Method for manufacturing porous carbon support, porous carbon support manufactured thereby, carbon-silicon composite comprising same, and battery anode material comprising same

Abstract

The present invention may provide a method for manufacturing a porous carbon support, the method comprising: (1) a step for preparing a mixture by heating and mixing a premix including pitch and a polymer having a melting point below 300 °C; (2) a step for stabilizing the mixture; (3) a step for carbonizing the stabilized mixture to obtain a carbonized body; and (4) a step for activating the carbonized body.

Description

Method for producing a porous carbon support, a porous carbon support produced therefrom, a carbon-silicon composite comprising the same, and a battery negative electrode material comprising the same

[0001] The present invention relates to a method for producing a porous carbon support, a porous carbon support produced therefrom, a carbon-silicon composite comprising the same, and a battery negative electrode material comprising the same.

[0002] Carbon materials are materials made of carbon, one of the most abundant resources on Earth. Carbon materials are extremely lightweight, strong, and possess excellent electrical and thermal conductivity, making them a key material widely used in fields such as hydrogen vehicles, aviation, secondary batteries, and high-end consumer goods.

[0003] Carbon materials can be manufactured from various raw materials such as palm shell, polyacrylonitrile, rayon, and pitch. Among these, it is difficult to control the molecular weight and composition of carbon materials manufactured from solid raw materials such as palm shell (Republic of Korea Patent Application Publication No. 10-2019-0093960).

[0004] On the other hand, pitch, a viscoelastic solid polymer extracted from crude oil or plants, has the advantages of high yield when converted into carbon materials, low cost of raw materials, and its molecular structure is closer to the graphite structure than other raw materials, which can reduce the energy required for heat treatment (U.S. Patent Nos. 4,242,196 and 4,340,464).

[0005] Conventionally, a carbon precursor in pellet form was manufactured from such pitch, which was then pulverized into powder form and then subjected to a physical activation process to produce a porous carbon support. However, the physical activation method has a mechanism in which amorphous matter is oxidized prior to crystalline grains, and micropores develop first, followed by mesopores. As a result, the manufactured porous carbon support mainly contains micropores, and when chemical vapor deposition (CVD) or other processes are performed in subsequent processes, there is a problem in that deposition does not reach the deep pores well. Furthermore, excessive activation is required to increase mesopores in the porous carbon support, which causes a problem in that the yield is reduced.

[0006]

[0007] One of the several objects of the present invention is to provide a method for producing a porous carbon support having controlled pore characteristics so that sufficient deposition into deep pores can be achieved during chemical vapor deposition, and a porous carbon support produced thereby.

[0008] One of the several objects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having a high charge / discharge capacity and a porous carbon support produced therefrom.

[0009] One of the several objects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having improved cycle characteristics and a porous carbon support produced therefrom.

[0010] One of the several objects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having excellent mechanical properties and a porous carbon support produced therefrom.

[0011]

[0012] In one embodiment of the present invention, a method for producing a porous carbon support according to the present invention comprises the steps of: (1) mixing a mixture containing a pitch and a polymer having a melting point of less than 300°C while heating to produce a mixture;

[0013] (2) a step of stabilizing the mixture;

[0014] (3) a step of carbonizing the stabilized mixture to obtain a carbonized body; and

[0015] (4) A step of activating the above carbonized body;

[0016] In one embodiment of the present invention, the step (1) may be performed at a temperature of the softening point of the pitch to the softening point of the pitch + 50°C.

[0017] Additionally, the softening point of the above pitch may be within a range of 220°C or higher to 280°C or lower.

[0018] In one example of the present invention, the polymer may include at least one of a thermoplastic polymer and a water-soluble polymer.

[0019] Additionally, the weight average molecular weight of the polymer may be within the range of 5,000 to 2,000,000.

[0020] In one example of the present invention, the content of the polymer in step (1) of the method for producing a porous carbon support according to the present invention may be in the range of 0.5 wt% to 5 wt% with respect to the weight of the entire mixture.

[0021] In one example, the mixture of step (1) of the method for producing a porous carbon support according to the present invention may further include a catalyst.

[0022] At this time, the content of the catalyst may be in the range of 1 wt% to 10 wt% with respect to the weight of the entire mixture.

[0023]

[0024] Another embodiment of the present invention provides a method for producing a carbon-silicon composite, comprising the step of depositing silicon on a porous carbon support produced by the method for producing a porous carbon support described above.

[0025]

[0026] Another embodiment of the present invention provides a porous carbon support comprising medium pores having a diameter of 2 nm to 50 nm, a ratio of the volume of the medium pores to the volume of the total pores being 40% or more, and a specific surface area of ​​600 to 1800 m2 / g.

[0027] Additionally, the porous carbon support may have a total pore volume of 0.5 to 1.5 cm3 / g.

[0028] Additionally, the porous support may have an average particle size (D50) of 1 to 500 μm.

[0029]

[0030] In addition, the present invention provides a carbon-silicon composite comprising the porous carbon support described above and silicon formed on at least a portion of the surface and interior of the pores of the porous carbon support.

[0031]

[0032] Another embodiment of the present invention provides a battery negative electrode material comprising the porous carbon support described above.

[0033]

[0034] In addition, another embodiment of the present invention provides a battery negative electrode material comprising the carbon-silicon composite.

[0035] One of the many effects of the present invention is to provide a method for manufacturing a porous carbon support in which mesopores are formed in the outer portion and micropores are formed in the inner portion, so that silicon can be sufficiently deposited even in the inner pores, and a porous carbon support manufactured thereby.

