Silicon subhalide-containing composite particles

Abstract

The present invention relates to silicon subhalide-containing composite particles having 3. a Si content >30 wt. %, 4. silicon disposed in and on the pores of a porous matrix, 5. a halogen concentration of 0.0003-16 wt. %, 6. a pH value of 3-9 and 7. a volume weighted particle size distribution with a diameter percentile d50 in the range of 0.5-20 μm, a method for producing the silicon subhalide-containing composite particles, an anode material for a lithium ion battery, the anode material comprising the composite particles, an anode comprising a current collector coated with the anode material and at least one anode comprising the composite particles.

Description

[Technical Field]

[0001] The present invention relates to porous particles, silicon subhalide-containing composite particles based on silicon and halogens, a method for making the composite particles and their use as active materials in anodes for lithium ion batteries. [Background technology]

[0002] As a storage medium for electrical current, 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 motorized transportation such as bicycles, scooters, and automobiles. Graphite carbon is currently widely used as the active material for the negative electrode ("anode") of corresponding batteries. However, such graphite carbon has the disadvantage of a relatively low electrochemical capacity. This theoretical maximum is 372 mAh per gram of graphite, which is therefore only about one-tenth of the theoretically achievable electrochemical capacity of lithium metal. An alternative active material for the anode uses the addition of silicon, as described, for example, in EP 3335262 B1. Silicon forms a binary electrochemically active alloy with lithium, allowing for very high electrochemically achievable lithium contents of up to 4200 mAh per gram of silicon.

[0003] The incorporation and de-incorporation of lithium ions into silicon has the drawback of causing very large volume changes, which can reach up to 300% in the case of complete incorporation. Such volume changes subject the silicon-containing active material to severe mechanical stresses that can ultimately lead to its decomposition. This process, also known as electrolytic grinding, results in a permanent and irreversible loss of electrode capacity due to the loss of electrical contact within the active material and the electrode structure.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the electrolyte components, resulting in the continuous formation of a passivating protective layer (solid electrolyte interface; SEI). The formed components are no longer electrochemically active. The lithium bound therein is no longer available to the system, thus resulting in a continuous and significant decrease in battery capacity. Due to the extreme changes in silicon volume during the battery's charge / discharge cycle, the SEI periodically ruptures. This exposes the unoccupied surface of the silicon-containing active material, which is then subjected to further SEI formation. Because the amount of mobile lithium in the entire cell, corresponding to the usable capacity, is limited by the cathode material, the cathode material is increasingly consumed, and the cell's capacity decreases to an unacceptable level from an application perspective after just a few cycles.

[0005] The decrease in capacity over the course of several charge and discharge cycles is also called capacity fade or continuous loss and is usually irreversible.

[0006] Several silicon-carbon composite particles have been described as silicon-containing active materials for lithium-ion battery anodes. Silicon-carbon composite particles are obtained, for example, by depositing silicon within porous carbon particles via the thermal decomposition of a gaseous or liquid silicon precursor. For example, US Pat. No. 10,147,950B2 describes the deposition of silicon within porous carbon particles from monosilane SiH4 by a CVD ("chemical vapor deposition") or PE-CVD ("plasma-enhanced chemical vapor deposition") method, preferably in a tubular furnace or equivalent furnace type at high temperatures of 300-900°C with particle agitation. Even composites obtainable in this way have insufficient cycle stability for use in demanding applications. Additionally, silicon deposition requires high temperatures and / or long reaction times, thus requiring significant amounts of energy and time. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent No. 3335262 [Patent Document 2] U.S. Patent No. 10,147,950 Summary of the Invention [Problem to be solved by the invention]

[0008] However, known materials do not claim halogens as constituents. US20140272592A, for example, describes Si / C composites with chlorine contents of up to 1000 ppm (measured by X-ray fluorescence, TXRF), and postulates that higher levels of contamination are detrimental to electrochemical performance. [Means for solving the problem]

[0009] The present invention provides 1.Si content>30wt%, 2. Silicon disposed within and on the pores of the porous matrix; 3. A halogen concentration of 0.0003 to 16% by weight; 4. pH 3 to 9 and 5. Diameter percentile d between 0.5 and 20 μm 50 volume-weighted particle size distribution having The present invention provides silicon subhalide-containing composite particles having the following formula:

[0010] Surprisingly, it has been found that the performance of halogen-containing materials is comparable to that of non-halogen-containing materials with similar physical properties. In addition, the halogen-containing materials can be produced from substantially less expensive halogen-containing precursors.

[0011] These halogen-containing precursors are also industrial precursors to halogen-free SiH, which is produced from HSiCl, SiHCl, or HSiCl and requires subsequent energy-intensive distillation purification. Therefore, the use of halosilanes can significantly reduce the CO footprint of the entire materials concept.

[0012] Furthermore, it has been surprisingly found that the decomposition temperatures of halogen-containing silanes in the presence of reactive surfaces (e.g., activated carbon) are substantially lower than previously assumed (J. Phys. Chem. 1990, 94, 327-331, above 600°C).

[0013] The silicon subhalide-containing composite particles of the present invention can be produced by any desired method.The method similar to that described in US 10,147,950B2, infiltrating into porous particles and depositing silicon from gaseous or liquid silicon precursors is a particularly suitable route to the silicon subhalide-containing composite particles of the present invention.

[0014] The deposition of silicon by pyrolysis from gaseous or liquid silicon precursors within the pores and on the surfaces of the porous particles is in this case referred to as silicon infiltration.

[0015] The same or different silicon precursors can be reacted with the same or different porous particles.

[0016] The present invention also relates to a method for producing subhalide silicon-containing composite particles according to the invention by silicon infiltration from silicon precursors selected from halogen-containing silicon precursors that are gaseous and / or liquid at 20° C. and 1013 mbar, wherein at least one halogen-containing silicon precursor is 1. Diameter percentile d between 0.5 and 20 μm 50 a volume-weighted particle size distribution having 2.0.4~2.2cm 3 the total pore volume of the micropores and mesopores (Grbic pore volume) measured by N2 adsorption in the range of / g, and PD50 pore diameter measured by N2 adsorption below 3.30 nm wherein the porous particles are present in the presence of the porous particles having the formula: DETAILED DESCRIPTION OF THE INVENTION

[0017] Silicon is deposited within the pores and on the surface of the porous particles.

[0018] Any material can be employed as the porous particles for the composite particles, including porous carbon particles or porous oxides such as silicon dioxide, aluminum oxide, silicon-aluminum mixed 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 oxides of the following formula: Al a B b C c Mg d N e O f Si g Other ceramic materials are preferred that can be described by the formula: where 0 £ a, b, c, d, e, f, g ≤ 1, and where at least two coefficients a~g > 0, and a*3 + b*3 + c*4 + d*2 + g*4 3 e*3+f*2.

