Method for producing silicon-containing materials in a cascade reactor system

Abstract

The present invention provides a method for producing silicon-containing materials by pyrolysis of one or more silicon precursors in the presence of one or more porous particles, wherein silicon is deposited in the pores and on the surfaces of the porous particles in a cascade reactor system comprising multiple reactors, Anode materials, anodes and lithium ion batteries are provided that include the silicon-containing materials.

Description

[Technical Field]

[0001] The present invention relates to a method for producing silicon-containing materials by thermal decomposition of a silicon precursor in the presence of porous particles, whereby silicon is deposited within the pores and on the surface of the porous particles, and to the use of the resulting silicon-containing materials as active materials for the anodes of lithium-ion batteries. [Background technology]

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

[0003] The intercalation and deintercalation of lithium ions in silicon suffers from the drawback of very rapid volume changes, which can reach 300% in the case of complete intercalation. Such volume changes subject silicon-containing active materials to severe mechanical loads that can ultimately lead to their decomposition. This process, also known as electrolytic grinding, can result in loss of electrical contact in the active material and electrode structure, and therefore in a sustained and irreversible loss of capacity in parts of the electrode.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the electrolyte components, continuously forming a passivating protective layer (solid electrolyte interface, SEI). These components are no longer electrochemically active. The lithium bound within them becomes unavailable to the system, leading to a significant and continuous loss of capacity in the battery's parts. Due to the extreme volumetric changes of silicon during battery charge / discharge, the SEI is periodically decomposed, which exposes more of the unoccupied surface of the silicon-containing active material and leads to further SEI formation. In a complete battery, the amount of mobile lithium corresponding to useful capacity is limited by the cathode material, so lithium is increasingly consumed, and after just a few cycles the battery's capacity drops to an unacceptable level from a performance standpoint.

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

[0006] A series of silicon-carbon composite particles have been described as active materials for the anode of lithium-ion batteries, in which silicon is incorporated into porous carbon particles starting from a gas or liquid precursor.

[0007] For example, US 10,147,950 B2 describes the deposition of silicon from monosilane SiH4 in porous carbon by the method of CVD (chemical vapor deposition) or PE-CVD (plasma-enhanced chemical vapor deposition) at high temperatures of 300-900 °C in a tubular furnace or equivalent type of furnace, preferably with particle agitation. This method uses a mixture of 2 mol% monosilane and nitrogen as an inert gas. As a result of the low concentration of silicon precursor in the gas mixture, the reaction time is very long. Furthermore, US 10,147,950 B2 discloses numerous possible combinations of different temperature ranges from 300-900 °C and different pressure ranges from 0.01 to 100 bar for carrying out the deposition of silicon on and in the porous starting material.

[0008] A similar procedure is described in US 10,424,786 B1, in which the silicon precursor is introduced as a mixture with an inert gas under a total pressure of 1.013 bar. WO 2012 / 097969 A1 describes the deposition of ultrafine silicon particles in the range of 1 to 20 nm by heating silane as a silicon precursor on a porous carbon support at 200 to 950 °C, the silane being diluted with an inert gas to prevent weak agglomeration of the deposited silicon particles and / or the formation of thick layers, and the deposition being carried out in the pressure range of 0.1 to 5 bar.

[0009] Motevalian et al., Ind. Eng. Chem. Res. 2017, 56, 14995, describe the deposition of silicon layers at high pressure in the absence of a porous matrix. Again, the silicon precursor used, in this case monosilane SiH4, is present only in low concentrations of up to 5 mol% in the total gas volume.

[0010] The above-mentioned methods have various serious drawbacks.Usually, silicon precursor is used at low absolute pressure and partial pressure, and therefore at low concentration, so that it requires long reaction time to achieve high silicon fraction in silicon-containing material.Another drawback of these methods is that only a small part of the reactive gas that is fed reacts, so the gas that goes out of the reactor must go through expensive and inconvenient recycling or disposal operation, which further increases costs, especially when using silicon precursor (which is subject to strict technical safety requirements). [Prior art documents] [Patent documents]

[0011] [Patent Document 1] European Patent No. 1730800 [Patent Document 2] U.S. Patent No. 10,559,812 [Patent Document 3] U.S. Patent No. 10,819,400 [Patent Document 4] European Patent No. 3335262 [Patent Document 5] U.S. Patent No. 10,147,950 [Patent Document 6] U.S. Patent No. 10,424,786 [Patent Document 7] International Publication No. 2012 / 097969 [Non-patent literature]

[0012] [Non-Patent Document 1] M.Obrovac,VLChevrier Chem.Rev.2014, 114, 11444 [Non-patent document 2] Motevalian et al., Ind. Eng. Chem. Res. 2017, 56, 14995 Summary of the Invention [Problem to be solved by the invention]

[0013] Against this background, the object of the present invention is to provide a method for producing a silicon-containing material, preferably having a high storage capacity for lithium ions, which allows high cycling stability when used as an active material in the anode of a lithium-ion battery, starting from porous particles and silicon precursors, which method is technically simple to carry out. , special Regarding reaction time have advantages . [Means for solving the problem]

[0014] Surprisingly, this objective has been substantially achieved by a method for depositing silicon into the pores and on the surface of porous particles by decomposing a silicon precursor at a pressure of at least 7 bar in a cascade reactor system.It is known from methods for producing polycrystalline silicon that depositing silicon at relatively high pressures is accompanied by increased and undesirable formation of dust.(J.O.O.dden et al., Solar Energy Mat. & Solar Cells 2005, 86, 165).This is counterproductive to both the deposition of silicon on the inner and outer surfaces of the pores of porous particles and product yield.Surprisingly, this harmful effect is overcome by the method of the present invention.

[0015] The production of silicon-containing materials as active materials for lithium-ion battery anodes is particularly economically interesting, for example, starting from porous particles and silicon precursors under pressure according to the present invention, which surprisingly allows for an increased amount of silicon precursor material in the porous particles and thus a shorter reaction time.Another economic advantage of this method is the higher silicon yield relative to the silicon precursor used.In addition, silicon deposition is particularly uniform, occurring especially within the porous particles, resulting in high stability of the resulting silicon-containing material when used as an active material in lithium-ion battery anodes, with a small volume change during cycling.In contrast to producing related materials in only one reactor (not according to the present invention), the cascade reactor procedure has the advantage that the long cooling and heating stages of one reactor are reduced.This is advantageous in terms of time and energy technology compared to using only one reactor, and reduces physical stress on the reactor. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention provides a method for producing silicon-containing materials by pyrolysis of one or more silicon precursors in the presence of one or more porous particles, wherein silicon is deposited within the pores and on the surfaces of the porous particles in a cascade reactor system comprising multiple reactors.

[0017] In one preferred embodiment, the method comprises at least steps 1-7. Step 1: Packing porous particles into reactor A and pretreating the particles; Step 2: Transfer the pretreated particles to reactor B and charge the reactor with reactive components including at least one silicon precursor; Step 3: Heat reactor B to a target temperature at which the silicon precursor begins to decompose within the reactor; Step 4: Decomposing the silicon precursor and depositing silicon in the pores and on the surface of the porous particles to form a silicon-containing material, and increasing the pressure to at least 7 bar; Step 5: Cooling Reactor B; Step 6: Removing the gaseous reaction products formed during the deposition process from reactor B and transferring the silicon-containing material to reactor C; Step 7: Remove the silicon-containing material from reactor C.

[0018] In a preferred embodiment, stage 1 is configured as follows: Phase 1 Step 1.1: Reactor A is filled with porous particles; Step 1.2: Pretreating particles in reactor A; Step 1.3: The pretreated particles are transferred to reactor B, or after intermediate storage in storage vessel D, transferred to reactor B, or the material remains in reactor A.

[0019] In a preferred embodiment, stage 2 is configured as follows: Phase 2 Step 2.1: Heating or cooling of particles in reactor B, Optionally, step 2.2: establishing pressure in reactor B; Optionally, step 2.3: charging reactor B with at least one silicon-free reactive component; Step 2.4: Reactor B is charged with at least one reactive component including at least one silicon precursor.

[0020] In a preferred embodiment, stage 3 is configured as follows: Stage 3 Step 3.1: Heat reactor B to a target temperature at which the reactive components begin to decompose within reactor B.

[0021] If at least one silicon-free reactive component is in reactor B, step 3.2 preferably follows. Step 3.2: Decompose reactive components that do not contain the Si precursor.

[0022] In a preferred embodiment, stage 4 is configured as follows: Stage 4 Step 4.1: The silicon precursor is decomposed, depositing silicon in the pores and on the surface of the porous particles, and the pressure is increased to at least 7 bar. Step 4.2: Establish a minimum temperature or temperature profile over a predetermined period of time that results in a pressure of at least 7 bar.

[0023] In a preferred embodiment, stage 5 is configured as follows: Stage 5 Step 5.1: Adjust the pressure in reactor B to a predetermined pressure; Step 5.2: Adjust reactor B to a predetermined temperature or predetermined temperature profile.

[0024] In a preferred embodiment, step 6 is configured as follows: Stage 6 Step 6.1: Removal of gaseous reaction products formed during deposition from reactor B; Step 6.2: The particles are transferred to reactor C or transferred to reactor C after intermediate storage in storage vessel E, or the material remains in reactor B; Step 6.3: Adjust reactor C to a predetermined temperature or a predetermined temperature profile and a predetermined pressure.

[0025] In a preferred embodiment, step 7 is configured as follows: Stage 7 Step 7.1: Post-treating the particles in reactor C to deactivate the particle surface; Step 7.2: The particles are cooled to a predetermined temperature and the silicon-containing material is removed from the reactor C and preferably transferred directly to a storage vessel E or charged directly into a suitable container.

[0026] In step 1.1, the porous particles are loaded into a heatable and / or vacuum-rated and / or pressure-rated reactor A, which loading can be done manually or automatically.

[0027] The filling of reactor A with porous particles can be carried out, for example, under an inert gas atmosphere, or preferably under ambient air. Examples of inert gases that can be used include hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide, or mixtures thereof, such as forming gas. Argon or, in particular, nitrogen is preferred.

[0028] Automated filling can be achieved using, for example, a metering screw, star wheel, vibrating trough, plate-type metering device, belt-type metering device, vacuum metering system, negative metering system, or other metering system, for example, from a silo, bag shaker, or other container system.

[0029] The purpose of pretreating the particles in reactor A in step 1.2 is to remove air / oxygen, water or dispersants such as surfactants or alcohols, and impurities from the particles. This can be achieved by inerting with an inert gas, increasing the temperature to 1000°C, reducing the pressure to 0.01 mbar, or a combination of the individual operating steps. The inert gas used can be, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, or carbon dioxide, or a mixture thereof, such as forming gas. Argon or, in particular, nitrogen is preferred.

[0030] The purpose of the pretreatment in step 1.2 may also be to modify the chemical surface properties of the porous particles with additional substances. The addition may occur before or after drying, and there may be an additional heating step before the material is transferred to step 1.3. The substances may be introduced into the reactor in gaseous, solid, or liquid form, or as a solution, including mixtures, emulsions, suspensions, aerosols, or foams. The substances in question may be, for example, carbon dioxide, water, sodium hydroxide, potassium hydroxide, hydrofluoric acid, phosphoric acid, nitric acid, ammonium dihydrogen phosphate, lithium nitrate, sodium nitrate, potassium nitrate, lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide, potassium bromide, or alkoxides.

