Rechargeable battery and method for manufacturing rechargeable battery

Abstract

The present invention relates to a rechargeable battery that can be charged and discharged and a method for manufacturing the rechargeable battery that can be charged and discharged. A rechargeable battery according to one embodiment of the present invention may comprise: a plurality of electrode assemblies each having an electrode tab bundle; an intermediate electrode interposed between the plurality of electrode assemblies; and a case for accommodating the plurality of electrode assemblies and the intermediate electrode.

Description

Secondary battery and method for manufacturing secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0002261, filed January 5, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a rechargeable secondary battery and a method for manufacturing a rechargeable secondary battery.

[0005] Unlike primary batteries, which are non-rechargeable, secondary batteries (rechargeable batteries) are rechargeable and dischargeable. Small secondary batteries are used in portable electronic devices such as cell phones, laptops, and camcorders, while medium- or large-sized secondary batteries are widely used as power sources for motors in hybrid vehicles and other vehicles.

[0006] These secondary batteries may have a shape in which an electrode assembly composed of electrodes and a separator is accommodated inside an outer case. At this time, each electrode in the electrode assembly has a non-coated portion (electrode tab) that is not coated with an active material, and these electrode tabs can be welded together to form a single electrode tab bundle. The electrode tab bundle is connected to an electrode lead, and the electrode lead can transmit the electric energy of the electrode assembly to the outside.

[0007] To increase the energy capacity of a secondary battery, it is advantageous to increase the thickness of the electrode assembly, which is housed within the outer packaging and generates electrical energy. However, when the electrode assembly becomes thicker, the electrode tabs must be longer to match the increased thickness of the electrode assembly in order to be welded together to form a bundle of electrode tabs. These increased electrode tabs are prone to tearing due to external impact or breaking during the electrode rolling process. Furthermore, when the length of the electrode tabs increases, the electrode tabs may be damaged when the electrode assembly expands (swelling) due to use of the secondary battery, as they cannot withstand the tensile force.

[0008] The present invention has been conceived in recognition of the above problems, and an object of the present invention is to provide a secondary battery and a method for manufacturing a secondary battery having improved energy capacity without increasing the length of an electrode tab.

[0009] A secondary battery according to one embodiment of the present invention may include a plurality of electrode assemblies each having a bundle of electrode tabs; a gap electrode interposed between the plurality of electrode assemblies; and a case accommodating the plurality of electrode assemblies and the gap electrode.

[0010] The secondary battery may further include an electrode lead connected to the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the inter-electrode.

[0011] The above electrode tab bundle may be a non-coated assembly in which the non-coated parts of the electrodes included in the above electrode assembly are welded.

[0012] The above plurality of electrode assemblies may include a first electrode assembly provided on the upper side of the inter-electrode; and a second electrode assembly provided on the lower side of the inter-electrode.

[0013] A first electrode tab bundle provided in the first electrode assembly may be welded to one side of the electrode lead, and a second electrode tab bundle provided in the second electrode assembly may be welded to the other side of the electrode lead.

[0014] The electrode lead may include a welding portion where the first electrode tab bundle and the second electrode tab bundle are welded together; and a protrusion connected to the joining portion and protruding outward from the case.

[0015] The above-mentioned joint portion may be formed thicker than the above-mentioned protrusion portion.

[0016] The above electrode may be welded to one side of the electrode lead together with the first electrode tab bundle, or may be welded to the other side of the electrode lead together with the second electrode tab bundle.

[0017] The outermost layer of the above electrode assembly may be composed of a separator.

[0018] The intervening electrode interposed between the plurality of electrode assemblies may be an anode.

[0019] Meanwhile, a method for manufacturing a secondary battery according to another embodiment of the present invention may include a preparation step of preparing a plurality of electrode assemblies each having a bundle of electrode tabs and a gap electrode; an electrode insertion step of interposing the gap electrode between the plurality of electrode assemblies; a connection step of connecting the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the gap electrode to an electrode lead; and a packaging step of accommodating the plurality of electrode assemblies and the gap electrode in a case.

[0020] The above connecting step may include a pre-welding step of welding the electrode tab of the intervening electrode between the plurality of electrode assemblies to the adjacent electrode tab bundle; and a main welding step of welding the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the intervening electrode to the electrode lead.

