Negative electrode material for lithium ion secondary battery, manufacturing method therefor, and negative electrode for lithium ion secondary battery and lithium ion secondary battery comprising same

Abstract

A negative electrode material for a lithium ion secondary battery of the present invention is included in a negative electrode for a lithium ion secondary battery included in a lithium ion secondary battery of the present invention, and comprises: a hydrocarbon pyrolysis catalyst containing crystalline carbon; and deposited carbon formed by vapor-depositing carbon generated by hydrocarbon gas pyrolysis on the surface of the crystalline carbon on the catalyst. In addition, a method for manufacturing a negative electrode material for a lithium ion secondary battery of the present invention comprises: (A) a catalyst preparation step; and (B) a deposited carbon forming step. The present invention can provide: a negative electrode material for a lithium ion secondary battery, which is recyclable and has excellent rate characteristics; a manufacturing method therefor; and a negative electrode for a lithium ion secondary battery or a lithium ion secondary battery comprising same.

Description

Anode material for lithium-ion secondary batteries, method for manufacturing the same, anode for lithium-ion secondary batteries and lithium-ion secondary batteries containing the same

[0001] The present invention relates to a negative electrode material for a lithium ion secondary battery and a method for manufacturing the same, and more particularly, to a negative electrode material for a lithium ion secondary battery that is recyclable and has excellent rate characteristics (power characteristics), a method for manufacturing the same, a negative electrode for a lithium ion secondary battery including the same, and a lithium ion secondary battery.

[0002] Lithium-ion secondary batteries are secondary batteries that utilize an organic electrolyte containing lithium salts. These lithium-ion secondary batteries utilize metallic lithium as their anode material. However, when lithium ions precipitate in the form of dendrites, they can cause short circuits and ignition. To solve this problem, a technology was developed that uses crystalline carbon materials, such as graphite, instead of metallic lithium. This is because graphite does not have the problem of lithium ion precipitation in the form of dendrites during lithium ion absorption and release. However, crystalline carbon materials such as graphite, which have a high degree of graphitization and a highly developed hexagonal network structure, also have problems such as poor rate properties. To solve this problem, a technology combining crystalline carbon materials such as graphite with amorphous carbon has been developed. For example, a technology for utilizing composite particles in which amorphous carbon powder is bonded and coated with a carbide of binder pitch on the surface of graphite powder as a negative electrode material for lithium-ion secondary batteries has been known (see U.S. Patent Publication No. US 8,153,303 B2).

[0003] However, such technology has a relatively complex manufacturing process and is far from being a resource recycling technology.

[0004] [Prior Art Literature]

[0005] [Patent Document]

[0006] (Patent Document 1) U.S. Patent Publication No. US 8,153,303 B2, (April 10, 2012), specification

[0007] One technical problem that the present invention seeks to solve is to provide a negative electrode material for a lithium-ion secondary battery that is recyclable and has excellent rate characteristics.

[0008] Another technical problem to be solved by the present invention is to provide a method for manufacturing a negative electrode material for a lithium-ion secondary battery that is capable of resource recycling and has excellent rate characteristics.

[0009] Another technical problem to be solved by the present invention is to provide a negative electrode for a lithium-ion secondary battery including a negative electrode material for a lithium-ion secondary battery that is capable of resource recycling and has excellent rate characteristics.

[0010] Another technical problem to be solved by the present invention is to provide a lithium ion secondary battery including a lithium ion secondary battery negative electrode including a lithium ion secondary battery negative electrode material that is capable of resource recycling and has excellent rate characteristics.

[0011] The technical problems of the present invention are not limited to the problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0012] While researching negative electrode materials for lithium-ion secondary batteries, the inventors of the present invention have completed the invention, which is extremely effective in terms of resource recycling, which was not previously considered.

[0013] An anode material for a lithium ion secondary battery according to one embodiment of the present invention comprises a hydrocarbon pyrolysis catalyst including crystalline carbon; and deposited carbon formed by vapor-depositing carbon generated by pyrolysis of hydrocarbon gas on the catalyst onto the surface of the crystalline carbon.

[0014] In addition, the anode for a lithium ion secondary battery according to one embodiment of the present invention includes the anode material for a lithium ion secondary battery according to one embodiment of the present invention.

[0015] In addition, a lithium ion secondary battery according to one embodiment of the present invention includes a negative electrode for a lithium ion secondary battery according to one embodiment of the present invention.

[0016] In addition, a method for manufacturing a negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention includes (A) a catalyst preparation step of preparing a hydrocarbon thermal decomposition catalyst including crystalline carbon; and (B) a deposition carbon formation step of forming crystalline carbon by vapor-depositing carbon generated by thermally decomposing hydrocarbon gas on the catalyst prepared in step (A) onto the surface of the crystalline carbon to form deposition carbon, thereby obtaining crystalline carbon having the deposition carbon formed on the surface.

[0017] The present invention has the effect of providing a negative electrode material for a lithium-ion secondary battery that is recyclable and has excellent rate characteristics, and a negative electrode for a lithium-ion secondary battery or a lithium-ion secondary battery comprising the same. In addition, the present invention has the effect of providing a method for manufacturing a negative electrode material for a lithium-ion secondary battery that is recyclable and has excellent rate characteristics.

[0018] Figure 1 is a flowchart for explaining one embodiment of the present invention.

[0019] Figure 2 is a spectrum showing the results of Raman spectrum measurement before formation of deposited carbon in one experimental example of the present invention.

[0020] Figure 3 is a spectrum showing the results of Raman spectrum measurement after formation of deposited carbon in one experimental example of the present invention.

[0021] The advantages and features of the present invention, as well as the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined solely by the claims.

[0022] According to one embodiment of the present invention, a negative electrode material for a lithium ion secondary battery comprises a hydrocarbon pyrolysis catalyst including crystalline carbon; and deposited carbon formed by vapor-depositing carbon generated by pyrolysis of hydrocarbon gas on the catalyst onto the surface of the crystalline carbon.

[0023] As confirmed by the experimental results, since crystalline carbon acts as a positive catalyst for the hydrogen production reaction by hydrocarbon pyrolysis, hydrogen can be produced by hydrocarbon pyrolysis, and the carbon generated in the process vapor-deposits on the surface of the crystalline carbon to form deposited carbon. Also, as confirmed by the experimental results, the crystalline carbon with deposited carbon formed on the surface has improved rate characteristics that are lacking in the crystalline carbon, and thus can be utilized as a superior negative electrode material for lithium-ion secondary batteries. In other words, since the crystalline carbon can be used as a catalyst in hydrocarbon pyrolysis and then recycled as an negative electrode material for lithium-ion secondary batteries, it can be seen that the present invention is very effective in terms of resource recycling. In addition, according to the present invention, since the negative electrode material for lithium-ion secondary batteries can be produced by vapor deposition during the process of producing hydrogen through hydrocarbon pyrolysis without a separate heat treatment or coating process, it is possible to manufacture the negative electrode material for lithium-ion secondary batteries more simply. In addition, since the deposited carbon is formed more uniformly on the surface of the crystalline carbon by vapor deposition, it is more stable than the case where the carbon is formed unevenly on the surface of the crystalline carbon, and it can also exhibit the desired effect both technically and economically. Meanwhile, it was difficult to find a suitable use for the by-product carbon generated together with hydrogen during the conventional hydrocarbon pyrolysis, and an additional treatment process for recycling may be required. However, according to the present invention, it can be seen that the by-product carbon can be utilized very usefully both technically and economically without an additional treatment process.

