Lithium secondary battery

Abstract

The present invention relates to a lithium secondary battery comprising: a positive electrode; a negative electrode: a separator between the positive electrode and the negative electrode; and an electrolyte, wherein the negative electrode comprises: a negative electrode current collector layer; and a negative electrode active material layer comprising a negative electrode active material layer composition and provided on one side or both sides of the negative electrode current collector layer, wherein the negative electrode active material layer composition comprises a carbon-based active material, comprises, based on 100 parts by weight of the carbon-based active material, 1 part by weight to 50 parts by weight of artificial graphite having an initial capacity of 330 mAh / g or more, and has an NP ratio of 110 or more.

Description

lithium secondary battery

[0001] This application claims the benefit of Korean Patent Application No. 10-2023-0159140, filed with the Korean Intellectual Property Office on November 16, 2023, the entire contents of which are incorporated herein by reference.

[0002] This application relates to a lithium secondary battery.

[0003] Due to the rapid increase in fossil fuel use, the demand for alternative or clean energy is increasing, and as part of this, the most actively researched field is power generation and storage using electrochemical reactions.

[0004] A representative example of an electrochemical device that currently utilizes this electrochemical energy is the secondary battery, and its application area is gradually expanding.

[0005] With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and voltage, long cycle life, and low self-discharge rates, are commercialized and widely used. Furthermore, active research is being conducted on methods for manufacturing high-density electrodes with even higher energy density per unit volume as electrodes for these high-capacity lithium secondary batteries.

[0006] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode includes a negative electrode active material that inserts and deintercalates lithium ions from the positive electrode. Silicon particles with a high discharge capacity can be used as the negative electrode active material.

[0007] In particular, due to the recent demand for high-density energy batteries, active research is being conducted on methods to increase capacity by using silicon-based compounds, such as Si / C or SiOx, as anode active materials, which have a capacity more than 10 times greater than graphite-based materials. However, in the case of silicon-based compounds, which are high-capacity materials, compared to the graphite used in the past, the capacity characteristics themselves are excellent, but the volume rapidly expands during the charging process, which cuts off the conductive path, deteriorating the battery characteristics, and consequently, the capacity drops from the beginning. In addition, when the silicon-based anode is repeated, lithium ions are not uniformly charged in the depth direction of the anode, and the reaction proceeds on the surface, accelerating surface degradation, so performance improvement in terms of the battery cycle is necessary.

[0008] Accordingly, in order to solve the above problems when using silicon-based compounds as negative electrode active materials, various methods are being discussed, such as a method of controlling the driving potential, a method of additionally coating a thin film on the active material layer, a method of suppressing the volume expansion itself such as a method of controlling the particle size of the silicon-based compound, or the development of a binder that will control the volume expansion of the silicon-based compound to prevent the conductive path from being cut off. In addition, research is also being conducted to supplement the life characteristics of silicon-based negative electrodes by limiting the proportion of silicon-based active materials used during initial charge and discharge and providing a reservoir role through a method of prelithiating the silicon-based active material layer.

[0009] However, the above methods may actually lower the performance of the battery, so their application is limited, and there are still limitations in the commercialization of negative electrode batteries with a high content of silicon compounds.

[0010] While artificial graphite has a lower capacity than silicon-based anodes, recent research has confirmed its superior cell characteristics. This has led to increased use of artificial graphite while reducing the use of natural graphite. However, from a cost perspective, artificial graphite has the disadvantage of being more expensive to process than natural graphite, as it requires coke to be calcined and graphitized.

[0011] Therefore, development of lithium secondary batteries that can reduce costs and provide performance equivalent to or superior to existing batteries is continuously underway.

[0012] <Prior Art Literature>

[0013] (Patent Document 1) Japanese Patent Publication No. 2009-080971

[0014] This application has discovered through research a cell that can use a carbon-based active material as a negative electrode, while reducing the amount of artificial graphite used in terms of cost, and at the same time, can implement cell characteristics that are the same or superior to those of existing cells even when the amount of artificial graphite is reduced.

[0015] Accordingly, the present application seeks to provide a lithium secondary battery using an active material of a specific composition in the negative electrode while controlling the NP ratio.

[0016] One embodiment of the present specification provides a lithium secondary battery comprising: a positive electrode; a negative electrode; a separator described between the positive electrode and the negative electrode; and an electrolyte, wherein the negative electrode comprises: a negative electrode current collector layer; and a negative electrode active material layer comprising a negative electrode active material layer composition provided on one or both sides of the negative electrode current collector layer, wherein the negative electrode active material layer composition comprises a carbon-based active material, and comprises 1 part by weight or more and 50 parts by weight or less of artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the carbon-based active material, and has an NP Ratio of 110 or more.

[0017] Previously, as the superior cell characteristics of artificial graphite were confirmed, the amount of natural graphite used was reduced while the amount of artificial graphite used was increased. However, this had the problem of being expensive due to the high processing cost in terms of cost and mass production.

[0018] Accordingly, in order to solve the problems of cost and mass production, the present application designed a cell by increasing the amount of natural graphite while reducing the amount of artificial graphite used, and solved the resulting problem by adjusting the NP Ratio.

[0019] That is, in the case of the lithium secondary battery according to the present application, the artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of carbon-based active material is included in an amount of 1 part by weight or more and 50 parts by weight or less, and the NP Ratio is adjusted to 110 or more, so that a large amount of residual negative electrode can be taken, and thus, even if the artificial graphite is used in the above range, cell degradation is not accelerated, and thus, life characteristics can be secured.

