Lithium secondary battery

Abstract

The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; and an electrolyte, wherein the average resistance X1 of the positive electrode at room temperature and an SOC of 20-100% and the average resistance Y1 of the negative electrode at room temperature and an SOC of 20-100% satisfy expression (1), and the average resistance X2 of the positive electrode at room temperature and an SOC of 0-20% and the average resistance Y2 of the negative electrode at room temperature and an SOC of 0-20% satisfy expression (2). Expression (1): 0.6×Y1≤X1≤0.9×Y1, and expression (2): 2×Y2≤X2.

Description

lithium secondary battery The present invention relates to a lithium secondary battery. [Cross-citation with related applications] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0091706, filed July 14, 2023, the entire contents of which are incorporated herein by reference. [Technical Field] With technological advancements in electric vehicles, portable electronic devices, and other devices, the demand for lithium secondary batteries as an energy source is rapidly increasing. Among these, recent advances in electric vehicle technology have led to a demand for batteries with high energy density and high output. High-energy density lithium secondary batteries, such as those used in electric vehicles and power storage, are often exposed to high-temperature external environments, and the temperature of the battery may rise due to instantaneous charging and discharging. In such high-temperature environments, the lifespan of the battery may be shortened and the amount of stored energy may be reduced. Therefore, there is a need to develop a high-capacity battery system that can improve lifespan characteristics not only at room temperature but also at high temperatures. The lifespan characteristics of lithium secondary batteries are influenced by various factors, but a balanced design of the anode and cathode is crucial. Even when manufacturing secondary batteries using commonly known, high-performance cathode and anode materials, if the thermodynamic or electrochemical balance between the anode and cathode is not achieved, poor lifespan characteristics can occur. The inventors of the present invention seek to prevent rapid deterioration of the room temperature and high temperature life characteristics of a lithium secondary battery including the positive electrode and the negative electrode by achieving thermodynamic or electrochemical balance. [1] The present invention provides a lithium secondary battery comprising a positive electrode; a negative electrode; and an electrolyte, wherein an average resistance X1 of the positive electrode at room temperature and an SOC of 20 to 100% and an average resistance Y1 of the negative electrode at room temperature and an SOC of 20 to 100% satisfy the following equation (1), and an average resistance X2 of the positive electrode at room temperature and an SOC of 0 to 20% and an average resistance Y2 of the negative electrode at room temperature and an SOC of 0 to 20% satisfy the following equation (2). Equation (1): 0.6 × Y1 ≤ X1 ≤ 0.9 × Y1 Equation (2): 2 × Y2 ≤ X2 [2] The present invention can provide a lithium secondary battery in which, in the above [1], the average resistance X3 of the positive electrode at 40°C and SOC 20 to 100% and the average resistance Y3 of the negative electrode at 40°C and SOC 20 to 100% additionally satisfy the following equation (3). Equation (3): 0.75 × Y3 ≤ X3 ≤ Y3 [3] The present invention can provide a lithium secondary battery in which, in the above [1] or [2], the average resistance X4 of the positive electrode at 40°C and SOC 0 to 20% and the average resistance Y4 of the negative electrode at 40°C and SOC 0 to 20% additionally satisfy the following equation (4). Equation (4): 1.5 × Y4 ≤ X4 [4] The present invention can provide a lithium secondary battery in which, in any one of the above [1] to [3], the positive electrode includes a positive electrode active material layer and a positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder, and the positive electrode active material is a lithium nickel-based transition metal oxide having a nickel content of 85 atm% or more among transition metals other than lithium. [5] The present invention can provide a lithium secondary battery in which the positive electrode active material is a single particle or a pseudo-single particle in the above [4]. [6] The present invention can provide a lithium secondary battery in which the conductive material is included in an amount of 0.1 to 2.5 wt% with respect to the entire positive electrode active material layer in the above [4] or [5]. [7] The present invention can provide a lithium secondary battery in which the powder resistance of the positive electrode active material is 100 to 500 Ω in any one of the above [4] to [6]. [8] The present invention can provide a lithium secondary battery in which, in any one of the above [1] to [7], the negative electrode includes a negative electrode active material layer and a negative electrode current collector, the negative electrode active material layer includes a negative electrode active material, a conductive material, and a binder, and the negative electrode active material includes a silicon-based negative electrode active material. [9] The present invention can provide a lithium secondary battery according to the above [8], wherein the silicon-based negative electrode active material is selected from the group consisting of SiO, SiC, and Si.

[0010] The present invention can provide a lithium secondary battery in which, in the above [8] or [9], the silicon-based negative electrode active material is included in an amount of 3 wt% or more relative to the entire negative electrode active material layer.

