Title of Invention: Composite negative active material, manufacturing method thereof, and negative electrode comprising same technical field [One] Cross Citation with Related Applications [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0120840 dated September 30, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification. [3] technical field [4] The present invention relates to a composite anode active material, a manufacturing method thereof, and an anode comprising the same. background [5] Recently, with the rapid spread of electronic devices using batteries, such as mobile phones, notebook computers, and electric vehicles, the demand for small, lightweight and relatively high-capacity secondary batteries is rapidly increasing. In particular, a lithium secondary battery has been in the spotlight as a driving power source for a portable device because it is lightweight and has a high energy density. Accordingly, research and development efforts for improving the performance of lithium secondary batteries are being actively conducted. [6] In general, a lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte, an organic solvent, and the like. In addition, the positive electrode and the negative electrode may have an active material layer including a positive electrode active material or a negative electrode active material on a current collector. Lithium-containing metal oxides such as LiCoO 2 and LiMn 2 O 4 are generally used for the positive electrode as a positive electrode active material, and thus, a carbon-based active material and a silicon-based negative active material that do not contain lithium are used as the negative electrode active material for the negative electrode. [7] In particular, among the negative active materials, silicon-based negative active materials are attracting attention in that they have a capacity that is about 10 times higher than that of carbon-based negative active materials. However, the silicon-based negative active material has not been widely used due to the problem of volume expansion due to charging and discharging, cracking/damage of the active material particles, and deterioration of the lifespan properties thereof. [8] In particular, the silicon-based negative active material has problems in that the distance between the active materials increases and an electrical short occurs due to volume expansion/contraction due to charging and discharging, and accordingly, the passage of charge is lost and lithium ions are isolated, thereby reducing the capacity and Lifespan deterioration can be accelerated. [9] Therefore, there is a need for the development of a secondary battery capable of improving the lifespan characteristics while realizing the high capacity and energy density of the silicon-based anode active material. [10] Korean Patent Laid-Open No. 10-2017-0074030 relates to a negative active material for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery including the same, and discloses a negative active material including a porous silicon-carbon composite, but solves the above problems There is a limit to solving it. [11] [Prior art literature] [12] [Patent Literature] [13] Korean Patent Publication No. 10-2017-0074030 DETAILED DESCRIPTION OF THE INVENTION technical challenge [14] One object of the present invention is to provide a composite anode active material capable of effectively preventing an electrical short circuit between active materials due to charging and discharging when using a silicon-based active material and improving lifespan characteristics. [15] In addition, another object of the present invention is to provide a method for manufacturing the above-described composite negative active material. [16] In addition, another object of the present invention is to provide an anode including the above-described composite anode active material. means of solving the problem [17] The present invention is a silicon-based core particle; an outer carbon coating layer positioned on the silicon-based core particle; a first single-walled carbon nanotube in contact with the outer carbon coating layer and protruding from the outer carbon coating layer; a conductive structure spaced apart from the outer carbon coating layer and including a second single-walled carbon nanotube; and a crosslinking material bonded to at least one of the first single-walled carbon nanotube and the second single-walled carbon nanotube, wherein at least one of the second single-walled carbon nanotubes is the first single-walled carbon nanotube Provided is a composite anode active material that is crosslinked by the tube and the crosslinking material to connect the conductive structure and the first single-walled carbon nanotube to each other. [18] In addition, the present invention comprises the steps of mixing a silicon-based core particle, a precursor for forming an outer carbon coating layer, two or more single-walled carbon nanotubes, and a crosslinking material; and heat-treating the mixture. [19] In addition, the present invention is a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer provides a negative electrode including a negative electrode material including the above-described composite negative active material, a binder, and a conductive material. Effects of the Invention [20] The composite anode active material of the present