Secondary battery electrode material and manufacturing method therefor

Abstract

The present invention relates to a secondary battery electrode material and a manufacturing method therefor, wherein a coating layer containing petroleum pitch is formed with an appropriate thickness and shape on the surface of an electrode active material, so that the secondary battery electrode material has a sphericity within an appropriate range, thereby significantly improving the performance of a secondary battery employing the secondary battery electrode material.

Description

Secondary battery electrode material and manufacturing method thereof

[0001] The present invention relates to a secondary battery electrode material including petroleum pitch and a method for manufacturing the same.

[0002]

[0003] Due to the rapid increase in fossil fuel use, the demand for alternative or clean energy is increasing, and as part of this, the most actively researched field is power generation and storage using electrochemical reactions.

[0004] Secondary batteries are a prime example of electrochemical devices that utilize this electrochemical energy, and their applications are expanding. With the recent technological development and increasing demand for portable devices such as laptops, mobile phones, and cameras, the demand for secondary batteries as an energy source has rapidly increased. Among these secondary batteries, lithium secondary batteries, which boast high energy density and high capacity, have been extensively studied and are now commercialized and widely used.

[0005] In general, secondary batteries are composed of a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode material of a lithium secondary battery includes a metal oxide such as LiCoO2, Li(NiCoMn)O2, Li(NiCoAl)O2, LiFePO4, LiMnO2, LiMn2O4, or LiCrO2, and the negative electrode material includes a metal lithium, a carbon-based material such as graphite or activated carbon, or a material such as silicon oxide (SiOx). Among the above negative electrode materials, metal lithium was mainly used in the early days, but as the charge and discharge cycle progresses, lithium atoms grow on the surface of the metal lithium, damaging the separator and destroying the battery. Therefore, carbon-based materials are mainly used recently. However, carbon-based materials have a disadvantage of low capacity, with a theoretical capacity of only about 400 mAh / g, and various studies are being conducted to replace the carbon-based materials using high-capacity materials such as silicon (Si), which has a high theoretical capacity (4,200 mAh / g) as a negative electrode material.

[0006] Meanwhile, when using negative electrode materials such as silicon, a technology is being applied to coat the surface of the negative electrode with pitch, which acts as a conductive material and binder, to prevent volume changes. However, the performance of secondary batteries remains inconsistent depending on the pitch used.

[0007]

[0008] The present invention has been devised to overcome the above-described problems, and provides a secondary battery electrode material and a method for manufacturing the same, which can significantly improve the performance of a secondary battery to which the secondary battery electrode material is applied by forming a coating layer containing petroleum pitch on the surface of an electrode active material with an appropriate thickness and an appropriate shape, thereby allowing the secondary battery electrode material to have an appropriate range of sphericity.

[0009]

[0010] To solve the above-described problem, the secondary battery electrode material of the present invention may include an electrode active material including silicon (Si) and a coating layer coated on the surface of the electrode active material.

[0011] As a preferred embodiment of the present invention, the coating layer may include carbonized petroleum pitch.

[0012] As a preferred embodiment of the present invention, the carbonized petroleum pitch may be carbonized at a temperature of 300 to 900°C for 60 to 300 minutes.

[0013] As a preferred embodiment of the present invention, the electrode active material may be a silicon-carbon (Si-C) composite particle containing 5 to 80 wt% of silicon.

[0014] As a preferred embodiment of the present invention, the silicon-carbon (Si-C) composite particles may have an average particle size of 4.0 to 8.0 μm and a tap density of 0.4 to 0.9 g / ml.

[0015] As a preferred embodiment of the present invention, the silicon-carbon (Si-C) composite particles may include a carbon support and silicon (Si) deposited on the surface of the carbon support.

[0016] As a preferred embodiment of the present invention, the secondary battery electrode material of the present invention can satisfy the following condition (1).

[0017] (1) A : B = 1 : 0.03 ~ 0.06

[0018] In the above condition (1), A represents the average particle size (㎛) of the electrode active material, and B represents the thickness (㎛) of the coating layer.

[0019] As a preferred embodiment of the present invention, the coating layer may have a thickness of 0.01 to 3 μm.

[0020] As a preferred embodiment of the present invention, the secondary battery electrode material of the present invention may have a sphericity of 0.5 to 1.

[0021] As a preferred embodiment of the present invention, the secondary battery may be a lead (Pd) battery, a nickel-cadmium (NiCd) battery, a nickel-metal (Ni-Metal) hydrogen battery, a lithium ion (Li-ion) battery, a lithium ion polymer (Li-ion polymer) battery, a lithium-metal (Li-Metal) battery, or an all solid state battery.

[0022] As a preferred embodiment of the present invention, the electrode active material may be a negative electrode active material.

[0023] As a preferred embodiment of the present invention, the secondary battery electrode material of the present invention may be a secondary battery negative electrode material.

[0024] Meanwhile, the method for manufacturing a secondary battery electrode material of the present invention may include a first step of forming a coating layer on the surface of an electrode active material by coating petroleum pitch on the surface of the electrode active material, and a second step of manufacturing a secondary battery negative electrode material by carbonizing the electrode active material on the surface of which the coating layer has been formed.

[0025] As a preferred embodiment of the present invention, the first step of the coating method for manufacturing a secondary battery electrode material of the present invention can be performed by dry coating using a mechano-fusion method.

[0026] As a preferred embodiment of the present invention, dry coating can be performed at a speed of 900 to 4,500 rpm for 5 to 30 minutes.

[0027] As a preferred embodiment of the present invention, the carbonization in the second step of the method for manufacturing a secondary battery electrode material of the present invention can be performed at a temperature of 300 to 900°C for 60 to 300 minutes.

[0028]

[0029] The secondary battery electrode material of the present invention and the method for manufacturing the same form a coating layer containing petroleum pitch on the surface of an electrode active material with an appropriate thickness and an appropriate shape, thereby allowing the secondary battery electrode material to have an appropriate range of sphericity, thereby significantly improving the performance of a secondary battery to which the secondary battery is applied.

