Silicon-containing material

Abstract

The present invention relates to a silicon-containing material based on one or more porous particles and silicon, said silicon being located in the pores and on the surface of the porous particles, the silicon-containing material having a surface area of ​​up to 50 m, as determined by nitrogen sorption and BET evaluation. 2 / g, and the porous particles are characterized by having a) an average electrical particle resistance of at least 2 kΩ, and b) a reversible delithiation capacity β of at most 100 mAh / g.

Description

Technical Field

[0001] The present invention relates to a silicon-containing material based on porous particles and silicon, a method for producing the same, and its use as a negative electrode active material of a lithium-ion battery.

Background Art

[0002] Lithium-ion batteries are currently the most practical electrochemical energy storage devices with the highest energy density as a current storage medium. Lithium-ion secondary batteries are mainly used in the fields of portable electronic devices, tools, and electric transportation means such as bicycles, scooters, and automobiles. Currently, graphite carbon is widely used as the active material of the negative electrode (anode) of the corresponding battery. However, such graphite carbon has the disadvantage of relatively low electrochemical capacity, and theoretically, it is at most 372 mAh per gram of graphite, which is only about one-tenth of the electrochemical capacity that can be theoretically achieved with lithium metal. As alternative active materials for the negative electrode, there are those containing silicon as described in, for example, European Patent 1730800 B1, US Patent 10,559,812 B2, US Patent 10,819,400 B2, and European Patent 3335262 B1. Silicon forms a binary electrochemically active alloy with lithium, enabling a very high electrochemically achievable lithium content of up to 3579 mAh per gram of silicon (M. Obrovac, V.L. Chevrier Chem. Rev. 2014, 114, 11444).

[0003] The incorporation and removal of lithium ions into and from silicon are accompanied by the disadvantage of very large volume changes. Such volume changes impose severe mechanical stress on the active material containing silicon, and as a result, the active material may ultimately become powder. This process is also called electrochemical pulverization, in which the electrical contact between the active material and the electrode structure is lost, and the capacity of the electrode is continuously and irreversibly lost.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the components of the electrolyte to continuously form a passivation protective layer (solid electrolyte interface phase: SEI). The formed components are no longer electrochemically active. The lithium bound thereto becomes unavailable in the system, resulting in a continuous and significant decrease in battery capacity. Due to the extreme volume change of silicon during the charge and discharge process of the battery, the SEI ruptures periodically, exposing the unoccupied surface of the silicon-containing active material further, and more SEI is formed. Since the amount of mobile lithium in the full cell corresponding to the available capacity is limited by the cathode material, the cathode material is gradually consumed, and the cell capacity decreases to an unacceptable level within just a few cycles in terms of application.

[0005] The decrease in capacity during repeated charge and discharge cycles is also called fading or continuous capacity decline and is usually irreversible.

[0006] A series of silicon-carbon composite particles have been described as an active material for the anode of a lithium-ion battery, where silicon is incorporated into porous carbon particles starting from a gaseous or liquid precursor. For example, U.S. Patent 10,147,950 B2 describes depositing silicon from monosilane SiH4 into porous carbon in a high-temperature tubular furnace or equivalent furnace type at 300 - 900 °C, preferably with stirring of the particles, by a CVD (chemical vapor deposition) or PE-CVD (plasma-enhanced chemical vapor deposition) process. A similar procedure is described in U.S. Patent 10,424,786 B1, where the silicon precursor is introduced as a mixture with an inert gas at a total pressure of 1.013 bar. International Publication No. WO 2012 / 097969 describes depositing ultrafine silicon particles of 1 - 20 nm by heating silane as a silicon precursor on a porous carbon support at 200 - 950 °C. To prevent aggregation of the deposited silicon particles and formation of a thick layer, silane is diluted with an inert gas, and the deposition is carried out in a pressure range of 0.1 - 5 bar.

[0007] The silicon-containing materials available from the processes described above are common in that when the silicon-containing material is used as the active material of the negative electrode for a lithium-ion battery, in addition to silicon, carbon also contributes to some extent to the electrochemical capacity of the silicon-containing material. In many cases, since the carbon used is in an amorphous structure, an uneven amount of lithium remains in the silicon-containing material during the electrochemical cycle within a limited potential difference. Especially in the case of applications to mobile phones, the theoretically possible range cannot be fully covered and it cannot be used for further cycles (trapping). Therefore, the full capacity cannot be utilized, and it is disadvantageous to use the known silicon-containing materials for such applications.

[0008] Furthermore, the deposition of silicon at temperatures exceeding about 800 °C has the drawback that it is only possible within a limited range. This is because the formation of silicon carbide can occur due to the high reactivity of amorphous carbon with respect to the gaseous silicon precursor. Unlike silicon, silicon carbide cannot be used for the electrochemical storage of lithium ions, and thus may significantly reduce the lithium-ion storage capacity of the silicon-containing material. Furthermore, at such high temperatures, there is a risk that at least part of the porosity of the porous particles is lost due to the sintering process.

[0009] U.S. Patent 9,005,818 B2 describes a silicon-containing negative electrode active material for a lithium-ion battery obtained by depositing silicon from a gaseous silicon precursor onto a mesoporous silicon dioxide matrix. The product thus obtained contains silicon in an amount of 0.05 to 100% based on the weight of the mesoporous silicon dioxide matrix, and has a pore volume of 0.2 to 0.5 ml / g and a BET surface area of 150 to 1000 m 2 / g as determined by nitrogen adsorption. The initial Coulombic efficiency and cycle stability of the corresponding lithium-ion battery are still not satisfactory. SUMMARY OF THE INVENTION

[0010] Against such a background, when used as a negative electrode active material of a lithium ion secondary battery, it is an object to provide a silicon-containing material that causes little initial and continuous loss of lithium available in the cell, and thus enables high coulombic efficiency and further stable electrochemical behavior in subsequent cycles. It is desirable that fading and trapping be as small as possible.

[0011] Surprisingly, the object of the present invention can be achieved by using one or more porous particles and a silicon-based silicon-containing material, wherein the silicon is disposed within the pores and on the surface of the porous particles, and the silicon-containing material has a specific surface area of at most 50 m 2 / g as determined by nitrogen sorption and BET evaluation, and the porous particles are characterized by having an average electrical particle resistance of at least 2 kΩ and a reversible delithiation capacity β of at most 100 mAh / g. Generally, for example, since it has an electron conductive layer of carbon having a very low electron resistance, an active material for a lithium ion secondary battery having low electron conductivity and thus high electrical particle resistance is particularly surprising. This is known, for example, from lithium iron phosphate used as a positive electrode active material in European Patent Application Publication No. 3678990A1 or silicon monoxide SiOx used as a negative electrode active material in European Patent 1323783B1. In this regard, generally, the average particle resistance of the porous particles as a starting material of a silicon-containing material used as a negative electrode active material of a lithium ion battery should be less than 2 kΩ in order to fully utilize the capacity of such a silicon-containing material and the required conductivity in the electrode. Generally, the particle resistivity of porous carbon is thus low. In contrast, surprisingly, even when the average electrical particle resistance of the porous particles is 2 kΩ or more, it has been found that the electrical conductivity of the resulting silicon-containing material is sufficient to enable the use of the full capacity in applications as a negative electrode active material of a lithium ion battery.

[0012] The present invention relates to a silicon-containing material based on one or more porous particles and silicon, wherein the silicon is disposed within pores and on the surface of the porous particles, and the silicon-containing material has a maximum specific surface area of 50 m 2 / g as determined by nitrogen sorption and BET evaluation, and the porous particles are characterized by having the following. a) An average electrical particle resistance of at least 2 kΩ, and b) A reversible delithiation capacity β of at most 100 mAh / g.

[0013] The porous particles that can be used in the silicon-containing material can be any material, and the particles have an average electrical particle resistance of at least 2 kΩ and a reversible delithiation capacity β of at most 100 mAh / g, preferably 0 to 100 mAh / g, particularly preferably 2 to 80 mAh / g.

