Method for manufacturing silicon-carbon composite materials

Abstract

The present invention provides a manufacturing method that can recover silicon-carbon composite materials in high yields and is also applicable to scale-up production. [Solution] 1. A method for producing a silicon-carbon composite material using a reactor having a tubular chamber rotatable about a longitudinal axis, comprising: (1) providing a tubular chamber with a carbon-based material comprising a carbon support and, optionally, a catalyst; (2) heating the tubular chamber under a carrier gas flow; (3) rotating the tubular chamber; (4) introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5) In the rotating tubular chamber, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 5 A step of performing a heat treatment at a pressure of 100 Pa or more; (6) recovering the resulting product; and The method includes the following.

Description

[Technical field]

[0001] The present invention relates to a method for producing carbon-silicon composites containing carbon-based materials and silicon nanomaterials (particularly nanowires or nanoislands) carried out at above atmospheric pressure in a tubular chamber of a rotating reactor. The present invention also relates to a method for producing electrodes for lithium-ion batteries. [Background technology]

[0002] The energy storage capacity of lithium-ion battery (LIB) technology has been increasing since its market introduction in 1991. However, next-generation LIBs require higher energy density (kWh / L) for a given battery volume and lower cost ($ / KWh), especially for electric vehicle applications. Current battery active materials (both anode and cathode) have already reached their theoretical limits, and battery manufacturers are seeking more efficient materials to meet market demands.

[0003] Today, graphite is the almost exclusive anode material used, but it occupies more space than any other component, making it the weak link in batteries. Over the past two decades, several anode materials have been developed to improve the storage capacity. Among them, silicon (Si) is the most promising candidate for a new anode material, as it can store nearly 10 times more energy than graphite. Although silicon has a high theoretical capacity, it has a large volume expansion and poor stability during lithium insertion and extraction.

[0004] Silicon nanowires (SiNWs) are excellent candidates for LIB anode materials in terms of specific capacity and cycle life due to their perfect strain and volume conformance. Cui et al., Nature Nanotechnology, 2008, 31-35 (Non-Patent Document 1) disclose a high-performance lithium battery anode using silicon nanowires grown directly on the current collector. However, integrating this new electrode technology into current battery manufacturing lines imposes a significant burden on battery manufacturers. In contrast, the combination of silicon nanowires and graphite / carbon could be one of the desirable strategies as a complete "drop-in solution". The industrial production of such composites at an acceptable cost is a key challenge for the battery market.

[0005] The various SiNW manufacturing technologies are mainly divided into two synthesis methods: bottom-up (growing nanowires from elemental silicon) and top-down (etching bulk silicon). The top-down method is characterized by the waste of much of the raw silicon and the unavoidable use of hazardous chemicals. The bottom-up method is generally based on chemical vapor deposition (CVD) and can produce high-quality nanowires.

[0006] Current "fixed-bed" CVD equipment for growing SiNWs is inadequate to meet market demands, as only limited contact of precursor gases with the two-dimensional surfaces decorated with metal nanoseeds allows production of small quantities.

[0007] There have been some attempts to synthesize SiNWs in vertical "fluidized bed" CVD reactors to increase the contact surface in three dimensions (e.g., US 2011 / 309306 A1, etc.). Unfortunately, classical "fluidized bed" CVD reactors have proven to have very limited economic and technical feasibility due to 1) decreasing volumetric productivity (mass of product / volume of reactor) as the manufacturing scale increases, and 2) handling very large amounts of reactant / carrier gases and composite materials, and the high costs of separating nano- and micro-sized materials from gases on an industrial scale.

[0008] WO 2018 / 013991 discloses a process for producing carbon-SiNW composites in a mechanical rotating fluidized bed reactor that can be used in batch or semi-continuous mode. The process is based on the use of a tumbler filled with carbon-based material and is carried out under low pressure. This process allows the production of materials with a Si content of up to 32% by weight on the kilogram scale. The process has some major limitations, such as the small size of the tumbler restricting the reaction zone of the CVD chamber and the need for rails, gas inlets, gas outlets, gear mechanisms and pressure regulators for the connection and control of the tumbler, making the device complex from a technical, process and economic point of view. The mechanism is equipped with a cyclone to collect particles larger than 5 μm in size by air sieving, which limits the range of powders that can be used with this process.

[0009] Recently, another example of the preparation of carbon-SiNW composites was reported (Energy&Fuels, 2021, 35, 2758-2765 (Non-Patent Document 2)). The authors showed the possibility of producing SiNW / graphite composites from chloromethylsilane and graphite powder using a simple rotary furnace. Under the reported conditions, a large part of the silicon / graphite composite is lost during the reaction. In addition to the low yield, the need for a gas-solid separator (filter or cyclone) at the exhaust of the gas line is inconvenient for industrialization of this method.

[0010] WO 2013 / 016339 (Patent Document 3) discloses a method for producing nanostructures, particularly silicon NWs, using copper-based catalytic materials. The reaction can be carried out under mixing or stirring and controlled pressure. It is disclosed that the pressure can be extremely low. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] US Patent Application Publication No. 2011 / 309306 [Patent Document 2] International Publication No. 2018 / 013991 [Patent Document 3] International Publication No. 2013 / 016339 [Non-patent literature]

[0012] [Non-Patent Document 1] Cui et al., High-performance lithium battery anodes using silicon nanowires. Nature Nanotechnology, 2008, 31-35 [Non-Patent Document 2] Liu, B.; Huang, P.; Xie, Z.; Huang, Q. Large-Scale Production of a Silicon Nanowire / Graphite Composites Anode via the CVD Method for High-Performance Lithium-Ion Batteries. Energy Fuels 2021, 35, 2758-2765 Summary of the Invention [Problem to be solved by the invention]

[0013] In view of the above, there has been a demand for a new, highly efficient method capable of producing high-performance silicon-graphite negative electrode materials for use as negative electrode active materials in lithium-ion batteries in high yields and capable of being carried out on an industrial scale.

[0014] There was a need for a process that could be implemented using existing industrial reactors / equipment with only minor modifications. There was a need for a method that would allow for easy separation of powders and gases after synthesis. [Means for solving the problem]

[0015] This invention presents a novel method for fabricating silicon nanowire-carbon / graphite composites for energy storage, i.e., LIBs, which can be produced on a large / industrial scale and at a competitive cost.

[0016] A first aspect of the present invention is a method for producing a carbon-silicon composite material, comprising: The method is carried out in a tubular chamber of a reactor, said tubular chamber being rotatable about its longitudinal axis (XX), the method comprising: (1) introducing into the tubular chamber a carbon-based material including at least a carbon support and, optionally, a catalyst; (2) heating the tubular chamber under a carrier gas flow; (3) rotating the tubular chamber; (4) introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5) In the rotating tubular chamber, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 5 A step of performing a heat treatment at a pressure of 1 Pa or more; (6) recovering the resulting product; and The method includes: However, the step (3) may be started at any stage, either before or after the step (1), or before or after the step (2).

[0017] Another aspect of the invention is a method of manufacturing an electrode including a current collector, the method comprising: (i) carrying out the method disclosed above to prepare a carbon-silicon composite material; (ii) coating at least one surface of the current collector with a composition containing the carbon-silicon composite material as an active material; This is a method for providing the above.

[0018] In another aspect, the present invention relates to a method for producing an energy storage device, such as a lithium secondary battery, comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, the method comprising: carrying out the method disclosed above to form at least one electrode, preferably the negative electrode; This is a method for providing the above.

[0019] In a preferred embodiment, the pressure in step (5) is 1.05×10 5 ~10 6 It is Pa. In a preferred embodiment, the temperature in step (5) is in the range of 350°C to 850°C.