[0031] The transfer in step 1.3 can be carried out, for example, by drop tubes, continuous conveyors, flow conveyors / suction or pressure conveying units (e.g., vacuum conveyors, transport blowers), mechanical conveyors (e.g., drive roller conveyors, screw conveyors, carousel conveyors, circulating conveyors, bucket units, star wheel locks, chain conveyors, scraper conveyors, belt conveyors, vibrating conveyors), gravity conveyors (e.g., chutes, roller beds, ball beds, rail beds), and non-continuous conveyors, floor-based and rail-free (e.g., automated vehicles, manual forklift trucks, electric forklift trucks, driverless This can be achieved by transport systems (DTS), air cushion vehicles, hand carts, powered carts, motorized vehicles (tractors, wagons, forklift stackers), transfer carriages, transfer / lift carriages, shelf access devices (with or without converters, capable of following curved paths), floor-based rail-bound (e.g., plant railways, track vehicles), floor-free (e.g., trolley trucks, cranes (e.g., bridge cranes, portal cranes, jib cranes, tower cranes), electric overhead trucks, small container transport systems, fixed objects (e.g., elevators, service lifts and cherry pickers, staged conveyors).

[0032] Storage vessel D may be temperature controllable, movable, insulated or connected to reactor B by a piping system.

[0033] In step 2.1, the pretreated material in reactor B is preferably brought to a temperature of 100 to 1000°C, more preferably 250 to 500°C, particularly preferably 300 to 400°C.

[0034] In optional step 2.2, reactor B is preferably adjusted to a pressure of 0.01 mbar to 100 bar, more preferably 0.01 mbar to 10 bar, particularly preferably 50 mbar to 3 bar. The pressure may be adjusted using an inert gas and / or a reactive gas. The inert gas used may be, for example, hydrogen, helium, neon, argon, krypton, xenon, nitrogen, carbon dioxide or steam, or a mixture thereof, such as forming gas. Argon, nitrogen, or especially hydrogen are preferred.

[0035] The materials may be introduced into reactor B simultaneously or sequentially, for example, by means of a T-piece or upstream mixing block, which may optionally be pre-evacuated.

[0036] In step 2.2, reactor B is preferably first filled with an inert gas or evacuated, in particular before reactor B is filled with the reactive components of steps 2.3 and / or 2.4.

[0037] In optional step 2.3, reactor B is charged with reactive components that do not contain a silicon precursor.

[0038] In step 2.4, reactor B is charged with reactive components including at least one silicon precursor.

[0039] In one variant of the process, the reactive components are introduced into the reactor directly into the bed of porous particles, for example from below or via a special stirrer. This variant is particularly preferred if they are metered into reactor B at a pressure of less than 1 bar before the addition begins.

[0040] Reactor B is preferably filled with reactive components in amounts such that, relative to the amount of porous particles weighed, a sufficient amount of silicon is deposited for the target volume of silicon-containing material to be produced. This can be done in one step or multiple iterations of steps 2.1 to 6.1.

[0041] Charging generally refers to the introduction of reactive components into a reactor. During introduction into the reactor, the components of the reactive components may be present, for example, in gaseous, liquid, or sublimable solid form.

[0042] The reactive component is preferably, for example, gaseous, liquid, solid, sublimable, or optionally a composition of matter of different states of matter.

[0043] The reactive component from step 2.4 comprises at least one silicon precursor and optionally an inert gas component. One or more silicon precursors can generally be introduced into reactor B as a mixture, separately, as a mixture with an inert gas component, or as a pure substance. The reactive component preferably comprises 0 to 99%, more preferably at most 50%, particularly preferably at most 30%, and very preferably at most 5%, of the inert gas component, based on the partial pressure of the inert gas component within the total pressure of the reactive component under standard conditions (according to DIN 1343). In one very preferred embodiment, the reactive component does not contain an inert gas component.

[0044] The silicon precursor comprises at least one reactive component capable of reacting to form silicon under selected conditions, for example, heat treatment. The reactive component is preferably a silicon-hydrogen compound such as monosilane SiH4, disilane Si2H6, and its higher linear, branched, or cyclic homologue, neopentasilane Si5H. 12 , cyclohexasilane Si6H 12chlorine-containing silanes, such as trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and higher linear, branched or cyclic homologues, such as 1,1,2,2-tetrachlorodisilane Cl2HSi-SiHCl2, chlorinated and partially chlorinated oligo- and polysilanes, methylchlorosilanes, such as trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylsilane MeH3Si, chlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or mixtures of the silicon compounds mentioned.

[0045] In one particular embodiment of the present method, monosilane or a mixture of silanes, such as a mixture of monosilane SiH, trichlorosilane HSiCl, dichlorosilane HSiCl, monochlorosilane HSiCl, and tetrachlorosilane SiCl (each component may be present at 0-99.9 wt%), is generated by a suitable process only immediately prior to placement into the reactor. Generally speaking, these processes start with trichlorosilane HSiCl, which is rearranged over a suitable catalyst (e.g., AmberLyst™ A21DRY) to form the other components of the described mixture. The composition of the resulting mixture is primarily determined by workup of the mixture obtained after one or more rearrangement steps at one or more different temperatures.

[0046] Particularly preferred reactive components are monosilanes SiH4, oligomeric or polymeric silanes, especially those of the general formula Si n H n+2 (n may be an integer ranging from 2 to 10), linear silanes of the general formula -[SiH2] n- (where n may include an integer ranging from 3 to 10), trichlorosilane HSiCl3, dichlorosilane H2SiCl2, and chlorosilane H3SiCl, which may be used alone or as a mixture, with highly preferred being SiH4, HSiCl3, and H2SiCl2, used alone or as a mixture.

[0047] Additionally, the reactive components from steps 2.3 and / or 2.4 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 the group including ammonia NH, diborane BH, phosphane PH, germanium GeH, arsane AsH, iron pentacarbonyl Fe(CO), and nickel tetracarbonyl Ni(CO).

[0048] Further reactive constituents which may be present in the reactive component include hydrogen or aliphatic hydrocarbons having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, such as methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane; unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethene, acetylene, propene or butene, isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene; cyclic unsaturated hydrocarbons, such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene; aromatic hydrocarbons, such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane or naphthalene. , other aromatic hydrocarbons such as phenol, o-, m-, p-cresol, cymene, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornane, borneol, isoborneol, bornane, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, bishydroxymethylfuran, and mixed fractions containing many such compounds, such as those from natural gas condensates, crude oil distillates or coking oven condensates, mixed fractions from product streams from fluid catalytic crackers (FCC), steam crackers or Fischer-Tropsch synthesis plants, or very generally hydrocarbon-containing material streams resulting from the processing of wood, natural gas, crude oil, and coal.

[0049] Steps 2.1, 2.2, 2.3, and 2.4 may, but need not, be performed in the order of their numbering, and they may also be performed repeatedly in succession in any desired order.

[0050] In step 3.1, in other words, generally after reactor B is charged with reactive components in step 2.4, reactor B is heated until the target temperature is reached. At the target temperature, decomposition of the silicon precursor begins, and silicon is deposited in the pores and on the surface of the porous particles. The onset of decomposition of the silicon precursor, accompanied by silicon deposition, can be experimentally confirmed by an increase in pressure in reactor B that is not caused by an increase in temperature in reactor B. In the case of decomposition of the silicon precursor, gaseous molecules are generally formed in addition to silicon under reaction conditions, increasing the pressure in reactor B. The volume of reactor B generally remains constant throughout the process.

[0051] Preferably, in step 3.1, the pressure change dp upon heating of the closed reactor B having volume V essentially depends on the temperature change dT, as can be described, for example, by the thermodynamic equation of state according to equation 1:

[0052]

number

[0053] After achieving the target temperature for the decomposition of the silicon precursor in step 3.2, the temperature of step 4.1 in reactor B can, for example, be increased, kept constant, or slightly decreased relative to the target temperature of step 3.1.

[0054] Temperature, pressure or differential pressure measurements in reactor B at all stages can be measured using techniques and equipment common to reactors. Following routine calibration, different measurement devices will give the same results.

[0055] The target temperature is preferably in the range of 250-1000°C, more preferably 300-800°C, and most preferably 300-550°C. For example, for SiH4, the target temperature is preferably between 300-500°C, more preferably in the range of 320-450°C, and very preferably in the range of 320-420°C. The target temperature for HSiCl3 is preferably between 380-1000°C, more preferably in the range of 420-600°C. The target temperature for H2SiCl2 is preferably between 350-800°C, more preferably in the range of 380-500°C.

[0056] If a hydrocarbon containing no silicon precursor is used as an additional reactive component in step 2.3, the target temperature further applied for silicon deposition in step 3.2 and / or during steps 4.1 and 4.2 is the temperature at which decomposition of the hydrocarbon begins and carbon is deposited in the pores and on the surface of the porous particles. In this embodiment, the selected target temperature is preferably in the range of 250 to 1000°C, more preferably 350 to 850°C, and most preferably 400 to 650°C.

[0057] In the process of the invention, the pressure in reactor B during stages 4.1 and 4.2 is increased to at least 7 bar.

[0058] In a preferred embodiment, the progress of reaction during the process is monitored based on pressure change.In this way, it is possible to check, for example, the degree of penetration or the end of penetration.Penetration refers to the deposition of silicon in the pores and on the surface of porous particles in step 4.1 and 4.2.The end of penetration can be measured, for example, by the absence of further pressure increase.

[0059] The pressure change dp in reactor B having volume V between steps 4.1 and 4.2 is generally proportional to the temperature change dT and / or the amount of substance change dn during the deposition of silicon, as represented, for example, by Equation 2: i arises substantially from

[0060]

number

[0061] The pressure change in steps 4.1 and 4.2 is preferably substantially the product of the mass change during the deposition of silicon.Therefore, advantageously, the end of the reaction of the silicon precursor can be recognized from the absence of further pressure increase at the end of steps 4.1 and 4.2, and therefore further steps can be effectively initiated in terms of time without unnecessarily removing unreacted silicon precursor from the reactor, and complete conversion is achieved.

[0062] In one variation of the process in steps 4.1 and 4.2, the temperature is not maintained or increased by external heating. The temperature in steps 4.1 and 4.2 is preferably generated as a result of heat resulting from the possibly exothermic decomposition of the silicon precursor. More preferred is a slight temperature decrease in steps 4.1 and 4.2, more preferably a temperature decrease of up to 20°C during steps 4.1 and 4.2.

[0063] The pressure increase dp in reactor B in steps 4.1 and 4.2 (decomposition of the silicon precursor) is preferably greater than the pressure increase in step 3.1 (heating of the pressure-rated reactor), which is represented, for example, by equation 3a or 3b.

[0064]

number

[0065]

number

[0066] In steps 4.1 and 4.2, the pressure in reactor B preferably reaches at least 10 bar, more preferably at least 50 bar, more preferably at least 100 bar. The pressure in reactor B in steps 4.1 and 4.2 preferably remains below 400 bar, more preferably below 300 bar, particularly preferably below 200 bar.

[0067] The temperature prevailing in reactor B in stages 4.1 and 4.2 is preferably in the range of 100-1000°C, more preferably in the range of 300-900°C, most preferably in the range of 320-750°C.

[0068] The temperature, pressure, pressure change, or differential pressure measurements in reactor B in steps 4.1 and 4.2 can be measured using techniques and equipment common to pressure-rated reactors. Following routine calibration, different measurement devices will produce identical results. The amount of material or change in material amount can be measured by, for example, withdrawing a sample of a predetermined volume from the pressure-rated reactor and measuring its net composition in a conventional manner by gas chromatography.