[0024] Crystalline carbon may be carbon that is crystalline in its raw state, as well as carbon that has been at least partially crystalline through processing. Such crystalline carbon is not limited to graphite as long as it is crystalline. In addition, the graphite may be one or more selected from natural graphite or artificial graphite. Artificial graphite includes graphite that has optionally undergone a graphitization process, and also includes carbon materials such as graphitized needle coke. In addition, the crystalline carbon may be expressed as a degree of crystallinity by the interplanar spacing of the carbon hexagonal planes. For example, the crystalline carbon may have an interplanar spacing of the carbon hexagonal planes of less than 0.3400 nm (e.g., 0.3354 to 0.3399 nm). The crystalline carbon may preferably have a carbon purity of 95% or more, more preferably a carbon purity of 99% or more. In addition, the crystalline carbon may more preferably have an impurity content of 100 ppm or less.

[0025] To control purity in this way, the crystalline carbon can undergo a purification process, and through primary purification (e.g., flotation, etc.), the carbon purity can be increased to 95% or more, or through secondary purification (e.g., physical purification, chemical purification, and / or thermal purification, etc.), the impurity content can be controlled to 100 ppm or less, or the carbon purity can be controlled to 99% or more.

[0026] In addition, the crystalline carbon may be subjected to a grinding process (e.g., grinding for preferably 10 hours or less under an inert gas, air, oxygen, or a mixed atmosphere thereof) to control the particle size or specific surface area, and may be subjected to a spheroidization process together with or additionally after the grinding process.

[0027] Additionally, the crystalline carbon may be crystalline carbon coated with amorphous carbon.

[0028] Such crystalline carbon can be purchased commercially or manufactured using a well-known method.

[0029] In addition, the hydrocarbon pyrolysis catalyst is not limited as long as it contains crystalline carbon as a positive catalyst for the hydrogen production reaction by hydrocarbon pyrolysis, and it is of course not excluded that the hydrocarbon pyrolysis catalyst is composed only of crystalline carbon.

[0030] The hydrocarbon is not limited as long as it is thermally decomposed by the catalyst, but is preferably methane. Furthermore, the hydrocarbon gas may preferably be a methane-containing gas or natural gas. Thermal decomposition is preferably performed at 900°C or higher, more preferably between 950°C and 1,100°C. Below this range, thermal decomposition may be insufficient, and above this range, the need for catalyst application may diminish.

[0031] In addition, pyrolysis is preferably performed at a gas space velocity of 8000 hr. -1 Below (0hr) -1 Excluding, more preferably 400hr -1 8,000hr -1 ) can be implemented. Exceeding this range (8000hr) -1 There is a concern that thermal decomposition may be insufficient in excess of this range (400 hr) and below this range (400 hr) -1 There is concern that the increase in efficiency compared to the catalyst used (below) will not be significant.

[0032] Preferably, the crystalline carbon has a hydrocarbon conversion rate of 10% or more, a hydrogen selectivity of 20% or more, and the hydrocarbon conversion rate and hydrogen selectivity can be calculated under thermal decomposition conditions including a temperature condition of 900 degrees Celsius or more. By such crystalline carbon, hydrocarbon thermal decomposition can be performed more effectively, and deposited carbon can be formed. At this time, the thermal decomposition conditions are preferably a gas space velocity of 8000 hr. -1 Below (0hr) -1 Excluding, more preferably 400hr -1 8,000hr -1) may further include a gas space velocity condition. In addition, the volume of crystalline carbon may be 8000 hr of the gas space velocity of the hydrocarbon-containing gas. -1 Below (0hr) -1 Excluding, more preferably 400hr -1 8,000hr -1 ) can respond.

[0033] Such crystalline carbon may have a deposition surface on which the deposited carbon is deposited.

[0034] Deposited carbon is formed by vapor deposition of carbon generated by the thermal decomposition of hydrocarbon gas on the surface of crystalline carbon. This vapor deposition carbon is generally amorphous carbon with a plane distance of 0.3400 nm or more between the hexagonal carbon planes, and may be amorphous carbon with a relatively low crystallinity compared to crystalline carbon. As confirmed by the experimental results, the deposited carbon is non-graphitizable carbon (hard carbon) different from crystalline carbon or graphitizable carbon (soft carbon). This is because the crystalline carbon on which the deposited carbon is deposited exhibits improved rate characteristics (power characteristics) that are lacking in crystalline carbon.

[0035] Crystalline carbon with deposited carbon formed on the surface has high-rate properties. High-rate properties may be a capacity retention ratio in which the discharge capacity at 5.0 C-rate is 80% or more of the discharge capacity at 0.2 C-rate when charge and discharge are performed in a half-cell test method. Such discharge capacity may be based on the charge and discharge capacity evaluation of a half-cell formed with a cathode material as the cathode and lithium metal as the counter electrode. Unlike crystalline carbon, the interplanar distance of the carbon hexagonal network of deposited carbon may be 0.3400 nm or more.

[0036] Considering its usability as a negative electrode material, the crystalline carbon may be powdered carbon in the form of powder. This is because, in order to be utilized as a negative electrode material, a powder state suitable for the particle size or specific surface area required for the negative electrode material is desirable. Therefore, when considering its usability as a negative electrode material, the crystalline carbon preferably has an average particle size of 25㎛ or less (excluding the average particle size of 0㎛, more preferably 0.5㎛ to 25㎛). If this range is exceeded, there is a concern that the electrode charging rate may decrease, resulting in a decrease in charge / discharge capacity, and if it is below this range, there is a concern that the internal resistance of the electrode may increase due to the formation of excessive interfaces between particles. In addition, the crystalline carbon may preferably have a specific surface area of ​​30㎡ / g or less (excluding the specific surface area of ​​0㎡ / g, more preferably 3㎡ / g to 30㎡ / g). If this range is exceeded, there is a concern that the initial charge / discharge efficiency may decrease due to the formation of excessive surface SEI (Solid Electrolyte Interface), and if it is below this range, the electrode charging rate may be inhibited due to excessive particle size, and the input / output characteristics (charge / discharge characteristics) may decrease due to the reduction in the reaction area required for lithium ion intercalation and deintercalation. In addition, from the perspective of the catalyst, if this range is exceeded, there is a concern that the methane thermal decomposition efficiency may decrease, and if it is below this range, there are difficulties in handling, such as catalyst installation and filter attachment in the reactor, and there is a concern that plugging may increase during the fluidization reaction.

