Method for producing porous carbon support and porous carbon support produced thereby

Abstract

The present invention can provide a method for producing a porous carbon support, which includes: (1) a step of synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) a step of solidifying the pitch to obtain solid pitch; and (3) a step of producing a carbon support from the solid pitch, wherein the pitch in the step (1) satisfies the following relational expression 1: [Equation 1] S / S P ×100+MP≦0.5 In the above Relational Formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results for the synthesized pitch, and S P is the softening point of the pitch and MP is the volume fraction of the mesophase content in the synthesized pitch.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a porous carbon support and a porous carbon support produced thereby. [Background technology]

[0002] Carbon materials are made from carbon, one of the most common resources on Earth. They are extremely light, strong, and have excellent electrical and thermal conductivity, making them a core material widely used in fields such as hydrogen vehicles, aviation, secondary batteries, and luxury consumer goods.

[0003] Carbon materials can be produced from various raw materials such as coconut shells, polyacrylonitrile, rayon, and pitch, but among them, carbon materials produced from solid raw materials such as coconut shells have difficulty in controlling their molecular weight and components (Korean Patent Publication No. 10-2019-0093960).

[0004] Meanwhile, pitch, a viscoelastic solid polymer extracted from crude oil or plants, has advantages over other raw materials in that it has a high yield when converted into carbon materials, is inexpensive, and has a molecular structure closer to that of graphite than other raw materials, reducing the energy required for heat treatment (U.S. Patent Nos. 4,242,196 and 4,340,464).

[0005] In particular, pyrolysis fuel oil (PFO), naphtha cracking bottom oil (NCB), vacuum residue (VR), and fluid catalytic cracking decant oil (FCC-DO), which are obtained as by-products in the petroleum refining process, have high aromatic compound contents and low impurity contents such as sulfur and nitrogen, and therefore the pitch produced from these products is attracting attention as a source of carbon materials. Summary of the Invention [Problem to be solved by the invention]

[0006] One of the various objects of the present invention is to provide a method for producing a porous carbon support having controlled pore characteristics and capable of being deposited sufficiently deep into pores during chemical vapor deposition, and a porous carbon support produced thereby.

[0007] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having a high charge / discharge capacity, and a porous carbon support produced thereby.

[0008] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having improved cycle characteristics, and a porous carbon support produced thereby.

[0009] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having excellent mechanical properties, and a porous carbon support produced thereby. [Means for solving the problem]

[0010] According to one embodiment of the present invention, the present invention can provide a method for producing a porous carbon support, comprising: (1) synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) solidifying the pitch to obtain a solid pitch; and (3) producing a carbon support from the solid pitch, wherein the pitch in step (1) satisfies the following relational expression 1:

[0011] [Equation 1]

[0012] S / S P ×100+MP≦0.5

[0013] In the above Relational Formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results for the synthesized pitch, and S P is the softening point of the pitch and MP is the volume fraction of the mesophase content in the synthesized pitch.

[0014] In this case, the polycondensation temperature of the pitch synthesis in step (1) may be in the range of 300°C or more and / or 450°C or less.

[0015] In one embodiment of the present invention, the softening point of the pitch synthesized in step (1) of the method for preparing a porous carbon support according to the present invention may be 200° C. or higher.

[0016] In one example, the proportion of saturated hydrocarbons in the pitch synthesized in step (1) of the method for producing a porous carbon support according to the present invention may be 0.6 mass % or less.

[0017] In another example, the asphaltene content of the pitch synthesized in step (1) of the method for producing a porous carbon support according to the present invention may be 30 mass % or less.

[0018] The step (3) of producing a carbon support may include steps of stabilizing, carbonizing, and activating the solid pitch.

[0019] In one example, the method for producing a porous carbon support according to the present invention may further include a step of depositing silicon on the porous carbon support.

[0020] In this case, the deposition may be performed at a temperature of 300° C. or more and / or 600° C. or less under a silane (SiH 4 ) gas atmosphere of 50 sccm or more and / or 500 sccm or less.

[0021] In this case, the content of silicon may be 10% by weight or more based on the weight of the entire support.

[0022] An embodiment of the present invention may provide a porous carbon support manufactured by the above-described method for manufacturing a porous carbon support.

[0023] An embodiment of the present invention may provide a battery anode material including the porous carbon support described above. [Effects of the Invention]

[0024] One of the various effects of the present invention is that mesopores are formed at the outer edge and deep inside. It is possible to provide a method for producing a porous carbon support in which micropores are formed in the porous carbon support and silicon can be sufficiently deposited even in deep pores, and a porous carbon support produced thereby.

[0025] One of the various effects of the present invention is that it provides a method for producing a porous carbon support that can produce a negative electrode material having a high charge / discharge capacity, and a porous carbon support produced thereby.

[0026] One of the various effects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having improved cycle characteristics, and a porous carbon support produced thereby.

[0027] One of the various effects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having excellent mechanical properties, and a porous carbon support produced thereby.

[0028] However, the various beneficial advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention. [Brief explanation of the drawings]

[0029] [Figure 1]FIG. 1 is a graph showing the results of SARA analysis of the porous carbon supports prepared in the Examples and Comparative Examples. [Figure 2] FIG. 2 is an SEM image of the carbon-silicon composite particles produced in Experimental Example 1. [Figure 3] FIG. 3 is an SEM image of the carbon-silicon composite particles produced in Experimental Example 2. [Figure 4] FIG. 4 is a graph showing the results of electrochemical evaluation of half coin cells fabricated using the porous carbon supports of Experimental Examples 1 and 3. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and the accompanying drawings. This is not intended to limit the technology described in this specification to the specific embodiments, but should be understood as including various modifications, equivalents, and / or alternatives of the embodiment examples of the present invention. In describing the drawings, similar reference numerals may be used for similar components.

