Electrode assembly and cylindrical lithium secondary battery comprising same

Abstract

The present invention provides an electrode assembly in which: a positive electrode including a positive electrode current collector and a positive electrode active material layer positioned on the positive electrode current collector; a negative electrode; and a separator interposed between the positive electrode and the negative electrode are wound in one direction, wherein Y defined by formula (1) is less than 0.38. Formula (1): Y = c × D / d, wherein, in formula (1), c is the curvature of a hollow part surrounded by the wound electrode assembly, D is the average particle diameter D50 (㎛) of positive electrode active material particles included in the positive electrode active material layer, and d is the thickness (㎛) of the positive electrode current collector.

Description

Electrode assembly and cylindrical lithium secondary battery including the same

[0001] [Cross-citation with related applications]

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0119329, filed September 7, 2023, and Korean Patent Application No. 10-2024-0081471, filed June 21, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] The present invention relates to an electrode assembly and a cylindrical lithium secondary battery including the same.

[0005]

[0006] Lithium secondary batteries have attracted significant attention for their numerous advantages, including high capacity, long lifespan, stability, durability, and reliability. Demand for lithium secondary batteries as an energy source is rapidly increasing due to technological advancements in electric vehicles, portable electronic devices, and other devices. Recent advancements in electric vehicle technology have led to a demand for high-energy-density batteries to improve the average vehicle range on a single charge.

[0007]

[0008] The present invention relates to an electrode assembly including a high-loading positive electrode, a curvature of a hollow portion surrounded by a wound electrode assembly, and an average particle diameter D of a positive electrode active material. 50 , by ensuring that the thickness of the positive electrode collector satisfies a specific relationship, a cylindrical lithium secondary battery having a high energy density can be provided, and at the same time, cracks can be prevented from occurring in the core when the electrode assembly for the cylindrical lithium secondary battery is wound.

[0009]

[0010] The present invention provides an electrode assembly comprising a positive electrode including a positive electrode current collector and a positive electrode active material layer positioned on the positive electrode current collector; a negative electrode and a separator interposed between the positive electrode and the negative electrode, which are wound in one direction, wherein Y, defined by the following formula (1), is less than 0.38.

[0011] Equation (1): Y = c × D / d

[0012] In the above equation (1), c is the curvature of the hollow portion surrounded by the wound electrode assembly, and D is the average particle diameter D of the positive electrode active material particles included in the positive electrode active material layer. 50 (㎛), and d is the thickness of the positive electrode collector (㎛).

[0013]

[0014] In addition, the present invention provides a cylindrical lithium secondary battery including the electrode assembly; a battery can in which the electrode assembly is accommodated; an electrolyte poured into the battery can; and a sealing body sealing an open end of the battery can.

[0015]

[0016] The electrode assembly of the present invention can provide a cylindrical lithium secondary battery having a high energy density. Since the cylindrical lithium secondary battery houses the electrode assembly in a battery can that hardly expands, when the loading amount of the positive electrode increases, the hollow space corresponding to the empty space becomes narrower, and the curvature of the hollow space surrounded by the rolled electrode assembly increases, which increases the probability of cracks occurring in the electrode current collector when the electrode assembly is rolled.

[0017] In addition, since the cylindrical lithium secondary battery houses the electrode assembly in a battery can that hardly expands, when the loading amount of the positive electrode increases, the thickness of the electrode assembly decreases as the loading amount increases due to insufficient space, which increases the probability of cracks occurring in the electrode current collector when the electrode assembly is wound.

[0018] The electrode assembly of the present invention has a high energy density and an average particle diameter D 50 By adjusting the curvature of the positive electrode current collector and the hollow portion to an appropriate ratio, the phenomenon of the positive electrode current collector being dimpled by the positive electrode active material (dimpling) is improved, thereby improving cracks in the electrode current collector when winding the electrode assembly. In order to increase the energy density of the positive electrode in a cylindrical lithium secondary battery, even if the thickness of the current collector is reduced and the radius of the winding core is reduced, cracks in the electrode current collector do not occur when winding the electrode assembly.

[0019]

[0020] The following drawings attached to this specification illustrate embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0021] FIG. 1 is a drawing showing the structure of a cylindrical secondary battery according to one embodiment of the present invention.

