Jelly roll electrode assembly and cylindrical lithium secondary battery containing the same

Abstract

To provide an electrode assembly that suppresses the occurrence of wrinkles in an electrode uncoated portion that is not coated with an electrode active material during winding, in an electrode assembly that is wound into a jelly roll shape.SOLUTION: A jelly roll electrode assembly is provided in which an uncoated electrode portion includes a protective tape on at least one side, and the protective tape satisfies the following formula 1: [Formula 1] 25%≤a1≤100%. In the formula 1, a1 is (the length of the protective tape attached to the uncoated electrode portion in the longitudinal direction of the electrode / the length of the uncoated electrode portion in the longitudinal direction of the electrode)×100%. This provides rigidity to the negative electrode current collector using the protective tape, preventing wrinkles from forming during winding, even when the process includes a winding step starting from the center of the thin negative electrode current collector. This can reduces wrinkles throughout the electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims the benefit as of the filing date of Korean Patent Application No. 10-2021-0174846, filed with the Korean Intellectual Property Office on December 8, 2021, and all its contents are incorporated herein by reference.

[0002] This application relates to a jelly roll electrode assembly and a cylindrical lithium secondary battery including the same. [Background technology]

[0003] The rapid increase in fossil fuel use has led to a growing demand for alternative and clean energy sources, and one of the most actively researched areas in this field is the generation and storage of electricity using electrochemical reactions.

[0004] Currently, a typical example of an electrochemical element that uses this type of electrochemical energy is the secondary battery, and its range of applications is steadily expanding.

[0005] As technological development and demand for mobile devices increase, the demand for rechargeable batteries as an energy source is rapidly rising. Among these rechargeable batteries, lithium-ion batteries, which have high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used. Furthermore, research is actively being conducted on methods for manufacturing high-density electrodes with even higher energy density per unit volume for use in such high-capacity lithium-ion batteries.

[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 inserts and removes lithium ions released from the positive electrode, and silicon-based particles with a large discharge capacity can be used as the negative electrode active material.

[0007] These lithium-ion secondary batteries are typically manufactured using a lithium-containing compound such as LiCoO2 or LiMn2O4 as the positive electrode, and a non-lithium-containing material such as a carbon-based or silicon-based material as the negative electrode. During charging, lithium ions inserted in the positive electrode move to the negative electrode via the electrolyte, and during discharging, lithium ions move again from the negative electrode to the positive electrode.

[0008] Lithium-ion batteries come in various forms, such as cylindrical, pouch, and prismatic, depending on their application. Conventional cylindrical cells have a separator on the outermost surface after winding, and the separator outer structure surrounds the entire cell, electrically connecting to the battery casing via positive and negative electrode tabs.

[0009] Conventional cylindrical cells have a structure where the positive electrode / separator / negative electrode / separator is wound in that order, with the separator exposed on the outermost layer. In contrast, the Cu foil outermost layer structure has the negative electrode / separator / positive electrode / separator wound in that order, with the Cu foil exposed on the outermost layer. This has the advantage of allowing direct contact with the inner wall of the battery casing of the cylindrical cell, enabling electrical connection and replacing the outer negative electrode tab.

[0010] However, if the contact between the Cu foil and the battery casing is poor, the resistance increases, and a problem arises where the resistance differs depending on the outer diameter of the jelly roll. Unlike the conventional separator outer structure, the Cu foil is on the outermost layer, resulting in two separators surrounding the positive electrode inside.

[0011] The thickness of the Cu foil, which is the negative electrode current collector, is gradually decreasing. In particular, a tab is attached to the plain part of the core of the negative electrode current collector, and winding is started from the core to form a jelly roll electrode assembly. However, at the same time as winding, wrinkles form in the plain part of the core of the negative electrode current collector, and these wrinkles propagate to the wrinkles in the negative electrode, resulting in the formation of a jelly roll electrode assembly that is wound in this state.

[0012] Therefore, research has been conducted on improving the wrinkles of the electrodes in the core part in a jelly roll electrode assembly in which a Cu foil, which is a negative electrode current collector, forms the outermost periphery.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0015] One embodiment of the present specification includes a first separator; a positive electrode laminated on one side surface of the first separator and including a positive electrode current collector; a second separator provided on the opposite surface of the positive electrode contacting the first separator; and a negative electrode including a negative electrode current collector provided on the opposite surface of the second separator contacting the positive electrode, and is a jelly roll electrode assembly having a structure in which a jelly roll hollow part is formed in a core part and wound around the negative electrode as a center, wherein the negative electrode current collector includes a negative electrode active material coating part on which a negative electrode active material is coated and a negative electrode non-coated part on which the negative electrode active material is not coated, the negative electrode non-coated part is formed at both ends of the negative electrode, at least one of the negative electrode non-coated parts at both ends has a negative electrode tab, the negative electrode non-coated part of the negative electrode current collector includes a protective tape on at least one side, and the protective tape satisfies the following formula 1, and provides a jelly roll electrode assembly.

[0016] [Formula 1] 50%≦a≦100% In the above formula 1, a is (the length of the protective tape attached to the negative electrode non-coated part / the total length of the negative electrode non-coated part)×100%.