[0020] In a preferred embodiment, the carbon-based material is selected from graphite, graphene and carbon, preferably from graphite powder having an average particle size of 0.01 to 50 μm.

[0021] In a preferred embodiment, the carbon-based material carries catalyst particles on its surface. In a preferred embodiment of the present invention, the catalyst is selected from metals, bimetallic compounds, metal oxides, metal nitrides, metal salts and metal sulfides.

[0022] In a preferred embodiment, the reactive silicon-containing mixed gas stream comprises at least a reactive silicon species and a carrier gas.

[0023] In a preferred embodiment, the reactive silicon species is selected from silane compounds, preferably the reactive silicon species is silane (SiH4).

[0024] In a preferred embodiment, the volume ratio of the carbon-based material, which includes the carbon support and optionally further includes the catalyst, based on the volume of the tubular chamber is 10% to 60%, more preferably 20% to 50%, and even more preferably 30% to 50%.

[0025] In a preferred embodiment, the flow rate of the reactive silicon-containing mixed gas in step (5) is in the range of 0.1 to 50 SLM (standard liters per minute), more preferably 0.5 to 40 SLM.

[0026] In one example, the flow rate of the reactive silicon-containing mixed gas in step (5) is in the range of 0.1 to 10 SLM (standard liters per minute), more preferably 0.5 to 5 SLM.

[0027] In a preferred embodiment, the rotation speed of the tubular chamber is in the range of 1 to 40 RPM (revolutions per minute).

[0028] In a preferred embodiment, the longitudinal axis XX of said tubular chamber makes an angle with the horizontal axis ranging from 0° to 20°.

[0029] In a preferred embodiment, the method further comprises the steps of: (1') re-introducing untreated carbon-based material into the tubular chamber; (2') heating the tubular chamber under a carrier gas flow; (3') rotating the tubular chamber; (4') introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5') In the rotating tubular chamber, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 5A step of performing a heat treatment at a pressure of 100 Pa or more; (6') recovering the resulting product. Contains at least one cycle.

[0030] In a preferred embodiment, the silicon-carbon composite material comprises a carbon-based material and a nanometer-sized silicon material.

[0031] In a preferred embodiment, the nanometer sized silicon material is a nanowire or nanoisland, more preferably a nanowire.

[0032] The method according to the present invention provides an anode active material containing a carbon-based support and silicon nanomaterials, particularly silicon nanowires, grown on the carbon-based support, which may further contain a carbon coating layer formed on the surface of the carbon-based support and the silicon nanomaterials, particularly silicon nanowires. Effect of the Invention

[0033] The method according to the invention has many advantages: the mechanical rotating fluidized bed reactor is more versatile than the classical one; the smaller heat and mass transfer in the rotating reactor compared to the classical fluidized bed configuration allows particles smaller than 30 μm and even smaller than 5 μm to be used with good efficiency in the chemical vapor deposition reaction; the behavior of the solids is not or is less affected by the gas flow depending on the position of the columnar part (horizontal or inclined), which increases the residence time of the reactants, reduces the gas consumption and makes gas-solid separators unnecessary or omittable. In fact, the generation of fines is significantly reduced in this type of reactor; the high pressure resistance and the overall mechanism are not complicated, which makes it easy to scale up to industrial production. The inventors of the invention have confirmed that by carrying out the method at pressures above atmospheric pressure, the chemical yield of the final composite material is very high. Moreover, such a procedure also reduces the need to collect particles and fines at the exhaust of the reactor.

[0034] The method according to the present invention provides an anode active material containing a carbon-based support and a silicon nanomaterial, particularly silicon nanowires, deposited on the carbon-based support. By directly growing the silicon nanomaterial, particularly silicon nanowires, on the carbon-based support, it is possible to reduce silicon / carbon contact loss during charging and discharging of the battery. If the material also has a carbon coating layer formed on the surface of the carbon-based support and on the surface of the silicon nanomaterial, particularly silicon nanowires, such an additional layer increases the bonding strength between the carbon-based support and the silicon nanomaterial, particularly silicon nanowires, and further improves the performance of the battery.

[0035] The method according to the invention has the advantage that, depending on the dimensions of the equipment, it can be carried out on a laboratory scale (up to 1 kg per day), on a pilot production scale (up to 100 kg per day) or on an industrial production scale (several tons per day).

[0036] The method according to the present invention makes it possible to economically produce, on an industrial scale, an anode active material in which silicon nanomaterials, particularly silicon nanowires, are uniformly deposited on the surface of a carbon-based material, preferably graphite. The uniform deposition of silicon nanomaterials, particularly silicon nanowires, improves the electrical conductivity of the final silicon-carbon composite, preferably silicon-graphite composite, and therefore improves the cycleability of the secondary battery. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a schematic cross-sectional view of a rotating fluidized bed reactor. [Diagram 2] 1 is a schematic of a process for producing silicon-carbon composites in a rotating fluidized bed reactor. [Diagram 3] 1 is a micrograph showing the microstructure of a silicon-carbon composite material according to Production Example 1 (Comparative Example) on a nanometer scale. [Figure 4] 1 is a micrograph showing the microstructure of a silicon-carbon composite material according to Production Example 1 (Comparative Example) on a millimeter scale. [Diagram 5] 1 is a micrograph showing, on a nanometer scale, the microstructure of a silicon-carbon composite material obtained by the method according to the present invention (Production Example 2). [Figure 6] 1 is a micrograph showing, on a millimeter scale, the microstructure of a silicon-carbon composite material obtained by the method according to the present invention (Production Example 2). [Figure 7] FIG. 1 is a schematic cross-sectional view of a Lodige type rotating fluidized bed reactor. [Figure 8] FIG. 1 is a schematic of a process for producing silicon-carbon composites in a Lödige rotating fluidized bed reactor. [Figure 9] FIG. 1 is a schematic cross-sectional view of a variant of a Loedige type industrial rotating fluidized bed reactor. [Figure 10] FIG. 10 is a schematic diagram of a process for producing silicon-carbon composites in a modified Loedige rotating fluidized bed reactor shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The phrase "consisting essentially of ... (one or more features) ..." means that the method or material of the invention may contain components or steps other than those explicitly stated, which do not materially affect the nature or characteristics of the invention.

[0039] The term "X to Y" is inclusive unless otherwise stated. This term means that the range covered includes values ​​X and Y, as well as all values ​​from X to Y.

[0040] A first aspect of the present invention is a method for producing a silicon-carbon composite material suitable for use as an anode active material in lithium-ion batteries by a chemical vapor deposition (CVD)-based process carried out in a rotating fluidized bed reactor.

[0041] The silicon-carbon composite material obtained by this method can be used as such or after post-production treatment as a silicon-carbon composite material for a negative electrode.

[0042] The present invention relates to a method for producing silicon-based nanostructured materials, the method being related to the production of silicon-carbon composite materials containing nanostructured silicon materials and carbon-based materials, obtained at high temperatures by chemical decomposition of reactive silicon-containing gas species mixed with a carrier gas (hereinafter this mixture is called reactive silicon-containing gas mixture), i.e. the method is based on the principle of chemical vapor deposition (CVD).

[0043] The term "nanostructured material" in the sense of the present invention is to be understood as meaning a material comprising individual particles in the form of aggregates or agglomerates, one or more of whose external dimensions range from 1 nm to 100 nm for at least 5% by weight, preferably at least 10% by weight, based on the total weight of the material.

[0044] "Composite material" refers to a material that is made up of two or more constituent materials that have significantly different physical or chemical properties.