invention includes silicon-based core particles; an outer carbon coating layer positioned on the silicon-based core particle; a first single-walled carbon nanotube in contact with the outer carbon coating layer and protruding from the outer carbon coating layer; a conductive structure spaced apart from the outer carbon coating layer and including a second single-walled carbon nanotube; and a crosslinking material bonded to at least one of the first single-walled carbon nanotube and the second single-walled carbon nanotube, wherein at least one of the second single-walled carbon nanotubes is the first single-walled carbon nanotube It is crosslinked by the tube and the crosslinking material to connect the conductive structure and the first single-walled carbon nanotube to each other. The conductive structure is connected to and fixed to the outer carbon coating layer by a cross-linked structure of the first single-walled carbon nanotube and the second single-walled carbon nanotube. Since the conductive structure is connected to and fixed to the outer carbon coating layer, a conductive network in the anode can be uniformly and stably formed, thereby improving the lifespan characteristics of the anode and the secondary battery. In addition, since the conductive structure is exposed to the outside of the composite anode active material to form a conductive network to prevent an electrical short circuit between the active materials, even if volume expansion/contraction occurs due to charging and discharging of the active material, it is possible to prevent an electrical short between the active materials. The crosslinking material serves as a crosslinking agent for crosslinking the two or more single-walled carbon nanotubes (first single-walled carbon nanotubes and/or second single-walled carbon nanotubes), and single-walled carbon nanotubes It can help to form a more stable and uniform conductive network by the [21] In addition, according to the manufacturing method of the above-described composite anode active material of the present invention, after mixing the silicon-based core particles, the precursor for forming an outer carbon coating layer, two or more single-walled carbon nanotubes, and a crosslinking material, the composite anode active material is compounded by heat treatment to manufacture By this process, the above-mentioned composite negative active material can be manufactured, and by the complexing by the heat treatment, the conductive structure including the second single-walled carbon nanotube is applied to the outer carbon coating layer by the first single-walled carbon nanotube. attachable, and allow the conductive structure to form a conductive network between the active materials. Brief description of the drawing [22] 1 is a cross-sectional view schematically illustrating a composite anode active material according to the present invention. [23] 2 is an SEM photograph of the negative electrode of Example 1. FIG. [24] 3 is an SEM photograph of the negative electrode of Comparative Example 4. Modes for carrying out the invention [25] The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention. [26] The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. [27] In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the presence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, elements, or combinations thereof. [28] In the present specification, the average particle diameter (D 50 ) may be defined as a particle diameter corresponding to 50% of the cumulative volume in the particle size distribution curve of the particles. The average particle diameter (D 50 ) may be measured using, for example, a laser diffraction method. In general, the laser diffraction method can measure a particle diameter of several mm from a submicron region, and can obtain results of high reproducibility and high resolution. [29] Hereinafter, the present invention will be described in detail. [30] [31] [32] The present invention relates to a composite anode active material. The composite negative active material may be preferably used in a lithium secondary battery. [33] Hereinafter, the composite negative active material of the present invention will be described in detail with reference to the drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted. [34] 1 is a cross-sectional view schematically illustrating a composite anode active material 10 of the present invention. [35] Referring to FIG. 1 , the composite anode active material 10 of the present invention includes silicon-based core particles 100 ; an outer carbon coating layer 200 positioned on the silicon-based core particle 100; a first single-walled carbon nanotube 300 in contact with the outer carbon coating layer 200 and protruding from the outer carbon coating layer 200; a conductive structure 400 spaced apart from the outer carbon coating layer 200 and including a second single-walled carbon nanotube 450; and a crosslinking material 500 bonded to at least one of the first single-walled carbon nanotube 300 and the second single-walled carbon nanotube 450; including, the second single-walled carbon nanotube (450) ) is cross-linked by the first single-walled carbon nanotube 300 and the cross-linking material 500 to connect the conductive structure 400 and the first single-walled carbon nanotube 300 to each other