[0020] Figure 1 is a diagram showing a laminated structure of a lithium secondary battery according to one embodiment of the present application.

[0021] <Explanation of symbols>

[0022] 10: Negative current collector layer

[0023] 20: Negative active material layer

[0024] 30: Membrane

[0025] 40: Positive active material layer

[0026] 50: Positive current collector layer

[0027] 100: Negative

[0028] 200: Bipolar

[0029] Before explaining the present invention, some terms are first defined.

[0030] When a part of this specification is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0031] In this specification, ‘p to q’ means a range of ‘p or more and q or less.’

[0032] In this specification, "specific surface area" is measured by the BET method, and specifically, is calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mino II of BEL Japan. That is, in this application, the BET specific surface area may mean the specific surface area measured by the above measurement method.

[0033] In this specification, "Dn" means particle size distribution, and means the particle size at the n% point of the cumulative distribution of particle numbers according to particle size. That is, D50 is the particle size (average particle size, center particle size) at the 50% point of the cumulative distribution of particle numbers according to particle size, D90 is the particle size at the 90% point of the cumulative distribution of particle numbers according to particle size, and D10 is the particle size at the 10% point of the cumulative distribution of particle numbers according to particle size. Meanwhile, the particle size distribution can be measured using the laser diffraction method. Specifically, after the target powder is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) and the difference in diffraction pattern according to particle size is measured when the particles pass through a laser beam, thereby calculating the particle size distribution.

[0034] As used herein, the term "a polymer comprises a monomer as a monomer unit" means that the monomer participates in a polymerization reaction and is included as a repeating unit within the polymer. As used herein, "a polymer comprises a monomer" is interpreted to mean that the polymer comprises the monomer as a monomer unit.

[0035] In this specification, the term 'polymer' is understood to be used in a broad sense including copolymers unless 'homopolymer' is specified.

[0036] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are polystyrene-converted molecular weights measured by gel permeation chromatography (GPC) using monodisperse polystyrene polymers (standard samples) of various degrees of polymerization commercially available for molecular weight measurement as standard materials. In this specification, molecular weight means weight average molecular weight unless otherwise specified.

[0037] Hereinafter, the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily practice it. However, the present invention can be implemented in various different forms and is not limited to the following description.

[0038] One embodiment of the present specification provides a lithium secondary battery comprising: a positive electrode; a negative electrode; a separator described between the positive electrode and the negative electrode; and an electrolyte, wherein the negative electrode comprises: a negative electrode current collector layer; and a negative electrode active material layer comprising a negative electrode active material layer composition provided on one or both sides of the negative electrode current collector layer, wherein the negative electrode active material layer composition comprises a carbon-based active material, and comprises 1 part by weight or more and 50 parts by weight or less of artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the carbon-based active material, and has an NP Ratio of 110 or more.

[0039] In the case of a lithium secondary battery according to the present application, an artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of a carbon-based active material is included in an amount of 1 part by weight or more and 50 parts by weight or less, and the NP Ratio is adjusted to 110 or more, so that a large amount of residual negative electrode can be taken, and thus, even if artificial graphite is used in the above range, cell degradation is not accelerated, and thus, a lifespan characteristic can be secured.

[0040] FIG. 1 is a diagram showing a laminated structure of a lithium secondary battery according to one embodiment of the present application. Specifically, a lithium secondary battery negative electrode (100) including a negative electrode active material layer (20) on one surface of a negative electrode current collector layer (10) can be confirmed, and a lithium secondary battery positive electrode (200) including a positive electrode active material layer (40) on one surface of a positive electrode current collector layer (50) can be confirmed, and it is shown that the lithium secondary battery negative electrode (100) and the lithium secondary battery positive electrode (200) are formed in a laminated structure with a separator (30) interposed therebetween.

[0041] Below, the lithium secondary battery of the present invention is described in more detail.

[0042] In the present application, the negative electrode includes a negative electrode current collector layer; and a negative electrode active material layer including a negative electrode active material layer composition provided on one or both sides of the negative electrode current collector layer.

[0043] In the present application, the negative electrode active material layer composition may include a carbon-based active material, and may include 1 part by weight or more and 50 parts by weight or less of artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the carbon-based active material.

[0044] In another embodiment, the negative electrode active material layer composition may include a carbon-based active material, and may include 1 part by weight or more and 50 parts by weight or less, specifically 10 parts by weight or more and 50 parts by weight or less, and more specifically 30 parts by weight or more and 50 parts by weight or less of artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the carbon-based active material.

[0045] In one embodiment of the present application, the carbon-based active material is, as a representative example, natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotubes, fullerene, or activated carbon, and can be used without limitation as long as it is commonly used in carbon materials for lithium secondary batteries, and specifically, can be used by processing it into a spherical or dot-shaped shape.

[0046] The present application has the characteristic that, by adjusting the NP Ratio described below to 110 or more, a large amount of residual cathode can be taken, so that even if artificial graphite is used within the above range, cell degradation is not accelerated, and thus life characteristics can be secured.

[0047] In the present application, the artificial graphite may have an initial capacity of 330 mAh / g or more.

[0048] In another embodiment, the artificial graphite may have an initial capacity of 330 mAh / g or more, preferably 335 mAh / g or more, and may have an initial capacity of 450 mAh / g or less, preferably 400 mAh / g or less.

[0049] The artificial graphite according to the present application has an initial capacity within the above range, and is a material with a high initial capacity, unlike other types of artificial graphite, such as mesocarbon. In this case, it exhibits superior capacity characteristics compared to general artificial graphite.

