Process for producing silicon-containing materials in a stirred tank reactor

Abstract

A process for producing a silicon-containing material by pyrolysis of a silicon precursor in the presence of porous particles, where silicon is deposited in the pores and on the surfaces of the porous particles, the pyrolysis of the silicon precursor is carried out in a reaction zone of a gas traverse reactor, and the particles are circulated in the reaction zone during pyrolysis by a close clearance agitator operating in a heated region, the agitation mechanism being close clearance as defined in claim 1. The silicon-containing material obtained by this process, an anode material, an anode and a lithium ion battery comprising the silicon-containing material.

Description

[Technical Field]

[0001] A process for producing a silicon-containing material by thermal decomposition of a silicon precursor in the presence of porous particles, wherein silicon is deposited within the pores and on the surface of the porous particles in a close-clearance agitator-equipped gas traversing reactor; a silicon-containing material obtainable by the process; an anode material, an anode, and a lithium-ion battery containing the silicon-containing material. [Background technology]

[0002] As a storage medium for electrical power, lithium-ion batteries are currently the most practical electrochemical energy storage devices with the highest energy density. They are primarily used in portable electronics, tools, and electrically powered transportation vehicles such as bicycles, scooters, and automobiles. The currently widely used active material for the negative electrode ("anode") of corresponding batteries is graphitic carbon. However, such graphitic carbon has the disadvantage of a relatively low electrochemical capacity, theoretically 372 mAh per gram of graphite, which is only about one-tenth of the electrochemical capacity theoretically achievable with lithium metal. An alternative active material for the anode uses the addition of silicon, as described, for example, in EP 1730800 B1, US 10,559,812 B2, US 10,819,400 B2, or EP 3335262 B1. Silicon together with lithium forms a binary electrochemically active alloy that allows very high electrochemically achievable lithium contents of up to 3579 mAh per gram of silicon (M. Obrovac, V. Chevrier Chem. Rev. 2014, 114, 11444).

[0003] The intercalation and deintercalation of lithium ions into silicon has the disadvantage of being accompanied by a very rapid change in volume, which can reach 300% in the case of complete intercalation. Such a volume change subjects the silicon-containing active material to severe mechanical stresses that can ultimately lead to the active material's decomposition. This process, also known as electrolytic grinding, in the active material and electrode structure results in the loss of electrical contact and therefore the irreversible loss of electrode capacity.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the electrolyte components to continuously form a passivating protective layer (solid electrolyte interphase, SEI). The formed components are no longer electrochemically active. The lithium bonds within them are no longer available to the system, thus leading to a significant and continuous loss of battery capacity. Due to the extreme changes in silicon volume during battery charge / discharge, the SEI regularly collapses, meaning that the unoccupied surface of the silicon-containing active material is further exposed and then undergoes further SEI formation. Since the amount of mobile lithium in a complete cell corresponding to the useful capacity is limited by the cathode material, it is increasingly consumed, and the battery capacity after just a few cycles drops to an unacceptable level from a performance standpoint.

[0005] The decrease in capacity over the course of multiple charge-discharge cycles, also known as fading or continuous capacity loss, is generally irreversible.

[0006] A series of silicon-carbon composite particles have been described as active materials for lithium-ion battery anodes, where silicon is incorporated into porous carbon particles starting from gas or liquid precursors.

[0007] It is general knowledge that in multiphase reaction systems good contact between the porous solid and the fluid precursor is necessary (F. Schueth Chem. Unserer Zeit 2006, 40, 92-103).

[0008] For example, US Pat. No. 1,014,795,022 describes the deposition of silicon from monosilane SiH4 in porous carbon in a rotary tubular furnace or equivalent furnace type at high temperatures of 300-900°C, preferably with particle agitation, by the process of CVD (chemical vapor deposition) or PE-CVD (plasma-enhanced chemical vapor deposition). This process uses a mixture of 2 mol% monosilane and nitrogen as an inert gas. As a result of the low concentration of silicon precursor in the gas mixture, the reaction time is very long. Also, the ratio of particle bed to reactor volume in a rotary tubular furnace is usually very unfavorable, since otherwise there would be significant particle emissions with the gas flow.

[0009] Another method for carrying out a gas-solid reaction, and therefore for incorporating silicon into a porous starting material, involves a gas fluidized bed, in which a bed of solid particles is loosened and extensively transported by an upward flow of gas, so that the bed of solids as a whole exhibits liquid-like behavior (VDI-Waermeatlas 11th Edition, Section L3.2 Flow forms and pressure loss in fluidized beds, pp. 1371-182, Springer Verlag, Berlin Heidelberg, 2013).

[0010] Gas fluidized beds are also commonly called fluidized beds, and the process for producing them is also called fluidization or fluidizing.

[0011] In a gas fluidized bed, solid particles are very well dispersed. As a result, a very large contact area between the solid and the gas is formed, which can be ideally utilized for energy and mass transfer processes. Gas fluidized beds are generally characterized by very good mass and heat transfer events and uniform temperature distribution. The quality of the mass and heat transfer processes is particularly important for the homogeneity of the products obtained by reactions in the fluidized bed and can be correlated with the homogeneity of the fluidized state. As a result, the formation of a homogeneous fluidized bed or a homogeneous fluidized state is essential for the utilization of a fluidized bed process to produce products with uniform product properties.

[0012] Fluidization characteristics can be classified as a function of particle size and solid density. For example, for a particle size d50<20 μm and a density difference between the particle and the gas of 1000 kg / m 3Larger particles are classified as Geldart Class C (cohesive) [D. Geldart, Types of Gas Fluidization, Powder Technology 7 (1973) 258]. Geldart Class C particles are characterized by their inability to easily convert to a fluidized state. Due to their small particle size, the effect of interparticle attraction is comparable to or greater than the forces acting on the primary particles as a result of the gas flow. This leads to corresponding effects such as the rise of the fluidized bed as a whole and / or the formation of channels. When channels form, tubes form in the particle bed instead of a fluidized bed, and the fluidizing gas flows preferentially through these tubes, while the majority of the bed does not experience any cross-flow. As a result, the fluidization does not achieve homogeneity. If the gas velocity increases significantly above the minimum fluidization velocity of the primary particles in the bed, agglomerates consisting of individual particles form over time, which can be fully or partially fluidized. Typical behavior is the formation of a layer with agglomerates of different sizes. In the bottom layer, directly above the inlet base, these agglomerates are very large and exhibit very little or no movement. In the upper layers, there are smaller agglomerates, which are fluidized. In the top layer, the smallest agglomerates are present and are partially entrained by the gas flow, which constitutes a technical problem in the process. The fluidization behavior of such particle beds is further characterized by the formation of large bubbles and low expansion of the fluidized bed. In the literature, this behavior is also referred to as "agglomerate bubble fluidization" (ABF) (Shabanian, J., Jafari, R., Chaouki, J., Fluidization of Ultrafine Powders, IRECHE., Vol. 4, No. 1, 16-50).

[0013] It is clear to those skilled in the art that beds fluidized by ABF are not suitable for producing materials with uniform properties due to the heterogeneity within the fluidized bed and the associated non-uniform mass and heat transfer conditions.

[0014] For this reason, GB2580110B2 specifies, for example, the production of particles of sizes greater than 50 μm (D 50However, after the reaction is complete, the resulting particles must be ground to the required target size of less than 20 μm. In this fluidized bed, fluidization of particles less than 20 μm will lead to severe cases of weak agglomeration and uneven infiltration of the porous carbon particles.

[0015] There are known means of assisting fluidization to convert particles less than 20 μm in the form of agglomerates into a predominantly homogeneous fluidized bed. For example, US 7,658,340 B2 describes how, through the input of additional force components such as vibrational, magnetic, acoustic, rotational / centrifugal forces, or combinations thereof, in addition to the force exerted by the fluidizing gas, the size of the agglomerates consisting of SiO nanoparticles (Geldart Class C) in a fluidized bed is influenced so that a predominantly homogeneous fluidized bed is formed.

[0016] Cadoret et al. (Cadoret, L., Reuge, N., Pannala, S., Syammal, M., Rossignol, C., Dexpert-Ghys, J., Coufort, C., Caussat, B., Silicon Chemical Vapor Deposition on Macro and Submicron Powders in a Fluidized Bed, Powder Technol., 190, 185-191, 2009) describe the deposition of silicon from monosilane SiH4 onto non-porous submicron-sized titanium dioxide particles in a vibrating fluidized-bed reactor. The input of vibrations allowed the agglomerates in the fluidized bed to be limited to a size range of 300-600 μm.

[0017] Fluidized bed processes without fluidization aids are not suitable for incorporating / depositing silicon into porous matrix particles because they cannot uniformly fluidize particles smaller than 20 μm in size. Due to the heterogeneous fluidized bed, it is not possible to produce a homogeneous product.

[0018] Fluidized bed processes with fluidization aids are disadvantageous for processes incorporating / depositing silicon into porous matrix particles, since the fluidization of particles smaller than 20 μm involves significant technical complexity, which is further complicated by the associated high capital investment and maintenance expenditures / costs.

[0019] Another drawback of incorporating silicon by fluidized bed process with fluidization aid is that during the process, the properties of primary particles, such as particle density or surface consistency, change.These changes have unknown effects on the formation of agglomerates, but for the process regime, such formation should be known.It is impossible to guarantee uniform process conditions throughout the entire process run time.

[0020] A further drawback of fluidized bed technology is that a gas flow is required to fluidize the agglomerates of primary porous particles, resulting in the expulsion of primary particles and / or smaller agglomerates.

[0021] A fundamental drawback of fluidized bed technology is that the flow of fluidizing gas required to form a homogeneous fluidized bed depends on the size of the particles / agglomerates in the fluidized bed. As a result, the amount of reactive gas metered and the contact time of the reactive gas with the porous particles depend on the fluidization and mixing conditions of the particle bed. In a fluidized bed process, for example, the contact time of the gaseous reactive component with the particle bed can only be increased by decreasing the gas velocity. However, gas velocity is a critical variable for ensuring the fluidization and mixing conditions.

[0022] One possibility to overcome the drawbacks of fluidized bed technology is to make the mixing of the particle bed with the gas phase independent of the flow.

[0023] US2020 / 0240013A1 describes the deposition of silicon from a silicon-containing gas into particles having an average particle size in the millimeter range in a stirred-bed reactor. Due to the particle size, the bed material used is assumed to have a very high fluidity. With the described apparatus, the exchange between gas and solid is carried out through the use of a central stirring screw, which simultaneously supplies reactant gas through openings in the stirred bed. Since particles in the millimeter range require a large amount of fluidizing gas to bring the particles into the fluidized bed, this patent application is particularly directed to the advantages of processing particles in this range.

[0024] However, the agitator used in US2020 / 0240013A1 is inappropriate for circulating agglomerated particles smaller than 20 μm.

[0025] It is known from the technical literature that particles in stirred beds can be circulated using a wide variety of different stirring elements (M. Mueller, Feststoffmischen (Solid Mixing), Chemie Ingenieur Technik 2007, 79, 7). For example, the use of close-clearance helical agitators transports particles laterally upwards within the reactor, creating a circulating flow with relative particle movement due to the anti-slip material. This prevents the particles from adhering to the reactor walls.

[0026] A parameter that describes the state of motion of a particle bed is the Froude number (Fr), which indicates the ratio of centrifugal force to gravitational force in a rotating system.

[0027]

number

[0028] In this formula, r c is the characteristic radius associated with the system. For systems with rotating mixing tools, r c corresponds to the outer diameter of the stirring element. For systems with a rotating drum, r cis the inner radius of the vessel. The circular frequency ω = 2πn depends on the rotational speed n of the rotating system. The effect of gravitational forces is taken into account via the acceleration due to gravity g. At low Froude numbers, the gravitational force component dominates, so the radial transport of material is low. Circulation of a particle bed is inappropriate. On the other hand, at high Froude numbers, the centrifugal force component dominates, causing the material to move excessively against the vessel wall. Here too, circulation of a particle bed is inappropriate.