[0036] One of the many effects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having a high charge / discharge capacity and a porous carbon support produced therefrom.

[0037] One of the many effects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having improved cycle characteristics and a porous carbon support produced therefrom.

[0038] One of the many effects of the present invention is to provide a method for producing a porous carbon support capable of producing a negative electrode material having excellent mechanical properties and a porous carbon support produced therefrom.

[0039] However, the various advantageous advantages and effects of the present invention are not limited to the above-described contents, and will be more easily understood in the process of explaining specific embodiments of the present invention.

[0040]

[0041] Figure 1 is an image of a cross-section taken after the mixture was solidified by heat mixing.

[0042] Figure 2 shows the results of pore distribution measurements for Manufacturing Example 1 and Comparative Manufacturing Example 1.

[0043]

[0044] Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and the attached drawings. It should be understood that the technology described herein is not limited to specific embodiments, but rather encompasses various modifications, equivalents, and / or alternatives of the embodiments of the present invention. In connection with the description of the drawings, similar reference numerals may be used for similar components.

[0045] And in order to clearly explain the present invention in the drawings, parts that are not related to the explanation are omitted, and the thickness is enlarged to clearly express several layers and areas, and components with the same function within the scope of the same idea can be explained using the same reference numerals.

[0046] In this specification, expressions such as “has”, “may have”, “includes”, or “may include” indicate the presence of a feature (e.g., a component such as a number, function, operation, or part), and do not exclude the presence of additional features.

[0047] In this specification, expressions such as "A or B," "at least one of A and / or B," or "one or more of A or / and B" can 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" can all refer to (1) including at least one A, (2) including at least one B, or (3) including both at least one A and at least one B.

[0048] All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification are to be understood as being modified in all cases by the term “about” unless otherwise stated.

[0049]

[0050] 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 comprises the steps of: (1) mixing a mixture containing a pitch and a polymer having a melting point of less than 300°C while heating to produce a mixture; (2) stabilizing the mixture; (3) carbonizing the stabilized mixture to obtain a carbonized body; and (4) activating the carbonized body.

[0051] The method for producing a porous carbon support according to the present invention comprises a polymer having a melting point of less than 300°C, thereby being able to be uniformly mixed with pitch as described below, and producing a porous carbon support with sufficiently developed pores.

[0052]

[0053] Hereinafter, each step of the present invention will be described in detail.

[0054]

[0055] Step (1)

[0056] Step (1) of the method for producing a porous carbon support according to the present invention may be a step of producing a mixture by mixing a mixture containing pitch and a polymer having a temperature of less than 300°C while heating.

[0057] The above pitch may be synthesized by thermal decomposition and polycondensation of a petroleum-based raw material. In a specific embodiment of the present invention, the petroleum-based raw material may include at least one selected from the group consisting of thermal cracking fuel oil (PFO), naphtha cracking residue (NCB), ethylene cracker bottom oil (EBO), vacuum residue (VR), de-asphalted oil (DAO), atmospheric residue (AR), fluidized bed catalytic cracking (RFCC-DO), residue fluid catalytic cracking decant oil (RFCC-DO), and heavy aromatic oil. In a preferred specific embodiment of the present invention, the petroleum-based raw material may include thermal cracking fuel oil.

[0058] In a specific embodiment of the present invention, the softening point of the pitch may be 200°C or higher. Since the pitch has a high softening point, when 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. The upper limit of the softening point of the pitch may be, for example, 350°C or lower, 330°C or lower, or 300°C or lower, and preferably, the softening point of the pitch is 220°C to 280°C, which may be more advantageous in achieving the purpose of the present invention.

[0059] In a specific embodiment of the present invention, the polymer may have a melting point below 300°C. The polymer may form pores as it decomposes during the carbonization process of the porous carbon support. This may help form pores before the activation process and help form pores internally during the activation process. The polymer may be a component that is thermally decomposed and removed during the stabilization and carbonization processes described below. The polymer must be uniformly mixed with the pitch to ensure uniform pore formation. If the polymer is unevenly mixed, the pore size may become excessively large, resulting in a carbon support that is not structurally sound and is easily broken. Conventional methods for manufacturing porous carbon supports have sometimes included polymer compounds as additives. Conventional polymer compounds were used in powder form, and high-melting-point components were used to prevent thermal decomposition prior to carbonization. In contrast, the inventors of the present invention have discovered that using a polymer with a melting point below 300°C can effectively develop mesopores. The method for manufacturing a porous carbon support according to the present invention can achieve uniform mixing of pitch and the polymer through step (1) using a polymer having a melting point of less than 300°C.

[0060] The melting point of the polymer may be less than 300°C, 295°C or less, 290°C or less, 285°C or less, or 280°C or less, and the lower limit is not particularly limited, but may be, for example, 100°C or more. The method for producing a porous carbon support according to the present invention uses a polymer having a melting point within the above range mixed with pitch, thereby uniformly mixing the pitch and the polymer, and producing a porous carbon support having a high mesoporous ratio.

[0061] In one example of the present invention, the polymer of the method for producing a porous carbon support according to the present invention may include at least one of a thermoplastic polymer and a water-soluble polymer. Since the polymer of the method for producing a porous carbon support according to the present invention includes at least one of a thermoplastic polymer and a water-soluble polymer, the pitch and the polymer can be mixed more uniformly.

