Electroactive materials for metal-ion batteries

Abstract

To provide a method for preparing particulate electroactive materials having high electrochemical capacities that are suitable for use as anode active materials in rechargeable metal-ion batteries, and to provide particulate electroactive materials.SOLUTION: This invention relates to particulate electroactive materials consisting of a plurality of composite particles, wherein the composite particles comprise a plurality of silicon nanoparticles dispersed within a conductive carbon matrix. The particulate material comprises 40 to 65 wt % silicon, at least 6 wt % and less than 20% oxygen, and has a weight ratio of the total amount of oxygen and nitrogen to silicon in the range of from 0.1 to 0.45 and a weight ratio of carbon to silicon in the range of from 0.1 to 1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates generally to electroactive materials for use in electrodes for rechargeable metal-ion batteries, and more particularly to Specifically, it has a high electrical conductivity suitable for use as an anode active material in rechargeable metal-ion batteries. The particulate electroactive material of the present invention has two or more chemical capacitances. It is particularly useful in hybrid anodes containing different electroactive materials. A method for preparing the electroactive material is also provided. [Background technology]

[0002] Rechargeable metal-ion batteries are widely used in portable electronic devices such as cell phones and laptops. They are increasingly being used in electric or hybrid vehicles. Batteries generally consist of an anode layer, a cathode layer, and a metal ion layer between the anode and cathode layers. an electrolyte for transporting the electrolyte, and an electrically insulating porous separator disposed between the anode and cathode. The cathode typically comprises a layer of metal ions, including a metal oxide-based composite. The anode includes a metal current collector and an anode that inserts and releases metal ions during charging and discharging of the battery. a metal current collector with a layer of electroactive material, defined herein as a material that can be For the avoidance of doubt, as used herein, the terms "cathode" and "anode" include: This means that the battery is placed in a load so that the cathode is positive and the anode is negative. When a metal-ion battery is charged, the metal ions are transferred to the From the cathode layer, it is transported through the electrolyte to the anode and inserted into the anode material. "Battery" is used herein to refer to a device containing a single anode and a single cathode, as well as a device containing multiple anodes. The term "electrode" is used to refer to both cathodes and / or devices containing multiple cathodes.

[0003] There is interest in improving the gravimetric and / or volumetric capacity of rechargeable metal-ion batteries. The use of lithium-ion batteries already offers significant improvements when compared to other battery technologies. However, there is still room for further development. To date, commercially available lithium-ion batteries have However, this has been limited to the use of graphite as the anode active material. When the card is charged, lithium is inserted between the graphite layers, giving the empirical formula Li x C6( (x is greater than 0 and less than or equal to 1). As a result, graphite is The maximum theoretical capacity of the battery is 372mAh / g, and the practical capacity is slightly lower (about 34 Other materials such as silicon, tin, and germanium are much more efficient than graphite. Although it can insert lithium at a significantly higher capacity than conventional batteries, it can do so over many charge / discharge cycles. It is not yet widely used commercially due to the difficulty of maintaining sufficient capacity at low temperatures.

[0004] Silicon, in particular, has a very high capacity relative to lithium, making it a high weight and volume It has been identified as a promising graphite alternative for the production of high-capacity rechargeable metal-ion batteries. (e.g., Insertion Electrode Materials for r Rechargeable Lithium Batteries, Winter , M. et al., in Adv. Mater. 1998, 10, No. 10 At room temperature, silicon provides approximately 3,600 mAh / g of energy in a lithium-ion battery. Theoretical maximum specific capacity (Li 15However, silicon is used as the anode material. Their use as electrolytes is complicated by the large volume changes on charging and discharging.

[0005] The insertion of lithium into bulk silicon significantly increases the volume of the silicon material, When the battery is lithiated to its maximum capacity, it can reach up to 400% of its original volume, and the charge / discharge cycle Repeated heating causes large mechanical strain in the silicon material, leading to the destruction of the silicon anode material. The volumetric shrinkage of silicon particles during delithiation leads to delamination of the anode material. This can lead to loss of electrical contact between the silicon and the current collector. The electrolyte interface (SEI) layer has sufficient mechanical resistance to accommodate the expansion and contraction of silicon. As a result, the newly exposed silicon surface is not susceptible to further decomposition of the electrolyte, the formation of the SEI layer, This leads to an increase in thickness and irreversible consumption of lithium. Together, they prevent unacceptable loss of electrochemical capacity over successive charge and discharge cycles. bring about.

[0006] Overcoming problems associated with volume changes observed when charging silicon-containing anodes Many approaches have been proposed to address the irreversible capacity loss of silicon-containing anodes. The most popular approach to addressing loss is to use nanostructured silicon as the electroactive material. Silicon nanoparticles and nanostructured silicon are microscale It has been reported that SiO2 particles are more resistant to volume changes during charging and discharging than SiO2 particles. However, nanoscale particles are difficult to prepare and handle, making them unsuitable for commercial use. For example, nanoscale particles tend to form agglomerates, This makes it difficult to obtain a useful dispersion of the particles in the anode material matrix. Furthermore, the formation of nanoscale particle agglomerates leads to unacceptable degradation after repeated charge-discharge cycles. A large capacity loss occurs.

[0007] Ohara et al. (Journal of Power Sources 136(200 4) 303–306) have been reported on the deposition of silicon onto a nickel foil current collector as a thin film and the subsequent deposition of lithium The use of this structure as an anode in a lithium-ion battery is described. Although the thin film structure of the capacitor provides good capacitance retention, the effective capacitance per unit area is low. The improvement disappears as the film thickness increases.

[0008] WO 2007 / 083155 describes a method for producing high aspect ratios, i.e., smallest particle dimensions. Improved capacity retention is obtained by using silicon particles with a ratio of maximum dimension to It discloses what you will get.

[0009] U.S. Patent No. 6,334,939 and U.S. Patent No. 6,514,395 disclose lithium The silicone may contain voids to provide a buffer zone for expansion that occurs when the silicone is inserted. Silicon-based nanostructures, such as bulbil-like spherical particles, are disclosed.

[0010] WO 2012 / 175998 describes, for example, chemical etching or sputtering. Particles comprising a plurality of silicon-containing pillars extending from a particle core that can be formed by the process has disclosed.

[0011] Producing batteries in which the electroactive material of the anode is primarily or entirely silicon is a long-term While this remains a general goal, the more immediate goal for battery manufacturers is to The goal is to identify ways to use small amounts of silicon to compensate for the capacitance. The current focus is on the modification of conventional graphite-based electrodes by including a small amount of silicon. Incremental improvements to existing metal-ion battery technology are being obtained through the use of "hybrid" electrodes that utilize This is what we should do.

[0012] The use of hybrid electrodes presents its own challenges. The additional electroactive material is a metal ion electrode. It must be provided in a shape that matches the shape of graphite particles traditionally used in ponds. For example, additional electroactive materials can be dispersed throughout the matrix of graphite particles. The particles of additional electroactive material must be blended and mixed with the graphite particles. and subsequent formation of the electrode layer (e.g., through steps such as pressing, drying, and calendering). ) and must have sufficient structural integrity to withstand the

[0013] U.S. Pat. No. 8,526,166 describes a hybrid anode containing two types of active material particles. The present invention discloses a lithium ion capacitor including an active material. The first active material particles are graphite. the second active material particles are selected from activated carbon particles such as silicon dioxide particles, and It has a particle size of 0 to 100 nm.

[0014] WO 2015 / 157358 discloses an anode for a lithium-ion battery. The anode active material includes graphite and nanoscale particles, and the nanoscale The particles contain a mixture of crystalline silicon and SiO2, obtained, for example, from the metallothermic reduction of silica. A mixture of crystalline silicon and SiO2 (often called SiOx) is a carbon-based anodized The anode materials may be used in combination with other anode materials such as arsenic, ... [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a plot of capacity retention (y-axis) versus carbon:silicon ratio for Samples 1-9 and Comparative Sample 1, described below. Summary of the Invention

[0016] Despite past efforts, there is still little progress in improving the electrochemical storage capacity of lithium-ion batteries. There is a continuing need for new materials, particularly those that offer the benefits of silicon's high lithiation capacity, An alternative that also has sufficient capacity retention and structural stability for use in commercially viable rechargeable batteries There is a need to identify silicon-based materials.

[0017] In a first aspect, the present invention provides a silicon nanotube having a plurality of silicon nanotubes dispersed in a conductive pyrolytic carbon matrix. The present invention provides a method for preparing a particulate material comprising a plurality of composite particles containing silicon nanoparticles, teeth, (a) Milling a silicon starting material in the presence of a non-aqueous solvent to form a 30-500% solution in the solvent. nmD 50 obtaining a dispersion of silicon-containing nanoparticles having a particle size; (b) treating the dispersion of silicon nanoparticles in the solvent with at least one oxygen or nitrogen atom; contacting a pyrolytic carbon precursor selected from one or more compounds containing a hydroxyl group; (c) The solvent is removed to obtain silicon nanoparticles coated with the pyrolytic carbon precursor. Preparing particles; (d) Optionally, the coated silicone may be heated for 5 minutes to 10 hours prior to step (e). heating the nanoparticles to a temperature of 100 to 400°C; and (e) The coated silicon nanoparticles were decomposed at a pyrolysis temperature of 600 to 1200 °C. pyrolyzed to comprise a plurality of silicon nanoparticles dispersed in a conductive pyrolytic carbon matrix; forming said plurality of composite particles.

[0018] As used herein, the term "composite particle" refers to a composite particle made of multiple particles dispersed in a conductive carbon matrix. However, the particles of the present invention are not limited to those containing silicon nanoparticles. There may be some statistical variation in the distribution of silicon nanoparticles among the particles that make up the nanomaterial. In the extreme case of this statistical variation, the size of a single silicon nanoparticle There are a few particles that contain only carbon matrix material or only conductive carbon matrix material. In this specification, "a plurality of silicon dioxide particles dispersed in a conductive pyrolytic carbon matrix" may be used. "Particle material consisting of a plurality of composite particles including silicon nanoparticles," "particle material," and "composite particle Reference to "particles" is understood to include such statistical variations in the composition of individual particles. Let's say.

[0019] By crushing silicon to form nanoparticles, the surface area of ​​the silicon is significantly increased. Freshly exposed silicon surfaces are highly reactive and typically degrade electrochemical performance. Without being bound by theory, in the presence of a non-aqueous solvent, the oxide layer spontaneously forms. It is thought that the oxidation of the silicon surface can be controlled by grinding the silicon-containing starting material with The silanol groups on the surface of silicon nanoparticles are formed by the oxidation of oxygen-containing groups from the pyrolytic carbon precursor. The silicon nanoparticles may be reacted with a functional group or a nitrogen-containing functional group to provide a functionalized silicon nanoparticle intermediate. Following pyrolysis, oxygen- or nitrogen-containing functional groups from the pyrolytic carbon precursor are bonded to the silicon surface. The reaction creates durable bonds at the interface between the carbon matrix and the surface of the silicon nanoparticles. This bond allows the silicon nanoparticles to expand and contract during charging and discharging. Even after shrinkage, a strong connection between the silicon nanoparticles and the carbon matrix is ​​maintained, which Thus, the advantages described herein in relation to the second and third aspects of the invention are provided.

[0020] The pyrolytic carbon precursor is an aromatic or aliphatic compound containing at least one oxygen or nitrogen atom. Preferably, it is selected from carbon-containing precursor materials.

