Secondary battery and manufacturing method therefor

Abstract

Provided is a secondary battery comprising: a stack-type electrode assembly having a plurality of unit batteries stacked in a first direction, and electrode leads formed at both ends thereof in a second direction perpendicular to the first direction; multifunctional terminal blocks (MTBs) provided at both ends of the stack-type electrode assembly; and a laminate sheet surrounding the side surface of the stack-type electrode assembly, wherein the MTBs include a fusion resin layer having a locally increased thickness on side surfaces thereof.

Description

Secondary battery and its manufacturing method

[0001] The present invention relates to a secondary battery and a method for manufacturing the same, and more particularly, to a secondary battery having improved safety and superior productivity and a method for manufacturing the same.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0167377, filed November 28, 2023, the entire disclosure of which is incorporated herein by reference.

[0003] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. They are widely used as a power source for various wireless devices, including handsets, laptops, and cordless vacuum cleaners. Recently, improved energy density and economies of scale have dramatically reduced the per-unit manufacturing cost of secondary batteries. Furthermore, as the range of battery electric vehicles (BEVs) has increased to match that of fuel-powered vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0004] As secondary batteries become increasingly used in mobility, demand for their safety is increasing. Fires and other accidents involving secondary batteries used in mobility vehicles can endanger the lives of drivers, making research into technologies that enhance secondary battery safety essential.

[0005] The first technical task to be achieved by the present invention is to provide a secondary battery with improved safety and superior productivity.

[0006] The second technical task to be achieved by the present invention is to provide a method for manufacturing a secondary battery with improved safety and superior productivity.

[0007] In order to achieve the first technical task, the present invention provides a secondary battery comprising: a stacked electrode assembly in which a plurality of unit cells are stacked in a first direction and have electrode leads at both ends in a second direction perpendicular to the first direction; a multifunctional terminal block (MTB) provided at both ends of the stacked electrode assembly; and a laminate sheet wrapping a side surface of the stacked electrode assembly, wherein the MTB includes a fusion resin layer having a locally increased thickness on the side surface.

[0008] In some embodiments, the laminated portion of the laminate sheet may be positioned at a location where the fused resin layer has a locally increased thickness.

[0009] In some embodiments, the fusion resin layer is a polymer film, and a location where the fusion resin layer has a locally increased thickness may be a location where the polymer film is coated more times than other locations, thereby increasing the thickness.

[0010] In some embodiments, the fusion resin layer may include an extension extending from an edge of the laminate sheet along a side of the MTB.

[0011] In some embodiments, the thickness of the fused resin layer at a location in the extension portion having the locally increased thickness may be about 1.8 to about 2.2 times the thickness of the fused resin layer at another location in the extension portion.

[0012] In some embodiments, the joint portion may be positioned substantially at the center of the secondary battery in the first direction.

[0013] In some embodiments, the fusion resin layer is a polymer ring fused around the perimeter of the MTB housing of the MTB, and a location where the fusion resin layer has a locally increased thickness may be a location where tension is applied to the polymer ring when the polymer ring is fused around the perimeter of the MTB housing.

[0014] In some embodiments, the fusion resin layer may extend at least partially between the bonding portions.

[0015] In some embodiments, the length of the fused resin layer extending between the bonding portions may be from about 0.1 mm to about 2 mm.

[0016] The present invention provides a method for manufacturing a secondary battery, comprising the steps of: attaching a multifunctional terminal block (MTB) to both ends of a stacked electrode assembly, which includes a plurality of unit cells stacked in a first direction and has electrode leads at both ends in a second direction perpendicular to the first direction; forming a fusion resin layer around an MTB housing of the MTB; and bonding a laminate sheet to the fusion resin layer so as to wrap a side surface of the stacked electrode assembly, wherein the fusion resin layer has a locally increased thickness, and the laminate sheet has a joint portion at a position where the fusion resin layer has a locally increased thickness.

[0017] In some embodiments, the step of forming the fusion resin layer may include the step of locally forming an overlapping layer of polymer film.

[0018] In some embodiments, the polymer film may be configured to locally overlap after wrapping around a side of the MTB housing.

[0019] In some embodiments, the step of forming the fusion resin layer may include the steps of: providing a polymer ring around the periphery of the MTB housing, the polymer ring having an inner length longer than the length of the outer circumferential surface of the MTB housing; fusing the polymer ring from one side of the MTB housing onto a side surface of the MTB housing; and fusing the remaining lengths of the polymer rings to each other.

[0020] In some embodiments, in the step of fusing the remaining length of the polymer rings together, the position at which the polymer rings are mutually fused together may substantially coincide with the position at which the laminate sheet has a bonding portion.

[0021] In some embodiments, an electrode terminal portion electrically connected to an electrode lead of the stacked electrode assembly is provided within the MTB housing; and a bus bar electrically connecting the electrode lead of the stacked electrode assembly to the electrode terminal portion is provided, and the laminate sheet includes a flexible metal layer; an inner resin layer provided on one side of the metal layer; and an outer resin layer provided on the other side of the metal layer, wherein the inner resin layer may include casted polypropylene (CPP).

[0022] The secondary battery of the present invention can improve safety because it has excellent sealing reliability, and can improve productivity because it is easy to manufacture.

[0023] The effects that can be obtained from the exemplary embodiments of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure pertain from the following description. In other words, unintended effects resulting from practicing the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0024] Figure 1 is a perspective view showing the main parts of a secondary battery according to one embodiment of the present invention.

[0025] Fig. 2 is a partial perspective view showing an enlarged portion of a part of the secondary battery of Fig. 1.

[0026] Figure 3 is a schematic perspective view showing the appearance of the laminate sheet removed from the secondary battery of Figure 1.

[0027] FIG. 4 is a side view showing a secondary battery according to one embodiment of the present invention viewed in a second direction.

[0028] Figure 5 is an enlarged partial view of the portion indicated by P in Figure 4.

[0029] FIG. 6 is a side view showing a secondary battery according to another embodiment of the present invention viewed in a second direction.

[0030] Figure 7 is a partially exploded perspective view showing a method of bonding laminate sheets of a secondary battery according to one embodiment of the present invention.

[0031] Figure 8 is a partial cross-sectional view of a laminate sheet according to one embodiment of the present invention.

[0032] Figure 9 is a schematic diagram showing the main portion of the extension exposed from the edge of the laminate sheet.