[0062] Specific examples of the thermoplastic polymer include, but are not limited to, one or more selected from the group consisting of polyolefin, polyester, polyamide, polyurethane, polyurea, poly(vinyl halide), poly(vinylidene halide), polystyrene, poly(vinyl ester), polycarbonate chain, polyether, polysulfide, polyimide, polysilane, polysiloxane, polycaprolactam, polyacrylate, and polymethacrylate.

[0063] In addition, specific examples of the water-soluble polymer include, but are not limited to, one or more selected from the group consisting of dextrin, cyclodextrin, mannitol, lactose, hydroxypropylcellulose, methylcellulose, starch, protein, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, water-soluble photosensitizing resin, sulfonated polyisoprene, and sulfonated polyisoprene copolymer.

[0064] In one example, in the method for producing a porous carbon support according to the present invention, the weight average molecular weight of the polymer may be in the range of 5,000 to 2,000,000. When the weight average molecular weight of the polymer satisfies the above range, uniform thermal mixing with the pitch may be possible. When the weight average molecular weight of the polymer is too large, uneven mixing with the pitch may occur, which may result in uneven pore formation and excessively large pores.

[0065] In one embodiment of the present invention, the content of the polymer in step (1) of the method for producing a porous carbon support according to the present invention may be in the range of 0.5 wt% to 5 wt% based on the weight of the total mixture. If the content of the polymer mixed with the pitch in step (1) is too low, pores may not be sufficiently formed and non-uniform pores may be formed. In addition, if the content of the carbon precursor polymer is too high, pores may grow excessively or there may be limitations in the development of the carbon structure, which may cause a decrease in yield and specific surface area. In addition, in this case, the characteristics of the manufactured battery may deteriorate.

[0066] In one example of the present invention, step (1) of the method for producing a porous carbon support according to the present invention can be performed at a temperature of the softening point of the pitch to the softening point of the pitch + 50°C. The temperature of step (1) may be a temperature higher than the melting point of the polymer described above. Conventional manufacturing methods that use polymer additives in pitch have used various methods to evenly disperse the polymer additives in the pitch. Since the dispersibility of powder particles is greatly affected by the size of the particles or the properties of the solvent, in the past, it was necessary to use polymer additives having a diameter within a predetermined range. In contrast, step (1) of the method for producing a porous carbon support according to the present invention can be performed at a temperature higher than the softening point of the pitch and the melting point of the polymer, and can induce uniform mixing between the pitch having fluidity and the polymer in a molten state.

[0067] In one example, the mixture of step (1) of the porous carbon support according to the present invention may further comprise a catalyst. The catalyst may comprise, for example, a metal chloride or a metal carbonate.

[0068] The metal of the metal chloride additive may include, but is not limited to, one or more selected from the group consisting of transition metals, alkali metals, alkaline earth metals, and noble metals. If the mixture in step (1) of the method for producing a porous carbon support according to the present invention further includes a catalyst, the activation rate of the carbon material in the carbonization process can be increased. In addition, if the catalyst is included, pore formation can be promoted in the carbonization process without adding other additives.

[0069] The above transition metal may be at least one selected from nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), titanium (Ti), iron (Fe), and manganese (Mn), and the above alkali metal may be at least one selected from the group consisting of lithium (Li), sodium (Na), and cesium (Cs), but is not limited thereto. In addition, the above alkaline earth metal may be at least one selected from magnesium (Mg), calcium (Ca), and strontium (Sr), and the above noble metal may be at least one selected from gold (Au), platinum (Pt), and silver (Ag), but is not limited thereto.

[0070] In the above example, when the mixture in step (1) further includes a catalyst, the content thereof may be in the range of 1 wt% to 10 wt% based on the weight of the entire mixture. If the amount of catalyst included in the mixture in step (1) of the method for producing a porous carbon support according to the present invention is too small, it may not be uniformly distributed, resulting in uneven pore formation or difficulty in forming mesopores. In addition, if the amount of the catalyst is too large, excessive pore formation may occur, and there may be a problem of generating a large amount of chlorine gas.

[0071] In one example of the present invention, in the method for producing a porous carbon support according to the present invention, the mixture produced in step (1) may be pellets in which the pitch and polymer mixed while heating are solidified and pelletized. The pitch and polymer mixed while heating may be solidified, for example, by extrusion and cooling, and the solid pellets may be produced by pelletizing the solid pellets. The process of obtaining solid pellets by extrusion, cooling, and pelletizing may be performed using commercially available equipment. For example, this process may be performed using a double belt cooler & flaker manufactured by IPCO, but is not particularly limited to this equipment.

[0072] At this time, if the mixture is the pellet, the pellet may have an average particle size of 3 to 30 mm, preferably 5 to 25 mm. When the average particle size of the pellet is within this range, a porous carbon support can be manufactured through stabilization, carbonization, and activation described below without separately pulverizing the pellet. Therefore, a porous carbon support having controlled pore characteristics can be provided while improving the product yield through a simple process.

[0073]

[0074] Step (2)

[0075] Step (2) of the method for producing a porous carbon support according to the present invention may be a step of stabilizing the mixture produced in step (1). Specifically, step (2) may be a step of stabilizing the structure of the pitch by first oxidizing the mixture.

[0076]

[0077] In one example of the present invention, the stabilization can be performed at a temperature of 250°C to 400°C. The lower limit of the stabilization temperature can be 250°C or higher, 260°C or higher, 270°C or higher, or 280°C or higher, and the upper limit can be 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, but is not limited thereto. When the stabilization temperature satisfies the above range, the carbon structure within the pitch changes from thermoplastic to thermosetting, and the structure can be stably maintained during a subsequent carbonization process.

