Negative electrode for lithium secondary battery, and lithium secondary battery including the same

Abstract

The present application relates to a negative electrode composition, a negative electrode for a lithium secondary battery including the same, and a lithium secondary battery including the negative electrode.

Description

Technical Field

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0184220, filed with the Korean Intellectual Property Office on December 26, 2022, and all of its contents are incorporated herein by reference.

[0002] This application relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the negative electrode.

Background Art

[0003] Due to the rapid increase in the use of fossil fuels, the demand for alternative and clean energy is increasing. As part of this, the fields of power generation and energy storage using electrochemical reactions are the most actively studied.

[0004] Currently, a typical example of an electrochemical device using such electrochemical energy is a secondary battery, and its use area is showing a trend of increasing more and more.

[0005] With the development of technologies related to mobile devices and the increasing demand, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, lithium secondary batteries having a high energy density, a high voltage, a long cycle life, and a low self-discharge rate have been commercialized and widely used. In addition, research on methods for manufacturing high-density electrodes with a higher energy density per unit volume as electrodes for such high-capacity lithium secondary batteries has been actively conducted.

[0006] Generally, a secondary battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode includes a negative electrode active material that inserts and desorbs lithium ions emitted from the positive electrode, and silicon-based particles having a large discharge capacity may be used as the negative electrode active material.

[0007] In particular, recently, with the demand for high-density energy batteries, as negative electrode active materials, Si / C or SiO having a capacity more than 10 times that of graphite-based materials xResearch on methods to increase the capacity using silicon-based compounds such as those described above is being actively conducted. However, in the case of silicon-based compounds, which are high-capacity materials, although they have a larger capacity compared to the conventionally used graphite, there is a problem in that during the charging process, the volume rapidly expands, severing the conductive pathways and degrading the battery characteristics.

[0008] Therefore, in order to solve the problems when using silicon-based compounds as the negative electrode active material, proposals to adjust the driving potential, additionally, methods to further coat a thin film on the active material layer, proposals to suppress the volume expansion itself such as methods to adjust the particle size of the silicon-based compound, or various proposals to prevent the severance of the conductive pathways have been discussed. However, in the case of the above proposals, there is a risk of degrading the battery performance instead, so there are limitations in their application, and there are still limitations in the widespread use of manufacturing negative electrode batteries with a high content of silicon-based compounds.

[0009] Also, in the case of conventional carbon-based negative electrodes such as graphite, since the active material, graphite itself, has high conductivity, the meaning for the range of electrical conductivity was not significant. However, when using a silicon-based active material to enhance the capacity characteristics, since the silicon-based active material is a non-conductive substance, it is necessary to impart conductivity such as adding a negative electrode conductive material or surface treatment of the silicon-based active material.

[0010] Therefore, in the process of manufacturing a silicon-based negative electrode for maximizing the capacity characteristics, research on a negative electrode composition capable of preventing volume expansion due to charge and discharge, damage to the conductive pathways, and surface cracking phenomena as described above is required, and research on a negative electrode capable of maintaining electrical conductivity with a silicon-based negative electrode is also required.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] It has been found that when using a negative electrode with a silicon-based active material to maintain the conductive network of the electrode, the performance of the silicon-based active material, which is a non-conductive material, can be maintained only when the negative electrode conductivity is maintained within a predetermined range. That is, it has been found that when improving the dispersibility with a specific combination of a silicon-based active material, a conductive material, and a binder contained in the silicon-based negative electrode, a predetermined conductivity can be maintained.

[0013] Therefore, an object of the present invention is to provide a negative electrode for a lithium secondary battery and a lithium secondary battery including the negative electrode.

Means for Solving the Problems

[0014] One embodiment of the present specification is a negative electrode for a lithium secondary battery including a negative electrode current collector layer; and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector layer, wherein the negative electrode active material layer composition includes a silicon-based active material, the porosity of the negative electrode active material layer is 10% to 50%, and the conductivity of the negative electrode for the lithium secondary battery is 1 S / cm 2 to 3,000 S / cm 2 The present invention provides a negative electrode for a lithium secondary battery that satisfies the following range.

[0015] In another embodiment, the present invention provides a lithium secondary battery including a positive electrode; the negative electrode for a lithium secondary battery according to the present application; a separator provided between the positive electrode and the negative electrode; and an electrolyte.

Advantages of the Invention

[0016] The negative electrode for a lithium secondary battery according to one embodiment of the present invention is characterized in that when using a silicon-based active material, which is a high-capacity material, to manufacture a high-capacity battery, a conductivity range that can maintain the performance of the silicon-based active material, which is a non-conductive material, has been derived.

[0017] That is, in the conventional carbon-based negative electrode, graphite itself has high conductivity, and the electrical conductivity of the negative electrode itself was not an important factor. However, in the negative electrode using a silicon-based active material to achieve rapid charging and high energy density, as described above, silicon, which is a non-conductive material, is used. At this time, the rolling porosity of the negative electrode itself and the degree of dispersion of the conductive material are very important. By adjusting these factors, the present application can adjust the electrical conductivity of the negative electrode to be 2 3,000 S / cm or more 2 and below, and has the characteristic that the performance of the silicon-based active material can be ensured and maintained.

Brief Description of Drawings

[0018]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0019] Before explaining the present invention, first, several terms are defined.

[0020] In this specification, when a part "includes" a certain component, this means that, unless otherwise stated, it does not exclude other components, but may further include other components.

[0021] In this specification, "p~q" means "p or more and q or less".

[0022] In this specification, the "specific surface area" is measured by the BET method. Specifically, it is calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) using BELSORP-mini II manufactured by BEL Japan, Inc. That is, in this application, the BET specific surface area can mean the specific surface area measured by the above measurement method.