[0037] In addition, the crystalline carbon formed on the surface of the deposited carbon preferably has an average particle diameter of 30㎛ or less (excluding an average particle diameter of 0㎛, more preferably 0.6㎛ to 30㎛). If this range is exceeded, there is a concern that the charge / discharge capacity may decrease due to excessive surface formation of deposited carbon, and at the same time, the discharge capacity and initial charge / discharge efficiency may decrease due to excessive surface formation of amorphous carbon. If this range is less than this range, there is a concern that the effect of improving the rate characteristics may decrease due to the small amount of surface formation of amorphous deposited carbon.

[0038] In addition, the crystalline carbon formed on the surface of the deposited carbon may have a specific surface area of ​​30 m2 / g or less (excluding a specific surface area of ​​0 m2 / g, preferably 3 m2 / g to 30 m2 / g). If this range is exceeded, there is a concern that the initial charge / discharge efficiency may decrease due to excessive SEI formation, and if this range is lowered, there is a concern that the electrode charging rate may decrease due to excessive particle size, resulting in a decrease in the discharge capacity.

[0039] In addition, with respect to 100 parts by weight of crystalline carbon, the amount of deposited carbon may be preferably 5 to 50 parts by weight (more preferably 5 to 25 parts by weight). Below this range, the amount of amorphous carbon deposited may decrease, which may not significantly contribute to improving the rate characteristics for discharging a large current in a short period of time, and there is a concern that the deposition may not be evenly distributed on the surface of the crystalline carbon. In addition, above this range, there is a concern that the amount of amorphous carbon formed on the surface of the crystalline carbon may be excessive, which may lower the discharge capacity and initial charge / discharge efficiency.

[0040] The negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention is included in the negative electrode for a lithium ion secondary battery according to one embodiment of the present invention, and the negative electrode for a lithium ion secondary battery according to one embodiment of the present invention is included in the lithium ion secondary battery according to one embodiment of the present invention. In addition, the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention can be manufactured by the method for manufacturing the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention. In order to avoid unnecessary duplication, in the description of each of the negative electrode for a lithium ion secondary battery according to one embodiment of the present invention, the lithium ion secondary battery according to one embodiment of the present invention, and the method for manufacturing the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention, matters mentioned in the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention may not be separately mentioned. However, the matters mentioned in the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention, the negative electrode for a lithium ion secondary battery according to one embodiment of the present invention, the lithium ion secondary battery according to one embodiment of the present invention, and the method for manufacturing the negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention are equally applicable to each other unless they are contradictory.

[0041] Specifically, a negative electrode for a lithium ion secondary battery according to one embodiment of the present invention includes a negative electrode material for a lithium ion secondary battery according to one embodiment of the present invention, and can be manufactured by a known method for manufacturing a negative electrode for a lithium ion secondary battery.

[0042] In addition, a lithium ion secondary battery according to one embodiment of the present invention includes a negative electrode for a lithium ion secondary battery according to one embodiment of the present invention, and can be manufactured by a known method for manufacturing a lithium ion secondary battery.

[0043] In addition, a method for manufacturing an anode material for a lithium ion secondary battery according to an embodiment of the present invention is described with reference to FIG. 1. FIG. 1 is a flowchart for explaining an embodiment of the present invention. As illustrated in FIG. 1, a method for manufacturing an anode material for a lithium ion secondary battery according to an embodiment of the present invention includes (A) a catalyst preparation step, and (B) a deposition carbon formation step.

[0044] (A) The catalyst preparation step is a step for preparing a hydrocarbon thermal decomposition catalyst containing crystalline carbon. In addition, (B) the deposition carbon formation step is a step for forming deposition carbon by vapor-depositing carbon generated by thermal decomposition of hydrocarbon gas on the catalyst prepared in step (A) onto the surface of the crystalline carbon, thereby obtaining crystalline carbon having the deposition carbon formed on the surface. By this method, an anode material for a lithium ion secondary battery can be effectively manufactured.

[0045] In addition, the method for manufacturing a negative electrode material for a lithium-ion secondary battery according to one embodiment of the present invention may further include a (C) hydrogen collection step. The hydrogen collection step is a step for collecting hydrogen generated by thermal decomposition in step (B). Hydrogen collection can be performed using a known method. Through this hydrogen collection step, hydrogen, a useful substance, can also be obtained. Therefore, it can be seen that the present invention is highly desirable from the perspective of resource utilization and recycling.

[0046] Hereinafter, with reference to experimental examples and working examples, one embodiment of the present invention will be described in more detail. The reagents used in the experimental examples were of the highest quality commercially available, purchased from Sigma and others.

[0047] <Example 1> Manufacturing of cathode material using crystalline carbon (natural graphite)

[0048] Crystalline carbon (natural graphite) was used as a hydrocarbon pyrolysis catalyst to manufacture cathode materials for lithium-ion secondary batteries. Hydrogen was also produced during the cathode material manufacturing process, and experiments were conducted to verify the effectiveness of this hydrogen production.

[0049] <Cathode Material Manufacturing and Hydrogen Production>

[0050] The crystalline carbon (natural graphite) sample was a sieved sample (Korea Mining and Resources Corporation, carbon content 95.7%, specific surface area 2.45 m2 / g, average particle size D50 84 μm) obtained through flotation and primary grinding. Natural graphite was placed in a prepared planetary mill (Retsch, PM200) equipped with a safety lock and a vented lid to allow for gas atmosphere control, and the mixture ratio of inert gas and oxygen was varied while grinding for 1 to 10 hours (see Table 1). Afterwards, particle size classification was performed using standard mesh sieves of 38 μm, 45 μm, 75 μm, 90 μm, and 125 μm.

[0051] Planetary Mill, PM2001×Planetary machine, 100-240V, 50 / 60Hz2×Grinding stations for jars for 125ml with safety closure device and aeration lidMax speed 650rpm

[0052] The classified samples were measured for particle size distribution separately. First, samples with particle sizes of 38 μm or less and larger than 38 μm were separated using a vacuum suction type sieve classifier (Retsch, AS200 Jet) equipped with a 38 μm standard mesh screen. Approximately 50-100 g of natural graphite sample per time was placed on the 38 μm standard mesh screen and maintained under conditions of rotation (nozzle rotation speed 15 rpm) and reduced pressure (industrial vacuum cleaner, GM80) for 1 minute and 30 seconds. After that, natural graphite samples with particle sizes of 38 μm or less were collected into a 500 mL sample bottle (see Table 2).