[0021] Examples of suitable aromatic pyrocarbon precursors include pyrrole, acrylonitrile, 2,3-dihydroxybenzophenone, hydroxynaphthalene, 2,3-diaminonaphthalene, 1,5-dihydroxynaphthalene, 1,5-diaminonaphthalene, 1,8-dihydroxynaphthalene, 1,8-diaminonaphthalene talen, 2,3-dihydroxyanthracene, 2,3-diaminoanthracene, 4,5- Dihydroxyanthracene, 4,5-diaminoanthracene, 9,10-phenanthracene Non, 2,3-dihydroxytetracene, fluorinated 2,3-dihydroxytetracene, tri Fluoromethyl-2,3-dihydroxytetracene, 2,3-diaminotetracene, Fluoromethyl-2,3-dihydroxytetracene, 2,3-diaminotetracene, trifluoromethyl-2,3-diaminotetracene, 2 ,3-Dihydroxypentacene, Fluorinated 2,3-Dihydroxypentacene, Trifluoro Methyl-2,3-dihydroxypentacene, 2,3-diaminopentacene, 2,3-fluoride -Diaminopentacene, Trifluoromethyl-2,3-diaminopentacene, 2,3-di Hydroxyhexacene, 2,3-dihydroxyhexacene fluoride, trifluoromethyl- 2,3-Dihydroxyhexacene, 2,3-diaminohexacene, 2,3-diamino fluoride hexacene, trifluoromethyl-2,3-diaminohexacene, 1,2-dihydroxy pyrene, fluorinated 1,2-dihydroxypyrene, trifluoromethyl-1,2-dihydropyrene Xypyrene, 1,2-diaminopyrene, fluorinated 1,2-diaminopyrene, trifluoromethyl 1,2-diaminopyrene, catechol, dihydroxychrysene, dihydroxyfluoride Cyclisene, trifluoromethyldihydroxychrysene, corrole, porphyrin, hep ter-2,4,6-trien-one, maleic acid, cyanobenzene, fumaronitrile, 4, 5-dihydroxybiphenol, 2,3-dihydroxybiphenol, benzidene, dihydroxybiphenol Droxystilbene, steridonic acid, eicosapentaenoic acid, gamma-linolenic acid, quinoline Phosphorus, isoquinoline, indole, purine, imidazole, adenine, guanine, tetrahydrofuran Hydroquinoline, 1,2-dihydroquinoline, quinolin-2(1H)-one, isoquinolin phenoxazine, phenothiazine, phenoxazol-2(1H)-one, carbazole, phenoxazine, phenothiazine, phenoxazol-2(1H)-one ... azepine, 2,3-dihydroazepine, 2,5-dihydroazepine, azepine, 1,2-diazepine zepine, 1,3-diazepine, 1,4-diazepine, 1,6-dihydropyrrolo-[2,3 -b]-pyrrole, indoline, 3H-indole, 1H-indole, 2H-indole 1H-indazole, benzimidazole, 4-azaindole, 5-azaindole 6-azaindole, 7-azaindole, isophthalic acid, terephthalic acid, phenol of methyl-formaldehyde resin, tannic acid, furfuryl alcohol and 2-naphthol Contains one or more of these.

[0022] Preferred aromatic pyrolytic carbon precursors include catechol, 2,3-dihydroxynaphthalene, , 1,5-dihydroxynaphthalene, 2,3-dihydroxyanthracene and 1,5- Dihydroxyanthracenes and mixtures thereof are included.

[0023] Pyrolytic carbon precursors include alkanediols, polyvinyl alcohol, camphor, gum louisia It also contains rosin.

[0024] Suitable pyrolytic carbon precursors contain one or more electrophilic functional groups, particularly carbonyl moieties, preferably Also included are carbon-containing compounds containing functional groups, preferably containing ester or amide groups. Alternatively, the pyrolytic carbon precursor comprises a carbon-containing backbone and pendant electrophilic functional groups, preferably is a pendant functional group containing a carbonyl moiety, more preferably a pendant amide or ester Polymers or oligomers containing pendant cyclic ester or amide groups Most preferably, the pyrolytic carbon precursor comprises a carbon-containing framework and pendant cyclic amines. Particularly preferred pyrolytic carbons in this category include polymers or oligomers containing hydroxyl groups. Precursors include polyvinylpyrrolidone (PVP) homopolymer, as well as vinylpyrrolidone and one or more other ethylenically unsaturated monomers. Copolymers of vinylpyrrolidone contain at least 50 mol % vinylpyrrolidone monomer. include.

[0025] Optional step (d) involves exposing the coated silicon nanoparticles to pyrolysis temperatures. Allow the coated silicon nanoparticles to stand for a period of time (e.g., 5 min to 1 min) before heating. 0 hours), to a temperature of 100 to 400°C, optionally 200 to 400°C. Preferably, the temperature in step (d) is between the melting point and boiling point of the pyrolytic carbon precursor. be selected.

[0026] In a preferred embodiment of the claimed method, the pyrolytic carbon precursor is one or more of the electrophilic and step (d) is performed by depositing a compound on the surface of the silicon nanoparticles. It involves the formation of crosslinks between nucleophilic functional groups and electrophilic functional groups of the pyrolytic carbon precursor.

[0027] The cross-linking reaction between silicon nanoparticles and pyrolytic carbon precursors results in finer porosity It was found that this formed a denser and more strongly bonded conductive carbon matrix. As a result, the conductive carbon matrix has a higher conductivity and the composite particles have a reduced first conductivity. However, the inventors have found that the silicon nanoparticles and the pyrolytic carbon precursor This cross-linking reaction (also referred to herein as the curing reaction) between the polymer and the polymer is highly exothermic. Therefore, controlling the reaction temperature is a key factor for an effective crosslinking process. The elements of the composite particles may be within the preferred ranges set out below in relation to the second and third aspects of the invention. It was found that this allows for control of the composition.

[0028] Specifically, the inventors have developed a thermal reaction system containing one or more electrophilic functional groups (e.g., PVP). When silicon nanoparticles coated with the decarbonized precursor are heated above 100 °C, It is particularly noteworthy that the resulting crosslinking reaction is highly exothermic, leading to a rapid and uncontrollable temperature rise. The inventors have determined that the temperature of the particles in the furnace or kiln varies depending on the location and size of the crucible. The temperature of the crosslinking reaction can vary greatly depending on the size and other characteristics of the polymer, such as its shape, making it highly non-uniform. It has been observed that this can adversely affect the properties of the final composite particles.

[0029] Without being bound by theory, it is believed that the excess heat from the exothermic crosslinking reaction can cause the crosslinking reaction to This is believed to result in the cleavage of the pyrocarbon precursor and the loss of electrophilic functional groups. Therefore, the cleaved electrophilic functional groups are not available for cross-linking reactions with the silicon nanoparticle surface. Insufficient cross-linking therefore reduces the performance of the final composite particle.

[0030] Therefore, careful control of the conditions in step (d) is essential to prevent excess heat from the reaction. This avoids unwanted cleavage reactions and maximizes the degree of crosslinking obtained in the crosslinking reaction. As a result, it was found that the carbon matrix after pyrolysis in step (e) was improved. Ta.

[0031] Therefore, according to the claimed method, the pyrolytic carbon precursor is preferably one of the above. The step (d) is carried out by coating the The temperature of the reaction mixture is increased by 5°C / min or less. and the maximum temperature of the crosslinking reaction is maintained at 270°C or less during the crosslinking reaction. The crosslinking reaction is complete when the exothermic reaction ceases. It can be confirmed.

[0032] Preferably, step (d) comprises the steps of: Further comprising mixing or stirring the coated silicon nanoparticles. Step (d) may be carried out in a rotary kiln.

[0033] Optionally, the maximum temperature of the crosslinking reaction is less than 250°C, less than 240°C, less than 230°C during the crosslinking reaction. The temperature is maintained below 220°C, below 210°C, or below 200°C.

[0034] The controlled cross-linking reaction in step (d) according to the present invention can be carried out by the step (e) After pyrolysis, a unique interfacial structure was obtained between the silicon nanoparticle core and the conductive carbon matrix. Specifically, the cross-linking reaction creates a silicon nanoparticle core and a conductive carbon matrix. Nitrogen and oxygen compounds exist at the interface with the carbon. Multiple bridging oxygen atoms and / or It is believed that the acid in the composite particles after pyrolysis is in the form of multiple bridging nitrogen atoms. The content of oxygen and / or nitrogen is an indicator of an effective crosslinking process and therefore performance. is associated with improvements in

[0035] More preferably, the pyrolytic carbon precursor comprises a carbon-containing framework and pendant electrophilic groups. functional group, preferably a functional group containing a carbonyl moiety, more preferably an amide or ester group , especially polymers or oligomers containing cyclic ester or amide groups. Particularly preferred pyrolytic carbon precursors in this context are polyvinylpyrrolidone (PVP) or or a copolymer of the above vinylpyrrolidone.

[0036] Preferably, the crosslinking reaction in step (d) is carried out in the presence of oxygen gas. For example, the crosslinking reaction of step (d) can be carried out in the presence of air. It has been found that the presence of hydroxybenzoates accelerates the crosslinking reaction, but excessive temperatures in the crosslinking reaction This can lead to the undesired oxidation of silicon to silica. In addition to optimizing the solubility of silica in water, the method of the present invention also reduces the undesirable oxidation of silica.

[0037] Most preferably, the pyrolytic carbon precursor is PVP and step (d) comprises the steps of: , 100 to 300°C, more preferably 150 to 280°C, more preferably 180 to 280°C Crosslinking the coated silicon nanoparticles at a reaction temperature controlled within the °C range. wherein the crosslinking reaction is carried out in the presence of air.

[0038] Optionally, step (d) is performed after the crosslinking reaction is complete (as determined by the cessation of the reaction exotherm). The coated silicon nanoparticles are then heated for a period of time (e.g., 10 minutes to 2 hours) until 100 This curing process may involve maintaining the temperature at 400° C. The curing process involves heating the silicon surface. It may promote various rearrangements of pyrolytic carbon precursors, e.g. Allowing the carbon to migrate to vacant areas of the silicon surface and / or pre-pyrolysis This allows the precursors to adopt more thermodynamically stable configurations. and / or the conductive carbon matrix. It is believed that this may contribute to the improved conductivity of the material.

[0039] The coated silicon nanoparticles from step (c) or (d) are subjected to step (e) undergoing pyrolysis to form an electrically conductive pyrolytic carbon matrix. is a temperature of 700 to 1150°C, or 800 to 1100°C, or 900 to 1050°C The electrical conductivity of the pyrolytic carbon matrix is ​​determined by the selected pyrolytic carbon precursor and the pyrolysis To obtain a highly conductive pyrolytic carbon matrix, Pyrolysis temperatures above 700°C are usually preferred. Pyrolysis step (e) is carried out for a period of 5 minutes to 120 minutes. For example, 10 to 100 minutes, 20 to 80 minutes, or 40 to 60 minutes. This can be done.

[0040] The pyrolysis step (e) is preferably carried out in an inert or reducing atmosphere. For example, pyrolysis can be carried out under argon or nitrogen, preferably nitrogen, or under argon or nitrogen. The reaction can be carried out in the presence of a mixture of oxygen and carbon monoxide or hydrogen.

[0041] The silicon starting material is preferably at least 95% by weight, at least 98% by weight, or has a purity of at least 99% by weight.

[0042] The silicon starting material may be suitably selected from metallurgical grade silicon. Grade silicon is produced by using charcoal in an electric arc furnace at a temperature of approximately 1900°C to produce high-purity silicon. Metallurgical grade silicon is usually obtained by reducing silicon dioxide. It contains silicon alloyed with various grades of purity ranging from 95% to over 99% by weight. Common impurities found in metallurgical grade silicon include calcium and These include titanium, aluminum, iron, copper, gallium, titanium, and their oxides.

[0043] The silicon starting material can be amorphous silicon, polycrystalline silicon, or single crystal silicon. It may include.

[0044] The silicon starting material preferably contains no more than 4% by weight of oxygen, more preferably no more than 2% by weight of oxygen. oxygen, more preferably not more than 1% by weight of oxygen, more preferably not more than 0.5% by weight of oxygen. nothing.