[0069] The heating of reactor B in step 3.1 and optionally in step 4.1 can be carried out, for example, at a constant heating rate or at several different heating rates.The heating rate can be adapted by those skilled in the art in each individual case according to the process design, for example, according to the size of the reactor, according to the amount of porous particles in the reactor, according to the stirring technique, or according to the planned reaction time.It is preferred that the entire reactor B is heated rapidly in step 3.1, so that, despite the rapid heating, the maximum temperature gradient in reactor B at the temperature at which the decomposition of the silicon precursor begins remains less than 1000 ° C. / min, more preferably less than 100 ° C. / min, and very preferably less than 10 ° C. / min.In this way, it is possible to ensure, for example, that most of the silicon is deposited in the pores of the porous particles, rather than on the outer surface of the porous particles.

[0070] The temperature at which the decomposition of the silicon precursor begins may depend, for example, on the porous particles used, the silicon precursor(s) used, and other boundary conditions of the decomposition, such as the partial pressure of the silicon precursor at the moment of decomposition, and the presence of other reactive components that affect the decomposition reaction, such as a catalyst.

[0071] Heating of reactor B in step 3.1 is preferably carried out at a heating rate of 1 to 100° C. per minute, more preferably at a heating rate of 2 to 50° C. per minute, and very preferably at a heating rate of 3 to 10° C. per minute.

[0072] During the decomposition of the silicon precursor in steps 4.1 and 4.2, the temperature can be kept constant or varied, with the aim being nearly complete conversion of the silicon precursor in the shortest possible time, with the production of usable silicon-containing materials.

[0073] To control the rate of pressure rise at the various stages of operation, various technical solutions can be used. To increase or decrease the pressure rise, the heat supplied to the reactor contents is preferably increased or decreased, respectively. To reduce the rate of pressure rise, it is also preferable to increase the heat removal from reactors B and C by cooling. For this purpose, one or more reactor walls are preferably cooled or equipment for removing heat, such as cooling pipes or cooling ribs, is introduced into the reactors. To control the pressure in the reactors very quickly, it is preferable to feed or remove small amounts of gas from reactor B or C or to feed an evaporating liquid. In this connection, the partial stream removed from reactor B or C is preferably returned completely or partially to the reactor contents again in a closed circuit after cooling and / or removing part of the total stream.

[0074] The course of the reaction in steps 4.1 and 4.2 is preferably monitored analytically in order to recognize the end of the reaction and therefore minimize the reactor occupation time. Methods for observing the course of the reaction include, for example, temperature measurements to measure exothermic or endothermic events, pressure measurements to measure the course of the reaction by changes in the ratio of solid reactor content constituents to gas reactor content constituents, and further techniques that allow observation of changes in the composition of the gas space during the reaction.

[0075] It is preferred to monitor the pressure change in reactor B during the process, in particular the pressure increase, which is an indicator of the deposition rate and therefore the remaining surface area in the porous particles and / or the resulting silicon-containing material.

[0076] In another preferred variant of the process, technological components are used that allow the separation of hydrogen and silane, which can be carried out, for example, via filtration and / or membrane techniques (solution-diffusion model and hydrodynamic model), adsorption, chemisorption, absorption or chemisorption or molecular sieves (e.g., zeolites).

[0077] This component allows step 2.4 to be continuously extended in the case of hydrogen as the gaseous reaction product until the desired amount of silicon is deposited, and step 6.1 can be continuously extended in parallel as well.

[0078] In another preferred variant of the process, reactor B is equipped with technical equipment that serves to remove the condensable or resublimable by-products that occur. In one particularly preferred variant in this regard, silicon tetrachloride is condensed and removed separately from the silicon-containing material.

[0079] In step 5.1, the pressure in reactor B is adjusted by releasing the prevailing pressure, evacuating and / or filling with additional gas, preferably an inert gas, such as hydrogen, helium, neon, argon, krypton, xenon, nitrogen, carbon dioxide or water vapor (hydrogen is particularly preferred), individually or as a mixture.

[0080] In step 5.2, reactor B is adjusted to a predetermined temperature or a predetermined temperature profile is carried out. After the end of deposition, cooling is preferably carried out, optionally to a target temperature, preferably to the temperature of the further steps 2.3 and / or 2.4.

[0081] The order of 5.1 and 5.2 can be chosen arbitrarily. Steps 5.1 and 5.2 may overlap in time in their operation.

[0082] In step 6.1, gaseous by-products of the reaction formed during the deposition process are removed, preferably at the deposition temperature or after reaching a temperature suitable for removing the gaseous by-products from the gas space of reactor B, for example, by purging. It is preferable to use a purge gas. It is preferable to evacuate reactor B at least once before filling it with the purge gas. Preferred purge gases are inert gases, such as hydrogen, helium, neon, argon, krypton, xenon, nitrogen, carbon dioxide, or water vapor, individually or as a mixture, or mixtures thereof with oxygen, such as air or diluted air. The water content of the gas mixture can be adjusted. Then, in step 6.2, the particles obtained from reactor B are transferred either to reactor C or to a suitable storage container. If the particles are transferred to a storage container, they can be transferred directly to reactor C on the container. The transfer in step 6.2 may be carried out by, for example, drop tubes, continuous conveyors, flow conveyors / suction or pressure conveying units (e.g. vacuum conveyors, transport blowers), mechanical conveyors (e.g. roller conveyors with drives, screw conveyors, carousel conveyors, circulating conveyors, bucket units, star wheel locks, chain conveyors, scraper conveyors, belt conveyors, vibrating conveyors), gravity conveyors (e.g. chutes, roller beds, ball beds, rail beds), discontinuous conveyors, floor-based and rail-free (e.g. automated vehicles, manual forklift trucks, electric forklift trucks, dry This can be achieved by means of barless transport systems (DTS), air cushion vehicles, hand carts, electric carts, motor vehicles (tractors, wagons, forklift stackers), transfer carriages, transfer / lift carriages, shelf access devices (with or without converters, capable of following curved paths), floor-based rail-bound (e.g., plant railways, track vehicles), floor-free (e.g., trolley trucks), cranes (e.g., bridge cranes, portal cranes, jib cranes, tower cranes), electric overhead trucks, small container transport systems, fixed objects (e.g., elevators, service lifts and cherry pickers, staged conveyors).

[0083] In step 7.1 of the process, the silicon-containing particles in reactor C can be post-treated and / or passivated. This is preferably carried out by purging reactor C with oxygen, more particularly with a mixture of inert gas and oxygen. In this way, for example, it is possible to modify and / or passivate the surface of the silicon-containing material. For example, it is possible to achieve reaction of any reactive groups present on the surface of the silicon-containing material. For this purpose, a mixture of nitrogen and oxygen, and optionally alcohol and / or water, is preferably used, preferably containing up to 20% by volume, more preferably up to 10% by volume, particularly preferably up to 5% by volume of oxygen, and preferably up to 100% by volume, more preferably up to 10% by volume, particularly preferably up to 1% by volume of water. This step is preferably carried out at a temperature of up to 200°C, more preferably up to 100°C, particularly preferably up to 50°C. The particle surface can also be passivated with a gas mixture containing an inert gas and an alcohol. Here, nitrogen and isopropanol are preferably used. However, it is also possible to use methanol, ethanol, butanol, pentanol, or long-chain and branched alcohols and diols.

[0084] The particles may also be deactivated by dispersion in a liquid solvent or solvent mixture, which may include, for example, isopropanol or an aqueous solution.

[0085] The passivation of the particles in step 7.1 can also be achieved optionally by coating using C, Al and / or B containing precursors at temperatures between 200 and 800°C, optionally followed by treatment in an oxygen-containing atmosphere.

[0086] Aluminum-containing precursors used include, for example, trimethylaluminum ((CH3)3Al), aluminum 2,2,6,6-tetramethyl-3,5-heptanedionate (Al(OCC(CH3)3CHCOC(CH3)3), tris(dimethylamido)aluminum (Al(N(CH3)2)3), and aluminum triisopropoxide (CH21 AlO3).

[0087] The boron-containing precursors used can be, for example, borane (BH3), triisopropylborate ([(CH3)2CHO]3B), triphenylborane ((C6H5)3B), and tris(pentafluorophenyl)borane (C6F5)3B.

[0088] However, in step 7.1 it is also possible to introduce a post-coating of the particles with, for example, a solid electrolyte, for example via CVI deposition from tert-butyllithium and trimethylphosphate.

[0089] In step 7.2 of the present process, in principle, the silicon-containing material is removed from reactor C, optionally while preserving the inert gas atmosphere present in reactor C. This can be achieved, for example, by the following discharge methods: pneumatic (by overpressure or vacuum), mechanical (starwheel lock in the reactor, plate discharge, discharge screw or stirring element, belt discharge) or gravimetric (double flap valve or double ball valve, optionally with vibration assistance).

[0090] In another preferred embodiment of the process, steps 2.1 to 5.2 are repeated one or more times.

[0091] In one preferred embodiment of this process, steps 2.1 to 5.2 are repeated multiple times, and in this case, the silicon precursors charged in each step 2.4 may be the same or different in each case, and a mixture of two or more silicon precursors is also possible. Similarly, the reactive component charge in 2.3 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 steps 2.1 to 5.2, the procedure in reactor B ends with step 6. The order and implementation of steps 2.1 to 6.1 can be modified by those skilled in the art. In this regard, individual steps may be omitted.

[0092] In another preferred embodiment of this process, step 6.1 follows directly from step 4.2, in other words step 5 can be omitted, in other words it is also possible to continue step 6.1 after step 4.2 without cooling reactor B.

[0093] In a further preferred embodiment, steps 2.1 to 6.1 are repeated one or more times (reaction cycle), optionally omitting step 5. In this case, it is also possible to use a silicon-free reactive component in the sense of step 2.3 in each or more repetitions, in which case the silicon-free reactive component in each repetition may be the same or different. The silicon-free reactive component preferably does not contain a silicon precursor. The silicon-free reactive component preferably comprises one or more hydrocarbons. In this preferred embodiment, the silicon-free reactive component may be used in the repetitions of steps 2.1 to 6.1, for example, before or after the deposition of silicon, or between two depositions of silicon. A preferred silicon-free reactive component is a hydrocarbon. When using a silicon-free reactive component, carbon is preferably deposited in the pores and on the surface of the porous particles or silicon-containing material.

[0094] In a particularly preferred embodiment, in the first reaction cycle, in step 2.4, a reactive component containing at least one silicon precursor is charged, and in the second reaction cycle, in step 2.3, a reactive component containing at least one hydrocarbon is charged, and this latter component preferably does not contain silicon, and optionally, step 5 is omitted. By this means, for example, it is possible to obtain a silicon-containing material that does not have a free silicon surface facing outward. The order of 2.3 and 2.4 can be changed.

[0095] Optionally, in the third reaction cycle, in step 2.3, an additional hydrocarbon-containing, silicon-free reactive component is used, and step 5 is optionally omitted. As a result, for example, a silicon-containing material can be obtained that has a carbon layer between the porous particles and the deposited silicon, and optionally also carries an outer carbon layer, meaning that there is no free silicon surface facing outward.

