WO2023149214A1 - Silicon-based material, composite material including silicon-based material, negative-electrode material for secondary battery, and secondary battery - Google Patents

Silicon-based material, composite material including silicon-based material, negative-electrode material for secondary battery, and secondary battery Download PDF

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Publication number
WO2023149214A1
WO2023149214A1 PCT/JP2023/001429 JP2023001429W WO2023149214A1 WO 2023149214 A1 WO2023149214 A1 WO 2023149214A1 JP 2023001429 W JP2023001429 W JP 2023001429W WO 2023149214 A1 WO2023149214 A1 WO 2023149214A1
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silicon
group
secondary battery
gpa
negative electrode
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PCT/JP2023/001429
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French (fr)
Japanese (ja)
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紘太朗 武田
培新 諸
敢 武久
賢一 川瀬
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Dic株式会社
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Priority to JP2023525063A priority Critical patent/JP7453631B2/en
Publication of WO2023149214A1 publication Critical patent/WO2023149214A1/en

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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
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/907—Oxycarbides; Sulfocarbides; Mixture of carbides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/46—Metal oxides
    • 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
    • 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 silicon-based materials and composite materials containing silicon-based materials.
  • the present invention also relates to a negative electrode material for a secondary battery including the composite material, a negative electrode including the negative electrode material for a secondary battery, and a secondary battery including the negative electrode.
  • Non-aqueous electrolyte secondary batteries are used in mobile devices, hybrid vehicles, electric vehicles, household storage batteries, etc., and are required to have well-balanced characteristics such as electrical capacity, safety, and operational stability. ing. Furthermore, in recent years, along with the miniaturization of various electronic devices and communication devices and the rapid spread of hybrid vehicles, etc., as a driving power source for these devices, higher capacity and various battery characteristics such as cycle characteristics and discharge rate characteristics are required. There is a strong demand for the development of lithium-ion secondary batteries with further improved performance.
  • Non-Patent Document 1 states that silicon particles with a diameter of 150 nm or less are less prone to surface cracks and less likely to destroy their structure. However, repeated charging and discharging reduces the mechanical strength and eventually destroys the structure of the silicon particles, resulting in deterioration of battery performance.
  • Patent Document 1 proposes a method for suppressing the expansion and contraction of silicon particles by coating the silicon surface with a carbon source to form a composite.
  • the resulting composite is electrochemically stable, but carbon is softer than silicon, and expansion and contraction of silicon particles cannot be sufficiently suppressed.
  • Patent Document 2 reports a method using a composite of a sodium silicate phase and silicon particles as a method for suppressing the expansion and contraction of silicon particles, and it is reported that the higher the hardness measured by a Vickers hardness tester, the better the battery performance. has been reported. However, measurement of hardness with a Vickers hardness tester alone is not sufficient as an index for repeated expansion and contraction of Si particles.
  • the present inventors investigated a method for suppressing the expansion and contraction of silicon particles.
  • a silicon-based material having various physical properties measured mechanically using a nanoindentation method has an effect of suppressing the expansion and contraction of silicon particles, leading to the present invention.
  • the present invention relates to a negative electrode active material for a secondary battery used in a lithium ion secondary battery and a secondary battery containing the negative electrode active material for a secondary battery in a negative electrode, and provides a secondary battery having an improved capacity retention rate.
  • An object of the present invention is to provide a silicon-based material.
  • the present invention has the following aspects.
  • [1] Selected from the group consisting of an indentation hardness of 1 GPa or more and 11 GPa or less, an indentation elastic modulus of 10 GPa or more and 110 GPa or less, and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
  • a silicon-based material having at least one physical property that [2] The silicon-based material according to [1], which has an indentation hardness of 1 GPa or more and 11 GPa or less and an indentation elastic modulus of 10 GPa or more and 110 GPa in a mechanical strength measurement using a nanoindentation method.
  • [3] The silicon-based material according to [1], which has an indentation hardness of 1 GPa or more and 11 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
  • [4] The silicon-based material according to [1], which has an indentation elastic modulus of 10 GPa or more and 110 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
  • [5] The silicon-based material according to any one of [1] to [4], which contains silicon element, oxygen element, and carbon element as main components.
  • [6] The silicon-based material according to [5] above, containing SiOxCy (1 ⁇ x ⁇ 2, 1 ⁇ y ⁇ 80) as a main component.
  • [7] The silicon-based material according to [6] above, which contains a nitrogen element.
  • a negative electrode active material for a secondary battery comprising the composite material according to [8].
  • a negative electrode comprising the negative electrode active material for a secondary battery according to [9].
  • a secondary battery comprising the negative electrode described in [10] above.
  • a secondary battery negative electrode active material used in a lithium ion secondary battery and a secondary battery containing the negative electrode active material for a secondary battery in a negative electrode have an improved capacity retention rate.
  • a silicon-based material that provides
  • the silicon-based material of the present invention (hereinafter also referred to as “this silicon-based material”) has an indentation hardness of 1 GPa or more and 11 GPa or less in mechanical strength measurement using a nanoindentation method (hereinafter also referred to as “NI method”).
  • NI method nanoindentation method
  • physical property 1 an indentation modulus of 10 GPa or more and 110 GPa or less
  • physical property 2 an elastic deformation power of 20% or more and 90% or less
  • physical property 3 has at least one physical property selected from the group consisting of
  • silicon particles have a high capacity, but their volume changes greatly due to expansion and contraction during charging and discharging. As a result, it is thought that this leads to a decrease in the capacity retention rate of the secondary battery.
  • the inventors focused on the strength of the silicon-based material used for the matrix phase in which the silicon particles are dispersed. As a result, it was found that when a silicon-based material having at least one physical property selected from the group consisting of physical properties 1, 2 and 3 is used for the matrix phase, it is effective in suppressing the volume change of silicon particles. Found it. It is considered that a secondary battery having an excellent capacity retention rate was obtained by using such a composite material in which a matrix phase using a silicon-based material and silicon particles were combined as a negative electrode active material for a secondary battery.
  • the NI method is a method of measuring mechanical strength such as hardness and Young's modulus of a minute area by attaching a protruding diamond indenter using a very small diamond to the tip of the measuring device and pushing the indenter. According to the NI method, it is possible to measure the mechanical properties of minute samples and thin film samples that could not be measured by conventional hardness tests.
  • the measurement method of the NI method is standardized by ISO14577.
  • micro Vickers hardness measurement method As a means for measuring the mechanical strength of particulate matter.
  • the micro Vickers hardness measurement method can only measure the indentation hardness of the particle surface, and cannot measure the indentation elastic modulus or the elastic deformation power.
  • the indentation modulus can be measured with an atomic force microscope or the like, it is impossible to measure other physical properties at the same time. Therefore, in order to evaluate physical properties 1 to 3 of the particulate matter, it is necessary to combine these different measurement methods, which complicates the evaluation.
  • the NI method it is possible to measure the three physical properties of indentation hardness, indentation elastic modulus, and elastic deformation power by indenting the particle surface once with an indenter. That is, since it is possible to simultaneously measure the three physical properties of indentation hardness, indentation elastic modulus, and elastic deformation power at the same indentation position, the physical properties 1 to 3 can be efficiently evaluated by the NI method. can be done. Furthermore, in a silicon-based material in which silicon particles are mixed with a matrix phase containing oxygen elements or carbon elements other than silicon elements, the indentation hardness and indentation elastic modulus of the matrix phase and silicon particles may differ. It is difficult to measure an accurate value of the elastic deformation power by any method other than the method of measuring the same point.
  • the physical properties 1, 2 and 3 are values measured by the NI method, and the present silicon-based material has at least one of the physical properties 1, 2 and 3 described above. Physical properties 1, 2 and 3 can be obtained by the method specified in ISO14577. From the viewpoint of the capacity retention rate of the secondary battery when the present silicon-based material is used for the negative electrode of the secondary battery, the physical property 1 is preferably 5 GPa or more, more preferably 6 GPa or more. Further, from the viewpoint of the capacity retention rate, the physical property 1 is preferably 9 GPa or less.
  • the physical property 2 is preferably 40 GPa or more, more preferably 50 GPa or more. From the viewpoint of capacity retention rate, the physical property 2 is preferably 100 GPa or less, more preferably 80 GPa or less.
  • the physical property 3 is preferably 30% or more, more preferably 40% or more. From the viewpoint of the capacity retention rate, the physical property 3 is preferably 80% or less, more preferably 60% or less.
  • the substance constituting the silicon-based material that satisfies the physical property 1 is preferably a substance containing silicon element, carbon element and oxygen element, and it is more preferable that the content of silicon element is high within a range where the battery performance is less affected. Substances in which these elements combine to form a matrix structure are more preferred.
  • the substance constituting the silicon-based material that satisfies the physical property 2 is preferably a substance containing silicon element, carbon element and oxygen element, and preferably a substance in which silicon element and carbon element are uniformly mixed. Substances in which these elements combine to form a matrix structure are more preferred.
  • the substance constituting the silicon-based material that satisfies the physical property 3 is preferably a substance containing silicon element, carbon element and oxygen element, more preferably a substance in which silicon element and carbon element are uniformly mixed, and carbon element is silicon element. Substances containing more are even more preferred. Substances in which these elements combine to form a matrix structure are particularly preferred.
  • the present silicon-based material preferably has at least two physical properties, more preferably physical properties 2 and 3.
  • the silicon-based material is a material containing a silicon-containing compound as a main component, and the content of the silicon-containing compound is at least 50% by mass based on the total mass of the silicon-based material being 100% by mass.
  • the compound containing elemental silicon may be silicon itself.
  • the content of the compound containing silicon element in the present silicon-based material is preferably 80% by mass or more, more preferably 90% by mass or more.
  • the content of the compound containing silicon element in the present silicon-based material is preferably 100% by mass.
  • the present silicon-based material preferably contains silicon element, oxygen element and carbon element as main components from the viewpoint of exhibiting physical properties 1 to 3, and more preferably contains a compound containing silicon element, oxygen element and carbon element. preferable. It is more preferable that the present silicon-based material contains 90% by mass or more of a compound containing silicon, oxygen and carbon, based on the total mass of the silicon-based material being 100% by mass.
  • Compounds containing silicon element, oxygen element and carbon element include silicon oxycarbide/carbon composites.
  • the composite preferably contains a compound represented by the following formula (1) as a main component: SiOxCy (1) In the above formula (1), x represents the molar ratio of oxygen to silicon, and y represents the molar ratio of carbon to silicon.
  • 1 ⁇ x ⁇ 2 is preferable, and 1 ⁇ x ⁇ 1.9 is more preferable. , 1 ⁇ x ⁇ 1.8 is more preferred. Further, in order to have at least one of physical properties 1, 2 and 3, 1 ⁇ y ⁇ 80 is preferable, and 1.2 ⁇ y ⁇ 70 is more preferable.
  • this silicon-based material has a three-dimensional network structure of silicon-oxygen-carbon skeleton and a structure containing free carbon
  • the silicon-oxygen-carbon skeleton of the matrix phase has high chemical stability and has a composite structure with free carbon. Silicon particles, which will be described later, are tightly wrapped in a composite structure of silicon-oxygen-carbon skeleton and free carbon. Also, the structure of the matrix itself is hard to break, and the surface side reaction of silicon can be suppressed.
  • the silicon particles in the negative electrode play a role as the main component for the expression of charge-discharge performance, and the particles accompanying the volume change of the silicon particles during charge-discharge. is suppressed, and the capacity retention rate of the lithium secondary battery is improved.
  • the degree of deformation of the matrix phase and the destruction of the particles due to the change in the volume of the silicon particles are suppressed by the parameters affected by the indentation modulus and the elastic deformation power. Capacity retention is improved.
  • the above x and y can be obtained by measuring the mass content of each element and then converting to a molar ratio (atomic number ratio).
  • the content of oxygen and carbon can be quantified by using an inorganic elemental analyzer, and the content of silicon can be quantified by using an ICP optical emission spectrometer (ICP-OES).
  • ICP-OES ICP optical emission spectrometer
  • the present silicon-based material is locally analyzed, and a large number of measurement points for the content ratio data obtained thereby is obtained. It is also possible to analogize the content ratio of the entire active material. Local analysis includes, for example, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Electron Probe Microanalyzer (EPMA).
  • this silicon-based material has a three-dimensional network structure of a silicon-oxygen-carbon skeleton and a structure containing free carbon
  • the silicon-oxygen-carbon skeleton becomes silicon-oxygen- Changes occur in the electron distribution inside the carbon skeleton, and electrostatic bonds and coordinate bonds are formed between the silicon-oxygen-carbon skeleton and lithium ions.
  • Lithium ions are stored in the silicon-oxygen-carbon skeleton by this electrostatic bond and coordinate bond.
  • the coordination bond energy is relatively low, the desorption reaction of lithium ions easily occurs. In other words, it is considered that the silicon-oxygen-carbon skeleton can reversibly cause intercalation and deintercalation reactions of lithium ions during charging and discharging.
  • the compound represented by the formula (1) may contain nitrogen element in addition to silicon element, oxygen element and carbon element.
  • Nitrogen is a functional group in the raw material used in the manufacturing method of the active material described later, such as phenolic resin, dispersant, polysiloxane compound, other nitrogen compounds, and nitrogen gas used in the firing process. By having an atomic group containing, it can be introduced into the compound represented by the formula (1). Since the compound represented by the formula (1) contains nitrogen, the charge/discharge performance and the capacity retention rate tend to be excellent when the present silicon-based material is used as a matrix phase and used as a negative electrode active material. When the compound represented by the formula (1) contains a nitrogen element, the compound represented by the following formula (2) is preferable.
  • SiOaCbNc (2) In formula (2), a and b have the same meanings as above, and c represents the molar ratio of nitrogen to silicon.
  • the matrix phase contains the compound represented by the formula (2), in order for the compound represented by the formula (2) to have at least one of the physical properties 1, 2 and 3, 1 ⁇ a ⁇ 2, 1 ⁇ b ⁇ 80 and 0 ⁇ c ⁇ 0.5 are preferable, and 1 ⁇ a ⁇ 1.9, 1.2 ⁇ b ⁇ 70 and 0 ⁇ c ⁇ 0.4 are more preferable.
  • a, b and c can be obtained by measuring the mass content of the elements and then converting them into molar ratios (atomic number ratios). As with x and y, it is preferable to measure a, b and c by the method described above. It is also possible to acquire and analogize the content ratio of the entire active material. Local analysis includes, for example, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Electron Probe Microanalyzer (EPMA).
  • SEM-EDX Energy Dispersive X-ray Spectroscopy
  • EPMA Electron Probe Microanalyzer
  • Silicon particles having an average particle size of 200 nm or less are dispersed and composited in a matrix phase (hereinafter also referred to as the "present matrix phase") containing the present silicon-based material as a main component. material (hereinafter also referred to as “this composite material”).