[0031] In addition, in the drawings, in order to clearly explain the present invention, parts that are not relevant to the explanation are omitted, and thicknesses are exaggerated to clearly represent multiple layers and regions, and components that have the same function within the same conceptual scope may be described using the same reference symbols.

[0032] In this specification, the terms "have," "may have," "include," or "may include" refer to the presence of a given feature (e.g., a value, function, operation, or component such as a part) and do not exclude the presence of additional features.

[0033] As used herein, phrases such as "A or B," "at least one of A or / and B," and "one or more of A or / and B" may include all possible combinations of the listed items. For example, "A or B," "at least one of A and B," or "at least one of A or B" may mean (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. It can refer to all cases where both contain at least one B.

[0034] All numbers and expressions expressing quantities of components, reaction conditions, and the like described herein, unless stated to the contrary, should be understood as being modified in all instances by the term "about."

[0035] The present invention relates to a method for producing a porous carbon support. The method for producing a porous carbon support according to one embodiment of the present invention may include the steps of (1) synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material, (2) solidifying the pitch to obtain solid pitch, and (3) producing a carbon support from the solid pitch.

[0036] In this case, the pitch in step (1) may satisfy the following relational expression 1.

[0037] [Equation 1]

[0038] S / S P ×100+MP≦0.5

[0039] In the above Relational Formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results for the synthesized pitch, and S P is the softening point of the pitch and MP is the volume fraction of the mesophase content in the synthesized pitch.

[0040] Each step of the present invention will now be described in detail.

[0041] Stage (1)

[0042] In the above step (1), a petroleum-based raw material is pyrolyzed and polycondensed to synthesize pitch.

[0043] In an embodiment of the present invention, the petroleum-based feedstock may comprise at least one selected from the group consisting of thermal cracking fuel oil (PFO), naphtha cracked bottom oil (NCB), ethylene cracker bottom oil (EBO), vacuum residue (VR), deasphalted oil (DAO), atmospheric residue (AR), fluid catalytic cracking decant oil (RFCC-DO), residue fluid catalytic cracking decant oil (RFCC-DO), and heavy aromatic oil. In a preferred embodiment of the present invention, the petroleum-based feedstock may comprise thermal cracking fuel oil.

[0044] In a specific example of the present invention, the pyrolysis and polycondensation of the petroleum-based feedstock may be carried out at a temperature of 300°C or higher and / or 450°C or lower. The pyrolysis and polycondensation temperature may be 300°C or higher, 310°C or higher, 320°C or higher, 330°C or higher, 340°C or higher, or 350°C or higher, and 450°C or lower, 440°C or lower, 430°C or lower, or 420°C or lower, but is not limited thereto. When the pyrolysis and polycondensation temperature is within the above range, a pitch containing a large amount of relatively low molecular weight components can be produced. Furthermore, during the activation process described below, the relatively low molecular weight components are vaporized first, thereby allowing sufficient formation of mesopores in the carbon support. If the pyrolysis and polycondensation temperature of the petroleum-based feedstock is too low, it may be difficult to produce a solid pitch at room temperature. If the temperature is too high, the pitch may contain a large amount of relatively high molecular weight components, making it impossible to produce a carbon support with mesopores.

[0045] In an embodiment of the present invention, the pyrolysis and polycondensation of the petroleum-based feedstock may be carried out in an atmosphere of an oxidizing gas, an inert gas, or a mixture thereof. In a preferred embodiment of the present invention, the oxidizing gas may be oxygen, ozone, or a combination thereof, the inert gas may be nitrogen, helium, neon, argon, or a combination thereof, and the mixture may be air, but is not limited thereto.

[0046] In an embodiment of the present invention, the gas may be supplied at a flow rate of 10 to 800 ml / min during the thermal decomposition and polycondensation of a petroleum-based feedstock. In a preferred embodiment of the present invention, the gas may be supplied at a flow rate of 100 to 500 ml / min during the thermal decomposition and polycondensation of a petroleum-based feedstock. If the flow rate of the gas is less than 10 ml / min, the pitch yield will be high, but the amount of low-molecular-weight components will be too high, which will be disadvantageous for subsequent processes (e.g., stabilization). If the flow rate of the gas exceeds 800 ml / min, the pitch yield may be low.

[0047] In an embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 1 to 10 hours. In a preferred embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 2 to 8 hours. In a more preferred embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 2 to 7 hours. If the pyrolysis and condensation polymerization time of the petroleum-based feedstock is less than 1 hour, it is difficult to produce a pitch with a high softening point, and if the pyrolysis and condensation polymerization time of the petroleum-based feedstock exceeds 10 hours, an excessive amount of quinoline-insoluble components may be produced.

[0048] In a specific example of the present invention, the pyrolysis and polycondensation of the petroleum-based raw material may be carried out under stirring. The stirring conditions for the petroleum-based raw material are not particularly limited, but for example, a stirrer rotating at 10 to 500 rpm may be used.

[0049] In an embodiment of the present invention, the pitch synthesized in step (1) may have a softening point of 200 to 350°C. In a preferred embodiment of the present invention, the pitch may have a softening point of 200 to 330°C. In a more preferred embodiment of the present invention, the pitch may have a softening point of 200 to 300°C. Since the pitch produced by the present invention has a high softening point, when it is used as a precursor for producing a carbon support, the stabilization process is easy and a high yield can be obtained after carbonization and activation.

[0050] In an embodiment of the present invention, the yield of pitch synthesized in step (1) may be 10-50 wt %. In another embodiment of the present invention, the yield of pitch may be 10-40 wt %.

