Porous carbon and its manufacturing method, silicon carbon negative electrode material, and manufacturing method of silicon carbon negative electrode material

Abstract

The objective of this study is to provide porous carbon suitable for the production of silicon-carbon anode materials. In particular, the objective is to solve the problems of conventional porous carbon, such as a decrease in initial efficiency and deterioration of cycle characteristics due to the excessively large specific surface area, which causes the decomposition reaction of the electrolyte to progress. [Solution] This application provides porous carbon and a manufacturing method thereof, a silicon-carbon anode material, and a manufacturing method of the silicon-carbon anode material. The porous carbon is used in the manufacture of silicon-carbon anode materials. The manufacturing method of the porous carbon includes the steps of: (1) carbonizing a biomass carbon source by heat treatment to obtain a crude porous carbon product (S100); and (2) performing a pore-filling and sealing treatment on the crude porous carbon obtained in S100 by chemical vapor deposition using an organic carbon source to obtain the finished porous carbon product (S200). The biomass carbon source includes coconut shells, straw, rice husks, wood, bamboo, sugarcane pomace, and nut shells. By performing the pore-filling and sealing treatment on the crude porous carbon product, extremely small pores in the porous carbon can be sealed, thereby reducing the specific surface area of ​​the porous carbon.

Description

[Technical Field]

[0001] The present invention relates to the technical field of chemical processes, and in particular to porous carbon and a method for producing the same, a silicon carbon anode material, and a method for producing a silicon carbon anode material. [Background technology]

[0002] Conventional methods for producing porous carbon mainly involve activation and templating. Physical activation involves contacting carbide with gases, such as water vapor, carbon dioxide, or air, at high temperatures to activate and form pores. Chemical activation involves adding chemicals, such as potassium hydroxide, phosphoric acid, or zinc chloride, to the raw material and then heating it in an inert gas atmosphere. Chemical activation requires the use of large amounts of alkaline particles, such as potassium hydroxide or sodium hydroxide. While the resulting porous carbon has a rich pore structure, it requires large amounts of deionized water for washing to neutralize the material before it can be used for practical purposes. Furthermore, magnetic adsorption is required to remove metal ions, which generates large amounts of wastewater during the production process and is prone to environmental pollution.

[0003] While the template method can control the pore structure in an orderly manner, it is expensive to prepare the template and requires etching to remove the resulting porous carbon, making industrialization difficult. Template methods can be divided into hard and soft template methods. In the hard template method, a porous template such as zeolite is first synthesized and used as a hard template. Carbon precursors are then injected into the pores to form nanosized organic / silica composites. The final porous carbon material is then obtained through high-temperature carbonization and template etching. In the soft template method, a surfactant is used as a template, and the interaction between the surfactant and the carbon source results in self-organization to form a porous structure.

[0004] Biomass carbon such as coconut shells and straw, and chemical substances such as phenolic resin are used as raw materials. They are first carbonized in a converter under high-temperature, oxygen-free conditions, and then pores are formed by secondary activation, making it possible to produce porous carbon with a large number of pores and a high specific surface area.

[0005] Porous carbon with a high specific surface area can be used in fields such as supercapacitors and hydrogen storage and adsorption. However, the porous carbon obtained using conventional manufacturing processes contains numerous micropores smaller than 1 nm, which do not contribute to silane vapor deposition. Furthermore, the presence of a large number of micropores smaller than 1 nm results in an excessively high specific surface area, which reduces the initial efficiency when producing silicon-carbon anode materials. Therefore, this type of porous carbon is unsuitable or unusable as a substrate for silane vapor deposition. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem that the present invention aims to solve is how to control the pore size of porous carbon and reduce small diameter micropores. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a method for manufacturing porous carbon, a silicon-carbon anode material, and a method for manufacturing the silicon-carbon anode material.

[0008] The porous carbon is used to manufacture a silicon carbon anode material, and the manufacturing method of the porous carbon includes the following steps: A step S100 of using a biomass carbon source as a raw material and carbonizing the biomass carbon source by heat treatment to produce the crude porous carbon; and step S200 of performing a pore filling and sealing process on the crude porous carbon product produced in step S100 using an organic carbon source by chemical vapor deposition to obtain the porous carbon product.

[0009] In any of the above technical solutions, the biomass carbon source includes at least one or any combination of coconut shell, straw, rice husk, wood, bamboo, sugarcane pomace, and nut shell.

[0010] In any of the above technical solutions, the organic carbon source includes at least one of methane, ethane, propane, acetylene, ethylene, propylene, and toluene, or any combination thereof.

[0011] In any of the above technical solutions, S100: A step S110 of subjecting the biomass carbon source to a primary heat treatment in a protective atmosphere and then cooling it; and a step S120 of subjecting the biomass carbon source to a secondary heat treatment under conditions in which water vapor is introduced into the biomass carbon source, followed by cooling to obtain the porous carbon crude product. Here, the primary heat treatment is carried out to carbonize the biomass carbon source and form pores, and the secondary heat treatment is carried out to enlarge the pores of the biomass carbon source.