[0050] In one embodiment of the present application, a lithium secondary battery is provided in which the carbon-based active material includes artificial graphite and natural graphite having an initial capacity of 330 mAh / g or more, and a weight ratio of the artificial graphite to the natural graphite based on 100 parts by weight of the carbon-based active material is 1:99 to 50:50.

[0051] That is, in the case of the lithium secondary battery according to the present application, a carbon-based active material is used as the negative active material, and at the same time, artificial graphite and natural graphite satisfying a specific initial capacity are blended and used at the above ratio as described above. Specifically, although using 100% artificial graphite is superior in terms of resistance characteristics and lifespan characteristics, such artificial graphite is expensive and requires a lot of processing time, making it unsuitable for mass production. Accordingly, the main purpose of the present invention is to use natural graphite blended at the above ratio and to resolve the resulting performance degradation by controlling the NP Ratio.

[0052] In the present application, the artificial graphite and the natural graphite having an initial capacity of 330 mAh / g or more may be crystalline carbon (Graphite).

[0053] Carbon-based active materials can be divided into crystalline carbon (graphite) and amorphous carbon, and amorphous carbon can be further divided into hard carbon and soft carbon. The artificial graphite and natural graphite according to the present application are mainly characterized by the use of crystalline carbon (graphite).

[0054] The carbon-based active material according to the present application is a high-capacity negative electrode material compared to soft carbon or hard carbon, has excellent initial efficiency, and also has excellent cycle characteristics.

[0055] In one embodiment of the present application, a lithium secondary battery is provided, wherein the negative electrode active material layer composition further includes at least one selected from the group consisting of a silicon-based active material, a tin-based active material, a metal-based active material capable of being alloyed with lithium, lithium titanium oxide, and a lithium-containing nitride.

[0056] In particular, the present application provides that the negative electrode active material layer composition includes a carbon-based active material and a silicon-based active material, and the silicon-based active material may be included in an amount of 50 parts by weight or less based on 100 parts by weight of the negative electrode active material layer composition.

[0057] The present application provides that the negative electrode active material layer composition includes a carbon-based active material and a silicon-based active material, and the silicon-based active material may be included in an amount of 30 parts by weight or less, preferably 20 parts by weight or less, and may be included in an amount of 1 part by weight or more and 10 parts by weight or more, based on 100 parts by weight of the negative electrode active material layer composition.

[0058] The present application reduces the artificial graphite content in a carbon-based active material, which in turn causes some problems with reduced resistance and lifespan characteristics. Accordingly, the aforementioned problems can be resolved by mixing a carbon-based active material with a silicon-based active material or lithium titanium oxide in the negative electrode active material layer composition.

[0059] In one embodiment of the present application, the silicon-based active material is SiOx (x=0), SiOx (0 <x<2), SiC, 및 Si 합금으로 이루어진 군에서 선택되는 1 이상을 포함할 수 있다.

[0060] In one embodiment of the present application, the silicon-based active material is SiOx (0 <x<2), SiC, 및 Si 합금으로 이루어진 군에서 선택되는 1 이상을 포함하며, 상기 실리콘계 활물질 100 중량부 기준 SiOx (0<x<2)를 1 중량부 이상 포함할 수 있다.

[0061] In another embodiment, the silicon-based active material is SiOx (0 <x<2), SiC, 및 Si 합금으로 이루어진 군에서 선택되는 1 이상을 포함하며, 상기 실리콘계 활물질 100 중량부 기준 SiOx (0<x<2)를 1 중량부 이상, 30 중량부 이상 포함할 수 있으며, 99 중량부 이하 포함할 수 있다.

[0062] In another embodiment, the silicon-based active material is SiOx (0 <x<2)를 포함할 수 있다.

[0063] In another embodiment, the silicon-based active material is SiOx (0 <x<2)로 이루어질 수 있다.

[0064] In one embodiment of the present application, the negative electrode active material layer composition may include a negative electrode conductive material; and a negative electrode binder.

[0065] Traditionally, graphite compounds were used exclusively as anode active materials. However, with the increasing demand for high-capacity batteries, attempts to blend silicon-based active materials to increase capacity are increasing. However, graphite-based or silicon-based active materials can experience rapid volume expansion during charge / discharge, potentially damaging the conductive path formed within the anode active material layer.

[0066] Therefore, in one embodiment of the present application, the negative conductive material may include at least one selected from the group consisting of a dot-shaped conductive material, a planar conductive material, and a linear conductive material.

[0067] In one embodiment of the present application, the dot-shaped conductive material may be used to improve conductivity of the negative electrode, and refers to a dot-shaped or spherical conductive material having conductivity without causing chemical change. Specifically, the dot-shaped conductive material may be at least one selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivatives, and preferably may include carbon black in terms of implementing high conductivity and excellent dispersibility.

[0068] In one embodiment of the present application, the dot-shaped conductive material has a BET specific surface area of ​​40 m 2 / g or more than 70m 2 / g or less, preferably 45m 2 / g or more than 65m 2 / g or less, more preferably 50m 2 / g or more than 60m 2 / g can be less.

[0069] In one embodiment of the present application, the dot-shaped conductive material can satisfy a volatile matter content of 0.01% or more and 1% or less, preferably 0.01% or more and 0.3% or less, and more preferably 0.01% or more and 0.1% or less.

[0070] In particular, when the functional group content of the dot-shaped conductive material satisfies the above range, the functional groups present on the surface of the dot-shaped conductive material exist, so that when water is used as a solvent, the dot-shaped conductive material can be smoothly dispersed within the solvent. In particular, in the present invention, the functional group content of the dot-shaped conductive material can be reduced by using a specific silicon-based active material, thereby having an excellent effect in improving dispersibility.