[0011] The present invention can provide a lithium secondary battery in which a conductive material is included in an amount of 0.05 to 2.50 wt% with respect to the entire negative electrode active material layer in any one of the above [8] to

[0010] . The inventor of the present invention has discovered that when both the positive and negative electrodes deteriorate during operation of a lithium secondary battery, the degree of deterioration of the negative electrode relative to the positive electrode is controlled at a specific temperature and in a specific charging section, the lithium secondary battery can be operated stably. When a lithium secondary battery is operated, both the positive and negative electrodes degrade. By controlling the degree of deterioration of both electrodes depending on the charge / discharge range, lithium secondary batteries can achieve superior long-life characteristics. Specifically, by controlling the positive and negative electrode resistances at room and high temperatures, the use of the negative electrode is suppressed, while the relative deterioration of the positive electrode is inducible, resulting in superior long-life characteristics. Figure 1 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Example 1. Figure 2 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Example 1. Figure 3 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Example 2. Figure 4 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Example 2. Figure 5 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Example 3. Figure 6 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Example 3. Figure 7 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 1. Figure 8 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 1. Figure 9 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 2. Figure 10 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 2. Figure 11 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 3. Figure 12 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 3. Figure 13 shows the results of measuring the resistance values ​​according to SOC at 24°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 4. Figure 14 shows the results of measuring the resistance values ​​according to SOC at 40°C for the positive and negative electrodes of the lithium secondary battery of Comparative Example 4. Hereinafter, the present invention will be described in more detail. Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner. In the present invention, "primary particle" refers to a particle unit that has no apparent grain boundary when observed under a magnification of 5,000 to 20,000 times using a scanning electron microscope. "Average particle diameter of primary particles" refers to the arithmetic mean value calculated after measuring the particle diameters of primary particles observed in a scanning electron microscope image. In the present invention, a "secondary particle" is a particle formed by the aggregation of multiple primary particles. In the present invention, to distinguish it from conventional secondary particles formed by the aggregation of tens to hundreds of primary particles, secondary particles formed by the aggregation of 10 or fewer primary particles are referred to as "quasi-single particles." In the present invention, "average particle diameter D 50"It refers to the particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material powder, and can be measured using the laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume cumulative amount. A lithium secondary battery according to the present invention comprises a positive electrode; a negative electrode; and an electrolyte, wherein an average resistance X1 of the positive electrode at room temperature and an SOC of 20 to 100% and an average resistance Y1 of the negative electrode at room temperature and an SOC of 20 to 100% satisfy the following equation (1), and an average resistance X2 of the positive electrode at room temperature and an SOC of 0 to 20% and an average resistance Y2 of the negative electrode at room temperature and an SOC of 20 to 100% satisfy the following equation (2). Equation (1): 0.6 × Y1 ≤ X1 ≤ 0.9 × Y1 Equation (2): 2 × Y2 ≤ X2 The above room temperature means a constant temperature without heating or cooling, and may be within the range of 15 to 25°C. Lithium secondary batteries charge and discharge as lithium ions move between the positive and negative electrodes. As charging and discharging progress, degradation of the lithium secondary battery occurs due to side reactions with the electrolyte and structural collapse at the positive and negative electrodes. Ideally, the degradation levels of the positive and negative electrodes should be similar. The positive electrode tends to degrade quickly at high voltages, and the negative electrode tends to react more strongly with silicon-based active materials at the lower end of discharge (SOC 0-20%) when the negative electrode contains silicon-based active materials. The lithium secondary battery of the present invention can suppress the degradation of the positive electrode by making the resistance of the positive electrode slightly lower than that of the negative electrode at SOC 20-100% when a high voltage is applied. In addition, the lithium secondary battery of the present invention can suppress the degradation of the negative electrode active material by adjusting the resistance of the positive electrode to be high at SOC 0-20%, which is the lower end of discharge, so that the potential of the negative electrode does not increase during discharge. This can minimize the difference in degradation levels between the positive and negative electrodes, thereby maximizing the lifespan characteristics of lithium secondary batteries. The average resistance of the positive electrode and the average resistance of the negative electrode can be measured using a first coin cell manufactured using a positive electrode and a lithium metal counter electrode, and a second coin cell manufactured using the negative electrode and a lithium metal counter electrode, respectively. Specifically, the first coin cell and the second coin cell can be manufactured by disassembling the positive electrode and the negative electrode from a manufactured lithium secondary battery, connecting a lithium metal having a thickness of 200 μm to the counter electrode, injecting an electrolyte including a LiPF6 lithium salt and an organic solvent (a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate), and aging for 24 hours. In the above equation (1), X1 is the average resistance of the positive electrode at room temperature and SOC 20 to 100%, and is the average resistance value (Ω) of the first coin cell in the