[0012] In any of the above technical solutions, the pores of the biomass carbon source are enlarged to 1 to 3 nm by the secondary heat treatment.

[0013] In any of the above technical solutions, the BET specific surface area of ​​the porous carbon crude product is 1800 m 2 ·g -1 For example, 1800 to 2000 m 2 ·g -1 For example, the occupancy rate of mesopores (>2 nm) in the crude porous carbon is 15% or less.

[0014] In any of the above technical solutions, the temperature range of the primary heat treatment is 750°C to 850°C, and the temperature range of the secondary heat treatment is 850°C to 900°C. The temperature range of the primary heat treatment is preferably 770°C to 850°C. The treatment time of the primary heat treatment is preferably 2 to 5 hours, for example 2.5 hours. The treatment time of the secondary heat treatment is preferably 3 to 6 hours, for example 5 hours.

[0015] In any of the above technical solutions, the method further includes, between S110 and S120, a step of washing and drying the biomass carbon source that has undergone the primary heat treatment and cooling.

[0016] In any of the above technical solutions, after S120, the method further includes a step of washing and drying the crude porous carbon product that has undergone the secondary heat treatment and cooling.

[0017] In any of the above technical solutions, the S200: A step S210 of jet-pulverizing the crude porous carbon so that the particle size of the crude porous carbon has a DV50 of 5 μm to 8 μm; and step S220 of feeding the crude porous carbon into a fluidized bed reactor and carrying out chemical vapor deposition using an organic carbon source under pressure conditions of 0.2 MPa to 0.3 MPa and temperature conditions of 700°C to 800°C to obtain the porous carbon product.

[0018] In step S220 of any of the above technical solutions, the temperature condition for the chemical vapor deposition is preferably 720 to 800°C, for example, 740 to 760°C.

[0019] In any of the above technical solutions, the chemical vapor deposition treatment time is 1 to 3 hours under the pressure conditions of 0.2 MPa to 0.3 MPa and the temperature conditions of 700 °C to 800 °C. The specific surface area of ​​the obtained porous carbon product is 1300 to 1700 m 2 ·g -BET1 For example, 1400 to 1600 m 2 ·g-1 For example, the mesopore (>2 nm) occupancy rate in the obtained porous carbon product is 18% or more.

[0020] In any of the above technical solutions, after the pore filling and sealing treatment, the pores of 1 nm or less in the porous carbon product are sealed.

[0021] The present invention provides a porous carbon, which can be obtained by the method described in any of the above technical solutions.

[0022] The present invention also provides a silicon-carbon anode material, which is manufactured using the porous carbon product obtained by any of the above technical solutions.

[0023] The present invention provides a silicon-carbon anode material, which is prepared by silane vapor deposition using porous carbon as raw material, and the porous carbon is obtained by any of the methods described in any of the above technical solutions.

[0024] The present invention provides a method for manufacturing a silicon-carbon anode material, which comprises the following steps: introducing a silicon source gas into the porous carbon product in a flowing state to perform chemical vapor deposition to grow silicon on the porous carbon, and then introducing a carbon source gas to perform chemical vapor deposition to grow carbon on the porous carbon.

[0025] In any of the above technical solutions, when growing silicon on porous carbon by chemical vapor deposition, the temperature is 650-850°C, the pressure of the silicon source gas is 0.1-0.8 MPa, and the treatment time is 3-10 hours, for example, 8 hours.

[0026] In any of the above technical solutions, the temperature when growing carbon on the porous carbon by chemical vapor deposition is 600 to 800°C, the treatment time is 1 to 5 hours, and the pressure when growing carbon on the porous carbon by chemical vapor deposition is 0 to 0.3 MPa.

[0027] In any of the above technical solutions, the silicon source gas is silane gas and / or halosilane gas, the silane gas is monosilane gas and / or disilane gas, and the halosilane gas is chlorosilane gas.

[0028] In any of the above technical solutions, the carbon source gas used in growing carbon on the porous carbon by chemical vapor deposition is one or any combination selected from the group consisting of methane, ethane, propane, acetylene, ethylene, propylene, and toluene. [Effects of the Invention]

[0029] In the present invention, in the manufacturing process of porous carbon, an organic carbon source is used to close the micropores (particularly pores of 1 nm or less) in 1 nm porous carbon by chemical vapor deposition, thereby reducing the specific surface area of ​​the porous carbon (1500 m 2 / g or less). Porous carbon can be used as a raw material for producing silicon-carbon anode materials. Using the silane vapor deposition technique, silicon can be grown on the surface of a porous carbon substrate to produce silicon-carbon anode materials. However, micropores (especially those smaller than 1 nm) do not contribute to silane vapor deposition. Furthermore, the presence of a large number of micropores smaller than 1 nm results in an excessively high specific surface area of ​​the porous carbon, adversely affecting the mechanical properties and mechanical parameters of the silicon-carbon anode material. Therefore, in the porous carbon production process, the porous carbon crude product obtained in step S100 is subjected to a pore filling and sealing treatment, which seals the micropores in the porous carbon, improving the growth efficiency in the chemical vapor deposition production process of silicon-carbon anode materials, saving organic carbon sources, and improving the mechanical properties and mechanical parameters of the silicon-carbon anode material.