[0051] In an embodiment of the present invention, the pitch synthesized in step (1) may exhibit a mesophase containing isotropic and anisotropic components. In a method for producing a porous carbon support from a petroleum-based feedstock according to an embodiment of the present invention, the pitch synthesized in step (1) may be centrifuged at high temperature to measure the respective contents of the isotropic and anisotropic components in the pitch without the need for a separate optical microscope. Furthermore, this data may be combined with the SARA analysis results described below to predict the specific surface area, tap density, average particle size, and pore characteristics of the porous carbon support produced from the pitch. Based on this, the specific surface area, tap density, average particle size, and pore characteristics of the porous carbon support may be controlled by adjusting at least one process variable in step (1).

[0052] In the above example, the mesophase content of the pitch synthesized in step (1) may be 0.2 or less. As used herein, mesophase may refer to an intermediate phase between an isotropic liquid phase and a crystalline solid phase, and isotropic liquid crystalline (carbonaceous A pitch containing a complex mixture of many aromatic hydrocarbons, including mesophase particles. The mesophase content may be 0.2 or less (20% by volume or less), 0.15 or less (15% by volume or less), or 0.1 or less (10% by volume or less) based on the volume of the total pitch, and the lower limit is not particularly limited, but may be, for example, 0 or more (0% by volume or more) or more than 0 (more than 0% by volume). If the mesophase content of the pitch is very high, there is a high possibility that crystalline carbon will be produced, and pores may not be well formed during the production of the carbon support.

[0053] The mesophase content of the pitch may be measured through high-temperature centrifugation. Specifically, the target temperature for high-temperature centrifugation is set to 350-360°C, slightly higher than 340°C, the approximate temperature at which the anisotropic components of the pitch to be analyzed begin to melt, and the temperature is increased at a rate of approximately 15°C / min. Once the equipment reaches the target temperature, the pitch is centrifuged for 15-30 minutes. After centrifugation, the tube and the pitch inside the tube are polished to confirm that the isotropic and anisotropic components have been separated, and the areas of each are measured to calculate the anisotropic content.

[0054] In the process for preparing a porous carbon support from a petroleum-based feedstock according to an embodiment of the present invention, a pretreatment step of the petroleum-based feedstock may be performed prior to step (1). By removing low-boiling point components contained in the petroleum-based feedstock through the pretreatment step, a pitch with a higher softening point can be produced.

[0055] In an embodiment of the present invention, the pretreatment step may be carried out at a temperature equal to or lower than the temperature of the pyrolysis and polycondensation of the petroleum-based feedstock in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be carried out at a temperature of 250 to 450°C, preferably 250 to 400°C, and more preferably 300 to 400°C.

[0056] In an embodiment of the present invention, the pretreatment step may be carried out for a time equal to or shorter than the time for pyrolysis and polycondensation of the petroleum-based feedstock in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be carried out for 1 to 8 hours, preferably 1 to 6 hours, and more preferably 1 to 5 hours.

[0057] The pitch in step (1) of the method for producing a porous carbon support according to the present invention may satisfy the following relational expression 1:

[0058] [Equation 1]

[0059] S / S P ×100+MP≦0.5

[0060] In the above Relational Formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results for the synthesized pitch, and S P is the softening point of the pitch and MP is the volume fraction of the mesophase content in the synthesized pitch.

[0061] SARA can refer to an analytical method that separates pitches by polarizability and polarity. The saturates fraction can consist of non-polar materials, including linear, branched, and cyclic saturated hydrocarbons (paraffins). Aromatics, which contain one or more aromatic rings, can be slightly more polar. The remaining two fractions, resins and asphaltenes, can have polar substituents. The difference between the two is that asphaltenes are insoluble in excess heptane (or pentane), while resins are insoluble in excess heptane (or pentane). The advantage of this is that it is miscible with pentane.

[0062] The aforementioned S / S P×100+MP may be 0.50 or less, 0.49 or less, 0.48 or less, 0.47 or less, 0.46 or less, or 0.45 or less, and the lower limit is not particularly limited, but may be, for example, 0 or more or greater than 0. P When ×100+MP satisfies the above range, a porous carbon support having a high mesopore ratio while being stable can be produced. P If the ×100+MP value is very large, the degree of polymerization of the pitch may be low, and the softening point may be low.

[0063] In one embodiment of the present invention, the saturated hydrocarbon content of the pitch synthesized in step (1) may be 0.6% by mass or less. The lower limit of the saturated hydrocarbon content of the pitch synthesized in step (1) may be, for example, 0% by mass or more or more than 0% by mass, but is not limited thereto. When the saturated hydrocarbon content of the pitch synthesized in step (1) satisfies this range, the pore characteristics of the porous carbon support to be prepared can be controlled within an appropriate range.

[0064] In another example, the proportion of aromatic compounds in the pitch synthesized in step (1) may be 60% by mass or more. The aromatic compound may be a compound having 1 to 4 aromatic rings. Specifically, the aromatic compound may include at least one selected from the group consisting of substituted or unsubstituted benzene, naphthalene, phenanthrene, indene, biphenyl, anthracene, tetralin, and fluorene. The upper limit of the aromatic compound content is not particularly limited, but may be, for example, 75% by mass or less. When the aromatic compound content satisfies this range, it may be advantageous to obtain a porous carbon support having controlled pore characteristics.

[0065] In another example, the asphaltene content of the pitch synthesized in step (1) of the method for producing a porous carbon support according to the present invention may be 30% by mass or less. The lower limit of the asphaltene content may be, for example, 20% by mass or more, but is not limited thereto. If the asphaltene content of the pitch synthesized in step (1) is too low, it may be impossible to produce a pitch having a desired molecular weight. If the asphaltene content is too high, the mesophase content may be excessively high, or pore development may be reduced during the production of the porous carbon support.