[0021] In the above pre-welding step, the electrode tab of the inter-electrode can be welded to a first electrode tab bundle of a first electrode assembly provided on the upper side, or to a second electrode tab bundle of a second electrode assembly provided on the lower side.

[0022] The above main welding step may include a step of welding the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the inter-electrode to the joint portion of the electrode lead.

[0023] In the above main welding step, a bundle of first electrode tabs of a first electrode assembly provided on the upper side of the inter-electrode may be welded to one side of the joint portion, and a bundle of second electrode tabs of a second electrode assembly provided on the lower side of the inter-electrode may be welded to the other side of the joint portion.

[0024] In the above electrode insertion step, the intervening electrode interposed between the plurality of electrode assemblies may be an anode.

[0025] A secondary battery according to one embodiment of the present invention may include a plurality of electrode assemblies each having a bundle of electrode tabs, an electrode interposed between the plurality of electrode assemblies, and a case housing the plurality of electrode assemblies and the electrodes. In this case, there is an advantageous effect of improving the energy capacity of the entire secondary battery without increasing the length of the electrode tabs included in each electrode assembly.

[0026] FIG. 1 is a cross-sectional view illustrating the internal structure of a secondary battery according to one embodiment of the present invention.

[0027] FIG. 2 is a drawing for explaining a state in which a side electrode is coupled to the upper side of an electrode lead in a secondary battery according to one embodiment of the present invention.

[0028] FIG. 3 is a drawing for explaining a state in which a side electrode is coupled to the lower side of an electrode lead in a secondary battery according to one embodiment of the present invention.

[0029] Figure 4 is a flowchart sequentially showing a secondary battery manufacturing method according to another embodiment of the present invention.

[0030] Figure 5 is a flowchart sequentially showing the connection steps of Figure 4.

[0031] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0032] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0033] In addition, terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0034] Hereinafter, a secondary battery and a method for manufacturing a secondary battery according to the present invention will be described with reference to the drawings.

[0035]

[0036] secondary battery

[0037] Fig. 1 is a cross-sectional view illustrating the internal structure of a secondary battery according to one embodiment of the present invention. Fig. 2 is a drawing illustrating a state in which a gap electrode is coupled to the upper side of an electrode lead in a secondary battery according to one embodiment of the present invention. Fig. 3 is a drawing illustrating a state in which a gap electrode is coupled to the lower side of an electrode lead in a secondary battery according to one embodiment of the present invention.

[0038] Referring to FIGS. 1 to 3, a secondary battery (10) according to the present invention may include a plurality of electrode assemblies (100, 200) each having a bundle of electrode tabs (130, 230), a spacer electrode (300) interposed between the plurality of electrode assemblies (100, 200), and a case (500) that accommodates the plurality of electrode assemblies (100, 200) and the spacer electrode (300). In this case, the electrode tab bundles (130, 230) are separately provided in each electrode assembly (100, 200), so that even when a plurality of electrode assemblies (100, 200) are included in the case (500), there is an advantageous effect that the length of the electrode tab bundles (130, 230) does not increase.

[0039] Here, the electrode assembly (100, 200) is an assembly composed of electrodes (110, 210) and separators (120, 220) interposed between the electrodes (110, 210), and may have various structures. For example, as illustrated in FIGS. 1 to 3, the electrode assembly (100, 200) may have a stacked structure in which a plurality of electrodes (110, 210) and separators (120, 220) are alternately stacked.

[0040] In addition, although not shown in FIGS. 1 to 3, the electrode assembly (100, 200) may have a stack-folding structure in which electrodes (110, 210) and separators (12, 220) are laminated and folded, or may have a jelly-roll structure in which a laminate in which electrodes (110, 210) and separators (120, 220) are laminated and rolled up.

[0041] Meanwhile, the electrode (110, 210) included in the electrode assembly (100, 200) is an anode or a cathode, and the electrode assembly (100, 200) can be accommodated inside the case (500) in a state of being impregnated with an electrolyte.

[0042] The anode has a structure in which a composite material comprising an active material, a conductive material, and a binder is applied to a thin plate made of a metal such as aluminum, and a coating layer may be formed on a portion of the anode. At this time, the non-coated portion of the anode where the coating layer is not formed becomes a cathode tab, and these cathode tabs can be welded together to form a bundle of cathode tabs.