[0045] The external dimensions of the particles can be determined by any known method, in particular by analysis of photographs of the composite material according to the invention obtained by scanning electron microscopy (SEM).

[0046] (Carbon-based materials) The method according to the invention uses at least one carbon-based material as a starting material.

[0047] Advantageously, the carbon-based material consists of micrometer-sized carbon in the form of a powder consisting of a "carbon support" or "carbon-based support" to which the catalyst is optionally bound.

[0048] In the present invention, carbon-based materials are used as supports for growing silicon nanomaterials, in particular silicon nanoislands or silicon nanowires, preferably silicon nanowires.

[0049] The carbon-based support may be any material selected from the group consisting of graphite, graphene, carbon, more specifically, natural graphite, artificial graphite, hard carbon, soft carbon, carbon nanotubes or amorphous carbon, carbon nanofibers, carbon black, expanded graphite, graphene, or a mixture of two or more thereof.

[0050] The present invention has the advantage that ultrafine graphite powder, a by-product of graphite production (grinding and rounding processes), can be used as a carbon-based support. In fact, rotating chamber reactors are suitable for the use of such materials. This is in contrast to other types of reactors equipped with filters and / or cyclones, which have difficulty in operation when particles smaller than 5 μm are introduced into the reaction chamber.

[0051] Preferably, the carbon support material consists essentially of natural or synthetic graphite, and more preferably consists solely of natural or synthetic graphite.

[0052] Preferably, based on the total mass of the carbon support, 75 mass% or more of the carbon support is composed of graphite, more preferably 80 mass% or more, even more preferably 90 mass% or more, even more preferably 95 mass% or more, and advantageously 99 mass% or more.

[0053] Preferably, the carbon support is on the micrometer scale. Advantageously, the carbon support has an average particle size of 0.01 to 50 μm, preferably 0.05 to 40 μm, more preferably 0.1 to 30 μm, advantageously 0.1 to 20 μm. For example, the average particle size of the carbon support can be measured using a laser diffraction method.

[0054] Preferably, the carbon support is in the form of particles, particle agglomerates, non-agglomerated flakes or agglomerated flakes.

[0055] Advantageously, the carbon support has a Brunauer-Emmett-Teller (BET) specific surface area of ​​1 to 100 m 2 / g, more preferably 3 to 70m 2 / g, more preferably 5 to 50 m 2 / g range.

[0056] In one preferred embodiment, the carbon-based material carries catalyst particles on its surface. If a catalyst is present, it is further advantageous that the surface of the carbon-based material is uniformly decorated with nanometer-sized catalyst particles or precursors thereof.

[0057] (catalyst) The process according to the invention can be carried out with or without a catalyst.

[0058] In one preferred embodiment, the method according to the invention comprises introducing at least one catalyst into the rotating chamber of the reactor.

[0059] The function of the catalyst is to form growth sites on the surface of the carbon support.

[0060] Preferably, the catalyst in this example is selected from metals, bimetallic compounds, metal oxides, metal nitrides, metal salts, metal sulfides and organometallic compounds.

[0061] Metal catalysts can include gold (Au), cobalt (Co), nickel (Ni), bismuth (Bi), tin (Sn), iron (Fe), indium (In), aluminum (Al), manganese (Mn), iridium (Ir), silver (Ag), copper (Cu), calcium (Ca), and mixtures thereof.

[0062] The binary metal compounds may include manganese platinum (MnPt3) or iron platinum (FePt). An example of the metal sulfide is tin sulfide (SnS). Metal oxides include ferric oxide (Fe2O3) and tin oxide (SnO 2-x) (0≦x<2). More preferably, the catalyst in this example is selected from metals and metal oxides.

[0063] When a catalyst is present, it is preferably selected from gold (Au), tin (Sn) and tin dioxide (SnO2). When a catalyst is present, it is advantageously tin dioxide (SnO2). Preferably, the catalyst in this example is in the form of particles, more preferably in the form of nanoparticles.

[0064] Preferably, the catalyst nanoparticles in this example have a longest dimension in the range of 1 nm to 100 nm, more preferably 1 nm to 50 nm, and even more preferably 5 nm to 30 nm.

[0065] When catalytic nanoparticles are present, they are advantageously spherical. In a preferred embodiment, the catalyst is in the form of nanometer-sized spherical particles with a particle size in the range of 1-30 nm, preferably 5 nm-30 nm.

[0066] Gold nanoparticles that can be used in the method of the present invention are prepared, for example, as disclosed in M. Brust et al., J. Chemical Society, Chemical Communications, 7(7):801-802, 1994.

[0067] Preferably, the metal constituting the catalyst is introduced in the form of a thin metal layer, which, when the method is started, liquefies under the action of heat, forming droplets of liquid metal, and is detached from the support. The metal may also be introduced in the form of a metal salt layer coating the growth substrate. When the growth process begins, this metal salt layer is reduced under the action of a reducing gas, for example hydrogen gas (H2).

[0068] The metal may be introduced in the form of an organometallic compound which decomposes during particle growth to deposit the metal in the form of nanoparticles or droplets on the carbon support.

[0069] In this example, the catalyst nanoparticles are preferably dispersed on the surface of the carbon support. The catalyst and the carbon support may or may not be in contact with each other.

[0070] In a preferred embodiment, the carbon support and catalyst are combined prior to introduction into the reactor.

[0071] For purposes of the present invention, the term "bonded" means that the carbon support and catalyst have been subjected to a bonding step equivalent to attaching or depositing at least a portion of the catalyst on at least a portion of the surface of the carbon support, i.e., at least a portion of the catalyst is linked to the surface of the carbon support, for example by physical bonding, adsorption, etc.

[0072] The catalyst and carbon support in this example are preferably used in a mass ratio (catalyst / carbon support) in the range of 0.01 to 1, more preferably 0.02 to 0.5, and even more preferably 0.05 to 0.1.

[0073] By binding the catalyst to the carbon support, multiple particle growth sites can be formed on the surface of the carbon support. In another embodiment, the method of the present invention is carried out without a catalyst.

[0074] Precursor Compositions for Silicon Nanomaterials, Particularly Nanowires The method of the present invention involves introducing a precursor composition for nanometer-sized silicon material (referred to as a "reactive silicon-containing gas species"), preferably a precursor composition for silicon nanoislands or nanowires, and more preferably a precursor composition for silicon nanowires, into a rotating fluidized bed reactor.

[0075] The precursor composition of the silicon particles comprises at least one precursor compound of a silicon nanomaterial, in particular a silicon nanowire.

[0076] The terms "precursor compound for nanometer-sized silicon material" and "precursor compound for silicon nanomaterial" refer to compounds that can be used to form nanometer-sized silicon material on the surface of a carbon support material by carrying out the method according to the present invention.

[0077] "Silicon nanoislands or nanowires precursor compound" refers to a compound that is capable of forming silicon nanoislands or nanowires on the surface of a carbon support material by carrying out the method of the present invention.

[0078] Preferably, the precursor compounds are in the form of reactive silicon-containing gas species mixed with a carrier gas (constituting a reactive silicon-containing gas mixture).

[0079] Preferably, the precursor compound (ie, the "reactive silicon-containing gas species") for nanometer-sized silicon materials (particularly silicon nanowires) is a silane compound or a mixture of silane compounds.

[0080] For purposes of the present invention, the term "silane compound" refers to a compound represented by the following formula (I): R1-(SiR2R3) n -R4(I) In the formula, n is an integer from 1 to 10; R1, R2, R3 and R4 are each independently hydrogen, C1-C 15 Alkyl groups, C6-C 12 Aryl groups, C7-C 20 It is selected from aralkyl groups and chloride. This refers to the compound.

