WO2021049557A1 - Méthode de production de fines particules de silicium purifiées - Google Patents

Méthode de production de fines particules de silicium purifiées Download PDF

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WO2021049557A1
WO2021049557A1 PCT/JP2020/034223 JP2020034223W WO2021049557A1 WO 2021049557 A1 WO2021049557 A1 WO 2021049557A1 JP 2020034223 W JP2020034223 W JP 2020034223W WO 2021049557 A1 WO2021049557 A1 WO 2021049557A1
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fine particles
silicon fine
mass
chlorine
silicon
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Japanese (ja)
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望月　直人
晴之 石田
浩二 福原
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株式会社トクヤマ
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to novel silicon fine particles and a method for producing the same. More specifically, the present invention provides a method for producing purified silicon fine particles in which the amount of oxygen in the silicon fine particles obtained by the vapor phase synthesis method is reduced to a predetermined range or less.
  • silicon is used for various purposes including the electrode material (negative electrode material) of lithium ion secondary batteries, or its use is proposed.
  • carbon materials such as graphite and graphite are generally used as the negative electrode material of lithium ion secondary batteries, but the theoretical capacity is as low as 372 mAh / g (when lithium is converted to LiC 6 ), and the capacity is higher. Negative electrode material is desired.
  • silicon has a large occlusion of lithium per unit mass and has a very high theoretical capacity of 3,579 mAh / g (when lithium is converted to Li 15 Si 4 ), and is a next-generation negative electrode. It is being considered as a material.
  • the problem is that the volume expansion is large when silicon and lithium form an alloy to occlude lithium, and strain energy is generated by repeated expansion and contraction due to charging and discharging. It is possible that the charge capacity of the negative electrode is lowered by accumulating inside and breaking the silicon into pieces to generate voids and losing electrical conductivity and ionic conductivity.
  • Non-Patent Document 1 when the particle size is reduced, the surface (specific surface area) per unit mass increases, and the amount of oxygen impurities tends to increase due to the oxide film formed on the silicon surface. Oxygen bonded to silicon causes irreversible capacity by irreversibly bonding with lithium and lowers battery performance (charging capacity). Therefore, it is desirable to use silicon fine particles having as little oxygen impurities as possible.
  • crystal domain crystallite
  • silicon fine particles those prepared by thermally decomposing halogenated silane such as trichlorosilane are attracting attention.
  • such a silicon fine particle manufacturing process is carried out in an environment in which water does not exist as much as possible.
  • water is mixed in when collecting and transporting the fine particle precursor, or water adsorbed on a furnace material or the like.
  • Even a very small amount of water such as contamination due to the above and water contained in the accompanying gas may oxidize the silicon fine particles and adversely affect the characteristics as the electrode material.
  • an object of the present invention is to provide a method for producing silicon fine particles, which is extremely less affected by a trace amount of water.
  • the present inventors have diligently studied to solve the above problems, and as a result, by treating the silicon fine particles obtained by the vapor phase synthesis method with hydrofluoric acid, the influence of oxidation by water can be exerted.
  • hydrofluoric acid hydrofluoric acid
  • the method for producing purified silicon fine particles of the present invention is characterized in that the silicon fine particles obtained by the vapor phase synthesis method are treated with hydrofluoric acid in the presence of an organic solvent compatible with water.
  • the effect of the present invention is particularly effective when the silicon fine particles obtained by the vapor phase synthesis method contain chlorine in a proportion of 0.1 to 10.0% by mass and oxygen in a proportion of 0.5 to 6.0% by mass. It is remarkable.
  • the silicon fine particles are obtained by heating a gas containing trichlorosilane to a temperature of 600 to 950 ° C. and thermally decomposing trichlorosilane to generate a chlorine-containing silicon fine particle precursor, and then capturing the chlorine-containing silicon fine particle precursor. It is preferably obtained by dechlorinating the collected chlorine-containing silicon fine particle precursor by heating it at a temperature of 750 to 1200 ° C. under the supply of an inert gas or under reduced pressure. ..
  • organic solvent a known organic solvent compatible with water can be used without limitation.
  • it must be at least one selected from methanol, ethanol, propanol, acetone, IPA (isopropyl alcohol), butanol, isobutanol, sec-butanol, tert-butanol, THF (tetra), and NMP (N-methylpyrrolidone). Is preferable.
  • the silicon fine particles in an organic solvent compatible with water, mix hydrofluoric acid (an aqueous solution of hydrogen fluoride), and dry by heating and / or reducing pressure.