[0023] In this specification, "Dn" means the particle size distribution and means the particle size at the n% point of the cumulative particle number distribution by particle size. That is, D50 is the particle size (average particle size) at the 50% point of the cumulative particle number distribution by particle size, D90 is the particle size at the 90% point of the cumulative particle number distribution by particle size, and D10 is the particle size at the 10% point of the cumulative particle number distribution by particle size. On the other hand, the particle size distribution may be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (for example, Microtrac S3500). When the particles pass through the laser beam, the difference in the diffraction pattern due to the particle size is measured to calculate the particle size distribution.

[0024] In this specification, the meaning that a polymer contains a certain monomer in monomer units means that the monomer participates in the polymerization reaction and is included as a repeating unit in the polymer. In this specification, when it is said that a polymer contains a monomer, this is interpreted to be the same as the polymer containing the monomer in monomer units.

[0025] In this specification, it is understood that the term "polymer" is used in a broad sense including copolymers unless specified as "homopolymer".

[0026] In this specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are the polystyrene-equivalent 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 substances. In this specification, the molecular weight means the weight-average molecular weight unless otherwise specified.

[0027] Hereinafter, for those with ordinary knowledge in the technical field to which the present invention belongs to easily implement the present invention, a detailed description will be given with reference to the drawings. However, the present invention can be embodied in various different forms and is not limited to the following description.

[0028] One embodiment of this specification is a negative electrode for a lithium secondary battery including a negative electrode current collector layer; and a negative electrode active material layer provided on one or both surfaces of the negative electrode current collector layer, wherein the negative electrode active material layer composition includes a silicon-based active material, the porosity of the negative electrode active material layer is 10% to 50%, and the electrical conductivity of the negative electrode for the lithium secondary battery is 1 S / cm 2 or more and 3,000 S / cm 2 A negative electrode for a lithium secondary battery that satisfies the following range is provided.

[0029] The electrical conductivity of the negative electrode for the lithium secondary battery according to this application is 1 S / cm 2 or more and 3,000 S / cm 2 Hereinafter, preferably, 10 S / cm 2 or more and 2,900 S / cm 2 Hereinafter, more preferably, 100 S / cm 2 or more and 2,800 S / cm 2 It can satisfy the following range.

[0030] According to one embodiment of the present invention, the negative electrode for a lithium secondary battery is characterized in that when using a silicon-based active material, which is a high-capacity material, to fabricate a high-capacity battery, the electrical conductivity range that can maintain the performance of the silicon-based active material, which is a non-conductive material, has been derived. At this time, the above-described conductivity range is the most important factor when using a silicon-based negative electrode, and the above-described conductivity range has been derived based on the porosity after rolling of the negative electrode for a lithium secondary battery and the degree of dispersion of the conductive material.

[0031] In one embodiment of the present application, the silicon-based active material is SiO x (x = 0), SiO x (0 < x < 2), SiC, and one or more selected from the group consisting of Si alloys, to provide a negative electrode for a lithium secondary battery.

[0032] The silicon-based active material may be SiO x , Si / C, or Si. SiO x may include a compound represented by SiO x (0 ≦ x < 2). In the case of SiO2, since it does not react with lithium ions and cannot store lithium, x is preferably within the above range. The silicon-based active material may be Si / C or Si composed of a composite of Si and C. Also, two or more of the above-described silicon-based active materials may be mixed and used. The negative electrode active material may further include a carbon-based active material together with the above-described silicon-based active material. The carbon-based active material can contribute to improving the cycle characteristics or battery life performance of the negative electrode or secondary battery of the present invention.

[0033] Generally, it is known that the silicon-based active material has a capacity more than 10 times higher than that of the carbon-based active material. Accordingly, when applying the silicon-based active material to the negative electrode, it is expected that an electrode having a high level of energy density can be realized even with a thin thickness.

[0034] In one embodiment of the present application, the silicon-based active material is SiO x (x = 0) and SiO xincluding one or more selected from the group consisting of (0 < x < 2), based on 100 parts by weight of the silicon-based active material, the SiO x (x = 0) may be included in an amount of 70 parts by weight or more.

[0035] In another embodiment, the silicon-based active material may include, based on 100 parts by weight of the silicon-based active material, the SiO x (x = 0) may be included in an amount of 70 parts by weight or more, preferably 80 parts by weight or more, more preferably 90 parts by weight or more, and may be included in an amount of 100 parts by weight or less, preferably 99 parts by weight or less, more preferably 95 parts by weight or less.

[0036] The silicon-based active material according to the present application includes, based on 100 parts by weight of the silicon-based active material, the SiO x (x = 0) in an amount of 70 parts by weight or more. When compared with a silicon-based active material using the SiO x (0 < x < 2) series as the main substance, it has the disadvantage that the theoretical capacity is much lower than that of the silicon-based active material of the present application. That is, when using the active material of the SiO x (0 < x < 2) series, no matter what treatment is performed on the active material itself, the conditions equivalent to the charge and discharge capacity when having the silicon-based active material of the present invention cannot be realized.

[0037] In one embodiment of the present application, the silicon-based active material may use pure silicon (Si) as the silicon-based active material. Using pure silicon (Si) as the silicon-based active material means that, as described above, when based on a total of 100 parts by weight of the silicon-based active material, pure Si particles (SiO x (x = 0)) are included within the above range.

[0038] When the silicon-based active material is compared with the graphite-based active material used conventionally, the attempt to apply it has increased because the capacity is significantly higher, but the volume expansion rate is high during the charge and discharge process, and it has stopped at the case of mixing a small amount with the graphite-based active material and using it.

