Method for preparing porous carbon support and porous carbon support prepared thereby

Abstract

The invention can provide the preparation method of the porous carbon carrier, which comprises the following steps: (1) performing thermal decomposition and polycondensation on a petroleum-based raw material to form asphalt; (2) curing and granulating the asphalt to obtain solid asphalt particles; (3) stabilizing the solid asphalt particles without crushing; and (4) carbonizing the stabilized asphalt particles to obtain a carbonized product.

Description

Technical Field

[0001] The invention relates to a method for preparing a porous carbon carrier and the porous carbon carrier prepared thereby. Background Art

[0002] Carbon materials are materials made from carbon, one of the most common resources on Earth. Lightweight, high-strength, and with excellent electrical and thermal conductivity, carbon materials are core materials widely used in hydrogen-powered vehicles, aviation, secondary batteries, and high-end consumer products.

[0003] Carbon materials can be made from a variety of raw materials, such as palm oil shells, polyacrylonitrile, rayon, and pitch. However, it is difficult to control the molecular weight and composition of carbon materials made from solid raw materials such as palm oil shells (Korean Patent Application No. 10-2019-0093960).

[0004] On the other hand, as a viscoelastic solid polymer extracted from crude oil or plants, asphalt has the following advantages: high yield when converted into carbon materials, low raw material cost, and the ability to reduce the energy required for heat treatment because its molecular structure is closer to graphite structure than other raw materials (U.S. Patents No. 4242196 and No. 4340464).

[0005] In particular, pyrolysis fuel oil (PFO), naphtha cracking bottom oil (NCB), vacuum residue (VR), fluid catalytic cracking decant oil (FCC-DO), etc., which are obtained as by-products in the petroleum refining process, have a high content of aromatic compounds and a low content of impurities such as sulfur and nitrogen. Therefore, asphalt produced from them has attracted much attention as a carbon material.

[0006] Conventionally, a porous carbon support is prepared by preparing a carbon precursor in the form of pellets from the above-mentioned pitch, crushing it into a powder form, and then performing an activation process. However, the porous carbon support prepared in this way mainly consists of micropores, and therefore has the problem of not being able to be well deposited into deep pores when chemical vapor deposition (CVD) is performed in subsequent processes. Summary of the Invention

[0007] Technical issues

[0008] One of the various objects of the present invention is to provide a method for preparing a porous carbon support having controlled pore characteristics and capable of being fully deposited into deep pores during a chemical vapor deposition process, and a porous carbon support prepared by the preparation method.

[0009] One of the multiple objects of the present invention is to provide a method for preparing a porous carbon support capable of preparing a negative electrode material with high charge and discharge capacity, and a porous carbon support prepared by the preparation method.

[0010] One of the various objects of the present invention is to provide a method for preparing a porous carbon support capable of preparing a negative electrode material with improved cycle characteristics, and a porous carbon support prepared by the preparation method.

[0011] One of the multiple objects of the present invention is to provide a method for preparing a porous carbon support capable of preparing a negative electrode material with excellent mechanical properties and a porous carbon support prepared by the preparation method.

[0012] Technical Solution

[0013] According to an exemplary embodiment of the present invention, the present invention can provide a method for preparing a porous carbon carrier, which includes: (1) thermally decomposing and polycondensing a petroleum-based raw material to form asphalt; (2) solidifying and granulating the asphalt to obtain solid asphalt particles; (3) stabilizing the above-mentioned solid asphalt particles without crushing; and (4) carbonizing the stabilized asphalt particles to obtain a carbonized product.

[0014] In this case, the polycondensation temperature of the pitch synthesis in the above step (1) may be in the range of 350°C or higher and / or 500°C or lower.

[0015] In addition, the softening point of the asphalt synthesized in the above step (1) can be above 200°C.

[0016] In an example of the present invention, the thickness of the solid asphalt particles in step (3) may be greater than 1 mm.

[0017] In an example, step (3) may include heating the uncomminuted solid asphalt pellets to a temperature of 250° C. or higher and / or 400° C. or lower, and the heating may be performed by microwaves or plasma.

[0018] Meanwhile, the oxygen content of the asphalt particles stabilized in the above step (3) may be 10 wt% or more.

[0019] Furthermore, the distribution deviation of the oxygen content in the cross section of the asphalt pellets stabilized in the above step (3) can be 30% or less.

[0020] In an example, the method for preparing the porous carbon support according to the present invention may further comprise depositing silicon after the above step (4).

[0021] In this case, the deposition may be performed at a temperature of 300° C. or higher and / or 600° C. or lower and in a silane (SiH 4 ) gas atmosphere of 50 sccm or higher and / or 500 sccm or lower.

[0022] In addition, the content of the deposited silicon may be 10 wt % or more relative to the total weight of the porous carbon support.

[0023] Another exemplary embodiment of the present invention may provide a porous carbon support prepared by the above-mentioned preparation method.

[0024] Yet another exemplary embodiment of the present invention may provide a battery negative electrode material including the porous carbon support.

[0025] Technical Effects

[0026] One of the effects of the present invention is that it is possible to provide a method for producing a porous carbon support in which silicon is sufficiently deposited in inner pores by forming mesopores in the outer periphery and micropores in the inner portion, and a porous carbon support produced by the production method.

[0027] One of the effects of the present invention is that it can provide a method for producing a porous carbon support capable of producing a negative electrode material having a high charge and discharge capacity, and a porous carbon support produced by the method.

[0028] One of the effects of the present invention is to provide a method for preparing a porous carbon support capable of preparing a negative electrode material with improved cycle characteristics, and a porous carbon support prepared by the preparation method.

[0029] One of the effects of the present invention is to provide a method for preparing a porous carbon support capable of preparing a negative electrode material with excellent mechanical properties, and a porous carbon support prepared by the preparation method.