  • hydrofluoric acid an aqueous solution of hydrogen fluoride
  • the purified silicon fine particles of the present invention The specific surface area is 10 m 2 / g or more, The average crystallite diameter is less than 40 nm
  • the chlorine concentration is 1 to 10% by mass with respect to the weight of the fine particles.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) is less than 0.025.
  • the influence of oxidation due to a small amount of water mixed in the manufacturing process can be extremely reduced, so that silicon fine particles having an extremely low oxygen impurity concentration can be stably manufactured.
  • the silicon fine particles obtained by the vapor phase synthesis method are treated with hydrofluoric acid in the presence of an organic solvent compatible with water.
  • silicon fine particles obtained by the vapor phase synthesis method are used.
  • an organic silane compound such as trichlorosilane is thermally decomposed to produce a chlorine-containing silicon fine particle precursor in a reaction vessel, and the collected silicon fine particle precursor is heated and / or depressurized. Includes a dechlorination step to dechlorinate.
  • the present applicant has proposed Japanese Patent Application No. 2018-96067 (Japanese Unexamined Patent Publication No. 2019-199385) and Japanese Patent Application No. 2018-239572 (WO2020 / 129499). ing.
  • an organic silane compound containing trichlorosilane as a main component is used as a Si source.
  • a Si source other than trichlorosilane dichlorosilane, silicon tetrachloride, etc. may be contained, and when these are contained, it is desirable to use an amount of 30 mol% or less in all the moles in the Si source. ..
  • a gas that is essentially inert to the reaction of the production method of the present invention such as nitrogen, argon, and helium, can be mixed with the Si source in the reaction vessel as a companion gas.
  • Trichlorosilane which is the main source of Si, has a high boiling point of about 32 ° C. and is easily liquefied.
  • the amount of the accompanying gas is not particularly limited, and it is desirable to use it in the range of 5 to 80% by volume with respect to trichlorosilane in order to stabilize the vaporization of trichlorosilane.
  • trichlorosilane is thermally decomposed as described below to produce SiCl x (x is generally 0.1 to 0.3) as an intermediate product as a silicon fine particle precursor.
  • SiCl x is generally 0.1 to 0.3
  • a typical reaction in this thermal decomposition step is represented by the following formula (2).
  • by-products include dichlorosilane and polymer-like silane.
  • the Si source is heated to a temperature of 600 to 950 ° C, preferably 650 to 900 ° C, more preferably 700 to 850 ° C.
  • the heating temperature is important for producing the silicon fine particle precursor, and when the heating temperature is higher than the predetermined temperature, the reactant is fused to the inner wall of the reaction vessel to close the reaction vessel, and the temperature is higher than the predetermined temperature. If it is low, the desired silicon fine particle precursor cannot be obtained.
  • the reaction vessel a tubular reaction vessel whose inner wall is made of a material such as quartz glass or carbon is usually used, and a heating device capable of heating the inner wall to a predetermined temperature is provided.
  • the crystallite diameter which was not conventionally found in the past, was small, and the amount of oxygen and chlorine was adjusted to a predetermined range. Silicon fine particles can be obtained.
  • the silicon fine particle precursor of the reaction product is collected and separated from hydrogen, silicon tetrachloride, nitrogen, unreacted trichlorosilane, by-product dichlorosilane, polymer-like silane, and the like.
  • the collection method is not particularly limited, and for example, a known method such as a cyclone type collection means, a bag filter, or an electrostatic precipitator can be used.
  • the collected silicon fine particle precursor is sent to the dechlorination process.
  • the means of transportation is not particularly limited as long as it is not exposed to oxygen and water and there is no contamination from the container.
  • the silicon fine particle precursor may be filled in a container made of carbon, aluminum, nickel-coated SUS or the like after nitrogen substitution, and transferred to a dechlorination step.
  • a carbon container is preferable because it is less affected by metallic contamination, which is a problem especially when used as a battery material, and is not denatured even when filled with high-temperature particles.
  • the silicon fine particle precursor collected by the known collecting means can be accumulated in a hopper or the like, and this can be accompanied by a gas containing no oxygen and water such as nitrogen and transported by air through a pipe.
  • the collected silicon fine particle precursor is charged into a dechlorination reaction vessel and heated to a temperature of 750 to 1200 ° C. for dechlorination treatment.
  • the dechlorination treatment is carried out in a dechlorination reaction vessel under the supply of an inert gas containing no oxygen atom or under reduced pressure.