[0039] Therefore, in order to improve the capacity performance, while using a high content of a silicon-based active material as the negative electrode active material, in order to solve the problems of maintaining the conductive path due to volume expansion as described above and maintaining the binding of the conductive material, binder, and active material, the present invention is characterized by using a binder under specific conditions.

[0040] On the other hand, the average particle diameter (D50) of the silicon-based active material of the present invention may be 5 μm to 10 μm, specifically, it may be 5.5 μm to 8 μm, and more specifically, it may be 6 μm to 7 μm. When the average particle diameter is within the above range, the specific surface area of the particles is within an appropriate range, and the viscosity of the negative electrode slurry is formed within an appropriate range. As a result, the dispersion of the particles constituting the negative electrode slurry becomes smooth. Further, since the size of the silicon-based active material has a value equal to or greater than the lower limit value of the above range, the contact area between the silicon particles and the conductive material by the composite composed of the conductive material and the binder in the negative electrode slurry is excellent, and the possibility of maintaining the conductive network is increased, and the capacity retention rate is increased. On the other hand, when the average particle diameter satisfies the above range, silicon particles that are too large are excluded, and the surface of the negative electrode is smoothly formed, whereby it is possible to prevent the non-uniformity phenomenon of the current density during charge and discharge.

[0041] In one embodiment of the present application, the silicon-based active material has a usually specific BET specific surface area. The BET specific surface area of the silicon-based active material is preferably 0.01 m 2 / g to 150.0 m 2 / g, more preferably 0.1 m 2 / g to 100.0 m 2 / g, particularly preferably 0.2 m 2 / g to 80.0 m 2 / g, most preferably 0.2 m 2 / g to 18.0 m 2 / g. The BET specific surface area is measured in accordance with DIN 66131 (using nitrogen).

[0042] In one embodiment of the present application, the silicon-based active material may be present, for example, in a crystalline or amorphous form, and preferably is not porous. The silicon particles are preferably spherical or multi-piece particles. Alternatively, the silicon particles may have a fibrous structure or may be present in the form of a thin film or coating containing silicon, but this is not so preferred.

[0043] In one embodiment of the present application, the silicon-based active material may be 60 parts by weight or more based on 100 parts by weight of the negative electrode active material layer composition.

[0044] In another embodiment, the silicon-based active material may be contained in an amount of 60 parts by weight or more, preferably 65 parts by weight or more, more preferably 70 parts by weight or more, and may be 95 parts by weight or less, preferably 90 parts by weight or less, more preferably 85 parts by weight or less, based on 100 parts by weight of the negative electrode active material layer composition.

[0045] The negative electrode composition according to the present application uses a specific conductive material and binder that can control the volume expansion rate during the charge and discharge process even when using a silicon-based active material with a significantly high capacity within the above range, and has the characteristic of excellent output characteristics during charging and discharging without degrading the performance of the negative electrode even when including the above range.

[0046] In one embodiment of the present application, the silicon-based active material may have a non-spherical form, and its sphericity is, for example, 0.9 or less, for example, 0.7 to 0.9, for example, 0.8 to 0.9, for example, 0.85 to 0.9.

[0047] In the present application, the sphericity is determined by the following formula 1-1, where A is the area and P is the boundary line. [Formula 1-1] 4πA / P 2

[0048] Conventionally, it has been common to use only graphite-based compounds as the negative electrode active material. However, recently, as the demand for high-capacity batteries has increased, attempts to mix and use silicon-based compounds to increase the capacity have been increasing. However, in the case of silicon-based compounds, even if the characteristics of the silicon-based active material itself are adjusted according to the present application, there is a risk that, as described above, the volume rapidly expands during the charge / discharge process, damaging the conductive path formed in the negative electrode active material layer.

[0049] Therefore, in one embodiment of the present application, the negative electrode active material layer composition further includes a negative electrode conductive material and a negative electrode binder, and the negative electrode conductive material is 1 part 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, and a negative electrode for a lithium secondary battery is provided.

[0050] In one embodiment of the present application, the negative electrode conductive material may include one or more selected from the group consisting of a dot-shaped conductive material, a planar conductive material, and a linear conductive material.

[0051] In one embodiment of the present application, the dot-shaped conductive material can be used to improve the conductivity of the negative electrode, and means a dot-shaped or spherical conductive material having conductivity without inducing a 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, furnace black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivative, and preferably may include carbon black in terms of realizing high conductivity and excellent dispersibility.

[0052] In one embodiment of the present application, the dot-shaped conductive material may have a BET specific surface area of 40 m 2 / g or more and 70 m 2 / g or less, and preferably 45 m 2 / g or more and 65 m 2 / g or less, more preferably 50 m 2 / g or more and 60 m 2 / g or less may be sufficient.

[0053] In one embodiment of the present application, the particulate conductive material can satisfy an active group content (Volatile matter) 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.

[0054] In particular, when the active group content of the particulate conductive material satisfies the above range, functional groups present on the surface of the particulate conductive material exist, and when water is used as a solvent, the particulate conductive material can be smoothly dispersed in the solvent. In particular, in the present invention, by using silicon particles and a specific binder, the active group content of the particulate conductive material can be reduced, thereby having an excellent effect in improving dispersibility.

[0055] In one embodiment of the present application, the adjustment of the active group content can be adjusted by the degree of heat treatment of the particulate conductive material.

[0056] In one embodiment of the present application, the particle size of the particulate conductive material may be 10 nm to 100 nm, preferably 20 nm to 90 nm, and more preferably 20 nm to 60 nm.

[0057] In one embodiment of the present application, the negative electrode conductive material may include a planar conductive material.

[0058] The planar conductive material can play a role in increasing the surface contact between silicon particles in the negative electrode to improve conductivity, and at the same time suppressing the interruption of the conductive path due to volume expansion. The planar conductive material may be expressed as a plate-shaped conductive material or a bulk-type conductive material.

