Method for purifying porous carbon support, porous carbon support purified thereby, and silicon negative electrode material comprising same

Abstract

The present invention relates to a method for efficiently removing metal impurities in a porous carbon support used as a silicon negative electrode material, an ultrahigh-purity porous carbon support purified by the method, a silicon negative electrode material (battery negative electrode material) using same, and a lithium ion battery and / or an all-solid-state battery comprising same as a negative electrode material.

Description

Method for purifying a porous carbon support, a porous carbon support purified by the method, and a silicon anode material comprising the same

[0001] The present invention relates to a purification method for efficiently removing metal impurities in a porous carbon support used as a silicon anode material, an ultra-high purity porous carbon support purified by the method, and a silicon anode material using the same.

[0002] With the recent development of the information and communication industry, demand for electronic devices has been rapidly increasing, and with the revitalization of the electric vehicle market, demand for batteries used in these electronic devices and electric vehicles has also increased significantly.

[0003] Secondary batteries, including lithium secondary batteries and all-solid-state batteries containing liquid electrolytes, are the most widely used for these applications due to their high energy density and minimal self-discharge when not in use. Secondary batteries generally consist of a positive electrode, a negative electrode, and an electrolyte (liquid or solid). Carbon-based materials such as graphite are widely used as the negative electrode active material.

[0004] Recently, attempts have been made to use silicon-based anode materials to improve the capacity of secondary batteries. Silicon, with its theoretically very high energy density, is attracting attention as a next-generation battery anode material to replace graphite. However, it reacts with lithium during charging and discharging, increasing its volume by up to 300%. This causes silicon, one of the anode components, to fragment during charging and discharging, resulting in significantly reduced mechanical stability.

[0005] Additionally, the introduction of carbon materials as a support for the above silicon-based negative electrode material is being attempted and developed.

[0006] Carbon materials are materials composed 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. Carbon materials can be manufactured from a variety of raw materials, including coconut shells, polyacrylonitrile, rayon, and pitch. However, carbon materials manufactured from solid raw materials like coconut shells are difficult to control in terms of molecular weight and composition (Korean Patent Application Publication No. 10-2019-0093960).

[0007] 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 reduces the energy required for heat treatment (U.S. Patent Nos. 4,242,196 and 4,340,464).

[0008] In particular, pyrolysis fuel oil (PFO), naphtha cracking bottom oil (NCB), vacuum residue (VR), and fluid catalytic cracking decant oil (FCC-DO), which are obtained as by-products in the petroleum refining process, have a high content of aromatic compounds and a low content of impurities such as sulfur and nitrogen, so the pitch manufactured from them is attracting attention as a carbon material, but the content of metal impurities is relatively high for application as an anode material for secondary batteries. If the residual amount of these metal impurities is large, there is a problem that they react with the electrolyte of the secondary battery to produce gases, increasing the risk of fire and explosion. In addition, various chemical side reactions caused by the metal impurities increase the irreversible capacity, resulting in a decrease in charge / discharge efficiency, which limits their application as anode materials for secondary batteries.

[0009] The present invention has been completed by finding optimal purification conditions that can effectively remove metal impurities within a porous carbon support, minimize damage to the carbon support, and even enhance advantageous properties as an anode material. That is, the present invention provides a method for purifying a porous carbon support for a silicon anode material, a porous carbon support for a silicon anode material purified by the method, and a silicon anode material comprising the same.

[0010] The porous carbon support of the present invention for solving the above problem contains a total of 1,000 ppm or less of metal impurities including at least one selected from Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe and Ni, and the porous carbon support has a specific surface area of ​​300 to 3,000 m 2 / g is.

[0011] As a preferred embodiment of the present invention, the metal impurities may include at least one selected from Na 35 ppm or less, Mg 90 ppm or less, Al 155 ppm or less, Ca 100 ppm or less, K 90 ppm or less, and Fe 400 ppm or less.

[0012] In addition, the present invention relates to a method for purifying a porous carbon support, comprising: a first step of preparing a porous carbon support powder; a second step of immersing and stirring the porous carbon support powder in an inorganic acid aqueous solution to perform an acidification treatment; a third step of removing the inorganic acid aqueous solution subjected to the acidification treatment to obtain a porous carbon support powder treated with an acidification agent; and a fourth step of washing and drying the obtained porous carbon support powder.

[0013] As a preferred embodiment of the present invention, the two-step inorganic acid aqueous solution may be an inorganic acid aqueous solution having a concentration of 0.2 to 10.0 M.

[0014] As a preferred embodiment of the present invention, the inorganic acid of the inorganic acid aqueous solution may include at least one selected from hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid.

[0015] As a preferred embodiment of the present invention, step 2 can be performed by mixing the porous carbon support powder and the inorganic acid aqueous solution in a weight ratio of 1:2 to 20.

[0016] As a preferred embodiment of the present invention, the second step of the calculation can be performed for 0.5 to 24 hours.

[0017] As a preferred embodiment of the present invention, the four-step washing can be repeated one or more times with distilled water.

[0018] As a preferred embodiment of the present invention, the porous carbon support powder of step 1 contains 40,000 ppm or less of one or more metal impurities selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni, and the porous carbon support powder obtained by performing step 4 may contain 1,000 ppm or less of one or more metal impurities selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni.

[0019] As a preferred embodiment of the present invention, the rate of change in oxygen content in the porous carbon support powder obtained by performing step 4 can satisfy the following equation 1.

[0020] [Formula 1]

[0021] 1 ≤ (BA) / A ≤ 10

[0022] In Equation 1, A is the oxygen content (%) in the porous carbon support powder of step 1, and B is the oxygen content (%) in the porous carbon support powder of step 4.

[0023] As a preferred embodiment of the present invention, the specific surface area change rate of the porous carbon support powder obtained by performing the above-mentioned step 4 may be -10.00 to 10.00% compared to the specific surface area of ​​the porous carbon support powder of the above-mentioned step 1.

[0024] Another object of the present invention is to provide a porous carbon support for a silicon anode material purified by the purification method described above.

[0025] In addition, another object of the present invention is to provide a silicon negative electrode material characterized by subjecting the porous carbon support to a silane coating or deposition treatment.