  • the inert gas containing no oxygen atom supplied to and distributed in the dechlorination reaction vessel is not particularly limited as long as it does not react with the silicon fine particle precursor.
  • the inert gas is not limited as long as it does not contain oxygen and water, and a gas such as nitrogen, argon or helium is preferably used.
  • the gas is preferably a gas in which the water content is reduced as much as possible, and particularly preferably a gas having a dew point of ⁇ 50 ° C. or lower. Further, when the pressure is reduced, it is preferable to exhaust the gas from the dechlorination reaction vessel so that the pressure is 1 kPa or less.
  • the reaction of the formula (4) proceeds, and silicon fine particles are obtained.
  • the stirring may be performed by any known method such as one in which the reaction vessel rolls or shakes, one in which the reaction vessel is provided with a stirring blade, or one in which the reaction vessel is agitated by an air flow. May be improved.
  • the dechlorination treatment temperature is appropriately selected according to the crystallite diameter, oxygen concentration, chlorine concentration, etc. of the target silicon fine particles.
  • the average diameter of the primary particles is 30 to 900 nm, the average crystallite diameter is less than 10 nm, and the particles are contained.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) is less than 0.05, and the chlorine concentration is 1 to 10% by mass with respect to the weight of the fine particles.
  • Certain silicon fine particles are obtained. Silicon fine particles having such characteristics have an effect of suppressing expansion when lithium and silicon are alloyed.
  • the collected silicon fine particle precursor when heated to a temperature of more than 900 ° C. to 1200 ° C., preferably to a temperature of more than 1050 ° C. to 1180 ° C. to perform dechlorination treatment, the primary particles are subjected to the dechlorination treatment.
  • the average diameter of the particles is 80 to 900 nm, and the average crystallite diameter is less than 20 to 40 nm. It is possible to produce silicon fine particles which are in mass% and have a ratio (Co / S) of an oxygen concentration (Co: mass%) in the fine particles to a specific surface area (S: m 2 / g) of less than 0.05. ..
  • the time (retention time) for heating the silicon fine particle precursor at the predetermined heating temperature is not particularly limited as long as it reaches the target chlorine concentration, but is generally about 5 to 60 minutes.
  • Hydrofluoric acid treatment The silicon fine particles obtained by the above gas phase synthesis method are treated with hydrofluoric acid (an aqueous solution of hydrogen fluoride) in the presence of an organic solvent compatible with water.
  • hydrofluoric acid an aqueous solution of hydrogen fluoride
  • the silicon fine particle precursor silicon containing a large amount of chlorine
  • the dechlorination treatment is insufficient. Therefore, chlorine near the surface of the remaining particles may react with moisture in the air to oxidize.
  • Si-OH hydroxyl group
  • Si -It is considered to be terminated as an H group
  • the present inventors consider that the amount of chlorine inside the fine particles does not change, and only the oxygen on the surface can be reduced.
  • a silicon powder having a size of several to several tens of microns is obtained by combining a lump of silicon with a crushing means such as a jaw crusher, a roll crusher, and a jet mill.
  • a method (breakdown method) of obtaining silicon fine particles by dispersing in water or an organic solvent and performing wet crushing with a bead mill is known.
  • the silicon fine particles obtained by the above breakdown method do not have the effect of reducing the oxygen concentration of the present invention even if the hydrofluoric acid treatment of the present invention is performed.
  • the reason for this is that in the case of the breakdown method, the reaction between the surface of the silicon fine particles and water or an organic solvent (mechanochemical reaction) occurs due to the energy of wet crushing, and oxidation easily proceeds remarkably. Further, it is known that the reaction by the energy of wet crushing gradually proceeds from the surface of the fine particles to the inside, and the oxygen impurities due to the oxidation that have proceeded to the inside of the fine particles in this way are the surface of the silicon fine particles by the hydrogen fluoride treatment of the present invention. The present inventors speculate that this is because the oxygen cannot be removed by removing oxygen.
  • hydrofluoric acid treatment method in the present invention for example, the following first to third aspects can be adopted without particular limitation.
  • hydrofluoric acid may be introduced into the dispersion (first aspect).
  • a solution in which hydrofluoric acid is dissolved in an organic solvent may be prepared in advance and then mixed with silicon fine particles (second aspect).
  • the silicon fine particles and hydrofluoric acid may be mixed and then mixed with an organic solvent (third aspect).
