Lithium secondary battery

Abstract

The present invention relates to a lithium secondary battery comprising: an electrode assembly including a cathode, an anode and a separator interposed between the cathode and the anode; an electrolyte; and a battery case including an inner space for accommodating the electrode assembly and the electrolyte, wherein the cathode includes a cathode active material, the cathode active material includes a lithium nickel-based oxide containing 50-70 mol% nickel from total metal content thereof excluding lithium, and the electrolyte filling factor (EFF) index (unit: g / Ah) defined by relation 1 is 1.82-2.06. [Relation 1] In relation 1, RE [unit: g] represents the weight of the remaining electrolyte included in the lithium secondary battery after activation, SU represents the ratio (SA / SE) of the volume (SA) of the electrode assembly and the volume (SE) of the lithium secondary battery, and NC [unit: Ah] represents the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C.

Description

lithium secondary battery Cross-citation with related applications This application claims the benefit of priority from Korean Patent Application No. 10-2024-0016255, filed February 1, 2024, the entire contents of which are incorporated herein by reference. Technology field The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery having high energy density and excellent high-temperature life characteristics. Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing. The above lithium secondary battery is generally composed of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte that serves as a medium for transferring lithium ions, and a separator. At this time, carbon-based active materials, silicon-based active materials, etc. can be used as the negative electrode active material, and lithium transition metal oxides such as lithium cobalt oxide, lithium nickel oxide, and lithium nickel-cobalt-manganese composite transition metal oxide can be used as the positive electrode active material. Meanwhile, lithium nickel-cobalt-manganese composite transition metal oxides containing nickel at a concentration of 80 mol% or more, excluding lithium, as a cathode active material have recently been studied primarily to increase the energy density of cathodes. However, increasing the nickel content of lithium nickel-cobalt-manganese composite transition metal oxides has the problem that the structural stability of the cathode active material rapidly deteriorates at high temperatures, significantly degrading its performance and lowering its thermal stability. To prevent these problems, when the nickel content in the lithium nickel-cobalt-manganese composite transition metal oxide is lowered, the operating voltage must be increased to achieve the required energy density. However, when operating at such a high voltage, the electrolyte side reaction at the cathode becomes more severe and the amount of gas generated inside the battery increases. Therefore, there is a need to develop a lithium secondary battery that has excellent energy density and thermal stability while reducing electrolyte side reactions during high-voltage operation. The present invention is intended to solve the above problems, and to provide a lithium secondary battery having excellent high-temperature life characteristics by realizing high energy density, excellent thermal stability of a positive electrode active material, and reduced electrolyte side reactions at high voltage. [1] The present invention provides a lithium secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; an electrolyte; and a battery case storing the electrode assembly and the electrolyte; wherein the positive electrode includes a positive electrode active material, and the positive electrode active material includes a lithium nickel-based oxide including 50 mol% to 70 mol% of nickel among all metals excluding lithium, and has an Electrolyte Filing Factor (EFF) index (unit: g / Ah) defined by the following Equation 1 of 1.82 to 2.06. [Formula 1] In the above equation 1, R E [Unit: g] refers to the weight of the remaining electrolyte contained in the lithium secondary battery after activation, and S U is the volume (S) of the electrode assembly A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E ) means, N C[Unit: Ah] refers to the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C. [2] The present invention, in the above [1], the R E Provides a lithium secondary battery weighing 265 to 295 g. [3] The present invention, in the above [1] or [2], the S U A lithium secondary battery is provided, wherein the resistance is 0.70 to 0.95. [4] The present invention, in at least one of the above [1] to [3], the N C Provides a lithium secondary battery having a capacity of 90 to 150 Ah. [5] The present invention, in at least one of the above [1] to [4], the N C The above R for E The ratio of (R) E / N C ) [Unit: g / Ah] is 2.00 to 3.30, and provides a lithium secondary battery. [6] The present invention, in at least one of the above [1] to [5], the volume (S) of the electrode assembly A ) provides a lithium secondary battery having a capacity of 0.3 L to 1.35 L. [7] The present invention, in at least one of the above [1] to [6], the volume (S) of the lithium secondary battery E ) provides a lithium secondary battery having a capacity of 0.4 L to 1.5 L. [8] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to [7], the lithium nickel-based oxide contains cobalt (Co) in an amount of 15 mol% or less among all metals excluding lithium. [9] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [8], the lithium nickel-based oxide is represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 [Ni x1 Co y1 Mn z1 M 1 w1 ]O2 In the above chemical formula 1, 0≤a1≤0.5, 0.5≤x1≤0.7, 0 <y1≤0.15, 0<z1≤0.4, 0≤w1≤0.2이고, M 1 is at least one doping element selected from among W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo.

[0010] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [9], the lithium nickel-based oxide is a single particle.

[0011] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0010] , the lithium secondary battery has a charge cut-off voltage of 4.3 V or higher.

[0012] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0011] , the lithium secondary battery has a nominal voltage of 3.68 V or higher.

[0013] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0012] , the negative electrode includes graphite as a negative electrode active material.

[0014] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0013] , the battery case is a square battery case.