[0053] Reduced pressure suction type sieve classifier, AS200 Jet1×Air jet machine, 100-240V, 50 / 60Hz1×Cyclone with holder and collecting receptacle, 500mL sample bottle1×Industrial vacuum cleaner GM80, 230V, 50 / 60 Hz1×Test Sieve, ASTM E11, 8"(203mm)x1", stainless stell, with compliance certificate acc. EN 10204 2.1

[0054] The above process was repeated, and the sample remaining on the top of the 38㎛ standard mesh screen (>38㎛) was collected for the next crushing and classified using a 3D vibrating sifter (Retsch, AS200 Control) equipped with each standard mesh screen. The AS200 Control was equipped with a collecting pan, 38㎛, 45㎛, 75㎛, 90㎛, and 125㎛ standard mesh screens in that order. About 100 g of the collected sample exceeding 38㎛ was placed on the top of the 125㎛ standard mesh screen at each time, and classification was performed while maintaining the vibration intensity at 1.3 mm (see Table 3).

[0055] 3D Vibratory Sieve Shaker (AS200 Control)1×Vibratory Sieve Shaker(AS200 Control), 100-240V, 50 / 60Hz1×Clamping Device “Comport” for Test Sieves 200 / 203Φ1×Test Sieve, ISO 3301 / 1, 200x50mm, 38㎛, 45㎛ and 75㎛ and 90㎛ and 125㎛, stainless steel, with compliance certificate acc. EN10240 2.11×Collecting pand, stainless steel, Φ200x50mm

[0056] The sample remaining on the top of the 38㎛ standard mesh sieve (>38㎛) was placed in a planetary mill and ground for 1-10 hours with various mixing ratios of inert gas and oxygen. The average particle size was evaluated through surface area evaluation and particle size analysis. The results of particle size analysis were compared, and samples with smaller particle sizes and smaller specific surface areas were ground using a jet mill (Hosokawa, MICRON JET-MJQ) (see Table 4).

[0057] MICORON JET-MJQ-LABMill Compressed air[Nm 3 / min] : 1Classifier motor [kW] : 1.5Dimensions[mm] : H×W×D=280×480×280

[0058] The average particle size was analyzed using a Particle Size and Shape Analyzer (Model: MICROTRAC, CAMSIZER X2). Using the dynamic image analysis (Dynamic Image Analysis-ISO 13322-2) measurement principle, 5 g of each of the above-mentioned classified samples was injected into the X-jet Module, and if equipment capable of air pressure dispersion was used to disperse any clumped samples, it was measured using a dry method (see Table 5).

[0059] Particle size analyzer (MICROTRAC, CAMSIZER X2) 1xModule "X-Dry" with "X-Jet" plug-in cartridge 1㎛ to 1.5㎜Measuring time: 2 minutesMeasuring principle: Dynamic Digital Image Processing (ISO 13322-2)Measuring speed: >275 images / sec. each with approx. 1.3 MPixel

[0060] The evaluation of hydrocarbon (methane) pyrolysis using natural graphite powder as crystalline carbon with controlled particle size and specific surface area was carried out according to the following procedure. At this time, the specific surface area was measured by the nitrogen BET method according to the known method (AV Neimark, Y. Lin, PI Ravikovitch, M. Thommes, Quenched solid density functional theory and pore size analysis of micro-mesoporous carbons, Carbon 47 (7) (2009) 1617-1628.). Specifically, about 0.1 g of the sample was evacuated and heated at 300 degrees Celsius for 12 hours to remove moisture and impurities, and then cooled to room temperature. The weight of the dried sample was recorded and the sample cell was mounted on the equipment (see Table 6). The nitrogen pressure applied to the sample was sequentially increased from 0 to 1 atm, and the amount of nitrogen adsorbed by the sample was measured as cm 3 / g is measured, and the volume of nitrogen adsorbed per 1.0g of sample is obtained. Afterwards, the acquired data is substituted into the BET theory for the nitrogen adsorption amount according to pressure, and the slope and Y-intercept of the graph converted by the BET equation are used to calculate the specific surface area of ​​the sample in units of m2 / g. The nitrogen adsorption amount according to pressure is substituted into the BJH and NLDFT theory equations, respectively, to obtain a pore size distribution graph to confirm the pore size.

[0061] BELSORP-MAX, Microtrac BELAnalysis and Degas Manifold System (independently)- 1×analysis manifold (turbo molecular pump + Oil vacuum pump)- 1×degas manifold (Oil vacuum pump)Sample Port; 3 ports (Simultaneously measurement)- Low pressure measurement - 1 samples- High accuracy measurement - 2 samples- Standard measurement - 3 samplesPressure Sensor ; 7 ea (Standard)- 5×133 kPa (1000 torr); accuracy ±0.25% FS- 1×13.3 kPa (10 torr) ; accuracy ±0.5% R- 1×0.133 kPa (1 torr) ; accuracy ±0.15% R

[0062] The evaluation of catalytic pyrolysis and hydrogen production of methane-containing gas is conducted as follows. A tubular quartz reactor (outer diameter 1.0 in, inner diameter 23 mm) is installed in a heating furnace capable of heating to the pyrolysis temperature under atmospheric pressure (1 atm), and crystalline carbon is installed between the upper and lower filters of the tubular reactor to prevent leakage during the pyrolysis process. The temperature maintenance section (±10℃, 800 mm) of the heating furnace is confirmed and set through a temperature profile before the experiment to set the gas space velocity (GHSV). Nitrogen gas is flowed up to the target heating temperature, and when the target pyrolysis temperature is reached, nitrogen gas (99.99%) and methane gas (99.95%, N35) are switched to flow only methane gas. The gas flow rate is controlled by an MFC (ATOVAC GMC1200) to maintain a constant space velocity. The temperature of the reactor is controlled through the PID (YOKOGAWA UP35A) in the controller.

[0063] The components of the gas generated after pyrolysis are evaluated using a gas chromatograph equipped with a thermal conductivity detector (TCD), a flame ionization detector (FID), and a metanizer, and a mass spectrometer. If the total proportion of unreacted methane and gases other than hydrogen generated after pyrolysis is less than 0.1%, it is ignored and the hydrocarbon conversion (based on methane) and hydrogen selectivity are evaluated using the following equation.

[0064] [Formula 1]

[0065]

[0066] In Equation 1, CH 4.전환 is the concentration (volume %) of injected methane gas converted to other gases, CH 4,주입 Silver represents the concentration of injected methane gas (volume %), H2 (%) represents the concentration of hydrogen gas (volume %) generated during pyrolysis, and CH4 (%) represents the concentration of methane gas (volume %) remaining after pyrolysis.

[0067] [Formula 2]

[0068]

[0069] In Equation 2, the amount of hydrogen generated and the amount of total generated gas represent the content (volume%) of hydrogen gas in the total pyrolysis gas after pyrolysis and the total amount (volume%) of the total pyrolysis gas, respectively. Here, the total pyrolysis gas includes unreacted methane gas.