[0043] The cathode emits electrons through a connected conductor and may have a structure in which an active material or the like is applied to a cathode substrate composed of a thin metal plate. A coating layer may be formed on a portion of the cathode, and the uncoated portion of the cathode may become a cathode tab. These cathode tabs may be welded together to form a bundle of cathode tabs.

[0044] The separator (120, 220) is a thin film of insulating material interposed between the electrodes (110, 210), and electrodes (110, 210) having different polarities may be positioned on one side and the other side of the separator (120, 220), respectively. That is, the separator (120, 220) can block direct contact between the positive and negative electrodes. In addition, the separator (120, 220) may have a plurality of pores having a diameter of 1 μm or less through which cations such as lithium pass. The separator (120, 220) may be composed of various materials. For example, a synthetic resin such as polyethylene (PE) or polypropylene (PP) may be used for the separator (120, 220).

[0045] The electrode tab bundle (130, 230) may be the positive tab bundle or the negative tab bundle described above. These electrode tab bundles (130, 230) are formed for each electrode assembly (100, 200), so that the length of the electrode tab bundle (130, 230) can be maintained constant regardless of the number of electrode assemblies (100, 200) included in the case (500).

[0046] Specifically, when only one electrode assembly is accommodated inside the case (500), the length of the electrode tab bundle of the electrode assembly becomes longer as the thickness of the electrode assembly becomes thicker. The electrode tab bundle is formed by welding after the electrode tabs (electrode non-coated portions) constituting the electrode assembly are folded, and this is because the length of the folded portion of the electrode tabs increases as the thickness of the electrode assembly becomes thicker.

[0047] Unlike the above case where a single electrode assembly is formed thickly, the secondary battery (10) according to the present invention increases the total energy capacity in a manner in which multiple separate electrode assemblies (100, 200) having a constant thickness are included inside the case (500). Here, the electrode tab bundles (130, 230) are formed for each electrode assembly (100, 200), so that the length at which each of the electrode tabs constituting the electrode tab bundle (130, 230) is folded can always be maintained constant.

[0048] Accordingly, the secondary battery (10) according to the present invention has the advantageous effect of improving the overall energy capacity without increasing the length of the electrode tabs. In addition, in the secondary battery (10) according to the present invention, the lengths of the electrode tabs constituting the electrode tab bundle (130, 230) are kept relatively short, which has the advantageous effect of preventing the electrode tabs from being easily torn by external impact or from being easily broken during the electrode rolling process.

[0049] Meanwhile, the inter-electrode (300) is an electrode interposed between a plurality of electrode assemblies (100, 200), and one side and the other side of the inter-electrode (300) may be in contact with a separator (120, 220) included in the electrode assembly (100, 200), respectively. That is, the outermost layer of the plurality of electrode assemblies (100, 200) may be composed of a separator (120, 220).

[0050] In addition, the inter-electrode (300) is the same electrode plate as the electrode (110, 210) included in the electrode assembly (100, 200), and can be a positive electrode or a negative electrode. In this case, when the inter-electrode (300) is configured as a positive electrode plate, there is an advantageous effect of further improving the overall energy capacity of the secondary battery (10).

[0051] Meanwhile, the electrode tab bundles (130, 230) and the inter-electrode (300) included in each of the plurality of electrode assemblies (100, 200) may be connected to the electrode lead (400). The electrode tab bundles (130, 230) and the inter-electrode (300) may be connected to the electrode lead (400) in various ways. For example, the electrode uncoated portion of the inter-electrode (300) and the electrode tab bundles (130, 230) may be welded to the electrode lead (400).

[0052] The electrode-free region of the interelectrode (300) is a region of the interelectrode (300) where the active material is not coated, and may be a positive electrode-free region or a negative electrode-free region. This electrode-free region of the interelectrode (300) may be welded to the electrode tab bundle (130, 230) in a folded state to one side or the other.

[0053] The case (500) is an outer material that accommodates a plurality of electrode assemblies (100, 200) and a gap electrode (300). The plurality of electrode assemblies (100, 200) and the gap electrode (300) can be accommodated inside the case (500) while being impregnated with an electrolyte. The case (500) can be made of various materials. For example, the case (500) can be a square case made of a metal such as aluminum or a material such as resin. In addition, the case (500) can be a pouch-shaped outer material made of a laminate sheet made of an inner resin layer, a metal layer, and an outer resin layer.

