This application claims priority based on Korean Patent Application No. 10-2019-0007121 filed on January 18, 2019. The present invention relates to an anode active material for a lithium secondary battery and a lithium secondary battery including the same. [2] background [3] Carbon-based materials obtained by sintering graphite or organic materials as anode materials for nonaqueous electrolyte batteries have excellent charge/discharge efficiency and excellent cycle life, and thus have been widely put to practical use. However, as portable electronic communication devices and power tools are increasingly miniaturized, lightweight, and high-performance, and the demand for high capacity for practical use of electric vehicles increases, anode material to replace carbon-based materials with low battery capacity due to structural characteristics There has been a need for [4] Recently, despite the various problems of metal cathodes, research on metals such as Si and Sn has been actively conducted. In particular, silicon-based anodes are being studied most actively because the theoretical capacity of silicon is 4,200 mAh/g, which is more than 10 times higher than the theoretical capacity of carbon-based anodes of 370 mAh/g. [5] Since silicon as an anode material expands by more than 300% in volume due to reaction with lithium during charging and contracts during discharging, such rapid expansion and contraction causes cracks in the anode material particles and the electrode falls off. In the end, there is a fatal problem that the cycle life is rapidly reduced. [6] The silicon oxide anode proposed to improve this problem has a smaller capacity than silicon, but is very superior to the capacity of a carbon-based anode, and has a low volume expansion rate compared to metals, so it is in the spotlight as a material with excellent cycle life characteristics. When such silicon oxide is applied as a negative electrode material for a secondary battery, the capacity is only half the capacity of the silicon negative electrode material, but is about 5 times greater than the capacity of the carbon-based negative electrode material. However, when silicon oxide is applied as a negative electrode material for a secondary battery, there is a problem in that the volume change during charging and discharging is still large compared to a carbon-based negative electrode material. [7] In addition, when silicon oxide is applied as a negative electrode material of a secondary battery, lithium and silicon oxide react during initial charging to generate lithium silicide and lithium oxide (lithium oxide and lithium silicate), of which lithium oxide is used for subsequent electrochemical Since it does not participate in the reaction, a part of lithium transferred to the negative electrode during initial charging causes an irreversible reaction that does not return to the positive electrode during discharge, resulting in a problem of depleting lithium. [8] In addition, in the case of silicon oxide, such an irreversible capacity is large compared to other silicon-based anodes, so the initial efficiency (ICE, the ratio of the initial charge capacity to the discharge capacity) is very low at 70 to 75%. Such low initial efficiency requires an excessive capacity of the positive electrode in configuring the secondary battery, thereby offsetting the capacity per unit mass of the negative electrode. [9] In order to solve this problem, a magnesium-doped silicon-silicon oxide composite has been prepared in the art, but there is still a need for improvement in terms of cycle characteristics. [10] DETAILED DESCRIPTION OF THE INVENTION technical challenge [11] In one aspect, the present invention is to solve the above problems, and provides a silicon-silicon oxide-magnesium silicate (Si-SiOx-Mg silicate) composite for use as an anode active material for a lithium secondary battery, wherein the composite includes The present invention is to provide an anode active material for a lithium secondary battery that improves the initial efficiency, capacity, and cycle of a lithium secondary battery by including two kinds of magnesium-silicate in a predetermined composition and amount. [12] In another aspect, the present invention is an invention for providing a method of manufacturing the negative active material for a lithium secondary battery. [13] means of solving the problem [14] According to a first aspect of the present invention, a silicon oxide (SiO x , 0 [84] Silicon powder and silicon dioxide powder (SiO 2 and a molar ratio of 1, the silicon powder and the Mg powder 1:: a) first silicon powder, silicon dioxide powder (SiO such that the mole ratio of 0.5 2, a mixture of a) and Mg powder was injected into the reactor. The silicon powder, silicon dioxide powder (SiO 2 ), and a mixture of Mg powder is heated to 1,500 ° C in a reduced pressure