  • the matrix phase in the composite material is a substance capable of intercalating and deintercalating lithium ions.
  • a substance capable of intercalating and deintercalating is a substance that can intercalate lithium ions into the matrix phase during charging of the battery and release lithium ions from the matrix phase during discharging.
  • a lithium secondary battery repeats the cycle of lithium ion absorption and discharge by this charging and discharging.
  • the present matrix phase contains the present silicon-based material as a main component, and intercalates and deintercalates lithium ions.
  • the main component is at least 50% by mass of the present silicon-based material when the total mass of the matrix phase is 100% by mass.
  • the content of the present silicon-based material in the present matrix phase is preferably 80% by mass or more, more preferably 90% by mass or more.
  • the content of the compound containing silicon element in the present silicon-based material is preferably 100% by mass.
  • the contained substance is preferably a substance capable of intercalating and releasing lithium ions.
  • substances capable of intercalating and releasing lithium ions include graphite and silicon dioxide. and titanium oxide.
  • the silicon particles dispersed in the matrix phase are composed of zero-valent silicon and have an average particle size of 200 nm or less.
  • the average particle size is a D50 value that can be measured using a laser diffraction particle size analyzer or the like. D50 can be measured by a dynamic light scattering method using a laser particle size analyzer or the like.
  • the average particle diameter of the present silicon particles is the particle diameter at which the volume cumulative distribution curve is drawn from the small diameter side in the particle diameter distribution, and the cumulative distribution is 50%.
  • Silicon particles with a large size exceeding 300 nm form large lumps, and when the composite material is used as a negative electrode active material, pulverization tends to occur during charging and discharging, so the capacity retention rate of the negative electrode active material tends to decrease. Therefore, it is preferable that the present silicon particles contain the large-sized silicon particles exceeding 300 nm and the small-sized silicon particles less than 10 nm as small as possible. From the above viewpoint, the average particle size is preferably 120 nm or less, more preferably 100 nm or less. The average particle size is preferably 10 nm or more.
  • the present silicon particles can be obtained, for example, by pulverizing a lump of silicon into particles such that the average particle size falls within the above range.
  • crushers used for crushing silicon lumps include crushers such as ball mills, bead mills, and jet mills.
  • the pulverization may be wet pulverization using an organic solvent, and as the organic solvent, for example, alcohols, ketones, etc. can be preferably used. Group hydrocarbon solvents can also be used.
  • the average particle diameter of the silicon particles can be adjusted to the above range.
  • the shape of the present silicon particles may be granular, needle-like, or flaky as long as it satisfies the above-mentioned average particle size, but the flaky shape is preferable from the viewpoint of handling.
  • the present silicon particles are flakes, it is preferable from the viewpoint of initial coulombic efficiency and capacity retention rate that the crystallite size obtained from the half width of the peak at 28.4° in the X-ray diffraction spectrum is 35 nm or less.
  • the crystallite size is more preferably 25 nm or less.
  • the present silicon particles preferably have a length in the longitudinal direction of 70 to 300 nm and a thickness of 15 to 70 nm.
  • the so-called aspect ratio which is the ratio of thickness to length, is preferably 0.5 or less.
  • the morphology of the present silicon particles can be measured by the dynamic light scattering method, but by using the analysis means of a transmission electron microscope (TEM) or a field emission scanning electron microscope (FE-SEM). , samples of said aspect ratio can be more easily and precisely identified.
  • the sample can be cut with a focused ion beam (FIB) and the cross section can be observed with FE-SEM, or the sample can be sliced and observed with TEM. can identify the state of the present silicon particles.
  • the aspect ratio of the present silicon particles is the result of calculation based on 50 particles in the main portion of the sample within the field of view shown in the TEM image.
  • the present silicon particles are dispersed in the present matrix phase.
  • the number of the present silicon particles dispersed in the present matrix phase may be one, it is preferable that a plurality of present silicon particles are dispersed in the present matrix phase.
  • the average particle size of the present composite material is preferably 0.5 ⁇ m or more and 50 ⁇ m or less.
  • the average particle size of the present composite material is more preferably 1 ⁇ m or more, particularly preferably 5 ⁇ m or more.
  • the average particle diameter of the present composite material is more preferably 30 ⁇ m or less, particularly preferably 15 ⁇ m or less.
  • the average particle size is the value of D50.
  • the specific surface area of the present composite material is preferably 0.1 m 2 /g or more and 50 m 2 /g or less.
  • the average particle size of the present composite material is more preferably 0.2 m 2 /g or more, particularly preferably 0.3 m 2 /g or more. Further, the average particle size of the present composite material is more preferably 30 m 2 /g or less, particularly preferably 20 m 2 /g or less.
  • the specific surface area is a value determined by the BET method, and can be determined by nitrogen gas adsorption measurement, for example, using a specific surface area measuring device.
  • the main component of the matrix phase is the compound represented by the formula (1), it preferably has the silicon-oxygen-carbon skeleton structure and the free carbon composed only of carbon elements.
  • this composite material has free carbon, in the Raman spectrum of this composite material, 1590 cm -1 assigned to the G band of the graphite long period carbon lattice structure and the D band of the graphite short period carbon lattice structure with disorder and defects A scattering peak is observed near 1330 cm ⁇ 1 attributed to .
  • the intensity ratio of the scattering peak intensity of the D band, I (G band), to the scattering intensity of the G band, I (D band), I (G band) / I (D band) is 0.7 or more and 2 or less. preferable.
  • the scattering peak intensity ratio, I (G band)/I (D band), is more preferably 0.7 or more and 1.8 or less.
  • the fact that the scattering peak intensity ratio, I (G band)/I (D band), is within the above range means that the free carbon in the matrix has the following properties.
  • Free carbon is mainly formed in the silicon-oxygen-carbon skeleton composed of SiO 2 C 2 , SiO 3 C, and SiO 4 , and some silicon atoms of the silicon-oxygen-carbon skeleton , electron transfer within the silicon-oxygen-carbon framework and between surface silicon atoms and free carbon is facilitated. For this reason, it is thought that when this composite material is used as a negative electrode active material of a secondary battery, the lithium ion insertion and extraction reactions during charging and discharging proceed rapidly, and the charging and discharging characteristics are improved.
  • the negative electrode active material may slightly expand and contract due to the insertion and extraction reactions of lithium ions
  • the presence of free carbon in the vicinity of the expansion and contraction of the negative electrode active material alleviates the expansion and contraction of the entire negative electrode active material. , is considered to have the effect of greatly improving the capacity retention rate.
  • Free carbon is formed along with the thermal decomposition of the silicon-containing compound and the carbon source resin, which are precursors to be described later, in an inert gas atmosphere when producing the compound represented by the formula (1).
  • the carbonizable sites in the molecular structures of the silicon-containing compound and the carbon source resin are converted into carbon components by high-temperature thermal decomposition in an inert atmosphere. Some of these carbons bond with parts of the silicon-oxygen-carbon skeleton.
  • the carbonizable component is preferably a hydrocarbon, more preferably alkyls, alkylenes, alkenes, alkynes, aromatics, and more preferably aromatics.
  • the presence of free carbon is expected to reduce the resistance of this composite material, and when this composite material is used as the negative electrode of a secondary battery, the reaction inside the composite material occurs uniformly and smoothly, resulting in charging and discharging. It is considered that a secondary battery material having an excellent balance between performance and capacity retention rate can be obtained.
  • free carbon can be introduced only from a silicon-containing compound, the combined use of a carbon source resin is expected to increase the abundance of free carbon and increase its effect.
  • the type of carbon source resin is not particularly limited, but a carbon compound containing a six-membered carbon ring is preferred.
  • the existence state of the free carbon can be identified by thermogravimetric differential thermal analysis (TG-DTA) as well as Raman spectrum. Unlike the carbon atoms in the silicon-oxygen-carbon skeleton, free carbon is easily thermally decomposed in the atmosphere, and the amount of carbon present can be determined from the amount of thermogravimetric loss measured in the presence of air. That is, the carbon content can be quantified using TG-DTA.
  • TG-DTA thermogravimetric differential thermal analysis
  • changes in thermal decomposition temperature behavior such as decomposition reaction start temperature, decomposition reaction end temperature, number of thermal decomposition reaction species, temperature of maximum weight loss for each thermal decomposition reaction species can be easily grasped. .
  • the temperature values of these behaviors can be used to determine the state of the carbon.
  • the carbon atoms in the silicon-oxygen-carbon skeleton that is, the carbon atoms bonded to the silicon atoms constituting the SiO 2 C 2 , SiO 3 C, and SiO 4 have very strong chemical bonds. It has high thermal stability, and it is thought that it will not be thermally decomposed in the air within the temperature range measured by thermal analysis equipment. Further, when the matrix phase is mainly composed of the compound represented by the formula (1), the carbon in the compound represented by the formula (1) has properties similar to those of amorphous carbon. Therefore, it is thermally decomposed in the atmosphere in the temperature range of about 550°C to 900°C. As a result, rapid weight loss occurs.
  • the maximum temperature of the TG-DTA measurement conditions is not particularly limited, but TG-DTA measurement is performed in the air under conditions from about 25° C. to about 1000° C. or higher in order to completely complete the thermal decomposition reaction of carbon. is preferred.
  • the composite material may also be surface-coated with a coating material.
  • a coating material a substance that can be expected to have electronic conductivity, lithium ion conductivity, and an effect of suppressing decomposition of the electrolytic solution is preferable.
  • the coating material include electron conductive substances such as carbon, titanium, and nickel. Among these, from the viewpoint of improving the chemical stability and thermal stability of the negative electrode active material, carbon is preferable, and low-crystalline carbon is more preferable.
  • the average thickness of the coating layer is preferably 10 nm or more and 300 nm or less.
  • the carbon coating is preferably formed on the surface of the present active material by vapor phase deposition.
  • the amount of the carbon coating is 1% by mass or more and 10% by mass or less, where the total amount of the mass of the composite material and the mass of the carbon coating is 100% by mass, from the viewpoint of improving the chemical stability and thermal stability of the composite material.
  • the mass of the present composite material is the total amount of the present matrix phase and the present silicon particles constituting the present composite material.
  • the present silicon-based material contains nitrogen, it is the total amount including nitrogen.
  • the present composite material may contain other necessary third components in addition to the above, and when the present composite material contains other third components, it is the total amount including the third component.
  • the present silicon particles can be prepared as a silicon particle slurry by using an organic solvent and pulverizing the silicon particles with a wet powder pulverizer.
  • a dispersant may be used to facilitate the grinding of the silicon particles in the organic solvent.
  • wet pulverizers include roller mills, high-speed rotary pulverizers, container-driven mills, and bead mills. In wet pulverization, it is preferable to pulverize until the silicon particles have the particle size of the present silicon particles.
  • Organic solvents used in the wet method include those that do not chemically react with silicon. Examples thereof include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; alcohols such as ethanol, methanol, normal propyl alcohol and isopropyl alcohol; aromatic benzene, toluene and xylene.
  • ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone
  • alcohols such as ethanol, methanol, normal propyl alcohol and isopropyl alcohol
  • aromatic benzene, toluene and xylene include those that do not chemically react with silicon. Examples thereof include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; alcohols such as ethanol, methanol, normal
  • Types of the dispersant include aqueous and non-aqueous dispersants.
  • a non-aqueous dispersant is preferably used in order to suppress excessive oxidation of the surface of the present silicon particles.
  • Types of non-aqueous dispersants include polymer types such as polyethers, polyalkylene polyamines, polycarboxylic acid partial alkyl esters, low molecular types such as polyhydric alcohol esters and alkylpolyamines, and polyphosphates.
  • the concentration of silicon in the silicon (zero-valent) slurry is not particularly limited, but when the solvent and optionally a dispersant are included, the total amount of the dispersant and silicon is 100% by mass, and the amount of silicon is 5% by mass. to 40% by mass, more preferably 10% to 30% by mass.
  • the composite material can be obtained by mixing the slurry of the silicon particles obtained above with the silicon-based compound material and sintering the mixture.
  • the matrix phase contains the compound of formula (1) as a main component
  • it is mixed with the mixture of the silicon particles, the polysiloxane compound, and the carbon source resin prepared as described above to form a suspension, followed by desorption.
  • a solvent is obtained to obtain a precursor.
  • the present active material is obtained by calcining the obtained precursor to obtain a calcined product, and pulverizing it as necessary.
  • the slurry of the present silicon particles can be prepared using an organic solvent while pulverizing the silicon particles with a wet powder pulverizer.
  • a dispersant may be added to the organic solvent in order to accelerate the pulverization of the silicon particles.
  • wet pulverizers include roller mills, high-speed rotary pulverizers, container-driven mills, and bead mills.
  • the organic solvent can be exemplified by the same compounds as described above.
  • examples of the dispersant include the same compounds as above, and the preferred dispersant is also as described above. Also, the concentration of silicon particles in the slurry is as described above.
  • polysiloxane compound examples include resins containing at least one of a polycarbosilane structure, a polysilazane structure, a polysilane structure and a polysiloxane structure.
  • a resin containing only these structures may be used, or a composite resin having at least one of these structures as a segment and chemically bonded to another polymer segment may be used.
  • Forms of composite include graft copolymerization, block copolymerization, random copolymerization, alternating copolymerization, and the like.
  • composite resins that have a graft structure in which polysiloxane segments and side chains of polymer segments are chemically bonded
  • composite resins that have a block structure in which polysiloxane segments are chemically bonded to the ends of polymer segments. mentioned.
  • a polysiloxane compound in which the polysiloxane segment has a structural unit represented by the following general formula (S-1) and/or the following general formula (S-2) is preferred.
  • the polysiloxane compound more preferably has a carboxy group, an epoxy group, an amino group, or a polyether group at the side chain or end of the siloxane bond (Si--O--Si) main skeleton.
  • R 1 represents an optionally substituted aromatic hydrocarbon group, an alkyl group, an epoxy group, a carboxy group, or the like.
  • R 2 and R3 represents an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, an epoxy group, a carboxy group, etc.
  • Alkyl groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 -methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylpropyl group, hexyl group, isohesyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 1,1 -dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethyl- 2-methylpropyl group, 1-ethyl-1-methylpropyl group
  • aryl groups include phenyl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-vinylphenyl, and 3-isopropylphenyl groups.
  • the aralkyl group includes, for example, a benzyl group, a diphenylmethyl group, a naphthylmethyl group and the like.
  • polymer segments other than the polysiloxane segment possessed by the polysiloxane compound include vinyl polymer segments such as acrylic polymers, fluoroolefin polymers, vinyl ester polymers, aromatic vinyl polymers, and polyolefin polymers, Examples include polymer segments such as polyurethane polymer segments, polyester polymer segments, and polyether polymer segments. Among them, a vinyl polymer segment is preferred.
