Anode composition, anode for lithium secondary battery including the same, and lithium secondary battery including the anode

Abstract

The present application relates to a negative electrode composition, a negative electrode for a lithium secondary battery, 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. 10-2022-0177386, filed with the Korean Intellectual Property Office on December 16, 2022, the entire contents of which are incorporated herein by reference.

[0002] 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. [Background technology]

[0003] The rapid increase in fossil fuel use has led to an increasing demand for alternative and clean energy, and one of the most actively researched fields in this area is the field of power generation and storage using electrochemical reactions.

[0004] Currently, a typical example of an electrochemical element that uses such electrochemical energy is a secondary battery, and the range of its use is tending to expand more and more.

[0005] As technological development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which have high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and widely used. In addition, active research is being conducted on methods for manufacturing high-density electrodes with higher energy density per unit volume as electrodes for such high-capacity lithium secondary batteries.

[0006] Generally, a secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator. The negative electrode contains a negative electrode active material that inserts and extracts lithium ions from the positive electrode. Silicon-based particles with a large discharge capacity can be used as the negative electrode active material.

[0007] In particular, with the recent demand for high-density energy batteries, active research is being conducted into methods of increasing capacity using silicon-based compounds such as Si / C and SiOx as anode active materials, which have a capacity more than 10 times greater than that of graphite-based materials.However, while silicon-based compounds, which are high-capacity materials, have a higher capacity than conventionally used graphite, they suffer from the problem of rapid volume expansion during charging, which breaks the conductive path and reduces battery performance.

[0008] Therefore, in order to solve the problems associated with using silicon-based compounds as negative electrode active materials, various methods have been discussed, such as methods for controlling the driving potential, methods for additionally coating a thin film on the active material layer, methods for suppressing volume expansion itself, such as methods for controlling the particle size of the silicon-based compound, or methods for preventing the conductive path from being broken. However, these methods have limitations in their application because they may actually degrade battery performance, and there are still limitations in the commercialization of negative electrode batteries with a high content of silicon-based compounds.

[0009] Furthermore, in the case of electrodes that use graphite or a composite of graphite and silicon as the active material, the electrodes are manufactured by adding dot-like conductive materials. However, conventionally used dot-like conductive materials react with lithium to block pores in the electrode structure, increasing the diffusion resistance of Li ions. This resistance results in differences in the degree of electrode deterioration during lithium insertion and desorption reactions at the top and bottom ends of the electrode.

[0010] Therefore, in the process of manufacturing silicon-based negative electrodes to maximize capacity characteristics, research is needed on electrodes that can maintain the same porosity of the electrode while maximizing the diffusion of Li ions. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-080971 Summary of the Invention Problems to be Solved by the Invention

[0012] Although various types of negative electrode conductive materials are used to maintain the conductive path, the above problems still remain unsolved. Therefore, while removing the dot-shaped conductive material, which is a conventional conductive material, and including a void securing material in the negative electrode composition to secure voids in the electrode, and inserting a linear conductive material to complement the void securing material, which is a non-conductor, as the conductive material, it has been found that the above problems can be solved.

[0013] Therefore, the present application relates to a negative electrode composition capable of solving the above problems, a negative electrode for a lithium secondary battery including the same, 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 composition including a silicon-based active material; a void securing material; a linear conductive material; and a negative electrode binder, wherein the silicon-based active material includes one or more selected from the group consisting of SiOx (x = 0) and SiOx (0 < x < 2), includes 90 parts by weight or more of the SiOx (x = 0) based on 100 parts by weight of the silicon-based active material, the void securing material is included in an amount of 0.1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the negative electrode composition, and a weight ratio of the linear conductive material to the void securing material is 1:10 to 1:120.

[0015] In another embodiment, there is provided a negative electrode for a lithium secondary battery including a negative electrode current collector layer; and a negative electrode active material layer including the negative electrode composition according to the present application formed on one or both surfaces of the negative electrode current collector layer.

[0016] Finally, there is provided 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

[0017] The negative electrode composition according to the present application is characterized by the inclusion of a void-forming material that can maintain the porosity of the electrode and maximize the diffusion of lithium ions. This eliminates the conventional conductive dots and uses the void-forming material, which has the advantage that the void-forming material is located between particles in the electrode, thereby creating voids that allow the diffusion of lithium ions.

[0018] In addition, the void-securing material is a non-conductor and a certain content is used to secure the void, but a linear conductive material is further included to complement this and reduce the resistance of the electrode. This allows the void to be maintained even during lithium insertion / extraction in the pure silicon electrode, and also ensures conductivity, thereby reducing the resistance of the electrode.

[0019] That is, the anode composition according to the present invention is characterized in that, in an anode that uses a silicon-based active material to maximize capacity, a certain amount of pore-securing material is used to simplify the pore structure, which is a problem with pure Si, and the resulting conductive network problem is solved by including a specific amount of linear conductive material. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing a laminated structure of a negative electrode for a lithium secondary battery according to an embodiment of the present application. [Figure 2] FIG. 1 is a diagram showing a stack structure of a lithium secondary battery according to an embodiment of the present application. [Figure 3] FIG. 1 shows a 4-point probe setup for calculating the conductivity of an electrode. DETAILED DESCRIPTION OF THE INVENTION

[0021] Before describing the present invention, some terms will first be defined. In this specification, when a part is said to "comprise" a certain component, this means that it may further include other components, rather than excluding other components, unless otherwise specified.