[0015] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0014] , the electrode assembly is formed by sequentially stacking a positive electrode, a separator, and a negative electrode and winding them in one direction. According to the present invention, by including nickel in an amount of 50 to 70 mol% among all metals excluding lithium, the structural stability of the positive electrode active material at high temperatures is improved, resulting in excellent thermal stability. In addition, by appropriately controlling the weight of the electrolyte remaining after activation according to the structure and capacity of the lithium secondary battery, the amount of gas generated inside the battery can be reduced during high-voltage operation, while at the same time ensuring appropriate electrolyte impregnation properties. As a result, the manufactured lithium secondary battery can secure high energy density and high capacity characteristics, and can have excellent life characteristics and high-temperature life characteristics. 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 idea 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 way. The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, it should be understood that terms such as “include,” “have,” or “have” 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, a "single-particle particle" means a particle composed of 30 or fewer sub-particles. The sub-particle unit constituting the single-particle particle is referred to as a "nodule." The single-particle particle includes a single particle composed of one single nodule and a pseudo-single particle which is a composite of 30 or fewer nodules. The above “nodule” refers to a sub-particle unit body constituting a single particle and a pseudo-single particle, and the nodule may be a single crystal lacking a crystalline grain boundary, or a polycrystal in which no grain boundary exists in appearance when observed at a field of view of 5,000 to 20,000 times using a scanning electron microscope (SEM). In the present invention, "secondary particle" refers to a particle formed by the aggregation of more than 30 sub-particles. To distinguish it from the sub-particles constituting the single particle, each sub-particle unit constituting the secondary particle is called a "primary particle." The expression “particle” used in the present invention may include any one or all of single particles, quasi-single particles, primary particles, nodules, and secondary particles. In the present invention, "average particle diameter D 50"It refers to the particle size corresponding to 50% of the volume accumulation amount of the volume accumulation particle size distribution of the powder to be measured, and can be measured using the laser diffraction method. For example, after dispersing the powder to be measured 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 accumulation particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume accumulation amount. The present inventors have conducted repeated research to develop a lithium secondary battery having excellent life performance and storage performance at high temperatures and high voltages while achieving high capacity characteristics. As a result, they have found that by including 50 mol% to 70 mol% of nickel among metals other than lithium and controlling the structure of the lithium secondary battery, discharge capacity, and the weight of the electrolyte remaining after activation to satisfy a specific formula, the capacity characteristics of the lithium secondary battery can be excellent, the life and storage characteristics at high voltages and high temperatures can be excellent, and the electrolyte impregnation property can be improved, thereby completing the present invention. Hereinafter, the present invention will be described in more detail. A lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination between technically possible configurations among the configurations below. lithium secondary battery A lithium secondary battery according to the present invention comprises: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; an electrolyte; and a battery case including an internal space for accommodating the electrode assembly and the electrolyte; wherein the positive electrode includes a positive electrode active material, and the positive electrode active material includes a lithium nickel-based oxide including 50 mol% to 70 mol% of nickel among the total metals excluding lithium, and has an Electrolyte Filing Factor (EFF) index (unit: g / Ah) defined by the following equation 1 of 1.82 to 2.06. [Formula 1] In the above equation 1, R E [Unit: g] refers to the weight of the remaining electrolyte contained in the lithium secondary battery after activation, and S U is the volume (S) of the electrode assembly A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E ) means, N C [Unit: Ah] refers to the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C. The lithium secondary battery according to the present invention has an EFF index (unit: g / Ah) defined by the above formula 1 of 1.82 to 2.06, specifically, 1.82 or more, 1.83 or more, 1.84 or more, 1.85 or more, 1.86 or more, 1.87 or more, 1.88 or more, 1.89 or more, 1.90 or more, 1.91 or more, and 2.06 or less, 2.05 or less, 2.04 or less, 2.03 or less, 2.02 or less, 2.01 or less, 2.00 or less, 1.99 or less, 1.98 or less, 1.97 or less, 1.96 or less, 1.95 or less, 1.94 or less, 1.93 or less, 1.92 or less, 1.91 or less. For example, the EFF index may be 1.82 to 2.06, 1.88 to 2.00, 1.89 to 1.96, or 1.90 to 1.94. Recently, in order to realize the high capacity characteristics of lithium secondary batteries, there have been attempts to increase the energy density of the cathode by using lithium nickel oxide with increased nickel content including nickel, cobalt, and manganese as the cathode active material. However, when the nickel content of the lithium nickel oxide is increased, Ni 2+ The ion is Ni 4+ As it changes into ions, the structural stability and chemical stability of the positive electrode active material deteriorate, and as a result, side reactions with the electrolyte are accelerated, which reduces the life characteristics. This phenomenon is further accelerated when exposed to high temperatures, and there was a problem that the thermal stability was greatly reduced. Reducing the nickel content of lithium nickel-based oxides can improve thermal stability at high temperatures. However, to achieve energy density equivalent to that of lithium nickel-based oxides containing a high nickel content, operation at high voltages (e.g., 4.35 V or higher) is necessary. However, during such high-voltage operation, oxygen is desorbed due to changes in the oxidation states of nickel and cobalt, which intensifies electrolyte side reactions and increases gas generation, resulting in deterioration of life and storage performance. Accordingly, it is necessary to reduce the amount of electrolyte injected to reduce the amount of gas generated. However, if the amount of electrolyte injected is excessively reduced, the electrolyte impregnation property of the electrode deteriorates, which increases the mobility of lithium ions and cell resistance, and thus the capacity and life characteristics of the battery may actually decrease. Therefore, the amount of electrolyte injected must be appropriately adjusted according to the characteristics of the battery. Therefore, the lithium secondary battery according to the present invention solves the above problem by controlling the weight of the electrolyte remaining after activation to a specific condition according to the characteristics of the lithium secondary battery according to the ratio of the volume of the lithium secondary battery excluding the battery case and the discharge capacity of the lithium secondary battery. Specifically, the lithium secondary battery according to the present invention can achieve high energy density and high capacity characteristics by controlling the EFF index defined by the above formula 1 to be 1.82 to 2.06, while having excellent thermal stability and reduced gas generation while having appropriate electrolyte impregnation properties, thereby exhibiting excellent high-temperature life characteristics and high-temperature storage characteristics. The above R E refers to the weight of the remaining electrolyte contained in the lithium secondary battery after activation. The residual electrolyte included in the above lithium secondary battery means the sum of the electrolyte impregnated in the internal pores of the electrode assembly and the electrolyte located outside the electrode assembly in the internal space of the battery case. The weight of the remaining electrolyte contained in the lithium secondary battery after the above activation may be different from the weight of the electrolyte initially injected into the battery case during the lithium secondary