[0059] In one embodiment of the present application, the planar conductive material may be provided in a form that binds to the surface of the silicon-based particles. Specifically, it may be provided in a form in which the -OH group or -O on the surface of the silicon-based particles binds to the hydrophilic group of the planar conductive material.

[0060] 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 preferably may be plate-shaped graphite.

[0061] In one embodiment of the present application, the average particle size (D50) of the planar conductive material may be 2 μm to 7 μm, specifically, it may be 3 μm to 6 μm, and more specifically, it may be 3.5 μm to 5 μm. When the above range is satisfied, since the particle size is sufficient, dispersion becomes easy while preventing the viscosity of the negative electrode slurry from increasing too much. Therefore, the dispersion effect is excellent when dispersing using the same equipment and time.

[0062] In one embodiment of the present application, the planar conductive material provides a negative electrode composition having D10 of 0.5 μm or more and 2.0 μm or less, D50 of 2.5 μm or more and 3.5 μm or less, and D90 of 6.5 μm or more and 15.0 μm or less.

[0063] In one embodiment of the present application, as the planar conductive material, a high specific surface area planar conductive material with a high BET specific surface area; or a low specific surface area planar conductive material may be used.

[0064] In one embodiment of the present application, as the planar conductive material, a high specific surface area planar conductive material; or a low specific surface area planar conductive material may be used without limitation. However, in particular, the planar conductive material according to the present application may be somewhat affected by dispersion in terms of electrode performance, and it is particularly preferable to use a low specific surface area planar conductive material that does not cause problems in dispersion.

[0065] In one embodiment of the present application, the planar conductive material has a BET specific surface area of 1 m 2 / g or more.

[0066] In another embodiment, the planar conductive material has a BET specific surface area of 1 m 2 / g or more and 500 m 2 / g or less, preferably 5 m 2 / g or more and 300 m 2 / g or less, more preferably 5 m 2 / g or more and 250 m 2 / g or less.

[0067] The planar conductive material according to the present application may use a planar conductive material with a high specific surface area or a planar conductive material with a low specific surface area.

[0068] In another embodiment, the planar conductive material is a planar conductive material with a high specific surface area, and the BET specific surface area is 50 m 2 / g or more and 500 m 2 / g or less, preferably 80 m 2 / g or more and 300 m 2 / g or less, more preferably 100 m 2 / g or more and 300 m 2 / g or less.

[0069] In another embodiment, the planar conductive material is a planar conductive material with a low specific surface area, and the BET specific surface area is 1 m 2 / g or more and 40 m 2 / g or less, preferably 5 m 2 / g or more and 30 m 2 / g or less, more preferably 5 m 2 / g or more and 25 m 2 / g or less.

[0070] In addition, as the conductive material, there may be a linear conductive material such as a carbon nanotube. The carbon nanotube may be a bundled carbon nanotube. The bundled carbon nanotube may include a plurality of carbon nanotube units. Specifically, here, the 'bundle type' refers to a secondary shape in which a plurality of carbon nanotube units are arranged in parallel or twisted in a bundle or rope shape with the axes in the longitudinal direction of the carbon nanotube units being substantially the same orientation, unless otherwise specified. The carbon nanotube unit has a graphite sheet having a nanosize diameter in a cylindrical shape and has an sp2 bonding structure. At this time, depending on the angle and structure of the winding of the graphite sheet, it can exhibit the characteristics of a conductor or a semiconductor. The bundled carbon nanotube can be uniformly dispersed during the production of the negative electrode compared to the entangled type carbon nanotube, and can smoothly form a conductive network in the negative electrode, improving the conductivity of the negative electrode.

[0071] In one embodiment of the present application, the negative electrode conductive material includes a linear conductive material. In particular, the linear conductive material may include SWCNT and MWCNT.

[0072] Exemplarily, the linear conductive material may be a single-walled carbon nanotube (SWCNT) having a large BET specific surface area, being linear, having a very small diameter and a very long length. A linear conductive material such as SWCNT cannot be stretched through dispersion and has a strong ability to return to its original form while being dried. As a result, a linear conductive material such as SWCNT has a strong force to return to its original form when dried, and thus it is generally present in a form that wraps or connects the negative electrode active material and secondary aggregates. The joining method can be adsorbed by van der Waals forces.

[0073] In one embodiment of the present application, a negative electrode composition is provided in which the negative electrode conductive material is 1 part by weight or more and 40 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0074] In another embodiment, the negative electrode conductive material may be included in an amount of 1 to 40 parts by weight, preferably 3 to 30 parts by weight, more preferably 3 to 25 parts by weight, based on 100 parts by weight of the negative electrode composition.

[0075] In one embodiment of the present application, the negative electrode conductive material provides a negative electrode for a lithium secondary battery, which is composed of a planar conductive material and a linear conductive material.

[0076] In one embodiment of the present application, based on 100 parts by weight of the negative electrode conductive material, the negative electrode conductive material may include 80 to 99.9 parts by weight of the planar conductive material; and 0.1 to 20 parts by weight of the linear conductive material.

[0077] In another embodiment, based on 100 parts by weight of the negative electrode conductive material, the negative electrode conductive material may include 80 to 99.9 parts by weight of the planar conductive material, preferably 85 to 99.9 parts by weight, more preferably 95 to 98 parts by weight.

[0078] In another embodiment, based on 100 parts by weight of the negative electrode conductive material, the negative electrode conductive material may include 0.1 to 20 parts by weight of the linear conductive material, preferably 0.1 to 15 parts by weight, more preferably 1 to 5 parts by weight.