[0078] In a specific embodiment of the present invention, the stabilization may be performed at a pressure of 0.1 to 10 bar, preferably 0.5 to 5 bar. When the stabilization is performed at this pressure, the structure of the carbon within the mixture can be sufficiently stabilized.

[0079] In a specific embodiment of the present invention, the stabilization may be performed under conditions of a flow rate of an oxidizing gas, preferably air, of 0.1 to 500 ml / min, preferably 1 to 300 ml / min. When the stabilization is performed under these oxidizing gas flow rates, the structure of the carbon within the mixture may be sufficiently stabilized.

[0080] In a specific embodiment of the present invention, the stabilization may be performed for 1 to 10 hours, preferably 2 to 8 hours. If the stabilization is performed for this period of time, the structure of the carbon within the mixture may be sufficiently stabilized.

[0081]

[0082] Step (3)

[0083] Step (3) of the method for manufacturing a porous carbon support according to the present invention may be a step of carbonizing a stabilized mixture to obtain a carbonized body. Through carbonization of the mixture, other functional groups included in the pitch are removed, and a carbonized body composed of substantially pure carbon can be obtained.

[0084] In a specific embodiment of the present invention, the carbonization may be performed under an inert gas atmosphere. In a preferred embodiment of the present invention, the carbonization may be performed under a nitrogen or argon atmosphere, but is not particularly limited thereto.

[0085] In a specific embodiment of the present invention, the carbonization may be performed at a temperature of more than 700°C and less than or equal to 1,000°C, preferably 800 to 900°C. If the temperature during the carbonization is lower than this range, carbonization may not be sufficiently performed, and if the temperature during the carbonization is higher than this range, the carbonization yield may decrease.

[0086] In a specific embodiment of the present invention, the carbonization may be performed under a flow rate condition of an inert gas, preferably nitrogen, of 0.1 to 30 ml / min, preferably 0.1 to 10 ml / min. When the carbonization is performed under these inert gas flow rates, the mixture can be sufficiently carbonized.

[0087] In a specific embodiment of the present invention, the carbonization may be performed for 0.5 to 5 hours, preferably 1 to 3 hours. If the carbonization is performed for this period of time, the mixture can be sufficiently carbonized.

[0088]

[0089] Step (4)

[0090] The method for manufacturing a porous carbon support according to the present invention includes a step (4) of activating the carbonized body manufactured in step (3). In step (4), the carbonized body is activated to obtain a porous carbon support. By activating the carbonized body (carbonized mixture), pores are formed in the carbonized body, thereby obtaining a porous carbon support.

[0091] In a specific embodiment of the present invention, the activation of the carbonized body may be performed in an oxidizing gas atmosphere. In a preferred embodiment of the present invention, the activation of the carbonized body may be performed in a steam atmosphere, but is not particularly limited thereto.

[0092] In a specific example of the present invention, the activation of the carbonized body can be performed at a temperature of more than 700°C and less than or equal to 1,000°C, preferably 800 to 900°C. When the activation of the carbonized body is performed at this temperature, a porous carbon support in which mesopores are sufficiently formed can be obtained.

[0093] 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 activation of the carbonized body is performed at this pressure, a porous carbon support in which micropores and mesopores are sufficiently formed can be obtained.

[0094] In a specific embodiment of the present invention, the activation of the carbonized body can be performed under conditions of a flow rate of an oxidizing gas, preferably water vapor, of 0.1 to 100 ml / min, preferably 0.1 to 50 ml / min. When the activation of the carbonized body is performed under these oxidizing gas flow rates, a porous carbon support in which micropores and mesopores are sufficiently formed can be obtained.

[0095] In a specific embodiment of the present invention, the activation of the carbonized body may be performed for 0.5 to 5 hours, preferably 1 to 3 hours. When the activation of the carbonized body is performed for this period of time, a porous carbon support in which micropores and mesopores are sufficiently formed can be obtained.

[0096]

[0097] In a specific embodiment of the present invention, steps (2) to (4) above can be performed continuously in a single device. In a preferred embodiment of the present invention, steps (2) to (4) above can be performed continuously in a single rotary kiln, but this device is not particularly limited. Since the above-described stabilization, carbonization, and activation are performed continuously in a single device, process optimization can be easily achieved.

[0098]

[0099] In a specific embodiment of the present invention, the porous carbon support obtained in step (4) may be further pulverized or ground and classified. Through pulverization or grounding, the porous carbon support can be further finely divided, and through classification, the particle size distribution of the porous carbon support can be made uniform. Here, classification may be dry classification, wet classification, or classification using a sieve. Through pulverization or grounding and classification, a porous carbon support powder having an average particle size (D50) of 1 to 500 μm can be obtained.

[0100]

[0101] In addition, the present invention provides a method for producing a carbon-silicon composite, including a step of depositing silicon on a porous carbon substrate produced by the method for producing a porous carbon substrate described above.

[0102] At this time, the deposition may be performed at a temperature of 300°C to 600°C and under a silane (SiH4) gas atmosphere of 150 sccm to 500 sccm. The deposition may utilize, for example, chemical vapor deposition (CVD) and may be performed 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.

[0103]

[0104] The present invention also relates to a porous carbon support. The porous carbon support according to the present invention may be manufactured by the method described above.

[0105]

[0106] In one example of the present invention, the porous carbon support according to the present invention includes medium pores having a diameter of 2 nm to 50 nm, and the ratio of the volume of the medium pores to the volume of the total pores is 40% or more.