[0030] However, various beneficial advantages and effects of the present invention are not limited to the above contents and can be more easily understood through the process of describing specific embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an SEM image of the cross section of the asphalt immediately after stabilization in Preparation Example 1.

[0032] Figure 2 This is an SEM image of the cross section of the asphalt immediately after stabilization in Preparation Example 3.

[0033] Figure 3 Graphs showing the results of electrochemical evaluations of half coin cells fabricated using the porous carbon supports of Example 1 and Comparative Example 1, respectively. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention in conjunction with specific embodiments and accompanying drawings. However, this does not limit the technology described in this specification to specific embodiments. It should be understood that it includes various modifications, equivalents, and / or alternatives to the embodiments of this specification. In the description of the drawings, similar reference numerals may be used for similar components.

[0035] In addition, in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the thickness is exaggerated to clearly indicate various layers and regions, and components having the same function within the scope of the same concept may be described using the same reference numerals.

[0036] In this specification, expressions such as "have", "may have", "include" or "may include" refer to the existence of corresponding features (for example, numbers, functions, actions or components and other constituent elements), and do not exclude the existence of other features.

[0037] In this specification, expressions such as "A or B", "at least one of A or / and B", or "one or more of A or / and B" may include all possible combinations of the items listed together. For example, "A or B", "at least one of A and B", or "at least one of A or B" may refer to all of the following situations: (1) including at least one A; (2) including at least one B; or (3) including at least one A and at least one B.

[0038] Unless otherwise indicated, all numbers and expressions relating to amounts of ingredients, reaction conditions and the like used in this specification are to be understood as being modified by the term "about".

[0039] The present invention relates to a method for preparing a porous carbon support. The method for preparing a porous carbon support according to an exemplary embodiment of the present invention may include: (1) thermally decomposing and polycondensing a petroleum-based feedstock to form asphalt; (2) solidifying and granulating the asphalt to obtain solid asphalt particles; (3) stabilizing the solid asphalt particles without crushing them; and (4) carbonizing the stabilized asphalt particles to obtain a carbonized product.

[0040] Hereinafter, each step of the present invention will be described in detail.

[0041] Step (1) of the method for preparing the porous carbon support according to the present invention may be a step of synthesizing pitch by thermally decomposing and polycondensing a petroleum-based raw material.

[0042] In a specific embodiment of the present invention, the petroleum-based feedstock may include at least one selected from pyrolysis fuel oil (PFO), naphtha cracking bottom oil (NCB), ethylene decomposition bottom oil (EBO), vacuum residue (VR), deasphalted oil (DAO), atmospheric residue (AR), fluidized catalytic cracking decant oil (RFCC-DO), residual catalytic cracking decant oil (RFCC-DO) and heavy aromatic oil. In a preferred embodiment of the present invention, the petroleum-based feedstock may include pyrolysis fuel oil.

[0043] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based feedstock can be carried out at a temperature of 350°C or higher and / or 500°C or lower. The thermal decomposition and polycondensation temperatures may be 350°C or higher, 360°C or higher, 370°C or higher, 380°C or higher, 390°C or higher, 400°C or higher, 410°C or higher, 420°C or higher, or 430°C or higher, and may be 500°C or lower, 490°C or lower, 480°C or lower, or 470°C or lower, but are not limited thereto. When the thermal decomposition and polycondensation temperatures meet the above ranges, a pitch containing a large amount of relatively low molecular weight components can be produced. Moreover, during the activation process described below, the relatively low molecular weight components are vaporized first, thereby allowing for sufficient formation of mesopores in the carbon support. If the thermal decomposition and polycondensation temperatures of the petroleum-based feedstock are too low, it is difficult to produce a pitch that is solid at room temperature. If the above temperature is too high, the pitch contains a large amount of relatively high molecular weight components, and thus a carbon support with mesopores may not be produced.

[0044] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based feedstock can 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 can be oxygen, ozone, or a combination thereof; the inert gas can be nitrogen, helium, neon, argon, or a combination thereof; and the mixed gas can be air, but is not particularly limited thereto.

[0045] When an oxidizing gas is used during the thermal decomposition and polycondensation of a petroleum-based feedstock, a pitch with a high softening point can be produced, but thermal decomposition and polycondensation at high temperatures are difficult. When an inert gas is used during the thermal decomposition and polycondensation of a petroleum-based feedstock, thermal decomposition and polycondensation can be carried out at high temperatures, but it is difficult to produce a pitch with a relatively high softening point. When a mixed gas of an oxidizing gas and an inert gas is used during the thermal decomposition and polycondensation of a petroleum-based feedstock, a pitch with a relatively high softening point can be produced by thermal decomposition and polycondensation at relatively high temperatures.

[0046] In a specific embodiment of the present invention, during the thermal decomposition and polycondensation of petroleum-based raw materials, the above-mentioned gas can be supplied with a flow rate of 10ml / minute to 800ml / minute. In a preferred specific embodiment of the present invention, during the thermal decomposition and polycondensation of petroleum-based raw materials, the above-mentioned gas can be supplied with a flow rate of 100ml / minute to 500ml / minute. If the flow rate of the above-mentioned gas is less than 10ml / minute, the yield of pitch increases, but the low molecular weight component increases too much, which is disadvantageous for subsequent processes (e.g., stabilization). If the flow rate of the above-mentioned gas exceeds 800ml / minute, the yield of pitch may decrease.

[0047] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out for 1 hour to 10 hours. In a preferred specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out for 2 hours to 8 hours. In a more preferred specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out for 2 hours to 7 hours. If the thermal decomposition and polycondensation time of the petroleum-based raw material is less than 1 hour, it is difficult to prepare asphalt with a high softening point. If the thermal decomposition and polycondensation time of the petroleum-based raw material exceeds 10 hours, excessive quinoline-insoluble components may be produced.