[0054] When the case (500) is a pouch-type outer material, the metal layer can serve as a substrate that maintains mechanical strength and a barrier layer that prevents the infiltration of moisture and oxygen. In addition to the function of preventing the inflow or leakage of foreign substances such as gas and moisture, the metal layer can be composed of aluminum or an aluminum alloy so that it can have the function of improving the strength of the battery case. Alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, 3105, etc. can be used as the aluminum alloy, and these can be used alone or in combination of two or more.

[0055] The external resin layer coated on the outer surface of the metal layer must have excellent resistance to the external environment in order to protect the electrode assembly from the outside. Therefore, the external resin layer is required to have excellent tensile strength and corrosion resistance relative to its thickness. Polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene and polypropylene, etc. can be used for this external resin layer.

[0056] The inner resin layer coated on the inner surface of the metal layer may be composed of a polyolefin-based resin. For example, the inner resin layer may be composed of CPP (Casted Polypropylene), chlorinated polypropylene, polyethylene, ethylene propylene copolymer, polyethylene and acrylic acid copolymer, and polypropylene and acrylic acid copolymer.

[0057] Meanwhile, the case (500) may be configured in various ways. For example, the case (500) may be configured with an upper case (510) and a lower case (520), and the upper case (510) and the lower case (520) may be coupled to each other to form a receiving space for accommodating a plurality of electrode assemblies (100, 200). Here, the upper case (510) and the lower case (520) may be coupled in various ways. For example, the upper case (510) and the lower case (520) may be coupled by a method such as welding or heat fusion.

[0058] Meanwhile, the electrode assemblies (100, 200) may include a first electrode assembly (100) provided on top of the inter electrode (300) and a second electrode assembly (200) provided on the bottom of the inter electrode (300). That is, the secondary battery (10) according to the present invention may have a two-stage structure in which the first electrode assembly (100) and the second electrode assembly (200) are stacked with the inter electrode (300) interposed therebetween.

[0059] Here, the first electrode tab bundle (130) provided in the first electrode assembly (100) may be welded to one side of the electrode lead (400), and the second electrode tab bundle (230) provided in the second electrode assembly (200) may be welded to the other side of the electrode lead (400). In addition, the electrode uncoated portion of the inter-electrode (300) may be welded to one side of the electrode lead (400) together with the first electrode tab bundle (130), or may be welded to the other side of the electrode lead (400) together with the second electrode tab bundle (230).

[0060] Meanwhile, the electrode lead (400) may include a joining portion (410) in which the first electrode tab bundle (130), the second electrode tab bundle (230), and the electrode blank portion of the inter-electrode (300) are welded together, and a protrusion (420) connected to the joining portion (410) and protruding outward from the case (500). Here, the joining portion (410) may be formed thicker than the protrusion (420).

[0061] That is, since the first electrode tab bundle (130), the second electrode tab bundle (230), and the electrode non-coated portion of the inter-electrode (300) are welded to the thick joint portion (410), even when heat and pressure are applied to the joint portion (410), the joint portion (410) can be prevented from being broken. Accordingly, the worker can increase the welding strength between the electrode non-coated portion of the first electrode tab bundle (130), the second electrode tab bundle (230), and the inter-electrode (300) and the joint portion (410), and even when an external impact, etc., is applied to the secondary battery (10), there is an advantageous effect of being able to prevent the joint between the electrode non-coated portion of the first electrode tab bundle (130), the second electrode tab bundle (230), and the inter-electrode (300) and the joint portion (410) from being separated.

[0062] Meanwhile, the connecting portion (410) and the protrusion (420) may have various shapes. Specifically, the connecting portion (410) may have a rectangular box shape with a fillet formed at the corner portion, and the protrusion (420) may have a terminal shape that protrudes outward from one surface of the connecting portion (410) toward the outside of the case (500).

[0063] The upper case (510) and lower case (520) described above are joined by heat fusion or the like to form a sealed internal space, and a terminal-shaped protrusion (420) can pass between the upper case (510) and the lower case (520). At this time, a sealing member that seals the internal space of the case (500) can be interposed between the upper case (510) and the lower case (520) and the protrusion (420).