[0071] In one embodiment of the present application, it is characterized by including a dot-shaped conductive material having a functional group content within the above range together with a silicon-based active material, and the functional group content can be controlled by adjusting the degree of heat treatment of the dot-shaped conductive material.

[0072] In one embodiment of the present application, the particle size of the dot-shaped conductive material may be 10 nm to 100 nm, preferably 20 nm to 90 nm, and more preferably 20 nm to 60 nm.

[0073] In one embodiment of the present application, the conductive material may include a planar conductive material.

[0074] The above-mentioned planar conductive material can improve conductivity by increasing planar contact between silicon particles within the cathode, and at the same time, suppress the disconnection of conductive paths due to volume expansion. The above-mentioned planar conductive material can be expressed as a plate-shaped conductive material or a bulk conductive material.

[0075] In one embodiment of the present application, the planar conductive material may include at least one selected from the group consisting of plate-shaped graphite, graphene, graphene oxide, and graphite flakes, and may preferably be plate-shaped graphite.

[0076] In one embodiment of the present application, the average particle diameter (D50) of the surface-shaped conductive material may be 2 μm to 7 μm, specifically 3 μm to 6 μm, and more specifically 3.5 μm to 5 μm. When the above range is satisfied, dispersion is easy without causing excessive viscosity increase of the negative electrode slurry due to sufficient particle size. Therefore, the dispersion effect is excellent when dispersion is performed using the same equipment and time.

[0077] In one embodiment of the present application, the surface-shaped conductive material provides a negative electrode composition having a D10 of 0.5 μm or more and 2.0 μm or less, a D50 of 2.5 μm or more and 3.5 μm or less, and a D90 of 6.5 μm or more and 15.0 μm or less.

[0078] In one embodiment of the present application, the planar conductive material may be a high-specific surface area planar conductive material having a high BET surface area; or a low-specific surface area planar conductive material.

[0079] In one embodiment of the present application, a high surface area surface conductive material or a low surface area surface conductive material may be used without limitation as the surface conductive material, but in particular, since the surface conductive material according to the present application may be affected to some extent by dispersion in electrode performance, it may be particularly preferable to use a low surface area surface conductive material that does not cause dispersion problems.

[0080] In one embodiment of the present application, the surface-shaped conductive material has a BET specific surface area of ​​0.25 m 2 / g can be more than that.

[0081] In another embodiment, the surface-shaped conductive material has a BET surface area of ​​1 m 2 / g or more than 500m 2 / g or less, preferably 5m 2 / g or more than 300m 2 / g or less, more preferably 5m 2 / g or more than 250m 2 / g can be less.

[0082] The planar conductive material according to the present application may be a planar conductive material with a high specific surface area; or a planar conductive material with a low specific surface area.

[0083] In another embodiment, the surface-shaped conductive material is a high surface area surface-shaped conductive material, and has a BET surface area of ​​50 m 2 / g or more than 500m 2 / g or less, preferably 80m 2 / g or more than 300m 2 / g or less, more preferably 100m 2 / g or more than 300m 2 / g can satisfy the range below.

[0084] In another embodiment, the surface-shaped conductive material is a low surface area surface-shaped conductive material, and has a BET surface area of ​​1 m 2 / g or more than 40m 2 / g or less, preferably 5m 2 / g or more than 30m 2 / g or less, more preferably 5m 2 / g or more than 25m 2 / g can satisfy the range below.

[0085] Other conductive materials may include linear conductive materials such as carbon nanotubes. The carbon nanotubes may be bundle-type carbon nanotubes. The bundle-type carbon nanotubes may include a plurality of carbon nanotube units. Specifically, the term "bundle type" herein refers to a secondary shape in the form of a bundle or rope, in which a plurality of carbon nanotube units are arranged in a substantially identical orientation with their longitudinal axes aligned in parallel or entangled, unless otherwise specified. The carbon nanotube units have a cylindrical shape of a graphite sheet with a nano-sized diameter and an sp2 bonding structure. At this time, the graphite sheets may exhibit conductor or semiconductor properties depending on the angle and structure at which they are rolled. The above bundled carbon nanotubes can be uniformly dispersed during the manufacture of a cathode compared to entangled type carbon nanotubes, and can smoothly form a conductive network within the cathode, thereby improving the conductivity of the cathode.

[0086] In one embodiment of the present application, the negative electrode conductive material may be included in an amount of 0.1 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the negative electrode active material layer composition.

[0087] In another embodiment, the negative electrode conductive material may be included in an amount of 0.1 to 40 parts by weight, preferably 0.2 to 30 parts by weight, more preferably 0.4 to 25 parts by weight, and most preferably 0.4 to 10 parts by weight, based on 100 parts by weight of the negative electrode active material layer composition.

[0088] In one embodiment of the present application, the negative electrode conductive material may include a planar conductive material or a linear conductive material.

[0089] In one embodiment of the present application, the negative electrode conductive material may include a planar conductive material and a linear conductive material.

[0090] In one embodiment of the present application, the cathode conductive material may include a dot-shaped conductive material and a linear conductive material.

[0091] In one embodiment of the present application, the cathode conductive material may include a dot-shaped conductive material.

[0092] In one embodiment of the present application, the negative electrode conductive material may include 80 parts by weight or more and 99.9 parts by weight or less of the planar conductive material based on 100 parts by weight of the negative electrode conductive material; and 0.1 parts by weight or more and 20 parts by weight or less of the linear conductive material.