[0070] The ratio of the amount of catalyst and the methane-containing gas, which is the target gas for thermal cracking, is based on the weight hourly space velocity or gas hourly space velocity.

[0071] [Formula 3]

[0072]

[0073] In Equation 3, Q feed gas represents the amount of gas injected per hour, and m catalyst represents the catalyst mass.

[0074] [Formula 4]

[0075]

[0076] In Equation 4, Q feed gas represents the amount of gas injected per hour, and V catalyst represents the catalyst volume.

[0077] The efficiency of conversion of hydrocarbons into hydrogen by a catalyst is evaluated through the following process.

[0078] (1) After installing a certain amount of catalyst in the central part of the vertical tube, fix the position by installing filters on the upper and lower parts of the catalyst layer, and take care to prevent leakage of reactants and products during the reaction process after installing the catalyst.

[0079] (2) The temperature of the reaction section including the catalyst is raised to the reaction temperature, and when the temperature stabilizes, injection of methane gas at a certain concentration is started.

[0080] (3) To determine the type and amount of products generated during the thermal decomposition process, a gas chromatograph (GC) equipped with a valve is connected to the rear end of the reactor (product gas outlet) and analyzed at regular time intervals.

[0081] (4) In the product analysis process, GC / MS analysis is first performed for qualitative analysis, and then GC / TCD / Methanizer-FID analysis is additionally performed for accurate quantitative analysis. The operating conditions of GC / MS and GC / TCD / Methanizer-FID applied for analysis are as follows (see Table 7).

[0082] GC(TCD), Agilent 6890NGC(TCD / FID), GC(TCD), Agilent 6890NGC-MS, Agilent 6890N Column Carboxen TM1010 PLOT FUSED SILICA Capillary Column,LxI.D., Avg. thickness: 30m×0.53mm×30㎛80 / 100 Porapak QL×Avg. thickness: (6ft×1 / 8in×2.1mm SS)19091P-K15 HP-AL / KCL L×Avg. thickness: 50m×0.320mm×8.00㎛)Operating conditionsOven50℃(2min hold)-250℃(3min hold), 20℃ / minTCD: 200℃Inlet: 200℃Oven50℃(1.5min hold)-200℃(1.0min hold), 20℃ / minTCD: 250℃FID: 250℃Inlet: 200℃Methanizer: 375℃Oven40℃(4.8min hold)-50℃(3.0min hold), 2℃ / min,50℃-150℃(10min hold)25℃ / min

[0083] (5) From the analysis results, the result value is calculated using the above formula.

[0084] The methane-containing gas components are as shown in Table 8 below, and the methane conversion rate and hydrogen selectivity by particle size (temperature 950 degrees Celsius, space velocity 400 hr) -1 The standard) is as shown in Table 9 below.

[0085] Methane-containing gas component concentration CH4≥99.95% N2≤130 ppm O2≤30 ppm C2H6≤300 ppm H2≤20 ppm H2O≤20 ppm

[0086] Example particle size (D50) [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -10.5hr1.0hr2.0hr3.0hr4.0hr5.0hr1-1>125(145.25)2.43Methane conversion rate[%]36.6834.9934.2034.0534.0534.0934.68Hydrogen selectivity[%]53.8652.2251.2451.0751.0651.0951.761-2>90,≤125(99.98)2.52Methane conversion rate[%]36. 5934.7133.9133.5933.4333.3434.26 Hydrogen selectivity [%] 52.2950.3749.6449.5449.6249.8250.211-3 >75,≤90 (65.41) 2.46 Methane conversion [%] 35.0733.8233.3733.2333.1233.0833.62 Hydrogen selectivity [%] 51.9150.8350.5350.595 0.6150.6450.851-4>45,≤75(56.67)2.48Methane conversion[%]38.1836.5235.3834.9534.6834.4635.70Hydrogen selectivity[%]55.6054.1052.7352.2952.1051.9853.131-5>38,≤45(35.05)2.44Methane conversion[%]36.9538.9036.9935. 9935.3735.0436.54Hydrogen selectivity [%]55.7558.5156.3555.0854.2653.8455.631-6≤38(25.35)2.44Methane conversion [%]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity [%]59.1459.1157.8357.0256.6956.5657.731-7Above Mixed sample of particle size (84.0) 2.45 Methane conversion [%] 41.84 40.00 37.04 35.77 35.00 34.66 37.39 Hydrogen selectivity [%] 59.09 57.31 54.16 52.77 51.93 51.57 54.47 1-8 (D50) 16.5 16.2 Methane conversion [%] 37.48 37.50 36.94 36.54 36.14 35.97 36.78 Hydrogen selectivity [%] 53.16 54.16 53.8 353.54 53.36 53.29 53.58

[0087] As shown in Table 9, it can be seen that hydrocarbons can be effectively thermally decomposed to produce hydrogen using natural graphite (carbon purity of 95% or more).

[0088] Meanwhile, in Table 9, Example 1-8 is a sample prepared by grinding the sample (>38 ㎛) remaining on the top of the 38 ㎛ standard mesh sieve using a jet mill (HOSOKAWA, MICRON JET-MJQ), unlike Examples 1-1 to 1-7. This is because, compared to Examples 1-1 to 1-7, the specific surface area is large (30 m 2 / g or less) also effectively removes hydrocarbons (950 degrees Celsius, 400 hr) -1 It indicates that hydrogen can be produced by thermal decomposition with a methane decomposition rate of 30% or higher and a hydrogen selectivity of 50% or higher.

[0089] Thus, from the catalytic action of natural graphite, which thermally decomposes hydrocarbons to produce hydrogen, we can see that the carbon generated during the thermal decomposition process is deposited on the surface of natural graphite. This is because the carbon generated during the thermal decomposition process is amorphous carbon, deposited on the surface of natural graphite through vapor deposition. This fact can also be confirmed by the experimental results below.

[0090] Raman spectroscopy

[0091] Raman spectroscopy was performed on samples before and after pyrolysis, and it was confirmed that carbon was deposited on the surface of the crystalline carbon. Specifically, the same sample as Example 1-6 was divided into samples before and after pyrolysis, and each sample was used as a Raman spectroscopy. D / I G The values ​​were measured. Raman spectroscopy was performed using an NRS-3200 Laser Raman Spectroscope (JASCO, Japan). Measurements were performed on pelletized samples using a 514.5 nm argon ion laser beam in a nitrogen atmosphere.