[0064] The first electrode tab bundle (130), the second electrode tab bundle (230), and the electrode uncoated portion of the inter electrode (300) can be variously coupled to the coupling portion (410). For example, as illustrated in FIG. 2, the first electrode tab bundle (130) and the electrode uncoated portion of the inter electrode (300) can be coupled to an upper surface of the coupling portion (410), and the second electrode tab bundle (230) can be coupled to a lower surface of the coupling portion (410). In addition, as illustrated in FIG. 3, the first electrode tab bundle (130) can be coupled to an upper surface of the coupling portion (410), and the second electrode tab bundle (230) and the electrode uncoated portion of the inter electrode (300) can be coupled to a lower surface of the coupling portion (410).

[0065]

[0066] Secondary battery manufacturing method

[0067] Figure 4 is a flowchart sequentially showing a secondary battery manufacturing method according to another embodiment of the present invention.

[0068] Referring to FIG. 4, a method for manufacturing a secondary battery according to the present invention may include a preparation step (S100) of preparing a plurality of electrode assemblies (100, 200) each having an electrode tab bundle (130, 230) and a gap electrode (300), an electrode insertion step (S200) of interposing a gap electrode (300) between the plurality of electrode assemblies (100, 200), a connection step (S300) of connecting the electrode tabs of the electrode tab bundles (130, 230) and the gap electrode (300) of each of the plurality of electrode assemblies (100, 200) to an electrode lead (400), and a packaging step (S400) of accommodating the plurality of electrode assemblies (100, 200) and the gap electrode (300) in a case (500).

[0069] In this case, the electrode tab bundles (130, 230) of the manufactured secondary battery (10) are provided separately for each electrode assembly (100, 200), so that even when a plurality of electrode assemblies (100, 200) are included in the case (500), there is an advantageous effect that the length of the electrode tab bundles (130, 230) does not become longer.

[0070] Meanwhile, the preparation step (S100) is a step of preparing a plurality of electrode assemblies (100, 200) and a gap electrode (300), and each of the plurality of electrode assemblies (100, 200) may be provided with a bundle of electrode tabs (130, 230). The gap electrode (300) is the same electrode plate as the electrode (110, 210) included in the electrode assembly (100, 200), and may be a positive electrode or a negative electrode.

[0071] Here, the electrode tab bundles (130, 230) are formed for each electrode assembly (100, 200), and the lengths of the electrode tabs that are folded and welded to form the electrode tab bundles (130, 230) can be maintained constant. Specifically, the electrode non-conductive portions (electrode tabs) of the electrodes (110, 210) included in each electrode assembly (100, 200) are folded and then welded together to form the electrode tab bundles (130, 230), and the thickness of the electrode assemblies (100, 200) is predetermined, and the lengths of the electrode tabs that are folded and welded can always be maintained constant.

[0072] The electrode insertion step (S200) is a step of interposing a gap electrode (300) between electrode assemblies (100, 200) each having electrode tab bundles (130, 230) formed thereon, and may be a step of improving the overall energy capacity of the secondary battery (10). For example, the electrode insertion step (S200) may be a step of forming a laminate by stacking electrode assemblies (100, 200) each having electrode tab bundles (130, 230) formed thereon and gap electrodes (300) vertically.

[0073] Since this laminate is not formed by a single thick electrode assembly, but by merging a plurality of electrode assemblies (100, 200), the length of the electrode tab bundle (130, 230) can always be maintained constant. That is, according to the secondary battery manufacturing method of the present invention, a secondary battery (10) with improved overall energy capacity can be manufactured without increasing the length of the electrode tabs.

[0074] Meanwhile, the worker can insert a positive electrode (300) between the electrode assemblies (100, 200) in the electrode insertion step (S200). In this case, there is a beneficial effect of further improving the overall energy capacity of the secondary battery (10).

[0075] The connection step (S300) is a step of connecting the electrode tab bundle (130, 230) and the electrode tab (electrode uncoated portion) of the inter-electrode (300) to the electrode lead (400), and can be configured in various ways. Here, the electrode tab bundle (130, 230) and the electrode uncoated portion of the inter-electrode (300) can be connected to the electrode lead (400) in various ways. For example, the electrode tab bundle (130, 230) and the electrode uncoated portion of the inter-electrode (300) can be welded to the electrode lead (400).