[0093] In another embodiment, the negative electrode conductive material may include 80 parts by weight or more and 99.9 parts by weight or less of the planar conductive material, preferably 85 parts by weight or more and 99.9 parts by weight or less, and more preferably 95 parts by weight or more and 98 parts by weight or less, based on 100 parts by weight of the negative electrode conductive material.

[0094] In another embodiment, the cathode conductive material may include the linear conductive material in an amount of 0.1 to 20 parts by weight, preferably 0.1 to 15 parts by weight, and more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the cathode conductive material.

[0095] In one embodiment of the present application, the cathode conductive material may include 80 parts by weight or more and 99.9 parts by weight or less of the dot-shaped conductive material based on 100 parts by weight of the cathode conductive material; and 0.1 parts by weight or more and 20 parts by weight or less of the linear conductive material.

[0096] In one embodiment of the present application, since the negative electrode conductive material includes a planar conductive material and a linear conductive material; or a point-shaped conductive material and a linear conductive material; and each satisfies the above composition and ratio, it does not have a significant effect on the life characteristics of an existing lithium secondary battery, and in particular, when a planar conductive material and a linear conductive material are included, the number of points at which charging and discharging are possible increases, so that the output characteristics are excellent at a high C-rate and the amount of high-temperature gas generation is reduced.

[0097] In one embodiment of the present application, the cathode conductive material may be formed of a linear conductive material.

[0098] In particular, when a linear conductive material is used alone, the electrode tortuosity, which is a problem of carbon-based or silicon-based negative electrodes, can be simplified, thereby improving the electrode structure and thus reducing the resistance to movement of lithium ions within the electrode.

[0099] In one embodiment of the present application, when the negative electrode conductive material comprises a linear conductive material alone, the negative electrode conductive material may comprise 0.1 parts by weight or more and 5 parts by weight or less, preferably 0.2 parts by weight or more and 3 parts by weight or less, and more preferably 0.4 parts by weight or more and 1 part by weight or less, based on 100 parts by weight of the negative electrode active material layer composition.

[0100] The negative electrode conductive material according to the present application has a completely separate composition from the positive electrode conductive material applied to the positive electrode. That is, the negative electrode conductive material according to the present application serves to secure the contact between silicon-based active materials, which undergo a significant volume expansion of the electrode due to charging and discharging, and the positive electrode conductive material serves to provide some conductivity while acting as a buffer during rolling, and is completely different in composition and role from the negative electrode conductive material of the present invention.

[0101] In one embodiment of the present application, the planar conductive material used as the aforementioned negative electrode conductive material has a structure and function different from those of carbon-based active materials generally used as negative electrode active materials. Specifically, the carbon-based active material used as the negative electrode active material may be artificial graphite or natural graphite, and refers to a material processed into a spherical or dot-shaped form to facilitate the storage and release of lithium ions.

[0102] On the other hand, the planar conductive material used as the negative electrode conductive material is a material having a planar or plate-like shape, and can be expressed as plate-like graphite. In other words, it refers to a material included to maintain a conductive path within the negative electrode active material layer, and is not a material that plays a role in storing and releasing lithium, but rather a material that secures a conductive path in a planar shape within the negative electrode active material layer.

[0103] That is, in the present application, the use of plate-shaped graphite as a conductive material means that it is processed into a planar or plate-shaped form and used as a material that secures a conductive path rather than a role for storing or releasing lithium. In this case, the included negative electrode active material has high capacity characteristics for lithium storage and release, and serves to store and release all lithium ions delivered from the positive electrode.

[0104] On the other hand, in the present application, the use of a carbon-based active material as an active material means that it is processed into a dot or spherical shape and used as a material that plays a role in storing or releasing lithium.

[0105] That is, in one embodiment of the present application, the carbon-based active material, artificial graphite or natural graphite, is in a dot-like shape and has a BET specific surface area of ​​0.1 m 2 / g or more than 4.5 m 2 / g or less can be satisfied. In addition, the plate-shaped graphite, which is a planar conductive material, has a BET surface area of ​​5 m in the form of a planar surface. 2 / g can be more than that.

[0106] In one embodiment of the present application, the negative electrode binder may include at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and a material in which hydrogens thereof are substituted with Li, Na, Ca, or the like, and may also include various copolymers thereof.

[0107] The negative electrode binder according to one embodiment of the present application serves to hold the active material and conductive material in order to prevent distortion and structural deformation of the negative electrode structure when the volume of the silicon-based active material expands and relaxes. If the above-mentioned role is satisfied, all general binders can be applied, and specifically, an aqueous binder can be used, and more specifically, a PAM-based binder can be used.

[0108] In one embodiment of the present application, the negative electrode binder may be 30 parts by weight or less, preferably 25 parts by weight or less, more preferably 20 parts by weight or less, and may be 5 parts by weight or more, or 10 parts by weight or more, based on 100 parts by weight of the negative electrode active material layer composition.

[0109] In one embodiment of the present application, a lithium secondary battery is provided, wherein the thickness of the negative electrode current collector layer is 1 μm or more and 100 μm or less, and the thickness of the negative electrode active material layer is 5 μm or more and 500 μm or less.

[0110] The above-described negative electrode current collector layer generally has a thickness of 1 μm to 100 μm. The negative electrode current collector layer is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. 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. In addition, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0111] However, the thickness can be varied depending on the type and purpose of the cathode used and is not limited thereto.

[0112] In one embodiment of the present application, the porosity of the negative electrode active material layer can satisfy a range of 10% or more and 60% or less.

