Jelly-roll electrode arrangement and cylindrical lithium secondary battery with the same

Abstract

Jelly roll electrode assembly comprising: a first separator (4); a positive electrode (3) stacked on a surface of the first separator (4) and having a positive electrode (3) current collector; a second separator (2) provided on a surface opposite to a surface of the positive electrode (3) adjacent to the first separator (4); and a negative electrode (1) having a negative electrode current collector provided on a surface opposite a surface of the second separator (2) adjacent to the positive electrode (3), wherein the jelly-roll electrode assembly defines a jelly-roll hollow section in a core part thereof, where the current collector of the negative electrode has: a coated portion of the negative electrode to which a negative electrode active material (16) is applied; and uncoated sections (15) of the negative electrode to which the active material (16) of the negative electrode is not applied, wherein the non-coated portions (15) of the negative electrode are formed at two opposite ends of the negative electrode (1), wherein at least one of the uncoated portions (15) of the negative electrode has a tab (10) of the negative electrode, wherein each of at least one protective tape (11, 12) is provided on a respective surface of one of the non-coated portions (15) of the negative electrode of the negative electrode current collector, and wherein each protective band (11, 12) is formed to cover 50% or more of the surface of the non-coated portion (15) of the negative electrode of the negative electrode current collector.

Description

[Technical field]

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0174846, filed on December 8, 2021, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a jelly roll electrode assembly and a cylindrical lithium secondary battery having the same. [State of the art]

[0003] The rapid increase in the use of fossil fuels has increased the need for alternative energy or clean energy. Power generation and power accumulation using an electrochemical reaction have been the most actively studied in the field of alternative energy or clean energy.

[0004] Currently, a representative example of an electrochemical element that utilizes electrochemical energy is a secondary battery. The field of application of secondary batteries is gradually expanding.

[0005] As technology advances and mobile device requirements increase, there is a rapidly growing need for rechargeable batteries as power sources. Among secondary batteries, a lithium secondary battery is commercially available and widely used. The lithium secondary battery exhibits high energy density, high voltage, extended cycle life, and low self-discharge rate. Furthermore, research is underway on a method for manufacturing a high-density electrode with a higher energy density per unit volume than an electrode for the high-capacity lithium secondary battery.

[0006] Generally, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode contains a negative electrode active material that intercalates and deintercalates lithium ions released from the positive electrode. Silicon-based particles with high discharge capacity can be used as the negative electrode active material.

[0007] The positive electrode of a lithium secondary battery is typically made using a compound in which lithium is intercalated, such as LiCoO2 or LiMn2O4. The negative electrode is made using a carbon-based or Si-based material in which lithium is not intercalated. The lithium ions intercalated into the positive electrode move through the electrolyte to the negative electrode during a charging process. The lithium ions move from the negative electrode back to the positive electrode during a discharging process.

[0008] Lithium secondary batteries are used in various shapes, such as cylindrical, pouch, and angled, depending on the intended application. A cylindrical cell in the related art is configured such that a separator is disposed on an outermost side of the cylindrical cell after a winding process. In a structure in which the separator is disposed on an outer periphery, the separator surrounds the entire cell, and the cylindrical cell is electrically connected to an external battery case (battery can) through a positive electrode tab and a negative electrode tab.

[0009] The cylindrical cell according to the prior art has a structure in which the positive electrode, the separator, the negative electrode, and the separator are wound in this order, and the separator is exposed to an outermost periphery. In contrast, a Cu foil has an outermost peripheral structure in which the negative electrode, the separator, the positive electrode, and the separator are wound, and the Cu foil is exposed to an outermost periphery. The Cu foil can be in direct contact with an inner wall of the external battery case of the cylindrical cell and electrically connected to the external battery case, so that the Cu foil can advantageously replace the outer tab of the negative electrode.

[0010] However, if the Cu foil is not in proper contact with the external battery case, a problem arises in that the resistance increases, and the resistance varies depending on the outer diameter of a jelly roll. Unlike a structure in the related art in which a separator is arranged on an outer periphery, the Cu foil is arranged on the outermost periphery, so that the two separators are present in the Cu foil, surrounding the positive electrode.

[0011] The thickness of the Cu foil, which serves as a negative electrode current collector, tends to gradually decrease. Specifically, a jelly-roll electrode assembly is manufactured by attaching the tab to a non-coated portion of a core part of the negative electrode current collector and starting the winding process around the core part. In this case, the non-coated portion of the core part of the negative electrode current collector is folded simultaneously with the winding process. The fold extends as a fold of the negative electrode, causing a problem that the jelly-roll electrode assembly is wound in a folded state.

[0012] Therefore, studies were conducted to prevent wrinkles in the electrode of the core part in the jelly-roll electrode assembly, in which the Cu foil, which is the current collector of the negative electrode, defines the outermost periphery. <Dokument des Stands der Technik>

[0013] (Patent Document 1) Japanese Patent Application Laid-Open No. 2009-080971 [Detailed description of the invention][Technical problem]

[0014] The present application relates to a jelly roll electrode assembly and a cylindrical lithium secondary battery having the same. [Technical solution]

[0015] An embodiment of the present description provides a jelly roll electrode assembly comprising: a first separator; a positive electrode stacked on a surface of the first separator and having a positive electrode current collector; a second separator provided on a surface opposite a surface of the positive electrode abutting against the first separator;and a negative electrode having a negative electrode current collector provided on a surface opposite to a surface of the second separator abutting against the positive electrode, the jelly roll electrode assembly having a structure wound around the negative electrode, defining a jelly roll hollow portion in a core part, the negative electrode current collector comprising: a negative electrode coated portion to which a negative electrode active material is applied;and uncoated portions of the negative electrode to which the negative electrode active material is not applied, wherein the uncoated portions of the negative electrode are formed at two opposite ends of the negative electrode, wherein at least one of the uncoated portions of the negative electrode has a negative electrode tab, wherein a protective tape is provided on at least one surface of the uncoated portion of the negative electrode of the negative electrode current collector, and wherein the protective tape satisfies the following expression 1.; 50%≤a≤100%, where a in Expression 1 represents: (a length of the protective tape attached to the uncoated portion of the negative electrode / a total length of the uncoated portion of the negative electrode) × 100.