[0066] In the method for producing a porous carbon support according to the present invention, the content of resin may be the remainder of the saturated hydrocarbons, aromatic compounds, and asphaltene of the pitch. For example, when the total content of the saturated hydrocarbons, aromatic compounds, and asphaltene is 95% by mass, the content of resin may be 5% by mass.

[0067] When the result of the SARA analysis of the method for producing a porous carbon support according to the present invention satisfies the above-mentioned values, a porous carbon support having controlled pore characteristics can be obtained even if the solid pitch pellets described below are stabilized, carbonized, and activated without being separately crushed.

[0068] Stage 2

[0069] In step (2) of the process for producing a porous carbon support from a petroleum-based raw material according to one embodiment of the present invention, the pitch can be solidified to obtain a solid pitch.

[0070] The liquid pitch obtained in step (1) is solidified, for example, by extrusion and cooling to obtain solid pitch pellets. The process of extruding the liquid pitch, cooling it, and obtaining solid pitch can be carried out using commercially available equipment. For example, this process can be carried out using an IPCO double belt cooler and flaker, but is not particularly limited to this equipment.

[0071] The pitch obtained in step (2) has an average particle size of 1 to 30 mm, preferably 5 to 25 mm. When the average particle size of the pitch is within this range, when the pitch is directly used to produce a porous carbon support through step (3) described below, the pitch has excellent pore characteristics and can be effectively used for various applications.

[0072] However, if necessary, the pitch obtained in step (2) can be further crushed or pulverized and classified. The pitch can be further pulverized through crushing or pulverization, and the particle size distribution of the pitch can be made uniform through classification. Here, classification can be performed using dry classification, wet classification, or classification using a sieve. Powder pitch with a diameter of 50 to 500 μm can be obtained by the crushing or pulverization and classification process.

[0073] Stage 3

[0074] In the method for producing a porous carbon support according to the present invention, step (3) may be a step of stabilizing solid pitch. Specifically, it may be a step of stabilizing the pitch structure by primary oxidation of solid pitch. If the solid pitch is pulverized in step (2), this step may be a step of stabilizing the pulverized powder pitch.

[0075] First, the pitch obtained in step (2) is subjected to primary oxidation to stabilize the carbon structure of the pitch.

[0076] In an embodiment of the present invention, the stabilization of the pitch may be carried out in an oxidizing gas atmosphere. In a preferred embodiment of the present invention, the stabilization of the pitch may be carried out in an air atmosphere, but is not particularly limited thereto.

[0077] In an embodiment of the present invention, pitch stabilization may be performed at a temperature of 100 to 500°C, preferably 150 to 300°C. When pitch stabilization is performed at this temperature, the carbon structure within the pitch changes from thermoplastic to thermosetting, and this structure can be stably maintained during the subsequent carbonization process. In this case, the temperature rise rate may be 2 to 10°C / min. If this temperature rise rate is too slow, productivity may be poor, and if the temperature rise rate is too fast, uniform stabilization may be difficult.

[0078] In a specific example of the present invention, the stabilization of the pitch can be carried out at a pressure of 0.1 to 10 bar, preferably 0.5 to 5 bar. When the stabilization of the pitch is carried out at this pressure, the structure of the carbon inside the pitch can be sufficiently stabilized.

[0079] In a specific example of the present invention, pitch stabilization can be carried out under conditions of a flow rate of an oxidizing gas, preferably air or oxygen, of 0.1 to 500 ml / min, preferably 1 to 300 ml / min. When pitch stabilization is carried out under these oxidizing gas flow rates, the structure of the carbon inside the pitch can be sufficiently stabilized.

[0080] In an embodiment of the present invention, the stabilization of the pitch can be carried out for 1 to 10 hours, preferably 2 to 8 hours. When the stabilization of the pitch is carried out within this time, the structure of the carbon inside the pitch can be sufficiently stabilized.

[0081] Subsequently, the stabilized pitch is carbonized to obtain a carbonized body. Other functional groups contained in the carbon can be removed to obtain a carbonized product consisting essentially of pure carbon.

[0082] In an embodiment of the present invention, the carbonization of the pitch can be carried out under an inert gas atmosphere. In a preferred embodiment of the present invention, the carbonization of the pitch is carried out under a nitrogen or argon atmosphere, but is not particularly limited thereto.

[0083] In an embodiment of the present invention, the carbonization of the pitch may be carried out at a temperature of more than 700° C. and not more than 1,000° C., preferably 800 to 900° C. If the temperature during the carbonization of the pitch is lower than this range, the carbonization may not be sufficient, and if the temperature during the carbonization of the pitch is higher than this range, the carbonization yield may decrease.

[0084] In a specific example of the present invention, the carbonization of the pitch can be carried out under the condition of an inert gas, preferably nitrogen, flow rate of 0.1 to 30 ml / min, preferably 0.1 to 10 ml / min. When the carbonization of the pitch is carried out under this inert gas flow rate condition, the pitch can be sufficiently carbonized.

[0085] In an embodiment of the present invention, the carbonization of the pitch can be carried out for 0.5 to 5 hours, preferably 1 to 3 hours. When the carbonization of the pitch is carried out within this time, the pitch can be sufficiently carbonized.

[0086] Next, the carbonized material (carbonized pitch pellets) is activated to obtain a porous carbon support. Pores are formed in the pitch pellets through the activation of the carbonized material, thereby obtaining a porous carbon support.

[0087] In an embodiment of the present invention, activation of the carbonized body may be carried out in an oxidizing gas atmosphere. In a preferred embodiment of the present invention, activation of the carbonized body may be carried out in a water vapor atmosphere, but is not particularly limited thereto.