[0030] In the present invention, during the production of a silicon-carbon negative electrode material, carbon is grown and coated after silicon growth, thereby effectively preventing direct contact between silicon and the electrolyte in the negative electrode material after completion of the battery, preventing a reaction between the electrolyte and silicon, and effectively improving product performance. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a measurement report of the BET specific surface area of ​​porous carbon that has not been subjected to acetylene treatment in Example 5. [Figure 2] 1 is a measurement report of the BET specific surface area of ​​the porous carbon product prepared in Example 5. [Figure 3] 1 is a graph showing the BET specific surface area of ​​the silicon carbon negative electrode material prepared in Example 11. [Figure 4] 1 is a graph showing the BET specific surface area of ​​the silicon carbon negative electrode material prepared in Example 12. [Figure 5] 1 is a graph showing the BET specific surface area of ​​a silicon carbon negative electrode material produced in Comparative Example 1. [Figure 6] 1 is a graph showing the BET specific surface area of ​​a silicon carbon negative electrode material produced in Comparative Example 2. [Figure 7] 10 is a graph showing the initial charge-discharge curve in the electrochemical property test of the battery using the silicon carbon negative electrode material produced in Example 11. [Figure 8] 10 is a graph showing the initial charge-discharge curve in the electrochemical property test of the battery using the silicon carbon negative electrode material produced in Example 12. [Figure 9] 1 is a graph showing initial charge-discharge curves in an electrochemical property test of a battery using a silicon carbon negative electrode material produced in Comparative Example 1. [Figure 10] 1 is a graph showing initial charge-discharge curves in an electrochemical property test of a battery using a silicon carbon negative electrode material produced in Comparative Example 2. [Figure 11]10 is a test curve of the capacity retention rate of a battery using the silicon carbon negative electrode material prepared in Example 11. [Figure 12] 1 is a test curve of the capacity retention rate of a battery using the silicon carbon negative electrode material produced in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0032] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be described in more detail below with reference to specific embodiments. It should be noted that, to the extent that no contradiction occurs, the examples of the present application and the features in the examples can be implemented in combination with each other.

[0033] In the following description, many specific details are set forth to allow a thorough understanding of the present invention, but the present invention may be embodied in other forms different from those described herein, and the scope of protection of the present invention is not limited to the specific embodiments disclosed below. The following technical features of the embodiments of the present invention may be combined with each other, provided that no contradiction arises.

[0034] The present invention provides a method for producing porous carbon, which is used for producing a silicon-carbon anode material, and the method for producing the porous carbon includes: A step S100 of using a biomass carbon source as a raw material and carbonizing the biomass carbon source by heat treatment to produce the crude porous carbon; and step S200 of performing a pore filling and sealing process on the crude porous carbon product produced in step S100 using an organic carbon source by chemical vapor deposition to obtain the porous carbon product.

[0035] In the above embodiment, the biomass carbon source has the advantage of being low cost and easily available, and the use of the biomass carbon source to produce porous carbon can provide environmentally friendly and advantageous effects.

[0036] In some embodiments of the present invention, the biomass carbon source comprises at least one or any combination of coconut shells, straw, rice husks, wood, bamboo, sugarcane pomace, and nut shells.

[0037] As will be appreciated, the heat treatment carbonizes the biomass carbon source.

[0038] In some embodiments of the present invention, the temperature range of the heat treatment is 700°C to 900°C.

[0039] In some embodiments of the present invention, the temperature range of the heat treatment is preferably 750°C to 850°C.

[0040] In some embodiments of the present invention, more preferably, the temperature range of the heat treatment is 800°C.

[0041] As will be appreciated, the heat treatment may include only a primary heat treatment, or may include secondary or further heat treatments.

[0042] In some embodiments of the present invention, S100 comprises: A step S110 of subjecting the biomass carbon source to a primary heat treatment in a protective atmosphere and then cooling it; and a step S120 of subjecting the biomass carbon source to a secondary heat treatment under conditions in which water vapor is introduced into the biomass carbon source, followed by cooling to obtain the porous carbon crude product. Here, the primary heat treatment is carried out to carbonize the biomass carbon source and form pores, and the secondary heat treatment is carried out to enlarge the pores of the biomass carbon source.

[0043] Illustratively, in some embodiments of the present invention, after the first heat treatment, the pores of the biomass carbon source are 1 nm to 3 nm, and after the second heat treatment, the pores of the porous carbon crude product are less than 5 nm.

[0044] In some embodiments of the present invention, the temperature range of the first heat treatment is 750°C to 850°C, and the temperature range of the second heat treatment is 850°C to 900°C.

[0045] In some embodiments of the present invention, the temperature range of the first heat treatment is preferably 780°C to 820°C, and the temperature range of the second heat treatment is preferably 870°C to 890°C.