[0016] Another embodiment provides a cylindrical lithium secondary battery including a battery outer material; the jelly-roll electrode assembly according to the present application provided in the battery outer material; and an outer lid having an electrode provided in an opening portion of the battery outer material. [Beneficial Effects]

[0017] The jelly-roll electrode assembly according to the present application is the jelly-roll electrode assembly having the structure wound around the negative electrode while defining the jelly-roll hollow portion in the core part to implement the structure in which the negative electrode current collector is arranged at the outermost periphery. The negative electrode non-coated portion of the negative electrode current collector includes the protective tape satisfying Expression 1 and provided on at least one surface thereof. Therefore, even though the winding process is performed around the central portion of the negative electrode current collector with a small thickness, the protective tape provides rigidity to the negative electrode current collector, making it possible to prevent the occurrence of a crease during the winding process and thus prevent electrode crease in the entire electrode.Therefore, it is possible to provide the jelly roll electrode assembly without wrinkles.

[0018] The jelly-roll electrode assembly according to the present application is configured such that the protective tape is formed to cover 50% or more of at least one surface of the uncoated portion of the negative electrode of the negative electrode current collector and is formed on one surface or two opposite surfaces of the uncoated portion of the negative electrode. In this way, electrode wrinkles can be avoided, and the cycle life and efficiency of the cylindrical lithium secondary battery with the jelly-roll electrode assembly can be improved. [Brief description of the drawings] Fig. 1 is a view illustrating a method of winding a jelly roll electrode assembly according to an embodiment of the present application. Fig. 2 is a view illustrating a method of manufacturing the jelly roll electrode assembly having a structure in which a separator is arranged at an outermost periphery. Fig. 3 is a side view illustrating the jelly roll electrode assembly according to the embodiment of the present application in a state before a winding process. Fig. 4 is a view illustrating a core part of a negative electrode according to the present application. Fig. 5 is a view illustrating a negative electrode according to Example 1 of the present application. Fig. 6 is a view illustrating a negative electrode according to Comparative Example 1 of the present application. Fig. 7 is a view showing whether the negative electrode according to Comparative Example 1 of the present application has a wrinkle. [Explanation of reference signs and symbols] 1 negative electrode 2 second separator 3 positive electrode 4 first separator 5 Current collector of the negative electrode 10 Negative electrode tab 11 protective tape provided on the surface of a first uncoated portion of the negative electrode 12 protective tape provided on the surface of a second uncoated portion of the negative electrode 13 Positive electrode tab 14 uncoated section of the positive electrode 15 uncoated section of the negative electrode 16 layer of negative electrode active material 17 Layer of active material of the positive electrode 21 Total length of a first uncoated section of the negative electrode 22 Total length of a second uncoated section of the negative electrode 23 Length of a protective tape provided on a surface of a first uncoated portion of the negative electrode 24 Length of a protective tape provided on a surface of a second uncoated portion of the negative electrode 100 Jelly Roll Hollow Sections [Best Mode]

[0019] Before describing the present disclosure, some terms are defined in advance.

[0020] Throughout this specification, unless expressly stated otherwise, expressions such as "comprise", "include", "include" etc. and their conjugations such as "comprises", "includes", "contains" or "having", "comprising", "containing" etc. imply that the specified elements are included without excluding other, unspecified elements.

[0021] In the present specification, the term “p to q” indicates a range of “p or more and q or less”.

[0022] In the present specification, the term "specific surface area" is measured by a BET method, and specifically, it is calculated from the adsorption amount of nitrogen gas under a liquid nitrogen temperature (77 K) using Belsorpmino II from BEL Japan Co. That is, in the present application, the term "BET specific surface area" may be a specific surface area measured by the above-mentioned measurement method.

[0023] In this specification, the term "average particle diameter Dn" refers to a particle diameter at an n% point in the cumulative distribution of the number of particles according to a particle diameter. That is, D50 is the particle size at a 50% point in the cumulative distribution of the number of particles according to the particle diameter, D90 is the particle size at a 90% point in the cumulative distribution of the number of particles according to the particle diameter, and D10 is the particle size at a 10% point in the cumulative distribution of the number of particles according to the particle diameter. Meanwhile, the average particle diameter can be measured by a laser diffraction method.Specifically, powder to be measured is dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measuring device (for example, Microtrac S3500) to calculate the particle size distribution by measuring the diffraction pattern difference according to the particle size when particles are passed through a laser beam.

[0024] In this specification, a configuration in which a polymer contains any monomer as a monomer unit means that the monomer participates in a polymerization reaction and is contained as a repeating unit in the polymer. In this specification, a configuration in which a polymer contains a monomer is interpreted in the same way as a configuration in which a polymer contains a monomer as a monomer unit.

[0025] In this description, the term “polymer” is used figuratively to include a copolymer, unless the term “polymer” explicitly refers to a “homopolymer”.

[0026] In this specification, the terms "weight-average molecular weight (Mw)" and "number-average molecular weight (Mn)" refer to polystyrene conversion molecular weights measured by gel permeation chromatography (GPC) using monodisperse polystyrene polymer (standard sample) with various degrees of polymerization, which is commercially available as a polymer for measuring molecular weight, as the standard material. In this specification, unless otherwise stated, the molecular weight refers to the weight-average molecular weight.

[0027] Hereinafter, the present invention will be described in detail with reference to the drawings so that those skilled in the art to which the present invention pertains can easily carry out the present invention. However, the present invention can be embodied in various forms and is not limited to the following description.