[0029] The parameter used to describe the contact time between the gas phase and the agitated particle bed is the residence time of the gaseous reactive components in the reactor. The mean residence time t V is the reactor volume and the metered gas phase

number

[0030]

number

[0031] A further important measure for assessing homogeneous reaction conditions in a stirred-bed reactor is the residence time t of the silicon precursor. v Particle bed circulation time t u The ratio of t u / t v The particle bed circulation time t u is the reactor volume V R and circulating particles

number

[0032]

number

[0033] Volumetric flow rate of particles circulated by a stirring element

number

[0034]

number

[0035] The volumetric flow rate of the circulating particles is the product of the rotation speed n and the sum of all volumes displaced tangentially by the individual stirring units i of the stirring element. The geometric dimensions of each individual stirring unit are determined by the rotation axis r R,inner,i The distance of the inner edge of the stirring element to the axis of rotation r R,outer,i and by the distance of the outer edge of the stirring element to the upper contour h of each stirring unit. o.i (r) and lower contour h u.i It is described by (r).

[0036] comparison u / t v If a value of t is less than 1, the process of particle circulation is faster than the gas cross-flow of the bed, producing a uniform distribution between the gas and the particles. u / t v At values ​​above 1 for , the gas flows through the stirred bed faster than the bed itself can be circulated. As a result, zones with different deposition conditions are formed in the stirred bed, leading to a non-uniform product distribution in the bed. [Prior art documents] [Patent documents]

[0037] [Patent Document 1] European Patent No. 1730800 [Patent Document 2] U.S. Patent No. 10,559,812 [Patent Document 3] U.S. Patent No. 10,819,400 [Patent Document 4] European Patent No. 3335262 [Patent Document 5] U.S. Patent No. 10,147,950 [License 6] UK Charter No. 2580110 [License 7] U.S. Patent No. 7,658,340 [License 8] U.S. Patent and Trademark Office Publication No. 2020 / 0240013 [Non-licensed literature]

[0038] [Non-licensed Document 1] M.Obrovac, V.Chevrier Chem.Rev.2014, 114, 11444 [Non-licensed Document 2] F.Schueth Chem.Unserer Zeit 2006, 40, 92~103 [Non-licensed Document 3] VDI-Waermeatlas 11th Edition, Section L3.2 Flow forms and pressure loss In fluidized beds, pp.1371~182, Springer Verlag, Berlin Heidelberg, 2013 [Non-licensed Document 4] D.Geldart, Types of gas fluidization, Powder Technology 7(1973)258 [Non-licensed Document 5] Shabanian,J., Jafari,R., Chaouki,J., Fluidization of Ultrafine Powders, IRECHE., Volume 4, N.1,16-50 [Non-licensed Document 6] Cadoret, L., Reuge, N., Pannala, S., Syamlal, M., Rossignol, C., Dexpert-Ghys, J., Coufort, C., Caussat, B., Silicon Chemical Vapor Deposition on macro and submicron powders in a fluidized bed, Powder Technol., 190, 185~191, 2009 [Non-Patent Document 7] M. Mueller, Feststoffmischen (solid mixtures), Chemie Ingenieur Technik 2007, 79, 7 Summary of the Invention [Problem to be solved by the invention]

[0039] Against this background, the object was to provide a process for producing silicon-containing materials, preferably having a high storage capacity for lithium ions, which allows high cycling stability when used as active material in the anode of a lithium-ion battery, starting from porous particles and silicon precursors, which is technically simple to implement and does not have the disadvantages that affect the above-mentioned methods of the prior art, in particular with regard to particle emissions, reaction times, and the necessary underlying equipment.

[0040] It is particularly desirable to minimize the dead space in the bed that is not stirred by the agitator, so that the material in the heated portion of the shell is kept in motion with maximum efficiency, and energy is transferred from the walls to the bed, which also prevents particle buildup on the walls. [Means for solving the problem]

[0041] The present invention provides a process for producing silicon-containing materials by thermal decomposition of a silicon precursor in the presence of porous particles, wherein silicon is deposited within the pores and on the surface of the porous particles; A process in which pyrolysis of a silicon precursor occurs within a reaction zone of a gas traverse reactor, and the particles are circulated within the reaction zone during pyrolysis by a close clearance agitator within the heated region. However, in the following formula 1,

number

[0042] Surprisingly, it has been found that the use of a close clearance stirring tool in the present invention allows very small particles, more particularly particles less than 20 μm, to be circulated within the reactor, and the gas flow of reactive components is metered such that the process of introducing silicon into the porous particles occurs homogeneously and with high conversion of the silicon precursor, while the contact time between the gas phase and the solid has a duration such that the release of particles from the reactor with the gas flow is minimal.

[0043] Compared to fluidized-bed reactors with fluidization-assisting means, gas transverse stirred reactors or stirred-bed reactors (SBRs) have a simpler construction, since the amount of gas that needs to be compressed and preheated in an SBR is smaller and gas is not utilized for fluidization. This means that the associated assembly costs are lower. In the case of an SBR, there is no need for sophisticated control and regulation techniques for the operation of the fluidization-assisting means. Compared to FBRs, SBRs have a smaller build, since the stirred bed occupies a smaller volume for a given mass. The specific capital investment costs are lower.

[0044] Compared with GB2580110B2, no additional operation steps are required in the process of the present invention.

[0045] Compared to fluidized bed reactors, particle circulation is independent of the gas phase feed. Longer residence times are possible, which leads to higher conversions of the reactive components.

[0046] The agitation in the process of the present invention only circulates the particles; they are not stirred up by the agitator.

[0047] The gas streams are preferably sized so that the entrainment of particles in the process of the present invention by the gas stream is minimized, and thus the release of particles from the reactor is also minimized, while at the same time the gas streams are preferably sized to maximize the conversion of the reactive components used.

[0048] Due to the appropriate selection of the rotary agitator speed parameter, expressed by the dimensionless Froude number, and due to an appropriate metering rate, homogeneous deposition conditions are possible.

[0049] In contrast to US2020 / 0240013A1, the process of the present invention is improved by the use of a close clearance agitator.

[0050] The rotary agitator speed is preferably set so that the particle bed circulation time is less than the residence time of the fluid reactive components, more particularly the porous particles, so that sufficient effective macro-mixing of the fluid and solid phases occurs, resulting in homogeneous treatment of all particles in the solid phase.

[0051] A further economic advantage of this process, in contrast to non-inventive processes, is the higher silicon yield. Also, the deposition of silicon on and especially within the porous particles is particularly uniform, resulting in high stability of the resulting silicon-containing material when used as an active material in the anode of a lithium-ion battery, with a concomitant low volume change upon cycling.

[0052] W(h) is the close clearance of the stirring mechanism in two rotationally symmetric reactors, defined as the ratio of the circumferences of two planar cross sections perpendicular to the axis of rotation of the two rotational surfaces, (h represents the height coordinate). The inner rotational surface is formed by one complete revolution of the stirring mechanism, and the distance r from the axis of rotation to the outer contour of the stirring mechanism. R The stirring mechanism is characterized by (h). The stirring mechanism includes all components attached to it. A planar cross section at any point h of the plane of rotation perpendicular to the axis of rotation forms a circular cross section. The circumference of the inner cross section is calculated as follows: u R (h)=2πr R (h)

[0053] The outer surface of rotation is formed by the rotation of the inner contour of the reactor around the axis of rotation, which is the distance r B (h). The inner contour of the reactor includes all components attached to it. The circumference of any cross section of the outer plane of revolution perpendicular to the axis of rotation is calculated as follows: u B (h)=2πr B (h)

[0054] Using the circumference, the proximal clearance is defined as:

number

[0055] Generally speaking, a reactor may contain one or more stirring mechanisms. The contours of each individual stirring mechanism form a plane of rotation through a complete rotation. These planes of rotation may be separate or, preferably, superimposed on one another. Sectioning the individual or superimposed planes of rotation at any point perpendicular to the axis of rotation generates a figure whose circumference can be ascertained. When multiple figures are generated, the overall circumference is determined by adding up the individual circumferences.

[0056] Generally speaking, a reactor may consist of one or more reactor sections, each preferably rotationally symmetric and interconnected. The entirety of all reactor walls encloses a figure. By dividing this figure at any point perpendicular to the axis of rotation of the stirring mechanism, the circumference of the resulting figure can be determined. The proximity clearance W(h) is calculated in the same way as for a rotationally symmetric reactor.

[0057] The proximity clearance can vary with h. A stirrer configuration is in accordance with the invention if the proximity clearance W(h) in the reaction zone is W(h)>0.9 for at least half of all values ​​of h, and the parameter defined for this is W(h 50% ) In one preferred embodiment, W(h 50% )>0.95. In a particularly preferred embodiment, W(h 50% )>0.97. In one particularly preferred embodiment, W(h 50% ) > 0.99. The reaction zone is the region within the reactor where the agitated particle bed contacts the reactive components and the reactive components are decomposed. For a particular case of the process, W(h) > 1 50% ) values ​​are also possible.

[0058] The process is preferably carried out in a cascade reactor system containing multiple reactors.

[0059] Implementation in a cascade reactor has the advantage over implementation in only one reactor that the long cooling and heating stages of the reactor are reduced. This has the time and energy advantages over only one reactor, leading to reduced stress on the reactor material. Cascade reactor systems also offer the advantage that each reactor can be precisely designed for its purpose. Cascade reactor systems are also more easily scalable, allowing different numbers of reactors to be combined with each other to form individual stages.

[0060] In one preferred embodiment, the process comprises at least the following steps 1 to 3:

[0061] Step 1: Reactor A is loaded with porous particles, the particles are pretreated, and then the pretreated particles are transferred to reactor B or a storage vessel, or the material remains in reactor A.

[0062] Step 2: Passing a gas flow consisting of at least one reactive component containing an inert gas and / or a silicon precursor, and / or at least one silicon-free precursor through reactor B; The reactor is adjusted to a temperature at which thermal decomposition of the reactive components occurs on the surface and within the pores of the porous particles. The particle bed in reactor B is circulated with a close-clearance agitator so that the motion of the particle bed can be described by a Froude number ranging from 1 to 10. The gas phase is fed to reactor B, and the particle bed in reactor B is circulated with a close-clearance agitator element so that the ratio of the circulation time to the mean residence time of the reactive components is less than 1. The reaction can proceed both below atmospheric pressure and above atmospheric pressure. After silicon is introduced into and onto the pores of the porous particles, the silicon-containing material is transferred to reactor C or a reservoir for intermediate storage, or the material remains in reactor B.

[0063] Step 3: Post-treatment of the silicon-containing particles for functionalization and / or coating of the surface of the silicon-containing particles. Cooling of the particles to a specified temperature and recovery of the silicon-containing material from reactor C and preferably direct transfer to a storage container or direct distribution to a suitable container.

[0064] In step 1, porous particles are packed into a heatable and / or vacuum-resistant and / or pressure-resistant reactor A. This packing can be done manually or automatically.

[0065] The filling of reactor A with porous particles can be carried out, for example, under an inert gas atmosphere, or preferably under ambient air. The inert gas used can include, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide, or mixtures thereof, such as forming gas. Argon or, more particularly, nitrogen is preferred.

[0066] Automated filling can be accomplished using, for example, a metering screw, star wheel, vibrating trough, plate-type metering system, belt-type metering system, vacuum metering system, negative metering system, or another metering system, for example, from a silo, bag chute, or another container system.

[0067] The purpose of pretreating the particles in reactor A in stage 1 is to remove air / oxygen, water or dispersants such as surfactants or alcohols, and impurities from the particles. This can be achieved by inertization with an inert gas, increasing the temperature to 1000°C, reducing the pressure to 0.01 mbar, or by a combination of the individual operating steps. The inert gas used can include, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide, or a mixture thereof, such as forming gas. Argon or, more specifically, nitrogen is preferred.

[0068] The purpose of the pretreatment in Step 1 may also be to modify the surface chemistry of the porous particles with an additional substance. The addition may occur before or after drying, and an additional heating step may occur before transferring the material to Reactor B. The substance may be introduced into the reactor in gaseous form, solid, liquid, or as a solution, including possible mixtures, emulsions, suspensions, aerosols, or foams. Included substances may include, for example, carbon dioxide, water, sodium hydroxide, potassium oxide, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, ammonia, ammonium dihydrogen phosphate, lithium nitrate, sodium nitrate, potassium nitrate, lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide, potassium bromide, and alkoxides.