[0022] FIG. 2 is a drawing showing the configuration of a positive electrode of a cylindrical secondary battery according to one embodiment of the present invention.

[0023] Figure 3 is a flowchart for manufacturing an electrode assembly of a cylindrical secondary battery according to one embodiment of the present invention.

[0024] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0025]

[0026] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0027] In the present invention, "primary particle" refers to a particle unit that has no apparent grain boundary when observed under a magnification of 5,000 to 20,000 times using a scanning electron microscope. "Average particle diameter of primary particles" refers to the arithmetic mean value calculated after measuring the particle diameters of primary particles observed in a scanning electron microscope image.

[0028] In the present invention, a "secondary particle" is a particle formed by the aggregation of multiple primary particles. In the present invention, to distinguish it from conventional secondary particles formed by the aggregation of tens to hundreds of primary particles, secondary particles formed by the aggregation of 10 or fewer primary particles are referred to as "quasi-single particles."

[0029] In the present invention, "average particle diameter D 50 "It refers to the particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material powder, and can be measured using the laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume cumulative amount.

[0030] Lithium secondary batteries can be classified into cylindrical, square, and pouch-type batteries depending on the shape of the battery case. Among these, cylindrical batteries are manufactured by sequentially stacking sheet-shaped positive electrodes, separators, and negative electrodes on a cylindrical battery can, winding them in one direction, and then housing an electrode assembly, which is then sealed by covering the top of the battery can with a cap plate.

[0031] To improve the energy density of cylindrical batteries, the amount of active material contained in the electrode assembly must be increased, thereby maximizing the space utilization within the limited can. However, increasing the electrode loading to achieve high energy density in cylindrical lithium secondary batteries poses the problem of cracks occurring in the electrode current collector located at the center during the coiling process of the electrode assembly. If these cracks become severe, the electrode current collector within the coiled electrode assembly can break.

[0032] In the present invention, the curvature of the hollow portion surrounded by the wound electrode assembly including the positive electrode of the high-loading, the average particle diameter D of the positive electrode active material particles 50 , a cylindrical lithium secondary battery with improved energy density is provided by taking into account the thickness of the positive electrode collector, etc.

[0033] Hereinafter, the present invention will be described with reference to the drawings.

[0034] Referring to FIG. 1, a cylindrical lithium secondary battery (100) according to one embodiment of the present invention is manufactured in a cylindrical shape by rolling up a structure in which a cylindrical core cylinder (110) has a negative electrode (112), a separator (113), and a positive electrode (114) sequentially overlapped. The jelly roll manufactured in this way is accommodated in an aluminum can (120), and an electrolyte is injected while only one side of the can (120) is sealed with a sealant (130) by a method such as welding, and then the other side is also sealed with a sealant (130) to complete the cylindrical lithium secondary battery (100).

[0035] Referring to FIG. 2, the positive electrode (114) of the cylindrical secondary battery (100) according to one embodiment of the present invention is a layer structure (116) in which a mixture of an active material, a conductive material, a binder, etc. is coated on one side or both sides of a current collector (115) such as aluminum.

[0036] Referring to FIG. 3, it is a process flow chart for a method of manufacturing a cylindrical secondary battery (100) of high loading according to one embodiment.

[0037] First, the target capacity of the cylindrical secondary battery requiring high loading is determined (S312), and the average particle diameter (D) to satisfy the high loading is determined accordingly. 50 ) is selected (S314). Next, the thickness (d) of the positive electrode current collector (115) to satisfy the high-loading condition is determined (S316), and the radius and curvature (c) of the core cavity (110) are determined (S318).

[0038] Next, it is checked whether the "Y = c × D / d" values ​​for the determined parameters fall within the set value range (S320). If the "Y = cx D / d" values ​​for the parameters do not fall within the set value range, the process returns to the previous process, for example, S314, and repeats the process until it falls within the set value range.

[0039] Next, a cathode slurry is prepared by mixing the selected cathode active material, a conductive agent, and a binder (S322), and the prepared cathode slurry is applied to a cathode current collector (115) (S324), dried, and rolled (S326) to prepare a cathode (114).

