KR20230155637A - Surface carbon-coated silicon oxide-based anode active material and its manufacturing method - Google Patents

Abstract

The present invention relates to a silicon oxide-based negative electrode active material with surface carbon coating and a method of manufacturing the same. According to an embodiment of the present invention, a carbon coating precursor satisfying the following conditions (1) to (4) obtained by heat treating petroleum residue distillate under an inert atmosphere is made of particles containing SiOx (0<x≤2). Depositing an amorphous carbon coating layer on the surface; and carbonizing the deposited amorphous carbon coating layer, wherein the content of each hydrocarbon compound under the following conditions (1) to (4) is determined by analyzing the ¹ H-NMR spectrum of the carbon coating precursor, with a detection peak of 2.0 ppm. A method for producing a silicon oxide-based negative active material can be provided, which is derived as a percentage of each peak area in the detection peak range of the following conditions (1) to (4) compared to the total peak area below 9.0 ppm.
(1) The content of monocyclic aromatic hydrocarbon compounds detected at a detection peak of 6.0 ppm or more and less than 7.2 ppm is 30% or less.
(2) The content of dicyclic aromatic hydrocarbon compounds detected at a detection peak of 7.2 ppm or more and less than 7.8 ppm is 10 to 45%.
(3) The content of tricyclic aromatic hydrocarbon compounds detected at a detection peak of 7.8 ppm or more and less than 9.0 ppm is 3 to 20%.
(4) The content of aliphatic hydrocarbon compounds detected at a detection peak of 2.0 ppm or more but less than 6.0 ppm is 30 to 60%.

Description

Surface carbon-coated silicon oxide-based anode active material and method of manufacturing the same {SURFACE CARBON-COATED SILICON OXIDE-BASED ANODE ACTIVE MATERIAL AND ITS MANUFACTURING METHOD}

The present invention relates to a silicon oxide-based negative electrode active material with surface carbon coating and a method of manufacturing the same.

In order to solve environmental problems such as air pollution and greenhouse effect around the world, much effort is being made to develop eco-friendly and sustainable energy sources and efficient energy storage systems. Lithium secondary batteries are attracting attention as an eco-friendly energy storage device to solve environmental problems. Lithium secondary batteries (LIBs) have advantages such as high energy density/operating voltage, fast output characteristics, and excellent lifespan.

However, large-scale energy storage devices required for electric vehicles, etc. require electrode materials with improved energy density than existing graphite-based anode materials (theoretical capacity ~372 mAh/g). As an alternative to graphite-based anode materials, silicon-based anode materials (theoretical capacity 4200 mAh/g) are being studied as anode materials that can store high capacity energy per unit weight and unit volume. However, silicon anode materials have the problem of high manufacturing costs incurred in manufacturing silicon powder, which is a raw material, and when silicon-based anode materials are applied to batteries, battery capacity retention decreases sharply due to the high volume expansion rate of silicon. there is a problem.

In order to improve the problems occurring in these silicon-based anode materials, research on silicon nanoparticles, porous silicon, etc. is underway. Recently, silicon oxide (SiOx, 0<x≤2) has been widely studied as a substitute for silicon. However, silicon oxide still has the problem of high volume expansion rate (160%) and low electrical conductivity during charging and discharging, which reduces the cycle stability of lithium secondary batteries.

To solve this problem, SiOx and carbon are combined to suppress volume expansion through carbon coating using carbon precursors such as graphite-like block Graphite-Like Blocky SiOx@C, Microspheres SiOx@C, and composite nanorods and coal/petroleum-based pitch. Research is underway to improve capacity maintenance.

Meanwhile, more than 1 million tons of petroleum residues are produced annually in Korea. Much research is being conducted using petroleum residue components that have different thermal and structural properties and to confirm the possibility of eco-friendly upcycling. Petroleum residue components or components derived from them are low-cost raw materials, and if used as a carbon coating material for silicon oxide-based anode active materials, it is expected that the recyclability of resources can be further expanded.

Korean Patent Publication No. 10-1345708 (Publication date: December 27, 2013)

In order to solve the above-mentioned problems, the present invention seeks to provide a silicon oxide-based negative electrode active material with surface carbon coating that has superior capacity compared to conventional negative electrode materials and improved cycle stability, and a method for manufacturing the same.

The present invention seeks to provide a silicon oxide-based negative electrode active material coated with surface carbon using refined petroleum residue and a method for manufacturing the same.

As a means to achieve the above-mentioned object, according to one embodiment of the present invention, SiOx (0 Depositing an amorphous carbon coating layer on the surface of particles containing <x≤2); and carbonizing the deposited amorphous carbon coating layer, wherein the content of each hydrocarbon compound under the following conditions (1) to (4) is determined by analyzing the ¹ H-NMR spectrum of the carbon coating precursor, with a detection peak of 2.0 ppm. A method for producing a silicon oxide-based negative active material can be provided, which is derived as a percentage of each peak area in the detection peak range of the following conditions (1) to (4) compared to the total peak area below 9.0 ppm.