[0113] In another embodiment, the porosity of the negative electrode active material layer can satisfy a range of 10% or more and 60% or less, preferably 20% or more and 50% or less, and more preferably 30% or more and 45% or less.

[0114] The above porosity varies depending on the composition and content of the active material, conductive material, and binder included in the negative electrode active material layer, and accordingly, the electrode is characterized by having an appropriate range of electrical conductivity and resistance.

[0115] In one embodiment of the present application, the positive electrode includes a positive electrode current collector layer; and a positive electrode active material layer including a positive electrode active material layer composition provided on one or both sides of the positive electrode current collector layer, wherein the positive electrode active material layer composition includes a positive electrode active material.

[0116] In the above positive electrode, the positive electrode current collector layer is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector layer may typically have a thickness of 3 to 500 ㎛, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0117] The above positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3Lithium manganese composite oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein, M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4, etc., in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion, but is not limited thereto. The positive electrode may be Li-metal.

[0118] In the present application, the positive electrode active material is LiNi x Co y Mn z O2(x+y+z=1); LiNi a Co b Mn c Al d O2(a+b+c+d=1); LiMn2O4; LiNi 0.5 Mn 1.5 O2; and LiM x Fe y A lithium secondary battery is provided, which includes at least one selected from the group consisting of PO4 (M: Transition metal, x+y=1).

[0119] In the present application, the positive electrode active material layer composition is LiNi x Co y Mn z O2(x+y+z=1); or LiNi a Co b Mn c Al d A lithium secondary battery is provided, which includes O2(a+b+c+d=1), wherein z is 0.5 or more and c is 0.4 or more.

[0120] That is, the lithium secondary battery according to the present application is characterized by using a Mn-rich positive electrode active material.

[0121] The above-described positive electrode active material layer may include a positive electrode conductive material and a positive electrode binder together with the positive electrode active material described above.

[0122] At this time, the 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, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one of these may be used alone or a mixture of two or more may be used.

[0123] In addition, the positive electrode binder plays a role of improving the adhesion between positive electrode active material particles and the adhesiveness between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof.

[0124] In the present application, the lithium secondary battery may have an NP Ratio of 110 or more.

[0125] In another embodiment, the NP Ratio may be 110 or more and 200 or less, 113 or more and 150 or less, or 115 or more and 140 or less.

[0126] By controlling NP within the above range, even when the amount of artificial graphite is reduced and the amount of natural graphite is increased, cell characteristics equivalent to or superior to those of the existing ones can be exhibited. In other words, when designing by controlling NP within the above range, a large amount of residual anode can be retained, resulting in a characteristic that can prevent accelerated cell degradation even when the amount of artificial graphite is reduced and the amount of natural graphite is increased.

[0127] In general, the NP ratio can satisfy the following equation A.

[0128] [Formula A]

[0129] N / P ratio = Discharge capacity per unit area of ​​cathode / Discharge capacity per unit area of ​​anode x 100

[0130] In the present invention, the “discharge capacity per unit area” means the discharge capacity per unit area in the first cycle of the negative electrode or the positive electrode.

[0131] The discharge capacity per unit area of ​​the negative electrode can be obtained by the following method. Specifically, a half-cell is manufactured with a negative electrode sample including a negative electrode active material and a counter electrode (e.g., a lithium metal electrode) facing the negative electrode sample. The half-cell is charged and discharged, and the measured discharge capacity is divided by the weight of the negative electrode active material to obtain the “discharge capacity of the negative electrode sample per unit weight of the negative electrode active material.” A secondary battery is manufactured with a negative electrode including the same negative electrode active material as the negative electrode active material used in the half-cell and a positive electrode including the positive electrode active material. The “discharge capacity of the negative electrode sample per unit weight of the negative electrode active material” is multiplied by the weight of the negative electrode active material included in the secondary battery, and the result is divided by the area of ​​the negative electrode included in the secondary battery to obtain the discharge capacity per unit area of ​​the negative electrode.

[0132] The discharge capacity per unit area of ​​the positive electrode can be obtained by the following method. Specifically, a half-cell is manufactured with a positive electrode sample including a positive electrode active material and a counter electrode (e.g., a lithium metal electrode) facing the negative electrode sample. The half-cell is charged and discharged, and the measured discharge capacity is divided by the weight of the positive electrode active material to obtain the “discharge capacity of the positive electrode sample per unit weight of the positive electrode active material.” A secondary battery is manufactured with a positive electrode including the same positive electrode active material as the positive electrode active material used in the half-cell and a negative electrode including the negative electrode active material. The “discharge capacity of the positive electrode sample per unit weight of the positive electrode active material” is multiplied by the weight of the positive electrode active material included in the secondary battery, and the result is divided by the area of ​​the positive electrode included in the secondary battery to obtain the discharge capacity per unit area of ​​the positive electrode.

[0133] The separator separates the negative and positive electrodes and provides a passage for lithium ions to move. Any separator commonly used in secondary batteries can be used without any particular restrictions, and in particular, one that has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0134] Examples of the above electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0135] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0136] As the above non-aqueous organic solvent, for example, an aprotic organic solvent such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, dioxolan derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyrropionate, ethyl propionate, etc. can be used.

[0137] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants and thus can be preferably used because they easily dissociate lithium salts. In addition, when low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed and used in an appropriate ratio with these cyclic carbonates, an electrolyte with high electrical conductivity can be produced, so that they can be used even more preferably.

[0138] The metal salt may be a lithium salt, and the lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte, for example, the anion of the lithium salt is F - , Cl - , I - , NO3 -, N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - One or more selected from the group consisting of can be used.