  • the polysiloxane compound may be a composite resin in which polysiloxane segments and polymer segments are bonded in a structure represented by the following structural formula (S-3), or may have a three-dimensional network-like polysiloxane structure.
  • the carbon atom is the carbon atom that constitutes the polymer segment, and the two silicon atoms are the silicon atoms that constitute the polysiloxane segment
  • the polysiloxane segment of the polysiloxane compound may have a functional group capable of reacting by heating, such as a polymerizable double bond, in the polysiloxane segment.
  • a functional group capable of reacting by heating such as a polymerizable double bond
  • the cross-linking reaction proceeds and the polysiloxane compound becomes solid, thereby facilitating the thermal decomposition treatment.
  • polymerizable double bonds examples include vinyl groups and (meth)acryloyl groups. Two or more polymerizable double bonds are preferably present in the polysiloxane segment, more preferably 3 to 200, and even more preferably 3 to 50. In addition, by using a composite resin having two or more polymerizable double bonds as the polysiloxane compound, the cross-linking reaction can be facilitated.
  • the polysiloxane segment may have silanol groups and/or hydrolyzable silyl groups.
  • Hydrolyzable groups in hydrolyzable silyl groups include, for example, halogen atoms, alkoxy groups, substituted alkoxy groups, acyloxy groups, phenoxy groups, mercapto groups, amino groups, amido groups, aminooxy groups, iminooxy groups, alkenyloxy and the like, and the hydrolyzable silyl group becomes a silanol group by hydrolysis of these groups.
  • a hydrolytic condensation reaction proceeds between the hydroxyl group in the silanol group and the hydrolyzable group in the hydrolyzable silyl group, thereby obtaining a solid polysiloxane compound. can.
  • a silanol group as used in the present invention is a silicon-containing group having a hydroxyl group directly bonded to a silicon atom.
  • the hydrolyzable silyl group referred to in the present invention is a silicon-containing group having a hydrolyzable group directly bonded to a silicon atom, specifically, for example, a group represented by the following general formula (S-4) is mentioned.
  • R4 represents a monovalent organic group such as an alkyl group, an aryl group or an aralkyl group
  • R5 represents a halogen atom, an alkoxy group, an acyloxy group, an allyloxy group, a mercapto group, an amino group, an amido group, an aminooxy group, iminooxy group or alkenyloxy group
  • b is an integer of 0 to 2.
  • Alkyl groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 -methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylpropyl group, hexyl group, isohesyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 1,1 -dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethyl- 2-methylpropyl group, 1-ethyl-1-methylpropyl group
  • aryl groups include phenyl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-vinylphenyl, and 3-isopropylphenyl groups.
  • the aralkyl group includes, for example, a benzyl group, a diphenylmethyl group, a naphthylmethyl group and the like.
  • the halogen atom includes, for example, fluorine atom, chlorine atom, bromine atom, iodine atom and the like.
  • alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, and tert-butoxy groups.
  • acyloxy groups include formyloxy, acetoxy, propanoyloxy, butanoyloxy, pivaloyloxy, pentanoyloxy, phenylacetoxy, acetoacetoxy, benzoyloxy, and naphthoyloxy groups. mentioned.
  • allyloxy groups include phenyloxy groups and naphthyloxy groups.
  • alkenyloxy groups include vinyloxy, allyloxy, 1-propenyloxy, isopropenyloxy, 2-butenyloxy, 3-butenyloxy, 2-petenyloxy, 3-methyl-3-butenyloxy, 2 -hexenyloxy group and the like.
  • polysiloxane segments having structural units represented by general formula (S-1) and/or general formula (S-2) include those having the following structures.
  • the polymer segment may have various functional groups as necessary to the extent that the effects of the present invention are not impaired.
  • Such functional groups include, for example, carboxyl group, blocked carboxyl group, carboxylic anhydride group, tertiary amino group, hydroxyl group, blocked hydroxyl group, cyclocarbonate group, epoxy group, carbonyl group, primary amide group, secondary Amide, carbamate groups, functional groups represented by the following structural formula (S-5), and the like can be used.
  • polymer segment may have polymerizable double bonds such as vinyl groups and (meth)acryloyl groups.
  • the above polysiloxane compound is preferably produced, for example, by the methods shown in (1) to (3) below.
  • a polymer segment containing a silanol group and/or a hydrolyzable silyl group is prepared in advance, and the polymer segment and the silanol group and/or the hydrolyzable silyl group are and a method of mixing with a silane compound having a polymerizable double bond and carrying out a hydrolytic condensation reaction.
  • a polymer segment containing a silanol group and/or a hydrolyzable silyl group is prepared in advance.
  • Polysiloxane is also prepared in advance by subjecting a silane compound having both a silanol group and/or a hydrolyzable silyl group and a polymerizable double bond to a hydrolytic condensation reaction. Then, a method of mixing the polymer segment and polysiloxane and performing a hydrolytic condensation reaction.
  • a polysiloxane compound is obtained by the above method.
  • the polysiloxane compound include the Ceranate (registered trademark) series (organic/inorganic hybrid type coating resin; manufactured by DIC Corporation) and the Compoceran SQ series (silsesquioxane type hybrid; manufactured by Arakawa Chemical Industries, Ltd.).
  • the carbon source resin is preferably a synthetic resin or a natural chemical raw material that has good miscibility with the polysiloxane compound, is carbonized by high-temperature baking in an inert atmosphere, and has an aromatic functional group.
  • Synthetic resins include thermoplastic resins such as polyvinyl alcohol and polyacrylic acid, and thermosetting resins such as phenol resin and furan resin.
  • Natural chemical raw materials include heavy oils, especially tar pitches such as coal tar, light tar oil, medium tar oil, heavy tar oil, naphthalene oil, anthracene oil, coal tar pitch, pitch oil, mesophase pitch, and oxygen-crosslinked petroleum pitch. , heavy oil, etc., but the use of phenolic resin is more preferable from the viewpoint of inexpensive availability and removal of impurities.
  • the carbon source resin is preferably a resin containing an aromatic hydrocarbon moiety
  • the resin containing an aromatic hydrocarbon moiety is preferably a phenol resin, an epoxy resin, or a thermosetting resin
  • the phenol resin is preferably a resol type.
  • phenolic resins include the Sumilite Resin series (resol-type phenolic resin, manufactured by Sumitomo Bakelite Co., Ltd.).
  • the polysiloxane compound with a phenol resin as a carbon source resin.
  • the slurry of the present silicon particles is mixed with the mixture of the polysiloxane compound and the carbon source resin, and the solvent is removed to obtain a precursor.
  • the mixture containing the polysiloxane compound and the carbon source resin is preferably in a state in which the polysiloxane compound and the carbon source resin are uniformly mixed.
  • Said mixing is carried out using a device having the function of dispersing and mixing. Apparatuses having dispersing and mixing functions include, for example, stirrers, ultrasonic mixers, premix dispersers, and the like.
  • a dryer, a reduced-pressure dryer, a spray dryer, or the like can be used for solvent removal and drying for the purpose of distilling off the organic solvent.
  • the precursor preferably contains 15% to 85% by mass of the solid content of the polysiloxane compound, 15% to 85% by mass of the solid content of the carbon source resin, and 20% to 70% by mass of the solid content of the polysiloxane compound.
  • the solid content of the carbon source resin is more preferably 20% by mass to 70% by mass.
  • the precursor may contain 1 to 90% by mass of Si particles.
  • the precursor obtained above is fired in an inert atmosphere to completely decompose the thermally decomposable organic component to obtain a fired product.
  • the firing temperature for example, by firing at a temperature in which the maximum reaching temperature is in the range of 900° C. to 1200° C., the thermally decomposable organic component can be completely decomposed.
  • the polysiloxane compound and the carbon source resin are converted into a silicon oxycarbide phase having a silicon-oxygen-carbon skeleton and free carbon by the energy of the high temperature treatment.
  • Firing is carried out according to a firing program that is defined by the rate of temperature increase, the holding time at a certain temperature, etc.
  • the maximum attainable temperature is the maximum temperature to be set, and strongly affects the structure and performance of the fired product.
  • the fine structure of the present active material which possesses the chemical bonding state of silicon and carbon in the silicon oxycarbide phase, can be precisely controlled, and better charge-discharge characteristics can be obtained.
  • the calcination method is not particularly limited, but a reaction apparatus having a heating function may be used in an inert atmosphere, and continuous and batch processes are possible.
  • a fluidized bed reactor, a rotary furnace, a vertical moving bed reactor, a tunnel furnace, a batch furnace, a rotary kiln, or the like can be appropriately selected as the firing apparatus according to the purpose.
  • This composite material can be obtained by pulverizing the obtained fired product and classifying it as necessary.
  • the pulverization may be carried out in one step until the target particle size is obtained, or may be carried out in several steps. For example, when producing an active material of about 10 ⁇ m from a sintered mass or agglomerated particles of 10 mm or more, it is roughly pulverized with a jaw crusher, a roll crusher, etc. to particles of about 1 mm, and then pulverized to about 100 ⁇ m with a glow mill, ball mill, etc. , a bead mill, a jet mill, or the like to a size of about 10 ⁇ m.
  • Particles produced by pulverization may contain coarse particles, and in order to remove them, or to adjust the particle size distribution by removing fine powder, classification is performed.
  • the classifier to be used may be a wind classifier, a wet classifier, or the like depending on the purpose, but when removing coarse particles, the classification method through a sieve is preferable because the purpose can be reliably achieved.
  • the precursor mixture is controlled to have a shape near the target particle size by spray drying or the like before firing, and the firing is performed in that shape, the pulverization step can be omitted.
  • a secondary battery negative electrode active material containing the present composite material has an excellent capacity retention rate, and a secondary battery using the secondary battery negative electrode active material containing the present composite material as a negative electrode exhibits good characteristics.
  • a slurry of a negative electrode active material for secondary batteries containing the present composite material, an organic binder, and other components such as a conductive agent as necessary is applied in a thin film form onto a current collector copper foil. can be attached to form a negative electrode.
  • a negative electrode can also be produced by adding a carbon material such as graphite to the slurry. Carbon materials include natural graphite, artificial graphite, amorphous carbon such as hard carbon or soft carbon, and the like.
  • the present composite material and a binder that is an organic binder are kneaded together with a solvent using a dispersing device such as a stirrer, ball mill, super sand mill, pressure kneader, etc. to prepare a slurry of a negative electrode active material for a secondary battery.
  • a dispersing device such as a stirrer, ball mill, super sand mill, pressure kneader, etc.
  • a negative electrode can be obtained by applying this to a current collector to form a negative electrode layer. It can also be obtained by forming a slurry of a pasty negative electrode active material for a secondary battery into a shape such as a sheet or pellet and integrating this with a current collector.
  • organic binder examples include styrene-butadiene rubber copolymer (hereinafter also referred to as "SBR"); methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile , and ethylenically unsaturated carboxylic acid esters such as hydroxyethyl (meth)acrylate, and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid (meth)acrylic copolymerization
  • Unsaturated carboxylic acid copolymers such as coalescence; A high molecular compound is mentioned.
  • these organic binders can be dispersed or dissolved in water, or dissolved in an organic solvent such as N-methyl-2-pyrrolidone (NMP).
  • NMP N-methyl-2-pyrrolidone
  • the content ratio of the organic binder in the negative electrode layer of the lithium ion secondary battery negative electrode is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass, and 3% by mass. to 15% by mass is more preferable.
  • the resulting negative electrode active material for secondary batteries has high chemical stability, and can be used with an aqueous binder, which makes it easy to handle in terms of practical use.
  • the slurry of the negative electrode active material for secondary batteries may be mixed with a conductive additive, if necessary.
  • conductive aids include carbon black, graphite, acetylene black, oxides and nitrides exhibiting conductivity, and the like.
  • the amount of the conductive aid used may be about 1% by mass to 15% by mass with respect to the negative electrode active material of the present invention.
  • the material and shape of the current collector for example, copper, nickel, titanium, stainless steel, etc. may be used in the form of a foil, a perforated foil, a mesh, or the like in a strip shape.
  • Porous materials such as porous metal (foamed metal) and carbon paper can also be used.
  • Examples of the method for applying the slurry of the negative electrode active material for a secondary battery to the current collector include a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, and a gravure method. Examples include a coating method and a screen printing method. After coating, it is preferable to carry out a rolling treatment using a flat plate press, calendar rolls, or the like, if necessary.
  • the slurry of the negative electrode active material for a secondary battery can be formed into a sheet or pellet form, and the sheet and the current collector can be integrated by, for example, rolling, pressing, or a combination thereof.
  • the negative electrode layer formed on the current collector or the negative electrode layer integrated with the current collector is preferably heat-treated according to the organic binder used.
  • the organic binder used For example, when a water-based styrene-butadiene rubber copolymer (SBR) or the like is used, heat treatment at 100 to 130° C. is sufficient, and when an organic binder having a main skeleton of polyimide or polyamideimide is used, Heat treatment at 150 to 450° C. is preferred.
  • SBR styrene-butadiene rubber copolymer
  • This heat treatment removes the solvent and hardens the binder to increase the strength, improving the adhesion between particles and between the particles and the current collector.
  • These heat treatments are preferably performed in an inert atmosphere such as helium, argon, or nitrogen, or in a vacuum atmosphere in order to prevent oxidation of the current collector during the treatment.
  • the negative electrode using the present composite material preferably has an electrode density of 1 g/cm 3 to 1.8 g/cm 3 , more preferably 1.1 g/cm 3 to 1.7 g/cm 3 . More preferably from 0.2 g/cm 3 to 1.6 g/cm 3 .
  • the electrode density there is a tendency that the higher the electrode density, the higher the adhesion and the volume capacity density of the electrode.
  • the electrode density is too high, the voids in the electrode are reduced, which weakens the effect of suppressing the volume expansion of silicon or the like, and the capacity retention rate may decrease. Therefore, an optimum range of electrode densities is selected.
  • the secondary battery of the present invention includes the negative electrode active material for secondary batteries in the negative electrode.
  • a secondary battery having a negative electrode containing the negative electrode active material for a secondary battery a non-aqueous electrolyte secondary battery and a solid electrolyte secondary battery are preferable. performance.
  • a positive electrode and a negative electrode containing the negative electrode active material for a secondary battery of the present invention are arranged to face each other with a separator interposed therebetween. It can be configured by injecting a liquid.
  • the positive electrode can be obtained by forming a positive electrode layer on the surface of the current collector in the same manner as the negative electrode.
  • the current collector may be a strip-shaped one made of a metal or alloy such as aluminum, titanium, or stainless steel in the form of foil, foil with holes, mesh, or the like.
  • the positive electrode material used for the positive electrode layer is not particularly limited.
  • a metal compound, a metal oxide, a metal sulfide, or a conductive polymer material capable of doping or intercalating lithium ions should be used.