[0022] In this specification, "p to q" means a range of "not less than p and not more than q." In this specification, the "specific surface area" is measured by the BET method, and specifically, is calculated from the amount of nitrogen gas adsorption at liquid nitrogen temperature (77 K) using a BELSORP-mini II manufactured by BEL Japan Co., Ltd. That is, in the present application, the BET specific surface area may mean the specific surface area measured by the above-mentioned measurement method.

[0023] In this specification, "Dn" refers to particle size distribution, and refers to the particle size at the n% point in the cumulative particle number distribution corresponding to the particle size. That is, D50 is the particle size (median particle size) at the 50% point in the cumulative particle number distribution corresponding to the particle size, D90 is the particle size at the 90% point in the cumulative particle number distribution corresponding to the particle size, and D10 is the particle size at the 10% point in the cumulative particle number distribution corresponding to the particle size. Meanwhile, the median particle size can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac S3500). The particle size distribution is calculated by measuring the difference in diffraction patterns corresponding to particle size when the particles pass through a laser beam.

[0024] In one embodiment of the present application, the particle size or particle size may refer to the average diameter or typical diameter of individual grains that make up the particle.

[0025] In this specification, when a polymer contains a certain monomer as a monomer unit, it means that the monomer participates in a polymerization reaction and is contained as a repeating unit in the polymer. In this specification, when a polymer contains a monomer, this is interpreted as the same as when a polymer contains the monomer as a monomer unit.

[0026] In this specification, unless otherwise specified, the term "polymer" is understood to be used in a broad sense that includes copolymers.

[0027] In this specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are the molecular weights in terms of polystyrene measured by Gel Permeation Chromatography (GPC) using various degrees of polymerization of monodisperse polystyrene polymers (standard samples) commercially available for molecular weight measurement as the standard substances. In this specification, unless otherwise specified, the molecular weight means the weight-average molecular weight.

[0028] Hereinafter, a detailed description will be given with reference to the drawings so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement the present invention. However, the present invention may be realized in various different forms and is not limited to the following description.

[0029] One embodiment of this specification is a negative electrode composition containing a silicon-based active material; a void ensuring material; a linear conductive material; and a negative electrode binder, wherein the silicon-based active material contains one or more selected from the group consisting of SiOx (x = 0) and SiOx (0 < x < 2), and contains 90 parts by weight or more of the SiOx (x = 0) based on 100 parts by weight of the silicon-based active material, the void ensuring material is contained in an amount of 0.1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the negative electrode composition, and the weight ratio of the linear conductive material to the void ensuring material is 1:10 to 1:120.

[0030] The main feature of the negative electrode composition according to the present invention is that in a negative electrode applying a silicon-based active material to maximize the capacity, a certain content of a void ensuring material is used to simplify the void structure, which is a problem of pure Si, and the resulting conductive network problem is solved by including a specific content of a linear conductive material.

[0031] Hereinafter, a detailed description will be given of the negative electrode composition according to the present application. In one embodiment of the present application, the silicon-based active material includes one or more selected from the group consisting of SiOx (x = 0) and SiOx (0 < x < 2), and may contain 90 parts by weight or more of the SiOx (x = 0) based on 100 parts by weight of the silicon-based active material.

[0032] In another embodiment, based on 100 parts by weight of the silicon-based active material, the SiOx (x = 0) may be contained in an amount of 90 parts by weight or more, preferably 92 parts by weight or more, more preferably 93 parts by weight or more, and may be contained 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.

[0033] In one embodiment of the present application, the silicon-based active material may be SiOx (x = 0).

[0034] In one embodiment of the present application, the silicon-based active material may use particularly pure silicon (Si) as the silicon-based active material. Using pure silicon (Si) as the silicon-based active material may mean that, as described above, based on a total of 100 parts by weight of the silicon-based active material, pure Si (SiOx (x = 0)) not bonded to other particles or elements is included within the above range.

[0035] That is, the silicon-based active material according to the present application uses pure Si and has the characteristic that it can secure a higher lithium-containing capacity compared to the case of using SiOx (0 < x < 2). As a result, it can be excellent in rapid charging ability and capacity characteristics. However, since problems such as ensuring voids can occur in a pure Si negative electrode, it is mainly characterized by including the above-described void ensuring material and linear conductive material.

[0036] Meanwhile, the average particle size (D50) of the silicon-based active material of the present invention may be 5 μm to 10 μm, specifically 5.5 μm to 8 μm, and more specifically 6 μm to 7 μm. When the average particle size is within this range, the specific surface area of ​​the particles falls within an appropriate range, and the viscosity of the negative electrode slurry is formed within an appropriate range. This allows for smooth dispersion of the particles constituting the negative electrode slurry. Furthermore, when the size of the silicon-based active material is equal to or greater than the lower limit of the range, the contact area between the silicon particles and the conductive material is improved by the composite of the conductive material and the binder in the negative electrode slurry, increasing the likelihood of maintaining the conductive network and improving the capacity retention rate. Meanwhile, when the average particle size is within this range, excessively large silicon particles are excluded, resulting in a smooth negative electrode surface, thereby preventing non-uniform current density during charge and discharge.

[0037] In one embodiment of the present application, the silicon-based active material generally has a characteristic BET specific surface area. The BET specific surface area of ​​the silicon-based active material is preferably 0.01 m 2 / g~150.0m 2 / g, more preferably 0.1m 2 / g~100.0m 2 / g, particularly preferably 0.2m 2 / g~80.0m 2 / g, most preferably 0.2m 2 / g~18.0m 2 / g. The BET specific surface area is determined in accordance with DIN 66131 (using nitrogen).