[0079] In one embodiment of the present application, when the negative electrode conductive material includes a planar conductive material and a linear conductive material and satisfies the respective compositions and ratios, it does not have a significant impact on the life characteristics of conventional lithium secondary batteries. In particular, when including a planar conductive material and a linear conductive material, there are more points where charging and discharging are possible, resulting in excellent output characteristics at a high C-rate and a reduction in the amount of high-temperature gas generation.

[0080] In one embodiment of the present application, the negative electrode conductive material includes a linear conductive material alone, and based on 100 parts by weight of the negative electrode conductive material, the linear conductive material is included in an amount of 5 parts by weight or less, providing a negative electrode for a lithium secondary battery.

[0081] In still another embodiment, the negative electrode conductive material includes a linear conductive material alone, and based on 100 parts by weight of the negative electrode conductive material, the linear conductive material may be 5 parts by weight or less, preferably 4 parts by weight or less, and may also include 0.1 part by weight or more, preferably 0.5 part by weight or more.

[0082] In one embodiment of the present application, the negative electrode conductive material includes a pre-dispersion liquid of the negative electrode conductive material, and the viscosity of the pre-dispersion liquid of the negative electrode conductive material is 2,000 cP or more and 10,000 cP or less, providing a negative electrode for a lithium secondary battery.

[0083] That is, the fact that the negative electrode conductive material includes a pre-dispersion liquid of the negative electrode conductive material means that the negative electrode conductive material is not directly included in the negative electrode active material layer composition, but is included in a pre-dispersed state. When the viscosity of the pre-dispersion liquid of the negative electrode conductive material in the pre-dispersed state satisfies 2,000 cP or more and 10,000 cP or less and satisfies the rolling porosity described later, it has the characteristic that the negative electrode conductivity according to the present application can be satisfied.

[0084] The negative electrode conductive material according to the present application has a completely different configuration from the positive electrode conductive material applied to the positive electrode. That is, in the case of the negative electrode conductive material according to the present application, it plays a role in controlling the contact points between silicon-based active materials with very large volume expansion of the electrode during charging and discharging. The positive electrode conductive material plays a role in imparting partial conductivity while acting as a buffer with a buffering effect when rolled, and its configuration and role are completely different from those of the negative electrode conductive material of the present invention.

[0085] In addition, the negative electrode conductive material according to the present application is applied to a silicon-based active material and has a completely different configuration from the conductive material applied to a graphite-based active material. That is, the conductive material used for an electrode having a graphite-based active material simply has smaller particles than the active material, and thus has the characteristics of improving output characteristics and imparting some conductivity, and is completely different in configuration and role from the negative electrode conductive material applied together with a silicon-based active material as in the present invention.

[0086] In one embodiment of the present application, the planar conductive material used as the aforementioned negative electrode conductive material generally has a structure and role different from those of the carbon-based active material generally used as the negative electrode active material. Specifically, the carbon-based active material used as the negative electrode active material may be artificial graphite or natural graphite, and means a material processed into a spherical or dot-like form in order to facilitate the storage and release of lithium ions.

[0087] On the other hand, the planar conductive material used as the negative electrode conductive material is a material having a planar or plate-like form and can be represented by plate-like graphite. That is, it is a material included to maintain a conductive path within the negative electrode active material layer, and means a material for securing a conductive path in a planar form inside the negative electrode active material layer that does not play a role in the storage and release of lithium.

[0088] That is, in the present application, the fact that plate-like graphite is used as the conductive material means that it has been processed into a planar or plate-like form and used as a material for securing a conductive path that does not play a role in the storage or release of lithium. At this time, the negative electrode active material included together has a high capacity characteristic with respect to the storage and release of lithium and plays a role of being able to store and release all lithium ions transmitted from the positive electrode.

[0089] On the other hand, in the present application, the fact that a carbon-based active material is used as the active material means that it has been processed into a dot-like or spherical form and used as a material that plays a role in storing or releasing lithium.

[0090] 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), fluororubber, poly acrylic acid, and substances in which hydrogen thereof is substituted with Li, Na, Ca, etc., and may also include various copolymers thereof.

[0091] The negative electrode binder according to one embodiment of the present application plays a role in controlling the active material and the conductive material in order to prevent the twisting and structural deformation of the negative electrode structure during the volume expansion and relaxation of the silicon-based active material. If the role is satisfied, general binders can all be applied. Specifically, an aqueous binder may be used, and more specifically, a PAM-based binder may be used.

[0092] In one embodiment of the present application, the negative electrode binder includes an aqueous binder, and the negative electrode binder is 5 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the negative electrode active material layer composition, to provide a negative electrode for a lithium secondary battery.

[0093] In another embodiment, the negative electrode binder may be 5 parts by weight or more and 30 parts by weight or less, preferably 7 parts by weight or more and 15 parts by weight or less, more preferably 9 parts by weight or more and 12 parts by weight or less based on 100 parts by weight of the negative electrode active material layer composition.

[0094] In one embodiment of the present application, based on 100 parts by weight of the silicon-based active material, the negative electrode binder may be included in an amount of 3 parts by weight or more and 10 parts by weight or less.

[0095] In another embodiment, based on 100 parts by weight of the silicon-based active material, the negative electrode binder may be 3 parts by weight or more and 10 parts by weight or less, preferably 3.5 parts by weight or more and 9.5 parts by weight or less, more preferably 4 parts by weight or more and 9 parts by weight or less.

[0096] In the case of the negative electrode for a lithium secondary battery according to the present application, in order to maximize the capacity characteristics, when using the silicon-based active material in the above parts by weight, compared with the case of using the conventional carbon-based active material as the main active material, the volume expansion during charge and discharge becomes larger. Therefore, by including the negative electrode binder in the above content, it has the characteristic that the volume expansion due to charge and discharge of the highly rigid silicon-based active material can be efficiently controlled.