[0014] In the present invention, 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 the following component formula: Al a B b C c Mg d N e O f Si g (where 0 ≤ a, b, c, d, e, f, g ≤ 1, but at least two of the coefficients a to g are >0, and a×3 + b×3 + c×4 + d×2 + g×4 ≥ e×3 + f×2.) Other ceramic materials that can be represented as such are preferred.

Embodiments for Carrying Out the Invention

[0015] The ceramic material can be, for example, a binary, ternary, quaternary, quinary, senary, or septenary compound. Ceramic materials having the following component formulas are preferably used. Non-stoichiometric boron nitride BNz (where z = 0.2 to 1), Non-stoichiometric carbonitride CNz (where z = 0.1 to 4 / 3) Boron carbonitride BxCNz (where x = 0.1 to 20, z = 0.1 to 20, x×3 + 4 ≥ z×3), Boron nitride-based oxide BNzOr (where z = 0.1 to 1, r = 0.1 to 1, 3 ≥ r×2 + z×3), Boron carbonitride oxide BxCNzOr (where x = 0.1 to 2, z = 0.1 to 1, r = 0.1 to 1, x×3 + 4 ≥ r×2 + z×3, Silicon carbon oxide SixCOz (where x = 0.1 to 2, z = 0.1 to 2, x×4 + 4 ≥ z×2, Silicon carbonitride SixCNz (where x = 0.1 to 3, z = 0.1 to 4, x×4 + 4 ≥ z×3, Silicon boron carbonitride SiwBxCNz (where w = 0.1 to 3, x = 0.1 to 2, z = 0.1 to 4, w×4 + x×3 + 4 ≥ z×3, Silicon boron carbon oxide SiwBxCOz (where w = 0.10 to 3, x = 0.1 to 2, z = 0.1 to 4, w×4 + x×3 + 4 ≥ z×2), Silicon boron carbonitride oxide SivBwCNxOz (where v = 0.1 to 3, w = 0.1 to 2, x = 0.1 to 4, z = 0.1 to 3, v×4 + w×3 + 4 ≥ x×3 + z×2, u = 0.1 to 2, v = 0.1 to 2, w = 0.1 to 4, x = 0.1 to 2, z = 0.1 to 3, u×3 + v×3 + x×4 + 4 ≥ w×3 + z×2)

[0016] Preferred porous particles are mixed materials based on silicon dioxide, boron nitride, silicon carbide, silicon nitride, or compounds thereof, particularly mixed materials based on silicon dioxide or boron nitride.

[0017] Particularly preferred porous particles are porous boron nitride particles, particularly porous silicon oxide particles, and particularly nanoporous silicon oxide particles are preferred.

[0018] The synthesis of porous particles can generally be carried out based on sol-gel synthesis. For example, for silica gel, aerogel or xerogel, it is described in M. Kato, K. Sakai-Kato, T Toyo'oka, J. Sep. Science, 2005, 28, 1893-1908. SiO2 materials having a pore structure of 10 nm or less and at the same time a high pore volume are preferably prepared using a sol-gel process using very small basic units (SiO2 particles, polyhedral oligomeric silsesquioxane (POSS) units). The pore characteristics can be adjusted, for example, by reaction conditions such as temperature, type of catalyst, concentration, etc., and by silane functionalization. Other influencing factors include, for example, post-treatments such as gel drying conditions and annealing. A pore diameter of less than 100 nm and a porosity of 90% or more can be achieved, for example, by supercritical drying of the gel. Xerogel having a pore diameter of 10 nm or less can also be obtained by convective drying.

[0019] The porous particles preferably have a density determined by helium pycnometry of 0.1 to 7 g / cm 3 , particularly preferably 0.3 to 3 g / cm 3 . This is advantageous for increasing the weight capacity (mAh / cm 3 ) of the lithium ion battery.

[0020] The porous particles preferably have a volume-weighted particle size distribution with a diameter percentile d 50 of ≧0.5 μm, particularly preferably ≧1.5 μm, and most preferably ≧2 μm. The diameter percentile d 50 is preferably ≦20 μm, more preferably ≦12 μm, and most preferably ≦8 μm.

[0021] The volume-weighted particle size distribution of the porous particles preferably has a diameter percentage d 10 of ≧0.2 μm to d 90 of ≦20.0 μm, particularly preferably d 10 of ≧0.4 μm to d 90 of ≦15.0 μm, and most preferably d 10 of ≧0.6 μm to d 90It is ≤ 12.0 μm.

[0022] The porous particles preferably have a volume-weighted particle size distribution with a diameter percentile d of ≤ 10 μm, particularly preferably ≤ 5 μm, particularly preferably ≤ 3 μm, and most preferably ≤ 2 μm. 10 The diameter percentile d 10 is preferably ≥ 0.2 μm, particularly preferably ≥ 0.5 μm, and most preferably ≥ 1 μm.

[0023] The porous particles preferably have a volume-weighted particle size distribution with a diameter percentile d of ≥ 4 μm, particularly preferably ≥ 8 μm. 90 The diameter percentile d 90 is preferably ≤ 18 μm, more preferably ≤ 15 μm, and most preferably ≤ 13 μm.

[0024] 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, particularly 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, and most preferably ≥ 1.0 μm 90 -d 10 The volume-weighted particle size distribution can be measured by a static laser scattering method using the Mie model with ethanol as the dispersion medium for the porous particles and a Horiba LA 950 measuring device in accordance with ISO 13320.

[0025] The volume-weighted particle size distribution can be measured by a static laser scattering method using the Mie model with ethanol as the dispersion medium for the porous particles and a Horiba LA 950 measuring device in accordance with ISO 13320.

[0026] The porous particles may be, for example, isolated or aggregated. The porous particles are preferably non-aggregates, and preferably non-aggregates. Aggregation generally means that in the process of manufacturing the porous particles, primary particles are first formed and grow together and / or the primary particles are linked to each other via, for example, covalent bonds to form aggregates in this way. The primary particles are generally isolated particles. Aggregates or isolated particles may form aggregates. An aggregate is a loose aggregate of aggregates or primary particles bonded to each other via, for example, van der Waals interactions or hydrogen bonds. Aggregated aggregates can be easily divided into aggregates again by a general kneading process or dispersion process. Aggregates can only be partially decomposed into primary particles in such processes. The presence of porous particles in the form of aggregates, agglomerates or isolated particles can be visualized, for example, using a conventional scanning electron microscope (SEM). In contrast, in the static light scattering method for determining the particle size distribution or particle diameter of matrix particles, aggregates cannot be distinguished from each other.

[0027] The porous particles may have any form, for example, they may be divided, flaky, spherical or needle-shaped, and divided or spherical particles are preferred.

[0028] According to Wadell's definition, the sphericity φ is the ratio of the surface area of a sphere with the same volume to the actual surface area. According to this definition, the porous particles preferably have a sphericity φ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0029] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle projected onto the surface to the measured value U of the circumference of this projection (S = 2√πA / U). In the case of ideal circular particles, S becomes the value 1. In the case of porous particles, the sphericity S is preferably in the range of 0.5 to 1.0, particularly preferably 0.65 to 1.0, based on the percentiles S10 to S90 of the sphericity distribution. The measurement of the sphericity S is performed, for example, by referring to a micrograph of individual particles using an optical microscope, or in the case of particles less than 10 μm, preferably by using a scanning electron microscope with a graph evaluation using image analysis software such as ImageJ.

[0030] The porous particles preferably have a pore volume accessible to gas of ≧0.2 cm 3 / g, particularly preferably ≧0.6 cm 3 / g, most preferably ≧1.0 cm 3 / g. This is advantageous for obtaining a high-capacity lithium-ion battery. The gas-adsorbable pore volume is determined by gas adsorption measurement with nitrogen in accordance with DIN 66134.

[0031] The porous particles are preferably open pores. Open pores generally mean that the pores communicate with the particle surface via, for example, flow paths, preferably exchange substances with the environment, and particularly can exchange gaseous compounds. This can be demonstrated by gas sorption measurement (analysis according to Brunauer, Emmett and Teller, "BET"), i.e., by specific surface area.