battery manufacturing process before activation. The above activation refers to a process of charging and / or discharging a lithium secondary battery that has been manufactured but has not been charged or discharged to provide electrical characteristics and forming a solid electrolyte interphase (SEI) film on the electrode to stabilize the battery, thereby making the battery ready for actual use. The above R E In relation to this, the activation can be achieved by performing the step of charging the lithium secondary battery to a voltage of 4.0 V or higher at 55°C at least once. Specifically, the above R E In relation to this, the activation can be achieved by performing (1) a step of charging the lithium secondary battery to 4.0 V or SOC 3% under a constant current condition of 0.2 C at 55°C, (2) a step of charging the lithium secondary battery to 4.35 V or SOC 17% under a constant current condition of 1.0 C at 55°C, and (3) a step of charging the lithium secondary battery to 4.35 V or SOC 60% under a constant current condition of 1.0 C at 55°C. The weight (R) of the remaining electrolyte contained in the lithium secondary battery after the above activation E ) is (1) the weight (M) of a lithium secondary battery after activation, including an electrode assembly, an electrolyte and a battery case, and in a sealed state of the battery case L ), (2) a step of disassembling the lithium secondary battery to remove the electrolyte present in the battery case, (3) a step of immersing the battery case and the electrode assembly in a solvent such as dimethyl carbonate to remove the electrolyte present in the surface of the battery case, the surface of the electrode assembly, and the internal pores, and then drying the battery case and the electrode assembly, (4) a step of measuring the weight (M) of the dried battery case C ) and the weight (M) of the dried electrode assembly A ) after the step of measuring, the measured M L , M C , M A It can be measured by substituting it into Equation A. [Formula A] R E = M L -M C -M A The above R Emay be 265 to 295 g, 267 to 290 g, 270 to 282 g, or 272 to 278 g. When the above range is satisfied, the electrolyte side reaction is reduced, the amount of gas generated is reduced, and sufficient electrolyte impregnation can be achieved, so that the mobility of lithium ions can be sufficiently secured, and the life characteristics, output characteristics, and high-temperature storage characteristics can be excellent. S U is the volume (S) of the electrode assembly A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E ) means. The volume (S) of the lithium secondary battery E ) is a volume calculated based on the external shape of the lithium secondary battery, and specifically, it means the volume of the space occupied by the external shape of the lithium secondary battery. At this time, the external shape of the lithium secondary battery may be the same as the external shape of the battery case when the battery case is sealed. The volume of the lithium secondary battery may be determined based on the external dimensions of the lithium secondary battery, without considering the volume occupied by the components such as the electrolyte and electrode assembly accommodated inside the battery case, or the volume of the void. If the above battery case is a square battery case, the volume (S) of the lithium secondary battery E ) can be obtained by the following formula B. The volume (S) of the lithium secondary battery according to the following formula B E ) is obtained by assuming that the shape of a lithium secondary battery including a square battery case is a rectangular parallelepiped. [Formula B] S E = (Thickness of lithium secondary battery) × (Length of lithium secondary battery) × (Width of lithium secondary battery) In the above formula B, the thickness of the lithium secondary battery means a distance measured along the thickness direction of the lithium secondary battery based on the external shape of the lithium secondary battery. In the above formula B, the length of the lithium secondary battery means a distance measured along the longitudinal direction of the lithium secondary battery based on the external shape of the lithium secondary battery. In the above formula B, the width of the lithium secondary battery means a distance measured along a direction perpendicular to the longitudinal direction of the lithium secondary battery based on the external shape of the lithium secondary battery. The shape of the lithium secondary battery is not limited to the shape described above and may have any suitable shape. The volume of the lithium secondary battery can be determined by an appropriate measuring method depending on the shape of the lithium secondary battery. The volume (S) of the above electrode assembly A ) refers to the total volume occupied by the positive electrode, the negative electrode, and the separator. The volume of the electrode assembly can be controlled by adjusting the porosity and loading amount of the positive electrode and the negative electrode, the N / P ratio (N / P ratio), which is the ratio of the negative electrode capacity to the positive electrode capacity, or by changing the type of conductive material included in the positive electrode and the negative electrode. The volume of the electrode assembly may be measured based on the external shape of the positive electrode, the negative electrode, and / or the separator, not excluding the volume of the pores included in the positive electrode, the negative electrode, and / or the separator. The volume (S) of the above electrode assembly A ) can be obtained by the following formula C. [Formula C] S A =(volume of anode)+(volume of cathode)+(volume of membrane) In the above formula C, the volume of the anode, the volume of the cathode, and the volume of the separator may be measured based on the external shape of the anode, cathode, or separator, without considering the volume of pores included in the anode, cathode, or separator, respectively. S above Umay be 0.70 to 0.95, 0.73 to 0.90, 0.75 to 0.85, or 0.77 to 0.82. When the above range is satisfied, the relative space utilization rate can be increased within the same capacity, thereby realizing high energy density, and the gas generated due to the electrolyte side reaction can be appropriately accommodated. The volume (S) of the above lithium secondary battery E ) can be 0.4 L to 1.5 L, 0.5 L to 1.3 L, or 0.6 L to 1.1 L. When the above range is satisfied, the electrode assembly and electrolyte can be sufficiently accommodated, and S U The value can satisfy an appropriate range. The volume (S) of the above electrode assembly A ) can be 0.3 L to 1.35 L, 0.4 L to 1.2 L, or 0.5 to 1 L. When the above range is satisfied, the energy density is excellent, and S U The value can satisfy an appropriate range. The above N C refers to the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C. Specifically, the above N C After activating the lithium secondary battery, the capacity when the lithium secondary battery is charged at 25°C and discharged from 4.4 V to 2.5 V at 0.33 C may refer to the discharge capacity when the first charge / discharge is performed after activation. The N C In relation to this, after the above activation, the first charge / discharge may be performed by charging the lithium secondary battery from 2.5 V to 4.35 V at a C-rate of 0.33 C at 25°C. The above N CIn this case, the activation may be performed by charging a lithium secondary battery that has been manufactured and has not been charged or discharged to 4.35 V with a 0.05 C cut under a constant current / constant voltage condition of 0.33 C at 25°C, and discharging it to 2.0 V under a constant current condition of 0.33 C. The above N C The capacity may be 90 to 150 Ah, 100 to 140 Ah, 105 to 130 Ah, or 110 to 120 Ah. When the above range is satisfied, high capacity characteristics can be achieved. Capacity (N) when the above lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C C ) The weight (R) of the remaining electrolyte contained in the lithium secondary battery after the above activation E ) of the ratio (R) E / N C ) [Unit: g / Ah] may be 2.00 to 3.30. Specifically, the R E / N C [Unit: g / Ah] may be 2.05 or more, 2.07 or more, 2.10 or more, 2.13 or more, 2.15 or more, 2.17 or more, 2.20 or more, 2.23 or more, 2.25 or more, 2.27 or more, 2.30 or more, 3.30 or less, 3.10 or less, 3.00 or less, 2.90 or less, 2.80 or less, 2.70 or less, 2.60 or less, 2.55 or less, 2.50 or less, 2.45 or less, 2.40 or less. For example, the R E / N C [Unit: g / Ah] can be 2.00 to 3.30, 2.15 to 2.90, 2.23 to 2.55, or 2.30 to 2.40. When the above range is satisfied, the effects of reducing gas generation and improving electrolyte impregnation can be maximized depending on the battery design. Next, each component of the lithium secondary battery according to the present invention will be described in more detail. A lithium secondary battery according to the present invention comprises an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; an electrolyte; and a battery case that accommodates the electrode assembly and the electrolyte. (1) Electrode assembly An electrode assembly according to the present invention includes an anode, a cathode, and a separator interposed between the anode and the cathode. Specifically, the electrode assembly can be formed by sequentially stacking an anode, a separator, and a cathode, and the anode and the cathode can be mutually insulated by the separator. Types of electrode assemblies include, but are not limited to, stacked, jelly roll, and stack-and-fold. Preferably, the type of the electrode assembly may be a jelly roll type, and the electrode assembly may be one in which the positive electrode, the separator, and the negative electrode are sequentially stacked and wound in one direction, and specifically, a plurality of the positive electrodes, the separator, and the negative electrode may be alternately stacked and wound in one direction. Hereinafter, each component of the electrode assembly according to the present invention will be described in detail. 