[0026] As a preferred embodiment of the present invention, the silicon anode material may be a silicon anode material for a secondary battery.

[0027]

[0028] In addition, the present invention can provide an anode for an all-solid-state battery or an anode current collector for an all-solid-state battery comprising the silicon anode material described above.

[0029] In addition, the present invention can provide a negative electrode for a lithium ion battery or a negative electrode current collector for a lithium ion battery including the silicon negative electrode material described above.

[0030] In addition, the present invention can provide an all-solid-state battery equipped with the negative electrode or negative electrode current collector.

[0031] In addition, the present invention can provide a lithium ion battery equipped with the negative electrode or negative electrode collector.

[0032] The purification method of the present invention can provide an ultra-high purity porous carbon support that satisfies the specific surface area and pore characteristics required as a carbon support for silicon anode materials while containing very low amounts of metal impurities. When such a porous carbon support is applied as a silicon anode material, secondary batteries (all-solid-state batteries, lithium-ion batteries) using the same can secure increased charge / discharge efficiency and high stability.

[0033] Figure 1 is a SEM image of a porous carbon support immediately after activation performed in Preparation Example 1.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Hereinafter, the present invention will be described in more detail.

[0038] The method for purifying a porous carbon support of the present invention comprises the steps of: a first step of preparing a porous carbon support powder; a second step of immersing and stirring the porous carbon support powder in an inorganic acid aqueous solution to perform an acidification treatment; a third step of removing the inorganic acid aqueous solution subjected to the acidification treatment to obtain a porous carbon support powder treated with an acidification agent; and a fourth step of washing and drying the obtained porous carbon support powder.

[0039] The above porous carbon support powder may be commercially available, and preferably, one manufactured by the following method may be used.

[0040]

[0041] [Step 1: Preparation of Porous Carbon Support Powder]

[0042] A porous carbon support powder according to one embodiment of the present invention can be manufactured by a method including the steps of (1) synthesizing pitch by thermal decomposition and polycondensation of a petroleum-based raw material, (2) solidifying the pitch to obtain a solid pitch, (3) stabilizing the pitch, (4) carbonizing the stabilized pitch to obtain a carbonized body, and (5) activating the carbonized body to obtain a porous carbon support.

[0043] Step (1)

[0044] Step (1) of the method for manufacturing a porous carbon support according to the present invention may be a step of synthesizing pitch by thermal decomposition and polycondensation of a petroleum-based raw material.

[0045] In a specific embodiment of the present invention, the petroleum-based raw material may include at least one selected from the group consisting of pyrolysis fuel oil (PFO), naphtha cracking residue (NCB), ethylene cracker bottom oil (EBO), vacuum residue (VR), de-asphalted oil (DAO), atmospheric residue (AR), fluid catalytic cracking oil (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 pyrolysis fuel oil.

[0046] In a specific embodiment of the present invention, the petroleum-based raw material may contain an aromatic compound in an amount of 10 to 90 wt%. Preferably, the petroleum-based raw material may contain an aromatic compound in an amount of 20 to 80 wt%, more preferably 30 to 70 wt%. When the content of the aromatic compound in the petroleum-based raw material satisfies the above range, even if the solid pitch pellets described below are stabilized, carbonized, and activated without separately pulverizing, a porous carbon support having controlled pore characteristics can be obtained.

[0047] In a specific embodiment of the present invention, the aromatic compound may be a compound having 1 to 4 aromatic rings. Specifically, the aromatic compound may include at least one selected from substituted or unsubstituted benzene, naphthalene, phenanthrene, indene, biphenyl, anthracene, tetralin, and fluorene.

[0048] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out at a temperature of 350 to 500°C. In a preferred specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out at a temperature of 400 to 500°C. 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 at a temperature of 430 to 470°C. When the temperature of the thermal decomposition and polycondensation of the petroleum-based raw material is 350 to 500°C, a pitch containing a large amount of relatively low molecular weight components can be produced, and in the activation process of step (5) described below, components having relatively small molecular weights are vaporized first, thereby sufficiently forming pores in the carbon support. If the thermal decomposition and polycondensation temperature of petroleum-based raw materials is less than 350°C, it is difficult to manufacture pitch that is solid at room temperature, and if this temperature exceeds 500°C, the pitch contains a large amount of relatively high molecular weight components, making it difficult to manufacture a carbon support having sufficient pores.

[0049] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum raw material may be performed under an atmosphere of an oxidizing gas, an inert gas, or a mixture thereof. In a preferred specific embodiment of the present invention, the oxidizing gas may be oxygen, ozone, or a combination thereof, the inert gas may be nitrogen, helium, neon, argon, or a combination thereof, and the mixture thereof may be air, but is not particularly limited thereto.

[0050] When an oxidizing gas is used during the thermal decomposition and polycondensation of petroleum-based raw materials, a pitch with a high softening point can be produced, but it is difficult to perform the thermal decomposition and polycondensation at high temperatures. When an inert gas is used during the thermal decomposition and polycondensation of petroleum-based raw materials, thermal decomposition and polycondensation can be performed 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 petroleum-based raw materials, thermal decomposition and polycondensation can be performed at relatively high temperatures, thereby producing a pitch with a relatively high softening point.

[0051] In a specific embodiment of the present invention, the gas may be supplied at a flow rate of 10 to 800 ml / min during the thermal decomposition and polycondensation of a petroleum-based raw material. In a preferred specific embodiment of the present invention, the gas may be supplied at a flow rate of 100 to 500 ml / min during the thermal decomposition and polycondensation of a petroleum-based raw material. When the flow rate of the gas is less than 10 ml / min, the yield of the pitch increases, but the low molecular weight component increases too much, which is disadvantageous for subsequent processes (e.g., stabilization). When the flow rate of the gas exceeds 800 ml / min, the yield of the pitch may decrease.

[0052] 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 to 10 hours. In a preferred embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out for 2 to 8 hours. In a more preferred embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material can be carried out for 2 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 produce a pitch having a high softening point, and if the thermal decomposition and polycondensation time of the petroleum-based raw material exceeds 10 hours, an excessive amount of quinoline-insoluble components may be produced.

[0053] In a specific embodiment of the present invention, the thermal decomposition and polycondensation of the petroleum-based raw material may be performed under stirring. The stirring conditions for the petroleum-based raw material are not particularly limited, but, for example, a stirrer rotating at 1 to 500 rpm may be used.