[0038] In one embodiment of the present application, silicon-based active material can be, for example, in crystalline or amorphous form, and is preferably non-porous.Silicon particles are preferably spherical or shard particles.Alternatively, but less advantageously, silicon particles can have a fibrous structure or be in the form of silicon-containing film or coating.

[0039] In one embodiment of the present application, there is provided a negative electrode composition, in which the silicon-based active material is contained in an amount of 60 parts by weight or more based on 100 parts by weight of the negative electrode composition.

[0040] In another embodiment, the silicon-based active material may be included in an amount of 60 parts by weight to 95 parts by weight based on 100 parts by weight of the negative electrode composition.

[0041] In yet another embodiment, the silicon-based active material may be included in an amount of 60 parts by weight or more, preferably 60.5 parts by weight or more, more preferably 61 parts by weight or more, based on 100 parts by weight of the negative electrode composition, and may be included in an amount of 95 parts by weight or less, preferably 90 parts by weight or less, more preferably 85 parts by weight or less.

[0042] The negative electrode composition according to the present application uses a silicon-based active material with a significantly high capacity within the above range. That is, if the amount exceeds the above range, even if the combination of the linear conductive material and the void-securing material of the present invention is used, the life characteristics cannot be ensured and the cell performance evaluation results are poor. On the other hand, if the amount is less than the above range, the life characteristics can be ensured, but the capacity characteristics and energy density are significantly reduced, and when a negative electrode with the same capacity is produced, the thickness of the active material layer increases and the fast charging performance also deteriorates.

[0043] The present application uses a silicon-based active material in the above range that can control volume expansion and maximize capacity characteristics, and is characterized by optimizing the contents of the linear conductive material and void-securing material described below.

[0044] In one embodiment of the present application, the silicon-based active material may have a non-spherical shape, and the 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.

[0045] In this application, the circularity is determined by the following formula 1, where A is the area and P is the perimeter. [Formula 1] 4πA / P 2

[0046] In one embodiment of the present application, the negative electrode composition may include a void-providing agent. When using silicon-based active materials, lithium insertion and deintercalation must occur uniformly at the top and bottom of the electrode to ensure stable life. However, when conventional conductive materials are used, they block voids in the electrode structure, increasing the diffusion resistance of lithium ions. This resistance results in different degrees of electrode degradation during lithium insertion and deintercalation reactions at the top and bottom of the electrode.

[0047] In order to solve the above-mentioned problems, the negative electrode composition according to the present application is characterized in that it does not contain a dot-like conductive material and contains 0.1 parts by weight to 20 parts by weight of a void-forming material based on 100 parts by weight of the negative electrode composition.

[0048] In another embodiment, the negative electrode composition contains 0.1 parts by weight or more and 20 parts by weight or less, preferably 0.5 parts by weight or more and 19 parts by weight or less, and more preferably 0.7 parts by weight or more and 19 parts by weight or less, of a void-securing material, based on 100 parts by weight of the negative electrode composition.

[0049] In other words, by including the above-mentioned part by weight of a void-securing material that can secure voids between particles and is non-reactive with lithium ions, there is an advantage in that a void structure that can cause lithium ions to diffuse can be secured. The gap securing material may be non-conductive metal oxide particles.

[0050] In particular, when the void-forming material is used, even if a side reaction layer is partially formed on the active material, the void-forming material can secure the lithium ion pathway in the electrode, allowing the lithium ion to be uniformly distributed in the electrode. Furthermore, the inclusion of the content portion induces a uniform reaction at the upper and lower ends in the electrode, thereby ensuring the life stability of the electrode.

[0051] In one embodiment of the present application, there is provided a negative electrode composition, wherein the void filler is an inorganic oxide having lower reactivity with lithium than the silicon-based active material, i.e., the void filler may be an inorganic oxide having lower or no reactivity with lithium than the silicon-based active material.

[0052] In one embodiment of the present application, the gap-retaining material may be amorphous or crystalline.

[0053] In one embodiment of the present application, the gap securing material is an oxide that forms an oxide with a non-transition metal or that is low in reactivity with lithium ions, and any oxide can be used as long as it does not change in composition or structure due to the band structure between the electrode and the electrolyte even when charging and discharging is performed between the lithium ions and the silicon-based active material.

[0054] In one embodiment of the present application, the void-securing material may be Al2O3; CaO; CeO2; MgO; or ZrO2, but is not limited thereto as long as it can be used to secure voids in the negative electrode.

[0055] While graphite-based compounds have traditionally been used exclusively as negative electrode active materials, attempts to incorporate silicon-based active materials into them to increase capacity have been increasing in recent years as demand for high-capacity batteries has grown. However, even if the properties of silicon-based active materials are partially adjusted as described above, their volume can rapidly expand during charge / discharge processes, potentially damaging the conductive paths formed within the negative electrode active material layer.

[0056] Furthermore, when the dotted conductive material is removed as described above and the gap securing material is used in the weight parts described above, the gap securing material exhibits non-conductive characteristics, which may make it difficult to secure a conductive path.

[0057] Therefore, the present application may include a linear conductive material as the negative electrode composition, which has the characteristic of complementing the non-conductive gap-ensuring material and lowering the resistance of the electrode.

[0058] Generally, conventional silicon-based negative electrodes may contain both point-shaped conductive materials and sheet-shaped conductive materials.