[0030]

[0031] Hereinafter, the present invention will be described in more detail.

[0032] To prevent volume changes when using existing anode materials like silicon, a technology has been applied to coat the surface of the anode with pitch, which acts as a conductive material and binder. However, the performance of secondary batteries has been inconsistent depending on the pitch used.

[0033] Accordingly, the present invention forms a coating layer containing petroleum pitch on the surface of an electrode active material with an appropriate thickness and an appropriate shape, thereby allowing a secondary battery electrode material to have an appropriate range of sphericity, thereby significantly improving the performance of a secondary battery to which the electrode material is applied.

[0034]

[0035] The secondary battery electrode material of the present invention may include an electrode active material including silicon (Si) and a coating layer coated on the surface of the electrode active material.

[0036] At this time, the electrode active material containing silicon (Si) may be a silicon-carbon (Si-C) composite particle.

[0037] Specifically, the silicon-carbon (Si-C) composite particles may contain 5 to 80 wt% of silicon (Si), preferably 10 to 60 wt%, more preferably 20 to 40 wt%, and even more preferably 25 to 35 wt%. If the silicon (Si) content is less than 5 wt%, there may be a problem of deterioration in performance, and if it exceeds 80 wt%, there may be a problem of volume expansion and / or cycle degradation.

[0038] More specifically, the silicon-carbon (Si-C) composite particles may include a carbon support and silicon (Si) deposited on the surface of the carbon support.

[0039] At this time, the carbon support may include a porous carbon support, and the surface of the porous carbon support includes not only the surface exposed to the outside but also the surface located inside.

[0040] Specifically, the porous carbon support is a porous material having pores on the outer surface and / or the inner surface. As an example, when silicon (Si) is deposited on the surface of the porous carbon support, the silicon (Si) penetrates and is deposited not only on the outer surface of the porous carbon support but also on the inner surface of the porous carbon support through the pores, thereby not only partially or entirely blocking the pores of the porous carbon support, but also being deposited on the outer surface of the porous carbon support with a certain thickness.

[0041] Additionally, the silicon-carbon (Si-C) composite particles may have an average particle size of 4.0 to 8.0 μm, preferably 5.0 to 7.0 μm, and more preferably 5.8 to 6.6 μm. Additionally, the silicon-carbon (Si-C) composite particles may have a tap density of 0.4 to 0.9 g / ml, preferably 0.5 to 0.8 g / ml, and more preferably 0.6 to 0.7 g / ml.

[0042] Meanwhile, a commercially available porous carbon support may be used, and preferably, one manufactured by the following method may be used.

[0043] A porous carbon support 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.

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

[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 (RFCC-DO) oil, 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, a porous carbon support having controlled pore characteristics can be obtained even when the solid pitch pellets described below are stabilized, carbonized, and activated without separate pulverization.

[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. In this case, 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.

[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 with relatively small molecular weights are vaporized first, thereby sufficiently forming mesopores 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 lot of relatively high molecular weight components, making it difficult to manufacture a carbon support having mesopores.

[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 10 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). 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 40°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 thermal decomposition and polycondensation time 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) of the method for manufacturing a porous carbon support can solidify the pitch to obtain a solid pitch.

[0060] 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 specifically limited to this equipment.

[0061] (2) 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.

[0062] However, if necessary, the pitch obtained in step (2) can 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 can be performed by dry classification, wet classification, or classification using a sieve. By crushing or pulverizing and classification, powdered pitch with a diameter of 50 to 500 μm can be obtained.

[0063] Step (3) of the method for manufacturing a porous carbon support may be a step for stabilizing the 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.

[0064] 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.

[0065] In a specific embodiment of the present invention, the stabilization of the pitch can be performed at a pressure of 0.1 to 10.0 bar, preferably 0.5 to 5.0 bar. When the stabilization of the pitch is performed at this pressure, the structure of the pitch can be sufficiently stabilized, even up to the carbon inside the pitch.

[0066] 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.

[0067] 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.

[0068] Step (4) of the method for manufacturing a porous carbon support may be a step of carbonizing the 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.

[0069] 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.

[0070] In a specific embodiment of the present invention, carbonization of the pitch may be performed at a temperature of 700°C to 1,000°C or 800°C 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.

[0071] In a specific embodiment of the present invention, the carbonization of the pitch can be performed under a flow rate condition of an inert gas, preferably nitrogen, of 0.1 to 30.0 ml / min, preferably 0.1 to 10.0 ml / min. When the carbonization of the pitch is performed under these inert gas flow rates, the pitch can be sufficiently carbonized.

[0072] In a specific embodiment of the present invention, the carbonization of the pitch may be performed for 0.5 to 5.0 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.

[0073] Step (5) of the method for manufacturing a porous carbon support can obtain a porous carbon support by activating a carbonized body. By activating the carbonized body (carbonized pitch), pores are formed in the pitch, thereby obtaining a porous carbon support.

[0074] 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.

[0075] In a specific embodiment of the present invention, activation of the carbonized body can be performed at a temperature of 700°C to 1,000°C or 800°C 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.

[0076] In a specific embodiment of the present invention, activation of the carbonized body can be performed at a pressure of 0.1 to 10.0 bar, preferably 0.1 to 5.0 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.

[0077] 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 100.0 ml / min, preferably 0.1 to 50.0 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.

[0078] In a specific embodiment of the present invention, the activation of the carbonized body may be performed for 0.5 to 5.0 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.

[0079] In a specific embodiment of the present invention, steps (3) to (5) above may each be performed in a heating furnace using microwaves. In a preferred specific embodiment of the present invention, steps (3) to (5) above may all be performed in a heating furnace using microwaves. A heating furnace using microwaves is preferred because it can increase the temperature of the pitch pellets themselves without increasing the external temperature of the pitch pellets, but is not particularly limited thereto.

[0080] 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.

