Positive electrode, this method of producing the positive electrode, and lithium secondary battery.

Abstract

The invention relates to an anode. The anode comprises an anode-active material layer consisting of a first anode-active material and a second anode-active material with different average particle diameters. The average particle diameter D50 of the first anode-active material is greater than the average particle diameter D50 of the second anode-active material, the first and second anode-active materials consist of single-particle particles, and the interface resistance of the anode with SOC 50% measured in a coin half-cell produced using the anode is from 6.5 Ω to 8.5 Ω, and the interface resistance of the anode with SOC 10% measured in a coin half-cell produced using the anode is from 15 Ω to 19 Ω.

Description

Positive electrode, method for manufacturing the same, and lithium secondary battery Cross-citation with related applications This application claims the benefit of priority to Korean Patent Application No. 10-2023-0188990, filed December 21, 2023, and Korean Patent Application No. 10-2024-0151560, filed October 30, 2024, the entire contents of which are incorporated herein by reference. Technical field The present invention relates to a cathode, a method for manufacturing the same, and a lithium secondary battery, and more particularly, to a cathode having improved capacity, resistance characteristics, and high-temperature life characteristics, a method for manufacturing the same, and a lithium secondary battery. Recently, with the rapid spread of electronic devices that use batteries, such as mobile phones, laptops, computers, and electric vehicles, the demand for small, lightweight, and relatively high-capacity secondary batteries is rapidly increasing. In particular, lithium secondary batteries are gaining attention as a power source for portable devices because they are lightweight and have high energy density. Accordingly, research and development efforts are actively being conducted to improve the performance of lithium secondary batteries. The present invention aims to provide a cathode having excellent resistance characteristics and high-temperature lifespan characteristics as well as excellent capacity characteristics, a method for manufacturing the same, and a lithium secondary battery by introducing a low-efficiency cathode material that can complement the problem caused by a cathode material having high irreversible capacity loss during initial charge and discharge. [1] The present invention is a positive electrode including a positive electrode active material layer including a first positive electrode active material and a second positive electrode active material having different average particle diameters, wherein the average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50) is larger than the first positive electrode active material and the second positive electrode active material, the first positive electrode active material and the second positive electrode active material include single-particle particles, and the interface resistance of the positive electrode having an SOC of 50% measured in a coin half cell manufactured using the positive electrode is 6.5Ω to 8.5Ω, and the interface resistance of the positive electrode having an SOC of 10% measured in a coin half cell manufactured using the positive electrode is 15Ω to 19Ω. [2] The present invention provides a positive electrode, wherein, in the above [1], the first positive electrode active material includes a first lithium transition metal oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 Ni x1 Co y1 Mn z1 Al w1 M 1 v1 O2 In the above chemical formula 1, 0≤a1≤0.3, 0.82≤x1<1.0, 0 <y1≤0.2, 0<z1≤0.2, 0<w1≤0.2, 0≤v1≤0.1이고, M 1 is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. [3] The present invention provides a positive electrode, wherein, in the above [1] or [2], the second positive electrode active material includes a second lithium transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2 Ni x2 Co y2 Mn z2 Al w2 M 2 v2 O2 In the above chemical formula 2, 0≤a2≤0.3, 0.82≤x2<1.0, 0 <y2≤0.2, 0<z2≤0.2, 0<w2≤0.2, 0≤v2≤0.1이고, M 2is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. [4] The present invention, in at least one of the above [1] to [3], the average particle diameter (D) of the first positive electrode active material 50 ) provides an anode having a diameter of 6 μm to 12 μm. [5] The present invention, in at least one of the above [1] to [4], the average particle diameter (D) of the second positive electrode active material 50 ) provides an anode having a diameter of 1.5 μm to 5 μm. [6] The present invention provides a positive electrode, wherein in at least one of the above [1] to [5], the first positive electrode active material comprises a first lithium transition metal oxide and a first coating layer positioned on the surface of the first lithium transition metal oxide particles and containing cobalt (Co) in an amount of 1.5 mol% to 5 mol%. [7] The present invention provides a positive electrode, wherein in at least one of the above [1] to [6], the second positive electrode active material comprises a second lithium transition metal oxide and a second coating layer positioned on the surface of the second lithium transition metal oxide particles and containing cobalt (Co) in an amount of 0.2 mol% to 2.5 mol%. [8] The present invention provides a positive electrode, wherein in at least one of the above [1] to [7], the first positive electrode active material and the second positive electrode active material are included in a weight ratio of 80:20 to 40:60. [9] The present invention is a positive electrode including a positive electrode active material layer including a first positive electrode active material and a second positive electrode active material having different average particle diameters, wherein the average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50) is larger than the first cathode active material and the second cathode active material comprises single-particle particles, and the cathode has an IRR value of 96 to 166 defined by the following equation 1. [Formula 1] IRR = R CT50 ×R CT10 In the above formula 1, the R CT50 is a dimensionless number of the interface resistance (unit: Ω) of the positive electrode at 50% SOC measured in a coin half cell manufactured using the above positive electrode, and R CT10 is a dimensionless number of the interfacial resistance (unit: Ω) of the positive electrode at SOC 10% measured in a coin half-cell manufactured using the above positive electrode.

[0010] The present invention provides a lithium secondary battery comprising an electrode assembly including a positive electrode and a negative electrode according to any one of [1] to [9]; an electrolyte; and a battery case in which the electrode assembly and the electrolyte are accommodated, wherein the negative electrode includes a silicon-based negative electrode active material.

[0011] The present invention provides a lithium secondary battery, wherein, in the above

[0010] , the negative electrode includes a carbon-based negative electrode active material, and the silicon-based negative electrode active material and the carbon-based negative electrode active material are included in a weight ratio of 1:99 to 30:70.

[0012] The present invention comprises a step (S1) of mixing a first cathode active material in distilled water, performing a first washing, and drying; a step (S2) of mixing a second cathode active material in distilled water, performing a second washing, and drying; and a step (S3) of forming a cathode active material layer including the first cathode active material and the second cathode active material; wherein the first washing is performed at a higher temperature than the second washing, and the average particle diameter (D) of the first cathode active material is 50 ) is the average particle diameter (D) of the second positive electrode active material. 50) is larger than the first positive electrode active material and the second positive electrode active material, and the first positive electrode active material and the second positive electrode active material include single-particle particles, and the interface resistance of the positive electrode having an SOC of 50% measured in a coin half cell manufactured using the positive electrode is 6.5Ω to 8.5Ω, and the interface resistance of the positive electrode having an SOC of 10% measured in a coin half cell manufactured using the positive electrode is 15Ω to 19Ω.

[0013] The present invention provides a method for manufacturing an anode, wherein, in the above

[0012] , the first washing is performed at 20°C to 40°C.

[0014] The present invention provides a method for manufacturing an anode, wherein, in the above

[0012] or

[0013] , the second washing is performed at 3°C ​​to 18°C.

[0015] The present invention provides a method for manufacturing a positive electrode, wherein, in at least one of the above

[0012] to

[0014] , the first washing is performed by mixing the first positive electrode active material in an amount of 50 wt% to 70 wt% based on the total weight of distilled water.

[0016] The present invention provides a method for manufacturing a positive electrode, wherein, in at least one of the above

[0012] to

[0015] , the second washing is performed by mixing the second positive electrode active material in an amount of 65 wt% to 85 wt% based on the total weight of distilled water.

[0017] The present invention provides a method for manufacturing a positive electrode, wherein, in at least one of the above

[0012] to

[0016] , the first positive electrode active material includes a first lithium transition metal oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 Ni x1 Co y1 Mn z1 Al w1 M 1 v1 O2 In the above chemical formula 1, 0≤a1≤0.3, 0.82≤x1<1.0, 0 <y1≤0.2, 0<z1≤0.2, 0<w1≤0.2, 0≤v1≤0.1이고, M 1 is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo.

[0018] The present invention provides a method for manufacturing a positive electrode, wherein, in at least one of the above

[0012] to

[0017] , the second positive electrode active material includes a second lithium transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2 Ni x2 Co y2 Mn z2 Al w2 M 2 v2 O2 In the above chemical formula 2, 0≤a2≤0.3, 0.82≤x2<1.0, 0 <y2≤0.2, 0<z2≤0.2, 0<w2≤0.2, 0≤v2≤0.1이고, M 2 is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo.

[0019] The present invention provides a method for manufacturing a positive electrode, wherein, in at least one of the above

[0012] to

[0016] , the first positive electrode active material includes a first lithium transition metal oxide and includes a first coating layer including cobalt (Co) on the surface of the first lithium transition metal oxide particle, the second positive electrode active material includes a second lithium transition metal oxide and includes a second coating layer including cobalt (Co) on the surface of the second lithium transition metal oxide particle, and the amount of cobalt (Co) included in the first coating layer is greater than the amount of cobalt (Co) included in the second coating layer.