[0028] An embodiment of the present description provides a jelly roll electrode assembly comprising: a first separator; a positive electrode stacked on a side surface of the first separator and having a positive electrode current collector; a second separator provided on a surface opposite a surface of the positive electrode abutting against the first separator;and a negative electrode having a negative electrode current collector provided on a surface opposite to a surface of the second separator abutting against the positive electrode, wherein the jelly-roll electrode assembly has a structure wound around the negative electrode while defining a jelly-roll hollow portion in a core part, the negative electrode current collector comprising: a negative electrode coated portion to which a negative electrode active material is applied;and non-coated portions of the negative electrode to which the negative electrode active material is not applied, wherein the non-coated portions of the negative electrode are formed at two opposite ends of the negative electrode, wherein at least one of the non-coated portions of the negative electrode arranged at the two opposite ends has a negative electrode tab, wherein a protective tape is provided on at least one surface of the non-coated portion of the negative electrode of the negative electrode current collector, and wherein the protective tape satisfies the following expression 1; 50%≤a≤100%, where a in Expression 1 represents: (a length of the protective tape attached to the uncoated portion of the negative electrode / a total length of the uncoated portion of the negative electrode) × 100.

[0029] The jelly-roll electrode assembly according to the present application has a structure wound around the negative electrode, defining the jelly-roll hollow portion at the central portion to implement a structure in which the negative electrode current collector is disposed at the outermost periphery. The negative electrode non-coated portion of the negative electrode current collector includes the protective tape satisfying Expression 1 provided on at least one surface thereof. Thus, the protective tape imparts rigidity to the negative electrode current collector even though the winding process is performed around the central portion of the negative electrode current collector with a small thickness, making it possible to prevent the occurrence of a crease during the winding process and thus prevent electrode wrinkles throughout the electrode.Therefore, it is possible to provide a jelly-roll electrode assembly without wrinkles.

[0030] An embodiment of the present application may provide an electrode sheet comprising a first separator, a positive electrode stacked on a side surface of the first separator and having a positive electrode current collector, a second separator stacked on a side surface of the positive electrode, and a negative electrode having a negative electrode current collector disposed on the second separator.

[0031] That is, the jelly-roll electrode assembly may include: a first separator; a positive electrode stacked on a side surface of the first separator and having a positive electrode current collector; a second separator provided on a surface opposite to a surface of the positive electrode abutting against the first separator; and a negative electrode having a negative electrode current collector provided on a surface opposite to a surface of the second separator abutting against the positive electrode, wherein the jelly-roll electrode assembly has a structure wound around the negative electrode, defining a jelly-roll hollow portion in a core part.The jelly roll electrode assembly may be represented by a jelly roll electrode assembly having a structure formed by winding the electrode sheet.

[0032] According to one embodiment of the present application, a method for manufacturing the jelly roll electrode assembly includes a step of preparing and stacking the positive electrode, the negative electrode, the first separator, and the second separator.

[0033] In the process step, the first separator, the positive electrode, the second separator, and the negative electrode are stacked in sequence and wound around the negative electrode, defining the jelly-roll hollow portion in the core part. The above-mentioned stacking and winding process can form a jelly-roll electrode assembly having a structure in which the current collector of the negative electrode is arranged at an outermost periphery.

[0034] Fig. 1 is a view illustrating a method for winding an electrode sheet according to an embodiment of the present application in the form of a jelly-roll electrode assembly. Specifically, it can be noted that a structure is manufactured by stacking a first separator 4, a positive electrode 3 stacked on a side surface of the first separator and having a positive electrode current collector, a second separator 2 stacked on a side surface of the positive electrode 3, and a negative electrode 1 having a negative electrode current collector arranged on the second separator 2. Further, it can be ensured that the structure is wound around the negative electrode 1, defining a jelly-roll hollow portion 100 at a central portion thereof. In addition, as shown in Fig. 1, it can be noted that only the negative electrode 1 having the negative electrode current collector is wound again, so that a jelly-roll electrode assembly is formed in which a negative electrode current collector is arranged at an outermost periphery.

[0035] Fig. Figure 2 illustrates a prior art structure in which a separator is disposed at an outermost periphery. The structure includes the positive electrode 3, the second separator 2, the negative electrode 1, and the first separator 4, and is wound around the positive electrode 3, defining the jelly-roll hollow portion 100 at the central portion thereof. Thus, the jelly-roll electrode assembly fabricated from the above-mentioned configuration may have a structure in which the first separator 4 is disposed at the outermost periphery.

[0036] In the embodiment of the present application, the positive electrode may include: a positive electrode current collector; and a positive electrode active material layer formed on one surface or two opposite surfaces of the positive electrode current collector and including a positive electrode active material.

[0037] In the embodiment of the present application, the positive electrode current collector includes: a coated portion of the positive electrode to which the positive electrode active material is applied; and an uncoated portion of the positive electrode to which the positive electrode active material is not applied. The jelly-roll electrode assembly includes a positive electrode tab disposed on the uncoated portion of the positive electrode.

[0038] In the embodiment of the present application, the positive electrode active material layer may be formed on the coated portion of the positive electrode current collector. A surface on which the positive electrode active material layer is not provided may be represented by the non-coated portion of the positive electrode.

[0039] In particular, as in Fig. As can be seen in Figure 3, the positive electrode 3 is provided between the first separator 4 and the second separator 2, and the positive electrode 3 includes a positive electrode uncoated portion 14 to which a positive electrode active material layer 17 is not applied. Furthermore, it can be seen that a positive electrode tab 13 is provided on the positive electrode uncoated portion.

[0040] In the positive electrode, the positive electrode current collector is not particularly limited, as long as the positive electrode current collector has conductivity without causing a chemical change in the battery. For example, the positive electrode current collector can be made of stainless steel, aluminum, nickel, titanium, burnt carbon, or aluminum, or stainless steel with a surface treated with carbon, nickel, titanium, silver, or the like. In addition, the positive electrode current collector can typically have a thickness of 3 to 500 μm. The adhesion of the positive electrode active material can be increased by forming fine concave-convex portions on the surface of the current collector.For example, the positive electrode current collector can be made of various materials such as sheets, plates, foils, nets, porous elements, foam elements and nonwovens.