[0017] In another embodiment, a cylindrical lithium secondary battery is provided, comprising a battery casing; a jelly roll electrode assembly according to this application provided inside the battery casing; and an outer cap with electrodes provided at the opening of the battery casing. [Effects of the Invention]

[0018] The jelly roll electrode assembly according to this application is a jelly roll electrode assembly having a structure in which a hollow jelly roll portion is formed in the core part around the negative electrode and wound up, in order to realize the outermost structure of the negative electrode current collector, and the plain negative electrode portion of the negative electrode current collector has a protective tape that satisfies formula 1 on at least one side. As a result, even if the winding process is included starting from the center of the thin negative electrode current collector, the protective tape provides rigidity to the negative electrode current collector and prevents the formation of wrinkles during winding, thereby improving the wrinkles of the electrode as a whole, and thus providing a jelly roll electrode assembly that does not have wrinkles formed.

[0019] In other words, the jelly roll electrode assembly according to this application is characterized in that a protective tape is formed so as to cover 50% or more of at least one side of the plain negative electrode portion of the negative electrode current collector, and is formed on one or both sides of the plain portion, thereby improving the wrinkling of the electrode and thereby increasing the lifespan and efficiency of the cylindrical lithium secondary battery containing it. [Brief explanation of the drawing]

[0020] [Figure 1] This figure shows a method for winding a jelly roll electrode assembly according to one embodiment of the present application. [Figure 2] This figure shows a method for manufacturing a jelly roll electrode assembly, which is the outermost structure of a separator. [Figure 3] This is a side view of a jelly roll electrode assembly before winding, according to one embodiment of this application. [Figure 4] This figure shows the core portion of the negative electrode according to this application. [Figure 5]This figure shows the negative electrode according to Example 1 of this application. [Figure 6] This figure shows the negative electrode according to Comparative Example 1 of this application. [Figure 7] This figure shows whether or not wrinkles occur in the negative electrode according to Comparative Example 1 of this application. [Explanation of symbols]

[0021] 1...Negative electrode 2 ···Second separator 3...Positive electrode 4 ···First Separator 10 ···Negative electrode tab 11. Protective tape attached to the blank surface of the first negative electrode. 12. Protective tape attached to the blank surface of the second negative electrode. 13 ···Positive Tab 14 ···Positive terminal blank area 15 ···Negative electrode blank section 16...Negative electrode active material layer 17...Cathode active material layer 21 ···Total length of the blank section of the first negative electrode 22 ···Total length of the blank section of the second negative electrode 23...Length of protective tape attached to the plain surface of the first negative electrode 24...Length of protective tape attached to the blank surface of the second negative electrode 100 ···Hollow part of jelly roll [Modes for carrying out the invention]

[0022] Before describing the present invention, let us first define some terms.

[0023] In this specification, when a part "includes" a component, this means that, unless otherwise stated, it may include other components rather than excluding them.

[0024] In this specification, "p~q" means the range "p or greater and q or less".

[0025] In this specification, "specific surface area" refers to the specific surface area measured by the BET method, specifically calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) using a BELSORP-mino II manufactured by BEL Japan. In other words, in this application, BET specific surface area may mean the specific surface area measured by the above measurement method.

[0026] In this specification, "Dn" means the average particle size, and represents the particle size at the n% point of the cumulative particle number distribution according to the particle size. That is, D50 is the particle size at the 50% point of the cumulative particle number distribution according to the particle size, D90 is the particle size at the 90% point of the cumulative particle number distribution according to the particle size, and D10 is the particle size at the 10% point of the cumulative particle number distribution according to the particle size. On the other hand, the average particle size can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns according to the particle size as the particles pass through the laser beam.

[0027] In this specification, when a polymer is said to contain a monomer as a monomer unit, it means that the monomer participates in the polymerization reaction and is included as a repeating unit in the polymer. In this specification, when a polymer is said to contain a monomer, this is interpreted in the same way as when the polymer contains a monomer as a monomer unit.

[0028] In this specification, unless otherwise specified, the term "polymer" is understood to be used in a broad sense, including copolymers.

[0029] In this specification, weight-average molecular weight (Mw) and number-average molecular weight (Mn) are polystyrene-equivalent molecular weights measured by gel permeation chromatography (GPC) using monodisperse polystyrene polymers of various degrees of polymerization (standard samples) commercially available for molecular weight measurement as standard substances. In this specification, molecular weight refers to weight-average molecular weight unless otherwise specified.

[0030] The present invention will be described in detail below with reference to the drawings so that a person with ordinary skill in the art to which the present invention pertains can easily implement it. However, the present invention may be realized in various different forms and is not limited to the following description.

[0031] One embodiment of this specification provides a jelly roll electrode assembly comprising: a first separator; a positive electrode laminated on one side surface of the first separator and including a positive electrode current collector; a second separator provided on the opposite side of the positive electrode from the surface in contact with the first separator; and a negative electrode including a negative electrode current collector provided on the opposite side of the second separator from the surface in contact with the positive electrode; wherein the jelly roll electrode assembly is wound around the negative electrode, forming a jelly roll hollow portion in the core, and the negative electrode current collector includes a negative electrode active material coated portion on which a negative electrode active material is applied, and a negative electrode plain portion on which the negative electrode active material is not applied, the negative electrode plain portion is formed at both ends of the negative electrode, at least one of the negative electrode plain portions at both ends has a negative electrode tab, and the negative electrode plain portion of the negative electrode current collector includes a protective tape on at least one side, the protective tape satisfying the following formula 1.

[0032] [Formula 1] 50%≦a≦100% In the above formula 1, a is (length of protective tape attached to the blank area of ​​the negative electrode / total length of the blank area of ​​the negative electrode) × 100%.