[0020] The present invention provides a method for manufacturing an anode, wherein, in the above

[0019] , the amount of cobalt (Co) in the first coating layer is 1.5 mol% to 5 mol%, and the amount of cobalt (Co) in the second coating layer is 0.2 mol% to 2.5 mol%. According to the present invention, since the bimodal positive electrode active material is included and the interfacial resistance of the positive electrode satisfies a specific range, the problem of irreversible capacity loss of the negative electrode can be supplemented without a separate sacrificial positive electrode material, thereby improving the capacity characteristics and life characteristics and improving the resistance characteristics. In addition, the positive electrode according to the present invention can reduce gas generation due to lithium byproduct generation during high-temperature storage, so that the high-temperature life characteristics of a lithium secondary battery including the positive electrode according to the present invention can be excellent. 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; therefore, the present invention should not be interpreted as being limited to matters described in such drawings. Figure 1 is a flow chart explaining a method for manufacturing a lithium secondary battery according to one embodiment of the present invention. Hereinafter, the present invention will be described in more detail. The 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 having meanings and concepts consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner. The terminology used in this specification is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In the present invention, the "single-particle type particle" means a particle formed by an aggregation of 30 or fewer sub-particles. The sub-particle unit constituting the single-particle type particle is called a nodule. The single-particle type particle includes a single particle composed of one nodule and a pseudo-single particle which is a composite of 2 to 30 nodules. The above “nodule” is a sub-particle unit that constitutes a single particle and a pseudo-single particle, and may be a single crystal without a crystalline grain boundary, or a polycrystal that has no apparent grain boundary when observed under a field of view of 5,000 to 20,000 times using a scanning electron microscope. In the present invention, a “secondary particle” means a particle formed by an aggregation of more than 30 sub-particles. In order to distinguish it from the sub-particles forming a single particle, the sub-particles forming a secondary particle are called “primary particles.” In the present invention, “particle” is a concept including any one or all of a single particle, a quasi-single particle, a primary particle, a nodule, and a secondary particle. In the present invention, the "average particle size D50" means a particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material powder, and can be measured using a laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and after irradiating the device with ultrasonic waves of about 28 kHz with an output of 60 W, a volume cumulative particle size distribution graph is obtained, and then the particle size corresponding to 50% of the volume cumulative amount is measured. In the present invention, the “interfacial resistance of a positive electrode having SOC 50% or SOC 10%” means the resistance measured at the interface between the positive electrode current collector and the positive electrode active material layer in a positive electrode having SOC 50% or SOC 10%. Specifically, in the present invention, the “interfacial resistance of the positive electrode with SOC 50% or SOC 10%” can be measured by interposing a separator between the positive electrode and the lithium metal counter electrode according to the present invention, injecting an electrolyte to manufacture a coin half-cell, and then charging the coin half-cell at 25°C under CC (constant current) / CV (constant voltage), 0.1C, 4.2V, 0.05C cut conditions, and performing two cycles of discharging to CC, 0.1C, 3.0V as one cycle, and then charging to SOC (State of Charge) 50% or SOC 10% at 0.1C, and then using a Biologic VMP3 device (100kHz to 10mHz range, 25°C conditions) for each coin half-cell charged to SOC 50% or SOC 10%. Carbonaceous materials such as graphite are mainly used as anode materials for lithium secondary batteries, but carbonaceous materials have a low capacity per unit mass, making it difficult to increase the capacity of lithium secondary batteries. Accordingly, non-carbonaceous anode materials that exhibit higher capacity than carbonaceous materials, such as silicon, tin, and oxides thereof, which form intermetallic compounds with lithium, are being developed and used. However, these anode materials have the problem of a large irreversible capacity loss during initial charge and discharge. To solve this problem, a method has been studied and proposed to overcome the irreversible capacity loss of the negative electrode by using a material that can provide a lithium ion supply source or storage as a positive electrode material and is electrochemically active after the first cycle so as not to deteriorate the performance of the battery itself. Specifically, there is a method of using a lithium nickel-based oxide such as Li2NiO2 as a sacrificial positive electrode material or an overdischarge prevention agent in the positive electrode. However, most of the above lithium nickel-based oxides are expensive and generate a lot of lithium byproducts, which increases the amount of gas generated, so a method to replace them is required. In order to supplement such problems, the present invention provides, according to one embodiment, a cathode having excellent resistance characteristics and high-temperature life characteristics and improved capacity characteristics, a method for manufacturing the same, and a lithium secondary battery by introducing a low-efficiency cathode material. In order to develop a high-capacity cell, it is essential to use a silicon-based negative electrode active material with high capacity. However, silicon-based negative electrode active materials have the disadvantage of low charge / discharge efficiency and high lithium ion loss rate due to irreversible reactions. Therefore, as charge / discharge is repeated, the loss of lithium in the positive electrode active material increases, which rapidly reduces the capacity of the battery during charge / discharge and may cause the collapse of the positive electrode active material structure. In order to solve the above problem, when using a cathode active material that is a single particle type, it is possible to implement a low-efficiency cathode active material that can provide lithium to a silicon-based anode active material during initial charge and discharge, so that even if irreversibility occurs in which lithium ions desorbed from the cathode active material are inserted into the anode active material and then not desorbed, it is possible to suppress or prevent deterioration of the life characteristics of the battery. However, when using a cathode active material in the form of a single particle, there is a problem in that the lithium diffusion path becomes longer than when using a lithium nickel oxide in the form of a secondary particle, which reduces the mobility of lithium ions and thus reduces the resistance characteristics and capacity characteristics. Accordingly, the inventors of the present invention provide a positive electrode having excellent life characteristics, which prevents or suppresses lithium ion loss due to an irreversible reaction of a silicon-based negative electrode active material, and prevents or suppresses degradation of the resistance characteristics of a battery, and has high energy density. Specifically, the present invention uses a single-particle positive electrode active material having a bimodal particle size distribution, and uses a positive electrode in which the interfacial resistance of the positive electrode is controlled within a specific range, so that the resistance characteristics of the battery can be improved while the life characteristics are excellent, and since it does not contain a separate lithium excess material like a conventional sacrificial positive electrode material, gas generation due to lithium byproduct generation during high-temperature storage can be minimized, and thus excellent high-temperature life characteristics, high energy density, and excellent capacity characteristics are also provided, a lithium secondary battery, and a method for manufacturing the positive electrode. Hereinafter, the present invention will be described in detail. The cathode, the method for manufacturing the same, and the lithium secondary battery according to the present invention comprise at least one of the following disclosed configurations, and may comprise any combination between technically possible configurations among the following configurations. anode The positive electrode according to the present invention is a positive electrode including a positive electrode active material layer including a first positive electrode active material and a second positive electrode active material having different average particle diameters, wherein the average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than the first positive electrode active material and the second positive electrode active material, and the first positive electrode active material and the second positive electrode active material include single-particle particles, and the interface resistance of the positive electrode having an SOC of 50% measured in a coin half cell manufactured using the positive electrode is 6.5Ω to 8.5Ω, and the interface resistance of the positive electrode having an SOC of 10% measured in a coin half cell manufactured using the positive electrode is 15Ω to 19Ω. The above positive electrode includes a positive electrode active material layer. Specifically, the positive electrode may include a positive electrode current collector; and a positive electrode active material layer positioned on the positive electrode current collector. As the positive electrode collector, various positive electrode collectors used in the relevant technical field can be used. For example, as the positive electrode collector, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. The positive electrode collector can typically have a thickness of 3 to 500 ㎛, and fine unevenness can be formed on the surface of the positive electrode collector to increase the adhesion of the positive electrode active material. The positive electrode collector 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. The above-mentioned positive electrode active material layer may be positioned on the positive electrode current collector, and specifically, may be positioned on one side or both sides of the positive electrode current collector. The above-mentioned positive electrode active material layer may have a single layer or a multilayer structure of two or more layers. The above positive electrode active material layer includes a first positive electrode active material and a second positive electrode active material. The above first cathode active material and the second cathode active material have an average particle diameter (D 50) are different, and specifically, the average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than that of the first cathode active material. Accordingly, when the electrode is rolled, the second cathode active material having a small particle size is filled into the pores of the first cathode active material having a large particle size, thereby increasing the electrode density and realizing a high energy density, thereby achieving high-capacity characteristics. The above first positive electrode active material includes single-particle particles. When the first positive electrode active material includes single-particle particles, since the single-particle particle size is large, the diffusion distance of lithium is long, so that the diffusion resistance increases, so that the positive electrode may have low efficiency, and thus, when applying a silicon-based negative electrode active material, the efficiency can be balanced with the negative electrode. Accordingly, the problem of lithium ion loss due to irreversible capacity when applying a conventional silicon-based negative electrode active material can be solved, and the lithium precipitation phenomenon on the surface of the negative electrode can be prevented, so that the life characteristics of a lithium secondary battery applying the positive electrode according to the present invention can be improved. In addition, when applying the first positive electrode active material which is a single-particle particle, unlike when using a conventional sacrificial positive electrode material, the generation of lithium byproducts due to the sacrificial positive electrode material during charge and discharge can be prevented or suppressed, so that the high-temperature storage characteristics and the high-temperature life characteristics can be superior to those when using a conventional sacrificial positive electrode material. The above first cathode active material may include a first lithium transition metal oxide containing nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al). Unlike ternary lithium transition metal oxides containing nickel, cobalt, and manganese, the first cathode active material according to the present invention further contains aluminum having a strong bonding force with oxygen atoms, thereby being structurally stable, and thereby suppressing cation mixing during charge and discharge, thereby being electrochemically stable at high potentials, so that thermal stability and capacity characteristics can be further improved. In addition, the first cathode active material may include a first lithium transition metal oxide containing nickel at 82 mol% or more among all metals excluding lithium. In this case, high-capacity characteristics of a lithium secondary battery can be implemented. Specifically, the first positive electrode active material may include a first lithium transition metal oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 Ni x1 Co y1 Mn z1 Al w1 M 1 v1 O2 In the above chemical formula 1, the M 1 may be at least one doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and preferably may be at least one doping element selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta and Nb. The above 1+a1 may mean a molar ratio of lithium (Li) in the first lithium transition metal oxide, and may be 0≤a1≤0.3, 0≤a1≤0.2, 0≤a1≤0.15, or 0≤a1≤0.1. When the above range is satisfied, a balance between the remarkable effect of improving the capacity characteristics of the first positive electrode active material according to the Li content control and the sinterability during the manufacture of the first positive electrode active material can be achieved. The above x1 may mean the molar ratio of nickel among the total metal excluding lithium in the first lithium transition metal oxide, and may be 0.82≤x1<1, 0.85≤x1<1, 0.90≤x1<1, or 0.92≤x1<1. When the above range is satisfied, a nickel content sufficient to contribute to charge and discharge in the lithium transition metal oxide is secured, thereby promoting high capacity. The above y1 may mean the molar ratio of cobalt among the total metals excluding lithium in the first lithium transition metal oxide, and 0 <y1≤0.2, 0<y1≤0.18, 0.01≤y1≤0.15, 0.03≤y1≤0.12, 또는 0.05≤y1≤0.10일 수 있다. 