[0054] In a specific embodiment of the present invention, the pitch synthesized in step (1) may have a softening point of 200 to 350°C. In a preferred embodiment of the present invention, the pitch may have a softening point of 200 to 330°C. In a more preferred embodiment of the present invention, the pitch may have a softening point of 200 to 300°C. Since the pitch manufactured according to the present invention has a high softening point, when used as a precursor for manufacturing a carbon support, the stabilization process is easy, and a high yield can be obtained after carbonization and activation.

[0055] In a specific embodiment of the present invention, the yield of the pitch synthesized in step (1) may be 10 to 50 wt%. In another specific embodiment of the present invention, the yield of the pitch may be 10 to 40 wt%. In yet another specific embodiment of the present invention, the yield of the pitch may be 20 to 30 wt%.

[0056] In a process for producing a porous carbon support from a petroleum-based raw material according to one embodiment of the present invention, a step of pretreating the petroleum-based raw material may be performed prior to step (1) above. By removing low-boiling-point components contained in the petroleum-based raw material through the pretreatment step, a pitch having a higher softening point can be produced.

[0057] In a specific embodiment of the present invention, the pretreatment step may be performed at a temperature equal to or lower than the thermal decomposition and polycondensation temperature of the petroleum-based raw material in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be performed at 250 to 450°C, preferably 250 to 400°C, and more preferably 300 to 400°C.

[0058] In a specific embodiment of the present invention, the pretreatment step may be performed for a time equal to or shorter than the time for thermal decomposition and polycondensation of the petroleum-based raw material in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be performed for 1 to 8 hours, preferably 1 to 6 hours, and more preferably 1 to 5 hours.

[0059] Step (2)

[0060] In step (2) of a process for manufacturing a porous carbon support powder from a petroleum-based raw material according to one embodiment of the present invention, pitch can be solidified to obtain a solid pitch.

[0061] The liquid pitch obtained in step (1) is solidified, for example, by extrusion and cooling, to obtain a solid pitch. The process of extruding, cooling, and solidifying the liquid pitch to obtain a solid pitch can be performed using commercially available equipment. For example, this process can be performed using IPCO's Double Belt Cooler & Flaker, but is not particularly limited to this equipment.

[0062] The pitch obtained in step (2) has an average particle size of 1 to 30 mm, preferably 5 to 25 mm. When the average particle size of the pitch is within this range, a porous carbon support can be manufactured through stabilization, carbonization, and activation described below without separately pulverizing the pitch.

[0063] However, if necessary, the pitch obtained in step (2) may be further crushed or pulverized and classified. The pitch can be further finely divided through crushing or pulverization, and the particle size distribution of the pitch can be made uniform through classification. Here, classification may be performed by dry classification, wet classification, or classification using a sieve. By crushing or pulverizing and classification, powdered pitch having a diameter of 3 to 500 μm can be obtained.

[0064] Step (3)

[0065] Step (3) of the method for manufacturing a porous carbon support powder according to the present invention may be a step for stabilizing a solid pitch. Specifically, it may be a step for stabilizing the structure of the solid pitch by first oxidizing the solid pitch. If the solid pitch is pulverized in step (2), this step may be a step for stabilizing the pulverized powder pitch.

[0066] In a specific embodiment of the present invention, the stabilization of the pitch may be performed at a temperature of 100 to 500°C, preferably 150 to 350°C. When the stabilization of the pitch is performed at this temperature, the carbon structure within the pitch changes from thermoplastic to thermosetting, so that the structure can be stably maintained during the subsequent carbonization process. At this time, the heating rate may be 2 to 10°C / min. If the heating rate is too slow, productivity may be poor, and if the heating rate is excessively fast, uniform stabilization treatment may be difficult.

[0067] In a specific embodiment of the present invention, the stabilization of the pitch can be performed at a pressure of 0.1 to 10 bar, preferably 0.5 to 5 bar. When the stabilization of the pitch is performed at this pressure, the structure of the pitch can be sufficiently stabilized, even to the carbon inside the pitch.

[0068] In a specific embodiment of the present invention, the stabilization of the pitch can be performed under conditions of a flow rate of an oxidizing gas, preferably air or oxygen, of 0.1 to 500 ml / min, preferably 1 to 300 ml / min. When the stabilization of the pitch is performed under these oxidizing gas flow rates, the structure of the pitch, including the carbon within the pitch, can be sufficiently stabilized.

[0069] In a specific embodiment of the present invention, the pitch stabilization may be performed for 1 to 10 hours, preferably 2 to 8 hours. If the pitch stabilization is performed for this period of time, the structure of the pitch, including the carbon within the pitch, can be sufficiently stabilized.

[0070] Step (4)

[0071] Step (4) of the method for manufacturing a porous carbon support according to the present invention may be a step of carbonizing stabilized pitch to obtain a carbonized body. Through carbonizing the pitch, other functional groups contained in the pitch are removed, and a carbonized body composed of substantially pure carbon can be obtained.

[0072] In a specific embodiment of the present invention, the carbonization of the pitch may be performed under an inert gas atmosphere. In a preferred 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.

[0073] In a specific example of the present invention, carbonization of the pitch may be performed at a temperature of more than 700°C and less than or equal to 1,000°C or 800°C and less than or equal to 1,000°C. If the temperature during carbonization of the pitch is lower than this range, carbonization may not be sufficiently performed, and if the temperature during carbonization of the pitch is higher than this range, the carbonization yield may decrease.

[0074] In a specific embodiment of the present invention, the carbonization of the pitch can be performed under conditions of a flow rate of an inert gas, preferably nitrogen, of 0.01 to 30 L / min, preferably 0.01 to 10 L / min. When the carbonization of the pitch is performed under these inert gas flow rates, the pitch can be sufficiently carbonized.

[0075] In a specific embodiment of the present invention, the carbonization of the pitch may be performed for 0.5 to 5 hours, preferably 1 to 3 hours. If the carbonization of the pitch is performed for this period of time, the pitch can be sufficiently carbonized.