[0069] The transfer of the porous particles to a further reactor or vessel can be achieved by, for example, drop tubes, continuous conveyors, flow conveyors / suction or pressure conveying units (e.g., vacuum conveyors, transport blowers), mechanical conveyors (e.g., driven roller conveyors, screw conveyors, carousel conveyors, circulating conveyors, bucket units, star wheel locks, chain conveyors, scraper conveyors, belt conveyors, vibrating conveyors), gravity conveyors (e.g., chutes, roller beds, ball beds, rail beds), and discontinuous conveyors, floor-based and rail-free (e.g., automated vehicles, manual forklift trucks, electric forklift trucks), drive conveyors, This can be achieved by: Distributed Transport Systems (DTS), air cushion vehicles, hand carts, electric carts, motor vehicles (tractors, wagons, forklift stackers), transfer carriages, transfer / lift carriages, shelf access devices (with or without converters, capable of following curved paths), floor-based rail-bound (e.g., plant railways, tracked cars), floor-free (e.g., trolley trucks), cranes (e.g., bridge cranes, portal cranes, jib cranes, tower cranes), electric overhead trucks, small container transport systems, fixed (e.g., elevators, service lifts and cherry pickers, staged conveyors).

[0070] In stage 2, the pretreated material in reactor B is preferably brought to a temperature of 100 to 1000°C, more preferably 250 to 600°C, and particularly preferably 300 to 500°C.

[0071] During the temperature change, or when the temperature is reached, or during the traversal of the temperature profile, reactor B is alternately or simultaneously traversed by a gas consisting of at least one inert gas and / or at least one silicon precursor and / or at least one reactive component consisting of at least one silicon-free precursor. During stage 2, different gas compositions are possible or changed continuously within the specified composition. The metering rate of the reactive component-containing gas phase with at least one silicon precursor relative to the pore volume is calculated based on the absolute pore volume (cm) of all porous particles introduced into reactor B. 3 The metered addition is defined as the mass (g) of silicon contained in the silicon precursor supplied per hour relative to the pore volume (cm) of the porous particles used per hour. During the course of deposition of the silicon precursor, the metered addition is preferably 3 The Si content is preferably 0.1 to 2 g, more preferably 0.5 to 1.5 g per 1000 particles.

[0072] Alternatively, it is the area-based metering rate of the reactive component-containing gas phase having at least one silicon precursor as the mass of silicon (kg) contained in the silicon precursor supplied per hour relative to the maximum cross-sectional flow area (m) of the reaction zone. The cross-section is measured with the reactor empty. The reaction zone is the region within the reactor where the agitated particle bed contacts the reactive component and the precursor is decomposed.

[0073] The metering rates of the precursors fed are calculated so that the ratio of the particle bed circulation time to the mean residence time of the reactive components in the reactor is always less than 1.

[0074] The gas phase can be metered in continuously or in pulses. The metering rate can be varied during the operating time of the reaction.

[0075] In a rotationally symmetric reactor, the silicon precursor rotates at an external rotation area of ​​1 m per hour over the course of deposition. 2 Preferably, Si is weighed and charged at a rate of 1 to 700 kg, more preferably 10 to 300 kg per unit area.

[0076] During the entire pyrolysis period, reactor B is preferably traversed by an amount of silicon-containing reactive component such that the amount of silicon deposited is sufficient for the target volume of silicon-containing material produced relative to the weighed amount of porous particles.

[0077] The heating of reactor B in step 2 can be carried out, for example, at a constant heating rate or at several different heating rates, which can be adapted in each individual case by a person skilled in the art according to the process design, for example according to the size of the reactor, the amount of porous particles in the reactor, the stirring technique or the planned reaction time.

[0078] The heating of reactor B in step 2 is preferably carried out at a heating rate of 1 to 100°C / min, more preferably at a heating rate of 2 to 50°C / min.

[0079] The temperature at which the silicon precursor begins to decompose may depend, for example, on the porous particles used, the silicon precursor used, and other boundary conditions of the decomposition, such as the partial pressure of the silicon precursor during decomposition and the presence of other reactive components, such as catalysts, that affect the decomposition reaction.

[0080] During the decomposition of the silicon precursor in Stage 2, the temperature may be held constant or may be varied, the objective being to achieve near complete conversion of the silicon precursor during the contact time of the gas with the stirred bed while producing usable silicon-containing material.

[0081] Bed temperatures during stages 2 and 3, particularly in the reaction zone of a reactor equipped with a close clearance agitator, are preferably in the range of 100-1000°C, more preferably 250-600°C, and most preferably 300-500°C. For example, the target temperature for SiH4 is preferably between 300-500°C, more preferably in the range of 320-450°C, and very preferably in the range of 320-430°C. The target temperature for HSiCl3 is preferably between 380-1000°C, more preferably in the range of 420-600°C. The target temperature for H2SiCl2 is preferably between 350-800°C, more preferably in the range of 380-500°C.

[0082] If a hydrocarbon is used in step 3 and / or in addition to the deposition of silicon during step 2, as a further reactive component that does not contain a silicon precursor, a target temperature is used at which the hydrocarbon begins to decompose and carbon is deposited in the pores and on the surface of the porous particles. The target temperature in this embodiment is preferably selected in the range of 250 to 1000°C, more preferably 350 to 850°C, and most preferably 400 to 650°C.

[0083] In stage 2, the bed of porous particles is preferably continuously circulated. Circulation is achieved via one or more stirring elements or via the rotational movement of the reactor itself (e.g., centralized mixers from Maschinenfabrik Gustav Eirich), or a combination thereof. The state of motion of the moving bed is characterized by a Froude number between 1 and 10. The Froude number is preferably between 1 and 6, more preferably between 1 and 4.

[0084] The thermal decomposition of the silicon precursor in the presence of the porous particles preferably occurs at a pressure of 0.05 MPa to 5 MPa, more preferably 0.08 to 0.7 MPa.

[0085] The gas phase from step 2 consists of at least one reactive component containing an inert gas and / or a silicon precursor and / or at least one silicon-free precursor, possibly of a different composition. The silicon precursor(s) can generally be introduced into reactor B in mixed form, or separately, or in a mixture with an inert gas component, or as a pure substance. The reactive component preferably contains 0% to 99%, more preferably at most 50%, particularly preferably at most 30%, and very particularly preferably at most 5% of the inert gas component, based on the partial pressure of the inert gas component, as a fraction of the total pressure of the reactive components under standard conditions (according to DIN 1343).

[0086] The silicon-containing reactive component contains at least one precursor that can react under selected conditions, such as heat treatment, to provide silicon. The precursor is preferably a silicon-hydrogen compound, such as monosilane SiH4, disilane Si2H6, and higher linear, branched, or cyclic homologs, neopentasilane Si5H. 12 , cyclohexasilane Si6H 12 , chlorine-containing silanes such as trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and higher linear, branched or cyclic homologues such as 1,1,2,2-tetrachlorodisilane Cl2HSi-SiHCl2, chlorinated and partially chlorinated oligosilanes and polysilanes, methylchlorosilanes such as trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylsilane MeH3Si, chlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or mixtures of the silicon compounds mentioned.

[0087] In one particular embodiment of this process, a monosilane or mixture of silanes, such as a mixture of monosilane SiH, trichlorosilane HSiCl, dichlorosilane HSiCl, monochlorosilane HSiCl, and tetrachlorosilane SiCl (each component may be present at 0-99.9 wt%), is produced by a suitable process only immediately prior to placement into the reactor. Generally speaking, these processes begin with trichlorosilane HSiCl, which is rearranged over a suitable catalyst (e.g., AmberLyst® A21 DRY) to form the other components of the described mixture. The composition of the resulting mixture is primarily determined by workup of the mixture after one or more rearrangement steps at one or more different temperatures.

[0088] Particularly preferred reactive components are monosilanes SiH4, oligomeric or polymeric silanes, especially those of the general formula Si n H n+2 Linear silanes of the general formula -[SiH2] (where n can include an integer ranging from 2 to 10). n - (wherein n can comprise an integer ranging from 3 to 10), trichlorosilane HSiCl3, dichlorosilane H2SiCl2, and chlorosilane H3SiCl, which may be used alone or as a mixture, with SiH4, HSiCl3, and H2SiCl2 being very preferably used alone or as a mixture.

[0089] During the metering of the reactive components into the reactor, the constituents of the reactive components may be present, for example, in gaseous, liquid or sublimable solid form.

[0090] The reactive components are preferably compositions of matter, for example, gaseous, liquid, solid, sublimable, or possibly different aggregate states. In one variant of the process, the reactive components are introduced directly into the bed of porous particles in the reactor, for example, from below, from the side, or using a special agitator.

[0091] Furthermore, the reactive components of steps 2 and / or 3 may comprise further reactive components, such as dopants based on compounds containing boron, nitrogen, phosphorus, arsenic, germanium, iron or nickel. The dopants are preferably selected from the group including ammonia NH3, diborane B2H6, phosphane PH3, germanium GeH4, arsane AsH3, iron pentacarbonyl Fe(CO)4 and nickel tetracarbonyl Ni(CO)4.

[0092] Reactive constituents which may also be present in the gas phase include hydrogen or aliphatic hydrocarbons having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, such as methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane; unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethene, acetylene, propene, methylacetylene, butylene, butyne (1-butyne, 2-butyne), isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene; cyclic unsaturated hydrocarbons, such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene; aromatic hydrocarbons, such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenyl These include methane or naphthalene, other aromatic hydrocarbons, such as hydrocarbons selected from the group comprising phenol, o-, m-, p-cresol, cymene, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornane, borneol, isoborneol, bornane, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, bishydroxymethylfuran, as well as mixed fractions containing a number of such compounds, such as those from natural gas condensates, crude oil distillates or coking oven condensates, mixed fractions from product streams from fluid catalytic crackers (FCC), steam crackers or Fischer-Tropsch synthesis plants, or, very generally, hydrocarbon-containing streams from the processing of wood, natural gas, crude oil and coal.

[0093] In one particularly preferred embodiment, a reactive component containing at least one silicon precursor is treated in the first reaction cycle of step 2, and a reactive component containing at least one hydrocarbon, preferably silicon-free, is treated in the second reaction cycle of step 2. By repeating these two steps, it is possible to obtain, for example, a silicon-containing material that does not have an outwardly facing free silicon surface.

[0094] Optionally, an additional hydrocarbon-containing silicon-free reactive component is used in the upstream reaction cycle in stage 2. By this means, for example, a silicon-containing material can be obtained that has a carbon layer between the porous particles and the deposited silicon, and optionally also carries an outer carbon layer, which means that there is no free silicon surface facing outward.

[0095] In one preferred embodiment, the temperature, pressure, pressure change or differential pressure measurements and gas flow measurements in reactor B are determined using conventional equipment and measurement methods. After routine calibration, measurements with different equipment will yield the same results.

[0096] The progress of the reaction in stage 2 is preferably monitored analytically to recognize the end of the reaction and thus minimize the reactor occupation time. Methods for monitoring the progress of the reaction include, for example, temperature measurement to determine exothermic or endothermic events to determine the progress of the reaction by changing the ratio of solid reactor content components to gaseous reactor content components, and additional techniques that allow for observation of changes in the composition of the gas space during the reaction. In one preferred variant of this process, the composition of the gas phase is determined by a gas chromatograph and / or a thermal conductivity detector and / or an infrared spectrometer and / or a Raman spectrometer and / or a mass spectrometer. In one preferred embodiment, the hydrogen content is determined using a thermal conductivity detector and / or any chlorosilanes present are determined using a gas chromatograph or gas infrared spectrometer. In another preferred variant of this process, technical components are used that allow for the separation of hydrogen and silanes. This separation can be achieved, for example, via filtration and / or membrane techniques (solution-diffusion and hydrodynamic models), adsorption, chemisorption, absorption or chemical adsorption, or molecular sieves (eg, zeolites).

[0097] This component allows for a gas recycling process in the case of hydrogen as the gaseous reaction product, in which case the gas discharged in stage 2 is scrubbed and / or enriched in the fraction of silicon-containing reactive components and then returned to the reactor until the desired amount of silicon has been deposited. In another embodiment, the gas is separated into its constituent components and disposed of as such.

[0098] In a further preferred variant of the process, reactor B or the gas discharge site is equipped with technical means for removing the condensable or resublimable by-products that occur, where in one particularly preferred variant, silicon tetrachloride is condensed and removed separately from the silicon-containing material.