[0059] In one embodiment of the present application, there is provided a negative electrode composition, wherein the negative electrode composition further comprises a negative electrode conductive material, and the negative electrode conductive material is included in an amount of 5 parts by weight to 15 parts by weight, based on 100 parts by weight of the negative electrode composition.

[0060] In another embodiment, the amount of the negative electrode conductive material may be 5 parts by weight or more and 15 parts by weight or less, preferably 13 parts by weight or less, based on 100 parts by weight of the negative electrode composition, or may be 5 parts by weight or more, specifically 7 parts by weight or more. In this case, the negative electrode conductive material may include a dot-like conductive material or a sheet-like conductive material.

[0061] The dot-like conductive material refers to a spherical or dot-like conductive material that can be used to improve the conductivity of the negative electrode, does not cause chemical changes, and is conductive. Specifically, the dot-like 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 derivatives, and preferably includes carbon black, which achieves high conductivity and excellent dispersibility.

[0062] The sheet-like conductive material can improve conductivity by increasing surface contact between silicon particles in the negative electrode and can also prevent the conductive path from being broken due to volume expansion, and can be referred to as a plate-like conductive material or a bulk-like conductive material. The sheet-like conductive material may include at least one selected from the group consisting of plate-like graphite, graphene, graphene oxide, and graphite flakes, and is preferably plate-like graphite.

[0063] First, when carbon black is used as a dot-like conductive material in a silicon-based anode, it has the advantage of being inexpensive in terms of processing cost, but to fulfill its function, it must be included in a high proportion in the anode composition. The need to use such a high proportion of dot-like conductive material has led to the problem of gas generation at high temperatures, which reduces the stability of the anode.

[0064] In addition, plate-shaped graphite used as a sheet-shaped conductive material has the advantages of being reasonably priced, having appropriate rigidity, and being flexible enough to act as a buffer when rolling a silicon-based negative electrode. It also has a high specific surface area, allowing for the formation of a conductive network between active materials. However, since a sheet-shaped conductive material must be contained in a certain amount relative to the silicon-based active material used, there are limitations on the amount of silicon-based active material that can be contained in the negative electrode active material, despite the above-mentioned properties. This has resulted in a problem of not being able to maximize capacity characteristics.

[0065] In one embodiment of the present application, the linear conductive material is characterized in that it includes single-walled carbon nanotubes (SWCNTs); and multi-walled carbon nanotubes (MWCNTs).

[0066] In the present application, the SWCNTs have a specific surface area of ​​900 m 2 / g~1500m 2 / g and the mean diameter may be 0.5 μm or more and 3 μm or less.

[0067] SWCNTs are long and have a high specific surface area, making them ideal for forming a conductive network between silicon-based active materials. However, they are very expensive, and if excessive SWCNTs are used, the stiffness decreases due to the presence of a SWCNT dispersant.

[0068] In the present application, the MWCNT has a specific surface area of ​​100 m2 / g~500m 2 / g, and the mean diameter may be 10 μm or more and 20 μm or less.

[0069] In one embodiment of the present application, the MWCNT may have 5 to 20 walls.

[0070] Although MWCNTs have a smaller specific surface area and are shorter in length than SWCNTs, they are superior in performance to the dot-like conductive materials and sheet-like conductive materials.

[0071] In this application, SWCNTs have a high specific surface area and a large aspect ratio, while MWCNTs are used in a bundled form and are located on the surface of the silicon-based active material, making it difficult to connect the active materials. That is, SWCNTs are used for long-distance connections, while MWCNTs are used for mixing with the surface of the particles and the binder composite.

[0072] In one embodiment of the present application, there is provided a negative electrode composition, wherein the linear conductive material is contained in an amount of 0.1 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of the negative electrode composition.

[0073] In another embodiment, the linear conductive material may be included in an amount of 0.1 parts by weight to 5 parts by weight, preferably 0.15 parts by weight to 4 parts by weight, and more preferably 0.15 parts by weight to 1.0 parts by weight, based on 100 parts by weight of the negative electrode composition.

[0074] In one embodiment of the present application, the negative electrode composition contains a linear conductive material and satisfies the above-described composition and ratio, which does not significantly affect the life characteristics of conventional lithium secondary batteries, increases the number of points at which charging and discharging are possible, and provides the characteristics of excellent output characteristics at high C-rates.

[0075] In one embodiment of the present application, there is provided a negative electrode composition, in which the total weight of the gap securing material and the linear conductive material is 0.1 parts by weight or more and 30 parts by weight or less, based on 100 parts by weight of the negative electrode composition.

[0076] In another embodiment, based on 100 parts by weight of the negative electrode composition, the total weight of the gap securing material and the linear conductive material may be 0.1 parts by weight or more and 30 parts by weight or less, preferably 0.5 parts by weight or more and 25 parts by weight or less, and more preferably 0.7 parts by weight or more and 20 parts by weight or less.

[0077] The above weight parts represent the optimal ratio for ensuring voids and conductive paths, and are characterized by being able to ensure the capacity characteristics of a pure Si negative electrode as well as the life characteristics and rapid charging characteristics.

[0078] The negative electrode conductive material according to the present application has a completely different structure from the positive electrode conductive material used in the positive electrode. That is, the negative electrode conductive material according to the present application serves as a contact point between silicon-based active materials, which undergo a very large volume expansion of the electrode upon charge and discharge, while the positive electrode conductive material serves as a buffer during rolling and also serves to impart some conductivity, and therefore has a completely different structure and role from the negative electrode conductive material of the present invention.