[0040] Meanwhile, a negative electrode (112) is manufactured following the above process or separately from the above process. For example, a negative electrode slurry is manufactured by mixing a negative electrode active material, a conductive agent, and a binder (S328), the manufactured negative electrode slurry is applied to a negative electrode current collector (S330), and the same is dried and rolled (S332) to manufacture a negative electrode. Thereafter, a separator (113) is interposed between the manufactured positive electrode and negative electrode (S334), and the positive electrode (114), the separator (113), and the negative electrode (112) are wound (S336) to complete an electrode assembly of a jelly roll type cylindrical secondary battery (100).

[0041] Next, a cylindrical secondary battery (100) is completed by inserting a jelly roll type electrode assembly into a battery can, injecting electrolyte (S338), and sealing the can (S340).

[0042] Meanwhile, the process sequences of the process flow chart described above may be appropriately changed according to needs and circumstances. For example, the processes S314 for selecting a positive electrode active material (116), S316 for determining the thickness of a positive electrode current collector (115), and S318 for determining the radius and curvature of the core cavity (120) may be performed in any order.

[0043] An electrode assembly according to one embodiment of the present invention comprises: a positive electrode (114) including a positive electrode current collector (115) and a positive electrode active material layer (116) positioned on the positive electrode current collector (115); a negative electrode (112) and a separator (113) interposed between the positive electrode (114) and the negative electrode (112), which is wound in one direction; and Y, defined by the following equation (1), is less than 0.38.

[0044] Equation (1): Y = c × D / d

[0045] The above Y may be 0.01 to 0.3, or 0.1 to 0.2.

[0046]

[0047] In the above equation (1), c is the curvature (mm) of the hollow portion (110) surrounded by the wound electrode assembly. -1 ) and is defined as the reciprocal of the radius (mm) of the bottom surface of the cylindrical hollow portion (110) formed inside the electrode assembly. For example, the radius of the hollow portion (110) can be confirmed by scanning the hollow portion (110) of the electrode assembly in a direction parallel to the bottom surface of the electrode assembly and perpendicular to the axial direction of the electrode assembly using “computerized tomography (CT) equipment.” The distance of the electrode assembly pattern located at the innermost angle in the cross-section of the scanned hollow portion (110) is measured, and the average value of the longest major axis and the shortest minor axis is calculated to find the length of the radius of the bottom surface of the hollow portion (110). This is the same as the radius length of the core used in manufacturing the electrode assembly.

[0048] In one embodiment, c is 0.4 mm -1 1.0 mm in diameter -1 , or 0.4 mm -1 0.8 mm -1 , or 0.4 mm -1 0.7 mm -1 That is, the radius of the hollow part may be from 1 mm to 2.5 mm, or from 1.3 mm to 2.0 mm, or from 1.5 mm to 2.0 mm.

[0049]

[0050] In the above formula (1), D is the average particle diameter D of the positive electrode active material particles included in the positive electrode active material layer (116). 50(㎛). In one embodiment, D may be 3 ㎛ to 12 ㎛, or 3 ㎛ to 9 ㎛, or 3 ㎛ to 6 ㎛.

[0051]

[0052] In the above formula (1), d is the thickness (㎛) of the positive electrode current collector (115). According to one embodiment, d may be 12 ㎛ to 30 ㎛, or 15 ㎛ to 30 ㎛, or 17 ㎛ to 30 ㎛.

[0053]

[0054] In the positive electrode (114) included in the electrode assembly according to one embodiment of the present invention, the loading amount of the positive electrode active material layer (116) is 30 mg / cm 2 Above, 35 mg / cm 2 Above, 40 mg / cm 2 or more than 45 mg / cm 2 It could be strange.

[0055]