[0033] FIG. 10 is a cross-sectional view showing a main portion of a cross-section of a first MTB and a laminate sheet according to one embodiment of the present invention taken along line XX' of FIG. 7.

[0034] Figure 11 is a partially exploded perspective view showing a method of bonding laminate sheets of a secondary battery according to another embodiment of the present invention.

[0035] Figure 12 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0036] FIG. 13, FIG. 14, and FIG. 19 are perspective views or side views showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0037] Figures 15 to 17 are drawings showing one embodiment of a method for forming a fusion resin layer.

[0038] Fig. 18 is a drawing showing another embodiment of a method for forming a fusion resin layer.

[0039] FIG. 20 is a schematic perspective view of a battery pack according to one embodiment of the present invention.

[0040] Fig. 21 is an exploded perspective view schematically illustrating the configuration of the battery pack of Fig. 20.

[0041] Figure 22 is a perspective view showing the battery cells of Figure 21 mounted in a pack housing.

[0042] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention may be modified in various different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. It is preferable to interpret that the embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art. Like numbers refer to like elements throughout. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the present invention is not limited by the relative sizes or spacings depicted in the accompanying drawings.

[0043] While terms like "first" and "second" may be used to describe various components, these components are not limited by these terms. These terms are used solely to distinguish one component from another. For example, a first component could be referred to as a "second component," and vice versa, without departing from the scope of the present invention.

[0044] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the inventive concept. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the expressions "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, operations, components, parts, or combinations thereof.

[0045] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Furthermore, it is to be understood that commonly used terms, such as those defined in dictionaries, should be interpreted to have a meaning consistent with their meaning within the relevant technical context, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0046] In some embodiments, where implementations are otherwise feasible, specific process sequences may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0047] In the accompanying drawings, variations in the shapes depicted may be expected, for example, depending on manufacturing techniques and / or tolerances. Therefore, embodiments of the present invention should not be construed as being limited to the specific shapes of the regions depicted herein, but should include, for example, changes in shapes resulting from the manufacturing process. All terms "and / or" used herein include each and every combination of one or more of the mentioned components. In addition, the term "substrate" used herein may mean the substrate itself, or a laminated structure including the substrate and a predetermined layer or film formed on the surface thereof. In addition, the "surface of the substrate" in this specification may mean the exposed surface of the substrate itself, or the outer surface of a predetermined layer or film formed on the substrate.

[0048]

[0049] (Example 1)

[0050] Fig. 1 is a perspective view showing the main part of a secondary battery (100) according to one embodiment of the present invention. Fig. 2 is a partial perspective view showing an enlarged portion of a part of the secondary battery (100) of Fig. 1. Fig. 3 is a schematic perspective view showing the secondary battery (100) of Fig. 1 with the laminate sheet (130) removed.

[0051] In the drawings below, the secondary battery (100) is illustrated as being defined in a vertical coordinate system defined by a first direction along the X-axis, a second direction along the Y-axis, and a third direction along the Z-axis, which are perpendicular to each other, but the first direction, the second direction, and the third direction are not particularly limited as long as they are relatively perpendicular to each other.

[0052] Referring to FIGS. 1 to 3, the secondary battery (100) includes a stacked electrode assembly (110), a multifunctional terminal block (MTB) (120a, 120b), and a laminate sheet (130).

[0053] The stacked electrode assembly (110) may include a plurality of unit cells (111) stacked in a first direction (e.g., X-axis direction). Each of the unit cells (111) may have an electrode material applied on a metal foil that acts as a current collector.

[0054] Each of the unit cells (111) may have a thin plate-shaped body extending in a second direction (e.g., the Y-axis direction). Each of the unit cells (111) may be a positive electrode unit cell or a negative electrode unit cell. In some embodiments, the plurality of unit cells (111) may be formed by alternately stacking positive electrode unit cells and negative electrode unit cells one by one. The positive electrode unit cell and the negative electrode unit cell may be separated from each other by a separator.

[0055] In some other embodiments, the plurality of unit batteries (111) may be formed by alternately stacking a plurality of positive unit batteries and a plurality of negative unit batteries. The plurality of positive unit batteries and the plurality of negative unit batteries may be separated from each other by a separator.

[0056] In some other embodiments, the plurality of unit batteries (111) may be formed by alternately stacking a plurality of positive unit batteries and a plurality of negative unit batteries. The plurality of positive unit batteries and the plurality of negative unit batteries may be separated from each other by a separator.

[0057] The stacked electrode assembly (110) may have electrode leads (116) at both ends in the second direction (e.g., Y-axis direction). The electrode leads (116) may be electrically connected to electrode tabs of the plurality of unit cells (111). One or more electrode tabs may be connected to one electrode lead (116). In some embodiments, two or more electrode tabs may be connected to one electrode lead (116).

[0058] The stacked electrode assembly (110) may include a first electrode stack (110a) stacked in the first direction (e.g., X-axis direction) while sharing one electrode lead (116) and a second electrode stack (110b) stacked in the first direction (e.g., X-axis direction) while sharing another electrode lead (116).

[0059] In some embodiments, the stacked electrode assembly (110) may have two electrode leads (116) on one side and two electrode leads (116) on the other side. In this case, the first electrode stack (110a) included in the stacked electrode assembly (110) may have a first electrode lead (116a) on one side and a second electrode lead (116b) on the other side. In addition, the second electrode stack (110b) included in the stacked electrode assembly (110) may have a third electrode lead (116c) on one side and a fourth electrode lead (116d) on the other side. However, the present invention is not limited thereto.

[0060] A first MTB (120a) may be provided at one end of the stacked electrode assembly (110) in the second direction (e.g., Y-axis direction), and a second MTB (120b) may be provided at the other end. One of the first MTB (120a) and the second MTB (120b) may be electrically connected to the positive electrode side of the stacked electrode assembly (110), and the other may be electrically connected to the negative electrode side of the stacked electrode assembly (110). The second MTB (120b) may have substantially the same configuration as the first MTB (120a) except for the polarity. Hereinafter, the first MTB (120a) will be described, but a person skilled in the art will be able to understand the configuration of the second MTB (120b) therefrom.

[0061] In some embodiments, the first MTB (120a) may include an MTB housing (122), an electrode terminal portion (124) accommodated within the MTB housing (122), and a bus bar (125) (see FIG. 10) electrically connecting the electrode terminal portion (124) and the electrode lead (116).