atmosphere of -100 torr under vacuum, and the silicon powder, silicon dioxide powder (SiO 2 ) By the mixed powder After gas phase reaction by generating silicon oxide vapor and magnesium vapor simultaneously, it was cooled and a silicon-silicon oxide-magnesium silicate composite was precipitated at 800°C. Then, the silicon-silicon oxide-magnesium silicate composite was pulverized to an average particle diameter (D50) of 5 μm using a jet mill, and then powder of the silicon-silicon oxide-magnesium silicate composite was recovered. At this time, the Mg content was 10.2% based on the weight of the silicon-silicon oxide-magnesium silicate composite particles. [85] The recovered silicon-silicon oxide-magnesium silicate composite particle powder was subjected to CVD treatment under a mixed gas of argon (Ar) and methane (CH 4 ) at 1,000° C. for 2 hours using a tube-type electric furnace to have a carbon content of 5 wt. % carbon coating layer was formed, silicon-silicon oxide-magnesium silicate composite particles were prepared. Additional heat treatment was not performed on the prepared silicon-silicon oxide-magnesium silicate composite particles having a carbon coating layer formed thereon. [86] As a result of ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) analysis of the silicon-silicon oxide-magnesium silicate composite particle powder (Sample 1), it was confirmed that the magnesium concentration was 10.2 wt%, and as a result of X-ray diffraction analysis (CuKα), Si It was confirmed that the grain size was 10.8 nm. [87] The obtained silicon-silicon oxide-magnesium silicate composite includes a silicon oxide (SiO x , 0 [90] A silicon-silicon oxide-magnesium silicate composite particle powder was prepared in the same manner as in Example 1, except that the heat treatment temperature of the mixed powder was 1400 °C. [91] [92] [93] Silicon-silicon oxide-magnesium silicate composite particles were prepared in the same manner as in Example 1, except that the cooling temperature after gas phase reaction was 600° C. by generating silicon oxide vapor and magnesium vapor simultaneously. [94] [95] [96] Silicon powder and silicon dioxide powder (SiO 2 and a molar ratio of 1, the silicon powder and the Mg powder 1:: a) first silicon powder, silicon dioxide powder (SiO such that the mole ratio of 0.5 2, a mixture of a) and Mg powder was injected into the reactor. The silicon powder, silicon dioxide powder (SiO 2 ), and a mixture of Mg powder is heated to 1,500 ° C in a reduced pressure atmosphere of -100 torr under vacuum, and the silicon powder, silicon dioxide powder (SiO 2 ) By the mixed powder After gas phase reaction was carried out by generating silicon oxide vapor and magnesium vapor simultaneously, it was cooled at 400° C. to precipitate a silicon-silicon oxide-magnesium silicate composite. [97] The recovered silicon-silicon oxide-magnesium silicate composite particles were subjected to CVD treatment under a mixed gas of argon (Ar) and methane (CH 4 ) at 1,000° C. for 2 hours using a tube-type electric furnace, so that the carbon content was 5 wt% A silicon-silicon oxide-magnesium silicate composite particle powder having a phosphorus carbon coating layer was prepared. [98] Subsequently, the silicon-silicon oxide-magnesium silicate composite particle powder having the carbon coating layer was further heat treated at 1000° C. for 5 hours under an argon (Ar) atmosphere to prepare a final product, a silicon-silicon oxide-magnesium silicate composite particle powder. . [99] [100] [101] In the final step, a silicon-silicon oxide-magnesium silicate composite particle powder was prepared in the same manner as in Comparative Example 1, except that additional heat treatment was further performed at 1200° C. for 5 hours in an argon (Ar) atmosphere. [102] [103] [104] Each of the samples prepared in Examples 1 to 2 and Comparative Examples 1 to 4 was used as an anode active material, and Super-P black as a conductive material and poly acrylic acid (PAA) as a binder were used in a weight-based 80:10:10 ratio. It was mixed with N-methylpyrrolidone as much as possible to prepare a slurry composition. [105] By applying the composition to one side of a copper foil having a thickness of 18 μm and drying it, an active material layer having a thickness of 30 μm was formed on one side of the copper foil, and a test electrode was prepared by punching a circle with a diameter of 14 Φ, and the thickness as the opposite electrode A 0.3 mm metallic lithium foil was used. [106] A porous polyethylene sheet having a thickness of 0.1 mm was used as the separator, and LiPF 6 as a lithium salt was added to a mixed solvent of ethylene carbonate (EC) and diethylene carbonate (DEC) in a volume ratio of 1:1 as an electrolyte solution at a concentration of about 1 mol/L was used after dissolving it. These components were incorporated in a