[0107] The pores of the porous carbon support can be classified into micropores with a diameter of less than 2 nm, medium pores with a diameter of 2 to 50 nm, and macropores with a diameter of more than 50 nm, depending on their size. These porous supports have been studied in the direction of increasing the ratio of micropores to increase the specific surface area or increasing the ratio of macropores to increase the amount of material supported inside the pores. However, when there are many micropores, there is a problem that the electrical capacity is reduced because it is difficult for silicon to be deposited inside the pores. In addition, when there are many macropores, silicon agglomeration occurs, which can generate stress during repeated charge / discharge processes, which can mechanically damage the negative electrode material.

[0108] On the other hand, in the case of medium pores, silicon can be sufficiently deposited deep within the pores during deposition. The porous carbon support according to the present invention can deposit a sufficient amount of silicon within the pores of the porous support by including medium pores within a predetermined range.

[0109] The porous carbon support may have a ratio of the volume of mesopores to the volume of the total pores of 40% or more, preferably 41% or more, and more preferably 42% or more. In addition, the upper limit of the ratio of mesopores to the total pores of the porous carbon support may be 100% or less, preferably less than 100%, more preferably 90% or less, even more preferably 80% or less, and even more preferably 60% or less. When the ratio of mesopores to the total pores of the porous carbon support satisfies the above range, it is possible to have excellent electrical properties while preventing excessive aggregation of silicon and thus preventing damage due to volume expansion of silicon.

[0110] In addition, the porous carbon support according to the present invention has a BET specific surface area of ​​600 to 1800 m 2 / g is.

[0111] At this time, the BET specific surface area of ​​the porous carbon support may be a value measured using ASAP 2420 (Micromeritics instrument (USA)). Specifically, analysis can be performed after vacuum drying at 300°C for 5 hours, and the results of N2 / 77K Isotherm adsorption according to ISO9277 can be calculated using the BET equation and the BJH equation.

[0112] The BET specific surface area of ​​the porous carbon support may be 600 m2 / g or more, preferably 650 m2 / g or more, more preferably 700 m2 / g or more, and even more preferably 750 m2 / g or more, and the upper limit of the BET specific surface area range of the porous carbon support may be 1800 m2 / g or less, preferably 1770 m2 / g or less, more preferably 1740 m2 / g or less, and even more preferably 1700 m2 / g or less. When the BET specific surface area of ​​the porous carbon support is below the range, the proportion of macropores may increase, which may lower the mechanical strength of the negative electrode material, and there may be insufficient effective pores. In addition, when the BET specific surface area of ​​the porous carbon support exceeds the range, the proportion of micropores may increase, and silicon may not be sufficiently deposited deep into the porous carbon support.

[0113] In one embodiment of the present invention, the total pore volume of the porous carbon support according to the present invention may be 0.5 to 1.5 cm3 / g, preferably 0.51 to 1.5 cm3 / g. Accordingly, it may be more advantageous in achieving the purpose of the present invention.

[0114] 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 PT-TD200 (Pharma Test). Specifically, 40 ml of the porous carbon support is loaded into a cylinder, tapped 1,000 times, and the primary volume is observed. After the observation, tapping is performed again 1,000 times and the volume is observed. This process is repeated three times until there is no difference from the previous volume, and then 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, and 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, process control during silane gas deposition may be difficult, resulting in a decrease in yield. Additionally, if the tap density of the porous carbon support is too high, uniform coating may be difficult to achieve during silane gas deposition.

[0115] In one embodiment of the present invention, the average particle size (D50) of the porous carbon support according to the present invention may be 1 to 500 μm. The average particle size may refer to a particle size distribution D50, and may be a value measured using a MICROTRAC S3500 device. Specifically, it may refer to an average value obtained by dispersing the porous carbon support in ethanol and then performing particle size analysis three times. The average particle size of the porous carbon support may be 1 to 500 μm, preferably 1 to 100 μm, more preferably 1 to 20 μm, more preferably 1 to 18 μm, still more preferably 2 to 16 μm, still more preferably 2 to 14 μm, still more preferably 3 to 12 μm, and most preferably 3 to 10 μm. If the average particle size of the porous carbon support is below the range, when performing silicon coating, silicon may be quickly filled inside and then additional coating may be performed on the surface, resulting in a thick surface coating layer. In this case, deterioration may be accelerated during charge and discharge, and when manufacturing an electrode, materials with small particle sizes may coagulate with each other, and deterioration of the coagulated portion may be significant. In addition, if the average particle size of the porous carbon support exceeds the range, diffusion of silane gas into the interior of the porous carbon support may be difficult, making it difficult to form a uniform silicon coating layer inside the support. In addition, uniform coating of the slurry on the current collector during electrode manufacturing may be difficult, resulting in a decrease in capacity uniformity.

[0116] 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 volume of the macropores to the total pore volume of the porous carbon support may be 0.4 (40%) or less. The ratio of the volume of the macropores to the total pore volume of the porous carbon support may be 0.40 (40%) or less, 0.38 (38%) or less, 0.36 (36%) or less, 0.34 (34%) or less, 0.32 (32%) or less, or 0.30 (30%) or less, but is not limited thereto. The lower limit of the ratio of the volume of the macropores to the total pore volume of the porous carbon support is not particularly limited, but may be, for example, 0% or more or greater than 0%. If the macropore ratio of 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 silicon agglomeration may occur within the anode material, generating stress due to volume expansion during repeated charge / discharge cycles, potentially damaging the anode material.