[0019] The ceramic material may be, for example, a binary, ternary, quaternary, pentanary, hexanary, or heptanary compound having the following formula: Non-stoichiometric boron nitride BN z where z=0.2 to 1, Non-stoichiometric carbon nitride CN z where z=0.1 to 4 / 3; Boron carbonitride B x CN z where x=0.1 to 20 and z=0.1 to 20, and where x*3+4 3 z*3, Boron nitride oxide BN z O r wherein z=0.1 to 1 and r=0.1 to 1, and wherein 3 3 r*2+z*3), Boron Carbonitride Oxide B x CN z O r where x=0.1 to 2, z=0.1 to 1, and r=0.1 to 1, and where x*3+4 3 r*2+z*3, Silicon Carboxide Si x CO zwhere x=0.1 to 2 and z=0.1 to 2, and where x*4+4 3 z*2, Silicon carbonitride Si x CN z where x=0.1 to 3 and z=0.1 to 4, and where x*4+4 3 z*3, Silicon borocarbonitride Si w B x CN z where w=0.1 to 3, x=0.1 to 2, and z=0.1 to 4, and where w*4+x*3+4 3 z*3, Silicon borocarbonate Si w B x CO z where w=0.10 to 3, x=0.1 to 2, and z=0.1 to 4, and where w*4+x*3+4 3 z*2), Silicon borocarbonitride oxide Si v B w CN x O z where v=0.1 to 3, w=0.1 to 2, x=0.1 to 4, and z=0.1 to 3, and where v*4+w*3+4 3 x*3+z*2 and Aluminum borosilicocarbonitride oxide Al u B v Si x CN w O z In the formula, u=0.1 to 2, v=0.1 to 2, w=0.1 to 4, x=0.1 to 2, and z=0.1 to 3, and in the formula, u*3+v*3+x*4+4 3 w*3+z*2 Ceramic materials having the formula:

[0020] Preferred porous particles are based on carbon, silicon dioxide, boron nitride, silicon carbide, silicon nitride or mixed materials based on these compounds, in particular based on silicon dioxide or boron nitride.

[0021] Particularly preferred porous particles are porous boron nitride particles, porous silicon oxide particles and / or microporous carbon particles.

[0022] It is preferred to dry the porous particles prior to reaction with the gas or liquid silicon precursor.

[0023] Drying of the porous particles can be carried out at high temperatures of 50 to 400°C in an inert gas atmosphere in any desired reactor suitable for drying. Examples of suitable inert gases include nitrogen and argon. Alternatively, drying can be carried out at high temperatures of 50 to 400°C and under reduced pressure of 0.001 to 900 mbar. The drying time is preferably 0.1 seconds to 48 hours. Drying of the porous particles can be carried out in the same reactor as the reaction with the gaseous or liquid silicon precursor or in a separate reactor suitable for drying.

[0024] The porous particles preferably have a density measured by helium pycnometry of 0.1 to 4 g / cm 3 , and particularly preferably 0.3 to 3 g / cm 3 is.

[0025] The porous particles preferably have a diameter percentile d of ≧0.5 μm, particularly preferably ≧1.5 μm, most preferably ≧2 μm. 50 The diameter percentile d 50 is preferably ≦20 μm, particularly preferably ≦12 μm, most preferably ≦8 μm.

[0026] 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, particularly preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0027] The porous particles preferably have a diameter percentile d of ≦10 μm, particularly preferably ≦5 μm, especially preferably ≦3 μm, most preferably ≦2 μm. 10 The diameter percentile d 10 is preferably ≧0.2 μm, particularly preferably ≧0.4, most preferably ≧0.6 μm.

[0028] The porous particles preferably have a diameter percentile d of ≧4 μm, particularly preferably ≧8 μm. 90 The diameter percentile d 90 is preferably ≦20 μm, particularly preferably ≦15, most preferably ≦12 μm.

[0029] The volume-weighted particle size distribution of the porous particles preferably has a width d of ≦15.0 μm, more preferably ≦12.0 μm, particularly preferably ≦10.0 μm, especially preferably ≦8.0 μm, and most preferably ≦4.0 μm. 90 ~d 10 The volume-weighted particle size distribution of the porous particles preferably has a width d of ≥ 0.6 μm, particularly preferably ≥ 0.7 μm, most preferably ≥ 1.0 μm. 90 ~d 10 It has.

[0030] The volume weighted particle size distribution can be measured in accordance with ISO 13320 using static laser scattering using the Mie model on a Horiba LA 950 measuring device with ethanol as the dispersion medium for the porous particles.

[0031] Porous particles can be, for example, isolated or agglomerated. Porous particles are preferably non-agglomerated, preferably non-agglomerated. Agglomerates generally mean that, during the production of porous particles, primary particles are first formed, then fuse and / or the primary particles are linked to each other, for example, by covalent bonds, thus forming agglomerates. Primary particles are generally isolated particles. Agglomerates or isolated particles can form agglomerates. Agglomerates are loose collections of agglomerates or primary particles linked to each other, for example, by van der Waals interactions or hydrogen bonds. Agglomerated agglomerates can be easily broken back into agglomerates by common kneading and dispersion processes. Agglomerates can only be partially broken down into primary particles, if at all, by such processes. The presence of porous particles in the form of agglomerates, agglomerates, or isolated particles can be visualized, for example, using a conventional scanning electron microscope (SEM). In contrast, static light scattering methods for measuring particle size distribution or particle diameter cannot distinguish between agglomerates and agglomerates.

[0032] The porous particles may have any desired morphology, ie, for example, lobed, flake-like, spherical or needle-like, preferably lobed or spherical porous particles.

[0033] The morphology can be characterized, for example, by the sphericity ψ or sphericity S. According to Wadell's definition, the sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the object. For a sphere, ψ has the value 1. According to this definition, the porous particles preferably have a sphericity ψ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0034] The sphericity S is the ratio of the circumference of a circle with the same area A as the projection of a particle onto a surface to the measured circumference U of this projection: S = 2πA / U. For an ideal circular particle, S can have a value of 1. For porous particles, the sphericity S is the percentile S of the sphericity distribution. 10 ~S90 Based on the above, the sphericity S is preferably in the range of 0.5 to 1.0, particularly preferably 0.65 to 1.0. The measurement of the sphericity S is carried out using micrographs of individual particles, for example by optical microscopy, or in the case of particles <10 μm, preferably by scanning electron microscopy, followed by graphical evaluation using image analysis software, for example ImageJ.

[0035] The porous particles are preferably ≥ 0.2 cm 3 / g, particularly preferably ≥ 0.6 cm 3 / g, most preferably ≥ 1.0 cm 3 / g, which is useful for obtaining high-capacity lithium-ion batteries. The gas-accessible pore volume is determined by gas adsorption measurements with nitrogen according to DIN 66134.

[0036] Preferably, porous particles are open-pore. Open-pore generally means that the pores are connected to the particle surface, for example, via channels, and are preferably capable of mass exchange with the environment, especially gaseous compounds. This can be demonstrated by gas adsorption measurements (analysis by Brunauer, Emmett, and Teller, "BET"), i.e., specific surface area.

[0037] The porous particles are preferably ≥ 50 m 2 / g, particularly preferably ≥ 500m 2 / g, most preferably ≥ 1000m 2 / g. The BET surface area is determined in accordance with DIN 66131 (with nitrogen).

[0038] The pores of the porous particles can have any diameter, i.e., generally in the range of macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Porous particles can be used as any mixture of different pore types. It is preferable to use porous particles with up to 30% macropores, based on the total pore volume, particularly preferably porous particles with no macropores, and especially preferably porous particles with at least 50% pores with an average pore diameter of less than 5 nm. It is particularly preferable for the porous particles to have only pores with a pore diameter of less than 2 nm (measurement method: pore size distribution in the mesopore range according to BJH (gas adsorption) according to DIN 66134, in the micropore range according to Horvath-Kawazoe (gas adsorption) according to DIN 66135; evaluation of the pore size distribution in the macropore range is carried out by mercury porosimetry according to DIN ISO 15901-1).

[0039] The PD50 pore diameter of the porous particles is preferably in the range of 0.5 to 30 nm, preferably in the range of 0.5 to 20 nm, particularly preferably in the range of 0.5 to 10 nm. As used herein, the term "PD50 pore diameter" refers to the average pore diameter on a volume basis based on the total volume of micropores and mesopores (i.e., 50% of the total volume of micropores and mesopores is found at pore diameters less than or equal to this). Thus, according to the present invention, preferably, at least 50% of the total volume of micropores and mesopores is in the form of pores having a diameter of less than 30 nm.