[0076] The packaging step (S400) is a step of packaging a plurality of electrode assemblies (100, 200) and a spacer electrode (300), and may be configured in various ways. For example, the packaging step (S400) may be a step of inserting a laminate composed of a plurality of electrode assemblies (100, 200) and a spacer electrode (300) into the interior of a case (500) composed of an upper case (510) and a lower case (520), and then joining the upper case (510) and the lower case (520) by heat fusion or welding. When the upper case (510) and the lower case (520) are joined, the internal space of the case (500) into which the laminate is inserted may be sealed from the outside.

[0077] Figure 5 is a flowchart sequentially showing the connection steps of Figure 4.

[0078] Referring to FIG. 5, the connection step (S300) may include a pre-welding step (S310) of welding the electrode-free portion of the intervening electrode (300) between the plurality of electrode assemblies (100, 200) to an adjacent electrode tab bundle (130, 230), and a main welding step (S320) of welding the electrode-free portion of the intervening electrode (300) and the electrode tab bundle (130, 230) of each of the plurality of electrode assemblies (100, 200) to the electrode lead (400).

[0079] In the pre-welding step (S310), the electrode-free portion of the inter-electrode (300) can be welded to the first electrode tab bundle (130) of the first electrode assembly (100) provided on the upper side, or to the second electrode tab bundle (230) of the second electrode assembly (200) provided on the lower side.

[0080] Here, the electrode-free region of the interelectrode (300) is a region where the interelectrode (300) is not coated with an active material, and may be a positive electrode-free region or a negative electrode-free region. In the pre-welding step (S310), the electrode-free region of the interelectrode (300) may be welded to the electrode tab bundle (130, 230) in a folded state to one side or the other side.

[0081] Specifically, the pre-welding step (S310) may be a step of welding the electrode uncoated portion of the interelectrode (300) and the first electrode tab bundle (130) while the electrode uncoated portion of the interelectrode (300) is folded to one side. In addition, the pre-welding step (S310) may be a step of welding the electrode uncoated portion of the interelectrode (300) and the second electrode tab bundle (230) while the electrode uncoated portion of the interelectrode (300) is folded to the other side.

[0082] When the electrode-free portion of the inter-electrode (300) is welded to the first electrode tab bundle (130) to form a welded body, this welded body can be welded to the upper surface of the electrode lead (400) in the main welding step (S320). At this time, the second electrode tab bundle (230) can be welded to the lower surface of the electrode lead (400).

[0083] When the electrode-free portion of the inter-electrode (300) is welded to the second electrode tab bundle (230) to form a welded body, this welded body can be welded to the lower surface of the electrode lead (400) in the main welding step (S320). At this time, the first electrode tab bundle (130) can be welded to the upper surface of the electrode lead (400).

[0084] Meanwhile, the main welding step (S320) may be a step of welding the electrode tab bundle (130, 230) of each of the first and second electrode assemblies (100, 200) and the electrode bare portion of the inter-electrode (300) to the joining portion (410) of the electrode lead (400).

[0085] Specifically, when the electrode-free portion of the inter-electrode (300) is welded to the first electrode tab bundle (130) to form a welded body, this welded body can be welded to the upper surface of the joint portion (410) in the main welding step (S320). At this time, the second electrode tab bundle (230) can be welded to the lower surface of the joint portion (410).

[0086] In addition, when the electrode-free portion of the inter-electrode (300) is welded to the second electrode tab bundle (230) to form a welded body, this welded body can be welded to the lower surface of the joint portion (410) in the main welding step (S320). At this time, the first electrode tab bundle (130) can be welded to the upper surface of the joint portion (410).

[0087] Here, the first electrode tab bundle (130), the second electrode tab bundle (230), and the electrode non-coated portion of the inter-electrode (300) are welded to one side and / or the other side of the thick joint portion (410), so that even when heat and pressure are applied to the joint portion (410), the joint portion (410) can be prevented from being broken. Accordingly, the worker can increase the welding strength between the electrode non-coated portion of the first electrode tab bundle (130), the second electrode tab bundle (230), and the inter-electrode (300) and the joint portion (410), so that even when an external impact, etc., is applied to the secondary battery (10), there is an advantageous effect of being able to prevent the joint between the electrode non-coated portion of the first electrode tab bundle (130), the second electrode tab bundle (230), and the inter-electrode (300) and the joint portion (410) from being separated.