1) Bipolar The positive electrode includes a positive electrode active material. 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, and the positive electrode active material layer may include a positive electrode active material. 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. The positive electrode active material layer may be positioned on the positive electrode current collector, and specifically, may be positioned on one or both sides of the positive electrode current collector. The positive electrode active material layer may have a single layer or a multilayer structure of two or more layers. The above-described positive electrode active material includes a lithium nickel-based oxide containing nickel in an amount of 50 mol% to 70 mol%, 52 mol% to 68 mol%, 55 mol% to 65 mol%, or 57 mol% to 63 mol% of the total metal excluding lithium. In this case, the positive electrode active material may have superior structural and chemical stability at high temperatures compared to a positive electrode active material containing a lithium nickel-based oxide containing a high nickel content, thereby exhibiting superior thermal stability. In addition, gas generation and swelling phenomena caused by residual lithium byproducts (LiOH, Li2CO3, etc.) present on the surface of the positive electrode active material may be improved, thereby exhibiting superior life characteristics. The lithium nickel-based oxide may contain cobalt (Co) in an amount of 15 mol% or less, 5 mol% to 15 mol%, 7 mol% to 13 mol%, or 8 mol% to 12 mol% of the total metal excluding lithium. When cobalt is contained within the above range, it is possible to improve resistance characteristics and output characteristics while having cost advantages by including cobalt in a small amount. Specifically, the lithium nickel-based oxide may be represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 [Ni x1 Co y1 Mn z1 M 1 w1 ]O2 In the above chemical formula 1, the M 1 corresponds to a doping element that may or may not be optionally included in the above lithium nickel-based oxide. The above M 1 The doping element may be at least one selected from among W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, or may be at least one selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta and Nb. When the doping element is included, particle growth during sintering of the positive electrode active material may be promoted or crystal structure stability may be improved. In the above chemical formula 1, the 1+a1 may refer to the molar ratio of lithium (Li) in the lithium nickel-based oxide, and may be 0≤a1≤0.5, 0≤a1≤0.2, or 0≤a1≤0.1. When the above range is satisfied, the positive electrode active material may form a stable layered crystal structure. In the above chemical formula 1, x1 may mean the molar ratio of nickel among the total metal excluding lithium in the lithium nickel-based oxide particles, and may be 0.5≤x1≤0.7, 0.52≤x1≤0.68, 0.55≤x1≤0.65, or 0.57≤x1≤0.63. When the above range is satisfied, the manufactured lithium secondary battery may have excellent high-temperature storage characteristics, high-temperature lifespan characteristics, and thermal stability. In the above chemical formula 1, the y1 may mean the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <y1≤0.15, 또는 0<y1≤0.10, 또는 0<y1≤0.07일 수 있다. 상기 범위를 만족하는 경우, Co 함량을 낮춤으로써 비용적인 이점을 가지며, 양호한 저항 특성 및 출력 특성을 구현할 수 있고, 상대적으로 Mn의 비율을 높여 양극 활물질의 구조적 안정성을 향상시킬 수 있다. In the above chemical formula 1, z1 may mean the molar ratio of manganese among the total metal excluding lithium in the lithium nickel-based oxide particles, and 0 <z1≤0.4, 0.1≤z1≤0.4, 0.15≤z1≤0.4, 또는 0.2≤z1≤0.4일 수 있다. 상기 범위를 만족할 경우, 양극 활물질의 구조적 안정성을 향상시킬 수 있다. The above w1 is M of all metals except lithium in the lithium nickel oxide. 1 This represents the molar ratio of elements, and may be 0≤w1≤0.2, 0≤w1≤0.15, or 0≤w1≤0.1. When the above range is satisfied, it may play a role in promoting particle growth during sintering of the positive electrode active material or improving crystal structure stability. Additionally, the lithium nickel-based oxide may be a single particle. Specifically, when the lithium nickel-based oxide is a secondary particle, particle breakage increases during electrode manufacturing, and internal cracks occur more frequently due to volume expansion / contraction of the primary particles during charge / discharge, which may reduce the effect of improving high-temperature life characteristics and high-temperature storage characteristics. Accordingly, when using the lithium nickel-based oxide, which is a single particle type particle as described above, the particle strength is higher than that of the existing secondary particle type lithium nickel-based oxide in which more than 30 primary particles are aggregated, so that the particle breakage is less during rolling. In addition, in the case of the lithium nickel-based oxide, which is a single particle type particle according to the present invention, 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, the lithium secondary battery according to the present invention can have excellent thermal stability by using lithium nickel oxide, which is a single particle type particle, and thus, particle breakage and occurrence of internal cracks in the particles during charge and discharge can be reduced, and thus, high-temperature life characteristics and high-temperature storage characteristics can be improved. Meanwhile, the average particle diameter (D) of the positive electrode active material 50 ) may be 1 ㎛ to 8 ㎛, 2 ㎛ to 7 ㎛, 2.5 ㎛ to 6 ㎛, 3 ㎛ to 5 ㎛, or 3.5 ㎛ to 4.5 ㎛. When the above range is satisfied, side reactions with the electrolyte can be minimized while preventing an increase in resistance and a decrease in output characteristics, and thus, high-temperature life characteristics and high-temperature storage characteristics can be excellent. The above-mentioned positive electrode active material layer may contain the positive electrode active material in an amount of 90 wt% to 99 wt%, 92 wt% to 99 wt%, or 94 wt% to 98 wt%. When the above range is satisfied, the energy density and capacity characteristics of the lithium secondary battery can be improved. 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 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, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The positive electrode conductive material may typically be included in an amount of 0.1 to 30 wt%, 0.3 to 20 wt%, 0.5 to 10 wt%, 0.7 to 5 wt%, or 1 to 3 wt% based on the total weight of the positive electrode active material layer. The above positive electrode binder serves to improve adhesion between positive electrode particles and adhesion between the positive electrode and the positive electrode current collector, and specific examples thereof include a fluororesin 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 carboxymethyl cellulose (CMC), starch, hydroxypropyl 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 0.1 to 30 wt%, 0.3 to 20 wt%, 0.5 to 10 wt%, 0.7 to 5 wt%, or 1 to 3 wt% based on the total weight of the positive electrode active material layer. Meanwhile, the positive electrode can be manufactured by applying positive electrode slurry to one or both sides of a long sheet-shaped positive electrode collector, removing the solvent of the positive electrode slurry through a drying process, and then rolling. Meanwhile, a positive electrode including a non-coated region can be manufactured by not applying the positive electrode slurry to some areas of the positive electrode collector, for example, one end of the positive electrode collector, when applying the positive electrode slurry. Additionally, the positive electrode slurry can be manufactured by dispersing the positive electrode active material in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. 