[0081] The silicon-containing gas species of this embodiment is, among other compounds of formula (I): n is an integer from 1 to 5; R1, R2, R3 and R4 are independently selected from hydrogen, C1-C3 alkyl groups, phenyl and chloride; It is preferable to select from the compounds.

[0082] More preferably, n is an integer from 1 to 3, and R1, R2, R3 and R4 are each independently selected from hydrogen, methyl, phenyl and chloride.

[0083] Preferably, the reactive silicon-containing gas species in this embodiment is selected from silane, disilane, trisilane, chlorosilane, dichlorosilane, trichlorosilane, dichlorodimethylsilane, phenylsilane, diphenylsilane, triphenylsilane, or mixtures thereof. In one preferred embodiment, the reactive silicon-containing gas species is silane (SiH4).

[0084] In the most preferred embodiments, the reactive silicon-containing gas species consists essentially of, and better still consists only of, one or more precursor compounds of nanometer-sized silicon materials, particularly silicon nanowires.

[0085] In one preferred embodiment, the reactive silicon-containing gas species is introduced into the reactor in admixture with a carrier gas.

[0086] (Reactive silicon-containing gas mixture) The silicon material is obtained by high temperature chemical decomposition of reactive silicon-containing gas species, optionally in admixture with a carrier gas, hereinafter referred to as the "reactive silicon-containing gas mixture."

[0087] "Carrier gas" refers to a gas selected from a reducing gas, an inert gas, or a mixture thereof. Preferably, the reducing gas is hydrogen (H2). Preferably, the inert gas is selected from argon (Ar), nitrogen (N2), helium (He) or mixtures thereof.

[0088] Preferably, the carrier gas composition consisting of a reducing gas and an inert gas contains 0-99% by volume of the reducing gas, more preferably 20-99% by volume of the reducing gas.

[0089] In a preferred embodiment, the silicon-containing gas mixture is at least 0.5% by volume, preferably at least 10% by volume, more preferably at least 50% by volume, and even more preferably 100% by volume of silicon-containing gas species.

[0090] The carrier gas used in step (2) of the present process may be the same as or different from the carrier gas used in admixture with the silicon-containing gas species in step (5).

[0091] The ratio of silicon-containing gas species to carrier gas may be adjusted to different levels at each step of the method.

[0092] (Rotating Fluidized Bed Reactor) The rotating fluidized bed reactor described above and below is at least composed of a tubular chamber heated by a heating furnace, and a carbon-based material is introduced into the tubular chamber. A rotation mechanism is incorporated in the reactor. The reactor may have two tubular chambers. The tubular chamber can be tilted. The reactor further includes a product supply mechanism and a product discharge mechanism, enabling semi-continuous production of silicon-carbon composite materials. The rotating fluidized bed reactor has a reactor pressure control device, such as a needle valve, a pressure controller, etc.

[0093] Mechanical fluidized bed reactors differ from classical fluidized bed reactors in that, in addition to the gas flow, they use an external action to fluidize the powder bed by rotating the reactor along its longitudinal axis. A typical mechanical fluidized bed reactor is the Lödige type rotating fluidized bed reactor, where the fluidization is induced by the rotation of a tubular chamber.

[0094] One advantage of the method according to the invention is that it allows the industrial scale-up of carbon-silicon composites by chemical vapor deposition (CVD) based on a Lödige rotating fluidized bed reactor.

[0095] [Fluidized Bed Reactor - Batch Mode] The apparatus of a rotating fluidized bed reactor is shown in Figure 1. The reactor consists of a quartz tubular chamber 106 extending along a central longitudinal axis XX. The chamber 106 is surrounded and heated by a furnace 107, which can be heated by resistance heating, induction heating or infrared lamps. Once the carbon powder material 108 is charged, the chamber 106 is closed by two flanges 103, 109 at either end. Each flange sits on a bearing mechanism 104, 110. The bearing mechanism 104 is connected to a motor 105, which can rotate the chamber 106 about the longitudinal axis XX via the bearing mechanism 104.

[0096] The rotating fluidized bed reactor has a carrier gas inlet 101 at one end of the chamber 106 (also called the inlet of the chamber 106) and a reactive silicon-containing mixed gas inlet 102 at the same end of the chamber 106 as the carrier gas inlet 101. At the opposite end of the chamber 106 (also called the outlet of the chamber 106) there is a tubular gas cooler 111 and a needle valve 112 for full control of the reactor pressure. Between the needle valve 112 and the tubular gas cooler 111 there are dual vessel liquid traps 114a, 114b for valve protection and fines / silane by-product collection, one vessel 114a containing oil. At the outlet of the needle valve 112 there is a total gas outlet 113. At the outlet of the chamber 106 there is a pressure gauge 115 to measure the reactor pressure. FIG. 1 does not show the reactor controllers that monitor process parameters such as temperature, carrier gas flow rate, reactive silicon-containing gas mixture flow rate, and rotation speed.

[0097] [Continuous mode reactor] In Fig. 7 an industrial rotating fluidized bed reactor of the Lödige type is shown. It consists of a tubular chamber 701 extending along a central longitudinal axis XX. The chamber 701 is surrounded and heated by a single-zone or multi-zone furnace 702. The furnace is heated by resistance heating, induction heating or infrared lamps. The tubular chamber 701 is closed by at least two boundary mechanisms 703 at both ends of the chamber 701. A product feed mechanism 705 feeds the carbon material 704 at one end of the chamber 701. A motor 706 can rotate the chamber 701 while the boundary mechanism 703 remains stationary. The furnace 702 remains fixed on the device support 707.

[0098] The Lödige type rotating fluidized bed reactor can be tilted by a tilting mechanism 708. Preferably, the tilt angle α of the longitudinal axis XX of the reactor with the horizontal plane is less than or equal to 20°. The tilting mechanism 708 allows the carbon-based material to slide down from the product supply mechanism 705 to a product discharge mechanism 709 located at the opposite end of the chamber 701 at a speed that depends on the rotation speed and the tilt angle.

[0099] The Lödige type rotating fluidized bed reactor has a carrier gas inlet 710, at least one reactive silicon-containing mixed gas inlet 711, and an inert gas inlet 712, all three located at the end of the chamber 701 opposite the product supply mechanism 705. The reactor also has a total gas outlet 713 located at the same end as the product supply mechanism 705. These gas inlets and outlets may be preheated with corresponding mechanisms. These gas inlets and outlets may also incorporate valves 714, 718. The valve 718 of the total gas outlet 713 allows control of the pressure of the reactor and can be managed by at least one reactive silicon-containing gas detector 715 depending on the number of reactive silicon-containing gas sources used. A pressure gauge 719 indicates the pressure of the reactor.

[0100] The gas safety tank 717 is connected to the tubular chamber 701 through a rupture disk safety mechanism 716 located at the boundary mechanism 703. The rupture disk safety mechanism 716 may incorporate a pressure sensor (not shown). The valve 714 of the reactive silicon-containing gas mixture inlet 711 can be controlled by the pressure sensor of the rupture disk safety mechanism 716 for both safety and process efficiency / flexibility purposes. In fact, increasing the pressure of the silicon-containing gas species in the tubular chamber 701 allows the growth of the silicon material, i.e. its structure, to be controlled. In FIG. 7, the reactor controller monitoring the process parameters such as temperature, carrier gas flow rate, reactive silicon-containing gas mixture flow rate, tilt angle, rotation speed, and the product collection tank are not shown.