[0041] The positive electrode active material may be a commonly used positive electrode active material. Specifically, examples of the positive electrode active material may include: a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; lithium manganese oxide such as a material represented by a chemical formula Li 1+c1 Mn 2-c1 O4 (o ≤ c1 ≤ 0.33), LiMnO3, LiMn2O3 or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxide, such as LiV3O8, V2O sor Cu2V2O7; lithium nickel oxide of the Ni-site type, which has a chemical formula LiNi 1-c2 M c2 O2 (where M here is at least one selected from the following group: Co, Mn, Al, Cu, Fe, Mg, B and Ga, and 0.01 ≤ c2 ≤ 0.3 is satisfied); lithium manganese composite oxide represented by a chemical formula LiMn 2-c3 M c3 O2 (where M here is at least one selected from the following group: Co, Ni, Fe, Cr, Zn and Ta, and 0.01 ≤ c3 ≤ 0.4 is satisfied); and ions substituted in the chemical formula LiMn2-c3Mc3O4, where M here is at least one selected from the following group: Co, Mn, Fe, Cu, Fe, Mg, B and Ga, and LiMnO8; or the like. The positive electrode may be made of Li metal.

[0042] The positive electrode active material layer may comprise, in addition to the above-mentioned positive electrode active material, a positive electrode conductor material and a positive electrode binder.

[0043] In this case, the positive electrode conductor material is used to impart conductivity to the electrode, and any conductor material that exhibits electron conductivity without causing a chemical change in the battery can be used without particular limitation. Specific examples of the positive electrode conductor material may include: graphite, such as natural graphite or artificial graphite; a carbon-based material, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, or carbon fiber; metal powder or metal fiber containing copper, nickel, aluminum, or silver; a conductive whisker, such as zinc oxide or potassium titanate; a conductive metal oxide, such as titanium oxide; and a conductive polymer, such as a polyphenylene derivative, which may be used alone or in combination of two or more thereof.

[0044] Furthermore, the positive electrode binder serves to improve the cohesion between particles of the positive electrode active material and the adhesion between the positive electrode active material and the positive electrode current collector. Specific examples of the positive electrode binder may include polyvinylidene fluoride (PVDF), a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, an ethylene-propylene-diene polymer (EPDM), a sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof, which may be used alone or in combination of two or more thereof.

[0045] In the embodiment of the present application, the positive electrode current collector may include a non-coated portion of the positive electrode and a positive electrode tab formed on the non-coated portion of the positive electrode. The jelly-roll electrode assembly according to the present application may include a positive electrode tab.

[0046] In this case, the non-coated portion of the positive electrode may be formed at the central portion of the positive electrode.

[0047] In the embodiment of the present application, the negative electrode may include a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector may include a coated negative electrode portion to which a negative electrode active material is applied and an uncoated negative electrode portion to which the negative electrode active material is not applied.

[0048] In particular, as in Fig. As can be seen in Figure 3, the negative electrode 1 is provided on the second separator 2, and the negative electrode 1 includes negative electrode uncoated portions 15 provided at two opposite ends of the negative electrode, to which the negative electrode active material layer 16 is not applied. Furthermore, it can be seen that at least one of the negative electrode uncoated portions located at the two opposite ends of the negative electrode includes a negative electrode tab 10.

[0049] The jelly-roll electrode assembly according to the present application includes the uncoated portions of the negative electrode provided at the two opposite ends of the negative electrode, and at least one of the uncoated portions of the negative electrode provided at the two opposite ends includes the negative electrode tab. Specifically, the one of the uncoated portions of the negative electrode located adjacent to a winding core portion may include the negative electrode tab.

[0050] In the embodiment of the present application, the negative electrode active material layer may comprise a negative electrode active material comprising one or more materials selected from the following group: silicon-based materials and carbon-based materials.

[0051] Furthermore, in the embodiment of the present application, the negative electrode active material layer may include a negative electrode conductor material and a negative electrode binder.

[0052] In the embodiment of the present application, materials used in the art can be used for the negative electrode active material, the negative electrode conductor material, and the negative electrode binder without limitation.

[0053] In the embodiment of the present application, the negative electrode current collector is not particularly limited as long as the negative electrode current collector has conductivity without causing a chemical change in the battery. For example, the current collector may be made of copper, stainless steel, aluminum, nickel, titanium, burnt carbon, or aluminum, or stainless steel with a surface treated with carbon, nickel, titanium, silver, or the like. In particular, the current collector may be made of a transition metal such as copper or nickel that appropriately absorbs carbon. The thickness of the current collector may be 6 μm to 20 μm, but the thickness of the current collector is not limited to this.

[0054] The negative electrode binder may comprise at least one selected from the following group: polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, an ethylene-propylene-diene monomer (EPDM), a sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and materials in which hydrogens thereof are substituted with Li, Na, Ca, or the like, and may also comprise various copolymers thereof.

[0055] The negative electrode conductor material is not particularly limited, as long as the negative electrode conductor material has conductivity without causing a chemical change in the battery. For example, the conductive material that can be used includes: graphite, such as natural graphite or artificial graphite; carbon black, such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; a conductive fiber, such as carbon fiber or metal fiber; a conductive tube, such as a carbon nanotube; metal powder, such as fluorocarbon powder, aluminum powder, or nickel powder; a conductive whisker, such as zinc oxide or potassium titanate; a conductive metal oxide, such as titanium oxide; or a conductive material, such as a polyphenylene derivative.

[0056] In the embodiment of the present application, the first and second separators can be used without particular limitation, as long as the first and second separators separate the negative electrode and the positive electrode from each other, provide movement channels for lithium ions, and are typically used as separators in the secondary battery. In particular, a separator that has low resistance to electrolyte ion migration and excellent electrolyte impregnation ability can be used. In particular, a porous polymer film can be used, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a stacked structure having two or more layers thereof.In addition, a typical porous nonwoven fabric can be used, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, or the like. Furthermore, a coated separator comprising a ceramic component or a polymer material can be used to ensure heat resistance or mechanical strength. Optionally, the separator can have a single-layer or multi-layer structure.

[0057] The embodiment of the present application provides the jelly roll electrode assembly in which the negative electrode current collector includes the coated portion of the negative electrode to which the negative electrode active material is applied and the uncoated portion of the negative electrode to which the negative electrode active material is not applied, wherein the uncoated portion of the negative electrode is formed at the two opposite ends of the negative electrode, one of the uncoated portions of the negative electrode provided at the two opposite ends includes the tab of the negative electrode, at least one surface of the uncoated portion of the negative electrode of the negative electrode current collector includes a protective tape, and the protective tape satisfies the following Expression 1. 50%≤a≤100%, where a in Expression 1 represents: length of the protective tape applied to the uncoated portion of the negative electrode / total length of the uncoated portion of the negative electrode × 100.