[0081] In a specific embodiment of the present invention, the porous carbon support (or porous carbon support powder) obtained in step (5) may be further pulverized or ground and classified. Through pulverization or grounding, the porous carbon support powder 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 powdered porous carbon support having a diameter of 1 to 20 μm can be obtained.

[0082] At this time, the porous carbon support may include a surface portion and a core portion, and in the present specification, the core portion of the carbon support may mean an area within a distance of 1 / 2 of the radius of the support from the center of the support, and the surface portion may mean the remaining area of ​​the support excluding the core portion.

[0083] The porous carbon support manufactured by performing steps (1) to (5) above includes mesopores having a diameter of 2 nm to 50 nm, and the ratio of the volume of the mesopores of the surface layer to the volume of the entire mesopores may be 50% or more, preferably 50 to 76%. When the ratio of the mesopores of the surface layer to the volume of the entire mesopores of the porous carbon support is 50% or more, the mesopores formed in the surface layer may act as passages through which pores may be formed to the inner surface, so that silicon may be deposited to the interior of the support. In addition, the volume of the entire mesopores of the porous carbon support may refer to the volume of the entire mesopores arranged in the interior of the porous carbon support, and the volume of the mesopores of the surface layer may refer to the volume of the entire mesopores arranged in the surface layer of the porous carbon support. In addition, the volume of the mesopores of the surface layer may mean the volume of the area corresponding to the surface layer with respect to the entire mesopores arranged in the porous carbon support.

[0084] At this time, if the ratio of the surface mesopores to the entire mesopores of the silicon-carbon composite particles is outside the above range, the charge / discharge capacity may decrease and the cycle characteristics may deteriorate.

[0085] In one example of the present invention, the porous carbon support may have a mesopore volume ratio of 10% or more to the total pore volume. The pores of the porous carbon support 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. Such 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 silicon (Si) is difficult to deposit inside the pores, resulting in a decrease in electrical capacity. 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.

[0086] On the other hand, in the case of mesopores, silicon can be sufficiently deposited on the inner surface of the porous carbon support during deposition. The silicon-carbon composite particles of the present invention can deposit a sufficient amount of silicon within the pores of the porous support by including mesopores within a predetermined range.

[0087] The above porous carbon support may have a ratio of the volume of mesopores to the volume of the entire pores of 10% or more, 12% or more, 14% or more, or 15% or more, but is not limited thereto. The upper limit of the ratio of the volume of mesopores to the volume of the entire pores of the above porous carbon support is not particularly limited, but may be, for example, 70% or less, 60% or less, 50% or less, or 40% or less. When the ratio of the volume of mesopores to the volume of the entire pores of the porous carbon support of the silicon-carbon composite particles satisfies the above range, it is possible to have excellent electrical properties while preventing excessive aggregation of silicon, thereby preventing damage due to volume expansion of silicon.

[0088] In one embodiment of the present invention, the tap density of the porous carbon support may be 0.70 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, the process of performing another 1,000 taps and observing the volume is repeated three times until there is no difference from the previous volume, and the tap density can be calculated using 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, 0.10 g / ml or more, 0.15 g / ml or more, 0.20 g / ml or more, or 0.22 g / ml or more, but is not limited thereto. If the tap density of the porous carbon support is too low, process control may be difficult during silane gas deposition, which may result in a decrease in yield. In addition, if the tap density of the porous carbon support is too high, uniform coating may be difficult during silane gas deposition.

[0089] In one example of the present invention, the BET specific surface area of ​​the porous carbon support is 300 m 2 / g ~ 3,000 m 2 / g range. The BET specific surface area of ​​the porous carbon support can be a value measured using ASAP 2420 (Micromeritics instrument (USA)). Specifically, the analysis was performed after vacuum drying at 300℃ for 5 hours, and the N2 / 77K Isotherm adsorption results can be calculated using the BET equation and the BJH equation according to ISO9277. The BET specific surface area of ​​the porous carbon support can be 300 ㎡ / g or more, 400 ㎡ / g or more, or 500 ㎡ / g or more, and 3,000 ㎡ / g or less, 2,800 ㎡ / g or less, 2,600 ㎡ / g or less, 2,000 ㎡ / g or less, or 1,900 ㎡ / g or less, but is not limited thereto. If the BET surface area of ​​the porous carbon support is excessively low, the proportion of macropores may increase, which may reduce the mechanical strength of the negative electrode material and result in a lack of effective pores. Furthermore, if the BET surface area of ​​the porous carbon support is excessively high, the proportion of micropores may increase, and silicon may not be sufficiently deposited on the inner surface of the porous carbon support.

[0090] The diameter of the porous carbon support may be 20 ㎛ or less. The diameter may refer to the D50 diameter 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 diameter of the porous carbon support may be 20 ㎛ or less, 18 ㎛ or less, 16 ㎛ or less, 14 ㎛ or less, 12 ㎛ or less, or 10 ㎛ or less, and may be 1 ㎛ or more, 2 ㎛ or more, 3 ㎛ or more, 4 ㎛ or more, or 4.5 ㎛ or more, but is not limited thereto. If the diameter of the porous carbon support is too small, when performing coating, silicon may be quickly filled inside and then additional deposition may be performed on the outer surface, so that the deposition may be formed thickly on the outer surface. In this case, deterioration may be accelerated during charge and discharge, and during electrode manufacturing, materials with small particle sizes may coagulate with each other, resulting in significant deterioration of the coagulated portion. Furthermore, if the diameter of the porous carbon support is too large, uniform coating of the slurry on the current collector during electrode manufacturing may be difficult, resulting in reduced capacity uniformity.

[0091] In one example, the porous carbon support 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 40% or less. The ratio of the volume of the macropores to the total pore volume of the porous carbon support may be 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, or 15% 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 ratio of the macropores of the porous carbon support is too high, the mechanical strength of the electrode material manufactured from the silicon-carbon composite particles may be reduced. In addition, local aggregation of silicon may occur inside the electrode material, which may generate stress due to volume expansion during repeated charge / discharge processes, which may cause damage to the electrode material.