2) Cathode The above negative electrode may include a positive electrode active material. Specifically, the negative electrode may include a negative electrode current collector; and a negative electrode active material layer positioned on the negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material. The 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 negative electrode current collector can typically have a thickness of 3 to 500 μm. In addition, the negative electrode current collector, like the positive electrode current collector, can form fine irregularities on the surface of the negative electrode 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, sheet, foil, net, porous body, foam, or 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 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 negative electrode may include graphite as a negative electrode active material. In this case, the volume change of the negative electrode active material during charge and discharge is less than that of a silicon-based active material, so the life characteristics may be excellent. Specifically, the graphite may be at least one selected from the group consisting of artificial graphite and natural graphite, and preferably may be a combination of artificial graphite and natural graphite. When the above negative electrode includes artificial graphite and natural graphite, the artificial graphite and the natural graphite may be included in a weight ratio of 6.5:3.5 to 9.5:0.5, 7:3 to 9:1, or 7.5:2.5 to 8.5:1.5. When the above range is satisfied, the capacity characteristics may be improved while the output characteristics and life characteristics may be excellent. The above negative active material may be included in an amount of 80 wt% to 99 wt%, 85 wt% to 98 wt%, or 90 wt% to 97 wt% based on the total weight of the negative active material layer. When the above range is satisfied, sufficient capacity characteristics can be realized. 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-described 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 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, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. 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 0.1 to 20 wt%, 0.2 to 10 wt%, 0.3 to 5 wt%, or 0.4 to 2 wt% based on the total weight of the negative electrode active material layer. The above negative electrode 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. The above negative electrode binder may be included in an amount of 0.1 to 30 wt%, 0.3 to 20 wt%, 0.5 to 10 wt%, 0.7 to 5 wt%, or 1 to 3 wt% based on the total weight of the negative electrode active material layer. The above negative electrode active material layer may optionally further include a thickener. The thickener may be any thickener used in conventional lithium secondary batteries, and an example thereof includes carboxymethyl cellulose (CMC). The thickener may be included in an amount of 0.1 to 10 wt%, 0.3 to 8 wt%, 0.5 to 5 wt%, 0.7 to 3 wt%, or 1 to 2 wt% based on the total weight of the negative electrode active material layer. The above negative electrode can be manufactured according to a conventional negative electrode manufacturing method. For example, the negative electrode can be manufactured by mixing a negative electrode active material, a negative electrode conductive material, and / or a negative electrode conductive material in a negative electrode solvent to manufacture a positive electrode slurry, applying the negative electrode slurry onto a negative electrode current collector, and drying and rolling. The cathode solvent may include at least one selected from the group consisting of distilled water, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate dispersion of the components of the cathode slurry. The solid content of the above cathode slurry may be 30 wt% to 80 wt%, specifically 40 wt% to 70 wt%. Alternatively, the negative electrode may be manufactured by casting the negative electrode slurry onto a separate support, then peeling the film from the support and laminating the resulting film onto a negative electrode current collector. 3) Membrane The above separator is interposed between the anode and the cathode. The above separator is interposed between the positive and negative electrodes to separate the negative and positive electrodes and provide a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries may be used without particular limitation. 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. (2) Electrolyte The electrolyte according to the present invention may include 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 include at least one selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2, preferably LiPF6. The concentration of the lithium salt may be 0.1 to 3.0 M, preferably 0.1 to 2.0 M, and more preferably 0.5 to 1.5 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so that it can exhibit excellent electrolyte performance, and lithium ions can move effectively. The organic solvent mentioned above is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery can be minimized. Specifically, the organic solvent may include at least one selected from the group consisting 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. Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof. The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent having a high dielectric constant and thus can easily dissociate a lithium salt in an electrolyte. Specifically, the cyclic carbonate-based organic solvent may be a non-fluorinated saturated cyclic carbonate-based organic solvent. The cyclic carbonate-based organic solvent may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and more specifically, may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically, may include ethylene carbonate (EC). In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may specifically be a non-fluorinated linear carbonate. The linear carbonate-based solvent may include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and more specifically, may include at least one selected from the group consisting of ethylmethyl carbonate (EMC) and diethyl carbonate (DEC), and more specifically, may include ethylmethyl carbonate (EMC). The above organic solvent may be a mixture of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. At this time, the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed in a volume ratio of 5:95 to 40:60, or a volume ratio of 10:90 to 38:62, or a volume ratio of 25:75 to 35:65. When the mixing ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent satisfies the above range, high dielectric constant and low viscosity characteristics can be simultaneously satisfied, and excellent ionic conductivity characteristics can be implemented. In addition, the organic solvent may further include at least one carbonate organic solvent selected from the group consisting of the cyclic carbonate organic solvent and the linear carbonate organic solvent, and at least one ester organic solvent selected from the group consisting of the linear ester organic solvent and the cyclic ester organic solvent, in order to produce an electrolyte having high ionic conductivity. The linear ester organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. In addition, the cyclic ester organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. Meanwhile, the organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes as needed. For example, at least one organic solvent among an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent may be additionally included. As the above ether solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto. The above glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and is a solvent with low reactivity with metals, and may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto. The above nitrile solvent may be at least one selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto. Meanwhile, in addition to the electrolyte components, the electrolyte may additionally include additives for the purpose of improving the life characteristics of the battery, suppressing battery capacity reduction, and improving the discharge capacity of the battery. The above additive may include, for example, at least one additive selected from the group consisting of non-fluorine-based unsaturated cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone-based compounds, sulfate-based compounds, borate-based compounds, nitrile-based compounds, benzene-based compounds, amine-based compounds, silane-based compounds, and lithium salt-based compounds different from the lithium salt included in the electrolyte. Specifically, the 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, One or more compounds 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) may be mentioned. The above 