[0040] For clarity, it should be noted that not all macropore volume (pore diameters greater than 50 nm) is taken into account in determining the PD50 value.

[0041] The porous particles preferably have a pH of > 3, preferably > 5, particularly preferably > 6. The pH of the porous particles can be measured according to ASTM Standard No. D1512, Method A.

[0042] The silicon subhalide composite particles of the present invention are comprised of one or more porous particles in which silicon subhalide is deposited within the pores and on the surfaces of the porous particles. The deposited subhalide is composed of silicon and a halogen, preferably chlorine, and has a molar composition SiCl in the range of x=0.00001 to 0.15, preferably x=0.00001 to 0.01, and particularly preferably x=0.0001 to 0.05. x In another embodiment, the deposited subhalide has a molar composition SiBr in the range of x=0.00001 to 0.15, preferably x=0.00001 to 0.01, particularly preferably x=0.0001 to 0.05. x and / or SiF x and / or SiI x It has.

[0043] The silicon subchloride composite particles according to the present invention preferably have a chlorine content of 0.0003 to 16% by weight, preferably 0.0003 to 12% by weight, particularly preferably 0.0003 to 6% by weight.

[0044] The silicon subbromide composite particles according to the present invention preferably have a bromine content of 0.0009 to 30% by weight, preferably 0.0009 to 22% by weight, particularly preferably 0.0009 to 15% by weight.

[0045] The silicon subfluoride composite particles according to the present invention preferably have a fluorine content of 0.0002 to 9% by weight, preferably 0.0002 to 7% by weight, particularly preferably 0.0002 to 3.5% by weight.

[0046] The silicon subiodide composite particles according to the present invention preferably have an iodine content of 0.0015 to 41% by weight, preferably 0.0015 to 31% by weight, particularly preferably 0.0015 to 18% by weight.

[0047] (Method of measurement: preferably X-ray fluorescence analysis on a Bruker AXS S8 Tiger 1 instrument, in particular with a rhodium anode).

[0048] The deposited subhalides may further contain the following elements as constituents: H, O, N, C, S, Fe, Ni, Cu, Mo, W, Mn, Al, K, Na, Ca, Ba, Sr, Cr, Mg, Zn, P.

[0049] The silicon subhalide-containing composite particles according to the invention preferably have a diameter percentile d of ≥ 1.5 μm, particularly preferably ≥ 2 μm. 50 The diameter percentile d 50 is preferably ≦13 μm, particularly preferably ≦8 μm.

[0050] The volume-weighted particle size distribution of the silicon subhalide-containing composite particles according to the present invention preferably has a diameter percentile d 10 ≧0.2μm~d 90 ≦20.0 μm, particularly preferably d 10 ≧0.4μm~d 90 ≦15.0 μm, most preferably d 10 ≧0.6μm~d 90 ≦12.0 μm.

[0051] The silicon subhalide-containing composite particles according to the invention preferably have a diameter percentile d of ≦10 μm, particularly preferably ≦5 μm, especially preferably ≦3 μm, most preferably ≦1 μm. 10 The diameter percentile d 10 is preferably ≧0.2 μm, particularly preferably ≧0.4 μm, most preferably ≧0.6 μm.

[0052] The silicon subhalide-containing composite particles according to the invention preferably have a diameter percentile d of ≥ 5 μm, particularly preferably ≥ 10 μm. 90 The diameter percentile d 90 is preferably ≦20.0 μm, particularly preferably ≦15.0 μm, and most preferably ≦12.0 μm.

[0053] The volume-weighted particle size distribution of the silicon subhalide-containing composite particles according to the present invention preferably has a width d 90 ~d 10 The volume-weighted particle size distribution of the silicon subhalide-containing composite particles according to the invention preferably has a width d of ≥ 0.6 μm, particularly preferably ≥ 0.7 μm, most preferably ≥ 1.0 μm. 90 ~d 10 It has.

[0054] The silicon subhalide-containing composite particles according to the present invention are preferably in the form of particles.Particles can be isolated or agglomerates.The silicon subhalide-containing composite particles according to the present invention are preferably non-agglomerates, preferably non-agglomerates.The terms isolated, agglomerates and non-agglomerates have already been further defined above in relation to porous particles.The presence of the silicon subhalide-containing composite particles according to the present invention in the form of agglomerates or agglomerates can be visualized, for example, by using a conventional scanning electron microscope (SEM).

[0055] The silicon subhalide-containing composite particles according to the present invention may have any desired morphology, ie, may be, for example, lobed, flake-like, spherical or acicular, preferably lobed or spherical particles.

[0056] According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the object. For a sphere, ψ has a value of 1. According to this definition, the silicon subhalide-containing composite particles according to the present invention preferably have a sphericity ψ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0057] The sphericity S is the ratio of the circumference of a circle equivalent to the projection of the particle onto the surface and having the same area A as the projection, to the measured circumference U of this projection: S=2πA / U. For an ideal circular particle, S may have a value of 1. For silicon subhalide-containing composite particles according to the invention, the sphericity S is the percentile S of the sphericity distribution. 10 ~S 90 Based on the above, the sphericity S is preferably in the range of 0.5 to 1.0, particularly preferably 0.65 to 1.0. The measurement of the sphericity S is carried out using micrographs of individual particles, for example by optical microscopy, or in the case of particles <10 μm, preferably by scanning electron microscopy, followed by graphical evaluation using image analysis software, for example ImageJ.

[0058] 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 the silicon subhalide-containing composite particles according to the present invention.

[0059] The silicon subhalide-containing composite particles according to the present invention preferably contain 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably 30 to 60% by weight, and especially preferably 40 to 50% by weight of silicon obtained by silicon infiltration, based on the total weight of the silicon subhalide-containing composite particles according to the present invention (preferably measured by elemental analysis such as ICP-OES).

[0060] The volume of silicon subhalide introduced into the porous particles is determined by multiplying the total mass of the silicon subhalide-containing composite particles according to the present invention by the density of silicon (2.336 g / cm 3 ) divided by the mass fraction of silicon subhalide obtained by infiltration from the silicon precursor.

[0061] The pore volume P of the silicon subhalide-containing particles according to the present invention is calculated by the sum of the gas-accessible pore volume and the gas-inaccessible pore volume. The Grbic gas-accessible pore volume of the silicon subhalide-containing composite particles according to the present invention can be measured by gas adsorption measurement using nitrogen according to DIN 66134.

[0062] The gas inaccessible pore volume of the silicon subhalide-containing composite particles according to the present invention can be measured by the formula: gas inaccessible pore volume=1 / skeletal density−1 / pure material density.

[0063] Here, the skeletal density is the density of the composite particles according to the invention measured by helium pycnometry according to DIN 66137-2, and the pure material density of the composite particles according to the invention is the theoretical density that can be calculated from the sum of the theoretical pure material densities of the components present in the composite particles according to the invention multiplied by their respective weight percentages in the total material, which gives the following for the silicon subhalide-containing composite particles: Pure material density = Theoretical pure material density of silicon (2.336 g / cm 3 )*percentage of silicon in wt%+density of porous particles (measured by helium pycnometry)*percentage of porous particles in wt%.

[0064] The pore volume P of the silicon subhalide-containing composite particles according to the present invention is preferably in the range of 0 to 400 vol. %, more preferably in the range of 100 to 350 vol. %, particularly preferably in the range of 200 to 350 vol. %, based on the volume of silicon obtained from silicon infiltration and present in the composite particles according to the present invention.

[0065] The pores present in the composite particles according to the present invention may be gas-accessible or gas-inaccessible. The volume ratio of gas-accessible pores to gas-inaccessible pores of the silicon subhalide-containing composite particles according to the present invention 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 of the composite particles according to the present invention is in the range of 0 to 0.8, particularly preferably in the range of 0 to 0.3, and particularly preferably in the range of 0 to 0.1.