[0058] In the embodiment of the present application, the uncoated portions of the negative electrode may be formed at the two opposite ends of the negative electrode, and one of the uncoated portions of the negative electrode may be formed in a jelly-roll hollow portion. Specifically, the uncoated portion of the negative electrode corresponds to a position 100 in Fig. 1. As in Fig. 3, the uncoated portion of the negative electrode may be a portion of one end of the negative electrode at which winding is started.

[0059] An embodiment of the present application provides the jelly roll electrode assembly in which the negative electrode current collector includes the coated portion of the negative electrode to which the negative electrode active material is applied and the uncoated portion of the negative electrode to which the negative electrode active material is not applied, wherein the uncoated portion of the negative electrode is formed at the two opposite ends of the negative electrode, one of the uncoated portions of the negative electrode provided at the two opposite ends includes the negative electrode tab, at least one surface of the uncoated portion of the negative electrode current collector includes the protective tape, and the protective tape satisfies the above Expression 1.

[0060] An embodiment of the present application provides a jelly-roll electrode assembly in which the negative electrode current collector includes the coated portion of the negative electrode to which the negative electrode active material is applied and the uncoated portion of the negative electrode to which the negative electrode active material is not applied, wherein the uncoated portion of the negative electrode is formed at the two opposite ends of the negative electrode, one of the uncoated portions of the negative electrode provided at the two opposite ends includes the negative electrode tab, the negative electrode tab is positioned at one end of the two opposite ends of the uncoated portion of the negative electrode positioned in the jelly-roll hollow portion of the negative electrode,at least one surface of the uncoated portion of the negative electrode of the negative electrode current collector has the protective tape, and the protective tape satisfies the above expression 1.,

[0061] An embodiment of the present application provides the jelly roll electrode assembly in which at least one surface of the negative electrode uncoated portion of the negative electrode current collector has the protective tape, and the protective tape satisfies the above Expression 1.

[0062] Another embodiment provides the jelly roll electrode assembly in which the negative electrode uncoated portion of the negative electrode current collector has the protective tape provided on a surface thereof, and the protective tape satisfies the above Expression 1.

[0063] Yet another embodiment provides a jelly roll electrode assembly in which the negative electrode uncoated portion of the negative electrode current collector has protective tapes provided on two opposite surfaces thereof, and the protective tape satisfies the above Expression 1.

[0064] A jelly-roll electrode assembly according to the present application includes a protective tape provided on at least one surface of the negative electrode non-coated portion of the negative electrode current collector, and the protective tape satisfies the above Expression 1. Thus, the protective tape can impart rigidity to the negative electrode current collector even though a process of winding the negative electrode current collector with a small thickness around the central portion is performed, thereby preventing the occurrence of a crease during the winding process. Therefore, it is possible to prevent the electrode crease from the entire electrode, making it possible to provide the jelly-roll electrode assembly without wrinkles.

[0065] That is, the main object of the present invention is to prevent the occurrence of an electrode fold as in the prior art by attaching the protective tape satisfying the length to the surface of at least one of the non-coated portions of the negative electrode of the jelly-roll electrode assembly according to the present application.

[0066] An embodiment of the present application provides the jelly roll electrode assembly in which the negative electrode uncoated portion has a surface of a first negative electrode uncoated portion having the negative electrode tab and a surface of a second negative electrode uncoated portion opposite to the surface of the first negative electrode uncoated portion, the protective bands are provided on the surface of the first negative electrode uncoated portion and the surface of the second negative electrode uncoated portion, and the protective band satisfies Expressions 2 and 3 below. 25%≤a1≤100%, 25%≤b1≤100%, where a1 in Expressions 2 and 3 represents: (length of the protective tape applied to the first uncoated portion of the negative electrode / total length of the first uncoated portion of the negative electrode) × 100; and b1 represents: (length of the protective tape applied to the second uncoated portion of the negative electrode / total length of the second uncoated portion of the negative electrode) × 100; and at least one of a1 and b1 is 50% or more.

[0067] In particular, the above-mentioned content may be Fig. 4 can be observed. Fig. 4 is a view illustrating the core part of the negative electrode according to the present application. Specifically, the negative electrode tab 10 is provided on the uncoated portion of the negative electrode included in the core part provided at one of the two opposite ends of the negative electrode. A length 23 of the protective tape applied to the first uncoated portion of the negative electrode and a total length 21 of the first uncoated portion of the negative electrode can be identified. A length 24 of the protective tape applied to the second uncoated portion of the negative electrode and a total length 22 of the second uncoated portion of the negative electrode can be identified.

[0068] In one embodiment of the present application, Expression 2 may satisfy a range of 25% ≤ a1 ≤ 100%, a range of 50% ≤ a1 ≤ 100%, a range of 70% ≤ a1 ≤ 100%.

[0069] In the embodiment of the present application, the protective tape applied to the first uncoated portion of the negative electrode can be configured to cover the negative electrode tab. The protective tape can fix the negative electrode tab and prevent the uncoated portion of the negative electrode current collector from folding during the winding process.

[0070] In the embodiment of the present application, Expression 3 may satisfy a range of 25% ≤ b1 ≤ 100%, a range of 50% ≤ b1 ≤ 100%, a range of 70% ≤ b1 ≤ 100%.

[0071] In the embodiment of the present application, in the case where the protective tape is provided on the first negative electrode non-coated portion of the negative electrode non-coated portions having the negative electrode tab, and the protective tape satisfying the above-mentioned range is provided on the second negative electrode non-coated portion opposite to the first negative electrode non-coated portion, it is possible to greatly reduce a frequency of occurrence of a core fold compared to a case where the protective tape is provided on the single non-coated portion.

