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

Abstract

A method for producing silicon-containing materials by thermal decomposition of a silicon precursor in the presence of porous particles, wherein silicon is deposited in the pores and on the surface of the porous particles, wherein the thermal decomposition of the silicon precursor occurs in a reaction zone of a reactor through which gas passes, and the particles are tumbled in the reaction zone during thermal decomposition by means of a close-gap stirrer operating in the heating zone, the stirring mechanism being a close-gap stirrer as defined in claim 1; silicon-containing materials obtainable by this method; and anode materials, anodes, and lithium-ion batteries comprising silicon-containing materials.

Description

Technical Field

[0001] A method for producing silicon-containing materials by thermal decomposition of silicon precursors in the presence of porous particles, wherein silicon is deposited in the pores and on the surface of the porous particles in a gas-traversed reactor having a close-clearance stirrer; silicon-containing materials obtainable by this method; and anode materials, anodes, and lithium-ion batteries including silicon-containing materials. Background Technology

[0002] As a storage medium for electricity, lithium-ion batteries are currently the most practical electrochemical energy storage devices with the highest energy density. Lithium-ion batteries are primarily used in portable electronic devices, tools, and also in electrically powered vehicles such as bicycles, scooters, or automobiles. Currently, graphite carbon is the most widely used active material for the negative electrode (“anode”) of these batteries. However, a drawback is the relatively low electrochemical capacity of this type of graphite carbon, theoretically a maximum of 372 mAh per gram of graphite, and therefore only about one-tenth of the theoretically achievable electrochemical capacity using lithium metal. Alternative active materials with added silicon for the anode are described, for example, in EP 1730800 B1, US 10,559,812 B2, US 10,819,400 B2, or EP 3335262 B1. Lithium forms a binary electrochemically active alloy with silicon, which enables very high electrochemically achievable lithium content of up to 3579 mAh / g silicon [M. Obrovac, VLChevrier Chem. Rev. 2014, 114, 11444].

[0003] The insertion and extraction of lithium ions into and out of silicon is associated with the drawback of a very rapid volume change, which can reach up to 300% in the case of full insertion. This volume change subjectes the silicon-containing active material to severe mechanical stress, potentially leading to eventual breakage of the active material. In the active material and electrode structure, this process (also known as electrochemical polishing) results in the loss of electrical contacts, and thus a continuous and irreversible loss of electrode capacity.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the electrolyte components to continuously form a passivation protective layer (solid electrolyte interphase; SEI). The formed component is no longer electrochemically active. The lithium bound therein is no longer usable in the system, thus leading to a significant and continuous loss of battery capacity. Due to the extreme volume changes of silicon during battery charging / discharging, the SEI decomposes regularly, meaning that additional unoccupied surfaces of the silicon-containing active material are exposed and then undergo further SEI formation. As the amount of mobile lithium in the entire battery (corresponding to usable capacity) is limited by the cathode material, it is gradually consumed, and after only a few cycles, the battery capacity declines to an unacceptable level from a performance point of view.

[0005] The reduction in capacity during multiple charge and discharge cycles is also known as decay or continuous capacity loss, and it is usually irreversible.

[0006] A series of silicon-carbon composite particles have been described as active materials for anodes in lithium-ion batteries, wherein silicon is incorporated into porous carbon particles from gaseous or liquid precursors.

[0007] In multiphase reaction systems, good contact between porous solids and fluid precursors is common knowledge [F. Schüth Chem. Unserer Zeit 2006, 40, 92-103].

[0008] For example, US10,147,950B2 describes the deposition of silicon from silane SiH4 in porous carbon by CVD (chemical vapor deposition) or PE-CVD (plasma-enhanced chemical vapor deposition) at elevated temperatures of 300°C to 900°C, preferably with particle agitation, in a rotary tube furnace or comparable furnace type. This method uses a mixture of 2 mol% silane and nitrogen as an inert gas. Due to the low concentration of the silicon precursor in the gas mixture, the reaction time is very long. Furthermore, the ratio of particle bed to reactor volume in a rotary tube furnace is generally very unfavorable, as otherwise there would be a considerable amount of particle emission through the gas stream.

[0009] Another approach to performing gas-solid reactions, and therefore operations that incorporate silicon into porous starting materials, includes gas-fluidized beds. In a gas-fluidized bed, the solid particle bed is loosened and carried extensively by an upward airflow, causing the solid bed as a whole to exhibit liquid behavior [VDI- 11th edition, section L3.2Flowforms and pressure loss in fluidized beds, pp.1371-1382, Springer Verlag, Berlin Heidelberg, 2013].

[0010] Gas-fluidized beds are also commonly referred to as fluidized beds. The process used to generate a fluidized bed is also called fluidization or fluidization.

[0011] In a gas-fluidized bed, solid particles are very well dispersed. This results in a very large contact area between the solid and the gas, ideal for energy and mass transfer processes. Gas-fluidized beds are generally characterized by excellent mass and heat transfer events and a uniform temperature distribution. The quality of mass and heat transfer methods is particularly critical to the homogeneity of the products obtained from reactions in a fluidized bed and can be related to the homogeneity of the fluidization state. Therefore, the formation of a homogeneous fluidized bed or homogeneous fluidization state is essential for the use of fluidized bed methods to produce products with uniform product properties.

[0012] Fluidization properties can be categorized as a function of particle size and particle solids density. For example, particle size d 50 <20μm and the density difference between the particles and the gas >1000kg / m³ 3 The particles fall into Geldart C type (cohesive) [D. Geldart, Types of gas fluidization, Powder Technology 7 (1973) 258]. Geldart C type particles are characterized by their inability to readily transition to a fluidized state. Due to their low particle size, the effect of interparticle attraction is on the same order of magnitude or greater than the forces acting on the primary particles due to the gas flow. Accordingly, effects such as fluidized bed elevation and / or channel formation as a whole occur. If channels are formed, tubes are formed in the particle bed rather than the fluidized bed, and the fluidizing gas preferentially flows through these tubes, while the main part of the bed receives no crossflow at all. Therefore, fluidization cannot achieve uniformity. If the gas velocity increases significantly above the minimum fluidization velocity of the primary particles in the bed, agglomerates (agglomerates) composed of individual particles form over time, which can be fully or partially fluidized. The typical behavior is the formation of layers of agglomerates of different sizes. In the bottommost layer, directly above the inflow bottom, these agglomerates are very large and exhibit very little or no movement. In the upper layers, smaller fluidized agglomerates exist. In the topmost layer, the smallest agglomerates exist and are partially entrained by the airflow, posing a technical problem in the process. This fluidization behavior of the particle bed is also 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 bubbling fluidization” (ABF) [Shabanian, J.; Jafari, R.; Chaouki, J., Fluidization of Ultrafine Powders, IRECHE., vol.4, N.1, 16-50].

[0013] It will be clear to those skilled in the art that, due to the inhomogeneity within the fluidized bed and the associated inhomogeneous mass and heat transfer conditions, a bed fluidized by ABF is not suitable for producing substances with homogeneous properties.

[0014] For this reason, GB 2580110 B2, for example, uses 1.25% by volume silane in a fluidized bed for particles with a size greater than 50 μm (D 50 The particles are fluidized. However, after the reaction is complete, the resulting particles must be ground to the desired target size of <20 μm. In this fluidized bed, fluidization of particles <20 μm will lead to severe agglomeration and uneven penetration of porous carbon particles.

[0015] There are known methods of assisted fluidization to transform particles <20 μm in agglomerate form into a predominantly homogeneous fluidized bed. For example, US 7,658,340 B2 describes how to influence the size of agglomerates (Geldart C type) of SiO2 nanoparticles in a fluidized bed by inputting additional force components (such as vibrational force, magnetic force, acoustic force, rotational / centrifugal force or combinations thereof) in addition to the force applied by the fluidizing gas, thus forming a predominantly homogeneous fluidized bed.

[0016] Cadoret et al. [Cadoret, L.; Reuge, N.; Pannala, S.; Syalmal, 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] described the deposition of silicon from silane SiH4 onto non-porous, submicron-sized titanium dioxide particles in a vibrating fluidized bed reactor. The vibration input allowed agglomerates in the fluidized bed to be confined to a size range from 300 to 600 μm.

[0017] Fluidized bed methods without auxiliary fluidization techniques are unsuitable for bonding / depositing silicon in porous matrix particles because particles <20 μm in size cannot be fluidized uniformly. Due to the non-uniform fluidized bed, it is impossible to produce a uniform product.

[0018] Fluidized bed processes with auxiliary fluidization mechanisms are disadvantageous for bonding / depositing silicon in porous matrix particles because fluidizing particles smaller than 20 μm requires significant technical complexity. This additional complexity is associated with substantial capital investment and maintenance costs.

[0019] Another drawback of combining silicon with fluidized bed methods and assisted fluidization is that the properties of these primary particles (such as particle density or surface consistency) change during the process. The impact of these changes on agglomeration formation is unknown; for the given process, this formation should be known. It is impossible to ensure uniform process conditions throughout the entire process operation time.

[0020] Another drawback of fluidized bed technology is that the fluidization of agglomerates composed of primary porous particles requires airflow, which leads to the discharge of primary particles and / or relatively small agglomerates.

[0021] A fundamental drawback of fluidized bed technology is that the fluidizing gas flow used to form a homogeneous fluidized bed depends on the size of the particles / agglomerates within the fluidized bed. Therefore, the metered amount of reactant gas and the contact time between the reactant gas and the porous particles depend on the fluidization and mixing state of the particle bed. In fluidized bed processes, for example, the contact time between the gaseous reactive component and the particle bed can only be increased by reducing the gas velocity. However, gas velocity is a critical variable for ensuring fluidization and mixing conditions.

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

[0023] US2020 / 0240013 A1 describes the deposition of silicon from silicon-containing gas into particles having an average particle size in the low millimeter range in a stirred bed reactor. Due to the particle size, it is assumed that the bed material used has very high fluidity. In the described apparatus, the exchange between gas and solid is carried out using a central stirring screw through which the reactant gas is simultaneously supplied, passing through openings in the stirred bed. This patent application particularly relates to the advantage of handling particles in the millimeter range, as a large fluidizing gas flow is necessary to bring the particles into a fluidized state for particles of this size.

[0024] However, the stirrer used in US2020 / 0240013 A1 is not suitable for turning over sticky particles <20 μm.

[0025] It is known from technical literature that particles in a stirred bed can be tumbled using various different stirring elements [M. Müller, Feststoffmischen [Solids Mixing], Chemie Ingenieur Technik 2007, 79, 7]. For example, using a close-gap helical stirrer, particles are laterally and upwardly conveyed in the reactor, creating a tumbling flow, where the relative motion of the particles is due to sliding material. This prevents particles from adhering to the reactor wall.

[0026] The parameter describing the motion state of a particle bed is the Froude number (Fr), which represents the ratio of centrifugal force to gravity in a rotating system.

[0027]

[0028] In this equation, r c It is the characteristic radius associated with the system. For systems with rotary mixing tools, r c Corresponding to the outer radius of the stirring element. In the case of a system with a rotating drum, r c This is the inner radius of the container. The tumbling frequency ω = 2πn depends on the rotational speed n of the rotating system. The effect of gravity is considered through gravitational acceleration g. At low Froude numbers, the gravitational component dominates, resulting in low radial material transport. Tumbling of the particle bed is insufficient. On the other hand, at high Froude numbers, the centrifugal component dominates, causing excessive material movement against the container wall. Here, tumbling of the particle bed is also insufficient.