characterized in that [36] In general, silicon-based anode active materials are known to have about 10 times higher capacity than carbon-based active materials. Accordingly, when silicon-based anode active materials are applied to anodes, thin-film electrodes having a high level of energy density even with a thin thickness are difficult to achieve. is expected to be possible. However, the silicon-based negative active material has a problem of deterioration in lifespan due to volume expansion/contraction according to insertion/desorption of lithium according to charging and discharging. In particular, when the silicon-based active material undergoes volume expansion/contraction due to charging and discharging, electrical contact deteriorates due to an increase in the distance between the active materials and an electrical short circuit occurs, which results in loss of the passage of charge and isolation of lithium ions. This may cause rapid deterioration of the lifespan of the anode and decrease in capacity. [37] In order to solve this problem, the composite anode active material of the present invention includes a silicon-based core particle, an outer carbon coating layer positioned on the silicon-based core particle, and a first single-walled carbon nanotube (hereinafter, the first single-walled carbon nanotube partially attached to the outer carbon coating layer). 1 SWCNT), a conductive structure including a second single-walled carbon nanotube (hereinafter referred to as a second SWCNT), and a crosslinking material, wherein the first SWCNT comprises at least one of the second SWCNTs and A conductive structure spaced apart from the outer carbon coating layer by being crosslinked by a crosslinking material may be connected to and fixed to the outer carbon coating layer by the first SWCNT. Since the conductive structure is connected to and fixed to the outer carbon coating layer, a conductive network in the anode can be uniformly and stably formed, thereby improving the lifespan characteristics of the anode and the secondary battery. In addition, since the conductive structure is exposed to the outside of the composite anode active material to form a conductive network to prevent an electrical short circuit between the active materials, even if volume expansion/contraction occurs due to charging and discharging of the active material, it is possible to prevent an electrical short between the active materials. The crosslinking material serves as a crosslinking agent for crosslinking the two or more SWCNTs (the first SWCNTs and/or the second SWCNTs), so that the conductive network by the SWCNTs can be formed at a more stable and uniform level. can help [38] In addition, while being spaced apart from the outer carbon coating layer, in the conductive structure connected and fixed to the outer carbon coating layer, even if the silicon-based core particles expand in volume due to charging and discharging, an electrical short circuit between the active materials is prevented due to the formation of a conductive network of the conductive structure. and, accordingly, the lifespan characteristics of the anode can be improved, and resistance can be reduced. [39] In addition, according to the present invention, since the conductive structure is connected to and fixed to the outer carbon coating layer by the first SWCNT, when the composite negative active material is included in the negative electrode, the conductive structure can be uniformly disposed in the negative electrode, Accordingly, it is possible to form a uniform and stable conductive network in the cathode. [40] [41] The silicon-based core particle 100 is capable of insertion/desorption of lithium, and may function as a core particle of the composite anode active material. [42] The silicon-based core particle 100 may include a compound represented by Formula 1 below. [43] [Formula 1] [44] M x SiO y [45] In Formula 1, M is at least one selected from the group consisting of Li, Mg, and Al, and may be 0≤x≤4, and 0≤y<2. [46] In Formula 1, SiO 2 (where x=0 and y=2 in Formula 1) does not react with lithium ions and cannot store lithium, so y is preferably within the above range. Specifically, y may be 0.5≤y≤1.5 in terms of structural stability of the active material in Formula 1 above. [47] In Formula 1, M may be contained in terms of increasing the efficiency of the active material by lowering the ratio of the irreversible phase (eg, SiO 2 ) of the silicon-based core particle, and is selected from the group consisting of Li, Mg, and Al. It may be at least one type, preferably at least one type selected from the group consisting of Li and Mg, and more preferably Mg. In Formula 1, x may be 0 [99] In addition, the present invention provides a method for preparing the above-described composite negative electrode active material. [100] Specifically, the method of manufacturing a composite negative active material of the present invention comprises the steps of mixing a silicon-based core particle, a precursor for forming an outer carbon coating layer, two or more SWCNTs, and a crosslinking material; and heat-treating the mixture. [101] According to the manufacturing method of the composite negative electrode active material of the present invention, the outer carbon coating layer positioned on the silicon-based core particle is formed by