[0079] Furthermore, the negative electrode conductive material according to the present application is applied to a silicon-based active material and has a completely different structure from conductive materials applied to graphite-based active materials. That is, conductive materials used in electrodes having graphite-based active materials simply have smaller particles than the active material, and therefore have the properties of improving output characteristics and imparting some conductivity, and are completely different in structure and role from negative electrode conductive materials applied together with silicon-based active materials as in the present invention.

[0080] In one embodiment of the present application, there is provided a negative electrode composition, wherein the negative electrode binder includes one or more selected from the group consisting of a rubber-based binder and a water-based binder.

[0081] 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, polyacrylic acid, and substances in which hydrogen is substituted with Li, Na, Ca, or the like, or may include various copolymers thereof.

[0082] The negative electrode binder according to one embodiment of the present application plays a role in holding the active material and the conductive material together to prevent distortion and structural deformation of the negative electrode structure when the silicon-based active material expands and relaxes in volume. Any common binder can be used as long as it fulfills the above role. Specifically, a water-based binder may be used, and more specifically, a PAM-based binder may be used.

[0083] In one embodiment of the present application, there is provided a negative electrode for a lithium secondary battery, wherein the negative electrode binder includes a water-based binder, and the negative electrode binder is present in an amount of 5 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the negative electrode composition.

[0084] In another embodiment, the amount of the negative electrode binder may be 5 parts by weight or more and 15 parts by weight or less, preferably 7 parts by weight or more and 13 parts by weight or less, and 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 composition.

[0085] In one embodiment of the present application, the negative electrode binder may be included in an amount of 3 parts by weight to 10 parts by weight based on 100 parts by weight of the silicon-based active material.

[0086] In another embodiment, based on 100 parts by weight of the silicon-based active material, the amount of 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 10 parts by weight or less, and more preferably 5 parts by weight or more and 10 parts by weight or less.

[0087] In the case of the negative electrode for a lithium secondary battery according to the present application, the silicon-based active material is used in the aforementioned amount by weight to maximize capacity characteristics, and the volume expansion during charge and discharge is greater than when a conventional carbon-based active material is used as the main active material. Therefore, by including the aforementioned amount of the negative electrode binder, the volume expansion of the highly rigid silicon-based active material during charge and discharge can be efficiently suppressed.

[0088] In one embodiment of the present application, there is provided a negative electrode for a lithium secondary battery, comprising: a negative electrode current collector layer; and a negative electrode active material layer formed on one or both surfaces of the negative electrode current collector layer, the negative electrode active material layer comprising the negative electrode composition according to the present application.

[0089] 1 is a diagram showing the laminated structure of a negative electrode for a lithium secondary battery according to one embodiment of the present application. Specifically, a negative electrode for a lithium secondary battery 100 can be seen, which includes a negative electrode active material layer 20 on one side of a negative electrode current collector layer 10. While FIG. 1 shows the negative electrode active material layer formed on one side, it may be formed on both sides of the negative electrode current collector layer.

[0090] In one embodiment of the present application, the negative electrode for a lithium secondary battery may be formed by applying a negative electrode slurry containing the negative electrode composition to one or both surfaces of a negative electrode current collector layer, followed by drying.

[0091] In this case, the negative electrode slurry may include the above-described negative electrode composition and a slurry solvent.

[0092] In one embodiment of the present application, the solid content of the negative electrode slurry may be 5% or more and 55% or less.

[0093] In another embodiment, the solid content of the negative electrode slurry may be in the range of 5% to 55%, preferably 7% to 35%, more preferably 10% to 30%.

[0094] The solid content of the negative electrode slurry refers to the content of the negative electrode composition contained in the negative electrode slurry, and may refer to the content of the negative electrode composition based on 100 parts by weight of the negative electrode slurry.

[0095] When the solid content of the negative electrode slurry satisfies the above range, the viscosity during the formation of the negative electrode active material layer is appropriate, and particle aggregation of the negative electrode composition is minimized, resulting in efficient formation of the negative electrode active material layer. In addition, the negative electrode composition according to the present application includes a linear conductive material and a high content of a silicon-based active material, and is characterized by excellent fast charging performance and cell performance.

[0096] In one embodiment of the present application, the slurry solvent can be any solvent that can dissolve the negative electrode composition, and specifically, water, acetone, or NMP may be used.

[0097] 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 does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, or an aluminum-cadmium alloy may be used. Furthermore, the surface may be formed with fine irregularities to strengthen the binding force of the negative electrode active material, and the negative electrode current collector layer may be used in various forms such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0098] In one embodiment of the present application, there is provided a negative electrode for a lithium secondary battery, 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 10 μm or more and 500 μm or less.

[0099] In the present application, the negative electrode active material layer may refer to the thickness of a single negative electrode active material layer formed on one side of a negative electrode current collector layer.

[0100] However, the thickness may vary depending on the type and application of the negative electrode used, and is not limited thereto.

[0101] In one embodiment of the present application, the porosity of the negative electrode active material layer may be in the range of 30% or more and 60% or less.

[0102] In another embodiment, the porosity of the negative electrode active material layer may satisfy the range of 30% to 60%, preferably 35% to 55%, more preferably 39% to 54%.