[0056] In the case where the positive electrode (114) included in the electrode assembly according to one embodiment of the present invention is a high-loading positive electrode, the loading amount of the positive electrode active material layer (116) is 50 mg / cm 2 Excess, 50.5 mg / cm 2 Above, 51 mg / cm 2 Above, 52 mg / cm 2 Above, 53 mg / cm 2 Above, 54 mg / cm 2 Above, 55 mg / cm 2 Above, 56 mg / cm 2 Above, 57 mg / cm 2 Above, 50 mg / cm 2 Exceeding 65 mg / cm 2 Below 50 mg / cm 2 Exceeding 64 mg / cm 2 Below 50 mg / cm 2 Exceeding 63 mg / cm 2 Below 50 mg / cm 2 Exceeding 62 mg / cm 2 Below 50 mg / cm2 Exceeding 61 mg / cm 2 Below 50 mg / cm 2 Exceeding 60 mg / cm 2 Below, 51 mg / cm 2 More than 65 mg / cm 2 Below, 51 mg / cm 2 More than 64 mg / cm 2 Below, 51 mg / cm 2 More than 63 mg / cm 2 Below, 51 mg / cm 2 More than 62 mg / cm 2 Below, 51 mg / cm 2 More than 61 mg / cm 2 Below, 51 mg / cm 2 More than 60 mg / cm 2 Below, 52 mg / cm 2 More than 65 mg / cm 2 Below, 52 mg / cm 2 More than 64 mg / cm 2 Below, 52 mg / cm 2 More than 62 mg / cm 2 Below, 52 mg / cm 2 More than 60 mg / cm 2 Below 55 mg / cm 2 More than 65 mg / cm 2 Below 55 mg / cm 2 More than 64 mg / cm 2 Below 55 mg / cm 2 More than 62 mg / cm 2 Below 55 mg / cm 2 More than 60 mg / cm 2 It may be as follows. The loading amount of the positive electrode active material layer (116) may refer to the total loading amount of the entire double-sided electrode. In another example, the positive electrode (114) included in the electrode assembly of the present invention may be a single-sided positive electrode in which the positive electrode active material layer (116) is formed on one side of the positive electrode current collector (115), and in the case of a single-sided positive electrode, the loading amount may be a range obtained by multiplying the loading amount range by 1 / 2.

[0057]

[0058] The positive electrode (114) of the present invention may be formed in a structure in which a positive electrode active material layer (116) is formed on one or both sides of a long sheet-shaped positive electrode current collector (115), and the positive electrode active material layer (116) may include a conductive material and a binder in addition to the positive electrode active material (116).

[0059] For example, the positive electrode can be manufactured by applying a positive electrode slurry prepared by dispersing a positive electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water on one or both sides of a long sheet-shaped positive electrode collector, removing the solvent of the positive electrode slurry through a drying process, and then rolling.

[0060] As the positive electrode current collector (115), various positive electrode current collectors used in the relevant technical field can be used. For example, the positive electrode current collector (115) may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. Meanwhile, fine unevenness may be formed on the surface of the positive electrode current collector (115) to increase the adhesive strength of the positive electrode active material. The positive electrode current collector (115) may be made of various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. In one embodiment, an aluminum thin film may be used in terms of elongation control, etc.

[0061]

[0062] Meanwhile, as the positive electrode active material, positive electrode active materials generally used in the relevant technical field can be used.

[0063] For example, the positive electrode active material may include a lithium nickel-based oxide represented by the following [chemical formula 2].

[0064] [Chemical Formula 2]

[0065] Li x Ni y Co z M 1 p M 2 q O2

[0066] In the above chemical formula 2, M 1 may be Mn, Al or a combination thereof, for example, Mn or Mn and Al.

[0067] Above M 2 is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, and may be, for example, at least one selected from the group consisting of Zr, Y, Mg, and Ti, or may be Zr, Y or a combination thereof. M 2 Although elements are not essential, when included in appropriate amounts, they can promote grain growth during firing or play a role in improving crystal structure stability.

[0068] The above x represents the molar ratio of lithium in the lithium nickel-based oxide, and may be 0.8≤x≤1.2, 0.85≤x≤1.15, or 0.9≤x≤1.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel-based oxide can be stably formed.

[0069] The above y represents the molar ratio of nickel among all metals excluding lithium in the lithium nickel-based oxide, and may be 0.85≤y<1, 0.86≤y<1, or 0.88≤y<1. When the molar ratio of nickel satisfies the above range, high energy density is exhibited, enabling high capacity implementation.

[0070] The above z represents the molar ratio of cobalt among all metals excluding lithium in the lithium nickel oxide, and is 0. <z<0.15, 0<z<0.14, 또는 0.01≤z≤0.12일 수 있다. 코발트의 몰비가 상기 범위를 만족할 때, 양호한 저항 특성 및 출력 특성을 구현할 수 있다.