[0033] The jelly roll electrode assembly according to this application is a jelly roll electrode assembly having a structure in which a hollow jelly roll portion is formed in the center and wound around the negative electrode in order to realize the outermost structure of the negative electrode current collector, and the plain negative electrode portion of the negative electrode current collector has a protective tape that satisfies formula 1 on at least one side. As a result, even if the process includes winding starting from the center of the thin negative electrode current collector, the protective tape provides rigidity to the negative electrode current collector and prevents the formation of wrinkles during winding, thereby improving the wrinkles of the electrode as a whole, and thus providing a jelly roll electrode assembly that does not have wrinkles formed.

[0034] In one embodiment of this application, a first separator, a positive electrode including a positive electrode current collector laminated on one side of the first separator, a second separator laminated on one side of the positive electrode, and a negative electrode including a negative electrode current collector on the second separator can be represented as an electrode sheet.

[0035] That is, a jelly roll electrode assembly comprising a first separator; a positive electrode including a positive electrode current collector laminated on one side surface of the first separator; a second separator provided on the opposite side of the positive electrode from the surface in contact with the first separator; and a negative electrode including a negative electrode current collector provided on the opposite side of the second separator from the surface in contact with the positive electrode, wherein the jelly roll electrode assembly has a structure in which a jelly roll hollow portion is formed in the core portion around the negative electrode and wound up, can be described as a jelly roll electrode assembly having a structure in which the electrode sheet is wound up.

[0036] In one embodiment of this application, the process for manufacturing a jelly roll electrode assembly includes the step of preparing and stacking a positive electrode, a negative electrode, a first separator, and a second separator, respectively.

[0037] In the above steps, the first separator, positive electrode, second separator, and negative electrode are stacked in that order, and a jelly roll hollow section is formed in the core part with the negative electrode at the center and wound up. By stacking and winding in the above manner, a jelly roll electrode assembly, which is the outermost structure of the negative electrode current collector, can be formed.

[0038] Figure 1 is a diagram illustrating a method for winding an electrode sheet in the form of a jelly roll electrode assembly according to one embodiment of the present application. Specifically, the structure consists of a first separator 4, a positive electrode 3 including a positive electrode current collector laminated on one side of the first separator, a second separator 2 laminated on one side of the positive electrode 3, and a negative electrode 1 including a negative electrode current collector laminated on the second separator 2. A jelly roll hollow portion 100 is formed in the center, and it can be confirmed that the assembly is wound around the negative electrode 1. Furthermore, as can be seen from Figure 1, it can be confirmed that the negative electrode 1 including the negative electrode current collector is wound separately again to form a jelly roll electrode assembly with the outermost negative electrode current collector.

[0039] Figure 2 shows a conventional separator outermost structure, which has the form of positive electrode 3 / second separator 2 / negative electrode 1 / first separator 4, with a jelly roll hollow section 100 formed in the center, and a structure that is wound around the positive electrode 3, and the jelly roll electrode assembly that is ultimately produced can be shown as the outermost structure of the first separator 4.

[0040] In one embodiment of this application, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on one or both sides of the positive electrode current collector, which contains positive electrode active material.

[0041] In one embodiment of this application, a jelly roll electrode assembly is provided, wherein the positive electrode current collector includes a positive electrode active material coated portion on which a positive electrode active material is applied, and a positive electrode blank portion on which the positive electrode active material is not applied, and a positive electrode tab is included on the positive electrode blank portion.

[0042] In one embodiment of this application, the positive electrode active material layer is formed on the active material coated portion of the positive electrode current collector, and the surface on which the positive electrode active material layer is not provided can be referred to as the positive electrode blank portion.

[0043] Specifically, as can be seen from 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 blank positive electrode portion 14 where the positive electrode active material layer 17 is not coated, and the positive electrode tab 13 is provided on the blank portion.

[0044] In the positive electrode, the positive electrode current collector is not particularly limited as long as it does not induce a chemical change in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. may be used. The positive electrode current collector may also have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the current collector to increase the adhesion strength of the positive electrode active material. For example, it may be used in various forms such as film, sheet, foil, mesh, porous material, foam, nonwoven fabric.

[0045] The positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be 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; or a compound with the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0 ≤ c1 ≤ 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 Ni-site type lithium nickel oxide represented as Mc2O2 (where M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01 ≤ c2 ≤ 0.3); chemical formula LiMn 2-c3 M c3Lithium manganese composite oxides represented as O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, satisfying 0.01 ≤ c3 ≤ 0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion, etc., are examples but are not limited thereto. The positive electrode may be Li-metal.

[0046] The positive electrode active material layer may also include a positive electrode conductive material and a positive electrode binder, along with the positive electrode active material described above.

[0047] In this case, the positive electrode conductive material is used to impart conductivity to the electrode, and can be used without particular limitation as long as it has electronic conductivity without causing a chemical change in the battery that is constructed. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these alone or a mixture of two or more may be used.

[0048] Furthermore, the positive electrode binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one or more of these may be used.

[0049] In one embodiment of this application, the positive electrode current collector may include a blank positive electrode portion and include a positive electrode tab formed on the blank positive electrode portion, and the jelly roll electrode assembly according to this application may include one positive electrode tab.

[0050] In this case, the blank area of ​​the positive electrode may be formed in the center of the positive electrode.

[0051] In one embodiment of this application, the negative electrode may include a negative electrode current collector and a negative electrode active material layer, and the negative electrode current collector may include a negative electrode active material coated portion on which the negative electrode active material is applied and a negative electrode plain portion on which the negative electrode active material is not applied.