[0092] Silicon-carbon (Si-C) composite particles can be manufactured by including the steps of: step 1-1 of preparing a porous carbon support; and step 1-2 of depositing silicon (Si) on the surface of the porous carbon support.

[0093] The porous carbon support of step 1-1 can be commercially available and can have the manufacturing method and properties described above.

[0094] The above deposition in steps 1 and 2 can be performed at a deposition temperature of 300°C to 600°C and under an atmosphere supplying silane (SiH4) gas.

[0095] Additionally, the silane gas supply can be performed at 50 sccm to 500 sccm.

[0096] As a preferred embodiment, the deposition can be performed under the conditions of a temperature of 300°C to 600°C and a flow rate of 150 sccm to 500 sccm and an atmosphere in which silane (SiH4) gas is supplied by the above method. The deposition can be performed, for example, using chemical vapor deposition (CVD) and under atmospheric pressure conditions, but is not limited thereto. Through the deposition, silicon can be deposited on the inner surface and / or the outer surface of the porous carbon support according to the present invention.

[0097] Additionally, before the deposition in step 1-2, the porous carbon support prepared in step 1-1 may be subjected to a further pretreatment process, and then the deposition may be performed using this.

[0098] As a preferred example, a pretreatment process can be performed in which the porous carbon support of step 1-1 is immersed and stirred in an inorganic acid aqueous solution, and acidification, washing, and drying are sequentially performed.

[0099] 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.

[0100] And, the concentration of the inorganic acid in the inorganic acid aqueous solution may be 0.2 to 5.0 M, preferably 0.3 to 1.2 M, and more preferably 0.4 to 1.0 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 5.0 M, there may be a problem that the pores in the porous carbon support collapse, lowering the specific surface area and reducing the number of micropores and / or mesopores. Therefore, it is appropriate to perform the purification with an inorganic acid aqueous solution within the above concentration range.

[0101] And, the mixing ratio of the porous carbon support and the inorganic acid aqueous solution is appropriate to mix the powder and the inorganic acid aqueous solution at a weight ratio of about 1:8 to 12, preferably at a weight ratio of about 1:9 to 11.

[0102] In addition, the acid purification is preferably performed by immersing and stirring the porous carbon support in an aqueous inorganic acid solution for 2 to 24 hours, preferably when the concentration of the inorganic acid is about 0.5 to 1.2 M, for 6 to 24 hours, more preferably 12 to 24 hours. At this time, if the acid purification time is less than 2 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 may collapse.

[0103] And, when the acidification is completed, the porous carbon support is separated from the inorganic acid aqueous solution and obtained, and the separation method can be performed by a general method used in the art and is not particularly limited.

[0104] Then, the porous carbon support is washed, and in a preferred embodiment, washing is performed at least once with distilled water at 60 to 80°C.

[0105] 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.

[0106] The porous carbon support purified by performing the above pretreatment process is a high-purity powder with very low metal impurities.

[0107] For a specific example, the porous carbon support of step 1-1 may contain Na 18 to 280 ppm, Mg 2 to 10 ppm, Al 5 to 40 ppm, Si 10 to 500 ppm, K 2 to 20 ppm, Ca 5 to 80 ppm, Cr 10 to 200 ppm, Mn 10 to 90 ppm, Fe 70 to 1000 ppm and Ni 15 to 100 ppm, preferably Na 18 to 200 ppm, Mg 3.0 to 8.5 ppm, Al 5 to 35 ppm, Si 20 to 300 ppm, K 2 to 20 ppm, Ca 20 to 80 ppm, Cr 20 to 150 ppm, Mn 10 to 80 ppm, Fe 100 to 800 ppm and Ni 15 to When the porous carbon support is sequentially subjected to the pretreatment process, the purified porous carbon support may contain 85 ppm, more preferably 18 to 22 ppm of Na, 4.0 to 7.0 ppm of Mg, 10 to 13 ppm of Al, 28 to 35 ppm of Si, 2 to 20 ppm of K, 45 to 70 ppm of Ca, 30 to 45 ppm of Cr, 15 to 25 ppm of Mn, 140 to 200 ppm of Fe and 20 to 30 ppm of Ni, and more preferably 5 to 35 ppm of Na, 3 ppm or less of Mg, 20 ppm or less of Al, 30 ppm or less of Si, 20 ppm or less of K, 10 ppm or less of Ca, 10 to 65 ppm of Cr, 20 ppm or less of Mn, 100 ppm or less of Fe and 10 ppm or less of Ni. It may contain Na 10 to 25 ppm, Mg 3.0 ppm or less, Al 5 to 20 ppm, Si 5 to 25 ppm, K 20 ppm or less, Ca 20 ppm or less, Cr 10 to 45 ppm, Mn 10 ppm or less, Fe 80 ppm or less, and Ni 10 ppm or less, and more preferably Na 15.0 to 23.0 ppm, Mg 3.0 ppm or less, Al 5.0 to 40 ppm, and Si 5.0 to 23.It may contain 0 ppm, Ca 1.0 to 19.0 ppm, Cr 10 to 43 ppm, Mn 1.0 to 8.0 ppm, Fe 20 to 75 ppm, and Ni 7.5 ppm or less.

[0108] In addition, when the inorganic acid aqueous solution used in the acidification agent is a 0.5 M inorganic acid aqueous solution, the rate of change in oxygen content in the porous carbon support obtained through the pretreatment process can satisfy the following equation 1.

[0109] [Equation 1]

[0110] 1.8 < B / A < 4.2, preferably 3.0 < B / A < 4.0, more preferably 3.2 ≤ B / A ≤ 3.9

[0111] In Equation 1, A is the oxygen content (%) in the porous carbon support before the pretreatment process, and B is the oxygen content (%) in the porous carbon support after the pretreatment process is completed.