[0046] In some embodiments of the present invention, more preferably, the temperature range of the first heat treatment is 800°C and the temperature range of the second heat treatment is 880°C.

[0047] In some embodiments of the present invention, the method further includes, between S110 and S120, washing and drying the biomass carbon source that has undergone the primary heat treatment and cooling.

[0048] After the primary heat treatment, the carbide not only contains many microporous structures but also a large amount of ash and metal impurities, so washing and drying are required to remove the ash and metal impurities.

[0049] In some embodiments of the present invention, after S120, the method further comprises washing and drying the crude porous carbon product that has undergone the secondary heat treatment and cooling.

[0050] After the secondary heat treatment, the porous carbon at this point must be washed and dried to remove impurities generated during chemical vapor deposition growth, making it easier for subsequent processing.

[0051] As will be understood, chemical vapor deposition using an organic carbon source is performed to fill and seal the pores of the porous carbon crude product obtained in S100.

[0052] In some embodiments of the present invention, the organic carbon source comprises at least one or any combination of methane, ethane, propane, acetylene, ethylene, propylene, and toluene.

[0053] In the porous carbon production process, the crude porous carbon obtained in step S100 is subjected to a pore filling and sealing treatment, which can seal the micropores in the porous carbon, thereby increasing the growth efficiency in the chemical vapor deposition production process of silicon-carbon anode materials, saving organic carbon sources, and improving the mechanical properties and dynamic parameters of the silicon-carbon anode materials.

[0054] In some embodiments of the present invention, S200 includes: A step S210 of jet-pulverizing the crude porous carbon so that the particle size of the crude porous carbon has a DV50 of 5 μm to 8 μm; and step S220 of feeding the crude porous carbon into a fluidized bed reactor and carrying out chemical vapor deposition using an organic carbon source under pressure conditions of 0.2 MPa to 0.3 MPa and temperature conditions of 700°C to 800°C to obtain the porous carbon product.

[0055] In some embodiments of the present invention, after undergoing the pore filling and sealing treatment, pores of 1 nm or less in the porous carbon product are sealed.

[0056] Example 1 As an example of the present invention, porous carbon was produced using the following manufacturing method. Coconut shells were used as the raw material for the porous carbon. They were heated to 750-850°C in a converter under a nitrogen atmosphere and carbonized. At this stage, the carbonized material contained numerous micropores and significant amounts of ash and metal impurities. After ultrasonic cleaning and drying, the material was returned to the converter, where water vapor was introduced at 850-900°C for secondary activation to form micropores, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 5-8 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor. Acetylene was introduced under conditions of a reaction pressure of 0.2-0.3 MPa and a reaction temperature of 700-800°C to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the porous carbon after pulverization had a BET specific surface area of ​​approximately 1820 m before the acetylene treatment. 2 ·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1450 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 11.6% before treatment to 18.8% after treatment, indicating a significant decrease in micropores.

[0057] Example 2 As an example of the present invention, porous carbon was produced using the following manufacturing method. Straw was used as the raw material for the porous carbon, and carbonization was performed by heating it to 750-800°C in a converter under a nitrogen atmosphere. After ultrasonic cleaning and drying, the porous carbon was returned to the converter, and water vapor was introduced at 850-880°C to form secondary pores, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, and methane was introduced under conditions of a reaction pressure of 0.2-0.3 MPa and a reaction temperature of 740-800°C to cause decomposition, packing, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1810 m before methane treatment. 2 ·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1433 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 13.3% before treatment to 19.1% after treatment, indicating a significant decrease in micropores.

[0058] Example 3 As an example of the present invention, porous carbon was produced using the following manufacturing method. Nut shells were used as the raw material for the porous carbon. They were heated to 780-800°C in a converter under an argon atmosphere for carbonization. After ultrasonic cleaning and drying, the porous carbon was returned to the converter, and water vapor was introduced at 880-900°C for secondary activation to form pores, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, where ethane was introduced under conditions of a reaction pressure of 0.2-0.3 MPa and a reaction temperature of 740-760°C to cause decomposition, packing, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1878 m2·g before ethane treatment. -1 The BET specific surface area of ​​the treated porous carbon product was approximately 1492 m g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 11.3% before treatment to 19.2% after treatment, indicating a significant decrease in micropores.

[0059] Example 4 As an example of the present invention, porous carbon was produced using the following manufacturing method. Rice husks were used as the raw material for the porous carbon. They were heated to 780-800°C in a converter under an argon atmosphere for carbonization. After ultrasonic cleaning and drying, the porous carbon was returned to the converter, and water vapor was introduced at 880-900°C for secondary activation to form pores, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, where propane was introduced under conditions of a reaction pressure of 0.2-0.3 MPa and a reaction temperature of 740-760°C to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1954 m before the propane treatment. 2 ·g-1 The BET specific surface area of ​​the treated porous carbon product is approximately 155 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 13.1% before treatment to 19.6% after treatment, indicating a significant decrease in micropores.