[0062] The MTB housing (122) may include a material having relatively high rigidity, such as metal, and defines the exterior of the first MTB (120a). In some embodiments, the MTB housing (122) may be made of aluminum (Al), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), manganese (Mn), or an alloy containing one or more of these.

[0063] The MTB housing (122) may include a through hole (122h) exposing the electrode terminal portion (124) described below. The through hole (122h) may be provided in the MTB housing (122) so that the electrode terminal portion (124) is exposed toward the second direction (e.g., Y-axis direction). Therefore, the through hole (122h) may be provided on a plane perpendicular to the second direction (e.g., Y-axis direction) of the MTB housing (122). In addition, the through hole (122h) may have an opening that is open in the longitudinal direction of the electrode assembly (110). The shape of the through hole (122h) may be configured to match the outer shape of the portion where the electrode terminal portion (124) is exposed to the outside.

[0064] In some embodiments, the electrode terminal portion (124) may have an exposed surface facing outward from the MTB housing (122) that is flat. In some embodiments, the exposed surface may have a flat surface extending perpendicular to the second direction (e.g., the Y-axis direction). In some embodiments, the electrode terminal portion (124) may have a free surface in the shape of a disk and may be exposed to the outside.

[0065] In some embodiments, an electrically insulating insulating gasket (129) may be provided between the electrode terminal portion (124) and the MTB housing (122) so that the electrode terminal portion (124) is electrically insulated from the MTB housing (122).

[0066] In some embodiments, the first MTB (120a) may include a venting disk configured to rupture when the internal pressure of the secondary battery (100) excessively increases, thereby releasing gas that causes the excessively increased internal pressure. The venting disk is not restored to its original state when it ruptures due to a thermal event occurring within the secondary battery (100). The venting disk may be any venting disk known in the art and is not particularly limited.

[0067] In some embodiments, the MTB housing (122) may further include a fusion resin layer (122p) on the side.

[0068] The above-mentioned fusion resin layer (122p) is a layer of thermoplastic resin, and may contain, for example, one or more of polyolefin resin, polyester resin, polyamide resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile, polyurethane, polycarbonate, polyacetal, polyacrylate, and modified polyvinyl alcohol resin.

[0069] The above polyolefin resin includes, for example, polyethylene, polypropylene, poly(1-butene), poly(4-methyl-1-pentene), an ethylene-propylene copolymer, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, a copolymer of polyolefin and maleic anhydride, an ethylene-vinyl ester copolymer, an ethylene-acrylic acid ester copolymer, or a modified polyolefin obtained by graft-modifying these with an unsaturated carboxylic acid or a derivative thereof, but the present invention is not limited thereto.

[0070] In some embodiments, the polyester resin includes polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate, but the present invention is not limited thereto.

[0071] In some embodiments, the polyamide resin comprises nylon 6, nylon 6·6, nylon 6 / 66 copolymer, nylon 11, nylon 12, or poly(m-xylene adipamide), but the present invention is not limited thereto.

[0072] In some embodiments, the fusion resin layer (122p) may be cast, or may be stretched or rolled in one or two axes.

[0073] In some embodiments, the fusion resin layer (122p) may at least partially cover a side surface of the MTB housing (122). In some embodiments, the fusion resin layer (122p) may extend from an inner end (122ie) or vicinity of the side surface of the MTB housing (122) toward an outer end (122oe) of the side surface of the MTB housing (122). Here, the inner end (122ie) refers to an end adjacent to the electrode lead (116). In some embodiments, the fusion resin layer (122p) may surround a side surface of the MTB housing (122) with a predetermined width between the inner end (122ie) and the outer end (122oe). In some embodiments, the fusion resin layer (122p) may extend along the side of the MTB housing (122) with a predetermined width between the inner end (122ie) and the outer end (122oe).

[0074] In some embodiments, the fusion resin layer (122p) may surround a side surface of the MTB housing (122) while having a constant width between the inner end (122ie) and the outer end (122oe). In some embodiments, the fusion resin layer (122p) may extend in a first direction (e.g., X-axis direction) and / or a third direction (e.g., Z-axis direction) while having a constant width between the inner end (122ie) and the outer end (122oe).

[0075] In some embodiments, the fusion resin layer (122p) may extend along the side of the MTB housing (122) with a constant width between the inner end (122ie) and the outer end (122oe).

[0076] In some embodiments, the fusion resin layer (122p) may cover the entire side surface of the MTB housing (122).

[0077] The above-mentioned fusion resin layer (122p) may have a thickness of, for example, about 20 μm to about 400 μm. In some embodiments, the fusion resin layer (122p) may have a thickness of from about 20 μm to about 400 μm, from about 30 μm to about 380 μm, from about 40 μm to about 360 μm, from about 50 μm to about 340 μm, from about 60 μm to about 320 μm, from about 70 μm to about 300 μm, from about 80 μm to about 280 μm, from about 90 μm to about 260 μm, from about 100 μm to about 240 μm, from about 110 μm to about 220 μm, from about 120 μm to about 200 μm, from about 130 μm to about 180 μm, from about 140 μm to about 160 μm, or a range between any two of these values.

[0078] If the thickness of the above-mentioned fusion resin layer (122p) is too thin, the mechanical strength may be insufficient. If the thickness of the above-mentioned fusion resin layer (122p) is too thick, it may be economically disadvantageous.

[0079] The above-mentioned fusion resin layer (122p) may be fused with the laminate sheet (130). In some embodiments, the above-mentioned fusion resin layer (122p) may extend from an end portion (130e) of the laminate sheet (130). In some embodiments, the above-mentioned fusion resin layer (122p) may be exposed from an edge portion (130e) of the laminate sheet (130) and then extend toward the outer end portion (122oe).

[0080] In some embodiments, the first MTB (120a) may further include a check valve (128). The check valve (128) may be configured to open to discharge internal gas when the internal pressure of the secondary battery (100) becomes higher than a predetermined pressure, and to close again when the internal pressure is relieved by the discharge of the gas. The check valve (128) does not have a part that is ruptured by the discharge of the gas, and can be restored to its original state after the discharge of the internal gas.

[0081] The secondary battery (100) further includes an electrolyte. The electrolyte may be an electrolyte used for a typical lithium secondary battery and is not particularly limited. In some embodiments, the electrolyte may be injected immediately before sealing the laminate sheet (130). In some embodiments, the electrolyte may be injected through an electrolyte injection port provided in the first MTB (120a) after sealing the laminate sheet (130).