[0071] The above p is M of all metals except lithium in lithium nickel oxide. 1 It represents the molar ratio of elements, 0 <p<0.15, 0<p<0.14, 또는 0.01≤p≤0.12일 수 있다. M 1 When the molar ratio of the elements satisfies the above range, the structural stability of the positive electrode active material is excellent.

[0072] The above q is M of all metals excluding lithium in lithium nickel oxide. 2 It represents the molar ratio of elements, and can be 0≤q≤0.1, or 0≤q≤0.05.

[0073]

[0074] Meanwhile, the cathode active material according to the present invention may further include, if necessary, a coating layer comprising one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S on the surface of the lithium nickel-based oxide particles. For example, the coating element may be Al, B, Co, or a combination thereof, or the coating element may be B.

[0075] When a coating layer exists on the surface of lithium nickel-based oxide particles, the contact between the electrolyte and the lithium composite transition metal oxide is suppressed by the coating layer, thereby reducing the elution of transition metal or gas generation due to side reactions with the electrolyte.

[0076]

[0077] The above positive electrode active material may be included in an amount of 80 wt% to 99 wt%, or 85 wt% to 99 wt%, or 90 wt% to 99 wt% based on the total weight of the positive electrode active material layer.

[0078]

[0079] Meanwhile, the cathode active material according to the present invention may have a unimodal particle size distribution or a bimodal particle size distribution. By using a cathode active material having a unimodal particle size distribution, resistance increase can be minimized. When using a bimodal cathode active material that mixes a large-particle cathode active material with a small-particle cathode active material, the electrode density can be improved.

[0080]

[0081] Meanwhile, the form of the positive electrode active material is not particularly limited, and may be in the form of a secondary particle in which a plurality of primary particles are aggregated, a single particle formed of a single primary particle, or a combination thereof.

[0082] The above positive electrode active material may include a positive electrode active material composed of a single particle consisting of one primary particle and / or a pseudo-single particle that is an aggregate of 10 or fewer primary particles. By using a positive electrode active material composed of a single particle consisting of one primary particle and / or a pseudo-single particle that is an aggregate of 10 or fewer primary particles, a cylindrical battery having high capacity and excellent safety can be obtained.

[0083] Previously, spherical secondary particles composed of tens to hundreds of primary particles were commonly used as cathode active materials for lithium secondary batteries. However, these secondary particles, which are composed of numerous primary particles, are prone to particle breakage during the rolling process during the cathode manufacturing process, causing the primary particles to fall out, and cracks can form within the particles during charge and discharge. When the particles of the cathode active material break or cracks occur within the particles, the contact area with the electrolyte increases, which increases gas generation due to side reactions with the electrolyte. This increased gas generation within a cylindrical battery increases the pressure within the battery, posing a risk of battery explosion. In particular, when the volume of the cylindrical battery is increased, the amount of active material within the battery increases accordingly, which significantly increases the amount of gas generated, further increasing the risk of battery ignition and / or explosion.

[0084] In comparison, the positive electrode active material in the form of a single particle or a pseudo-single particle in which 10 or fewer primary particles are aggregated has higher particle strength than the existing secondary particle type positive electrode active material in which tens to hundreds of primary particles are aggregated, so that particle breakage hardly occurs during rolling. In addition, in the case of the positive electrode active material in the form of a single particle or a pseudo-single particle, since the number of primary particles constituting the particle is small, the change due to volume expansion and contraction of the primary particles during charge and discharge is small, and accordingly, the occurrence of cracks inside the particle is also significantly reduced.

[0085] Therefore, when using a cathode active material composed of single particles and / or pseudo-single particles, the amount of gas generated due to particle breakage and internal cracking can be significantly reduced, and thus, excellent safety can be achieved even in cylindrical batteries.

[0086]

[0087] Meanwhile, the positive electrode active material composed of the single particles and / or pseudo-single particles is included in an amount of 95 wt% to 100 wt%, or 98 wt% to 100 wt%, or 99 wt% to 100 wt%, or 100 wt%, based on the weight of the total positive electrode active material included in the positive electrode active material layer. When the content of the single particles and / or pseudo-single particles satisfies the above range, sufficient safety can be obtained when applied to a cylindrical battery.