[0066] The pores of the silicon subhalide-containing composite particles according to the present invention can have any desired diameter, for example, in the range of macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). The composite particles according to the present invention can also contain any desired mixture of different pore types. The composite particles according to the present invention preferably contain up to 30% macropores based on the total pore volume, with composite particles according to the present invention having no micropores being particularly preferred, and composite particles according to the present invention comprising at least 50% pores with an average pore diameter of less than 5 nm being very particularly preferred. It is particularly preferred if the silicon subhalide-containing composite particles according to the present invention only contain pores with a diameter of up to 2 nm.

[0067] The silicon subhalide-containing composite particles according to the invention preferably have silicon structures in at least one dimension, preferably with a structure size of at most 1000 nm, more preferably less than 100 nm, particularly preferably less than 5 nm (measurement method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)).

[0068] The silicon subhalide-containing composite particles according to the present invention preferably contain silicon or silicon subhalide in the form of a layer in the pores and / or on the outer surface, with a layer thickness of up to 1000 nm, more preferably less than 100 nm, particularly preferably less than 5 nm (measurement method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The composite particles according to the present invention can also contain silicon or silicon subhalide in the form of a layer formed from silicon particles. The silicon particles preferably have a diameter of up to 1000 nm, more preferably less than 100 nm, particularly preferably less than 10 nm (measurement method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The data on silicon particles here preferably relate to the diameter of the circumference of the particle in the microscopic image.

[0069] The silicon subhalide-containing composite particles according to the present invention have a maximum particle size of 170 m 2 / g, preferably 100m 2 / g, and even more preferably less than 60m 2 / g, particularly preferably less than 20m 2 / g。 BET surface area is measured in accordance with DIN 66131 (using nitrogen). Therefore, by using the silicon subhalide-containing composite particles according to the present invention as an active material in an anode for a lithium ion battery, it is possible to reduce SEI formation and increase the initial coulombic efficiency.

[0070] Furthermore, the silicon deposited from the silicon precursor in the silicon-containing material may contain a dopant selected from the group consisting of, for example, Fe, Al, Cu, S, Cl, Zr, Ti, Pt, Ni, Cr, Sn, Ag, Co, Zn, B, P, Sb, Pb, Ge, Bi, rare earths, or combinations thereof. Li and / or Sn are preferred. The dopant content in the silicon subhalide-containing composite particles is preferably at most 1 wt. %, particularly preferably at most 100 ppm, based on the total weight of the composite particles as measured by ICP-OES.

[0071] The silicon subhalide-containing composite particles according to the present invention generally have surprisingly high stability under compressive load and / or shear load.The compressive load stability and shear load stability of the composite particles according to the present invention are demonstrated, for example, by the fact that the composite particles according to the present invention show little, if any, change in their porous structure under SEM under compressive stress (for example, during electrode compression) or shear stress (for example, during electrode preparation).

[0072] The preparation of silicon subhalide-containing composite particles according to the present invention can be carried out in any desired reactor that is commonly used for silicon infiltration.Preferably, reactor is selected from fluidized bed reactor, rotary kiln, which can be oriented in any desired configuration from horizontal to vertical, and fixed bed reactor, which can be operated as an open or closed system, for example, as a pressure reactor.Particularly preferred is a reactor that allows the porous particles formed during the infiltration of silicon precursor and the silicon-containing material to be homogeneously mixed.This is advantageous for the most homogeneous possible deposition of silicon in the pores and on the surface of porous particles.The most preferred reactor is a fluidized bed reactor, a rotary kiln or a pressure reactor, particularly a fluidized bed reactor or a pressure reactor.

[0073] Silicon is generally deposited by pyrolysis from halogen-containing silicon precursors.Silicon infiltration can be performed by using one silicon precursor or two or more silicon precursors mixed or alternately, and at least one chlorine-containing precursor must be used.Preferred halogen-containing silicon precursors are trichlorosilane HSiCl3, trifluorosilane HSiF3, tribromosilane HSiBr3, triiodosilane HSiI3, dichlorosilane H2SiCl2, difluorosilane H2SiF2, dibromosilane H2SiBr2, diiodosilane H2SiI2, monochlorosilane H3SiCl, monofluorosilane H3SiF, monobromosilane H3SiBr, monoiodosilane H3SiI, tetrachlorosilane SiCl4, tetrafluorosilane SiF4, tetrabromosilane SiBr4, tetraiodosilane SiI4, hexachlorodisilane Si2 Cl6, hexafluorodisilane Si2F6, hexabromodisilane Si2Br6, hexaiododisilane Si2I6 and higher linear, branched or cyclic homologues such as, for example, 1,1,2,2-tetrachlorodisilane Cl2HSi-SiHCl2, halogenated and partially halogenated oligo- and polysilanes such as trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylchlorosilanes.

[0074] The halogen-free silicon precursors in the mixture are monosilane SiH4, disilane Si2H6 and their higher linear, branched or cyclic homologues, neopentasilane Si5H 12 , cyclopentasilane, cyclohexasilane Si6H 12The silicon precursor is selected from silicon-hydrogen compounds such as methylsilanes, such as methylsilane MeH3Si, chlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or mixtures of the silicon compounds mentioned. In particular, the silicon precursor is selected from trichlorosilane HSiCl3, dichlorosilane H2SiCl2, monochlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and / or mixtures thereof with H-containing silanes, such as monosilane SiH4 or disilane Si2H6. More than 5 ppm of chlorosilane SiH n Cl 4-n Dichlorosilane H2SiCl2, monochlorosilane H3SiCl and monosilane SiH4 having a ratio of (n=0 to 3) are particularly preferred.

[0075] Silicon-free reactive components may also be present in the silicon precursor mixture or alternating therewith. Additional reactive components that may be present in the silicon-free reactive component include hydrocarbons selected from the group consisting of 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, ethene, acetylene, propene or butene, isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene, unsaturated cyclic hydrocarbons such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene, aromatic hydrocarbons such as benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylene, ethylene, propylene, propylene glycol, propylene glycol esters ... methylbenzene, diphenylmethane or naphthalene, further 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 comprising a number of such compounds, for example from natural gas condensates, petroleum distillates or coke oven condensates, mixed fractions from the output streams of fluid catalytic crackers (FCC), steam crackers or Fischer-Tropsch synthesis plants or more generally hydrocarbon-containing material streams from wood, natural gas, petroleum and coal processing.

[0076] These non-silicon-containing reactive components may also be introduced into the gas space of the reactor alternately with the silicon precursor.

[0077] In a particular embodiment of this process, monosilane or silane mixtures, such as a mixture of monosilane SiH4, trichlorosilane HSiCl3, dichlorosilane H2SiCl2, monochlorosilane H3SiCl, and tetrachlorosilane SiCl4, each of which may be present in an amount of 0 to 99.9% by weight, are prepared by a suitable process only immediately prior to use in the reactor. These processes generally proceed from trichlorosilane HSiCl3, which is reconstituted into the other components of the described mixture by a suitable catalyst (e.g., AmberLyst™ A21DRY). The composition of the resulting mixture is primarily determined by workup of the mixture formed at one or more different temperatures after one or more reconstitution steps.

[0078] Particularly preferred reactive components are monosilanes SiH4, oligomeric or polymeric silanes, especially those of the general formula Si n H n+2 wherein n can include an integer ranging from 2 to 10, and linear silanes of the general formula -[SiH2] n -cyclic silanes of the formula -, where n may contain an integer ranging from 3 to 10, selected from the group comprising trichlorosilane HSiCl3, dichlorosilane H2SiCl2 and monochlorosilane H3SiCl, which may be employed alone or in mixtures, the use of SiH4, HSiCl3 and H2SiCl2 alone or in mixtures being very particularly preferred.