[0072] That is, it is possible to prevent the occurrence of electrode wrinkles as in the prior art by attaching the protective tape that satisfies the length to the surface of one of the non-coated portions of the negative electrode of the jelly-roll electrode assembly. In particular, in the case where the protective tapes are provided on both the first non-coated portion of the negative electrode and the second non-coated portion of the negative electrode, it is possible to achieve the excellent effect of preventing wrinkles and collapse of the core part because the jelly-roll core part has rigidity.

[0073] An embodiment of the present application provides a jelly roll electrode assembly in which a1 is 100% and b1 is 100%.

[0074] In the present application, the configuration in which a1 is 100% and b1 is 100% may mean that the entire two opposite surfaces of the uncoated portion of the negative electrode having the tab of the negative electrode are covered by the protective tape.

[0075] An embodiment of the present application provides a jelly roll electrode assembly having a positive electrode tab and a negative electrode tab.

[0076] As in Fig. As can be seen from Figure 3, it can be seen that the negative electrode tab of the jelly-roll electrode assembly according to the present invention is positioned at one end of the two opposite ends of the negative electrode positioned at the core part of the negative electrode, and the positive electrode tab is formed at the central portion of the positive electrode instead of the outer periphery of the positive electrode. Furthermore, it can be seen that the jelly-roll electrode assembly includes a positive electrode tab and a negative electrode tab.

[0077] If the jelly-roll electrode assembly has one positive electrode tab and one negative electrode tab as described above, the resistance may increase compared to a case where the jelly-roll electrode assembly has two or more positive electrode tabs and two or more negative electrode tabs. However, since the jelly-roll electrode assembly has one positive electrode tab and one negative electrode tab, an area of ​​the uncoated portion can be reduced, and the positive electrode active material and the negative electrode active material can be further contained, making it possible to greatly increase the capacity.

[0078] That is, the jelly-roll electrode assembly according to the present invention has one positive electrode tab and one negative electrode tab, so that the jelly-roll electrode assembly is used for high-capacity purposes rather than high-output purposes. Therefore, it is possible to identify a difference in purpose depending on the number of positive electrode tabs and the number of negative electrode tabs.

[0079] The embodiment of the present application provides a jelly-roll electrode assembly comprising: layers of positive electrode active material provided on two opposite surfaces of the positive electrode coated portion of the positive electrode current collector; and layers of negative electrode active material provided on two opposite surfaces of the negative electrode coated portion of the negative electrode current collector.

[0080] If the layers of active material are provided on both of the two opposite surfaces as described above, a larger amount of active material can be contained, thereby maximizing the capacity.

[0081] The embodiment of the present application provides a jelly roll electrode assembly having a structure in which the current collector of the negative electrode is arranged at the outermost periphery.

[0082] The method for manufacturing the jelly-roll electrode assembly having the structure in which the current collector of the negative electrode is arranged at the outermost periphery can be described in Fig. 1. As in Fig. As can be seen in Figure 1, the structure is wrapped around the negative electrode 1, defining the jelly-roll hollow section 100 at the central portion. Only the negative electrode current collector 5 contained within the negative electrode 1 is finally wrapped once more around the outer periphery of the jelly-roll electrode assembly, making it possible to define the structure in which the negative electrode current collector is exposed at the outermost periphery.

[0083] That is, the structure in which the negative electrode current collector is arranged at the outermost periphery is a structure fabricated such that the negative electrode current collector is exposed at the outermost periphery by changing the winding order of the positive electrode and the negative electrode. This structure allows the negative electrode current collector to be in direct contact with an inner wall of a battery outer material described below, thus enabling electrical connection with the case (can) without an external tab of the negative electrode.That is, the jelly roll electrode assembly according to the present invention has a positive electrode tab and a negative electrode tab as described above, so that the high-capacity battery can be implemented and the above-mentioned feature can be implemented because the negative electrode current collector is provided at the outermost periphery.

[0084] The embodiment of the present application provides a jelly roll electrode assembly in which the protective tape is made of one selected from the following group: polyethylene terephthalate (PET), polypropylene (PP), polyester, polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyarylate (PAR), polycycloolefin (PCO), polynorbornene, polyethersulfone (PES), and cycloolefin polymer (COP).

[0085] The protective tape can secure the tab of the negative electrode. Any protective tape that has sufficient rigidity to prevent the uncoated portion of the negative electrode from folding during the winding process can be used without limitation. In particular, the protective tape can be made of PET.

[0086] The embodiment of the present application can provide a jelly roll electrode assembly in which a thickness of the protective tape is 10 µm or more and 100 µm or less.

[0087] The embodiment of the present application provides a cylindrical lithium secondary battery including an outer material of the battery; the jelly-roll electrode assembly according to the present application provided in the outer material of the battery; and an outer lid having an electrode provided in an opening portion of the outer material of the battery.

[0088] The content related to the jelly roll electrode assembly is identical to the content mentioned above.

[0089] In the embodiment of the present application, the outer material of the battery may have the electrolyte therein.

[0090] The electrolyte may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-like polymer electrolyte, a solid inorganic electrolyte, and a melt-like inorganic electrolyte, which can be used to manufacture the lithium secondary battery.

[0091] In particular, the electrolyte may comprise a non-aqueous organic solvent and a metal salt.

[0092] As the non-aqueous organic solvent, an aprotic organic solvent can be used, for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triesters, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, ethyl propionate or the like.

[0093] In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates among carbonate-based organic solvents, are organic solvents with high viscosity and high dielectric constant, and dissociate lithium salts in an electrolyte tank and can be preferably used. If such a cyclic carbonate and a linear carbonate with low viscosity and low dielectric constant, such as dimethyl carbonate and diethyl carbonate, are mixed and used in an appropriate ratio, an electrolyte with high electrical conductivity can be prepared and can be used more preferably.