[0088] In an embodiment of the present invention, the activation of the carbonized body can be carried out at a temperature of more than 700° C. and not more than 1,000° C., preferably 800 to 900° C. When the activation of the carbonized body is carried out at this temperature, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0089] In an embodiment of the present invention, the activation of the carbonized body can be carried out at a pressure of 0.1 to 10 bar, preferably 0.1 to 5 bar. When the activation of the carbonized body is carried out at this pressure, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0090] In an embodiment of the present invention, the activation of the carbonized body can be carried out under conditions of an oxidizing gas, preferably steam, flowing at a rate of 0.1 to 100 ml / min, preferably 0.1 to 50 ml / min. When the activation of the carbonized body is carried out under these oxidizing gas flow conditions, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0091] In an embodiment of the present invention, the activation of the carbonized body can be carried out for 0.5 to 5 hours, preferably 1 to 3 hours. When the activation of the carbonized body is carried out within this time, a porous carbon support with sufficiently formed micropores and mesopores can be obtained.

[0092] In an embodiment of the present invention, the stabilization, carbonization, and activation of the pitch can each be carried out in a microwave oven. In a preferred embodiment of the present invention, the stabilization, carbonization, and activation of the pitch can all be carried out in a microwave oven. A microwave oven can increase the temperature of the pitch itself without increasing the external temperature of the pitch. This is preferable because it can increase the temperature, but is not particularly limited thereto.

[0093] In an embodiment of the present invention, the stabilization, carbonization, and activation of pitch can be carried out continuously in one device. In a preferred embodiment of the present invention, the stabilization, carbonization, and activation of pitch can be carried out continuously in one rotary kiln, but the present invention is not particularly limited to this device. By carrying out the stabilization, carbonization, and activation of pitch continuously in one device, process optimization can be achieved.

[0094] In one embodiment of the present invention, the method for producing a porous carbon substrate according to the present invention may further include a step of depositing silicon on the porous carbon substrate produced after step (3).

[0095] In this case, the deposition may be performed at a temperature of 300°C or higher and / or 600°C or lower in an atmosphere of silane (SiH4) gas at a flow rate of 50 sccm or higher and / or 500 sccm or lower. The deposition may be performed, for example, by chemical vapor deposition (CVD) under atmospheric pressure conditions, but is not limited thereto. Through the deposition, silicon may be deposited on the surface and inside the pores of the porous carbon support according to the present invention.

[0096] The present invention also relates to a porous carbon support. The porous carbon support according to the present invention may be prepared by the above-described method.

[0097] In one embodiment of the present invention, the porous carbon support according to the present invention may have a ratio of mesopore volume to total pore volume of 0.1 or more. The pores of a porous carbon support can be classified into micropores with a diameter of less than 2 nm, mesopores with a diameter of 2 to 50 nm, and macropores with a diameter of more than 50 nm, depending on their size. Research on such porous supports has focused on increasing the proportion of micropores to increase the specific surface area, or increasing the proportion of macropores to increase the amount of material supported inside the pores. However, when there are many micropores, silicon deposition inside the pores is difficult, resulting in a problem of reduced electrical capacity. Furthermore, when there are many macropores, silicon aggregates, generating stress during repeated charge / discharge processes, which can mechanically damage the negative electrode material.

[0098] On the other hand, in the case of mesopores, silicon can be sufficiently deposited deep within the pores during deposition. The porous carbon support according to the present invention has mesopores within a predetermined range, allowing a sufficient amount of silicon to be deposited inside the pores of the porous support.

[0099] The ratio of the volume of mesopores to the volume of total pores of the porous carbon support may be, but is not limited to, 0.10 or more, 0.12 or more, 0.14 or more, or 0.15 or more. The upper limit of the ratio of mesopores to total pores of the porous carbon support is not particularly limited, but may be, for example, 1.0 or less or less than 1.0. When the ratio of mesopores to total pores of the porous carbon support satisfies the above range, excessive silicon aggregation and damage due to volume expansion of silicon can be prevented while maintaining excellent electrical properties.

[0100] In one embodiment of the present invention, the tap density of the porous carbon support according to the present invention may be 0.7 g / ml or less. The tap density of the porous carbon support may be a value measured using a PT-TD200 (Pharma Test). Specifically, 40 ml of the porous carbon support is placed in a cylinder, tapped 1,000 times, and then the initial volume is observed. After the observation, the cylinder is tapped 1,000 times again, and the volume is observed. This process is repeated three times until there is no difference from the previous volume, and the tap density can be calculated as the final volume. The tap density of the porous carbon support may be 0.70 g / ml or less, 0.65 g / ml or less, or 0.60 g / ml or less, or 0.05 g / ml or more, or 0.1 g / ml or more. However, the tap density of the porous carbon support is not limited to the above. If the tap density of the porous carbon support is too low, it may be difficult to control the process during deposition of the silane gas, resulting in a reduced yield. Also, if the tap density of the porous carbon support is too high, it may be difficult to achieve a uniform coating during deposition of the silane gas.

[0101] In one embodiment of the present invention, the BET specific surface area of ​​the porous carbon support according to the present invention is 300 m 2 / g or higher and / or 3000m 2The BET specific surface area of ​​the porous carbon support may be a value measured using an ASAP 2420 (Micromeritics Instrument (USA)). Specifically, analysis is performed after vacuum drying at 300°C for 5 hours, and calculation can be performed using the BET equation and the BJH equation based on the N2 / 77K isothermal adsorption results according to ISO9277. The BET specific surface area of ​​the porous carbon support may be a value measured using an ASAP 2420 (Micromeritics Instrument (USA)) after vacuum drying at 300°C for 5 hours. 2 / g or more, 400m 2 / g or more or 500m 2 / g or more, and 2 / g or less, 2800m 2 / g or less, 2600m 2 / g or less or 2000m 2 / g or less, but is not limited thereto. If the BET specific surface area of ​​the porous carbon support is too low, the proportion of macropores may be high, which may reduce the mechanical strength of the anode material and may result in insufficient effective pores. Also, if the BET specific surface area of ​​the porous carbon support is too high, the proportion of micropores may be high, which may result in insufficient silicon deposition deep into the porous carbon support.