SOC 20 to 100% range when discharged at 1C at room temperature. Specifically, X1 is the average resistance value calculated for the SOC 20 to 100% range after measuring the resistance value according to the state of charge (SOC) while fully charging the first coin cell and discharging it at 1C using the HPPC (hybrid pulse power characteristic) test at room temperature. In the above equation (1), Y1 is the average resistance of the negative electrode at room temperature and SOC 20 to 100%, and can be measured as the average resistance value (Ω) of the second coin cell in the SOC 20 to 100% range when discharging at 1C at room temperature. Specifically, Y1 is the average resistance value calculated for the SOC 20 to 100% range after measuring the resistance value according to the state of charge (SOC) while fully charging the second coin cell and discharging at 1C using the HPPC (Hybrid Pulse Power Characteristic) test at room temperature. At SOC 20 to 100%, since a high potential is applied, the structural collapse of the positive electrode and the side reaction with the electrolyte are maximized. This causes rapid degradation of the positive electrode, reducing the capacity retention rate of the lithium secondary battery. The lithium secondary battery of the present invention satisfies the above equation (1) at room temperature, so that the positive electrode resistance and the negative electrode resistance are adjusted to similar levels in the SOC 20 to 100% range, thereby preventing a large overvoltage of the positive electrode during charging, and preventing a large increase in the potential of the positive electrode during constant current (CC) charging, thereby reducing the structural collapse of the positive electrode material and the side reaction with the electrolyte. In the above equation (2), X2 is the average resistance of the positive electrode at room temperature and SOC 0 to 20%, and can be measured as the average resistance value (Ω) of the first coin cell in the SOC 0 to 20% range when discharging at 1C at room temperature. Specifically, X2 is the average resistance value calculated for the SOC 0 to 20% range after measuring the resistance value according to the state of charge (SOC) while fully charging the first coin cell and discharging at 1C using the HPPC (Hybrid Pulse Power Characteristic) test at room temperature. In the above equation (2), Y2 is the average resistance of the negative electrode at room temperature and SOC 0 to 20%, and can be measured as the average resistance value (Ω) of the second coin cell in the SOC 0 to 20% range when discharging at 1C at room temperature. Specifically, Y2 is the average resistance value calculated for the SOC 0 to 20% range after measuring the resistance value according to the state of charge (SOC) while fully charging the second coin cell and discharging at 1C using the HPPC (Hybrid Pulse Power Characteristic) test at room temperature. Silicon-based negative electrode active materials are highly activated at SOC 0 to 20%. If the potential of the negative electrode rises significantly in the SOC 0 to 20% range during discharge of a lithium secondary battery, the use of silicon-based negative electrode active materials increases, which maximizes pulverization and side reactions with the electrolyte, resulting in degradation of the performance of the lithium secondary battery. The lithium secondary battery of the present invention satisfies the above equation (2) at room temperature, so that the resistance of the positive electrode is set higher than that of the negative electrode, so that the potential of the positive electrode decreases before the negative electrode potential rises during discharge of the lithium secondary battery, allowing the operation of the lithium secondary battery to be terminated quickly. As a result, the potential of the negative electrode does not become high during discharge in the SOC 0 to 20% range, reducing the use of silicon-based negative electrode active materials, thereby suppressing negative electrode degradation and resulting in excellent life characteristics. The lithium secondary battery according to the present invention can more preferably satisfy the following equation (2-1). Equation (2-1): 2 × Y2 ≤ X2 ≤ 6.5 × Y2 In the above equation (2-1), the definitions of X2 and Y2 are the same as in equation (2). In addition, the lithium secondary battery according to the present invention can satisfy the following formula (A). Formula (A): 0.9 × Y1 + Y2 ≤ 1.5 × (X1 + 0.5 × X2) In the above formula (A), the definitions of X1, X2, Y1 and Y2 are the same as in formulas (1) and (2). The lithium secondary battery according to the present invention can satisfy the condition of the following equation (3) in which the average resistance X3 of the positive electrode at 40°C and SOC 20 to 100% and the average resistance Y3 of the negative electrode at 40°C and SOC 20 to 100% are satisfied. Equation (3): 0.75 × Y3 ≤ X3 ≤ Y3 In the above equation (3), X3 is the average resistance of the positive electrode at 40°C and SOC 20 to 100%, and can be measured as the average resistance value (Ω) of the first coin cell in the SOC 20 to 100% range when discharging at 1C at 40°C. Specifically, X3 is the average resistance value calculated for the SOC 20 to 100% range after fully charging the first coin cell using the HPPC (Hybrid Pulse Power Characteristic) test at 40°C and measuring the resistance value according to the state of charge (SOC) while discharging at 1C. In the above equation (3), Y3 is the average resistance of the cathode at 40°C and SOC 20 to 100%, which can be measured as the average resistance value (Ω) of the second coin cell in the SOC 20 to 100% range when discharging at 1C at 40°C. Y3 is the average resistance value calculated for the SOC 20 to 100% range after fully charging the second coin cell using the HPPC (hybrid pulse power characteristic) test at 40°C and measuring the resistance value according to the state of charge (SOC) while discharging at 1C. The lithium secondary battery of the present invention satisfies the above equation (3) at 40°C, so that the anode resistance and cathode resistance in the SOC 20-100% range can be controlled to be at a more similar level than at room temperature, so that the degradation levels of the anode and cathode can be controlled to be similar. The lithium secondary battery according to the present invention can satisfy the condition of the following equation (4) in which the average resistance X4 of the positive electrode at 40°C and SOC 0 to 20% and the average resistance Y4 of the negative electrode at 40°C and SOC 0 to 20% are satisfied. Equation (4): 1.5 × Y4 ≤ X4 In the above equation (4), X4 is the average resistance