[0045] The silicon-containing starting material preferably has a particle size of, for example, 1 to 100 μm, more preferably 2 to 5 μm. 0 μm, more preferably 2 to 20 μm, more preferably 2 to 10 μm 50 Particle size Smaller particles of silicon-containing starting material are used. In this case, the amount of fresh silicon surface exposed during step (a) is reduced and the amount of silicon surface exposed is increased. The larger particles may have excess silicon surface carrying natural oxides. However, it may be more difficult to efficiently grind larger silicon particles into smaller sizes. The contained particles or monoliths (e.g., ingots or wafers) are subjected to a pre-grinding step (e.g., The silicon-containing starting material is then subjected to a suitable process (e.g., grinding or milling) and, optionally, sieving to obtain the desired silicon-containing starting material. It is not excluded to obtain silicon microparticles in a desired size range.

[0046] For the avoidance of doubt, the term "particle size" as used herein means equivalent spherical diameter (ESD), That is, it refers to the diameter of a sphere that has the same volume as a particle, and the particle volume is determined by the number of pores within the particle. As used herein, the term "D 50 " and "D 50 Particle size is the volume-based median particle size, i.e., the diameter at which 50% of the volume of the particle population is detected As used herein, the term "D 10 " and "D 10 The particle size is 10% The median particle size on a tile volume basis, i.e., the size below which 10% by volume of the particle population The term "D" as used herein refers to the diameter detected. 90 " and "D90 Particle size is , the 90th percentile volume-based median particle size, i.e., below which the particle population As used herein, the term "D" refers to the diameter at which 90% by volume of the particles are detected. 99 " and "D 99 "Particle size" is the 99th percentile volume-based median particle size, i.e., Below refers to the diameter at which 99% by volume of the particle population is detected.

[0047] Particle size and particle size distribution can be determined by conventional laser diffraction techniques. It is based on the principle that particles scatter light at angles that vary depending on the size of the particle. A collection of particles exhibits a scattered light pattern defined by intensity and angle that correlates with the particle size distribution. For fast and reliable measurement of particle size distribution, many laser diffraction instruments Unless otherwise specified, the particle size distribution measurements specified or reported herein The setpoints were measured using conventional Malvern Mass Spectrometers from Malvern Instruments. This is measured by a Tersizer 3000 particle size analyzer. The Malvern Mastersizer 3000 particle size analyzer is a water-soluble A helium-neon gas laser beam is directed through a transparent cell containing particles of interest suspended in a liquid. The light rays that strike the particles are scattered at angles that are inversely proportional to the particle size. The photodetector array measures the light intensity at several predetermined angles and the measured intensity at different angles. The intensities are processed by a computer using standard theoretical principles to determine the particle size distribution. The laser diffraction values ​​reported herein are determined using a wet dispersion of particles in distilled water. The refractive index of the particles is taken to be 3.50 and the index of the dispersant is 1.330 The particle size distribution is calculated using the Mie scattering model.

[0048] Step (a) may be performed by, for example, ball milling, planetary milling, jet milling, or This can be done using any suitable wet milling process, including combinations thereof. Suitable solvents for step (a) include hydrocarbons (e.g., toluene, xylene, n-hexane, n-heptane, n-octane, decane, dodecane and petroleum ether ethers (e.g., selected from tetrahydrofuran, diglyme, and triglyme); ketones (e.g., selected from acetone and methyl ethyl ketone), alcohols (e.g., selected from isopropyl alcohol and n-butyl alcohol), and and halogenated solvents (e.g., 1,2-dichloroethane, 1,1,1-trichloroethane, etc.). Other suitable solvents include acetonitrile, dimethylformamide, Preferred solvents include dimethyl ether (DMF) and dimethyl sulfoxide (DMSO). These include alcohols and ketones. A particularly preferred solvent is isopropyl alcohol. do.

[0049] The solvent may be present in an amount of 5 to 50% by weight based on the weight of the silicon starting material, e.g., It can be used in an amount of 10 to 25% by weight based on the weight of the composition.

[0050] Step (a) prevents unwanted side reactions on the newly exposed surfaces of the silicon nanoparticles. The solvent used in step (a) may be degassed and For example, the solvent may be 10 ppmw (parts per million by weight) or less. 1) less than 5 ppmw of oxygen, or less than 1 ppmw of oxygen. The solvent contains less than 10 ppmw (parts per million by weight) water, less than 5 ppmw water, or More preferably, the solvent contains less than 1 ppmw of oxygen and water. Less than 10 ppmw (parts per million by weight), oxygen and water less than 5 ppmw each; or may contain less than 1 ppmw of water and oxygen each. It is carried out under an air and / or anhydrous atmosphere, for example under an inert gas such as nitrogen or oxygen. Alternatively, step (a) may be performed by removing atmospheric water and and / or in a milling vessel with minimized headspace to virtually exclude oxygen Preferably, the headspace of the milling vessel is filled with nitrogen prior to milling. The gas is flushed with an inert gas such as nitrogen.

[0051] Optionally, D of the silicon nanoparticles formed in step (a) 50 The particle size is at least 50 nm, or at least 60 nm, or at least 70 nm, or at least 7 Optionally, the thickness of the silicon formed in step (a) may be 5 nm, for example at least 80 nm. D of the recombinant nanoparticles 50 The particle size is preferably 300 nm or less, more preferably 250 nm or less, and even more preferably More preferably, it is 200 nm or less, more preferably, it is 150 nm or less, and more preferably, it is 120 nm or less. It can be less than or equal to m.

[0052] The silicon nanoparticles formed in step (a) are preferably 50 to 250 nm, more preferably Preferably 60 to 200 nm, more preferably 70 to 150 nm, more preferably 80 to 120nm D 50 For example, the silicon nanoparticles formed in step (a) Particle D 50 The particle size may be about 100 nm.

[0053] D of silicon nanoparticles formed in step (a) 10 Particle size is at least 10 nm , more preferably at least 20 nm, more preferably at least 40 nm, more preferably The D of the silicon nanoparticles formed in step (a) may be at least 60 nm. 90 The particle size is 500 nm or less, more preferably 400 nm or less, more preferably 300 The thickness of the silicon dioxide formed in step (a) may be 200 nm or less, more preferably 200 nm or less. The nanoparticles are preferably 5 or less, more preferably 4 or less, more preferably 3 or less, and even more preferably has a particle size distribution span (as defined above) of 2 or less, more preferably 1.5 or less. can.

[0054] Steps (a) and (b) are carried out in situ during the milling of the silicon starting material. The nanoparticles may be contacted with the pyrolytic carbon precursor simultaneously. Steps (a) and (b) may be performed sequentially. If carried out next, step (b) comprises dissolving a solution of pyrolytic carbon precursor in a non-aqueous solvent, optionally followed by silane. Mix thoroughly to ensure uniform distribution of the pyrolytic carbon precursor in the silicon nanoparticle dispersion. may include adding, with stirring, the silicon nanoparticle dispersion from step (a). The solvent used to dissolve the pyrolytic carbon precursor is the same as that used to obtain the silicon in step (a). It may be the same solvent as that used to grind the activator material.

[0055] Step (b) is carried out in a manner that avoids contact of the silicon nanoparticles with oxygen and / or water. For example, the dispersion of silicon nanoparticles from step (a) is suitably Before step (b), the silicon nanoparticles may be stored under an anaerobic and / or anhydrous atmosphere. Contact of the nanoparticles with the pyrolytic carbon precursor is also preferably carried out under an anaerobic and / or anhydrous inert atmosphere. Furthermore, the pyrolytic carbon precursor or its solution in a non-aqueous solvent must be degassed. For example, the pyrolytic carbon precursor or a solution thereof may contain 10 ppm Less than w (parts per million by weight) of oxygen, less than 5 ppmw of oxygen, or less than 1 ppmw The pyrolytic carbon precursor or solution thereof may contain 10 ppmw (10 ppm by weight) of oxygen. May contain less than 100,000 parts per million (ppmw) of water, less than 5 ppmw of water, or less than 1 ppmw of water More preferably, the pyrolytic carbon precursor or a solution thereof contains 10 parts oxygen and 10 parts water. Less than pmw (parts per million by weight), oxygen and water less than 5 ppmw each, or It may contain less than 1 ppmw each of water and oxygen.

[0056] The weight loss from the pyrolytic carbon precursor during pyrolysis is typically determined by the structure of the pyrolytic carbon precursor. and 40-70 wt % depending on the pyrolysis conditions. The weight ratio of carbon to silicon is typically determined by the proportion of carbon to silicon in the particulate material product. The weight ratio is selected to be about 1.5 to 3.5 times higher than the desired weight ratio. For example, in step (b), The weight ratio of the pyrolytic carbon precursor to silicon in It may be 0.2 to 3, for example 0.3 to 2.5.

[0057] The solvent may be removed in step (c) by any conventional means. One solvent removal technique is The technique involves evaporation of the solvent under reduced pressure, for example using a rotary evaporator, and optionally, Sufficient heat is provided to prevent the solvent from freezing. More preferably, the solvent is removed by spray drying. The resulting composite particle powder is then removed to form a powder of silicon nanoparticles dispersed in a pyrolytic carbon precursor. The solvent removal process may result in silicon nanoparticles being entrained in the vapor stream. Therefore, the solvent vapor rate must be properly controlled to avoid excessive solvent vapor rates.

[0058] The material resulting from step (c) is composed of silica dispersed in a matrix of pyrolytic carbon precursor. This material may be prepared by dissolving inert (e.g., cellulose nanoparticles) prior to step (d) or (e). However, the pyrolytic carbon precursor may be stored under an atmosphere of low temperature (e.g., anaerobic and / or anhydrous). The coating and / or solvent passivation provides sufficient protection for the silicon nanoparticles, It has been found that the undesirable reaction of silicon with oxygen or water can be prevented.

[0059] The conductive carbon matrix obtained in the pyrolysis step (e) is usually characterized by Raman spectroscopy. Large G band (~1600 cm -1 ), it is clear that graphite However, the large Raman spectra D band (up to 1350cm -1 ), the carbon is completely graphitic. isn't it.

[0060] The thermal decomposition of the coated silicon nanoparticles in step (e) produces silicon nanoparticles. The conductive carbon matrix is ​​formed with dispersed carbon particles. Containing large and / or irregular particles with dimensions ranging from 0 μm to tens of millimeters Therefore, the particulate material from step (e) can be subjected to a size reduction step ( f) to obtain a particulate material having a reduced particle size. Any suitable surface treatment may be used, such as grinding, planetary milling, jet milling, or a combination thereof. Step (f) is carried out in the presence of a solvent (wet powder). Dry milling techniques can be used. If present, the solvent may be removed by any conventional means, for example, evaporation under reduced pressure.

[0061] The particulate material from step (e) or step (f) is subjected to removal of oversized particles. To do this, the mixture may optionally be subjected to a sieving step (g).

[0062] The particulate material from step (e), (f) or (g) is then coated with a carbon coating. Preferably, the carbon coating is modified by chemical vapor deposition (CVD). CVD is a methodology well known in the art that involves depositing a layer of metal on the surface of a particulate material. The process involves the thermal decomposition of volatile carbon-containing gases (e.g., ethylene). The formation of the cyclohexane may occur simultaneously with or immediately after the pyrolysis of step (e). For example, once the pyrolysis reaction is substantially complete, a suitable olefin such as ethylene may be added. Any suitable volatile carbon-containing gas may be introduced into the pyrolysis reactor.

[0063] Alternatively, the carbon coating may be formed by depositing a solution of a carbon-containing compound onto the surface of the particulate material. Suitable carbon-containing compounds include those mentioned above, which may be formed by pyrolysis. Decarbonized precursors are included.

[0064] The carbon coating has the ability to smooth out surface imperfections and fill the remaining surface micro-pores. This further reduces the BET surface area of ​​the particulate material, thereby reducing first cycle losses. Furthermore, the carbon coating has the advantage of further reducing the surface This improves the conductivity of the electrode, reduces the need for conductive additives in the electrode composition, and promotes the formation of a stable SEI layer. This creates an optimal surface for cell growth and improves capacity retention with cycling.