상기 범위를 만족할 경우, 코발트를 적은 함량으로 포함하여 비용적인 이점을 가지면서도 양호한 저항 특성 및 출력 특성을 구현할 수 있다. The above z1 may mean the molar ratio of Mn among the total metals excluding lithium in the first lithium transition metal oxide, and 0 <z1≤0.2, 0<z1≤0.18, 0.01≤z1≤0.15, 또는 0.03≤z1≤0.10일 수 있다. 상기 범위를 만족할 경우, 리튬 전이금속 산화물의 구조적 안정성을 향상시킬 수 있다. The above w1 may mean the molar ratio of Al among the total metals excluding lithium in the first lithium transition metal oxide, and 0 <w1≤0.2, 0<w1≤0.18, 0.01≤w1≤0.15, 또는 0.03≤w1≤0.10일 수 있다. 상기 범위를 만족할 경우, 산소와의 높은 결합력으로 인하여 리튬 전이금속 산화물의 열적 안정성을 향상시킬 수 있다. The above v1 is M among all metals except lithium in the first lithium transition metal oxide. 1 It can mean the molar ratio of v1 and can be 0≤v1≤0.1, 0≤v1≤0.08, or 0≤v1≤0.05. The first cathode active material may include a first lithium transition metal oxide and a first coating layer positioned on the surface of the first lithium transition metal oxide particles, and the first coating layer may include cobalt (Co). By means of the first coating layer, contact between the lithium transition metal oxide and the electrolyte is blocked, thereby suppressing occurrence of an electrolyte side reaction, thereby suppressing surface structure degradation of the lithium transition metal oxide that may occur during a charge and discharge process, thereby improving high-temperature life and suppressing an increase in resistance. The first coating layer may contain cobalt (Co) in an amount of 1.5 mol% to 5 mol%, 2 mol% to 4.5 mol%, 2.3 mol% to 4 mol%, 2.5 mol% to 3.5 mol%, or 2.7 mol% to 3.3 mol%. When the first coating layer contains cobalt in the above range, the first coating layer contains a larger amount of cobalt than the second coating layer included in the second positive electrode active material described below, thereby lowering the positive electrode interfacial resistance when the SOC of the coin half-cell including the positive electrode according to the present invention is 50%, thereby preventing the problem of initial resistance increasing due to a decrease in ion mobility during charge and discharge when a positive electrode active material that is a single particle is used, thereby improving the life characteristics and high-temperature life characteristics of the battery. The first coating layer may be formed on the entire surface of the first lithium transition metal oxide particle, or may be formed partially. Specifically, when the first coating layer is formed partially on the surface of the first lithium transition metal oxide particle, it may be formed in an area of ​​5% or more and less than 100%, preferably 20% or more and less than 100% of the entire surface area of ​​the surface of the first lithium transition metal oxide. The average particle diameter (D) of the first positive electrode active material 50) can be 6㎛ to 12㎛. Specifically, the average particle size of the first positive electrode active material may be 6 ㎛ or more, 6.2 ㎛ or more, 6.4 ㎛ or more, 6.6 ㎛ or more, 6.8 ㎛ or more, 7 ㎛ or more, 7.2 ㎛ or more, 7.4 ㎛ or more, 7.6 ㎛ or more, 7.8 ㎛ or more, 8 ㎛ or more, 8.2 ㎛ or more, 8.4 ㎛ or more, and may be 12 ㎛ or less, 11.8 ㎛ or less, 11.6 ㎛ or less, 11.4 ㎛ or less, 11.2 ㎛ or less, 11 ㎛ or less, 10.8 ㎛ or less, 10.6 ㎛ or less, 10.4 ㎛ or less, 10.2 ㎛ or less, 10 ㎛ or less, 9.8 ㎛ or less, 9.6 ㎛ or less, 9.4 ㎛ or less, 9.2 ㎛ or less, 9 ㎛ or less, 8.8 ㎛ or less, 8.6 ㎛ or less. For example, the average particle size of the first positive electrode active material may be 6 ㎛ to 12 ㎛, 7.4 ㎛ to 11 ㎛, 8 ㎛ to 9.6 ㎛, or 8.2 ㎛ to 9 ㎛. When the above range is satisfied, the rolling density of the positive electrode material can be increased, and thus the electrode density is improved during electrode manufacturing, thereby realizing excellent energy density. The above first positive electrode active material may be included in an amount of 20 wt% to 80 wt%, preferably 30 wt% to 70 wt%, and more preferably 40 wt% to 60 wt%, based on the total weight of the positive electrode active material layer. When the above range is satisfied, the rolling density can be improved to realize high energy density. Meanwhile, the second positive electrode active material includes single-particle particles. When the second positive electrode active material includes single-particle particles, since the single-particle particle size is large, the diffusion distance of lithium is long, so that the diffusion resistance increases, so that the positive electrode may have low efficiency, and thus, when applying a silicon-based negative electrode active material, the efficiency can be balanced with the negative electrode. Accordingly, the problem of lithium ion loss due to irreversible capacity when applying a conventional silicon-based negative electrode active material can be solved, and the lithium precipitation phenomenon on the surface of the negative electrode can be prevented or suppressed, so that the life characteristics of a lithium secondary battery applying the positive electrode according to the present invention can be improved. In addition, when applying a second positive electrode active material which is a single-particle particle, unlike when using a conventional sacrificial positive electrode material, the generation of lithium byproducts due to the sacrificial positive electrode material during charge and discharge can be prevented, so that the high-temperature storage characteristics and the high-temperature life characteristics can be excellent compared to when using a conventional sacrificial positive electrode material. The second positive electrode active material may include a second lithium transition metal oxide containing nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al). Unlike the ternary lithium transition metal oxide containing nickel, cobalt, and manganese, the first positive electrode active material according to the present invention further contains aluminum having a strong bonding force with oxygen atoms, thereby being structurally stable, and thereby suppressing cation mixing during charge and discharge, making it electrochemically stable at high potentials, so that thermal stability and capacity characteristics can be further improved. In addition, the second cathode active material may include a second lithium transition metal oxide containing nickel at 82 mol% or more among all metals excluding lithium. In this case, it is possible to implement high-capacity characteristics of a lithium secondary battery. Specifically, the second positive electrode active material may include a second lithium transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2Ni x2 Co y2 Mn z2 Al w2 M 2 v2 O2 In the above chemical formula 2, the M 2 may be at least one doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, or may be at least one doping element selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta and Nb. The above 1+a2 may mean a molar ratio of lithium (Li) in the second lithium transition metal oxide, and may be 0≤a2≤0.3, 0≤a2≤0.2, 0≤a2≤0.15, or 0≤a2≤0.1. When the above range is satisfied, a balance between the remarkable effect of improving the capacity characteristics of the second positive electrode active material according to the Li content control and the sinterability during the manufacture of the first positive electrode active material can be achieved. The above x2 may mean the molar ratio of nickel among the total metal excluding lithium in the second lithium transition metal oxide, and may be 0.82≤x2<1, 0.85≤x2<1, 0.90≤x2<1, 0.92≤x2<1. When the above range is satisfied, a nickel content sufficient to contribute to charge / discharge in the lithium transition metal oxide is secured, thereby promoting high capacity. The above y2 may mean the molar ratio of cobalt among the total metals excluding lithium in the second lithium transition metal oxide, and 0 <y2≤0.2, 0<y2≤0.18, 0.01≤y2≤0.15, 0.03≤y2≤0.12, 또는 0.05≤y2≤0.10일 수 있다. 상기 범위를 만족할 경우, 코발트를 적은 함량으로 포함하여 비용적인 이점을 가지면서도 양호한 저항 특성 및 출력 특성을 구현할 수 있다. The above z2 may mean the molar ratio of Mn among the total metals excluding lithium in the second lithium transition metal oxide, and 0 <z2≤0.2, 0<z2≤0.18, 0.01≤z2≤0.15, 또는 0.03≤z2≤0.10일 수 있다. 상기 범위를 만족할 경우, 리튬 전이금속 산화물의 구조적 안정성을 향상시킬 수 있다. The above w2 may mean the molar ratio of Al among the total metals excluding lithium in the second lithium transition metal oxide, and 0 <w2≤0.2, 0<w2≤0.18, 0.01≤w2≤0.15, 또는 0.03≤w2≤0.10일 수 있다. 상기 범위를 만족할 경우, 산소와의 높은 결합력으로 리튬 전이금속 산화물의 열적 안정성을 확보할 수 있다. The above v2 is M among all metals except lithium in the second lithium transition metal oxide. 2 It can mean the molar ratio of v2 and can be 0≤v2≤0.1, 0≤v2≤0.08, or 0≤v2≤0.05. The second positive electrode active material may include a second lithium transition metal oxide and a second coating layer positioned on the surface of the second lithium transition metal oxide particles, and the second coating layer may include cobalt (Co). By means of the second coating layer, contact between the lithium transition metal oxide and the electrolyte is blocked, thereby suppressing occurrence of electrolyte side reactions, thereby suppressing surface structure degradation of the lithium transition metal oxide that may occur during a charge and discharge process, and thereby suppressing an increase in resistance and improving high-temperature life characteristics. The amount of cobalt (Co) included in the first coating layer may be greater than the amount of cobalt (Co) included in the second coating layer. In this case, the positive electrode interfacial resistance when the SOC of the coin half-cell including the positive electrode according to the present invention is 50% can be lowered, so that the problem of an increase in initial resistance during charge and discharge due to a decrease in ion mobility when a positive electrode active material which is a single particle is used can be prevented or suppressed, so that the life characteristics and high-temperature life characteristics of the battery can be improved, and the energy density can be improved. The second coating layer may contain cobalt (Co) in an amount of 0.2 mol% to 2.5 mol%, 0.3 mol% to 2 mol%, 0.5 mol% to 1.5 mol%, or 0.7 mol% to 1.3 mol%. When the second coating layer contains cobalt in the above range, the second coating layer contains a smaller amount of cobalt than the first coating layer included in the first positive electrode active material described above, thereby lowering the positive electrode interfacial resistance when the SOC of the coin half-cell including the positive electrode according to the present invention is 50%, thereby preventing or suppressing the problem of initial resistance increasing due to decreased ion mobility during charge and discharge when a positive electrode active material that is a single particle is used, thereby improving the life characteristics and high-temperature life characteristics of the battery and improving the energy density. The second coating layer may be formed on the entire surface of the second lithium transition metal oxide particle, or may be formed partially. Specifically, when the second coating layer is formed partially on the surface of the second lithium transition metal oxide particle, it may be formed in an area of ​​5% or more and less than 100%, or 20% or more and less than 100% of the entire surface area of ​​the surface of the second lithium transition metal oxide. The average particle diameter (D) of the second positive electrode active material 50) may be 1.5 ㎛ to 5 ㎛. Specifically, the average particle diameter of the second positive electrode active material may be 1.5 ㎛ or more, 1.7 ㎛ or more, 1.9 ㎛ or more, 2 ㎛ or more, 2.2 ㎛ or more, 2.4 ㎛ or more, 2.6 ㎛ or more, 2.8 ㎛ or more, 3 ㎛ or more, and may be 5 ㎛ or less, 4.8 ㎛ or less, 4.6 ㎛ or less, 4.4 ㎛ or less, 4.2 ㎛ or less, 4 ㎛ or less, 3.8 ㎛ or less, 3.6 ㎛ or less, 3.4 ㎛ or less, 3.2 ㎛ or less. For example, the average particle diameter of the second positive electrode active material may be 1.5 ㎛ to 5 ㎛, 2 ㎛ to 4.5 ㎛, 2.6 ㎛ to 4.2 ㎛, 3 ㎛ to 4 ㎛, or 3 ㎛ to 3.4 ㎛. When the above range is satisfied, the rolling density of the cathode material can be increased, and thus the electrode density can be improved during electrode manufacturing, thereby realizing excellent energy density. The above second positive electrode active material may be included in an amount of 20 wt% to 80 wt%, 30 wt% to 70 wt%, or 40 wt% to 60 wt% based on the total weight of the positive electrode active material layer. When the above range is satisfied, the rolling density can be improved to realize high energy density. The above first positive electrode active material and the above second positive electrode active material may be included in a weight ratio of 80:20 to 40:60, 75:25 to 45:55, 70:30 to 50:50, or 65:45 to 55:45. When the above weight ratio is satisfied, the effect of improving the high temperature life characteristics and resistance characteristics while improving the energy density can be maximized. Meanwhile, when a silicon-based active material is included as the negative electrode active material, the silicon-based active material acts in the discharge terminal voltage range, and at this time, when the discharge terminal resistance of the positive electrode is low, a problem occurs in which lithium is deposited on the surface of the negative electrode due to the difference in resistance between the positive electrode and the negative electrode. Therefore, in order to reduce the discharge terminal resistance