(1) The content of monocyclic aromatic hydrocarbon compounds detected at a detection peak of 6.0 ppm or more and less than 7.2 ppm is 30% or less;

(2) The content of dicyclic aromatic hydrocarbon compounds detected at a detection peak of 7.2 ppm or more and less than 7.8 ppm is 10 to 45%;

(3) The content of tricyclic aromatic hydrocarbon compounds detected at a detection peak of 7.8 ppm or more and less than 9.0 ppm is 3 to 20%;

(4) The content of aliphatic hydrocarbon compounds detected at a detection peak of 2.0 ppm or more and less than 6.0 ppm is 30 to 60%;

In addition, according to one embodiment of the present invention, the temperature range for heat treating the refined petroleum residue may be 100 to 400 ° C.

In addition, according to one embodiment of the present invention, it may include heating at a temperature increase rate of 3 to 7 ° C./min from room temperature to a temperature of 100 to 400 ° C., which is the temperature range for heat treatment of the petroleum residue distillate.

In addition, according to one embodiment of the present invention, the sum of the contents of the dicyclic aromatic hydrocarbon compound detected under condition (2) and the tricyclic aromatic hydrocarbon compound detected under condition (3) may be 20% or more.

Additionally, according to one embodiment of the present invention, the deposition step may include deposition using physical vapor deposition (PVD).

In addition, according to one embodiment of the present invention, the carbonization step includes heating the amorphous carbon coating layer at a temperature increase rate of 8 to 12 °C/min to 800 to 1200 °C and then heat treating for more than 30 minutes. can do.

Additionally, according to one embodiment of the present invention, the refined petroleum residue may be a product obtained by pitch reforming petroleum residue.

In addition, as another means to achieve the object of the present invention, according to an embodiment of the present invention, a silicon oxide-based negative electrode active material manufactured according to the above-described manufacturing method can be provided.

In addition, as another means to achieve the object of the present invention, according to one embodiment of the present invention, silicon oxide comprising particles containing SiOx (0<x≤2) and an amorphous carbon coating layer provided on the surface of the particles For cathode active materials, in Raman spectrum analysis using a laser with a wavelength of 514 nm, I _D is the maximum peak intensity that appears from 1300 cm ^-1 to 1400 cm ^-1 , and I _G appears from 1550 cm ^-1 to 1650 cm ^-1 When referring to the maximum peak intensity, a silicon oxide-based negative electrode active material can be provided, characterized in that the peak intensity ratio I _D /I _G value is 0.9 to 1.05.

In addition, the silicon oxide-based anode active material according to an embodiment of the present invention is at% when analyzed by surface XPS elements using an Al-Kα May contain unavoidable impurities.

In addition, as a result of surface XPS C _1s detailed peak analysis of the silicon oxide-based negative electrode active material according to an embodiment of the present invention using an Al-Kα ) may be satisfied.

C(1): C=C bond area ratio 70 to 85%;

C(2): C-C bond area ratio 5 to 25%;

C(3): C-O bond area ratio exceeding 0% and 5% or less;

C(4): O-C=O bond area ratio exceeding 0% and less than or equal to 5%;

Additionally, according to one embodiment of the present invention, the thickness of the amorphous carbon coating layer may be 10 to 30 nm.

Additionally, according to one embodiment of the present invention, the average particle diameter of the particles containing SiOx (0<x≤2) may be 1 to 10 ㎛.

In addition, as another means for achieving the object of the present invention, according to an embodiment of the present invention, a negative electrode containing the above-described negative electrode active material can be provided.

In addition, as another means for achieving the object of the present invention, according to an embodiment of the present invention, a battery including the above-described negative electrode can be provided.

According to an embodiment of the present invention, a silicon oxide-based negative electrode active material coated with surface carbon is formed by forming an amorphous carbon coating layer on the surface of a silicon oxide-based negative electrode active material using a physical vapor deposition (PVD) method of petroleum residue distillate, and a surface carbon-coated silicon oxide-based negative electrode active material. Manufacturing methods can be provided.

According to one embodiment of the present invention, it is possible to provide a silicon-based oxide-based negative electrode active material with surface carbon coating that can upcycle refined petroleum residue, which is a low-cost raw material, and a method for manufacturing the same, which is excellent in economic efficiency and eco-friendliness.

The surface carbon-coated silicon-based oxide-based negative electrode active material according to an embodiment of the present invention has excellent capacity and excellent cycle stability.