[0088]

[0089] Next, the conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. For example, 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, carbon fiber, carbon nanotube, etc.; metal powder or metal fiber such as copper, nickel, aluminum, silver, etc.; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, etc., and one of these alone or a mixture of two or more thereof can be used as the conductive material.

[0090] The above-mentioned conductive material may be included in an amount of 0.1 wt% to 2.0 wt%, or 0.6 wt% to 2.0 wt%, or 1.2 wt% to 2.0 wt% based on the total weight of the positive electrode active material layer.

[0091]

[0092] The above binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode current collector, and examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more thereof may be used as the binder.

[0093] The above binder may be included in an amount of 1 wt% to 3 wt%, or 1.5 wt% to 3.0 wt%, or 2 wt% to 3 wt% based on the total weight of the positive electrode active material layer.

[0094]

[0095] The above negative electrode (112) may be formed in a structure in which a negative electrode active material layer is formed on one or both sides of a long sheet-shaped negative electrode collector, and the negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder.

[0096] For example, the negative electrode (112) can be manufactured by applying a negative electrode slurry prepared by dispersing a negative electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water on one or both sides of a long sheet-shaped negative electrode collector, removing the solvent of the negative electrode slurry through a drying process, and then rolling.

[0097]

[0098] As the negative electrode current collector, negative electrode collectors generally used in the relevant technical field can be used, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. The negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector (115), fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0099]

[0100] The above negative active material is Si, Si-Me alloy (wherein, Me is at least one selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiOy (wherein, 0 <y<2), Si-C 복합체 등과 같은 실리콘계 음극 활물질을 포함할 수 있고, 예를 들면 SiO, SiC 및 Si로 이루어지는 군으로부터 선택되는 실리콘계 음극 활물질을 포함할 수 있다.

[0101] As a negative electrode active material other than the silicon-based negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Examples thereof include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; lithium metal thin films; metal materials capable of alloying with lithium, such as Sn and Al; and a mixture of any one or two or more of these may be used.

[0102] A negative electrode (112) containing a silicon-based negative electrode active material can realize high capacity, but has a tendency to have poor structural stability due to extreme shrinkage and expansion during the charge / discharge process. Therefore, it is preferable to use it in combination with a carbon-based negative electrode active material. For example, a material containing a mixture of graphite and SiO can be used as the negative electrode active material.

[0103] The above silicon-based negative electrode active material may be included in an amount of 1 wt% to 5 wt%, or 4 wt% to 5 wt%, relative to the entire negative electrode active material layer.

[0104] The above conductive material is used to provide conductivity to the negative electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. For example, 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, summer black, carbon fiber, carbon nanotube, etc.; metal powder or metal fiber such as copper, nickel, aluminum, silver, etc.; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, etc., and one of these alone or a mixture of two or more thereof can be used as the conductive material.

[0105] The above-mentioned conductive material may typically be included in an amount of 0.01 wt% to 2.00 wt%, or 0.5 wt% to 2.0 wt%, or 0.75 wt% to 1.25 wt% based on the total weight of the negative electrode active material layer.

[0106]

[0107] The above binder serves to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. Examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more thereof may be used as the binder.

[0108] The above binder may be included in an amount of 0.1 wt% to 5.0 wt%, or 1 wt% to 6 wt%, or 2 wt% to 3 wt% based on the total weight of the negative electrode active material layer.

[0109]

[0110] In addition to the positive electrode (114) and negative electrode (112), a separator (113) interposed between the positive electrode (114) and negative electrode (112) separates the negative electrode (112) and positive electrode (114) and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries may be used without special restrictions. For example, the separator (113) may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. In addition, a conventional porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. Additionally, coated separators containing ceramic components or polymeric materials may be used to secure heat resistance or mechanical strength.

[0111]

[0112] In addition, the electrolyte used in the present invention may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc. that can be used in the manufacture of a lithium secondary battery.

[0113] For example, the electrolyte may include an organic solvent and a lithium salt.

[0114] The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. For example, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R represents a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. In one embodiment, a carbonate solvent may be used, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) may be used.

[0115]

[0116] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. For example, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of, and the lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. The concentration of the lithium salt can be used within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0117]

[0118] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 wt% to 10 wt% based on the total weight of the electrolyte.