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

[0049] In a specific embodiment of the present invention, the softening point of the pitch synthesized in step (1) can be 200°C or higher. The pitch synthesized in step (1) has a high softening point, and when used as a precursor for preparing a carbon support, it facilitates stabilization and can achieve a high yield after carbonization and activation. The upper limit of the softening point of the pitch can be, for example, 350°C or lower, 330°C or lower, or 300°C or lower, but is not limited thereto.

[0050] In a specific embodiment of the present invention, the yield of the asphalt synthesized in step (1) can be 10% to 50% by weight. In another specific embodiment of the present invention, the yield of the asphalt can be 10% to 40% by weight. In yet another specific embodiment of the present invention, the yield of the asphalt can be 20% to 30% by weight.

[0051] In the process for preparing a porous carbon support from a petroleum-based feedstock according to an embodiment of the present invention, a step of pretreating the petroleum-based feedstock may be performed before step (1). By removing low-boiling point components contained in the petroleum-based feedstock through the pretreatment step, a pitch having a higher softening point can be prepared.

[0052] In a specific embodiment of the present invention, the pretreatment may be performed at a temperature equal to or lower than the thermal decomposition and polycondensation temperature of the petroleum-based feedstock in step (1), but is not particularly limited to the above conditions. Specifically, the pretreatment step may be performed at 250° C. to 450° C., preferably 250° C. to 400° C., and more preferably 300° C. to 400° C.

[0053] In a specific embodiment of the present invention, the pretreatment step may be performed for a time equal to or shorter than the thermal decomposition and polycondensation time of the petroleum-based feedstock in step (1), but is not particularly limited to the above conditions. Specifically, the pretreatment step may be performed for 1 to 8 hours, preferably 1 to 6 hours, and more preferably 1 to 5 hours.

[0054] Step (2)

[0055] In the method for preparing the porous carbon carrier according to the present invention, step (2) may be a step of solidifying and granulating the asphalt to obtain solid asphalt particles.

[0056] The liquid asphalt obtained in step (1) is solidified, for example, by extrusion and cooling, and then granulated into a desired size to obtain solid asphalt pellets. The process of obtaining solid asphalt pellets by extruding, cooling, and granulating the liquid asphalt can be performed using a commercial device. For example, a double belt cooler & flaker from IPCO can be used to perform the process, but the process is not particularly limited to the above device.

[0057] The average particle size of the asphalt particles obtained in step (2) is 3 mm to 30 mm, preferably 5 mm to 25 mm. When the average particle size of the asphalt particles is within the above range, a porous carbon support can be prepared by stabilization, carbonization, and activation as described below without the need for separate pulverization of the asphalt particles. Therefore, the product yield can be improved through a simple process while providing a porous carbon support with controlled pore properties.

[0058] Step (3)

[0059] Step (3) in the method for preparing the porous carbon support according to the present invention may be a step of stabilizing the solid pitch particles without crushing them. Specifically, the above step may be a step of stabilizing the structure of the pitch by preliminarily oxidizing the un-crushed solid pitch particles.

[0060] In the method for preparing a porous carbon carrier according to the present invention, the solid pitch particles prepared in the above-mentioned step (2) may not be crushed. Conventionally, a carbon precursor in the form of particles is prepared, crushed into a powder form, and then an activation process is performed to prepare a porous carbon carrier. This is because, when the particles are stabilized in an un-crushed state, oxygen does not penetrate into the interior of the particles, and therefore no reaction with oxygen occurs. As a result, the isotropy of the pitch may not be maintained during the carbonization and activation process, and the interior of the particles may coke during carbonization, hindering the smooth formation of pores. However, when the prepared particles are crushed, the process is somewhat complicated, and the yield is reduced during the crushing process. According to the method for preparing a porous carbon carrier according to the present invention, the solid pitch particles prepared in step (2) are stabilized without being crushed, thereby simplifying the process and improving the process efficiency.

[0061] In one embodiment of the present invention, the thickness of the solid asphalt particles stabilized in the above step (3) can be 1 mm or more. For example, the thickness of the above asphalt particles can refer to the shortest length of the length of an imaginary line passing through the center of the asphalt particles. The thickness of the above solid asphalt particles can be 1 mm or more, 2 mm or more, or 3 mm or more, and can be 10 mm or less, 9 mm or less, or 8 mm or less, but is not limited thereto. If the solid asphalt particles stabilized in step (3) are not crushed, the above thickness can be met, and by undergoing the stabilization step described below, a porous carbon support having excellent pore characteristics and effectively used for various purposes can be prepared.

[0062] In one embodiment of the present invention, asphalt pellets can be stabilized at a temperature of 250°C or higher and / or 400°C or lower. The stabilization temperature for the asphalt pellets can be 250°C or higher, 260°C or higher, 270°C or higher, or 280°C or higher, and can be, but are not limited to, 400°C or lower, 390°C or lower, 380°C or lower, 370°C or lower, 360°C or lower, or 350°C or lower. When the asphalt pellet stabilization temperature falls within the above range, the carbon structure in the asphalt changes from thermoplastic to thermosetting, thereby stably maintaining this structure during the subsequent carbonization process.

[0063] At this time, the heating rate can be 0.5°C / minute or higher and / or 10°C / minute or lower. The heating rate can be 0.5°C / minute or higher, 1°C / minute or higher, or 2°C / minute or higher, and can be 10°C / minute or lower, 8°C / minute or lower, or 6°C / minute or lower, but is not limited thereto. If the heating rate is too slow, the interior of the pellets may not be fully stabilized. Furthermore, if the heating rate is too fast, the reaction time with oxygen is shortened, causing the temperature to rise rapidly, preventing the asphalt from crosslinking and causing it to melt.