[0101] The product supply mechanism 705 may be an endless supply screw mechanism, a dispensing mechanism, or a funnel type mechanism, as may the product discharge mechanism 709. The latter may be equipped with a cooling mechanism.

[0102] Depending on the complexity of the manufacturing run, further devices may be incorporated into the tubular rotating chamber 701 and / or the process support 707 and / or the boundary mechanism 703. Such devices may include thermocouples, pressure sensors, optical systems, sealing mechanisms, sampling mechanisms, and even analytical devices for gas or product control.

[0103] The tubular rotating chamber 701 may have internal structures such as fixed fins, movable rods, movable balls, etc. The geometry, layout and number of fins, as well as the size and number of rods and balls, are dependent on the physical properties of the carbon-based material powder 704.

[0104] One of the advantages of the method according to the invention is that the mechanical fluidized bed reactor allows the scale of production to be easily scaled up to industrial scale compared to classical fluidized bed reactors. Powders with a particle size of less than 30 μm (Geldert powder classification group C), which are difficult to process in classical fluidized bed reactors, can be easily processed in this type of fluidized bed reactor. Moreover, in a rotating fluidized bed reactor, the behavior of the solid particles is not or is less affected by the gas flow, resulting in a much longer residence time of the reactants, which makes it possible to increase the production efficiency from a chemical and therefore economic point of view. The movement of the reactor causes the solid particles to move.

[0105] [Dual chamber reactor] FIG. 9 shows a variant of the industrial rotating fluidized bed reactor of the Lödige type described above. The reactor in this case consists of two tubular chambers 901.a, 901.b extending along a central longitudinal axis XX, each heated by a single-zone or multi-zone furnace 902. The tubular chambers 901.a, 901.b are closed by at least two fixed boundary mechanisms 903 and separated by a separation mechanism 918. The tubular chamber 901.a is intended for the preparation of silicon-carbon composites. The carbon material is introduced into the tubular chamber 901.a by a product feed mechanism 905. The tubular chamber 901.b (hereafter referred to as the granulation chamber) is used for granulation of the silicon-carbon composites. Granulation is the process of forming granules or particles from powdered substances, which results in granulation. The granulation chamber is fed with raw silicon-carbon composite material 904 by a separation mechanism 918, which results in silicon-carbon composite granules 919. A motor 906 can rotate the chamber. The furnace 902 remains fixed to the process support 907.

[0106] The Lödige rotating fluidized bed reactor can be tilted by a tilting mechanism 908. The tilting mechanism 908 allows the carbon-based material to spread in the tubular chamber 901.a, the silicon-carbon composite material 904 to slide from the chamber 901.a to the chamber 901.b via a separation mechanism 918, and the silicon-carbon composite granules 919 to the product discharge mechanism 909 at a speed depending on the rotation speed and the tilt angle. The Lödige rotating fluidized bed reactor has a carrier gas inlet 910, at least one reactive silicon-containing mixed gas inlet 911 connected to the preparation chamber 901.a, an inert gas inlet 912, and total gas outlets 913a, 913b. These gas inlets and outlets may be preheated by corresponding mechanisms. These gas inlets and outlets may also incorporate valves 914a, 914b, 914c. A valve 918 at the total gas outlet 913b of chamber 901.a allows full control of the reactor pressure and can be managed by at least one reactive silicon-containing gas detector 915 depending on the number of reactive silicon-containing gas sources used.

[0107] A pressure gauge 919 measures the reactor pressure. A gas safety tank 917 is connected to the tubular chamber 901.a through a rupture disk safety mechanism 916 located at the boundary mechanism 903. The rupture disk safety mechanism 916 may have a pressure sensor integrated therein. The valve 914c of the reactive silicon-containing gas mixture inlet 911 can be controlled by the pressure sensor of the rupture disk safety mechanism 916 for both safety and process efficiency / flexibility purposes. In fact, increasing the pressure of the silicon-containing gas species in the tubular chamber 901.a allows the growth of silicon material, i.e. its structure, to be controlled. In FIG. 9, the reactor controller monitoring process parameters such as temperature, carrier gas flow rate, reactive silicon-containing gas mixture flow rate, tilt angle, rotation speed, and product collection tank are not shown.

[0108] The product supply mechanism 905 may be an endless supply screw mechanism, a dispensing mechanism, or a funnel type mechanism, as may the product discharge mechanism 909. The latter may be equipped with a cooling mechanism.

[0109] The separation mechanism 918 acts as a link between the tubular chambers 901.a, 901.b and rotates similarly when the motor 906 is in use. The separation mechanism 918 incorporates a three-phase gear mechanism that remains closed during the preparation process in tubular chamber 901.a and the granulation process in tubular chamber 901.b, respectively, and opens when these processes are complete to allow the silicon-carbon composite material to slide from one chamber to the other. This means that a given batch of silicon-carbon composite material can be prepared in tubular chamber 901.a while another batch of silicon-carbon composite material is being granulated in tubular chamber 901.b.

[0110] Depending on the complexity of the manufacturing run, devices may be incorporated into the tubular rotating chamber 901 and / or the process support 907 and / or the boundary mechanism 903. Such devices may include thermocouples, pressure sensors, optics, sealing mechanisms, sampling mechanisms, and even analytical devices for gas or product control.

[0111] The tubular chamber 901.a may have internal structures such as movable rods, movable balls, etc. The size and number of the rods and balls are dependent on the physical properties of the starting carbon-based material powder. The tubular chamber 901.b may have internal structures such as fixed fins, etc. The geometry, layout and number of the fins are dependent on the physical properties of the silicon-carbon composite material 904.

[0112] (Method of manufacturing carbon-silicon composite materials) The method according to the present invention comprises the steps of: (1) introducing into a tubular chamber at least a carbon-based material, and optionally further a catalyst; (2) heating the tubular chamber under a carrier gas flow; (3) rotating the tubular chamber; (4) introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5) In the rotating tubular chamber, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 5 A step of performing a heat treatment at a pressure of 100 Pa or more; (6) recovering the resulting product; and Equipped with.

[0113] Most of the steps must be performed in the order listed above, although the rotation of step (3) may be initiated either before or after step (1), or before or after step (2).

[0114] [Process (1)] Preferably, the input volume ratio of the carbon-based material (including the carbon support and, optionally, the catalyst) based on the volume of the tubular chamber is 10% to 60%, more preferably 20% to 50%, and even more preferably 30% to 50%.

[0115] [Process (2) ~ Process (5)] Preferably, in step (2), the rate of temperature rise until the chamber reaches the desired temperature is in the range of 1° C. to 50° C. / min, more preferably 5° C. to 30° C. / min, and even more preferably around 10° C. / min.

[0116] Preferably, in step (5), the tubular chamber is maintained at a temperature in the range of 200°C to 900°C, more preferably 350°C to 850°C, even more preferably 450°C to 750°C. The furnace can be heated by resistance, induction or infrared lamps.

[0117] In step (5), the pressure in the tubular chamber is controlled to be preferably 1.02×10 5 Pa~5×10 6 Pa range, more preferably 1.05×10 5 Pa~10 6Pa, and more preferably 1.1×10 5 Pa~10 6 It is said to be in the Pa range.

[0118] Preferably, the combined treatment time of step (5) with the reactive silicon-containing gas mixture and heating in the rotating chamber is from 1 minute to 10 hours, advantageously from 5 minutes to 5 hours, and even more preferably from 15 minutes to 10 hours.

[0119] Preferably, the flow rate of the carrier gas in step (2) is in the range of 0.1 SLM to 50 SLM (standard liters per minute), more preferably 0.5 SLM to 40 SLM.