[0052] Specifically, as can be seen from Figure 3, the negative electrode 1 is provided on the second separator 2, and the negative electrode 1 includes a blank negative electrode portion 15 at both ends of the negative electrode where the negative electrode active material layer 16 is not coated, and it can be confirmed that at least one of the blank negative electrode portions at both ends is provided with a negative electrode tab 10.

[0053] The jelly roll electrode assembly according to this application includes a plain negative electrode portion at both ends of the negative electrode, and at least one of the plain negative electrode portions at both ends includes a negative electrode tab. Specifically, the plain negative electrode portion on the winding core side may include a negative electrode tab.

[0054] In one embodiment of this application, the negative electrode active material layer may include one or more negative electrode active materials selected from the group consisting of silicon-based materials and carbon-based materials.

[0055] Furthermore, in one embodiment of this application, the negative electrode active material layer may include a negative electrode conductive material and a negative electrode binder.

[0056] In one embodiment of this application, the negative electrode active material; negative electrode conductive material; and negative electrode binder can be any material used in the industry without limitation.

[0057] In one embodiment of this application, the negative electrode current collector is not particularly limited as long as it does not induce a chemical change in the battery and is conductive. For example, the current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. Specifically, transition metals that readily adsorb carbon, such as copper and nickel, may be used as the current collector. The thickness of the current collector may be 6 μm to 20 μm, but is not limited thereto.

[0058] The negative electrode binder may contain at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and substances in which the hydrogen atoms of these substances are substituted with Li, Na, or Ca, and may also contain a variety of copolymers thereof.

[0059] The negative electrode conductive material is not particularly limited as long as it does not induce a chemical change in the battery and is conductive. For example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0060] In one embodiment of this application, the first and second separators separate the negative and positive electrodes and provide a passage for lithium ions to move. They are not particularly limited as long as they are commonly used as separators in secondary batteries, and are preferably low resistance to ion movement of the electrolyte and have excellent electrolyte moisture retention capacity. Specifically, porous polymer films, such as porous polymer films made from polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof may be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, coated separators containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and may be selectively used as single-layer or multi-layer structures.

[0061] In one embodiment of this application, the negative electrode current collector includes a negative electrode active material coated portion on which a negative electrode active material is applied, and a negative electrode plain portion on which the negative electrode active material is not applied, the negative electrode plain portion is formed at both ends of the negative electrode, at least one of the negative electrode plain portions at both ends has a negative electrode tab, and the negative electrode plain portion of the negative electrode current collector includes a protective tape on at least one side, the protective tape satisfying the following formula 1, thereby providing a jelly roll electrode assembly.

[0062] [Formula 1] 50%≦a≦100% In the above formula 1, a is (length of protective tape attached to the blank area of ​​the negative electrode / total length of the blank area of ​​the negative electrode) × 100%.

[0063] In one embodiment of this application, the plain negative electrode portion is formed at both ends of the negative electrode, and one of them may be formed in the hollow portion of the jelly roll. Specifically, this corresponds to position 100 in Figure 1 and, as can be seen from Figure 3, may mean the portion of the negative electrode end where winding begins.

[0064] In one embodiment of this application, the negative electrode current collector includes a negative electrode active material coated portion on which a negative electrode active material is applied, and a negative electrode plain portion on which the negative electrode active material is not applied, the negative electrode plain portion is formed at both ends of the negative electrode, one of the negative electrode plain portions at both ends has a negative electrode tab, the negative electrode plain portion of the negative electrode current collector includes a protective tape on at least one side, the protective tape satisfies formula 1, and the present invention provides a jelly roll electrode assembly.

[0065] In one embodiment of this application, the negative electrode current collector includes a negative electrode active material coated portion on which a negative electrode active material is applied, and a negative electrode plain portion on which the negative electrode active material is not applied, the negative electrode plain portion is formed at both ends of the negative electrode, one of the negative electrode plain portions has a negative electrode tab, the negative electrode tab is located at the end of the negative electrode plain portion that is located in the hollow portion of the jelly roll of the negative electrode, the negative electrode plain portion of the negative electrode current collector includes a protective tape on at least one side, the protective tape satisfies formula 1, and the invention provides a jelly roll electrode assembly.

[0066] In one embodiment of this application, the plain negative electrode portion of the negative electrode current collector includes a protective tape on at least one side, and the protective tape satisfies formula 1, providing a jelly roll electrode assembly.

[0067] In another embodiment, the plain negative electrode portion of the negative electrode current collector includes a protective tape on one side, and the protective tape satisfies formula 1, providing a jelly roll electrode assembly.

[0068] In another embodiment, the negative electrode plain portion of the negative electrode current collector includes protective tape on both sides, and the protective tape satisfies formula 1, providing a jelly roll electrode assembly.

[0069] The jelly roll electrode assembly according to this application includes a protective tape satisfying the above formula 1 on at least one side of the plain negative electrode portion of the negative electrode current collector. This allows for a winding process starting from the center of the thin negative electrode current collector, while the protective tape provides rigidity to the negative electrode current collector, preventing wrinkle formation during winding. As a result, wrinkles in the entire electrode can be improved, providing a jelly roll electrode assembly free of wrinkles.

[0070] In other words, the main objective of the present invention is to have the feature that, when a protective tape having the above-mentioned length is attached to at least one surface of the plain negative electrode portion of the jelly roll electrode assembly according to this application, the problem of wrinkle formation in conventional electrodes can be solved.