[0064] In one example, the above-mentioned heating can be performed by microwaves and / or plasma. In the existing method for preparing porous carbon carriers, various methods are used to heat the particles in the stabilization step. A typical heating method in the stabilization step may include heating using an electric furnace, but in the case of this heating method, heat transfer in the thickness direction is insufficient, so uniform heat treatment may not be achieved. As a result, there may be problems such as the pitch not being stabilized and melting, pores not being formed in the carbonization and activation processes, or structural stabilization of the pitch not being achieved. Therefore, in the existing preparation method, solid pitch particles are crushed into powder and then stabilized. In contrast, the method for preparing a porous carbon carrier according to the present invention uses microwaves and / or plasma to heat the pitch particles, thereby heating the pitch particles from the inside of the pitch, thereby enabling uniform heating. As a result, the diffusion of oxygen into the interior is promoted, and thus, even if the pitch particles in the un-crushed state are not crushed and stabilized, a porous carbon carrier with excellent pore characteristics can be prepared.

[0065] In a specific embodiment of the present invention, the stabilization of the asphalt pellets can be performed at a pressure of 0.1 to 10 bar, preferably 0.5 to 5 bar. When the asphalt pellets are stabilized at such a pressure, the carbon structure inside the pellets can be fully stabilized.

[0066] In a specific embodiment of the present invention, asphalt pellet stabilization can be performed at a flow rate of 0.1 ml / min to 500 ml / min, preferably 1 ml / min to 300 ml / min, of an oxidizing gas, preferably air or oxygen. Stabilization of the asphalt pellets under these oxidizing gas flow rates can fully stabilize the carbon structure within the pellets.

[0067] In a specific embodiment of the present invention, the asphalt pellets can be stabilized for 1 to 10 hours, preferably 2 to 8 hours. When the asphalt pellets are stabilized for such a time, the carbon structure inside the asphalt can be fully stabilized.

[0068] In one embodiment, the oxygen content of the stabilized asphalt granules in step (3) of the method for preparing a porous carbon support according to the present invention can be 10% by weight or greater relative to the total weight of the asphalt granules. The oxygen content of the stabilized asphalt granules can be a value measured using SEM-EDS. The oxygen content of the asphalt granules can be 10% by weight or greater, 12% by weight or greater, 14% by weight or greater, or 15% by weight or greater, and can be 30% by weight or less, 28% by weight or less, 26% by weight or less, or 25% by weight or less, but is not limited thereto.

[0069] The asphalt pellets can be stabilized by heating with microwaves and / or plasma. When the asphalt pellets are heated with microwaves and / or plasma, uniform heat treatment can be achieved by heating the pellets from within, allowing the stabilized asphalt pellets to have an oxygen content within the aforementioned range. If the oxygen content of the stabilized asphalt pellets is too low, melting or coking may occur due to a lack of oxygen, which acts as a crosslinking agent during the carbonization process. Alternatively, if the oxygen content of the stabilized asphalt pellets is too high, excessive reaction with oxygen may occur, resulting in a reduced yield during the carbonization process and potentially preventing successful structural development.

[0070] In another embodiment, in step (3) of the method for preparing a porous carbon support according to the present invention, the oxygen content distribution deviation in the cross section of the stabilized pitch particles may be 30% or less. The oxygen content in the cross section of the stabilized pitch particles may be a value measured using line profiling using SEM-EDS, and the oxygen content distribution deviation (d) may refer to the percentage of the difference (|(Ma)|) between the average value (M) and the oxygen content (weight %) value (a) that differs most from the average value (M) divided by the value (|(Ma)| / M) obtained by dividing the difference (|(Ma)|) between the average value (M) and the oxygen content (weight %) value (a) that differs most from the average value (M), wherein the average value (M) is the average value (M) of the oxygen content (weight %) measured in the sample cross section. The distribution deviation of the oxygen content in the cross section of the stabilized asphalt particles in the above step (3) can be less than 30%, less than 28%, less than 26%, less than 24%, less than 22% or less than 20%. There is no particular restriction on its lower limit, but for example, it can be more than 0%, greater than 0%, more than 1%, more than 2%, more than 3%, more than 4%, or more than 5%, but is not limited thereto.

[0071] As described above, the asphalt particles in step (3) of the method for preparing a porous carbon carrier according to the present invention can be stabilized by heating with microwaves and / or plasma in an un-finely crushed state. When the asphalt particles in an un-finely crushed state are heated in air using a general electric furnace, the distribution deviation of the oxygen content may increase due to the difference in heating rate between the central part and the peripheral part of the asphalt particles. On the other hand, in the case of the method for preparing a porous carbon carrier according to the present invention, uniform heat treatment can be obtained by stabilizing the asphalt particles in an un-crushed state using microwaves and / or plasma, and a low oxygen content deviation can be obtained. If the distribution deviation of the oxygen content in the cross section of the stabilized asphalt particles in step (3) is too large, the structure of the particles and the pore structure formed thereby may develop unevenly due to the unevenness of the oxygen content.

[0072] The method for heating the uncomminuted asphalt pellets using microwaves and / or plasma in step (3) is not particularly limited, as long as the asphalt pellets are sufficiently heated. For example, microwaves with an output power in the range of 500 W to 1000 W can be used to heat the asphalt pellets, but the method is not limited thereto. Furthermore, the heating can be performed using DC or RF plasma in a vacuum (less than 500 mTorr) or under atmospheric pressure, but the method is not limited thereto.

[0073] Step (4)

[0074] Step (4) in the method for preparing a porous carbon support according to the present invention may be a step of carbonizing the stabilized pitch particles to obtain a carbonized body. By carbonizing the pitch particles, other functional groups contained in the pitch can be removed, and a carbonized body consisting essentially of pure carbon can be obtained.

[0075] In a specific embodiment of the present invention, the carbonization of the pitch may be performed under an inert gas atmosphere. In a preferred specific embodiment of the present invention, the carbonization of the pitch may be performed under a nitrogen or argon atmosphere, but is not particularly limited thereto.

[0076] In a specific embodiment of the present invention, the carbonization of the pitch may be performed at a temperature greater than 700° C. and less than or equal to 1,000° C., preferably at a temperature of 800° C. to 900° C. If the temperature during the carbonization of the pitch is lower than the above range, carbonization may not be fully achieved, and if the temperature during the carbonization of the pitch is higher than the above range, the carbonization yield may be reduced.