Figures 1a to 1d are diagrams showing the results of ¹ H-NMR spectrum analysis for 200, 250, and 300 fraction oil.
Figure 2 is a diagram showing the results of FT-IR analysis for 200, 250, and 300 fraction oil.
Figures 3a and 3b are diagrams showing the results of surface XPS analysis using an Al-Kα
Figures 3c to 3e are diagrams showing the results of analyzing the _detailed surface
Figures 4a to 4c are diagrams showing the results of Raman spectrum analysis of carbon-coated silicon oxide-based anode active materials (SiOx@C 200, 250, and 300), respectively.
Figures 4d to 4f are diagrams showing TEM analysis results of carbon-coated silicon oxide-based negative electrode active materials (SiOx@C 200, 250, and 300), respectively.
Figures 4g to 4i show the EDS analysis results of carbon-coated silicon oxide-based negative electrode active material (SiOx@C 200, 250, and 300), respectively.
Figure 5a is a graph evaluating the rate characteristics of carbon-uncoated silicon oxide-based negative electrode active material (SiOx) and carbon-coated silicon oxide-based negative electrode active material (SiOx@C 200, 250, 300) manufactured as half cells.
Figure 5b is a graph evaluating the cycle stability of carbon-uncoated silicon oxide-based negative electrode active material (SiOx) and carbon-coated silicon oxide-based negative electrode active material (SiOx@C 200, 250, 300) manufactured as half cells.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily implement it. However, the present invention may be implemented in various different forms and is not limited to the implementation examples described herein. Additionally, it is not intended to limit the scope of protection limited by the scope of the patent claims.

In addition, if there is no other definition in the technical and scientific terms used in the description of the present invention, they have the meaning commonly understood by those skilled in the art in the technical field to which this invention pertains, and in the following description, the present invention Descriptions of known functions and configurations that may unnecessarily obscure the point are omitted.

Unless there is a special definition for the present invention, the fact that a part "includes" a certain component does not mean that other components are excluded, but that it may further include other components, unless specifically stated to the contrary. Additionally, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly dictates otherwise.

The present inventors found that when an amorphous carbon layer is formed on the surface of a silicon oxide-based anode material using pitch or polymer oxide, which are carbon precursors, the formed amorphous carbon layer acts as a buffer on the surface of the silicon oxide-based anode material and suppresses volume expansion. paid attention to.

Carbon precursors include coal-based pitch, petroleum-based pitch, sucrose, PVC, and PVA. Among them, pyrolzed fuel oil (PFO), a mixture of polycyclic aromatic hydrocarbons (PAH), is known to be a suitable raw material for high-value carbon materials because it contains fewer impurities such as sulfur than coal-based pitch. Additionally, the mixtures constituting the pyrolysis residual oil are individually separated depending on the heat treatment temperature. The separated components undergo polymerization and/or condensation reactions individually or between each component to form compounds of various structures. As a result, when the pyrolysis residual oil is heat treated, it can exhibit various physicochemical properties.

The present inventors paid attention to the characteristics of the pyrolysis residual oil distillate. The present inventors attempted to develop a surface carbon-coated silicon oxide-based anode active material in which an amorphous carbon coating layer was formed on the surface of particles containing SiOx (0<x≤2) by heating pyrolysis residual oil distillate under specific conditions. We sought to develop a silicon oxide-based anode active material with superior capacity and improved cycle stability compared to existing graphite anode materials.

Hereinafter, each configuration of the present invention will be described in more detail. However, this is only illustrative and the present invention is not limited to the specific embodiments described as examples.

According to an embodiment of the present invention, a carbon coating precursor satisfying the following conditions (1) to (4) obtained by heat treating petroleum residue distillate under an inert atmosphere is made of particles containing SiOx (0<x≤2). Depositing an amorphous carbon coating layer on the surface; and carbonizing the deposited amorphous carbon coating layer, wherein the content of each hydrocarbon compound under the following conditions (1) to (4) is determined by analyzing the ¹ H-NMR spectrum of the carbon coating precursor, with a detection peak of 2.0 ppm. A method for producing a silicon oxide-based negative active material can be provided, which is derived as a percentage of each peak area in the detection peak range of the following conditions (1) to (4) compared to the total peak area below 9.0 ppm.

(1) The content of monocyclic aromatic hydrocarbon compounds detected at a detection peak of 6.0 ppm or more and less than 7.2 ppm is 30% or less;

(2) The content of dicyclic aromatic hydrocarbon compounds detected at a detection peak of 7.2 ppm or more and less than 7.8 ppm is 10 to 45%;

(3) The content of tricyclic aromatic hydrocarbon compounds detected at a detection peak of 7.8 ppm or more and less than 9.0 ppm is 3 to 20%;

(4) The content of aliphatic hydrocarbon compounds detected at a detection peak of 2.0 ppm or more and less than 6.0 ppm is 30 to 60%;

According to one embodiment of the present invention, the refined petroleum residue may be a product obtained by pitch reforming petroleum residue, but is not particularly limited.

The carbon coating precursor that satisfies the above conditions (1) to (4) has a high content of aromatic hydrocarbon compounds, especially high content of di- and tri-ring aromatic hydrocarbon compounds, so when the surface of the silicon oxide-based negative electrode active material is coated with an amorphous carbon coating layer, It is possible to provide an amorphous carbon coating layer with a fine structure and thickness that can secure excellent capacity characteristics and cycle stability.