[0099] In one preferred embodiment of this process, the metering procedure in step 2 is repeated multiple times, and in this case, each silicon precursor processed in step 2 can be the same or different in each case, and a mixture of multiple silicon precursors is also possible. Similarly, the silicon-free reactive components processed in step 2 can be the same or different in each case, or can consist of a mixture of different reactive components. After multiple repetitions of the individual metering procedures in step 2, the operation in reactor B ends with the transfer of the silicon-containing particles to reactor C.

[0100] In step 3 of this process, the silicon-containing particles in reactor C can be post-treated and / or passivated and / or coated. This is preferably carried out by purging reactor C with oxygen, more particularly with a mixture of inert gas and oxygen. In this way, for example, it is possible to modify and / or functionalize and / or passivate the surface of the silicon-containing material. For example, it is possible to achieve the reaction of any reactive groups present on the surface of the silicon-containing material. For this purpose, a mixture of nitrogen, oxygen, and optionally alcohol and / or water is preferably used, preferably containing up to 20% by volume, more preferably up to 10% by volume, particularly preferably up to 5% by volume of oxygen, and preferably up to 100% by volume, more preferably up to 10% by volume, particularly preferably up to 1% by volume of water. This step is preferably carried out at a temperature of up to 250°C, more preferably up to 100°C, particularly preferably up to 50°C. The particle surface can also be passivated with a gas mixture containing an inert gas and an alcohol. Here, nitrogen and isopropanol are preferably used. However, it is also possible to use methanol, ethanol, butanol, pentanol or longer-chain and branched alcohols and diols.

[0101] The particles may also be deactivated by dispersion in a liquid solvent or solvent mixture, which may include, for example, isopropanol or an aqueous solution.

[0102] The passivation of the particles in step 3 can also be achieved by coating using C-, Al- and / or B-containing precursors at temperatures between 200 and 800°C, optionally followed by treatment in an oxygen-containing atmosphere.

[0103] Aluminum-containing precursors used include, for example, trimethylaluminum ((CH3)3Al), aluminum 2,2,6,6-tetramethyl-3,5-heptanedionate (Al(OCC(CH3)3CHCOC(CH3)3)3), tris(dimethylamido)aluminum (Al(N(CH3)2)3), and aluminum triisopropoxide (CH 21 AlO3).

[0104] The boron-containing precursors used can be, for example, borane (BH3), triisopropylborate ([(CH3)2CHO]3B), triphenylborane ((C6H5)3B), and tris(pentafluorophenyl)borane (C6F5)3B.

[0105] However, in step 3 it is also possible to introduce a post-coating of the particles with a solid electrolyte, for example via pyrolysis of tert-butyllithium and trimethylphosphate.

[0106] In step 3 of the process, in principle, the silicon-containing material is removed from reactor C, optionally while preserving the inert gas atmosphere present in reactor C. This can be achieved, for example, by the following discharge methods: pneumatic (by means of pressure above or below atmospheric pressure), mechanical (starwheel lock, plate discharge, discharge screw or stirring element in the reactor, belt discharge) or gravimetric (double flap or double ball valve, optionally with vibration assistance).

[0107] The preferred silicon-free reactive component is one or more hydrocarbons, the pyrolysis of which generally allows for the deposition of carbon within the pores and on the surfaces of the porous particles. Examples of hydrocarbons are aliphatic hydrocarbons having 1 to 10 carbon atoms, in particular 1 to 6 carbon atoms, preferably methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane and cycloheptane, unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethene, acetylene, propene or butene, isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene, cyclic unsaturated hydrocarbons, such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene, aromatic hydrocarbons, such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane or naphthalene, other aromatic hydrocarbons. Aromatic hydrocarbons, such as phenol, o-, m-, p-cresol, cymene, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornane, borneol, isoborneol, bornane, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, bishydroxymethylfuran, and mixed fractions containing many such compounds, such as those from natural gas condensates, crude oil distillates or coking oven condensates, mixed fractions from product streams from fluid catalytic crackers (FCC), steam crackers or Fischer-Tropsch synthesis plants, or very commonly hydrocarbon-containing streams resulting from the processing of wood, natural gas, crude oil and coal.

[0108] The silicon-free reactive component, i.e., the reactive component containing one or more hydrocarbons but not a silicon precursor, preferably contains no additional components, or one or more inert gases and / or one or more reactive components such as hydrogen, and / or one or more dopants. The dopant is, for example, a compound containing boron, nitrogen, phosphorus, arsenic, germanium, iron, or nickel. The dopant is preferably selected from the group including ammonia NH3, diborane B2H6, phosphane PH3, germane GeH4, arsane AsH3, and nickel tetracarbonyl Ni(CO)4.

[0109] For the purposes of this specification, reactor types selected from the group comprising retort ovens, tubular reactors, stirred bed reactors, stirred tank reactors and autoclaves are preferred, with particular preference being given to using stirred reactors and autoclaves, more preferably stirred reactors and very particularly preferably stirred tank reactors.

[0110] In one particular variant of the process, reactors A, B and C are the same vessel. It is not excluded that reactors A, B and C are the same vessel. In two particular embodiments of the process, the cascade reactor consists of only two interdependent reactors. In a first embodiment, stages 1 and 2 are carried out in the same reactor. In a second embodiment, stages 2 and 3 are carried out in one reactor. In both cases, the reactors may have different temperature zones and they may be operated at atmospheric pressure or at subatmospheric or superatmospheric pressures.

[0111] The reactor can be adjustable, pressure-resistant and vacuum-resistant, all combinations being possible, but the reactor can also fulfil only one of the above mentioned characteristics.

[0112] Technical requirements for the reactor and optional special features for particular variants of the invention

[0113] Reactor A: The reactor is at least adjustable. The reactor may be vacuum-resistant. - A system for preheating, drying and inactivating porous particles. - The system can be connected for the specific addition / metering of porous particles (see step 1 for technical description). For drying and / or removal of impurities in the porous particles, a system may be connected which allows removal of condensable or resublimable substances. A system may be connected that allows the porous particles to be transferred to reactor B (see step 1 for technical description).

[0114] Reactor B: The reactor is at least adjustable. - including a stirring mechanism according to the invention - System for metering reaction gases - System for exhausting reaction gases - To simplify the process, a hydrogen separator (for technical description see stage 2) may be connected. In order to remove condensable or resublimable by-products in the gaseous reaction product, a vessel can be connected which allows the removal of the by-products by condensation or resublimation. - A system may be connected that allows the transfer of material to the reactor C or to a storage vessel (see step 1 for technical description).

[0115] Reactor C: The reactor is at least adjustable. - A system for removing condensable or resublimable by-products. A container may be connected which allows removal of by-products by condensation or resublimation. - a system for metering reactive gases for functionalization - System for exhausting reaction gases - A system may be connected that allows the transfer of material to the storage container (see stage 3 for technical description).

[0116] Adjustable reactors are generally reactors that can be operated so that the temperature inside the reactor can be adjusted, for example, in a range between −40 and 1000° C. Narrower temperature ranges are possible.

[0117] A cascade reactor system for the purposes of this specification is a connection of at least two reactors. There is no upper limit to the number of reactors. The number of reactors A, B, and C relative to each other, as well as their size, shape, material, and configuration, can also be different. A person skilled in the art can adjust the number of reactors and their size relative to each other in order to make the output of the cascade reactor system as efficient as possible as a whole. The reactors may be directly connected to each other or locally separated from each other, in which case the filling is carried out by a movable storage container. It is also conceivable to connect two or more reactors B to each other and carry out each reaction step in a separate reactor B.

[0118] During operation, the porous particles and the resulting silicon-containing material may generally be in the form of a fixed bed or in the form of agitated mixture. It is preferred to agitate and mix the porous particles or the resulting silicon-containing material in reactors A, B, and C. However, during the pyrolysis of the reactive components in step 2, the particles must be actively mixed. This allows, for example, for uniform contact between all the porous particles and the reactive components, or for uniform temperature distribution in the bed. The particles can be circulated, for example, by stirring the inside of the reactor or by moving the entire reactor around an agitator.

[0119] Further preferred forms of construction for reactors A, B, and C are fixed reactors with moving stirring elements for circulation. The purpose of circulation is to contact the porous solid with the gaseous reactive components as uniformly as possible. Preferred geometries for this purpose are cylindrical reactors, conical reactors, spherical, polyhedral, rotationally symmetric reactors, or combinations thereof. The stirring element movement is preferably rotational. Other forms of movement are also suitable. The stirring elements are preferably driven via a stirring shaft, and there may be one stirring element or multiple stirring elements per stirring shaft. Reactors A, B, and C may incorporate multiple stirring shafts, each of which may have one stirring element or multiple stirring elements. The main reactor axis is preferably aligned horizontally or vertically. In further preferred embodiments, the stirring shaft is installed horizontally or vertically in any orientation of the reactor. For vertically operated reactors A, B, and C, a preferred configuration is, for example, one in which the stirring element or multiple stirring elements mix the bed material by rotational movement with the main stirring shaft. A further possibility is a configuration in which two or more agitator shafts run parallel to each other. Another possibility is a configuration in which two or more agitator shafts do not operate parallel to each other. Another form of construction for vertically operated reactors A, B, or C is characterized by the use of a screw conveyor. The screw conveyor preferably transports the bed material centrally. A further design according to the invention is a screw conveyor (Nauta® Mixer, Hosokawa) that rotates along the edge of the reactor. Another preferred form of construction is a planetary or spiral agitation system. For horizontally operated reactors A, B, or C, a preferred configuration is, for example, one in which a stirring element or multiple stirring elements mix the bed material by rotational movement with the main agitator shaft. A configuration in which two or more agitator shafts run parallel to each other is also possible. Even more preferred is a configuration in which two or more agitator shafts do not operate parallel to each other.For reactors A, B, or C operated vertically, preferred stirring elements are elements selected from the group including helical stirrers, spiral stirrers, anchor stirrers, or generally stirring elements that convey bed material axially or radially, or both axially and radially, and exhibit the proximity clearance W according to the invention. For reactors A, B, or C operated horizontally, it is preferred to have multiple stirring elements on one shaft. Configurations according to the invention for stirring elements of horizontally operated reactors are, for example, plowshares, paddles, blade stirrers, spiral stirrers, or generally stirring elements that convey bed material both axially and radially, and exhibit the proximity clearance W according to the invention. The proximity clearance can be reduced by additional scrapers on the stirring elements. In addition to moving stirring elements, reactors A, B, or C can also include rigid interiors such as baffles.

[0120] In principle, any material is suitable for constructing reactors A, B, or C for carrying out the process of the present invention, provided that it has the necessary mechanical strength and chemical resistance under the respective operating conditions. With regard to chemical resistance, reactors A, B, or C can be made of corresponding solid materials as well as chemically non-resistant materials (pressure-resistant) with specific coatings or platings on the parts in contact with the medium.

[0121] These materials are selected according to the invention from the group comprising: - metallic materials corresponding to (according to DIN CEN ISO / TR 15608) material groups 1 to 11 steels, groups 31 to 38 nickel and nickel alloys, groups 51 to 54 titanium and titanium alloys, groups 61 and 62 zirconium and zirconium alloys, and groups 71 to 76 cast irons; - ceramic materials, including oxide ceramics in single-substance systems, such as aluminum oxide, magnesium oxide, zirconium oxide, titanium dioxide (capacitor materials), and multi-substance systems, such as aluminum titanate (a mixed form of aluminum oxide and titanium oxide), mullite (a mixed form of aluminum oxide and silicon oxide), lead zirconate titanate (piezoceramics), or dispersed ceramics such as aluminum oxide reinforced with zirconium oxide (ZTA - Zirconia reinforced aluminum oxide) - Al2O3 / ZrO2); non-oxide ceramics, such as carbides, e.g. silicon carbide and boron carbide, nitrides, e.g. silicon nitride, aluminum nitride, boron nitride and titanium nitride, borides and silicides, and mixtures thereof; - composite materials from the group of granular composites, such as, for example, cemented carbides, ceramic composites, concrete and polymer concrete, fibre composites, such as, for example, glass fibre reinforced glass, metal matrix composites (MMC), fibre cement, carbon fibre reinforced silicon carbide, self-reinforced thermoplastics, steel reinforced concrete, fibre reinforced concrete, fibre plastic composites, such as, for example, carbon fibre reinforced plastics (CRP), glass fibre reinforced plastics (GRP) and aramid fibre reinforced plastics (ARP), fibre ceramic composites (ceramic matrix composites (CMC)), permeated composites such as, for example, metal matrix composites (MMC), dispersion reinforced aluminium alloys or dispersion hardened nickel-chromium superalloys, layered composites, such as, for example, bimetals, titanium-graphite composites, composite plates and tubes, glass fibre reinforced aluminium and sandwich structures, and structural composites.