[0077] In a specific embodiment of the present invention, the carbonization of the pitch can be performed under an inert gas flow rate of 0.1 ml / min to 30 ml / min, preferably 0.1 ml / min to 10 ml / min, preferably nitrogen. When the carbonization of the pitch is performed under the above inert gas flow rate conditions, the pitch can be fully carbonized.

[0078] In a specific 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 for the above time, the pitch can be fully carbonized.

[0079] Step (5)

[0080] In step (5) of the method for preparing a porous carbon support according to the present invention, the porous carbon support can be obtained by activating the carbonized body. The porous carbon support can be obtained by forming pores in the pitch by activating the carbonized body (carbonized pitch).

[0081] In a specific embodiment of the present invention, activation of the carbonized body may be performed in an oxidizing gas atmosphere. In a preferred specific embodiment of the present invention, activation of the carbonized body may be performed in a water vapor atmosphere, but is not particularly limited thereto.

[0082] In a specific embodiment of the present invention, activation of the carbonized body may be performed at a temperature greater than 700° C. and less than or equal to 1,000° C., preferably at a temperature of 800° C. to 900° C. When activation of the carbonized body is performed at the above temperature, a porous carbon support having sufficiently formed micropores and mesopores may be obtained.

[0083] In a specific embodiment of the present invention, the activation of the carbonized body can be performed at a pressure of 0.1 to 10 bar, preferably 0.1 to 5 bar. When the carbonized body is activated at the above pressure, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0084] In a specific embodiment of the present invention, activation of the carbonized body can be performed under conditions of an oxidizing gas, preferably water vapor, at a flow rate of 0.1 ml / min to 100 ml / min, preferably 0.1 ml / min to 50 ml / min. When the carbonized body is activated under these oxidizing gas flow rates, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0085] In a specific embodiment of the present invention, the carbonized body can be activated for 0.5 to 5 hours, preferably 1 to 3 hours. If the carbonized body is activated for the above time, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0086] In a specific embodiment of the present invention, steps (4) and (5) can each be performed in a heating furnace using microwaves and / or plasma. In a preferred embodiment of the present invention, steps (4) and (5) can both be performed in a heating furnace using microwaves and / or plasma. A heating furnace using microwaves and / or plasma can increase the temperature of the asphalt pellets themselves without increasing the temperature of other parts of the heating furnace for the asphalt pellets.

[0087] In a specific embodiment of the present invention, steps (3) to (5) can be performed continuously in a single apparatus. In a preferred embodiment of the present invention, steps (3) to (5) can be performed continuously in a rotary kiln, but are not particularly limited to such an apparatus. By continuously performing the stabilization, carbonization, and activation of the asphalt pellets in a single apparatus, process optimization can be easily achieved.

[0088] In a specific embodiment of the present invention, the porous carbon support obtained in step (5) can be further crushed or ground and classified. The porous carbon support can be further subdivided by crushing or grinding, and the particle size distribution of the porous carbon support can be uniform by classification. Among them, as classification, dry classification, wet classification, or classification using a sieve can be used. By crushing or grinding and classification, a porous carbon support powder with an average diameter of 1 μm to 20 μm can be obtained.

[0089] In one embodiment of the present invention, the method for preparing the porous carbon support according to the present invention may further include a step of depositing silicon on the prepared porous carbon support.

[0090] At this time, the above-mentioned deposition can be performed at a temperature of 300° C. or higher and / or 600° C. or lower and in a silane (SiH4) gas atmosphere of 150 sccm or higher and / or 500 sccm or lower. The above-mentioned deposition can be achieved by, for example, chemical vapor deposition (CVD) and can be performed under atmospheric pressure conditions, but is not limited thereto. Through the above-mentioned deposition, silicon can be deposited on the surface and inside the pores of the porous carbon support according to the present invention.

[0091] The present invention also relates to a porous carbon support. The porous carbon support according to the present invention can be prepared by the above method.

[0092] In one example of the present invention, the ratio of the mesopore volume to the total pore volume of the porous carbon support according to the present invention may be 0.1 or more. The pores of the porous carbon support can be divided into micropores having a diameter of less than 2 nm, mesopores having a diameter of 2 nm to 50 nm, and macropores having a diameter of more than 50 nm according to their size. The above-mentioned porous support has been studied in the direction of increasing the ratio of micropores in order to increase the specific surface area or increasing the ratio of macropores in order to increase the amount of material loaded in the pores. However, when there are many micropores, silicon is difficult to deposit inside the pores, resulting in a problem of reduced capacitance. In addition, when there are many macropores, silicon agglomeration may occur, generating stress during repeated charge and discharge processes, which may mechanically damage the negative electrode material.

[0093] On the other hand, in the case of mesopores, silicon can be deposited sufficiently in the core of the pores. According to the present invention, the porous carbon support contains mesopores within a predetermined range, enabling sufficient silicon to be deposited inside the pores of the porous support.

[0094] The ratio of the mesopore volume to the total pore volume of the porous carbon support may be, but is not limited to, 0.10 or greater, 0.12 or greater, 0.14 or greater, or 0.15 or greater. The upper limit of the ratio of the mesopore volume to the total pore volume of the porous carbon support is not particularly limited, but may be, for example, 1.0 or less or less. When the ratio of the mesopore volume to the total pore volume of the porous carbon support satisfies the above range, the porous carbon support exhibits excellent electrical properties and can also prevent excessive aggregation of silicon, thereby preventing damage caused by volume expansion of silicon.