[0097] In particular, the negative electrode for a lithium secondary battery according to the present application satisfies a predetermined electrical conductivity, which can be adjusted by a negative electrode conductive material and a negative electrode binder. The negative electrode conductive material is a conductive substance, and the silicon-based active material and the negative electrode binder are non-conductive substances. By adjusting the ratio and dispersion degree in the mixed electrode to adjust the mixing state, the above-described electrical conductivity can be satisfied, and by satisfying the electrical conductivity, the performance of the silicon-based active material can be maintained.

[0098] FIG. 1 is a diagram showing the laminated structure of the negative electrode for a lithium secondary battery according to one embodiment of the present application. Specifically, the negative electrode 100 for a lithium secondary battery including the negative electrode active material layer 20 on one surface of the negative electrode current collector layer 10 can be confirmed.

[0099] FIG. 2 according to another embodiment is a diagram showing the laminated structure of the negative electrode for a lithium secondary battery. Specifically, the negative electrode 100 for a lithium secondary battery including the negative electrode active material layer 20 on both surfaces of the negative electrode current collector layer 10 can be confirmed.

[0100] In this application, there are two types: one is that the negative electrode active material layer is coated on one side of the negative electrode current collector layer (see Figure 1), and the other is that the negative electrode active material layer is coated on both sides of the negative electrode current collector layer (see Figure 2). At this time, the compositions of the negative electrode active material layers coated on both sides may be the same or different.

[0101] In one embodiment of this application, when the negative electrode active material layer is coated on both sides, the negative electrode active material layer containing the negative electrode composition according to this application can be used without limitation as long as it is coated on only one of the two sides, and the other side may contain a silicon-based negative electrode active material or a carbon-based negative electrode active material that can generally be included.

[0102] In one embodiment of this application, the negative electrode for the lithium secondary battery can be formed by coating the negative electrode slurry containing the negative electrode active material layer composition on one side or both sides of the current collector.

[0103] In one embodiment of this application, the negative electrode slurry may contain a negative electrode active material layer composition and a slurry solvent.

[0104] In one embodiment of this application, the content of the solid content of the negative electrode slurry can satisfy 5% or more and 40% or less.

[0105] In another embodiment, the content of the solid content of the negative electrode slurry can satisfy the range of 5% or more and 40% or less, preferably 7% or more and 35% or less, more preferably 10% or more and 30% or less.

[0106] The content of the solid content of the negative electrode slurry may mean the content of the negative electrode composition contained in the negative electrode slurry, or may mean the content of the negative electrode composition based on 100 parts by weight of the negative electrode slurry.

[0107] When the content of the solid component of the negative electrode slurry satisfies the above range, during the formation of the negative electrode active material layer, the viscosity is appropriate, the agglomeration phenomenon of the particles of the negative electrode composition is minimized, and the negative electrode active material layer can be efficiently formed.

[0108] In one embodiment of the present application, the negative electrode current collector layer generally has a thickness of 1 μm to 100 μm. Such a negative electrode current collector layer is not particularly limited as long as it has high conductivity without inducing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. may be used. Also, fine irregularities may be formed on the surface to strengthen the binding force of the negative electrode active material, and it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc.

[0109] In one embodiment of the present application, a negative electrode for 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 20 μm or more and 500 μm or less.

[0110] However, the thickness may vary diversely depending on the type and use of the negative electrode used, and is not limited thereto.

[0111] In one embodiment of the present application, the porosity of the negative electrode active material layer can satisfy the range of 10% or more and 50% or less.

[0112] In another embodiment, the porosity of the negative electrode active material layer can satisfy the range of 10% or more and 40% or less, preferably 20% or more and 40% or less, more preferably 30% or more and 40% or less.

[0113] The porosity is varied by the composition and content of the silicon-based active material, conductive material, and binder contained in the negative electrode active material layer. In particular, by including the silicon-based active material and conductive material according to the present application in specific compositions and content portions, the above range is satisfied, whereby the electrode has appropriate ranges of electrical conductivity and resistance.

[0114] In one embodiment of the present application, there is provided a lithium secondary battery including a positive electrode; a negative electrode for a lithium secondary battery according to the present application; a separator provided between the positive electrode and the negative electrode; and an electrolyte.

[0115] FIG. 3 is a diagram showing a laminated structure of a lithium secondary battery according to one embodiment of the present application. Specifically, a negative electrode 100 for a lithium secondary battery including a negative electrode active material layer 20 can be confirmed on one surface of a negative electrode current collector layer 10, and a positive electrode 200 for a lithium secondary battery including a positive electrode active material layer 40 can be confirmed on one surface of a positive electrode current collector layer 50, indicating that the negative electrode 100 for a lithium secondary battery and the positive electrode 200 for a lithium secondary battery are laminated with a separator 30 interposed therebetween. Further, the negative electrode active material layer 20 may be formed on both surfaces of the negative electrode current collector layer 10. Further, the positive electrode active material layer 40 may be formed on both surfaces of the positive electrode current collector layer 50.

[0116] A secondary battery according to one embodiment of the present specification may particularly include the negative electrode for a lithium secondary battery described above. Specifically, the secondary battery may include a negative electrode, a positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, and the negative electrode is the same as the negative electrode described above. Since the above has been described with respect to the negative electrode, a specific description is omitted.

[0117] The positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode active material.

[0118] In the positive electrode, the positive electrode current collector is not particularly limited as long as it has conductivity without inducing chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those with a surface treatment of carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel may be used. Further, the positive electrode current collector may usually have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the current collector to enhance the adhesive force of the positive electrode active material. For example, it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabric bodies, etc.