[0096] The preferred silicon-free reactive component is one or more hydrocarbons, the pyrolysis of which generally allows for the deposition of carbon within the pores and on the surfaces of the porous particles. Examples of hydrocarbons are aliphatic hydrocarbons having 1 to 10 carbon atoms, in particular 1 to 6 carbon atoms, preferably methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane and cycloheptane, unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethene, acetylene, propene or butene, isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene, cyclic unsaturated hydrocarbons, such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene, aromatic hydrocarbons, such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane or naphthalene, other aromatic hydrocarbons. aromatic hydrocarbons, such as phenol, o-, m-, p-cresol, cymene, nitrobenzene, chlorobenzene, pyridine, anthracene or phenanthrene, myrcene, geraniol, thioterpineol, norbornane, borneol, isoborneol, bornane, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, bishydroxymethylfuran, and mixed fractions containing many such compounds, such as those from natural gas condensates, crude oil distillates or coking oven condensates, mixed fractions from product streams from fluid catalytic crackers (FCC), steam crackers or Fischer-Tropsch synthesis plants, or very generally hydrocarbon-containing streams resulting from the processing of wood, natural gas, crude oil, and coal.

[0097] The silicon-free reactive component, i.e., the reactive component containing one or more hydrocarbons but not a silicon precursor, preferably does not contain additional components or one or more inert gases and / or one or more reactive components such as hydrogen and / or one or more dopants. The dopant is, for example, a compound containing boron, nitrogen, phosphorus, arsenic, germanium, iron, or nickel. The dopant is preferably selected from the group including ammonia NH3, diborane B2H6, phosphane PH3, germane GeH4, arsane AsH3, and nickel tetracarbonyl Ni(CO)4.

[0098] A temperature-controllable reactor is generally a reactor that can be operated in such a way that the temperature inside the reactor can be established in the range of, for example, −40 to 1000° C. Narrower temperature ranges are possible.

[0099] A vacuum-rated reactor is generally a reactor that can be operated in such a manner that the pressure inside the reactor is less than / equal to the ambient pressure of the reactor.

[0100] A pressure-rated reactor is generally a reactor that can be operated in a manner such that the pressure inside the reactor is greater than / equal to the ambient pressure of the reactor.

[0101] The reactor may simultaneously be temperature adjustable, pressure-rated and vacuum-rated, all combinations being possible, or the reactor may in each case only fulfill one of the above-specified characteristics.

[0102] The minimum reactor requirements used were as follows: - Reactor A: temperature adjustable and vacuum rated - Reactor B: temperature adjustable and pressure rated - Reactor C: Temperature adjustable

[0103] The technical optional features of the individual reactors for this particular variant of the invention are as follows:

[0104] Reactor A: - A system for preheating, drying and inactivating porous particles. - The system can be connected for the specific addition / metering of porous particles (see step 1.1 for technical description). For drying and / or removal of impurities in the porous particles, a system may be connected which allows removal of condensable or resublimable substances. - A system may be connected that allows the porous particles to be transferred to reactor B (for technical description see step 1.3)

[0105] Reactor B: - System for air cooling. - To increase the volume, an additional pressure-rated vessel may be connected, which allows for higher amounts of reactive components in each reaction cycle. This vessel may or may not be heated. Pressure equalization between this vessel and reactor B can be passive (diffusion) or active (facilitated by technical means). - For simplicity of operation, a hydrogen separator may be connected (for technical description see step 3.1). In order to remove condensable or resublimable by-products in the gaseous reaction product, a container may be connected which allows the by-products to be removed by condensation or resublimation. - A system can be connected that allows the material to be transferred to reactor C or to a storage vessel (see step 1.3 for technical description).

[0106] Reactor C - A system for removing condensable or resublimable by-products. A container may be connected that allows the by-products to be removed by condensation or resublimation.

[0107] A cascade reactor system for the purposes of this application is a connection of at least two reactors. There is no upper limit to the number of reactors. The number of reactors A, B, and C relative to each other, as well as their size, shape, material, and configuration, can also be different. A person skilled in the art can adjust the amount of reactors and their size relative to each other in order to make the output of the cascade reactor system as efficient as possible as a whole. The reactors may be directly connected to each other or locally separated from each other, in which case the filling is carried out by a movable storage container. It is also conceivable to connect two or more reactors B to each other and perform each reaction step in an additional reactor B.

[0108] The reactor for the purposes of the present application is preferably a reactor of a type selected from the group comprising tubular reactors, retort kilns, fluidized bed reactors, fixed bed reactors and autoclaves. Particularly preferably, fluidized bed reactors and autoclaves are used, and particularly preferably, autoclaves are used.

[0109] During operation, the porous particles and the resulting silicon-containing material can generally be in the form of a static bed, or can be in the form of agitation while being mixed.Agitation and mixing of the porous particles or the resulting silicon-containing material in reactors A, B and C is preferred.This allows, for example, uniform contact between all porous particles and reactive components, or uniform temperature distribution in the bed.The particles can be agitated, for example, by stirring the inside of the reactor, by moving the entire reactor, or by fluidizing the solids in the reactor with gas flow.

[0110] The types of reactors that can be used for immiscible stationary beds are of any desired geometric shape. Preferred forms of reactor structure are cylindrical, conical, spherical and polyhedral shapes or combinations thereof.

[0111] All forms of reactor construction that allow agitation of the solid beds are preferred in order to mix the beds together in reactors A, B and C. These are, for example, moving reactors, reactors with moving stirring elements or gas traverse reactors, or combinations thereof.

[0112] The form of movement in the moving reactor is preferably rotational. Other forms of movement are equally suitable. Preferred forms of configuration for the rotating reactor are, for example, drum or tubular reactors, conical reactors, double-cone reactors, reactors with offset cones, spherical reactors, polyhedral reactors, V-shaped reactors, double-V-shaped reactors, or geometric combinations thereof. In the case of symmetrical configurations, the axis of rotation preferably lies within the axis of symmetry of the reactor. In the case of asymmetrical configurations, the axis of rotation preferably passes through the center of gravity of the reactor. In another preferred embodiment, the axis of rotation is selected so that a tumbling movement occurs. Mixing events in the moving reactor are preferably enhanced by internal structures. Typical internal structures are guide plates, blades, vanes, and plowshares. According to the invention, the orientation of the axis of rotation is freely selectable here. The axis of rotation is preferably oriented vertically, horizontally, or at any angle relative to the horizontal embodiment. Further preferred forms of structure for mixing the beds together are stationary reactors A, B, and C with moving stirring elements. Preferred geometric shapes for this purpose are cylindrical reactors, conical reactors, spherical reactors, polyhedral reactors, or combinations thereof. The stirring element movement is preferably rotational. Other forms of movement are also suitable. The stirring elements are preferably driven via stirring shafts, and there may be one stirring element or multiple stirring elements per stirring shaft. Reactors A, B, and C preferably incorporate multiple stirring shafts, each of which may have one stirring element or multiple stirring elements. The main reactor axis is preferably aligned horizontally or vertically. In further preferred embodiments, the stirring shafts are installed horizontally or vertically in reactors of any orientation. For vertically operated reactors A, B, and C, preferred configurations are, for example, those in which the stirring element or elements mix the bed material by rotational movement with the main stirring shaft. Furthermore, configurations in which two or more stirring shafts run parallel to each other are preferred. In some preferred configurations, two or more agitator shafts do not operate parallel to one another. Another preferred configuration of vertically operated reactors A, B or C is characterized by the use of a screw conveyor, which preferably transports the bed material centrally.A further design according to the present invention is a screw conveyor that rotates along the edge of the reactor. For horizontally operated reactors A, B, or C, a preferred configuration is, for example, one in which a stirring element or elements mix the bed material by rotational movement with the main stirring shaft. Configurations in which two or more stirring shafts run parallel are also possible. Even more preferred are configurations in which two or more stirring shafts do not run parallel to each other. For vertically operated reactors A, B, or C, preferred stirring elements are elements selected from the group including helical stirrers, spiral stirrers, anchor stirrers, or generally stirring elements that convey bed material axially or radially, or both axially and radially. For horizontally operated reactors A, B, or C, multiple stirring elements on one shaft are preferred. Configurations according to the present invention for stirring elements in horizontally operated reactors are plowshares, paddles, blade stirrers, spiral stirrers, or generally stirring elements that convey bed material both axially and radially. In addition to the moving stirring elements, rigid internal structures such as guide plates are also preferred for the stationary reactors A, B or C with moving stirring elements. Particularly preferred are configurations in which both the reactor and the stirring elements rotate.

[0113] As a further possibility for mixing, the bed of material is preferably exposed to a gas flow. Particularly preferred here are constructions such as fluidized bed reactors. Even more preferred are reactors A, B or C in which a mixing zone is intentionally introduced into the reactor by using air pressure.

[0114] In principle, any material is suitable for constructing reactors A, B, or C for carrying out the process of the present invention, provided that it has the necessary mechanical strength and chemical resistance under the respective operating conditions. With regard to chemical resistance, reactors A, B, or C can be made of corresponding solid materials as well as chemically impervious materials (pressure-resistant) with specific coatings or platings on the parts in contact with the medium.

[0115] These materials are selected according to the invention from the group comprising:

[0116] - metallic materials corresponding to (according to DIN CEN ISO / TR 15608) material groups 1 to 11 steels, groups 31 to 38 nickel and nickel alloys, groups 51 to 54 titanium and titanium alloys, groups 61 and 62 zirconium and zirconium alloys, and groups 71 to 76 cast irons;

[0117] - ceramic materials, including oxide ceramics in single-substance systems, such as aluminum oxide, magnesium oxide, zirconium oxide, titanium dioxide (capacitor materials), and multi-substance systems, such as aluminum titanate (a mixed form of aluminum oxide and titanium oxide), mullite (a mixed form of aluminum oxide and silicon oxide), lead zirconate titanate (piezoelectric ceramics), or dispersed ceramics such as aluminum oxide reinforced with zirconium oxide (ZTA - Zirconia reinforced aluminum oxide) - Al2O3 / ZrO2);

[0118] non-oxide ceramics, such as carbides, e.g. silicon carbide and boron carbide, nitrides, e.g. silicon nitride, aluminum nitride, boron nitride and titanium nitride, borides and silicides, and mixtures thereof;

[0119] - composite materials belonging to the group of granular composites, such as, for example, cemented carbide, ceramic composites, concrete and polymer concrete, fibre composites, such as, for example, glass fibre reinforced glass, metal matrix composites (MMC), fibre cement, carbon fibre reinforced silicon carbide, self-reinforced thermoplastics, steel reinforced concrete, fibre reinforced concrete, fibre plastic composites, such as, for example, carbon fibre reinforced plastics (CRP), glass fibre reinforced plastics (GRP) and aramid fibre reinforced plastics (ARP), fibre-ceramic composites (ceramic matrix composites (CMC)), interpenetrating composites, such as, for example, metal matrix composites (MMC), dispersion reinforced aluminium alloys or dispersion hardened nickel-chromium superalloys, layered composites, such as, for example, bimetals, titanium-graphite composites, composite plates and tubes, glass fibre reinforced aluminium and sandwich structures, and structural composites.