[0029] The parameter used to describe the contact time between the gas phase and the stirred particle bed is the residence time of the gaseous reactive component in the reactor. Average residence time t V It can be used as a quotient of reactor volume and metered gas phase volumetric flow rate. To calculate:

[0030]

[0031] Another important measure for evaluating homogeneous reaction conditions in a stirred bed reactor is the particle bed turning time t. u Residence time t with silicon precursor v The ratio t u / t v Particle bed turning time t u Calculated as reactor volume V R The quotient of the volumetric flow rate of the flipped particles

[0032]

[0033] The volumetric flow rate of particles tumbled by the stirring element. Defined as the volume of particles displaced tangentially by the stirring element per unit time, and generally described by the following formula:

[0034]

[0035] The volumetric flow rate of the tumbling particles is the sum of the rotational speed *n* and the volume of all tangential displacements of the individual stirring units *i* of the stirring element. The geometry of each individual stirring unit is defined by the distance *r* from the inner edge of the stirring element to the axis of rotation. R,内边缘,i The distance r from the outer edge of the stirring element to the rotating shaft R,外边缘,i and the upper contour h of the corresponding stirring unit o.i (r) and lower contour h u.i Let's consider (r).

[0036] When the ratio t u / t v When the value is <1, the particle tumbling process is faster than the gas flow through the bed, resulting in a uniform distribution between the gas and particles. At a ratio t... u / t v When the value is greater than 1, the gas flows through the stirred bed faster than the bed itself rotates. Therefore, regions with different deposition conditions are formed in the stirred bed, resulting in an uneven distribution of products in the bed.

[0037] Against this backdrop, the object of the present invention is to provide a method for producing silicon-containing materials, preferably having a high storage capacity for lithium ions, which, when used as an active material in the anode of a lithium-ion battery, enables high cycle stability starting from porous particles and silicon precursors. The method is technically simple to implement and does not include the disadvantages of the aforementioned methods that affect the prior art, particularly regarding particle discharge, reaction time, and the required basic structure.

[0038] A particular aim is to minimize the dead space in the bed that is not agitated by the agitator. Therefore, the material in the heated section of the shell remains in motion with maximum efficiency, and energy is transferred from the walls to the bed. Furthermore, this prevents particle adhesion to the walls. Summary of the Invention

[0039] This invention provides a method 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.

[0040] The thermal decomposition of the silicon precursor occurs in the reaction zone of the reactor through which the gas passes, and the particles are tumbled in the reaction zone by a stirrer with close clearance in the heated area during the thermal decomposition process.

[0041] In Equation 1, if the stirring mechanism has a tight gap...

[0042]

[0043] Then for half of all values ​​of h, the close interstitial spaces in the reaction zone W(h) are W(h) > 0.9, where u R (h) = the outer perimeter of the stirring mechanism in the cross-section at height coordinate h, and u B (h) = the inner circumference of the reactor.

[0044] It has been unexpectedly discovered that by using a tightly spaced stirring tool in this invention, very small particles (more particularly <20 μm particles) are circulated in the reactor, and the gas flow of the reactive components is metered, such that the contact time between the gas phase and the solid has the following duration: the process of introducing silicon into the porous particles occurs uniformly with a high conversion rate of silicon precursors, while the discharge of particles from the gas flow from the reactor is minimized.

[0045] Compared to fluidized bed reactors with auxiliary fluidization devices, gas-through stirred reactors (SBRs) have a simpler construction because the amount of gas requiring compression and preheating is lower in SBRs, and this gas is not used for fluidization. This translates to lower costs for associated components. In the case of SBRs, sophisticated control and regulation techniques are not required to operate the auxiliary fluidization devices. Compared to FBRs, SBRs have a smaller construction size because the stirred bed occupies a smaller volume for a given mass. Specific capital investment costs are also lower.

[0046] Compared with GB 2580110 B2, the method of the present invention does not require any further operational steps.

[0047] Compared to fluidized bed reactors, particle tumbling is independent of the gas phase supply. Higher residence times are possible, leading to higher conversion rates of these reactive components.

[0048] In the method of this invention, the stirring only causes the particles to tumble. The particles are not rolled up by the stirrer.

[0049] Preferably, the size of the gas flow is determined such that the vortex of the gas flow through the particles is minimized in the method of the present invention, and therefore the discharge of particles from the reactor is also minimized. Simultaneously, the size of the gas flow is preferably such that the conversion rate of the reactive component used is at its maximum.

[0050] Homogeneous deposition conditions are possible because of the appropriate selection of the rotary stirrer speed parameter, expressed in terms of the dimensionless Froude number, and because of the appropriate metering rate.

[0051] Compared to US2020 / 0240013 A1, the method of the present invention is improved by using a close-gap stirrer.

[0052] The rotary stirrer speed is preferably set such that the tumbling time of the particle bed is less than the residence time of the fluid reactive components, especially the porous particles. The result is sufficiently effective and extensive mixing of the fluid and solid phases, leading to uniform treatment of all particles in the solid phase.

[0053] A further economic advantage of this method compared to methods not described in this invention is the higher silicon yield. Furthermore, the deposition of silicon on and particularly within these porous particles is exceptionally uniform, resulting in high stability of the obtained silicon-containing material when used as an active material in the anode of a lithium-ion battery, while exhibiting low volume change upon flipping.

[0054] In a rotationally symmetric reactor, the tight clearance W(h) of the stirring mechanism is defined as the quotient of the perimeters of two plane sections perpendicular to the rotation axes of the two rotational planes, where h is the height coordinate. The inner rotational plane is formed by one complete rotation of the stirring mechanism and is characterized by the distance r from the rotation axis to the outer contour of the stirring mechanism. R (h). The stirring mechanism includes all components attached to it. The planar cross-section at any point h on the plane of rotation perpendicular to the axis of rotation forms a circular cross-section. The perimeter of the inner cross-section is calculated as...

[0055] u R (h)=2πr R (h)

[0056] The outer surface of rotation is formed by rotating the inner contour of the reactor around the axis of rotation. It is measured by a distance r. B (h) describes the reactor's inner contour, including all components attached to it. The perimeter of any cross-section of the outer plane of rotation perpendicular to the axis of rotation is calculated as:

[0057] u B (h)=2πr B (h)

[0058] Using the perimeter, the tight clearance is defined as follows:

[0059]

[0060] Generally, a reactor may include one or more stirring mechanisms. The profile of each individual stirring mechanism forms a plane of rotation by complete rotation. These planes of rotation may exist individually. Preferably, they may be superimposed on each other. Dividing the individual planes of rotation or the superimposed planes of rotation at arbitrary points perpendicular to or perpendicular to the axis of rotation produces a diagram or graph in which the perimeter can be determined. In the case of generating multiple figures, the total perimeter is determined by summing the individual perimeters.

[0061] Generally, the reactor can consist of one or more reactor components, which are preferably each rotationally symmetric and connected to each other. A general view of the overall enclosure of all reactor walls is provided. Cutting this view at any point perpendicular to the axis of rotation of the agitator mechanism allows determination of the perimeter of the resulting diagram. The tight clearance W(h) is calculated in a manner similar to that used for rotationally symmetric reactors.

[0062] The tightness can vary with h. If for at least half of all values ​​of h, the tightness W(h) in the reaction zone is W(h) > 0.9; the parameter defined for this is W(h). 50％ In a preferred embodiment, W(h) 50％ W(h) > 0.95. In a particularly preferred embodiment, W(h) > 0.95. 50％ W(h) > 0.97. In a particularly preferred embodiment, W(h) > 0.97. 50％ W(h) > 0.99. The reaction zone is the area in the reactor where the stirred particle bed comes into contact with the reactive components and the reactive components decompose. For the specific case of this process, W(h) > 0.99. 50％ Values ​​greater than 1 are also possible.

[0063] This method is preferably carried out in a cascaded reactor system comprising multiple reactors. Implementing this in a cascaded reactor offers advantages over implementing it in a single reactor: it reduces the long cooling and heating phases of the reactor. This provides advantages in terms of time and energy compared to a single reactor, and results in reduced stress on the reactor materials. Furthermore, cascaded reactor systems offer the advantage that individual reactors can be precisely designed for their intended purpose. Cascaded reactor systems are also easier to scale, allowing different numbers of reactors to be combined to form a single phase.

[0064] In a preferred embodiment, the method includes at least stages 1 to 3:

[0065] Phase 1: Fill reactor A with porous particles and pretreated particles, then transfer the pretreated particles to reactor B or a storage container, or retain the material in reactor A.

[0066] Stage 2: Pass a gas stream consisting of an inert gas and / or at least one reactive component containing a silicon precursor and / or at least one silicon-free precursor through reactor B.

[0067] The reactor is adjusted to a temperature at which the thermal decomposition of the reactive component occurs on the surface and within the pores of the porous particles. The particle bed in reactor B is agitated using a tight-gap stirrer, such that the movement of the particle bed can be described by a Froude number in the range of 1 to 10. A gas phase is supplied to reactor B while the particle bed in reactor B is agitated by the tight-gap stirring element, such that the ratio of agitation time to the average residence time of the reactive component is less than 1. The reaction can be carried out at pressures below and above atmospheric pressure. After silicon has been introduced into and onto the pores of the porous particles, the silicon-containing material is transferred to reactor C or to a storage container for temporary storage, or the material is retained in reactor B.

[0068] Stage 3: Post-processing of silicon-containing particles for functionalization and / or coating of the surface of the silicon-containing particles. The particles are cooled to a defined temperature and the silicon-containing material is extracted from reactor C, and preferably transferred directly to a storage container or directly dispensed into a suitable container.

[0069] In stage 1, reactor A, which is heatable and / or vacuum-resistant and / or pressure-resistant, is filled with porous particles. This filling can be done manually or automatically.

[0070] The filling of reactor A with porous particles can be carried out, for example, in an inert gas atmosphere or preferably in ambient air. The inert gas used may include, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide or mixtures thereof, as a forming gas. Argon or more specifically nitrogen is preferred.

[0071] Automatic filling can be accomplished, for example, using a metering screw, star wheel, vibratory trough, plate metering system, belt metering system, vacuum metering system, negative weighing outlet, or another metering system (from, for example, silos, bag chutes, or another container system).

[0072] The purpose of pretreating these particles in reactor A in stage 1 is to remove air / oxygen, water, or dispersants (such as surfactants or alcohols) and impurities from them. This can be achieved by inertization with an inert gas, raising the temperature to up to 1000°C, reducing the pressure to as low as 0.01 mbar, or by a combination of individual operating steps. The inert gas used may include, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide or mixtures thereof, as a forming gas. Argon or more specifically nitrogen is preferred.

[0073] The purpose of the pretreatment in Stage 1 can also be to alter the chemical surface properties of the porous particles with additional substances. These substances can be added before or after drying, and further heating steps can be performed before transferring the material to Reactor B. These substances can be introduced into the reactor in gaseous, solid, liquid, or solution form, including mixtures, emulsions, suspensions, aerosols, or foams. The substances involved 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.

[0074] For example, the transfer of porous particles to another reactor or container can be accomplished by means of drop pipes, continuous conveyors, flow conveyors / suction or pressure conveyor units (e.g., vacuum conveyors, conveyor blowers); mechanical conveyors (e.g., roller conveyors with drives, screw conveyors, circular conveyors, tipping conveyors, bucket units, star wheel locks, chain conveyors, scraper conveyors, belt conveyors, oscillating conveyors); gravity conveyors (e.g., chutes, roller beds, ball beds, track beds), and also by means of discontinuous conveyors, floor-based and trackless (e.g.). Automated vehicles, manual forklifts, electric forklifts), driveless transport systems (DTS), air cushion vehicles, handcarts, electric trolleys, motorized vehicles (tractors, trucks, forklift stackers), transfer trays, transfer / lift trays, rack entry equipment (with / without converters, capable of following curved paths); floor-based, track-integrated (e.g., plant railways, rail vehicles); floorless (e.g., trolley tracks), cranes (e.g., bridge cranes, gantry cranes, boom cranes, tower cranes), electric overhead rails, small boat transport systems; fixed (e.g., elevators, maintenance elevators and cherry pickers, tiered conveyors).

[0075] In stage 2, the pretreated material is preferably brought to a temperature of 100°C to 1000°C, more preferably 250°C to 600°C, and especially preferably 300°C to 500°C in reactor B.