[0082] FIG. 4 is a side view showing a secondary battery (100) according to one embodiment of the present invention when viewed in a second direction (e.g., Y-axis direction).

[0083] Referring to FIG. 4, a fusion resin layer (122p) may be provided between the MTB housing (122) and the laminate sheet (130) surrounding the MTB housing (122). The fusion resin layer (122p) may have a locally increased thickness. In FIG. 4, the fusion resin layer (122p) is illustrated as having a locally increased thickness on the upper surface of the MTB housing (122), but the present invention is not limited thereto.

[0084] In some embodiments, the fusion resin layer (122p) may have a protrusion (122pp) at a location having a locally increased thickness. The protrusion (122pp) may be positioned adjacent to the joining portion (130m) where the laminate sheets (130) are joined. A defect may occur in which a gap is formed between the joining portion (130m) where the facing laminate sheets (130) are joined and the MTB housing (122) due to insufficient bonding. This defect may cause problems such as electrolyte leakage or external moisture inflow.

[0085] However, in the secondary battery (100) of the present invention, a defect in which a gap is generated can be effectively prevented by arranging a protrusion (122pp) between the joint (130m) and the MTB housing (122), and thus problems such as leakage of electrolyte or inflow of external moisture can be prevented.

[0086] In some embodiments, the joining portion (130m) may be positioned at the substantial center portion of the secondary battery (100) in the first direction (e.g., X-axis direction). In some other embodiments, the joining portion (130m) may be positioned adjacent to the corner portion of the MTB housing (122) illustrated in FIG. 4.

[0087] In some embodiments, the fusion resin layer (122p) may extend at least partially between the laminate sheets (130) of the joining portion (130m). The portion of the fusion resin layer (122p) extending between the laminate sheets (130) of the joining portion (130m) may be the protrusion (122pp).

[0088] The length (d) of the protrusion (122pp) extending between the laminate sheets (130) may be from about 0.1 mm to about 2 mm. In some embodiments, the extended length (d) may be from about 0.1 mm to about 2 mm, from about 0.2 mm to about 1.9 mm, from about 0.3 mm to about 1.8 mm, from about 0.4 mm to about 1.7 mm, from about 0.5 mm to about 1.6 mm, from about 0.6 mm to about 1.5 mm, from about 0.7 mm to about 1.4 mm, from about 0.8 mm to about 1.3 mm, from about 0.9 mm to about 1.2 mm, from about 1 mm to about 1.1 mm, or a range between any two of these values.

[0089] If the extended length (d) of the above protrusion (122pp) is too small or too large, the effect of preventing defects that cause gaps may be insufficient.

[0090] Figure 5 is an enlarged partial view of the portion indicated by P in Figure 4.

[0091] Referring to FIG. 5, the fusion resin layer (122p) may include an overlapping layer in which two polymer films (122pf1, 122pf2) are overlapped adjacent to the bonding portion (130m). In some embodiments, the overlapping polymer films (122pf1, 122pf2) may be opposite ends of a single polymer film constituting the fusion resin layer (122p). That is, the polymer film may surround the MTB housing (122) and then have its opposite ends overlap one surface of the MTB housing (122).

[0092] In Fig. 5, polymer films (122pf1, 122pf2) are indicated by dotted lines. In some cases, the interface between the polymer films (122pf1, 122pf2) may be confirmed, or the interface between the polymer films (122pf1, 122pf2) may not be confirmed due to fusion. In some embodiments, as shown in Fig. 5, a location where the fusion resin layer (122p) has a locally increased thickness (i.e., a protrusion (122pp)) may have an increased thickness because the number of times the polymer film is coated is greater than that of other locations. However, the present invention is not limited thereto.

[0093] Fig. 6 is a side view showing a secondary battery (100) according to another embodiment of the present invention when viewed in a second direction (e.g., Y-axis direction). In the embodiment described with reference to Fig. 4, the joining part (130m) is positioned at the center of the secondary battery (100) in the first direction (e.g., X-axis direction), whereas in the embodiment of Fig. 6, the joining part (130m) is positioned adjacent to a corner of the MTB housing (122), which is different.

[0094] Referring to FIG. 6, the joining portion (130m) may be positioned close to any corner of the MTB housing (122). In some embodiments, the joining portion (130m) may be positioned close to one of two corners of the four corners of the MTB housing (122) that are closer to the check valve (128). In some other embodiments, the joining portion (130m) may be positioned close to one of two corners of the four corners of the MTB housing (122) that are farther from the check valve (128).

[0095] The position of the protrusion (122pp) may be substantially the same as the position of the joint (130m). Accordingly, the protrusion (122pp) may be positioned close to any corner of the MTB housing (122). In some embodiments, the protrusion (122pp) may be positioned close to one of the two corners of the four corners of the MTB housing (122) that are closer to the check valve (128). In some other embodiments, the protrusion (122pp) may be positioned close to one of the two corners of the four corners of the MTB housing (122) that are farther from the check valve (128).

[0096] Fig. 7 is a partially exploded perspective view showing a method of joining a laminate sheet (130) of a secondary battery (100) according to one embodiment of the present invention. Fig. 8 is a partial cross-sectional view of a laminate sheet (130) according to one embodiment of the present invention.

[0097] Referring to FIGS. 7 and 8, the laminate sheet (130) may be configured to wrap around a side surface of the stacked electrode assembly (110). In some embodiments, the laminate sheet (130) may be attached to a side surface of the MTB (120a, 120b) so as to at least partially cover the side surface of the MTB (120a, 120b). In some embodiments, a pair of parallel edge portions (130e) of the laminate sheet (130) may cover the entire side surfaces of the MTB (120a, 120b) that are parallel to the second direction (e.g., the Y-axis direction). In some other embodiments, the pair of parallel edge portions (130e) of the laminate sheet (130) may cover only a portion of the side surfaces of the MTB (120a, 120b) that are parallel to the second direction (e.g., Y-axis direction).

[0098] The above laminate sheet (130) may include a flexible metal layer (134), an inner resin layer (132) provided on one side of the metal layer (134), and an outer resin layer (136) provided on the other side of the metal layer (134).