[0076] Step (5)

[0077] In the method for manufacturing a porous carbon support powder according to the present invention, in step (5), a porous carbon support can be obtained by activating a carbonized body. By activating the carbonized body (carbonized pitch), pores are formed in the pitch, thereby obtaining a porous carbon support.

[0078] In a specific embodiment of the present invention, the activation of the carbonized body may be performed under an oxidizing gas atmosphere. In a preferred embodiment of the present invention, the activation of the carbonized body may be performed under a steam atmosphere, but is not particularly limited thereto.

[0079] In a specific embodiment of the present invention, activation of the carbonized body can be performed at a temperature of more than 500°C and less than or equal to 1,000°C or 800°C and less than or equal to 1,000°C. When activation of the carbonized body is performed at this temperature, a porous carbon support in which micropores and mesopores are sufficiently formed can be obtained.

[0080] In a specific embodiment of the present invention, activation of the carbonized body can be performed at a pressure of 0.1 to 10 bar, preferably 0.1 to 5 bar. When 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.

[0081] 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 steam, of 0.01 to 3 L / min, preferably 0.01 to 1 L / 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.

[0082] 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.

[0083] In a specific embodiment of the present invention, steps (3) to (5) above can be performed continuously in a single device. In a preferred embodiment of the present invention, steps (3) to (5) above can be performed continuously in a single rotary kiln, but this device is not particularly limited. Since stabilization, carbonization, and activation of pitch pellets are performed continuously in a single device, process optimization can be easily achieved.

[0084] In a specific embodiment of the present invention, the porous carbon support powder obtained in step (5) may be further pulverized or ground and classified. The porous carbon support powder can be further finely divided through pulverization or grounding, and the particle size distribution of the porous carbon support can be made uniform through classification. Here, the classification may be dry classification, wet classification, or classification using a sieve. Through the pulverization or grounding and classification treatment, a porous carbon support powder having a diameter of 1 to 200 μm can be obtained.

[0085] The porous carbon support powder manufactured by performing the above steps (1) to (5) may include mesopores having a diameter of 2 nm to 50 nm. In this case, the porous carbon support powder may have a ratio of the volume of mesopores to the volume of the total pores of 0.1 or more.

[0086] Additionally, the tap density of the porous carbon support powder may be 0.9 g / ml or less, and the BET specific surface area may be 300 m 2 / g ~ 3,000 m 2 / g can be within the range.

[0087] Additionally, the particle size of the porous carbon support powder may be 200 μm or less.

[0088] Additionally, the porous carbon support powder may include macropores having a diameter exceeding 50 nm, and the ratio of macropores to the total pores of the porous carbon support powder may be 20% or less.

[0089]

[0090] [2-step calculation system]

[0091] Next, the second step of the method for purifying the porous carbon support powder of the present invention is a process of purifying the porous carbon support powder commercially purchased and the porous carbon support powder manufactured by the method described above by immersing and stirring in an aqueous inorganic acid solution.

[0092] The above-mentioned inorganic acid aqueous solution is an aqueous solution in which an inorganic acid is dissolved in water, and the inorganic acid may include at least one selected from hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid, preferably at least one selected from hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid, and more preferably may include hydrochloric acid.

[0093] And, the concentration of the inorganic acid in the inorganic acid aqueous solution may be 0.2 to 10.0 M, preferably 0.5 to 8.0 M, and more preferably 0.4 to 7.0 M. At this time, if the concentration of the inorganic acid is less than 0.2 M, there may be a problem that the removal of metal impurities in the powder is not done well or the purification time takes too long, and if it exceeds 10.0 M, there may be a problem that the surface of the porous carbon support is excessively oxidized, so it is appropriate to perform the purification with an inorganic acid aqueous solution within the above concentration range.

[0094] And, the mixing ratio of the powder and the inorganic acid aqueous solution in the second step is appropriate to mix the powder and the inorganic acid aqueous solution at a weight ratio of about 1:2 to 20, preferably at a weight ratio of about 1:4 to 15.

[0095] In addition, the second step of the acid purification is preferably performed by immersing and stirring the powder in an aqueous inorganic acid solution for 0.5 to 24 hours, preferably when the concentration of the inorganic acid is about 0.4 to 7.0 M, for 0.5 to 24 hours, more preferably 2 to 24 hours. At this time, if the acid purification time is less than 0.5 hours, the removal rate of metal impurities in the porous carbon support may be too low, and if it exceeds 24 hours, it is uneconomical and there may be a problem that some of the internal pore structures of the porous carbon support collapse.

[0096]

[0097] Next, in the third step, when the purification process is completed, a porous carbon support powder is obtained by separating it from the inorganic acid aqueous solution, and the separation method can be performed by a general method used in the art and is not particularly limited.

[0098]

[0099] Next, the four-step process of the present invention is a process of washing and drying the purified porous carbon support powder. In a preferred embodiment, the process is performed by repeatedly washing at least once with distilled water and then drying.

[0100] And, after washing is completed, after checking whether neutralization has occurred, if neutralization has occurred, drying can be performed using a general method used in the industry, such as natural drying or hot air drying, to obtain a purified, high-purity porous carbon support powder.

[0101] The porous carbon support powder purified by performing the above steps 1 to 4 is a high-purity powder with very low metal impurities.

[0102] For example, the porous carbon support powder of step 1 contains at least one metal impurity selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni in an amount of 40,000 ppm or less, and preferably 20,000 ppm or less. For example, the porous carbon support powder of step 1 may contain at least one metal impurity selected from among Na 5 to 300 ppm, Mg 1 to 150 ppm, Al 5 to 100 ppm, Si 10 to 500 ppm, K 1 to 5000 ppm, Ca 5 to 1000 ppm, Cr 10 to 200 ppm, Mn 10 to 90 ppm, Fe 1 to 5000 ppm, and Ni 5 to 100 ppm.