  • lithium cobalt oxide LiCoO 2
  • lithium nickel oxide LiNiO 2
  • lithium manganate LiMnO 2
  • lithium manganese spinel LiMn 2 O 4
  • lithium vanadium compounds V2O5 , V6O13 , VO2 , MnO2 , TiO2 , MoV2O8 , TiS2 , V2S5 , VS2 , MoS2 , MoS3 , Cr3O8 , Cr 2 O 5
  • olivine-type LiMPO 4 (where M is Co, Ni, Mn or Fe), conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene and polyacene, porous carbon, etc. can be used.
  • the separator for example, a non-woven fabric, cloth, microporous film, or a combination of them can be used, the main component of which is polyolefin such as polyethylene or polypropylene.
  • the positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery to be manufactured are structured such that they do not come into direct contact with each other, there is no need to use a separator.
  • electrolytes examples include lithium salts such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 and LiSO 3 CF 3 , ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, cyclopentanone, sulfolane.
  • the structure of the secondary battery of the present invention is not particularly limited, but usually, a positive electrode, a negative electrode, and an optional separator are wound into a flat spiral to form a wound electrode plate group. It is common to have a structure in which flat plates are laminated to form a laminated electrode plate group, and these electrode plate groups are enclosed in an outer package.
  • the half-cell used in the examples of the present invention has a structure mainly composed of this composite material for the negative electrode, and a simple evaluation is performed using metallic lithium for the counter electrode. for comparison.
  • Secondary batteries using this composite material are not particularly limited, but are used as paper-type batteries, button-type batteries, coin-type batteries, laminated-type batteries, cylindrical batteries, square-type batteries, and the like.
  • the negative electrode active material of the present invention described above can also be applied to general electrochemical devices having a charging/discharging mechanism of intercalating and deintercalating lithium ions, such as hybrid capacitors and solid lithium secondary batteries.
  • the present composite material when used as a negative electrode active material for a secondary battery, it provides a secondary battery with an improved capacity retention rate.
  • This composite material can be used as a negative electrode by the method described above to form a secondary battery having the negative electrode.
  • the silicon-based material, the composite material, the secondary battery active material containing the composite material, the negative electrode containing the secondary battery active material, and the secondary battery containing the negative electrode have been described above. It is not limited to the configuration of the embodiment.
  • the silicon-based material, the composite material, the active material for a secondary battery containing the composite material, the negative electrode containing the active material for a secondary battery, and the secondary battery containing the negative electrode have the configurations of the above embodiments, and any other Features may be added or replaced with any features that serve a similar function.
  • the present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
  • the half-cell used in the examples of the present invention has a negative electrode composed mainly of the silicon-containing active material of the present invention, and a simple evaluation using metallic lithium as the counter electrode. This is to clearly compare the cycle characteristics.
  • Synthesis Example 1 Preparation of Polysiloxane Compound 1 150 parts by mass of n-butanol (hereinafter also referred to as “n-BuOH”) was added to a reaction vessel equipped with a stirrer, thermometer, dropping funnel, cooling tube and nitrogen gas inlet. ), 249 parts by mass of phenyltrimethoxysilane (hereinafter also referred to as “PTMS”), and 263 parts by mass of dimethyldimethoxysilane (hereinafter also referred to as “DMDMS”) were charged and heated to 80°C.
  • n-BuOH n-butanol
  • MMA methyl methacrylate
  • BMA butyl methacrylate
  • BA butyric acid
  • AA acrylic acid
  • MPTS methacryloyloxypropyltrimethoxysilane
  • TPEH butylperoxy-2-ethylhexanoate
  • Synthesis Example 2 Preparation of polysiloxane compound 2 Into a reaction vessel equipped with a stirrer, thermometer, dropping funnel, cooling tube and nitrogen gas inlet, 55 parts by mass of isopropanol (hereinafter also referred to as "IPA”), 952 parts by mass of Parts of methyltrimethoxysilane (hereinafter also referred to as “MTMS”), 180 parts by mass of PTMS, and 152 parts by mass of DMDMS were charged, and the temperature was raised to 60°C.
  • IPA isopropanol
  • MTMS Parts of Parts of methyltrimethoxysilane
  • the effective ingredient is a value obtained by dividing the theoretical yield (parts by mass) when all the methoxy groups of the silane monomer such as MTMS are condensed by the actual yield (parts by mass) after the condensation reaction. Theoretical yield when all methoxy groups are condensed (parts by mass)/Actual yield after condensation reaction (parts by mass)].
  • Synthesis Example 3 Preparation of Silicon Particles Zirconia beads with a particle size of 0.1 mm to 0.2 mm and 100 ml of methyl ethyl ketone (hereinafter also referred to as "MEK") were prepared at a filling rate of 60% in a container of a 150 ml small bead mill device. Added solvent. After that, silicon powder (commercially available) with an average particle size of 5 ⁇ m and a cationic dispersant liquid (BYK-Chemie Japan Co., Ltd.: BYK145) are added, and wet milling is performed under the conditions shown in Table 1 to obtain a solid. A dark brown liquid silicon slurry having a concentration of 30% by mass was obtained. The morphology and size of the silicon particles obtained by TEM observation were confirmed, and as shown in Table 1, Si1, Si2 and Si3, respectively.
  • MEK methyl ethyl ketone
  • Example 1 The polysiloxane compound 1 prepared in Synthesis Example 1 and a phenol resin (Sumilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.) were sufficiently mixed in a stirrer at a resin solid weight ratio of 1:9. Desolvation was performed. After that, it was molded into a plate mold and dried under reduced pressure to obtain a plate-shaped dried product. The molding was high temperature fired at 1050° C. for 6 hours in a nitrogen atmosphere to obtain a black solid.
  • a phenol resin Sudilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.
  • the mechanical properties of the black solid produced as described above were measured using a nanointender measuring device (ENT-2100: manufactured by Elionix Co., Ltd.). The measurement was carried out in accordance with ISO14577. The shape of the sample is a structure that is perpendicular to the measuring indenter and is locally flat. A buffed one was used. Measurement conditions were as follows: starting load 0 mN, ending load 100 mN, number of divisions 500, step interval 20 ms loading, unloading test was measured at 20 arbitrary points, and the average value was calculated. The indentation hardness was 1.2 GPa.
  • Polysiloxane compound 1 and phenolic resin (Sumilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.) are mixed, and Si1 having an average particle size of 50 nm prepared in Synthesis Example 3 is adjusted to 50% by weight. Silicon slurry was added and mixed well in a stirrer. After that, the solvent was removed and dried under reduced pressure to obtain a precursor. It was sintered at a high temperature of 1050° C. for 6 hours in a nitrogen atmosphere, and pulverized with a planetary ball mill (ball mill P-6 classic line: manufactured by FRITSCH) to obtain a black powder. The resulting black powder was used as an active material powder for charge/discharge measurements.
  • phenolic resin Sudilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.
  • the active material powder had an average particle size of about 7.0 ⁇ m ⁇ 1.0 ⁇ m and a specific surface area of 15 m 2 /g.
  • Half-cell evaluation is carried out by mixing 8 parts by mass of the negative electrode active material, 1 part by mass of acetylene black as a conductive aid, and 1 part by mass of an organic binder, and stirring for 10 minutes with a rotation-revolution type Awatori Rentaro.
  • the slurry was adjusted by
  • the organic binder is a mixture of 0.75 parts by mass of SBR (commercial product) and 0.25 parts by mass of CMC. After coating the obtained slurry on a copper foil having a thickness of 20 ⁇ m using an applicator, it was dried at 110° C. under reduced pressure conditions to obtain an electrode thin film having a thickness of about 40 ⁇ m.
  • the obtained electrode thin film was punched into a circular electrode with a diameter of 14 mm, and in a dry room with a dew point of ⁇ 40° C. or less and a very low moisture content, Li foil was used as the counter electrode, and the electrode of the present invention was passed through a 25 ⁇ m polypropylene separator. The electrodes were opposed.
  • An electrolytic solution manufactured by Kishida Chemical Co., Ltd.
  • diethyl carbonate and ethylene carbonate at a volume ratio of 1:1 and containing 1 mol/L of LiPF 6 was adsorbed to prepare a half battery for evaluation (CR2032 type).
  • Battery characteristics are measured using a secondary battery charge-discharge test device (manufactured by Hokuto Denko), room temperature is 25 ° C., the cutoff voltage range is 0.005-1.4 V, and the charge rate is 0 from the 1st to the 3rd cycle.
  • the charging/discharging characteristics were evaluated under conditions of constant current/constant voltage type charging/discharging and constant current type charging/discharging at 0.2 C after the 4th cycle. At each charge/discharge switch, the battery was left open circuit for 30 minutes.
  • a single-layer sheet using LiCoO 2 as the positive electrode active material and aluminum foil as the current collector was used to prepare the positive electrode film, and graphite powder and A negative electrode film was produced by mixing an active material powder and a binder.
  • the composition of the active material powder was adjusted so that the charge capacity of the half cell was 1500 mAh/g, and the non-aqueous electrolyte was lithium hexafluorophosphate mixed with ethylene carbonate and diethyl carbonate in a volume ratio of 1/1.
  • a laminated lithium ion secondary battery was fabricated using a non-aqueous electrolyte solution dissolved at a concentration of 1 mol/L and using a polyethylene microporous film having a thickness of 30 ⁇ m as a separator.
  • a laminated lithium ion secondary battery is charged at room temperature at a constant current of 1.2 mA (0.25c based on the positive electrode) until the voltage of the test cell reaches 4.2 V. After reaching 4.2 V, Charging was performed by decreasing the current so as to keep the cell voltage at 4.2 V, and the discharge capacity was determined. The capacity retention rate after 300 cycles at room temperature was 72%. Table 3 shows the results.
  • Examples 2, 3, 6-8, 11-13, 16-18, 25, 26 In the same manner as in Example 1, active materials were produced with the resin composition ratios shown in Table 2, and mechanical measurements and charge/discharge characteristics of each material were evaluated. The evaluation results are shown in Tables 2 and 3.
  • Examples 23 and 24 In the same manner as in Example 1, active materials were prepared by changing the resin composition ratio and the average particle size of Si shown in Table 2 to 100 nm and 200 nm, and mechanical measurements and charge/discharge characteristics of the materials were evaluated. The evaluation results are shown in Tables 2 and 3.
  • Example 27 In the same manner as in Example 1, an active material was produced by adding melamine as a nitrogen element source to the resin composition ratio shown in Table 2, and the mechanical measurement and charge/discharge characteristics of each material were evaluated. The evaluation results are shown in Tables 2 and 3.
  • Example 1 After drying the precursor with polysiloxane resin alone or phenol resin alone, it was baked at 1050° C. for 6 hours in a nitrogen atmosphere to obtain an active material.
  • the indentation elastic moduli of the active material were 114 GPa and 4.5 GPa, and the elastic deformation power was 18% and 105%, respectively.
  • the capacity retention rates after 300 cycles at room temperature were 50% and 65%, respectively, which were greatly reduced.
  • the evaluation results are shown in Tables 2 and 3.
  • Average particle size measured using a laser diffraction particle size distribution analyzer (Mastersizer 3000, manufactured by Malvern Panalytical), and the D50 value was defined as the average particle size.
  • Specific surface area Measured by BET method from nitrogen adsorption measurement using a specific surface area measuring device (BELSORP-mini, manufactured by BEL JAPAN).
  • the indentation hardness, indentation elastic modulus, and elastic deformation power were obtained by the following methods.
  • the mechanical properties of the measurement sample were measured using a nanointender measuring device (ENT-2100: manufactured by Elionix Co., Ltd.). The measurement was carried out in accordance with ISO14577.
  • the shape of the sample is a structure that is perpendicular to the measuring indenter and is locally flat. A buffed one was used. Measurement conditions were as follows: starting load 0 mN, ending load 100 mN, number of divisions 500, step interval 20 ms loading, unloading test was measured at 20 arbitrary points, and the average value was calculated.
  • the present active material containing a silicon-based material that satisfies any of the physical properties 1 to 3 is used as the negative electrode active material, the capacity retention rate is excellent.
  • secondary batteries containing the present active material as a negative electrode active material are considered to have excellent battery characteristics.

Abstract

The present invention relates to a negative-electrode active material for secondary batteries which is for use in lithium ion secondary batteries and to a secondary battery which includes a negative electrode containing the negative-electrode active material for secondary batteries. This invention provides a silicon-based material which gives a secondary battery having an improved capacity retention.　The silicon-based material, when examined for mechanical strength by a nanoindentation method, has at least one physical property selected from among an indentation hardness of 1-11 GPa, an indentation modulus of 10-110 GPa, and an elastic-deformation power of 20-90%.

Description

ケイ素系材料、ケイ素系材料を含む複合材料、二次電池用負極物質および二次電池Silicon-based materials, composite materials containing silicon-based materials, negative electrode materials for secondary batteries, and secondary batteries
　本発明は、ケイ素系材料およびケイ素系材料を含む複合材料に関する。また本発明は前記複合材料を含む二次電池用負極物質、前記二次電池用負極物質を含む負極、前記負極を含む二次電池に関する。 The present invention relates to silicon-based materials and composite materials containing silicon-based materials. The present invention also relates to a negative electrode material for a secondary battery including the composite material, a negative electrode including the negative electrode material for a secondary battery, and a secondary battery including the negative electrode.
　非水電解質二次電池は、携帯機器を始め、ハイブリッド自動車や電気自動車、家庭用蓄電池などに用いられており、電気容量、安全性、作動安定性など複数の特性をバランスよく有することが要求されている。
　さらに近年、各種電子機器・通信機器の小型化およびハイブリッド自動車等の急速な普及に伴い、これら機器等の駆動電源として、より高容量であり、かつサイクル特性や放電レート特性等の各種電池特性が更に向上したリチウムイオン二次電池の開発が強く求められている。 Non-aqueous electrolyte secondary batteries are used in mobile devices, hybrid vehicles, electric vehicles, household storage batteries, etc., and are required to have well-balanced characteristics such as electrical capacity, safety, and operational stability. ing.
Furthermore, in recent years, along with the miniaturization of various electronic devices and communication devices and the rapid spread of hybrid vehicles, etc., as a driving power source for these devices, higher capacity and various battery characteristics such as cycle characteristics and discharge rate characteristics are required. There is a strong demand for the development of lithium-ion secondary batteries with further improved performance.