[0032] The porous particles preferably have a specific surface area of ≧50 m 2 / g, particularly preferably ≧500 m 2 / g, most preferably ≧1000 m 2 / g. The BET specific surface area is measured in accordance with DIN 66131 (using nitrogen).

[0033] The pores of the porous particles may have any diameter, generally in the range of macropores (50 nm or more), mesopores (2 - 50 nm), and micropores (less than 2 nm). The porous particles can be used as any mixture of different pore types. Preferably, based on the total pore volume, porous particles having up to 30% macropores, particularly preferably porous particles having no macropores, and particularly preferably porous particles having at least 50% pores with an average pore diameter of less than 5 nm are used. The porous particles particularly preferably have only pores with a pore diameter of less than 2 nm (Determination method: In the mesopore range, the pore size distribution according to BJH (gas adsorption) in accordance with DIN 66134, in the micropore range, the pore size distribution according to Horvath - Kawazoe (gas adsorption) in accordance with DIN 66135; the pore size distribution in the macropore range is evaluated by mercury porosimetry in accordance with DIN ISO 15901 - 1).

[0034] Preferably less than 0.3 cm 3 / g, particularly preferably less than 0.15 cm 3 / g of the porous particles having a pore volume inaccessible to gas. This can also be used to increase the capacity of a lithium - ion battery. The gas - impermeable pore volume can be determined by the following formula. Gas - impermeable pore volume = 1 / pure substance density - 1 / skeletal density

[0035] Here, the pure substance density is the theoretical density of the material based on the phase composition or the density of the pure substance (assuming no closed pores). Data on the pure substance density can be found by those skilled in the art, for example, from the ceramic data portal site of the National Institute of Standards and Technology (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd) in the United States. For example, the pure substance density of silicon dioxide SiO2 is 2.203 g / cm 3 3, the pure substance density of boron nitride BN is 2.25 g / cm 3 3, the pure substance density of silicon nitride Si3N4 is 3.44 g / cm 3 3, and the pure substance density of silicon carbide SiC is 3.21 g / cm3 It is. The skeletal density is the actual density (gas permeability) of the porous particles measured by helium pycnometry.

[0036] For clarity, it should be noted that the porous particles are different from the silicon-containing material. The porous particles function as a starting material for producing the silicon-containing material. Generally, there is no silicon, preferably silicon, and more particularly silicon obtained by deposition of a silicon precursor, in the pores of the porous particles and on the surface of the porous particles.

[0037] The silicon-containing material obtained by deposition of silicon in the pores and on the surface of the porous particles preferably has a volume-weighted particle size distribution with a diameter percentile d 50 in the range of 0.5 to 20 μm. d 50 The value is preferably at least 1.5 μm, particularly preferably at least 2 μm. The diameter percentile d 50 is preferably at most 13 μm, particularly preferably at most 8 μm.

[0038] The volume-weighted particle size distribution of the silicon-containing material preferably has a diameter percentile d 10 ≥ 0.2 μm to d 90 ≤ 20.0 μm, and particularly preferably d 10 ≥ 0.4 μm to d 90 ≤ 15.0 μm, and most preferably d 10 ≥ 0.6 μm to d 90 ≤ 12.0 μm.

[0039] The silicon-containing material preferably has a volume-weighted particle size distribution with a diameter percentile d 10 ≤ 10 μm, particularly preferably ≤ 5 μm, particularly preferably ≤ 3 μm, and most preferably ≤ 1 μm. The diameter percentile d 10 is preferably ≥ 0.2 μm, particularly preferably ≥ 0.4 μm, and most preferably ≥ 0.6 μm.

[0040] The silicon-containing material preferably has a diameter percentile d 90 ≥ 5 μm, particularly preferably ≥ 10 μm.It has a volume-weighted particle size distribution. The diameter percentile d 90 is preferably ≦ 20.0 μm, particularly preferably ≦ 15.0 μm, and most preferably ≦ 12.0 μm.

[0041] The volume-weighted particle size distribution of the silicon-containing material preferably has a width d of ≦ 15.0 μm, particularly preferably ≦ 12.0 μm, more preferably ≦ 10.0 μm, particularly preferably ≦ 8.0 μm, and most preferably ≦ 4.0 μm 90 -d 10 and has. The volume-weighted particle size distribution of the silicon-containing material preferably has a width d of ≧ 0.6 μm, particularly preferably ≧ 0.7 μm, and most preferably ≧ 1.0 μm 90 -d 10 and has.

[0042] The silicon-containing material is preferably in the form of particles. The particles may be isolated or aggregated. The silicon-containing active material is preferably non-aggregated and preferably non-aggregated. The terms isolated, aggregated, and non-aggregated have already been defined above with respect to porous particles. The presence of a silicon-containing material in the form of an aggregate or agglomerate can be visualized, for example, using a conventional scanning electron microscope (SEM).

[0043] The silicon-containing material may have any form, for example, flaky, lamellar, spherical, or acicular, and flaky or spherical particles are preferred.

[0044] According to the definition of Wadell, the sphericity ψ is the ratio of the surface area of a sphere with the same volume to the actual surface area. According to this definition, the silicon-containing material preferably has a sphericity ψ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0045] The sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of the particle projected onto the surface to the measured value U of the circumference of this projection (S = 2√πA / U). In the case of an ideal circular particle, S becomes the value 1. In the case of a silicon-containing material, the sphericity S is preferably in the range of 0.5 to 1.0, particularly preferably in the range of 0.65 to 1.0, based on the percentiles S10 to S90 of the sphericity distribution. The measurement of the sphericity S is performed, for example, by referring to a micrograph of individual particles using an optical microscope, or in the case of particles less than 10 μm, preferably by using a scanning electron microscope with a graph evaluation using image analysis software such as ImageJ.

[0046] The cycle stability of the lithium-ion battery can be further improved by the morphology, material composition, particularly the specific surface area and internal porosity of the silicon-containing material.

[0047] The silicon-containing material preferably contains 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably 30 to 60% by weight, particularly preferably 40 to 50% by weight of porous particles based on the total weight of the silicon-containing material.

[0048] The silicon-containing material preferably consists of silicon obtained through deposition from a silicon precursor, in an amount of 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably 30 to 60% by weight, particularly preferably 40 to 50% by weight, based on the total weight of the silicon-containing material (determination is preferably by elemental analysis such as ICP-OES). When the porous particles consist of a silicon compound in the form of, for example, silicon dioxide, the above data can be determined in weight % by subtracting the mass of silicon in the porous particles determined by elemental analysis from the mass of silicon in the silicon-containing material determined by elemental analysis, and dividing the result by the mass of the silicon-containing material.

[0049] The volume of silicon present in the silicon-containing material obtained by deposition from a silicon precursor is calculated by dividing the mass fraction of silicon obtained by deposition from a silicon precursor in the total mass of the silicon-containing material by the density of silicon (2.336 g / cm 3) is divided by

[0050] The pore volume P of the silicon-containing material is obtained from the sum of the pore volume permeable to gas and the pore volume non-permeable to gas. According to Gurwitsch, the pore volume permeable to gas of the silicon-containing material can be determined by gas sorption measurement with nitrogen in accordance with DIN 66134.

[0051] The pore volume inaccessible to gas in the silicon-containing material can be determined by the following formula. Pore volume non-permeable to gas = 1 / pure substance density - 1 / skeletal density

[0052] The pure substance density of the silicon-containing material is the theoretical density obtained by multiplying the sum of the theoretical pure substance densities of the components contained in the silicon-containing material by their respective weight ratios in the whole material. The pure substance density is reported on the Ceramic Data Portal site of the National Institute of Standards and Technology (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). The determination of the skeletal density will be described later at the beginning of the description of the examples. For example, in the case of a material containing silicon, it is as follows. Pure substance density = theoretical pure substance density of silicon × ratio of silicon (weight %) + theoretical pure substance density of porous particles × ratio of porous particles (weight %)

[0053] The pore volume P of the silicon-containing material is preferably in the range of 0 to 400% by volume, more preferably in the range of 100 to 350% by volume, and particularly preferably in the range of 200 to 350% by volume, based on the volume of silicon present in the silicon-containing material obtained from the deposition from the silicon precursor.