[0103] The porosity varies depending on the composition and content of the silicon-based active material, conductive material, and binder contained in the negative electrode active material layer. In particular, the silicon-based active material, void-retaining material, and linear conductive material according to the present application are contained in specific compositions and content portions to satisfy the above range, thereby providing the electrode with an appropriate range of electrical conductivity and resistance.

[0104] In one embodiment of the present application, there is provided a lithium secondary battery comprising: 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.

[0105] 2 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 anode 100 including an anode active material layer 20 on one side of an anode current collector layer 10 can be seen, and a lithium secondary battery cathode 200 including a cathode active material layer 40 on one side of a cathode current collector layer 50 can be seen, and the lithium secondary battery anode 100 and lithium secondary battery cathode 200 are shown stacked with a separator 30 interposed therebetween.

[0106] A secondary battery according to an embodiment of the present specification may include, in particular, 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 negative electrode has been described above, detailed description thereof will be omitted.

[0107] 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.

[0108] The positive electrode current collector in the positive electrode is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like may be used. The positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to enhance the adhesive strength of the positive electrode active material. The positive electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0109] The 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) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; 1+c1 Mn 2-c1O4 (0≦c1≦0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, and Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by the chemical formula LiMnO2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and 0.01≦c2≦0.3 is satisfied); 2-c3 M c3 Examples of the lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO8 (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 Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); and LiMn2O4, in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion. The positive electrode may be metallic lithium (Li-metal).

[0110] The positive electrode active material layer may contain a positive electrode conductive material and a positive electrode binder in addition to the above-described positive electrode active material.

[0111] In this case, the positive electrode conductive material is used to impart conductivity to the electrode, and can be any material that has electronic conductivity without causing chemical changes in the battery that is constructed. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives. These may be used alone or in combination of two or more.

[0112] The positive electrode binder serves to improve adhesion between particles of the positive electrode active material and 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, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof. These may be used alone or in combination.

[0113] The separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator typically used in secondary batteries can be used without particular limitation. It is particularly preferable that the separator exhibits low resistance to electrolyte ion migration and excellent electrolyte humidification. Specifically, porous polymer films, such as those made from polyolefin polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers, or laminated structures of two or more layers thereof, may be used. Conventional porous nonwoven fabrics, such as nonwoven fabrics made from high-melting-point glass fibers or polyethylene terephthalate fibers, may also be used. To ensure heat resistance or mechanical strength, a separator coated with a ceramic component or a polymeric material may be used, and may be selectively used as a single-layer or multi-layer structure.

[0114] 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 manufacturing lithium secondary batteries. Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0115] Examples of the non-aqueous organic solvent that can be used 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, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate.

[0116] In particular, among the carbonate organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, can be preferably used as high-viscosity organic solvents, because they have a high dielectric constant and dissociate lithium salts well. When such cyclic carbonates are mixed in an appropriate ratio with linear carbonates having low viscosity and low dielectric constants, such as dimethyl carbonate and diethyl carbonate, an electrolyte having high electrical conductivity can be prepared, and therefore such cyclic carbonates can be used even more preferably.

[0117] The metal salt may be a lithium salt, which is a substance that is easily dissolved in the non-aqueous electrolyte. For example, the anion of the lithium salt may be 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:

[0118] In addition to the constituent components of the electrolyte, the electrolyte may further include one or more additives, such as a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride, in order to improve the life characteristics of the battery, suppress a decrease in battery capacity, and improve the discharge capacity of the battery.

[0119] 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 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. [Example]

[0120] Below, preferred examples are presented to help understand the present invention, but these examples are merely illustrative of the present description, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present description, and it goes without saying that such changes and modifications fall within the scope of the appended claims.

[0121] <Production example> <Production of negative electrodes> Example 1 A silicon-based active material, Si (average particle size (D50): 5 μm), a void-securing material (Al2O3), a second conductive material, SWCNT as a linear conductive material, and polyacrylamide (PAM) as a binder were added in a weight ratio of 79:0.75:10:0.25:10 to distilled water as a solvent for forming a negative electrode slurry to produce a negative electrode slurry (solid concentration 28 wt%).

[0122] The SWCNTs have a BET specific surface area of ​​1000 m 2 / g~1500m 2 The SWCNTs satisfied the above-mentioned requirements: 1.0 μm / g, 2.0 μm or more in aspect ratio, and 1.0 μm or more in average diameter. As the SWCNTs, a solution in which they were dispersed in CMC was used. As the second conductive material, plate-like graphite (specific surface area: 17 m) was used. 2 / g, average particle size (D50): 3.5 μm) was used.

[0123] Specifically, the SWCNTs, second conductive material, void-securing material, binder, and water were dispersed using a homomixer at 2500 rpm for 30 minutes, and then the silicon-based active material was added and dispersed at 2500 rpm for 30 minutes to prepare a negative electrode slurry.

[0124] The negative electrode current collector layer was made of a copper current collector (thickness: 15 μm) and the negative electrode slurry was applied to both sides of the copper current collector at a rate of 87.7 mg / 25 cm. 2 The coated layer was rolled and dried in a vacuum oven at 130°C for 10 hours to form a negative electrode active material layer (thickness: 27 µm), which was used as a negative electrode (thickness of negative electrode: 42 µm).

[0125] A negative electrode was prepared in the same manner as in Example 1, except that the weight parts were changed as shown in Table 1 below.

[0126] [Table 1]

[0127] In Table 1, the porosity of the negative electrode, including the volume of the gap securing material, was calculated as follows.