of the positive electrode at 40°C and SOC 0 to 20%, which can be measured as the average resistance value (Ω) of the first coin cell in the SOC 0 to 20% range when discharging at 1C at 40°C. Specifically, X4 is the average resistance value calculated for the SOC 0 to 20% range after fully charging the first coin cell using the HPPC (hybrid pulse power characteristic) test at 40°C and measuring the resistance value according to the state of charge (SOC) while discharging at 1C. In the above equation (4), Y4 is the average resistance of the cathode at 40°C and SOC 0 to 20%, which can be measured as the average resistance value (Ω) of the second coin cell in the SOC 0 to 20% range when discharging at 1C at 40°C. Specifically, Y4 is the average resistance value calculated for the SOC 0 to 20% range after fully charging the second coin cell using the HPPC (Hybrid Pulse Power Characteristic) test at 40°C and measuring the resistance value according to the state of charge (SOC) while discharging at 1C. Silicon-based negative electrode active materials are highly activated at SOC 0 to 20%. If the potential of the negative electrode rises significantly in the SOC 0 to 20% range during lithium secondary battery discharge, the use of silicon-based negative electrode active materials will increase, which will maximize pulverization and side reactions with the electrolyte, resulting in degradation of lithium secondary battery performance. By setting the resistance of the positive electrode higher than that of the negative electrode, the positive electrode potential will drop before the negative electrode potential rises during discharge, allowing the operation of the lithium secondary battery to be terminated quickly. This prevents the negative electrode discharge potential from being high in the SOC 0 to 20% range, reducing the use of silicon-based negative electrode active materials, and thereby suppressing negative electrode degradation, which is thought to result in excellent cycle life characteristics. The difference in resistance between the negative and positive electrodes is smaller under the 40℃ condition of Equation (4) than under the room temperature condition of Equation (2). This is thought to be because the positive electrode degradation is faster at high temperatures, allowing for a slightly lower positive electrode resistance. The lithium secondary battery according to the present invention can more preferably satisfy the following equation (4-1). Equation (4-1): 1.5 × Y4 ≤ X4 ≤ 6.5 × Y4 In the above equation (4-1), the definitions of X4 and Y4 are the same as in equation (4). The lithium secondary battery according to the present invention can satisfy the following formula (B). Formula (B): Y3 + 1.5 × Y4 ≤ X3 + X4 In the above formula (B), the definitions of X3, X4, Y3 and Y4 are the same as in formulas (3) and (4). The positive electrode of the present invention may have a structure in which a positive electrode active material layer is formed on one or both sides of a positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material, a conductive material, and a binder. As the positive electrode current collector, various positive electrode current collectors used in the relevant technical field can be used. For example, the positive electrode current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. The positive electrode current collector may 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. Meanwhile, as the positive electrode active material, positive electrode active materials generally used in the relevant technical field can be used. Preferably, the positive electrode active material may include a lithium nickel-based oxide, and specifically, may include a lithium nickel-based transition metal oxide having a nickel content of 85 atm% or more, or 90 atm% or more, among transition metals other than lithium. Preferably, the lithium nickel-based oxide may include Ni in an amount of 90 mol% or more and less than 100 mol%, 93 mol% or more and less than 100 mol%, or 95 mol% or more and less than 100 mol%. When a lithium nickel-based oxide having a high Ni content as described above is used, a high capacity can be realized. More specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following [chemical formula 5]. [Chemical Formula 5] Li a Ni b Co c M 1 d M 2 e O2 In the above chemical formula 5, M 1 It may be Mn, Al or a combination thereof, preferably Mn or Mn and Al. Above M 2 is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, preferably at least one selected from the group consisting of Zr, Y, Mg, and Ti, and more preferably Zr, Y or a combination thereof. M 2 Although elements are not essential, when included in appropriate amounts, they can promote grain growth during firing or play a role in improving crystal structure stability. The above a represents the molar ratio of lithium in the lithium nickel-based oxide, and may be 0.8≤a≤1.2, 0.85≤a≤1.15, or 0.9≤a≤1.2. When the molar ratio of lithium satisfies the above range, the crystal structure of the lithium nickel-based oxide can be stably formed. The above b represents the molar ratio of nickel among all metals excluding lithium in the lithium nickel-based oxide, and may be 0.85≤b<1, 0.9≤b<1, or 0.95≤b<0.98. When the molar ratio of nickel satisfies the above range, high energy density is exhibited, enabling high capacity implementation. The above c represents the molar ratio of cobalt among all metals excluding lithium in the lithium nickel oxide, and is 0. <c<0.15, 0<c<0.1, 또는 0.02≤c≤0.07일 수 있다. 코발트의 몰비가 상기 범위를 만족할 때, 양호한 저항 특성 및 출력 특성을 구현할 수 있다. The above d is M of all metals excluding lithium in lithium nickel oxide. 1 It represents the molar ratio of elements, 0 <d<0.15, 0<d<0.1, 또는 0.01≤d≤0.05일 수 있다. M 1 When the molar ratio of the elements satisfies the above range, the structural stability of the positive electrode active material is excellent. The above e is M of all metals except lithium in lithium nickel oxide. 