mixing and heat-treating the silicon-based core particle, the precursor for forming an outer carbon coating layer, two or more SWCNTs, and a crosslinking material, A first SWCNT in contact with the outer carbon coating layer and protruding from the outer carbon coating layer, a conductive structure including a second SWCNT spaced apart from the outer carbon coating layer, the first SWCNT and the second SWCNT combined with at least one A crosslinking material may be formed simultaneously. At this time, at least one of the first SWCNTs and the second SWCNTs may be crosslinked with each other by the crosslinking material, so that the conductive structure and the first SWCNTs may be connected to each other, through which the above-described composite negative active material may be manufactured. have. [102] [103] The method of manufacturing a composite anode active material of the present invention includes mixing a silicon-based core particle, a precursor for forming an outer carbon coating layer, two or more SWCNTs, and a crosslinking material. [104] The silicone-based core particles and the type, characteristics, content, and the like of the cross-linking material have been described above. [105] The precursor for forming the outer carbon coating layer is a component capable of forming the outer carbon coating layer of the composite anode active material. [106] The precursor for forming the outer carbon coating layer is carboxy methyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), methyl hydroxypropyl cellulose (MHPC) ), ethyl hydroxyethyl cellulose (EHEC), methyl ethyl hydroxyethyl cellulose (methyl ethyl hydroxyethyl cellulose, MEHEC), and may be at least one selected from the group consisting of cellulose gum (cellulose gum), preferably It may be carboxymethyl cellulose. [107] In order to prepare the composite anode active material of the present invention, a process of mixing the crosslinking material with the silicon-based core particles, the precursor for forming the outer carbon coating layer, and two or more SWCNTs is required. If the crosslinking material is not added and the silicon-based core particles, the precursor for forming the outer carbon coating layer, and two or more SWCNTs are mixed and heat treated to form a composite, the SWCNTs are entirely or excessively on the surface of the silicon-based core and/or outer carbon coating layer. Due to the problem of adhesion, a part of the SWCNT body cannot be spaced apart or protrude from the outer carbon coating layer, and thus it is difficult to form the first SWCNT according to the composite anode active material of the present invention. The connection between the carbon coating layers is difficult. In addition, if the crosslinking material is not added, the silicon-based core particles, the precursor for forming the outer carbon coating layer, and two or more SWCNTs are mixed and heat-treated to form a composite, and even if an additional cross-linking material is added, the SWCNTs are already silicon-based core and / or since the outer carbon coating layer will be completely attached to the surface, the crosslinking material cannot crosslink two or more parts of the SWCNT body with each other, thus making it difficult to form a conductive structure according to the present invention. [108] [109] The method of manufacturing a composite negative active material of the present invention may further include forming an internal carbon coating layer on the silicon-based core particle before the mixing step. The internal carbon coating layer is formed on the silicon-based core particles, and may function as a protective layer that can appropriately control volume expansion according to charging and discharging of the silicon-based core particles and prevent side reactions with the electrolyte. [110] The step of forming the inner carbon coating layer may be performed by chemical vapor deposition (CVD), specifically, chemical vapor deposition (CVD) using at least one hydrocarbon gas selected from the group consisting of methane, ethane and acetylene. can be performed by According to the method, the internal carbon coating layer can be formed at a uniform level on the silicon-based core particles, so that the volume expansion of the silicon-based core particles can be smoothly controlled, and side reactions caused by the electrolyte can be prevented. [111] The forming of the inner carbon coating layer may be performed at 800°C to 1,100°C, preferably 900°C to 1,000°C. [112] Other descriptions of the inner carbon coating layer have been described above. [113] [114] The manufacturing method of the composite negative active material of the present invention includes the step of heat-treating the mixture. The composite negative active material according to the manufacturing method of the present invention may be composited by the heat treatment step. If the heat treatment is not performed on the mixture, the formation of the outer carbon coating layer, adhesion between the outer carbon coating layer and SWCNTs, and crosslinking between the SWCNTs and the crosslinking material cannot be smoothly performed. [115] Through the heat treatment, an outer carbon coating layer, a first SWCNT, a conductive structure (including a second SWCNT), and a crosslinking material may be formed. In particular, some of the SWCNTs included in