　そこで理論容量が高く、リチウムイオンを吸蔵および放出可能なシリコンが注目されている。シリコン粒子は、充放電における膨張収縮率が体積比で４倍と高いため、充放電時の膨張収縮によるシリコン粒子の破壊を抑制することが課題である。
　非特許文献１には１５０ｎｍ以下のシリコン粒子は、表面亀裂が生じにくく、その構造が破壊されにくいとされている。しかしながら、繰り返しの充放電により機械的強度が低下し、最終的には、シリコン粒子の構造が破壊され、結果として電池性能の劣化要因となっている。 Therefore, silicon, which has a high theoretical capacity and is capable of intercalating and deintercalating lithium ions, is attracting attention. Since silicon particles have a high expansion/contraction rate of four times the volume during charge/discharge, it is a problem to suppress breakage of silicon particles due to expansion/contraction during charge/discharge.
Non-Patent Document 1 states that silicon particles with a diameter of 150 nm or less are less prone to surface cracks and less likely to destroy their structure. However, repeated charging and discharging reduces the mechanical strength and eventually destroys the structure of the silicon particles, resulting in deterioration of battery performance.
　特許文献１にはシリコン粒子の膨張収縮を抑制する方法として、炭素源をシリコン表面に被覆し複合体とする方法が提案されている。得られる複合体は電気化学的に安定であるが、炭素はシリコンに比較して柔らかく、シリコン粒子の膨張収縮を十分に抑えるまでには至っていない。 Patent Document 1 proposes a method for suppressing the expansion and contraction of silicon particles by coating the silicon surface with a carbon source to form a composite. The resulting composite is electrochemically stable, but carbon is softer than silicon, and expansion and contraction of silicon particles cannot be sufficiently suppressed.
　特許文献２にはシリコン粒子の膨張収縮を抑える方法として、ナトリウムシリケート相とシリコン粒子からなる複合体による方法が報告されており、ビッカース硬度計の測定による硬さが大きいほど電池性能が向上することが報告されている。
　しかしながらビッカース硬度計による硬度の測定のみでは、Ｓｉ粒子の繰り返しの膨張収縮に対する指標としては十分でない。 Patent Document 2 reports a method using a composite of a sodium silicate phase and silicon particles as a method for suppressing the expansion and contraction of silicon particles, and it is reported that the higher the hardness measured by a Vickers hardness tester, the better the battery performance. has been reported.
However, measurement of hardness with a Vickers hardness tester alone is not sufficient as an index for repeated expansion and contraction of Si particles.
特開２０１４－１８３０４３号公報JP 2014-183043 A ＷＯ２０１９－１０７０３２号WO2019-107032
　したがってシリコン粒子の膨張収縮、および繰り返しの充放電によるシリコン粒子の構造破壊を抑制し、二次電池の容量維持率の改良の評価方法については未だ十分ではなかった。 Therefore, the method of evaluating the improvement of the capacity retention rate of secondary batteries by suppressing the expansion and contraction of silicon particles and the structural destruction of silicon particles due to repeated charging and discharging was not yet sufficient.
　本発明者らはシリコン粒子の膨張収縮を抑制する方法を検討した。その結果、ナノインデンテーション法を用いた力学測定した各種物性を有するケイ素系材料がシリコン粒子の膨張収縮の抑制効果を有することを見出し、本発明に至った。
　即ち本発明は、リチウムイオン二次電池に用いられる二次電池用負極活物質および前記二次電池用負極活物質を負極に含む二次電池に関し、容量維持率が改良された二次電池を与えるケイ素系材料を提供することを目的とする。 The present inventors investigated a method for suppressing the expansion and contraction of silicon particles. As a result, the inventors have found that a silicon-based material having various physical properties measured mechanically using a nanoindentation method has an effect of suppressing the expansion and contraction of silicon particles, leading to the present invention.
That is, the present invention relates to a negative electrode active material for a secondary battery used in a lithium ion secondary battery and a secondary battery containing the negative electrode active material for a secondary battery in a negative electrode, and provides a secondary battery having an improved capacity retention rate. An object of the present invention is to provide a silicon-based material.
　本発明は下記の態様を有する。
［１］　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａ以下、および弾性変形仕事率が２０％以上９０％以下からなる群より選択される少なくとも１の物性を有するケイ素系材料。
［２］　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下で且つ、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａである前記［１］に記載のケイ素系材料。
［３］　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下で且つ、弾性変形仕事率が２０％以上９０％以下である前記［１］に記載のケイ素系材料。
［４］　ナノインデンテーション法を用いた力学強度測定において、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａ以下で且つ、弾性変形仕事率が２０％以上９０％以下である前記［１］に記載のケイ素系材料。
［５］　主成分としてケイ素元素、酸素元素、炭素元素を含む前記［１］から［４］のいずれかに記載のケイ素系材料。
［６］　主成分としてＳｉＯｘＣｙ　（１≦ｘ＜２、１≦ｙ≦８０）を含む前記［５］に記載のケイ素系材料。
［７］　窒素元素を含む前記［６］に記載のケイ素系材料。 The present invention has the following aspects.
[1] Selected from the group consisting of an indentation hardness of 1 GPa or more and 11 GPa or less, an indentation elastic modulus of 10 GPa or more and 110 GPa or less, and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method. A silicon-based material having at least one physical property that
[2] The silicon-based material according to [1], which has an indentation hardness of 1 GPa or more and 11 GPa or less and an indentation elastic modulus of 10 GPa or more and 110 GPa in a mechanical strength measurement using a nanoindentation method.
[3] The silicon-based material according to [1], which has an indentation hardness of 1 GPa or more and 11 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
[4] The silicon-based material according to [1], which has an indentation elastic modulus of 10 GPa or more and 110 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
[5] The silicon-based material according to any one of [1] to [4], which contains silicon element, oxygen element, and carbon element as main components.
[6] The silicon-based material according to [5] above, containing SiOxCy (1≤x<2, 1≤y≤80) as a main component.
[7] The silicon-based material according to [6] above, which contains a nitrogen element.
　また本発明は下記の態様を有する。
［８］　前記［１］から［７］のいずれかに記載のケイ素系材料を主成分とするマトリクス相に平均粒径２００ｎｍ以下のシリコン粒子が分散された複合材料。 Moreover, this invention has the following aspects.
[8] A composite material in which silicon particles having an average particle size of 200 nm or less are dispersed in a matrix phase containing the silicon-based material according to any one of [1] to [7] as a main component.
　さらに本発明は下記の態様を有する。
［９］　前記［８］に記載の複合材料を含む二次電池用負極活物質。
［１０］　前記［９］に記載の二次電池用負極活物質を含む負極。
［１１］　前記［１０］に記載の負極を含む二次電池。 Furthermore, the present invention has the following aspects.
[9] A negative electrode active material for a secondary battery, comprising the composite material according to [8].
[10] A negative electrode comprising the negative electrode active material for a secondary battery according to [9].
[11] A secondary battery comprising the negative electrode described in [10] above.
　本発明によれば、リチウムイオン二次電池に用いられる二次電池用負極活物質および前記二次電池用負極活物質を負極に含む二次電池に関し、容量維持率が改良された二次電池を与えるケイ素系材料が提供される。 According to the present invention, a secondary battery negative electrode active material used in a lithium ion secondary battery and a secondary battery containing the negative electrode active material for a secondary battery in a negative electrode have an improved capacity retention rate. Provided is a silicon-based material that provides
　本発明のケイ素系材料（以下、「本ケイ素系材料」とも記す。）はナノインデンテーション法（以下、「ＮＩ法」とも記す。）を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下（以下、「物性１」とも記す。）、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａ以下（以下、「物性２」とも記す。）、および弾性変形仕事率が２０％以上９０％以下（以下、「物性３」とも記す）からなる群より選択される少なくとも１の物性を有する。
　前記のとおり、シリコン粒子は高容量であるが充放電における膨張収縮による体積変化が大きく、繰り返しの充放電による機械的強度の低下によるシリコン粒子の構造破壊が起こると考えられる。その結果、二次電池の容量維持率の低下に繋がると考えられる。 The silicon-based material of the present invention (hereinafter also referred to as "this silicon-based material") has an indentation hardness of 1 GPa or more and 11 GPa or less in mechanical strength measurement using a nanoindentation method (hereinafter also referred to as "NI method"). (hereinafter also referred to as “physical property 1”), an indentation modulus of 10 GPa or more and 110 GPa or less (hereinafter also referred to as “physical property 2”), and an elastic deformation power of 20% or more and 90% or less (hereinafter, “physical property 3”) ”) has at least one physical property selected from the group consisting of
As described above, silicon particles have a high capacity, but their volume changes greatly due to expansion and contraction during charging and discharging. As a result, it is thought that this leads to a decrease in the capacity retention rate of the secondary battery.
　本発明者らは、前記シリコン粒子の体積変化を抑えるために、シリコン粒子が分散しているマトリクス相に用いるケイ素系材料の強度に着目した。その結果、前記物性１、前記物性２および前記物性３からなる群より選択される少なくとも１つの物性を有するケイ素系材料をマトリクス相に用いると、シリコン粒子の体積変化の抑制に効果があることを見出した。このようなケイ素系材料を用いたマトリクス相とシリコン粒子を組み合わせた複合材料を二次電池用負極活物質として負極に用いることで、容量維持率に優れた二次電池が得られたと考えられる。 In order to suppress the volume change of the silicon particles, the inventors focused on the strength of the silicon-based material used for the matrix phase in which the silicon particles are dispersed. As a result, it was found that when a silicon-based material having at least one physical property selected from the group consisting of physical properties 1, 2 and 3 is used for the matrix phase, it is effective in suppressing the volume change of silicon particles. Found it. It is considered that a secondary battery having an excellent capacity retention rate was obtained by using such a composite material in which a matrix phase using a silicon-based material and silicon particles were combined as a negative electrode active material for a secondary battery.
　ＮＩ法とは測定装置に、先端に極小のダイヤモンドを使用した突起状のダイヤモンド圧子を取り付け、圧子を押し込むことで微小領域の硬さやヤング率等の力学的強度を測定する方法である。ＮＩ法によれば従来の硬さ試験では測定できなかった微小試料や薄膜試料の力学的特性を測定することができる。
　ＮＩ法の測定方法はＩＳＯ１４５７７により規格化されている。 The NI method is a method of measuring mechanical strength such as hardness and Young's modulus of a minute area by attaching a protruding diamond indenter using a very small diamond to the tip of the measuring device and pushing the indenter. According to the NI method, it is possible to measure the mechanical properties of minute samples and thin film samples that could not be measured by conventional hardness tests.
The measurement method of the NI method is standardized by ISO14577.
　従来、粒子状物質の機械的強度を測定する手段として、マイクロビッカース硬度測定法がある。しかしながら、マイクロビッカース硬度測定法では粒子表面の押し込み硬度のみ測定が可能であり、押し込み弾性率や弾性変形仕事率の測定を行うことは不可能である。また、押し込み弾性率は原子間力顕微鏡などで測定できるが、同様にその他の物性を同時に測定することは不可能である。したがって、粒子状物質の前記物性１から３の評価を行なうためには、これらの異なる測定方法を組合わせる必要があるため、評価が煩雑となる。
　一方、ＮＩ法では粒子表面に一度圧子を押し込むことで押し込み硬度、押し込み弾性率、および弾性変形仕事率の３つの物性を測定することが可能である。即ち、同じ押し込み位置での押し込み硬度、押し込み弾性率、および弾性変形仕事率の３つの物性について同時に測定を行うことが可能であることから、ＮＩ法により前記物性１から３を効率よく評価することができる。
　さらに、ケイ素元素以外の酸素元素や炭素元素を含むマトリクス相と、シリコン粒子が混在しているケイ素系材料においては、マトリクス相とシリコン粒子の押し込み硬度、および押し込み弾性率が異なることがあり、そのため同一箇所を測定する方法以外では、弾性変形仕事率の正確な値を測定することが困難となる。 Conventionally, there is a micro Vickers hardness measurement method as a means for measuring the mechanical strength of particulate matter. However, the micro Vickers hardness measurement method can only measure the indentation hardness of the particle surface, and cannot measure the indentation elastic modulus or the elastic deformation power. Also, although the indentation modulus can be measured with an atomic force microscope or the like, it is impossible to measure other physical properties at the same time. Therefore, in order to evaluate physical properties 1 to 3 of the particulate matter, it is necessary to combine these different measurement methods, which complicates the evaluation.
On the other hand, in the NI method, it is possible to measure the three physical properties of indentation hardness, indentation elastic modulus, and elastic deformation power by indenting the particle surface once with an indenter. That is, since it is possible to simultaneously measure the three physical properties of indentation hardness, indentation elastic modulus, and elastic deformation power at the same indentation position, the physical properties 1 to 3 can be efficiently evaluated by the NI method. can be done.
Furthermore, in a silicon-based material in which silicon particles are mixed with a matrix phase containing oxygen elements or carbon elements other than silicon elements, the indentation hardness and indentation elastic modulus of the matrix phase and silicon particles may differ. It is difficult to measure an accurate value of the elastic deformation power by any method other than the method of measuring the same point.
　前記物性１、物性２および物性３はＮＩ法で測定した値であり、本ケイ素系材料は前記物性１、物性２および物性３の少なくとも一つの物性を有する。物性１、物性２および物性３はＩＳＯ１４５７７で規定されている方法で求めることができる。
　本ケイ素系材料を二次電池の負極に用いた場合の二次電池の容量維持率の観点から、前記物性１は５ＧＰａ以上が好ましく、６ＧＰａ以上がより好ましい。また前記物性１は容量維持率の観点から、９ＧＰａ以下が好ましい。 The physical properties 1, 2 and 3 are values measured by the NI method, and the present silicon-based material has at least one of the physical properties 1, 2 and 3 described above. Physical properties 1, 2 and 3 can be obtained by the method specified in ISO14577.
From the viewpoint of the capacity retention rate of the secondary battery when the present silicon-based material is used for the negative electrode of the secondary battery, the physical property 1 is preferably 5 GPa or more, more preferably 6 GPa or more. Further, from the viewpoint of the capacity retention rate, the physical property 1 is preferably 9 GPa or less.
　本ケイ素系材料を二次電池の負極に用いた場合の二次電池の容量維持率の観点から、前記物性２は４０ＧＰａ以上が好ましく、５０ＧＰａ以上がより好ましい。また前記物性２は容量維持率の観点から、１００ＧＰａ以下が好ましく、８０ＧＰａ以下がより好ましい。 From the viewpoint of the capacity retention rate of the secondary battery when the present silicon-based material is used for the negative electrode of the secondary battery, the physical property 2 is preferably 40 GPa or more, more preferably 50 GPa or more. From the viewpoint of capacity retention rate, the physical property 2 is preferably 100 GPa or less, more preferably 80 GPa or less.
　本ケイ素系材料を二次電池の負極に用いた場合の二次電池の容量維持率の観点から、前記物性３は３０％以上が好ましく、４０％以上がより好ましい。また前記物性３は容量維持率の観点から、８０％以下が好ましく、６０％以下がより好ましい。 From the viewpoint of the capacity retention rate of the secondary battery when the present silicon-based material is used for the negative electrode of the secondary battery, the physical property 3 is preferably 30% or more, more preferably 40% or more. From the viewpoint of the capacity retention rate, the physical property 3 is preferably 80% or less, more preferably 60% or less.