[0103] And, the purified porous carbon support powder obtained by sequentially performing 2 to 4 steps of purification processes contains at least one metal impurity selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni in an amount of 1,000 ppm or less, and preferably 1 to 1,000 ppm. As a specific example, the purified porous carbon support may contain at least one metal impurity selected from among Na 35 ppm or less, Mg 90 ppm or less, Al 155 ppm or less, Si 70 ppm or less, Ca 100 ppm or less, K 90 ppm or less, Cr 30 ppm or less, Mn 20 ppm or less, Fe 400 ppm or less, and Ni 10 ppm or less, and preferably Na 33 ppm or less, Mg 85 ppm or less, Al 150 ppm or less, Si 65 ppm or less, K 85 ppm or less, Ca 95 ppm or less, Cr 25 ppm or less, Mn 15 ppm or less, Fe 390 ppm or less, and Ni 8 ppm or less, and more preferably Na 30 ppm or less, Mg 82 ppm or less, Al 145 ppm or less, Si 60 ppm or less, It may contain one or more metal impurities among K 80 ppm or less, Ca 93 ppm or less, Cr 20 ppm or less, Mn 10 ppm or less, Fe 380 ppm or less, and Ni 7.5 ppm or less.

[0104]

[0105] In addition, the rate of change in oxygen content in the porous carbon support powder obtained by performing step 4 can satisfy the following equation 1.

[0106] [Formula 1]

[0107] 1 ≤ (BA) / A ≤ 10, preferably 2.0 ≤ (BA) / A ≤ 8.0, more preferably 3.0 ≤ (BA) / A ≤ 5.0, even more preferably 3.0 ≤ (BA) / A ≤ 4.0

[0108] In Equation 1, A is the oxygen content (%) in the porous carbon support powder of step 1, and B is the oxygen content (%) in the porous carbon support powder of step 4.

[0109]

[0110] Additionally, the specific surface area change rate of the porous carbon support powder obtained by performing step 4 may be -10.00 to 10.00%.

[0111]

[0112] And, the pores of the refined carbon support powder can be classified into micropores with a diameter of less than 2 nm, mesopores with a diameter of 2 nm to 50 nm, and macropores with a diameter of more than 50 nm depending on their size. These porous carbon 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 and mechanically damage the negative electrode material. In the case of mesopores, silicon can be sufficiently deposited deep in the pores during silicon deposition.

[0113] Additionally, the BET specific surface area of ​​the purified porous carbon support is 300 m 2 / g ~ 3,000 m 2 / g, preferably 600 m 2 / g ~ 2,000 m 2 / g, more preferably 700 m 2 / g ~ 1,500 m 2 / g range. The BET specific surface area of ​​the porous carbon support may be a value measured using ASAP 2420 (Micromeritics instrument, USA). Specifically, the analysis was performed after vacuum drying at 50 to 300℃ for 5 to 24 hours, and the N2 / 77K Isotherm adsorption results can be calculated using the BET equation and the BJH equation according to ISO9277. If the BET specific surface area of ​​the porous carbon support is excessively low, the proportion of macropores may increase, which may lower the mechanical strength of the negative electrode material and may result in a lack of effective pores. In addition, if the BET specific surface area of ​​the porous carbon support is too high, the proportion of micropores may increase, and silicon may not be sufficiently deposited deep into the porous carbon support.

[0114] And, the purified porous carbon support may have a diameter of 200 μm or less. The diameter is D 50 It can mean diameter. Specifically, it can mean the average value obtained by dispersing a porous carbon support in ethanol and then performing particle size analysis three times. The diameter of the porous carbon support can be 200 ㎛ or less, 150 ㎛ or less, 100 ㎛ or less, 80 ㎛ or less, or 50 ㎛ or less, and can be 1 ㎛ or more, 2 ㎛ or more, 3 ㎛ or more, 4 ㎛ or more, or 5 ㎛ or more, but is not limited thereto.

[0115]

[0116] The purification method of the present invention described above and the porous carbon support powder manufactured by this method can be provided as a silicon anode material, preferably as a silicon anode material for a secondary battery, by silane coating or deposition treatment.

[0117] As a preferred embodiment, the porous carbon support powder purified by the above method can be deposited under temperature conditions of 300°C to 600°C and a silane (SiH4) gas atmosphere. The deposition can be performed, for example, using chemical vapor deposition (CVD) and under atmospheric pressure, but is not limited thereto. Through the deposition, silicon can be deposited on the surface and inside the pores of the porous carbon support according to the present invention.

[0118] The content of the deposited silicon may be 10 wt% or more based on the weight of the total particles. The content of the deposited silicon may be a value obtained by analysis using an energy dispersive spectrometer (EDS). 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. In addition, the content of the deposited silicon may be 60 wt% or less, 58 wt% or less, 56 wt% or less, 54 wt% or less, 52 wt% or less, or 50 wt% or less, but is not limited thereto. If the content of the deposited silicon is too low, the electric capacity may be reduced. In addition, if the content of the deposited silicon is too large, the problem caused by the volume expansion of the silicon during charge and discharge may not be resolved, which may cause structural damage to the negative electrode material and deteriorate the cycle characteristics.

[0119] The present invention also relates to a battery negative electrode material (silicon negative electrode material) comprising the aforementioned porous carbon support. The battery negative electrode material comprising the porous carbon support powder according to the present invention can have improved mechanical strength along with high electrical capacity and excellent cycle characteristics.

[0120] 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 material, a binder, etc., and coating / drying / rolling the mixture onto a component such as an electrode current collector, but is not limited thereto.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] The above negative electrode may include a negative electrode material according to the present invention. The negative electrode may have a single-layer structure including the negative electrode material, or may further include a negative electrode current collector as needed, but is not limited thereto.

[0127] 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.

[0128]

[0129] Hereinafter, the present invention will be described in more detail through examples, but the following examples do not limit the scope of the present invention, and should be interpreted as helping to understand the present invention.

[0130]

[0131] [Example]

[0132] Preparation Example 1: Preparation of porous carbon support powder

[0133] 300 g of petroleum residue oil (YNCC PFO) 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 (softening point: 250°C) was solidified and pelletized to obtain solid pitch pellets with an average particle size of 1–30 mm.

[0134] The solid pitch pellets obtained above were crushed and then placed in a rotary kiln, where they were sequentially subjected to stabilization, carbonization, and activation. The conditions for stabilization, carbonization, and activation are shown in Table 1 below.

[0135] And, the cross-sectional SEM image of the pitch immediately after stabilization is shown in Fig. 1.

[0136] The activated carbonized body, which was activated above, was pulverized using a pulverizer (NETZSCH, air jet mill) to produce a porous carbon support powder, and the properties of the manufactured porous carbon support powder are shown in Table 2 below.