[0065] The particulate material prepared according to the method of the present invention preferably contains 40 to 65% by weight of silica. more preferably 43 to 65 wt. % silicon, more preferably 45 to 65 wt. % silicon For example, the particulate material may contain 48-62% by weight silicon, or 50-60% by weight silicon. % silicon by weight, or 52-58% silicon by weight.

[0066] The total amount of oxygen and nitrogen relative to silicon in the particulate material prepared according to the method of the present invention The weight ratio is preferably 0.1 to 0.45.

[0067] For example, the total amount of oxygen and nitrogen in the composite material from step (e) relative to silicon The weight ratio is 0.42 or less, or 0.4 or less, or 0.38 or less, or 0.35 or less Optionally, the weight ratio of the total amount of oxygen and nitrogen to silicon may be 0.1 to 0.42. , or 0.1 to 0.4, or 0.1 to 0.38, or 0.1 to 0.35 .

[0068] The total amount of oxygen and nitrogen relative to silicon in the particulate material prepared according to the method of the present invention The weight ratio is at least 0.2, more preferably at least 0.24, more preferably At least 0.28, more preferably at least 0.3, more preferably at least 0. 32, and more preferably at least 0.34.

[0069] Preferably, the total amount of oxygen and nitrogen in the particulate material prepared according to the method of the present invention The weight ratio of silicon is 0.25 to 0.42, preferably 0.28 to 0.4, more preferably It may be more preferably 0.3 to 0.38, and most preferably 0.32 to 0.38.

[0070] The weight ratio of carbon to silicon in the composite material from step (e) is preferably 0. It's 1~1.

[0071] The weight ratio of carbon to silicon in the particulate material prepared according to the method of the present invention is at least 0.15, more preferably at least 0.2, more preferably at least 0.2 5, more preferably at least 0.3.

[0072] The weight ratio of carbon to silicon in the particulate material prepared according to the method of the present invention is 0. .8 or less, more preferably 0.7 or less, more preferably 0.6 or less, more preferably 0. It may be 0.55 or less, more preferably 0.5 or less, more preferably 0.0.45 or less.

[0073] For example, the weight of carbon to silicon in the particulate material prepared according to the method of the present invention The ratio is 0.2 to 0.6, more preferably 0.25 to 0.5, and even more preferably 0.3 to 0. It could be 45.

[0074] The ratio of carbon to the total amount of oxygen and nitrogen in the particulate material prepared according to the method of the present invention The weight ratio (i.e., weight [C]:weight [O+N]) is at least 0.7, more preferably at least 0.8, more preferably at least 0.85, or at least 0.9, may be at least 0.95.

[0075] The particulate material prepared according to the method of the present invention preferably contains at least 8% by weight of oxygen. or at least 10% by weight oxygen, or at least 12% by weight oxygen, or less It contains at least 15% by weight of oxygen.

[0076] The particulate material prepared according to the method of the present invention preferably contains from 8 to less than 20% by weight of acid. oxygen, more preferably from 10 to less than 20% by weight, more preferably from 12 to 20% by weight less than oxygen, more preferably less than 15 to 20 wt. % oxygen.

[0077] The particulate material prepared according to the method of the present invention preferably contains 2 to 6% by weight of nitrogen, more preferably Preferably, the nitrogen content is 2.5 to 5% by weight, more preferably 3 to 4.5% by weight, and most preferably The nitrogen-containing particulate material contains 3.5 to 4.5 weight percent nitrogen. It can be prepared from a pyrolytic carbon precursor containing oxygen.

[0078] The particulate material prepared according to the method of the present invention preferably contains at least 10% by weight of carbon. or at least 15% by weight carbon, or at least 18% by weight carbon. The particulate material prepared according to the method of the invention preferably contains no more than 35% by weight of carbon, 30% by weight of cellulose, % or less by weight of carbon, 28% or less by weight of carbon, or 25% or less by weight of carbon, for example. The particulate material prepared according to the method of the present invention may contain 15 to 30% by weight of carbon, or more Preferably, the carbon content is 18 to 25% by weight.

[0079] In a preferred embodiment, the particulate material prepared according to the method of the present invention has a particle size of 43 to 65 s.p.m. % silicon by weight, 10 to less than 20% oxygen by weight, 2 to 6% nitrogen by weight, and 15 to 3 0% by weight of carbon; the total amount of oxygen and nitrogen in the particulate material relative to the silicon in the particulate material The weight ratio of carbon to silicon in the particulate material is 0.25 to 0.42. The ratio is 0.2 to 0.6.

[0080] In a more preferred embodiment, the particulate material prepared according to the method of the present invention has a molecular weight of 48 to 6 2% by weight silicon, 12 to less than 20% by weight oxygen, 2.5 to 5% by weight nitrogen, and The total amount of carbon in the particulate material is 18 to 25% by weight; the total amount of oxygen and nitrogen in the particulate material is 18 to 25% by weight; The weight ratio of carbon to silicon in the particulate material is 0.28 to 0.4; The weight ratio is 0.25 to 0.5.

[0081] In a particularly preferred embodiment, the particulate material prepared according to the method of the present invention is 0 wt. % silicon, 15 to less than 20 wt. % oxygen, 3 to 4.5 wt. % nitrogen, and The total amount of carbon in the particulate material is 18 to 25% by weight; the total amount of oxygen and nitrogen in the particulate material is 18 to 25% by weight; The weight ratio of carbon to silicon in the particulate material is 0.3 to 0.38; The weight ratio is 0.3 to 0.45.

[0082] The particulate material prepared according to the method of the present invention contains trace amounts of silicon, carbon, or oxygen. For example, the particulate material may contain one or more of the following additional elements: Al, Sb, C u, Mg, Zn, Mn, Cr, Co, Mo, Ni, Be, Zr, Fe, Na, Sr, P, Contains trace amounts of one or more additional elements selected from Sn, Ru, Ag, Au, and Ti Such elements may be used, for example, when silicon nanoparticles are obtained from metallurgical grade silicon. When silicon nanoparticles are used, they may be present as trace impurities in the silicon nanoparticles. The molecular materials are aluminum, iron, copper, gallium, magnesium, calcium, titanium and and zirconium in an amount of 0.1 to 8 wt. %, and the remainder of the material is Silicon, carbon and oxygen. Alternatively, such elements may be present from the manufacturing process. You may do so.

[0083] Preferably, the particulate material prepared according to the method of the present invention contains silicon, carbon, oxygen and and nitrogen in total at least 80% by weight, and silicon, oxygen, nitrogen and carbon in total at least at least 85% by weight, the sum of silicon, oxygen, nitrogen and carbon being at least 90% by weight, or at least 95% by weight of silicon, oxygen and carbon in total, e.g., silicon, oxygen , nitrogen and carbon in total at least 98% by weight, or silicon, oxygen, nitrogen and carbon The total content of the elements is at least 99% by weight.

[0084] In a second aspect, the present invention provides a particulate material comprising a plurality of composite particles, the composite particles comprising: , comprising a plurality of silicon nanoparticles dispersed in a conductive carbon matrix; The silicon nanoparticles include a nanoparticle core and a nanoparticle surface, and the nanoparticle surface is A compound of oxygen or a compound of nitrogen or a ... or mixtures thereof; The particulate material comprises 40-65% by weight silicon; the particulate material comprises at least 6% by weight and less than 20% by weight oxygen; The weight ratio of the total amount of oxygen and nitrogen to silicon in the particulate material is 0.1 to 0.45 and; The weight ratio of carbon to silicon in the particulate material is 0.1-1.

[0085] In a third aspect, the present invention provides a particulate material comprising a plurality of composite particles, the composite particles comprising: , comprising a plurality of silicon nanoparticles dispersed in a conductive carbon matrix; The silicon nanoparticles include a nanoparticle core and a nanoparticle surface, Multiple bridging oxygen atoms and / or multiple bridging nitrogen atoms connect the nanoparticle surface and the conductive carbon and a conductive carbon matrix is ​​disposed between the conductive carbon matrix and at least a portion of the conductive carbon matrix. chemically bonded to the particle surface; The particulate material comprises 40-65% by weight silicon; the particulate material comprises at least 6% by weight and less than 20% by weight oxygen; The weight ratio of the total amount of oxygen and nitrogen in the particulate material to the silicon in the particulate material is 0.1 ~0.45; The weight ratio of carbon to silicon in the particulate material is 0.1-1.

[0086] The particulate materials of the present invention are particularly advantageous for use in hybrid electrodes for metal-ion batteries. The use of silicon nanoparticles has been found to have excellent properties, eliminating the problems that occur with larger particles. However, excessive mechanical strain during lithiation and delithiation is avoided. Silicon nanoparticles are dispersed in a conductive carbon matrix in the form of composite particles. By providing silicon nanoparticles, the handling problems associated with silicon nanoparticles can be overcome. Cut.

[0087] Furthermore, the particulate material of the present invention has a carbon matrix and a silicon nanoparticle surface. Therefore, the carbon matrix of the composite particles of the present invention has a unique interface. It does not simply provide a coating that covers the surface of the silicon particles. The unique chemical properties of the interface with the silicon nanoparticles allow the silicon nanoparticles to expand during charging and discharging. The strong connection between the silicon nanoparticles and the carbon matrix is ​​maintained even as the silicon nanoparticles expand and contract. As a result, the electrical conductivity between the silicon nanoparticles, the carbon matrix, and the anode current collector is As a result of their unique structure, the particulate materials of the present invention are effectively maintained. Capacity fade mechanisms characteristic of the use of silicon as the anode active material in ion batteries In particular, the particulate material of the present invention avoids many of the problems associated with the prior art for use in metal ion batteries. Reduced first cycle losses when compared to other silicon-containing particulate forms disclosed in the art. was found to be associated with improved volume retention and volume maintenance.

[0088] The particulate material of the present invention exhibits a significant improvement over anodes containing only graphite as the active material. can be used to provide a hybrid anode with increased volumetric capacity. In addition, the particulate material is dense and uniform, especially when the anode layer is calendered as in the prior art. When fabricating the layer, it must be able to withstand fabrication and incorporation into the anode layer without losing structural integrity. It is robust enough to withstand such a

[0089] The particulate material of the present invention preferably contains 43 to 65% by weight silicon, more preferably 45 For example, the particulate material of the present invention may contain 48 to 62% silicon by weight. Silicon, or 50-60% by weight of silicon, or 52-58% by weight of silicon It is possible.

[0090] The weight ratio of the total amount of oxygen and nitrogen to silicon in the particulate material of the present invention (i.e., The ratio of O+N to Si is 0.42 or less, or 0.4 or less, or 0.38 or less. Optionally, the total amount of oxygen and nitrogen by weight relative to silicon may be 0.35 or less. The ratio is 0.1 to 0.42, or 0.1 to 0.4, or 0.1 to 0.38, or 0. It may be 1 to 0.35.

[0091] The weight ratio of the total amount of oxygen and nitrogen to silicon in the particulate material of the present invention is at least at least 0.2, more preferably at least 0.24, more preferably at least 0.28, More preferably at least 0.3, more preferably at least 0.32, more preferably at least It can be at least 0.34.

[0092] Preferably, the weight ratio of the total amount of oxygen and nitrogen to silicon is 0.25 to 0.42. , more preferably 0.28 to 0.4, more preferably 0.3 to 0.38, and most preferably It can be 0.32 to 0.38.

[0093] The particulate material of the present invention may contain trace amounts of one or more additives other than silicon, carbon, oxygen and nitrogen. For example, the particulate material may optionally contain elements such as Al, Sb, Cu, Mg, Zn, Mn, Cr, Co, Mo, Ni, Be, Zr, Fe, Na, Sr, P, Sn, Ru, Ag , Au, Ti. For example, if the silicon nanoparticles are obtained from metallurgical grade silicon, It may be present as a trace impurity in the nanoparticles. For example, the particulate material of the present invention may Aluminum, iron, copper, gallium, magnesium, calcium, titanium, and zirconium The remainder of the material contains 0.1 to 8 wt. % of one or more elements selected from silicon, Alternatively, such elements may be present in the composition. It may be present from the manufacturing process.