　前記物性１を満たすケイ素系材料を構成する物質は、珪素元素と炭素元素と酸素元素を含む物質が好ましく、電池性能に影響の少ない範囲で珪素元素の含有率が高い方がより好ましい。これら元素が結合してマトリックス構造になっている物質がさらに好ましい。 The substance constituting the silicon-based material that satisfies the physical property 1 is preferably a substance containing silicon element, carbon element and oxygen element, and it is more preferable that the content of silicon element is high within a range where the battery performance is less affected. Substances in which these elements combine to form a matrix structure are more preferred.
　前記物性２を満たすケイ素系材料を構成する物質は、珪素元素と炭素元素と酸素元素を含む物質が好ましく、珪素元素と炭素元素が均一に混合している物質が好ましい。これら元素が結合してマトリックス構造になっている物質がさらに好ましい。 The substance constituting the silicon-based material that satisfies the physical property 2 is preferably a substance containing silicon element, carbon element and oxygen element, and preferably a substance in which silicon element and carbon element are uniformly mixed. Substances in which these elements combine to form a matrix structure are more preferred.
　前記物性３を満たすケイ素系材料を構成する物質は、珪素元素と炭素元素と酸素元素を含む物質が好ましく、珪素元素と炭素元素を均一に混合している物質がより好ましく、炭素元素を珪素元素より多く含む物質がさらに好ましい。これら元素が結合してマトリックス構造になっている物質が特に好ましい。 The substance constituting the silicon-based material that satisfies the physical property 3 is preferably a substance containing silicon element, carbon element and oxygen element, more preferably a substance in which silicon element and carbon element are uniformly mixed, and carbon element is silicon element. Substances containing more are even more preferred. Substances in which these elements combine to form a matrix structure are particularly preferred.
　本ケイ素系材料は前記物性１、物性２および物性３の内、少なくとも２つの物性を有するのが好ましく、物性２と物性３を有するのがより好ましい。 Of the physical properties 1, 2 and 3, the present silicon-based material preferably has at least two physical properties, more preferably physical properties 2 and 3.
　なおケイ素系材料とはケイ素元素を有する化合物を主成分として含有する材料であり、ケイ素系材料の全質量を１００質量％として、ケイ素元素を有する化合物の含有量が少なくとも５０質量％である。ケイ素元素を含有する化合物はケイ素そのものでもよい。
　本ケイ素系材料中のケイ素元素を有する化合物の含有量は８０質量％以上が好ましく、９０質量％以上がより好ましい。
　本ケイ素系材料中のケイ素元素を有する化合物の含有量は１００質量％が好ましい。 The silicon-based material is a material containing a silicon-containing compound as a main component, and the content of the silicon-containing compound is at least 50% by mass based on the total mass of the silicon-based material being 100% by mass. The compound containing elemental silicon may be silicon itself.
The content of the compound containing silicon element in the present silicon-based material is preferably 80% by mass or more, more preferably 90% by mass or more.
The content of the compound containing silicon element in the present silicon-based material is preferably 100% by mass.
　本ケイ素系材料中、主成分としてケイ素元素、酸素元素および炭素元素を含むのが、物性１から３の特性を示す観点から好ましく、ケイ素元素、酸素元素および炭素元素を含む化合物を含むのがより好ましい。本ケイ素系材料は、ケイ素系材料の全質量を１００質量％として、ケイ素元素、酸素元素および炭素元素を含む化合物を９０質量％以上含有するのがさらに好ましい。ケイ素元素、酸素元素および炭素元素を含む化合物としてシリコンオキシカーバイド／カーボン複合体が挙げられる。
　前記複合体は、主成分として下記式（１）で表される化合物を含有するのが好ましい
　　　ＳｉＯｘＣｙ　　　（１）
　前記式（１）中、ｘはケイ素に対する酸素のモル比、ｙはケイ素に対する炭素のモル比を表す。
　前記式（１）で表される化合物において、前記物性１、物性２および物性３の少なくとも１の物性を有するためには、１≦ｘ＜２が好ましく、１≦ｘ≦１．９がより好ましく、１≦ｘ≦１．８がさらに好ましい。
　また、前記物性１、物性２および物性３の少なくとも１の物性を有するためには、１≦ｙ≦８０が好ましく、１．２≦ｙ≦７０がより好ましい。 The present silicon-based material preferably contains silicon element, oxygen element and carbon element as main components from the viewpoint of exhibiting physical properties 1 to 3, and more preferably contains a compound containing silicon element, oxygen element and carbon element. preferable. It is more preferable that the present silicon-based material contains 90% by mass or more of a compound containing silicon, oxygen and carbon, based on the total mass of the silicon-based material being 100% by mass. Compounds containing silicon element, oxygen element and carbon element include silicon oxycarbide/carbon composites.
The composite preferably contains a compound represented by the following formula (1) as a main component: SiOxCy (1)
In the above formula (1), x represents the molar ratio of oxygen to silicon, and y represents the molar ratio of carbon to silicon.
In order for the compound represented by the formula (1) to have at least one of physical properties 1, 2 and 3, 1 ≤ x < 2 is preferable, and 1 ≤ x ≤ 1.9 is more preferable. , 1≦x≦1.8 is more preferred.
Further, in order to have at least one of physical properties 1, 2 and 3, 1≦y≦80 is preferable, and 1.2≦y≦70 is more preferable.
　本ケイ素系材料の主成分がケイ素－酸素－炭素骨格の三次元ネットワーク構造とフリー炭素を含む構造を有する場合、本ケイ素系材料をマトリクス相に用いた時に、マトリクス相のケイ素－酸素－炭素骨格は化学安定性が高く、フリー炭素との複合構造をとり、このマトリックス構造の変形度合いは小さく、割れにくい。
　後述するシリコン粒子がケイ素－酸素－炭素骨格とフリー炭素との複合構造体に密に包まれることで、リチウムの吸蔵および放出に対するシリコン粒子の体積変化及び膨張が抑制され、ケイ素の膨張に対しても、マトリックスの構造自体が割れにくくケイ素の表面副反応を抑えることが出来る。その結果、本ケイ素系材料を含む複合材料を負極に用いた場合、負極中のシリコン粒子が充放電性能発現の主要成分とする役割を果たしながら、充放電時に本シリコン粒子の体積変化に伴う粒子の破壊を抑制し、リチウム二次電池の容量維持率が改良される。
　このマトリックス相の変形度合いとシリコン粒子の体積変化に伴う粒子の破壊を抑制するのは、押し込み弾性率と弾性変形仕事率が影響するパラメータであり、この値を制御することによってリチウム二次電池の容量維持率が改良される。 When the main component of this silicon-based material has a three-dimensional network structure of silicon-oxygen-carbon skeleton and a structure containing free carbon, when this silicon-based material is used for the matrix phase, the silicon-oxygen-carbon skeleton of the matrix phase has high chemical stability and has a composite structure with free carbon.
Silicon particles, which will be described later, are tightly wrapped in a composite structure of silicon-oxygen-carbon skeleton and free carbon. Also, the structure of the matrix itself is hard to break, and the surface side reaction of silicon can be suppressed. As a result, when a composite material containing this silicon-based material is used for the negative electrode, the silicon particles in the negative electrode play a role as the main component for the expression of charge-discharge performance, and the particles accompanying the volume change of the silicon particles during charge-discharge. is suppressed, and the capacity retention rate of the lithium secondary battery is improved.
The degree of deformation of the matrix phase and the destruction of the particles due to the change in the volume of the silicon particles are suppressed by the parameters affected by the indentation modulus and the elastic deformation power. Capacity retention is improved.
　前記ｘおよびｙはそれぞれの元素の質量含有量を測定した後、モル比（原子数比）に換算することにより求めることができる。この際、酸素と炭素は無機元素分析装置を使用することによって、その含有量を定量でき、ケイ素の含有量はＩＣＰ発光分析装置（ＩＣＰ－ＯＥＳ）を使用することによって定量できる。
　なお、前記ｘおよびｙの測定は上記記載方法によって実施することが好ましいが、本ケイ素系材料の局所的な分析を行い、それにより得られた含有比データの測定点数を多く取得して、本活物質全体の含有比を類推することでも可能である。局所的な分析としては、例えばエネルギー分散型Ｘ線分光法（ＳＥＭ－ＥＤＸ）や電子線プローブマイクロアナライザ（ＥＰＭＡ）が挙げられる。 The above x and y can be obtained by measuring the mass content of each element and then converting to a molar ratio (atomic number ratio). At this time, the content of oxygen and carbon can be quantified by using an inorganic elemental analyzer, and the content of silicon can be quantified by using an ICP optical emission spectrometer (ICP-OES).
Although it is preferable to measure x and y by the method described above, the present silicon-based material is locally analyzed, and a large number of measurement points for the content ratio data obtained thereby is obtained. It is also possible to analogize the content ratio of the entire active material. Local analysis includes, for example, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Electron Probe Microanalyzer (EPMA).
　また本ケイ素系材料の主成分がケイ素－酸素－炭素骨格の三次元ネットワーク構造とフリー炭素を含む構造を有していると、ケイ素－酸素－炭素骨格は、リチウムイオンの接近によりケイ素－酸素－炭素骨格の内部の電子分布に変動が生じ、ケイ素－酸素－炭素骨格とリチウムイオンの間に静電的な結合や配位結合などが形成される。この静電的な結合や配位結合によりリチウムイオンがケイ素－酸素－炭素骨格中に貯蔵される。一方、配位結合エネルギーは比較的低いため、リチウムイオンの脱離反応が容易に行われる。つまりケイ素－酸素－炭素骨格が充放電の際にリチウムイオンの挿入と脱離反応を可逆的に起こすことができると考えられる。 In addition, if the main component of this silicon-based material has a three-dimensional network structure of a silicon-oxygen-carbon skeleton and a structure containing free carbon, the silicon-oxygen-carbon skeleton becomes silicon-oxygen- Changes occur in the electron distribution inside the carbon skeleton, and electrostatic bonds and coordinate bonds are formed between the silicon-oxygen-carbon skeleton and lithium ions. Lithium ions are stored in the silicon-oxygen-carbon skeleton by this electrostatic bond and coordinate bond. On the other hand, since the coordination bond energy is relatively low, the desorption reaction of lithium ions easily occurs. In other words, it is considered that the silicon-oxygen-carbon skeleton can reversibly cause intercalation and deintercalation reactions of lithium ions during charging and discharging.
　前記式（１）で表される化合物はケイ素元素、酸素元素、炭素元素以外に窒素元素を含んでもよい。窒素は後述する本活物質の製造方法において、使用する原料、例えばフェノール樹脂、分散剤、ポリシロキサン化合物、その他の窒素化合物、および焼成プロセスで用いる窒素ガス等がその分子内に官能基として窒素を含む原子団を有することで、前記式（１）で表される化合物に導入することができる。前記式（１）で表される化合物が窒素を含むことで、本ケイ素系材料をマトリクス相に用い負極活物質とした時の充放電性能や容量維持率に優れる傾向にある。
　前記式（１）で表される化合物が窒素元素を含む場合、下記式（２）で表される化合物が好ましい。
　　　ＳｉＯａＣｂＮｃ　　　（２）
式（２）中、ａおよびｂは前記と同じ意味であり、ｃはケイ素に対する窒素のモル比を表す。
　マトリクス相が前記式（２）で表される化合物を含む場合、前記式（２）で表される化合物において、前記物性１、物性２および物性３の少なくとも１の物性を有するためには、１≦ａ≦２、１≦ｂ≦８０、０＜ｃ≦０．５が好ましく、１≦ａ≦１．９、１．２≦ｂ≦７０、０＜ｃ≦０．４がより好ましい。 The compound represented by the formula (1) may contain nitrogen element in addition to silicon element, oxygen element and carbon element. Nitrogen is a functional group in the raw material used in the manufacturing method of the active material described later, such as phenolic resin, dispersant, polysiloxane compound, other nitrogen compounds, and nitrogen gas used in the firing process. By having an atomic group containing, it can be introduced into the compound represented by the formula (1). Since the compound represented by the formula (1) contains nitrogen, the charge/discharge performance and the capacity retention rate tend to be excellent when the present silicon-based material is used as a matrix phase and used as a negative electrode active material.
When the compound represented by the formula (1) contains a nitrogen element, the compound represented by the following formula (2) is preferable.
SiOaCbNc (2)
In formula (2), a and b have the same meanings as above, and c represents the molar ratio of nitrogen to silicon.
When the matrix phase contains the compound represented by the formula (2), in order for the compound represented by the formula (2) to have at least one of the physical properties 1, 2 and 3, 1 ≤a≤2, 1≤b≤80 and 0<c≤0.5 are preferable, and 1≤a≤1.9, 1.2≤b≤70 and 0<c≤0.4 are more preferable.
　前記ａ、ｂおよびｃは前記ｘおよびｙと同様、元素の質量含有量を測定した後、モル比（原子数比）に換算することにより求めることができる。
　前記ｘおよびｙと同様、ａ、ｂおよびｃの測定は上記記載方法によって実施することが好ましいが、本活物質の局所的な分析を行い、それにより得られた含有比データの測定点数を多く取得して、本活物質全体の含有比を類推することでも可能である。局所的な分析としては、例えばエネルギー分散型Ｘ線分光法（ＳＥＭ－ＥＤＸ）や電子線プローブマイクロアナライザ（ＥＰＭＡ）が挙げられる。 Similar to x and y, a, b and c can be obtained by measuring the mass content of the elements and then converting them into molar ratios (atomic number ratios).
As with x and y, it is preferable to measure a, b and c by the method described above. It is also possible to acquire and analogize the content ratio of the entire active material. Local analysis includes, for example, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Electron Probe Microanalyzer (EPMA).
　前記本ケイ素系材料を主成分とするマトリクス相（以下、「本マトリクス相」とも記す。）に平均粒径が２００ｎｍ以下のシリコン粒子（以下、「本シリコン粒子」とも記す。）を分散させ複合材料（以下、「本複合材料」とも記す。）とすることができる。
　複合材料におけるマトリクス相はリチウムイオンを吸蔵放出が可能な物質である。吸蔵放出が可能な物質とは、電池の充電時にリチウムイオンをマトリクス相内に吸蔵し、放電時にリチウムイオンをマトリクス相内から放出することができる物質である。リチウム二次電池はこの充電と放電によるリチウムイオンの吸蔵と放電のサイクルが繰り返される。 Silicon particles having an average particle size of 200 nm or less (hereinafter also referred to as "the present silicon particles") are dispersed and composited in a matrix phase (hereinafter also referred to as the "present matrix phase") containing the present silicon-based material as a main component. material (hereinafter also referred to as "this composite material").