difference between the positive electrode and the negative electrode, it is necessary to increase the discharge terminal resistance of the positive electrode. However, there is a problem in that if the interfacial resistance of the positive electrode increases in the entire range, the cell resistance increases. Therefore, the positive electrode according to the present invention solves the above problem by maintaining the interface resistance of the positive electrode having an SOC of 50% in a coin half cell manufactured using the positive electrode and increasing the interface resistance of the positive electrode having an SOC of 10% measured in a coin half cell manufactured using the positive electrode. In a coin half cell manufactured using the positive electrode, the interface resistance of the positive electrode having an SOC of 50% is 6.5Ω to 8.5Ω. Specifically, the positive electrode may have an interface resistance of 6.5Ω or more, 6.7Ω or more, 6.9Ω or more, 7.0Ω or more, or 7.2Ω or more, and may have 8.5Ω or less, 8.3Ω or less, 8.1Ω or less, 8.0Ω or less, 7.8Ω or less, 7.6Ω or less, or 7.4Ω or less in the coin half cell. For example, the positive electrode may have an interface resistance of 6.5Ω to 8.5Ω, 6.7Ω to 8.0Ω, or 6.9Ω to 7.4Ω in the coin half cell. When the above range is satisfied, the interfacial resistance of the positive electrode at SOC 50% is maintained without increasing, so that the overall resistance of the battery does not increase, preventing the problem of an increase in the initial resistance during charge and discharge, and thus improving the life characteristics of the battery. In addition, the interface resistance of the positive electrode having SOC 10% measured in a coin half-cell manufactured using the positive electrode is 15Ω to 19Ω. Specifically, the positive electrode may have an interface resistance of SOC 10% in the coin half-cell of 15Ω or more, 15.2Ω or more, 15.4Ω or more, 15.6Ω or more, 15.8Ω or more, 16Ω or more, 16.2Ω or more, 16.4Ω or more, 16.6Ω or more, 16.8Ω or more, 17Ω or more, 17.2Ω or more, 17.4Ω or more, and may be 19Ω or less, 18.8Ω or less, 18.6Ω or less, 18.4Ω or less, 18.2Ω or less, 18Ω or less, 17.8Ω or less, 17.6Ω or less. For example, the positive electrode may have an interface resistance of 15Ω to 19Ω, 15.2Ω to 18Ω, 16Ω to 17.8Ω, or 17Ω to 17.6Ω in a coin half cell at 10% SOC. When the above range is satisfied, the difference in resistance between the positive electrode and the negative electrode at the end of discharge can be reduced, so that the phenomenon of lithium ions being deposited on the surface of the negative electrode can be suppressed, thereby suppressing degradation of the negative electrode, thereby solving the problem of deterioration of the cycle characteristics of the battery, and preventing the problem of initial resistance increasing during charge and discharge, thereby improving the life characteristics of the battery. At this time, the interface resistance of the positive electrode having an SOC of 50% or 10% in the coin half-cell can be controlled through the composition of the first positive electrode active material and the second positive electrode active material, the cobalt content of the first coating layer included in the first positive electrode active material and the second coating layer included in the second positive electrode active material, the washing conditions during the production of the first positive electrode active material and the second positive electrode active material, etc. The anode according to the present invention has an IRR value of 96 to 166, as defined by the following equation 1. Specifically, the IRR value defined by the following Equation 1 may be 96 or more, 98 or more, 100 or more, 102 or more, 104 or more, 106 or more, 108 or more, 110 or more, 112 or more, 116 or more, 118 or more, 120 or more, 122 or more, 124 or more, 126 or more, 166 or less, 164 or less, 162 or less, 160 or less, 158 or less, 156 or less, 154 or less, 152 or less, 150 or less, 148 or less, 146 or less, 144 or less, 142 or less, 140 or less, 138 or less, 136 or less, 134 or less, 132 or less, 130 or less, or 128 or less. For example, the IRR value defined by the following Equation 1 may be 96 to 166, 100 to 140, 104 to 130, 120 to 130, or 124 to 128. When the above range of IRR values ​​is satisfied, the interfacial resistance of the positive electrode can be controlled in a range such that the difference in discharge terminal resistance between the positive electrode and the negative electrode is reduced while preventing the resistance of the positive electrode from increasing in the entire region, so that the high-temperature life characteristics of the lithium secondary battery can be excellent. [Formula 1] IRR = R CT50 ×R CT10 In the above formula 1, the R CT50 is the dimensionless number of the interface resistance (unit: Ω) of the positive electrode at 50% SOC measured in a coin half cell manufactured using the above positive electrode, and R CT10 is a dimensionless number of the interfacial resistance (unit: Ω) of the positive electrode at SOC 10% measured in a coin half-cell manufactured using the above positive electrode. Above R CT50 The interfacial resistance of the positive electrode having an SOC of 50% measured in a coin half-cell manufactured using the positive electrode may be the same as described above. Above R CT10The interfacial resistance of the positive electrode having an SOC of 10% measured in a coin half-cell manufactured using the positive electrode may be the same as described above. Meanwhile, the positive electrode active material layer may optionally further include at least one of a positive electrode conductive material and a positive electrode binder. The above-described positive electrode 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 special restrictions. 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, summer black, carbon fiber, and carbon nanotube; metal powder or metal fiber 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, and the like, and one of these may be used alone or a mixture of two or more may be used. The above-described positive electrode conductive material may typically be included in an amount of 1 to 30 wt%, 1 to 20 wt%, or 1 to 10 wt% based on the total weight of the positive electrode active material layer. The above positive electrode binder serves to improve the adhesion between positive electrode particles and the adhesive strength between the positive electrode and the positive electrode current collector, and specific examples thereof include a fluorine resin binder including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxyl methyl cellulose (CMC), starch, hydroxy propyl cellulose, and regenerated cellulose; a polyalcohol binder including polyvinyl alcohol; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; and a polyester binder. And silane binders, etc. can be mentioned, and one of these can be used alone or a mixture of two or more can be used. The positive electrode binder can be included in an amount of 1 to 30 wt%, 1 to 20 wt%, or 1 to 10 wt% with respect to the total weight of the positive electrode active material layer. The above positive electrode can be manufactured by a method of applying positive electrode slurry to one side 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. Meanwhile, a positive electrode including a non-coated portion can be manufactured by a method of not applying the positive electrode slurry to some area of ​​the positive electrode collector, for example, one end of the positive electrode collector, during the application of the positive electrode slurry. In addition, the positive electrode slurry can be prepared by dispersing the first positive electrode active material and the second positive electrode active material according to the present invention in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. Lithium secondary battery Next, a lithium secondary battery according to the present invention will be described. A lithium secondary battery according to the present invention comprises an electrode assembly including the positive and negative electrodes described above; an electrolyte; and a battery case in which the electrode assembly and the electrolyte are accommodated, wherein the negative electrode includes a silicon-based negative electrode active material. Below, each component of the lithium secondary battery according to the present invention will be described in more detail. (1) Electrode assembly An electrode assembly according to the present invention includes an anode and a cathode, and specifically, the electrode assembly may include an anode, a cathode, and a separator. Specifically, the electrode assembly can be formed by sequentially stacking an anode, a separator, and a cathode, and the anode and cathode can be mutually insulated by the separator. The types of electrode assemblies may include, but are not limited to, stacked, jellyroll, and stack-and-folded. Hereinafter, each component of the electrode assembly according to the present invention will be described in detail. 1) Bipolar Since the above anode is the same as described above, a detailed description is omitted. 2) Cathode The above negative electrode includes a silicon-based negative electrode active material. Specifically, the negative electrode may include a negative electrode current collector; and a negative electrode active material layer; and the negative electrode active material layer may include a silicon-based negative electrode active material. The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, 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 above negative electrode current collector can typically have a thickness of 3 to 500 ㎛. In addition, the negative current collector, like the positive current collector, can form fine irregularities on the surface of the negative current collector to strengthen the bonding strength of the negative active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, and non-woven fabric. The negative electrode active material layer may be positioned on the negative electrode current collector, and specifically, may be positioned on one side or both sides of the negative electrode current collector. The negative electrode active material layer may have a single layer or a multilayer structure of two or more layers. The above silicon-based negative electrode active material may be a particle containing silicon (Si). The above silicon-based negative electrode active material is SiO x (0≤x≤2), Si / C composite or a combination thereof. The SiO x (0≤x≤2) may be a form containing Si and SiO2. That is, the x is the SiO x (0≤x≤2) corresponds to the number ratio of O to Si included in the silicon-based negative electrode active material. The silicon-based negative electrode active material is SiO x (0≤x≤2), most preferably SiO. When a silicon-based negative electrode active material is included in the negative electrode, it has the advantage of having a very high charge / discharge capacity compared to a conventional carbon-based negative electrode active material. However, the silicon-based negative electrode active material has a problem in that the irreversible capacity is large, which reduces the life characteristics of the battery. However, as described above, the lithium secondary battery according to the present invention solves the above problem by including a single-particle positive electrode active material in the positive electrode and controlling the interfacial resistance of the positive electrode to a specific range. The above silicon-based negative electrode active material may be included in the negative electrode active material layer at 1 wt% to 30 wt%, 1 wt% to 25 wt%, or 2 wt% to 20 wt%. When the above range is satisfied, sufficient capacity characteristics can be implemented. Meanwhile, the negative electrode active material layer may further include a carbon-based negative electrode active material as the negative electrode active material. The above carbon-based negative electrode active material may be at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; and carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, and carbon nanotube. When the carbon-based negative electrode active material is included, the deterioration of the life characteristics due to the volume change of the silicon-based negative electrode active material during charge and discharge can be suppressed. When a carbon-based negative electrode active material is further included, the silicon-based negative electrode active material and the carbon-based negative electrode active material may be included in a weight ratio of 1:99 to 30:70, 1.5:98.5 to 20:80, 2:98 to 15:85, or 2.5:97.5 to 10:90. When the above range is satisfied, the capacity characteristics may be excellent and the life characteristics may be excellent. The above carbon-based negative electrode active material may be included in the negative electrode active material layer at 70 wt% to 99 wt%, 75 wt% to 99 wt%, or 80 wt% to 98 wt%. When the above range is satisfied, the life characteristics of the battery can be improved while implementing sufficient capacity characteristics. Meanwhile, the negative electrode active material layer may optionally further include a negative electrode conductive material and a negative electrode binder in addition to the negative electrode active material. The above negative electrode 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 special restrictions. 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, summer black, carbon fiber, and carbon nanotube; metal powder or metal fiber 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, and the like, and one of these may be used alone or a mixture of two or more may be used. The negative electrode conductive material may typically be included in an amount of 1 to 30 wt%, 1 to 20 wt%, or 1 to 10 wt% based on the total weight of the negative electrode active material layer. The above negative electrode binder serves to improve the adhesion between negative electrode active material particles and the adhesive strength between the negative electrode active material and the negative electrode current collector. Specific 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 may be used alone or a mixture of two or more thereof may be used. The above negative electrode binder may be included in an amount of 1 to 30 wt%, 1 to 20 wt%, or 1 to 10 wt% based on the total weight of the negative electrode active material layer. 