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, the low-temperature output of the battery, high-temperature storage characteristics, and high-temperature lifespan characteristics can be improved, and side reactions within the electrolyte can be reduced and the additives can be suppressed from existing as unreacted substances. (3) Battery case The above battery case can serve to accommodate the electrode assembly and the electrolyte. Specifically, the battery case is intended to house an electrode assembly, inject an electrolyte, and then seal it. It is manufactured from a material having a predetermined flexibility that allows a housing to be formed. There is no limitation on its shape, but it may preferably be cylindrical, coin-shaped, square, or pouch-shaped. The upper case and the lower case constituting the battery case may be independent members, or may be substantially one member with one end connected. The outer shape of the battery case may be manufactured in various ways, and the present invention does not limit this. For example, the battery case may be a square battery case. The square battery case has the advantage of being in the form of a square metal can, being able to be stacked with a high degree of integration, and having a small width relative to its length. The above square battery case has an opening formed at the top and can be made of a conductive metal material such as aluminum or steel, and the square battery case can accommodate an electrode assembly and an electrolyte in an internal space through the top opening of the battery can, and a top cap can be welded to the top opening to seal the battery case. Meanwhile, the lithium secondary battery of the present invention may have a charge cut-off voltage of 4.3 V or higher, specifically 4.35 V or higher, and more specifically 4.4 V or higher. In this case, it is possible to achieve excellent energy density and improved high-temperature lifespan performance and high-temperature storage performance equivalent to that of a cathode active material containing a high nickel content. Meanwhile, the lithium secondary battery may have a nominal voltage of 3.68 V or higher, preferably 3.68 V to 3.80 V, and more preferably 3.69 V to 3.75 V. At this time, the nominal voltage refers to the average voltage value during discharge of the lithium secondary battery. Since the energy density of the lithium secondary battery is calculated by the product of the average voltage and the average current during discharge, the energy density increases when the nominal voltage is high. The nominal voltage of a conventional lithium secondary battery using a lithium nickel cobalt manganese oxide as a positive electrode active material was at the level of 3.6 V, but in the present invention, the charge cut-off voltage is increased to make the nominal voltage 3.68 V or higher, thereby enabling high energy density to be implemented. 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, such as 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 devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. Examples and Comparative Examples Example 1 <Electrode assembly manufacturing> A cathode slurry was prepared by mixing a cathode active material, a binder, and a conductive agent in a weight ratio of 97:1.8:1.2 in an N-methylpyrrolidone solvent. After that, the cathode slurry was applied to one side of an aluminum current collector with a thickness of 12 μm, dried, and rolled to prepare a cathode. At this time, the cathode active material was Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2, PVDF was used as the binder, and carbon nanotubes were used as the conductive material. A negative electrode slurry was prepared by mixing a negative electrode active material, a binder, a conductive agent, and a thickener in distilled water at a weight ratio of 96.15:2.3:0.5:1.05. The negative electrode slurry was then applied to one surface of a 7.8 μm thick copper current collector, dried, and rolled to a porosity of 30% to prepare a negative electrode. At this time, the negative electrode active material was artificial graphite and natural graphite, the binder was styrene-butadiene rubber (SBR), the conductive agent was Super C65, and the thickener was carboxymethyl cellulose (CMC). An electrode assembly was manufactured by interposing a porous polyethylene separator between the cathode and anode manufactured above and winding the membrane. At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2 , and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing An electrolyte was prepared by adding 0.5 wt% of vinylene carbonate (VC), 0.5 wt% of propane sultone (PS), 1 wt% of ethylene sulfate (ESa), 1 wt% of lithium difluorophosphate, 0.2 wt% of LiBF4 as additives to an organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7, and adding 1.0 M of LiPF6. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 303.19 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.813. Example 2 <Electrode assembly manufacturing> An electrode assembly was manufactured using the same method as in Example 1 above. At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2 , and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 297.87 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.813. Example 3 <Electrode assembly manufacturing> An electrode assembly was manufactured using the same method as in Example 1 above. At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2 , and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 292.55 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.813. Example 4 <Electrode assembly manufacturing> Li[Ni 0.62 Co 0.06 Mn 0.32 ] An electrode assembly was manufactured in the same manner as in Example 1, except that a positive electrode active material having a composition of O2 was used. At this time, the porosity of the positive electrode is 21.7%, and the loading amount is 4.33 mAh / cm 2, and the porosity of the cathode was 26.1%. At this time, the N / P ratio of the cathode and the anode was 107.1, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 319.15 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.830. Example 5 <Electrode assembly manufacturing> An electrode assembly was manufactured using the same method as in Example 1 above. At this time, the porosity of the positive electrode is 19.1%, and the loading amount is 4.28 mAh / cm 2 , and the porosity of the cathode was 24.7%. At this time, the N / P ratio of the cathode and the anode was 105.9, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 319.15 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E) of the ratio (S) A / S E )in S u was 0.820. Example 6 In the above Example 1, 1.2 M LiPF6 was dissolved in an organic solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 2:7:1, instead of the electrolyte used, and then, as additives, 0.3 wt% of vinylethylene carbonate (VEC), 0.5 wt% of vinylene carbonate, 0.5 wt% of propane sultone (PS), 1.0 wt% of ethylene sulfate (ESa), 0.8 wt% of lithium difluorophosphate (LiDFP, product name: SLO 7), 0.5 wt% of lithium oxalyldifluoroborate (LiODFB), 0.1 wt% of propargyl 1Himidazole-1-carboxylate (HS02, CAS 83395-38-4), and lithium bis(fluorosulfonyl)imide (LiFSI, product name: A lithium secondary battery was manufactured in the same manner as in Example 1, except that an electrolyte was used by adding 0.5 wt% of SL06), 0.5 wt% of fluoroethylene carbonate (FEC), and 0.5 wt% of trimethylsilyl phosphate (TMSPa). At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2 , and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Comparative Example 1 <Electrode assembly manufacturing> An electrode assembly was manufactured using the same method as in Example 1 above. At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2, and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 319.15 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.813. Comparative Example 2 <Electrode assembly manufacturing> An electrode assembly was manufactured using the same method as in Example 1 above. At this time, the porosity of the positive electrode is 21.35%, and the loading amount is 4.03 mAh / cm 2 , and the porosity of the cathode was 28.01%. At this time, the N / P ratio of the cathode and the anode was 107.26, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 276.60 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary batteryE ) of the ratio (S) A / S E )in S u was 0.813. Comparative Example 3 <Electrode assembly manufacturing> Li[Ni 0.65 Co 0.15 Mn 0.2 ] An electrode assembly was manufactured in the same manner as in Example 1, except that a positive electrode active material having a composition of O2 was used. At this time, the porosity of the positive electrode is 24.6%, and the loading amount is 4.02 mAh / cm 2 , and the porosity of the cathode was 26.9%. At this time, the N / P ratio of the cathode and the anode was 108.6, and the electrode assembly had a jelly-roll shape in which the