[0102] In one embodiment of the present invention, the diameter of the porous carbon support according to the present invention may be 20 μm or less. This diameter may refer to the D50 diameter, measured using a MICROTRAC S3500 instrument. Specifically, it may refer to the average value obtained by dispersing the porous carbon support in ethanol and then performing particle size analysis three times. The diameter of the porous carbon support may be 20 μm or less, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or more, 1 μm or more, 2 μm or more, or 3 μm or more, but is not limited thereto. If the diameter of the porous carbon support is too small, silicon may be quickly filled into the interior during coating, and further coating may be performed on the surface, resulting in a thick surface coating layer. In this case, deterioration during charge and discharge may be accelerated, and materials with small particle sizes may aggregate during electrode fabrication, resulting in significant deterioration of the aggregates. In addition, if the diameter of the porous carbon support is too large, it may be difficult to form a uniform silicon coating layer inside the support due to the difficulty in diffusing silane gas inside the porous carbon support.In addition, if the diameter of the porous carbon support is too large, it may be difficult to uniformly coat the slurry on the current collector during electrode fabrication, which may result in reduced capacity uniformity.

[0103] In one example, the porous carbon support according to the present invention may include macropores with a diameter of more than 50 nm. In this case, the ratio of the volume of the macropores to the volume of all pores of the porous carbon support may be 0.4 or less. The ratio of the volume of the macropores to the volume of all pores of the porous carbon support may be, but is not limited to, 0.40 or less, 0.38 or less, 0.36 or less, 0.34 or less, 0.32 or less, or 0.30 or less. The lower limit of the ratio of the volume of the macropores to the volume of all pores of the porous carbon support is not particularly limited, but may be, for example, 0 or more or greater than 0. If the ratio of macropores in the porous carbon support is too high, the mechanical strength of the anode material manufactured using the porous carbon support may be reduced. Furthermore, localized aggregation of silicon may occur within the anode material, generating stress due to volume expansion during repeated charge and discharge processes, which may cause damage to the anode material.

[0104] In one example, silicon may be disposed on the surface and inside the pores of the porous carbon support according to the present invention. The silicon may be formed by vapor deposition, as described above. Because the porous carbon support according to the present invention has the above structure, the negative electrode material prepared using the porous carbon support according to the present invention can have high electric capacity while minimizing the influence of volume expansion of silicon.

[0105] In another example, the content of the deposited silicon may be 10 wt % or more based on the weight of the total particles. The silicon content may be a value obtained by analysis using an energy dispersive spectrometer (EDS). The content of the deposited silicon may be, but is not limited to, 10 wt % or more, 15 wt % or more, 20 wt % or more, 25 wt % or more, or 30 wt % or more. The content of the deposited silicon may be, but is not limited to, 60 wt % or less, 58 wt % or less, 56 wt % or less, 54 wt % or less, 52 wt % or less, or 50 wt % or less. If the content of the deposited silicon is too low, the electrical capacity may decrease. If the content of silicon is too high, the problem caused by the volumetric expansion of silicon during charging and discharging may not be resolved, which may cause structural damage to the anode material and reduce cycle characteristics.

[0106] The present invention also relates to a battery anode material comprising the porous carbon support described above. The battery anode material comprising the porous carbon support according to the present invention can have improved mechanical strength as well as high electrical capacity and excellent cycle characteristics.

[0107] The method for manufacturing the battery anode material is not particularly limited, and a general method for manufacturing a battery anode material can be used. For example, the battery anode material can be manufactured by mixing a porous carbon support, an active material, a conductive agent, a binder, etc., and coating / drying / rolling the mixture onto a member such as an electrode current collector, but is not limited thereto.

[0108] The present invention also relates to a battery comprising the aforementioned battery anode material. The battery comprising the battery anode material according to the present invention may be, but is not limited to, a lithium ion battery or an all-solid-state battery.

[0109] The lithium-ion battery may specifically include a positive electrode, a negative electrode, a separator, and an electrolyte. In this case, the negative electrode may include the battery negative electrode material described above. The positive electrode may be made of a material usable in lithium-ion batteries, such as, but not limited to, one or more positive electrode active materials selected from doped or undoped lithium nickel oxide, lithium cobalt oxide, lithium cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium nickel cobalt aluminum oxide, and a positive electrode current collector selected from aluminum, stainless steel, nickel, titanium, platinum, or alloys thereof. The separator may be a conventional separator usable in lithium-ion batteries. The separator may include, but is not limited to, one or more materials selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE).

[0110] The negative electrode of the lithium ion battery may include the above-described battery negative electrode material. The negative electrode may include a negative electrode current collector and a battery negative electrode material, and the negative electrode current collector may include one or more selected from, but not limited to, aluminum, stainless steel, nickel, titanium, platinum, or alloys thereof.

[0111] The electrolyte of the lithium ion battery may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a polymer electrolyte, or a molten inorganic electrolyte that can be used in a lithium ion battery.

[0112] The all-solid-state battery may specifically include, but is not limited to, a positive electrode, a negative electrode, and a solid electrolyte, and may further include a separator as needed. The positive electrode may include the above-described positive electrode active material, and may optionally include a positive electrode current collector as needed, but is not limited to these.