[0117]

[0118] In addition, the present invention provides a carbon-silicon composite comprising the porous carbon support described above and silicon formed on at least a portion of the surface and interior of the pores of the porous carbon support.

[0119] The above silicon may be formed by deposition. Since the porous carbon support according to the present invention has the above structure, the negative electrode material manufactured from the porous carbon support according to the present invention and / or the carbon-silicon composite can have high electrical capacity while minimizing the influence due to volume expansion of silicon.

[0120] In another example, the content of the deposited silicon may be 10 wt% or more based on the weight of the total particle. The content of the silicon may be a value obtained by analysis using an energy dispersive spectrometer (EDS). The lower limit of the content of the deposited silicon may be 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, or 30 wt% or more, but is not limited thereto. Preferably, the lower limit of the content of the deposited silicon may be 36 wt% or more, and more preferably, 41 wt% or more. In addition, the upper limit of the content of the deposited silicon may be 60 wt% or less, 59 wt% or less, 58 wt% or less, or 57 wt% or less, but is not limited thereto. If the content of the deposited silicon is too low, the electrical capacity may be reduced. In addition, if the silicon content is too large, the problem caused by the volume expansion of silicon during charge and discharge may not be resolved, which may cause structural damage to the negative electrode material and deteriorate the cycle characteristics.

[0121]

[0122] The present invention also relates to a battery negative electrode material comprising the porous carbon support described above. The battery negative electrode material comprising the porous carbon support according to the present invention can have improved mechanical strength along with high electrical capacity and excellent cycle characteristics.

[0123] Furthermore, the present invention relates to a battery negative electrode material comprising the carbon-silicon composite. The battery negative electrode material comprising the carbon-silicon composite according to the present invention can have improved mechanical strength along with high electrical capacity and excellent cycle characteristics.

[0124] The method for manufacturing the above-mentioned battery negative electrode material is not particularly limited, and a general method for manufacturing a battery negative electrode material can be used. For example, the above-mentioned battery negative electrode 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 component such as an electrode current collector, but is not limited thereto.

[0125] The present invention also relates to a battery comprising the aforementioned battery negative electrode material. A 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.

[0126] The lithium ion battery may specifically include a positive electrode, a negative electrode, a separator, and an electrolyte. At this time, the negative electrode may include the above-described battery negative electrode material. The positive electrode may use a material usable in a lithium ion battery, and may include, for example, 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 an alloy thereof, but is not limited thereto. In addition, the separator may use a typical separator usable in a lithium ion battery. The separator may include, for example, one or more selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE), but is not limited thereto.

[0127] 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 aluminum, stainless steel, nickel, titanium, platinum, or an alloy thereof, but is not limited thereto.

[0128] The electrolyte of the above 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 usable in a lithium ion battery.

[0129] The above-mentioned all-solid-state battery may specifically 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 above-mentioned positive electrode active material, and may include a positive electrode current collector as needed, but is not limited thereto.

[0130] The above negative electrode may include a 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.

[0131] The solid electrolyte may optionally use a solid electrolyte usable in an all-solid-state battery. The solid electrolyte may be, for example, at least one selected from the group consisting of a Garnet-type, a Nasicon-type, a LISICON-type, a perovskite-type, and a LiPON-type, but is not limited thereto.

[0132]

[0133] Hereinafter, preferred examples are presented to aid in understanding the present invention. However, the following examples are provided solely to facilitate a better understanding of the present invention, and the scope of the present invention is not limited by the following examples.

[0134]

[0135] Manufacturing Examples 1 and 2: Manufacturing of a porous carbon support

[0136] 300 g of petroleum residue oil (YNCC, HTC PFO (pyrolysis fuel oil)) was placed in a reactor equipped with a stirrer, and pyrolysis and polycondensation were performed at 450°C for 3 hours while supplying nitrogen at a flow rate of 100 ml / min. During this time, the stirrer was rotated at a speed of 200 rpm to mix the reactants. The polymerized pitch was solidified and pelletized to obtain solid pitch pellets with a particle size of 1 to 30 mm.

[0137] To the solid pitch pellets obtained above, 1 wt% (Preparation Example 1) and 5 wt% (Preparation Example 2) of CMC (carboxymethyl cellulose) as a polymer were added, and then the temperature was increased at a rate of 2 °C / min to 260 °C, which is the softening point temperature of the pitch, and then mixed at 300 rpm for 4 hours. In addition, to prevent oxidation, thermal mixing was performed while supplying nitrogen at 2 L / min.

[0138] Figure 1 is an image of a cross-section of a mixture solidified after heat mixing. Referring to Figure 1, it can be confirmed that the pitch and polymer are evenly mixed.

[0139] The manufactured mixture was crushed to a size of 200 μm or less and then placed in a rotary kiln to sequentially perform stabilization, carbonization, and activation. The stabilization process was carried out by heating to 310 ℃ at a rate of 2 ℃ / min in an air atmosphere and then maintaining it for 2 hours. The carbonization and activation processes were carried out by heating to 700 ℃ at a rate of 10 ℃ / min in a nitrogen atmosphere and maintaining it for 1 hour (carbonization), then increasing the temperature to 950 ℃ at a rate of 10 ℃ / min, and then switching to a steam atmosphere and maintaining it for 1 hour (activation).

[0140] The activated carbonized body, which was activated above, was pulverized using a pulverizer (NETZSCH, air jet mill) to produce a porous carbon support.