[0128]

number

[0129] <Comparative Example 5> The silicon-based active material was Si (average particle size (D50): 5 μm), the linear conductive material was SWCNT, and the carbon black C (specific surface area: 58 m 2 / g, diameter: 37 nm), the second conductive material, and polyacrylamide (PAM) as a binder were added in a weight ratio of 70:9.79:10:0.21:10 to distilled water as a solvent for forming a negative electrode slurry to prepare a negative electrode slurry (solid concentration: 28 wt%).

[0130] The SWCNTs have a BET specific surface area of ​​1000 m 2 / g~1500m 2 / g, an aspect ratio of 10000 or more, and an average diameter of 1.0 μm or more. The SWCNTs were used as a solution dispersed in CMC.

[0131] Specifically, the SWCNTs, carbon black C, binder, and water were dispersed using a homomixer at 2500 rpm for 30 minutes, and then the silicon-based active material was added and dispersed at 2500 rpm for 30 minutes to prepare a negative electrode slurry.

[0132] The negative electrode current collector layer was made of a copper current collector (thickness: 26 μm) and the negative electrode slurry was applied to both sides of the copper current collector at a rate of 87.7 mg / 25 cm. 2The coated layer was rolled and 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 a negative electrode (thickness of negative electrode: 41 µm).

[0133] <Comparative Example 6> Silicon-based active materials include Si (average particle size (D50): 5 μm) and carbon black C (specific surface area: 58 m 2 / g, diameter: 37 nm), a void-retaining material, and polyacrylamide (PAM) as a binder were added in a weight ratio of 70:10:10:10 to distilled water as a solvent for forming a negative electrode slurry to prepare a negative electrode slurry (solid concentration: 28 wt%).

[0134] Specifically, the carbon black C, the void-retaining agent, the binder, and the water were dispersed using a homomixer at 2500 rpm for 30 minutes, and then the silicon-based active material was added and dispersed at 2500 rpm for 30 minutes to prepare a negative electrode slurry.

[0135] The negative electrode current collector layer was made of a copper current collector (thickness: 26 μm) and the negative electrode slurry was applied to both sides of the copper current collector at a rate of 87.7 mg / 25 cm. 2 The coated layer was rolled and 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 a negative electrode (thickness of negative electrode: 41 µm).

[0136] <Experimental Example> Experimental example 1: Life evaluation of mono-cell The secondary batteries including the negative electrodes prepared in the Examples and Comparative Examples were subjected to a lifespan evaluation using an electrochemical charger / discharger to evaluate the capacity retention. The secondary batteries were subjected to an in-situ cycle test at 4.2-3.0 V and 1 C / 0.5 C, and the capacity retention was measured every 50 cycles during the test by charging / discharging at 0.33 C / 0.33 C (4.2-3.0 V). The results are shown in Table 2.

[0137] Lifetime retention rate (%) = {(discharge capacity at Nth cycle) / (discharge capacity at first cycle)} × 100

[0138] [Table 2]

[0139] Experimental Example 2: Tortuosity Evaluation After preparing a symmetric coin cell with the same electrode on each electrode, the ionic resistance (R ion ) was measured. From this ionic resistance, the tortuosity was calculated using the following formula:

[0140]

number

[0141] In the above formula, τ is the void tortuosity, R ion is the ionic resistance, ε is the porosity of the electrode, A is the area of ​​the electrode, κ is the conductivity of the electrolyte, and t is the thickness of the electrode.

[0142] [Table 3]

[0143] The void tortuosity rating is an index that indicates how easily ions can be transferred through the void pathways in the electrode, and the lower the rating, the easier it is for actual electrochemical reaction participants to penetrate into the electrode. In this case, it is possible to secure voids in the electrode through a void-securing material, and as the porosity increases, the number of paths through which the electrolyte can move increases, indicating an improved void tortuosity (in the table above, the lower the void tortuosity rating, the more improved it is).

[0144] Experimental Example 3: Initial cycle @SOC50 2.5C 0.1s discharge resistance evaluation (electrode resistance measurement using a mono cell) In Experimental Example 1, the capacity retention rate was measured after 50 cycles of 0.33C / 0.33C charge / discharge (4.2-3.0V) during the test, and then the resistance was measured for a certain period of time (0.1 s) when discharging at a 2.5C pulse at SOC50. The results are shown in Table 4 below.

[0145] [Table 4]

[0146] Experimental Example 4: Measurement and evaluation of electrode conductivity The electrode resistance was measured using the four-point probe measurement method. Specifically, as can be seen in Figure 3, DC was applied between the two outer probes of four equally spaced probes, and the voltage drop was measured through the two inner probes. The resistance was calculated from the current and voltage values. The electrode conductivity was then calculated using the calculated resistance value and the distance between the probes, and the results are shown in Table 5 below.

[0147] [Table 5]

[0148] Experimental example 5: PC penetration experiment A fixed amount (10 ml) of PC (propylene carbonate) was injected via syringe onto the surface of a punched electrode of a fixed area, leaving droplets of PC on the surface. The container was then covered to prevent the injected PC from evaporating, and the time it took for the solvent to completely penetrate the electrode and for the droplets to disappear was compared. The results are shown in Table 6.

[0149] [Table 6]

[0150] As can be seen from Examples 1 to 8, the present application is characterized by the inclusion of a gap-securing material that can maintain the porosity of the electrode and maximize the diffusion of lithium ions. This allows the conventional conductive dot-like material to be removed and the gap-securing material to be used, which has the advantage of being located between particles in the electrode, thereby securing voids that allow the diffusion of lithium ions to occur.