[0099] The metal layer (134) can maintain an appropriate thickness and prevent water vapor, oxygen, and other gases from penetrating from the outside to the inside, and can prevent electrolyte leakage. In some embodiments, the metal layer (134) may include at least one selected from iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), aluminum (Al), and alloys thereof, but is not limited thereto. When the metal layer (134) is made of a material containing iron, the mechanical strength is strengthened, and when it is made of an aluminum material, the flexibility is improved, and thus, aluminum metal foil is mainly used.

[0100] The above metal layer (134) can be relatively easily deformed by a force applied from the outside, and can be configured to have an appropriate thickness and mechanical strength so that cracks or holes do not occur even when repeatedly deformed.

[0101] In some embodiments, the metal layer (134) can have a thickness of about 20 micrometers (μm) to about 100 μm. In some embodiments, the thickness of the metal layer (134) can have a range of about 20 μm to about 100 μm, about 25 μm to about 95 μm, about 30 μm to about 90 μm, about 35 μm to about 85 μm, about 40 μm to about 80 μm, about 45 μm to about 75 μm, about 50 μm to about 70 μm, about 55 μm to about 60 μm, or any two of these values.

[0102] The internal resin layer (132) provided on one side of the metal layer (134) may include a heat-sealing layer. In some embodiments, the internal resin layer (132) may include a polyolefin-based material capable of performing a sealing function through fusion. In some embodiments, the internal resin layer (132) may include a modified propylene such as cast polypropylene (CPP), or a polypropylene-butylene-ethylene terpolymer.

[0103] The above inner resin layer (132) can be formed by coating or laminating one side of the above metal layer (134).

[0104] The external resin layer (136) provided on the other side of the metal layer (134) can act as a base substrate and a protective layer for forming the laminate sheet (130). The external resin layer (136) can include an insulating material such as polyethylene terephthalate (PET) or nylon.

[0105] In some embodiments, the inner resin layer (132) and the outer resin layer (136) may each have a thickness of about 10 micrometers (μm) to about 50 μm. In some embodiments, the thickness of each of the inner resin layer (132) and the outer resin layer (136) may have a thickness of about 10 μm to about 50 μm, about 12 μm to about 48 μm, about 15 μm to about 45 μm, about 17 μm to about 43 μm, about 20 μm to about 40 μm, about 22 μm to about 38 μm, about 25 μm to about 35 μm, about 27 μm to about 33 μm, or a range between any two of these values.

[0106] In some embodiments, an adhesive resin layer may be further provided between the inner resin layer (132) and the metal layer (134) and / or between the outer resin layer (136) and the metal layer (134). The adhesive resin layer may be provided for smooth adhesion between different materials. The adhesive resin layer may be formed as a single layer or multiple layers. In some embodiments, the adhesive resin layer may include a polyolefin-based resin, a polyurethane-based resin, an epoxy-based resin, or a mixture thereof.

[0107] In some embodiments, the inner resin layer (132) may be fused to a fusion resin layer (122p) provided on the side surfaces of the MTBs (120a, 120b) at both ends in the second direction (e.g., Y-axis direction). As the inner resin layer (132) surrounds the side surfaces of the MTBs (120a, 120b) and is fused to the fusion resin layer (122p), the stacked electrode assembly (110) may be sealed within the laminate sheet (130).

[0108] The inner resin layer (132) facing the first MTB (120a) can be melted by heating while in contact with the fusion resin layer (122p) on the side of the first MTB (120a) and then cooled to be fused on the side, thereby forming a first sealing portion (130m1). The inner resin layer (132) facing the second MTB (120b) can be melted by heating while in contact with the fusion resin layer (122p) on the side of the second MTB (120b) and then cooled to be fused on the side, thereby forming a second sealing portion (130m2).

[0109] The end portions (130t) of the laminate sheet (130) surround the sides of the MTBs (120a, 120b) and the stacked electrode assembly (110) and are then fused to each other to form a joint portion (130m) (see FIG. 1). Specifically, the laminate sheet (130) can be pressed so that the inner resin layers (132) face each other in the joint portion (130m), and then the facing inner resin layers (132) can be fused to each other.

[0110] The above-mentioned joining part (130m) may be positioned on any one side of the stacked electrode assembly (110). In some embodiments, the joining part (130m) may surround the stacked electrode assembly (110) and be positioned in a third direction (e.g., the Z-axis direction) of the stacked electrode assembly (110).

[0111] The above-mentioned fusion resin layer (122p) may include an extension portion (122pe) extending from an edge (130e) of the laminate sheet (130) along a side surface of the MTB housing (122). The extension portion (122pe) may extend a predetermined length from the edge (130e) of the laminate sheet (130) toward an outer end (122oe) of the MTB housing (122).

[0112]

[0113] Figure 9 is a schematic diagram showing the main portion of the extension portion (122pe) exposed from the edge (130e) of the laminate sheet (130).

[0114] Referring to Fig. 9, the thickness (d2) of the fusion resin layer (122p) at a location having a locally increased thickness in the extension portion (122pe) is greater than the thickness (d1) of the fusion resin layer (122p) at another location in the extension portion (122pe). For example, the thickness (d2) may be about 1.8 to about 2.2 times the thickness (d1).

[0115] Since the above extension portion (122pe) is a portion exposed to the outside of the laminate sheet (130), it may not be thermally affected or may be subject to a small amount of thermal influence when the laminate sheet (130) is fused to the MTB housing (122) with the fusion resin layer (122p) therebetween. Therefore, in the above extension portion (122pe), an overlapping layer of the polymer film may remain at a location having a locally increased thickness. In some cases, the overlapping layer of the polymer film may melt in the fusion resin layer (122p) fused between the laminate sheet (130) and the MTB housing (122), so that an overlapping appearance may not be observed.

[0116]

[0117] FIG. 10 is a cross-sectional view showing a main portion of a cross-section of a first MTB (120a) and a laminate sheet (130) according to one embodiment of the present invention taken along line XX' of FIG. 7.

[0118] Referring to FIG. 10, a bus bar (125) may be provided to make surface contact with the electrode terminal portion (124). The bus bar (125) may be made of a metal material having low electrical resistance. In some embodiments, the bus bar (125) may be made of copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), platinum (Pt), molybdenum (Mo), tin (Sn), palladium (Pd), or an alloy including one or more of these.

[0119] The bus bar (125) may be configured to make surface contact with the electrode lead (116) of the stacked electrode assembly (110). In some embodiments, the bus bar (125) may be joined to the electrode lead (116) by welding. In some embodiments, the bus bar (125) may be joined to the electrode lead (116) by a fastener, for example, by a rivet.