  • hydrofluoric acid a commercially available product sold as an aqueous solution is usually used.
  • the hydrogen fluoride concentration in the aqueous solution is usually 47 to 48% by mass, but is not particularly limited to this concentration.
  • hydrogen fluoride can be treated as a gas, the introduction of hydrogen fluoride gas results in insufficient treatment for the purpose of the present invention. Therefore, in the present invention, it is preferable to use hydrofluoric acid.
  • the silicon fine particles obtained after the dechlorination treatment are stable, and even if they are opened to the atmosphere after cooling, the quality hardly changes.
  • Chlorine trapped in the crystals of silicon fine particles has low reactivity and has a function of suppressing a volume change during amorphization when forming an alloy with lithium.
  • Moisture includes not only moisture in the air when it is open to the atmosphere, but also moisture contamination during collection and transportation of silicon fine particle precursors, moisture contamination from furnace materials, and argon and nitrogen used as inert gases. Moisture contained in such as.
  • the Si-OH group is terminated to the Si-H group by performing a specific hydrofluoric acid treatment.
  • the reaction of the hydroxyl groups on the surface of the silicon fine particles by hydrofluoric acid treatment is as follows, Si-OH is released, hexafluorosilicic acid (H 2 SiF 6 ) is generated, and the silicon surface is terminated with hydrogen. It is believed that. It is said that this reaction does not occur with hydrogen fluoride gas that does not contain water.
  • the treatment is carried out with hydrofluoric acid in the presence of an organic solvent compatible with water. Therefore, of the above aspects, the first and second aspects are more preferable in that the mixing efficiency of the silicon fine particles and hydrofluoric acid is high.
  • organic solvent those having high affinity with silicon fine particles and hydrofluoric acid are preferable, and specifically, methanol, ethanol, propanol, acetone, IPA (isopropyl alcohol), butanol, isobutanol, sec-butanol, tert- At least one selected from butanol, THF (tetrahydrofuran), and NMP (N-methylpyrrolidone) is preferable.
  • the mixing ratio of the silicon fine particles and hydrofluoric acid is not particularly limited as long as hydrogen fluoride is introduced, which is more than 6 times the amount of hydroxyl groups on the surface of the silicon fine particles, but is usually hydrogen fluoride in hydrofluoric acid. However, it is preferable to mix in an amount of 10 to 100% by mass, preferably 30 to 65% by mass, based on the mass of the silicon fine particles.
  • the amount of the organic solvent used is not particularly limited as long as it is sufficient to uniformly mix the silicon fine particles and hydrofluoric acid, but is 100 to 1000% by mass, preferably 200 to 600% by mass, based on the mass of the silicon fine particles. It is preferably in the range of% by mass.
  • the silicon fine particles For mixing the silicon fine particles with hydrofluoric acid and an organic solvent, known means such as stirring, shaking, and ultrasonic dispersion can usually be adopted in the container.
  • a pulverizing medium such as a ball mill or a bead mill
  • the highly active surface of the broken silicon fine particles is oxidized, or the organic solvent is bonded to the silicon fine particles by a mechanochemical reaction.
  • a mixing means that is not used is preferable.
  • a dispersant or the like When mixing the silicon fine particles with hydrofluoric acid and an organic solvent, a dispersant or the like may be appropriately contained.
  • the dispersant is not particularly limited as long as it volatilizes easily, and is an anionic surfactant such as a carboxylic acid type, a sulfonic acid type or a sulfate ester type, or a cationic surfactant such as an amine salt type or a quaternary ammonium salt type.
  • Activators, nonionic surfactants such as polyethers, bases such as ammonia and triethanolamine are used, and the amount used is preferably 5% by mass or less with respect to the mass of the silicon fine particles.
  • the temperature at which the silicon fine particles are treated with hydrofluoric acid is not particularly limited as long as it does not evaporate the organic solvent or hydrogen fluoride, and is usually carried out at a temperature of room temperature to 80 ° C., but this is not the case.
  • the processing time is also not particularly limited, but is not particularly limited as long as it can flow and mix as a whole for about 1 to 10 minutes.
  • an oxidizing agent such as nitric acid or hydrogen peroxide as is generally performed as a method for surface etching of a silicon wafer.
  • an oxidizing agent such as nitric acid or hydrogen peroxide
  • the surface oxidation and oxide removal of the silicon fine particles proceed violently, which causes the volume of the silicon fine particles to decrease and the yield to decrease significantly, and in an extreme case, the entire silicon fine particles disappear.