[0119] The positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material is 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; chemical formula Li 1+c1 Mn 2-c1 O4 (0 ≦ c1 ≦ 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2 O2 (where 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) of Ni-site type lithium nickel oxide; chemical formula LiMn 2-c3 M c3 O2 (where 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 lithium manganese composite oxide represented by Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); examples include LiMn2O4 in which a part of the Li in the chemical formula is substituted with an alkaline earth metal ion, but it is not limited thereto. The positive electrode may be Li metal (Li-metal).

[0120] The 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.

[0121] At this time, the positive electrode conductive material is used to impart conductivity to the electrode, and in the battery to be configured, it can be used without particular limitation as long as it has electron conductivity without causing a chemical change. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; 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. Among these, one kind alone or a mixture of two or more kinds may be used.

[0122] In addition, the positive electrode binder serves to improve the adhesion between the positive electrode active material particles and the adhesive force between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene 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), fluorine rubber, or various copolymers thereof. Among these, one kind alone or a mixture of two or more kinds may be used.

[0123] The separator membrane separates the negative electrode and the positive electrode and provides a lithium ion migration path. Usually, any separator membrane that can be used in a secondary battery can be used without particular limitation. In particular, a separator membrane that has a low resistance to the ion migration of the electrolyte and is excellent in the moisture retention ability of the electrolyte solution is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof may be used. Also, a normal porous non-woven fabric, for example, a non-woven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, a coated separator membrane containing a ceramic component or a polymer substance to ensure heat resistance or mechanical strength may be used, and it may be selectively used in a single layer or a multi-layer structure.

[0124] Examples of the 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.

[0125] Specifically, the electrolyte may contain a non-aqueous organic solvent and a metal salt.

[0126] Examples of the non-aqueous organic solvent include aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate, etc. may be used.

[0127] In particular, among the carbonate-based organic solvents, ethylene carbonate and propylene carbonate which are cyclic carbonates are high-viscosity organic solvents with high dielectric constants and can preferably be used because they can well dissociate lithium salts. If linear carbonates with low viscosity and low dielectric constant such as dimethyl carbonate and diethyl carbonate are mixed with such cyclic carbonates at an appropriate ratio and used, an electrolyte having high electric conductivity can be produced, so they can be more preferably used.

[0128] As the metal salt, a lithium salt may be used. The lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte solution. For example, as the anion of the lithium salt, 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:

[0129] In addition to the constituent components of the electrolyte, the electrolyte may further contain one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine 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 a decrease in battery capacity, and improving the discharge capacity of the battery.

[0130] According to one embodiment of the present invention, there is provided a battery module including the secondary battery as a unit cell, and a battery pack including the same. The battery module and the battery pack include the secondary battery having high capacity, high rate characteristics, and high cycle characteristics, and therefore may 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.

[0131] [Example] Hereinafter, in order to facilitate the understanding of the present invention, preferred embodiments are presented. However, these embodiments are merely illustrative of the description, and it is obvious to those skilled in the art that various changes and modifications can be made within the scope of the description and the scope of the technical idea. It is natural that such variations and modifications belong to the scope of the claims.

[0132] [Production Example] <Example 1> As a silicon-based active material, Si (average particle size (D50): 3.5 μm), a first conductive material, a second conductive material, and polyacrylamide as a binder were added to distilled water as a solvent for forming a negative electrode slurry at a weight ratio of 88:2.6:0.4:9 to produce a negative electrode slurry (solid content concentration: 25% by weight).

[0133] The first conductive material is SWCNT, with a BET specific surface area satisfying about 1000 - 1500 m 2 / g, and an aspect ratio of 10000 or more (specific surface area: 58 m 2 / g, diameter: 37 nm, Volatile matter: 0.01%). The second conductive material was MWCNT.

[0134] At this time, the first conductive material and the second conductive material formed a pre-dispersion liquid of the negative electrode conductive material in water as a dispersion medium so that the solid content content was 15%, and a milling device using a homomixer was used to disperse the pre-dispersion liquid of the negative electrode to obtain a pre-dispersion liquid of the negative electrode conductive material with a viscosity of 6700 cP.

[0135] As a mixing method, the pre-dispersion liquid of the negative electrode conductive material, the binder, and water were dispersed at 2500 rpm for 30 minutes using a homo mixer, then the active material was added, and then dispersed at 2500 rpm for 30 minutes to produce a slurry.

[0136] As a negative electrode current collector, the negative electrode slurry was applied to both sides of a copper current collector (thickness: 8 μm) at 85 mg / 25 cm 2Coated with the loading amount of [material] and roll-pressed, then dried in a vacuum oven at 130 °C for 10 hours to form a negative electrode active material layer (thickness: 33 μm), which was used as the negative electrode (negative electrode thickness: 41 μm). At this time, the porosity and electrical conductivity of the negative electrode active material layer satisfied Table 1 below.

[0137]

Table 1

[0138] <Manufacture of secondary battery> As the positive electrode active material, LiNi 0.6 Co 0.2 Mn 0.2 O2 (average particle size (D50): 15 μm), carbon black (product name: Super C65, manufacturer: Timcal) as the conductive material, and polyvinylidene fluoride (PVdF) as the binder were added to N-methyl-2-pyrrolidone (NMP) as the solvent for forming the positive electrode slurry at a weight ratio of 97:1.5:1.5 to produce a positive electrode slurry (solid content concentration: 78 wt%).

[0139] As the positive electrode current collector, the positive electrode slurry was coated on both sides of an aluminum current collector (thickness: 12 μm) at a loading amount of 537 mg / 25 cm 2 and roll-pressed, then dried in a vacuum oven at 130 °C for 10 hours to form a positive electrode active material layer (thickness: 65 μm), and a positive electrode was manufactured (positive electrode thickness: 77 μm, porosity 26%).