According to a preferred embodiment from the above viewpoint, the content of monocyclic aromatic hydrocarbon compounds detected under condition (1) may be 30% or less, or 25% or less, or 20% or less, or 10% or less, or 5% or less.

According to a preferred embodiment from the above viewpoint, the content of the bicyclic aromatic hydrocarbon compound detected under condition (2) may be 10 to 45%, or 15 to 45%, or 20 to 45%.

According to a preferred embodiment from the above viewpoint, the content of the tricyclic aromatic hydrocarbon compound detected under condition (3) may be 3 to 20%, or 5 to 20%.

According to a preferred embodiment from the above viewpoint, the content of aliphatic hydrocarbon compounds detected under condition (4) may be 30 to 60%, or 30 to 55%, or 35 to 60%, or 35 to 55%.

According to a preferred embodiment from the above viewpoint, the sum of the contents of the dicyclic aromatic hydrocarbon compound detected in condition (2) and the tricyclic aromatic hydrocarbon compound detected in condition (3) is 20% or more, or 25% or more, Or it may be 30% or more, or 35% or more.

According to one embodiment of the present invention, the temperature range for heat treating the refined petroleum residue may be 100 to 400 ° C. If the heat treatment temperature is too low, the aliphatic hydrocarbon compound content is high and the aromatic hydrocarbon compound content is low, so there is a risk that an amorphous carbon coating layer with the desired microstructure and thickness cannot be formed. On the other hand, if the heat treatment temperature is too high, there is a risk that the content of 2- or 3-ring aromatic hydrocarbon compounds, which are advantageous for securing excellent capacity characteristics and cycle stability, will decrease, and the content of monocyclic aromatic hydrocarbon compounds will increase. In view of the above, the temperature range for heat treating the petroleum residue distillate is preferably 100 to 350 ℃, or 150 to 400 ℃, or 150 to 350 ℃, or 200 to 400 ℃, or 200 to 350 ℃. It may be particularly preferably 200 to 300°C, or 200 to 280°C, or 220 to 300°C, or 220 to 280°C.

According to one embodiment of the present invention, the heat treatment time for the refined petroleum residue is preferably 10 minutes or more. The time for heating the refined petroleum residue may be more preferably 30 minutes to 6 hours, and even more preferably 30 minutes to 3 hours.

According to one embodiment of the present invention, it may include heating at a temperature increase rate of 3 to 7 °C/min from room temperature to a temperature of 100 to 400 °C, which is the temperature range for heat treatment of the petroleum residue distillate.

According to one embodiment of the present invention, the step of depositing a carbon coating precursor obtained by heat treating petroleum residue distillate may include deposition using physical vapor deposition (PVD). The physical vapor deposition method has the advantage of lowering the possibility of contamination of the material surface because vapor deposition occurs at low pressure and preventing problems caused by moisture.

According to one embodiment of the present invention, the atmosphere for heating the refined petroleum residue may be created as an inert atmosphere. Inert gases for creating an inert atmosphere may include, for example, nitrogen, helium, neon, or argon. Any inert gas commonly used in the relevant technical field may be used without being limited to the above types.

According to one embodiment of the present invention, the step of carbonizing the amorphous carbon coating layer includes heating the amorphous carbon coating layer at a temperature increase rate of 8 to 12 ° C./min to 800 to 1200 ° C. and then heat treating for more than 30 minutes. It can be included.

According to one embodiment of the present invention, a silicon oxide-based negative electrode active material manufactured according to the above-described manufacturing method can be provided.

According to one embodiment of the present invention, in the silicon oxide-based anode active material including particles containing SiOx (0<x≤2) and an amorphous carbon coating layer provided on the surface of the particles, Raman using a laser with a wavelength of 514 nm In spectrum analysis, I _D is the maximum peak intensity appearing from 1300 cm ^-1 to 1400 cm ^-1 , and I _G is the maximum peak intensity appearing from 1550 cm ^-1 to 1650 cm ^-1 . The peak intensity ratio I _D / I A silicon oxide-based negative electrode active material can be provided, characterized in that the _G value is 0.9 to 1.05, or 0.9 to 1.03. If the above-mentioned peak intensity ratio is satisfied, an amorphous carbon coating layer with the desired microstructure and thickness can be formed. If the peak intensity ratio range is not satisfied, a highly crystalline or thin carbon coating layer is formed, thereby reducing the diffusivity of lithium. As a result, there is a risk that the initial capacity and efficiency may be inferior.

According to an embodiment of the present invention, when analyzing surface XPS elements using an Al-Kα A negative electrode active material can be provided.

According to one example, the C content may be 80 at% or more, or 85 at% or more.

According to one example, the O content may be 5 to 15 at%, or 8 to 15 at%.

According to one example, the Si content may be 2 at% or less, or 1.5 at% or less, and may not be included, but is not particularly limited thereto.

According to an embodiment of the present invention, as a result of surface XPS C _1s detailed peak analysis using an Al-Kα Active materials can be provided.