the mixture are in contact with the outer carbon coating layer by the heat treatment to form a first SWCNT derived from the outer carbon coating layer, and the remainder of the SWCNTs included in the mixture are the second SWCNTs It is possible to form a conductive structure by the cross-linking material. At least one of the first SWCNTs and the second SWCNTs may be crosslinked by the crosslinking material to connect the conductive structure and the first SWCNTs to each other. Additionally, the crosslinking material may perform crosslinking between the first SWCNTs and the second SWCNTs, crosslinking between the first SWCNTs, and crosslinking between the second SWCNTs. [116] Specifically, the heat treatment may be performed by a spray-drying process. The spray drying process is a method of producing dry powder by rapidly heat-treating or drying a liquid feed with a high-temperature gas while spraying it. When the composite anode active material of the present invention is heat-treated by the spray drying process, rapid heat treatment or drying of the mixture is possible, preventing aggregation between particles and improving the quality uniformity of the composite anode active material, and SWCNT is a silicon-based core It is preferable in terms of preventing excessive adsorption to particles. [117] The spray drying process may be performed by injecting an inert gas at a temperature of 120° C. to 350° C. into the drying chamber while spraying the mixture into a drying chamber to heat-treat the mixture. [118] In the spray drying process, the inert gas is a non-reactive gas and may be at least one selected from the group consisting of helium, nitrogen, and argon. [119] In the spray drying process, the temperature of the inert gas may be 150 °C to 350 °C, preferably 180 °C to 250 °C. When heat-treating within the above range, SWCNTs can be sufficiently fixed in the carbon coating layer so that a uniform conductive network can be formed in the cathode, carbonization of the carbon coating layer due to high-temperature heat treatment is prevented, and SWCNTs are more than necessary in the silicon-based core particles It is possible to improve the flexibility and freedom of SWCNTs by preventing excessive adsorption. [120] According to the manufacturing method of the composite negative electrode active material of the present invention, oxygen in the precursor for forming the outer carbon coating layer is reduced by the heat treatment, and the outer carbon coating layer is formed so that the precursor for forming the outer carbon coating layer attaches and fixes a part of the SWCNTs. can Specifically, the outer carbon coating layer may contain oxygen in an amount of 35 wt% to 55 wt%, preferably 40 wt% to 55 wt%. When the oxygen content is in the range, it can be determined that the first SWCNTs of the composite anode active material of the present invention are preferably formed by properly attaching and fixing a part of the SWCNTs in the outer carbon coating layer. [121] [122] [123] In addition, the present invention provides a negative electrode comprising the above-described composite negative electrode active material. [124] Specifically, the negative electrode of the present invention is a negative electrode current collector; and an anode active material layer formed on the anode current collector, wherein the anode active material layer includes an anode material, a binder, and a conductive material, and the anode material includes the composite anode active material described above. [125] The anode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Specifically, the negative electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and an aluminum-cadmium alloy, preferably copper. [126] The negative electrode current collector may typically have a thickness of 3 to 500 μm. [127] The negative electrode current collector may form fine concavities and convexities on the surface to strengthen the bonding strength of the negative electrode active material. For example, the negative electrode current collector may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like. [128] The anode active material layer is formed on the anode current collector. [129] The negative active material layer may include a negative electrode material and a binder, and the negative electrode material includes the above-described composite negative active material. [130] The composite negative active material may be included in the negative electrode to exhibit excellent capacity characteristics, and may contribute to improving the lifespan characteristics of the negative electrode by the conductive network formed by the SWCNT and the cross-linking material included therein. [131] The description of the composite negative active material has been described above. [132] The negative electrode material may further include a carbon-based active material together with the composite negative active material described above, and thus the degree of volume expansion of the entire negative electrode material may be lowered by the carbon-based active material having a low degree of volume expansion according to charging and discharging, and the composite The conductive network due to SWCNTs in the negative active material can surround the carbon-based active material, which is more preferable for improving resistance