[0120] The method of the present invention for producing silicon-containing materials offers various decisive advantages over the prior art. A particular advantage is the possibility of complete conversion of the silicon precursor in a short reaction time, aided, for example, by the absence of a pressure increase related solely to temperature during step 4. Another advantage is the possibility of reducing the amount of inert gas or completely avoiding it, which in turn leads to a higher space / time yield and thus allows for more rapid and uniform deposition of the desired layer on the substrate. Furthermore, continuous recycling or disposal of reactor off-gas, as typically occurs in open reactor operation, can be avoided. The described implementation in a sealable reactor also facilitates multiple depositions from the same or different reactive components, with precisely adjustable amounts of deposition product based on the reactants in each deposition step. Therefore, the silicon-containing materials obtained from the method of the present invention are also distinguished by the advantageous homogeneity of the deposited layers. As a result of the advantages of the method of the present invention, silicon-containing materials are advantageously available quickly and economically, particularly for use as active materials for the anodes of lithium-ion batteries with excellent properties. Another particular advantage is the ability to avoid the often-described dusting problem. This can be achieved, for example, by the large surface area of ​​the porous particles that are made available for silicon deposition from the silicon precursor, and by the strong penetration of the porous particles by the silicon precursor. At the same time, a high yield of deposited silicon is obtained in this way. In contrast to the variant in which all reaction steps are carried out in the same reactor (see counterexample 2), the cascade reactor offers the following advantages: - Energy savings through reduction of cooling and heating operations involving large temperature differences. - Capital cost savings through precise design of each reactor to the requirements of the specific operating process. - The high level of modularity offers wide opportunities for adaptation to different volume requirements and operating parameters. - The possibility to combine different reactors A, B and C in different sizes and numbers reduces the risk of complete breakdown and makes downtime planning possible for necessary modifications. - The modular configuration allows minor maintenance work to be carried out on one reactor while the other reactors are still operating.

[0121] The porous particles for the process of the present invention are preferably selected from the group comprising hard carbon, soft carbon, mesocarbon microbeads, natural or synthetic graphite, amorphous carbon in the form of single-walled and multi-walled carbon nanotubes and graphene, oxides such as silicon dioxide, aluminum oxide, mixed silicon oxide-aluminum oxide, magnesium oxide, lead oxide and zirconium oxide, carbides such as silicon carbide and boron carbide, nitrides such as silicon nitride and boron nitride, and other ceramic materials, as may be described by the following formula:

[0122] Al where 0≦a, b, c, d, e, f, g≦1 and at least two coefficients a~g>0 and a×3+b×3+c×4+d×2+g×4≧e×3+f×2 a B b C c Mg d N e O f Si g .

[0123] The ceramic material can be, for example, a binary, ternary, quaternary, pentanary, hexanary, or heptanary compound. Preferred ceramic materials are those having the following formula:

[0124] Non-stoichiometric boron nitride BN z At z=0.2~1, Non-stoichiometric carbon nitride CN z At z=0.1~4 / 3, Boron carbonitride B x CN z where x=0.1~20 and z=0.1~20, x×3+4≧z×3, Boron nitridoxide (BN) z O r where z=0.1~1 and r=0.1~1, 3≧r×2+z×3, Boron Carbonitride Oxide B x CN z O r where x=0.1~2, z=0.1~1 and r=0.1~1, x×3+4≧r×2+z×3, Silicon carboxylate Si x CO z where x=0.1~2 and z=0.1~2, x×4+4≧z×2, Silicon carbonitride Si x CN z where x=0.1~3 and z=0.1~4, x×4+4≧z×3, Silicon borocarbonitride Si w B x CN z In this case, w=0.1~3, x=0.1~2, z=0.1~4, w×4+x×3+4≧z×3, Silicon borocarboxide (Si) w B x CO z In this case, w=0.10~3, x=0.1~2 and z=0.1~4, and w×4+x×3+4≧z×2. Silicon borocarbonitridooxide (Si) v B w CN x O z where v=0.1~3, w=0.1~2, x=0.1~4 and z=0.1~3, v×4+w×3+4≧x×3+z×2, and Aluminum borosilicocarbonitridooxide (Al) u B v Si x CN w O zIn this case, u=0.1~2, v=0.1~2, w=0.1~4, x=0.1~2 and z=0.1~3, and u×3+v×3+x×4+4≧w×3+z×2.

[0125] Porous particles have a particle size of 0.1-7 g / cm as measured by helium pycnometry. 3 , more preferably 0.3 to 3 g / cm 3 This is in line with the gravimetric capacity (mAh / cm) of a lithium-ion battery. 3 ) is advantageous in increasing the

[0126] Preferred porous particles used are amorphous carbon, silicon dioxide, boron nitride, silicon carbide and silicon nitride or mixed materials based on these materials, with the use of amorphous carbon, boron nitride and silicon dioxide being particularly preferred.

[0127] The porous particles preferably have a diameter percentile d of 0.5 μm or more, more preferably 1.5 μm or more, and most preferably 2 μm or more. 50 The diameter percentile d 50 is preferably 20 μm or less, more preferably 12 μm or less, and most preferably 8 μm or less.

[0128] The volume-weighted particle size distribution of the porous particles is preferably determined by the diameter percentile d 10 ≧0.2μm~d 90 ≦20.0 μm, more preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0129] The porous particles preferably have a diameter percentile d of 10 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less, and most preferably 2 μm or less. 10 The diameter percentile d 10is preferably 0.2 μm or more, more preferably 0.5 μm or more, and most preferably 1 μm or more.

[0130] The porous particles preferably have a diameter percentile d of 4 μm or more, more preferably 8 μm or more. 90 The diameter percentile d 90 is preferably 18 μm or less, more preferably 15 μm or less, and most preferably 13 μm or less.

[0131] The volume-weighted particle size distribution of the porous particles preferably has a span d of 15.0 μm or less, more preferably 12.0 μm or less, very preferably 10.0 μm or less, especially preferably 8.0 μm or less, and most preferably 4.0 μm or less. 90 -d 10 It has.

[0132] The volume weighted particle size distribution of the silicon-containing material producible by the process of the present invention preferably has a span d of 0.6 μm or more, more preferably 0.8 μm or more, and most preferably 1.0 μm or more. 90 -d 10 It has.

[0133] The volume weighted particle size distribution of porous particles can be measured according to ISO 13320 by static laser scattering method using Mie model with Horiba LA 950 measuring equipment, using ethanol as the dispersion medium of the porous particles.

[0134] The porous particles are preferably present in the form of particles. The particles may be, for example, isolated or agglomerated. The porous particles are preferably not agglomerated, and preferably not agglomerated. Agglomerated generally means that during the production of the porous particles, primary particles are first formed and then fuse together and / or the primary particles bond to each other, for example, via covalent bonds, thus forming aggregates. The primary particles are usually isolated particles. The agglomerates or isolated particles may form agglomerates. Agglomerates are loose combinations of agglomerates or primary particles connected to each other, for example, via van der Waals interactions or hydrogen bonds. Agglomerated agglomerates can be easily broken back into agglomerates by conventional kneading and dispersion techniques. Agglomerates cannot be broken down into primary particles by these techniques, or can only be partially broken down. The presence of porous particles in the form of agglomerates, agglomerates, or isolated particles can be visualized, for example, by conventional scanning electron microscopy (SEM). Static light scattering methods for measuring particle size distribution or particle size of matrix particles, in contrast, cannot distinguish between agglomerates or agglomerates.

[0135] The porous particles may have any desired morphology, and thus may be, for example, sputtery, plate-like, spherical, or acicular, with sputtery or spherical particles being preferred. The morphology can be characterized, for example, by the sphericity ψ or sphericity S. According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the body. For a sphere, the value of ψ is 1. According to this definition, the porous particles for the method of the present invention preferably have a sphericity ψ of 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0136] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle on the surface to the measured circumference U of this projection,

[0137]

number

[0138] The porous particles are preferably 0.2 cm 3 / g or more, more preferably 0.6 cm 3 / g or more, most preferably 1.0 cm 3 / g or more, which is useful for obtaining high-capacity lithium-ion batteries. The gas-accessible pore volume was determined by gas sorption measurements with nitrogen according to DIN 66134.

[0139] The porous particles are preferably open-pore. Open pore generally means that the pores are connected to the particle surface, for example, via channels, and are preferably in a state of mass transfer with the surroundings, in particular in a state of gaseous compound transfer. This can be verified using gas sorption measurements (evaluation according to Brunauer, Emmett and Teller, "BET"), i.e., specific surface area. The porous particles are preferably 50 m 2 / g or more, more preferably 500m 2 / g or more, most preferably 1000m 2 / g or more. The BET specific surface area is determined in accordance with DIN 66131 (including nitrogen).

[0140] The pores of the porous particles can have any desired diameter, i.e., diameters generally ranging from macropores (greater than 50 nm), mesopores (2-50 nm), and micropores (less than 2 nm). Porous particles can be used in any desired mixture of different pore types. Preferably, porous particles are used that have less than 30% macropores, based on the total pore volume, more preferably no macropores, and very preferably at least 50% of the pores have an average pore diameter of less than 5 nm. Very particularly preferably, the porous particles contain only pores with a pore diameter of less than 2 nm (measurement method: pore size distribution according to BJH (gas adsorption) in the mesopore range according to DIN 66134 and Horvath-Kawazoe (gas adsorption) in the micropore range according to DIN 66135; evaluation of the pore size distribution in the macropore range is carried out by mercury porosimetry in accordance with DIN ISO 15901-1).

[0141] The preferred porous particles are 0.3 cm 3 / g, more preferably less than 0.15 cm 3 The gas inaccessible pore volume is less than 1 / g. This can also increase the capacity of lithium ion batteries. The gas inaccessible pore volume can be measured by the following formula: Gas inaccessible pore volume = 1 / density of pure material - 1 / skeletal density.

[0142] Here, the pure material density is the theoretical density of the porous particles based on the phase composition or the density of the pure material (the density of the material as if it had no closed pores). Data on the pure material density can be found by those skilled in the art, for example, in the Ceramic Data Portal of the National Institute of Standards (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the pure material density of silicon oxide is 2.203 g / cm 3 The density of pure boron nitride is 2.25 g / cm 3 The density of pure silicon nitride is 3.44 g / cm 3The density of pure silicon carbide is 3.21 g / cm 3 Skeletal density is the actual density of the porous particles (gas accessible) measured by helium pycnometry.

[0143] For clarity, it should be noted that porous particles are different from silicon-containing materials.Porous particles serve as the starting material for producing silicon-containing materials.Generally, it is preferred that there is no silicon located in the pores and on the surface of porous particles, and more specifically, there is no silicon obtained by depositing silicon precursor.

[0144] The silicon-containing material obtained by the method of the present invention by deposition of silicon in the pores and on the surface of porous particles preferably has a diameter percentile d in the range of 0.5 to 20 μm. 50 The particle size distribution has a volume weighted value of d 50 A value of at least 1.5 μm is preferred, and at least 2 μm is more preferred. Diameter percentile d 50 is preferably at most 13 μm, more preferably at most 8 μm.

[0145] The volume weighted particle size distribution of the silicon-containing material is preferably determined by the diameter percentile d 10 ≧0.2μm~d 90 ≦20.0 μm, more preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0146] The silicon-containing material preferably has a diameter percentile d of 10 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less, and most preferably 1 μm or less. 10 The diameter percentile d 10 is preferably 0.2 μm or more, more preferably 0.4 μm or more, and most preferably 0.6 μm or more.

[0147] The silicon-containing material preferably has a diameter percentile d of 5 μm or more, more preferably 10 μm or more. 90 The diameter percentile d 90 is preferably 20 μm or less, more preferably 15 μm or less, and most preferably 12 μm or less.

[0148] The volume weighted particle size distribution of the silicon-containing material preferably has a span d of 15.0 μm or less, more preferably 12.0 μm or less, more preferably 10.0 μm or less, particularly preferably 8.0 μm or less, and most preferably 4.0 μm or less. 90 -d 10 The volume weighted particle size distribution of the silicon-containing material preferably has a span d of 0.6 μm or more, more preferably 0.8 μm or more, and most preferably 1.0 μm or more. 90 -d 10 It has.