[0092] The results are shown in Fig. 2 and Fig. 3. Fig. 2 is a spectrum showing the results of Raman spectrum measurement for a sample before the formation of deposited carbon, and Fig. 3 is a spectrum showing the results of Raman spectrum measurement for a sample after the formation of deposited carbon. As shown in Fig. 2 and Fig. 3, the crystalline carbon before the deposition of deposited carbon is I D / I G The value is 0.1857, and the crystalline carbon deposited after pyrolysis is I D / I G It can be seen that the value is 1.478. In the case of carbon materials, 1580 cm is derived from the graphite structure (sp2 bonding). -1 The peak near 1350 cm (hereinafter abbreviated as G band) and the diamond structure (sp3 bonding) -1 It consists of a peak (hereinafter referred to as D band) near the G band. The D band is also thought to be a peak due to defects in the graphite structure. In the case of amorphous carbon materials, both peaks are expressed relatively widely, and in crystalline carbon with a high degree of graphitization, the D band peak is smaller than the G band peak, whereas in amorphous carbon such as activated carbon or carbon black, the D band peak is expressed large. The intensity ratio of the peaks of the G and D bands (I D / I G ) is used as an indicator of the degree of amorphous carbon (see TANSO 1996 [No.175] 304-313, Raman Spectroscopy of Graphite and Carbon Materials and Its Recent Application, Gen Katagiri). In particular, in the case of Raman spectroscopy, unlike XRD diffraction, which expresses the average structure of the entire carbon material through the transmission of a beam, the surface structure of the carbon material can be expressed and analyzed more sensitively. Therefore, from the results of this experiment, it can be reconfirmed that amorphous carbon is deposited on the surface of crystalline carbon by hydrocarbon pyrolysis.

[0093] <Example 2> Manufacturing of cathode material using crystalline carbon (carbon purity 99%)

[0094] Using natural graphite (Korea Institute of Energy Research) with a carbon purity of 99% as crystalline carbon, a negative electrode material was manufactured in the same manner as in Example 1, and experiments were conducted. The results are shown in Table 10.

[0095] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr2(D50)17.35.8Methane conversion [%]38.1838.337.4937.2136.9836.7937.51Hydrogen selectivity [%]53.8654.9554.3954.2254.254.0954.31

[0096] As shown in Table 10, it can be seen that even with natural graphite (carbon purity of 99% or more), hydrocarbons can be effectively thermally decomposed to produce hydrogen and manufacture cathode materials.

[0097] <Example 3> Manufacturing of negative electrode material using spheroidal crystalline carbon

[0098] Using spheroidized natural graphite (Elbs graphite) as crystalline carbon, a negative electrode material was manufactured in the same manner as in Example 1, and experiments were conducted. The results are shown in Table 11.

[0099] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr3(D50)16.32.88Methane conversion [%]36.6834.9934.2034.0534.0534.0934.68Hydrogen selectivity [%]53.8652.2251.2451.0751.0651.0951.76

[0100] As shown in Table 11, it can be seen that even with spheroidal crystalline carbon, hydrocarbons can be effectively thermally decomposed to produce hydrogen and manufacture cathode materials.

[0101] <Example 4> Manufacturing of cathode material using crystalline carbon with spheroidal / amorphous carbon coating

[0102] Using spheroidized / amorphous carbon-coated natural graphite (POSCO Chemical, PAS-C3B), a cathode material was manufactured in the same manner as in Example 1, and experiments were conducted. The results are shown in Table 12.

[0103] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr4(D50)17.35.8Methane conversion [%]37.6037.6037.6437.7637.8437.9037.72Hydrogen selectivity [%]52.2452.2552.1852.1452.1252.1452.18

[0104] As shown in Table 12, natural graphite coated with amorphous carbon after spheroidization can also effectively thermally decompose hydrocarbons to produce hydrogen and manufacture cathode materials.

[0105] <Example 5> Manufacturing of cathode material using crystalline carbon (artificial graphite)

[0106] Using artificial graphite (Showa Denko, SCMG-BH) as crystalline carbon, a negative electrode material was manufactured in the same manner as in Example 1, and the experiment was conducted. The results are shown in Table 13.

[0107] Example particle size [㎛] specific surface area [㎡ / g] thermal decomposition temperature, space velocity thermal decomposition time average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr5(D50)22.02.5Methane conversion [%]36.2735.935.6735.5335.535.4835.73Hydrogen selectivity [%]53.3653.1152.8952.7552.7152.6952.92

[0108] As shown in Table 13, artificial graphite can also effectively thermally decompose hydrocarbons to produce hydrogen and manufacture cathode materials.

[0109] <Example 6> Manufacturing of cathode material using crystalline carbon (graphitized needle coke)

[0110] Using needle coke graphitized with crystalline carbon, a cathode material was manufactured in the same manner as in Example 1, and an experiment was conducted. The results are shown in Table 15. Graphitized needle coke is an artificial graphite with a carbon hexagonal network plane distance of 0.3394 nm. Needle coke (manufactured by JX) with the specifications described in Table 14 was used after graphitization treatment (2800°C, 10 minutes).

[0111] Item Needle coke Moisture content [%] 0.1 Ash [%] <0.1 True density [g / cm3] 2.13 Apparent density [g / cm3] 1.80 Particle size [%] <5 ㎛ 40 Sulfur content [%] 0.4 Nitrogen content [%] 0.4

[0112] Example: Pyrolysis temperature, space velocity, pyrolysis time, average 950℃, 400hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr6Methane conversion rate [%]43.244.544.344.744.244.344.2Hydrogen selectivity [%]59.960.761.261.361.361.560.1

[0113] As shown in Table 15, graphitized needle coke can also be used to produce hydrogen and manufacture cathode materials by thermally decomposing hydrocarbons.

[0114] <Experimental Example 1> Experiment to confirm the effect according to the specific surface area of ​​crystalline carbon

[0115] Using natural graphite (carbon purity 95%, Korea Mining and Energy Corporation) as crystalline carbon as described in Table 16, a negative electrode material was manufactured in the same manner as in Example 1, and an experiment was conducted. The results are shown in Table 16.

[0116] Example Surface area [㎡ / g] Average particle size [D50, ㎛] Methane conversion rate [%], average hydrogen selectivity [%], average reference 7-1350.01.718.4935.82 Temperature: 950℃, Space velocity: 400hr -1Thermal decomposition time: 5hr7-2240.15.021.4038.747-3131.112.426.7240.577-465.635.728.9144.657-529.665.431.6548.567-62.4583.737.0253.80

[0117] As shown in Table 16, as the specific surface area decreases, hydrogen production tends to be more effective, and thermal decomposition occurs more effectively. Thus, by adjusting the specific surface area, hydrogen production can be controlled, and as a result, cathode materials containing various amounts of deposited carbon can be manufactured.

[0118] <Experimental Example 2> Experiment to confirm the effect according to pyrolysis temperature

[0119] For the same sample as Example 1-6, the thermal decomposition temperature was changed to the temperature described in Table 17, and the negative electrode material was manufactured and tested in the same manner as Example 1. The results are shown in Table 17.