[0094] The metal salt can use a lithium salt, and the lithium salt is a material that can be easily dissolved in the non-aqueous electrolyte. For example, one or more selected from the following group can be used as the anion of the lithium salt: F-, Cl-, I-, NO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , N(CN)2<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , BF4<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , ClO4<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , PF6<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3)2PF4<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3)3PF3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3)4PF2<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3)5PF<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3)6P<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , CF3SO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , CF3CF2SO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3SO2)2N<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (FSO2)2N<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , CF3CF2(CF3)2CO<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3SO2)2CH<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (SF3)3C<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , (CF3SO2)3C-, CF3(CF2)7SO3-, CF3CO2<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , CH3CO2<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , SCN- and (CF3CF2SO2)2N<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> .<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0095] In the electrolyte, one or more types of additives, for example, a haloalkylene carbonate-based material such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivatives, sulfur, a quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, an ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride, may be included in addition to the components of the electrolyte in order to improve the cycle life characteristics of a battery, to limit the decrease in battery capacity, and to improve battery discharge capacity.

[0096] The jelly-roll electrode assembly according to the present invention can be incorporated into a cylindrical battery. The cylindrical battery can refer to a battery comprising an assembly including the positive electrode, the negative electrode, the separator, and the electrolyte, and having a cylindrical shape. Specifically, the cylindrical battery can include a cylindrical casing, a battery assembly provided in the cylindrical casing, and a top cap. [Mode for invention]

[0097] Examples are provided below to aid understanding of the present invention, but the examples are provided only to illustrate the present invention. It will be apparent to those skilled in the art that various modifications and changes can be made within the technical spirit of the present invention, and these modifications and changes are within the scope of the appended claims. <Beispiel 1>

[0098] According to the Fig. 3, a jelly roll electrode assembly is formed by stacking a first separator, a positive electrode, a second separator, and a negative electrode, providing a negative electrode tab at a winding center portion of a non-coated portion of a negative electrode current collector, attaching a protective tape satisfying a condition that a is 100%, specifically, a1 is 100% and b1 is 100%, to two opposite surfaces of the non-coated portion of the negative electrode current collector having the negative electrode tab, and winding the resulting structure. <Beispiel 2>

[0099] A jelly-roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, a protective tape satisfying a condition that a is 100%, specifically, a1 is 100%, is attached to a surface of a non-coated portion of a negative electrode current collector having a negative electrode tab. <Beispiel 3>

[0100] A jelly-roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, a protective tape satisfying a condition that a is 80%, specifically, a1 is 80% and b1 is 30%, is attached to two opposite surfaces of a non-coated portion of a negative electrode current collector having a negative electrode tab. <Beispiel 4>

[0101] A jelly-roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, a protective tape satisfying a condition that a is 80%, specifically, a1 is 30% and b1 is 80%, is attached to two opposite surfaces of a non-coated portion of a negative electrode current collector having a negative electrode tab. <Vergleichsbeispiel 1>

[0102] A jelly-roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, a protective tape satisfying a condition that a is 40%, specifically, a1 is 40%, is attached to a surface of a non-coated portion of a negative electrode current collector having a negative electrode tab. <Vergleichsbeispiel 2>

[0103] A jelly-roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, a protective tape satisfying a condition that a is 40%, specifically, a1 is 40% and b1 is 30%, is attached to two opposite surfaces of a non-coated portion of a negative electrode current collector having a negative electrode tab. <Vergleichsbeispiel 3>

[0104] A jelly roll electrode assembly is formed by the same method as in Example 1, except that in Example 1, no protective tape is attached to the opposite surfaces of an uncoated portion of a negative electrode current collector having a negative electrode tab.

[0105] The jelly-roll electrode assemblies according to Examples 1 to 4 are each configured such that the protective tape is formed to cover 50% or more of at least one surface of the uncoated portion of the negative electrode of the negative electrode current collector and is formed on one surface or two opposite surfaces of the uncoated portion of the negative electrode. In this way, it can be observed that electrode wrinkles are prevented and the cycle life and efficiency of the cylindrical lithium secondary battery with the jelly-roll electrode assembly are improved.

[0106] Specifically, Example 1 is a case where the protective tape is applied to 100% of the two opposite surfaces of the negative electrode uncoated portion of the negative electrode current collector having the negative electrode tab. Example 2 is a case where the protective tape is applied to 100% of the surface of the negative electrode uncoated portion of the negative electrode current collector on which the negative electrode tab is provided.

[0107] According to the comparison between Examples 1 and 2, Example 1 has the effect of preventing electrode wrinkles compared to Comparative Examples 1 to 3, and especially compared to Example 2 (in which the protective tape is formed on a single surface), it has an excellent effect of preventing electrode wrinkles. This is a result of the formation of the rigid protective tape on the two opposite surfaces of the uncoated portion of the negative electrode.

[0108] In particular, Fig. 5 is a view illustrating the negative electrode according to Example 1 of the present application. Specifically, it can be seen that the protective tape is attached to the two opposite surfaces of the uncoated portion of the negative electrode (indicated by the dashed line), so that the condition that a is 100% is satisfied. In this case, it can be seen that the negative electrode has no wrinkles, thus achieving the effect of preventing electrode wrinkles.

[0109] Examples 3 and 4 are cases where the protective tape is provided on the two opposite surfaces of the uncoated negative electrode portion of the negative electrode current collector having the negative electrode tab, but a1 and b1 are not 100%. It can be seen that in Examples 3 and 4, electrode wrinkles occur relatively easily, but the electrode wrinkles are such that they do not cause any problems for the electrode operation compared to Example 1.

[0110] Comparative Example 1 is a case where the protective tape is formed on 50% or less of the single surface of the uncoated portion of the negative electrode, and Comparative Example 2 is a case where the protective tape is formed on 50% or less of the two opposite surfaces of the uncoated portion of the negative electrode. It can be seen that, even though the protective tape is provided, electrode wrinkles still occur at the time of winding the electrode assembly. Therefore, a problem of performance deterioration of the lithium secondary battery and a safety problem caused by lithium precipitation may occur.

[0111] Fig. Figure 6 is a view illustrating the negative electrode according to Comparative Example 1 of the present application. Specifically, it can be seen that the protective tape is attached to a surface of the uncoated portion of the negative electrode (indicated by the thin dashed line), so that the condition that a is 40% is satisfied, and 60% of the uncoated portion of the negative electrode is exposed. In this case, as shown in Fig. 6 and Fig. As shown in Figure 7, it can be seen that a length of the protective tape cannot be satisfied, and the uncoated portion of the negative electrode is folded (enlarged, as indicated by the thick dashed line). Therefore, it can be seen that the entire negative electrode is folded, causing performance deterioration of the lithium secondary battery.