[0071] In one embodiment of this application, the negative electrode blank portion includes a first negative electrode blank surface on which the negative electrode tab is provided; and a second negative electrode blank surface which is the opposite surface of the first negative electrode blank surface, and the protective tape is formed on the first negative electrode blank surface and the second negative electrode blank surface, and the protective tape satisfies the following formulas 2 and 3, providing a jelly roll electrode assembly.

[0072] [Formula 2] 25%≦a1≦100% [Formula 3] 25%≦b1≦100% In equations 2 and 3, a1 is (length of protective tape attached to the blank area of ​​the first negative electrode / total length of the blank area of ​​the first negative electrode) × 100%, b1 is (length of protective tape attached to the blank area of ​​the second negative electrode / total length of the blank area of ​​the second negative electrode) × 100%, At least one of a1 and b1 is 50% or more.

[0073] Specifically, the above details can be confirmed from Figure 4. Figure 4 is a diagram showing the core portion of the negative electrode according to this application. Specifically, a negative electrode tab 10 is provided on the blank negative electrode portion included in the core portion at both ends of the negative electrode. The length 23 of the protective tape attached to the first blank negative electrode portion and the total length 21 of the first blank negative electrode portion can be confirmed, and the length 24 of the protective tape attached to the second blank negative electrode portion and the total length 22 of the second blank negative electrode portion can be confirmed, respectively.

[0074] In one embodiment of this application, formula 2 may satisfy the range 25% ≤ a1 ≤ 100%, the range 50% ≤ a1 ≤ 100%, and the range 70% ≤ a1 ≤ 100%.

[0075] In one embodiment of this application, the protective tape attached to the plain portion of the first negative electrode is formed to cover the negative electrode tab, and has the feature of fixing the negative electrode tab and improving the wrinkle phenomenon of the plain portion of the negative electrode current collector when it is wound up.

[0076] In one embodiment of this application, formula 3 may satisfy the range 25% ≤ b1 ≤ 100%, the range 50% ≤ b1 ≤ 100%, and the range 70% ≤ b1 ≤ 100%.

[0077] In one embodiment of this application, when a protective tape is included in the first negative electrode plain portion on which the negative electrode tab is provided, and a protective tape that covers the above range is also included in the second negative electrode plain portion on the opposite side, the core wrinkle occurrence rate is significantly reduced compared to when the protective tape is only on one side.

[0078] In other words, when a protective tape of the aforementioned length is attached to one of the plain negative electrode portions of the jelly roll electrode assembly, the problem of wrinkle formation in conventional electrodes can be solved. At the same time, especially when protective tape is provided on both the first and second plain negative electrode portions, in addition to solving the wrinkle formation problem, the jelly roll-like core portion has rigidity, resulting in an even greater improvement in the collapse of the core portion.

[0079] One embodiment of this application provides a jelly roll electrode assembly in which a1 is 100% and b1 is 100%.

[0080] In this application, when a1 is 100% and b1 is 100%, it may mean that the entire surface of both sides of the blank negative electrode portion on which the negative electrode tab is provided is covered with protective tape.

[0081] One embodiment of this application provides a jelly roll electrode assembly comprising one positive electrode tab and one negative electrode tab.

[0082] As can be seen from Figure 3, the negative electrode tab of the jelly roll electrode assembly according to the present invention is located at the end of the negative electrode that is located in the core of the negative electrode, and the positive electrode tab is formed in the center of the positive electrode, not on the outer casing of the positive electrode. The assembly may include one positive electrode tab and one negative electrode tab.

[0083] As described above, when one positive electrode tab and one negative electrode tab are included, the resistance may be higher compared to when two or more are included. However, by including only one of each, the area of ​​blank space is reduced, allowing for the inclusion of more positive and negative electrode active materials, thus resulting in a significant increase in capacity.

[0084] In other words, the jelly roll electrode assembly according to the present invention includes one positive electrode tab and one negative electrode tab, and is not used for high-power applications but for high-capacity applications, and the difference in purpose can be confirmed according to the number of positive electrode tabs and negative electrode tabs.

[0085] One embodiment of this application provides a jelly roll electrode assembly comprising: a positive electrode active material layer provided on both sides of the positive electrode active material coated portion of the positive electrode current collector; and a negative electrode active material layer provided on both sides of the negative electrode active material coated portion of the negative electrode current collector.

[0086] As described above, when both sides contain an active material layer, it is possible to include even more active material, resulting in a characteristic of maximizing the capacity.

[0087] In one embodiment of this application, the jelly roll electrode assembly is provided, wherein the jelly roll electrode assembly is the outermost structure of the negative electrode current collector.

[0088] A manufacturing method having the outermost structure of the negative electrode current collector can be seen from Figure 1. As can be seen from Figure 1, a hollow jelly roll section 100 is formed in the center, and the negative electrode 1 is wound around it. Finally, only the negative electrode current collector contained in the negative electrode 1 is wound again around the outer casing of the jelly roll electrode assembly, thereby forming the outermost exposed structure of the negative electrode current collector.

[0089] In other words, the outermost structure of the negative electrode current collector is a structure manufactured by changing the winding order of the positive and negative electrodes so that the negative electrode current collector is exposed to the outermost layer, enabling direct contact between the negative electrode current collector and the inner wall of the battery casing material described later, and having the characteristic that electrical connection with the can is possible even without an outer negative electrode tab. In other words, as described above, the jelly roll electrode assembly according to the present invention is equipped with one positive electrode tab and one negative electrode tab, thereby enabling a high-capacity battery, and the above characteristics are realized by forming the negative electrode current collector to the outermost layer.