[0054] The porosity of the silicon-containing material may be gas-permeable or gas-impermeable. The volume ratio of the gas-impermeable porosity to the gas-permeable porosity of the silicon-containing material can generally range from 0 (no gas-permeable pores) to 1 (all pores are gas-impermeable). The ratio of the gas-permeable porosity to the gas-permeable porosity of the silicon-containing material is preferably in the range of 0 to 0.8, more preferably 0 to 0.3, and particularly preferably 0 to 0.1.

[0055] The pores of the silicon-containing material can have any diameter in the range of, for example, macropores (50 nm or more), mesopores (2 - 50 nm), and micropores (less than 2 nm). The silicon-containing material may also be composed of any mixture of different pore types. Preferably, the silicon-containing material consists of at most 30% macropores based on the total pore volume, particularly preferably a silicon-containing material without macropores, and particularly preferably a silicon-containing material having at least 50% pores with an average pore diameter of less than 5 nm. Particularly preferably, the silicon-containing material consists only of pores with a diameter of at most 2 nm.

[0056] The silicon-containing material has a silicon structure with a structural size of preferably at most 1000 nm, more preferably less than 100 nm, and particularly preferably less than 5 nm in at least one dimension (determination method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)).

[0057] The silicon-containing material preferably consists of a silicon layer having a layer thickness of less than 1000 nm, more preferably less than 100 nm, and particularly preferably less than 5 nm (determination method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). The silicon-containing material can also contain 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 particularly preferably less than 5 nm (determination method: scanning electron microscope (SEM) and / or high-resolution transmission electron microscope (HR-TEM)). Data on the silicon particles preferably relate to the diameter of the circumference of the particles in the microscopic image.

[0058] The silicon-containing material has a specific surface area of at most 50 m 2 / g, preferably less than 30 m 2 / g, and particularly preferably less than 10 m 2 / g. The BET specific surface area is measured according to DIN 66131 (using nitrogen). When the silicon-containing material is used as a negative electrode active material for a lithium-ion secondary battery, the formation of the SEI can be reduced and the initial Coulombic efficiency can be improved.

[0059] 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, 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. Li and / or Sn are preferred. The content of the dopant in the silicon-containing material is preferably at most 1 wt%, particularly preferably at most 100 ppm, based on the total weight of the silicon-containing material, which can be determined by ICP-OES.

[0060] Silicon-containing materials generally exhibit surprisingly high stability under compressive loads and / or shear stresses. The pressure stability and shear stability of silicon-containing materials are demonstrated, for example, by the fact that the silicon-containing materials show no change or only minor changes in their porous structure in SEM under compressive loads (e.g., during electrode compression) or shear stresses (e.g., during electrode preparation).

[0061] In addition to porous particles, silicon deposited from a silicon precursor, and other additional elements, the silicon-containing material may generally contain other components. In particular, carbon may be present. In particular, carbon may be present in the form of a thin layer having a layer thickness of at most 1 μm, preferably less than 100 nm, particularly preferably less than 5 nm, particularly preferably less than 1 nm (determinable by SEM or HR-TEM). The carbon layer may be present, for example, on the surface of the pores and / or on the outer surface of the silicon-containing material. The order and number of different layers in the silicon-containing material are also arbitrary. For example, on the porous particles, there may first be a layer of another material different from the material of the porous particles, for example carbon, and on top of that, there may be a layer of silicon or a layer of silicon particles. Also, on the silicon layer or the silicon particle layer, regardless of whether there is a further layer of a material different from the material of the porous particles between the porous particles and the layer consisting of the silicon layer or the silicon particle layer, there may be a further layer of a material different from or the same as the material of the porous particles.

[0062] The silicon-containing material preferably contains ≦50 wt%, particularly preferably ≦40 wt%, particularly preferably ≦20 wt% of additional elements. The silicon-containing material preferably contains ≧1 wt%, particularly preferably ≧2 wt%, particularly preferably ≧3 wt% of additional elements. Wt% means the total weight of the silicon-containing material. In an alternative embodiment, the silicon-containing material does not contain additional elements.

[0063] The present invention also relates to a method for producing a silicon-containing material, in which one or more silicon precursors are pyrolyzed in the presence of one or more porous particles to deposit silicon in the pores and on the surface of the porous particles. The silicon-containing material has a specific surface area of at most 50 m 2 / g as determined by nitrogen sorption and BET evaluation, and the porous particles are characterized by having the following. a) An average electrical particle resistance of at least 2 kΩ, and b) A reversible delithiation capacity β of at most 100 mAh / g characterized by having.

[0064] The silicon-containing material can be produced in any reactor commonly used for the deposition of silicon from silicon precursors. Reactors selected from the group consisting of fluidized bed reactors, rotary kilns which can be in any configuration from horizontal to vertical, and fixed bed reactors which can be operated as open or closed systems, for example pressure reactors, are preferred. Particularly preferred is a reactor in which the porous particles and the silicon-containing material formed during deposition can be uniformly mixed with the silicon precursor. This is advantageous for the most homogeneous possible deposition of silicon into the pores and on the surface of the porous particles. The most preferred reactors are fluidized bed reactors, rotary kilns or pressure reactors, particularly fluidized bed reactors or pressure reactors.

[0065] Silicon is generally deposited from silicon precursors under pyrolysis. Preferred silicon precursors are monosilane SiH4, disilane Si2H6, and higher linear, branched or cyclic homologues, neopentasilane Si5H 12 , cyclohexasilane Si6H 12Silicon-hydrogen compounds such as; chlorine-containing silanes such as trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and higher-order linear, branched or cyclic homologues such as 1,1,2,2-tetrachlorodisilane Cl2HSi-SiHCl2; chlorinated and partially chlorinated oligosilanes and polysilanes, methylchlorosilanes such as trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylsilane MeH3Si, chlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or a mixture of the described silicon compounds. In particular, the silicon precursor is selected from the group consisting of monosilane SiH4, disilane Si2H6, trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and mixtures consisting of these silanes.

[0066] Furthermore, one or more reactive components may be introduced into the reactor. These examples are dopants based on boron, nitrogen, phosphorus, arsenic, germanium, iron or nickel-containing compounds. The dopant is preferably selected from the group consisting of ammonia (NH3), diborane (B2H6), phosphine (PH3), germane (GeH4), arsine (AsH3), and nickel tetracarbonyl (Ni(CO)4).

[0067] Further examples of reactive components are hydrogen or hydrocarbons, in particular aliphatic hydrocarbons having from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, such as methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane; unsaturated hydrocarbons having from 1 to 10 carbon atoms, such as ethylene, acetylene, propylene or butylene; isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, cyclooctadiene; cyclic unsaturated hydrocarbons such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene, norbornadiene, benzene, toluene, p-, m-, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane, naphthalene and other aromatic hydrocarbons; phenol, o-, m-, p-cresol, cymene, nitrobenzene, chlorobenzene, pyridine, anthracene, phenanthrene, myrcene, geraniol, thioterpineol and other aromatic hydrocarbons, norbornane, borneol, isoborneol, bornane, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anisole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, bishydroxymethylfuran, and various mixed fractions from natural gas condensates, petroleum distillates, coke oven condensates, fluid catalytic cracking units (FCC), steam crackers or the product streams of Fischer-Tropsch synthesis plants, or more generally various mixed fractions consisting of such compounds from hydrocarbonaceous material streams from wood, natural gas, petroleum and coal processing are mentioned.

[0068] The process of the invention is preferably carried out in an inert gas atmosphere, such as a nitrogen or argon atmosphere.

[0069] In all other respects, if the process of the invention requires routine adjustments customary to those skilled in the art, it can be carried out by conventional methods generally used for the deposition of silicon from silicon precursors.

[0070] The present invention further relates to the use of the silicon-containing material according to the invention as an active material of the negative electrode material of a lithium-ion battery, and to the use of the negative electrode according to the invention for manufacturing a lithium-ion battery.

[0071] The negative electrode material preferably comprises a mixture consisting of the silicon-containing material according to the 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.

[0072] The present invention further relates to a negative electrode material comprising a silicon-containing material, one or more binders, optionally graphite as a further active material, optionally one or more further conductive components, and optionally one or more additives.