[0122] The porous particles for the process of the present invention are preferably selected from the group comprising hard carbon, soft carbon, mesocarbon, microbeads, natural or synthetic graphite, amorphous carbon in the form of single-walled and multi-walled carbon nanotubes and graphene, oxides such as silicon dioxide, aluminum oxide, mixed silicon-aluminum oxide, magnesium oxide, lead oxide and zirconium oxide, carbides such as silicon carbide and boron carbide, nitrides such as silicon nitride and boron nitride, and other ceramic materials as may be described by the following formula: Al with at least two coefficients 0≦a, b, c, d, e, f, g≦1, and a~g>0 and a*3+b*3+c*4+d*2+g*4+3*3+f*2 a B b C c Mg d N e O f Si g .

[0123] The ceramic material may be, for example, a binary, ternary, quaternary, pentanary, hexanary or heptanary compound. Preferred ceramic materials are those having the following formula: Non-stoichiometric boron nitride BN z (z=0.2~1), Non-stoichiometric carbonitride CN z (z=0.1~4 / 3), Boron carbonitride B x CN z (x=0.1 to 20 and z=0.1 to 20), where x*3+4 3 z*3, Boron nitride oxide BN z O r (z=0.1 to 1 and r=0.1 to 1), 3 3 r*2+z*3, Boron Carbonitride Oxide B x CN z O r (x=0.1 to 2, z=0.1 to 1 and r=0.1 to 1), where x*3+4 3 r*2+z*3, Silicon carboxylate Six CO z (x=0.1 to 2 and z=0.1 to 2), where x*4+4 3 z*2, Silicon carbonitride Si x CN z (x=0.1 to 3 and z=0.1 to 4), where x*4+4 3 z*3, Silicon borocarbonitride Si w B x CN z (w=0.1 to 3, x=0.1 to 2 and z=0.1 to 4), where w*4+x*3+4 3 z*3, Silicon borocarboxylate Si w B x CO z (w=0.10 to 3, x=0.1 to 2, and z=0.1 to 4), where w*4+x*3+4 3 z*2 Silicon borocarbonitride oxide Si v B w CN x O z (v=0.1 to 3, w=0.1 to 2, x=0.1 to 4 and z=0.1 to 3), where v*4+w*3+4 3 x*3+z*2, and Aluminum borosilicocarbonitride oxide Al u B v Si x CN w O z (u=0.1 to 2, v=0.1 to 2, w=0.1 to 4, x=0.1 to 2 and z=0.1 to 3), where u*3+v*3+x*4+4 3 w*3+z*2.

[0124] The porous particles have a density of 0.1 to 7 g / cm as measured by helium pycnometry. 3 is preferably 0.3 to 3 g / cm 3 This is more preferable when the volumetric capacity (mAh / cm) of a lithium-ion battery is 3 ) is advantageous in increasing the

[0125] Preferred porous particles used are amorphous carbon, silicon dioxide, boron nitride, silicon carbide and silicon nitride or mixed materials based on these materials, with the use of amorphous carbon, boron nitride and silicon dioxide being particularly preferred.

[0126] The porous particles preferably have a diameter percentile d of ≥ 0.5 μm, more preferably ≥ 1.5 μm, and most preferably ≥ 2 μm. 50 The diameter percentile d 50 is preferably ≦20 μm, more preferably ≦12 μm, and most preferably ≦8 μm.

[0127] The volume-weighted particle size distribution of the porous particles is preferably determined by the diameter percentile d 10 ≧0.2μm~d 90 ≦20.0 μm, more preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0128] The porous particles preferably have a diameter percentile d of ≦10 μm, more preferably ≦5 μm, particularly preferably ≦3 μm, and most preferably ≦2 μm. 10 The diameter percentile d 10 is preferably ≧0.2 μm, more preferably ≧0.5, and most preferably ≧1 μm.

[0129] The porous particles preferably have a diameter percentile d of ≥ 4 μm, more preferably ≥ 8 μm. 90 The diameter percentile d 90 is preferably ≦18 μm, more preferably ≦15, and most preferably ≦13 μm.

[0130] The volume-weighted particle size distribution of the porous particles preferably has a span d of ≦15.0 μm, more preferably ≦12.0 μm, very preferably ≦10.0 μm, particularly preferably ≦8.0 μm, and most preferably ≦4.0 μm. 90 -d 10 It has.

[0131] The volume weighted particle size distribution of the silicon-containing material producible by the process of the present invention preferably has a span d of ≥ 0.6 μm, more preferably ≥ 0.8 μm, and most preferably ≥ 1.0 μm. 90 -d 10 It has.

[0132] The volume-weighted particle size distribution of porous particles can be measured in accordance with ISO 13320 by static laser scattering using the Mie model with a Horiba LA 950 measuring device, using ethanol as the dispersion medium for the porous particles.

[0133] The porous particles are preferably present in the form of individualized particles. The particles may be, for example, isolated or agglomerated. The porous particles are preferably not agglomerated, and preferably not agglomerated. Agglomeration generally means that, during the production of the porous particles, primary particles are first formed and then fuse together, and / or the primary particles bond to each other, for example, via covalent bonds, thus forming agglomerates. Primary particles are usually isolated particles. Agglomerates or isolated particles can form agglomerates. Agglomerates are loose aggregates of agglomerates or primary particles connected to each other, for example, via van der Waals interactions or hydrogen bonds. Agglomerates that have agglomerated can be easily broken back into agglomerates by conventional kneading and dispersion techniques. Agglomerates cannot be broken down into primary particles by these techniques, or can only be partially broken down. The presence of porous particles in the form of agglomerates, agglomerates, or isolated particles can be visualized, for example, by conventional scanning electron microscopy (SEM). Static light scattering methods for determining particle size distribution or particle size of matrix particles, in contrast, cannot distinguish between agglomerates or agglomerates.

[0134] The porous particles may have any desired morphology, and thus may be, for example, spheroidal, plate-like, spherical, or needle-like, with spheroidal or spherical particles being preferred. The morphology can be characterized, for example, by the sphericity ψ or sphericity S. According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the object. For a sphere, the value of ψ is 1. According to this definition, the porous particles for the process of the present invention preferably have a sphericity ψ of 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0135] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle onto the surface to the measured circumference U of this projection.

number

[0136] The porous particles are preferably ≥ 0.2 cm 3 / g, more preferably ≥ 0.6 cm 3 / g, most preferably ≥ 1.0 cm 3 / g, which is useful for obtaining high-capacity lithium-ion batteries. The gas-accessible pore volume was determined by nitrogen gas sorption measurements in accordance with DIN 66134.

[0137] The porous particles are preferably open-pore. Open pore generally means that the pores are connected to the surface of the particle, for example, via channels, and are preferably capable of mass transfer with the surroundings, especially gaseous compounds. This can be verified using gas sorption measurements (evaluated by Brunauer, Emmett and Teller, "BET"), i.e., specific surface area. The porous particles are preferably ≥ 50 m 2 / g, more preferably ≥ 500m 2 / g, most preferably ≥ 1000m 2 / g. The BET specific surface area is determined in accordance with DIN 66131 (with nitrogen).

[0138] The pores of the porous particles can have any desired diameter, i.e., generally in the range of macropores (greater than 50 nm), mesopores (2-50 nm), and micropores (less than 2 nm). Porous particles can be used in any desired mixture of different pore types. Preferably, porous particles are used that have less than 30% macropores, based on the total pore volume, more preferably no macropores, and very preferably at least 50% pores with an average pore diameter of less than 5 nm. Very particularly preferably, the porous particles contain only pores with a pore diameter of less than 2 nm (determination method: pore size distribution according to BJH (gas adsorption) according to DIN 66134 in the mesopore range and Horvath-Kawazoe (gas adsorption) according to DIN 66135 in the micropore range; evaluation of the pore size distribution in the macropore range is carried out by mercury porosimetry according to DIN ISO 15901-1).

[0139] The preferred porous particles are 0.3 cm 3 / g, more preferably less than 0.15 cm 3 The gas-inaccessible pore volume is less than 1 / g. This can also increase the capacity of lithium-ion batteries. The gas-inaccessible pore volume can be determined by the following formula: Gas inaccessible pore volume = 1 / pure material density - 1 / skeletal density.

[0140] where the pure material density is the theoretical density of the porous particle based on the phase composition or density of the pure material (the density of the material as if it had no closed porosity). Data on the pure material density can be found by those skilled in the art, for example, in the Ceramic Data Portal of the National Institute of Standards (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the pure material density of silicon oxide is 2.203 g / cm 3 and the density of pure boron nitride is 2.25 g / cm 3 and the density of the pure silicon nitride material is 3.44 g / cm 3 and the density of pure silicon carbide is 3.21 g / cm 3 Skeletal density is the actual density of the (gas-accessible) porous particles as determined by helium pycnometry.

[0141] For clarity, please note that porous particles are different from silicon-containing materials.Porous particles act as the starting material for producing silicon-containing materials.Generally, preferably there is no silicon located in the pores of porous particles and on the surface of porous particles, and more specifically there is no silicon obtained by depositing silicon precursor.

[0142] The silicon-containing material obtained by the process of the present invention by deposition of silicon in the pores and on the surface of the porous particles preferably has a diameter percentile d in the range of 0.5 to 20 μm. 50 The particle size distribution has a volume weighted value of d 50 The value is preferably at least 1.5 μm, more preferably at least 2 μm or more. Diameter percentile d 50 is preferably at most 13 μm, more preferably at most 8 μm.

[0143] The volume weighted particle size distribution of the silicon-containing material is preferably determined by the diameter percentile d 10 ≧0.2μm~d 90 ≦20.0 μm, more preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0144] The silicon-containing material preferably has a diameter percentile d of ≦10 μm, more preferably ≦5 μm, particularly preferably ≦3 μm, most preferably ≦1 μm. 10 The diameter percentile d 10 is preferably ≧0.2 μm, more preferably ≧0.4 μm, and most preferably ≧0.6 μm.

[0145] The silicon-containing material preferably has a diameter percentile d of ≥ 5 μm, more preferably ≥ 10 μm. 90 The diameter percentile d 90 is preferably ≦20 μm, more preferably ≦15 μm, and most preferably ≦12 μm.

[0146] The volume-weighted particle size distribution of the silicon-containing material preferably has a span d of ≦15.0 μm, more preferably ≦12.0 μm, more preferably ≦10.0 μm, particularly preferably ≦8.0 μm, and most preferably ≦4.0 μm. 90 -d 10 The volume weighted particle size distribution of the silicon-containing material preferably has a span d of ≥ 0.6 μm, more preferably ≥ 0.8 μm, and most preferably ≥ 1.0 μm. 90 -d 10 It has.

[0147] The particles of silicon-containing material are preferably in the form of particles.Particles can be isolated or agglomerated.The silicon-containing material is preferably not agglomerated, and preferably not agglomerated.The terms isolated, agglomerated and non-agglomerated have already been defined above in relation to porous particles.The existence of the silicon-containing material in the form of agglomerates or agglomerates can be visualized, for example, by conventional scanning electron microscope (SEM).

[0148] The silicon-containing material may have any desired morphology, and thus may be, for example, shard, platelet, spherical or needle-like, with shard or spherical particles being preferred.

[0149] According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the object. For a sphere, the value of ψ is 1. According to this definition, the silicon-containing materials usable by the process of the present invention preferably have a sphericity ψ of 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0150] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle onto the surface to the measured circumference U of this projection.

number

[0151] The cycling stability of lithium-ion batteries can be further enhanced by the morphology, material composition, and especially the specific surface area or internal porosity of silicon-containing materials.

[0152] The silicon-containing material preferably contains 10 to 90 wt. %, more preferably 20 to 80 wt. %, very preferably 30 to 60 wt. %, and particularly preferably 40 to 50 wt. % of porous particles, based on the total weight of the silicon-containing material.