[0120] In some embodiments, the bus bar (125) may include a center portion (125c) having a planar shape extending horizontally in the first direction (e.g., X-axis direction) and an edge portion (125e) extending by bending from the center portion (125c). The center portion (125c) may be configured to form a generally U-shaped cross-sectional shape together with the edge portion (125e) and may extend in the third direction (e.g., Z-axis direction). In some embodiments, the edge portion (125e) may have a plane extending perpendicularly to the first direction (e.g., X-axis direction).

[0121] The above bus bar (125) can make surface contact with the electrode terminal portion (124) at the center portion (125c). The above bus bar (125) can make surface contact with the electrode lead (116) at the edge portion (125e).

[0122] In some embodiments, the electrode lead (116) may include a pre-bended portion that is bent at a portion that does not contact the bus bar (125). The pre-bended portion may prevent stress from being concentrated at a specific portion of the electrode lead (116) due to an external force applied to the stacked electrode assembly (110), thereby improving safety.

[0123] The laminate sheet (130) can be fused with the fusion resin layer (122p). More specifically, the inner resin layer (132) of the laminate sheet (130) can be fused with the fusion resin layer (122p).

[0124] In Fig. 10, an interface is shown to exist between the inner resin layer (132) and the fusion resin layer (122p), but this is for convenience of understanding, and in reality, an interface may not be confirmed between the inner resin layer (132) and the fusion resin layer (122p).

[0125] As described above, the extension portion (122pe) of the fusion resin layer (122p) may extend somewhat from the edge (130e) of the laminate sheet (130) toward the outer end (122oe) of the side of the MTB housing (122).

[0126]

[0127] (Example 2)

[0128] Figure 11 is a partially exploded perspective view showing the bonding method of a laminate sheet (130) of a secondary battery (100) according to another embodiment of the present invention.

[0129] Referring to FIG. 11, the fused resin layer (122p) may have a protrusion (122pp) having a locally increased thickness. In some embodiments, the protrusion (122pp) may protrude in a third direction (e.g., in the Z-axis direction) with a length (d) as described with reference to FIG. 4.

[0130] In some embodiments, the fusion resin layer (122p) may be a polymer ring provided around the MTB housing (122). The material of the polymer ring may be the same as the material of the fusion resin layer (122p) with reference to FIGS. 1 to 3 above, and thus, further description thereof is omitted herein.

[0131] The method for forming the protrusion (122pp) provided on the fusion resin layer (122p) will be described in more detail later. The protrusion (122pp) may be, for example, a portion to which tension is applied to the polymer ring when the polymer ring is fused to form the fusion resin layer (122p) around the periphery of the MTB housing (122).

[0132]

[0133] (Example 3)

[0134] Fig. 12 is a flowchart illustrating a method for manufacturing a secondary battery (100) according to one embodiment of the present invention. Figs. 13 to 19 are perspective views or side views illustrating a method for manufacturing a secondary battery (100) according to one embodiment of the present invention.

[0135] Referring to FIGS. 12 and 13, MTBs (120a, 120b) are attached to both ends of a stacked electrode assembly (110) including a plurality of unit cells (111) stacked in a first direction (e.g., X-axis direction) (S110).

[0136] The above stacked electrode assembly (110) may have electrode leads at both ends in the second direction (e.g., the Y-axis direction). This has been described with reference to FIG. 3, so a detailed description thereof is omitted here.

[0137] In some embodiments, the MTB (120a, 120b) and the stacked electrode assembly (110) may be joined to each other by welding the electrode leads to the bus bars of the MTB. The welding method is not particularly limited and any suitable method known to those skilled in the art may be used.

[0138]

[0139] Referring to FIGS. 12 and 14, a fusion resin layer (122p) can be formed around the MTB housing (122) of the MTB (120a, 120b) (S120).

[0140] In some embodiments, the method of forming the fusion resin layer (122p) may include wrapping a polymer film around the perimeter of the MTB housing (122) as described with reference to FIGS. 5 and 9, and surrounding the side of the MTB housing (122) so that the polymer film partially overlaps. The portion where the polymer film overlaps has a locally increased thickness, and a laminate sheet may be laminated at this portion as described below.

[0141] In some embodiments, the method of forming the fusion resin layer (122p) may include providing a polymer ring around the periphery of the MTB housing (122) and using the same to form a protrusion. FIGS. 15 to 17 are drawings illustrating one embodiment of a method of forming the fusion resin layer (122p).

[0142] Referring to FIG. 15, a polymer ring (122pr) may be provided around the periphery of the MTB housing (122). The inner length of the polymer ring (122pr) is longer than the length of the outer circumference of the MTB housing (122). Therefore, the polymer ring (122pr) may be easily provided around the periphery of the MTB housing (122).

[0143] Referring to Fig. 16, a polymer ring (122pr) can be pressed against one side of the MTB housing (122). Fig. 16 illustrates a polymer ring (122pr) pressed against the side of the MTB housing (122) starting from the lower end of the MTB housing (122). However, the present invention is not limited thereto. In some embodiments, the polymer ring (122pr) can be pressed against the surface of the MTB housing (122) and fused.

[0144] Referring to Fig. 17, a polymer ring (122pr) of residual length remains on a specific portion of the MTB housing (122). This is because the inner length of the polymer ring (122pr) is longer than the length of the outer circumferential surface of the MTB housing (122). The remaining length portion of the polymer ring (122pr) can be mutually fused so that the inner surfaces of the polymer rings (122pr) face each other.

[0145] The portion where the remaining length of the polymer ring (122pr) is mutually fused forms a locally increased thickness of the fused resin layer (122p). The laminate resin (130) may be laminated at the portion where the remaining length of the polymer ring (122pr) is mutually fused. In some embodiments, tension may be applied to the polymer ring (122pr) when the polymer ring (122pr) is pressed along the surface of the MTB housing (122). In some embodiments, the position where tension is applied to the polymer ring (122pr) may be the remaining length of the polymer ring (122pr).

[0146] In some embodiments, the remaining length of the polymer ring (122pr) may be positioned at the center of the secondary battery (100) in the first direction (e.g., X-axis direction). That is, the remaining length of the polymer ring (122pr) may be positioned at the center of the MTB housing (122) in the first direction (e.g., X-axis direction).

[0147] Fig. 18 is a drawing showing another embodiment of a method for forming a fusion resin layer (122p), showing the results performed subsequent to Fig. 16.