and efficiency. [133] The carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, acetylene black, Ketjen black, super P, graphene, and fibrous carbon, preferably It may include at least one selected from the group consisting of artificial graphite and natural graphite. [134] The average particle diameter (D 50 ) of the carbon-based active material may be 5 μm to 35 μm, preferably 10 μm to 20 μm, in terms of structural stability during charging and discharging and reducing side reactions with the electrolyte. [135] Specifically, the negative electrode material preferably uses both the composite negative electrode active material and the carbon-based active material in terms of simultaneously improving capacity characteristics and cycle characteristics, and specifically, the negative electrode material includes the composite negative electrode active material and the carbon-based active material 1 :99 to 35:65, preferably in a weight ratio of 5:95 to 30:70, more preferably in a weight ratio of 10:90 to 20:80. When it is in the above range, it is preferable in terms of simultaneous improvement of capacity and cycle characteristics. [136] The anode material may be included in the anode active material layer in an amount of 80 wt% to 99 wt%, preferably 90 wt% to 98.5 wt% in the anode active material layer. [137] The negative active material layer includes a binder. [138] The binder further improves electrode adhesion and in terms of providing sufficient resistance to volume expansion/contraction of the active material, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (acrylonitrile butadiene rubber), acrylic rubber (acrylic rubber), butyl rubber, fluoro rubber, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol (PVA: polyvinyl alcohol), It may include at least one selected from the group consisting of polyacrylic acid (PAA), polyethylene glycol (PEG: polyethylene glycol), polyacrylonitrile (PAN: polyacrylonitrile), and polyacryl amide (PAM: polyacryl amide). . Preferably, the binder has high strength, has excellent resistance to volume expansion/contraction of the silicon-based negative active material, and provides excellent flexibility to the binder to prevent distortion and warpage of the electrode. It is preferable to include [139] The binder may be included in the anode active material layer in an amount of 0.5 wt% to 10 wt%, and when it is in the above range, it is preferable in terms of being able to more effectively control the volume expansion of the active material. [140] If necessary, the negative active material layer may further include a conductive material. The conductive material may be used to improve the conductivity of the negative electrode, and it is preferable to have conductivity without causing a chemical change. Specifically, the conductive material is natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, farness black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, titanic acid It may be at least one selected from the group consisting of potassium, titanium oxide, and polyphenylene derivatives, and may preferably include carbon black in terms of realizing high conductivity. [141] The conductive material may be included in the negative active material layer in an amount of 0.5 wt% to 10 wt%. [142] The anode active material layer may have a thickness of 30 µm to 100 µm, preferably 40 µm to 80 µm, in terms of increasing electrical contact to components of the anode material due to the aforementioned SWCNT. [143] [144] The negative electrode is prepared by dispersing a negative electrode material, a binder and a conductive material on the negative electrode current collector in a solvent for forming a negative electrode slurry to prepare a negative electrode slurry, coating the negative electrode slurry on the negative electrode current collector, drying and rolling can be [145] The solvent for forming the negative electrode slurry may include at least one selected from the group consisting of distilled water, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in terms of facilitating dispersion of the components. [146] [147] [148] The present invention provides a secondary battery including the above-described negative electrode, specifically, a lithium secondary battery. [149] Specifically, the secondary battery according to the present invention includes the above-described negative electrode; an anode opposite the cathode; a separator interposed between the negative electrode and the positive electrode; and electrolytes. [150] The positive electrode is a positive electrode current collector; It may include a positive electrode active material layer formed on the positive electrode current collector. [151] The positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Specifically, the negative electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and an aluminum-cadmium alloy, preferably aluminum. [152] The positive electrode current collector may typically have a thickness of 3 to 500 μm. [153] The positive electrode current collector may form fine concavities and convexities on the surface to strengthen the bonding force of the negative electrode active material. For example, the negative electrode current collector may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like. [154] The positive active material layer may include