[0139] 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.

[0140] One embodiment of the present invention provides a battery module including the secondary battery as a unit cell and a battery pack including the same. The battery module and battery pack include the secondary battery having high capacity, high rate characteristics, and cycle characteristics, and thus can be used as a power source for medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0141] Hereinafter, preferred embodiments are presented to help understand the present invention, but the above embodiments are only illustrative of the present disclosure, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present disclosure, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

[0142] <Manufacturing Example>

[0143] <Manufacturing of secondary batteries>

[0144] <Example>

[0145] Carbon-based active material (artificial graphite (D50=18μm): natural graphite (D50=18μm) = 50:50, carbon black and SBR as a binder, CMC as a thickener) were added to distilled water as a solvent for forming a negative electrode slurry at a weight ratio of 95.7:1:2.3:1 to prepare a negative electrode slurry (solid content concentration 50 wt%).

[0146] As a mixing method, carbon black, binder, and water were dispersed using a homogenous mixer at 2500 rpm for 30 min, then the active material (artificial graphite, natural graphite) was added and dispersed at 2500 rpm for 30 min to produce a slurry.

[0147] The negative electrode slurry was applied to both sides of a copper current collector (thickness: 15㎛) as a negative electrode current collector at 5.48 mAh / cm 2The negative electrode active material layer was formed by coating with a loading amount, drying in a vacuum oven at 130°C for 1 hour, and rolling (roll pressing). (Negative electrode porosity 35%)

[0148] LiNi as a cathode active material 0.6 Co 0.2 Mn 0.2 O2 (average particle size (D50): 15㎛), carbon black (product name: Super C65, manufacturer: Timcal) as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder were added to N-methyl-2-pyrrolidone (NMP) as a solvent for forming a cathode slurry at a weight ratio of 95:2.5:2.5 to prepare a cathode slurry (solid content concentration: 63 wt%).

[0149] The positive electrode slurry was applied to both sides of an aluminum current collector (thickness: 15㎛) as a positive electrode collector at a density of 4.0 mAh / cm. 2 The positive electrode was manufactured by coating with a loading amount of , drying in a vacuum oven at 130°C for 1 hour, and rolling (roll pressing) to form a positive electrode active material layer (positive electrode porosity 25%).

[0150] A lithium secondary battery was manufactured by inserting a polyethylene separator between the positive electrode and the negative electrode of the above example and injecting an electrolyte. (Based on 4.2 V to 2 V, NP ratio 137)

[0151] <Comparative Example>

[0152] Carbon-based active material (artificial graphite (D50=18μm): natural graphite (D50=18μm) = 80:20, carbon black and SBR as a binder, CMC as a thickener) were added to distilled water as a solvent for forming a negative electrode slurry at a weight ratio of 95.7:1:2.3:1 to prepare a negative electrode slurry (solid content concentration 50 wt%).

[0153] As a mixing method, carbon black, binder, and water were dispersed using a homogenous mixer at 2500 rpm for 30 min, then the active material (artificial graphite, natural graphite) was added and dispersed at 2500 rpm for 30 min to produce a slurry.

[0154] The negative electrode slurry was applied to both sides of a copper current collector (thickness: 15㎛) as a negative electrode current collector at 5.48 mAh / cm 2 The negative electrode active material layer was formed by coating with a loading amount, drying in a vacuum oven at 130°C for 1 hour, and rolling (roll pressing). (Negative electrode porosity 35%)

[0155] LiNi as a cathode active material 0.6 Co 0.2 Mn 0.2 O2 (average particle size (D50): 15㎛), carbon black (product name: Super C65, manufacturer: Timcal) as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder were added to N-methyl-2-pyrrolidone (NMP) as a solvent for forming a cathode slurry at a weight ratio of 95:2.5:2.5 to prepare a cathode slurry (solid content concentration: 63 wt%).

[0156] The positive electrode slurry was applied to both sides of an aluminum current collector (thickness: 15㎛) as a positive electrode collector at a density of 4.0 mAh / cm. 2 The positive electrode was manufactured by coating with a loading amount of , drying in a vacuum oven at 130°C for 1 hour, and rolling (roll pressing) to form a positive electrode active material layer (positive electrode porosity 25%).

[0157] A lithium secondary battery was manufactured by inserting a polyethylene separator between the positive electrode and the negative electrode of the comparative example and injecting an electrolyte. (Based on 4.2 V to 2 V, NP ratio 137)

[0158] Artificial graphite: Natural graphite: Additional active material Initial capacity of natural graphite (mAh / g) Initial capacity of artificial graphite (mAh / g) Anode loading amount (mAh / cm 2)NP Ratio (4.2V~2V standard) Example 50:50:03643505.48137 Comparative example 80:20:03643505.48137

[0159] Experimental Example 1: Life Characteristics Evaluation

[0160] The secondary batteries containing the negative electrodes manufactured in the above examples and comparative examples were subjected to a life evaluation of three cells each using an electrochemical charger and discharger, and the capacity retention rate was evaluated. The secondary batteries were subjected to an in-situ cycle test at 4.2-2.0 V 1C / 0.5C, and the capacity retention rate was measured by charging / discharging at 0.33C / 0.33C (4.2-2.0 V) every 50 cycles during the test. Table 2 below shows the in-situ capacity retention rate, not the RPT capacity retention rate.

[0161] Capacity retention rate (%) = {(discharge capacity in the Nth cycle) / (discharge capacity in the first cycle)} Х 100

[0162] Experimental Example 2: Measurement and Evaluation of Resistance Increase Rate

[0163] In the above experimental example 1, the capacity retention rate was measured by performing 0.33C / 0.33C charge / discharge (4.2-2.0V) every 50 cycles during the test, and then the resistance was measured by discharging at 2.5C pulse at SOC50 to compare and analyze the resistance increase rate.