[0112] In addition, when the inorganic acid aqueous solution used in the acidification process is a 1.0 M inorganic acid aqueous solution, the rate of change in oxygen content in the porous carbon support obtained through the pretreatment process can satisfy the following equation 2.

[0113] [Equation 2]

[0114] 4.8 < C / A < 6.0, preferably 4.9 < C / A < 5.8, 4.9 ≤ C / A ≤ 5.5

[0115] In Equation 2, A is the oxygen content (%) in the porous carbon support before the pretreatment process, and C is the oxygen content (%) in the porous carbon support after the pretreatment process is completed.

[0116] In addition, when the inorganic acid aqueous solution used in the acidifying agent is a 0.5 M inorganic acid aqueous solution and the acid washing is performed for 24 hours, the porous carbon support obtained by performing the pretreatment process may have a specific surface area change rate of -4.00 to 4.00%, a micropore volume change rate of -5.00 to 18.00%, and a mesopore volume change rate of -2.00 to 3.00%, and preferably, a specific surface area change rate of 0.50 to 2.50%, a micropore volume change rate of -5.00 to 5.00%, and a mesopore volume change rate of -2.00 to 2.00%.

[0117] In addition, when the inorganic acid aqueous solution used in the acidifying agent is a 1.0 M inorganic acid aqueous solution and the acid washing is performed for 24 hours, the porous carbon support obtained by performing the pretreatment process may have a specific surface area change rate of -4.00 to 6.50%, a micropore volume change rate of 0 to 15.00%, and a mesopore volume change rate of 0 to 1.50%, and preferably, a specific surface area change rate of 0.20 to 2.50%, a micropore volume change rate of 0 to 5.00%, and a mesopore volume change rate of 0 to 1.00%.

[0118] In addition, the BET specific surface area of ​​the purified porous carbon support is 500 m 2 / g ~ 3,200 m 2 / g, preferably 600 m 2 / g ~ 2,500 m 2 / g, more preferably 700 m 2 / g ~ 1,600 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 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 on the inner surface of the porous carbon support.

[0119] Additionally, the carbon support may include a nonporous carbon support including at least one of hard carbon and soft carbon.

[0120] At this time, if the carbon support is hard carbon, the hard carbon can be manufactured by a method including the steps of (1') synthesizing pitch by thermal decomposition and condensation polymerization of petroleum-based raw materials, (2') solidifying and pelletizing the pitch to obtain pellet-like pitch, or solidifying, pelletizing, and pulverizing the pitch to obtain powder-like pitch, (3') stabilizing the pellet-like pitch or powder-like pitch, and (4') carbonizing the stabilized pitch to obtain hard carbon.

[0121] At this time, since the description of the above steps (1') to (4') may be the same as the description of the above steps (1) to (4), a detailed description will be omitted.

[0122] Meanwhile, the pitch for manufacturing the hard carbon may be at least one of an isotropic pitch and an anisotropic pitch, and it is more advantageous to achieve the purpose of the present invention to be an isotropic pitch.

[0123] In addition, when the carbon support is soft carbon, the soft carbon can be manufactured by a method including the steps of (1") synthesizing pitch by thermal decomposition and condensation polymerization of petroleum-based raw materials, (2") solidifying and pelletizing the pitch to obtain pellet-like pitch, or solidifying, pelletizing, and pulverizing the pitch to obtain powder-like pitch, (3") stabilizing the pellet-like pitch or powder-like pitch, and (4") carbonizing the stabilized pitch to obtain soft carbon.

[0124] At this time, the description of the above steps (1") and (2") may be the same as the description of the above steps (1) and (2), so a detailed description will be omitted.

[0125] The above step (3") and the step (4") described below may be performed as a series of steps in a rotary kiln, as in the above-described steps (3) and (4), or may be performed as a series of steps by placing the material in a crucible and placing it in an oven. Preferably, it may be advantageous to achieve the purpose of the present invention to perform the series of steps by placing the material in a crucible and placing it in an oven.

[0126] Meanwhile, since the description of the contents other than the above step (3") may be the same as the description of the above step (3), a detailed description will be omitted.

[0127] In addition, the above step (4") is a step of carbonizing the stabilized pitch to obtain soft carbon, and through carbonization of the stabilized pitch, other functional groups included in the pitch are removed, and soft carbon composed of substantially pure carbon can be obtained.

[0128] In a specific embodiment of the present invention, the carbonization in step (4") may be performed under an inert gas atmosphere. In a preferred specific embodiment of the present invention, the carbonization in step (4") may be performed under a nitrogen or argon atmosphere, but is not particularly limited thereto.

[0129] In a specific example of the present invention, the carbonization in step (4") may be performed at a temperature of 1,000°C to 2,700°C, preferably 1,200°C to 2,200°C. If the temperature during the carbonization in step (4") is lower than this range, the crystal structure of carbon may not develop sufficiently, and if the temperature during the carbonization is higher than this range, the carbonization yield may decrease.

[0130] In a specific example of the present invention, the carbonization in step (4") can be performed under a flow rate condition of an inert gas, preferably argon, of 0.1 to 30 ml / min, preferably 0.1 to 10 ml / min. When the carbonization is performed under this inert gas flow rate condition, the stabilized pitch can be sufficiently carbonized.

[0131] In a specific example of the present invention, the carbonization in step (4") can be performed for 0.5 to 5 hours, preferably 1 to 3 hours. When the carbonization in step (4") is performed for this period of time, the stabilized pitch can be sufficiently carbonized.

[0132] Meanwhile, since the description of the contents other than the above step (4") may be the same as the description of the above step (4), a detailed description will be omitted.

[0133] Meanwhile, the pitch for manufacturing the soft carbon may be at least one of an isotropic pitch and an anisotropic pitch, and preferably, an anisotropic pitch may be more advantageous in achieving the purpose of the present invention.

[0134]

[0135] The coating layer may include pitch.