2 It represents the molar ratio of elements, and can be 0≤e≤0.1 or 0≤e≤0.01. Meanwhile, the cathode active material according to the present invention may further include, if necessary, a coating layer comprising one or more coating elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si and S on the surface of the lithium nickel-based oxide particles. Preferably, the coating element may be Al, B, Co or a combination thereof, and most preferably, the coating element may be B. When a coating layer exists on the surface of lithium nickel-based oxide particles, the contact between the electrolyte and the lithium composite transition metal oxide is suppressed by the coating layer, thereby reducing the elution of transition metal or gas generation due to side reactions with the electrolyte. Meanwhile, the form of the positive electrode active material is not particularly limited, and may be in the form of a secondary particle in which multiple primary particles are aggregated, a single particle composed of one primary particle, or a combination of these. Preferably, the positive electrode active material may include a positive electrode active material composed of a single particle consisting of one primary particle and / or a quasi-single particle which is an aggregate of 10 or fewer primary particles. By using a positive electrode active material composed of a single particle consisting of one primary particle and / or a quasi-single particle which is an aggregate of 10 or fewer primary particles, a lithium secondary battery having high capacity and excellent safety can be obtained. The positive electrode active material in the form of a single particle or a pseudo-single particle in which 10 or fewer primary particles are aggregated has higher particle strength than the existing secondary particle type positive electrode active material in which tens to hundreds of primary particles are aggregated, so that the particles are hardly broken during rolling. In addition, in the case of the positive electrode active material in the form of a single particle or a pseudo-single particle, since the number of primary particles constituting the particle is small, the change due to volume expansion and contraction of the primary particles during charge and discharge is small, and accordingly, the occurrence of cracks inside the particle is also significantly reduced. Therefore, there is a problem that the structural instability of the positive electrode increases as the content of Ni in the positive electrode material increases in order to implement high energy, but when the positive electrode active material is used in the form of single particles and / or pseudo-single particles, the amount of gas generated due to particle breakage and internal cracks can be significantly reduced, and excellent safety can be implemented. However, when using a positive electrode active material with a high content of nickel in the form of single particles, there is a limitation of high resistance, so it is necessary to adjust the resistance characteristics of the positive and negative electrodes of the lithium secondary battery so that the conditions of the above equations (1) and (2) are satisfied. In particular, the powder resistance of the positive electrode active material may be 100 to 500 Ω, preferably 200 to 400 Ω, and more preferably 300 to 350 Ω. When the powder resistance satisfies the above range, it can be adjusted to have a degree of degradation similar to that of the negative electrode. Meanwhile, the cathode active material in the form of single particles and / or pseudo-single particles according to the present invention has an average particle diameter D 50 The average particle size of the positive electrode active material may be 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, and more preferably 2 μm to 5 μm. The average particle size D of the positive electrode active material 50 When this above range is satisfied, the increase in resistance can be minimized. Single particle and / or pseudo-single particle type cathode active materials have a problem in that lithium mobility is lower than that of secondary particle type cathode active materials because the interface between primary particles, which serves as a diffusion path for lithium ions within the particles, is small, which increases resistance. This increase in resistance becomes more severe as the particle size increases, and an increase in resistance adversely affects capacity and output characteristics. Therefore, in the present invention, the average particle diameter D 50 By applying a single particle or pseudo-single particle positive electrode active material of 5㎛ or less, the diffusion distance of lithium ions within the particle can be minimized, thereby suppressing the increase in resistance. The above-mentioned single particle and / or pseudo-single particle type positive electrode active material may have an average particle diameter of silver primary particles of 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, for example, 0.5 μm to 5 μm, preferably 1 μm to 5 μm, more preferably 2 μm to 5 μm. When the average particle diameter of the primary particles satisfies the above range, a single particle and / or pseudo-single particle type positive electrode active material having excellent electrochemical properties can be formed. If the average particle diameter of the primary particles is too small, the number of agglomerates of the primary particles forming the positive electrode active material increases, which reduces the effect of suppressing particle breakage during rolling, and if the average particle diameter of the primary particles is too large, the lithium diffusion path within the primary particles becomes long, which may increase the resistance and deteriorate the output characteristics. In the present invention, it is preferable that the positive electrode active material in the form of single particles and / or pseudo-single particles have a unimodal particle size distribution. Conventionally, bimodal positive electrode active materials have been widely used, in which a large-particle positive electrode active material with a large average particle size and a small-particle positive electrode active material with a small average particle size are mixed to improve the electrode density of the positive electrode active material layer. However, in the case of positive electrode active materials in the form of single particles or pseudo-single particles, when the particle size increases, the lithium migration path becomes longer, which significantly increases the resistance. Therefore, when large-particle particles are mixed and used, a problem of reduced capacity and output characteristics may occur. Therefore, in the present invention, by using a positive electrode active material with a unimodal distribution, the increase in resistance can be minimized. Next, the conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any particular limitation. 