[0120] In one example, the flow rate of the reactive silicon-containing mixed gas in step (2) ranges from 0.1 SLM to 10 SLM (standard liters per minute), more preferably from 0.5 SLM to 5 SLM.

[0121] Preferably, the flow rate of the reactive silicon-containing mixed gas in step (5) is in the range of 0.1 SLM to 50 SLM (standard liters per minute), more preferably 0.5 SLM to 40 SLM.

[0122] In one example, the flow rate of the reactive silicon-containing mixed gas in step (5) ranges from 0.1 SLM to 10 SLM (standard liters per minute), more preferably from 0.5 SLM to 5 SLM.

[0123] The flow rates of the carrier gas and the reactive silicon-containing gas mixture may be the same or different.

[0124] The carrier gas used in step (2) of the present process may be the same as or different from the carrier gas used in admixture with the silicon-containing gas species in step (5).

[0125] The gas flow in step (2) reduces the amount of oxygen in the reactor chamber.

[0126] The gas flow in step (5) grows nanostructured silicon on the carbon-based support within the reactor chamber.

[0127] Preferably, upon completion of step (5), the flow of the reactive silicon-containing gas mixture is stopped and the tubular chamber is allowed to cool to room temperature under a flow of carrier gas.

[0128] Preferably, the rotation speed of said tubular chamber is in the range of 1 RPM to 40 RPM (revolutions per minute), preferably 1 RPM to 30 RPM, even more preferably 1 RPM to 20 RPM, and even more preferably 1 RPM to 15 RPM.

[0129] In one example, the rotation speed of the tubular chamber ranges from 1 RPM to 40 RPM (revolutions per minute), preferably from 10 RPM to 30 RPM, and more preferably from 15 RPM to 25 RPM.

[0130] In a first embodiment, the longitudinal axis XX of said tubular chamber is horizontal.

[0131] In a second embodiment, the longitudinal axis XX of said tubular chamber is inclined and makes an angle α with the horizontal plane. Advantageously, in this embodiment, said angle of inclination ranges from 1 to 20°, more preferably from 5 to 15°, advantageously around 10°.

[0132] In one advantageous embodiment, the process according to the invention further comprises, after step (6), (1') re-introducing untreated carbon-based material (including the carbon support and, optionally, the catalyst) into the tubular chamber; (2') heating the tubular chamber under a carrier gas flow; (3') rotating the tubular chamber; (4') introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5') In the rotating tubular chamber, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 5A step of performing a heat treatment at a pressure of 100 Pa or more; (6') recovering the resulting product. At least one cycle is performed.

[0133] The preferred embodiments of step (1') to step (6') are the same as the preferred embodiments of step (1) to step (6), respectively.

[0134] Advantageously, between two cycles, the heating of the tubular chamber may continue, whilst the rotation of the tubular chamber may be slowed down or stopped completely, and the gas flow as a carrier gas flow may continue.

[0135] The rotation in step (3') may be initiated before or after either step (1') or step (2'). Alternatively, the rotation may be continuous from one cycle to the next, and the speed of rotation may be changed between cycles.

[0136] [Additional process] In some embodiments, an optional step may be performed between steps (5) and (6), such as forming a carbon coating on the surface of the silicon-carbon composite, and in this case, an additional valve with one or more additional gas inlets for carbon-based gas species may be provided.

[0137] For example, the method may comprise the additional step of heat treating the silicon-carbon composite material obtained at the end of step (5) in the presence of a carbon source.

[0138] For example, the method may comprise the further step, prior to step (6), of injecting an inert gas into the tubular chamber to prevent oxygen contamination.

[0139] In one embodiment, the method according to the invention further comprises a step (G) of granulating the product obtained at the end of step (5) or step (5'). In this embodiment, the product obtained in step (5) or step (5') is introduced into a granulation chamber, which is rotated for a predetermined time. After granulation is deemed complete, the product is recovered (step (6)) and may be subjected to further post-processing steps, such as, for example, heat treatment.

[0140] [Method - Batch mode] FIG. 2 illustrates a method for producing silicon-carbon composites in a rotating fluidized bed reactor of the Lödige type, such as the reactor of FIG. 1. In step 201, a carbon-based powder material 108, optionally including a catalyst, is loaded into a quartz tubular chamber 106 by removing the flange 109. Once the carbon-based powder material 108 is loaded, the chamber 106 is closed with the flange 109 and placed on a bearing mechanism 110. A tubular cooling device 111, a needle valve 112, and a total gas outlet 113 are then connected to the flange 109 according to the arrangement shown in FIG. 1. In step 202, a carrier gas is supplied to the chamber 106 via the carrier gas inlet 101. In step 203, the rotation of the chamber 106 is started, and in step 204, the heating of the chamber 106 is started. Once the reactor reaches the desired temperature, in step 205, the temperature is stabilized for a certain amount of time.

[0141] In step 206, the carrier gas inlet 101 is closed and the reactive silicon-containing gas mixture inlet 102 is opened instead. The pressure is monitored by the needle valve 112 while heating is performed under the inert gas flow. The flow rate of the reactive silicon-containing gas mixture may be the same as that of the carrier gas in step 202. In step 207, the silicon source from the reactive silicon-containing gas mixture reacts with the carbon-based powder material for a predetermined time to form a silicon-carbon composite. The duration of the process depends on the silicon source and its concentration in the gas flow.

[0142] Once the production of the silicon-carbon composite is completed, in step 208, the reactive silicon-containing mixed gas inlet 102 is closed and the carrier gas inlet 101 is opened instead. The flow rate of the carrier gas may be the same as in step 202. At the same time, the furnace 107 is switched off and the chamber 106 is cooled to room temperature under the carrier gas flow (step 209). Once room temperature is reached, the rotation is stopped (step 210) and in step 211, the silicon-carbon composite is removed by disconnecting the tubular cooling device 111 from the flange 109 and removing the flange 109 from the bearing device 110 and the chamber 106.

[0143] [Method - Continuous Mode] FIG. 8 shows a method for producing silicon-carbon composites in a Lödige type rotating fluidized bed reactor such as the reactor of FIG. 7. The method begins with step 801, in which the process support 707 is tilted by the tilt mechanism 708. Rotation of the tubular rotation chamber 701 is then started at a desired rotation speed and the chamber is heated to a desired temperature. Then, in step 802, a carbon-based powder material 704, optionally including a catalyst, is loaded into the quartz tubular chamber 701 by opening the product supply mechanism 705. In step 803, the product supply mechanism 705 is closed while a carrier gas is supplied into the tubular rotation chamber 701 by the carrier gas inlet 710. The temperature is allowed to stabilize for a certain period of time.

[0144] Once the reactor has reached the desired temperature, in step 804, the carrier gas inlet 710 is automatically closed and instead the reactive silicon-containing gas mixture inlet 711 is opened. The flow rate of the reactive silicon-containing gas mixture may be the same as the flow rate of the carrier gas in step 801. In step 805, the silicon source from the reactive silicon-containing gas mixture reacts with the carbon-based powder material for a predetermined time depending on the silicon source and its concentration in the gas flow, thereby forming the silicon-carbon composite material. The total gas outlet 713 is kept closed to allow the pressure of the reactive silicon-containing gas inside the tubular chamber 716 to increase. When it is determined that the production of the silicon-carbon composite material is complete, the reactive silicon-containing gas mixture inlet 711 is closed and instead the inert gas inlet 712 is opened together with the total gas outlet 713. This allows the tubular rotation chamber 701 and the silicon-carbon composite material to be purged of all remaining reactive gas species.

[0145] The flow rate of the inert gas carrier gas and the flow rate of the reactive silicon-containing gas mixture may be the same in step 803 and / or step 804 and / or step 806. In step 807, the silicon-carbon composite material is removed by opening the product discharge mechanism 709.