  • the silicon fine particle dispersion mixed with hydrofluoric acid is dried under heating and / or reduced pressure.
  • the heating temperature is not particularly limited, and the heating temperature is higher than the temperature at which the components evaporate. Specifically, it is preferable to heat at atmospheric pressure at a temperature of 80 to 300 ° C.
  • the depressurization is not particularly limited as long as the above-mentioned components can be removed, and the pressure may be reduced to 40 to 80 torr (about 5 to 10% of the standard atmospheric pressure) below the atmospheric pressure.
  • the drying method is not particularly limited, and for example, static drying may be used, and spin drying, hot air drying, and spray drying are also possible. Further, heating may be performed when the pressure is reduced.
  • the silicon fine particle dispersion may be solid-liquid separated in advance, and for example, known separation methods such as centrifugation, suction filtration, ultrafiltration, and pressure filtration can be adopted.
  • known separation methods such as centrifugation, suction filtration, ultrafiltration, and pressure filtration can be adopted.
  • the purified silicon fine particles of the present invention have a specific surface area of 10 m 2 / g or more, an average crystallite diameter of less than 40 nm, a chlorine concentration of 1 to 10% by mass with respect to the weight of the fine particles, and an oxygen concentration (oxygen concentration).
  • the ratio (Co / S) of Co: mass%) to the specific surface area (S: m 2 / g) is less than 0.025.
  • the chlorine concentration does not change substantially, and even if it does change, it is very small.
  • the crystallite diameter and specific surface area do not change substantially. Therefore, the chlorine concentration, crystallite diameter, and specific surface area of the silicon fine particles produced by the vapor phase synthesis method are maintained.
  • the range of oxygen impurities in silicon is defined by the ratio (Co / S).
  • the oxygen concentration of the purified silicon fine particles of the present invention is reduced by removing oxygen by hydrofluoric acid treatment, and (Co / S) is reduced to less than 0.025. Further, according to the treatment method of the present invention, it is possible to produce purified silicon fine particles in which the oxygen concentration is reduced to a predetermined range even if the oxygen concentration in the silicon fine particles before the hydrofluoric acid treatment is high. ..
  • the silicon fine particles obtained as described above are crushed as necessary, granulated with an arbitrary agglomerated particle size, and further uniformly dispersed in an arbitrary solvent as necessary, and then, in particular, a lithium ion secondary battery. Can be suitably used as a negative electrode material of.
  • the silicon fine particles of the present invention have a small crystallite diameter and are adjusted to a predetermined amount of oxygen and chlorine, they do not break due to a volume change during occlusion of lithium ions and maintain a high charge / discharge capacity for a long period of time. It is possible to construct a possible negative electrode. Further, since the silicon fine particles of the present invention are not easily affected by oxygen and moisture because the surface hydroxyl groups caused by chlorine remaining on the particle surface are removed and replaced with Si—H groups, they are not easily affected by oxygen and moisture, and have long-term storage stability. It is expensive and can be handled extremely safely.
  • reaction rate of trichlorosilane is calculated from the ratio of trichlorosilane, silicon tetrachloride, and dichlorosilane detected by analyzing the composition of the exhaust gas after the reaction with a gas chromatograph. did.
  • Chlorine concentration in the silicon fine particle precursor and the silicon fine particles The sample was measured and obtained by fluorescent X-ray analysis.
  • Oxygen Concentration in Silicon Fine Particle Precursor and Silicon Fine Particle The sample was measured and obtained with an oxygen nitrogen concentration analyzer (TC-600 manufactured by LECO).
  • Example 1 -Synthesis of silicon fine particle precursor A graphite reaction cylinder with an inner diameter of 80 mm and a length of 2500 mm is heated to 750 ° C., where trichlorosilane is added at a rate of 900 g / min and nitrogen is added as an accompanying gas at a rate of 37 NL (L is liter) / min. It was supplied to synthesize silicon fine particle precursors, which were separated and collected from unreacted gas by a bag filter. The reaction rate of trichlorosilane was about 40%, and about 70% of the silicon fine particle precursor produced was collected by a bag filter. The collected silicon particulate precursor accumulated the atmosphere in a nitrogen-replaced storage vessel.
  • silicon fine particle precursors (those that are not open to the atmosphere) accumulated in the storage container were supplied to a nitrogen-substituted graphite heating crucible while being careful not to touch the atmosphere. .. An appropriate amount of nitrogen was supplied to the inside of this graphite crucible and heated to 750 ° C. while being circulated. After reaching 750 ° C., the mixture was held for 1 hour, then heating was stopped and natural cooling was performed.