[0073] By using other conductive components in the negative electrode material, the contact resistance within the electrode and between the electrode and the current collector can be reduced, and the energization capacity of the lithium-ion battery can be improved. Preferred further conductive components are conductive carbon black, carbon nanotubes, or metal particles such as copper.

[0074] The primary particles of the conductive carbon black preferably have a volume-weighted particle size distribution between a diameter percentile d 10 = 5 nm and d 90 = 200 nm. The primary particles of the conductive carbon black can branch like chains and form structures up to the size of micrometers. The carbon nanotubes preferably have a diameter of 0.4 to 200 nm, more preferably 2 to 100 nm, and most preferably 5 to 30 nm. The metal particles have a volume-weighted particle size distribution with a diameter percentile d 10 = 5 nm and d 90 = 800 nm.

[0075] The negative electrode material preferably contains 0 to 95% by weight, particularly preferably 0 to 40% by weight, and most preferably 0 to 25% by weight of one or more further conductive components based on the total weight of the negative electrode material.

[0076] The silicon-containing material can be present in the negative electrode for a lithium-ion battery, preferably in an amount of 5 to 100% by weight, more preferably 30 to 100% by weight, and most preferably 60 to 100% by weight, based on the total active material present in the negative electrode material.

[0077] As the binder, polyacrylic acid or its alkali metal salts, especially lithium salts or sodium salts, polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefin, polyimide, especially polyamideimide, or thermoplastic elastomer, especially ethylene-propylene-diene terpolymer can be preferably used. Particularly preferably, polyacrylic acid, polymethacrylic acid or cellulose derivatives, especially carboxymethyl cellulose. The alkali metal salts of the above-mentioned binders, especially lithium salts or sodium salts are also particularly preferred. Most preferred are the alkali metal salts of polyacrylic acid or polymethacrylic acid, especially lithium salts or sodium salts. All or preferably a proportion of the acid groups of the binder may be present in the form of salts. The binder preferably has a molar mass of 100,000 to 1,000,000 g / mol. A mixture of two or more binders can also be used.

[0078] The graphite used is generally natural graphite or synthetic graphite. The graphite particles preferably have a volume-weighted particle size distribution between a diameter percentile d 10 > 0.2 μm and d 90 < 200 μm.

[0079] Examples of additives include pore formers, dispersants, leveling agents, dopants such as elemental lithium, etc.

[0080] A preferred composition of the negative electrode material preferably comprises 5 to 95% by weight, particularly 60 to 90% by weight, of a silicon-containing material; 0 to 90% by weight, particularly 0 to 40% by weight, of a further conductive component; 0 to 90% by weight, particularly 5 to 40% by weight, of graphite; 0 to 25% by weight, particularly 5 to 20% by weight, of a binder; and optionally 0 to 80% by weight, particularly 0.1 to 5% by weight, of a further additive. Here, % by weight refers to the total weight of the negative electrode material, and the proportion of all components of the negative electrode material is 100% by weight.

[0081] The present invention further relates to a negative electrode comprising a current collector coated with the negative electrode material according to the present invention. This negative electrode is preferably used in a lithium-ion battery.

[0082] The constituent components of the negative electrode material can be processed into a negative electrode ink or paste, for example, in a solvent selected from the group consisting of water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide, and ethanol, 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.

[0083] The anode ink or paste preferably has a pH of 2 to 7.5 (measured at 20 °C using a WTW pH 340i pH meter with a SenTix RJD probe).

[0084] For example, the anode ink or paste can be knife-coated onto a copper foil or other current collector. Also, other coating methods such as spin coating, roller coating, dip coating, slot coating, brush coating, and spraying can be used in the present invention.

[0085] Before coating the copper foil with the negative electrode material according to the present invention, the copper foil may be treated with a commercially available primer, for example, one based on a polymer resin or silane. The primer improves the adhesion to copper, but generally has substantially no electrochemical activity itself.

[0086] The negative electrode material is preferably dried to a certain weight. The drying temperature depends on the components and solvents used. The drying temperature is preferably 20°C to 300°C, particularly preferably 50°C to 150°C.

[0087] The layer thickness, i.e., the dry layer thickness of the anode film, is preferably 2 μm to 500 μm, particularly preferably 10 μm to 300 μm.

[0088] Finally, the electrode coating can be calendered to achieve a defined porosity. The electrode thus produced preferably has a porosity of 15 to 85% determined by mercury porosimetry according to DIN ISO 15901-1. Preferably, 25 to 85% of the pore volume that can be determined by this method is provided by pores having a pore diameter of 0.01 to 2 μm.

[0089] The present invention further relates to a lithium-ion battery comprising an anode, a negative electrode, two conductive connections to the electrodes, a separator, an electrolyte in which the separator and the two electrodes are impregnated, and a housing for accommodating the specified components, wherein the negative electrode is made of a silicon-containing material according to the present invention.

[0090] In the context of the present invention, the term lithium-ion battery also includes cells. A cell generally consists of a positive electrode, a negative electrode, a separator, and an electrolyte. That is, in addition to one or more cells, a lithium-ion battery preferably also includes a battery management system. The battery management system is generally used to control the battery using, for example, an electronic circuit, and is particularly used for detecting the state of charge, deep discharge protection, and overcharge protection.

[0091] Preferred cathode materials used are lithium cobaltate, lithium nickelate, lithium nickel cobaltate (doped or undoped), lithium manganate (spinel), lithium nickel cobalt manganate, lithium nickel manganate, lithium iron phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium vanadium phosphate, or lithium vanadate.

[0092] The separator is preferably an ion-permeable electrical insulating film and is composed of polyolefin such as polyethylene (PE) or polypropylene (PP), or polyester or the corresponding laminate. The separator may be composed of a glass or ceramic material or coated with a glass or ceramic material as is common in battery manufacturing. As is well known, the separator separates the first electrode from the second electrode and prevents an electronic conductive connection (short circuit) between the electrodes.

[0093] The electrolyte is preferably a solution composed of one or more lithium salts (= conductive salts) in an aprotic solvent. The conductive salt is preferably selected from the group consisting of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium imide, lithium methide, LiCF3SO3, LiN(CF3SO2), and lithium borate. The concentration of the conductive salt is preferably between 0.5 mol / l and the solubility limit of the corresponding salt based on the solvent. Particularly preferably, it is 0.8 to 1.2 mol / l.

[0094] 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, γ-butyrolactone, dioxolane, acetonitrile, organic carbonates or nitriles, and can be used alone or as mixtures thereof.

[0095] The electrolyte preferably contains a film former such as vinylene carbonate or fluoroethylene carbonate. As a result, a remarkable improvement in the cycle stability of the negative electrode containing the silicon-containing material according to the present invention can be achieved. This is mainly due to the formation of a solid electrolyte interphase on the surface of the active particles. The proportion of the film former in the electrolyte is preferably 0.1 to 20.0% by weight, particularly preferably 0.2 to 15.0% by weight, and most preferably 0.5 to 10% by weight.

[0096] In order to optimally match the actual capacities of the electrodes of a lithium-ion battery as much as possible, it is advantageous to balance the amounts of the positive and negative electrode materials. From this perspective, it is particularly important that a coating layer is formed on the surface of the electrochemically active material of the negative electrode during the first or the first charge-discharge cycle (so-called formation) of a secondary lithium-ion battery. This outermost layer is called the "solid electrolyte interphase" (SEI), and generally mainly consists of decomposition products of the electrolyte and a certain amount of lithium, and this lithium cannot be used for further charge-discharge reactions. The thickness and composition of the SEI depend on the type and quality of the negative electrode material used and the electrolyte solution used.

[0097] In the case of graphite, the SEI is particularly thin. In the case of graphite, generally 5% to 35% of the mobile lithium in the cell is lost during the first charging stage. Along with this, the reversible capacity of the battery also decreases.

[0098] In the case of the negative electrode having the silicon-containing material according to the present invention, the loss of mobile lithium in the first charging step is preferably at most 30%, particularly preferably at most 20%, and most preferably at most 10%, which is significantly lower than the prior art values described, for example, in US Patent 10,147,950B1 for silicon-containing composite negative electrode materials.