C(1): C=C bond area ratio 70 to 85%;

C(2): C-C bond area ratio 5 to 25%;

C(3): C-O bond area ratio exceeding 0% and 5% or less;

C(4): O-C=O bond area ratio exceeding 0% and less than or equal to 5%;

Each area ratio is derived as a percentage of the area of each combined peak divided based on the total area of all peaks.

The C(1) C=C bond area ratio may preferably be 70 to 80%.

The C(2) C-C bond area ratio may preferably be 8 to 25%, or 10 to 25%.

The C(3) C-0 bond area ratio may preferably be more than 0% and 4% or less, or more than 0% and 3% or less.

The C(4) O-C=O bond area ratio may preferably be greater than 0% and less than or equal to 4%.

According to one embodiment of the present invention, the thickness of the amorphous carbon coating layer may be 10 to 30 nm. For the desired cycle stability, it is preferable that the thickness of the amorphous carbon coating layer is 10 nm or more. However, if the thickness exceeds 30 nm, there is a risk that initial capacity and efficiency may decrease.

Particles containing SiOx (0<x≤2) according to an embodiment of the present invention may have an average particle diameter of 1 to 10㎛. If the average particle diameter is less than 1㎛, a large amount of petroleum residue distillate is required to form the carbon coating layer, which is not desirable in terms of process efficiency. If the average particle diameter exceeds 10㎛, the density between particles increases and the SiOx content in the negative electrode active material decreases, which may reduce initial capacity and efficiency.

According to one embodiment of the present invention, a silicon oxide-based negative electrode containing the above-described negative electrode active material can be provided.

According to an embodiment of the present invention, a battery including the above-described negative electrode can be provided.

According to an embodiment of the present invention, a silicon oxide-based negative electrode active material coated with surface carbon is formed by forming an amorphous carbon coating layer on the surface of a silicon oxide-based negative electrode active material using a physical vapor deposition (PVD) method of petroleum residue distillate, and a surface carbon-coated silicon oxide-based negative electrode active material. Manufacturing methods can be provided.

According to one embodiment of the present invention, it is possible to provide a silicon-based oxide-based negative electrode active material with surface carbon coating that can upcycle refined petroleum residue, which is a low-cost raw material, and a method for manufacturing the same, which is excellent in economic efficiency and eco-friendliness.

The surface carbon-coated silicon-based oxide-based negative electrode active material according to an embodiment of the present invention has excellent capacity and excellent cycle stability.

The present invention will be described in more detail below based on examples and comparative examples. However, the following Examples and Comparative Examples are only one example to explain the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

{Example}

Manufacturing example

Carbon-coated silicon oxide-based anode active material

In the PVD method, the residual oil distillate is heated to a deposition temperature of 200 ℃, 250 ℃, and 300 ℃ at a temperature increase rate of 5 ℃/min under a nitrogen atmosphere, and then heat treated at the deposition temperature for 1 hour to obtain silicon as a carbon coating precursor. An amorphous carbon coating layer was deposited on the surface of particles containing oxide (SiOx) (0<x≤2). The residual oil distillate produced when pitch reforming pyrolysis fuel oil (PFO) (Yeocheon NCC) was used. The carbon coating precursor was named 200 fraction oil, 250 fraction oil, and 300 fraction oil according to the deposition temperature of 200 ℃, 250 ℃, and 300 ℃, respectively.

After depositing the amorphous carbon coating layer, it was heated at a temperature increase rate of 10°C/min and carbonized by heat treatment at 950°C for 1 hour to prepare a carbon-coated silicon oxide-based negative electrode active material. The prepared carbon-coated silicon oxide-based anode active material samples were named SiOx@C 200, SiOx@C 250, and SiOx@C 300 according to the deposition temperatures of 200 ℃, 250 ℃, and 300 ℃, respectively.

Manufacturing of half cells

The anode active material (SiOx@C 200, SiOx@C 250, SiOx@C 300) prepared as above, the conductive material super P, and polyvinylidene fluoride (PVDF) as a binder were used in a weight ratio of 94:3:3. The mixed mixture was dispersed in n-methyl-2-pyrrolidone (NMP) to prepare a negative electrode slurry.

The prepared cathode slurry was coated on aluminum foil and then dried at 120°C in a vacuum oven. After rolling and cutting the dried anode, a 2032 coin cell type half battery was manufactured using the prepared anode as a working electrode and lithium metal as a counter electrode. Celgard 2400 was used as a separator, and as an electrolyte, LiPF ₆ dissolved at 1.0M in a mixed solution of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) at a volume ratio of 1:1 was used.

Evaluation Example 1: Structural analysis of carbon coating precursor (200, 250, 300 fraction oil)

To analyze the structure of the carbon coating precursor according to the deposition temperature, the carbon coating precursor was diluted by 5 to 6 wt% in a 0.03 v/v% mixed solution of chloroform-d and tetramethylsilane (TMS) and subjected to ¹ H-NMR analysis (AVANCE III HD 400, Bruker Biospin, USA) was performed. Topspin 4.0.5 software was used to analyze the spectrum, and quantitative analysis of the type of hydrogen for each sample was performed using the integral value and area based on the peak position. ¹ To increase the reliability of H-NMR analysis, Fourier transform infrared spectrometer (FT-IR) analysis was subsequently performed.