[0149] The particles of silicon-containing material are preferably in the form of particles.Particles can be isolated or agglomerated.The silicon-containing material is preferably not agglomerated, and preferably not agglomerated.The terms isolated, agglomerated and not agglomerated have already been defined above in relation to porous particles.The existence of the silicon-containing material in the form of agglomerates or agglomerates can be visualized, for example, by conventional scanning electron microscope (SEM).

[0150] The silicon-containing material may have any desired morphology, and thus may be, for example, sputtered, plate-like, spherical or acicular, with sputtered or spherical particles being preferred.

[0151] 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 body. For a sphere, the value of ψ is 1. According to this definition, the silicon-containing material usable by the method of the present invention preferably has a sphericity ψ of 0.3 to 1.0, more preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0152] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle on the surface to the measured circumference U of this projection,

[0153]

number

[0154] The cycling stability of lithium-ion batteries can be further enhanced by the morphology, material composition, and especially the specific surface area or internal porosity of silicon-containing materials.

[0155] The silicon-containing material preferably contains 10 to 90 wt. %, more preferably 20 to 80 wt. %, very preferably 30 to 60 wt. %, and particularly preferably 40 to 50 wt. % of porous particles, based on the total weight of the silicon-containing material.

[0156] The silicon-containing material preferably contains 10 to 90 wt. %, more preferably 20 to 80 wt. %, very preferably 30 to 60 wt. %, and particularly preferably 40 to 50 wt. % of silicon obtained by deposition from a silicon precursor, based on the total weight of the silicon-containing material (preferably measured by elemental analysis such as ICP-OES).

[0157] When the porous particles contain a silicon compound in the form of silicon dioxide, for example, the above-mentioned weight percent value of silicon obtained through deposition from a silicon precursor can be determined by subtracting the mass of silicon in the porous particles confirmed by elemental analysis from the mass of silicon in the silicon-containing material confirmed by elemental analysis, and dividing the result by the mass of the silicon-containing material.

[0158] The volume of silicon contained in the silicon-containing material and obtained via deposition from a silicon precursor is determined by the density of silicon (2.336 g / cm 3 is the result of the mass fraction of silicon obtained via deposition from a silicon precursor as a percentage of the total mass of silicon-containing material divided by the mass fraction of silicon-containing material.

[0159] The pore volume P of a silicon-containing material is the sum of the gas-accessible pore volume and the gas-inaccessible pore volume. The gas-accessible pore volume of a silicon-containing material can be measured by nitrogen gas sorption measurement according to DIN 66134.

[0160] The gas inaccessible pore volume of a silicon-containing material can be measured using the following equation: Gas inaccessible pore volume = 1 / skeletal density - 1 / density of pure material.

[0161] Here, the pure material density of the silicon-containing material is the theoretical density that can be calculated by multiplying the sum of the theoretical pure material densities of the components contained in the silicon-containing material by their respective weight-based proportions in the whole material.Therefore, for example, in the case of a silicon-containing material in which silicon is deposited on porous particles, Pure material density = theoretical pure material density of silicon x percentage of silicon expressed in weight % + theoretical pure material density of porous particles x percentage of porous particles expressed in weight %.

[0162] Data regarding pure material density can be obtained by those skilled in the art, for example, from the Ceramic Data Portal of the National Institute of Standards (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the pure material density of silicon oxide is 2.203 g / cm. 3 The density of pure boron nitride is 2.25 g / cm 3 The density of pure silicon nitride is 3.44 g / cm 3 The density of pure silicon carbide is 3.21 g / cm 3 is.

[0163] The pore volume P of the silicon-containing material is preferably in the range of 0 to 400 vol%, more preferably in the range of 100 to 350 vol%, and particularly preferably in the range of 200 to 350 vol%, based on the volume of silicon contained in the silicon-containing material and obtained from the deposition of the silicon precursor.

[0164] The pores contained in the silicon-containing material may be either gas-accessible or gas-inaccessible. The volume ratio of gas-accessible pores to gas-inaccessible pores in the silicon-containing material can generally be in the range of 0 (no gas-accessible pores) to 1 (all pores are gas-accessible). The volume ratio of gas-accessible pores to gas-inaccessible pores in the silicon-containing material is preferably in the range of 0 to 0.8, more preferably in the range of 0 to 0.3, and particularly preferably in the range of 0 to 0.1.

[0165] The pores of the silicon-containing material can have any desired diameter, for example, within the range of macropores (greater than 50 nm), mesopores (2-50 nm), and micropores (less than 2 nm). The silicon-containing material can also contain any desired mixture of different pore types. The silicon-containing material preferably contains up to 30% macropores based on the total pore volume, particularly preferably a silicon-containing material without macropores, and very particularly preferably a silicon-containing material with at least 50% pores based on the total pore volume and an average pore diameter of less than 5 nm. More particularly preferably, the silicon-containing material only has pores with a diameter of up to 2 nm.

[0166] The silicon-containing material comprises silicon structures having a structure size in at least one dimension of preferably up to 1000 nm, more preferably less than 100 nm, very preferably less than 5 nm (measurement method: scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)).

[0167] The silicon-containing material preferably comprises a silicon layer having a layer thickness of less than 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (measurement method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The silicon-containing material may also comprise silicon in the form of particles. The silicon particles preferably have a diameter of at most 1000 nm, more preferably less than 100 nm, and very preferably less than 5 nm (measurement method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The numerical value of the silicon particles here is preferably based on the diameter of the circle around the particle in the microscope image.

[0168] The silicon-containing material is preferably up to 100 m 2 / g, more preferably 30m 2 / g, particularly preferably less than 10m 2 / g。 The BET specific surface area is measured in accordance with DIN 66131 (by nitrogen). Therefore, when the silicon-containing material is used as an active material for the anode of a lithium-ion battery, SEI formation can be reduced and the initial coulombic efficiency can be increased.

[0169] The silicon in the silicon-containing material deposited from the silicon precursor may further comprise a dopant selected from the group including, for example, Li, Fe, Al, Cu, Ca, K, Na, S, Cl, Zr, Ti, Pt, Ni, Cr, Sn, Mg, Ag, Co, Zn, B, P, Sb, Pb, Ge, Bi, rare earths, or combinations thereof. Lithium and / or tin are preferred. The amount of dopant in the silicon-containing material is preferably at most 1 wt. %, more preferably at most 100 ppm, based on the total weight of the silicon-containing material, and can be measured by ICP OES.

[0170] Silicon-containing materials generally have surprisingly high stability under compressive load and / or shear load.The pressure stability and shear stability of silicon-containing materials are revealed, for example, by the absence or substantial absence of change in the porous structure of silicon-containing materials under compressive load (for example, when compressing an electrode) and shear load (for example, when preparing an electrode) in SEM.

[0171] The silicon-containing material may optionally further comprise an element such as carbon. The carbon is preferably present in the form of a thin layer having a layer thickness (measurable by SEM or HR TEM) of at most 1 μm, preferably less than 100 nm, more preferably less than 5 nm, and very preferably less than 1 nm. These carbon layers may be present both in the pores and on the surface of the silicon-containing material. The order and number of different layers in the silicon-containing material through the corresponding repetition of steps 2.1 to 6.1 are also arbitrary. Thus, first, there may be a layer of an additional material different from the porous particles, such as carbon, on the porous particles, which may comprise a silicon layer or a layer of silicon particles. It is also possible that there is a layer of an additional material on the silicon layer or layer of silicon particles, which may be different from or the same as the material of the porous particles, regardless of whether there is a layer of an additional material different from the material of the porous particles between the porous particles and the silicon layer or layer consisting of silicon particles.

[0172] The silicon-containing material preferably contains 50% by weight or less, more preferably 40% by weight or less, particularly preferably 20% by weight or less of additional elements.The silicon-containing material preferably contains 1% by weight or more, more preferably 3% by weight or more, particularly preferably 2% by weight or more of additional elements.The values ​​expressed in weight percent are based on the total weight of the silicon-containing material.In an alternative embodiment, the silicon-containing material does not contain additional elements.

[0173] Further subject matter of the present invention is the use of a silicon-containing material as an active material in an anode material for an anode of a lithium-ion battery, and the use of such an anode for producing a lithium-ion battery.

[0174] The anode material is preferably based on a mixture comprising a silicon-containing material accessible by the method of the present invention, one or more binders, optionally graphite as a further active material, optionally one or more further conductive components, and optionally one or more additives.

[0175] The use of an additional conductive component in the anode material can reduce the contact resistance within the electrode and between the electrode and the current collector, thereby improving the current-carrying capacity of the lithium-ion battery of the present invention. Examples of preferred additional conductive components are conductive carbon black, carbon nanotubes, or metal particles, such as copper.

[0176] The primary particles of the conductive carbon black preferably have a diameter percentile d 10 =5nm~d 90 = 200 nm. The primary particles of conductive carbon black may also have chain-like branches and form structures up to μm in size. The carbon nanotubes preferably have diameters of 0.4 to 200 nm, more preferably 2 to 100 nm, and most preferably 5 to 30 nm. The metal particles preferably have a diameter percentile d 10 =5nm~d 90 = 800 nm.

[0177] The anode material preferably comprises 0 to 95 wt %, more preferably 0 to 40 wt %, and most preferably 0 to 25 wt %, of one or more further conductive components, based on the total weight of the anode material.

[0178] In the anode of a lithium ion battery, the silicon-containing material may be present in an amount of preferably 5 to 100 wt %, more preferably 30 to 100 wt %, and most preferably 60 to 100 wt %, based on the total active material present in the anode material.

[0179] Preferred binders are polyacrylic acid or its alkali metal salts, more specifically lithium or sodium salts, polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, particularly polyamideimides, or thermoplastic elastomers, particularly ethylene-propylene-diene terpolymers. Particularly preferred are polyacrylic acid, polymethacrylic acid, or cellulose derivatives, particularly carboxymethylcellulose. Also particularly preferred are alkali metal salts of the binders, particularly lithium or sodium salts. Most preferred are alkali metal salts of polyacrylic acid or polymethacrylic acid, particularly lithium or sodium salts. All or, preferably, a portion of the acid groups of the binder may be present in the form of a salt. The binder preferably has a molar mass of 100,000 to 1,000,000 g / mol. A mixture of two or more binders may also be used.

[0180] Generally, natural or synthetic graphite can be used as the graphite. The graphite particles preferably have a diameter percentile d 10 >0.2μm~d 90 <200 μm.

[0181] Examples of additives are pore formers, dispersants, flow control agents or dopants, such as elemental lithium.

[0182] A preferred formulation for the anode material preferably comprises 5 to 95 wt. %, more particularly 60 to 90 wt. % silicon-containing material, 0 to 90 wt. %, more particularly 0 to 40 wt. % further conductive component, 0 to 90 wt. %, more particularly 5 to 40 wt. % graphite, 0 to 25 wt. %, more particularly 5 to 20 wt. % binder, and 0 to 80 wt. %, more particularly 0.1 to 5 wt. % additive, the figures expressed in wt. % being based on the total weight of the anode material, and the percentages of all components of the anode material adding up to 100 wt. %.

[0183] The components of the anode material that make up the anode ink or anode paste are preferably processed in a solvent preferably selected from the group including water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide and ethanol, and mixtures of these solvents, preferably using a rotor-stator machine, a high-energy mill, a planetary kneader, an agitator ball mill, a shaker plate or an ultrasonic device.

[0184] The anode ink or anode paste preferably has a pH of 2 to 7.5 (measured, for example, at 20° C. using a WTW pH340i pH meter equipped with a SenTix RJD probe).