[0140] A polyethylene separator was interposed between the positive electrode and the negative electrode of Example 1, and an electrolyte was injected to manufacture the secondary battery of Example 1.

[0141] The electrolyte is an organic solvent in which fluoroethylene carbonate (FEC) and diethyl carbonate (DMC) are mixed at a volume ratio of 30:70, with vinylene carbonate added at 3 wt% based on the total weight of the electrolyte, and LiPF6 added at a concentration of 1 M as the lithium salt.

[0142] Secondary batteries were manufactured in the same manner as described above, except that the negative electrodes of the above Examples and Comparative Examples were used.

[0143] Experimental Example 1: Monocell Life Evaluation Life evaluations were performed on the secondary batteries manufactured in the above Examples and Comparative Examples using an electrochemical charge / discharge device, and the capacity retention rate was evaluated. The secondary batteries were charged (0.33C CC / CV charge at 4.2V with 0.05C cut-off) and discharged (0.33C CC discharge at 3.0V cut-off) to make this the first cycle, and then charged (1.0C CC / CV charge at 4.2V with 0.05C cut-off) and discharged (0.5C CC discharge at 3.0V cut-off) from the second cycle onwards.

[0144] The capacity retention rate of the Nth cycle was evaluated according to the following formula. The results are shown in Table 2 below.

[0145] Capacity retention rate (%) = {(discharge capacity in the Nth cycle) / (discharge capacity in the first cycle)} × 100

[0146]

Table 2

[0147] As can be confirmed from Tables 1 and 2 above, the batteries including the negative electrodes of Examples 1 to 4 according to the present application satisfy the porosity and the degree of dispersion of the conductive material, adjust the electrical conductivity within the scope of the present application, and can ensure and maintain the performance of the silicon-based active material.

[0148] Comparative Example 1 corresponds to the case where the range of electrical conductivity is less than the range according to the present application, and Comparative Example 2 corresponds to the case where it exceeds the range according to the present application. Similarly, the porosity and the degree of dispersion of the conductive material were adjusted and formed as described above. In this case, as can be confirmed in Table 2, it was confirmed that the capacity retention rate decreased. Specifically, in Comparative Example 1, the electrical conductivity was low, the formation of the conductive network was not easy, and the performance decreased. In the case of Comparative Example 2, on the contrary, it was confirmed that the range of electrical conductivity was high and problems also occurred in terms of capacity and life.

Explanation of Reference Numerals

[0149] 10 ··· Negative electrode current collector layer 20 ··· Negative electrode active material layer 30 ··· Separator 40 ··· Positive electrode active material layer 50 ··· Positive electrode current collector layer 100 ··· Negative electrode for lithium secondary battery 200 ··· Positive electrode for lithium secondary battery

Claims

1. 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 surfaces of the negative electrode current collector layer; A negative electrode for a lithium secondary battery, comprising: The negative electrode active material layer composition contains a silicon-based active material, The porosity of the negative electrode active material layer is 10% to 50%, The electric conductivity of the negative electrode for the lithium secondary battery is 1 S / cm ２ or more and 3,000 S / cm ２ or less, and a negative electrode for a lithium secondary battery satisfying the following range.

2. The silicon-based active material is SiO ｘ (x = 0), SiO ｘ (0 < x < 2), SiC, and one or more selected from the group consisting of Si alloys, the negative electrode for a lithium secondary battery according to claim 1.

3. The silicon-based active material is SiO ｘ where x = 0 and SiO ｘ where 0 < x < 2, and based on 100 parts by weight of the silicon-based active material, the SiO ｘ where x = 0 contains 70 parts by weight or more. The negative electrode for a lithium secondary battery according to claim 1.

4. The silicon-based active material is 60 parts by weight or more based on 100 parts by weight of the negative electrode active material layer composition. The negative electrode for a lithium secondary battery according to Claim 1.

5. The negative electrode active material layer composition further includes a negative electrode conductive material and a negative electrode binder, The negative electrode conductive material is 1 part 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. The negative electrode for a lithium secondary battery according to Claim 1.

6. The negative electrode conductive material includes a linear conductive material, Based on 100 parts by weight of the negative electrode conductive material, the linear conductive material is included in an amount of 5 parts by weight or less. The negative electrode for a lithium secondary battery according to Claim 5.

7. The negative electrode conductive material consists of a planar conductive material and a linear conductive material. The negative electrode for a lithium secondary battery according to Claim 5.

8. The negative electrode conductive material includes, based on 100 parts by weight of the negative electrode conductive material, 80 parts by weight or more and 99.9 parts by weight or less of the planar conductive material; and 0.1 parts by weight or more and 20 parts by weight or less of the linear conductive material. The negative electrode for a lithium secondary battery according to Claim 7.

9. The negative electrode conductive material includes a pre-dispersion liquid of the negative electrode conductive material, The viscosity of the pre-dispersion liquid of the negative electrode conductive material is 2,000 cP or more and 10,000 cP or less. The negative electrode for a lithium secondary battery according to Claim 5.

10. The negative electrode binder is 5 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the negative electrode active material layer composition. The negative electrode for a lithium secondary battery according to Claim 5.

11. The thickness of the negative electrode current collector layer is 1 μm or more and 100 μm or less, The thickness of the negative electrode active material layer is 20 μm or more and 500 μm or less. The negative electrode for a lithium secondary battery according to Claim 1.

12. A positive electrode; The negative electrode for a lithium secondary battery according to any one of Claims 1 to 11; A separator provided between the positive electrode and the negative electrode; and An electrolyte; A lithium secondary battery comprising:

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