[0090] In one embodiment of this application, a jelly roll electrode assembly is provided, wherein the protective tape is selected from the group consisting of PET (polyethylene terephthalate), PP (polypropylene), polyester, PC (polycarbonate), PI (polyimide), PEN (polyethylene naphthalate), PEEK (polyether ether ketone), PAR (polyarylate), PCO (polycylicolefin), polynorbornene, PES (polyethersulphone), and COP (cycloolefin polymer).

[0091] The protective tape can be any tape that can secure the negative electrode tab and has sufficient rigidity to prevent bending of the plain negative electrode portion when winding, and specifically, PET may be used.

[0092] In one embodiment of this application, a jelly roll electrode assembly is provided in which the thickness of the protective tape is 10 μm or more and 100 μm or less.

[0093] One embodiment of this application provides a cylindrical lithium secondary battery comprising: a battery casing; a jelly roll electrode assembly according to this application provided inside the battery casing; and an outer cap with electrodes provided at an opening in the battery casing.

[0094] The contents of the jelly roll electrode assembly are as described above.

[0095] In one embodiment of this application, the battery casing material may contain an electrolyte.

[0096] Examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0097] Specifically, the electrolyte may contain a non-aqueous organic solvent and a metal salt.

[0098] Examples of the non-aqueous organic solvent include aprotic organic solvents such as N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triphosphate ester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate.

[0099] In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates among the carbonate-based organic solvents, can be preferably used as high-viscosity organic solvents because they have a high dielectric constant and can dissociate lithium salts well. When such cyclic carbonates are mixed with linear carbonates having low viscosity and low dielectric constant, such as dimethyl carbonate and diethyl carbonate, at an appropriate ratio, an electrolyte having high electrical conductivity can be produced, so it can be more preferably used.

[0100] A lithium salt may be used as the metal salt. The lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte solution. For example, as the anion of the lithium salt, F - , Cl - , I - , NO3 -, N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - , (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - , and (CF3CF2SO2)2N - You may use one or more selected from the group consisting of the following:

[0101] In addition to the components of the electrolyte, the electrolyte may further contain one or more additives for the purpose of improving battery life characteristics, suppressing the decrease in battery capacity, and improving battery discharge capacity, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride.

[0102] The jelly roll electrode assembly according to the present invention may be included in a cylindrical battery, and the cylindrical battery means that the shape of the battery itself, which includes an assembly containing a positive electrode, a negative electrode, a separator, and an electrolyte, is cylindrical, and specifically it can consist of a cylindrical can, a battery assembly provided inside the cylindrical can, and a top cap. [Examples]

[0103] The following are preferred embodiments to aid in understanding the present invention, but these embodiments are merely illustrative of the description, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the description and the technical concept, and such variations and modifications will naturally fall within the scope of the appended claims.

[0104] <Example 1> A first separator / positive electrode / second separator / negative electrode was stacked in the manner shown in Figure 3, a negative electrode tab was provided on the winding center side of the blank portion of the negative electrode current collector, and protective tape satisfying a = 100%, specifically a1 = 100% and b1 = 100%, was attached to both sides of the blank portion of the negative electrode current collector where the negative electrode tab was provided, and the assembly was wound up to form a jelly roll electrode assembly.

[0105] <Example 2> In the above-described embodiment 1, the jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that a protective tape with a value of 100%, specifically a1, was attached to one side of the plain portion of the negative electrode current collector on which the negative electrode tab was provided.

[0106] <Example 3> In the above-described embodiment 1, a jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that protective tape with a value of 80%, specifically a1 being 80% and b1 being 30%, was attached to both sides of the plain portion of the negative electrode current collector on which the negative electrode tab was provided.

[0107] <Example 4> In the above-described embodiment 1, a jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that protective tape with a ratio of 80%, specifically a1 being 30% and b1 being 80%, was attached to both sides of the plain portion of the negative electrode current collector on which the negative electrode tab was provided.

[0108] <Comparative Example 1> In the above-described embodiment 1, the jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that a protective tape with a value of 40%, specifically a1, was attached to one side of the plain portion of the negative electrode current collector on which the negative electrode tab was provided.

[0109] <Comparative Example 2> In the above-described embodiment 1, a jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that protective tape with a value of 40%, specifically a1 being 40% and b1 being 30%, was attached to both sides of the plain portion of the negative electrode current collector on which the negative electrode tab was provided.

[0110] <Comparative Example 3> In the above-described embodiment 1, the jelly roll electrode assembly was formed in the same manner as in embodiment 1, except that protective tape was not attached to both sides of the plain portion of the negative electrode current collector on which the negative electrode tab is provided.

[0111] The jelly roll electrode assemblies of Examples 1 to 4 are characterized in that a protective tape is formed on at least one side of the plain negative electrode portion of the negative electrode current collector, covering 50% or more of it, and the tape is formed on one or both sides of the plain portion. It was confirmed that this has the advantage of improving the wrinkles in the electrode, thereby increasing the lifespan and efficiency of the cylindrical lithium secondary battery containing it.

[0112] Specifically, in the case of Embodiment 1, protective tape is applied 100% to both sides of the plain portion of the negative electrode current collector on which the negative electrode tab is provided, and in the case of Embodiment 2, protective tape is applied 100% to the side of the plain portion of the negative electrode current collector on which the negative electrode tab is provided.

