior material 342, taking into consideration the thickness of the exterior material 342, etc. The electrode lead 350 of this embodiment includes a protruding portion 350c that protrudes outward from the exterior material 342, making it easy to electrically connect the electrode lead 350 to other parts. This also makes it easier to weld the electrode lead 350 to other parts (e.g., a bus bar). This ease of welding can be further enhanced if the protruding portion 350c protrudes from the non-exposed portion 350b at least to the outer surface of the exterior material 342 (see P).

[0106] The protrusion 350c may be spaced a predetermined distance L from the edge of the exposure hole 333. The metal layers 141a, 142a (see FIG. 4) of the outer casing 342 may be exposed to the side of the exposure hole 333 due to the formation of the exposure hole 333. If the metal layers of the outer casing 342 come into contact with the protrusion 350c of the electrode lead 350, an electrical short circuit may occur. To prevent this, the above-described spacing may be necessary. The spacing distance L may be 0.5 mm or more. Alternatively, as shown in FIG. 15, an insulating member 380 may be disposed in the empty space provided by the above-described spacing to electrically insulate the protrusion 350c from the outer casing 342.

[0107] On the other hand, in the case of the secondary battery of the first embodiment, electrical connection can be achieved as shown in FIGS. 16 and 17 without the above-described protrusion 350c.

[0108] In the case of the secondary battery of embodiment 1, exposure holes 133 for exposing the electrode leads 150 are formed in the exterior material 130. When the secondary batteries are positioned so that the exposure holes 133 face each other as shown in Fig. 16 and then brought into close contact as shown in Fig. 17, the secondary batteries can be electrically connected to each other.

[0109] For example, as shown in FIG. 16, by positioning an exposure hole formed on the front surface of a secondary battery so that it corresponds to an exposure hole formed on the rear surface of another secondary battery, and then stacking the secondary batteries as shown in FIG. 17, the secondary batteries can be electrically connected to each other.

[0110] Considering the thin thickness of the exterior material, the electrode leads can be in contact with each other simply by adhering or laminating as described above. For stable contact of the electrode leads, the above-mentioned protrusions may be formed on the electrode leads 150. Alternatively, a separate connecting member (not shown) may be further provided to electrically connect the electrode leads exposed through the exposure holes 133 to each other.

[0111] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0112] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and do not limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0113] The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0114] 1. Pouch-type secondary battery 2 electrode assembly 15 Electrode tab 17 Electrode Lead 20 Exterior materials 21 Storage unit 23 Sealing section 100 Secondary battery 110 Electrode assembly 111 Electrode tab 130 Exterior materials 131 Storage unit 132 Exterior sealing section 133 Exposure Hole 134 Exposed hole sealing part 141 Exposed hole exterior material (first exterior material) 142 Exposed hole exterior material (second exterior material) 150 electrode leads 151 Surface Treatment Section 170 Insulating film 200 Secondary battery 230 Exterior materials 231 Storage Unit 232 Exterior sealing section 233 Exposure Hole 234 Exposed hole sealing part 241 Exposed hole exterior material (first exterior material) 242 Exposed hole exterior material (second exterior material) 300 Secondary battery 330 Exterior materials 331 Storage Unit 332 Exterior sealing section 333 Exposure Hole 334 Exposed hole sealing part 341 First exterior material 342 Second exterior material 350 Electrode Lead 380 Insulating materials

Claims

1. an electrode assembly including an electrode tab; an exterior material having a housing portion that houses the electrode assembly; an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the exterior material, the outer casing further includes an exposure hole that is opened to expose a portion of the electrode lead to the outside of the outer casing, the electrode lead includes an exposed portion exposed to the outside of the outer casing through the exposure hole, and a non-exposed portion connected to the exposed portion and covered by the outer casing so as not to be exposed to the outside of the outer casing, The exposed portion includes a protruding portion that protrudes toward the outside of the exterior material beyond the non-exposed portion.

2. The secondary battery according to claim 1 , wherein the protrusion protrudes from the unexposed portion by at least the outer surface of the exterior material.

3. The secondary battery according to claim 1 , wherein the protrusion is spaced a predetermined distance from an edge of the exposure hole.

4. The secondary battery according to claim 3 , further comprising an insulating member disposed in a vacant space defined by the predetermined distance for electrical insulation between the protrusion and the exterior material.

5. The exterior material further includes an exterior material sealing portion formed to at least partially enclose the receiving portion, and an exposure hole sealing portion formed to enclose the exposure hole, The secondary battery according to claim 1 , wherein the sealing performance of the exterior sealing portion is higher than that of the exposure hole sealing portion.

6. The exterior material sealing portion is formed by welding, The secondary battery according to claim 5 , wherein the exposure hole sealing portion is formed by fusion.

7. The exterior material is a first exterior material including a first metal layer; a second exterior material disposed opposite the first exterior material to form the storage section together with the first exterior material, and including a second metal layer; an exterior material sealing portion that hermetically connects the first exterior material and the second exterior material and is formed to at least partially enclose the storage portion; 2. The secondary battery of claim 1, further comprising: an exposure hole sealing part formed to enclose the exposure hole in an exposure hole exterior material, which is one of the first exterior material and the second exterior material and in which the exposure hole is formed.