[0095] In an 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 PT-TD200 (Pharma Test). Specifically, 40 ml of the porous carbon support is placed in a graduated cylinder and the first volume is observed after vibrating 1000 times. After observation, the first volume is observed after vibrating 1000 times. This process is repeated 3 times until the volume is the same as the previous volume, and then the tap density can be calculated from 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, 0.60 g / ml or less, 0.55 g / ml or less, or may be 0.05 g / ml or more or 0.1 g / ml or more, but is not limited thereto. If the tap density of the porous carbon support is too low, it may be difficult to control the process during silane vapor deposition, resulting in a reduced yield. In addition, if the tap density of the porous carbon support is too high, it may be difficult to coat evenly during silane vapor deposition.

[0096] In one embodiment of the present invention, the BET specific surface area of the porous carbon support according to the present invention can be 300 m 2 / g and / or 3000m 2 / g or less. The BET specific surface area of the porous carbon carrier can be a value measured using ASAP 2420 (Micromeritics instrument (USA)). Specifically, the analysis was performed after vacuum drying at 300 ° C for 5 hours, and the BET equation and BJH equation can be used to calculate the BET specific surface area of the porous carbon carrier using the N2 / 77K isotherm adsorption results according to ISO9277. The BET specific surface area of the porous carbon carrier can be 300m 2 / g or above, 400m 2 / g or above, or 500m 2 / g or more, and can be 3000m 2 / g or less, 2800m 2 / g or less, 2600m 2 / g or less, or 2000m 2 / g or less, but not limited thereto. If the BET specific surface area of the porous carbon support is too low, the ratio of macropores may increase, resulting in a decrease in the mechanical strength of the negative electrode material and insufficient effective pores. In addition, if the BET specific surface area of the porous carbon support is too high, the ratio of micropores may increase, and silicon may not be sufficiently deposited in the core of the porous carbon support.

[0097] In an embodiment of the present invention, the diameter of the porous carbon support according to the present invention may be 20 μm or less. The above diameter may refer to the D50 diameter and may be a value measured using a MICROTRAC S3500 device. Specifically, it may refer to the average value obtained by dispersing the porous carbon support in ethanol and performing three particle size analyses. 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, or 12 μm or less, and may be 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more, but is not limited thereto. If the diameter of the porous carbon support is too small, the interior may be quickly filled with silicon during coating, and then additional coating may be performed on the surface, resulting in the formation of a thick surface coating. In this case, degradation may be accelerated during charge and discharge, and agglomeration between small particle materials may occur during electrode manufacturing, and the agglomerated portion may be significantly degraded. In addition, if the diameter of the porous carbon support is too large, it may be difficult for the silane gas to diffuse into the interior of the porous carbon support, making it difficult to form a uniform silicon coating inside the 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 when manufacturing the electrode, and thus the capacity uniformity may be reduced.

[0098] In one example, the porous carbon support according to the present invention may include macropores having a diameter exceeding 50 nm. In this case, the ratio of the macropore volume relative to the total pore volume of the porous carbon support may be 0.4 or less. The ratio of the macropore volume relative to the total pore volume of the porous carbon support may be 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, but is not limited thereto. There is no particular restriction on the lower limit of the ratio of the macropore volume relative to the total pore volume of the porous carbon support, but for example, it may be 0 or more or greater than 0. If the macropore ratio of the porous carbon support is too high, the mechanical strength of the negative electrode material made from the above-mentioned porous carbon support may be reduced. In addition, localized agglomeration of silicon may occur inside the negative electrode material, thereby generating stress due to volume expansion during repeated charge and discharge, resulting in damage to the negative electrode material.

[0099] In one embodiment, silicon can be disposed on the surface and within the pores of the porous carbon support according to the present invention. The silicon can be formed by deposition as described above. Since the porous carbon support according to the present invention has the above structure, the negative electrode material made from the porous carbon support according to the present invention can have a high capacitance while minimizing the effect of silicon volume expansion.

[0100] In another example, the content of the deposited silicon may be 10% by weight or more relative to the total weight of the particles. The content of the silicon may be a value obtained by analysis using an energy dispersive spectrometer (EDS). The content of the deposited silicon may be 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, or 30% by weight or more, but is not limited thereto. In addition, the content of the deposited silicon may be 60% by weight or less, 58% by weight or less, 56% by weight or less, 54% by weight or less, 52% by weight or less, or 50% by weight or less, but is not limited thereto. If the content of the deposited silicon is too low, the capacitance may decrease. In addition, if the silicon content is too high, the problem caused by the volume expansion of silicon during charge and discharge cannot be solved, which may cause structural damage to the negative electrode material and deteriorate the cycle characteristics.

[0101] The present invention also relates to a battery negative electrode material comprising the porous carbon support. The battery negative electrode material comprising the porous carbon support according to the present invention can have high capacity, excellent cycle characteristics and improved mechanical strength.

[0102] There are no particular limitations on the method for producing the battery negative electrode material, and conventional methods for producing battery negative electrode materials may be used. For example, the battery negative electrode material may be produced by mixing a porous carbon support, an active material, a conductive material, and a binder, and then coating, drying, and rolling the mixture onto a component such as an electrode current collector, but the present invention is not limited thereto.

[0103] The present invention also relates to a battery comprising the above-mentioned battery negative electrode material. The battery comprising the battery negative electrode material according to the present invention may be a lithium-ion battery or an all-solid-state battery, but is not limited thereto.

[0104] Specifically, the lithium-ion battery may include a positive electrode, a negative electrode, a separator and an electrolyte. In this case, the negative electrode may include the negative electrode material of the battery. The positive electrode may be made of materials that can be used for lithium-ion batteries. For example, it may include at least one positive electrode active material 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 an alloy thereof, but is not limited thereto. In addition, the separator may be a conventional separator that can be used for lithium-ion batteries. For example, the separator may include at least one selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene and polytetrafluoroethylene (PTFE), but is not limited thereto.

[0105] The negative electrode of the lithium-ion battery may include the negative electrode material. The negative electrode may include a negative electrode current collector and the negative electrode material. The negative electrode current collector may include at least one selected from aluminum, stainless steel, nickel, titanium, platinum, or alloys thereof, but is not limited thereto.