[0094] Preferably, the particulate material of the present invention contains at least the sum of silicon, carbon, oxygen and nitrogen. 80% by weight of silicon, oxygen, nitrogen and carbon in total, at least 85% by weight of silicon At least 90% by weight of silicon, oxygen, nitrogen and carbon in total, or silicon, oxygen, nitrogen At least 95% by weight of silicon and carbon in total, e.g., silicon, oxygen, nitrogen and carbon at least 98% by weight of the sum of silicon, oxygen, nitrogen and carbon, or Both contain 99% by weight.

[0095] The weight ratio of carbon to silicon in the particulate material of the present invention is preferably at least 0. 15, more preferably at least 0.20, more preferably at least 0.25, more preferably Preferably, the weight ratio of carbon to silicon in the particulate material is at least 0.3. .8 or less, more preferably 0.7 or less, more preferably 0.6 or less, more preferably 0. It may be 55 or less, more preferably 0.5 or less, more preferably 0.45 or less.

[0096] For example, the weight ratio of carbon to silicon in the particulate material of the present invention is 0.2 to 0.6; It may be more preferably 0.25 to 0.5, and even more preferably 0.3 to 0.45.

[0097] The weight ratio of carbon to the total amount of oxygen and nitrogen in the particulate material of the present invention (i.e., weight [C ]:weight [O+N]) is at least 0.7, more preferably at least 0.8, even more preferably Preferably it is at least 0.85, or at least 0.9, or at least 0.95. That's fine.

[0098] The particulate material of the present invention preferably contains at least 8% by weight of oxygen, or at least 10% by weight of oxygen. % by weight of oxygen, or at least 12% by weight of oxygen, or at least 15% by weight of oxygen Includes:

[0099] The particulate material of the present invention may contain less than 18% by weight of oxygen.

[0100] The particulate material of the present invention preferably contains from 8 to less than 20% by weight of oxygen, more preferably from 10 to less than 20% by weight of oxygen, more preferably 12 to less than 20% by weight of oxygen, even more preferably It contains less than 15 to 20% by weight of oxygen.

[0101] In a preferred embodiment, the particulate material of the present invention contains 2 to 6% by weight of nitrogen, more preferably 2.5 to 5 wt. % nitrogen, more preferably 3 to 4.5 wt. % nitrogen, most preferably 3. Contains 5 to 4.5% by weight of nitrogen.

[0102] The particulate material of the present invention preferably contains at least 10% by weight carbon, at least 15% by weight % carbon, or at least 18% carbon by weight. or less than 35% by weight carbon, less than 30% by weight carbon, less than 28% by weight carbon, or less than 2 Contains 5% or less by weight of carbon. For example, the particulate material of the present invention contains 15-30% by weight of carbon, Or, more preferably, it may contain 18 to 25% by weight of carbon.

[0103] In a preferred embodiment, the particulate material of the present invention comprises 43 to 65% by weight silicon, 10 to 15% by weight silicon dioxide, containing less than 20% by weight oxygen, 2-6% by weight nitrogen, and 15-30% by weight carbon; The weight ratio of the total amount of oxygen and nitrogen in the particulate material to the silicon in the particulate material is 0.25 ~0.42; the weight ratio of carbon to silicon in the particulate material is 0.2-0.6 be.

[0104] In a more preferred embodiment, the particulate material of the present invention comprises 48-62% by weight silicon, 1 2 to less than 20% by weight oxygen, 2.5 to 5% by weight nitrogen, and 18 to 25% by weight carbon the weight ratio of the total amount of oxygen and nitrogen in the particulate material to the silicon in the particulate material is 0.28 to 0.4; the weight ratio of carbon to silicon in the particulate material is 0.25 to It is 0.5.

[0105] In a particularly preferred embodiment, the particulate material of the present invention comprises 50-60% by weight of silicon, 1 5 to less than 20 wt.% oxygen, 3 to 4.5 wt.% nitrogen, and 18 to 25 wt.% carbon the weight ratio of the total amount of oxygen and nitrogen in the particulate material to the silicon in the particulate material is 0.3 to 0.38; the weight ratio of carbon to silicon in the particulate material is 0.3 to 0 It is .45.

[0106] The conductive carbon matrix in the composite particles may be any suitable material as described with reference to the first aspect of the invention. Conductive carbon matrix obtained by pyrolysis is obtained by pyrolysis of a pyrolytic carbon precursor. Pyrolytic carbon (herein referred to as "pyrolytic carbon") has a large G-band in the Raman spectrum. Do (up to 1600cm -1), it is clear that amosite has graphite-like properties. It may have a rufous structure.

[0107] The composite particles are D 50 Optionally, D 50 The particle size is small At least 2 μm, more preferably at least 3 μm, more preferably at least 4 μm, More preferably, it may be at least 5 μm. 50 The particle size is 20 μm or less. More preferably 18 μm or less, more preferably 15 μm or less, more preferably 12 μm or less For example, the composite particles may have a diameter of 1 to 20 μm, more preferably 10 μm or less. Preferably, it is 2 to 18 μm, more preferably 3 to 15 μm, more preferably 4 to 12 μm, and even more preferably More preferably, D is 5 to 10 μm. 50 Within this size range, the particle size may be The particles with the porosity and pore size distribution described in the document are different from the conventional particles with a uniform thickness of 20 to 50 μm. Their dispersibility in slurries suitable for forming high-density electrode layers, and their structural robustness , their capacity retention over repeated charge-discharge cycles, and their compatibility. It has been found to be ideal for use in metal-ion battery anodes.

[0108] D of composite particles 10 The particle size is preferably at least 0.5 μm, more preferably at least At most 1 μm, and even more preferably at least 2 μm. 10 Particle size of 1 μm or more By maintaining the temperature at a low level, the submicron-sized particles may not aggregate undesirably. This reduces the dispersibility of the particulate material and improves the capacity retention rate.

[0109] D of composite particles 90The particle size is preferably 40 μm or less, more preferably 30 μm or less. The particle size is more preferably 25 μm or less, and even more preferably 20 μm or less. This leads to uneven packing of particles in the electrode active layer, and therefore to the formation of high density electrode layers, especially This prevents the formation of an electrode layer with a thickness of 20 to 50 μm.

[0110] D of composite particles 99 The particle size is preferably 50 μm or less, more preferably 40 μm or less. More preferably, it is 35 μm or less, and most preferably, it is 30 μm or less.

[0111] The composite particles preferably have a narrow size distribution span. N((D 90 -D 10 ) / D 50 (defined as) is preferably 5 or less, more preferably Preferably 4 or less, more preferably 3 or less, more preferably 2 or less, most preferably 1.5 or less Maintaining a narrow size distribution span allows for efficient particle distribution into the high-density electrode layer. Filling is more easily achieved.

[0112] The silicon nanoparticles preferably have a D of 30 to 500 nm. 50 Silicon Nanoparticle D 50 If the particle size is smaller than 30 nm, the surface area of ​​the particles becomes too large and the silicon The amount of oxygen / nitrogen required to bond the carbon nanoparticles to the surrounding conductive carbon matrix is ​​high. This can lead to excessive oxidation, which can reduce the lithiation capacity of silicon. 50 When the particle size is larger than 500 nm, the silicon nanoparticles are efficiently packed into the composite particles. They cannot fit together and require excessive amounts of carbon to compensate for the voids between the silicon nanoparticles. Optionally, the D of silicon nanoparticles 50 The particle size should be at least 50 nm or less. at least 60 nm, or at least 70 nm, or at least 75 nm, for example at least Optionally, the D of the silicon nanoparticles may be 80 nm or less. 50 Particle diameter: 300nm More preferably, 250 nm or less, more preferably, 200 nm or less, more preferably, It may be 150 nm or less, more preferably 120 nm or less.

[0113] The silicon nanoparticles are preferably 50 to 250 nm, more preferably 60 to 200 nm. m, more preferably 70 to 150 nm, more preferably 80 to 120 nm 50 Particle size For example, the D of silicon nanoparticles 50 The particle size may be about 100 nm.

[0114] Silicon nanoparticle D 10 The particle size is at least 10 nm, more preferably at least 20 nm, more preferably at least 40 nm, more preferably at least 60 nm. Silicon nanoparticles D 90 The particle size is 500 nm or less, more preferably 40 0 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less The silicon nanoparticles should be 5 or less, more preferably 4 or less, more preferably 3 or less, and most preferably More preferably, the particle size distribution span (as defined above) is 2 or less, more preferably 1.5 or less. ) can be obtained by using these optimized D 10 , D 90 , and particle size distribution span value is Minimize the problems associated with excessively small or excessively large silicon nanoparticles as described above. is selected to suppress

[0115] The composite particles that make up the particulate material of the present invention preferably have low porosity. For example: The composite particles may be 30% or less, 20% or less, or The particulate material of the present invention may have an intra-particle porosity of 10% or less, 5% or less, or 2% or less. nanoscale silicon to manage the mechanical stresses of lithiation and delithiation The presence of a large pore volume within the composite particles is essential for the particulate composition of the present invention, as it is dependent on the use of the particles. It simply detracts from the volumetric energy density available in the material. The porous membranes may be porous and have pores with diameters of less than 2 nm distributed throughout their volume. It may include.

[0116] As used herein, the term "intracene porosity" refers to the ratio of the volume of pores within a particle to the total volume of the particle. The term "interparticle porosity" refers to the ratio of the volume of pores between discrete particles. The total porosity of a particle can be defined as the sum of the intra- and inter-particle porosity.

[0117] Mercury porosimetry involves applying various levels of pressure to a sample of material immersed in mercury. This technique characterizes the porosity and pore size distribution of a material by measuring the pore size of the sample. The pressure required to force the mercury in is inversely proportional to the size of the pore. Lossimetry is based on the capillary law that governs the penetration of liquids into small pores. is expressed by the Washburn equation below for a non-wetting liquid such as mercury: D=(1 / P)·4γ·cosφ where D is the pore diameter, P is the applied pressure, γ is the surface tension, and φ is the liquid The contact angle between the sample and the pores of the sample is the volume of mercury that penetrates the pores of the sample. As the pressure increases during the analysis, the pore size at each pressure point increases. is calculated and the corresponding volume of mercury required to fill these pores is determined. These measurements were taken over a range of pressures to determine the pore volume versus pore diameter distribution of the sample material. The Washburn equation assumes that all pores are cylindrical. Although cylindrical pores are rarely encountered in real materials, this assumption is valid for most materials. To avoid any misunderstanding, the pore size in this specification provides a sufficiently useful representation of the pore structure. References to are understood to refer to equivalent cylindrical dimensions as determined by mercury porosimetry. The values ​​reported herein obtained by mercury porosimetry are based on ASTM The surface tension γ was 480 mN / m and the contact angle φ is taken to be 140° for mercury at room temperature. The density of mercury is 13.54° at room temperature. 62g / cm 3 It is considered to be.

[0118] For samples in the form of powders of porous particles, the total pore volume of the sample is the sum of the intra-particle pores and the inter-particle pores. This allows for at least bimodal pores to be detected in mercury porosimetry analysis. A pore size distribution curve is generated, which has one or more peaks at low pore sizes related to the intra-particle pore size distribution. and one or more sets of peaks at large pore diameters related to the interparticle pore size distribution. From the pore size distribution curve, the lowest point between the two sets of peaks corresponds to the intra- and inter-particle pore volume. The pore volume at diameters larger than this is the pore volume associated with interparticle pores. The intra-particle porosity is calculated by subtracting the inter-particle pore volume from the total pore volume. gives the intra-particle pore volume that can be obtained.