[0099] The lithium-ion secondary battery according to the present invention can be manufactured in any normal form, such as a wound type, a foldable type, or a laminated type.

[0100] As described above, all substances and materials used to manufacture the lithium-ion battery according to the present invention are known. The manufacture of the battery components according to the present invention and their assembly to form the battery according to the present invention are carried out according to methods known in the field of battery manufacture.

[0101] The silicon-containing material of the present invention is characterized by significantly improved electrochemical behavior and can realize a lithium-ion battery having a high volumetric capacity and excellent application characteristics. Since the silicon-containing material according to the present invention is permeable to lithium ions and electrons, charge transport is possible. When the silicon-containing material according to the present invention is used, the amount of SEI in the lithium-ion battery can be significantly reduced. Furthermore, due to the design of the silicon-containing material according to the present invention, SEI no longer peels off from the surface of the silicon-containing material according to the present invention, or at least the degree of peeling is much smaller. As a result, the cycle stability of the corresponding lithium-ion battery is increased. Fading and trapping can be minimized. Furthermore, the lithium-ion battery according to the present invention has less initial and continuous loss of lithium available in the cell and thus exhibits high coulombic efficiency.

Examples

[0102] The following examples serve to further illustrate the invention described herein.

[0103] <Scanning Electron Microscope (SEM / EDX)> Microscopic analysis was performed using a Zeiss Ultra 55 scanning electron microscope and an energy-dispersive Oxford X-Max 80N X-ray spectrometer. Before the analysis, in order to prevent charging, carbon vapor deposition treatment was performed using a Safematic Compact Coating Unit 010 / HV. The cross-section of the silicon-containing material was prepared at 6 kV using a Leica TIC 3X ion cutter.

[0104] <Inorganic / Elemental Analysis> The C content was measured using a Leco CS 230 analyzer, and a Leco TCH-600 analyzer was used for the measurement of oxygen and nitrogen contents. The qualitative and quantitative analysis of other elements was performed by ICP (Inductively Coupled Plasma) optical emission spectrometry (Optima 7300 DV, Perkin Elmer). For this purpose, the samples were acid-digested (HF / HNO3) using a microwave (Microwave 3000, manufactured by Anton Paar). The quantification by ICP-OES complies with ISO 11885 "Water quality - Determination of selected elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (ISO 11885:2007); German version EN ISO 11885:2009" and is used for the analysis of acidic aqueous solutions (acidified drinking water, wastewater, other water samples, aqua regia extracts of soil and sediment, etc.).

[0105] <Particle size measurement> The particle size distribution was measured by the static laser scattering method using a Horiba LA 950 in accordance with ISO 13320. In the preparation of the samples, special attention should be paid to the dispersion of the particles in the measurement solution so as not to measure the size of the aggregates rather than individual particles. For the materials studied here, these were dispersed in ethanol. For this purpose, the dispersion was treated with ultrasonic waves at 250 W for 4 minutes using a Hielscher model UIS250v ultrasonic device equipped with an LS24d5 sonotrode before measurement if necessary.

[0106] <BET specific surface area measurement> The specific surface area of the materials was measured by the BET method (measurement method compliant with DIN ISO 9277:2003-05 using nitrogen) by gas adsorption using a Sorptomatic 199090 device (manufactured by Porotec) or a SA-9603MP device (manufactured by Horiba).

[0107] <Skeletal density> The skeletal density, i.e., the density of a porous solid based only on the volume of the pore space into which gas can penetrate from the outside, was measured by helium pycnometry in accordance with DIN 66137-2.

[0108] <Gas permeability pore volume> The gas permeability pore volume according to Gurwitsch was determined by gas sorption measurement with nitrogen according to DIN 66134.

[0109] <Measurement of reversible delithiation capacity β> The measurement of the capacity of the porous particles or silicon-containing material was carried out using a button-type half cell (CR2032 type, Hohsen Corp.). For this purpose, an electrode was manufactured from the porous particles or silicon-containing material, a binder, optionally graphite, optionally further conductive components, and optionally additives, and installed with respect to a lithium counter electrode (Rockwood Lithium, thickness 0.5 mm, diameter = 15 mm). The working electrode based on the silicon-containing material corresponds to the positive electrode in this cell structure. Metallic lithium was used for the counter electrode, which corresponds to the negative electrode. A glass fiber filter paper (Whatman, GD type D) saturated with 120 μl of the electrolyte was used as the separator (Dm = 16 mm). The electrolyte used was a 1.0 molar solution of lithium hexafluorophosphate in a 1:4 (v / v) mixed solvent of fluoroethylene carbonate and diethyl carbonate. The cell was usually assembled inside a glove box (H2O and O2 are 1 ppm or less). The water content of the dried starting materials is preferably 20 ppm or less.

[0110] First, the half cell was converted to a discharged state by discharging it using a constant current corresponding to the theoretical capacity of the silicon-containing material (theoretical capacity: silicon weight % × 3579 mAh / g, rate: C / 25) by the cc method (constant current) until a voltage limit of 0.005 V was reached. Here, the active material is lithiated.

[0111] The reversible delithiation capacity β of the anode film was determined by charging the button-type half cell thus generated and discharged at C / 25 until a voltage limit of 1.5 V was reached. The electrochemical measurement was carried out at 20°C.

[0112] <Measurement of average electrical particle resistance> To measure the electrical resistance of individual particles below 100 μm, a flat copper indenter was attached to a Shimazu micro compression tester MCT211 and connected to a KEITHLEY 2602 dual source meter together with a sample holder. The resistance values of individual particles vary due to different particle shapes. Therefore, for each product batch, the average value of the electrical resistance of at least 20 particles was determined. Statistical analysis using a t-test [One-sample test, Student.Test: The Probable Error of a Mean. In: Biometrika. Volume 6, No. 1 March 1908, pp. 1-259] can be used to determine the significant difference between the average values of different product batches, for example, at a 95% confidence level.

[0113] [Example 1] <Porous particles of silicon dioxide> 493 ml of ethanol and 308 ml of water were placed in a 1 L wide-mouth Duran glass bottle. 30.18 g of tetraethoxysilane (TEOS) was added to this mixture at room temperature and dissolved with stirring. The temperature of this solution was adjusted to 15 °C, and an additional 30.18 g of TEOS was added dropwise over 45 minutes using a dropping funnel. The solution gradually became turbid and a precipitate formed. After stirring the reaction mixture at 15 °C for an additional 4 hours, the precipitate was suction filtered and washed 4 times with water and ethanol. The white powder thus obtained was dried in a drying cabinet at 80 °C for 4 hours. The crude product (18.68 g) was heated in a boat in a tubular furnace to 400 °C at a heating rate of 2 °C / min. The temperature was then raised to 600 °C, the next holding temperature, at 10 °C / min and held for 4 hours. The furnace atmosphere was adjusted with an argon flow of 12 L / h throughout the reaction and with an argon flow of 3 L / h until the tube was emptied during the cooling stage. 13.74 g (73.6%) of porous SiO2 particles were obtained.

[0114] Reversible de-lithiation capacity β: 8 mAh / g BET: 1270 m2 / g Particle size distribution (PSD): D50 = 5.4 μm, span 0.77 Total pore volume: 0.8 cm3 / g Average particle electrical resistance: 240000 kΩ

[0115] [Example 2] <Silicon-containing material> 3.0 g of the porous silicon dioxide particles of Example 1 (specific surface area = 1070 m 2 / g, pore volume = 0.6 cm 3 / g) were charged into a quartz glass boat. After being inactivated with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.8 hours. Then, after purging the reactor with an inert gas, the product was annealed at 500 °C for 1 hour. Before removing from the reactor, the product was cooled to room temperature under an inert gas.