[0076] During temperature changes, when a temperature is reached, or during passage through a temperature distribution, reactor B is alternately or simultaneously passed through by a gas consisting of at least one inert gas and / or at least one reactive component consisting of at least one silicon precursor and / or at least one silicon-free precursor. Continuous different gas compositions are possible, or variations within a specified composition are possible during stage 2. The metering rate of the gas phase containing the reactive component with at least one silicon precursor is defined relative to the absolute pore volume [cm³] of all porous particles introduced into reactor B. 3The mass [g] of silicon supplied per hour, including in the silicon precursor. During the deposition of the silicon precursor, a Si / cm³ density of 0.1 g to 2 g, more preferably 0.5 g to 1.5 g of porous particles per hour is preferred. 3 The rate at which the pore volume is metered is added.

[0077] An alternative is an area-based metering rate of the gas phase containing the reactive component with at least one silicon precursor, such as relative to the maximum flow cross-sectional area [m] in the reaction zone. 2 The hourly supply of silicon, including the silicon precursor, in kg. The cross-section of the empty reactor is measured. The reaction zone is the area in the reactor where the stirred particle bed comes into contact with the reactive components and the precursor decomposes.

[0078] The metering rate of the supplied precursor is calculated such that the ratio of the particle bed tumble time to the average residence time of the reactive component in the reactor is always less than 1.

[0079] The gas phase can be metered continuously or in pulses. The metering rate can vary during the reaction's operating time.

[0080] In this rotationally symmetric reactor, the deposition process is preferably carried out at a rate of [per hour per m]. 2 The silicon precursor is added at a rate of 1 kg to 700 kg, more preferably 10 kg to 300 kg, of Si with an external rotation area of ​​1 kg to 700 kg.

[0081] Throughout the thermal decomposition process, reactor B is preferably passed through a certain amount of silicon-containing reactive components, such that the amount of silicon deposited is sufficient for the target capacity of the silicon-containing material produced, relative to the amount of porous particles weighed.

[0082] In stage 2, the heating of reactor B can be carried out, for example, at a constant heating rate or at several different heating rates. The heating rate can be adjusted by the technician in each individual case according to the design of the method, taking into account, for example, the size of the reactor, the amount of porous particles in the reactor, the stirring technique, or the planned reaction time.

[0083] In stage 2, the heating of reactor B 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.

[0084] The temperature at which the silicon precursor begins to decompose can depend on, for example, the porous particles used, one or more silicon precursors used, and other boundary conditions of 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.

[0085] During the decomposition of the silicon precursor in stage 2, the temperature can be kept constant or varied. The aim is to ensure that most of the silicon precursor is completely converted during the contact time between the gas and the stirred bed, thereby producing a usable silicon-containing material.

[0086] In stages 2 and 3, and specifically in the reaction zone of the reactor equipped with the close-gap stirrer, the bed temperature is preferably in the range of 100°C to 1000°C, more preferably from 250°C to 600°C, and most preferably from 300°C to 500°C. For example, the target temperature for SiH4 is preferably 300°C to 500°C, more preferably 320°C to 450°C, and very preferably 320°C to 430°C. The target temperature for HSiCl3 is preferably between 380°C and 1000°C, more preferably in the range of 420°C to 600°C. The target temperature for H2SiCl2 is preferably 350°C to 800°C, more preferably 380°C to 500°C.

[0087] When hydrocarbons are used in stage 3 and / or as other reactive components other than silicon deposition during stage 2, the target temperature at which hydrocarbon decomposition begins and carbon deposition occurs within the pores and on the surface of the porous particles is adopted. In this embodiment, the target temperature is preferably selected in the range of 250°C to 1000°C, more preferably from 350°C to 850°C, and most preferably from 400°C to 650°C.

[0088] In stage 2, the bed of porous particles is turned over, preferably continuously. Turning is accomplished by one or more stirring elements or by the rotational motion of the reactor itself (e.g., a strong mixer from Maschinenfabrik Gustav Eirich) or a combination thereof. The moving state of the moving bed is characterized by a Froude number of 1 to 10. The Froude number is preferably 1 to 6, more preferably 1 to 4.

[0089] The thermal decomposition of the silicon precursor in the presence of porous particles preferably occurs at a pressure of 0.05 MPa to 5 MPa, more preferably at a pressure of 0.08 MPa to 0.7 MPa.

[0090] The gas phase from stage 2 consists of an inert gas and / or at least one reactive component containing a silicon precursor and / or at least one silicon-free precursor in a possibly varied composition. One or more silicon precursors may be introduced into reactor B, typically in a mixed form or separately, either as a mixture with the inert gas component or as a pure substance. Based on the partial pressure of the inert gas component as a proportion of the total pressure of the reactive component under standard conditions (according to DIN 1343), the reactive component preferably contains 0% to 99%, more preferably up to 50%, particularly preferably up to 30%, and very particularly preferably up to 5% of the inert gas component.

[0091] The silicon-containing reactive component includes at least one precursor that can react under selected conditions (e.g., heat treatment) to produce silicon. The precursor is preferably selected from the group containing silicon-hydrogen compounds, such as silane SiH4, silane Si2H6, and more advanced straight-chain, branched, or cyclic homologues, neopentyl silane Si5H6. 12 Cyclohexasilane Si6H 12 Chlorosilanes, 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 oligomeric and polysilanes, methylchlorosilanes, such as, for example, trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylsilane MeH3Si, dichlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or mixtures of other described silicon compounds.

[0092] In one specific embodiment of the method, a silane or mixture of silanes, such as silane SiH4, trichlorosilane HSiCl3, dichlorosilane H2SiCl2, monochlorosilane H3SiCl, and tetrachlorosilane SiCl4, wherein each component may be present from 0 to 99.9 wt%, is produced by a suitable method only before being arranged in the reactor. Generally, these methods begin with trichlorosilane HSiCl3, which is rearranged over a suitable catalyst (e.g., a catalyst). AmberLyst TM A21DRY) to form other components of the mixture. The composition of the resulting mixture is primarily determined by post-treatment of the mixture after one or more rearrangement stages at one or more different temperatures.

[0093] The particularly preferred reactive component is selected from the group consisting of: silanes SiH4, oligomeric or polymeric silanes, especially those of the general formula Si. n H n+2 Straight-chain silanes (where n can include integers in the range of 2 to 10), and the general formula -[SiH2]. n - Cyclic silanes (where n can include integers in the range of 3 to 10), trichlorosilane HSiCl3, dichlorosilane H2SiCl2, and chlorosilane H3SiCl, which can be used alone or as a mixture; it is very preferred to use SiH4, HSiCl3, and H2SiCl2 alone or in a mixture.

[0094] During the metering of the reactive component into the reactor, the reactive component may be present, for example, in a gaseous, liquid, or sublimated solid form. The reactive component is preferably, for example, gaseous, liquid, solid, sublimable, or optionally a composition of substances in different aggregate states. In a variation of this method, the reactive component is introduced directly into a porous particle bed in the reactor, for example, from below or from the side, or using a special stirrer.

[0095] Furthermore, the reactive components in stages 2 and / or 3 may also include other reactive components, such as dopants based on compounds containing boron, nitrogen, phosphorus, arsenic, germanium, iron, or nickel. The dopants are preferably selected from ammonia (NH3), diborane (B2H6), phosphine (PH3), germanane (GeH4), arsine (AsH3), iron pentacarbonyl (Fe(CO)4), and nickel tetracarbonyl (Ni(CO)4).

[0096] Other reactive components that may be present in this gas phase include hydrogen or other hydrocarbons selected from the group consisting of 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, and cycloheptane; unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethylene, acetylene, propylene, methylacetylene, butene, butyne (1-butyne, 2-butyne), isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, and cyclooctadiene; cyclic unsaturated hydrocarbons, such as cyclopropylene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene, or norbornene; and aromatic hydrocarbons such as benzene, toluene, p-, m-, and o-xylene. Ethylene (vinylbenzene), ethylbenzene, diphenylmethane or naphthalene, other aromatic hydrocarbons such as phenol, o-, m-, p-cresol, umbelliferone, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornene, borneol, isobornene, borneolane, camphor, limonene, terpinene, pinene, pinane, octane, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, dihydroxymethylfuran, and mixed fractions including a variety of such compounds, such as those from natural gas condensate, crude oil distillate or coke oven condensate, mixed fractions from product streams from fluidized catalytic cracking (FCC), steam cracking or Fischer-Tropsch synthesis units, or very commonly, hydrocarbon streams from wood processing, natural gas, crude oil and coal.

[0097] In a particularly preferred embodiment, in the first reaction cycle of stage 2, a reactive component containing at least one silicon precursor is treated, and in the second reaction cycle of stage 2, a reactive component containing at least one hydrocarbon and preferably without silicon is treated. By repeating these two steps, for example, a silicon-containing material without an outward-facing free silicon surface can be obtained.

[0098] Optionally, in the upstream reaction cycle of stage 2, additional hydrocarbon-containing, silicon-free reactive components are used. In this way, for example, a silicon-containing material can be obtained, which has a carbon layer between the porous particles and the deposited silicon and optionally carries an additional outer carbon layer, meaning that there is no outward-facing free silicon surface.

[0099] In a preferred embodiment, the temperature, pressure, pressure change or differential pressure measurements, and gas flow measurements in reactor B are determined using common instruments and measurement methods. After routine calibration, measurements using different instruments produce the same results.

[0100] The reaction process in Stage 2 is preferably analyzed and monitored to identify the end of the reaction and to minimize reactor occupancy time. Methods for observing the reaction process include, for example, temperature measurements to determine exothermic or endothermic events by changing the ratio of solid to gaseous reactor contents components, temperature measurements to determine the reaction process, and other techniques capable of observing changes in the composition of the gas space during the reaction. In a preferred variant of this method, the composition of the gas phase is determined by gas chromatography and / or a thermal conductivity detector and / or an infrared spectrometer and / or a Raman spectrometer and / or a mass spectrometer. In a preferred embodiment, a thermal conductivity detector is used to determine the hydrogen content, and / or a gas chromatograph or gas infrared spectrometer is used to determine the presence of any chlorosilanes. In another preferred variant of this method, an industrial component capable of separating hydrogen and silanes is used. This separation can be performed, for example, via filtration and / or membrane technology (solution-diffusion model and hydrodynamic model), adsorption, chemisorption, absorption, or molecular sieves (e.g., zeolite).

[0101] When hydrogen is the gaseous reaction product, the component can undergo a gas flipping process. In this case, the gas discharged in stage 2 is purged and / or the fraction of silicon-containing reactive components is increased, then returned to the reactor until the desired amount of silicon has been deposited. In another embodiment, the gas is separated into its components and disposed of in that manner.

[0102] In a further preferred variant of the method, the reactor B or the gas emission site is equipped with a technical means for removing the generated condensable or re-foaming byproducts. In a particularly preferred variant, silicon tetrachloride is condensed and removed separately from the silicon-containing material.

[0103] In a preferred embodiment of the method, the metering procedure in stage 2 is repeated multiple times, in which case the corresponding silicon precursors treated in stage 2 may be the same or different in each case, and a mixture of multiple silicon precursors is also possible. Similarly, the silicon-free reactive component treated in stage 2 may be the same or different in each case, or may consist of a mixture of different reactive components. After multiple repetitions of the individual metering procedure in stage 2, the implementation in reactor B ends with the transfer of silicon-containing particles to reactor C.

[0104] In stage 3 of this method, the silicon-containing particles in reactor C can be post-treated and / or deactivated and / or coated. This is preferably done by purging reactor C with oxygen, more particularly with a mixture of an inert gas and oxygen. In this way, it is possible, for example, to modify and / or functionalize and / or deactivate the surface of the silicon-containing material. For example, any reactive groups present on the surface of the silicon-containing material can be reacted. For this purpose, a mixture of nitrogen, oxygen, and optionally alcohol and / or water is preferably used, the mixture containing preferably up to 20 vol%, more preferably up to 10 vol%, and especially preferably up to 5 vol% oxygen, and also preferably up to 100 vol%, more preferably up to 10 vol%, and especially preferably up to 1 vol% water. This step is preferably carried out at a temperature of up to 250°C, more preferably up to 100°C, and especially preferably up to 50°C. The particle surface can also be deactivated with a gas mixture comprising an inert gas and an alcohol. Nitrogen and isopropanol are preferred here. However, methanol, ethanol, butanol, pentanol, or longer-chain and branched alcohols and glycols may also be used. The particles can also be deactivated by dispersion in a liquid solvent or solvent mixture. This mixture may include, for example, isopropanol or an aqueous solution. Deactivation of the particles in stage 3 may also optionally be accomplished by coating with a precursor containing C-, Al-, and / or B at a temperature of 200°C–800°C, optionally followed by treatment in an oxygen-containing atmosphere.