[0148] Referring to FIG. 18, the remaining length portion of the polymer ring (122pr) may be positioned close to a corner of the MTB housing (122). A person skilled in the art will be able to position the remaining length portion of the polymer ring (122pr) as described with reference to FIG. 6.

[0149] Although FIGS. 12 to 14 illustrate that the MTB (120) is bonded to both ends of the stacked electrode assembly (110) and then a fusion resin layer (122p) is formed around the MTB housing (122), the present invention is not limited thereto. In some other embodiments, the MTB (120) may be bonded to both ends of the stacked electrode assembly (110) after the fusion resin layer (122p) is formed around the MTB housing (122).

[0150]

[0151] Referring to FIG. 12 and FIG. 19, the laminate sheet is bonded to the fusion resin layer (122p) to wrap the side of the stacked electrode assembly (110) (S130).

[0152] The laminate sheet (130) may have a pair of substantially parallel edge portions (130e) that may be fused to the outer side surfaces of the MTBs (120). Meanwhile, a pair of substantially parallel end portions (130t) connecting the pair of edge portions (130e) of the laminate sheet (130) may have a portion that is not fused to each other, and a portion of the stacked electrode assembly (110) may be exposed between the pair of end portions (130t).

[0153] The joint portion (130m) where the above pair of terminal portions (130t) are fused can be positioned adjacent to a locally thickened portion of the fused resin layer (122p) described above.

[0154] Thereafter, an electrolyte can be supplied to the stacked electrode assembly (110) through the non-fused portion of the pair of terminal portions (130t) (S140).

[0155] In some embodiments, the step of supplying the electrolyte may be performed after attaching the laminate sheet (130) to the MTBs (120). In some embodiments, the step of supplying the electrolyte may be performed after sealing the laminate sheet. In this case, at least one of the MTBs (120) may include an electrolyte injection port.

[0156] The above electrolyte may be a common electrolyte used for lithium secondary batteries and is not particularly limited.

[0157] When the electrolyte is supplied to the stacked electrode assembly (110) through the unfused portion of a pair of terminal portions (130t), the laminate sheet (130) can be sealed thereafter (S150). Specifically, the laminate sheet (130) can be sealed by laminating the terminal portions (130t) of the laminate sheet (130). In some embodiments, the terminal portions (130t) can be laminated by applying heat after the inner resin layers (132) of the terminal portions (130t) are brought into contact with each other. In other embodiments, the terminal portions (130t) can be laminated by applying heat after the inner resin layer (132) of one terminal portion (130t) is brought into contact with the outer resin layer (136) of the other terminal portion (130t).

[0158]

[0159] (Example 4)

[0160] FIG. 20 is a schematic perspective view of a battery pack (1) according to one embodiment of the present invention, FIG. 21 is an exploded perspective view schematically showing the configuration of the battery pack (1) of FIG. 20, and FIG. 22 is a perspective view showing the battery cells (100) of FIG. 21 mounted in a pack housing.

[0161] Referring to FIGS. 20 to 22, a battery pack (1) according to one embodiment of the present invention includes a plurality of battery cells (100), an electrical component assembly (500), a pack housing (300), and a pack cover (600).

[0162] The battery cells (100) are stacked in a first direction (e.g., X-axis direction), and a cooling pad (200) may be interposed between the battery cells. In some embodiments, the stack of the battery cells (100) and the cooling pad (200) may be stored directly within the pack housing (300) without being stored within another frame. However, a person skilled in the art will understand that various modifications are possible with respect to the method of storing the battery cells (100).

[0163] For example, a stack of the battery cells (100) and the cooling pads (200) may be housed in a module frame to form a battery module, and the battery modules may be housed in the pack housing (300). The module frame may be configured in the shape of a rectangular parallelepiped box that surrounds the outer surface of the stack of the battery cells (100) and the cooling pads (200) so that the stack of the battery cells (100) and the cooling pads (200) may be held inside. The module frame may be made of a metal material having high mechanical rigidity so as to sufficiently protect the battery cells (100) from swelling and external impact.

[0164] The electrical component assembly (500) may include a relay device, a current sensor, a fuse, a BMS (Battery Management System), an MSD (Manual Service Disconnector), etc. The relay device is a switching component that selectively opens and closes a charging / discharging path through which current flows, and can block the flow of charging / discharging current when an abnormality occurs in the battery pack (1). The BMS refers to a battery management device that overall controls the charging / discharging operation of battery cells (100), and can be said to be a component typically included in the battery pack (1). In addition, the MSD is a system for selectively cutting off the power of a high-voltage battery by a physical method, and cuts off the power by disconnecting the service plug when necessary.

[0165] This battery assembly (500) can be packaged together with battery cells (100) by a pack housing (300) and a pack cover (600) so as not to be exposed to the outside.

[0166] The pack housing (300) can be said to be a structure that provides a space for storing battery cells (100) and an electrical component assembly (200) inside and is provided with a bracket (332) or a mounting structure (343, 353) so that it can be coupled to the body of a vehicle.

[0167] The pack housing (300) provides mechanical support to the battery modules (100) and the electrical component assembly (500) and protects them from external impacts, etc., and therefore can be manufactured from a metal material with high rigidity.

[0168] The pack housing (300) according to the present embodiment may include a lower frame (310) provided in the form of a wide plate on which battery cells (100) can be mounted, a front frame (320), a rear frame (330), a right side frame (340), and a left side frame (350) that are vertically coupled along the edge of the lower frame (310) to form a wall. In addition, the pack housing (300) may further include a center beam (370) and cross beams (360) to define a space on which the battery cells (100) can be mounted. One end of the center beam (370) may be coupled to the front frame (320) and the other end may be coupled to the rear frame (330). In some embodiments, one end of the cross beam (360) may be coupled to the center beam (370) and the other end may be coupled to the right side frame (340) or the left side frame (350). In some embodiments, the crossbeam (360) may extend across the center beam (370) and have one end coupled to the right side frame (340) and the other end coupled to the left side frame (350).

[0169] In some embodiments, the lower frame (310), the front frame (320), the rear frame (330), the right side frame (340), the left side frame (350), and the cross beam (360) may each be an aluminum extrusion structure, and the pack housing (300) may be formed by welding and / or bolting the frames.

[0170] For example, by manufacturing the frames by extruding aluminum with a mixture of empty spaces and ribs inside and welding them to form the pack housing (300), the weight of the pack housing (300) can be reduced and the mechanical rigidity can have reliability exceeding the required level.