[0153] The silicon-containing material preferably contains 10 to 90 wt. %, more preferably 20 to 80 wt. %, very preferably 30 to 60 wt. %, and particularly preferably 40 to 50 wt. % silicon obtained by deposition from a silicon precursor (preferably determined by elemental analysis such as ICP-OES), based on the total weight of the silicon-containing material.

[0154] When the porous particles contain a silicon compound in the form of silicon dioxide, for example, the above-mentioned weight percent value of silicon obtained through deposition from a silicon precursor can be determined by subtracting the mass of silicon in the porous particles confirmed by elemental analysis from the mass of silicon in the silicon-containing material confirmed by elemental analysis, and dividing the result by the mass of the silicon-containing material.

[0155] The volume of silicon deposited in the porous particles was calculated by multiplying the mass fraction of silicon obtained by deposition from the silicon precursor as a percentage of the total mass of the silicon-containing material by the density of silicon (2.336 g / cm 3 ) is the result.

[0156] The pore volume P of a silicon-containing material is the sum of the gas-accessible pore volume and the gas-inaccessible pore volume. The Gurwitsch gas-accessible pore volume of a silicon-containing material can be determined by gas sorption measurements using nitrogen according to DIN 66134.

[0157] The gas inaccessible pore volume of a silicon-containing material can be determined using the following formula: Gas inaccessible pore volume = 1 / skeletal density - 1 / pure material density.

[0158] Wherein, the pure material density of silicon-containing material is the theoretical density that can be calculated by multiplying the sum of the theoretical pure material densities of the components contained in silicon-containing material by their respective weight-based proportions in the whole material.Therefore, for example, in the case of silicon-containing material in which silicon is deposited on porous particles, Pure material density = theoretical pure material density of silicon * percentage of silicon in weight % + theoretical pure material density of porous particles * percentage of porous particles in weight %.

[0159] Data regarding pure material density can be obtained by those skilled in the art, for example, from the Ceramic Data Portal of the National Institute of Standards (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the pure material density of silicon oxide is 2.203 g / cm. 3 and the density of pure boron nitride is 2.25 g / cm 3 and the density of the pure silicon nitride material is 3.44 g / cm 3 and the density of pure silicon carbide is 3.21 g / cm 3 is.

[0160] The pore volume P of the silicon-containing material is preferably in the range of 0 to 400 vol%, more preferably in the range of 100 to 350 vol%, and particularly preferably in the range of 200 to 350 vol%, based on the volume of silicon contained in the silicon-containing material and obtained from the deposition of the silicon precursor.

[0161] The pores contained in the silicon-containing material may be gas-accessible or gas-inaccessible. The volume ratio of gas-accessible pores to gas-inaccessible pores in the silicon-containing material can generally be in the range of 0 (no gas-accessible pores) to 1 (all pores are gas-accessible). The volume ratio of gas-accessible pores to gas-inaccessible pores in the silicon-containing material is preferably in the range of 0 to 0.8, more preferably in the range of 0 to 0.3, and particularly preferably in the range of 0 to 0.1.

[0162] The pores of the silicon-containing material can have any desired diameter, for example, within the range of macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). The silicon-containing material can also contain any desired mixture of different pore types. The silicon-containing material preferably contains up to 30% macropores based on the total pore volume, particularly preferred are silicon-containing materials that do not have macropores, and very particularly preferred are silicon-containing materials in which at least 50% of the pores based on the total pore volume have an average pore diameter of less than 5 nm. More particularly preferred are silicon-containing materials that only have pores with a diameter of up to 2 nm.

[0163] The silicon-containing material preferably comprises silicon structures having a structure size in at least one dimension of at most 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (determination method: scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)).

[0164] The silicon-containing material preferably comprises a silicon layer having a layer thickness of less than 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (determination method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The silicon-containing material may also comprise silicon in the form of particles. The silicon particles preferably have a diameter of at most 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (determination method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The numerical value of the silicon particles here is preferably based on the diameter of the circle around the particle in the microscope image.

[0165] The silicon-containing material is preferably at most 100 m 2 / g, more preferably 30m 2 / g, particularly preferably less than 10m 2 / g。 The BET specific surface area is determined in accordance with DIN 66131 (using nitrogen). Therefore, when the silicon-containing material is used as an active material for the anode of a lithium-ion battery, SEI formation can be reduced and the initial coulombic efficiency can be increased.

[0166] The silicon in the silicon-containing material deposited from the silicon precursor may further comprise a dopant selected from the group including, for example, Li, Fe, Al, Cu, Ca, K, Na, S, Cl, Zr, Ti, Pt, Ni, Cr, Sn, Mg, Ag, Co, Zn, B, P, Sb, Pb, Ge, Bi, rare earths, or combinations thereof. Lithium and / or tin are preferred. The amount of dopant in the silicon-containing material is preferably at most 1 wt. %, more preferably at most 100 ppm, based on the total weight of the silicon-containing material, and can be determined by ICP OES.

[0167] Silicon-containing materials generally have surprisingly high stability under compressive load and / or shear load.The pressure stability and shear stability of silicon-containing materials are revealed, for example, by the absence or substantial absence of change in the porous structure of silicon-containing materials under compressive load (for example, when compressing an electrode) and shear load (for example, when preparing an electrode) in SEM.

[0168] The silicon-containing material may optionally further comprise an element such as carbon. Carbon is preferably present in the form of a thin layer with a layer thickness of at most 1 μm, preferably less than 100 nm, more preferably less than 5 nm, and very preferably less than 1 nm (measurable by SEM or HR TEM). These carbon layers can be present both in the pores and on the surface of the silicon-containing material. The order of different layers in the silicon-containing material through the corresponding repetition of alternate metering of different precursors, and their number, are also arbitrary. Thus, first, there may be a layer of an additional material different from the porous particles, such as carbon, on the porous particles, and this layer may have a silicon layer or a layer of silicon particles. It is also possible that there is a layer of an additional material different from or the same as the material of the porous particles on the silicon layer or layer of silicon particles, regardless of whether there is an additional layer of a material different from the material of the porous particles between the porous particles and the silicon layer or layer made of silicon particles.

[0169] The silicon-containing material preferably contains ≦50 wt%, more preferably ≦40 wt%, particularly preferably ≦20 wt% of additional elements. The silicon-containing material preferably contains ≧1 wt%, more preferably ≧3 wt%, particularly preferably ≧2 wt% of additional elements. The weight percentages are based on the total weight of the silicon-containing material. In an alternative embodiment, the silicon-containing material does not contain additional elements.

[0170] Further subject matter of the present invention is the use of a silicon-containing material as an active material in an anode material for an anode of a lithium-ion battery, and the use of such an anode for producing a lithium-ion battery.

[0171] The anode material is preferably based on a mixture comprising a silicon-containing material accessible by the process of the present invention, one or more binders, optionally graphite as a further active material, optionally one or more further conductive components, and optionally one or more additives.

[0172] The use of an additional conductive component in the anode material can reduce the contact resistance within the electrode and between the electrode and the current collector, thereby improving the current-carrying capacity of the lithium-ion battery of the present invention. Examples of preferred additional conductive components are conductive carbon black, carbon nanotubes, or metal particles, such as copper.

[0173] The anode material preferably comprises 0 to 95 wt %, more preferably 0 to 40 wt %, and most preferably 0 to 25 wt %, of one or more further conductive components, based on the total weight of the anode material.

[0174] In the anode of a lithium ion battery, the silicon-containing material may be present preferably at 5 to 100 wt %, more preferably at 30 to 100 wt %, and most preferably at 60 to 100 wt %, based on the total active material present in the anode material.

[0175] Preferred binders are polyacrylic acid or its alkali metal salts, more specifically lithium or sodium salts, polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, particularly polyamideimides, or thermoplastic elastomers, particularly ethylene-propylene-diene terpolymers. Alkali metal salts of the above binders, particularly lithium or sodium salts, are also particularly preferred. All or, preferably, a portion of the acid groups of the binder may be present in the form of a salt. The binder preferably has a molar mass of 100,000 to 1,000,000 g / mol. A mixture of two or more binders may also be used.

[0176] Generally, natural or synthetic graphite can be used as the graphite. The graphite particles preferably have a diameter percentile d 10 >0.2μm~d 90 <200 μm.

[0177] Examples of additives are pore formers, dispersants, flow control agents or dopants, such as elemental lithium.

[0178] A preferred formulation for the anode material preferably comprises 5-95 wt. % silicon-containing material, 0-90 wt. % further conductive component, 0-90 wt. % graphite, 0-25 wt. % binder, and 0-80 wt. % additive, the weight percentages being based on the total weight of the anode material and the fractions of all components of the anode material adding up to 100 wt. %.

[0179] The components of the anode material that make up the anode ink or anode paste are preferably processed in a solvent, preferably selected from the group comprising water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide and ethanol, and mixtures of these solvents, preferably using a rotor-stator machine, a high-energy mill, a planetary kneader, an agitator ball mill, a shaker plate or an ultrasonic device.

[0180] The anode ink or anode paste preferably has a pH of 2 to 8.5 (measured, for example, at 20° C. using a WTW pH340i pH meter equipped with a SenTix RJD probe).

[0181] The anode ink or anode paste can be applied, for example, to a copper foil or another current collector by a doctor blade. Other coating methods, such as spin coating, roller coating, dip or slot die coating, painting or spraying, can also be used in accordance with the present invention.

[0182] Prior to coating the copper foil with the anode material of the present invention, the copper foil may be treated with a commercially available primer, for example based on a polymer resin or silane, which can provide improved adhesion to the copper but which generally has no substantial electrochemical activity itself.

[0183] The anode material is usually dried to a constant weight. The drying temperature depends on the components and solvent used. The drying temperature is preferably between 20 and 300°C. The layer thickness, meaning the dry layer thickness of the anode coating, is preferably between 2 and 500 µm.

[0184] Finally, the electrode coating may be calendered to set a defined porosity. The electrode thus produced preferably has a porosity of 15 to 85%, which can be measured by mercury porosimetry according to DIN ISO 15901-1. Preferably, 25 to 85% of the pore volume thus determined is made up of pores with diameters of 0.01 to 2 μm.

[0185] A further subject of the present invention is a lithium-ion battery comprising a cathode, an anode comprising an etched silicon-containing material, two electrically conductive connections to these electrodes, a separator, an electrolyte in which the separator and the two electrodes are impregnated, and a casing containing the above-mentioned components.

[0186] In the context of the present invention, the term lithium-ion battery also encompasses cells. A cell generally comprises a cathode, an anode, a separator, and an electrolyte. In addition to one or more cells, a lithium-ion battery preferably further comprises a battery management system. The battery management system generally serves to control the battery, for example by means of electronic circuits, in particular to recognize the state of charge, to protect against deep discharge, or to protect against overcharging.

[0187] Preferred cathode materials that can be used in accordance with the present invention include lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide (doped or undoped), lithium manganese oxide (spinel), lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium vanadium phosphate, or lithium vanadium oxide.

[0188] The separator is generally an electrically insulating, ion-permeable membrane, preferably made of polyolefin, such as polyethylene (PE) or polypropylene (PP), or polyester, or a corresponding laminate. Alternatively, as is customary in battery manufacturing, the separator may consist of or be coated with a glass or ceramic material. The separator traditionally separates the first electrode from the second electrode, thereby preventing a conductive connection (short circuit) between the electrodes.

[0189] The electrolyte is preferably a solution containing one or more lithium salts (=conductive salts) in an aprotic solvent. The conductive salts are preferably selected from the group consisting of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium imide, lithium methide, lithium trifluoromethanesulfonate LiCF3SO3, lithium bis(trifluoromethanesulfonimide) LiN(CF3SO2)2, and lithium borate. The concentration of the conductive salt, based on the solvent, is preferably from 0.5 mol / L to the solubility limit of the salt in question. The concentration is more preferably from 0.8 to 1.2 mol / L.

[0190] The solvents used, individually or as mixtures thereof, are preferably cyclic carbonates, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethoxyethane, diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, acetonitrile, organic esters of carbonic acid, or nitriles.