[0106] The electrolyte of the lithium-ion battery may include an organic liquid electrolyte, an inorganic liquid electrolyte, a polymer electrolyte, or a molten inorganic electrolyte that can be used in lithium-ion batteries, but is not limited thereto.

[0107] Specifically, the all-solid-state battery may include a positive electrode, a negative electrode, and a solid electrolyte, and may further include a separator as needed, but is not limited thereto. The positive electrode may include the positive electrode active material, and may include a positive electrode current collector as needed, but is not limited thereto.

[0108] 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.

[0109] The solid electrolyte may be any solid electrolyte that can be used in all-solid-state batteries. For example, the solid electrolyte may be at least one selected from the group consisting of garnet, Nasicon, Lisicon, perovskite, and LiPON, but is not limited thereto.

[0110] Hereinafter, preferred embodiments are provided to help understand the present invention. However, the following embodiments are provided only to help understand the present invention more easily, and the content of the present invention is not limited to the following embodiments.

[0111] Preparation Example 1: Preparation of porous carbon support

[0112] 300g of petroleum-based residual oil (YNCC, HTC PFO (pyrolysis fuel oil)) was placed in a reactor equipped with a stirrer and subjected to thermal decomposition and polycondensation at 450°C for 3 hours while nitrogen was supplied at a rate of 100ml / minute. The stirrer was rotated at 200rpm to mix the reactants. The polymerized asphalt was solidified and pelletized to produce solid asphalt pellets with a thickness of 3.0mm.

[0113] The solid asphalt pellets obtained above were placed in a rotary kiln and stabilized, carbonized, and activated using a plasma with an output power of 200 W. The stabilization, carbonization, and activation conditions are shown in Table 1 below.

[0114] The activated carbonized body after activation was pulverized using a pulverizer (Netsch, Air Jet Mill) to prepare a porous carbon support.

[0115] Table 1

[0116]

[0117] Preparation Example 2

[0118] A porous carbon support was prepared in the same manner as in Preparation Example 1, except that the thickness of the solid pitch particles was changed as shown in Table 2 below and microwaves with an output power of 800 W were used instead of plasma for heating in the stabilization step.

[0119] Preparation Example 3

[0120] A porous carbon support was prepared in the same manner as in Preparation Example 1, except that the thickness of the solid pitch particles was changed as shown in Table 2 below and a general electric furnace was used instead of plasma for heating in the stabilization step.

[0121] Preparation Example 4

[0122] The porous carbon support was prepared in the same manner as in Preparation Example 1, except that the prepared solid pitch particles were crushed to form a powder with a thickness of 200 μm and then heated using a general electric furnace instead of plasma in the stabilization step.

[0123] Table 2

[0124] Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 thickness 3.0mm 2.1mm 2.0mm 200μm

[0125] Table 3 below shows the results of measuring the physical properties of the prepared porous carbon support. The specific surface area of the porous carbon support was measured using a Belsorp mini II according to ASTM D4820-93. The tap density of the carbon support was measured using a tap density analyzer (Electrolab, ETD-1020x) according to ASTM B527. The average particle size of the carbon support was measured using a particle size analyzer (Horiba, laser particle size analyzer, LA-960V2) according to ASTM E112. The oxygen content and internal deviation were measured using the spectral profile of the SEM-EDS on a cross section of the pitch immediately after stabilization.

[0126] Table 3

[0127] Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Average particle size (μm) 10.22 7.20 10.45 9.21 <![CDATA[Specific surface area (m 2 / g)]]> 1285.9 944.2 254.6 1240.9 <![CDATA[Total pore volume (cm 3 / g)]]> 0.50 0.40 0.13 0.43 Tap density (g / ml) 0.41 0.52 0.61 0.59 Micropores (%) 42.1 72.9 53.3 72.8 Mesopore (%) 51.6 24.1 45.4 25.1 Average oxygen content (weight %) 17.3 15.6 4.7 18.8 Maximum deviation of oxygen content (weight %) 2.5 2.2 2.0 1.4 Oxygen content distribution deviation (%) 14.5 14.1 42.6 7.4

[0128] Figure 1 is an SEM image of the cross section of the asphalt immediately after stabilization in Preparation Example 1. Figure 2 This is an SEM image of the cross section of the asphalt immediately after stabilization in Preparation Example 3. Figure 1 and Figure 2 As shown, the oxygen content is determined by line profiling along a line passing through the center of a cross section of the asphalt.

[0129] In Table 3 above, the maximum deviation (a) of the oxygen content is the value of the oxygen content that differs most from the average oxygen content (M). For example, in the case of Preparation Example 1, the oxygen content in the cross section of the porous carbon support may be within the range of 17.3 ± 2.5, that is, within the range of 14.8 to 19.8. In this case, the distribution deviation of the oxygen content may be referred to as a percentage (|(14.8-17.3)| / 17.3).

[0130] Example 1: Preparation of carbon-silicon composite particles

[0131] Carbon-silicon composite particles were prepared using the porous carbon support prepared in Preparation Example 1. 15 to 20 g of the porous carbon support powder of Preparation Example 1 was added to a rotary kiln, and silane (SiH4) gas was injected to coat the porous carbon support.

[0132] The silane gas coating was carried out under normal pressure, at a temperature of 475° C., and at a flow rate of 300 sccm for 1 hour.

[0133] Example 2

[0134] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 2 was used.

[0135] Comparative Example 1

[0136] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 3 was used.

[0137] Comparative Example 1

[0138] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 4 was used.

[0139] Table 4

[0140]

[0141] Table 4 above shows the physical properties measured after silicon was deposited on the porous carbon support in Examples 1 and 2 and Comparative Example 1. In Comparative Example 1, the specific surface area was too low, making it difficult to form inward-facing pores, and therefore, silicon could not be coated inside the pores. Referring to Table 4, it can be seen that the silicon content in Examples 1 and 2 and Comparative Example 1 all exceeded 30% by weight. The above results confirm that by using the method for preparing a porous carbon support according to the present invention, composite particles with a sufficient amount of silicon deposited thereon can be prepared even without crushing solid pitch particles.