[0105] The aluminum-containing precursors used can be, for example, trimethylaluminum ((CH3)3Al), aluminum 2,2,6,6-tetramethyl-3,5-heptadecanoate (Al(OCC(CH3)3CHCOC(CH3)3)3), tris(dimethylamino)aluminum (Al(N(CH3)2)3), and aluminum triisopropoxide (C9H). 21 AlO3).

[0106] The boron-containing precursor used can be, for example, borane (BH3), triisopropyl borate ([(CH3)2)2), etc. 3)2[CHO]3B), triphenylborane ((C6H5)3B), and tri(pentafluorophenyl)borane (C6F5)3B. However, in stage 3, it is also possible to introduce a post-coating, for example, particles, using a solid electrolyte through the thermal decomposition of, for example, tert-butyllithium and trimethyl phosphate.

[0107] In stage 3 of this method, in principle, the silicon-containing material is extracted from reactor C, optionally retaining the inert gas atmosphere present in reactor C. This can be achieved, for example, by the following emission methods: pneumatically (by means of atmospheric pressure or below atmospheric pressure); mechanically (star wheel lock, plate discharge, discharge screw or stirring element in the reactor, belt discharge); or by gravimetric analysis (double-lobe or double-ball valve, optionally with vibration assistance).

[0108] Preferred silicon-free reactive components are one or more hydrocarbons. Carbon can typically be deposited within the pores and on the surface of porous particles through the thermal decomposition of hydrocarbons. Examples of hydrocarbons are aliphatic hydrocarbons having 1 to 10 carbon atoms, particularly 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 ethylene, acetylene, propylene, or butene, isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene; cyclic unsaturated hydrocarbons, such as cyclopropylene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene, or norbornene; aromatic hydrocarbons, such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane, or naphthalene; and other aromatic hydrocarbons. Hydrocarbons, such as phenol, o-, m-, p-cresol, umbelliferone, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornene, borneol, isoborneolene, borneolane, camphor, limonene, terpinene, pinene, pinene, nifedipine, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, dihydroxymethylfuran, and mixed fractions including a variety of such compounds, such as those from natural gas condensate, crude oil distillate or coke oven condensate, mixed fractions from product streams from fluidized catalytic cracking (FCC), steam cracking or Fischer-Tropsch synthesis units, or very commonly, hydrocarbon streams from wood processing, natural gas, crude oil and coal.

[0109] The reactive component is free of silicon, i.e., includes one or more hydrocarbons but not silicon precursors, and preferably contains no other components or one or more inert gases and / or one or more reactive components, such as hydrogen and / or one or more dopants. Dopants are, for example, compounds containing boron, nitrogen, phosphorus, arsenic, germanium, iron, or nickel. Dopants are preferably selected from ammonia (NH3), diborane (B2H6), phosphine (PH3), germanane (GeH4), arsine (AsH3), and nickel tetracarbonyl (Ni(CO)4).

[0110] As reactors used for the purposes of this specification, preferred reactor types are those selected from the group consisting of: digesters, tubular reactors, stirred bed reactors, stirred tank reactors, and autoclaves. Stirred reactors and autoclaves are particularly preferred, stirred reactors are more preferred, and stirred tank reactors are very preferred.

[0111] In one specific variation of this method, reactors A, B, and C are identical containers. It is not excluded that reactors A, B, and C are identical containers. In two specific embodiments of this method, the cascade reactor consists of only two interdependent reactors. In the first embodiment, stages 1 and 2 are carried out in the same reactor. In the second embodiment, stages 2 and 3 are carried out in one reactor. In both cases, the reactors can have different temperature zones; they can operate at atmospheric pressure or at pressures below or above atmospheric pressure.

[0112] The reactor can be adjustable, pressure-resistant, and vacuum-resistant: all combinations are possible. However, the reactor can also satisfy only the above characteristics.

[0113] Technical requirements for the reactor and optional special features of specific variants of the invention:

[0114] Reactor A:

[0115] - The reactor is at least adjustable.

[0116] - The reactor can be vacuum resistant.

[0117] - A system for preheating, drying, and inertizing porous particles.

[0118] - It can be connected to a system for specific addition / metering of porous particles (see Phase 1 for technical description).

[0119] - To dry and / or remove impurities from porous particles, a system capable of removing condensable or re-foaming substances can be connected.

[0120] - It can be connected to a system that allows porous particles to be transferred to reactor B (technical description in Phase 1).

[0121] Reactor B:

[0122] - The reactor is at least adjustable.

[0123] -Including the stirring mechanism according to the invention

[0124] - Systems for metering reaction gases

[0125] -A system for discharging reaction gases

[0126] - To simplify the process, a hydrogen separator can be connected (see Phase 2 for technical description).

[0127] - To remove condensable or re-foamable byproducts from gaseous reaction products, a container can be connected that allows for the removal of byproducts through condensation or re-foaming.

[0128] - It can be connected to a system capable of transferring materials to reactor C or storage container (see Phase 1 for technical description).

[0129] Reactor C:

[0130] - The reactor is at least adjustable.

[0131] - A system for removing condensable or re-foamable byproducts.

[0132] - It can be connected to a container, which allows byproducts to be removed by condensation or sublimation.

[0133] - Metering system for functionalized reactive gases

[0134] -A system for discharging reaction gases

[0135] - It can be connected to a system that allows materials to be transferred to storage containers (technical description in Phase 3).

[0136] Adjustable reactors are typically reactors that are operable to allow the internal temperature to be adjusted, for example, within a range of -40°C to 1000°C. Smaller temperature ranges are possible.

[0137] For the purposes of this specification, a cascade reactor system 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 vary. Those skilled in the art can adjust the number of reactors and their dimensions to maximize the overall output of the cascade reactor system. The reactors can be directly connected to each other or can be partially separated, in which case charging is performed via a movable storage container. It is also conceivable that two or more reactors B are connected to each other, with each reaction step taking place in a separate reactor B.

[0138] During operation, the porous particles and the resulting silicon-containing material can typically be in the form of a fixed bed or can be in a stirred state during mixing. Stirred mixing of the porous particles or the resulting silicon-containing material in reactors A, B, and C is preferred. However, during the thermal decomposition of the reactive components in stage 2, the particles must be actively mixed. This allows, for example, uniform contact of all the porous particles with the reactive components, or a uniform temperature distribution within the bed. The particles can be stirred, for example, by stirring the internal components of the reactor or by tumbling the reactor as a whole around a stirrer.

[0139] Another preferred configuration for reactors A, B, and C is a stationary reactor with a moving stirring element for overturning. The purpose of overturning is to ensure that the porous solids are contacted as uniformly as possible with the gaseous reactive components. Preferred geometries for this purpose are cylindrical reactors, conical reactors, spherical reactors, polyhedral reactors, rotationally symmetric reactors, or combinations thereof. The movement of the stirring element is preferably rotational. Other forms of movement are also suitable. The stirring element is preferably driven by a stirring shaft, and each stirring shaft may have one or more stirring elements. In reactors A, B, and C, multiple stirring shafts may exist, and each stirring shaft may have one or more stirring elements. The main reactor shaft is preferably horizontally or vertically aligned. In another preferred embodiment, these stirring shafts are mounted horizontally or vertically in the reactor in any orientation. For vertically operating reactors A, B, and C, preferred configurations are those in which, for example, the stirring element or multiple stirring elements mix the bed material through the rotational movement of the main stirring shaft. Another possibility is a configuration in which two or more stirring shafts extend in parallel. Another possibility is a configuration in which two or more stirring shafts operate non-parallel to each other. Another structural form of reactors A, B, or C used for vertical operation is characterized by the use of a screw conveyor. The screw conveyor preferably conveys the bed material at the center. An alternative design according to the invention is that the screw conveyor rotates at the edge of the reactor. Mixer (Hosokawa). Another preferred configuration is a planetary or helical mixing system. For horizontally operating reactors A, B, or C, preferred configurations are those in which, for example, stirring elements or multiple stirring elements mix the bed material via the rotational motion of a main stirring shaft. Various configurations are also possible, in which two or more stirring shafts extend in parallel. Further preferred configurations are those in which two or more stirring shafts operate non-parallel to each other. For vertically operating reactors A, B, or C, preferred stirring elements are those selected from the group including helical stirrers, spiral stirrers, anchor stirrers, or generally, those that axially or radially, or axially and radially convey the bed material and exhibit a tight gap according to the invention. The stirring elements. In the case of horizontally operating reactors A, B, or C, it is preferable to have multiple stirring elements on one shaft. The stirring elements of the horizontally operating reactors, according to the invention, are constructed in the form of, for example, plowshares, impellers, blade agitators, helical agitators, or generally axially and radially convey the bed material and exhibit the tight clearance according to the invention. The stirring element. This tight gap can be reduced by an additional scraper on the stirring element. In addition to the moving stirring element, reactors A, B, or C may also include rigid internal components, such as baffles.

[0140] For the construction of reactors A, B, or C used to implement the method of the present invention, any material is suitable in principle if it possesses the necessary mechanical strength and chemical resistance under the corresponding operating conditions. Regarding chemical resistance, reactors A, B, or C may be composed of corresponding solid materials as well as chemically unstoppable (pressure-bearing) materials having specific coatings or platings on the parts in contact with the medium.

[0141] According to the present invention, these materials are selected from the group consisting of:

[0142] - Metallic materials, corresponding to (according to DIN CEN ISO / TR 15608) steel material groups 1 to 11, nickel and nickel alloys groups 31 to 38, titanium and titanium alloys groups 51 to 54, zirconium and zirconium alloys groups 61 and 62, and cast iron groups 71 to 76.

[0143] - In single-material systems, ceramic materials include oxide ceramics, such as alumina, magnesium oxide, zirconium oxide, and titanium dioxide (capacitor materials), as well as multi-material systems, such as aluminum titanate (a mixture of alumina and titanium oxide), mullite (a mixture of alumina and silicon oxide), lead zirconate titanate (piezoelectric ceramics), or dispersion ceramics such as zirconium-reinforced alumina (ZTA - zirconium oxide-toughened alumina - Al2O3 / ZrO2).

[0144] - Non-oxide ceramics, such as carbides, examples of which are silicon carbide and boron carbide; nitrides, examples of which are silicon nitride, aluminum nitride, boron nitride and titanium nitride; borides and silicides; and mixtures thereof; and

[0145] - Composite materials belonging to the particulate composites group, such as sintered carbides, ceramic composites, concrete and polymer concrete; fiber composites, such as glass fiber reinforced glass, metal matrix composites (MMC), fiber cement, carbon fiber reinforced silicon carbide, self-reinforcing thermoplastics, steel-reinforced concrete, fiber-reinforced concrete; fiber plastic composites, such as carbon fiber reinforced plastics (CRP), glass fiber reinforced plastics (GRP) and aramid fiber reinforced plastics (ARP); fiber ceramic composites (ceramic matrix composites (CMC)); infiltrated composites, such as metal matrix composites (MMC); dispersion-strengthened aluminum alloys or dispersion-hardened nickel-chromium superalloys; layered composites, such as bimetallic composites, titanium-graphite composites, composite plates and composite pipes; glass fiber reinforced aluminum and sandwich structures.

[0146] And structural composite materials.

[0147] The porous particles used in the methods of the present invention are preferably selected from the group consisting of amorphous carbon in the form of hard carbon, soft carbon, mesophase carbon, microspheres, natural or synthetic graphite, single-walled and multilayer carbon nanotubes and graphene; oxides such as silicon dioxide, alumina, mixed silicon-alumina, 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, such as those described by the following component formulas:

[0148] Al a B b C c Mg d N e O f Si g Where 0 ≤ a, b, c, d, e, f, g ≤ 1, and at least two coefficients a to g > 0 and a*3 + b*3 + c*4 + d*2 + g*4 ≥ e*3 + f*2.