[0113] Comparing Examples 1 and 2, Example 1 showed a greater improvement in electrode wrinkles compared to Comparative Examples 1-3, and was found to be particularly superior in improving electrode wrinkles compared to Example 2 (with protective tape formed on one side). This is a result of forming rigid protective tape on both sides of the plain area.

[0114] In particular, Figure 5 shows the negative electrode according to Embodiment 1 of this application. Specifically, it can be seen that protective tape was applied to both sides of the plain area of ​​the negative electrode (shown by the dotted line) such that a satisfies 100%. In this case, it was confirmed that no wrinkles occurred on the negative electrode, and this demonstrated an improvement in the wrinkles of the electrode.

[0115] In Examples 3 and 4, protective tape is provided on both sides of the plain portion of the negative electrode current collector where the negative electrode tab is provided, provided that a1 and b1 are not 100%. Compared to Example 1, a small amount of wrinkling occurs in the electrodes, but it was confirmed that the wrinkling of the electrodes is improved to an extent that does not cause problems in driving the electrodes.

[0116] In Comparative Example 1, protective tape is formed on one side of the plain negative electrode area, and in Comparative Example 2, protective tape is formed on both sides of the plain negative electrode area. However, in both cases, the amount of protective tape is less than 50%, and it has been confirmed that even with protective tape, wrinkles still occur in the electrodes due to the winding of the electrode assembly. This can lead to a decrease in the performance of the lithium secondary battery and safety problems due to lithium deposition.

[0117] Figure 6 shows the negative electrode according to Comparative Example 1 of this application. Specifically, protective tape is attached to one side of the blank area of ​​the negative electrode (shown by a thin dotted line) such that a satisfies 40%, and it can be seen that 60% of the blank area of ​​the negative electrode is exposed. In this case, as can be seen from Figures 6 and 7, the length of the protective tape cannot be met, and it can be confirmed that wrinkles occur in the blank area of ​​the negative electrode (enlarged view of the thick dotted line), which causes wrinkles to occur throughout the negative electrode and leads to a decrease in the performance of the lithium secondary battery.

[0118] Comparative Example 3 is a case in which protective tape is not present on both sides. In this case, many wrinkles occur when the electrode assembly is wound up, which can lead to premature performance degradation of the lithium secondary battery and safety problems due to lithium deposition. The following items will also be disclosed. [Item 1] First separator; A positive electrode, including a positive electrode current collector, is laminated on one side surface of the first separator; A second separator provided on the opposite side of the positive electrode from the surface in contact with the first separator; and A jelly roll electrode assembly comprising a negative electrode including a negative electrode current collector provided on the opposite side of the second separator from the side in contact with the positive electrode, wherein the negative electrode is wound around a core portion with a jelly roll hollow portion formed therein, The negative electrode current collector includes a negative electrode active material coated portion on which the negative electrode active material is applied, and a negative electrode plain portion on which the negative electrode active material is not applied. The negative electrode blank portion is formed at both ends of the negative electrode, and at least one of the negative electrode blank portions at both ends has a negative electrode tab. The negative electrode plain portion of the negative electrode current collector includes protective tape on at least one side, and the protective tape satisfies the following formula 1, jelly roll electrode assembly: [Formula 1] 50%≦a≦100% In the above formula 1, a is (length of protective tape attached to the blank part of the negative electrode / total length of the blank part of the negative electrode) × 100%. [Item 2] The negative electrode blank portion includes a first negative electrode blank surface on which the negative electrode tab is provided, and a second negative electrode blank surface which is the opposite surface of the first negative electrode blank surface. The protective tape is formed on the plain surface of the first negative electrode and the plain surface of the second negative electrode. The protective tape is a jelly roll electrode assembly as described in item 1, satisfying the following formulas 2 and 3: [Formula 2] 25%≦a1≦100% [Formula 3] 25%≦b1≦100% In formulas 2 and 3, a1 is (length of protective tape attached to the blank part of the first negative electrode / total length of the blank part of the first negative electrode) × 100%, b1 is (length of protective tape attached to the blank area of ​​the second negative electrode / total length of the blank area of ​​the second negative electrode) × 100%, At least one of a1 and b1 is 50% or more. [Item 3] The positive electrode current collector includes a positive electrode active material coated portion on which the positive electrode active material is applied, and a positive electrode plain portion on which the positive electrode active material is not applied. The jelly roll electrode assembly according to item 1, comprising a positive electrode tab on the plain positive electrode portion. [Item 4] The jelly roll electrode assembly according to item 2, wherein a1 is 100% and b1 is 100%. [Item 5] The jelly roll electrode assembly according to item 3, comprising one positive electrode tab and one negative electrode tab. [Item 6] Positive electrode active material layers provided on both sides of the positive electrode active material coated portion of the positive electrode current collector; and The jelly roll electrode assembly according to item 3, comprising: a negative electrode active material layer provided on both sides of the negative electrode active material coated portion of the negative electrode current collector; [Item 7] The protective tape is one selected from the group consisting of PET (polyethylene terephthalate), PP (polypropylene), polyester, PC (polycarbonate), PI (polyimide), PEN (polyethylene naphthalate), PEEK (polyether ether ketone), PAR (polyarylate), PCO (polycylicolefin), polynorbornene, PES (polyethersulphone), and COP (cycloolefin polymer), as described in item 1, for the jelly roll electrode assembly. [Item 8] The jelly roll electrode assembly described in item 1, wherein the thickness of the protective tape is 10 μm or more and 100 μm or less. [Item 9] The jelly roll electrode assembly is the outermost structure of the negative electrode current collector, as described in item 1. [Item 10] Battery casing material; A jelly roll electrode assembly according to any one of items 1 to 9 provided inside the battery casing; and An outer cap having electrodes provided at the opening of the aforementioned battery casing material; A cylindrical lithium-ion secondary battery, including one.