[0060] Example 5 The method for producing porous carbon in this embodiment includes the following steps: Coconut shells are used as the raw material for porous carbon. They are heated to 800°C in a nitrogen atmosphere in a converter for 2.5 hours and carbonized. At this stage, the carbonized material contains numerous micropores and also contains significant amounts of ash and metal impurities. After ultrasonic cleaning and drying, the carbonized material is returned to the converter and subjected to secondary activation by introducing steam at 880°C to form micropores. This secondary activation is then performed at 880°C for 5 hours, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon is jet-pulverized to adjust the particle size (DV50) to the range of 5-8 μm. The ground porous carbon is then placed in a fluidized-bed reactor. Acetylene is introduced for 1 hour under conditions of 0.2 MPa reaction pressure and 750°C reaction temperature to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction is complete, the product is collected and packaged. In this example, the porous carbon after pulverization had a BET specific surface area of ​​approximately 1820 m before the acetylene treatment. 2 ·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1450 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and found to be approximately 11.6% before treatment, increasing to 18.8% after treatment, indicating a significant decrease in micropores. The BET specific surface area measurements of the porous carbon before and after treatment are shown in Figures 1 and 2, respectively.

[0061] Example 6 The method for producing porous carbon in this embodiment includes the following steps: Straw was used as the raw material for porous carbon, and it was heated to 770°C in a nitrogen atmosphere in a converter and carbonized for 5 hours. After ultrasonic cleaning and drying, the carbonized material was returned to the converter, where water vapor was introduced at 870°C for secondary activation to form pores. This secondary activation was continued at 870°C for 3 hours, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, where methane was introduced for 3 hours under conditions of a reaction pressure of 0.3 MPa and a reaction temperature of 740°C to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1810 m before methane treatment. 2 ·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1433 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 13.3% before treatment to 19.1% after treatment, indicating a significant decrease in micropores.

[0062] Example 7 The method for producing porous carbon in this embodiment includes the following steps: Nut shells are used as the raw material for porous carbon. They are heated to 780°C in a converter under an argon atmosphere and carbonized for four hours. After ultrasonic cleaning and drying, the carbonized material is returned to the converter and subjected to secondary activation by introducing steam at 880°C to form micropores. This is followed by secondary activation at 880°C to 900°C for five hours, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon is jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The ground porous carbon is then placed in a fluidized-bed reactor. Ethane is introduced for two hours under conditions of 0.2 MPa reaction pressure and 740°C reaction temperature to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction is complete, the product is collected and packaged. In this example, the BET specific surface area of ​​the ground porous carbon before ethane treatment was approximately 1878 m2·g-1, and the BET specific surface area of ​​the treated porous carbon product was approximately 1492 m2·g-1. The mesopore (>2 nm) fraction was calculated and found to increase from approximately 11.3% before treatment to 19.2% after treatment, indicating a significant reduction in micropores.

[0063] Example 8 The method for producing porous carbon in this embodiment includes the following steps: Rice husks were used as the raw material for porous carbon, and they were heated to 800°C in an argon atmosphere in a converter and carbonized for two hours. After ultrasonic cleaning and drying, the carbonized material was returned to the converter, where water vapor was introduced at 900°C for secondary activation to form pores. This was followed by secondary activation at 900°C for three hours, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 6-7 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, where propane was introduced for two hours under conditions of a reaction pressure of 0.3 MPa and a reaction temperature of 740°C to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1954 m before propane treatment. 2 ·g -1The BET specific surface area of ​​the treated porous carbon product is approximately 1558 m 2 ·g -1 The proportion of mesopores (greater than 2 nm) was calculated, and it increased from about 13.1% before treatment to 19.6% after treatment, indicating a significant decrease in micropores.

[0064] Example 9 The method for producing porous carbon in this embodiment includes the following steps: Porous carbon was produced using coconut shells as raw materials and carbonized in a converter under a nitrogen atmosphere at 850°C for two hours. After ultrasonic cleaning and drying, the carbonized material was returned to the converter and subjected to secondary activation by introducing steam at 850°C to form pores. This secondary activation was continued at 850°C for three hours, enlarging some of the pores to 1-3 nm. After ultrasonic cleaning and drying, the activated porous carbon was jet-pulverized to adjust the particle size (DV50) to a range of 5-8 μm. The pulverized porous carbon was then placed in a fluidized-bed reactor, where acetylene was introduced for three hours under conditions of a reaction pressure of 0.25 MPa and a reaction temperature of 720°C to cause decomposition, filling, and growth, filling and sealing micropores less than 1 nm in size. After the reaction was completed, the product was collected and packaged. In this example, the pulverized porous carbon had a BET specific surface area of ​​approximately 1982 m before propane treatment. 2 ·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1534 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 12.8% before treatment to 19.8% after treatment, indicating a significant decrease in micropores.