[0119] Micromeritics Instrument Corporation, USA Many high-performance porosimeters, such as the AutoPore IV series of automated mercury porosimeters available from High-precision mercury porosimetry instruments are commercially available. For a complete review of mercury porosimetry, For more information, see PA Webb and C. Orr's "Analytical Methods in Fine Particle Technology”, 1997, Microm eritics Instrument Corporation,ISBN 0-96 56783-0.

[0120] Mercury porosimetry and other intrusion techniques involve the introduction of mercury (or However, the pore volume is only useful for determining the pore volume of pores accessible to the fluid (or another fluid). It will be understood that the intra-particle porosity values ​​specified or reported herein are those that represent the open pores, i.e. This is understood to refer to the pore volume accessible to the fluid from the exterior of the particle of the invention. When specifying or reporting intra-particle porosity values, the complete porosity not determined by mercury porosimetry is Closed pores are not considered here.

[0121] The particulate material of the present invention is preferably 100 ml 2 / g, more preferably less than 80m 2 / g Less than 60m, preferably 2 / g, more preferably less than 40m 2 / g or less, more preferred Approximately 30m 2 / g, more preferably less than 25m 2 / g, more preferably less than 20m 2 / g Less than 15m, preferably 2 / g. The term "BET surface area" refers to the Brunauer-Emm Calculated from measurements of the physical adsorption of gas molecules on solid surfaces using the Ett-Teller theory The surface area per unit mass of the particulate material of the present invention should be interpreted as referring to the surface area per unit mass of the particulate material. Preferably, the composite particles include particles with low intra-particle porosity, so that the BET surface area is substantially The initial charge of the anode containing the particulate material of the present invention is a function of the particle size and particle size distribution. Minimizing the formation of a solid electrolyte interfacial (SEI) layer on the surface of composite particles during discharge cycling Generally, a low BET surface area is preferred for this purpose. However, an excessively low BET surface area can lead to the formation of a periphery. This is unacceptable due to the inaccessibility of most of the electroactive material to the metal ions in the surrounding electrolyte. For example, the BET surface area is preferably at least Even 0.1m 2 / g, more preferably at least 1m 2 / g, more preferably at least 2 m 2 / g, more preferably at least 5m 2 / g. For example, the BET surface area is 2 / g~25m 2 / g, more preferably 2 to 15m 2 / g.

[0122] The silicon nanoparticles are at least 10 nm in size as measured by X-ray diffraction (XRD) techniques. , at least 12 nm, at least 14 nm, or at least 16 nm of Si(111) It can be characterized by the crystal lattice spacing.

[0123] Optionally, the Si(111) crystal lattice spacing of the silicon nanoparticles is less than 100 nm, less than 50 nm. m or less, or 35 nm or less.

[0124] The particulate material of the present invention typically has a first lithium Preferably, the particulate material of the present invention has a specific charge capacity at 1400 m It has a specific charge capacity at first lithiation of 1000 Ah / g.

[0125] The particulate material of the present invention is preferably prepared by the method defined in relation to the first aspect of the present invention. You get this.

[0126] The particulate material prepared according to the method of the first aspect of the invention may be used in combination with the method of the second and third aspects of the invention. It may be further defined by any of the characteristics defined for the particulate material according to the embodiment of It will be appreciated that such features and combinations of features are within the scope of the first aspect of the invention. It should be understood that this applies equally to particulate materials prepared accordingly.

[0127] In particular, silicon nanoparticles in particulate materials prepared according to the method of the first aspect of the invention. can include a nanoparticle core and a nanoparticle surface, and the nanoparticle surface can include a nanoparticle core and a conductive carbon matrix, The particulate material comprises 40 to 65 weight percent silicon; the particulate material comprises , containing at least 6% by weight and less than 20% by weight of oxygen; and oxygen and nitrogen in the particulate material The weight ratio of the total amount of silicon to the total amount of carbon in the particulate material is 0.1 to 0.45; The weight ratio to silicon is 0.1 to 1.

[0128] The silicon nanoparticles in the particulate material prepared according to the method of the first aspect of the present invention are The nanoparticle core and nanoparticle surface may comprise multiple bridging oxygen atoms and / or multiple Bridging nitrogen atoms are positioned between the nanoparticle surface and at least a portion of the conductive carbon matrix. The particulate material is a conductive carbon matrix chemically bonded to the nanoparticle surface; , 40 to 65 wt. % silicon; the particulate material contains at least 6 wt. % and 20 wt. % silicon. The total amount of oxygen and nitrogen in the particulate material is less than 100% relative to the amount of silicon in the particulate material. The weight ratio of carbon to silicon in the particulate material is 0.1 to 0.45. is between 0.1 and 1.

[0129] In a fourth aspect, the present invention provides a plurality of composite particles obtainable by the method of the first aspect of the invention. A particulate material comprising the child is provided.

[0130] In a fifth aspect of the invention, a particulate material according to the second, third or fourth aspect of the invention and at least In particular, compositions comprising the second, third or The particulate material of the fourth aspect may be used as a component of an electrode composition.

[0131] Thus, a particulate material according to the second, third or fourth aspect of the invention and a compound selected from: and at least one other component selected from: (i) a binder; (ii) a conductive additive; and (iii) an additional particulate electroactive material. The particulate materials used to prepare such electrode compositions are in accordance with the second and third aspects of the present invention. may have any of the features described as preferred or optional with respect to and / or any of the features described as preferred or optional in relation to the first aspect of the invention. It may be prepared by a method including:

[0132] The particulate material of the present invention preferably accounts for 0.5 to 80% by weight of the total dry weight of the electrode composition, more preferably More preferably, it is 1 to 70% by weight, more preferably, it is 1 to 60% by weight, and more preferably, it is 2 to 50% by weight. % by weight, more preferably 2 to 40% by weight, more preferably 2 to 30% by weight, and even more preferably constitutes 5 to 15% by weight.

[0133] Preferably the electrode composition comprises a particulate material according to the second, third or fourth aspect of the invention. and at least one additional particulate electroactive material. Examples of particulate electroactive materials include graphite, hard carbon, silicon, germanium, gallium, The at least one additional particulate electroactive material may include: Preferably selected from graphite and hard carbon, most preferably at least one An additional particulate electroactive material is graphite.

[0134] The at least one additional particulate electroactive material preferably has a particle size of 10 to 50 μm, preferably 10 to 40 μm, more preferably 10 to 30 μm, most preferably 10 to 25 μm, e.g. For example, D of 15 to 25 μm 50 It has a particle size.

[0135] D of at least one additional particulate electroactive material 10 The particle size is preferably at least 5 μm, more preferably at least 6 μm, more preferably at least 7 μm, more preferably At least 8 μm, more preferably at least 9 μm, even more preferably at least Both are 10 μm.

[0136] D of at least one additional particulate electroactive material 90The particle size is preferably 100 μm or less. More preferably, 80 μm or less, more preferably 60 μm or less, more preferably 50 μm or less The thickness is preferably 40 μm or less, and most preferably 40 μm or less.

[0137] In a preferred embodiment, the at least one additional particulate electroactive material comprises carbon-containing particles, Selected from graphite particles and / or hard carbon particles, Elementary particles are 10-50 μm D 50 Even more preferably, the particle size is at least One additional particulate electroactive material is selected from graphite particles, the graphite particles being , 10-50 μm D 50 It has a particle size.

[0138] The particulate material of the present invention preferably accounts for the total dry weight (i.e., i.e., the total dry weight of the particulate material of the present invention and at least one additional particulate electroactive material) More preferably, the particulate material of the present invention comprises 1 to 50% by weight of the electrode composition. 2 to 40% by weight, more preferably 4 to 25% by weight, more preferably 1 to 20% by weight, based on the total dry weight of the electroactive material. It usually comprises 5 to 20% by weight.

[0139] The electrode composition may optionally include a binder. The binder acts to bind the electrode composition to the current collector. It adheres to the body and functions to maintain the integrity of the electrode composition. Examples of binders include polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), and and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, Carboxymethyl cellulose (CMC), modified carboxymethyl cellulose (mCMC) , sodium carboxymethylcellulose (Na-CMC), polyvinyl alcohol (P VA), its alginates and alkali metal salts, styrene butadiene rubber (SBR) and and polyimides. The electrode composition may also include a mixture of binders. The binder is typically polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid, etc. A polymer selected from acrylic acid (mPAA) and its alkali metal salts, SBR, and CMC. Including Rimmer.

[0140] The binder is present in an amount of 0.5 to 20% by weight, preferably 0.5 to 20% by weight, based on the total dry weight of the electrode composition. It may suitably be present in an amount of from 1 to 15% by weight, most preferably from 2 to 10% by weight.

[0141] The binder may include a crosslinking promoter, a coupling agent, and / or an adhesion promoter. It may optionally be present in combination with one or more additives that modify the properties of the composition.

[0142] The electrode composition may optionally include one or more conductive additives. The agent is a non-electroactive material, which is capable of interfering with the electroactive components of the electrode composition and the electrical conductivity of the electrode composition. It is included to improve electrical conductivity between the active ingredient and the current collector. Black, carbon fiber, carbon nanotube, graphene, acetylene black Select from black, ketjen black, metal fibers, metal powders and conductive metal oxides. Preferred conductive additives include carbon black and carbon nanotubes. Contains a utility file.

[0143] The one or more conductive additives are present in an amount of 0.5 to 20 wt. %, based on the total dry weight of the electrode composition. , preferably 1 to 15 wt %, most preferably 2 to 10 wt % in total amount. .

[0144] In a sixth aspect, the present invention provides a second, third or fourth electrode of the present invention in electrical contact with a current collector. There is provided an electrode comprising the particulate material defined in relation to the fourth aspect. The particulate material used to prepare the electrodes may be any of the materials described in relation to the second and third aspects of the invention. It may have any of the features described as preferred or optional, and / or A method including any of the features described as preferred or optional in relation to the first aspect of the invention. It may also be prepared by the method.

[0145] As used herein, the term current collector refers to a material that carries electrical current to or from the electroactive particles in the electrode composition. Examples of materials that can be used as current collectors include copper, aluminum, Aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is preferred. The current collector is typically a foil or mesh with a thickness of 3 to 500 μm. The particulate material of the present invention preferably has a particle size of 10 μm to 1 mm, for example, 20 to 50 It can be applied to one or both sides of the current collector to a thickness of 0 μm or 50 to 200 μm. Cut.

[0146] Preferably, the electrode is in electrical contact with a current collector as defined in relation to the fifth aspect of the invention. The electrode composition may be any of the preferred or optional electrode compositions according to the fifth aspect of the invention. In particular, the electrode of the sixth aspect of the present invention may have any of the features described above. The electrode composition used to form the electrode may contain one or more additional particulate electroactive materials as defined above. It is preferable to include quality.

[0147] The electrode of the sixth aspect of the invention comprises a particulate material of the invention (optionally in the form of an electrode composition of the invention). ) with a solvent and optionally one or more viscosity modifying additives to form a slurry. The slurry can then be poured onto the surface of the current collector and the solvent removed. By this, an electrode layer is formed on the surface of the current collector. Further steps such as treatment and / or calendering of the electrode layer may be performed as needed. The electrode layer may suitably have a thickness of 20 μm to 2 mm, preferably 20 μm to 1 mm. , preferably 20 μm to 500 μm, preferably 20 μm to 200 μm, preferably 20 The thickness is from 20 μm to 100 μm, preferably from 20 μm to 50 μm.

[0148] Alternatively, the slurry may be cast by, for example, casting the slurry onto a suitable casting template. The casting is carried out by casting, removing the solvent, and then removing the casting template. The resulting film or mat may be formed into a free-standing film or mat comprising the particulate material of the present invention. The mat is in the form of a self-supporting cohesive mass which is then bonded to the current collector by known methods. can be combined.