[0141]

[0142] Manufacturing Example 3

[0143] A porous carbon support was manufactured in the same manner as in Manufacturing Examples 1 and 2, except that 1 wt% of PVA (polyvinyl alcohol) was added as the polymer.

[0144]

[0145] Comparative Manufacturing Example 1

[0146] A porous carbon support was manufactured in the same manner as in Manufacturing Examples 1 and 2, except that no polymer was added.

[0147]

[0148] Comparative Manufacturing Example 2

[0149] A porous carbon support was manufactured in the same manner as in Manufacturing Examples 1 and 2, except that no polymer was added and the holding time in the activation process was increased to 2 hours.

[0150]

[0151] Experimental Example 1: Measurement of physical properties of porous carbon supports

[0152] Tables 1 and 2 below show the measured physical properties of the manufactured porous carbon supports. The specific surface area of ​​the porous carbon supports was measured using a Belsorp mini II according to ASTM D4820-93. The tap density of the carbon supports was measured using a tap density analyzer (Electrolab, ETD-1020x) according to ASTM B527. The average particle size of the carbon supports was measured using a particle size analyzer (Horiba, Laser Particle Analyzer, LA-960V2) according to ASTM E112.

[0153] Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Specific surface area (m 2 / g)12201620860Total pore volume (cm) 3 / g)0.641.060.51Microscopic volume (cm) 3 / g)0.370.390.22 Medium-term pore volume (cm) 3 / g)0.270.370.29Porosity ratio(%)42.248.656.9Yield(wt%)40.732.448.7

[0154] Comparative Manufacturing Example 1 Comparative Manufacturing Example 2 Specific surface area (m 2 / g)10701970Total pore volume (cm) 3 / g)0.491.03 Microscopic volume (cm) 3 / g)0.370.55 Medium-term pore volume (cm) 3 / g)0.120.48Porosity ratio(%)24.546.6Yield(wt%)51.722.0

[0155] Referring to Tables 1 and 2 above, it can be confirmed that Manufacturing Examples 1 to 3 have a mesopore ratio of 40% or more and a yield of 30 wt% or more. On the other hand, Comparative Manufacturing Example 1 showed a mesopore ratio of 24.5%, which is significantly lower than Manufacturing Examples 1 to 3, and Comparative Manufacturing Example 2 showed a mesopore ratio of 46.6% but a yield of 22.0 wt%, which can be seen to show a lower mesopore ratio or yield than Manufacturing Examples 1 to 3.

[0156] Figure 2 shows the results of pore distribution measurements for Manufacturing Example 1 and Comparative Manufacturing Example 1. Referring to Figure 2, it can be confirmed that Comparative Manufacturing Example 1 has fewer pores with a size of 2 nm to 50 nm compared to Manufacturing Example 1.

[0157]

[0158] Example 1: Preparation of carbon-silicon composite particles

[0159] Carbon-silicon composite particles were manufactured using the porous carbon support manufactured in Manufacturing Example 1. 15 g of the porous carbon support was placed in a rotary kiln, and silane (SiH4) gas was injected to deposit the porous carbon support.

[0160] During silane gas coating, the pressure was at atmospheric pressure, and deposition was performed for 60 minutes at a temperature of 475°C and a flow rate of 300 sccm to manufacture carbon-silicon composite particles.

[0161]

[0162] Comparative Example 1

[0163] Carbon-silicon composite particles were manufactured in the same manner as in Example 1, except that the porous carbon support manufactured in Comparative Manufacturing Example 1 was used.

[0164]

[0165] Comparative Example 2

[0166] Carbon-silicon composite particles were manufactured in the same manner as in Example 1, except that the porous carbon support manufactured in Comparative Manufacturing Example 2 was used.

[0167]

[0168] Example 1 Comparative Example 1 Comparative Example 2 Average particle size (μm) 7.8 10.15.7 Specific surface area (m 2 / g)7.58.9615.4Tap density (g / ml)0.70.60.5Silicon content (wt%)574035

[0169] Referring to Table 3 above, it can be seen that Example 1 has a lower specific surface area than Comparative Examples 1 and 2, and thus the silicon formation within the pores of the porous carbon support is significantly superior.

[0170] In particular, the specific surface area of ​​Example 1 is about 1.2% compared to the specific surface area of ​​Comparative Example 2, and it can be seen that the carbon-silicon composite particles of Example 1 have significantly superior silicon formation properties within the pores of the porous carbon support compared to the carbon-silicon composite particles of Comparative Example 2.

[0171] Additionally, it can be seen that Example 1 has a higher silicon content than Comparative Examples 1 and 2.

[0172] At this time, Comparative Example 1 has a surface area difference of 1.4 m compared to Example 1 despite having a low silicon content. 2 / g is not large, which can be seen as a phenomenon in which silicon is not well deposited inside the comparative example 1 and is deposited only in the external pores. As a result, the silicon conversion rate of the silane gas is also lowered, or the silicon content within the particle is reduced due to the agglomeration of particles as they are formed into silicon lumps.

[0173] In addition, Comparative Example 2 had a relatively large number of pores in the support compared to Example 1, which prevented silicon from being deposited entirely, resulting in a low silicon deposition amount, and thus a relatively large specific surface area.

[0174]

[0175] Experimental Example 2: Electrochemical Evaluation of Secondary Batteries

[0176] Half coin cells were manufactured using each of the carbon-silicon composites manufactured in Example 1, Comparative Example 1, and Comparative Example 2.