3) Membrane Next, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. If it is a separator commonly used in lithium secondary batteries, it can be used without special restrictions. At this time, the separator can be interposed between the positive electrode and the negative electrode. Specifically, as the separator, 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 can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material can be used to secure heat resistance or mechanical strength. (2) Electrolyte The electrolyte according to the present invention comprises a lithium salt and an organic solvent. The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1 to 5.0 M, or 0.1 to 3.0 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. The above organic solvent may include at least one of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent. The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent, and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, and specifically, ethyl methyl carbonate (EMC) may be included. Specific examples of the linear ester organic solvent include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. The above cyclic ester organic solvent may include at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. Preferably, the electrolyte according to the present invention may include ethylene carbonate and dimethyl carbonate as organic solvents. Meanwhile, in addition to the electrolyte components, the electrolyte may additionally contain other additives for the purposes of improving the life characteristics of the battery, suppressing battery capacity reduction, and improving the discharge capacity of the battery. These other additives may include at least one other additive selected from the group consisting of, for example, cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds different from the lithium salt included in the electrolyte. Specifically, the other additives include vinylene carbonate (VC), vinylethylene carbonate, fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, 1-methyl-1,3-propene sultone, ethylene sulfate (ESA), trimethylene sulfate (TMS), methyl trimethylene sulfate (MTMS), tetraphenylborate, lithium oxalyldifluoroborate, succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, The present invention relates to a compound selected from the group consisting of 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, fluorobenzene, triethanolamine, ethylenediamine, tetravinylsilane, LiN(SO2F)2(lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF3)2(lithium bis(trifluoromethane sulfonyl)imide, LiTFSI), LiPO2F2, LiODFB, LiBOB (lithium bisoxalatoborate (LiB(C2O4)2) and LiBF4. The above other additives may be included in an amount of 0.01 to 20 wt%, or 0.05 to 5.0 wt%, based on the total weight of the electrolyte. When the above range is satisfied, high-temperature life characteristics and low-temperature output characteristics can be improved, and side reactions within the electrolyte can be prevented. (3) Battery case The above battery case is for accommodating the electrode assembly and the electrolyte, and various battery cases known in the art, such as a cylindrical battery case, a square battery case, a pouch-type battery case, etc., can be used. The lithium secondary battery according to the present invention is useful in portable devices such as mobile phones, laptop computers, and digital cameras, and in electric vehicles such as hybrid electric vehicles (HEVs). In addition, a battery module or battery pack including the lithium secondary battery as a unit cell can be used as a power source for one or more medium- to large-sized devices among a power tool; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system. The lithium secondary battery 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 preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells. Examples of the above medium and large-sized devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. Method for manufacturing anode Next, a method for manufacturing an anode according to the present invention will be described with reference to FIG. 1. The method for manufacturing a positive electrode according to the present invention comprises a step (S1) of mixing a first positive electrode active material in distilled water, performing a first washing, and drying; a step (S2) of mixing a second positive electrode active material in distilled water, performing a second washing, and drying; and a step (S3) of forming a positive electrode active material layer including the first positive electrode active material and the second positive electrode active material; wherein the first washing is performed at a higher temperature than the second washing, and the average particle diameter (D) of the first positive electrode active material is 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than the first positive electrode active material and the second positive electrode active material, and the first positive electrode active material and the second positive electrode active material include single-particle particles, and the interface resistance of the positive electrode having an SOC of 50% measured in a coin half cell manufactured using the positive electrode is 6.5Ω to 8.5Ω, and the interface resistance of the positive electrode having an SOC of 10% measured in a coin half cell manufactured using the positive electrode is 15Ω to 19Ω. Hereinafter, each step of the method for manufacturing an anode according to the present invention will be described in detail with reference to FIG. 1. (1) S1 stage: First cathode active material washing stage First, a step (S1 step) of mixing the first positive electrode active material in distilled water, washing it for the first time, and drying it is performed. The above first positive electrode active material includes single-particle particles. Since the first positive electrode active material is the same as described above, a detailed description is omitted. The above step S1 serves to control the interface resistance of the positive electrode within a specific range by performing the washing intensity of the first positive electrode active material higher than the washing intensity of the second positive electrode active material in the step S2 described below. Specifically, the first washing is performed at a higher temperature than the second washing. The above first washing is performed at 20° C. to 40° C., 25° C. to 35° C., or 27° C. to 38° C. When the first washing is performed at the above temperature, the interface resistance of the anode can be controlled within the desired range. In addition, the first washing may be performed by mixing the first cathode active material in an amount of 50 wt% to 70 wt%, 55 wt% to 65 wt%, or 57 wt% to 63 wt% based on the total weight of distilled water. In this case, the amount of residual lithium on the surface of the cathode active material may be reduced, thereby preventing deterioration of high-temperature durability. The drying can be performed at 60°C to 200°C, 70°C to 180°C, or 80°C to 160°C. (2) S2 stage: Second cathode active material washing stage Next, a step (S2 step) of mixing the second positive electrode active material in distilled water, performing a second washing, and drying is performed. The second positive electrode active material includes single-particle particles. When the second positive electrode active material is a single-particle particle, since the single-particle particle size is large, the diffusion distance of lithium is long, so that the diffusion resistance increases, so that the positive electrode may have low efficiency. Therefore, when applying a silicon-based negative electrode active material, the efficiency can be balanced with the negative electrode. Accordingly, the problem of lithium ion loss due to irreversible capacity when applying a conventional silicon-based negative electrode active material can be solved, and the lithium precipitation phenomenon on the surface of the negative electrode can be prevented or suppressed, so that the life characteristics of a lithium secondary battery applying the positive electrode according to the present invention can be improved. In addition, when applying a second positive electrode active material which is a single-particle particle, unlike when using a conventional sacrificial positive electrode material, the generation of lithium byproducts due to the sacrificial positive electrode material during charge and discharge can be prevented or suppressed, so that high-temperature storage characteristics and high-temperature life characteristics can be excellent. The average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than that. Since the above second positive electrode active material is the same as described above, a detailed description is omitted. The above S2 step is performed by lowering the washing intensity of the second positive electrode active material having a smaller particle size and larger specific surface area than the first positive electrode active material, thereby preventing deterioration of the high-temperature durability of the second positive electrode active material and controlling the interface resistance of the positive electrode within a specific range. The above second washing can be performed at 3° C. to 18° C., 5° C. to 15° C., or 7° C. to 13° C. When the second washing is performed within the above range, the interface resistance of the positive electrode can be controlled within the desired range while preventing deterioration of high-temperature durability. In addition, the second washing may be performed by mixing the second cathode active material in an amount of 65 wt% to 85 wt%, 70 wt% to 80 wt%, or 72 wt% to 78 wt% based on the total weight of distilled water. In this case, residual lithium on the surface of the cathode active material may be reduced, thereby preventing deterioration of high-temperature durability. The drying can be performed at 60°C to 200°C, 70°C to 180°C, or 80°C to 160°C. (3) S3 stage: Positive electrode active material layer formation stage Next, a step (step S3) of forming a positive electrode active material layer including the first positive electrode active material and the second positive electrode active material is performed. First, a cathode slurry can be prepared by mixing the first cathode active material, the second cathode active material, and the solvent. At this time, since the first positive electrode active material and the second positive electrode active material are the same as described above, a detailed description is omitted. The above cathode slurry may optionally further include a cathode binder and / or a cathode conductive material. Since the above positive electrode binder and positive electrode conductive material are the same as described above, a detailed description is omitted. Meanwhile, the solvent used in the positive electrode slurry may be an aqueous solvent, an organic solvent, or a combination thereof. The aqueous solvent may include, for example, water, and the polar aprotic organic solvent may include at least one selected from the group consisting of N-methyl pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dihydrolevoglucosenone (Cyrene), γ-valerolactone, dimethyl isosorbide (DMI), and methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate, and preferably, N-methyl pyrrolidone. Next, the positive electrode slurry may be applied to a positive electrode current collector and dried to form a positive electrode active material layer. Specifically, the positive electrode may be manufactured by applying the positive electrode slurry to one or both sides of the positive electrode current collector, and then drying and rolling to form a positive electrode active material layer. Since the above-mentioned positive electrode collector is the same as described above, a detailed description is omitted. Meanwhile, the above coating can be performed continuously or discontinuously using various coating methods well known in the art, such as slot die coating, slide coating, curtain coating, etc. The drying can be performed at a temperature of 40°C to 180°C, 60°C to 160°C, or 70°C to 150°C. The above rolling can be performed by a roll press method that adjusts the thickness of the anode by adjusting the upper / lower gap of the roll, but is not limited thereto. Meanwhile, in a coin half-cell manufactured using the positive electrode, the interface resistance of the positive electrode having SOC 50% is 6.5Ω to 8.5Ω. Specifically, the positive electrode may have an interface resistance of 6.5Ω or more, 6.7Ω or more, 6.9Ω or more, 7.0Ω or more, or 7.2Ω or more, and may have an interface resistance of 8.5Ω or less, 8.3Ω or less, 8.1Ω or less, 8.0Ω or less, 7.8Ω or less, 7.6Ω or less, or 7.4Ω or less in the coin half-cell. For example, the positive electrode may have an interface resistance of 6.5Ω to 8.5Ω, 6.7Ω to 8.0Ω, or 6.9Ω to 7.4Ω in the coin half-cell. When the above range is satisfied, the interfacial resistance of the positive electrode at SOC 50% is maintained without increasing, so that the overall resistance of the battery does not increase, preventing the problem of an increase in the initial resistance during charge and discharge, and thus improving the life characteristics of the battery. In addition, the interface resistance of the positive electrode having SOC 10% measured in a coin half-cell manufactured using the positive electrode is 15Ω to 19Ω. Specifically, the positive electrode may have an interface resistance of SOC 10% in the coin half-cell of 15Ω or more, 15.2Ω or more, 15.4Ω or more, 15.6Ω or more, 15.8Ω or more, 16Ω or more, 16.2Ω or more, 16.4Ω or more, 16.6Ω or more, 16.8Ω or more, 17Ω or more, 17.2Ω or more, 17.4Ω or more, and may be 19Ω or less, 18.8Ω or less, 18.6Ω or less, 18.4Ω or less, 18.2Ω or less, 18Ω or less, 17.8Ω or less, 17.6Ω or less. For example, the positive electrode may have an interface resistance of 15Ω to 19Ω, 15.2Ω to 18Ω, 16Ω to 17.8Ω, or 17Ω to 17.6Ω in a coin half cell at 10% SOC. When the above range is satisfied, the difference in resistance between the positive electrode and the negative electrode at the end of discharge can be reduced, so that the phenomenon of lithium ions being deposited on the surface of the negative electrode can be suppressed, thereby suppressing degradation of the negative electrode, thereby solving the problem of deterioration of the cycle characteristics of the battery, and preventing the problem of initial resistance increasing during charge and discharge, thereby improving the life characteristics of the battery. Since the manufactured anode is the same as described above, a detailed description is omitted. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. Example 1 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 8.6㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 30°C so that the solid content was 60 wt%, washed, dried, and then Co(OH)2 was mixed. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a first positive electrode active material coated with Co. The first positive electrode active material contained 3 mol% of Co and had an average particle diameter (D 50 ) was confirmed to be 8.6㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 3.1㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 75 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 3.1㎛ and a single particle. <Polar manufacturing> The first positive electrode active material and the second positive electrode active material manufactured above were mixed in a weight ratio of 60:40 to manufacture a positive electrode material, and the positive electrode material, carbon black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were mixed in a weight ratio of 96:2:2 in an N-methylpyrrolidone solvent to manufacture a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector having a thickness of 20 μm, dried at 130°C, and then rolled to manufacture a positive electrode having a thickness of 70 μm. Example 2 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 8.4㎛, and Ni 0.83 Co 0.07 Mn 0.1A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 25°C so that the solid content became 60 wt%, washed, dried, and then Co(OH)2 was mixed. Thereafter, a first positive electrode active material coated with Co was manufactured by heat-treating at 750°C for 5 hours. The first positive electrode active material contained 3 mol% of Co and had an average particle size (D 50 ) was confirmed to be 8.4㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 3.3㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 15°C so that the solid content became 75 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 3.3㎛ and a single particle. <Polar manufacturing> A positive electrode was manufactured in the same manner as in Example 1, except that the first positive electrode active material and the second positive electrode active material manufactured above were used. Example 3 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 8.1㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 30°C so that the solid content became 60 wt%, washed, dried, and then Co(OH)2 was mixed. Thereafter, heat treatment was performed at 750°C for 5 hours to manufacture a first positive electrode active material coated with Co. The first positive electrode active material contained 2.5 mol% of Co and had an average particle size (D 50 ) was confirmed to be 8.1㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with the co-precipitation reaction, and the average particle size (D) is 50 ) is 3.5㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 75 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1.5 mol% of Co and had an average particle size (D 50 ) was confirmed to be 3.5㎛ and a single particle. <Polar manufacturing> A positive electrode was manufactured in the same manner as in Example 1, except that the first positive electrode active material and the second positive electrode active material manufactured above were used. Comparative Example 1 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with the co-precipitation reaction, and the average particle size (D) is 50 ) is 7.2㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 75 wt%, washed, dried, and then Co(OH)2 was mixed. Thereafter, a first positive electrode active material coated with Co was manufactured by heat-treating at 750°C for 5 hours. The first positive electrode active material contained 3 mol% of Co and had an average particle size (D 50 ) was confirmed to be 7.2㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with the co-precipitation reaction, and the average particle size (D) is 50 ) is 2.5㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 75 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 2.5㎛ and a single particle. <Polar manufacturing> A positive electrode was manufactured in the same manner as in Example 1, except that the first positive electrode active material and the second positive electrode active material manufactured above were used. Comparative Example 2 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with the co-precipitation reaction, and the average particle size (D) is 50) is 7.7㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 30°C so that the solid content became 60 wt%, washed, dried, and then Co(OH)2 was mixed. Thereafter, heat treatment was performed at 750°C for 5 hours to manufacture a first positive electrode active material coated with Co. The first positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 7.7㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 2.9㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 70 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 2.9㎛ and a single particle. <Polar manufacturing> A positive electrode was manufactured in the same manner as in Example 1, except that the first positive electrode active material and the second positive electrode active material manufactured above were used. Comparative Example 3 <Manufacture of the first cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 8.5㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A first lithium transition metal oxide represented by O2 was prepared. Then, the first lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 75 wt%, washed, dried, and then Co(OH)2 was mixed. Thereafter, a first positive electrode active material coated with Co was manufactured by heat-treating at 750°C for 5 hours. The first positive electrode active material contained 3 mol% of Co and had an average particle size (D 50 ) was confirmed to be 8.5㎛ and a single particle. <Manufacturing of the second cathode active material> A transition metal aqueous solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 83:7:10. Next, deionized water is added to the reactor, nitrogen gas is purged into the reactor to remove dissolved oxygen in the water, and the inside of the reactor is made into a non-oxidizing atmosphere. Then, NaOH is added to proceed with a co-precipitation reaction, and the average particle size (D) is 50 ) is 3.0㎛, and Ni 0.83 Co 0.07 Mn 0.1 A precursor represented by (OH)2 was prepared. The above precursor and LiOH were mixed in a ratio of 1:1.05, and Al was mixed as a doping element and calcined at 910°C for 16 hours to obtain Li[Ni 0.81 Co 0.07 Mn 0.10 Al 0.02 ]A second lithium transition metal oxide represented by O2 was prepared. Then, the second lithium transition metal oxide was mixed in distilled water at 10°C so that the solid content became 70 wt%, washed, dried, and then mixed with Co(OH)2. After that, a heat treatment was performed at 750°C for 5 hours to manufacture a second positive electrode active material coated with Co. The second positive electrode active material contained 1 mol% of Co and had an average particle size (D 50 ) was confirmed to be 3.0㎛ and a single particle. <Polar manufacturing> A positive electrode was manufactured in the same manner as in Example 1, except that the first positive electrode active material and the second positive electrode active material manufactured above were used. Experimental Example 1 - Measurement of bipolar interface resistance and evaluation of IRR value An electrode assembly was manufactured by interposing a porous polyethylene separator between each of the positive electrodes and the lithium metal negative electrodes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3, and then positioning this inside a battery case, and then injecting an electrolyte into the case to manufacture a coin half cell. At this time, the electrolyte used was 1.0 M LiPF6 dissolved in a mixed organic solvent of ethylene carbonate (EC):ethyl methyl carbonate (EMC) in a volume ratio of 3:7. Next, for each coin half-cell manufactured above, the battery was charged under the conditions of CC / CV, 0.1C, 4.2V, 0.05C cut at 25℃, and discharged to CC, 0.1C, 3.0V for 2 cycles (one cycle), and then charged to SOC 50% and SOC 10% at 0.1C. Then, the positive electrode interface resistance at SOC 50% and SOC 10% of each coin half-cell was measured using a Biologic VMP3 device (100kHz to 10mHz range, 25℃ condition). The measurement results are shown in Table 1 below. In addition, the IRR value defined by Equation 1 below was calculated using the positive electrode interface resistance at SOC 50% and SOC 10% of the coin half-cells manufactured using the positive electrodes of Examples 1 to 3 and Comparative Examples 1 to 3 measured above. The calculated IRR values ​​are shown in Table 1 below. [Formula 1] IRR = R CT50 ×R CT10 In the above formula 1, the R CT50is a dimensionless number of the interface resistance (unit: Ω) of the positive electrode at 50% SOC measured in a coin half cell manufactured using the above positive electrode, and R CT10 is a dimensionless number of the interfacial resistance (unit: Ω) of the positive electrode at SOC 10% measured in a coin half-cell manufactured using the above positive electrode. SOC 50% Anode Interface Resistance [Ω] SOC 10% Anode Interface Resistance [Ω] IRR Value Example 17.23 17.44 126.09 12 Example 26.89 15.32 105.55 48 Example 37.46 17.99 134.2054 Comparative Example 16.12 14.56 89.1072 Comparative Example 28.66 19.25 166.705 Comparative Example 36.47 14.78 95.6266 Referring to Table 1 above, it can be seen that the interface resistance of the positive electrode having an SOC of 50% measured in the coin half cell manufactured using the positive electrode of the present invention, as in the cases of Examples 1, 2, and 3, is 6.5Ω to 8.5Ω, and the interface resistance of the positive electrode having an SOC of 10% measured in the coin half cell manufactured using the positive electrode is 15Ω to 19Ω. In addition, it can be seen that the IRR value is in the range of 96 or more and 166 or less. Experimental Example 2 - Initial Resistance Evaluation A negative electrode slurry was prepared by mixing a negative electrode active material of SiO:artificial graphite in a weight ratio of 5:95, a conductive material of carbon black, a binder of SBR, and a thickener of CMC in a weight ratio of 95.6:1.0:2.3:1.1 in distilled water. The negative electrode slurry was applied to one surface of a copper current collector having a thickness of 12 μm, dried at 130°C, and then rolled to prepare a negative electrode. (Slurry solid content: 50 wt% based on the total weight of the negative electrode slurry) An electrode assembly was manufactured by interposing a porous polyethylene separator between each of the positive and negative electrodes manufactured in Examples 1 to 3 and Comparative Example 2, and then positioning the electrode assembly inside a battery case and injecting an electrolyte to manufacture a lithium secondary battery. At this time, an electrolyte solution was used in which 1.0 M LiPF6 was dissolved in an organic solvent mixed with ethylene carbonate (EC):ethyl methyl carbonate (EMC) in a volume ratio of 3:7. For each lithium secondary battery manufactured as described above, it was charged at 25℃ in CC / CV mode at 0.1C until 4.2V, discharged at a constant current of 0.1C, and measured for discharge resistance (HPPC) at SOC 50% and SOC 10%. The results are shown in Table 2. Discharge resistance (HPPC) at 50% SOC [Ω] Discharge resistance (HPPC) at 10% SOC [Ω] Example 11.564.11 Example 21.523.89 Example 31.614.17 Comparative example 21.724.86 Referring to Table 2 above, it can be confirmed that the lithium secondary battery manufactured using the positive electrodes manufactured in Examples 1 to 3 has a lower discharge resistance at SOC 50% and SOC 10% than the lithium secondary battery manufactured using the positive electrode manufactured in Comparative Example 2. Experimental Example 3 - Evaluation of High Temperature Life Characteristics Lithium secondary batteries including the positive electrodes of Examples 1 to 3 and Comparative Examples 1 to 3 manufactured in the above Experimental Example 2 were charged to 4.2 V under CC / CV, 0.5 C conditions, 0.05 C cut conditions at 45° C. using an electrochemical charger / discharger, and then discharged to 3.0 V under CC, 1.0 C conditions, which was considered one cycle, to perform 100 charge / discharge cycles. (1) Capacity maintenance rate The capacity retention rate is calculated using the formula below, and the results are shown in Table 3 below. Capacity retention rate (%) = {(discharge capacity after 100 cycles / discharge capacity after 1 cycle)} Х 100 (2) Resistance increase rate After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger / discharger, the SOC was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after pulse application. After 100 cycles of charge and discharge, the resistance after 100 cycles was calculated using the same method as above, and the resistance increase rate was calculated using the equation below, and the results are shown in Table 3 below. Resistance increase rate (%) = (resistance after 100 cycles - initial resistance) / initial resistance Х 100 Capacity retention rate (%) Resistance increase rate (%) Example 198.911.3 Example 297.416.3 Example 396.918.1 Comparative example 193.243.5 Comparative example 294.539.7 Comparative example 393.947.2 Referring to Table 3 above, it can be confirmed that the lithium secondary batteries manufactured using the positive electrodes manufactured in Examples 1 to 3 have a higher capacity retention rate at 45°C and a lower resistance increase rate than the lithium secondary batteries manufactured using the positive electrodes manufactured in Comparative Examples 1 to 3. Through this, it can be understood that the lithium secondary batteries manufactured using the positive electrodes manufactured in Examples 1 to 3 have excellent high-temperature life characteristics. 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 common knowledge in the art that various modifications and changes can be made to the various embodiments of the present disclosure within a scope that does not depart from the technical scope of the various embodiments of the present disclosure described in the claims to be described below. Therefore, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims

1. A positive electrode including a positive electrode active material layer including a first positive electrode active material and a second positive electrode active material having different average particle diameters, The average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than The above first positive electrode active material and the above second positive electrode active material include single particle-type particles, A positive electrode, wherein the interface resistance of a positive electrode having an SOC of 50%, as measured in a coin half cell manufactured using the positive electrode, is 6.5Ω to 8.5Ω, and the interface resistance of a positive electrode having an SOC of 10%, as measured in a coin half cell manufactured using the positive electrode, is 15Ω to 19Ω.

2. In paragraph 1, A positive electrode, wherein the first positive electrode active material comprises a first lithium transition metal oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 Ni x1 Co y1 Mr z1 Al w1 M 1 v1 O2 In the above chemical formula 1, 0≤a1≤0.3, 0.82≤x1<1.0, 0 <y1≤0.2, 0<z1≤0.2, 0<w1≤0.2, 0≤v1≤0.1이고, M 1 is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo.

3. In paragraph 1, A cathode, wherein the second cathode active material comprises a second lithium transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2 Ni x2 Co y2 Mr z2 Al w2 M 2 v2 O2 In the above chemical formula 2, 0≤a2≤0.3, 0.82≤x2<1.0, 0 <y2≤0.2, 0<z2≤0.2, 0<w2≤0.2, 0≤v2≤0.1이고, M 2 is a doping element selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo.