[0149] The electrode of the sixth aspect of the present invention can be used as an anode in a metal ion battery. Therefore, in a seventh aspect, the present invention provides an anode comprising the above-described electrode and a catalyst containing metal ions. a cathode containing a cathode active material capable of discharging and reabsorbing; an anode and a cathode and an electrolyte between the cathode and the metal ion battery.

[0150] The metal ion is preferably lithium, sodium, potassium, calcium or magnesium. More preferably, the rechargeable metal ion battery of the present invention is selected from lithium. It is a lithium-ion battery, and the cathode active material is capable of releasing lithium ions.

[0151] The cathode active material is preferably a metal oxide-based composite. Examples include LiCoO2, LiCo 0.99 Al 0.01 O2, LiNiO2, LiMn O2, LiCo 0.5 Ni 0.5O2 , LiCo 0.7 Ni 0.3 O2, LiCo 0.8 Ni 0.2 O2, LiCo 0.82 Ni 0.18 O2, LiCo 0.8 Ni 0.15 Al 0.05 O2, LiNi 0.4 Co 0.3 Mn 0.3 O2 and LiNi 0.33 Co0 .33 Mn 0.34 The cathode current collector is generally 3 to 500 μm thick. Examples of materials that can be used as cathode current collectors include aluminum, stainless steel, and nickel. Nickel, titanium, and sintered carbon.

[0152] The electrolyte is suitably a non-aqueous electrolyte comprising a metal salt, for example a lithium salt, e.g. The non-aqueous electrolytes that can be used include non-aqueous electrolytes, solid electrolytes, and inorganic solid electrolytes. Examples include propylene carbonate, ethylene carbonate, butylene carbonate, Diethyl carbonate, diethyl carbonate, gamma butyrolactone, 1,2-dimethoxy Ethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane , formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, Methyl acetate, phosphate triester, trimethoxymethane, sulfolane, methyl sulfolane and aprotic organic solvents such as 1,3-dimethyl-2-imidazolidinone. .

[0153] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene Propylene oxide derivatives, phosphate ester polymers, polyester sulfides, polyvinyl Examples include polyvinyl alcohols, polyvinylidene fluoride, and polymers containing ionically dissociating groups.

[0154] Examples of inorganic solid electrolytes include Li5NI2, Li3N, LiI, LiSiO4, and Li2S. Nitrides of lithium salts such as iS3, Li4SiO4, LiOH, Li3PO4, and halogens These include oxides and sulfides.

[0155] The lithium salt is suitably soluble in the selected solvent or mixture of solvents. Examples of salts include LiCl, LiBr, LiI, LiClO4, LiBF4, and LiBC4O8. , LiPF6, LiCF3SO3, LiAsF6, LiSbF6, LiAlCl4, CH 3SO3Li and CF3SO3Li.

[0156] When the electrolyte is a non-aqueous organic solution, metal-ion batteries have a Preferably, the separator is inserted. The separator is typically a highly ionic The separator is made of an insulating material that has permeability and high mechanical strength. Suitable electrode separators have a pore size of 0.01 to 100 μm and a thickness of 5 to 300 μm. Examples include microporous polyethylene films.

[0157] The separator may be replaced with a polymer electrolyte material, in which case the polymer -Electrolyte material is present in both the composite anode layer and the composite cathode layer. The porous material can be a solid polymer electrolyte or a gel-type polymer electrolyte.

[0158] In an eighth aspect, the present invention provides a method for treating a pulmonary arthritis with a pulmonary arthritis virus as defined in relation to the second, third or fourth aspect of the invention. The present invention provides the use of a particulate material as an anode active material. Preferably, the particulate material is a particulate material according to the present invention. In the form of an electrode composition as defined in relation to the fifth aspect of the present invention, most preferably an electrode composition The article includes one or more additional particulate electroactive materials as defined above.

[0159] The elemental analysis of the particulate material of the present invention reported herein reveals the presence of carbon, nitrogen and and oxygen weight percent. Conducted according to ASTM D5373 using a Mechanical Analyzer Silicon analysis is performed using ICP-AES analysis according to ASTM D5600. It was carried out.

[0160] The invention is illustrated by the examples and the accompanying Figure 1, which shows the sample described below. 1 is a plot of capacity retention (y-axis) versus carbon:silicon ratio for Samples 1-9 and Comparative Sample 1. . [Example]

[0161] Example 1 - Preparation of particulate silicon-carbon material The granular silicon-carbon materials of samples 1 to 14 and the control sample (CS1) were The mixture was prepared using the raw materials and the amounts of carbon sources specified in Table 1.

[0162] The designated carbon source was dissolved in the designated solvent (approximately 40 mL) in a glass beaker. The raw silicon material was added and the mixture was stirred to form a slurry. The slurry was placed in a Retsch ball mill cup containing 1 mm zirconium oxide grinding beads. The beaker was rinsed with additional solvent (2 x 15 mL) and the rinse was transferred to the R The mixture was added to the Etsch ball mill cup. The lid was placed on the ball mill cup and weighed. Measure the weight of the second ball mill cup and continue weighing until it is the same weight as the first ball mill cup. This second cup was adjusted for its weight by the first cup during planetary ball milling. Both cups were fixed to a Retsch PM200 planetary ball mill and mixed. The mixture was milled at 500 rpm for 30 minutes, rested for 15 minutes, and then the direction of the mill was reversed. Reverse the mill direction and grind these samples until the total effective grinding time for each sample listed in Table 1 is reached. The steps were repeated.

[0163] [Table 1] 1 2,3-dihydroxynaphthalene; 2 2,3-diaminonaphthalene; 3 1,2-diaminobenzene; 4 isopropyl alcohol; 5 Undecided

[0164] The milling cup was cooled. The milled material was filtered through a 53 μm mesh. The solution was washed with additional solvent (approximately 150 mL) until it turned pale. The solvent was removed from the filtrate under reduced pressure using a porator. Further drying was carried out in the oven overnight.

[0165] Wash the oven-dried material with 5 x 20 mL of acetone to remove unbound carbon source. The acetone-washed material was then decomposed in a furnace using the pyrolysis procedure specified in Table 2. The material was pyrolyzed in an alumina crucible. The material was then packed in an alumina crucible under an argon flow (1 L / min). The oven was sealed and heated at a rate of 5°C / min to the initial temperature (T1) specified in Table 2. The crucible is maintained at this initial temperature for a first hold time (t1) specified in Table 2, and then The crucible is heated at a rate of 5°C / min to the final temperature (T2) specified in Table 2. The mixture was held at this temperature for a second hold time (t2), designated as , and then cooled to room temperature.

[0166] The pyrolyzed material was removed from the crucible and analyzed using a handheld micronizer for 10 min. The powder was then micronized for a total micronization time of 30 seconds to 1 minute under the conditions specified in Table 2. The pulverized material was dry milled using an etsch PM200 planetary ball mill. The material is mixed with the required amount of milling beads in a ball mill in the amounts specified in Table 2. Place the mixture in a bowl and grind at 500 rpm for 2 minutes, rest for 1 minute, then change the direction of the mill and grind the mixture as specified in Table 2. This was repeated until the total effective grinding time was reached.

[0167] [Table 2]

[0168] The particulate material was then analyzed using a Malvern Mastersizer 3000 instrument. and subjected to particle size analysis and elemental analysis using both ICP / MS and LECO techniques. The BET surface area values ​​of the obtained particulate materials were also measured by Micromeritics Trista. The results for samples 1 to 12 and comparative sample 1 were determined using a II 3020 instrument. The results are shown in Table 3.

[0169] [Table 3]

[0170] Example 2 - Electrode Preparation Anodes having the compositions specified in Table 4 were prepared using the materials of Examples 1 to 12 using the following method. Test coin cells were prepared as described above from the sample and control sample 1 (CS1). The negative electrode was made with silicon-carbon particles. P (conductive carbon) and natural graphite (D 50 = 2.85 μm) dispersed The silicon carbon particulate material was added to the mixture. The SBR binder was then added and mixed in a Thinky™ mixer for 30 minutes. In addition, a 1:1 CMC:SBR ratio was used to prepare the particulate silicon-carbon:graphite shown in Table 4. A slurry having a weight ratio of cellulose:CMC / SBR:conductive carbon was obtained. The slurry was left for 1 hour. The mixture was further mixed by magnetic stirring and then coated onto a 10 μm thick copper substrate (current collector). The copper-based cellulose was dried at 50°C for 10 minutes, followed by further drying at 120-180°C for 12 hours. The electrode was formed with an active layer on a plate. The active layer was calendered at 2 T before cell fabrication. I understood.

[0171] [Table 4]

[0172] Example 3 - Cell Fabrication and Cycling Half-cell manufacturing Porous polyethylene separator, lithium foil as the counter electrode, and 3 wt.% vinylene EC / FEC (Ethylene Carbonate / Fluoroethylene Carbonate) containing carbonate Cut from the electrode of Example 2 with an electrolyte containing 1M LiPF in a 7:3 solution of HCl (HCl). A coin half-cell was fabricated using a circular electrode with a radius of 0.8 cm.

[0173] These half-cells were used to determine the initial volumetric energy density (VED1) of the active layer, The full cycle loss (FCL) and first delithiation capacity (DC1) were measured. The values ​​are shown in Table 5. C / 25 (where "C" is the specific capacity of the electrode in mAh, and "2 A constant current of 5 h ("5" indicates 25 h) was applied to the sample containing the porous particles at a cut-off voltage of 10 mV. The half-cell was tested by lithiating the electrodes. A constant voltage of V is applied with an end current of C / 100. The cell is then left in a lithiated state for 1 hour. The electrode was then delithiated galvanostatically at C / 25 with a cutoff voltage of 1 V, and then The cell was then allowed to rest for 1 hour. A constant current of C / 25 was then applied to the cell at a cut-off voltage of 10 mV. After two lithiations, a constant voltage of 10 mV is applied with an end current of C / 100.

[0174] Full Cell Manufacturing Cut from this electrode with a porous polyethylene separator and a lithium cobalt oxide cathode A full coin-type battery was fabricated using a circular negative electrode with a radius of 0.8 cm. The poles were designed to form balanced pairs, with a projected capacitance ratio of approximately 1:1. Next, EMC / FEC (ethylene methyl carbonate) containing 3% by weight of vinylene carbonate was used. Electrolysis of 1M LiPF6 in a 7:3 solution of ethylene carbonate / fluoroethylene carbonate The material was added to the cell and then sealed.

[0175] The full coin cell was cycled as follows: C / 25 with an end voltage of 4.2V. A constant current of 4.2 V was applied to lithiate the anode. The cell was then allowed to rest in the lithiated state for 1 hour. The anode was then delithiated at a constant current of C / 25 with a cutoff voltage of 3.0 V. After this initial cycle, the cell was allowed to rest for 1 hour. After this initial cycle, a constant current of C / 2 was applied to Lithiate the anode at an end voltage of 1000 V, followed by a constant voltage of 4.2 V at an end current of C / 40. The anode was then delithiated at a constant current of C / 2 with a 3.0 V cutoff. The cell was then allowed to rest for 5 minutes. This was then repeated for the desired number of cycles. The charge / discharge capacity (DC100) and capacity retention rate (CR100) were determined for each sample. The values ​​are shown in Table 5.

[0176] [Table 5]

[0177] Figure 1 is a plot of capacity retention (y-axis) versus carbon:silicon ratio. It can be seen that when the carbon:silicon ratio exceeds 0.10, a good capacity retention rate is observed. If the ratio is less than 0.1, the capacity retention rate is relatively low. Ideally, the carbon and silicon in the particulate material The ratio of the cones is on the order of 0.4 to 0.65.