[0119]

[0120] The external shape of the lithium secondary battery of the present invention may be a cylindrical or square shape using a can.

[0121] The cylindrical lithium secondary battery (100) according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0122] Examples of the above medium and large devices include, but are not limited to, electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles, and power storage systems.

[0123]

[0124]

[0125] Hereinafter, the present invention will be described through examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims.

[0126]

[0127] Example

[0128] Example 1

[0129] Average particle diameter D 50 This 10.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2, A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0130] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0131] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 2.0 mm, and the hollow curvature was 0.500 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0132]

[0133] Example 2

[0134] Average particle diameter D50 This 8.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2, Carbon nanotubes and PVDF binder were mixed in a weight ratio of 95:2:3 in N-methylpyrrolidone to prepare a cathode slurry. The cathode slurry was applied to both sides of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a cathode. The loading amount of the prepared cathode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0135] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0136] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.8 mm, and the hollow curvature was 0.556 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0137]

[0138] Example 3

[0139] Average particle diameter D 50 This 4.0㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0140] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0141] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.8 mm, and the hollow curvature was 0.556 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0142]

[0143] Example 4

[0144] Average particle diameter D 50 This 4.0㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0145] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0146] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.6 mm, and the hollow curvature was 0.625 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0147]

[0148] Comparative Example 1

[0149] Average particle diameter D 50 This 10.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 50 mg / cm based on a double-sided electrode. 2 It was.

[0150] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0151] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.6 mm, and the hollow curvature was 0.625 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0152]

[0153] Comparative Example 2

[0154] Average particle diameter D 50 This 10.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0155] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0156] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.6 mm, and the hollow curvature was 0.625 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0157]

[0158] Comparative Example 3

[0159] Average particle diameter D 50 This 8.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,Carbon nanotubes and PVDF binder were mixed in a weight ratio of 95:2:3 in N-methylpyrrolidone to prepare a cathode slurry. The cathode slurry was applied to one side of a 12.0 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a cathode. The loading amount of the prepared cathode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0160] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0161] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.8 mm, and the hollow curvature was 0.556 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0162]

[0163] Comparative Example 4

[0164] Average particle diameter D 50 This 10.5㎛ Li[Ni 0.9 Co 0.05 Mn 0.03 Al 0.02 ]O 2,A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95:2:3 in N-methylpyrrolidone. The positive electrode slurry was applied to one side of a 15 μm thick aluminum current collector sheet, dried at 120°C, and rolled to prepare a positive electrode. The loading amount of the prepared positive electrode active material layer was 58 mg / cm based on a double-sided electrode. 2 It was.

[0165] A negative electrode slurry was prepared by mixing a negative electrode active material (graphite: SiO = 95:5 weight ratio mixture), a conductive agent (super C), and styrene-butadiene rubber (SBR): carboxymethyl cellulose (CMC) in water at a weight ratio of 95:2:2:1. The negative electrode slurry was applied to one surface of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode.

[0166] A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode was laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The hollow radius of the manufactured electrode assembly was 1.8 mm, and the hollow curvature was 0.556 mm. -1 The electrode assembly manufactured as described above was inserted into a cylindrical battery can and an electrolyte was injected to manufacture a 2170 cylindrical cell having specifications of 21 mm in diameter and 70 mm in length.

[0167]

[0168] Experimental example

[0169] The initial capacity was measured for the 2170 cylindrical cells of Examples 1 to 4 and Comparative Examples 1 to 4. For example, each cell was charged to 4.2 V at a constant current of 0.2 C at 25 °C, and then discharged to 2.5 V at a constant current of 0.2 C, and the initial discharge capacity was measured. The results are shown in Table 1 below.

[0170] In addition, the occurrence of core cracks during winding was checked for the 2170 cylindrical cells of Examples 1 to 4 and Comparative Examples 1 to 4. The results are shown in Table 1 below.