[0136] Pitch, which can be incorporated into the coating layer, is a solid organic substance at room temperature or a residue from the thermal decomposition of tar distillation. It consists of a complex mixture of numerous highly aromatic hydrocarbons and heterocyclic compounds. Pitch does not have a constant melting point but rather a wide softening range, with a softening temperature ranging from approximately 320K to 570K, depending on its molecular weight and composition.

[0137] The pitch of the present invention may include at least one selected from petroleum pitch, coal tar pitch, and mesogenic pitch, and preferably may include petroleum pitch.

[0138] Specifically, the coating layer can be formed by coating pitch on the surface of an electrode active material including silicon and then carbonizing it. That is, the coating layer can include carbonized pitch.

[0139] More specifically, the carbonized pitch, preferably petroleum pitch, may be carbonized at a temperature of 300 to 900°C, preferably 400 to 800°C, and more preferably 450 to 750°C for 60 to 300 minutes, and preferably 120 to 240 minutes. At this time, if the carbonization temperature is less than 300°C, residual components having aromatic rings of the petroleum pitch may remain, which may cause a problem of performance degradation during electrode manufacturing, and if it exceeds 900°C, amorphous silicon particles may form crystals, which may cause a problem of reduced capacity and / or life performance of the electrode. In addition, if the carbonization time is less than 60 minutes, there may be a problem of coating layer peeling due to a thick coating caused by insufficient heat treatment, and if it exceeds 300 minutes, there may be a problem of the coating layer being too thin due to excessive heat treatment, which may cause a problem of the petroleum pitch coating having little effect.

[0140] Meanwhile, the coating layer coated on the surface of the electrode active material refers to a coating layer that is coated not only on the surface of the electrode active material exposed to the outside but also on the surface of the electrode active material located inside. Specifically, the electrode active material is a porous material having pores on the outside and / or the inside. For example, when a coating layer is formed using petroleum pitch, the petroleum pitch penetrates and coats not only the outside surface of the electrode active material but also the inside surface of the electrode active material through the pores, thereby not only partially or entirely blocking the pores of the electrode active material, but also coating the outside surface of the electrode active material with a certain thickness to form a coating layer.

[0141]

[0142] In addition, the secondary battery electrode material of the present invention can satisfy the following condition (1).

[0143] (1) A:B = 1:0.03 ~ 0.06, preferably A:B = 1:0.038 ~ 0.058, more preferably A:B = 1:0.043 ~ 0.053, even more preferably A:B = 1:0.045 ~ 0.051

[0144] In the above condition (1), A represents the average particle size (㎛) of the electrode active material, and B represents the thickness (㎛) of the coating layer. If, in condition (1), A:B is less than 1:0.03, there may be a problem that amorphous silicon particles are easily exposed to the electrolyte, and if A:B exceeds 1:0.06, not only may the capacity and / or lifespan decrease, but there may also be a problem that the rate-dependent characteristics deteriorate.

[0145] In addition, the coating layer may have a thickness of 0.01 to 3 μm, preferably the coating layer may have a thickness of 0.05 to 1 μm, more preferably the coating layer may have a thickness of 0.1 to 0.8 μm, and even more preferably the coating layer may have a thickness of 0.2 to 0.5 μm. If the thickness is less than 0.01 μm, there may be a problem that the amorphous silicon may be easily exposed to the electrolyte due to the coating layer being too thin, and if it exceeds 3 μm, the coating layer may be too thick, so that lithium ions may not be easily transferred to the amorphous silicon, resulting in a decrease in capacity and lifespan as well as a problem that is not good in rate-dependent characteristics.

[0146]

[0147] In addition, the secondary battery of the present invention may be a lead (Pd) battery, a nickel-cadmium (NiCd) battery, a nickel-metal (Ni-Metal) hydrogen battery, a lithium ion (Li-ion) battery, a lithium ion polymer (Li-ion polymer) battery, a lithium-metal (Li-Metal) battery, or an all solid state battery.

[0148] Additionally, the electrode active material of the present invention may be a negative electrode active material.

[0149] Additionally, the secondary battery electrode material of the present invention may be a secondary battery negative electrode material.

[0150] Meanwhile, the secondary battery electrode material of the present invention may have a sphericity of 0.5 to 1, preferably 0.6 to 0.9, more preferably 0.7 to 0.9, and even more preferably 0.8 to 0.87, as measured using a particle shape analyzer. If the sphericity is less than 0.5, there may be a problem of short circuit occurrence.

[0151]

[0152] Meanwhile, the method for manufacturing a secondary battery electrode material of the present invention includes a first step and a second step.

[0153] First, in the first step of the method for manufacturing a secondary battery electrode material of the present invention, a coating layer can be formed on the surface of the electrode active material by coating the surface of the electrode active material with petroleum pitch. At this time, the electrode active material and / or the petroleum pitch are as described above, respectively.

[0154] Additionally, the first stage coating can be performed by dry coating using the mechano-fusion method.

[0155] Specifically, dry coating can be performed at a speed of 900 to 4,500 rpm, preferably 2,000 to 3,000 rpm, for 5 to 30 minutes, preferably 10 to 30 minutes, and more preferably 12 to 20 minutes. If the speed is less than 900 rpm, the shear force may be low, which may cause problems with the bonding force between the parent particles and the particles, that is, the coating layer peeling, and the spheroidization may not be sufficient. If the speed exceeds 4,500 rpm, the shear force may be too excessive, which may cause problems with damaging the parent particles and the particles. In addition, if the time is less than 10 minutes, sufficient mixing may not occur, which may cause problems with uneven dispersion. If the time exceeds 30 minutes, secondary particles may be formed by edge etching during the coating layer formation and spheroidization process, which may be reassembled, which may cause problems with a decrease in capacity during electrode manufacturing.

[0156]

[0157] Next, in the second step of the method for manufacturing a secondary battery electrode material of the present invention, a secondary battery electrode material can be manufactured by carbonizing an electrode active material having a coating layer formed on the surface.