[0149] Ceramic materials can be, for example, binary, ternary, quaternary, pentagonal, or heptagonal compounds. Preferred ceramic materials are those having the following compositional formulas:

[0150] Non-stoichiometric boron nitride (BN) z Where z = 0.2 to 1,

[0151] Non-stoichiometric carbonitrides CN z Where z = 0.1 to 4 / 3,

[0152] Boron carbonitride B x CN z Where x = 0.1 to 20 and z = 0.1 to 20, and x*3 + 4 ≥ z*3,

[0153] Boron oxide (BN) z O r Where z = 0.1 to 1, and r = 0.1 to 1, where 3 ≥ r*2 + z*3.

[0154] Boron carbonitride oxide B x CN z O r Where x = 0.1 to 2, z = 0.1 to 1, and r = 0.1 to 1, and x*3 + 4 ≥ r*2 + z*3,

[0155] silicon carbide (Si) x CO z Where x = 0.1 to 2 and z = 0.1 to 2, and x*4 + 4 ≥ z*2,

[0156] Silicon carbonitride (Si) x CN z Where x = 0.1 to 3 and z = 0.1 to 4, where x*4+4≥z*3,

[0157] Boron carbonitride Si w B x CN z Where w = 0.1 to 3, x = 0.1 to 2, and z = 0.1 to 4, where w*4 + x*3 + 4 ≥ z*3.

[0158] borosilicate Si w B x CO z Where w = 0.10 to 3, x = 0.1 to 2 and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*2.

[0159] Silicon-boron-carbon-silicon trioxide (Si) v B w CN x O z Where 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 ≥ x*3 + z*2, and

[0160] Borosilicate carbon aluminum oxide Al u B v Si x CN w O z , where 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≥w*3+z*2.

[0161] Porous particles preferably have a density of 0.1 to 7 g / cm³ as determined by helium density determination. 3 And more preferably 0.3 to 3 g / cm³ 3 The density. This is important for increasing the volumetric capacity (mAh / cm³) of lithium-ion batteries. 3 It is advantageous.

[0162] The preferred porous particles used are amorphous carbon, silicon dioxide, boron nitride, silicon carbide, and silicon nitride, or other mixtures of these materials, with amorphous carbon, boron nitride, and silicon dioxide being particularly preferred.

[0163] These porous particles have a volume-weighted particle size distribution, where the diameter percentile d 50 Preferably ≥0.5μm, more preferably ≥1.5μm, and most preferably ≥2μm. Diameter percentile d 50 Preferably ≤20μm, more preferably ≤12μm and most preferably ≤8μm.

[0164] The volume-weighted particle size distribution of these porous particles is preferably at the diameter percentile d. 10 ≥0.2μm and d 90 Between ≤20.0 μm, more preferably in d 10 ≥0.4μm and d 90 ≤15.0 μm, and most preferably in d 10 ≥0.6μm and d 90 Between ≤12.0μm.

[0165] These porous particles have a volume-weighted particle size distribution, where the diameter percentile d 10 Preferably ≤10μm, more preferably ≤5μm, particularly preferably ≤3μm, and most preferably ≤2μm. Diameter percentile d 10 Preferably ≥0.2μm, more preferably ≥0.5μm and most preferably ≥1μm.

[0166] These porous particles have a volume-weighted particle size distribution, where the diameter percentile d 90 Preferably ≥4μm, and more preferably ≥8μm. Diameter percentile d 90 Preferably ≤18μm, more preferably ≤15μm, and most preferably ≤13μm.

[0167] The span d of the volume-weighted particle size distribution of porous particles 90 -d 10 Preferably ≤15.0μm, more preferably ≤12.0μm, very preferably ≤10.0μm, especially preferably ≤8.0μm, and most preferably ≤4.0μm.

[0168] The silicon-containing material produced by the method of the present invention has a volume-weighted particle size distribution with a span d that is preferably ≥0.6 μm, more preferably ≥0.8 μm, and most preferably ≥1.0 μm. 90 -d 10 .

[0169] The volume-weighted particle size distribution of porous particles can be determined according to ISO 13320 using a Mie model with static laser scattering measured by a Horiba LA 950 instrument, with ethanol as the dispersion medium for the porous particles.

[0170] Porous particles are preferably present in the form of monolithic particles. Particles can be, for example, separate or aggregated. Porous particles are preferably non-agglomerated. Agglomerates generally mean that during the production of porous particles, primary particles are initially formed and undergo fusion, and / or, for example, the primary particles are linked together by covalent bonds, thus forming aggregates. Primary particles are typically separate particles. Agglomerates or separate particles can form clusters. Clusters are loosely aggregated or primary particles linked together, for example, via van der Waals interactions or hydrogen bonds. Agglomerated aggregates can be easily broken back into aggregates by conventional kneading and dispersing techniques. By these techniques, the aggregates cannot disintegrate, or can only partially disintegrate into primary particles. The presence of porous particles in the form of aggregates, clusters, or separate particles can be visible by, for example, conventional scanning electron microscopy (SEM). Conversely, static light scattering methods used to determine the particle size distribution or particle size of matrix particles cannot distinguish between aggregates and clusters.

[0171] Porous particles can have any desired morphology, and thus can be, for example, flaky, plate-like, spherical, or needle-like, preferably flaky or spherical. Morphology can be characterized, for example, by 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 bulk. In the case of a sphere, the value of ψ is 1. According to this definition, the porous particles used in the method of the present invention have a sphericity ψ of preferably 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0172] Sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of a particle onto a surface to the measured circumference U of this projection. In the case of particles with ideal sphericity, the value of S will be 1. For porous particles used in the method of the present invention, S is based on the percentile of the numerical sphericity distribution. 10 To S 90The sphericity S is preferably in the range of 0.5 to 1.0 and more preferably 0.65 to 1.0. The sphericity S is measured, for example, from optical micrographs of individual particles or preferably (in the case of particles <10 μm) by scanning electron microscopy, by image evaluation using image analysis software (e.g., ImageJ).

[0173] These porous particles preferably have a density of ≥0.2 cm. 3 / g, more preferably ≥0.6cm 3 / g and the optimal value is ≥1.0cm 3 The gas can enter the pore volume at a rate of / g. This is useful for obtaining lithium-ion batteries with high capacity. The pore volume that a gas can enter is determined by gas adsorption with nitrogen according to DIN 66134.

[0174] Porous particles are preferably open-celled. Open-celled generally means that pores connect to the particle surface, for example, via channels, and can preferably transfer mass with the surrounding environment, especially gaseous compounds. This can be verified using gas adsorption measurements (according to the assessments of Brunauer, Emmett, and Teller's "BET") (i.e., specific surface area). These porous particles preferably have a surface area ≥50 μm. 2 / g, more preferably ≥500m 2 / g and the optimal value is ≥1000m 2 Specific surface area per g. BET surface area is determined according to DIN 66131 (using nitrogen).

[0175] The pores of porous particles can have any desired diameter, i.e., typically within the range of macropores (above 50 nm), mesopores (2 mm to 50 nm), and micropores (less than 2 nm). Porous particles can be used in any desired mixture of different pore types. It is preferred to use porous particles having macropores comprising less than 30% of the total pore volume, more preferably porous particles without macropores, and very preferably porous particles having at least 50% of pores with an average pore size of less than 5 nm. Very particularly preferably, the porous particles comprise only pores with a pore size of less than 2 nm (measured by: pore size distribution (gas adsorption) determined by BJH in the mesopore range and Horvath-Kawazoe (gas adsorption) according to DIN 66135 in the micropore range; the pore size distribution in the macropore range is evaluated by mercury porosimetry according to DIN ISO 15901-1).

[0176] The preferred porous particles have a porosity of less than 0.3 cm. 3 / g and more preferably less than 0.15cm 3The volume of pores that are inaccessible to gas ( / g). In this way, the capacity of lithium-ion batteries can also be increased. The volume of pores that cannot be penetrated by gas can be determined by the following formula:

[0177] The volume of pores inaccessible to gas = 1 / density of pure material = 1 / density of framework.

[0178] The density of pure materials here refers to the theoretical density of porous particles, based on phase composition or the density of the pure material (material density doesn't seem to have closed-pore properties). Data on the density of pure materials can be found, for example, in the National Institute of Standards and Technology's ceramics data portal (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the density of pure silicon dioxide is 2.203 g / cm³. 3 The density of pure boron nitride is 2.25 g / cm³. 3 The density of pure silicon nitride is 3.44 g / cm³. 3 The density of pure silicon carbide is 3.21 g / cm³. 3 The skeletal density is the actual density of porous particles (that gas can penetrate) measured using a helium hydrometer.

[0179] For clarity, it can be noted that porous particles differ from silicon-containing materials. Porous particles are used as starting materials for the preparation of silicon-containing materials. Typically, silicon is not present, more specifically, silicon obtained through the deposition of silicon precursors, which are preferably located within the pores of the porous particles and on the surface of the porous particles.

[0180] The silicon-containing material obtained by the method of the present invention by means of silicon deposition within the pores and on the surface of these porous particles has a volume-weighted particle size distribution, wherein the diameter percentile d 50 Preferably, the micrometer size is in the range of 0.5 to 20 μm. 50 The value is preferably at least 1.5 μm, and more preferably at least 2 μm. Diameter percentile d 50 Preferably, it is at most 13 μm, and more preferably at most 8 μm.

[0181] The volume-weighted particle size distribution of the silicon-containing material is preferably located at the diameter percentile d. 10 ≥0.2μm and d 90 Between ≤20.0 μm, more preferably in d 10 ≥0.4μm and d 90 ≤15.0 μm, and most preferably in d 10 ≥0.6μm and d 90 Between ≤12.0μm.

[0182] The silicon-containing material has a volume-weighted particle size distribution, where the diameter percentile d10 Preferably ≤10μm, more preferably ≤5μm, particularly preferably ≤3μm, and most preferably ≤1μm. Diameter percentile d 10 Preferably ≥0.2μm, more preferably ≥0.4μm, and most preferably ≥0.6μm.

[0183] The silicon-containing material has a volume-weighted particle size distribution, where the diameter percentile d 90 Preferably greater than 5 μm, and more preferably ≥10 μm. Diameter percentile d 90 Preferably ≤20μm, more preferably ≤15μm and most preferably ≤12μm.

[0184] The volume-weighted particle size distribution of this silicon-containing material has a span d 90 -d 10 Preferably ≤15.0 μm, more preferably ≤12.0 μm, even more preferably ≤10.0 μm, particularly preferably ≤8.0 μm, and most preferably ≤4.0 μm. The volume-weighted particle size distribution of this silicon-containing material has a span d. 90 -d 10 Preferably ≥0.6μm, more preferably ≥0.8μm and most preferably ≥1.0μm.

[0185] The silicon-containing material particles are preferably in particulate form. These particles can be separate or aggregated. The silicon-containing material is preferably non-aggregate, and even more preferably non-aggregate. The terms separate, agglomerated, and non-aggregate have already been defined above with respect to porous particles. The presence of silicon-containing materials in aggregate or aggregate form can be made visible, for example, by conventional scanning electron microscopy (SEM).

[0186] Silicon-containing materials can have any desired shape, and therefore can be, for example, flake-shaped, plate-shaped, spherical or needle-shaped, preferably flake-shaped or spherical particles.

[0187] 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 bulk. In the case of a sphere, the value of ψ is 1. Based on this definition, the silicon-containing material obtainable by the method of the present invention has a sphericity ψ of preferably 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0188] Sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of a particle onto a surface to the measured circumference U of this projection. In the case of particles with ideal sphericity, the value of S will be 1. For silicon-containing materials obtainable by the method of this invention, the percentile S is based on the numerical sphericity distribution. 10 To S 90The sphericity S is preferably in the range of 0.5 to 1.0, more preferably 0.65 to 1.0. The sphericity S is measured, for example, from optical micrographs of individual particles or preferably (in the case of particles smaller than 10 μm) by scanning electron microscopy, through graphic evaluation and measurement using image analysis software (e.g., ImageJ).