[0120] Example Temperature [℃] Space velocity thermal decomposition time Average 400 hr -1 0.5hr1.0hr2.0hr3.0hr4.0hr5.0hr8-1850Methane conversion rate [%]3.953.913.964.084.224.344.08Hydrogen selectivity [%]7.727.637.727.948.218.437.948-2900Methane conversion rate [%]10.3110.6011.0411.9912.9013.1411.66Hydrogen selectivity [%]19.5219.7020.3421.8723.3224 .7321.588-3950Methane conversion [%]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity [%]59.1459.1157.8357.0256.6956.5657.738-41000Methane conversion [%]56.8455.9154.7654.4154.3854.4655.13Hydrogen selectivity [%]73.4072.6071.5771.2471.1771.2071.86

[0121] As shown in Table 17, when the pyrolysis temperature is 900 degrees Celsius or higher, the hydrocarbon conversion rate (based on methane) is 10% or higher, and the hydrogen selectivity is 20% or higher. In addition, when the pyrolysis temperature is 950 degrees Celsius or higher, the hydrocarbon conversion rate (based on methane) is 30% or higher, and the hydrogen selectivity is 50% or higher. From these experimental results, it can be seen that when the pyrolysis temperature is preferably 900 degrees Celsius or higher, and more preferably 950 degrees Celsius or higher, pyrolysis occurs more effectively, and hydrogen production is also more effective. In this way, by controlling the pyrolysis temperature, hydrogen production can be controlled, and as a result, cathode materials containing various contents of deposited carbon can be manufactured.

[0122] <Experimental Example 3> Experiment to verify the effect according to space velocity

[0123] For the same sample as Example 1-6, the space velocity was changed to the value described in Table 18, and the negative electrode material was manufactured in the same manner as Example 1, and the experiment was conducted. The results are shown in Table 18.

[0124] Example space velocity [hr -1] Temperature Pyrolysis Time Average 950℃ 0.5hr 1.0hr 2.0hr 3.0hr 4.0hr 5.0hr 9-1200 Methane Conversion Rate [%] 38.86 37.60 38.95 39.07 38.79 38.42 38.62 Hydrogen Selectivity [%] 51.10 54.38 56.31 56.62 56.48 56.19 55.18 9-2400 Methane Conversion Rate [% ]38.1938.2037.4136.9136.6636.5137.31Hydrogen selectivity[%]59.1459.1157.8357.0256.6956.5657.739-3500Methane conversion[%]33.0632.6932.3932.2332.2632.2932.49Hydrogen selectivity[%]51.7351.6851.5 051.1351.1951.2251.419-42000Methane conversion rate [%] 27.2227.7128.1828.3528.3628.0127.97Hydrogen selectivity [%] 41.3542.8443.8344.2044.4444.1943.489-54000Methane conversion rate [%] 26.4226.1925.6625.542 5.5125.5225.81 Hydrogen selectivity [%] 45.1844.8243.2942.1741.7641.7143.169-68000 Methane conversion [%] 19.4921.8022.9922.1222.3622.4721.87 Hydrogen selectivity [%] 32.9842.9549.2844.0044.9744.4343.10

[0125] As shown in Table 18, 8000hr -1 It shows a methane conversion rate of more than 20% at a space velocity of 500 hr. -1 It can be seen that a more significant methane conversion rate of over 30% is achieved at a space velocity of . In this way, by controlling the space velocity, hydrogen production can be controlled, and as a result, cathode materials containing various contents of deposited carbon can also be manufactured.

[0126] <Experimental Example 4> Experiments on the manufacture and performance evaluation of various cathode materials, cathodes, and secondary batteries.

[0127] By controlling the pyrolysis time, space velocity, and pyrolysis temperature, and by controlling the amount of carbon deposition, various negative electrode materials were manufactured, and negative electrodes including the negative electrode materials and secondary batteries (in the form of a half-cell) including the negative electrodes were manufactured, and performance evaluation experiments were conducted.

[0128] First, for the same sample as in Examples 1-6, pyrolysis was performed under the conditions described in Tables 19 and 20, but the pyrolysis experiment was conducted in the same manner as in Example 1. At this time, the pyrolysis time, space velocity, and pyrolysis temperature were adjusted to control the deposition amount of the deposited carbon. In addition, the deposition amount of the deposited carbon was calculated as a value measured by a weighing method that measures the weight of the sample before and after deposition. Specifically, the weight before and after deposition was measured immediately using a precision balance (METTLER TLEDO, ME204) after the sample was stored for 2 hours under constant temperature and humidity conditions (25 degrees Celsius, 60% relative humidity), and the deposition amount was expressed as a percentage by dividing the weight increase (the value obtained by subtracting the weight before deposition from the weight after deposition) by the weight before deposition. The crystalline carbon formed on the surface of the deposited carbon obtained as a result of the pyrolysis experiment was collected as an anode material for a lithium-ion secondary battery.

[0129] For the lithium-ion secondary battery negative electrode material collected in this manner, a half-cell of the lithium-ion secondary battery type was manufactured through the following process, and the performance of the negative electrode material, such as discharge capacity, initial efficiency, and rate characteristics, was evaluated.

[0130] O Preparation of slurry;

[0131] For 100 parts by weight of crystalline carbon having deposited carbon formed on the surface, 10 parts by weight of carboxymethyl cellulose (CMC) aqueous solution as a thickener was added in an appropriate amount and stirred and mixed for 30 minutes, and then 10 parts by weight of styrene-butadiene rubber (SBR) aqueous solution as a binder was added in an appropriate amount and stirred and mixed for 5 minutes to produce a negative electrode composite paste.

[0132] Fabrication of O working electrode;

[0133] The obtained negative electrode composite paste was applied onto a copper foil (current collector) having a thickness of 18 μm and heated at 130°C in a vacuum to completely volatilize the solvent. The obtained electrode sheet was rolled with a roller press to have an electrode thickness of approximately 100 μm and a density of approximately 1.5 g / cc, and then punched with a punch to obtain a working electrode.

[0134] O Fabrication of counter electrode;

[0135] In an inert atmosphere, a counter electrode was obtained by punching a lithium metal foil and imprinting it on a nickel mesh (current collector).