cathode, separator, and anode were sequentially laminated and wound. Electrolyte manufacturing The electrolyte was prepared in the same manner as in Example 1. <Lithium secondary battery manufacturing> After positioning the electrode assembly manufactured above inside a square battery case, 303.19 g of the electrolyte manufactured above was injected into the case and sealed to manufacture a lithium secondary battery. At this time, the volume (S) of the electrode assembly in the manufactured lithium secondary battery A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E )in S u was 0.830. Experimental Example 1 - EFF Index Evaluation The EFF index defined by Equation 1 below was measured for the lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1 below. [Formula 1] In the above equation 1, R E[Unit: g] refers to the weight of the remaining electrolyte contained in the lithium secondary battery after activation, and S U is the volume (S) of the electrode assembly A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E ) means, N C [Unit: Ah] refers to the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C. (1) R E measurement For each of the lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3, activation was performed by performing (1) a step of charging the lithium secondary battery to 3% SOC under a constant current condition of 0.2 C at 55°C, (2) a step of charging the lithium secondary battery to 17% SOC under a constant current condition of 1.0 C at 55°C, and (3) a step of charging the lithium secondary battery to 60% SOC under a constant current condition of 1.0 C at 55°C. After this, each activated lithium secondary battery was disassembled and the weight of the remaining electrolyte (R E ) was measured. Specifically, the weight (R) of the remaining electrolyte included in the lithium secondary battery after the activation E ) is, (1) the weight (M) of the activated lithium secondary battery before disassembling the activated lithium secondary battery. L ), (2) a step of disassembling the activated lithium secondary battery to remove the electrolyte present in the battery case, (3) a step of immersing the battery case and electrode assembly in dimethyl carbonate, a solvent, to remove the electrolyte present on the surface of the battery case, the surface of the electrode assembly, and the internal pores, and then drying the battery case and electrode assembly, (4) a step of measuring the weight (M) of the dried battery case C ) and the weight (M) of the dried electrode assembly A ) after the step of measuring, the measured M L, M C , M A It was measured by substituting it into Equation A below. [Formula A] R E = M L -M C -M A The results are shown in Table 1 below. (2) N C measurement The lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were each charged to 4.35 V with a 0.05 C cut under constant current / constant voltage conditions of 0.33 C at 25°C, and then discharged to 2.0 V under constant current conditions of 0.33 C, thereby activating them. Next, the capacity (N) when the lithium secondary battery was charged from 2.5 V to 4.35 V at 0.33 C at 25 °C and then discharged from 4.4 V to 2.5 V at 0.33 C at 25 °C C ) was measured, and the results are shown in Table 1 below. (3) S U measurement For each lithium secondary battery manufactured in the above Examples 1 to 6 and Comparative Examples 1 to 3, S U is the volume of the electrode assembly (S A ) and the volume (S) of the lithium secondary battery E ) are measured respectively, and the above S A Wow S E Rain of S A / S E ) was measured by calculating the above S A and S E Each was measured using the following methods. The results are shown in Table 1 below. The volume (S) of the above lithium secondary battery E ) was obtained by the following formula B. The volume (S) of the lithium secondary battery according to the following formula B E) is obtained by assuming that the shape of a lithium secondary battery including a square battery case is a rectangular parallelepiped. [Formula B] S E = (Thickness of lithium secondary battery) × (Length of lithium secondary battery) × (Width of lithium secondary battery) In the above formula B, the thickness of the lithium secondary battery means a distance measured along the thickness direction of the lithium secondary battery based on the external shape of the lithium secondary battery, the length of the lithium secondary battery means a distance measured along the longitudinal direction of the lithium secondary battery based on the external shape of the lithium secondary battery, and the width of the lithium secondary battery means a distance measured along a direction perpendicular to the longitudinal direction of the lithium secondary battery based on the external shape of the lithium secondary battery. The volume (S) of the above electrode assembly A ) was obtained by the following formula C. [Formula C] S A =(volume of anode)+(volume of cathode)+(volume of membrane) In the above formula C, the volume of the anode, the volume of the cathode, and the volume of the separator were measured based on the external shape of the anode, cathode, or separator, without excluding the volume of the pores included in the anode, cathode, or separator. R E [g]S U N C [Ah]R E / N C[g / Ah]EFF Index [g / Ah]Example 12850.8131172.4361.98Example 22800.8131172.3931.95Example 32750.8131172.3501.91Example 43000.830133.52.2471.87Example 53000.820127.82.3471.92Example 62850.8131172.4361.98Comparative Example 13000.8131172.5642.08Comparative Example 22600.8131172.2221.81Comparative Example 32850.830108.52.6272.18 Experimental Example 2: Evaluation of High-Temperature Storage Characteristics The lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were charged to 100% of SOC under CC / CV, 0.33C conditions at 25°C, and then stored at 60°C for 12 weeks. The capacity retention rate and resistance increase rate of each lithium secondary battery were measured. The specific measurement method is as follows. (1) Capacity retention rate Before storing at 60°C for 12 weeks, the lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were charged to 4.25 V with a 0.05 C cut under CC / CV, 0.33 C conditions at 25°C and discharged to 2.0 V under CC, 0.33 C for 3 cycles, and the discharge capacity in the 3rd cycle was measured and used as the initial discharge capacity. After being stored at 60°C for 12 weeks, the lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were charged to 4.25 V with a 0.05 C cut under CC / CV, 0.33 C conditions at 25°C and discharged to 2.0 V under CC, 0.33 C conditions three times, and the discharge capacity in the third cycle was measured and used as the discharge capacity after being stored at 60°C for 12 weeks. The initial discharge capacity measured above was compared with the discharge capacity after storage at 60°C for 12 weeks, and the capacity retention rate was evaluated according to the following formula, and the results are shown in Table 2 below. Capacity retention (%) = (Discharge capacity after 12 weeks of storage at 60℃ / Initial discharge capacity) Х 100 (2) Resistance increase rate The lithium secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 3 were charged to 4.25 V with a 0.05 C cut under CC / CV, 0.33 C conditions at 25°C and discharged to 2.0 V under CC, 0.33 C conditions three times, and then the discharge capacity of the third cycle was set to 50% SOC under CC / CV, 0.33 C conditions, and discharged for 30 seconds with a 2.5 C current. The resistance was measured based on the voltage drop difference at this time, which was used as the initial resistance. After storing at 60°C for 12 weeks, the resistance was measured using the same method, which was used as the final resistance, and the resistance increase rate was calculated using the following equation. The results are shown in Table 2 below. Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) Х 100 Capacity retention rate [%] Resistance increase rate [%] Example 195.89 19.77 Example 296.26 17.15 Example 396.26 16.25 Example 494.66 23.65 Example 594.77 24.89 Example 695.50 22.31 Comparative example 193.23 32.34 Comparative example 293.52 25.47 Comparative example 394.11 26.84 Referring to Table 2 above, it can be confirmed that the lithium secondary batteries manufactured in Examples 1 to 6 have superior capacity retention and resistance increase rates after being stored at 60°C for 12 weeks compared to the lithium secondary batteries manufactured in Comparative Examples 1 to 3. In addition, although Example 6 used a different electrolyte from Example 1, it can be understood that the high-temperature storage characteristics are excellent when the EFF value defined by Equation 1 satisfies 1.82 to 2.06 from the fact that the capacity retention and resistance increase rates after being stored at 60°C for 12 weeks are superior to the lithium secondary batteries manufactured in Comparative Examples 1 to 3 even when a different electrolyte is applied.