[0065] Example 10 The porous carbon manufacturing method in this example differs from the porous carbon manufacturing method in Example 9 in only one respect: in this example, after the pulverized porous carbon is introduced into a fluidized bed reactor, acetylene is introduced and the reaction temperature is controlled to 800°C. In this example, the pulverized porous carbon has a BET specific surface area of ​​approximately 1982 m before the acetylene treatment. 2·g -1 The BET specific surface area of ​​the treated porous carbon product is approximately 1498 m 2 ·g -1 The proportion of mesopores (>2 nm) was calculated and increased from approximately 12.8% before treatment to 20.7% after treatment, indicating a significant decrease in micropores.

[0066] Example 11 The silicon carbon anode material of this example is manufactured by the following steps using the porous carbon product obtained in Example 5 as a raw material.

[0067] The porous carbon product is placed in a fluidized bed reactor, and nitrogen is introduced to keep the porous carbon fluidized. The temperature is controlled at 800°C. The monosilane gas pressure is set to 0.5 MPa, and monosilane gas is introduced to perform chemical vapor deposition. During this process, the monosilane and porous carbon are thoroughly mixed, and the resulting silicon grows and deposits within the pores of the porous carbon. After 5 hours of silicon growth, acetylene gas is introduced under conditions of 700°C and 0.1 MPa, and carbon is grown by chemical vapor deposition, forming a coating on the porous carbon. The coating time is set to 1 hour, resulting in the production of a silicon-carbon anode material.

[0068] Example 12 The silicon carbon anode material of this example is manufactured by the following steps using the porous carbon product obtained in Example 5 as a raw material.

[0069] The porous carbon product is placed in a fluidized bed reactor, and nitrogen is introduced to keep the porous carbon fluidized. The temperature is controlled at 850°C. The monosilane gas pressure is set to 0.8 MPa, and monosilane gas is introduced to perform chemical vapor deposition. During this process, the monosilane and porous carbon are thoroughly mixed, and the resulting silicon grows and deposits within the pores of the porous carbon. After three hours of silicon growth, acetylene gas is introduced under conditions of 800°C and 0.3 MPa, and carbon is grown by chemical vapor deposition, forming a coating on the porous carbon. The coating time is three hours, resulting in the production of a silicon-carbon anode material.

[0070] Example 13 The silicon carbon anode material of this example is manufactured by the following steps using the porous carbon product obtained in Example 5 as a raw material.

[0071] The porous carbon product is placed in a fluidized bed reactor, and nitrogen is introduced to keep the porous carbon fluidized, with the temperature controlled at 650°C. The monosilane gas pressure is set to 0.1 MPa, and monosilane gas is introduced to perform chemical vapor deposition. During this process, the monosilane and porous carbon are thoroughly mixed, and the resulting silicon grows and deposits within the pores of the porous carbon. After 10 hours of silicon growth, acetylene gas is introduced at 700°C and atmospheric pressure to grow carbon by chemical vapor deposition, forming a coating on the porous carbon. The coating time is 5 hours, resulting in the production of a silicon-carbon anode material.

[0072] Example 14 The silicon carbon anode material of this example is manufactured by the following steps using the porous carbon product obtained in Example 8 as a raw material.

[0073] The porous carbon product is placed in a fluidized bed reactor, and nitrogen is introduced to keep the porous carbon fluidized. The temperature is controlled at 700°C. The monosilane gas pressure is set to 0.3 MPa, and monosilane gas is introduced to perform chemical vapor deposition. During this process, the monosilane and porous carbon are thoroughly mixed, and the resulting silicon grows and deposits within the pores of the porous carbon. After six hours of silicon growth, acetylene gas is introduced under conditions of 600°C and 0.1 MPa, and carbon is grown by chemical vapor deposition, forming a coating on the porous carbon. The coating time is five hours, resulting in the production of a silicon-carbon anode material.

[0074] Example 15 The silicon carbon anode material of this example is manufactured by the following steps using the porous carbon product obtained in Example 5 as a raw material.

[0075] The porous carbon product is placed in a fluidized bed reactor, and nitrogen is introduced to keep the porous carbon fluidized. The temperature is controlled at 750°C. The monosilane gas pressure is set to 0.4 MPa, and monosilane gas is introduced to perform chemical vapor deposition. During this process, the monosilane and porous carbon are thoroughly mixed, and the resulting silicon grows and deposits within the pores of the porous carbon. After four hours of silicon growth, acetylene gas is introduced under conditions of 750°C and 0.1 MPa, and carbon is grown by chemical vapor deposition, forming a coating on the porous carbon. The coating time is two hours, resulting in the production of a silicon-carbon anode material.

[0076] Example 16 The method for manufacturing a silicon-carbon anode material in this example differs from the method for manufacturing a silicon-carbon anode material in Example 15 in only one respect: in this example, the porous carbon used is the porous carbon product manufactured in Example 10.

[0077] Comparative Example 1 The method for producing a silicon carbon negative electrode material in this comparative example differs from the method for producing a silicon carbon negative electrode material in Example 10 in only one respect: in this comparative example, the porous carbon pulverized in Example 5 (i.e., porous carbon that has not been subjected to a pore-sealing treatment) is used as the raw material.