[0158] At this time, carbonization can be performed at a temperature of 300 to 900℃, preferably 400 to 800℃, more preferably 450 to 750℃, for 60 to 300 minutes, preferably 120 to 240 minutes. If the carbonization temperature is less than 300℃, residual components having aromatic rings of petroleum pitch may remain, which may cause a problem of performance degradation during electrode manufacturing, and if it exceeds 900℃, amorphous silicon particles may form crystals, which may cause a problem of reduced capacity and / or life performance of the electrode. In addition, if the carbonization time is less than 60 minutes, there may be a problem of coating layer peeling due to thick coating caused by insufficient heat treatment, and if it exceeds 300 minutes, there may be a problem of the coating layer being too thin due to excessive heat treatment, which may cause a problem of the petroleum pitch coating having little effect.

[0159]

[0160] 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.

[0161]

[0162] Preparation Example 1: Preparation of a porous carbon support

[0163] 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 an average particle size of 1–30 mm.

[0164] After crushing the solid pitch pellets obtained above, they were placed in a rotary kiln with three zones to sequentially perform stabilization, carbonization, and activation. The conditions for stabilization, carbonization, and activation are as shown in Table 1 below.

[0165] The activated carbonized body, which was activated above, was pulverized using a pulverizer (NETZSCH, air jet mill) to produce a porous carbon support.

[0166]

[0167] Table 2 below shows 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 porous carbon supports was measured using a particle size analyzer (Horiba, Laser Particle Analyzer, LA-960V2) according to ASTM E112.

[0168]

[0169]

[0170] Preparation Example 2: Manufacturing of silicon-carbon (Si-C) composite particles

[0171] Silicon-carbon (C-Si) composite particles were prepared using the porous carbon support of Preparation Example 1 prepared above. 20 g of the porous carbon support was placed in a rotary kiln, and silane (SiH4) gas was injected to deposit silicon (Si) on the surface of the porous carbon support.

[0172] When depositing using silane gas, the pressure was performed at atmospheric pressure, and the temperature was 475°C and the flow rate was 300 sccm for 1 hour to manufacture silicon-carbon (C-Si) composite particles.

[0173]

[0174] Experimental Example 1: Measurement of the physical properties of silicon-carbon (Si-C) composite particles

[0175] The Si content in the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 was measured using XRF (Xray fluorescence spectroscopy), and the results are shown in Table 3 below.

[0176] In addition, the average particle size and tap density of the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 were measured, and the results are shown in Table 3 below.

[0177]

[0178]

[0179] Example 1: Preparation of secondary battery negative electrode material

[0180] (1) Using the mechano-fusion method, petroleum pitch was dry-coated on the surface of the negative electrode active material to form a coating layer on the surface of the negative electrode active material. At this time, the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 were used as the negative electrode active material, and the coating was performed at a speed of 2700 rpm for 15 minutes.

[0181] (2) A secondary battery negative electrode material was manufactured by carbonizing a negative electrode active material having a coating layer formed on its surface at a temperature of 700°C for 120 minutes. Meanwhile, the petroleum-based pitch forming the coating layer was coated on the surface of the negative electrode active material to a thickness of 0.3 μm.

[0182]

[0183] Example 2: Manufacturing of secondary battery negative electrode material

[0184] A secondary battery negative electrode material was manufactured using the same method as in Example 1. However, unlike Example 1, the coating was performed at a speed of 900 rpm for 15 minutes, and a secondary battery negative electrode material was finally manufactured.

[0185]

[0186] Example 3: Preparation of secondary battery negative electrode material

[0187] A secondary battery negative electrode material was manufactured using the same method as in Example 1. However, unlike Example 1, the coating was performed at a speed of 4500 rpm for 15 minutes, and a secondary battery negative electrode material was finally manufactured.

[0188]

[0189] Example 4: Manufacturing of secondary battery negative electrode material

[0190] A secondary battery negative electrode material was manufactured using the same method as in Example 1. However, unlike Example 1, the coating was performed at a speed of 2700 rpm for 5 minutes, and a secondary battery negative electrode material was finally manufactured.

[0191]

[0192] Example 5: Manufacturing of secondary battery negative electrode material

[0193] A secondary battery negative electrode material was manufactured using the same method as in Example 1. However, unlike Example 1, the coating was performed at a speed of 2700 rpm for 30 minutes, and a secondary battery negative electrode material was finally manufactured.

[0194]

[0195] Example 6: Preparation of secondary battery negative electrode material

[0196] (1) Using a wet coating method, petroleum pitch was coated on the surface of the negative electrode active material, thereby forming a coating layer on the surface of the negative electrode active material. Specifically, the negative electrode active material was placed in a tetrahydrofuran (THF) solvent in which petroleum pitch was dispersed, and then dispersed ultrasonically. Then, the tetrahydrofuran (THF) was separated and dried using an evaporator, thereby forming a coating layer on the surface of the negative electrode active material. At this time, the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 were used as the negative electrode active material.

[0197] (2) A secondary battery negative electrode material was manufactured by carbonizing a negative electrode active material having a coating layer formed on its surface at a temperature of 700°C for 120 minutes. Meanwhile, the petroleum pitch forming the coating layer was coated on the surface of the negative electrode active material to a thickness of 0.9 μm.

[0198]

[0199] Experimental Example 2: Measurement of Physical Properties of Secondary Battery Anode Materials

[0200] In Examples 1 to 6, the average particle size and tap density of each secondary battery negative electrode material were measured, and the results are shown in Table 4 below.

[0201]

[0202] Experimental Example 3: Measurement of sphericity

[0203] The sphericity of each of the secondary battery negative electrode materials in Examples 1 to 6 and the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 was measured using a particle shape analyzer, and the results are shown in Table 4 below.

[0204]

[0205]

[0206]

[0207] Manufacturing Example 1: Manufacturing of secondary battery coin cell

[0208] (1) A negative electrode slurry was prepared by mixing 3 g of the secondary battery negative electrode material manufactured in Example 1, 0.33 g of carbon black as a conductive material, and 0.32 g of LiPAA (lithium polyacrylate) as a binder.