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 among these, one type alone or a mixture of two or more types may be used. The above-mentioned conductive material may be included in an amount of 0.1 to 2.5 wt%, preferably 0.5 to 2.0 wt%, and more preferably 1.0 to 1.8 wt%, based on the total weight of the positive electrode active material layer. The above binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode current collector, and 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, polyvinylpyrrolidone, 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 binder may be included in an amount of 1 to 30 wt%, preferably 1 to 10 wt%, and more preferably 1.5 to 5.0 wt%, based on the total weight of the positive electrode active material layer. The negative electrode of the present invention may have a structure in which a negative electrode active material layer is formed on one or both sides of a negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a conductive material, and a binder. As the negative electrode current collector, negative electrode collectors generally used in the relevant technical field can be used, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. The negative electrode current collector can typically have a thickness of 3 to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. The above negative active material is Si, Si-Me alloy (wherein, Me is at least one selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiOy (wherein, 0 <y<2), Si-C 복합체 등과 같은 실리콘계 음극 활물질을 포함할 수 있고, 가장 바람직하게는 SiO, SiC 및 Si로 이루어지는 군으로부터 선택되는 실리콘계 음극 활물질을 포함할 수 있다. 실리콘계 음극 활물질을 포함하는 음극은 높은 용량을 구현할 수 있다. 그러나, 저항이 높은 양극을 실리콘계 음극 활물질을 포함하는 음극과 함께 사용하는 경우, 상온에서 실리콘계 음극재를 포함하는 음극의 사용량이 많아져 음극이 급격하게 퇴화하여 리튬 이차 전지의 성능이 급속히 퇴화하는 한계점이 있으므로, 리튬 이차 전지의 양, 음극의 저항 특성을 상기 식 (1) 및 식 (2) 의 조건이 만족되도록 조절할 필요가 있다. As a negative electrode active material other than the silicon-based negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; lithium metal thin films; metal materials capable of alloying with lithium, such as Sn and Al; and the like. One or a mixture of two or more of these may be used. The above silicon-based negative electrode active material may be included in an amount of 3 wt% or more, preferably 3 to 10 wt%, and more preferably 3 to 6 wt%, relative to the entire negative electrode active material layer. The above conductive material is used to provide conductivity to the negative electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. 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. One of these may be used alone or a mixture of two or more may be used. The above-mentioned conductive material may be typically included in an amount of 0.05 to 2.50 wt%, preferably 0.5 to 2.0 wt%, and more preferably 1.0 to 1.5 wt%, based on the total weight of the negative electrode active material layer. The above binder serves to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. 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 binder may be included in an amount of 1 to 10 wt%, preferably 1 to 5 wt%, and more preferably 1.5 to 3.0 wt%, based on the total weight of the negative electrode active material layer. In addition to the positive and negative electrodes, a separator interposed between the positive and negative electrodes separates the positive and negative electrodes and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries may be used without particular limitations. Specifically, the separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength. In addition, the electrolyte used in the present invention may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc. that can be used in the manufacture of a lithium secondary battery. Specifically, the electrolyte may include an organic solvent and a lithium salt. As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable. The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of, and the lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. It is recommended that the concentration of the lithium salt be within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively. In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 10 wt% based on the total weight of the electrolyte. There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape. 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 devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims. Example Example 1 D 50 This 10.8㎛ cathode active material (LiNi 0.958 Co0.015 Mn 0.027 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.6:1.8:2.6 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: artificial graphite: SiO = 47.75:47.75:4.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.95:1.05:1.70:1.30. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 1. In the graph of Fig. 1, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 1, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 2. In the graph of Fig. 2, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 2, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Example 2 D 50 This 8.5㎛ cathode active material LiNi 0.891 Co 0.066 Mn 0.043 O 2, A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.95:1.50:2.55 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.7:1.4:1.5:1.4. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 3. In the graph of Fig. 3, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 3, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 4. In the graph of Fig. 4, the average resistance value (Ω) X3 of the first coin cell in the SOC 20-100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20-100% region were calculated and shown in Table 1 below. In the graph of Fig. 4, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Example 3 D 50 This 11.2㎛ cathode active material (LiNi 0.962 Co 0.029 Mn 0.009 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.69:1.30:3.01 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: artificial graphite: SiO = 46.75:46.75:6.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.625:1.075:1.900:1.400. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 5. In the graph of Fig. 5, the average resistance value (Ω) X1 of the first coin cell in the SOC 20-100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20-100% region were calculated and shown in Table 1 below. In the graph of Fig. 5, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 6. In the graph of Fig. 6, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 6, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Comparative Example 1 D 50 This 3.8㎛ cathode active material (LiNi0.962 Co 0.029 Mn 0.009 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.19:1.80:3.01 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: artificial graphite: SiO = 46.75:46.75:6.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.625:1.0750:1.900:1.400. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 7. In the graph of Fig. 7, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 7, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 8. In the graph of Fig. 8, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 8, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Comparative Example 2 D 50 This 3.8㎛ cathode active material (LiNi 0.962 Co 0.029 Mn 0.009 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.19:1.80:3.01 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: artificial graphite: SiO = 44.75:44.75:10.