8. The secondary battery according to claim 7 , wherein the exterior sealing portion is formed by welding the first metal layer and the second metal layer together.

9. The first exterior material further includes a first resin layer disposed inside the first metal layer, the second exterior material further includes a second resin layer disposed inside the second metal layer and facing the first resin layer, The secondary battery according to claim 7, wherein the exterior material sealing portion is formed by welding the first metal layer and the second metal layer in a state where the first metal layer and the second metal layer are in direct contact without the first resin layer and the second resin layer.

10. The secondary battery according to claim 7 , wherein the first metal layer and the second metal layer include stainless steel.

11. The electrode lead may further include an insulating film disposed between the exposure hole sheath and the electrode lead to cover the portion of the electrode lead exposed through the exposure hole, The secondary battery according to claim 7 , wherein the exposure hole sealing portion is formed by fusing the insulating film and a resin layer of the exposure hole exterior material disposed opposite the insulating film.

12. the exterior material sealing part is formed to entirely enclose the receiving part except for a portion where the first exterior material and the second exterior material are connected to each other, The secondary battery according to claim 7 , wherein the electrode lead is disposed inside the exterior material without passing through the exterior material sealing portion.

13. The secondary battery according to claim 1 , wherein the electrode lead extends in a direction transverse to an extension direction of the electrode tab and is disposed inside the exterior material.

14. The secondary battery according to claim 1 , wherein the housing includes an electrode assembly housing that houses the electrode assembly, and an electrode lead housing that houses at least a portion of the electrode lead.

15. the electrode assembly receiving portion is preformed into a shape for receiving the electrode assembly before the electrode assembly is received therein; The secondary battery according to claim 14 , wherein the electrode lead accommodating portion is preformed into a shape for accommodating the electrode lead before the electrode lead is accommodated therein.

16. The secondary battery of claim 1 , wherein the electrode lead is provided to be electrically connected to an electrode lead of another secondary battery through the protrusion.

17. The electrode lead may further include an insulating film disposed between the exposure hole sheath and the electrode lead to cover the portion of the electrode lead exposed through the exposure hole, a surface treatment portion having a large surface roughness is partially formed on the surface of the electrode lead; The secondary battery according to claim 7 , wherein the formation region of the surface treatment portion includes a region of the surface of the electrode lead that faces the insulating film.

18. an electrode assembly including an electrode tab; an exterior material having a housing portion that houses the electrode assembly; an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the outer covering, The secondary battery further includes an exposure hole formed in the exterior material to expose at least a portion of the electrode lead to the outside of the exterior material.

19. The secondary battery of claim 18 , wherein the electrode lead is configured to be electrically connected to an electrode lead of another secondary battery through the exposure hole.

20. 19. The secondary battery according to claim 18, wherein the electrode lead extends in a direction transverse to an extension direction of the electrode tab and is disposed inside the exterior material such that the electrode tab is located at a center of the electrode lead with respect to the transverse direction.

21. The secondary battery of claim 18 , wherein the electrode tab is bent toward one side of the electrode assembly such that one side of the electrode lead faces the one side of the electrode assembly from which the electrode tab protrudes.

22. 22. The secondary battery of claim 18, wherein the electrode tab is bent toward an outermost surface of the electrode assembly such that one side of the electrode lead faces the outermost surface of the electrode assembly in a stacking direction of the electrodes and separators of the electrode assembly.

23. an electrode assembly including an electrode tab; an exterior material having a housing portion that houses the electrode assembly; an electrode lead connected to the electrode tab of the electrode assembly and disposed inside the outer covering, The housing includes an electrode assembly housing that houses the electrode assembly, and an electrode lead housing that houses at least a portion of the electrode lead.

24. The sheath further includes a sheath sealing portion formed to at least partially enclose the container portion, The secondary battery according to claim 23 , wherein the electrode lead receiving portion is located on the exterior sealing portion to receive the electrode lead and is disposed inside the exterior sealing portion.

25. the electrode lead receiving portion has a side facing the electrode assembly receiving portion, the side communicating with the electrode assembly receiving portion; The secondary battery according to claim 24 , wherein the remaining side of the electrode lead accommodating portion is surrounded by the exterior material sealing portion.

26. The secondary battery according to claim 23 , wherein the exterior material further includes an exposure hole that is opened to expose at least a portion of the electrode lead to the outside of the exterior material.

27. the electrode tab is bent toward one side of the electrode assembly so that one side of the electrode lead faces the one side of the electrode assembly from which the electrode tab protrudes; The secondary battery of claim 26 , wherein the exposure hole is formed on one side of the exterior material facing the other side of the electrode lead by bending the electrode tab.

28. the electrode tab is bent toward the outermost surface of the electrode assembly such that one side of the electrode lead faces the outermost surface of the electrode assembly based on a direction in which the electrodes and separators of the electrode assembly are stacked; The secondary battery of claim 26 or 27, wherein the exposure hole is formed on one side of the exterior material facing the other side of the electrode lead by bending the electrode tab.

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