The matrix phase in the composite material is a substance capable of intercalating and deintercalating lithium ions. A substance capable of intercalating and deintercalating is a substance that can intercalate lithium ions into the matrix phase during charging of the battery and release lithium ions from the matrix phase during discharging. A lithium secondary battery repeats the cycle of lithium ion absorption and discharge by this charging and discharging.
　本マトリクス相は前記本ケイ素系材料を主成分であり、リチウムイオンを吸蔵放出する。主成分とはマトリクス相の全質量を１００質量％として、本ケイ素系材料の含有量が少なくとも５０質量％である。
　本マトリクス相中の本ケイ素系材料の含有量は８０質量％以上が好ましく、９０質量％以上がより好ましい。
　本ケイ素系材料中のケイ素元素を有する化合物の含有量は１００質量％が好ましい。 The present matrix phase contains the present silicon-based material as a main component, and intercalates and deintercalates lithium ions. The main component is at least 50% by mass of the present silicon-based material when the total mass of the matrix phase is 100% by mass.
The content of the present silicon-based material in the present matrix phase is preferably 80% by mass or more, more preferably 90% by mass or more.
The content of the compound containing silicon element in the present silicon-based material is preferably 100% by mass.
　本マトリクス相が本ケイ素系材料以外の物質を含有する場合、含有する物質はリチウムイオンを吸蔵放出が可能な物質であるのが好ましく、リチウムイオンを吸蔵放出が可能な物質としては黒鉛、二酸化ケイ素および酸化チタンが挙げられる。 When the present matrix phase contains a substance other than the present silicon-based material, the contained substance is preferably a substance capable of intercalating and releasing lithium ions. Examples of substances capable of intercalating and releasing lithium ions include graphite and silicon dioxide. and titanium oxide.
　本マトリクス相中に分散される本シリコン粒子は０価のケイ素から構成され、平均粒径は２００ｎｍ以下である。
　ここで平均粒径はレーザー回折式粒度分析計などを用いて測定することができるＤ５０の値である。Ｄ５０はレーザー粒度分析計などを用い動的光散乱法により測定することができる。本シリコン粒子の平均粒径は、粒子径分布において、小径側から体積累積分布曲線を描いた場合に、累積５０％となるときの粒子径である。 The silicon particles dispersed in the matrix phase are composed of zero-valent silicon and have an average particle size of 200 nm or less.
Here, the average particle size is a D50 value that can be measured using a laser diffraction particle size analyzer or the like. D50 can be measured by a dynamic light scattering method using a laser particle size analyzer or the like. The average particle diameter of the present silicon particles is the particle diameter at which the volume cumulative distribution curve is drawn from the small diameter side in the particle diameter distribution, and the cumulative distribution is 50%.
　３００ｎｍを超える大サイズのシリコン粒子は、大きな塊となり、本複合材料を負極活物質とした時、充放電時に微粉化現象が起りやすいため、負極活物質の容量維持率が低下する傾向がある。
　したがって、本シリコン粒子は３００ｎｍを超える大サイズのシリコン粒子および１０ｎｍ未満の小サイズのシリコン粒子の含有割合が出来るだけ小さいことが好ましい。
　前記の観点から、平均粒径は１２０ｎｍ以下が好ましく、１００ｎｍ以下がより好ましい。平均粒径は１０ｎｍ以上が好ましい。 Silicon particles with a large size exceeding 300 nm form large lumps, and when the composite material is used as a negative electrode active material, pulverization tends to occur during charging and discharging, so the capacity retention rate of the negative electrode active material tends to decrease.
Therefore, it is preferable that the present silicon particles contain the large-sized silicon particles exceeding 300 nm and the small-sized silicon particles less than 10 nm as small as possible.
From the above viewpoint, the average particle size is preferably 120 nm or less, more preferably 100 nm or less. The average particle size is preferably 10 nm or more.
　本シリコン粒子は、例えばシリコンの塊を平均粒径が前記範囲となるように粉砕などで粒子化し、得ることができる。
　シリコンの塊の粉砕に用いる粉砕機としては、ボールミル、ビーズミル、ジェットミルなどの粉砕機が例示できる。また、粉砕は有機溶剤を用いた湿式粉砕であってもよく、有機溶剤としては、例えば、アルコール類、ケトン類などを好適に用いることができるが、トルエン、キシレン、ナフタレン、メチルナフタレンなどの芳香族炭化水素系溶剤も用いることができる。
　得られたシリコンの粒子を、ビーズ粒径、配合率、回転数または粉砕時間などのビーズミルの条件を制御し、分級等することで本シリコン粒子の平均粒径を前記範囲とすることができる。 The present silicon particles can be obtained, for example, by pulverizing a lump of silicon into particles such that the average particle size falls within the above range.
Examples of crushers used for crushing silicon lumps include crushers such as ball mills, bead mills, and jet mills. In addition, the pulverization may be wet pulverization using an organic solvent, and as the organic solvent, for example, alcohols, ketones, etc. can be preferably used. Group hydrocarbon solvents can also be used.
By controlling the bead mill conditions such as the bead diameter, blending ratio, rotation speed or grinding time, and classifying the obtained silicon particles, the average particle diameter of the silicon particles can be adjusted to the above range.
　本シリコン粒子の形状は前記平均粒径を満たす範囲であれば、粒状、針状、フレーク状のいずれでもよいが、フレーク状が取り扱いの観点から好ましい。本シリコン粒子がフレーク状の場合、Ｘ線回折スペクトルにおける２θが２８．４°のピーク半値幅から得られる結晶子サイズが３５ｎｍ以下であれば、初期クーロン効率および容量維持率の観点から好ましい。結晶子サイズは２５ｎｍ以下がより好ましい。 The shape of the present silicon particles may be granular, needle-like, or flaky as long as it satisfies the above-mentioned average particle size, but the flaky shape is preferable from the viewpoint of handling. When the present silicon particles are flakes, it is preferable from the viewpoint of initial coulombic efficiency and capacity retention rate that the crystallite size obtained from the half width of the peak at 28.4° in the X-ray diffraction spectrum is 35 nm or less. The crystallite size is more preferably 25 nm or less.
　本シリコン粒子は、本複合材料を負極活物質とした時の充放電性能の観点から、長軸方向の長さが７０から３００ｎｍが好ましく、厚みは１５から７０ｎｍが好ましい。負極活物質とした時の充放電性能の観点から、長さに対する厚みの比である、いわゆるアスペクト比が０．５以下であることが好ましい。
　本シリコン粒子の形態は、動的光散乱法で平均粒径の測定が可能であるが、透過型電子顕微鏡（ＴＥＭ）や電界放出型走査電子顕微鏡（ＦＥ－ＳＥＭ）の解析手段を用いることで、前記アスペクト比のサンプルをより容易かつ精密に同定することができる。本発明の二次電池用材料を含有する負極活物質の場合は、サンプルを集束イオンビーム（ＦＩＢ）で切断して断面をＦＥ－ＳＥＭ観察することができ、またはサンプルをスライス加工してＴＥＭ観察により本シリコン粒子の状態を同定することができる。
　なお前記本シリコン粒子のアスペクト比は、ＴＥＭ画像に映る視野内のサンプルの主要部分５０粒子をベースにした計算結果である。 From the viewpoint of charge/discharge performance when the present composite material is used as a negative electrode active material, the present silicon particles preferably have a length in the longitudinal direction of 70 to 300 nm and a thickness of 15 to 70 nm. From the viewpoint of charge/discharge performance when used as a negative electrode active material, the so-called aspect ratio, which is the ratio of thickness to length, is preferably 0.5 or less.
The morphology of the present silicon particles can be measured by the dynamic light scattering method, but by using the analysis means of a transmission electron microscope (TEM) or a field emission scanning electron microscope (FE-SEM). , samples of said aspect ratio can be more easily and precisely identified. In the case of the negative electrode active material containing the secondary battery material of the present invention, the sample can be cut with a focused ion beam (FIB) and the cross section can be observed with FE-SEM, or the sample can be sliced and observed with TEM. can identify the state of the present silicon particles.
The aspect ratio of the present silicon particles is the result of calculation based on 50 particles in the main portion of the sample within the field of view shown in the TEM image.
　本複合材料は前記本マトリクス相中に前記本シリコン粒子が分散している。本マトリクス相中に分散している本シリコン粒子の数は１つでもよいが、複数の本シリコン粒子が本マトリクス相中に分散しているのが好ましい。 In the present composite material, the present silicon particles are dispersed in the present matrix phase. Although the number of the present silicon particles dispersed in the present matrix phase may be one, it is preferable that a plurality of present silicon particles are dispersed in the present matrix phase.
　本複合材料の平均粒径が小さすぎると、比表面積の大幅な上昇につれ、本複合材料を活物活物質として二次電池とした時、充放電時に固相界面電解質分解物の生成量が増えることで単位体積当たりの可逆充放電容量が低下することがある。本複合材料の平均粒径が大きすぎると、電極膜作製時に集電体から剥離するおそれがある。
　したがって本複合材料の平均粒径は０．５μｍ以上５０μｍ以下が好ましい。本複合材料の平均粒径は１μｍ以上がより好ましく、５μｍ以上が特に好ましい。また、本複合材料の平均粒径は３０μｍ以下がより好ましく、１５μｍ以下が特に好ましい。平均粒径は前記Ｄ５０の値である。 If the average particle size of the composite material is too small, the amount of solid-phase interfacial electrolyte decomposition products generated during charging and discharging increases when the composite material is used as an active material in a secondary battery as the specific surface area increases significantly. As a result, the reversible charge/discharge capacity per unit volume may decrease. If the average particle size of the present composite material is too large, there is a risk that the composite material will peel off from the current collector during the production of the electrode film.
Therefore, the average particle size of the present composite material is preferably 0.5 μm or more and 50 μm or less. The average particle size of the present composite material is more preferably 1 μm or more, particularly preferably 5 μm or more. Further, the average particle diameter of the present composite material is more preferably 30 μm or less, particularly preferably 15 μm or less. The average particle size is the value of D50.
　本複合材料の比表面積は０．１ｍ２／ｇ以上５０ｍ２／ｇ以下が好ましい。本複合材料の平均粒径は０．２ｍ２／ｇ以上がより好ましく、０．３ｍ２／ｇ以上が特に好ましい。また、本複合材料の平均粒径は３０ｍ２／ｇ以下がより好ましく、２０ｍ２／ｇ以下が特に好ましい。比表面積が前記範囲であると、電極作製時における溶媒の吸収量を適切に保つことができ、結着性を維持するための結着剤の使用量も適切に保つことができる。なお前記比表面積はＢＥＴ法により求めた値であり、窒素ガス吸着測定により求めることができ、例えば比表面積測定装置を用いて測定することができる。 The specific surface area of the present composite material is preferably 0.1 m 2 /g or more and 50 m 2 /g or less. The average particle size of the present composite material is more preferably 0.2 m 2 /g or more, particularly preferably 0.3 m 2 /g or more. Further, the average particle size of the present composite material is more preferably 30 m 2 /g or less, particularly preferably 20 m 2 /g or less. When the specific surface area is within the above range, the amount of solvent absorbed during electrode production can be appropriately maintained, and the amount of binder used for maintaining binding properties can also be properly maintained. The specific surface area is a value determined by the BET method, and can be determined by nitrogen gas adsorption measurement, for example, using a specific surface area measuring device.
　本マトリクス相が前記式（１）で表される化合物を主成分とする場合、ケイ素－酸素－炭素骨格構造とともに炭素元素のみで構成される前記フリー炭素を有しているのが好ましい。本複合材料がフリー炭素を有する場合、本複合材料のラマンスペクトルにおいて、グラファイト長周期炭素格子構造のＧバンドに帰属される１５９０ｃｍ－１と、乱れや欠陥のあるグラファイト短周期炭素格子構造のＤバンドに帰属される１３３０ｃｍ－１付近の散乱ピークが観測される。Ｄバンドの散乱ピーク強度、Ｉ（Ｇバンド）、に対するＧバンドの散乱強度、Ｉ（Ｄバンド）、の強度比、Ｉ（Ｇバンド）／Ｉ（Ｄバンド）が、０．７以上２以下が好ましい。前記散乱ピーク強度比、Ｉ（Ｇバンド）／Ｉ（Ｄバンド）は０．７以上１．８以下がより好ましい。前記散乱ピーク強度比、Ｉ（Ｇバンド）／Ｉ（Ｄバンド）が前記の範囲であるということは、マトリクス中のフリー炭素において以下のことが言える。 When the main component of the matrix phase is the compound represented by the formula (1), it preferably has the silicon-oxygen-carbon skeleton structure and the free carbon composed only of carbon elements. When this composite material has free carbon, in the Raman spectrum of this composite material, 1590 cm -1 assigned to the G band of the graphite long period carbon lattice structure and the D band of the graphite short period carbon lattice structure with disorder and defects A scattering peak is observed near 1330 cm −1 attributed to . The intensity ratio of the scattering peak intensity of the D band, I (G band), to the scattering intensity of the G band, I (D band), I (G band) / I (D band) is 0.7 or more and 2 or less. preferable. The scattering peak intensity ratio, I (G band)/I (D band), is more preferably 0.7 or more and 1.8 or less. The fact that the scattering peak intensity ratio, I (G band)/I (D band), is within the above range means that the free carbon in the matrix has the following properties.
　フリー炭素の一部の炭素原子は、ケイ素－酸素－炭素骨格中の一部のケイ素原子と結合している。このフリー炭素は、充放電特性に影響を与える重要な成分である。フリー炭素は主に、ＳｉＯ２Ｃ２，ＳｉＯ３Ｃ、およびＳｉＯ４で構成されるケイ素－酸素－炭素骨格中に形成しているものであり、ケイ素－酸素－炭素骨格の一部のケイ素原子と結合しているため、ケイ素－酸素－炭素骨格内部、および表面のケイ素原子とフリー炭素間の電子伝達がより容易となる。このため本複合材料を二次電池の負極活物質として用いた時の充放電時のリチウムイオンの挿入および離脱反応が速やかに進行し、充放電特性が向上すると考えられる。また、リチウムイオンの挿入および脱離反応によって、負極活物質は僅かではあるが膨張および収縮することがあるが、フリー炭素がその近傍に存在することで負極活物質全体の膨張および収縮が緩和され、容量維持率を大きく向上させる効果があると考えられる。 Some of the free carbon atoms are bonded to some silicon atoms in the silicon-oxygen-carbon framework. This free carbon is an important component that affects charge/discharge characteristics. Free carbon is mainly formed in the silicon-oxygen-carbon skeleton composed of SiO 2 C 2 , SiO 3 C, and SiO 4 , and some silicon atoms of the silicon-oxygen-carbon skeleton , electron transfer within the silicon-oxygen-carbon framework and between surface silicon atoms and free carbon is facilitated. For this reason, it is thought that when this composite material is used as a negative electrode active material of a secondary battery, the lithium ion insertion and extraction reactions during charging and discharging proceed rapidly, and the charging and discharging characteristics are improved. In addition, although the negative electrode active material may slightly expand and contract due to the insertion and extraction reactions of lithium ions, the presence of free carbon in the vicinity of the expansion and contraction of the negative electrode active material alleviates the expansion and contraction of the entire negative electrode active material. , is considered to have the effect of greatly improving the capacity retention rate.