[0189] The cycle stability of lithium-ion batteries can be further improved by the morphology and composition of silicon-containing materials, especially by their specific surface area or internal porosity.

[0190] The silicon-containing material preferably contains 10-90% by weight, more preferably 20-80% by weight, very preferably 30-60% by weight, and especially preferably 40-50% by weight of porous particles, based on the total weight of the silicon-containing material.

[0191] The silicon-containing material comprises, based on the total weight of the silicon-containing material, preferably 10 wt% to 90 wt%, more preferably 20 wt% to 80 wt%, very preferably 30 wt% to 60 wt%, and especially preferably 40 wt% to 50 wt% of silicon obtained by deposition from the silicon precursor (preferably determined by elemental analysis such as ICP-OES).

[0192] If these porous particles comprise silicon compounds in the form of silica, the aforementioned wt% value of silicon obtained by deposition from the silicon precursor can be determined, for example, by subtracting the silicon mass of the porous particles, as determined by elemental analysis, from the silicon mass of the silicon-containing material determined by elemental analysis, and dividing the result by the mass of the silicon-containing material.

[0193] The volume of silicon deposited in porous particles is calculated by dividing the mass fraction of silicon obtained from the silicon precursor deposition (as a proportion of the total mass of the silicon-containing material) by the density of silicon (2.336 g / cm³). 3 The result of ).

[0194] The pore volume P of a silicon-containing material is the sum of the pore volumes that can and cannot be penetrated by gas. The Gurwitsch gas-permeable pore volume of silicon-containing materials can be determined by nitrogen adsorption according to DIN 66134.

[0195] The pore volume that prevents gases from entering a silicon-containing material can be determined using the following formula:

[0196] The volume of pores that cannot be entered by gas = 1 / skeletal density - 1 / pure material density.

[0197] In this paper, the pure material density of a silicon-containing material is a theoretical density that can be calculated by multiplying the sum of the theoretical pure material densities of the components included in the silicon-containing material by their respective weight-based percentage fractions in the total material. Therefore, for example, in a silicon-containing material where silicon is deposited on porous particles:

[0198] Pure material density = Theoretical pure material density of silicon * Silicon fraction in wt% + Theoretical pure material density of porous particles * Porous particle fraction in wt%.

[0199] Data on the density of pure materials can be obtained by technicians from sources such as the National Institute of Standards and Technology's Ceramic Data Portal (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the density of pure silicon dioxide is 2.203 g / cm³. 3 The density of pure boron nitride is 2.25 g / cm³. 3 The density of pure silicon nitride is 3.44 g / cm³. 3 The density of pure silicon carbide is 3.21 g / cm³. 3 .

[0200] Based on the volume of silicon included in the silicon-containing material and obtained by deposition of silicon precursors, 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%.

[0201] The pores contained in silicon-containing materials can be either gas-permeable or gas-inaccessible. The volume ratio of gas-permeable to gas-inaccessible pores in silicon-containing materials is typically in the range of 0 (no gas-permeable pores) to 1 (all pores are gas-permeable pores). The ratio of gas-permeable porosity to gas-inaccessible porosity in silicon-containing materials is preferably in the range of 0-0.8, more preferably in the range of 0-0.3, and particularly preferably in the range of 0-0.1.

[0202] The pores in silicon-containing materials can have any desired diameter, falling within the range of, for example, macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Silicon-containing materials can also contain any desired mixture of different pore types. Based on the total pore volume, the silicon-containing material preferably contains up to 30% macropores, particularly preferred is a silicon-containing material without macropores, and very particularly preferred is a silicon-containing material having at least 50% of pores with an average pore diameter of less than 5 nm based on the total pore volume. More particularly preferably, the silicon-containing material has only pores with a diameter of up to 2 nm.

[0203] Silicon-containing materials include silicon structures having a structural size of preferably up to 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm in at least one dimension (measurement method: scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)).

[0204] The silicon-containing material preferably comprises a silicon layer with a thickness of less than 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (measured by scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)). The silicon-containing material may also comprise silicon in particulate form. The diameter of the silicon particles is preferably at most 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (measured by scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)). Here, the number of silicon particles is preferably based on the diameter of the circle surrounding the particle in the microscopic image.

[0205] Silicon-containing materials preferably have a maximum of 100 μm 2 / g, more preferably less than 30m 2 / g, with a particularly preferred concentration of less than 10m 2 The specific surface area is measured per g. The BET surface area is determined according to DIN 66131 (using nitrogen). Therefore, when silicon-containing materials are used as active materials in the anode of lithium-ion batteries, SEI formation can be reduced and the initial coulombic efficiency can be enhanced.

[0206] The silicon in the silicon-containing material deposited from the silicon precursor may further include dopants, for example selected from the group consisting of 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 earth elements, or combinations thereof. Lithium and / or tin are preferred here. The amount of dopants in the silicon-containing material is preferably at most 1% by weight and more preferably at most 100 ppm, which can be determined by ICP-OES based on the total weight of the silicon-containing material.

[0207] Silicon-containing materials typically exhibit surprisingly high stability under compressive and / or shear loads. The pressure and shear stability of silicon-containing materials are demonstrated by the absence or virtual absence of changes in the porous structure of the material in SEM images, for example, under compressive loads (e.g., during electrode compression) and shear loads (e.g., during electrode fabrication).

[0208] Silicon-containing materials may optionally further include elements such as carbon. Carbon is preferably present in the form of a thin layer with a thickness of at most 1 μm, preferably less than 100 nm, more preferably less than 5 nm, and very preferably less than 1 nm (which can be measured by SEM or HR-TEM). These carbon layers may exist in the pores and on the surface of the silicon-containing material. The order and number of different layers in the silicon-containing material from different precursors can also be arbitrary, by correspondingly repeating and alternating measurements. Thus, for example, a layer of a material other than the porous particles (such as carbon) may first be present on the porous particles, and this layer may have a silicon layer or a silicon particle layer. It is also possible that, on the silicon layer or silicon particle layer, a layer of another material may be present in sequence, which may be different from or the same as the material of the porous particles, regardless of whether there is a layer of another material different from the porous particles between the porous particles and the silicon layer or the layer composed of silicon particles.

[0209] The silicon-containing material preferably includes ≤50 wt%, more preferably ≤40 wt%, and particularly preferably ≤20 wt% of additional elements. The silicon-containing material preferably contains ≥1 wt%, more preferably ≥3 wt%, and particularly preferably ≥2 wt% of additional elements. The figures in wt% are based on the total weight of the silicon-containing material. In alternative embodiments, the silicon-containing material does not include additional elements.

[0210] Another subject of the present invention is the use of silicon-containing materials as active materials in anode materials for lithium-ion batteries, and the use of such anodes in the production of lithium-ion batteries.

[0211] The anode material is preferably based on a mixture comprising a silicon-containing material available by the method of the present invention, one or more binders, graphite optionally as another active material, one or more other conductive components optionally, and one or more additives optionally.

[0212] By using additional conductive components in the anode material, it is possible to 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. Preferred embodiments of additional conductive components include conductive carbon black, carbon nanotubes, or metal particles, such as copper.

[0213] Based on the total weight of the anode material, the anode material preferably includes 0 to 95 wt%, more preferably 0 to 40 wt%, and most preferably 0 to 25 wt% of one or more other conductive components.

[0214] In the anode used in lithium-ion batteries, based on the total active material present in the anode material, the silicon-containing material may preferably be present at 5 wt% to 100 wt%, more preferably 30 wt% to 100 wt%, and most preferably 60 wt% to 100 wt%.

[0215] Preferred adhesives are polyacrylic acid or its alkali metal salts, more particularly lithium or sodium salts, polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, especially polyamide-imides, or thermoplastic elastomers, particularly ethylene-propylene-diene terpolymers. Alkali metal salts of the above-mentioned adhesives, especially lithium or sodium salts, are also preferred. All or preferably proportions of the acid groups in the adhesive may be present in the form of salts. The adhesive has a molar mass preferably from 100,000 g / mol to 1,000,000 g / mol. Mixtures of two or more adhesives may also be used.

[0216] Natural or synthetic graphite can be used as the graphite. Graphite particles preferably have a diameter percentile d. 10 >0.2μm and d 90 Volume-weighted particle size distribution between <200 μm.

[0217] Examples of additives include pore-forming agents, dispersants, flow control agents, or dopants; an example is elemental lithium.

[0218] The preferred formulation for the anode material preferably comprises 5 wt% to 95 wt% of silicon-containing material, 0 wt% to 90 wt% of additional conductive component, 0 wt% to 90 wt% of graphite, 0 wt% to 25 wt% of binder, and 0 wt% to 80 wt% of additives, wherein the figures in wt% are based on the total weight of the anode material, and wherein the total fraction of all components of the anode material is 100 wt%.

[0219] The components of the anode material constituting the anode ink or anode paste are preferably processed in a solvent selected from the group consisting of water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide, and ethanol, as well as mixtures of these solvents, preferably using a rotor-stator machine, a high-energy mill, a planetary kneader, a stirred ball mill, a rocker, or an ultrasonic device.

[0220] The anodic ink or anodic paste preferably has a pH of 2 to 8.5 (measured at 20°C using, for example, a WTW pH 340ipH meter with a SenTix R-JD probe).

[0221] Anode ink or anode paste can be applied to, for example, copper foil or another current collector using a doctor blade. Other coating methods can also be used according to the invention, such as spin coating, roll coating, dip coating, or stencil coating, painting, or spraying.

[0222] Before coating the copper foil with the anode material of the present invention, the copper foil may be treated with a commercial primer, such as one based on a polymer resin or silane. Primers can result in improved adhesion to copper, but they are not substantially electrochemically active in themselves.

[0223] The anode material is typically dried to a constant weight. The drying temperature is guided by the components and solvents used. It is preferably between 20°C and 300°C. The layer thickness refers to the dried layer thickness of the anode coating, preferably 2 to 500 μm.

[0224] Finally, the electrode coating can be calendered to set a defined porosity. The electrode thus produced preferably has a porosity of 15% to 85%, which can be determined according to DIN ISO 15901-1 via the mercury porosity determination method. Here, preferably, 25% to 85% of the pore volume, which can be determined in this way, is provided through pores having a pore size of 0.01 to 2 μm.

[0225] Another subject of the present invention is a lithium-ion battery comprising a cathode, an anode containing an etched silicon-containing material, two conductive connectors to the electrodes, a separator, an electrolyte (the separator and the two electrodes are impregnated with the electrolyte), and a housing housing these components.

[0226] In the context of this invention, the term lithium-ion battery also includes a battery cell. A cell typically includes a cathode, an anode, a separator, and an electrolyte. In addition to one or more cells, a lithium-ion battery preferably also includes a battery management system. The battery management system is generally used for controlling the battery via electronic circuitry, for example, particularly for identifying the state of charge, for protecting against complete discharge, or for protecting against overcharging.

[0227] Preferred cathode materials that can be used according to 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.

[0228] The separator is typically an electrically insulating, ion-permeable membrane, preferably made of polyolefins such as polyethylene (PE) or polypropylene (PP), or polyester, or a corresponding laminate. Alternatively, as is customary in battery manufacturing, the separator may be composed of or coated with glass or ceramic materials. Typically, the separator separates the first electrode from the second electrode, thereby preventing conductive connections (short circuits) between the electrodes.

[0229] The electrolyte is preferably a solution comprising one or more lithium salts (conductive salts) in an aprotic solvent. The conductive salt is preferably selected from the group consisting of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium imide, lithium methylide, lithium trifluoromethanesulfonate LiCF3SO3, lithium bis(trifluoromethanesulfonylimide)LiN(CF3SO2)2, and lithium borate. Based on the solvent, the concentration of the conductive salt is preferably between 0.5 mol / L and the solubility limit of the salt in question. More preferably, it is 0.8 to 1.2 mol / L.