[0078] Comparative Example 2 The method for producing a silicon carbon negative electrode material in this comparative example differs from the method for producing a silicon carbon negative electrode material in Example 11 in only one respect: in this comparative example, the porous carbon pulverized in Example 6 (i.e., porous carbon that has not been subjected to pore sealing treatment) is used as the raw material.

[0079] Comparative Example 3 The method for producing a silicon carbon negative electrode material in this comparative example differs from the method for producing a silicon carbon negative electrode material in Example 12 in only one respect: in this comparative example, the porous carbon pulverized in Example 7 (i.e., porous carbon that has not been subjected to pore sealing treatment) is used as the raw material.

[0080] Comparative Example 4 The method for producing a silicon carbon negative electrode material in this comparative example differs from the method for producing a silicon carbon negative electrode material in Example 13 in only one respect: in this comparative example, the porous carbon pulverized in Example 8 (i.e., porous carbon that has not been subjected to a pore-sealing treatment) is used as the raw material.

[0081] Comparative Example 5 The method for producing a silicon carbon negative electrode material in this comparative example differs from the method for producing a silicon carbon negative electrode material in Example 14 in only one respect: in this comparative example, the porous carbon pulverized in Example 9 (i.e., porous carbon that has not been subjected to a pore-sealing treatment) is used as the raw material.

[0082] Comparative Example 6 The method for producing a silicon carbon anode material in this comparative example differs from the method for producing a silicon carbon anode material in Comparative Example 1 in only one respect: in this comparative example, the material is removed when the silicon growth is completed, and is used as the silicon carbon anode material as is.

[0083] Experimental example 1) BET specific surface area measurement The BET specific surface area of ​​each of the silicon carbon negative electrode materials obtained in Examples 11 to 16 and Comparative Examples 1 to 6 was measured. The measurement results are shown in Table 1. Graphs of the BET specific surface area of ​​the silicon carbon negative electrode materials of Examples 11 to 16 and Comparative Examples 1 and 2 are shown in Figures 3 to 6.

[0084] Table 1 BET specific surface area of ​​porous carbon before and after carbon source gas treatment JPEG2025537581000002.jpg112131

[0085] As is clear from the data in Table 1, in Examples 11 to 16, the porous carbon was treated with an organic carbon source gas before being used to produce a silicon carbon anode material, and the BET specific surface area was clearly lower than that of Comparative Examples 1 to 6. This indicates that the pores of the porous carbon were blocked.

[0086] 2) Electrochemical property test The silicon-carbon anode materials obtained in Examples 11-16 and Comparative Examples 1-6 were used as the anode material, lithium foil as the counter electrode, and LiPF6 (concentration in the electrolyte: 1 mol / L) as the electrolyte salt. Anode electrode sheets were fabricated in a ratio of silicon-carbon anode material: CMC / SBR: conductive agent = 80:10:10, and coin-type batteries were fabricated using the same manufacturing process. The resulting coin-type batteries were evaluated for initial discharge specific capacity and initial coulombic efficiency (voltage range: 0-2.0 V, charge / discharge rate: 0.1 C / 0.1 C). The silicon-carbon anode materials obtained in Examples 11-16 and Comparative Examples 1-6 were composited with graphite to form a 500 mAh / g anode material. A full battery was fabricated using LiPF6 (concentration in the electrolyte solution: 1 mol / L) as the electrolyte salt and a ternary material as the positive electrode material, and a cycle performance test was conducted for 300 cycles at 2.75 to 4.2 V, room temperature, and 1C / 1C. The results are shown in Table 2. Initial charge / discharge curves in electrochemical property tests for coin-type batteries using the silicon-carbon negative electrode materials obtained in Examples 11 to 16 and Comparative Examples 1 and 2 are shown in Figures 7 to 10. Capacity retention test curves for full batteries using the silicon-carbon negative electrode materials obtained in Example 11 and Comparative Example 1 are shown in Figures 11 and 12.

[0087] Table 2 Coin cell battery performance test results JPEG2025537581000003.jpg128130

[0088] The data in Table 2 reveal the following: There is no significant change in the capacity of the silicon-carbon anode material prepared before and after treating the porous carbon with an organic carbon source gas, and no capacity loss is observed, but the initial coulombic efficiency is significantly improved. Regarding cycling performance, the coin-type battery with the silicon-carbon anode material prepared using porous carbon not treated with an organic carbon source gas retains approximately 82% of its capacity after 300 cycles, whereas the coin-type battery with the silicon-carbon anode material prepared using porous carbon treated with an organic carbon source gas retains approximately 91% of its capacity after 300 cycles. Therefore, the coin-type battery with the silicon-carbon anode material prepared using porous carbon treated with an organic carbon source gas exhibits significant improvements in both initial coulombic efficiency and cycling performance.