Claims

1. An electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; electrolyte; and A battery case including an internal space for storing the electrode assembly and the electrolyte; The above positive electrode includes a positive electrode active material, The above positive electrode active material includes a lithium nickel oxide containing 50 to 70 mol% of nickel among all metals excluding lithium, A lithium secondary battery having an EFF (Electrolyte Filing Factor) index (unit: g / Ah) defined by the following equation 1 of 1.82 to 2.

06. [Formula 1] In the above equation 1, R E [Unit: g] refers to the weight of the remaining electrolyte contained in the lithium secondary battery after activation. S U is the volume (S) of the electrode assembly A ) and the volume (S) of the lithium secondary battery E ) of the ratio (S) A / S E ) means, N C [Unit: Ah] refers to the capacity when the lithium secondary battery is discharged from 4.4 V to 2.5 V at 0.33 C at 25°C.

2. In paragraph 1, The above R E A lithium secondary battery weighing 265 to 295 g.

3. In paragraph 1, S above U A lithium secondary battery having an oxidation number (I) of 0.70 to 0.

95.

4. In paragraph 1, The above N C A lithium secondary battery having a capacity of 90 to 150 Ah.

5. In paragraph 1, The above N C The above R for E The ratio of (R) E / N C )[Unit: g / Ah] is 2.00 to 3.30, lithium secondary battery.

6. In paragraph 1, The volume (S) of the above electrode assembly A ) is a lithium secondary battery having a capacity of 0.3 L to 1.35 L.

7. In paragraph 1, The volume (S) of the above lithium secondary battery E ) is a lithium secondary battery having a capacity of 0.4 L to 1.5 L.

8. In paragraph 1, A lithium secondary battery, wherein the lithium nickel-based oxide contains cobalt (Co) in an amount of 15 mol% or less among all metals excluding lithium.

9. In paragraph 1, A lithium secondary battery, wherein the lithium nickel-based oxide is represented by the following chemical formula 1. [Chemical Formula 1] Li 1+a1 [Ni x1 Co y1 Mr z1 M 1 w1 ]O2 In the above chemical formula 1, 0≤a1≤0.5, 0.5≤x1≤0.7, 0 <y1≤0.15, 0<z1≤0.4, 0≤w1≤0.2이고, M 1 is at least one doping element selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo.

10. In paragraph 1, A lithium secondary battery, wherein the lithium nickel oxide is a single particle.

11. In paragraph 1, The above lithium secondary battery is a lithium secondary battery having a charge cut-off voltage of 4.3 V or higher.

12. In paragraph 1, The above lithium secondary battery is a lithium secondary battery having a nominal voltage of 3.68 V or higher.

13. In paragraph 1, A lithium secondary battery, wherein the negative electrode comprises graphite as a negative electrode active material.

14. In paragraph 1, The above battery case is a square battery case, a lithium secondary battery.

15. In paragraph 1, The above electrode assembly is a lithium secondary battery in which a positive electrode, a separator, and a negative electrode are sequentially laminated and wound in one direction.

Images