[0137] The specific surface area of ​​the porous carbon support was measured using ASAP 2420 according to ASTM D4820-99. 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 Analyzer, LA-960V2) according to ASTM D822.

[0138] Step Condition Preparation Example 1 Stabilization temperature (℃) 320 hours (hr) 2 Atmosphere air carbonization temperature (℃) 900 hours (hr) 1 Atmosphere nitrogen activation temperature (℃) 900 hours (hr) 3 Steam flow rate (ml / min) 100

[0139] Example 1 of preparation for classification Average particle size (㎛) 5.5 Specific surface area (m 2 / g)984.0Total pore volume (cm) 3 / g)0.62 micro pore volume (cm)3 / g)0.55 mesopore volume (cm) 3 / g)0.04 Micropore volume ratio among total pores (%)88.7 Mesopore volume ratio among total pores (%)6.5 Oxygen content (%)0.5

[0140]

[0141] Example 1-1 ~ Example 1-2: Purification of porous carbon support powder

[0142] The porous carbon support of Preparation Example 1 was immersed in a 0.5 M HCl aqueous solution, and then purified for 2 hours and 24 hours, respectively, while stirring. At this time, the mixing ratio of the porous carbon support powder and the HCl aqueous solution was 1:10 by weight.

[0143] A porous carbon support powder with reduced metal impurities was obtained by performing the calculation for each of the above times.

[0144] Next, after preparing distilled water, the porous carbon support powder was repeatedly washed.

[0145] After washing, the powder was dried with hot air to obtain a purified porous carbon support powder.

[0146]

[0147] Example 2-1 ~ Example 2-2: Purification of porous carbon support powder

[0148] A purified porous carbon support powder was obtained using the same method and conditions as in Example 1, but a 1.0 M HCl aqueous solution was used instead of a 0.5 M HCl aqueous solution during purification, and the acidification was performed for 2 hours and 24 hours, respectively.

[0149]

[0150] Examples 3-1 to 3-2: Purification of porous carbon support powder

[0151] A purified porous carbon support powder was obtained using the same method and conditions as in Example 1, but a 5.0 M HCl aqueous solution was used instead of a 0.5 M HCl aqueous solution during purification, and the acidification was performed for 2 hours and 24 hours, respectively.

[0152]

[0153] Examples 4-1 to 4-2: Purification of porous carbon support powder

[0154] A purified porous carbon support powder was obtained using the same method and conditions as in Example 1, but an 8.0 M HCl aqueous solution was used instead of a 0.5 M HCl aqueous solution during purification, and the acidification was performed for 2 hours and 24 hours, respectively.

[0155]

[0156] Examples 5 to 8: Purification of porous carbon support powder

[0157] A purified porous carbon support powder was obtained using the same method and conditions as in Example 1, but instead of the HCl aqueous solution, a 1.0 M HNO3 aqueous solution, a 1.0 M HF aqueous solution, a 1.0 M H2SO4 aqueous solution, and a 1.0 M H3PO4 aqueous solution were used, respectively, to perform the acidification process for 24 hours, and Examples 5 to 8 were performed, respectively.

[0158]

[0159] Examples 9-1 to 9-2

[0160] A purified porous carbon support powder was obtained using the same method and conditions as in Example 1, but instead of the 0.5 M HCl aqueous solution, an 11.0 M HCl aqueous solution was used during the purification process, and the acidification was performed for 2 hours and 24 hours, respectively.

[0161]

[0162] Experimental Example 1: Analysis of Metal Impurities in Porous Support Powder

[0163] The content of metal impurities was measured by ICP-AES for each of the porous carbon support powders obtained in Preparation Example 1 and the Examples above, and the results are shown in Tables 3 and 4 below.

[0164] Classification NaMgAlCaKFe Preparation Example 194232315373270662HCl 0.5 M Example 1-12 hours 26781349269376 Example 1-224 hours 27791427172306HCl 1.0 M Example 2-12 hours 29781397271278 Example 2-224 hours 26591145356291HCl 5.0 M Example 3-12 hours 26561377679289 Example 3-224 hours 25641125354253HCl 8.0 M Example 4-12 hours 27631286768276 Example 4-224 Hours 25781197272295HNO31.0M Example 524 Hours 28591345859260HF 1.0M Example 624 Hours 19721218077272H2SO41.0M Example 724 Hours 18671396565284H3PO41.0M Example 824 Hours 21801155150268HCl 11.0M Example 9-12 Hours 20751345840256 Example 9-224 Hours 18701015431211

[0165] As shown in Table 3 above, compared to the unrefined porous carbon support powder of Preparation Example 1, the content of metal impurities has been significantly reduced. Due to this reduced content of impurities, improved battery performance can be expected.

[0166]

[0167] Experimental Example 2: Measurement of pore structure and oxygen content of purified porous support powder

[0168] The pore structure and resistance of each porous carbon support powder obtained in the above preparation examples and examples were measured, and the results are shown in Tables 4 and 5 below.

[0169] The specific surface area change rate (%) in Table 4 below is calculated as a percentage based on the specific surface area of ​​Preparation Example 1 using Equation 2 below.

[0170] [Formula 2]

[0171] Specific surface area change rate (%) = (DC) / C*100(%),

[0172] In Equation 2, C is the specific surface area of ​​the porous carbon support powder of Preparation Example 1, and D is the specific surface area of ​​the porous carbon support powder of the Example.

[0173] In addition, the oxygen content change rate in Table 5 below is calculated based on the oxygen content of Preparation Example 1 using Equation 1 below.

[0174] [Formula 1]

[0175] 1 ≤ (BA) / A ≤ 10

[0176] In Equation 1, A is the oxygen content (%) in Preparation Example 1, and B is the oxygen content (%) in the porous carbon support powder of the example.