[0185] The anode ink or anode paste can be applied, for example, to a copper foil or another current collector by a doctor blade. Other coating methods, such as spin coating, roller coating, dip or slot die coating, painting or spraying, can also be used in accordance with the present invention.

[0186] Prior to coating the copper foil with the anode material of the present invention, the copper foil may be treated with a commercially available primer, for example, based on a polymer resin or silane, which can provide improved adhesion to the copper but which generally has no substantial electrochemical activity itself.

[0187] The anode material is usually dried to a constant weight. The drying temperature depends on the components and solvent used. It is preferably between 20 and 300°C, more preferably between 50 and 150°C. The layer thickness, meaning the dry layer thickness of the anode coating, is preferably between 2 and 500 μm, more preferably between 10 and 300 μm.

[0188] Finally, the electrode coating may be calendered to set a predetermined porosity. The electrode thus produced preferably has a porosity of 15 to 85%, which can be measured by mercury porosimetry according to DIN ISO 15901-1. Preferably, 25 to 85% of the pore volume thus determined is provided by pores with diameters of 0.01 to 2 μm.

[0189] A further subject of the present invention is a lithium-ion battery comprising a cathode, an anode, two electrically conductive connections to these electrodes, a separator, an electrolyte in which the separator and the two electrodes are impregnated, and a casing containing the above components, the anode comprising a silicon-containing material obtainable according to the method of the present invention.

[0190] In the context of the present invention, the term lithium-ion battery also encompasses cells. A cell generally comprises a cathode, an anode, a separator, and an electrolyte. In addition to one or more cells, a lithium-ion battery preferably further comprises a battery management system. The battery management system generally serves to control the battery, for example by means of electronic circuits, in particular to recognize the state of charge, to protect against deep discharge, or to protect against overcharging.

[0191] Preferred cathode materials that can be used in accordance with the present invention include lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide (doped or undoped), lithium manganese oxide (spinel), lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium vanadium phosphate, or lithium vanadium oxide.

[0192] The separator is generally an electrically insulating, ion-permeable membrane, preferably made of polyolefin, such as polyethylene (PE) or polypropylene (PP), or polyester, or a corresponding laminate. Alternatively, as is customary in battery manufacturing, the separator may consist of or be coated with a glass or ceramic material. The separator traditionally separates the first electrode from the second electrode, thus preventing a conductive connection (short circuit) between the electrodes.

[0193] The electrolyte is preferably a solution containing one or more lithium salts (=conductive salts) in an aprotic solvent. The conductive salts are preferably selected from the group consisting of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium imide, lithium methide, lithium trifluoromethanesulfonate LiCF3SO3, lithium bis(trifluoromethanesulfonimide) LiN(CF3SO2)2, and lithium borate. The concentration of the conductive salt, based on the solvent, is preferably from 0.5 mol / L to the solubility limit of the salt in question. More preferably, the concentration of the conductive salt is from 0.8 to 1.2 mol / L.

[0194] The solvents used are preferably, individually or as mixtures, cyclic carbonates, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethoxyethane, diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, gamma-butyrolactone, dioxolane, acetonitrile, organic esters of carbonic acid, or nitriles.

[0195] The electrolyte preferably contains a film-forming agent, such as vinylene carbonate or fluoroethylene carbonate. In this way, it is possible to achieve a significant improvement in the cycling stability of anodes containing silicon-containing materials obtained according to the method of the present invention. This improvement is primarily due to the formation of a solid electrolyte interface on the surface of the active particles. The proportion of the film-forming agent in the electrolyte is preferably between 0.1 and 20.0 wt %, more preferably between 0.2 and 15.0 wt %, and most preferably between 0.5 and 10 wt %.

[0196] To best match the actual capacities of the electrodes in a lithium-ion battery, it is advantageous to quantitatively balance the materials in the positive and negative electrodes. Of particular importance in this context is the fact that during the first or initial charge / discharge cycle (known as activation) of a secondary lithium-ion cell, a coating layer forms on the surface of the electrochemically active material in the anode. This coating layer, called the solid electrolyte interface (SEI), generally consists primarily of electrolyte decomposition products and a certain amount of lithium, which is therefore no longer available for further charge / discharge reactions. The thickness and composition of the SEI depend on the anode material used and the nature and quality of the electrolyte solution used.

[0197] In the case of graphite, the SEI is particularly thin. Graphite typically loses 5-35% of its mobile lithium during the first charging step, with a corresponding decrease in the reversible capacity of the battery.

[0198] For anodes having a silicon-containing active material obtained by the method of the present invention, the first charging step is preferably accompanied by a loss of mobile lithium of at most 30%, more preferably at most 20%, and most preferably at most 10%, which is much lower than the values ​​described in the prior art, e.g., in US Pat. No. 1,014,790 B1.

[0199] Lithium ion batteries whose anodes comprise silicon-containing materials obtainable by the method of the present invention can be produced in all customary forms, such as wound, folded or stacked forms.

[0200] All of the substances and materials utilized in the manufacture of such lithium-ion batteries are known, and the manufacture of the components of such batteries and their assembly to obtain batteries is carried out according to methods known in the art of battery manufacturing.

[0201] The silicon-containing materials obtained by the method of the present invention are notable for their significantly improved electrochemical properties, resulting in lithium-ion batteries with high volumetric capacity and excellent performance characteristics. The silicon-containing materials obtained by the method of the present invention are permeable to lithium ions and electrons, thus enabling charge transport. The SEI in lithium-ion batteries can be significantly reduced by the silicon-containing materials obtained by the method of the present invention. Furthermore, due to the design of the silicon-containing materials obtained by the method of the present invention, the peeling of the SEI from the surface of the active material no longer exists or is at least significantly reduced. All of this results in high cycle stability in those lithium-ion batteries whose anodes contain silicon-containing materials obtainable by the method of the present invention. [Example]

[0202] The following examples serve to further elucidate the invention described herein.

[0203] The analytical methods and instruments used for measuring the properties were as follows:

[0204] Inorganic analysis / elemental analysis: The C content reported in the examples was confirmed using a Leco CS230 analyzer. A Leco TCH-600 analyzer was used to measure the O content and, where appropriate, the N and H content. Qualitative and quantitative determination of other reported elements was performed by ICP (inductively coupled plasma) optical emission spectroscopy (Optima 7300 DV, Perkin Elmer). For this analysis, samples were subjected to acid digestion (HF / HNO3) in a microwave (icrowave 3000, Anton Paar). ICP-OES measurements are guided by ISO 11885 (Water quality - Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885:2007), German translation EN ISO 11885:2009), which is used for the analysis of acidic aqueous solutions (e.g., drinking water, acidified samples of wastewater and other waters, aqua regia extracts of soils and sediments).

[0205] Particle size measurement: In the context of the present invention, particle size distribution was measured in accordance with ISO 13320 by static laser scattering using a Horiba LA 950. Particular attention must be paid to the dispersion of particles in the measurement solution during sample preparation, to avoid measuring the size of weak agglomerates rather than individual particles. For the measurement, the particles were dispersed in ethanol. For this purpose, the dispersion was treated with 250 W ultrasound for 4 minutes in a Hielscher model UIS250v ultrasonic laboratory instrument equipped with an LS24d5 sonotrode, if necessary, prior to measurement.

[0206] BET specific surface area measurement: The specific surface area of ​​the materials was measured by gas adsorption with nitrogen by the BET method (measurement in accordance with DIN ISO 9277:2003-05 with nitrogen) using a Sorptomatic 199090 instrument (Porotec) or a SA-9603MP instrument (Horiba).

[0207] Bone Density: The skeletal density, i.e. the density of the porous solid based on the volume of the pore space only accessible to gas from the outside, was determined by He pycnometry in accordance with DIN 66137-2.

[0208] Gas accessible pore volume: The gas-accessible pore volume of Gurwitsch was determined by gas sorption measurements with nitrogen according to DIN 66134.

[0209] The materials and equipment used in carrying out the experimental examples were as follows:

[0210] The reactors A, B, and C used consisted of a cylindrical lower part (beaker) and a lid with numerous connections (e.g., gas supply, gas removal, temperature measurement, and pressure measurement). The volume of each of the three reactors was 12 liters. The reactors were electrically heated. The temperature was measured primarily between the heater and the reactor. The agitators used were very close-coupled helical agitators. The height of these agitators was approximately 50% of the clear height inside the reactor.

[0211] Counterexample 2, which is not according to the present invention, had the special feature that the reactors used were the same, reactors A, B and C were the same reactor, and there was no transfer of materials between the steps.

[0212] The grade 4.0 SiH4 used was obtained from Linde GmbH.

[0213] The porous particles used in the examples had the following properties: Density: 2.19g / cm 3;(He pycnometry) BET specific surface area: 2255m 2 / g Gurvich volume: 1.16cm 3 / g Carbon content: 93.39% by weight (EA) Oxygen content: 5.45% by weight (EA) Hydrogen content: 0.70% by weight (EA) Micropore volume: 0.46 cm 3 / g Particle size distribution:d 50 4.4 μm

[0214] [Example 1] Production of silicon-containing materials using monosilane SiH4 as silicon precursor in a cascade reactor system.

[0215] In step 1.1, reactor A was filled with 842 g of porous material, which was porous particles, and sealed. Then, in step 1.2, reactor A was adjusted to 350°C and heated to 1×10 -3 The mixture was then evacuated to a final pressure of 100 bar. Subsequently, in step 1.3, the material was transferred under nitrogen atmosphere to reactor B, which was heated to 350°C.

[0216] In step 2.1, the porous material in reactor B was heated to 350° C. In step 2.2, reactor B was initially charged with 1×10 -3 The reactor was evacuated to 1.5 bar. Subsequently, in step 2.4, an amount of 158 g of SiH4 was charged at a pressure of 15.0 bar. In steps 3.1 and 4.1, reactor B was heated to a temperature of 430°C over 15 minutes, and in step 4.2, this temperature was maintained for 70 minutes. In the course of step 4.2, the pressure rose to 35.8 bar, according to equation 2. Thereafter, the pressure in reactor B was reduced to 1.5 bar in step 5.1, and the temperature of the reactor was reduced to 350°C in step 5.2.

[0217] Steps 2.4, 3.1, 4.1, 4.2, 5.1, and 5.2 were then performed 10 times in the specified order. During this operation, x g of SiH4 was metered in at various steps 2.4 (x = 139, 133, 131, 128, 122, 119, 116, 114, 110, 77) in the specified order while initially establishing a pressure of y bar (y = 15.0, 15.0, 15.0, 15.0, 15.0, 15.0, 15.0, 15.0, 14.9, 11.0). In all 10 cases, Reactor B was heated to a temperature of 430°C over 15 minutes in steps 3.1 and 4.1 and maintained at this temperature for 60 minutes in the repetition of step 4.2. During step 4.2, the pressure increased to zbar (z=35.6, 35.0, 34.2, 33.4, 33.1, 32.6, 32.0, 31.5, 31.8, 23.4) according to equation 2. Following the first nine repetitions of step 4.2, the pressure was reduced to 1.5bar in step 5.1, and reactor B was cooled to a temperature of 350°C over 30 minutes in step 5.2. After the tenth and final repetition of step 4.2, step 5 was omitted, and the pressure in reactor B was reduced to 1.0bar in step 6.1. The hot material was then transferred to reactor C through a piping connection in step 6.2. In step 6.3, a pressure of 4.5bar was generated in reactor C using nitrogen, and the silicon-containing material was cooled to a temperature of 70°C in reactor C over 90 minutes. Then, in step 7.1, reactor C is purged with nitrogen 5 times, with the lean air of 5% oxygen fraction 10 times, with the lean air of 10% oxygen fraction 10 times, with the lean air of 15% oxygen fraction 10 times, and then with air 10 times.In step 7.2, the silicon-containing material in the form of fine black solid is isolated in an amount of 1992 g.The silicon-containing material has the following properties: - BET specific surface area: 43m 2 / g - Carbon content: 40.2% by weight (EA) - Oxygen content: 2.77% by weight (EA) - Silicon content: 57.0% by weight (EA)

[0218] The run lasted a total of 36 hours. All three reactors were running simultaneously. The timed run of the cascade reactors was run in reactor B, which in this case was 18 hours.