[0230] The solvents used are preferably cyclic carbonates, propylene carbonates, ethylene carbonates, fluoroethylene carbonates, dimethyl carbonates, diethyl carbonates, methyl ethyl carbonates, dimethoxyethanes, diethoxyethanes, tetrahydrofurans, 2-methyltetrahydrofurans, γ-butyrolactones, dioxolane, acetonitrile, organic esters of carbonic acid, or nitriles (alone or as mixtures thereof).

[0231] The electrolyte preferably includes a film-forming agent, such as vinylene carbonate or fluoroethylene carbonate. In this way, a significant improvement in the cycle stability of the anode, including the etched silicon-containing material obtained according to the method of the invention, can be achieved. This improvement is primarily attributed to the formation of a solid electrolyte phase interface on the surface of the active particles. The proportion of the film-forming agent in the electrolyte is preferably between 0.1 wt% and 20.0 wt%. To match the actual capacity of the electrodes of the lithium-ion battery to each other in the best possible way, it is advantageous to balance the materials used for the positive and negative electrodes in terms of absolute capacity. Particularly important here is the fact that during the first or initial charge / discharge cycle (referred to as activation) of a secondary lithium-ion battery, a capping layer forms on the surface of the electrochemically active material in the anode. This capping layer is called the solid electrolyte phase interface (SEI) and typically consists mainly of electrolyte decomposition products and a certain amount of lithium, which is therefore no longer usable for further charge / discharge reactions. The thickness and composition of the SEI depend on the nature and quality of the anode material used and the nature and quality of the electrolyte solution used.

[0232] In the case of graphite, the SEI is particularly thin. On graphite, there is a typical loss of 5% to 35% of mobile lithium during the first charging step. Correspondingly, the reversible capacity of the battery also decreases.

[0233] In the case of an anode having an etched silicon-containing active material obtained by the method of the present invention, the first charging step is accompanied by a loss of preferably up to 30%, more preferably up to 20%, and most preferably up to 10% of mobile lithium, which is much lower than the values ​​described in the prior art (e.g., in US10,147,950B1).

[0234] All substances and materials used in the production of the lithium-ion battery described above are known. The components of this battery are produced and the battery is assembled according to processes known in the field of battery manufacturing.

[0235] The silicon-containing materials obtained by the method of this invention notably exhibit significantly improved electrochemical properties, resulting in lithium-ion batteries with high volumetric capacity and excellent performance characteristics. The silicon-containing materials obtained by the method of this invention are permeable to both lithium ions and electrons, thus allowing charge transport. The SEI in lithium-ion batteries can be largely reduced using the silicon-containing materials obtained by the method of this invention. Furthermore, due to the design of the silicon-containing materials obtained by the method of this invention, there is no longer any separation between the SEI and the surface of the active material, or at least a significantly reduced separation. All of these contribute to high cycle stability in portions of such lithium-ion batteries whose anodes contain silicon-containing materials obtainable by the method of this invention. Detailed Implementation

[0236] The following examples are provided to further illustrate the invention described herein.

[0237] The analytical methods and instruments used for characterization are as follows:

[0238] Inorganic analysis / elemental analysis:

[0239] The C content reported in the examples was determined using a Leco CS230 analyzer; the O content, and, where appropriate, the N and H content, was determined using a Leco TCH-600 analyzer. Qualitative and quantitative determinations of other reported elements were performed by ICP (inductively coupled plasma) emission spectrometry (Optima 7300DV, from Perkin Elmer). For this analysis, the samples were acid-digested (HF / HNO3) in a microwave (Microwave 3000, from Anton Paar). ICP-OES determination was performed according to ISO 11885 “Water quality—Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885:2007); German version EN ISO 11885:2009”, which is used for the analysis of acidic aqueous solutions (e.g., acidified samples of drinking water, wastewater and other waters, aqua regia extracts from soil and sediments).

[0240] Particle size determination:

[0241] Particle size distribution was determined in the context of this invention according to ISO 13320 using static laser scattering with a Horiba LA 950. In sample preparation, particular care must be taken regarding the dispersion of particles in the measurement solution to avoid measuring the size of aggregates instead of individual particles. For measurement, the particles were dispersed in ethanol. For this purpose, prior to measurement, the dispersion was sonicated at 250W in a Hielscher UIS250V ultrasonic laboratory instrument with an LS24d5 ultrasonic welding electrode and, if necessary, treated for 4 minutes.

[0242] BET surface area measurement:

[0243] The specific surface area of ​​the material was measured by the BET method (determined with nitrogen according to DIN ISO 9277:2003-05) using a Sorptomatic 199090 instrument (Porotec) or an SA-9603MP instrument (Horiba) with nitrogen gas adsorption.

[0244] Skeletal density:

[0245] The skeletal density, i.e. the density of porous solids (based solely on the volume of pore space accessible from the outside), is determined by the He specific gravity determination method according to DIN 66137-2.

[0246] The volume of the pores through which gas can enter:

[0247] The pore volume into which Gurwitsch gas can enter is determined by nitrogen adsorption measurement according to DIN 66134.

[0248] Conversion rate:

[0249] The conversion rate is calculated as the quotient of the molar amount of starting material (reactant) converted relative to the molar amount of starting material (reactant) used. In these examples, it is shown how much of the SiH4 molecules used were converted to Si.

[0250]

[0251] Yield:

[0252] Yield is the quotient of the actual mass of the product obtained to the theoretically maximum possible mass of the product. Yield is expressed as a percentage (%) of mass.

[0253]

[0254] It is a measure of the loss of particles entrained by the airflow.

[0255] Example

[0256] The grade 4.0 SiH4 used was obtained from Linde GmbH.

[0257] In all embodiments, amorphous carbon is used as a porous starting material:

[0258] Specification surface area = 1907m² 2 / g

[0259] Hole volume = 0.96 cm³ 3 / g

[0260] Average volume-weighted particle size D 50 =2.95μm

[0261] Particle density = 0.7 g / cm³ 3

[0262] Cohesion, Geldart classification: C

[0263] The reactor used for the experimental embodiment is as follows:

[0264] Reactor (of this invention):

[0265] All embodiments of the invention are carried out within specific variations of the method—reactors A, B, and C are identical containers. The reactors used are constructed with an inner radius r. B The reactor consists of a cylindrical lower part (beaker) with a diameter of 121.5 mm and a height h of 512 mm, a lid with multiple connections (e.g., for gas supply, gas discharge, temperature measurement, and pressure measurement), and a flat base. There is no internal material on the walls. The reactor volume V is... B =24l. The perimeter of any cross-section of the plane of rotation generated by the rotation of the internal reactor profile around the axis of rotation is calculated to be 763.4 mm. The agitator used has a radius r B =119.5mm multi-threaded helical stirrer. The complete rotation of the helical stirrer creates a rotating surface. The circumference of any section perpendicular to the axis of rotation of this rotating surface is 750.8mm. The tight clearance W = 0.98 obtained from these two circumferences. The height of the helix corresponds to approximately 75% of the net height inside the reactor. The reactor is filled such that the height of the stirred particle bed is lower than the height of the helix. Therefore, more than 50% of the reaction zone is within the area of ​​the stirrer with a tight clearance W = 0.98. The beaker is electrically heated using a jacketed heater. The temperature between the heater and the reactor is measured in principle. Gas is supplied to the lower half of the bed (125mm above the reactor base) through two submerged tubes with an outer diameter of d = 6mm, which directly introduces the gas into the stirred bed.

[0266] Fluidized bed reactor (not of this invention):

[0267] The fluidized bed reactor used in Comparative Example 1 (not of this invention) consists of a cylindrical section with an outer diameter of 160 mm and a height of 1200 mm. The cylindrical section comprises a bottom chamber and the fluidized bed reactor itself. The two sections are separated from each other by a permeable substrate. Following the cylindrical reactor section at the top is the reactor section, which has a cross-sectional area twice the size of the cylindrical reactor section. At the top of the reactor, there is a cover with filter elements for gas exhaust. The reaction temperature is regulated by heating the reactor walls; the height of the heating zone is 80% of the cylindrical length from the permeable substrate. The process temperature is measured by the temperature between the heating jacket and the outer wall of the reactor. Heating is performed electrically. Therefore, the fluidizing gas is preheated with a gas heater before the gas flow enters the fluidized bed reactor. The gas flow is pulsed using a directly controlled solenoid valve. The fluidization index is used as a measure of fluidized bed quality. In preliminary tests, the minimum fluidization velocity was determined by measuring the pressure loss of the fluidized bed.

[0268] Definition of fluidization index: The fluidization index FI is defined as the pressure loss Δp measured on a fluidized bed. WS,测量的 The theoretical maximum achievable pressure loss Δp WS,th The ratio of , and calculated using the following Equation 1:

[0269]

[0270] Neglecting gas density, the mass m of the bed... S gravitational acceleration g and reactor cross-sectional area A WS The theoretically maximum pressure loss is calculated to be Δp. WS,th =m S ·g / A WS In the case of a fully fluidized bed, the fluidization index is set to a value no greater than 1.

[0271] Fluidization Index Determination: The fluidization index is the ratio of measured pressure loss to the theoretical maximum possible pressure loss. To determine the fluidization index, it is necessary to capture the pressure loss of the fluidized bed through technical measurement. Pressure loss measurement occurs as a measurement of the pressure difference between the bottom and top of the fluidized bed. A differential pressure instrument converts the pressure detected on the membrane into a digital value and displays the pressure difference. Pressure measurement lines must be configured such that they are positioned directly above the gas-permeable substrate and directly above the fluidized bed. Accurate capture of the weight of the introduced particle bed is also necessary for determining the fluidization index. See also [VDI-] 11th edition, section L3.2 Flow forms and pressure loss influidized beds, pp.1371-1382, Springer Verlag, Berlin Heidelberg, 2013].

[0272] Determination of Minimum Fluidization Velocity: The minimum fluidization velocity is the fluidizing gas velocity – based on the empty reactor cross-sectional area – of the particle bed transitioning from a fixed bed to a fluidized bed. The minimum fluidization velocity can be determined by simultaneously measuring the regulated fluidizing gas flow using a mass flow meter and simultaneously measuring the pressure loss of the fluidized bed using a digital differential pressure gauge. Given the reactor's cross-sectional area, the fluidizing gas velocity can be calculated from the measured fluidizing gas flow. The plotted distribution of pressure loss against the fluidizing gas velocity is called the characteristic fluidized bed line. It should be noted that the characteristic fluidized bed line starts with a high fluidizing gas velocity and is recorded by gradually decreasing that velocity. In the case of pure fixed bed crossflow, the pressure loss increases linearly. The associated fluidization index FI is less than 1. For a fully formed fluidized bed, the measured pressure loss is constant. The associated fluidization index FI is 1. The minimum fluidization state lies at the transition between two ranges. The associated fluidizing 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 ranges, 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- 11th edition, section L3.2 Flow forms and pressure loss in fluidized beds, pp.1371-1382, Springer Verlag, Berlin Heidelberg, 2013].

[0273] Rotary tube furnace reactor (not of this invention):

[0274] In Comparative Example 2 (not of this invention), an indirect-heating rotary tube furnace was used. This furnace has a rotating tube made of quartz glass, rotatable about its longitudinal axis, with a diameter of 20 cm and a heatable volume of 30 L. The outer wall temperature of the quartz tube is used as a measure of the process temperature. Heating occurs electrically and can be adjusted in three zones. For the silicon permeation reaction to be carried out, the rotating tube should have an hermetically sealed design.

[0275] Comparative Example 1 (fluidized bed, not of this invention): Production of silicon-containing materials in a fluidized bed reactor using pulsed fluidized gas flow.

[0276] 500g of amorphous carbon was used as the porous starting material (specific surface area = 1907m²). 2 / g, pore volume = 0.96cm³ 3 / g, average volume-weighted particle size D 50 =2.95μm, particle density =0.7g / cm³ 3 (Geldart C-grade particles) are introduced into the reactor.

[0277] The granular bed was fluidized with a nitrogen-based fluidizing gas, the flow rate of which was set to at least three times the minimum fluidization rate determined in preliminary tests. Simultaneously, a solenoid valve was used to oscillate the gas flow, with a frequency of 3 Hz between the open and closed positions. The temperature in the reactor was then increased to a setpoint of 430°C. Due to the temperature increase, the fluidizing gas flow was adapted to achieve a fluidization index >0.95.