[0171]

[0172] Y Initial capacity (mAh) Crack occurrence Exemplary example 10.3504955X Exemplary example 20.3154920X Exemplary example 30.1484980X Exemplary example 40.1675020X Comparative example 10.4384880X Comparative example 20.4385010O Comparative example 30.3945015O Comparative example 40.3894970O

[0173] As can be seen in Table 1, the lithium secondary batteries of Examples 1 to 4 using electrode assemblies having a Y value of less than 0.38 did not exhibit cracks when the electrode assemblies were wound, whereas the lithium secondary batteries of Comparative Examples 2 to 4 using electrode assemblies having a Y value of greater than 0.38 exhibited cracks when the electrode assemblies were wound. As in Comparative Example 1, the loading amount of the positive electrode was 50 mg / cm 2 It can be seen that the low electrode assembly does not have the problem of core cracking. Although the above has been described with reference to the embodiments of the present disclosure, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims below. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims

1. An electrode assembly comprising a positive electrode including a positive electrode current collector and a positive electrode active material layer positioned on the positive electrode current collector; a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode and the negative electrode are wound in one direction; An electrode assembly having Y defined by the following equation (1) of less than 0.

38. Equation (1): Y = c × D / d In the above equation (1), c is the curvature of the hollow portion surrounded by the wound electrode assembly, D is the average particle diameter of the positive electrode active material particles included in the positive electrode active material layer. 50 (㎛), d is the thickness of the positive electrode collector (㎛).

2. In claim 1, The loading amount of the above positive electrode active material layer is 50 mg / cm 2 Excessive electrode assembly.

3. In claim 1, The above c is an electrode assembly of 0.1 to 0.

5.

4. In claim 1, An electrode assembly in which the curvature c of the hollow portion surrounded by the above-mentioned wound electrode assembly is 1 / radius of the hollow portion (mm).

5. In claim 4, An electrode assembly having a hollow radius of 2 mm to 10 mm.

6. In claim 1, The above D is an electrode assembly having a size of 3 μm to 12 μm.

7. In claim 1, The above d is an electrode assembly having a size of 12 μm to 30 μm.

8. In claim 1, An electrode assembly wherein the positive electrode active material is a lithium nickel-based oxide represented by the following [chemical formula 1]. [Chemical Formula 1] Li x Ni y Co z M 1 p M 2 q O2 In the above chemical formula 1, M 1 is Mn, Al or a combination thereof, and M 2 is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, and 0.8≤x≤1.2, 0.8≤y<1, 0 <z<0.2, 0<p<0.2, 0≤q≤0.1임.

9. In claim 1, The above negative electrode includes a negative electrode active material layer including a negative electrode active material, An electrode assembly in which the negative electrode active material included in the above negative electrode active material layer is made of a mixture of graphite and SiO.

10. In claim 9, An electrode assembly comprising 1 to 5 wt% of SiO based on the total weight of the negative active material.

11. In claim 1, The loading amount of the above positive electrode active material layer is 30 mg / cm 2 Ideal electrode assembly.

12. A cylindrical lithium secondary battery comprising: the electrode assembly of claim 1; a battery can in which the electrode assembly is housed; an electrolyte poured into the battery can; and a sealing body sealing an open end of the battery can.

13. A method for manufacturing an electrode assembly comprising a positive electrode including a positive electrode current collector and a positive electrode active material layer positioned on the positive electrode current collector; a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode and the negative electrode are wound in one direction. A method for manufacturing an electrode assembly in which Y, defined by the following equation (1), is less than 0.

38. Equation (1): Y = c × D / d In the above equation (1), c is the curvature of the hollow portion surrounded by the wound electrode assembly, D is the average particle diameter of the positive electrode active material particles included in the positive electrode active material layer. 50 (㎛), d is the thickness of the positive electrode collector (㎛).

14. In claim 13, The loading amount of the above positive electrode active material layer is 50 mg / cm 2 A method for manufacturing an excess electrode assembly.

15. In claim 13, A method for manufacturing an electrode assembly wherein c is 0.1 to 0.

5.

16. In claim 13, A method for manufacturing an electrode assembly, wherein the curvature c of the hollow portion surrounded by the above-mentioned wound electrode assembly is 1 / radius of the hollow portion (mm), and the radius of the hollow portion is 2 mm to 10 mm.

17. In claim 13, The above D is a method for manufacturing an electrode assembly having a diameter of 3 μm to 12 μm.

18. In claim 13, A method for manufacturing an electrode assembly wherein the above d is 12 ㎛ to 30 ㎛.

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