stainless steel container, and a coin cell for evaluation of a general shape having a thickness of 2 mm and a diameter of 32 mm (so-called type 2032) was manufactured. [107] [108] Evaluation Example 1: Analysis of Diffraction Peak Intensity Ratio by X-ray Diffraction Analysis [109] The results of X-ray diffraction analysis for the samples prepared in Examples 1 to 2 and Comparative Examples 1 to 3, respectively, are shown in Table 1 below. [110] Based on the full width at half maximum (FWHM) of the diffraction peak of MgSiO 3 (310) in X-ray diffraction analysis , it may be determined by the sherrer equation (see Equation 1 below), and the precipitation temperature during the manufacturing process was taken as a reference for the silicon-silicon oxide-magnesium silicate composite obtained at 25 °C. [111] Equation 1: CS[nm] = K λ/ B cosθ [112] In the above, K = 0.9, λ = 0.154 nm, B = full width at half maximum (FWHM, rad), and θ = peak position (angle). [113] [114] In X-ray diffraction analysis, it can be determined by the Sira method (see Equation 1 below) based on the full width at half maximum (FWHM) of the diffraction peak of Mg 2 SiO 4 (130), and obtained by setting the precipitation temperature to 25 ° C during the manufacturing process. A silicon-silicon oxide-magnesium silicate composite was referenced. [115] Equation 1: CS[nm] = K λ/ B cosθ [116] In the above, K = 0.9, λ = 0.154 nm, B = full width at half maximum (FWHM, rad), and θ = peak position (angle). [117] [118] The size of the Si grains can be determined by the Sherrer equation (refer to Equation 1 below) based on the full width at half maximum (FWHM) of the diffraction peak of Si(111) in X-ray diffraction analysis, and the precipitation temperature during the manufacturing process is 25 The obtained silicon-silicon oxide-magnesium silicate composite was taken as a reference. [119] Equation 1: CS[nm] = K λ/ B cosθ [120] In the above, K = 0.9, λ = 0.154 nm, B = full width at half maximum (FWHM, rad), and θ = peak position (angle). [121] Mg, MgSiO 3 and Mg 2 SiO 4 Each content was measured through ICP (inductively coupled plasma). [122] [Table 1] Mg content (wt%) Si grain size Crystalline size of MgSiO 3 grains (nm) Crystalline size of Mg 2 SiO 4 grains (nm) Ratio of the crystal size of Mg 2 SiO 4 grains / the crystal size of MgSiO 3 grains Content of MgSiO 3 grains (wt%) Content of Mg 2 SiO 4 grains (wt%) Content ratio of MgSiO 3 grains/Mg 2 SiO 4 grains (based on weight) Example 1 10.2 10.8 16.2 32.4 2 24.7 17.3 1.4 Example 2 10.6 11.2 11.2 22.4 2 24.3 17.5 1.4 Comparative Example 1 10.5 10.7 No MgSiO 3 grains 32.1 Not applicable Not applicable 18.0 Not applicable Comparative Example 2 10.1 10.3 5.4 10.9 2 14.8 24.3 0.6 Comparative Example 3 10.4 10.1 21.1 23.4 1.1 17.8 22.2 0.8 [123] Evaluation Example 2: Battery Characteristics Evaluation [124] The coin cells prepared using the silicon-silicon oxide-magnesium silicate composite particle powders of Examples 1 to 2 and Comparative Examples 1 to 3 were charged at a constant current of 0.05 C until the voltage became 0.01 V, and Discharge capacity and initial efficiency were obtained by discharging with a constant current until the voltage reached 1.5V. [125] In addition, the coin cell manufactured for each sample in the above preparation example is charged with a constant current of 0.2C until the voltage becomes 0.01V, and discharged with a constant current of 0.2C until the voltage becomes 1.5V, so that after one charge/discharge 50 cycle characteristics were obtained. [126] The discharge capacity, initial efficiency, and cycle characteristics were calculated as follows, and the results are shown in Table 2 below. [127] Initial discharge capacity: Discharge capacity in 1th cycle [128] Initial efficiency: 100 x (discharge capacity in 1th cycle) / (charge capacity in 1th cycle) [129] [Table 2] Initial Efficiency (%) Capacity mAh/g Life characteristics (%, 50 cycles) Example 1 90.8 405.2 82 Example 2 90.6 404.8 80 Comparative Example 1 88.1 401.9 77 Comparative Example 2 85.1 392.7 62 Comparative Example 3 87.2 398.4 70 [130] As shown in [Table 2], in the case of the coin cell battery using the silicon-silicon oxide-magnesium silicate composite particles of Examples 1 and 2 of the present invention as an anode active material, the silicon-silicon oxide-magnesium of Comparative Examples 1 to 3 Compared to a coin cell battery using silicate composite particles as an anode active material, the initial charge/discharge efficiency was improved, and the capacity and lifespan characteristics were also excellent. [131] The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may also be implemented in a combined form. [132] The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. WE CLAIM [Claim 1]A negative active material for a lithium secondary battery, comprising: a silicon oxide (SiO x , 0