[0116] BET specific surface area 29 m 2 / g PSD: D50 = 5.4 μm, span 0.77 Vapor-deposited Si content 35 wt Reversible delithiation capacity β: 1245 mAh / g Initial Coulombic efficiency: 92

[0117] [Comparative Example 3] <Silicon-containing material> 3.0 g of a mesoporous silicon dioxide matrix (specific surface area = 360 m 2 / g, pore volume = 1.1 cm 3 / g, Polygoprep (trademark) 100 - 12 manufactured by Macherey-Nagel, average particle electrical resistance 210000 kΩ, reversible capacity β = 8 mAh / g) was filled into a tubular reactor. After being inactivated with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5 hours. After purging the reactor with an inert gas, the product was annealed at 500 °C for 1 hour. Before removing from the reactor, the product was cooled to room temperature under an inert gas.

[0118] BET specific surface area 214 m 2 / g PSD: D50 = 14 μm, span 0.8 Vapor-deposited Si content: 30 wt% Reversible lithium deintercalation capacity β: 1068 mAh / g Initial Coulombic efficiency: 89

[0119] [Example 4] <Electrochemical test in a lithium-ion battery with a negative electrode made of the silicon-containing material of Example 2> 29.71 g of polyacrylic acid (dried to a constant weight at 85 °C; manufactured by Sigma-Aldrich, Mw ~ 450,000 g / mol) and 756.60 g of deionized water were stirred using a shaker (290 L / min) for 2.5 hours until the dissolution of polyacrylic acid was complete. Lithium hydroxide monohydrate (Sigma-Aldrich) was added little by little to the solution until the pH reached 7.0 (measured with a WTW pH 340i pH meter and a SenTix RJD probe). 3.87 g of the neutralized polyacrylic acid solution and 0.96 g of graphite (Imerys, KS6L C) were placed in a 50 ml container and mixed at 2000 rpm using a planetary mixer (SpeedMixer, DAC 150 SP). Then, 3.40 g of the silicon-containing material according to the present invention from Example 2 was stirred at 2000 rpm for 1 minute. Next, 1.21 g of an 8% conductive carbon black dispersion and 0.8 g of deionized water were added and mixed at 2000 rpm in the planetary mixer. Then, dispersion was carried out at 3000 rpm and 20 °C for 30 minutes in a dissolver. The ink was degassed again in the planetary mixer under vacuum at 2500 rpm for 5 minutes.

[0120] The completed dispersion was applied to a copper foil (Schlenk metal foils, SE-Cu58) with a thickness of 0.03 mm using a film drawing frame (Erichsen, model 360) with a gap height of 0.1 mm. The negative electrode film thus prepared was dried at 50 °C and a pressure of 1 bar for 60 minutes. The average areal weight of the dried negative electrode film was 3.0 mg / cm 2 , and the film density was 0.7 g / cm 3 .

[0121] Electrochemical tests were conducted using a two - electrode configuration button cell (CR2032 type, Hohsen Corp.). The electrode coating was used as the counter electrode or the negative electrode (Dm = 15 mm). Based on lithium - nickel - manganese - cobalt oxide 6:2:2, with a content rate of 94.0% and an average basis weight of 15.9 mg / cm 2 of the coating (obtained from SEI) was used as the working electrode or the positive electrode (Dm = 15 mm). Glass fiber filter paper (Whatman, GD Type D) saturated with 60 μl of the electrolyte was used as the separator (Dm = 16 mm). The electrolyte used was a 1.0 - molar solution of lithium hexafluorophosphate in a 1:4 (v / v) mixed solvent of fluoroethylene carbonate and diethyl carbonate. The cell was assembled inside a glove box (<1 ppm H2O, O2), and the water content in the dried products of all components used was 20 ppm or less.

[0122] The electrochemical tests were carried out at 20 °C. By the cc / cv method (constant current / constant voltage), in the first cycle, charging was performed at a constant current of 5 mA / g (equivalent to C / 25), and in subsequent cycles, at a constant current of 60 mA / g (equivalent to C / 2). When the voltage limit of 4.2 V was reached, charging was continued at a constant voltage until the current dropped below 1.2 mA / g (equivalent to C / 100) or 15 mA / g (equivalent to C / 8). By the cc method (constant current), in the first cycle, discharging was performed at a constant current of 5 mA / g (equivalent to C / 25), and in subsequent cycles, at a constant current of 60 mA / g (equivalent to C / 2) until the voltage limit of 2.5 V was reached. The selected specific current was based on the coating weight of the positive electrode. The electrodes were selected so that the capacity ratio of the positive electrode:negative electrode was 1:1.2.

[0123] Using the full - lithium - ion battery cell of Example 4, the following test results were obtained. - Reversible specific capacity of the negative electrode in the second cycle: 600 mAh / g (4.2 - 2.5 V); 534 mAh / g (4.2 - 3.0V) - Number of cycles with capacity retention of 80% or more: 302 charge - discharge cycles

[0124] [Comparative Example 5] <Electrochemical Test of the Anode Using the Silicon-Containing Material of Comparative Example 3 in a Lithium-Ion Battery> An anode was fabricated using the non-inventive silicon-containing material of Comparative Example 3 as described in Example 4. This anode was attached to the lithium-ion secondary battery described in Example 4, and tests were conducted in the same procedure.

[0125] The following test results were obtained using the full lithium-ion battery cell of Comparative Example 5. - Reversible specific capacity of the anode in the second cycle: 520 mAh / g (4.2 - 2.5 V); 490 mAh / g (4.2 - 3.0 V) - Number of charge-discharge cycles with capacity retention of 80% or more: 35 charge-discharge cycles

[0126] [Example 6] <Microporous Boron Nitride as Porous Particles> 3.36 g of boric acid and 13.68 g of dicyandiamide were dissolved in 300 ml of distilled water at room temperature. Then, the solution was heated to 100 °C and evaporated with stirring until a white crystalline solid (16.79 g) was obtained. 8.15 g of the intermediate product thus obtained was placed in a quartz glass boat and put into a tubular furnace. This was heated at a rate of 10 K / min to 975 °C under a forming gas (5% H2 in N2, 12 Nl / h) stream. After reaching the target temperature, the gas stream was switched to CO2 (3 Nl / h) and maintained for 5 hours. Finally, the mixture was passively cooled to room temperature under a forming gas stream (3 Nl / h). As a result, 0.5 g of a white solid was obtained.

[0127] BET specific surface area 1006 m 2 / g Total pore volume: 0.56 cm 3 / g Reversible delithiation capacity β: 5 mAh / g Average electrical particle resistance: 72740 kΩ PSD: D 50 = 6.8 μm, span 0.81

[0128] [Example 7] <Silicon-containing Material Using Porous Particles of Example 6> 3.0 g of the porous BN particles of Example 6 placed in a quartz glass boat were charged into a tubular reactor. After being inactivated with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.2 hours. Then, before annealing the product at 500 °C for 1 hour, the reactor was purged with an inert gas. Before removing from the reactor, the product was cooled to room temperature under an inert gas.

[0129] BET specific surface area 14 m 2 / g PSD: D 50 = 6.8 μm, span 0.81 Vapor-deposited Si content 35 wt% Reversible delithiation capacity β: 1210 mAh / g

[0130] [Example 8] <Electrochemical Test of the Anode Using the Silicon-containing Material of Example 7 in a Lithium-ion Battery> Using the silicon-containing material of the present invention of Example 7, an anode was fabricated as described in Example 4. This anode was attached to the lithium-ion battery described in Example 4, and the test was conducted in the same procedure.

[0131] Using the full lithium-ion battery cell of Example 8, the following test results were obtained. - Reversible specific capacity of the anode in the second cycle: 740 mAh / g (4.2~2.5 V); 657 mAh / g (4.2~3.0 V) - Number of cycles with a capacity retention of 80% or more: 280 charge-discharge cycles

[0132] [Comparative Example 9] <Silicon-containing Material with Porous Carbon as Porous Particles> 3.0 g of porous carbon (specific surface area = 1189 m 2 / g, pore volume = 0.65 cm 3 / g, average particle electrical resistance = 1.2 kΩ, reversible capacity β = 389 mAh / g) was placed and charged into a tubular reactor. After being inactivated with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.2 hours. After purging the reactor with an inert gas, the product was annealed at 500 °C for 1 hour. Before removing from the reactor, the product was cooled to room temperature under an inert gas.