¹ Through H-NMR spectrum analysis, peaks for polycyclic aromatic hydrocarbons (PAHs) in the carbon coating precursor are shown in Figure 1a. Aliphatic hydrocarbon compounds (R-CH ₂ -R', R-CH _3, etc.) were confirmed at levels above 2.0 ppm and below 6.0 ppm. Aromatic hydrocarbon compounds were found to be between 6.0 ppm and less than 9.0 ppm, monocyclic aromatic hydrocarbon compounds were found to be between 6.0 ppm and less than 7.2 ppm, dicyclic aromatic hydrocarbon compounds were found to be between 7.2 ppm and less than 7.8 ppm, and tricyclic aromatic hydrocarbon compounds were found to be above 7.8 ppm. It was confirmed to be less than 9.0 ppm.

In order to confirm the structural changes of these peaks in more detail, quantitative analysis of the hydrogen type for each sample was performed using the integrated value and area based on the peak position. Specifically, the percentage of the peak area at 2.0 ppm or more and less than 6.0 ppm compared to the total peak area at the detection peak 2.0 ppm or more and less than 9.0 ppm means the content of aliphatic hydrocarbon compounds, and the total peak area at the detection peak 2.0 ppm or more and less than 9.0 ppm. The percentage of the peak area at 6.0 ppm or more and less than 7.2 ppm compared to the peak area means the content of monocyclic aromatic hydrocarbon compounds, and the peak area at 7.2 ppm or more and less than 7.8 ppm compared to the total peak area at 2.0 ppm or more and less than 9.0 ppm of the detection peak. The percentage refers to the content of dicyclic aromatic hydrocarbon compounds, and the percentage of the peak area at 7.8 ppm to less than 9.0 ppm compared to the total peak area at detection peaks from 2.0 ppm to less than 9.0 ppm refers to the content of tricyclic aromatic hydrocarbon compounds. do.

The results of the quantitative analysis are shown in Figures 1B to 1D. Referring to Figure 1c, in the case of monocyclic aromatic compounds, it was confirmed that the content decreased and then increased as the temperature increased, to 20.52% for 200 fraction oil, 4.43% for 250 fraction oil, and 21.37% for 300 fraction oil. In the case of 2- and 3-ring polycyclic aromatic compounds, as temperature increases, 2 rings increase by 21.36% and 6.3%, respectively, in 200 fraction oil, 38.26% and 16.42%, respectively, in 250 fraction oil, and 27.34% and 11.07%, respectively, in 300 fraction oil. , it was confirmed that the content of tricyclic aromatic compounds increased and then decreased again. Referring to Figures 1c and 1d, the total aromatic compound content was found to be higher in 250 fraction oil and 300 fraction oil than in 200 fraction oil. In addition, it was confirmed that the content of total aromatic compounds was similar in 250 fraction oil and 300 fraction oil, but the highest content of di- and tri-ring aromatics was detected in 250 fraction oil.

The results of FT-IR analysis of 200, 250, and 300 fraction oils are shown in Figure 2. As a result of the analysis, peaks at 3050 cm ^-1 (aromatic CH stretch), 1599 cm ^-1 (aromatic C=C stretch), 2958 cm ^-1 (aliphatic CH stretch), and 1453 cm ^-1 (aliphatic CH stretch) were confirmed. Referring to the results in FIG. 2, similar results to the structural analysis through ¹ H-NMR analysis were confirmed.

Evaluation Example 2: Structural analysis of carbon-coated silicon oxide-based anode active material (SiOx@C 200, 250, 300)

To investigate the chemical bonding of the carbon coating layer of carbon-coated silicon oxide-based anode active material (C@SiOx 200, 250, 300), surface Scientific, USA) and Raman (LabRAM HR-800, Horiba, Japan) analysis were performed. The peaks at binding energies of approximately 103.8 eV, 154.6 eV, 284.2 eV and 532.5 eV refer to Si 1s, Si 2s, C 1s and O 1s peaks, respectively. Si 1s Si 2s and O 1s peaks are observed on the surface of silicon oxide-based anode active material (SiOx) without carbon coating, but Si 1s and Si 2s peaks are observed on the surface of carbon-coated silicon oxide-based anode active material (SiOx@C 200, 250, 300). The peak disappeared, and the C 1s peak could be confirmed. The results are shown in Figure 3a. Referring to the results of FIG. 3a, since XPS analysis can analyze surface chemical characteristics up to a depth of 10 nm, it is believed that the carbon coating was well formed to a thickness of 10 nm or more.

Figure 3b and Table 1 below show the atomic contents of silicon oxide-based negative electrode active material without carbon coating (SiOx) and carbon-coated silicon oxide-based negative electrode active material (SiOx@C 200, 250, 300). As a result, it was confirmed that SiOx@C 250 had the highest carbon content and the lowest oxygen and silicon contents.