[0146] At this point, a semi-continuous production mode 809 can be performed by repeating all of the above steps starting from step 802, where the product feed mechanism 705 is opened to re-introduce the powdered carbon-based material 704 into the tubular rotating chamber 701. The temperature of the chamber 701 is maintained while the rotation of the chamber 701 may be slowed down or stopped between the two cycles.

[0147] Step 808 allows the manufacturing process to be stopped for mechanical maintenance or safety reasons: under an inert atmosphere, the furnace 702 is switched off, the tubular chamber 701 is stopped from rotating and allowed to cool to room temperature, and the reactor is tilted back to horizontal if necessary.

[0148] [Method - Granulation mode] FIG. 10 shows a method for producing silicon-carbon composites in a modified Lödige type rotating fluidized bed reactor according to FIG. 9. In this method, first, in step 1001, the process support 907 is tilted by the tilting mechanism 908, and the rotation of the tubular rotating chambers 901.a, 901.b is started at a desired rotation speed, and each of the tubular chambers 901.a, 901.b is heated to a desired temperature. In step 1002, inert gas is supplied to both chambers from the inert gas inlet 912, and the temperature is stabilized for a certain period of time. Next, in step 1003, the product supply mechanism 905 is opened to introduce carbon-based powder material into one of the tubular chambers 901.a. In step 1004, the product supply mechanism 905 is closed, while carrier gas is supplied into the tubular rotating chambers 901.a by the carrier gas inlet 910.

[0149] Once the desired temperature is reached, in step 1005, the carrier gas inlet 910 is closed and instead the reactive silicon-containing gas mixture inlet 911 is opened. In step 1006, the silicon source from the reactive silicon-containing gas mixture reacts with the carbon-based powder material to form a silicon-carbon composite for a predetermined time depending on the silicon source and its concentration in the gas. The pressure of the reactive silicon-containing gas inside the tubular chamber 901.a is increased by closing the total gas outlet 913. When it is determined in step 1007 that the production of the silicon-carbon composite 904 is complete, the reactive silicon-containing gas mixture inlet 911 is closed and instead the inert gas inlet 912 is opened together with the total gas outlet 913. This purges the tubular rotation chamber 901.a and the silicon-carbon composite to remove all remaining reactive gas species.

[0150] Once the tubular chamber 901.a has been purged with inert gas, the separation mechanism 918 is opened and the silicon-carbon composite material 904 is transferred to the granulation chamber 901.b in step 1008. At this point, the method can be repeated from step 1002 through step 1008 to perform semi-continuous production 1012.

[0151] In step 1009, granulation of silicon-carbon composite 904 is initiated and carried out for a predetermined period of time by supplying inert gas or carrier gas as required via inert gas inlet 910 or carrier gas inlet 912. The resulting silicon-carbon composite granules 919 are then removed from the granulation chamber 901.b by product discharge mechanism 909. At this point, the method can be repeated from step 1009 to step 1010 to perform semi-continuous granulation 1013.

[0152] Step 1011 allows the manufacturing process to be stopped for mechanical maintenance or safety reasons: under an inert atmosphere, the furnace 902 is switched off, the tubular chamber 901 is stopped from rotating and allowed to cool to room temperature, and the reactor is tilted back to horizontal if necessary.

[0153] (Silicon-carbon composite material) According to the present invention, a silicon-carbon composite material can be obtained by carrying out the above method.

[0154] The silicon-carbon composite material obtained by this method contains a carbon-based material and a nanometer-sized silicon material, the carbon-based material including the aforementioned carbon support, and, optionally, a catalyst.

[0155] The catalyst and the carbon support may or may not be in contact with each other. When a catalyst is present, the catalyst is preferably in contact with the surface of the carbon support. The contact between the catalyst and the carbon support may be due to either chemical or physical adsorption.

[0156] If a catalyst is present, it is more preferably in the form of particles and well dispersed on the surface of the carbon support.

[0157] Preferably, the nanostructured silicon material is composed of silicon particles having at least one of their outer dimensions in the range of 10 nm to 500 μm, preferably in the range of 10 nm to 500 nm.

[0158] The silicon material obtained by chemical vapor deposition of silicon-containing gaseous species may be in the form of wires, worms, rods, filaments, islands, particles, films, sheets or spheres.

[0159] The presence or absence of a catalyst affects the type of silicon particles obtained.

[0160] In a preferred embodiment, the silicon particles are in the form of nanowires. Preferably, the silicon nanowires are obtained by a catalytic method.

[0161] The term "nanowire" within the meaning of the present invention is to be understood to mean an elongated object having a wire-like shape and a diameter of nanometers.

[0162] Preferably, the silicon nanowires have a diameter in the range of 1 nm to 100 nm, more preferably in the range of 10 nm to 100 nm, and even more preferably in the range of 10 nm to 50 nm.

[0163] Preferably, the average diameter of the silicon nanowires is in the range of 5 nm to 5 μm, more preferably 10 nm to 50 nm. Preferably, the average length of the silicon nanowires is in the range of 50 nm to 500 nm.

[0164] Nanoworms refer to certain preferred classes of nanowires that fall into the low aspect ratio range (ratio of average length to average diameter), that is, L / D ratios of 10 or less, more preferably 5 or less, advantageously 2 or less.

[0165] In another embodiment, the silicon particles are in the form of nanoislands. Preferably, the silicon nanoislands are obtained by a method carried out without a catalyst.

[0166] The term "nanoislands" within the meaning of the present invention is to be understood to mean objects of rounded shape and nanometer diameter.

[0167] Preferably, the silicon nanoislands have a diameter in the range of 1 nm to 100 nm, more preferably in the range of 10 nm to 100 nm, and even more preferably in the range of 10 nm to 50 nm.

[0168] Preferably, the average diameter of the silicon nanoislands is in the range of 5 nm to 5 μm, more preferably 10 nm to 50 nm.

[0169] The size of the silicon material may be measured by a number of techniques well known to those skilled in the art, such as, for example, by analysis of photographs taken by scanning electron microscopy (SEM) of one or more samples of the carbon-silicon composite material.

[0170] The silicon particles, preferably silicon nanowires or silicon nanoislands, constitute 1% to 70% by weight of the silicon-carbon composite, preferably 10% to 70% by weight, more preferably 20% to 70% by weight, even more preferably 30% to 70% by weight, advantageously 50% to 70% by weight.

[0171] Preferably, the silicon-carbon composite material is obtained in the form of a powder.

[0172] (Use of carbon-silicon composite materials) The silicon-carbon composite material according to the present invention can be used as an anode active material and in the manufacture of lithium ion batteries.

[0173] The electrode including the current collector is manufactured by a manufacturing method conventionally used in the art. For example, the negative electrode active material made of the carbon-silicon composite material of the present invention is mixed with a binder, a solvent and a conductive agent. If necessary, a dispersant may be added. The mixture is stirred to prepare a slurry. Next, the slurry is applied to a current collector and pressed to manufacture a negative electrode.

[0174] Various types of binder polymers can be used as binders in the present invention, such as polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and the like.

[0175] The electrode can be used to manufacture a lithium secondary battery with a separator and an electrolyte disposed between a positive electrode and a negative electrode, as commonly used in the art. EXAMPLES

[0176] (experiment) Below, two examples of the preparation of silicon-carbon composite materials are given. In the production examples, the production was carried out in a Nabertherm hinged rotary tube furnace RSRB 120-750 / 11 equipped with a 4 L quartz tube as the reaction chamber.