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.625:1.075:1.900:1.400. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 9. In the graph of Fig. 9, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 9, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 10. In the graph of Fig. 10, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 10, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Comparative Example 3 D 50 This 11.2㎛ cathode active material (LiNi 0.962 Co 0.029 Mn 0.009 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.6:1.8:2.6 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: artificial graphite: SiO = 44.75:44.75:10.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.625:1.075:1.900:1.400. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 11. In the graph of Fig. 11, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region are calculated and shown in Table 1 below. In the graph of Fig. 11, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 12. In the graph of Fig. 12, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 12, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. Comparative Example 4 D 50This 4.5㎛ cathode active material (LiNi 0.962 Co 0.029 Mn 0.009 O2) , A positive electrode slurry was prepared by mixing carbon nanotubes and PVDF binder in a weight ratio of 95.69:1.30:3.01 in N-methylpyrrolidone. The positive electrode slurry was applied to both sides of an aluminum current collector sheet, dried at 120°C, and then rolled to prepare a positive electrode. A negative electrode slurry was prepared by mixing a negative electrode active material (natural graphite: SiO = 93.5:6.5 weight ratio mixture), super C, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in water at a weight ratio of 95.625:1.075:1.900:1.400. The negative electrode slurry was applied to both sides of a copper current collector sheet, dried at 150°C, and then rolled to prepare a negative electrode. An electrolyte was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) = 20:5:75 volume ratio) to a concentration of 1.3 M. A separator was interposed between the positive and negative electrodes manufactured as described above, and the separator / positive electrode / separator / negative electrode were laminated in that order, and then wound to manufacture a jelly-roll type electrode assembly. The electrode assembly manufactured as described above was inserted into a cylindrical battery can. The electrolyte was injected into the battery can to manufacture a 4680 cell, which was then activated to manufacture a lithium secondary battery. The positive and negative electrodes were separated from the activated lithium secondary battery. A first coin cell was manufactured using the separated positive electrode and lithium metal counter electrode, and a second coin cell was manufactured using the separated negative electrode and lithium metal counter electrode. The resistance of the manufactured first and second coin cells was measured while discharging at 1 C at 24°C, and the results are shown in Figure 13. In the graph of Fig. 13, the average resistance value (Ω) X1 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y1 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 13, the average resistance value (Ω) X2 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y2 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. In addition, the resistance of the manufactured first and second coin cells was measured while discharging at 1C at 40°C, and the results are shown in Fig. 14. In the graph of Fig. 14, the average resistance value (Ω) X3 of the first coin cell in the SOC 20~100% region and the average resistance value (Ω) Y3 of the second coin cell in the SOC 20~100% region were calculated and shown in Table 1 below. In the graph of Fig. 14, the average resistance value (Ω) X4 of the first coin cell in the SOC 0~20% region and the average resistance value (Ω) Y4 of the second coin cell in the SOC 0~20% region were calculated and shown in Table 1 below. X1Y1X2Y2X3Y3X4Y4Example 17.49.589.421.75.67.463.324.6Example 28.39.3100.915.56.16.280.814.1Example 310.412.693.126.19.28.167.124.2Comparative Example 17.412.438.424.25.97.731.623.0Comparative Example 27.47.938.418.85.97.131.621.4Comparative Example 38.37.189.420.07.16.563.322.4Comparative Example 411.812.946.128.212.811.140.127.0 Experimental Example 1 - Evaluation of Room Temperature Lifetime Characteristics The room temperature life characteristics were evaluated for the 4680 cells of Examples 1 to 3 and Comparative Examples 1 to 4. Specifically, for each of the 4680 cells of Examples 1 to 3 and Comparative Examples 1 to 4, 70 charge-discharge cycles were performed, with one cycle being a charge to 4.2 V at a constant current of 0.5 C at 24°C and a discharge to 2.5 V at a constant current of 0.5 C, and the capacity retention rate compared to the initial capacity after the 70th cycle was measured. The results are shown in Table 2 below. Capacity retention rate (%) Example 197.4 Example 295.4 Example 392.4 Comparative example 190.3 Comparative example 286.4 Comparative example 387.2 Comparative example 477.4 As shown in Table 2 above, it was confirmed that the lithium secondary batteries satisfying Equations (1) and (2) of Examples 1 to 3 had superior room temperature life characteristics compared to the lithium secondary batteries of Comparative Examples 1 to 4 that did not satisfy at least one of Equations (1) and (2). Experimental Example 2 - Evaluation of High-Temperature Lifetime Characteristics High temperature life characteristics were evaluated for the 4680 cells of Examples 1 to 3 and Comparative Examples 1 to 4. Specifically, for each of the 4680 cells of Examples 1 to 3 and Comparative Examples 1 to 4, 70 charge-discharge cycles were performed, with one cycle being a charge to 4.2 V at a constant current of 0.5 C at 40°C and a discharge to 2.5 V at a constant current of 0.5 C, and the capacity retention rate compared to the initial capacity after the 70th cycle was measured. The results are shown in Table 3 below. Capacity retention rate (%) Example 196.5 Example 295.7 Example 394.1 Comparative example 193.7 Comparative example 292.9 Comparative example 393.9 Comparative example 486.2 As shown in Table 3 above, it was confirmed that the lithium secondary batteries satisfying Equations (1) and (2) of Examples 1 to 3 had superior high-temperature life characteristics compared to the lithium secondary batteries of Comparative Examples 1 to 4 that did not satisfy at least one of Equations (1) and (2).