[0191] The electrolyte preferably contains a film-forming agent, such as vinylene carbonate or fluoroethylene carbonate. In this way, it is possible to achieve a significant improvement in the cycling stability of anodes containing etched silicon-containing materials obtained according to the process of the present invention. This improvement is primarily due to the formation of a solid electrolyte interfacial phase on the surface of the active particles. The proportion of the film-forming agent in the electrolyte is preferably between 0.1 and 20.0 wt. %.

[0192] In order to best match the actual capacities of the electrodes of a lithium-ion cell, it is advantageous to balance the positive and negative electrode materials in terms of absolute capacity. Of particular importance in this context is the fact that during the first or initial charge / discharge cycle (known as activation) of a secondary lithium-ion cell, a coating layer forms on the surface of the electrochemically active material in the anode. This coating layer, called the solid electrolyte interphase (SEI), generally consists primarily of electrolyte decomposition products and a certain amount of lithium, and is therefore no longer available for further charge / discharge reactions. The thickness and composition of the SEI depend on the anode material used and the nature and quality of the electrolyte solution used.

[0193] In the case of graphite, the SEI is particularly thin. On graphite, there is typically a loss of 5-35% of the mobile lithium during the first charging step, with a corresponding decrease in the reversible capacity of the battery.

[0194] In the case of an anode having an etched silicon-containing active material obtained by the process of the present invention, the first charging step is preferably accompanied by a loss of mobile lithium of at most 30%, more preferably at most 20%, and most preferably at most 10%, which is far below the values ​​described in the prior art, for example in US Pat. No. 10,147,950 B1.

[0195] All of the substances and materials utilized in the manufacture of such lithium-ion batteries as described above are known, and the manufacture of the components of such batteries and their assembly to obtain the batteries is carried out according to processes known in the art of battery manufacturing.

[0196] The silicon-containing materials obtained by the process of the present invention are notable for their significantly improved electrochemical properties, resulting in lithium-ion batteries with high volumetric capacity and excellent performance characteristics. The silicon-containing materials obtained by the process of the present invention are permeable to lithium ions and electrons, thus enabling charge transport. The SEI in lithium-ion batteries can be significantly reduced by the silicon-containing materials obtained by the process of the present invention. Furthermore, due to the design of the silicon-containing materials obtained by the process of the present invention, the peeling of the SEI from the surface of the active material no longer exists or is at least significantly reduced. All of this results in high cycle stability in the components of such lithium-ion batteries whose anodes contain silicon-containing materials obtainable by the process of the present invention.

[0197] The following examples serve to further elucidate the invention described herein.

[0198] The analytical methods and instruments used for characterization were as follows:

[0199] Inorganic analysis / elemental analysis: The carbon contents reported in the examples were confirmed using a Leco CS230 analyzer, and a Leco TCH-600 analyzer was used for the determination of oxygen and, where appropriate, nitrogen and hydrogen contents. Qualitative and quantitative determination of other reported elements was performed by inductively coupled plasma (ICP) optical emission spectrometry (Optima 7300 DV, Palkin Elmer). For this analysis, samples were subjected to acid digestion (HF / HNO3) in a microwave (Microwave 3000, Anton Paar). ICP-OES determinations were guided by ISO 11885 ("Water quality - Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885:2007), German translation EN ISO 11885:2009"), which is used for the analysis of acidic aqueous solutions (e.g., drinking water, acidified samples of wastewater and other waters, aqua regia extracts of soils and sediments).

[0200] Particle size determination: In the context of the present invention, particle size distribution was determined by static laser scattering using a Horiba LA 950 in accordance with ISO 13320. Particular attention must be paid to the dispersion of particles in the measurement solution during sample preparation, to avoid measuring the size of weak agglomerates rather than individual particles. For the measurements, the particles were dispersed in ethanol. For this purpose, the dispersion was treated with 250 W ultrasonic waves for 4 minutes in a Hielscher model UIS250v ultrasonic laboratory instrument equipped with an LS24d5 sonotrode, if necessary, prior to the measurements.

[0201] BET specific surface area measurement: The specific surface area of ​​the materials was measured by gas adsorption with nitrogen by the BET method (measurement according to DIN ISO 9277:2003-05 with nitrogen) using a Sorptomatic 199090 instrument (Porotec) or a SA-9603MP instrument (Horiba).

[0202] Bone Density: The skeletal density, i.e. the density of the porous solid based on the volume of the externally gas-accessible pore space only, was determined by He pycnometry according to DIN 66137-2.

[0203] Gas-accessible pore volume: The Gurwitsch gas-accessible pore volume was determined by gas sorption measurements with nitrogen according to DIN 66134.

[0204] Conversion rate: The conversion is calculated as the ratio of the molar amount of converted starting material (reactant) to the molar amount of starting material (reactant) used. In these examples, the conversion indicates how many of the SiH4 molecules used are converted to Si.

number

[0205] yield: The yield is the ratio of the mass of the product actually obtained to the theoretically possible maximum mass of the product. The yield is expressed as a mass ratio amount in percent.

number

[0206] It is a measure of the loss of particles entrained by the gas flow. [Example]

[0207] The grade 4.0 SiH4 used was obtained from Linde GmbH.

[0208] In all of the examples, the following amorphous carbon was used as the porous starting material: - Specific surface area=1907m 2 / g - Pore volume = 0.96 cm 3 / g - Average volume-weighted particle size D50 = 2.95 μm - Particle density=0.7g / cm 3 - Cohesiveness, Geldart classification: C

[0209] The reactors used in carrying out the experimental examples were as follows:

[0210] Reactor (present invention): All inventive examples are carried out within a specific variant of the process, where reactors A, B and C are the same vessel. The reactor used has an inner radius r B The reactor consisted of a cylindrical lower part (beaker) with a diameter of 121.5 mm and a height of h = 512 mm, a lid with several connections (e.g., gas supply, gas exhaust, temperature measurement, and pressure measurement), and a flat base. There were no internal walls. The volume of the reactor was V B = 24 L. The circumference of any cross section of the rotation surface generated by rotating the reactor inner contour around the rotation axis is calculated to be 763.4 mm. The agitator used has a radius r R The agitator was a multi-flight helical agitator with a diameter of 119.5 mm. A complete revolution of the helical agitator generates a rotating surface. The circumference of any cross section perpendicular to the axis of rotation of this rotating surface is 750.8 mm. The two circumferences result in a close clearance of W = 0.98. The height of the helix corresponds to approximately 75% of the clear height inside the reactor. The reactor was filled so that the height of the stirred particle bed was lower than the height of the helix. Thus, more than 50% of the reaction zone is in the region of the agitator with a close clearance of W = 0.98. The beaker was electrically heated with a jacket heater. Temperatures were measured primarily between the heater and the reactor. Gas was supplied to the lower half of the bed (125 mm above the base of the reactor) through two dip tubes with an outer diameter of d = 6 mm, introducing the gas directly into the stirred bed.

[0211] Fluidized bed reactor (non-invention): The fluidized-bed reactor used in Non-Inventive Comparative Example 1 consisted of a cylindrical section with an outer diameter of 160 mm and a height of 1200 mm. The cylindrical section consisted of the bottom chamber and the fluidized-bed reactor itself. These two sections were separated from each other by a gas-permeable base. The upper part of the cylindrical reactor section was followed by a reactor section whose cross section expanded to twice its cross-sectional area compared to the cylindrical reactor section. The upper end of the reactor had a lid with a filter element for discharging gas. The reaction temperature was controlled by heating the reactor wall, and the height of the heated zone was 80% of the cylindrical length starting from the gas-permeable base. The metering factor used for the process temperature was the temperature between the heating jacket and the outer reactor wall. Heating was electrical. Therefore, the fluidizing gas was preheated with a gas heater before flowing into the fluidized-bed reactor. The fluidizing gas flow was pulsed using a directly controlled magnetic valve. The fluidization index was used as a measure of the quality of the fluidized bed.

[0212] In preliminary tests, the minimum fluidization velocity was determined by measuring the pressure drop across the fluidized bed.

[0213] Definition of fluidization index: The fluidization index FI is defined as the pressure drop Δp measured across the fluidized bed. WS,measured and the theoretically achievable maximum pressure loss Δp WS,th It is defined as the ratio of and calculated by the following formula 1.

number

[0214] Floor mass m S , acceleration due to gravity g, and reactor cross-sectional area A WS From this, ignoring the gas density, the theoretically achievable maximum pressure drop is Δp WS,th =m S g / A WS Calculate as follows.

[0215] In the case of a fully fluidized bed, the fluidization index is set to a value of 1 or less.

[0216] Determining the Fluidization Index: The fluidization index is the ratio of the measured pressure drop to the theoretically possible maximum pressure drop. To determine the fluidization index, it is necessary to capture the pressure drop in the fluidized bed by technical measurements. The pressure drop is measured as a differential pressure between the lower and upper ends of the fluidized bed. The differential pressure instrument converts the pressure detected on the membrane into a digital value and displays the pressure difference. The pressure measurement lines must be configured so that they are positioned directly above the gas-permeable base and directly above the fluidized bed. To determine the fluidization index, accurate capture of the weight of the introduced particle bed is also required. See also [VDI-Waermeatlas, 11th Edition, Section L3.2 Flow Forms and Pressure Loss in Fluidized Beds, pp. 1371-182, Springer Verlag, Berlin Heidelberg, 2013].

[0217] Determining the Minimum Fluidization Velocity: The minimum fluidization velocity is the fluidization gas velocity (based on the empty reactor cross-sectional area) at which the particle bed transitions from a fixed bed across flow to a fluidized bed. The minimum fluidization velocity can be determined by simultaneously measuring the regulated fluidization gas flow using a mass flow meter and the pressure drop across the fluidized bed using a digital differential pressure meter. Knowing the reactor cross-sectional area, the fluidization gas velocity can be calculated from the measured fluidization gas flow. The plotted profile of pressure drop versus fluidization gas velocity is called the characteristic fluidized bed line. Note that the characteristic fluidized bed line is recorded starting from a high fluidization gas velocity and gradually reducing this velocity. For pure fixed-bed across flow, the pressure drop increases linearly. The associated fluidization index, FI, is less than 1. For a fully formed fluidized bed, the measured pressure drop is constant. The associated fluidization index, FI, is 1. The state of minimum fluidization lies in the transition between these two ranges. The associated fluidization gas velocity based on the empty reactor cross-sectional area is equal to the minimum fluidization velocity. If the transition from a fixed bed to a fluidized bed is characterized by a range, the intersection of the extrapolated characteristic fixed bed line and the extrapolated characteristic fluidized bed line is defined as the minimum fluidization point. [See also VDI-Waermeatlas 11th Edition, Section L3.2 Flow forms and pressure loss in fluidized beds, pp. 1371-1382, Springer Verlag, Berlin Heidelberg, 2013].

[0218] Rotary tubular furnace reactor (non-invention): In non-inventive comparative example 2, an indirectly heated rotary tube furnace was used. This rotary tube furnace had a quartz glass rotary tube that could rotate around its longitudinal axis, had a diameter of 20 cm, and a heatable volume of 30 L. The temperature of the outer wall of the quartz tube was used as a measure of the process temperature. Heating was performed electrically and could be adjusted through three zones. For the silicon infiltration reaction to be carried out, the rotary tube should have an airtight seal.

[0219] Comparative Example 1 (Fluidized Bed, Non-Invention): Production of Silicon-Containing Materials in a Fluidized Bed Reactor Using Pulsed Fluidizing Gas Flow

[0220] Amorphous carbon (specific surface area = 1907 m) as a porous starting material 2 / g, pore volume = 0.96 cm 3 / g, mean volume-weighted particle size D 50 =2.95μm, particle density=0.7g / cm 3 , Geldart Class C particles) were introduced into the reactor.

[0221] The particle bed was fluidized with nitrogen gas, with the gas volume set to at least three times the minimum fluidization velocity determined in preliminary tests. Simultaneously, a magnetic valve was used to oscillate the gas flow at a frequency of 3 Hz between the open and closed positions of the valve. The temperature in the reactor was then increased to a set temperature of 430°C. For this temperature increase, the fluidization gas flow was adjusted to achieve a fluidization index greater than 0.95.

[0222] When the set temperature of 430°C was reached, the fluidizing gas was replaced with a reactive gas containing 10% by volume of SiH4. The pulsation of the gas flow with a frequency of 3 Hz between the open and closed positions of the valve was maintained during and after the switching of the fluidizing gas, and in addition, the gas amount of the fluidizing gas was adjusted so that the fluidizing index value was always greater than 0.95, not only due to the fluidization index value of FI=0.98, but also due to the change in the density of the porous starting material during the deposition of silicon.