[0136] O Fabrication of evaluation batteries;

[0137] Using the above-mentioned working electrode and counter electrode, a coin-type (2023 type) battery was assembled as an evaluation battery under an inert atmosphere. The electrolyte was 1 mol / dm 3 A 1:1 mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) containing lithium salt LiPF6 was used. Charging was performed at a current density of 30 mA / cm. 2 , after constant current charging to a terminal voltage of 0.003 V, the lower limit current is 0.03 mA / cm 2 Maintain the constant potential until the discharge reaches a current density of 350 mA / cm. 2The rate was set to 1C, and after the above charging, constant current discharge was performed up to a potential of 1.5 V at rate rates of 0.2C, 0.5C, 1.0C, 2.0C, and 5.0C for 5 cycles each, and after each 5 cycle of charge / discharge at the above rates, a discharge of 0.2C was performed again to measure the discharge capacity, initial efficiency, and rate characteristics. Here, the rate characteristics were evaluated by dividing the discharge capacity measured at 5.0C by the discharge capacity measured at 0.2C and then converting it to a percentage (%). The results are shown in Tables 19 to 20. Table 19 shows the experimental results evaluating the charge / discharge capacity and initial efficiency among the negative electrode material performance evaluations. Table 20 shows the experimental results evaluating rate characteristics during the performance evaluation of cathode materials, and the rate characteristics are expressed as capacity retention ratio (the discharge capacity measured at 5.0 C divided by the discharge capacity measured at 0.2 C, then converted to a percentage (%)). At this time, a capacity retention ratio of 80% or more was evaluated as a high-rate characteristic.

[0138] Methane pyrolysis time (950℃, 500hr) -1 ) Deposition amount (Coating amount compared to initial catalyst, %) Charge capacity [mAh / g] Discharge capacity [mAh / g] Initial efficiency (1st cycle coulombic efficiency) [%] Comparative example 1-0 398.0 35 1.18 8.2 Example 10-10.1 hours 5405.5 362.78 9.4 Example 10-20.2 hours 10385.4 353.39 1.7 Example 10-30.5 hours 16396.9 355.6 89.6 Example 10-41.5 hours 25395.1 366.99 2.9 Example 10-53.0 hours 35364.23 22.78 8.6 Example 10-65.0 hours 50358.1321.189.7 Example 10-720.0 hours 150312.7269.786.2 Example 10-820.0 hours Deposited sample graphitized 308.2266.486.4

[0139] As shown in Table 19, it can be seen that the negative electrode material for a lithium ion secondary battery of the present invention (crystalline carbon having deposited carbon formed on the surface) has excellent charge / discharge capacity and initial efficiency. In particular, when 5 to 50 parts by weight of deposited carbon is deposited based on 100 parts by weight of crystalline carbon, it can be seen that the initial efficiency increases significantly compared to the case where no deposited carbon exists. In addition, since there is no significant difference when a deposited sample with a methane pyrolysis time of 20 hours is subjected to graphitization treatment (2800℃, 10 minutes of heat treatment) compared to the case where graphitization treatment is not performed, it can be seen that the deposited carbon corresponds to non-graphitizable carbon.

[0140] Methane pyrolysis time (950℃, 500hr) -1 ) Deposition amount (coating amount compared to initial catalyst, %)Current density 0.2CCurrent density 5.0CCapacity retention rate [%]Discharge capacity at 5 cyclesDischarge capacity at 25 cyclesComparative example 1-0360.1227.663.2%Example 10-10.1 hours5369.9299.680.1%Example 10-20.2 hours10359.9296.082.2%Example 10-30.5 hours16361.9307.084.8%Example 10-41.5 hours25360.5317.688.1%Example 10-53.0 hours35330.0315.095.5%Example 10-65.0 hours 50323.7293.290.6% Example 10-720.0 hours 150279.1260.095.1%

[0141] As shown in Table 20, it can be seen that the negative electrode material for a lithium ion secondary battery of the present invention (crystalline carbon having deposited carbon formed on the surface) has excellent rate characteristics. In particular, when 5 to 50 parts by weight of the deposited carbon is deposited based on 100 parts by weight of the crystalline carbon, it can be seen that the rate characteristics, that is, the power characteristics, significantly increase while maintaining the discharge capacity and the initial charge / discharge efficiency compared to the case where the deposited carbon does not exist. In addition, when 5 to 25 parts by weight of the deposited carbon is deposited based on 100 parts by weight of the crystalline carbon, it can be seen that the discharge capacity, the initial charge / discharge efficiency, and the rate characteristics all increase. It can be seen that the case where 5 to 25 parts by weight of the deposited carbon is deposited is particularly effective considering that thermal decomposition occurs over a relatively short period of time.

[0142] Accordingly, it can be seen that the present invention provides a lithium ion secondary battery negative electrode material capable of resource recycling and having excellent rate characteristics, a method for manufacturing the same, a lithium ion secondary battery negative electrode including the same, and a lithium ion secondary battery.

[0143] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical concept or essential features thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

[0144] According to the present invention, a negative electrode material for a lithium-ion secondary battery capable of resource recycling and having excellent rate characteristics, and a negative electrode for a lithium-ion secondary battery or a lithium-ion secondary battery including the same can be provided. Therefore, the present invention has industrial applicability.

Claims

1. A hydrocarbon thermal decomposition catalyst containing crystalline carbon; and It includes deposited carbon formed by vapor deposition of carbon generated by thermal decomposition of hydrocarbon gas on the catalyst surface onto the surface of the crystalline carbon, The above crystalline carbon is a positive catalyst for hydrogen production reaction by hydrocarbon thermal decomposition. A negative electrode material for a lithium ion secondary battery, wherein 5 to 25 parts by weight of the deposited carbon is contained relative to 100 parts by weight of the crystalline carbon.

2. In paragraph 1, The above crystalline carbon has a hydrocarbon conversion rate of 10% or more and a hydrogen selectivity of 20% or more, A negative electrode material for a lithium ion secondary battery, wherein the above hydrocarbon conversion rate and the above hydrogen selectivity are calculated under thermal decomposition conditions including a temperature condition of 900 degrees Celsius or higher.

3. In paragraph 1, The above crystalline carbon is an anode material for lithium-ion secondary batteries having a carbon purity of 95% or higher.

4. In paragraph 1, The above-mentioned deposited carbon is an amorphous carbon negative electrode material for lithium-ion secondary batteries.

5. A lithium-ion secondary battery negative electrode comprising the lithium-ion secondary battery negative electrode material of paragraph 1.

6. A lithium-ion secondary battery comprising the negative electrode for a lithium-ion secondary battery of Article 7. 7.(A) A catalyst preparation step for preparing a hydrocarbon thermal decomposition catalyst containing crystalline carbon; and (B) a deposition carbon formation step of obtaining crystalline carbon formed on the surface by vapor-depositing carbon generated by thermal decomposition of hydrocarbon gas on the catalyst prepared in step (A) onto the surface of the crystalline carbon to form deposition carbon, The above crystalline carbon is a positive catalyst for hydrogen production reaction by hydrocarbon thermal decomposition. A method for manufacturing an anode material for a lithium ion secondary battery, wherein 5 to 25 parts by weight of the deposited carbon is used for 100 parts by weight of the crystalline carbon.

8. In paragraph 7, (C) A method for manufacturing a negative electrode material for a lithium ion secondary battery, further comprising a hydrogen collection step for collecting hydrogen generated by the thermal decomposition in the step (B).

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