[0177] Specific surface area (m) 2 / g) Surface area change rate (%) Total pore volume (cm) 3 / g) Micropore volume (cm 3 / g) Mesopore volume (cm) 3 / g) Micropore volume ratio (%) Mesopore volume ratio (%) Preparation Example 1984-0.620.550.0488.76.5 HCl 0.5 M Example 1-12 hours 10031.930.630.570.0490.47.0 Example 1-224 hours 9900.610.630.570.0490.47.0 HCl 1.0 M Example 2-12 hours 952-3.250.610.560.0590.78.0 Example 2-224 hours 956-2.850.620.540.0487.48.0 HCl 5.0 M Example 3-12 Time 100 3 1.9 3 0.6 2 0.5 4 0.0 4 8 7.1 6.5 Example 3-2 2 4 Time 93 5-4.9 8 0.6 2 0.5 5 0.0 4 8 8.7 6.5 HCl 8.0 M Example 4-12 Time 104 25.8 9 0.6 1 0.5 5 0.0 4 9 0.2 6.6 Example 4-2 2 4 Time 98 3-0.1 0 0.6 2 0.5 7 0.0 5 9 1.9 8.1 HNO 3 1.0 M Example 5 2 4 Time 97 2-1.2 2 0.6 3 0.5 5 0.0 4 8 7.3 6.3 HF 1.0 M Example 6 2 4 Time 96 1-2.3 4 0.6 3 0.5 7 0.0 5 9 0.5 7.9 H2SO 4 1.0 M Example 7 2 4 Time 10163.250.610.560.0491.86.6H3PO41.0M Example 824 Time 9951.120.630.550.0587.37.9HCl 11.0M Example 9-12 Time 850-13.620.420.370.0488.19.5 Example 9-224 Time 790-19.720.40.360.0390.07.5

[0178] ClassificationOxygen content (%)Oxygen content change rateElectrical conductivity (S / cm, at 2000 kgf)Preparation example 10.5-6.980HCl 0.5 MExample 1-12 hours 1.72.47.881Example 1-224 hours 1.82.67.890HCl 1.0 MExample 2-12 hours 1.82.67.885Example 2-224 hours 1.92.87.894HCl 5.0 MExample 3-12 hours 2.84.67.657Example 3-224 hours 3.56.07.451HCl 8.0 MExample 4-12 hours 4.58.07.333Example 4-224 hours 5.19.26.997HNO3 1.0 MExample 524 6.1 11.2 6.8 4 5 HF 1.0 M Example 6 24 hr 6.2 11.4 6.8 1 4 H2SO 4 1.0 M Example 7 24 hr 5.8 10.6 6.9 8 H3PO 4 1.0 M Example 8 24 hr 3.5 6 7.3 9 4 HCl 11.0 M Example 9-12 hr 6.2 11.4 6.8 0 2 Example 9-2 24 hr 6.5 12.0 6.7 8

[0179] According to the analysis results shown in Table 5 above, Example 2-2, which had the best effect in reducing metal impurities, showed the highest electrical conductivity (low resistance), confirming that it is most advantageous to use as a negative electrode material. In addition, the higher the rate of change in oxygen content, the lower the electrical conductivity tends to be, and in particular, it was confirmed that the electrical conductivity decreased significantly when the rate of change in oxygen content exceeded 10%.

[0180] And, looking at Tables 4 and 5 above, it can be confirmed that the specific surface area change rate and pore characteristics are different depending on the type and concentration of the acid purification solution. It can be confirmed that Examples 1-1 to 8 have a specific surface area change rate that satisfies the range of -10% to 10% while the oxygen content change rate is within 10. However, in the case of Examples 9-1 and 9-2 where the concentration of the acid purification solution exceeded 10M, the specific surface area change rate greatly exceeded the range of -10% to 10%, resulting in a problem of the specific surface area being greatly reduced, and it can be confirmed that there is a problem of the oxygen content change rate also greatly changing by exceeding 10.

[0181] In addition, in Example 5 using nitric acid instead of hydrochloric acid, Example 6 using hydrofluoric acid, and Example 7 using sulfuric acid, it was confirmed that the rate of change in oxygen content exceeded 10 and the electrical conductivity was relatively reduced. Therefore, it was found that using hydrochloric acid as the acidifier could exhibit a better effect.

[0182] The specific surface area within the porous carbon support is a factor that affects the silicon deposition pattern, and if the specific surface area changes significantly due to acid refining, it can affect the uniformity of product quality, and the oxygen content within the porous carbon support is a factor that affects resistance, and if the oxygen content change rate exceeds 10%, it can reduce the electrical conductivity of the porous carbon support, which can be a factor that impairs battery performance, and therefore, it is not suitable for use as a material for the porous carbon support-silicon composite powder, which is a silicon anode material.

[0183]

[0184] Manufacturing Example 1

[0185] A porous carbon support-silicon composite powder (carbon-silicon composite particles) was prepared using the purified porous carbon support manufactured in Example 2-2. 18.0 g of the porous carbon support powder was placed in a rotary kiln, and silane (SiH4) gas was injected to coat the porous carbon support.

[0186] During silane gas coating, the pressure was at normal pressure, and the coating was performed at a temperature of 475°C for 1 hour.

[0187]

[0188] Comparative Manufacturing Example 1

[0189] A porous carbon support-silicon composite powder was prepared in the same manner as in Preparation Example 1, except that an unrefined porous carbon support having a diameter of 5.5 μm (Preparation Example 1) was used as the carbon support.

[0190]

[0191] Comparative Manufacturing Example 2

[0192] A carbon support-silicon composite powder was prepared in the same manner as in Manufacturing Example 1, except that graphite having a diameter of 17.08 μm was used as the carbon support.

[0193]

[0194] Comparative manufacturing example 3

[0195] A porous carbon support-silicon composite powder was manufactured in the same manner as in Manufacturing Example 1, except that a commercially available product (Ingevity®, USA, product name BAX1500) with a diameter of 4.28 μm was used as the carbon support.

[0196]

[0197] Manufacturing Examples 2 and 3

[0198] A porous carbon support-silicon composite powder (carbon-silicon composite particle) was manufactured in the same manner as Manufacturing Example 1, but Manufacturing Example 2 was performed using the porous carbon support of Example 4-2 instead of the purified porous carbon support manufactured in Example 2-2, and Manufacturing Example 3 was performed using the porous carbon support of Example 9-2, thereby manufacturing a silane-coated porous carbon support (silicon negative electrode material), respectively.