a positive active material. [155] The positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, a lithium transition metal composite oxide containing lithium and at least one transition metal consisting of nickel, cobalt, manganese and aluminum; Preferably, it may include a lithium transition metal composite oxide containing a transition metal containing nickel, cobalt and manganese and lithium. [156] More specifically, as the lithium transition metal composite oxide, lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4 , etc.), lithium-cobalt-based oxide (eg, LiCoO 2 , etc.), lithium-nickel Oxide-based oxides (eg, LiNiO 2 , etc.), lithium-nickel-manganese oxides (eg, LiNi 1-Y Mn Y O 2 (here, 0 [241] As an anode material, a mixture of the composite anode active material prepared in Example 1 and natural graphite (average particle diameter (D 50 ): 15 μm) as a carbon-based active material in a weight ratio of 15:85 was used. [242] A negative electrode slurry was prepared by mixing the negative electrode material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose as a thickener in a weight ratio of 98:1:1, and adding this to distilled water as a solvent for forming the negative electrode slurry. [243] As a negative electrode collector, the negative electrode slurry was coated on one side of a copper current collector (thickness: 15 μm) at a loading amount of (3mAh/cm 2 ), rolled, and dried in a vacuum oven at 130° C. for 10 hours. to form a negative active material layer (thickness: 42 μm), which was used as the negative electrode according to Example 1 (thickness of the negative electrode: 57 μm, area 1.4875 cm 2 , circular). [244] [245] In addition, a negative electrode of Comparative Example 4 was prepared in the same manner as in Example 1, except that the negative active material of Comparative Example 4 was used instead of the composite negative active material of Example 1. [246] [247] [248] The cathodes of Example 1 and Comparative Example 4 prepared above were observed by SEM using a scanning electron microscope (manufacturer: JEOL). [249] The SEM photograph of the negative electrode of Example 1 is shown in FIG. 2 , and the SEM photograph of the negative electrode of Comparative Example 4 is shown in FIG. 3 . [250] [251] 2 and 3 , in the composite negative active material of Example 1, a portion of the body is in contact with the outer carbon coating layer, and the remaining part of the body not in contact with the outer carbon coating layer is spaced apart from the outer carbon coating layer and protrudes 1 SWCNT is formed, and it can be seen that the crosslinking material crosslinks the first SWCNT and the second SWCNT with each other to form a conductive structure. However, in the negative active material of Comparative Example 1, SWCNTs are entirely attached to the outer carbon coating layer surface, and it is confirmed that carbon black exists independently, so it can be confirmed that the conductive structure and cross-linking structure for the purpose of the present invention are not formed. have. [252] [253] Experimental Example 2: Lifespan characteristic evaluation [254] [255] As an anode material, a mixture of the composite anode active material prepared in Example 1 and natural graphite (average particle diameter (D 50 ): 15 μm) as a carbon-based active material in a weight ratio of 15:85 was used. [256] A negative electrode slurry was prepared by mixing the negative electrode material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose as a thickener in a weight ratio of 98:1:1, and adding this to distilled water as a solvent for forming the negative electrode slurry. [257] As a negative electrode collector, the negative electrode slurry was coated on one side of a copper current collector (thickness: 15 μm) at a loading amount of (3mAh/cm 2 ), rolled, and dried in a vacuum oven at 130° C. for 10 hours. to form a negative active material layer (thickness: 42 μm), which was used as the negative electrode according to Example 1 (thickness of the negative electrode: 57 μm, area 1.4875 cm 2 , circular). [258] [259] In addition, in the same manner as in Example 1, Examples 2 to 7 and Comparative Examples 1 to except that the composite negative active materials of Examples 2 to 7 and Comparative Examples 1 to 4 were used instead of the composite negative active material of Example 1, respectively. The negative electrode of 4 was prepared. [260] [261] [262] A lithium metal thin film having an area of ​​1.7671 cm 2 and having a circular shape was used as the positive electrode. [263] A coin-type half-cell secondary battery was manufactured by interposing a separator of porous polyethylene between the negative electrode and the positive electrode of Examples 1 to 7 and Comparative Examples 1 to 4 prepared above, and injecting an electrolyte. [264] As the electrolyte, in a solution of ethylmethyl carbonate (EMC) and ethylene carbonate (EC) in a volume ratio of 7:3, 0.5 wt% of vinylene carbonate (VC) was dissolved, and LiPF 6 was dissolved at a concentration of 1M. was used. [265] [266] [267] For the secondary batteries prepared in Examples 1 to 7 and Comparative Examples 1 to 4, cycle capacity retention rates were evaluated using an electrochemical charger/discharger. [268] The cycle capacity retention rate was 0.1C in the 1st and 2nd cycles, and