  • the heating crucible was opened to the atmosphere, and silicon fine particles were taken out from the inside. Even when the obtained silicon fine particles were exposed to the atmosphere, no odor due to hydrogen chloride gas was felt.
  • the specific surface area of the obtained silicon fine particles was 16 m 2 / g, the average crystallite diameter was 9 nm, and the chlorine concentration was 6.0% by mass with respect to the weight of the fine particles.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) was 0.048.
  • the specific surface area of the obtained purified silicon fine particles was 16 m 2 / g, the average crystallite diameter was 9 nm, and the chlorine concentration was 6.0% by mass with respect to the weight of the fine particles.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) was 0.019.
  • Example 2 A silicon fine particle precursor was synthesized by the same method as in Example 1. Dechlorination was carried out in the same manner as in Example 1 except that there was some contact with the atmosphere when the silicon fine particle precursor was moved to the heating crucible for dechlorination and the heating temperature was set to 800 ° C. did.
  • the specific surface area of the obtained silicon fine particles was 21 m 2 / g, the average crystallite diameter was 6 nm, and the chlorine concentration was 7.4% by mass with respect to the weight of the fine particles.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) was 0.195.
  • the specific surface area of the obtained purified silicon fine particles was 21 m 2 / g, the average crystallite diameter was 6 nm, and the chlorine concentration was 7.6% by mass with respect to the weight of the fine particles.
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) was 0.023.
  • Comparative Example 1 A powder (average diameter 5 ⁇ m) obtained by crushing polycrystalline silicon was dispersed in ethanol and wet-crushed using a bead mill (zirconia beads diameter 0.05 mm) to obtain plate-shaped fine particles having an average diameter of 200 nm.
  • the specific surface area of the obtained silicon fine particles was 85 m 2 / g, the average crystallite diameter was 6 nm, the chlorine concentration was below the lower limit of detection (0.1% by mass), and the oxygen concentration (Co: mass%) and the specific surface area (S).
  • the ratio (Co / S) to: m 2 / g) was 0.129.
  • the specific surface area of the obtained purified silicon fine particles was 85 m 2 / g, the average crystallite diameter was 6 nm, and the chlorine concentration was below the lower limit of detection (0.1% by mass).
  • the ratio (Co / S) of the oxygen concentration (Co: mass%) to the specific surface area (S: m 2 / g) was 0.115.

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Abstract

La présente invention aborde le problème de la fourniture d'une méthode de production de fines particules de silicium purifiées qui sont peu affectées par une quantité infime d'eau.　Dans une méthode de production de fines particules de silicium purifiées selon la présente invention, de fines particules de silicium obtenues par une méthode de synthèse en phase vapeur sont traitées avec de l'acide fluorhydrique en présence d'un solvant organique ayant une compatibilité avec l'eau.　Les fines particules de silicium comprennent du chlore dans une proportion de 0,1 à 10,0 % en masse et de l'oxygène dans une proportion de 0,5 à 6,0 % en masse. Les fines particules de silicium purifiées obtenues ont une surface spécifique d'au moins 10 m2/g, un diamètre de cristallite moyen inférieur à 40 nm, une concentration en chlore de 1 à 10 % en masse par rapport au poids des particules fines, et un rapport (Co/S) d'une concentration en oxygène (Co : % en masse) à une surface spécifique (S : m2/g) inférieur à 0,025.
PCT/JP2020/034223 2019-09-13 2020-09-10 Méthode de production de fines particules de silicium purifiées WO2021049557A1 (fr)

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JP2007537965A (ja) * 2004-05-21 2007-12-27 サイメデイカ リミテツド ケイ素構造体
JP2012524022A (ja) * 2009-04-20 2012-10-11 エーイー ポリシリコン コーポレーション 高純度ポリシリコンの製造方法及び装置
JP2013514252A (ja) * 2009-12-17 2013-04-25 サイメデイカ リミテツド 多孔質シリコン
WO2012033203A1 (fr) * 2010-09-10 2012-03-15 株式会社ブリヂストン Procédé de production de particules fines de silicium et procédé de contrôle de la taille particulaire des particules fines de silicium
US20140235884A1 (en) * 2013-02-20 2014-08-21 The Governors Of The University Of Alberta Method of preparing silicon nanocrystals

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