[0199] Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Comparative Manufacturing Example 1 Comparative Manufacturing Example 2 Comparative Manufacturing Example 3 Porous carbon support (before coating) Average particle size (㎛) 5.5 5.4 5.4 5.5 17.14.3 Specific surface area (m 2 / g)956983790101051934Tap density (g / ml)0.410.400.420.420.960.21Microporosity (%)87929086012Mesoporosity (%)78884472Silane-coated porous carbon support (after coating)Average particle size (㎛)5.55.45.55.518.55.4Specific surface area (m 2 / g)201815182.94206.42Tab density (g / ml)0.610.630.620.611.020.57Silicon content (weight%)50.950.551.251.25.727.3

[0200] Comparing Manufacturing Examples 1 to 3 of Table 6 above, there was a difference in terms of the specific surface area before silane coating, but there was almost no significant effect by the concentration of the acid purification solution in terms of the physical properties (size, specific surface area, tap density, silicon content) of the silane-coated porous carbon support.

[0201]

[0202] Experimental Example 3: Electrochemical Evaluation of Secondary Batteries

[0203] Half coin cells were manufactured using the manufactured carbon-silicon composite particles.

[0204] A slurry was prepared by mixing the carbon-silicon composite particles of the manufacturing example or comparative manufacturing example: conductive material: binder in a ratio of 8:1:1. 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.

[0205] The above 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.

[0206] A half coin cell was manufactured using the above-mentioned negative plate and lithium foil as a counter electrode. A porous polyethylene film was used as a separator, and a CR2032 half coin cell was manufactured under the conditions shown in Table 7 below.

[0207] 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) as additives.

[0208] 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

[0209] In Table 7 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.

[0210] Electrochemical analysis was performed on the manufactured half coin cell under the following conditions.

[0211] Cut off voltage (V): 0.005 - 1.5V (Formation), 0.005 - 1.2V(Cycle)

[0212] Formation C-rate (C): 0.1C lithiation, 0.1C delithiation

[0213] Cycle C-rate (C): 0.5C lithiation, 0.5C delithiation

[0214] ClassificationCharge capacity (mAh / g)Discharge capacity (mAh / g)Initial charge / discharge efficiency (%)Manufacturing example 12121195792.3Manufacturing example 22125193591.1Manufacturing example 32019181589.9Comparative manufacturing example 11903170189.4Comparative manufacturing example 261355290.0Comparative manufacturing example 386053061.6

[0215] Looking at the electrochemical evaluation of Table 8 above, it was confirmed that Manufacturing Example 1 using a porous carbon support-silicon composite powder using the purified porous carbon support manufactured in Example 2-2 had a relatively excellent initial charge-discharge efficiency (ICE) compared to Comparative Manufacturing Example 1 using a porous carbon support-silicon composite powder using an unpurified porous carbon support, and Comparative Manufacturing Examples 2 and 3 using graphite as a carbon support.

[0216] And, comparing Manufacturing Example 2 and Manufacturing Example 3, it was confirmed that in the case of Manufacturing Example 3, the oxygen content in the porous support of the negative electrode material used was relatively high, and due to the increase in oxygen content, the conductivity of the carbon support was relatively low, and as a result, the charge / discharge capacity decreased, and the charge / discharge efficiency was relatively low by more than 1%.

[0217]

[0218] 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. Contains a total of 1,000 ppm or less of metal impurities including one or more selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni. Specific surface area: 300 to 3,000 m 2 A porous carbon support characterized by having / g.

2. In paragraph 1, A porous carbon support comprising at least one metal impurity selected from Na 35 ppm or less, Mg 90 ppm or less, Al 155 ppm or less, Ca 100 ppm or less, K 90 ppm or less, and Fe 400 ppm or less.

3. Step 1: Preparing porous carbon support powder; Step 2: performing acid purification by immersing and stirring the porous carbon support powder in an aqueous inorganic acid solution; Step 3: removing the acid-treated inorganic acid aqueous solution to obtain a porous carbon support powder treated with an acid-treated agent; and A method for purifying a porous carbon support, characterized in that it comprises performing a process including the step of washing and drying the obtained porous carbon support powder.

4. In paragraph 3, A method for purifying a porous carbon support, wherein the above two-step inorganic acid aqueous solution is an inorganic acid aqueous solution having a concentration of 0.2 to 10.0 M.

5. In paragraph 3, A method for purifying a porous carbon support, characterized in that the inorganic acid of the above inorganic acid aqueous solution includes at least one selected from hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid.

6. A method for purifying a porous carbon support, characterized in that in the third paragraph, the second step is performed by mixing a porous carbon support powder and an inorganic acid aqueous solution in a weight ratio of 1:2 to 20.

7. A method for purifying a porous carbon support, characterized in that the step 2 of the third paragraph is performed for 0.5 to 24 hours.

8. A method for purifying a porous carbon support, characterized in that in the third paragraph, the washing in the fourth step is repeated at least once with distilled water.

9. In the third paragraph, the porous carbon support powder of step 1 contains at least one metal impurity selected from among Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni at 40,000 ppm or less, A method for purifying a porous carbon support, characterized in that the porous carbon support powder obtained by performing step 4 contains 1,000 ppm or less of one or more metal impurities selected from Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Ni.

10. A method for purifying a porous carbon support, characterized in that the rate of change in oxygen content in the porous carbon support powder obtained by performing step 4 in the third paragraph satisfies the following equation 1: [Formula 1] 1 ≤ (BA) / A ≤ 10 In Equation 1, A is the oxygen content (%) in the porous carbon support powder of step 1, and B is the oxygen content (%) in the porous carbon support powder of step 4.

11. A method for purifying a porous carbon support, characterized in that, in the third paragraph, the specific surface area change rate of the porous carbon support powder obtained by performing the fourth step is -10.00 to 10.00% compared to the specific surface area of ​​the porous carbon support powder of the first step.

12. A silicon anode material characterized by having the porous carbon support of claim 1 or 2 subjected to silane coating or deposition treatment.

13. A silicon anode material according to claim 12, characterized in that the silicon anode material is a silicon anode material for a secondary battery.

14. An all-solid-state battery negative electrode characterized by comprising the silicon negative electrode material of clause 12.

15. An all-solid-state battery characterized by having the negative electrode of clause 14.

16. A negative electrode for a lithium ion battery, characterized by including the silicon negative electrode material of Article 12.

17. A lithium ion battery characterized by having the negative electrode of clause 16.

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