[0209] (2) A copper (Cu) sheet was prepared as a negative electrode collector, and the prepared negative electrode material slurry was uniformly coated on one side of the negative electrode collector to a thickness of 100 μm using a doctor blade device to form a sheet, and then vacuum-dried at a temperature of 80℃ for 10 hours and punched to a diameter of 13.5 mm to manufacture a secondary battery coin cell. In addition, an electrolyte was filled in the manufactured secondary battery coin cell, and a 1.0 M LiPF6 solution containing 5 wt% FEC (Fluoroethylene carbonate) was used as the electrolyte. In addition, the 1.0 M LiPF6 solution was a solvent in which EC (Ethylene Carbonate) and EMC (Ethyl methyl carbonate) were mixed in a 3:7 volume% ratio.

[0210]

[0211] Manufacturing Examples 2 to 6 and Comparative Manufacturing Example 1: Manufacturing of secondary battery coin cells

[0212] A secondary battery coin cell was manufactured using the same method as Manufacturing Example 1. However, unlike Manufacturing Example 1, Manufacturing Example 2 used the secondary battery negative electrode material manufactured in Example 2 instead of the secondary battery negative electrode material manufactured in Example 1, Manufacturing Example 3 used the secondary battery negative electrode material manufactured in Example 3 instead of the secondary battery negative electrode material manufactured in Example 1, Manufacturing Example 4 used the secondary battery negative electrode material manufactured in Example 4 instead of the secondary battery negative electrode material manufactured in Example 1, Manufacturing Example 5 used the secondary battery negative electrode material manufactured in Example 5 instead of the secondary battery negative electrode material manufactured in Example 1, Manufacturing Example 6 used the secondary battery negative electrode material manufactured in Example 6 instead of the secondary battery negative electrode material manufactured in Example 1, and Comparative Manufacturing Example 1 used the silicon-carbon (Si-C) composite particles manufactured in Preparation Example 2 instead of the secondary battery negative electrode material manufactured in Example 1.

[0213]

[0214] Experimental Example 4: Measurement of electric capacity, initial charge-discharge efficiency (ICE), and charge-discharge efficiency after 50 charge-discharge cycles.

[0215] Using a charger / discharger (WBCS3000, Wonatech), the electric capacity (=charge capacity and discharge capacity), initial charge / discharge efficiency (ICE), and charge / discharge efficiency after 50 charge / discharge cycles of the secondary battery coin cells manufactured in Manufacturing Examples 1 to 6 and Comparative Manufacturing Example 1 were measured, and the results are shown in Table 5 below.

[0216]

[0217] As can be seen in Table 5, it was confirmed that the secondary battery coin cell manufactured in Manufacturing Example 1 had excellent electric capacity, initial charge / discharge efficiency, and charge / discharge efficiency after 50 charge / discharge cycles.

[0218]

[0219] The above illustrates and describes specific embodiments. However, the invention is not limited to the aforementioned embodiments, and those skilled in the art will readily appreciate that various modifications and implementations can be made without departing from the spirit and scope of the invention as set forth in the claims below.

Claims

1. Electrode active material containing silicon (Si); and A coating layer coated on the surface of the electrode active material; A secondary battery electrode material, wherein the coating layer comprises carbonized petroleum pitch.

2. In paragraph 1, The above carbonized petroleum pitch is a secondary battery electrode material carbonized at a temperature of 300 to 900°C for 60 to 300 minutes.

3. In paragraph 1, The above electrode active material is a secondary battery electrode material, which is a silicon-carbon (Si-C) composite particle containing 5 to 80 wt% of silicon.

4. In paragraph 3, A secondary battery electrode material, wherein the above silicon-carbon (Si-C) composite particles have an average particle size of 4.0 to 8.0 μm and a tap density of 0.4 to 0.9 g / ml.

5. In the third paragraph, the silicon-carbon (Si-C) composite particles carbon support; and A secondary battery electrode material comprising silicon (Si) deposited on the surface of the carbon support.

6. In paragraph 1, The above secondary battery electrode material is a secondary battery electrode material that satisfies the following condition (1). (1) A : B = 1 : 0.03 ~ 0.06 In the above condition (1), A represents the average particle size (㎛) of the electrode active material, and B represents the thickness (㎛) of the coating layer.

7. In paragraph 6, The above coating layer is a secondary battery electrode material having a thickness of 0.01 to 3 μm.

8. In paragraph 1, The above secondary battery electrode material is a secondary battery electrode material having a sphericity of 0.5 to 1.

9. In paragraph 1, The secondary battery is a lead (Pd) storage battery, a nickel-cadmium (NiCd) battery, a nickel-metal (Ni-Metal) hydrogen battery, a lithium ion (Li-ion) battery, a lithium ion polymer (Li-ion polymer) battery, a lithium-metal (Li-Metal) battery, or an all-solid-state battery, a secondary battery electrode material.

10. In paragraph 1, The above electrode active material is a negative electrode active material, a secondary battery electrode material.

11. In paragraph 1, The above secondary battery electrode material is a secondary battery negative electrode material.

12. A first step of forming a coating layer on the surface of the electrode active material by coating the surface of the electrode active material with petroleum pitch; and A second step of manufacturing a secondary battery negative electrode material by carbonizing an electrode active material having a coating layer formed on the surface; A method for manufacturing a secondary battery electrode material, comprising:

13. In paragraph 12, A method for manufacturing a secondary battery electrode material, wherein the coating in the first step is dry coating using a mechano-fusion method.

14. In paragraph 13, A method for manufacturing a secondary battery electrode material, wherein the above dry coating is performed at a speed of 900 to 4,500 rpm for 5 to 30 minutes.

15. In paragraph 12, A method for manufacturing a secondary battery electrode material, wherein the carbonization in the second step is performed at a temperature of 300 to 900°C for 60 to 300 minutes.

Images