[0079] Furthermore, the reactive component may further contain further reactive constituents, such as dopants based on compounds containing boron, nitrogen, phosphorus, arsenic, germanium, iron or nickel, preferably selected from the group comprising ammonia NH3, diborane B2H6, phosphane PH3, germanium GeH4, arsane AsH3, iron pentacarbonyl Fe(CO)4 and nickel tetracarbonyl Ni(CO)4.

[0080] The composition of the gas phase can be measured, for example, by a gas chromatograph and / or a thermal conductivity detector and / or an infrared spectrometer and / or a Raman spectrometer and / or a mass spectrometer, thus allowing targeted control of the deposition process. In a preferred embodiment, the hydrogen content is measured using a thermal conductivity detector and / or any chlorosilanes present are measured using a gas chromatograph or a gas infrared spectrometer.

[0081] The silicon subhalide-containing composite particles can also be post-treated and / or passivated. The composite particles are preferably purged with oxygen, particularly a mixture of an inert gas and oxygen, in the same or a different reactor. This makes it possible, for example, to modify and / or passivate the surfaces of the silicon and silicon subhalide. For example, it is possible to cause any reactive groups present on the surfaces of the silicon and silicon subhalide to react. For this purpose, it is preferred to use a mixture of nitrogen, oxygen, and optionally alcohol and / or water, preferably containing up to 20% by volume, particularly preferably up to 10% by volume, and particularly preferably up to 5% by volume of oxygen, and preferably up to 100% by volume, particularly preferably up to 10% by volume, and particularly preferably up to 1% by volume of water. This step is preferably carried out at a temperature of up to 200°C, particularly preferably up to 100°C, and particularly preferably up to 50°C. Passivation of the particle surface can also be carried out using a gas mixture containing an inert gas and an alcohol. Here, it is preferred to use nitrogen and isopropanol. However, it is also possible to employ methanol, ethanol, butanol, pentanol or longer chain and branched alcohols and diols.

[0082] Deactivation of the composite particles may also be carried out by dispersion in a liquid solvent or solvent mixture, which may contain, for example, isopropanol or an aqueous solution.

[0083] Passivation of the composite particles can also be selectively carried out by coating using C-, Al- and B-containing precursors at temperatures between 200 and 800° C., and optionally subsequent treatment in an oxygen-containing atmosphere.

[0084] Alternatively, post-treatment of the composite particles can be carried out using water or an aqueous solution. Preferably, the particles are washed several times with water until the pH of the wash water is > 3. The sample can be treated, for example, with ultrasound.

[0085] The process for producing a composite article according to the invention is preferably carried out in an inert gas atmosphere, for example in a nitrogen or argon atmosphere.

[0086] In this method, silicon infiltration is preferably carried out at temperatures between 280 and 900°C, particularly preferably between 320 and 600°C, in particular between 350 and 450°C.

[0087] Silicon infiltration can be carried out at reduced pressure, atmospheric pressure or elevated pressure, with preference being given to infiltration being carried out at atmospheric pressure or elevated pressures up to 50 bar.

[0088] In all other respects, the process may be carried out in a conventional manner as is common for the infiltration of silicon from silicon precursors, using the usual adjustments, as are familiar to those skilled in the art, as necessary.

[0089] The present invention further provides an anode material for a lithium ion battery containing the silicon subhalide-containing composite particles according to the present invention.

[0090] The anode material is preferably based on a mixture comprising silicon subhalide-containing composite particles according to 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.

[0091] The anode material contains silicon subhalide-containing composite particles according to the present invention, preferably one or more binders, optionally graphite as a further active material, optionally one or more further conductive components, and optionally one or more additives.

[0092] The use of other conductive components 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. Preferred additional conductive components are conductive carbon black, carbon nanotubes, or metal particles, such as copper.

[0093] The primary particles of the conductive carbon black preferably have a diameter percentile d 10 = 5 nm and d 90 The primary particles of conductive carbon black can branch like chains, forming structures up to μm in size. Carbon nanotubes preferably have diameters of 0.4 to 200 nm, more preferably 2 to 100 nm, and most preferably 5 to 30 nm. Metal particles have diameter percentiles d 10 = 5 nm and d 90 = 800 nm.

[0094] The anode material preferably comprises 0 to 95% by weight, particularly preferably 0 to 40% by weight, most preferably 0 to 25% by weight of one or more further conductive components, based on the total weight of the anode material.

[0095] The silicon subhalide-containing composite particles according to the present invention may be present in the anode for a lithium ion battery in an amount of preferably 5 to 100% by weight, particularly preferably 30 to 100% by weight, and most preferably 60 to 100% by weight, based on the total active material present in the anode material.

[0096] Preferred binders are polyacrylic acid or its alkali metal salts, particularly lithium or sodium salts, polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, particularly polyamideimides, or thermoplastic elastomers, especially ethylene-propylene-diene terpolymers. Polyacrylic acid, polymethacrylic acid, or cellulose derivatives, particularly carboxymethylcellulose, are particularly preferred. Alkali metal salts of the above-mentioned binders, particularly lithium or sodium salts, are also particularly preferred. Alkali metal salts of polyacrylic acid or polymethacrylic acid, particularly lithium or sodium salts, are most preferred. All or, preferably, some 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. Mixtures of two or more binders can also be used.

[0097] The graphite used can generally be natural or synthetic graphite. The graphite particles preferably have a diameter percentile d 10 >0.2μm~d 90 It has a volume-weighted particle size distribution of <200 μm.

[0098] Examples of additives are pore formers, dispersants, levelling agents or dopants such as elemental lithium.

[0099] A preferred formulation for the anode material preferably contains 5 to 95 wt. %, in particular 60 to 90 wt. %, of silicon subhalide-containing composite particles according to the invention, 0 to 90 wt. %, in particular 0 to 40 wt. % of a further conductive component, 0 to 90 wt. %, in particular 5 to 40 wt. % of graphite, 0 to 25 wt. %, in particular 5 to 20 wt. % of a binder, and optionally 0 to 80 wt. %, in particular 0.1 to 5 wt. % of a further additive, the amounts in wt. % being based on the total weight of the anode material, and the proportions of all components of the anode material adding up to 100 wt. %.

[0100] The present invention further relates to an anode comprising a current collector coated with the anode material according to the present invention, the anode preferably being used in a lithium-ion battery.

[0101] The components of the anode material may be processed into an anode ink or paste, for example, preferably in a solvent 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 bead mill, a vibrating plate, or an ultrasonic device.

[0102] The anode ink or paste preferably has a pH of 2 to 10 (measured, for example, at 20° C. using a WTW pH 340i pH meter with a SenTix RJD probe).

[0103] For example, the anode ink or paste can be knife coated onto a copper foil or another current collector. Other coating methods, such as spin coating, roller, dip or slot coating, brushing or spraying, can also be used in accordance with the present invention.

[0104] Before the copper foil is coated with the anode material according to the invention, it may be treated with a commercially available primer, for example based on polymer resins or silanes, which may provide improved adhesion to the copper but which generally have virtually no electrochemical activity themselves.

[0105] The anode material is preferably dried to a constant weight. The drying temperature depends on the components and solvent used. The drying temperature is preferably 20°C to 300°C, particularly preferably 50°C to 150°C.

[0106] The layer thickness, ie the dry layer thickness of the anode coating, is preferably between 2 μm and 500 μm, particularly preferably between 10 μm and 300 μm.

[0107] Finally, the electrode coating can be calendered to achieve a defined porosity. The electrode thus produced preferably has a porosity of 15 to 85%, which can be measured by mercury porosimetry according to DIN ISO 15901-1. Preferably, 25 to 85% of the pore volume thus measured is provided by pores with a pore diameter of 0.01 to 2 μm.