[0113] The negative electrode may include the battery negative electrode material according to the present invention. The negative electrode may have a single-layer structure including the battery negative electrode material, or may further include a negative electrode current collector as needed, but is not limited thereto.

[0114] The solid electrolyte can be selected from solid electrolytes that can be used in all-solid-state batteries, and may be, for example, one or more selected from the group consisting of garnet-type, Nasicon-type, LISICON-type, perovskite-type, and LiPON-type, but is not limited thereto. [Example]

[0115] Preferred examples are shown below to aid in understanding the present invention. However, the following examples are provided merely to facilitate understanding of the present invention, and the contents of the present invention are not limited to these examples.

[0116] Example 1: Preparation of porous carbon support

[0117] 300 g of petroleum residual oil (YNCC, HTC PFO (pyrolysis fuel oil)) was placed in a reactor equipped with a stirrer, and pyrolysis and polycondensation were carried out while supplying nitrogen at a flow rate of 100 ml / min. The stirrer was rotated at 200 rpm to mix the reactants. The polymerized pitch was solidified and pelletized, yielding solid pitch pellets with an average particle size of 1 to 30 mm.

[0118] The solid pitch pellets obtained above were crushed, and the crushed powder was then charged into a three-zone rotary kiln for stabilization, carbonization and activation, in that order.

[0119] Thereafter, the activated primary powder porous carbon support was re-pulverized using a pulverizer (Netch air jet mill) to prepare a secondary powder porous carbon support.

[0120] Examples 2 to 4 and Comparative Examples 1 to 4

[0121] Porous carbon supports were prepared under the same conditions as in Example 1, except that pyrolysis and condensation polymerization were carried out under the conditions shown in Table 1 below. Stabilization in Examples 1 to 4 and Comparative Examples 1 to 4 was carried out at a temperature 50°C higher than the softening point.

[0122] [Table 1]

[0123] Test Example 1: SARA analysis

[0124] SARA analysis was performed on the pitch obtained in the production example. A Chromarod S-5 was loaded onto a chroma-rod holder, and a sample (10-15 mg / ml) dissolved in dichloromethane was spotted onto it. Using the spotting guide, 1 μl was dropped into the holder using a micropipette in 7-8 increments. After drying, the chroma-rod holder was placed in a tank filled with the developing solvent and developed. The developing solvents used were hexane, toluene, and methanol / dichloromethane (5:95), in that order. The dried chroma-rod holder was attached to an IATROSCAN mK-6, and a 30-second scan was performed. The Clarity program on the connected PC was then run, and the analysis was performed. The results are shown in Figure 1.

[0125] Test Example 2: Anisotropy measurement

[0126] High-temperature centrifugation was performed on the pitch obtained in the preparation example. 0.6 g of ground pitch was placed in a glass tube with an inner diameter of 6 mm, an outer diameter of 8 mm, and a height of 90–100 mm. Two or four tubes were placed in a balanced arrangement inside a high-temperature centrifuge. The heater temperature of the high-temperature centrifuge was set to 410°C and increased at a rate of 15°C per minute. Approximately 30 minutes after the heater reached the target temperature, when the actual internal temperature reached 350–360°C, the tube was centrifuged at 1,787–3,096 rpm (500–1,500 g) for 15–30 minutes. The tube containing the centrifuged pitch was cut to a length of 23–28 mm from the bottom, cured with epoxy resin, and polished using a Tegramin-25 polisher. The polished cross section was photographed using a polarizing microscope, and the anisotropic / isotropic area was manually determined using the ImageJ program. The ratio of the anisotropic area to the total area was calculated.

[0127] [Table 2]

[0128] Test Example 3: Measurement of physical properties of porous carbon support

[0129] The specific surface area of ​​the porous carbon support was measured using a Belsorp Mini II in accordance with ASTM D4820-93. The tap density of the carbon support was measured using a tap density tester (Electrolab, ETD-1020x) in accordance with ASTM B527. The average particle size of the carbon support was measured using a particle size analyzer (Horiba, Laser Particle Analyzer, LA-960V2) in accordance with ASTM E112.

[0130] [Table 3]

[0131] The evaluation results in Table 3 show the measured values ​​of the primary powder porous carbon support. In the cases of Comparative Examples 1 and 2, stabilization was not achieved and the porous carbon support was melted, making it impossible to produce a porous carbon support.

[0132] Experimental Example 1: Electrochemical evaluation of secondary batteries

[0133] Carbon-silicon composite particles were produced using the porous carbon support prepared in Example 4. 15 to 20 g of the porous carbon support powder prepared in Example 4 was placed in a rotary kiln, and silane (SiH4) gas was injected to coat the porous carbon support.

[0134] The silane gas coating was carried out at atmospheric pressure, at a temperature of 475°C and a flow rate of 300 sccm for 1 hour, to produce carbon-silicon composite particles with silicon coated on the porous carbon support.

[0135] The carbon-silicon composite particles were used to manufacture half coin cells under the manufacturing conditions shown in Table 4 below.

[0136] [Table 4]

[0137] In Table 4, AM, CM, and BM represent the active material (silane-deposited porous carbon support), conductor (Super P carbon black), and binder (styrene butadiene rubber / carboxymethyl cellulose 5:5), respectively, and EC, EMC, DMC, FEC, VC, and PS represent ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, fluoroethylene carbonate, vinylene carbonate, and propane sultone, respectively.

[0138] Experimental Examples 2 and 3

[0139] Carbon-silicon composite particles were prepared in the same manner as in Experimental Example 1, except that the porous carbon supports prepared in Comparative Examples 3 and 4 were used, and half coin cells were fabricated using the carbon-silicon composite particles.