charging and discharging at 0.5C from the 3rd cycle (Charging conditions: CC/CV, 5mV/0.005C cut-off, discharge conditions: CC, 1.5V cut off) [269] The capacity retention rate was calculated as follows. [270] Capacity retention rate (%) = {(discharge capacity in Nth cycle)/(discharge capacity in 1st cycle)} × 100 [271] (in Equation 2, N is an integer greater than or equal to 1) [272] The 50th cycle capacity retention rate (%) is shown in Table 1 below. [273] [274] [Table 1] [275] [276] Referring to Table 1, it can be seen that the negative electrode and the secondary battery using the composite negative active material of Examples 1 to 7 improved the cycle capacity retention rate to an excellent level compared to Comparative Examples 1 to 4. [277] [278] [Explanation of code] [279] 10: composite anode active material [280] 100: silicon-based core particles [281] 200: outer carbon coating layer [282] 300: first single-walled carbon nanotube [283] 400: conductive structure [284] 450: second single-walled carbon nanotube [285] 500: crosslinking material [286] 600: inner carbon coating layer Claims [Claim 1] silicon-based core particles; an outer carbon coating layer positioned on the silicon-based core particle; a first single-walled carbon nanotube in contact with the outer carbon coating layer and protruding from the outer carbon coating layer; a conductive structure spaced apart from the outer carbon coating layer and including a second single-walled carbon nanotube; and a crosslinking material bonded to at least one of the first single-walled carbon nanotube and the second single-walled carbon nanotube, wherein at least one of the second single-walled carbon nanotubes is the first single-walled carbon nanotube A composite negative electrode active material crosslinked by the tube and the crosslinking material to connect the conductive structure and the first single-walled carbon nanotube to each other. [Claim 2] The method according to claim 1, wherein the silicon-based core particle is a composite negative electrode active material comprising a compound represented by the following Chemical Formula 1: [Formula 1] M x SiO y In Chemical Formula 1, M is selected from the group consisting of Li, Mg, and Al It is at least 1 type, 0≤x≤0.4, and 0≤y<2. [Claim 3] The composite anode active material of claim 1 , further comprising an internal carbon coating layer formed between the silicon-based core particle and the outer carbon coating layer. [Claim 4] The composite anode active material of claim 1, wherein the sum of the weights of the first single-walled carbon nanotube and the second single-walled carbon nanotube is 0.04 wt% to 0.7 wt% based on the composite anode active material. [Claim 5] The composite anode active material of claim 1, wherein the crosslinking material is at least one selected from the group consisting of carbon black, natural graphite, and artificial graphite. [Claim 6] The composite anode active material of claim 1, wherein the crosslinking material is included in an amount of 0.6 wt% to 5 wt% in the composite anode active material. [Claim 7] The composite anode active material of claim 1 , wherein the cross-linking material has a spherical shape. [Claim 8] The composite anode active material of claim 1, wherein the crosslinked material has an average particle diameter (D 50 ) of 0.01 μm to 3 μm. [Claim 9] The composite negative active material of claim 1 , wherein a ratio of the sum of the weights of the first single-walled carbon nanotube and the second single-walled carbon nanotube to the weight of the cross-linking material is 1:99 to 40:60. [Claim 10] mixing silicon-based core particles, a precursor for forming an outer carbon coating layer, two or more single-walled carbon nanotubes, and a crosslinking material; and heat-treating the mixture. [Claim 11] The method of claim 10 , wherein the heat treatment is performed by a spray drying process. [Claim 12] The method according to claim 10, wherein the precursor for forming the outer carbon coating layer is from the group consisting of carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, methyl hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, methyl ethyl hydroxyethyl cellulose and cellulose gum. A method of manufacturing at least one selected composite anode active material. [Claim 13] The method according to claim 10, further comprising the step of forming an internal carbon coating layer on the silicon-based core particles before the mixing step, wherein the step of forming the internal carbon coating layer is at least one selected from the group consisting of methane, ethane and acetylene A method of manufacturing a composite anode active material performed by chemical vapor deposition (CVD) using a hydrocarbon gas of [Claim 14] negative electrode current collector; and an anode active material layer formed on the anode current collector, wherein the anode active material layer includes an anode material including the composite anode active material according to claim 1, a binder, and a conductive material. [Claim 15] The negative electrode of claim 14 , wherein the negative electrode material further includes a carbon-based active material, and the negative electrode material includes the composite negative active material and the carbon-based active material in a weight ratio of 1:99 to 35:65.