[0108] The present invention further provides a lithium ion battery comprising at least one anode containing the silicon subhalide-containing composite particles according to the present invention. The lithium ion battery may further comprise a cathode, two conductive connections to the electrodes, a separator, an electrolyte in which the separator and the two electrodes are impregnated, and a housing to contain the components.

[0109] In the context of the present invention, the term lithium-ion battery also includes a cell. 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 also includes a battery management system. A battery management system is generally used to control the battery, for example, for deep discharge protection or overcharge protection, in particular using electronic circuits for detecting the state of charge.

[0110] Preferred cathode materials used may be 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.

[0111] The separator is preferably an ion-permeable, electrically insulating film, preferably made of a polyolefin, such as polyethylene (PE) or polypropylene (PP), or a polyester or corresponding laminate. Alternatively, the separator may consist of or be coated with a glass or ceramic material, as is common in battery manufacturing. As is known, the separator separates the first electrode from the second electrode, thus preventing an electronically conductive connection (short circuit) between the electrodes.

[0112] 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, LiCF3SO3, LiN(CF3SO2) and lithium borate. The concentration of the conductive salt, based on the solvent, is preferably between 0.5 mol / l and the solid solubility limit of the relevant salt. Particularly preferred is a concentration of 0.8 to 1.2 mol / l.

[0113] Examples of solvents that can be used are 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 carbonates or nitriles, either individually or as mixtures thereof.

[0114] The electrolyte preferably contains a film-forming agent such as vinylene carbonate or fluoroethylene carbonate. As a result, the cycle stability of the anode containing the silicon-containing material according to the present invention can be significantly improved. This is mainly 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 0.1 to 20.0 wt %, particularly preferably 0.2 to 15.0 wt %, and most preferably 0.5 to 10 wt %.

[0115] To best match the actual capacity of the electrodes in a lithium-ion cell, it is advantageous to balance the amounts of positive and negative electrode materials. In this regard, it is particularly important that during the first or initial charge / discharge cycle (so-called formation) of a secondary lithium-ion cell, a coating layer forms on the surface of the electrochemically active material in the anode. This top layer, called the "solid electrolyte interface" (SEI), generally consists primarily of electrolyte decomposition products and a certain amount of lithium, and is therefore no longer available for further charge / discharge reactions. The thickness and composition of the SEI depend on the anode material used and the type and quality of the electrolyte solution used.

[0116] In the case of graphite, the SEI is particularly thin. With graphite, there is a typical loss of 5% to 35% of the mobile lithium in the cell during the first charging step. Therefore, the reversible capacity of the battery is also reduced.

[0117] In the case of an anode comprising silicon subhalide-containing composite particles according to the invention, there is preferably a loss of mobile lithium of at most 30%, particularly preferably at most 20%, most preferably at most 10% in the first charging step, which is significantly lower than the prior art values ​​described, for example, in US Pat. No. 10,147,950 B1, for silicon-containing composite anode materials.

[0118] The lithium ion battery according to the invention can be manufactured in all the usual forms, for example in a wound, folded or stacked form.

[0119] As mentioned above, all substances and materials used to manufacture the lithium-ion battery according to the invention are known, except for the composite particles according to the invention. The manufacture of the components of the battery according to the invention and their assembly to obtain the battery according to the invention is carried out by methods known in the art of battery manufacturing.

[0120] The silicon subhalide-containing composite particles of the present invention are characterized by very good electrochemical behavior, resulting in lithium-ion batteries with high volumetric capacity and excellent performance characteristics. The composite particles of the present invention are permeable to lithium ions and electrons, thus enabling charge transport. The use of the silicon subhalide-containing composite particles of the present invention allows for a significant reduction in the amount of SEI in lithium-ion batteries. Additionally, due to the design of the composite particles of the present invention, the SEI no longer peels off from the surface of the composite particles of the present invention, or at least peels off to a much lesser extent. All of this results in high cycle stability of the corresponding lithium-ion batteries. Attenuation and scavenging can be minimized. Furthermore, the lithium-ion batteries of the present invention exhibit low initial and continuous loss of available lithium in the cell, and therefore high coulombic efficiency.

[0121] In the following examples, all amounts and percentages are by weight, all pressures are 0.10 MPa (absolute) and all temperatures are 20° C., unless otherwise specified in each case. [Example]

[0122] pH is measured in accordance with ASTM Standard No. D1512, Method A.

[0123] Scanning electron microscopy (SEM / EDX): Microscopic analysis was carried out using a Zeiss Ultra 55 scanning electron microscope and an energy-dispersive Oxford X-Max 80N X-ray spectrometer. Prior to analysis, samples were subjected to carbon deposition using a Safematic Compact Coating Unit 010 / HV to prevent charging phenomena. Cross sections of silicon-containing materials were prepared using a Leica TIC 3X ion cutter at 6 kV.

[0124] Inorganic / elemental analysis: Carbon content was measured using a Leco CS 230 analyzer, and a Leco TCH-600 analyzer was used to measure oxygen and nitrogen content. Qualitative and quantitative determination of other elements, especially alkali or alkaline earth metals, was performed by inductively coupled plasma (ICP) optical emission spectrometry (Optima 7300 DV, Perkin Elmer). For this purpose, samples were subjected to acid digestion (HF / HNO3) in a microwave (Microwave 3000, Anton Paar). ICP-OES measurements were guided by ISO 11885 "Water quality - Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885:2007)," the German equivalent of EN ISO 11885:2009, which is used for the analysis of acidic aqueous solutions (e.g., acidified drinking water, wastewater and other water samples, aqua regia extracts of soils and sediments).

[0125] X-ray fluorescence analysis: The chlorine content was measured by X-ray fluorescence analysis on a Bruker AXS SB Tiger 1 with a rhodium anode.

[0126] For this purpose, 5.00 g of sample was mixed with 1.00 g of Boreox and 2 drops of ethanol and compressed into tablets in a Herzog HP 40 tablet press at a pressure of 150 kN for 15 seconds.

[0127] Particle size measurement: Particle size distributions are measured according to ISO 13320 by static laser scattering using a Horiba LA 950. Particular care must be taken during sample preparation to ensure that the size of individual particles, and not the size of weak agglomerates, is measured. For the materials considered here, these were dispersed in ethanol. For this purpose, the dispersions were sonicated at 250 W in a Hielscher UIS250v ultrasonic laboratory instrument with an LS24d5 sonotrode for 4 minutes before measurement, if necessary.

[0128] BET surface area measurements: 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 using nitrogen) using a Sorptomatic 199090 instrument (Porotec) or a BELSorp MAX II instrument (Microtrac) or a SA-9603MP instrument (Horiba).

[0129] Bone Density: The skeletal density, i.e. the density of the porous solid based on the volume of the pore space only accessible to external gas, was determined by helium pycnometry according to DIN 66137-2.

[0130] Gas-accessible pore volume (Grbic pore volume): The Grbic gas-accessible pore volume was determined by gas adsorption measurements with nitrogen according to DIN 66134.

[0131] PD50 pore diameter: The PD50 pore diameter was calculated as the volume-average pore diameter based on the total volume of micropores defined by the Horvath-Kawazoe method according to DIN 66135 and mesopores defined by the BJH method according to DIN 66134.

[0132] The following Examples 1-6 and Comparative Example 1 describe the preparation and properties of porous carbon particles used in the production of silicon-carbon according to the present invention.

[0133] Production of silicon composite particles Comparative Example 1A (not of the invention): Silicon-carbon composite particles from porous carbon particles.