[0151] In addition, the void-securing material is a non-conductor and a certain content is used to secure the voids, but a linear conductive material is further included to complement the void-securing material and reduce the resistance of the electrode. This allows the voids to be maintained even during lithium insertion / extraction in a pure Si electrode, and also ensures conductivity, thereby reducing the resistance of the electrode.

[0152] That is, the negative electrode composition according to the present invention is characterized in that, in a negative electrode in which a silicon-based active material is used to maximize capacity, a certain amount of void-securing material is used to simplify the void structure, which is a problem with pure Si, and the resulting conductive network problem is solved by including a specific amount of linear conductive material.

[0153] Comparative Examples 1 and 2 correspond to cases where a gap securing material is included but the ratio of linear conductive material to gap securing material according to the present application is not met, and Comparative Examples 3 and 4 correspond to cases where a gap securing material is included but the content exceeds the weight according to the present application. Comparative Example 5 corresponds to a case where a gap securing material is not included. Furthermore, Comparative Example 6 corresponds to a case where a linear conductive material and a gap securing material are not used, but where a point-like conductive material and a gap securing material are used without a linear conductive material.

[0154] In this case, compared to the Examples, it was confirmed that Comparative Examples 1 and 2 contained a small amount of the void-securing material, which can secure voids between particles and is not reactive with lithium ions, and was unable to fully fulfill its role, making it difficult to secure a void structure and resulting in poor evaluation results, while Comparative Examples 3 and 4 contained a large amount of the void-securing material, which is a non-conductor, and even though they contained linear conductive material, it was difficult to secure conductivity and resulting in poor evaluation results.

[0155] In Comparative Example 5, no void-securing material was used, making it difficult to secure the desired void structure. In Comparative Example 6, dot-shaped conductive material was used instead of linear conductive material. In this case, a side reaction layer was formed on the dot-shaped conductive material at the level of several tens of nanometers, which blocked the voids. As a result, lithium ions could not enter the lower end of the electrode, resulting in uneven lithium ion distribution at the upper and lower ends. As a result, it was confirmed that the silicon at the upper end was charged more than the depth of charge, causing cracks in the active material and reducing the life stability of the electrode. [Explanation of symbols]

[0156] 10 Negative electrode current collector layer 20...Negative electrode active material layer 30 Separator 40...Cathode active material layer 50 Positive electrode current collector layer 60 External probe 70 Internal probe 100 ···Negative electrode for lithium secondary battery 200 ···Positive electrode for lithium secondary battery

Claims

1. A negative electrode composition comprising: a silicon-based active material; a void-securing material; a linear conductive material; and a negative electrode binder, The silicon-based active material includes one or more selected from the group consisting of SiOx (x=0) and SiOx (0<x<2), and the silicon-based active material includes 90 parts by weight or more of the SiOx (x=0) based on 100 parts by weight of the silicon-based active material; The void-securing agent is included in an amount of 0.1 parts by weight to 20 parts by weight based on 100 parts by weight of the negative electrode composition, The weight ratio of the linear conductive material to the gap securing material is 1:2 to 1:

120.

2. The negative electrode composition according to claim 1 , wherein the silicon-based active material is included in an amount of 60 parts by weight or more based on 100 parts by weight of the negative electrode composition.

3. The negative electrode composition according to claim 1 , wherein the total weight of the gap securing material and the linear conductive material is 0.1 parts by weight or more and 30 parts by weight or less, based on 100 parts by weight of the negative electrode composition.

4. The negative electrode composition according to claim 1 , wherein the linear conductive material is present in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the negative electrode composition.

5. The negative electrode composition according to claim 1 , wherein the linear conductive material is SWCNT or MWCNT.

6. The MWCNT has a specific surface area of ​​100 m ２ / g to 500m ２ / g, The negative electrode composition according to claim 5 , wherein the mean diameter is 10 μm or more and 20 μm or less.

7. The SWCNT has a specific surface area of ​​900 m ２ / g~1500m ２ / g, The negative electrode composition according to claim 5 , wherein the mean diameter is 0.5 μm or more and 3 μm or less.

8. The negative electrode composition according to claim 1 , wherein the negative electrode binder comprises at least one selected from the group consisting of a rubber-based binder and a water-based binder.

9. The negative electrode composition further includes a negative electrode conductive material, The negative electrode composition according to claim 1 , wherein the negative electrode conductive material is contained in an amount of 5 parts by weight to 15 parts by weight based on 100 parts by weight of the negative electrode composition.

10. 2. The negative electrode composition according to claim 1, wherein the void-securing material is an inorganic oxide having lower reactivity with lithium than the silicon-based active material.

11. a negative electrode current collector layer; and a negative electrode active material layer comprising the negative electrode composition according to any one of claims 1 to 10, formed on one or both surfaces of the negative electrode current collector layer; A negative electrode for a lithium secondary battery comprising:

12. the negative electrode current collector layer has a thickness of 1 μm or more and 100 μm or less, 12. The negative electrode for a lithium secondary battery according to claim 11, wherein the thickness of the negative electrode active material layer is 10 μm or more and 500 μm or less.

13. The negative electrode for a lithium secondary battery according to claim 11, wherein the porosity of the negative electrode active material layer is 30% or more and 60% or less.

14. positive electrode; The negative electrode for a lithium secondary battery according to claim 11; a separator disposed between the positive electrode and the negative electrode; and Electrolyte; A lithium secondary battery comprising:

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