[0164] In addition, for the above life characteristic evaluation and the above resistance increase rate measurement evaluation, data at 100 cycles, 200 cycles, and 400 cycles were calculated, respectively, and the results were as shown in Table 2 below.

[0165] In Table 2 below, life evaluations were performed on three secondary batteries of the above examples and were marked as Examples 1 to 3, and life evaluations were performed on three secondary batteries of the above comparative examples and were marked as Comparative Examples 1 to 3, and the average and standard deviation values ​​of Examples 1 to 3 and the average and standard deviation values ​​of Comparative Examples 1 to 3 were entered, respectively.

[0166] 1 st 0.33C discharge capacity (mAh) 100 th Capacity retention rate (%)200 th Capacity retention rate (%) 400 th Capacity retention rate (%) 2.5C charge 30 seconds resistance (R 30sec , ohm)2.5C discharge 30 seconds resistance (R 30sec , ohm)Example 188.993.388.380.81.121.21Example 289.191.687.579.71.141.26Example 389.79186.377.41.151.3Average 89.292.087.479.31.11.3Standard deviation 0.421.191.011.730.020.05Comparative example 187.791.686.480.11.221.28Comparative example 288.792.788.578.61.141.33Comparative example 389.28884.175.11.191.46Average88.590.886.377.91.21.4Standard deviation0.762.462.202.570.040.09

[0167] As can be seen from Tables 1 and 2 above, in the case of the lithium secondary battery according to the present application example, the artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the carbon-based active material is included in an amount of 1 to 50 parts by weight, and the NP Ratio is adjusted to 110 or more, so that a large amount of residual negative electrode can be taken, and it was confirmed that even if the artificial graphite is used in the above range, cell degradation is not accelerated, and accordingly, the life characteristics and resistance characteristics are equivalent or improved.

[0168] Additionally, in the comparative examples where artificial graphite was used beyond the scope of the present application, it was difficult to manufacture the electrode due to the difficulty in handling, and as a result, it was confirmed that the standard deviation of the electrochemical performance values ​​was large compared to the examples. In other words, it was found that the battery of the comparative example was not suitable for mass production and had poor processability. Therefore, it was found that in cases where the NP Ratio was 110 or higher, it was desirable to include natural graphite that is easy to handle and to use a specific weight of artificial graphite according to the present application.

Claims

1. A lithium secondary battery comprising a positive electrode; a negative electrode; a separator described between the positive electrode and the negative electrode; and an electrolyte, The above negative electrode comprises a negative electrode current collector layer; and a negative electrode active material layer comprising a negative electrode active material layer composition provided on one or both sides of the negative electrode current collector layer, The above negative electrode active material layer composition includes a carbon-based active material, Contains 1 to 50 parts by weight of artificial graphite having an initial capacity of 330 mAh / g or more based on 100 parts by weight of the above carbon-based active material, A lithium secondary battery having an NP Ratio of 110 or more.

2. In claim 1, The above carbon-based active material includes artificial graphite and natural graphite having an initial capacity of 330 mAh / g or more, A lithium secondary battery, wherein the weight ratio of the artificial graphite to the natural graphite based on 100 parts by weight of the carbon-based active material is 1:99 to 50:

50.

3. In claim 1, A lithium secondary battery, wherein the negative electrode active material layer composition further includes at least one selected from the group consisting of a silicon-based active material, a tin-based active material, a metal-based active material capable of being alloyed with lithium, lithium titanium oxide, and a lithium-containing nitride.

4. In claim 1, A lithium secondary battery having an NP Ratio of 110 or more and 200 or less.

5. In claim 3, The above negative electrode active material layer composition includes a carbon-based active material and a silicon-based active material, A lithium secondary battery, wherein the silicon-based active material is contained in an amount of 50 parts by weight or less based on 100 parts by weight of the negative active material layer composition.

6. In claim 2, A lithium secondary battery, wherein the artificial graphite and the natural graphite having an initial capacity of 330 mAh / g or more are crystalline carbon.

7. In claim 1, The above positive electrode comprises a positive electrode current collector layer; and a positive electrode active material layer comprising a positive electrode active material layer composition provided on one or both sides of the positive electrode current collector layer, The above positive electrode active material layer composition is LiNi x Co y Mn z O 2 (x+y+z=1); LiNi a Co b Mn c Al d O 2 (a+b+c+d=1); LiMn 2 O 4 ; LiNi 0.5 Mn 1.5 O 2 ; and LiM x Fe y PO 4 A lithium secondary battery comprising one or more positive electrode active materials selected from the group consisting of (M: transition metal, x+y=1).

8. In claim 7, The above positive electrode active material layer composition is LiNi x Co y Mn z O 2 (x+y+z=1); or LiNi a Co b Mn c Al d O 2 Contains (a+b+c+d=1), The above z is greater than or equal to 0.5, A lithium secondary battery wherein the above c is 0.4 or greater.

9. In claim 1, The thickness of the above negative electrode current collector layer is 1 μm or more and 100 μm or less, A lithium secondary battery, wherein the thickness of the negative active material layer is 5 μm or more and 500 μm or less.

10. In claim 7, The thickness of the above positive electrode current collector layer is 1 μm or more and 100 μm or less, A lithium secondary battery, wherein the thickness of the positive electrode active material layer is 5 μm or more and 500 μm or less.

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