4. In paragraph 1, The average particle diameter (D) of the first positive electrode active material 50 ) is a positive electrode with a diameter of 6 μm to 12 μm.

5. In paragraph 1, The average particle diameter (D) of the second positive electrode active material 50 ) is a positive electrode having a diameter of 1.5 μm to 5 μm.

6. In paragraph 1, A cathode, wherein the first cathode active material comprises a first lithium transition metal oxide and a first coating layer positioned on the surface of the first lithium transition metal oxide particles and containing 1.5 mol% to 5 mol% of cobalt (Co).

7. In paragraph 1, A cathode, wherein the second cathode active material comprises a second lithium transition metal oxide and a second coating layer positioned on the surface of the second lithium transition metal oxide particles and containing 0.2 mol% to 2.5 mol% of cobalt (Co).

8. In paragraph 1, A positive electrode, wherein the first positive electrode active material and the second positive electrode active material are included in a weight ratio of 80:20 to 40:

60.

9. A positive electrode including a positive electrode active material layer including a first positive electrode active material and a second positive electrode active material having different average particle diameters, The average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is larger than The above first positive electrode active material and the above second positive electrode active material include single particle-type particles, A cathode having an IRR value of 96 to 166, as defined by the following equation 1. [Formula 1] IRR = R CT50 ×R CT10 In the above equation 1, Above R CT50 is a dimensionless number of the interface resistance (unit: Ω) of the positive electrode at 50% SOC measured in a coin half-cell manufactured using the above positive electrode, Above R CT10 is a dimensionless number of the interfacial resistance (unit: Ω) of the positive electrode at SOC 10% measured in a coin half-cell manufactured using the above positive electrode.

10. An electrode assembly comprising a positive electrode and a negative electrode according to any one of claims 1 to 9; an electrolyte; and a battery case in which the electrode assembly and the electrolyte are stored, A lithium secondary battery, wherein the negative electrode comprises a silicon-based negative electrode active material.

11. In paragraph 10, The above negative electrode comprises a carbon-based negative electrode active material, A lithium secondary battery, wherein the silicon-based negative electrode active material and the carbon-based negative electrode active material are included in a weight ratio of 1:99 to 30:

70.

12. Step (S1) of mixing the first positive electrode active material in distilled water, washing it with water, and drying it; Step (S2) of mixing the second cathode active material in distilled water, washing it a second time, and drying it; and A step (S3) of forming a positive electrode active material layer including the first positive electrode active material and the second positive electrode active material; The above first washing is performed at a higher temperature than the above second washing, The average particle diameter (D) of the first positive electrode active material 50 ) is the average particle diameter (D) of the second positive electrode active material. 50 ) is greater than The above first positive electrode active material and the above second positive electrode active material contain single particle-type particles, A method for manufacturing a positive electrode, wherein the interface resistance of a positive electrode having an SOC of 50%, measured in a coin half cell manufactured using the positive electrode, is 6.5Ω to 8.5Ω, and the interface resistance of a positive electrode having an SOC of 10%, measured in a coin half cell manufactured using the positive electrode, is 15Ω to 19Ω.

13. In paragraph 12, A method for manufacturing an anode, wherein the first washing is performed at a temperature of 20°C to 40°C.

14. In paragraph 12, A method for manufacturing an anode, wherein the second washing is performed at 3°C ​​to 18°C.

15. In paragraph 12, A method for manufacturing a positive electrode, wherein the first washing is performed by mixing the first positive electrode active material in an amount of 50 to 70 wt% based on the total weight of distilled water.

16. In paragraph 12, A method for manufacturing a positive electrode, wherein the second washing is performed by mixing the second positive electrode active material in an amount of 65 to 85 wt% based on the total weight of distilled water.

17. In paragraph 12, A method for manufacturing a positive electrode, wherein the first positive electrode active material comprises a first lithium transition metal oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 Ni x1 Co y1 Mr z1 Al w1 M 1 v1 O2 In the above chemical formula 1, 0≤a1≤0.3, 0.82≤x1<1.0, 0 <y1<0.18, 0<z1<0.18, 0<w1<0.2, 0≤v1≤0.1이고, M 1 is a doping element selected from the group consisting of W, Mo, Cr, Zr, Ti, Mg, Ta, and Nb.

18. In paragraph 12, A method for manufacturing a positive electrode, wherein the second positive electrode active material comprises a second lithium transition metal oxide represented by the following chemical formula 2. [Chemical formula 2] Li 1+a2 Ni x2 Co y2 Mr z2 Al w2 M 2 v2 O2 In the above chemical formula 2, 0≤a2≤0.3, 0.82≤x2<1.0, 0 <y2<0.18, 0<z2<0.18, 0<w2<0.2, 0≤v2≤0.1이고, M 2 is a doping element selected from the group consisting of W, Mo, Cr, Zr, Ti, Mg, Ta, and Nb.

19. In paragraph 12, The first cathode active material comprises a first lithium transition metal oxide, and comprises a first coating layer comprising cobalt (Co) on the surface of the first lithium transition metal oxide particles, The second cathode active material comprises a second lithium transition metal oxide, and comprises a second coating layer comprising cobalt (Co) on the surface of the second lithium transition metal oxide particles, A method for manufacturing an anode, wherein the amount of cobalt (Co) included in the first coating layer is greater than the amount of cobalt (Co) included in the second coating layer.

20. In paragraph 19, A method for manufacturing an anode, wherein the amount of cobalt (Co) in the first coating layer is about 1.5 mol% to 5 mol%, and the amount of cobalt (Co) in the second coating layer is about 0.2 mol% to 2.5 mol%.

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