[0177] In both production examples, the silicon-carbon composite is obtained using silane as the silicon source, which is mixed with nitrogen to a silane concentration of 0.9% by volume. Nitrogen is also used as the sole carrier gas during heating (steps 202, 203, 204, 205) and cooling (steps 208, 209) of the rotating fluidized bed reactor. The flow rates of the carrier gas and the reactive silicon-containing gas mixture are both 1 SLM. The pressure is controlled. Both productions were carried out for 6 hours. The rotation speed is 20 RPM. The temperature rise is 10°C / min to reach a temperature of 650°C. In both production examples, the micrometer-sized graphite support in the carbon-based material of the silicon-carbon composite is graphite KS4 (Imerys). The graphite is uniformly coated with catalyst nanoparticles. The operation is carried out with 30 g of carbon-based material. In both production examples, the target value of silicon is 10% by mass. In all manufacturing examples, the diameter of the silicon nanowires is set to 20 to 50 nm.

[0178] (Production Example 1 (Comparative Example)) In this Example 1, the pressure P = 1.013 × 10 5 Pa (atmospheric pressure). 3 and 4 show a silicon-carbon composite material production example 1. Silicon nanowires 303 are synthesized on a micrometer-sized graphite KS4 support (30 g) 301 uniformly coated with catalytic gold nanoparticles 302. The gold / graphite mass ratio is 0.05.

[0179] Observation with a scanning electron microscope confirmed that silicon nanowires were obtained (Figure 3). Figure 4 shows the granulation phenomenon that occurred during this process. Spherical aggregates 401 were present, measuring 1-3 mm. In addition, larger "burr-like" aggregates 402 were also present, measuring 3-5 mm.

[0180] (Production Example 2 (present invention)) The conditions common to Preparation Example 1 were as follows: T = 650 °C, t = 6 h, rotation = 20 rpm, flow rate of nitrogen gas and nitrogen / silane mixed gas (silane: 0.9 vol%) = 1 SLM, powder = graphite KS4 with gold nanoparticles (KS4 is still 30 g).

[0181] Unlike Example 1, in Example 2, the pressure P = 1.2 × 10 5 The pressure was measured at 1000 MPa (Pa). Figure 5 shows a silicon-carbon composite material production example 2. Silicon nanowires 503 are synthesized on a micrometer-sized graphite KS4 support 501 uniformly coated with catalytic gold nanoparticles 502. The gold / graphite mass ratio is 0.05. Observation with a scanning electron microscope confirmed that silicon nanowires (estimated diameter: 50-100 nm, estimated length: 100 nm) were obtained (Figure 5). Figure 6 shows a silicon-carbon composite material production example 2. In this micrograph, the granulation phenomenon that occurred during this process can be confirmed. Spherical aggregates 601 are present with a size of 1-3 mm.

[0182] [Table 1]

[0183] From the above comparison it can be seen that by carrying out the process according to the parameters set out in the claims, an improved yield of composite material is obtained. [Explanation of symbols]

[0184] 106, 701, 901.a, 901.b Tubular chambers 107, 702, 902 Heating furnace 108 Carbon Powder Material 103,109 Flange 104,110 Bearing mechanism 101, 710, 910 Carrier gas inlet 102, 711, 911 Reactive silicon-containing mixed gas inlet 111 Gas Cooling Device 112 Needle valve 111 114a, 114b Liquid trap 113, 713, 913a, 913b All gas outlets 115, 919 Pressure gauge 703, 903 boundary mechanism 705, 905 Product supply mechanism 704 Carbon Materials 706, 906 motors 707 Device support part 708, 908 Tilt mechanism 709, 909 Product discharge mechanism 712, 912 Inert gas inlet 714,718,914a,914b,914c,918 valves 715, 915 Reactive silicon-containing gas detector 716, 916 Bursting disc safety mechanism 717, 917 Gas Safety Tank 918 Separation mechanism 904 Silicon-carbon composite material (untreated) 919 Silicon-carbon composite granules 907 Process Support Department

Claims

1. 1. A method for producing a carbon-silicon composite material, comprising: A reactor comprising a tubular chamber rotatable about a longitudinal axis (X-X), 13. A method of manufacturing in a tubular chamber, comprising: (1) A carbon-based material including a carbon support and, optionally, a catalyst, in the tubular chamber. introducing at least one of the ingredients; (2) heating the tubular chamber under a carrier gas flow; (3) rotating the tubular chamber; (4) introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5) In the rotating tubular chamber, under a flow of reactive silicon-containing gas mixture, a temperature in the range of 200° C. to 900° C. and a temperature of 1.02×10 ５ A step of performing a heat treatment at a pressure of 100 Pa or more; (6) recovering the resulting product; and The method includes: However, the step (3) may be started at any stage, that is, before or after the step (1), or before or after the step (2).

2. 2. The method according to claim 1, wherein the pressure in step (5) is 1.05×10 ５ ~10 ６ The method according to claim 1,

3. 3. The method according to claim 1 or 2, wherein the temperature in step (5) is in the range of 350°C to 850°C.

4. The method of claim 1 , wherein the carbon-based material is selected from graphite, graphene, and carbon.

5. The method according to claim 1, wherein the carbon-based material is graphite powder having an average particle size of 0.01 to 50 μm.

6. The method of claim 1 , wherein the carbon-based material carries catalytic particles on its surface.

7. 10. The method of claim 1, wherein the catalyst is selected from metals, bimetallic compounds, metal oxides, metal nitrides, metal salts, and metal sulfides.

8. 10. The method of claim 1, wherein the reactive silicon-containing mixed gas stream comprises at least a reactive silicon species and a carrier gas.

9. 2. The method of claim 1, wherein the reactive silicon species is selected from silane compounds, and preferably the reactive silicon species is silane (SiH ４ ) a method.

10. The method of claim 1, wherein the reactive silicon species is silane (SiH 4 ).

11. 10. The method of claim 1, wherein a volume ratio of the carbon-based material, including the carbon support and optionally further including the catalyst, based on the volume of the tubular chamber is 10% to 60%.

12. 2. The method of claim 1, wherein the flow rate of the reactive silicon-containing gas mixture in step (5) is in the range of 0.1 to 50 SLM (standard liters per minute).

13. 2. The method of claim 1, wherein the rotational speed of the tubular chamber ranges from 1 to 40 RPM (revolutions per minute).

14. The method of claim 1, further comprising, after step (6), (1') re-introducing untreated carbon-based material into the tubular chamber; (2') heating the tubular chamber under a carrier gas flow; (3') rotating the tubular chamber; (4') introducing a reactive silicon-containing gas mixture into the rotating tubular chamber; (5') In the rotating tubular chamber, under a flow of reactive silicon-containing mixed gas, a temperature in the range of 200°C to 900°C and a concentration of 1.02 x 10 ５ A step of performing a heat treatment at a pressure of 100 Pa or more; (6') recovering the resulting product. The method is carried out for at least one cycle.

15. 10. The method of claim 1, wherein the silicon-carbon composite material comprises a carbon-based material and a nanometer-sized silicon material.

16. The method of claim 15, wherein the nanometer-sized silicon material is a nanowire or a nanoisland.

17. 1. A method for producing an electrode comprising a current collector, comprising: (i) carrying out the method of claim 1 to prepare a carbon-silicon composite material; (ii) coating at least one surface of the current collector with a composition containing the carbon-silicon composite material as an electrode active material; A method comprising:

18. A method for producing an energy storage element comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, comprising the steps of:

20. Carrying out the method of claim 17 to form at least one electrode; A method comprising:

19. The method of claim 18, used in the manufacture of a lithium secondary battery.

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