[0134] For the reaction, an electrically heated autoclave was used, consisting of a cylindrical lower part (cup) and a lid with a volume of 5.3 L and multiple connections (e.g., for gas inlet, outlet, temperature, and pressure measurements). The agitator employed was essentially a narrow-clearance helical agitator, with a height equivalent to approximately 50% of the clearance height inside the reactor. The helical agitator was designed to allow for direct temperature measurement within the bed. 342.5 g of porous carbon (specific surface area = 1617 m) was placed in the autoclave. 2 / g, Grbic pore volume = 0.80 cm 3The autoclave was first evacuated. Thereafter, it was pressurized with SiH4 (70 g) to a pressure of 16.0 bar at 350°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH4 (59 g) to a pressure of 16.0 bar at 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH4 (57 g) to a pressure of 16.0 bar at 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH (55 g) to a pressure of 16.0 bar at a temperature of 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH (54 g) to a pressure of 16.0 bar at a temperature of 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH (52 g) to a pressure of 16.0 bar at a temperature of 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes, and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar, and the autoclave was pressurized with SiH (51 g) to a pressure of 16.0 bar at a temperature of 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes and the temperature was maintained for 60 minutes. The pressure was then reduced to 1.5 bar and the autoclave was pressurized with SiH4 (29 g) to a pressure of 10.0 bar at a temperature of 370°C. The autoclave was then heated to a temperature of 420°C within 20 minutes and the temperature was maintained for 60 minutes. The autoclave was then cooled to a temperature of 100°C, after which it was purged five times with nitrogen, five times with lean air having an oxygen content of 5%, five times with lean air having an oxygen content of 10%, and then five times with air.

[0135] The pressure in the autoclave was reduced to 1 bar and then purged with nitrogen three times. Under an Ar atmosphere, 651 g of silicon-carbon composite particles in the form of a fine black solid were isolated.

[0136] Comparative Example 1B (not of the present invention): silicon subchloride-containing composite particles from porous carbon particles.

[0137] Into a tubular reactor, 3.0 g of porous carbon particles (specific surface area = 2140 m) in a quartz glass boat was added. 2 / g, Grbic pore volume = 1.01 cm 3 The reactor was filled with 1000kJ / g of trichlorosilane (liquid), pH = 5.4. After inerting with nitrogen, the reactor was heated to 450°C. Once the reaction temperature was reached, reactive gas (a mixture of 20 g / h of trichlorosilane (liquid) and 10 NL / h of Ar) was passed through the reactor for 24 hours. The reactor was then purged with inert gas, cooled to room temperature, and the product was removed.

[0138] [Example 1] Silicon subchloride-containing composite particles from porous carbon particles.

[0139] Into a tubular reactor, 3.0 g of porous carbon particles (specific surface area = 2140 m) in a quartz glass boat was added. 2 / g, Grbic pore volume = 1.01 cm 3 The reactor was filled with a 1000 ml / g solution of chlorosilane (liquid), pH = 5.4. After inerting with nitrogen, the reactor was heated to 450 °C. Once the reaction temperature was reached, reactive gas (a mixture of 20 g / h of trichlorosilane (liquid) and 10 NL / h of Ar) was passed through the reactor for 24 hours. The reactor was then purged with inert gas, cooled to room temperature, and the product was removed. The product was then suspended in water at 20 °C (30 ml water / 1 g of product), stirred for 10 minutes, and filtered through a Buchner funnel while measuring the pH. The entire procedure was repeated (typically 3-5 times) until the pH of the wash water was > 3.

[0140] [Example 2] Silicon-carbon composite particles from porous carbon particles.

[0141] Into a tubular reactor, 3.0 g of porous carbon particles (specific surface area = 2140 m) in a quartz glass boat was added. 2 / g, Grbic pore volume = 1.01 cm 3 The reactor was filled with 100 mL of HCl (10 mL / g, pH=5.4). After inerting with nitrogen, the reactor was heated to 415°C. Once the reaction temperature was reached, reactive gas (a mixture of 5 mL / h of dichlorosilane and 10 mL / h of Ar) was passed through the reactor for 15 hours. The reactor was then purged with inert gas, cooled to room temperature, and the product was removed. The product was then suspended in water at 20°C (30 mL of water / 1 g of product), treated in an ultrasonic bath at 80°C for 1 hour, and filtered through a Buchner funnel while measuring the pH. The entire procedure was repeated until the pH of the wash water was >3.

[0142] [Example 3] Silicon-carbon composite particles from porous carbon particles.

[0143] Into a tubular reactor, 3.0 g of porous carbon particles (specific surface area = 2140 m) in a quartz glass boat was added. 2 / g, Grbic pore volume = 1.01 cm 3 The reactor was filled with an inert gas (10% SiH4 in N2, 10 NL / h). After inerting with nitrogen, the reactor was heated to 380°C. Once the reaction temperature was reached, reactive gas 1 (a mixture of 33 g / h of trichlorosilane (liquid) and 10 NL / h of Ar) was passed through the reactor for 8 hours. Then reactive gas 2 (10% SiH4 in N2, 10 NL / h) was passed through the reactor for 9 hours. The reactor was then purged with inert gas, cooled to 20°C, and the product was removed.

[0144] [Example 4] Silicon-carbon composite particles from porous carbon particles.

[0145] Into a tubular reactor, 3.0 g of porous carbon particles (specific surface area = 2140 m) in a quartz glass boat was added. 2 / g, Grbic pore volume = 1.01 cm 3 After inerting with nitrogen, the reactor was heated to 380°C. Once the reaction temperature was reached, Reactive Gas 1A mixture of 5 NL / h dichlorosilane and 10 NL / h Ar was passed through the reactor for 15 hours. The reactor was then heated to 400°C. Once the reaction temperature was reached, Reactive Gas 2 (10% SiH in N, 10 NL / h) was passed through the reactor for 7.6 hours, after which the reactor was purged with inert gas, cooled to room temperature, and the product was removed.

[0146] [Example 5] Silicon-carbon composite particles from porous carbon particles by reaction in a pressure reactor.

[0147] For the reaction, an electrically heated autoclave was used, consisting of a cylindrical lower part (cup) and a lid with a volume of 594 ml and multiple connections (e.g., for gas inlet, outlet, temperature, and pressure measurements). The agitator employed was essentially a narrow-clearance helical agitator, with a height equivalent to approximately 50% of the clearance height inside the reactor. The helical agitator was designed to allow direct temperature measurement within the bed. The autoclave was filled with porous carbon (specific surface area = 2010 m). 2 / g, Grbic pore volume = 0.95 cm 3 The autoclave was first evacuated. It was then pressurized to a pressure of 15.1 bar with DCS (1 g) and SiH4 (15 g). The autoclave was then heated to a temperature of 420°C within 90 minutes, and the temperature was maintained for 210 minutes. Over the course of the reaction, the pressure rose to 74 bar. The autoclave was cooled to room temperature (20°C) within 12 hours. After cooling, a pressure of 33.5 bar remained in the autoclave. The pressure in the autoclave was reduced to 1 bar, and then purged three times with nitrogen. Under an Ar atmosphere, 20.8 g of silicon-carbon composite particles in the form of a black, fine solid were isolated. After replacing the Ar atmosphere with air, the product was suspended in water (30 ml / 1 g of product), treated in an ultrasonic bath at 80°C for 1 hour, and filtered through a Buchner funnel while measuring the pH. The entire procedure was repeated until the pH of the wash water was >3.

[0148] The reaction conditions for the preparation and material properties of the silicon-carbon composite particles are summarized in Table 2 below.

[0149] [Table 1]

[0150] Regardless of the silicon precursor employed, the same material properties are obtained.

[0151] Evaluation of silicon-carbon composite particles in electrochemical cells Comparative Example 7: Anode containing non-inventive silicon-carbon composite particles from Comparative Example 1A and electrochemical testing in a lithium ion battery.