[0088] Meanwhile, when the upper case (510) and the lower case (520) are joined by heat fusion or welding in the packaging step (S400), a protrusion (420) formed protruding from one surface of the joining portion (410) may be interposed between the upper case (510) and the lower case (520). At this time, a sealing member for sealing the internal space of the case (500) may be interposed between the upper case (510) and the lower case (520) and the protrusion (420).

[0089]

[0090] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0091]

[0092] [Explanation of symbols]

[0093] 10: Secondary battery 100, 200: Electrode assembly

[0094] 110, 210: Electrode 120, 220: Separator

[0095] 130, 230: Electrode tab bundle 300: Intermediate electrode

[0096] 400: Electrode lead 410: Joint

[0097] 420: Protrusion 500: Case

[0098] 510: Upper case 520: Lower case

Claims

1. A plurality of electrode assemblies, each having a bundle of electrode tabs; A spacer electrode interposed between the plurality of electrode assemblies; and A secondary battery comprising a case accommodating the plurality of electrode assemblies and the interlayer electrode.

2. In claim 1, A secondary battery further characterized by including an electrode tab bundle of each of the plurality of electrode assemblies and an electrode lead connected to the electrode tab of the inter-electrode.

3. In claim 2, A secondary battery characterized in that the above electrode tab bundle is a non-woven assembly in which the non-woven parts of the electrodes included in the above electrode assembly are welded.

4. In claim 2, The above plurality of electrode assemblies, A first electrode assembly provided on the upper portion of the above-mentioned inter-electrode; and A secondary battery characterized by including a second electrode assembly provided below the above-mentioned inter-electrode.

5. In claim 4, The first electrode tab bundle provided in the first electrode assembly is welded to one side of the electrode lead, A secondary battery, characterized in that the second electrode tab bundle provided in the second electrode assembly is welded to the other side of the electrode lead.

6. In claim 5, The above electrode leads are, A joint in which the first electrode tab bundle and the second electrode tab bundle are welded together; and A secondary battery characterized by including a protrusion connected to the above-mentioned connecting portion and protruding outwardly from the case.

7. In claim 6, A secondary battery, characterized in that the above-mentioned connecting portion is formed thicker than the above-mentioned protrusion portion.

8. In claim 5, A secondary battery, characterized in that the above-mentioned inter-electrode is welded to one side of the electrode lead together with the first electrode tab bundle, or is welded to the other side of the electrode lead together with the second electrode tab bundle.

9. In claim 1, A secondary battery, characterized in that the outermost layer of the electrode assembly is composed of a separator.

10. In claim 1, A secondary battery, characterized in that the intervening electrode interposed between the plurality of electrode assemblies is a positive electrode.

11. A preparatory step of preparing a plurality of electrode assemblies and a middle electrode, each having a bundle of electrode tabs; An electrode insertion step for interposing the intervening electrode between the plurality of electrode assemblies; A connecting step for connecting the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the inter-electrode to the electrode lead; and A method for manufacturing a secondary battery, comprising a packaging step of accommodating the plurality of electrode assemblies and the inter-electrode in a case.

12. In claim 11, The above connection steps are: A pre-welding step of welding the electrode tab of the intervening electrode between the plurality of electrode assemblies to the adjacent electrode tab bundle; and A method for manufacturing a secondary battery, characterized by including a main welding step of welding the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the inter-electrode to the electrode lead.

13. In claim 12, In the above pre-welding step, A method for manufacturing a secondary battery, characterized in that the electrode tab of the above-mentioned inter-electrode is welded to a bundle of first electrode tabs of a first electrode assembly provided on the upper side or to a bundle of second electrode tabs of a second electrode assembly provided on the lower side.

14. In claim 12, The above main welding step is, A method for manufacturing a secondary battery, characterized in that it includes a step of welding the electrode tab bundle of each of the plurality of electrode assemblies and the electrode tab of the inter-electrode to a joint portion of an electrode lead.

15. In claim 14, In the above main welding step, The first electrode tab bundle of the first electrode assembly provided on the upper side of the above-mentioned inter-electrode is welded to one side of the above-mentioned joint, A method for manufacturing a secondary battery, characterized in that a bundle of second electrode tabs of a second electrode assembly provided on the lower side of the above-mentioned inter-electrode is welded to the other side of the joining part.

16. In claim 11, A method for manufacturing a secondary battery, characterized in that in the electrode insertion step, the intervening electrode interposed between the plurality of electrode assemblies is a positive electrode.

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