[0112] Comparative Example 3 is a case where the protective tape is not provided on the two opposite surfaces. In this case, a large number of wrinkles occur during the winding process of the electrode assembly, which may cause early performance deterioration of the lithium secondary battery and a safety issue caused by lithium precipitation. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2021-0174846

[0001] JP 2009-080971

[0013]

Claims

[1] Jelly-roll electrode assembly, comprising: a first separator (4); a positive electrode (3) stacked on a surface of the first separator (4) and having a positive electrode (3) current collector; a second separator (2) provided on a surface opposite to a surface of the positive electrode (3) adjacent to the first separator (4); and a negative electrode (1) having a negative electrode current collector provided on a surface opposite a surface of the second separator (2) adjacent to the positive electrode (3), wherein the jelly-roll electrode assembly defines a jelly-roll hollow section in a core part thereof, where the current collector of the negative electrode has: a coated portion of the negative electrode to which a negative electrode active material (16) is applied; and uncoated sections (15) of the negative electrode to which the active material (16) of the negative electrode is not applied, wherein the non-coated portions (15) of the negative electrode are formed at two opposite ends of the negative electrode (1), wherein at least one of the uncoated portions (15) of the negative electrode has a tab (10) of the negative electrode, wherein each of at least one protective tape (11, 12) is provided on a respective surface of one of the non-coated portions (15) of the negative electrode of the negative electrode current collector, and wherein each protective band (11, 12) is formed to cover 50% or more of the surface of the non-coated portion (15) of the negative electrode of the negative electrode current collector. [2] The jelly roll electrode assembly of claim 1, wherein said one non-coated portion (15) of the negative electrode is a non-coated portion (15) of the negative electrode having the tab (10) of the negative electrode. [3] Jelly-roll electrode assembly according to claim 1 or 2, wherein the protective tape (11, 12) satisfies the following expression 1: 50%≤a≤100%, wherein in Expression 1 a in Expression 1 represents: (a length (23, 24) of the protective tape (11, 12) applied to the at least one surface of the uncoated portion (15) of the negative electrode / a total length (21, 22) of the at least one surface of the uncoated portion (15) of the negative electrode) x 100%. [4] Jelly-roll electrode assembly, comprising: a first separator (4); a positive electrode (3) stacked on a surface of the first separator (4) and having a positive electrode (3) current collector; a second separator (2) provided on a surface opposite to a surface of the positive electrode (3) adjacent to the first separator (4); and a negative electrode (1) having a negative electrode current collector provided on a surface opposite a surface of the second separator (2) adjacent to the positive electrode (3), wherein the jelly-roll electrode assembly defines a jelly-roll hollow section in a core part thereof, where the current collector of the negative electrode has: a coated portion of the negative electrode to which a negative electrode active material (16) is applied; and uncoated sections (15) of the negative electrode to which the active material (16) of the negative electrode is not applied, wherein the non-coated portions (15) of the negative electrode are formed at two opposite ends of the negative electrode (1), wherein at least one of the uncoated portions (15) of the negative electrode has a tab (10) of the negative electrode, wherein one of the uncoated portions (15) of the negative electrode comprises: a first surface having the tab (10) of the negative electrode; and a second surface opposite the first surface, wherein a first protective band (11) is formed on the first surface of the one non-coated portion (15) of the negative electrode and a second protective band (12) is formed on the second surface of the one non-coated portion (15) of the negative electrode, and wherein the first and second protective bands (11, 12) satisfy expressions 2 and 3, respectively: 25%≤a1≤100%, 25%≤b1≤100%, where a1 in Expression 2 represents: (a length (23) of the first protective tape (11) applied to the first surface of the one non-coated portion (15) of the negative electrode / a total length (21) of the first surface of the one non-coated portion (15) of the negative electrode) × 100%, and where b1 in Expression 3 represents: (a length (24) of the protective tape (12) applied to the second surface of the one non-coated portion (15) of the negative electrode / a total length (22) of the second surface of the one non-coated portion (15) of the negative electrode) × 100%. [5] The jelly roll electrode assembly according to claim 4, wherein at least one of a1 and b1 is 50% or more. [6] Jelly roll electrode assembly according to claim 4, wherein a1 is 100% and b1 is 100%. [7] Jelly-roll electrode assembly according to one of claims 1 to 6, wherein the positive electrode current collector comprises: a coated portion of the positive electrode to which a positive electrode active material (17) is applied; and an uncoated portion (14) of the positive electrode to which the active material (17) of the positive electrode is not applied, and wherein the jelly roll electrode assembly has a positive electrode tab (13) disposed on the non-coated portion (14) of the positive electrode. [8] Jelly roll electrode assembly according to claim 7, wherein the positive electrode has only one tab (13) and the negative electrode has only one tab (10). [9] Jelly-roll electrode assembly according to claim 7 or 8, comprising: positive electrode active material layers provided on two opposite surfaces of the positive electrode coated portion (3) of the positive electrode current collector (3); and negative electrode active material layers provided on two opposite surfaces of the negative electrode coated portion (1) of the negative electrode current collector. [10] A jelly-roll electrode assembly according to any one of claims 1 to 9, wherein the protective tape (11, 12) is made of a material selected from a group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyester, polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyarylate (PAR), polycyclic olefin (PCO), polynorbornene, polyethersulfone (PES) and cycloolefin polymer (COP). [11] The jelly roll electrode assembly according to any one of claims 1 to 10, wherein a thickness of the protective tape (11, 12) is 10 µm or more and 100 µm or less. [12] The jelly-roll electrode assembly according to any one of claims 1 to 11, wherein the negative electrode current collector is disposed at an outermost periphery of the jelly-roll electrode assembly. [13] Cylindrical lithium secondary battery, comprising: an external material of the battery; the jelly-roll electrode assembly according to any one of claims 1 to 12, which is provided in the outer material of the battery; and an outer cover having an electrode provided in an opening portion of the battery outer material.

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