[0219] [Counterexample 2 (not according to the present invention)] Production of silicon-containing materials using monosilane SiH4 as silicon precursor in reactors (for a counter example, reactors A, B and C in Example 1 are the same pressure vessel).

[0220] In step 1.1, the reactor was filled with 842 g of porous material and sealed. Then, in step 1.2, the reactor was conditioned to 350°C and heated to 1×10°C for 240 min. -3The reactor was evacuated to a final pressure of 1.5 bar. Subsequently, in step 2.4, an amount of 318 g of SiH4 was charged at a pressure of 15.0 bar. In steps 3.1 and 4.1, the reactor was heated to a temperature of 430°C over 15 minutes, and in step 4.2, this temperature was maintained for 70 minutes. During step 4.2, the pressure increased to 35.8 bar, according to equation 2. The pressure in the reactor was then reduced to 1.5 bar in step 5.1, and the temperature of the reactor was reduced to 350°C in step 5.2. Subsequently, steps 2.4, 3.1, 4.1, 4.2, 5.1, and 5.2 were performed 10 times in the specified order. During this operation, x g of SiH4 were metered in the specified sequence in various stages 2.4 (x = 137, 130, 131, 130, 123, 120, 118, 116, 111, 75) while initially establishing a pressure of y bar (y = 15.0, 15.0, 15.0, 15.0, 15.0, 15.0, 14.9, 15.0, 15.0, 11.0). In all ten cases, the reactor was heated to a temperature of 430°C over 15 minutes in stages 3.1 and 4.1, and this temperature was maintained for 60 minutes in stage 4.2. During step 4.2, the pressure increased to zbar (z=35.7, 35.2, 34.0, 33.3, 33.1, 32.8, 32.0, 31.3, 31.5, 23.74) according to equation 2. After the first nine repetitions of step 4.2, the pressure was reduced to 1.5bar in step 5.1, and the reactor was cooled to a temperature of 350°C in step 5.2 over 30 minutes. After the tenth and final repetition of step 4.2, step 5 was omitted, and the pressure in the reactor was reduced to 1.0bar in step 6.1. In step 6.3, a pressure of 4.5bar was generated in the reactor using nitrogen, and the silicon-containing material was cooled to a temperature of 70°C over 14 hours. Subsequently, in step 7.1, reactor is purged with nitrogen 5 times, with the lean air of 5% oxygen fraction 10 times, with the lean air of 10% oxygen fraction 10 times, with the lean air of 15% oxygen fraction 10 times, and then with air 10 times.In step 7.2, the silicon-containing material in the form of fine black solid is isolated in an amount of 1986 g.The silicon-containing material has the following properties: - BET specific surface area: 39m 2 / g - Carbon content: 39.6% by weight (EA) - Oxygen content: 2.87% by weight (EA) - Silicon content: 57.0% by weight (EA)

[0221] The operation lasted a total of 47 hours.

[0222] [Example 3] Electrochemical characterization of silicon-containing materials for use as active materials in anodes of lithium-ion batteries:

[0223] 29.71 g of polyacrylic acid (Sigma Aldrich, Mw approx. 450,000 g / mol, dried to constant weight at 85°C) and 756.6 g of deionized water were stirred on a shaker (290 1 / min) for 2.5 hours until the polyacrylic acid was completely dissolved. Lithium hydroxide monohydrate (Sigma Aldrich) was added in portions to the solution until the pH reached 7.0 (measured using a WTW pH340i pH meter and SenTix RJD probe). The solution was then mixed on the shaker for an additional 4 hours.

[0224] 3.87 g of the neutralized polyacrylic acid solution and 0.96 g of graphite (Imerys, KS6L C) were introduced into a 50 ml container and mixed in a planetary mixer (SpeedMixer, DAC 150 SP) at 2000 rpm. Next, 3.40 g each of the silicon-containing materials from Examples 1 and 2 were stirred at 2000 rpm for 1 minute. 1.21 g of an 8% dispersion of conductive carbon black and 0.8 g of deionized water were then added and incorporated in a planetary mixer at 2000 rpm. Dispersion was then carried out in a dissolver at 3000 rpm and a constant temperature of 20°C for 30 minutes. The ink was again degassed under vacuum in the planetary mixer at 2500 rpm for 5 minutes. The finished dispersion was then applied to a copper foil (Schlenk Metallfolien, SE-Cu58) with a thickness of 0.03 mm using a film applicator frame (Erichsen, Model 360) with a gap height of 0.1 mm. The anode coating thus produced was then dried at 50°C for 60 minutes under an air pressure of 1 bar. The average basis weight of the dried anode coating was 2.1 mg / cm. 2 and the coating density is 0.9 g / cm 3 It was.

[0225] Electrochemical studies were carried out on a two-electrode button cell (CR2032 type, Hosen). The electrode coating was used as the counter electrode or negative electrode (Dm = 15 mm). The content was 94.0% and the concentration was 15.9 mg / cm. 2 A lithium nickel manganese cobalt oxide 6:2:2 based coating (obtained from SEI) with an average basis weight of 1000 kJ / cm2 was used as the working electrode or positive electrode (D = 15 mm). A glass fiber filter paper (Whatman, GD Type D) impregnated with 60 μl of electrolyte was used as the separator (D = 16 mm). The electrolyte used consisted of a 1.0 molar solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of fluoroethylene carbonate and diethyl carbonate. The cell was assembled in a glove box (less than 1 ppm H2O, O2). The water content of the dry mass of all components used was less than 20 ppm.

[0226] Electrochemical testing was performed at 20°C. The cells were charged by the cc / cv (constant current / constant voltage) method at a constant current of 5 mA / g (corresponding to C / 25) in the first cycle and 60 mA / g (corresponding to C / 2) in subsequent cycles. After reaching a voltage limit of 4.2 V, charging was continued at a constant voltage until the current fell below 1.2 mA / g (corresponding to C / 100) or 15 mA / g (corresponding to C / 8). The cells were discharged by the cc (constant current) method at a constant current of 5 mA / g (corresponding to C / 25) in the first cycle and 60 mA / g (corresponding to C / 2) in subsequent cycles until a voltage limit of 2.5 V was reached. The specific current selected was based on the weight of the coating on the positive electrode. The ratio of the cell's charge capacity to its discharge capacity is called the coulombic efficiency. The electrodes were selected to establish a cathode-to-anode capacity ratio of 1:1.2.

[0227] The results of electrochemical testing of full cells of lithium ion batteries containing the active materials of Examples 1 and 2 are shown in Table 1.

[0228] [Table 1]

[0229] In Comparative Example 2, 1986 g of material was produced in a 12 liter reactor over 48 hours by a method not according to the invention. In Example 1, 1992 g of material was produced by a method according to the invention over 18 hours in three reactors each having a volume of 12 liters. Thus, in Example 1, the yield of material over time was 2.5 times higher than in Example 2.

Claims

1. 1. A method for producing silicon-containing materials by pyrolysis of one or more silicon precursors in the presence of one or more porous particles, wherein silicon is deposited within the pores and on the surfaces of the porous particles in a cascade reactor system, which is a series of multiple reactors; A method comprising at least steps 1 to 7: Step 1: Packing reactor A with porous particles and pretreating the particles; Step 2: Transfer the pretreated particles to reactor B and charge the reactor with reactive components including at least one silicon precursor; Step 3: Heating reactor B to a target temperature at which the silicon precursor begins to decompose within the reactor; Step 4: Decomposing the silicon precursor and depositing silicon in the pores and on the surface of the porous particles to form a silicon-containing material, and increasing the pressure to at least 7 bar. Step 5: Cooling Reactor B. Step 6: Removing gaseous reaction products formed during deposition from reactor B and transferring the silicon-containing material to reactor C; Step 7: The silicon-containing material is removed from the reactor C.

2. The method of claim 1, wherein step 1 comprises: Stage 1 Step 1.1: Packing the porous particles into reactor A; Step 1.2: Pretreating the particles in reactor A; Step 1.3: The pretreated particles are transferred to reactor B, or transferred to reactor B after intermediate storage in storage vessel D, or the material remains in reactor A.

3. 3. The method according to claim 1 or 2, wherein step 2 comprises: Stage 2 Step 2.1: Heating or cooling the particles in reactor B; Step 2.4: Reactor B is charged with at least one reactive component comprising at least one silicon precursor.

4. The method according to claims 1 to 3, wherein step 3 is configured as follows: Stage 3 Step 3.1: Heat Reactor B to a target temperature at which the reactive components begin to decompose within Reactor B.

5. The method according to claims 1 to 4, wherein step 4 is configured as follows: Step 4.1: The silicon precursor is decomposed to deposit silicon in the pores and on the surface of the porous particles, and the pressure is increased to at least 7 bar. Step 4.2: Establish a minimum temperature or temperature profile over a predetermined period of time that results in a pressure of at least 7 bar.

6. The method according to claims 1 to 5, wherein step 5 is configured as follows: Stage 5 Step 5.1: Adjust the pressure in reactor B to a predetermined pressure; Step 5.2: Cool reactor B to a predetermined temperature or to a predetermined temperature profile.

7. The method according to claims 1 to 6, wherein step 6 is configured as follows: Stage 6 Step 6.1: Removing gaseous reaction products formed during deposition from reactor B; Step 6.2: The particles are transferred to reactor C, or transferred to reactor C after intermediate storage in storage vessel E, or the material remains in reactor B; Step 6.3: Adjust reactor C to a predetermined temperature or predetermined temperature profile and predetermined pressure.

8. The method according to claims 1 to 7, wherein step 7 is configured as follows: Stage 7 Step 7.1: Post-treating the particles in reactor C to deactivate the particle surface; Step 7.2: The particles are cooled to a predetermined temperature and the silicon-containing material is removed from reactor C and preferably transferred directly to storage vessel E or charged directly into a suitable container.

9. 9. The process according to claims 1 to 8, wherein the cascade reactor system consists of only two interdependent reactors, and steps 1 to 6.1 are carried out in the same reactor and step 1.3 is omitted, or steps 2 to 7 are carried out in one reactor and step 6.2 is omitted.

10. 10. The process according to claim 1 or 5 to 9, wherein the pressure in reactor B in steps 4.1 and 4.2 reaches at least 10 bar.

11. 11. The process according to claim 1 or 5 to 10, wherein the temperature in reactor B in steps 4.1 and 4.2 is in the range of 100 to 1000°C.

12. 12. The method of any one of claims 1 to 11, wherein the silicon precursor comprises at least one reactive component selected from silicon-hydrogen compounds, chlorine-containing silanes and higher linear, branched or cyclic homologues of chlorine-containing silanes, chlorinated and partially chlorinated oligosilanes and polysilanes, methylchlorosilanes or mixtures thereof.

13. 13. The method according to any one of claims 1 to 12, wherein the porous particles are selected from amorphous carbon, silicon dioxide, boron nitride, silicon carbide and silicon nitride or hybrid materials based on these materials.

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