[0171] In some embodiments, a heat sink may be further provided within the pack housing (300). The heat sink may be provided in the form of a plate having a flow path therein to absorb and discharge heat from another object through thermal contact. In some embodiments, the lower frame (310) may include an inlet port (410a) through which cooling water may be introduced, an outlet port (410b) through which cooling water may be discharged, and a cooling water channel through which cooling water may flow.

[0172] The battery cells (100) may be electrically connected by inter-bus bars (510, 520, 530). The inter-bus bars may include a first inter-bus bar (510) that electrically connects the battery modules (100) arranged 2x2 along a first direction (e.g., X-axis direction) and a second direction (e.g., Y-axis direction). In some embodiments, the first inter-bus bar (510) may be provided at a position where the center beam (370) and the cross beam (360) intersect.

[0173] Additionally, the inter-busbars may include a second inter-busbar (520) that electrically connects the electrically connected battery cells (100) to an external load or charging system. The second inter-busbar (520) need not be directly connected to the external load or charging system, and may be connected to the external load or charging system through the electrical equipment assembly (500).

[0174] The above battery modules (100) may include a first group of battery cells (100A) positioned on one side of the center beam (370) and a second group of battery cells (100B) positioned on the other side. The inter-bus bars may include a third inter-bus bar (530) electrically connecting the first group of battery cells (100A) and the second group of battery cells (100B).

[0175] While the embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims. Therefore, modifications to future embodiments of the present invention will not depart from the scope of the invention.

[0176]

[0177] [Explanation of symbols]

[0178] 1: Battery pack

[0179] 100: Secondary battery

[0180] 110: Stacked electrode assembly

[0181] 111: Unit battery

[0182] 116: Electrode lead

[0183] 120, 120a, 120b: MTB

[0184] 122: MTB Housing

[0185] 122h: Penetration hole

[0186] 122p: Fusion resin layer

[0187] 122pe: Extension

[0188] 122pp: Protrusion

[0189] 124: Electrode terminal section

[0190] 125: Busbar

[0191] 128: Check valve

[0192] 130: Laminate sheet

[0193] 130e: Edge

[0194] 130m: Joint section

[0195] 130t: Terminal

[0196] 132: Inner resin layer

[0197] 134: Metal layer

[0198] 136: Outer resin layer

Claims

1. A stacked electrode assembly in which a plurality of unit cells are stacked in a first direction and have electrode leads at both ends in a second direction perpendicular to the first direction; A multifunctional terminal block (MTB) provided at both ends of the stacked electrode assembly; and A laminate sheet covering the side surface of the stacked electrode assembly; A secondary battery comprising a fused resin layer having a locally increased thickness on a side surface, wherein the MTB comprises:

2. In paragraph 1, A secondary battery characterized in that the above-mentioned fusion resin layer has a laminated portion at a location where the thickness is locally increased.

3. In paragraph 2, The above-mentioned fusion resin layer is a polymer film, A secondary battery characterized in that the thickness of the above-mentioned fusion resin layer is increased locally at a location where the number of times the polymer film is coated is greater than at other locations, thereby increasing the thickness.

4. In paragraph 2, A secondary battery, characterized in that the above-mentioned fusion resin layer includes an extension portion extending along a side surface of the MTB from an edge of the above-mentioned laminate sheet.

5. In paragraph 4, A secondary battery, characterized in that the thickness of the fusion resin layer at a location having the locally increased thickness in the extended portion is about 1.8 to about 2.2 times the thickness of the fusion resin layer at another location in the extended portion.

6. In paragraph 2, A secondary battery, characterized in that the above-mentioned joint is located substantially at the center of the secondary battery in the first direction.

7. In paragraph 2, The above-mentioned fusion resin layer is a polymer ring fused around the MTB housing of the MTB, A secondary battery, characterized in that the location where the fusion resin layer has a locally increased thickness is a location where tension is applied to the polymer ring when the polymer ring is fused to the periphery of the MTB housing.

8. In paragraph 7, A secondary battery, characterized in that the above-mentioned fusion resin layer extends at least partially between the above-mentioned bonding parts.

9. In paragraph 8, A secondary battery, characterized in that the length of the fusion resin layer extending between the bonding parts is about 0.1 mm to about 2 mm.

10. A step of connecting a multifunctional terminal block (MTB) to both ends of a stacked electrode assembly including a plurality of unit cells stacked in a first direction and having electrode leads at both ends in a second direction perpendicular to the first direction; A step of forming a fusion resin layer around the MTB housing of the above MTB; and A step of bonding the laminate sheet to the fusion resin layer so as to wrap the side surface of the stacked electrode assembly; Including, A method for manufacturing a secondary battery, wherein the above-mentioned fusion resin layer has a locally increased thickness, and the laminate sheet has a bonding portion at a location where the above-mentioned fusion resin layer has a locally increased thickness.

11. In Article 10, A method for manufacturing a secondary battery, characterized in that the step of forming the above-mentioned fusion resin layer includes a step of locally forming an overlapping layer of polymer films.

12. In paragraph 11, A method for manufacturing a secondary battery, characterized in that the polymer film is configured to locally overlap after wrapping around a side of the MTB housing.

13. In paragraph 10, The steps of forming the above-mentioned fusion resin layer are: A step of providing a polymer ring having an inner length longer than the length of an outer circumferential surface of the MTB housing around the periphery of the MTB housing; A step of fusing the polymer ring from one side of the MTB housing onto the side surface of the MTB housing; and A step of mutually fusing the remaining length of the above polymer rings; A method for manufacturing a secondary battery, characterized by including a.

14. In paragraph 13, A method for manufacturing a secondary battery, characterized in that in the step of mutually fusing the remaining length of the polymer rings, the position at which the polymer rings are mutually fused substantially coincides with the position at which the laminate sheet has a bonding portion.

15. In paragraph 10, Inside the above MTB housing: An electrode terminal electrically connected to the electrode lead of the above stacked electrode assembly; and A bus bar electrically connecting the electrode lead of the stacked electrode assembly and the electrode terminal portion; is provided, The above laminate sheets: A metal layer having flexibility; An internal resin layer provided on one side of the metal layer; and An outer resin layer provided on the other side of the above metal layer; Including, A method for manufacturing a secondary battery, characterized in that the inner resin layer includes casted polypropylene (CPP).

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