[0142] Experimental Example: Electrochemical Evaluation of Secondary Batteries

[0143] Semi-coin batteries were fabricated using the prepared carbon-silicon composite particles.

[0144] The carbon-silicon composite particles of the examples and comparative examples, the conductive material, and the binder were mixed at a ratio of 8:1:1 to prepare a slurry. Super-P was used as the conductive material, and a mixture of styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) at a weight ratio of 5:5 was used as the binder.

[0145] The slurry was evenly coated onto copper foil and preliminarily dried in an oven at 80°C for about 1 hour. After preliminarily drying, the slurry was roll-pressed and then preliminarily dried in a vacuum oven at 120°C for about 6 hours and 30 minutes to produce a negative electrode plate.

[0146] A half coin cell was fabricated using the above-prepared negative electrode plate and lithium foil as a counter electrode, and a porous polyethylene film as a separator under the conditions shown in Table 5 below.

[0147] The electrolyte was prepared by dissolving 1.3 M LiPF6 in a solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 3:5:2, and 10 wt% fluoroethylene carbonate (FEC), 0.2 wt% lithium tetrafluoroborate (LiBF4), 0.5 wt% vinylene carbonate (VC), and 1 wt% propane sultone (PS) were added as additives.

[0148] Table 5

[0149]

[0150] In Table 5 above, AM, CM, and BM represent active material (porous carbon support deposited with silane), conductor (Super P carbon black), and binder (styrene-butadiene rubber / carboxymethyl cellulose 5:5), respectively. EC, EMC, DMC, FEC, VC, and PS represent ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, fluoroethylene carbonate, vinylene carbonate, and propane sultone, respectively.

[0151] The electrochemical analysis of the fabricated half-coin cells was performed under the following conditions.

[0152] Cut-off voltage (V): 0.005–1.5 V (formation), 0.005–1.2 V (cycling)

[0153] Formation C rate (C): 0.1C for lithiation, 0.1C for delithiation

[0154] Cycle C rate (C): 0.5C lithiation, 0.5C delithiation

[0155] Table 6

[0156]

[0157] like Figure 3 As shown in the graph, the above charge and discharge capacity characteristics are measured by taking the capacity at the completion of charging as the charge capacity and the capacity at the start of discharging as the discharge capacity. The above ICE is the value of the discharge capacity divided by the charge capacity. Referring to Table 6 above, it can be seen that the half-button cell batteries manufactured using Examples 1 and 2 and the half-button cell batteries manufactured using Comparative Example 1 have almost the same level of performance in terms of the measurement results of charge capacity, discharge capacity and ICE. Examples 1 and 2 used porous carbon supports that were stabilized without crushing the solid asphalt particles in step (3), while Comparative Example 1 used a porous carbon support that was stabilized after crushing the solid asphalt particles using an existing preparation method. In view of the above, by using the method for preparing a porous carbon support according to the present invention, a porous carbon support with excellent pore characteristics can be prepared even if a separate crushing process is not performed on the solid asphalt particles. Thus, the process efficiency can be greatly improved by the method for preparing a porous carbon support according to the present invention.

[0158] Although the embodiments of the present invention have been described in detail above, the present invention is not limited by the above embodiments and the accompanying drawings, but is limited by the appended claims. Therefore, within the scope of the technical concept of the present invention described in the claims, a person skilled in the art may make various substitutions, modifications, and changes, which are also considered to fall within the scope of the present invention.

[0159] Industrial Applicability

[0160] The present invention can provide a method for manufacturing a porous carbon carrier, which includes the following steps: (1) thermally decomposing and polycondensing a petroleum-based raw material to form asphalt; (2) solidifying and granulating the asphalt to obtain solid asphalt particles; (3) stabilizing the solid asphalt particles without crushing them; and (4) carbonizing the stabilized asphalt particles to obtain a carbonized product.

Claims

1. A method for preparing a porous carbon support, comprising: (1) Thermal decomposition and polycondensation of petroleum-based raw materials to form asphalt; (2) solidifying and granulating the asphalt to obtain solid asphalt pellets; (3) stabilizing the solid asphalt pellets without crushing them; and (4) Carbonizing the stabilized asphalt particles to obtain a carbonized product.

2. The method according to claim 1, wherein The polycondensation temperature of the asphalt synthesis in step (1) is in the range of 350°C or higher and / or 500°C or lower.

3. The method according to claim 1, wherein The softening point of the asphalt synthesized in step (1) is above 200°C.

4. The method according to claim 1, wherein The thickness of the solid asphalt particles in step (3) is greater than 1 mm.

5. The method according to claim 1, wherein Step (3) comprises heating the uncomminuted solid asphalt particles to a temperature of 250° C. or higher and / or 400° C. or lower, wherein the heating is performed by microwaves or plasma.

6. The method according to claim 1, wherein The oxygen content of the asphalt pellets stabilized in step (3) is 10% by weight or more.

7. The method according to claim 1, wherein The distribution deviation of the oxygen content in the cross section of the asphalt particles stabilized in step (3) is 30% or less.

8. The method according to claim 1, wherein After step (4), the method further includes depositing silicon.

9. The method according to claim 8, wherein The deposition is performed at a temperature of 300° C. or higher and / or 600° C. or lower and in a silane (SiH 4 ) gas atmosphere of 50 sccm or higher and / or 500 sccm or lower.

10. The method according to claim 8, wherein The content of the deposited silicon is 10 wt% or more relative to the total weight of the porous carbon support. 11 . A porous carbon support, prepared by the method according to claim 1 .

12. A battery negative electrode material comprising the porous carbon support according to claim 11.

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