[0177] Carbon-silicon composite: Conductive material: Binder was mixed in a ratio of 8:1:1 to prepare a slurry. At this time, the conductive material used was super-P, and the binder used was a mixture of styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) in a weight ratio of 5:5.

[0178] Next, the slurry was uniformly applied to copper foil and dried in an 80°C oven for approximately 1 hour. After the primary drying, the slurry was roll-pressed and dried in a 120°C vacuum oven for approximately 6 hours and 30 minutes to manufacture a negative electrode plate.

[0179] A half coin cell was manufactured using the above-mentioned negative electrode and lithium foil as a counter electrode. A porous polyethylene film was used as a separator, and a CR2032 half coin cell (half cell) was manufactured under the conditions shown in Table 5 below.

[0180] The electrolyte was prepared by dissolving 1.3 M LiPF6 in a solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:5:2, and dissolving 10 wt% fluoro-ethylene carbonate (FEC), 0.2 wt% lithium tetrafluoroborate (LiBF4), 0.5 wt% vinylene carbonate (VC), and 1 wt% propane sulton (PS) additives (see Table 4).

[0181] Composition (AM:CM:BM) 8:1:1 Area capacity (mAh / cm 2 )1 Electrolyte 1.3M LiPF6 EC / EMC / DMC 3:5:2, FFC 10%, LiBF4 0.2%, 0.5% VC, 1% PS Cut-off voltage (V) Formation: 0.005 ~ 1.5, Cycle test: 0.005 ~ 1.5 C-rate (C) Formation: 0.1 ~ 0.1. 0.01 C cut-off (CV) at 0.005 V

[0182] In Table 4 above, AM, CM, and BM represent active material (carbon-silicon composite particles), 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.

[0183] Electrochemical analysis was performed on the manufactured half coin cell under the following conditions.

[0184] Cut off voltage (V): 0.005 - 1.5V (Formation), 0.005 - 1.2V(Cycle)

[0185] Formation C-rate (C): 0.1C lithiation, 0.1C delithiation

[0186] Cycle C-rate (C): 0.5C lithiation, 0.5C delithiation

[0187] The results are shown in Table 5 and Fig. 3.

[0188] Charge capacity (mAh / g)Discharge capacity (mAh / g)ICE (%)Example 12264205991Comparative example 12015176187Comparative example 21789148883

[0189] Referring to Table 5, it can be seen that Example 1 using the porous carbon support according to Manufacturing Example 1 has significantly superior charge and discharge capacities compared to Comparative Example 1 using the porous carbon support according to Comparative Manufacturing Example 1 and Comparative Example 2 using the porous carbon support according to Comparative Manufacturing Example 2.

[0190] In particular, Example 1 showed a high capacity and high ICE due to the high silicon content, confirming that the SEI layer was properly and uniformly formed.

[0191] Comparative Examples 1 and 2 were confirmed to have low capacity due to low silicon content and low ICE due to uneven SEI layer formation.

[0192]

[0193] While 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 attached drawings, but is intended to be defined by the appended claims. Accordingly, those skilled in the art will appreciate that various substitutions, modifications, and alterations may be made without departing from the technical spirit of the present invention as defined in the claims, and such modifications are also within the scope of the present invention.

Claims

1. (1) A step of preparing a mixture by heating and mixing a mixture containing a polymer having a melting point of less than 300°C and a melting point of less than 300°C; (2) a step of stabilizing the mixture; (3) a step of carbonizing the stabilized mixture to obtain a carbonized body; and (4) a step of activating the carbonized body; including; A method for producing a porous carbon support.

2. In paragraph 1, The above step (1) is performed at a temperature of the softening point of the pitch to the softening point of the pitch +50℃. A method for producing a porous carbon support.

3. In paragraph 1, The softening point of the above pitch is within the range of 220 ℃ to 280 ℃. A method for producing a porous carbon support.

4. In paragraph 1, The above polymer comprises at least one of a thermoplastic polymer and a water-soluble polymer. A method for producing a porous carbon support.

5. In paragraph 1, The weight average molecular weight of the above polymer is in the range of 5,000 to 2,000,000. A method for producing a porous carbon support.

6. In paragraph 1, The content of the polymer in step (1) above is in the range of 0.5 wt% to 5 wt% with respect to the weight of the entire mixture. A method for producing a porous carbon support.

7. In paragraph 1, The mixture of step (1) further comprises a catalyst, A method for producing a porous carbon support.

8. In paragraph 7, The content of the catalyst is in the range of 1 wt% to 10 wt% based on the weight of the entire mixture. A method for producing a porous carbon support.

9. A method for producing a carbon-silicon composite, comprising the step of depositing silicon on a porous carbon support produced by the method for producing a porous carbon support according to any one of claims 1 to 8.

10. Containing medium pores with a diameter of 2 nm to 50 nm, The ratio of the volume of the above pores to the volume of the entire pores is 40% or more, A porous carbon support having a surface area of ​​600 to 1800 m2 / g.

11. In paragraph 10, The above porous carbon support is a porous carbon support having a total pore volume of 0.5 to 1.5㎤ / g.

12. In paragraph 10, The above porous support is a porous carbon support having an average particle size (D50) of 1 to 500 μm.

13. A porous carbon support according to any one of claims 10 to 12; and A carbon-silicon composite comprising silicon formed on at least a portion of the surface and interior of the pores of the porous carbon support.

14. A battery negative electrode material comprising a porous carbon support according to any one of claims 10 to 12.

15. A battery negative electrode material comprising a carbon-silicon composite according to Article 13.

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