[0178] Example 4 - Preparation of particulate silicon-carbon material Dissolve isopropyl alcohol (IPA) in 200 micron zirconium oxide grinding beads. The mixture was then transferred to a Netzsch high-energy agitated bead mill containing recirculating IPA. Set the bead mill so that the silicon is slowly added to the solvent to a concentration of approximately 27% by weight. A weight of silicon slurry was then prepared. The slurry temperature was maintained below 50°C. The slurry is 90 The particles were milled to <800 nm. Particle size measurements were performed using a Malvern Master The grinding was carried out on a rsizer 3000. The resulting grinding slurry was discharged into a suitable container and dried. The solids content was measured using a weight loss (LOD) moisture meter (usually up to 30% w / w). is referred to as the "pre-milled" silicon slurry.

[0179] The "pre-milled" silicon slurry was then adjusted to 20% w / w solids with IPA; The mixture was charged into a Netzsch bead mill containing 50 micron zirconium oxide grinding beads. The slurry is then heated to D while maintaining a slurry temperature below 50°C. 98 <188nm Particle size measurements were performed using a Malvern Mastersizer 3000. The resulting milled slurry was discharged into a suitable container, and the solid content was measured using an LOD moisture meter (usually 2 This slurry was referred to as a "nano-milled" silicon slurry. Call.

[0180] A 20% wt / wt solution of polyvinylpyrrolidone (PVP) in IPA was added overhead. The solution was prepared by dissolving PVP in IPA using a stirrer. The solids content was measured using a fractional meter. The PVP solution was then diluted with 1 part silicone and 1 part PVP. Mix with "nano-ground" silicon slurry at a solid weight ratio of 1.1 parts and homogenize in a high-pressure homogenizer. The mixture was mixed with an overhead stirrer until completely homogenized. The resulting Si:PVP slurry was passed through a high-pressure homogenizer under a pressure of about 1500 bar. The solid content was then measured using an LOD moisture meter (Sartorius M at 100°C). A37) and adjusted to 20% w / w total solids with IPA before spray drying.

[0181] Spray drying was carried out in a ProCept 4M8Trix dryer equipped with a nitrogen closed loop. The homogenized Si / PVP / IPA slurry (410 g) was spray dried at a rate of 10 g / min. The dried product was recovered from the cyclone (71.2 g, 87% recovery). D 50 = 10.5 μm (Malvern Mastersizer / Aero) and The content of carbon dioxide was found to be 7% by weight.

[0182] Further dried product was recovered from the walls of the drying chamber (10.9 g) and cycled It was not mixed with the material from Ron.

[0183] The spray-dried material (batch size 20 g) was then poured into a 400 mL glass rotary kiln vessel. The material was then packed and placed in a Carbolite HTR1100 rotary furnace. The air flow was placed under a flow of dry compressed air at 0.75 rpm. The furnace was kept under controlled conditions of 5°C / min or less throughout the process. The temperature is increased to a maximum of 270°C at a rate of 100°C. After crosslinking, the material was allowed to cool for approximately 2 hours and then discharged from the vessel. At this stage, samples up to approximately 2 g were removed and analyzed by both ICP / MS and LECO. Techniques were used to analyze the material composition.

[0184] The cross-linked material was then placed in an alumina crucible and subjected to static curing under nitrogen flow (0.6 L / min). The pyrolysis was carried out in a bolite tube furnace. The furnace was heated to 1170°C at a rate of 5°C / min. This temperature was maintained for 3 hours, and then the mixture was allowed to cool naturally (usually 10 to 15 hours).

[0185] The pyrolysis product is then sieved through a 38 micron mesh before use. The results are also complete with respect to elemental composition (as above) and surface area (BET), particle size, and tap density. BET was performed using a Micromeritics Tristar II 30 20 instrument. The properties of the final product are shown in Table 6 below.

[0186] Example 5 - Preparation of particulate silicon-carbon material without temperature control Example 5 shows that the crosslinking reaction was carried out in a static oven without controlling the maximum temperature of the crosslinking reaction. The procedure was the same as in Example 4, except that the internal temperature was 100°C due to the exothermic crosslinking reaction. The temperature rose rapidly from 00°C to well over 300°C. The properties of the final product are shown in Table 6 below. Shown below.

[0187] Example 6 - Preparation of carbon-coated silicon-carbon composites by CVD 11.1 g of silicon-carbon composite material prepared according to the method of Example 5 was added to a tared stone. Fill a reaction vessel (400 ml / 85 mm diameter) with Carbolite HTR1100 The mixture was heated in a rotary furnace at 5°C / min under argon (200 mL / min) to 900°C. Once the furnace reached the target temperature, the ethylene gas was turned on for 20 minutes (20 mL / min). The ethylene flow was then stopped and argon was allowed to flow for an additional 5 minutes, after which the The heat was turned off. The product was swirled and allowed to stand under argon until the internal temperature had dropped to 50°C. The reaction vessel was weighed and showed an approximate weight gain of 0.3 g (2.6%). The product was collected (10.6 g) and the BET was 5.0 to 3.4 m. 2 reduced to / g The properties of the final product are shown in Table 6 below.

[0188] [Table 6]

Claims

1. 1. A method for preparing a particulate material comprising a plurality of composite particles, the composite particles comprising a plurality of silicon nanoparticles dispersed in an electrically conductive pyrolytic carbon matrix, the method comprising: (a) Milling a silicon starting material in the presence of a non-aqueous solvent to form a silicon starting material having a D of 30 to 300 nm in said solvent. ５０ obtaining a dispersion of silicon-containing nanoparticles having a particle size; (b) contacting the dispersion of silicon nanoparticles in the solvent with a pyrolytic carbon precursor selected from one or more aromatic or aliphatic carbon-containing compounds containing at least one oxygen or nitrogen atom and containing one or more electrophilic functional groups; (c) removing the solvent to provide silicon nanoparticles coated with the pyrolytic carbon precursor; (d) before step (e), crosslinking the silicon nanoparticles and the pyrolytic carbon precursor by a reaction between nucleophilic functional groups on the surface of the silicon nanoparticles and the one or more electrophilic functional groups of the pyrolytic carbon precursor under conditions in which the temperature increase in the reaction mixture containing the silicon nanoparticles and the pyrolytic carbon precursor is controlled at 5°C / min or less; and (e) pyrolyzing the coated silicon nanoparticles at a pyrolysis temperature of 600-1200°C to form the plurality of composite particles comprising a plurality of silicon nanoparticles dispersed in a conductive pyrolytic carbon matrix; A method for preparing a particulate material comprising a plurality of composite particles, comprising:

2. 10. The method of claim 1, wherein the pyrolytic carbon precursor is polyvinylpyrrolidone (PVP) or a copolymer of vinylpyrrolidone and one or more other ethylenically unsaturated monomers.

3. 3. The method of claim 1 or 2, wherein step (d) comprises mixing or stirring the coated silicon nanoparticles to ensure a uniform reaction temperature during the reaction.

4. The method of any one of claims 1 to 3, wherein step (d) is carried out in the presence of oxygen gas.

5. 5. The method of claim 1, wherein step (d) further comprises maintaining the coated silicon nanoparticles at a temperature of 100-400° C. for a period of time after completion of the reaction.

6. The method according to any one of claims 1 to 5, wherein the solvent is selected from alcohols and ketones.

7. 7. The method of any one of claims 1 to 6, wherein the solvent is removed in step (c) by rotary evaporation or spray drying.

8. The method of any one of claims 1 to 7, further comprising: (f) reducing the size of the composite particles from step (e).

9. The method of any one of claims 1 to 8, further comprising: (g) sieving the composite particles from step (e) or step (f).

10. 10. The method of any one of claims 1 to 9, further comprising: (h) coating the composite particles from step (e), (f) or (g) with a carbon coating.

11. The method of any one of claims 1 to 10, wherein step (d) comprises heating the coated silicon nanoparticles to a temperature of from 100 to 400°C.

12. The method of any one of claims 1 to 11, wherein step (d) comprises heating the coated silicon nanoparticles for a period of from 5 minutes to 10 hours.

13. a particulate material comprising a plurality of composite particles, the composite particles comprising a plurality of silicon nanoparticles dispersed in a conductive carbon matrix; the silicon nanoparticles include a nanoparticle core and a nanoparticle surface, wherein a plurality of bridging oxygen atoms and / or a plurality of bridging nitrogen atoms are disposed between the nanoparticle surface and at least a portion of the conductive carbon matrix, and the conductive carbon matrix is ​​chemically bonded to the nanoparticle surface; the particulate material comprises 40-65% by weight silicon; the particulate material comprises 0.5 to 18% by weight oxygen; the weight ratio of the total amount of oxygen and nitrogen to silicon in the particulate material is 0.42 or less; and A particulate material comprising a plurality of composite particles, wherein the weight ratio of carbon to silicon in said particulate material is 0.1 to 1.

14. The composite particles have a D of 1 to 25 μm ５０ 14. The particulate material of claim 13, having a particle size.

15. D of the composite particles １０ 15. A particulate material according to claim 13 or 14, wherein the particle size is at least 0.5 μm.

16. D of the composite particles ９０ A particulate material according to any one of claims 13 to 15, having a particle size of 40 µm or less.

17. 17. The particulate material of any one of claims 13 to 16, wherein the composite particles have a particle size distribution span of 5 or less, 4 or less, 3 or less, 2 or less, or 1.5 or less.

18. The silicon nanoparticles have a D of 250 nm or less, or 200 nm or less, or 150 nm or less, or 120 nm or less. ５０ A particulate material according to any one of claims 13 to 17, having a particle size.

19. The silicon nanoparticles have a D of at least 10 nm １０ A particulate material according to any one of claims 13 to 18, having a particle size.

20. The silicon nanoparticles have a D of 500 nm or less ９０ 20. The particulate material according to any one of claims 13 to 19, having a particle size.

21. 21. A particulate material according to any one of claims 13 to 20, wherein the surface of the silicon nanoparticles comprises silicon oxide.

22. 22. The particulate material of any one of claims 13 to 21, wherein the composite particles have an intra-particle porosity of no more than 30%, no more than 20%, no more than 10%, no more than 5%, or no more than 2% as determined by mercury porosimetry.

23. The composite particles are 100 m ２ / g or less, 80m ２ / g or less, 60m ２ / g or less, 40m ２ / g or less, 30m ２ / g or less, 25m ２ / g or less, 20m ２ / g or less, or 15m ２ 23. The particulate material of any one of claims 13 to 22, having a BET surface area of ​​no more than 1 / g.

24. 24. The particulate material of any one of claims 13 to 23, wherein the composite particles have a specific charge capacity at first lithiation of at least 1200 mAh / g.

25. 25. A particulate material according to any one of claims 13 to 24, wherein the composite particles comprise 0.1 to 8% by weight of one or more elements selected from aluminium, iron, copper, gallium, magnesium, calcium, titanium and zirconium, the remainder of the material being silicon, carbon, nitrogen and oxygen.

26. A particulate material according to any one of claims 13 to 25, wherein the conductive carbon matrix has an amorphous structure.

27. 27. A hybrid electrode comprising an electrode composition in electrical contact with a current collector; the electrode composition comprising the particulate material of any one of claims 13 to 26 and at least one additional particulate electroactive material selected from graphite, hard carbon, silicon, germanium, gallium, aluminum, and lead; A hybrid electrode wherein in said electrode composition said particulate material comprises 1 to 50 weight percent of the total dry weight of said particulate material and said at least one additional particulate electroactive material.

28. 28. The hybrid electrode of claim 27, wherein the electrode composition forms a layer on the current collector having a thickness of 10 μm to 1 mm or 20 to 50 μm.

29. 29. The hybrid electrode of claim 27 or 28, wherein in the electrode composition, the particulate material comprises 2 to 40 wt % or 5 to 20 wt % of the total dry weight of the particulate material and the at least one additional particulate electroactive material.

30. 30. The hybrid electrode of any one of claims 27 to 29, wherein the electrode composition comprises at least one conductive additive selected from carbon black, carbon fiber, carbon nanotubes, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide.

31. 31. The hybrid electrode of claim 30, wherein the at least one conductive additive is present in the electrode composition in an amount of 0.5 to 20 wt %, based on the total dry weight of the electrode composition.

Images