Claims

1. An electrode that is wound into a jelly roll shape, An electrode current collector having a first surface and a second surface facing the first surface, wherein the first surface includes a first electrode area coated with an electrode active material and a first electrode area not coated with the electrode active material, and the second surface includes a second electrode area coated with the electrode active material and a second electrode area not coated with the electrode active material, and the first electrode area and the second electrode area extend from the first end of the electrode in the longitudinal direction of the electrode, An electrode tab is placed on the blank portion of the first electrode, A first protective tape is placed on the plain portion of the first electrode, covering at least a portion of the electrode tab in the longitudinal direction of the electrode, and extending in the longitudinal direction of the electrode only within the plain portion of the first electrode; A second protective tape is placed on the plain portion of the second electrode, with at least a portion facing the electrode tab, and extending in the longitudinal direction of the electrode only within the plain portion of the second electrode; Includes, The first protective tape satisfies the following formula 1, and the second protective tape satisfies the following formula 2, the electrodes: [Formula 1] 25%≦a1≦100% [Formula 2] 25%≦b1≦100% In formulas 1 and 2, a1 is (length of the first protective tape attached to the plain portion of the first electrode in the longitudinal direction of the electrode / length of the plain portion of the first electrode in the longitudinal direction of the electrode) × 100%, b1 is (length of the second protective tape attached to the plain portion of the second electrode in the longitudinal direction of the electrode / length of the plain portion of the second electrode in the longitudinal direction of the electrode) × 100%, At least one of a1 and b1 is 50% or more.

2. The electrode according to claim 1, wherein the electrode is a negative electrode.

3. The electrode according to claim 1, wherein the first protective tape extends from the end of the plain portion of the first electrode in the longitudinal direction of the electrode.

4. The electrode according to claim 1, wherein the first protective tape covers the entire width of the electrode tab in the longitudinal direction of the electrode.

5. The electrode according to claim 1, wherein the second protective tape is arranged on the plain portion of the second electrode so as to face the entire width of the electrode tab in the longitudinal direction of the electrode.

6. The electrode according to claim 1, wherein the electrode current collector includes a third electrode blank portion extending from a second end facing the first end in the longitudinal direction of the electrode.

7. The electrode according to claim 1, wherein a1 is 100% and b1 is 100%.

8. The electrode according to claim 1, wherein the first protective tape and the second protective tape are selected from the group consisting of PET (polyethylene terephosphate), PP (polypropylene), polyester, PC (polycarbonate), PI (polyimide), PEN (polyethylene naphthalate), PEEK (polyether ketone), PAR (polyarylate), PCO (polycyclicolefin), polynorbornene, PES (polyetherulphone), and COP (cycloolefin polymer).

9. The electrode according to claim 1, wherein the thickness of the first protective tape and the second protective tape is 10 μm or more and 100 μm or less.

10. The first electrode includes a current collector, A separation membrane placed on the surface of the first electrode, The electrode according to claim 1, comprising a second electrode including a second electrode current collector, The second electrode is positioned on the second surface of the separation membrane facing the first surface of the separation membrane which is coupled to the first electrode, A jelly roll electrode assembly in which the first end of the second electrode is wound before the first electrode, and a jelly roll hollow portion is formed in the core.

11. The jelly roll electrode assembly according to claim 10, wherein the first end of the second electrode is located in the hollow portion of the jelly roll.

12. The jelly roll electrode assembly according to claim 10, wherein the first electrode is a positive electrode and the second electrode is a negative electrode.

13. The first electrode includes a positive electrode current collector. The positive electrode current collector includes a positive electrode surface portion coated with a positive electrode active material and a positive electrode surface portion not coated with the positive electrode active material. The jelly roll electrode assembly according to claim 12, wherein a positive electrode tab is arranged on the blank positive electrode portion.

14. The electrode tab of the second electrode is a negative electrode tab. The jelly roll electrode assembly according to claim 13, wherein the negative electrode tab extends in the width direction of the second electrode and the positive electrode tab extends in the width direction of the first electrode.

15. The jelly roll electrode assembly according to claim 13, wherein the positive electrode ground portion includes a first positive electrode ground portion coated on the first surface of the positive electrode current collector and a second positive electrode ground portion coated on the second surface facing the first surface.

16. The electrode current collector of the second electrode is a negative electrode current collector. The negative electrode current collector includes a blank portion of the third electrode extending from the second end facing the first end in the longitudinal direction of the second electrode, The jelly roll electrode assembly according to claim 12, wherein the plain portion of the third electrode is located at the outermost edge.

17. The separation membrane is the first separation membrane, The jelly roll electrode assembly according to claim 10, further comprising a second separation membrane disposed on the opposite surface of the first electrode, which is opposite to the surface of the first electrode bonded to the first separation membrane.

18. Battery casing material, The jelly roll electrode assembly according to claim 10, disposed within the battery casing, A cylindrical lithium secondary battery, comprising an outer cap positioned at the opening of the battery casing material.

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