[0152] 29.71 g of polyacrylic acid (dried to constant weight at 85°C, Sigma-Aldrich, Mw approx. 450,000 g / mol) and 756.60 g of deionized water were stirred on a shaker (290 rpm) for 2.5 hours until the polyacrylic acid was completely dissolved. Lithium hydroxide monohydrate (Sigma-Aldrich) was added to the solution in small increments until the pH reached 7.0 (measured using a WTW pH 340i pH meter and a SenTix RJD probe). The solution was then mixed on a shaker for an additional 4 hours. 3.87 g of the neutralized polyacrylic acid solution and 0.96 g of graphite (Imerys, KS6L C) were first charged into a 50 ml container and blended at 2000 rpm in a planetary mixer (SpeedMixer, DAC 150 SP). Subsequently, 3.40 g of silicon-carbon composite particles according to the present invention from Example 1A were added and stirred at 2000 rpm for 1 minute. Then, 1.21 g of 8 percent conductive carbon black dispersion and 0.8 g of deionized water were added and incorporated using a planetary mixer at 2000 rpm. This was followed by dispersion using a dissolver at 3000 rpm at a constant 20° C. for 30 minutes. Degassing of the ink was carried out again using a planetary mixer under vacuum at 2500 rpm for 5 minutes.

[0153] The finished dispersion was then applied to a 0.03 mm thick copper foil (Schlenk Metallfolien, SE-Cu58) using a film stretching frame (Erichsen, model 360) with a gap clearance of 0.1 mm. The anode coating thus produced was then dried for 60 minutes at 60°C and 1 bar air pressure. The average basis weight of the dried anode coating was 2.2 mg / cm. 2 , coating density is 0.9g / cm 3 It was.

[0154] Electrochemical studies were carried out using a two-electrode button cell (type CR2032, Hohsen Corp.). The electrode coating was used as the counter or negative electrode (Dm = 15 mm) with a content of 94.0% and a concentration of 15.9 mg / cm. 2 A coating based on lithium-nickel-manganese-cobalt oxide 6:2:2 (obtained from SEI) with an average basis weight of 1000 kJ / cm2 was used as the working electrode, i.e., the positive electrode (D = 15 mm). A glass fiber filter paper (Pall, GF type A / E) soaked with 60 μl of electrolyte was used as the separator (D = 16 mm). The employed electrolyte consisted of a 1.0 molar solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of fluoroethylene carbonate and diethyl carbonate. Cell construction was performed in a glove box (<1 ppm H2O, O2), and the moisture content of all employed components was less than 20 ppm in dry matter.

[0155] Electrochemical tests were performed at 22 °C. The cells were charged by the cc / cv (constant current / constant voltage) method at a constant current of 15 mA / g (equivalent to C / 10) in the first cycle and 75 mA / g (equivalent to C / 2) in subsequent cycles. Once the voltage limit of 4.2 V was reached, the cells were charged at a constant voltage until the current dropped below 1.5 mA / g (equivalent to C / 100) or 3 mA / g (equivalent to C / 50). The cells were discharged by the cc (constant current) method at a constant current of 15 mA / g (equivalent to C / 10) in the first cycle and 75 mA / g (equivalent to C / 2) in subsequent cycles until the voltage limit of 2.5 V was reached. The specific current selected was based on the weight of the positive electrode coating. The electrodes were selected to establish a cathode:anode capacity ratio of 1:1.2.

[0156] Comparative Example 8: Anode containing non-inventive silicon-carbon composite particles from Comparative Example 1B and electrochemical testing in a lithium ion battery.

[0157] The non-inventive silicon-containing material from Comparative Example 1B was used to prepare the anode described in Comparative Example 7. The anode was installed in a lithium ion battery as described in Comparative Example 7 and tested according to the same procedure.

[0158] Comparative Example 9: Anode containing non-inventive silicon-carbon composite particles from Comparative Example 1C and electrochemical testing in a lithium ion battery.

[0159] The non-inventive silicon-carbon composite particles from Comparative Example 1C were used to prepare an anode as described in Comparative Example 7. The anode was installed in a lithium ion battery as described in Comparative Example 7 and tested according to the same procedures.

[0160] [Example 10] Anode containing silicon-carbon composite particles from Example 3 and electrochemical testing in a lithium ion battery.

[0161] The silicon-containing material according to the present invention from Example 3 was used to prepare the anode described in Comparative Example 7. The anode was installed in a lithium ion battery as described in Comparative Example 7 and tested according to the same procedure.

[0162] The results of the electrochemical evaluation are summarized in Table 3 below.

[0163] [Example 11] Anode containing silicon-carbon composite particles from Example 1 and electrochemical testing in a lithium ion battery.

[0164] The silicon-containing material according to the present invention from Example 1 was used to prepare the anode described in Comparative Example 7. The anode was installed in a lithium ion battery as described in Comparative Example 7 and tested according to the same procedure.

[0165] The results of the electrochemical evaluation are summarized in Table 3 below.

[0166] [Table 2]

[0167] A comparison of Comparative Example 7 with Example 10 according to the invention reveals that the presence of chlorine content in the material does not adversely affect the electrochemical performance. A comparison of Comparative Example 8 with Example 11 according to the invention reveals that an excessively low pH adversely affects the electrochemical performance of the battery, while adapting the pH stabilizes the performance.

Claims

1. A silicon subhalide-containing composite particle for use in an anode of a lithium ion battery, comprising:

1. Si content >30% by weight, 2. Silicon disposed within and on the pores of a porous carbon matrix; 3. A halogen concentration of 0.0003 to 16 wt. %; 4. pH 3-9, 5. A volume-weighted particle size distribution with a diameter percentile d50 between 0.5 and 20 μm; and 6. Specific BET surface area up to 170 m2 / g The silicon subhalide-containing composite particles have the following formula:

2. The halogen is chlorine, having a Cl concentration of 0.0003 to 16 wt. %; The composite particle according to claim 1 .

3. 3. Composite particles according to claim 1 or 2, in which the silicon is present at least partly in the form of silicon subchloride SiClx, where x=0.00001 to 0.

15.

4. Composite particles according to any one of claims 1 to 3, comprising at least 30% by weight of silicon obtained by silicon infiltration.

5. 5. A method for producing composite particles according to any one of claims 1 to 4 by silicon infiltration from silicon precursors selected from halogen-containing and halogen-free silicon precursors which are gaseous and / or liquid at 20°C and 1013 mbar, wherein at least one halogen-containing silicon precursor is 1. A volume-weighted particle size distribution having a diameter percentile d50 of 0.5 to 20 μm; 2. The total pore volume of micropores and mesopores (Grbic pore volume) measured by N2 adsorption in the range of 0.4 to 2.2 cm3 / g, and 3. PD50 pore diameter as measured by N2 adsorption of 30 nm or less in the presence of porous particles having

6. 6. The method of claim 5, wherein the silicon infiltration is carried out in a reactor selected from a fluidized bed reactor, a rotary kiln arranged in a horizontal to vertical position, an open or closed fixed bed reactor, and a pressure reactor.

7. 7. The method according to claim 5 or 6, wherein the silicon infiltration is carried out at a temperature of 280°C to 900°C.

8. The method according to claims 5 to 7, wherein the composite particles are produced by silicon infiltration from a silane selected from monosilanes and chlorine-containing silanes, and at least one chlorine-containing silane is employed.

9. The method of claims 5 to 8, wherein a silicon-free reactive component is also present in admixture with or alternating with the silicon precursor.

10. An anode material for a lithium ion battery containing the silicon subhalide composite particles according to claims 1 to 4.

11. An anode comprising a current collector coated with the anode material of claim 10.

12. A lithium ion battery comprising at least one anode containing the silicon subhalide-containing composite particles of claims 1-4.

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