Elemental composition [at%] C O Si SiOx 0.56 63.56 35.88 SiOx@C 200 86.80 12.27 0.93 SiOx@C 250 89.09 10.03 0.88 SiOx@C 300 88.00 10.83 1.17

Figures 3c, 3d, 3e and Table 2 below show the XPS C _1s detailed spectrum analysis results of the samples divided into four peaks, and from the C _1s detailed spectrum analysis results, C=C bond (284.8 eV), C-C bond ( 285.8 eV), CO binding (286.6 eV), and OCO binding (288.8 eV) peaks were confirmed. Referring to FIGS. 3c, 3d, 3e and Table 2, as the heat treatment temperature for the residual oil distillation increased, the area ratio of the C=C bond decreased and then increased, and the area ratio of the C-C bond increased and then decreased. . The area ratio of each peak in Table 2 was derived as a percentage of the area of each combined peak divided based on the total area of all peaks.

component binding energy [eV] SiOx@C 200 SiOx@C 250 SiOx@C 300 C=C 284.8 84.04% 76.42% 80.28% C-C 285.8 9.44% 17.21% 13.78% C-O 286.1 3.00% 2.48% 2.02% O=C-O 288.8 3.52% 3.89% 3.92%

The crystallinity and structural characteristics of the SiOx@C 200, 250, and 300 amorphous carbon coating layers were confirmed through Raman spectroscopy. The laser wavelength for Raman spectrum analysis was 514 nm and was measured in the range of 1,000 to 2,000 cm ^-1 . The Raman spectrum analysis results of SiOx@C 200, 250, and 300 are shown in Figures 4a, 4b, and 4c. Referring to FIGS. 4A to 4C, the SiOx@C 200, 250, and 300 samples carbonized through the carbonization step have a maximum peak intensity I _D at about 1360 cm ^-1 (D band, D for defect or disorder) and about 1580 cm. The maximum peak intensity I _G was confirmed at ^-1 (G band, G for graphitic). The peak intensity ratio I _D /I _G value of SiOx@C 250 was 1.01, but for SiOx@C 200 and 300, the peak intensity ratio I _D /I _G values decreased to 0.93 and 0.95, respectively.

To evaluate the carbon coating layer of SiOx@C 200, 250, and 300 samples in detail, the microstructure and thickness of the carbon coating layer were compared using TEM. As can be seen in Figures 4d to 4f, the TEM analysis results showed that an amorphous carbon coating layer was formed uniformly on the surface of the SiOx@C sample, and the thicknesses were confirmed to be approximately 13.8 nm, 24.6 nm, and 19.4 nm, respectively.

In addition, the morphology and element distribution of SiOx@C 200, 250, and 300 samples were analyzed through STEM and Energy dispersion spectroscopy (EDS). Referring to Figures 4g to 4h, the size of the SiOx particles is about 5 to 5.5 μm, and as a result of EDS analysis, it was confirmed that C was evenly distributed on the surface of the carbon-coated silicon oxide-based negative electrode active material. In particular, it was confirmed with the naked eye that the C content in SiOx@C 250 was higher than that in SiOx@C 200 and 300. This is believed to be because a large amount of 2- and 3-ring aromatics precipitated on the SiOx surface in 250 fraction oil, a carbon coating precursor, to form a thicker carbon coating layer, as confirmed through ¹ H-NMR and FT-IR analysis.

Evaluation Example 3: Evaluation of electrochemical properties of carbon-coated silicon oxide-based anode active material (SiOx@C 200, 250, 300)

To evaluate the electrochemical properties, 2032 coin cells were prepared using each carbon-uncoated silicon oxide-based negative electrode active material (SiOx) and carbon-coated silicon oxide-based negative electrode active material (SiOx@C 200, 250, 300) in the same manner as described in the manufacturing example. A type of half cell was manufactured.

As a result of checking the rate characteristics and C-rate efficiency, at 0.2C, 0.5C, 1.0C, and 2.0C, SiOx@C 200 is 1012.9 mAh/g, 802.9 mAh/g, 701.6 mAh/g, 515.4 mAh/g, SiOx@C 250 was 839.4 mAh/g, 660.1 mAh/g, 545.6 mAh/g, 417.4 mAh/g, SiOx@C 300 was 906.3 mAh/g, 738.7 mAh/g, 611.9 mAh/g, 470.0 mAh/g, SiOx@ C 250 showed the highest capacity. This means that as the peak intensity ratio I _D / I _G increases, the number of edge sites increases, and structural defects such as vacancies and bonding disorders occur, and these structural defects have a significant impact on the electronic structure, affecting lithium ion diffusion, i.e., rate characteristics. This is because it affects electrochemical properties. That is, from Figure 5a, it was confirmed that SiOx@C 250 with the highest I _D /I _G ratio showed the highest capacity.