[0089] In the present invention, terms such as "first," "second," and "third" are used merely for convenience of description and do not imply or limit relative importance. Furthermore, the term "plurality" means two or more unless otherwise specified. Terms such as "attach," "connect," "couple," and "fix" should be interpreted broadly. For example, "connect" may mean a fixed connection, a detachable connection, or an integral connection. "Coupling" may mean a direct connection or an indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0090] In this specification, the terms "one embodiment," "several embodiments," "particular embodiment," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. The descriptive descriptions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the described particular feature, structure, material, or characteristic may be used in any suitable combination in any one or more embodiments or examples. The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art may make various modifications and variations to the present invention. All modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for producing porous carbon, the porous carbon being used for producing a silicon carbon negative electrode material, the method for producing the porous carbon includes: a step S100 of using a biomass carbon source as a raw material and carbonizing the biomass carbon source by heat treatment to produce the porous carbon crude product; and a step S200 of performing a pore filling and sealing treatment on the crude porous carbon produced in S100 by chemical vapor deposition using an organic carbon source to obtain the porous carbon product. A method for producing porous carbon.

2. The biomass carbon source includes at least one or any combination of coconut shells, straw, rice husks, wood, bamboo, sugarcane pomace, and nut shells; The organic carbon source comprises at least one of methane, ethane, propane, acetylene, ethylene, propylene, and toluene, or any combination thereof; 2. The method for producing porous carbon according to claim 1.

3. S100 includes a step S110 of subjecting the biomass carbon source to a primary heat treatment in a protective atmosphere and then cooling the biomass carbon source; and a step S120 of subjecting the biomass carbon source to a secondary heat treatment under conditions in which water vapor is introduced into the biomass carbon source, followed by cooling to obtain the porous carbon crude product. wherein the primary heat treatment is carried out to carbonize the biomass carbon source and form pores, and the secondary heat treatment is carried out to enlarge the pores of the biomass carbon source.

3. The method for producing porous carbon according to claim 1, wherein the porous carbon is a carbon material.

4. The secondary heat treatment enlarges the pores of the biomass carbon source to 1 to 3 nm.

4. The method for producing porous carbon according to claim 3.

5. The temperature range of the first heat treatment is 750°C to 850°C, and the temperature range of the second heat treatment is 850°C to 900°C.

4. The method for producing porous carbon according to claim 3.

6. The treatment time of the primary heat treatment is 2 to 5 hours, and the treatment time of the secondary heat treatment is 3 to 6 hours.

4. The method for producing porous carbon according to claim 3.

7. Between S110 and S120, the method further includes a step of washing and drying the biomass carbon source that has undergone the primary heat treatment and cooling, After S120, the method further includes a step of washing and drying the crude porous carbon product that has undergone the secondary heat treatment and cooling.

4. The method for producing porous carbon according to claim 3.

8. S200 includes a step S210 of jet-pulverizing the crude porous carbon so that the particle size of the crude porous carbon has a DV50 of 5 μm to 8 μm; and a step S220 of feeding the crude porous carbon into a fluidized bed reactor and performing chemical vapor deposition using an organic carbon source under a pressure condition of 0.2 MPa to 0.3 MPa and a temperature condition of 700°C to 800°C to obtain the porous carbon product.

3. The method for producing porous carbon according to claim 1, wherein the porous carbon is a carbon material.

9. After the pore filling and sealing treatment, pores of 1 nm or less in the porous carbon product are sealed.

9. The method for producing porous carbon according to claim 8.

10. The chemical vapor deposition treatment time is 1 to 3 hours under a pressure condition of 0.2 MPa to 0.3 MPa and a temperature condition of 700°C to 800°C.

9. The method for producing porous carbon according to claim 8.

11. A porous carbon, the porous carbon being obtained by the method according to any one of claims 1 to 10. The porous carbon is characterized by:

12. A silicon carbon negative electrode material, the silicon carbon negative electrode material being produced by silane vapor deposition using porous carbon as a raw material, the porous carbon being obtained by the method according to any one of claims 1 to 10. A silicon carbon anode material characterized by:

13. A silicon carbon negative electrode material, which is composed of porous carbon manufactured by the manufacturing method according to any one of claims 1 to 10. A silicon carbon anode material characterized by:

14. 14. A method for producing a silicon-carbon negative electrode material according to claim 13, comprising the steps of: introducing a silicon source gas into porous carbon under a flowing state to perform chemical vapor deposition to grow silicon on the porous carbon; and then introducing a carbon source gas to perform chemical vapor deposition to grow carbon on the porous carbon. The method for producing a silicon-carbon anode material according to claim 13.

15. The temperature when growing silicon on the porous carbon by chemical vapor deposition is 650 to 850°C, the pressure of the silicon source gas is 0.1 to 0.8 MPa, and the treatment time is 3 to 10 hours. The method for producing a silicon-carbon anode material according to claim 14.

16. The temperature when growing carbon on the porous carbon by chemical vapor deposition is 600 to 800°C, and the treatment time is 1 to 5 hours. The method for producing a silicon-carbon anode material according to claim 14 or 15.

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