[0140] [Table 5]

[0141] Table 5 compares the physical properties of the porous carbon supports of Example 4, Comparative Example 3, and Comparative Example 4 before and after silicon coating. In Experimental Examples 1 to 3, silicon was coated on the surface and inside the pores of the porous carbon support, resulting in a decrease in the relative area and an increase in tap density after coating compared to before coating. Referring to Table 5, it can be seen that Experimental Example 1, which used the porous carbon support of Example 4, had a silicon coating amount of 39.7 wt%. Meanwhile, Experimental Examples 2 and 3, which used the porous carbon supports of Comparative Examples 3 and 4, had silicon contents of 31.6 wt% and 24.4 wt%, respectively.

[0142] Fig. 2 is an SEM image of the carbon-silicon composite particles produced in Experimental Example 1, and Fig. 3 is an SEM image of the carbon-silicon composite particles produced in Experimental Example 2. Figs. 2 and 3 were taken in BSE mode, and the higher the atomic number, the brighter the output, so in Figs. 2 and 3, the brighter areas indicate regions where Si is located, and the darker areas indicate regions where C is located.

[0143] 2 and 3, it can be seen that the inside of the particles in Experimental Example 1, which used the porous carbon support of Example 4, is brighter than in Experimental Example 2, which used the porous carbon support of Comparative Example 3. It can also be seen that the thickness of the Si region coated on the outside of the support is thicker in Experimental Example 2 than in Experimental Example 1. This confirms that Si was evenly coated even inside the support in Experimental Example 1. On the other hand, it can be seen that in Experimental Example 2, not enough Si was coated inside the support, but rather was deposited on the outer surface.

[0144] Furthermore, the half coin cells manufactured in Experimental Examples 1 to 3 were subjected to electrochemical analysis under the following conditions, and the results are shown in Table 6 below.

[0145] Cutoff voltage (V): 0.005~1.5V (formation), 0.005~1.2V (cycle)

[0146] Formation C rate (C): 0.1C lithiation, 0.1C delithiation

[0147] Cycle C rate (C): 0.5C lithiation, 0.5C delithiation

[0148] [Table 6]

[0149] Referring to Table 6, it can be seen that Experimental Example 1 prepared from the porous carbon support of Example 4 has better performance in terms of initial charge efficiency (ICE) and discharge capacity than Experimental Example 3 prepared from the porous carbon support of Comparative Example 4. In addition, it can be seen that the capacity retention rate after 50 charge / discharge cycles in Experimental Example 1 was 70.5%, while Experimental Examples 2 and 3 were 49.7% and 51.9%, respectively, which were significantly lower than Experimental Example 1. This shows that when the porous carbon support according to an embodiment of the present invention is used, a secondary battery with excellent properties such as initial charge / discharge capacity, initial charge efficiency, and charge / discharge cycle can be manufactured.

[0150] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and the accompanying drawings, but should be limited by the appended claims. Therefore, various substitutions, modifications, and changes may be made by a person skilled in the art without departing from the technical spirit of the present invention as set forth in the claims, and these are also included in the scope of the present invention. [Industrial Applicability]

[0151] The present invention can provide a method for producing a porous carbon support, which includes: (1) a step of synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) a step of solidifying the pitch to obtain solid pitch; and (3) a step of producing a carbon support from the solid pitch, wherein the pitch in the step (1) satisfies the following relational expression 1:

[0152] [Equation 1]

[0153] S / S P ×100+MP≦0.5

[0154] In the above Relational Formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results for the synthesized pitch, and S P is the softening point of the pitch and MP is the volume fraction of the mesophase content in the synthesized pitch.

Claims

1. (1) synthesizing pitch by pyrolysis and polycondensation of a petroleum-based raw material; (2) solidifying the pitch to obtain a solid pitch; (3) producing a carbon support from solid pitch; The method for producing a porous carbon support in step (1) satisfies the following relational expression 1: [Relationship 1] S / S Ｐ ×100+MP≦0.5 In the above formula 1, S is the mass ratio of saturated hydrocarbons derived from the SARA (saturates-aromatics-resins-asphaltenes) analysis results to the synthesized pitch, and S Ｐ is the softening point of the pitch, and MP is the volume ratio of the mesophase content in the synthesized pitch.

2. 2. The method for producing a porous carbon support according to claim 1, wherein the polycondensation temperature of the pitch synthesis in step (1) is in the range of 300°C or more and / or 450°C or less.

3. 2. The method for producing a porous carbon support according to claim 1, wherein the softening point of the pitch synthesized in step (1) is 200° C. or higher.

4. 2. The method for producing a porous carbon support according to claim 1, wherein the pitch synthesized in step (1) has a saturated hydrocarbon content of 0.6% by mass or less based on the total mass of the pitch.

5. 2. The method for producing a porous carbon support according to claim 1, wherein the pitch synthesized in step (1) has an asphaltene content of 30% by mass or less based on the total mass of the pitch.

6. The method for producing a porous carbon support according to claim 1 , wherein the step (3) of producing a carbon support comprises the steps of stabilizing, carbonizing, and activating the solid pitch.

7. The method for producing a porous carbon support according to claim 1 , further comprising the step of depositing silicon on the porous carbon support.

8. The deposition may be carried out at a temperature of 300° C. or more and / or 600° C. or less and at a flow rate of 50 sccm or more and / or 500 sccm or less of silane (SiH ４ 8. The method for producing a porous carbon support according to claim 7, wherein the method is carried out under a gas atmosphere.

9. The method for producing a porous carbon support according to claim 7 , wherein the silicon content is 10% by weight or more based on the weight of the entire support.

10. A porous carbon support produced by the production method according to any one of claims 1 to 9.

11. A battery negative electrode material comprising the porous carbon support of claim 10.

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