[0223] After a reaction time of 2.6 hours, the fluidizing gas was switched to a pulsed flow of nitrogen. The heating power was reduced. When a temperature of 50°C was reached, the fluidizing gas flow was switched to a fluidizing gas consisting of 5% by volume of oxygen in nitrogen and maintained for 60 minutes to allow for controlled reaction of any reactive groups present on the surface of the resulting product. The reactor was then cooled to room temperature.

[0224] After the operation was completed, 990 g of black solid was discharged from the reactor. The resulting silicon-containing material was introduced into a cylindrical container and homogenized using a drum hoop mixer. The weak agglomerates formed as a result of the fluidized bed process could be removed by sieving. The reaction conditions for the preparation and the physical properties of the silicon-carbon composite particles are summarized in Table 2.

[0225] Comparative Example 2 (Rotary Tubular Furnace, Non-Invention): Production of Silicon-Containing Materials by a Non-Invention Process in a Rotary Tubular Reactor

[0226] The same porous carbon (specific surface area = 1907 m) as in Comparative Example 1 was placed in a rotating tube reactor (internal volume: 30 L). 2 / g, pore volume = 0.96 cm 3 / g, mean volume-weighted particle size D 50 =2.95μm, particle density=0.7g / cm 3 After inerting with nitrogen, the reactor was heated to 430 °C. Once the reaction temperature was reached, reactive gas (10% SiH in N, metered at a rate of 0.4 g Si / (c 3 m*h)) was passed through the reactor for 8.5 hours, during which time the reactor was rotated at a speed of approximately 7 revolutions per minute. The reactor was then purged with inert gas. Before removing the product from the reactor, the reactor was cooled to room temperature under inert gas. The reaction conditions for production and the physical properties of the silicon-carbon composite particles are summarized in Table 2.

[0227] Examples 1-5 (Invention): Production of silicon-containing materials by the process of the invention using monosilane SiH4 as a silicon precursor under standard pressure (0.1 MPa) (the values ​​of parameters A-D and the example numbers are summarized in Table 1).

[0228] In step 1 of the process, 2.4 kg of the same porous carbon (specific surface area = 1907 m) as in Comparative Examples 1 and 2 was added. 2 / g, pore volume = 0.96 cm3 / g, average volume-weighted particle size D 50 =2.95μm, particle density=0.7g / cm 3, Geldart class C particles) was introduced into a reactor of the invention equipped with a stirring mechanism (volume 24 L, diameter 25 cm). The reactor was then adjusted to 350°C for 240 minutes and inerted with nitrogen.

[0229] In Stage 2, the reactor was heated to 430°C. When this reaction temperature was reached, reactive gas was passed through the reactor for C hours at a metered feed rate B based on a concentration of A mol% and pore volume. The gas phase was fed to the reactor, and the particle bed was circulated by a helical agitator, a close clearance agitation mechanism of the present invention, so that the ratio of the circulation time to the mean residence time of the reactants was D and the bed dynamics could be expressed by a Froude number of 3.

[0230] In step 3, the silicon-containing material is cooled to a temperature of 70 ° C. over 120 minutes. Then, the reactor is purged with nitrogen for 1 hour, with lean air having an oxygen fraction of 5% by volume for 1 hour, with lean air having an oxygen fraction of 10% by volume for 1 hour, with lean air having an oxygen fraction of 15% by volume for 1 hour, and then with air for 1 hour. Finally, the product is taken out of the reactor.

[0231] [Table 1]

[0232] The reaction conditions for preparation and physical properties of the silicon-carbon composite particles are summarized in Table 2 below.

[0233] [Table 2]

[0234] Equivalent physical properties were obtained regardless of the reactor used, however, SiH conversion, product yield and reaction time could be improved in the reactor system of the present invention compared to the fluidized bed and rotary tubular furnace.

[0235] <Evaluation of silicon composite particles in electrochemical cells> Example 6: Anodes containing the silicon-containing materials obtained by the process of the present invention from Examples 1 to 5, the silicon-containing materials obtained by non-invention processes from Comparative Examples 1 and 2, and the silicon-containing material produced by the process of the present invention, and electrochemical testing in lithium-ion batteries of the present invention.

[0236] 29.71 g of polyacrylic acid (Sigma-Aldrich, Mw ∼450,000 g / mol, dried to constant weight at 85 °C) and 756.60 g of deionized water were stirred on a shaker (290 L / min) for 2.5 hours until the polyacrylic acid was completely dissolved. The solution was mixed with lithium hydroxide monohydrate (Sigma-Aldrich) in small increments until the pH reached 7.0 (measured using a WTW pH340i pH meter and SenTix RJD probe). The solution was then mixed on a shaker for an additional 4 hours. 3.87 g of the neutralized polyacrylic acid solution and 0.96 g of graphite (Imerys, KS6L C) were placed in a 50 ml container and mixed at 2000 rpm in a planetary mixer (SpeedMixer, DAC 150 SP). Next, 3.35 g of each of the silicon-containing materials obtained by the inventive process in Examples 1 to 5 and 3.35 g of each of the silicon-containing materials obtained by the non-inventive process in Comparative Examples 1 and 2 were stirred at 2000 rpm for 1 minute. Then, 1.21 g of an 8% dispersion of conductive carbon black and 0.8 g of deionized water were added and introduced into a planetary mixer at 2000 rpm. This was followed by dispersion in a dissolver at 3000 rpm for 30 minutes at a constant temperature of 20°C. The ink was again degassed under reduced pressure in the planetary mixer at 2500 rpm for 5 minutes.

[0237] The finished dispersion was then applied to a copper foil (Schlenk Metallfolien, SE-Cu58) with a thickness of 0.03 mm using a film drawing frame (Erichsen, Model 360) with a slot height of 0.1 mm. The anode coating thus produced was then dried for 60 minutes at 50°C and 1 bar air pressure. The average surface weight of the dried anode coating was 3.0 mg / cm. 2 and the coating density is 0.8 g / cm 3 It was.

[0238] Electrochemical studies were carried out in a two-electrode button cell (CR2032 type, Hosen). The electrode coating was used as the counter electrode or negative electrode (Dm = 15 mm). The content was 94.0% and the concentration was 15.9 mg / cm. 2 A lithium nickel manganese cobalt oxide 6:2:2 based coating (obtained from SEI) with an average basis weight of 1000 kJ / cm2 was used as the working electrode or positive electrode (D = 15 mm). A glass fiber filter paper (Whatman, GD Type D) impregnated with 60 μl of electrolyte was used as the separator (D = 16 mm). The electrolyte used consisted of a 1.0 molar solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of fluoroethylene carbonate and diethyl carbonate. The cell was assembled in a glove box (<1 ppm H2O, O2), and the water content in the dry mass of all components used was less than 20 ppm.

[0239] Electrochemical testing was performed at 20 °C. The cells were charged by the cc / cv (constant current / constant voltage) method at a constant current of 5 mA / g (corresponding to C / 25) for the first cycle and 60 mA / g (corresponding to C / 2) for subsequent cycles. After reaching a voltage limit of 4.2 V, the cells were charged at a constant voltage until the current fell below 1.2 mA / g (corresponding to C / 100) or 15 mA / g (corresponding to C / 8). The cells were discharged by the cc (constant current) method at a constant current of 5 mA / g (corresponding to C / 25) for the first cycle and 60 mA / g (corresponding to C / 2) for subsequent cycles until a voltage limit of 2.5 V was reached. The specific current chosen was based on the weight of the coating on the positive electrode. The electrodes were selected to establish a cathode-to-anode capacity ratio of 1:1.2.

[0240] The results of electrochemical testing of full cells of lithium ion batteries containing silicon-containing materials from Inventive Examples 1-5 and Comparative Examples 1 and 2 are shown in Table 3.

[0241] [Table 3]

Claims

Claim 1: A process for producing a silicon-containing material by thermal decomposition of a silicon precursor in the presence of porous particles having a volume-weighted particle size distribution with a diameter percentile d50 of ≦20 μm, wherein silicon is deposited within the pores and on the surface of the porous particles; A process wherein the pyrolysis of the silicon precursor occurs in a reaction zone of a gas traverse reactor, and the porous particles are circulated within the reaction zone during pyrolysis by a close clearance agitator within a heated region. However, in the following formula 1, [Equation 1] For half of all values ​​of h, if the proximal clearance W(h) in the reaction zone is W(h) > 0.9, the stirring mechanism is proximal clearance (where u Ｒ (h) = outer periphery of the stirring mechanism in the cross section at height coordinate h, u Ｂ (h) = inner circumference of the reactor at the cross section with height coordinate h).

2. 10. The process of claim 1, wherein the reaction zone of the reactor is rotationally symmetric. However, the following formula 1 [Equation 2] (In the formula, W(h) = the close clearance of the stirring mechanism in a rotationally symmetric reactor, defined as the ratio of the circumferences of two planar cross sections perpendicular to the axis of rotation of the two surfaces of rotation (h represents the height coordinate); u Ｒ (h) = the circumference of the circular inner cross section, calculated according to Equation 2 below, at any point h on the plane of revolution perpendicular to the axis of revolution passing through the planar cross section; u Ｒ (h) = 2πr Ｒ (h) (2) r Ｒ (h) = distance from the axis of rotation to the outer contour of the stirring mechanism (the stirring mechanism includes all components attached to it); u Ｂ (h) = the circumference of the circular outer surface of rotation calculated according to Equation 3 below at each arbitrary point h of the surface of rotation perpendicular to the axis of rotation through the planar cross section (the surface of rotation is formed by the rotation of the inner contour of the reactor about the axis of rotation), u Ｂ (h) = 2πr Ｂ (h) (3) r Ｂ (h) = distance of the inner contour of the reactor to the axis of rotation In (2), the stirring mechanism is close clearance if the close clearance W(h) in the reaction zone must be W(h)>0.9 for half of all values ​​of h.

3. During the deposition of the silicon precursor, the metered addition is carried out at a rate of 1 cm 3 of pore volume of the porous particles used per hour. ３ 3. The process according to claim 1 or 2, carried out at a rate of 0.1 to 2 g of Si per 1000 kJ / g.

4. During the deposition, the silicon precursor is introduced into the reaction zone at a rate of 1 m of the maximum cross-sectional flow area of ​​the reactor per hour. ２ 3. The process according to claim 1, wherein the Si is metered in at a rate of 1 to 700 kg per molten metal.

5. The process of any of claims 1 to 4, wherein the thermal decomposition of the silicon precursor occurs at 0.08 to 5 MPa.

6. The process according to any one of claims 1 to 5, wherein the pyrolysis of the silicon precursor is carried out at 280 to 900°C.

7. 7. The process of any one of claims 1 to 6, wherein the bed temperature in the reaction zone of the reactor equipped with a close clearance agitator is in the range of 100 to 1000°C.

8. The process of any one of claims 1 to 7, carried out in a cascade reactor system comprising multiple reactors.

9. The process of claim 7, comprising at least steps 1 to 3: Step 1: Reactor A is loaded with porous particles, the porous particles are pretreated, and the pretreated porous particles are then transferred to reactor B or a storage vessel, or the pretreated porous particles remain in reactor A. Step 2: Passing a gas flow consisting of at least one reactive component containing an inert gas and / or a silicon precursor and / or at least one silicon-free precursor through reactor B; The reactor is adjusted to a temperature at which thermal decomposition of the reactive components occurs on the surface and within the pores of the porous particles. The particle bed in reactor B is circulated with a close clearance agitator so that the motion of the particle bed can be described by a Froude number in the range of 1 to 10. The gas phase is fed to reactor B and the particle bed in reactor B is circulated by close clearance stirring elements such that the ratio of circulation time to the mean residence time of the reactive components is less than one. After silicon is introduced into and onto the pores of the porous particles, the silicon-containing material is transferred to reactor C or a reservoir for intermediate storage, or the silicon-containing material remains in reactor B. Step 3: Post-treatment of silicon-containing particles for functionalization and / or coating of the surface of silicon-containing particles. Cooling the silicon-containing particles to a specified temperature and recovering the silicon-containing material from reactor C.

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