Claims

1. A lithium secondary battery comprising a positive electrode; a negative electrode; and an electrolyte, A lithium secondary battery in which the average resistance X1 of the positive electrode at room temperature and SOC 20 to 100% and the average resistance Y1 of the negative electrode at room temperature and SOC 20 to 100% satisfy the following equation (1), and the average resistance X2 of the positive electrode at room temperature and SOC 0 to 20% and the average resistance Y2 of the negative electrode at room temperature and SOC 0 to 20% satisfy the following equation (2). Equation (1): 0.6 × Y1 ≤ X1 ≤ 0.9 × Y1 Equation (2): 2 × Y2 ≤ X2 2. In claim 1, A lithium secondary battery, wherein the average resistance X3 of the positive electrode at 40°C and SOC 20 to 100% and the average resistance Y3 of the negative electrode at 40°C and SOC 20 to 100% additionally satisfy the following equation (3). Equation (3): 0.75 × Y3 ≤ X3 ≤ Y3 3. In claim 1, A lithium secondary battery, wherein the average resistance X4 of the positive electrode at 40°C and SOC 0 to 20% and the average resistance Y4 of the negative electrode at 40°C and SOC 0 to 20% additionally satisfy the following equation (4). Equation (4): 1.5 × Y4 ≤ X4 4. In claim 1, The above positive electrode includes a positive electrode active material layer and a positive electrode current collector, The above positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder, A lithium secondary battery wherein the positive electrode active material is a lithium nickel-based transition metal oxide having a nickel content of 85 atm% or more among transition metals other than lithium.

5. In claim 4, A lithium secondary battery wherein the positive electrode active material is a single particle or a pseudo-single particle.

6. In claim 4, A lithium secondary battery in which a conductive material is included in an amount of 0.1 to 2.5 wt% for the entire positive electrode active material layer.

7. In claim 4, A lithium secondary battery having a powder resistance of the positive electrode active material of 100 to 500 Ω.

8. In claim 1, The above negative electrode includes a negative electrode active material layer and a negative electrode current collector, The above negative electrode active material layer includes a negative electrode active material, a conductive material, and a binder, A lithium secondary battery wherein the negative electrode active material includes a silicon-based negative electrode active material.

9. In claim 8, A lithium secondary battery wherein the silicon-based negative electrode active material is selected from the group consisting of SiO, SiC, and Si.

10. In claim 8, A lithium secondary battery, wherein the silicon-based negative electrode active material is included in an amount of 3 wt% or more relative to the entire negative electrode active material layer.

11. In claim 8, A lithium secondary battery comprising a conductive material in an amount of 0.05 to 2.50 wt% relative to the entire negative active material layer.

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