[0133] BET surface area 32 m 2 / g PSD: D 50 = 3.9 μm, span 0.86 Deposited Si content 38 wt% Reversible delithiation capacity β: 1130 mAh / g

[0134] [Comparative Example 10] <Electrochemical Test of the Anode and Lithium-Ion Battery Using the Silicon-Containing Material of Comparative Example 9> Using the non-inventive silicon-containing material of Comparative Example 9, an anode was fabricated as described in Example 4. This anode was attached to the lithium-ion battery described in Example 4, and the test was conducted in the same procedure.

[0135] Using the full lithium-ion battery cell of Comparative Example 10, the following test results were obtained. - Reversible specific capacity of the anode in the second cycle: 580 mAh / g (4.2~2.5 V); 464 mAh / g (4.2~3.0 V) - Number of capacity retention cycles of 80% or more: 174 charge-discharge cycles

[0136]

Table 1

Claims

1. A silicon-containing material for a negative electrode active material of a lithium-ion battery, containing one or more porous particles and silicon, wherein the silicon is disposed within pores and on the surface of the porous particles, and the silicon-containing material has a maximum specific surface area of 50 m ２ / g as determined by nitrogen sorption and BET evaluation, wherein the porous particles a) have an average electrical particle resistance of at least 2 kΩ, and b) have a reversible delithiation capacity β of up to 100 mAh / g and the porous particles are a ceramic material represented by the following general formula: Al a B b C c Mg d N e O f Si g (wherein 0 ≦ a, b, c, d, e, f, g ≦ 1, but at least two of the coefficients a to g are > 0, and a×3 + b×3 + c×4 + d×2 + g×4 ≧ e×3 + f×2). and non-stoichiometric boron nitride BNz (wherein z = 0.2 to 1), non-stoichiometric carbon nitride CNz (wherein z = 0.1 to 4 / 3) boron carbon nitride BxCNz (wherein x = 0.1 to 20, z = 0.1 to 20, x×3 + 4 ≧ z×3), boron nitride-based oxide BNzOr (wherein z = 0.1 to 1, r = 0.1 to 1, 3 ≧ r×2 + z×3), boron carbon nitride oxide BxCNzOr (wherein x = 0.1 to 2, z = 0.1 to 1, r = 0.1 to 1, x×3 + 4 ≧ r×2 + z×3, silicon carbon oxide SixCOz (wherein x = 0.1 to 2, z = 0.1 to 2, x×4 + 4 ≧ z×2, silicon carbon nitride SixCNz (wherein x = 0.1 to 3, z = 0.1 to 4, x×4 + 4 ≧ z×3, silicon boron carbon nitride SiwBxCNz (wherein w = 0.1 to 3, x = 0.1 to 2, z = 0.1 to 4, w×4 + x×3 + 4 ≧ z×3, Silicon boron carbon oxide SiwBxCz (where w = 0.10 - 3, x = 0.1 - 2, z = 0.1 - 4, w×4 + x×3 + 4 ≥ z×2), Silicon boron carbonitride oxide SivBwCNxOz (where v = 0.1 - 3, w = 0.1 - 2, x = 0.1 - 4, z = 0.1 - 3, v×4 + w×3 + 4 ≥ x×3 + z×2, u = 0.1 - 2, v = 0.1 - 2, w = 0.1 - 4, x = 0.1 - 2, z = 0.1 - 3, u×3 + v×3 + x×4 + 4 ≥ w×3 + z×2) A silicon-containing material comprising a ceramic material selected from the group containing characterized by that.

2. The porous particles have a density of 0.1 - 7 g / cm determined by helium pycnometry ３ The silicon-containing material according to claim 1.

3. The porous particles have a volume-weighted particle size distribution with a diameter percentile d ５０ having a value of 0.5 - 20 μm, the silicon-containing material according to claim 1 or 2.

4. The silicon-containing material has a volume-weighted particle size distribution with a diameter percentile d ５０ having a value of 0.5 - 20 μm, the silicon-containing material according to claim 1 or 2.

5. The silicon-containing material has, based on the total pore volume, at most 30% macropores, the silicon-containing material according to claim 1 or 2.

6. The silicon-containing material has at least 50% pores with a diameter of at most 5 nm, the silicon-containing material according to claim 1 or 2.

7. The silicon-containing material contains at least 30% by weight of silicon, the silicon-containing material according to claim 1.

8. Silicon is present in the pores or on the outer surface of the porous particles in the form of a layer formed from silicon particles having a maximum layer thickness of 1 μm, the silicon-containing material according to claim 1 or 2.

9. A method for producing a silicon-containing material according to any one of claims 1 to 8, comprising pyrolyzing one or more silicon precursors in the presence of one or more porous particles to deposit silicon in pores and on the surface of the porous particles, wherein the silicon-containing material has a specific surface area of at most 50 m ２ / g as determined by nitrogen sorption and BET evaluation, and the porous particles a) have an average electrical particle resistance of at least 2 kΩ, and b) have a reversible lithium deintercalation capacity β of at most 100 mAh / g and the porous particles are a ceramic material represented by the following general formula: Al a B b C c Mg d N e O f Si g (wherein 0 ≦ a, b, c, d, e, f, g ≦ 1, but at least two of the coefficients a to g are > 0, and a×3 + b×3 + c×4 + d×2 + g×4 ≧ e×3 + f×2). and are non-stoichiometric boron nitride BNz (where z = 0.2 to 1), non-stoichiometric carbon nitride CNz (where z = 0.1 to 4 / 3) boron carbon nitride BxCNz (where x = 0.1 to 20, z = 0.1 to 20, x×3 + 4 ≧ z×3), boron nitride-based oxide BNzOr (where z = 0.1 to 1, r = 0.1 to 1, 3 ≧ r×2 + z×3), boron carbon nitride oxide BxCNzOr (where x = 0.1 to 2, z = 0.1 to 1, r = 0.1 to 1, x×3 + 4 ≧ r×2 + z×3, silicon carbon oxide SixCOz (where x = 0.1 to 2, z = 0.1 to 2, x×4 + 4 ≧ z×2, silicon carbon nitride SixCNz (where x = 0.1 to 3, z = 0.1 to 4, x×4 + 4 ≧ z×3, silicon boron carbon nitride SiwBxCNz (where w = 0.1 to 3, x = 0.1 to 2, z = 0.1 to 4, w×4 + x×3 + 4 ≧ z×3, Silicon boron carbon oxide SiwBxCz (where w = 0.10 - 3, x = 0.1 - 2, z = 0.1 - 4, w×4 + x×3 + 4 ≥ z×2), Silicon boron carbonitride oxide SivBwCNxOz (where v = 0.1 - 3, w = 0.1 - 2, x = 0.1 - 4, z = 0.1 - 3, v×4 + w×3 + 4 ≥ x×3 + z×2, u = 0.1 - 2, v = 0.1 - 2, w = 0.1 - 4, x = 0.1 - 2, z = 0.1 - 3, u×3 + v×3 + x×4 + 4 ≥ w×3 + z×2) A method, characterized by comprising a ceramic material selected from the group containing

10. The method according to claim 9, wherein silicon is deposited in a reactor selected from a fluidized bed reactor, a rotary kiln oriented from horizontal to vertical, an open or closed fixed bed reactor, and a pressure reactor.

11. A negative electrode material for use in a lithium ion battery, 5 to 95% by weight of the silicon-containing material according to claim 1 or 2, 0 to 90% by mass of one or more further electrically conductive components, 0 to 90% by mass of graphite, 0 to 25% by weight of a binder, and 0 to 80% by weight of further additives (wherein % by weight refers to the total weight of the negative electrode material, and the proportion of all components of the negative electrode material is at most 100% by weight). A negative electrode material characterized by containing

12. A negative electrode comprising a current collector coated with the negative electrode material according to claim 11.

13. A lithium ion battery comprising an anode, a negative electrode, two conductive connections to the electrodes, a separator, an electrolyte in which the separator and the two electrodes are impregnated, and a housing for accommodating the specified components, wherein the negative electrode contains the silicon-containing material according to any one of claims 1 or 2. A lithium ion battery.

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