The manufactured half-cell was charged and discharged for 100 cycles at a rate of 1.0 C, and the specific capacity according to the charge and discharge cycle is shown in Figure 5b. Referring to FIG. 5b, it was confirmed that the initial capacity of SiOx@C 200, 250, and 300 samples with a carbon coating layer was superior to that of SiOx without a carbon coating layer. In addition, SiOx@C 200 showed a lower initial capacity than SiOx@C 250 and SiOx@C 300, and in the case of SiOx@C 300, the initial capacity was similar to SiOx@C 250, but after 20 cycles, SiOx@C 250 Better cycle stability was confirmed. This is believed to be due to the formation of a thick carbon coating layer that alleviates the volume expansion of SiOx in SiOx@C 250, as shown in the above-mentioned TEM analysis results.

Claims (15)

An amorphous carbon coating layer is deposited on the surface of particles containing SiOx (0<x≤2) using a carbon coating precursor that satisfies the following conditions (1) to (4) obtained by heat treating petroleum residue distillate under an inert atmosphere. steps; and
It includes; carbonizing the deposited amorphous carbon coating layer,
The content of each hydrocarbon compound in the following conditions (1) to (4) was determined as a result of ¹ H-NMR spectrum analysis of the carbon coating precursor, compared to the total peak area at the detection peak of 2.0 ppm or more and less than 9.0 ppm. Method for producing a silicon oxide-based negative electrode active material, derived as a percentage of each peak area in the detection peak range of (4):
(1) The content of monocyclic aromatic hydrocarbon compounds detected at a detection peak of 6.0 ppm or more and less than 7.2 ppm is 30% or less;
(2) The content of dicyclic aromatic hydrocarbon compounds detected at a detection peak of 7.2 ppm or more and less than 7.8 ppm is 10 to 45%;
(3) The content of tricyclic aromatic hydrocarbon compounds detected at a detection peak of 7.8 ppm or more and less than 9.0 ppm is 3 to 20%;
(4) The content of aliphatic hydrocarbon compounds detected at a detection peak of 2.0 ppm or more and less than 6.0 ppm is 30 to 60%. According to paragraph 1,
A method for producing a silicon oxide-based negative electrode active material, wherein the temperature range for heat treating the petroleum residue distillate is 100 to 400 ° C. According to paragraph 2,
A method for producing a silicon oxide-based negative active material, comprising heating at a temperature increase rate of 3 to 7 ° C./min from room temperature to a temperature of 100 to 400 ° C., which is the temperature range for heat treatment of the petroleum residue distillate. According to paragraph 1,
A method for producing a silicon oxide-based negative electrode active material, wherein the sum of the content of the dicyclic aromatic hydrocarbon compound detected in condition (2) and the tricyclic aromatic hydrocarbon compound detected in condition (3) is 20% or more. According to paragraph 1,
The deposition step is,
A method of producing a silicon oxide-based negative electrode active material, comprising depositing using physical vapor deposition (PVD). According to paragraph 1,
The carbonization step is,
A method for producing a silicon oxide-based negative electrode active material, comprising heating the amorphous carbon coating layer at a temperature increase rate of 8 to 12 °C/min to 800 to 1200 °C and then heat treating for at least 30 minutes. According to paragraph 1,
A method for producing a silicon oxide-based negative electrode active material, wherein the petroleum residue oil is a product obtained by pitch reforming petroleum residue oil. A silicon oxide-based negative electrode active material manufactured according to the manufacturing method of any one of claims 1 to 7. In the silicon oxide-based negative electrode active material comprising particles containing SiOx (0<x≤2) and an amorphous carbon coating layer provided on the surface of the particles,
In Raman spectrum analysis using a laser with a wavelength of 514 nm, I _D is the maximum peak intensity appearing from 1300 cm ^-1 to 1400 cm ^-1 , and I _G is the maximum peak intensity appearing from 1550 cm ^-1 to 1650 cm ^-1 ,
A silicon oxide-based negative electrode active material, characterized in that the peak intensity ratio I _D /I _G value is 0.9 to 1.05. According to clause 9,
A silicon oxide-based negative electrode active material containing at% C: 80% or more, O: 5 to 15%, the remainder Si and other inevitable impurities, as determined by at% when surface XPS elemental analysis was performed using an Al-Kα X-ray source. According to clause 9,
As a result of surface XPS C _1s detailed peak analysis using an Al-Kα
C(1): C=C bond area ratio 70 to 85%;
C(2): CC bond area ratio 5 to 25%;
C(3): CO bonding area ratio exceeds 0% and is 5% or less;
C(4): OC=O bond area ratio exceeds 0% and does not exceed 5%. According to clause 9,
A silicon oxide-based negative electrode active material wherein the amorphous carbon coating layer has a thickness of 10 to 30 nm. According to clause 9,
A silicon oxide-based negative electrode active material, wherein the particles containing SiOx (0<x≤2) have an average particle diameter of 1 to 10 ㎛. A negative electrode comprising the negative electrode active material according to any one of claims 9 to 13. A battery comprising a cathode according to claim 14.