[0278] When the set temperature of 430°C is reached, the fluidizing gas is replaced with a reaction gas containing 10 vol% SiH4. During and after switching the fluidizing gas, the gas flow is maintained in a pulsating pattern of 3 Hz between the valve's open and closed positions. Furthermore, not only is the fluidization index FI = 0.98, but the flow rate of the fluidizing gas is also adjusted to ensure that the fluidization index is always greater than 0.95 due to the density changes of the porous raw material during silicon deposition.

[0279] After a 2.6-hour reaction time, the fluidizing gas was switched back to a pulsed flow of nitrogen. The heating power was reduced. When the temperature reached 50°C, the fluidizing gas flow was switched to a fluidizing gas consisting of 5 vol% oxygen in nitrogen and maintained for 60 minutes to allow controlled reaction of any reactive groups present on the surface of the resulting product. The reactor was then cooled to room temperature.

[0280] After the operation was completed, 990 g of black solid was discharged from the reactor. The obtained silicon-containing material was introduced into a cylindrical container and homogenized in a rotary drum annular mixer. Agglomerates formed as a result of the fluidized bed process were removed by sieving. The reaction conditions used for production and the physical properties of the silicon-carbon composite particles are summarized in Table 2.

[0281] Comparative Example 2 (Rotating Tube Furnace, not of this invention): Production of silicon-containing materials in a rotating tube reactor using a method not of this invention.

[0282] 0.9 kg of the same porous carbon (specific surface area = 1907 m²) as in Comparative Example 1 was loaded into a rotating tubular reactor (internal volume 30 L). 2 / g, pore volume = 0.96cm³ 3 / g, average volume-weighted particle size D 50 =2.95μm, particle density =0.7g / cm³ 3(Geldart C-grade particles). After inertization with nitrogen, the reactor was heated to 430°C. When this reaction temperature was reached, the reaction gas (10% SiH4 in N2, metering rate 0.4 g Si / (cm³)) was introduced. 3 The product was passed through the reactor for 8.5 hours, during which time the reactor rotated at approximately 7 rpm. The reactor was then purged with an inert gas. Before removing the product from the reactor, it was cooled to room temperature under an inert gas atmosphere. The reaction conditions used for production and the physical properties of the silicon-carbon composite particles are summarized in Table 2.

[0283] Examples 1-5 (Invention): Using silane SiH4 as a silicon precursor, silicon-containing materials were produced under standard pressure (0.1 MPa) using the method of the present invention (the corresponding values ​​of parameter AD and the number of examples are summarized in Table 1).

[0284] In stage 1 of the method, 2.4 kg of the same porous carbon (specific surface area = 1907 m²) as in Comparative Examples 1 and 2 was used. 2 / g, pore volume = 0.96cm³ 3 / g, average volume-weighted particle size D 50 =2.95μm, particle density =0.7g / cm³ 3 Geldart C-grade particles were introduced into the reactor of the present invention (volume 24 L, diameter 25 cm) equipped with a stirring mechanism. The reactor was then adjusted to 350°C for 240 minutes and inertized with nitrogen.

[0285] In stage 2, the reactor is heated to 430°C. When the reaction temperature is reached, a reaction gas at a concentration of A mol% and a metering rate B based on pore volume is passed through the reactor for C hours. The gas phase is supplied to the reactor while the particle bed is turned over by the tight-gap stirring mechanism and spiral stirrer of the present invention, such that the ratio of the turning time to the average residence time of the reactive component is D, and the movement of the bed can be described by Froude number 3. In stage 3, the silicon-containing material is cooled to a temperature of 70°C over a period of 120 minutes. The reactor is then purged with nitrogen for 1 hour, with lean air containing 5 vol% oxygen for 1 hour, with lean air containing 10 vol% oxygen for 1 hour, with lean air containing 15 vol% oxygen for 1 hour, and subsequently with air for 1 hour. Finally, the product is removed from the reactor.

[0286] Table 1 Test parameters of embodiments 1 to 5 of the invention

[0287]

[0288] Table 2 below summarizes the reaction conditions used for production and the physical properties of silicon-carbon composite particles.

[0289] Table 2

[0290]

[0291] *Not of this invention

[0292] Regardless of the reactor used, equivalent physical properties can be obtained. However, compared with fluidized beds and rotating tube furnaces, the reactor system of the present invention can improve SiH4 conversion, product yield, and reaction time.

[0293] Evaluation of silicon composite particles in electrochemical cells

[0294] Example 6: An anode containing silicon-containing materials (from Examples 1 to 5) obtained by the method of the present invention and silicon-containing materials (from Comparative Examples 1 and 2) as corresponding materials, a silicon-containing material produced by the method of the present invention, and electrochemical testing in the lithium-ion battery of the present invention.

[0295] 29.71 g of polyacrylic acid (dried to constant weight at 85 °C; Sigma-Aldrich, Mw approx. 450,000 g / mol) and 756.60 g of deionized water were stirred in a shaker (290 l / min) for 2.5 h until the polyacrylic acid was completely dissolved. This solution was then mixed in portions with lithium hydroxide monohydrate (Sigma-Aldrich) until the pH reached 7.0 (measured using a WTW pH 340i pH meter and a SenTix R-JD probe). The solution was then further mixed in a shaker for 4 h. 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 in a planetary mixer (SpeedMixer, DAC 150SP) at 2000 rpm. Subsequently, 3.35 g of each of the silicon-containing materials obtained by the method of the present invention from Examples 1 to 5, and the silicon-containing materials obtained by a non-inventive method from Comparative Examples 1 and 2, were stirred at 2000 rpm for 1 min. Then, 1.21 g of 8% conductive carbon black dispersion and 0.8 g of deionized water were added and incorporated into a planetary mixer at 2000 rpm. This was followed by dispersion in a dissolver at 3000 rpm and a constant temperature of 20°C for 30 min. The ink was then degassed again in a planetary mixer at 2500 rpm under reduced pressure for 5 min.

[0296] The completed 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 groove height of 0.1 mm. The resulting anolyte coating was then dried at 50 °C and 1 bar air pressure for 60 minutes. The average surface weight of the dried anolyte coating was 3.0 mg / cm³. 2 The coating density is 0.8 g / cm³. 3 .

[0297] Electrochemical studies were conducted on a button cell (CR2032 type, Hohsen Corp.) with a dual-electrode arrangement. The electrode coating served as either the counter electrode or the anode (Dm = 15 mm). The coating was based on a 6:2:2 lithium nickel manganese cobalt oxide with a content of 94.0% and a concentration of 15.9 mg / cm³. 2 A coating of average basis weight (obtained from SEI) was used as the working electrode or positive electrode (Dm = 15 mm). Glass fiber filter paper (Whatman, GD type D) impregnated with 60 μl of electrolyte was used as the separator (Dm = 16 mm). The electrolyte used consisted of a 1.0 mol solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of fluoroethylene carbonate and diethyl carbonate. The battery was constructed in a glove box (<1 ppm H2O, O2); the water content in the dry mass of all components used was less than 20 ppm.

[0298] Electrochemical tests were performed at 20°C. The battery was charged using the cc / cv (constant current / constant voltage) method, with a constant current of 5 mA / g (corresponding to C / 25) in the first cycle and a constant current of 60 mA / g (corresponding to C / 2) in subsequent cycles. After reaching the voltage limit of 4.2V, it was charged at a constant voltage until the current dropped below 1.2 mA / g (corresponding to C / 100) or 15 mA / g (corresponding to C / 8). The battery was discharged using the cc (constant current) method, with a constant current of 5 mA / g (corresponding to C / 25) in the first cycle and a constant current of 60 mA / g (corresponding to C / 2) in subsequent cycles until the voltage limit of 2.5V was reached. The specific current selected was based on the weight of the coating on the positive electrode. Electrodes were selected to establish a cathode to anode capacity ratio of 1:1.2.

[0299] The electrochemical test results of all lithium-ion batteries, including those from Examples 1 to 5 of the present invention and Comparative Examples 1 and 2, using silicon-containing materials, are listed in Table 3.

[0300] Table 3

[0301]

[0302] *Not of this invention.

Claims

1. A method for preparing 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. The thermal decomposition of the silicon precursor occurs in the reaction zone of the reactor through which the gas passes, and the particles are tumbled in the reaction zone by a tightly spaced stirrer in the heating zone during the thermal decomposition process. in, If in Equation 1, the stirring mechanism is a tight-gap mechanism. W(h) = the tight clearance in the reaction zone for all values of h, where u R (h) = the outer perimeter of the agitator in the cross-section at height coordinate h, and u B (h) = the inner perimeter of the reactor in the cross-section at height coordinate h.

2. The method according to claim 1, wherein the reaction zone of the reactor is rotationally symmetric. in, If, in Equation 1, the stirring mechanism has a tight gap... Then among them W(h) = the tight clearance of the stirring mechanism in a rotationally symmetric reactor, defined as the quotient of the perimeters of two plane sections perpendicular to the axes of rotation of the two planes of rotation, where h represents the height coordinate. u R (h) = the perimeter of the inner cross-section calculated according to equation 2, u R (h) = 2πr R (h) (2) Calculated at multiple arbitrary points h on the plane of rotation perpendicular to the axis of rotation, through the circular inner section of the planar segment. r R (h) = the distance from the axis of rotation to the outer contour of the stirring mechanism, wherein the stirring mechanism comprises all components attached thereto, u B (h) = Circumference of the outer revolution surface calculated according to Equation 3 u B (h)=2πr B (h) (3) At any point h on the plane of rotation perpendicular to the axis of rotation, the outer circular plane of rotation of the planar segment is calculated, which is formed by rotating the inner contour of the reactor around the axis of rotation. r B (h) = the distance from the inner contour of the reactor to the axis of rotation. Furthermore, for half of all values ​​of h, the tight gap W(h) in the reaction zone must be W(h) > 0.

9.

3. The method according to claim 1 or 2, wherein, During the deposition of the silicon precursor, a process using 0.1-2 g Si / cm³ per hour is employed. 3 The rate of addition of porous particles with pore volume is measured.

4. The method according to claim 1 or 2, wherein, During the deposition process, at a rate of 1-700 kg Si / m³ per hour 2 The silicon precursor is added at a rate that measures the maximum flow cross-sectional area of ​​the reactor in the reaction zone.

5. The method according to claim 1 or 2, wherein the thermal decomposition of the silicon precursor occurs at 0.08 to 5 MPa.

6. The method according to claim 1 or 2, wherein the thermal decomposition of the silicon precursor is carried out at 280 to 900°C.

7. The method according to claim 1 or 2, wherein the bed temperature in the reaction zone of the reactor equipped with a close-gap stirrer is in the range of 100°C to 1000°C.

8. The method according to claim 1 or 2, wherein the method is operated in a cascade reactor system comprising multiple reactors.

9. The method of claim 7, wherein the method comprises at least stages 1 to 3: Stage 1: Reactor A is filled with porous particles and the particles are pretreated. The pretreated particles are then transferred to reactor B or a storage container, or the material is retained in reactor A. Stage 2: Pass a gas stream consisting of an inert gas and / or at least one reactive component containing a silicon precursor and / or at least one silicon-free precursor through reactor B. The reactor is adjusted to a temperature at which the thermal decomposition of the reactive component occurs on the surface and within the pores of the porous particles. The particle bed in reactor B is agitated using a tight-gap stirrer, such that the movement of the particle bed can be described by a Froude number in the range of 1 to 10. A gas phase is supplied to reactor B while the particle bed in reactor B is agitated by a tight-gap stirring element, such that the ratio of agitation time to the average residence time of the reactive component is less than 1. After silicon has been introduced into and onto the pores of the porous particles, the silicon-containing material is transferred to reactor C or to a storage container for temporary storage, or the material is retained in reactor B. Phase 3: Post-processing of silicon-containing particles for functionalization and / or coating of the surface of the silicon-containing particles, cooling the particles to a defined temperature and recovering the silicon-containing material from reactor C.

Images