　フリー炭素は、前記式（１）で表される化合物を製造する際に後述する前駆体であるケイ素含有化合物および炭素源樹脂の不活性ガス雰囲気中の熱分解に伴い形成する。具体的にはケイ素含有化合物および炭素源樹脂の分子構造中にある炭化可能な部位が不活性化する雰囲気中で高温熱分解によって炭素成分となる。これらの一部の炭素がケイ素－酸素－炭素骨格の一部と結合する。炭化可能な成分は、炭化水素が好ましく、アルキル類、アルキレン類、アルケン類、アルキン類、芳香族類がより好ましく、その中でも芳香族類であることがさらに好ましい。 Free carbon is formed along with the thermal decomposition of the silicon-containing compound and the carbon source resin, which are precursors to be described later, in an inert gas atmosphere when producing the compound represented by the formula (1). Specifically, the carbonizable sites in the molecular structures of the silicon-containing compound and the carbon source resin are converted into carbon components by high-temperature thermal decomposition in an inert atmosphere. Some of these carbons bond with parts of the silicon-oxygen-carbon skeleton. The carbonizable component is preferably a hydrocarbon, more preferably alkyls, alkylenes, alkenes, alkynes, aromatics, and more preferably aromatics.
　また、フリー炭素が存在することにより、本複合材料の抵抗低減効果が期待され、二次電池の負極として本複合材料を使用した場合、本複合材料内部の反応が均一かつスムーズに起こり、充放電性能と容量維持率のバランスに優れた二次電池用材料が得られると考えられる。フリー炭素の導入はケイ素含有化合物由来だけでも可能であるが、炭素源樹脂を併用することにより、フリー炭素の存在量とその効果の増大が期待される。炭素源樹脂の種類は、特に限定されてないが、炭素の六員環を含む炭素化合物が好ましい。 In addition, the presence of free carbon is expected to reduce the resistance of this composite material, and when this composite material is used as the negative electrode of a secondary battery, the reaction inside the composite material occurs uniformly and smoothly, resulting in charging and discharging. It is considered that a secondary battery material having an excellent balance between performance and capacity retention rate can be obtained. Although free carbon can be introduced only from a silicon-containing compound, the combined use of a carbon source resin is expected to increase the abundance of free carbon and increase its effect. The type of carbon source resin is not particularly limited, but a carbon compound containing a six-membered carbon ring is preferred.
　前記フリー炭素の存在状態は、ラマンスペクトル以外に熱重量示差熱分析装置（ＴＧ－ＤＴＡ）でも同定することが可能である。ケイ素－酸素－炭素骨格中の炭素原子と異なり、フリー炭素は、大気中で熱分解されやすく、空気存在下で測定した熱重量減少量により炭素の存在量を求めることができる。つまり炭素量は、ＴＧ－ＤＴＡを用いることで定量できる。
　また、熱重量減少挙動より、分解反応開始温度、分解反応終了温度、熱分解反応種の数、各熱分解反応種における最大重量減少量の温度などの熱分解温度挙動の変化も容易に把握できる。これら挙動の温度値を用いて炭素の状態を判断することができる。一方、ケイ素－酸素－炭素骨格中の炭素原子、すなわち前記ＳｉＯ２Ｃ２、ＳｉＯ３Ｃ、およびＳｉＯ４を構成するケイ素原子と結合している炭素原子は、非常に強い化学結合を有するために熱安定性が高く、熱分析装置測定の温度範囲内では大気中で熱分解されることがないと考えられる。また、本マトリクス相が前記式（１）で表される化合物を主成分として構成される場合、前記式（１）で表される化合物中の炭素は、非晶質炭素と類似する特性を有しているため、大気中において約５５０℃から９００℃の温度範囲に熱分解される。その結果、急激な重量減少が発生する。ＴＧ－ＤＴＡの測定条件の最高温度は特に限定されないが、炭素の熱分解反応を完全に終了させるために、大気中、約２５℃から約１０００℃以上までの条件下でＴＧ－ＤＴＡ測定を行うのが好ましい。 The existence state of the free carbon can be identified by thermogravimetric differential thermal analysis (TG-DTA) as well as Raman spectrum. Unlike the carbon atoms in the silicon-oxygen-carbon skeleton, free carbon is easily thermally decomposed in the atmosphere, and the amount of carbon present can be determined from the amount of thermogravimetric loss measured in the presence of air. That is, the carbon content can be quantified using TG-DTA.
In addition, from the thermal weight loss behavior, changes in thermal decomposition temperature behavior such as decomposition reaction start temperature, decomposition reaction end temperature, number of thermal decomposition reaction species, temperature of maximum weight loss for each thermal decomposition reaction species can be easily grasped. . The temperature values of these behaviors can be used to determine the state of the carbon. On the other hand, the carbon atoms in the silicon-oxygen-carbon skeleton, that is, the carbon atoms bonded to the silicon atoms constituting the SiO 2 C 2 , SiO 3 C, and SiO 4 have very strong chemical bonds. It has high thermal stability, and it is thought that it will not be thermally decomposed in the air within the temperature range measured by thermal analysis equipment. Further, when the matrix phase is mainly composed of the compound represented by the formula (1), the carbon in the compound represented by the formula (1) has properties similar to those of amorphous carbon. Therefore, it is thermally decomposed in the atmosphere in the temperature range of about 550°C to 900°C. As a result, rapid weight loss occurs. The maximum temperature of the TG-DTA measurement conditions is not particularly limited, but TG-DTA measurement is performed in the air under conditions from about 25° C. to about 1000° C. or higher in order to completely complete the thermal decomposition reaction of carbon. is preferred.
　また本複合材料は被覆材により表面が被覆されていてもよい。被覆材としては、電子伝導性、リチウムイオン伝導性、電解液の分解抑制効果が期待出来る物質が好ましい。
　前記被覆材としては、炭素、チタン、ニッケル等の電子伝導性物質が挙げられる。これらの中でも、負極活物質の化学安定性や熱安定性改善の観点から、炭素が好ましく、低結晶性炭素がより好ましい。 The composite material may also be surface-coated with a coating material. As the coating material, a substance that can be expected to have electronic conductivity, lithium ion conductivity, and an effect of suppressing decomposition of the electrolytic solution is preferable.
Examples of the coating material include electron conductive substances such as carbon, titanium, and nickel. Among these, from the viewpoint of improving the chemical stability and thermal stability of the negative electrode active material, carbon is preferable, and low-crystalline carbon is more preferable.
　被覆材が低結晶性炭素の場合、被覆層の平均厚みは１０ｎｍ以上３００ｎｍ以下、または、低結晶性炭素の含有量は本活物質の全量を１００質量％として、１から３０質量％が好ましい。
　被覆材が炭素の場合、炭素の被膜は気相沈積法により本活物質表面に作成するのが好ましい。炭素の被膜の量は本複合材料の質量と炭素の被膜の質量の合計量を１００質量％として、１質量％以上１０質量％以下が本複合材料の化学安定性や熱安定性の改善の観点から好ましい。
　なお本複合材料の質量とは、本複合材料を構成する本マトリクス相および本シリコン粒子の合計量である。本ケイ素系材料が窒素を含む場合は、窒素も含む合計量である。また本複合材料は前記以外に他の必要な第三成分を含んでもよく、本複合材料が他の第三成分を含む場合、第三成分も含む合計量である。 When the coating material is low-crystalline carbon, the average thickness of the coating layer is preferably 10 nm or more and 300 nm or less.
When the coating material is carbon, the carbon coating is preferably formed on the surface of the present active material by vapor phase deposition. The amount of the carbon coating is 1% by mass or more and 10% by mass or less, where the total amount of the mass of the composite material and the mass of the carbon coating is 100% by mass, from the viewpoint of improving the chemical stability and thermal stability of the composite material. preferred from
The mass of the present composite material is the total amount of the present matrix phase and the present silicon particles constituting the present composite material. When the present silicon-based material contains nitrogen, it is the total amount including nitrogen. In addition, the present composite material may contain other necessary third components in addition to the above, and when the present composite material contains other third components, it is the total amount including the third component.
　本シリコン粒子は、有機溶媒を用いシリコン粒子を湿式粉末粉砕装置にて粉砕しながら行うことでシリコン粒子スラリーとして調整することができる。有機溶媒においてシリコン粒子の粉砕を促進させるために分散剤を用いても良い。湿式粉砕装置としては、例えば、ローラーミル、高速回転粉砕機、容器駆動型ミル、ビーズミルなどが挙げられる。
　湿式粉砕ではシリコン粒子が本シリコン粒子の粒径となるまで粉砕するのが好ましい。 The present silicon particles can be prepared as a silicon particle slurry by using an organic solvent and pulverizing the silicon particles with a wet powder pulverizer. A dispersant may be used to facilitate the grinding of the silicon particles in the organic solvent. Examples of wet pulverizers include roller mills, high-speed rotary pulverizers, container-driven mills, and bead mills.
In wet pulverization, it is preferable to pulverize until the silicon particles have the particle size of the present silicon particles.
　湿式法で用いる有機溶媒は、シリコンと化学反応しない有機溶媒が挙げられる。例えば、ケトン類のアセトン、メチルエチルケトン、メチルイソブチルケトン、ジイソブチルケトン；アルコール類のエタノール、メタノール、ノルマルプロピルアルコール、イソプロピルアルコール；芳香族のベンゼン、トルエン、キシレンなどが挙げられる。 Organic solvents used in the wet method include those that do not chemically react with silicon. Examples thereof include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; alcohols such as ethanol, methanol, normal propyl alcohol and isopropyl alcohol; aromatic benzene, toluene and xylene.
　前記分散剤の種類は、水系や非水系の分散剤が挙げられる。本シリコン粒子の表面に対する過剰酸化を抑制するため、非水系分散剤の使用が好ましい。非水系分散剤の種類は、ポリエーテル系、ポリアルキレンポリアミン系、ポリカルボン酸部分アルキルエステル系などの高分子型、多価アルコールエステル系、アルキルポリアミン系などの低分子型、ポリリン酸塩系などの無機型が例示される。ケイ素（０価）スラリーにおけるケイ素の濃度は特に限定されないが、前記溶媒および、必要に応じて分散剤を含む場合は分散剤とケイ素の合計量を１００質量％として、ケイ素の量は５質量％から４０質量％の範囲が好ましく、１０質量％から３０質量％がより好ましい。 Types of the dispersant include aqueous and non-aqueous dispersants. A non-aqueous dispersant is preferably used in order to suppress excessive oxidation of the surface of the present silicon particles. Types of non-aqueous dispersants include polymer types such as polyethers, polyalkylene polyamines, polycarboxylic acid partial alkyl esters, low molecular types such as polyhydric alcohol esters and alkylpolyamines, and polyphosphates. is exemplified by the inorganic type of The concentration of silicon in the silicon (zero-valent) slurry is not particularly limited, but when the solvent and optionally a dispersant are included, the total amount of the dispersant and silicon is 100% by mass, and the amount of silicon is 5% by mass. to 40% by mass, more preferably 10% to 30% by mass.
　前記で得られた本シリコン粒子のスラリーを、本ケイ素系化合物物質と混合し、焼成することで本複合材料が得られる。
　例えばマトリクス相が主成分として前記式（１）の化合物を含む場合、前記のようにして調整された本シリコン粒子とポリシロキサン化合物と炭素源樹脂との混合物と混合して懸濁液とし、脱溶媒して前駆体が得られる。得られた前駆体を焼成して焼成物を得、必要に応じて粉砕することで本活物質が得られる。
　本シリコン粒子のスラリーは、有機溶媒を用い、シリコン粒子を湿式粉末粉砕装置にて粉砕しながら調整することができる。シリコン粒子の粉砕を促進させるために有機溶媒に分散剤を添加して用いても良い。湿式粉砕装置としてはローラーミル、高速回転粉砕機、容器駆動型ミル、ビーズミルなどが挙げられる。
　有機溶媒は、前記と同じ化合物が例示できる。
　分散剤の種類も前記と同じ化合物が例示でき、好ましい分散剤の種類も前記のとおりである。またスラリー中のシリコン粒子の濃度も前記のとおりである。 The composite material can be obtained by mixing the slurry of the silicon particles obtained above with the silicon-based compound material and sintering the mixture.
For example, when the matrix phase contains the compound of formula (1) as a main component, it is mixed with the mixture of the silicon particles, the polysiloxane compound, and the carbon source resin prepared as described above to form a suspension, followed by desorption. A solvent is obtained to obtain a precursor. The present active material is obtained by calcining the obtained precursor to obtain a calcined product, and pulverizing it as necessary.
The slurry of the present silicon particles can be prepared using an organic solvent while pulverizing the silicon particles with a wet powder pulverizer. A dispersant may be added to the organic solvent in order to accelerate the pulverization of the silicon particles. Examples of wet pulverizers include roller mills, high-speed rotary pulverizers, container-driven mills, and bead mills.
The organic solvent can be exemplified by the same compounds as described above.
Examples of the dispersant include the same compounds as above, and the preferred dispersant is also as described above. Also, the concentration of silicon particles in the slurry is as described above.
　前記ポリシロキサン化合物としては、ポリカルボシラン構造、ポリシラザン構造、ポリシラン構造およびポリシロキサン構造を少なくとも１つ含む樹脂が挙げられる。これらの構造のみを含む樹脂であっても良く、これら構造の少なくとも一つをセグメントとして有し、他の重合体セグメントと化学的に結合した複合型樹脂でも良い。複合化の形態はグラフト共重合、ブロック共重合、ランダム共重合、交互共重合などがある。例えば、ポリシロキサンセグメントと重合体セグメントの側鎖に化学的に結合したグラフト構造を有する複合樹脂があり、重合体セグメントの末端にポリシロキサンセグメントが化学的に結合したブロック構造を有する複合樹脂等が挙げられる。 Examples of the polysiloxane compound include resins containing at least one of a polycarbosilane structure, a polysilazane structure, a polysilane structure and a polysiloxane structure. A resin containing only these structures may be used, or a composite resin having at least one of these structures as a segment and chemically bonded to another polymer segment may be used. Forms of composite include graft copolymerization, block copolymerization, random copolymerization, alternating copolymerization, and the like. For example, there are composite resins that have a graft structure in which polysiloxane segments and side chains of polymer segments are chemically bonded, and there are composite resins that have a block structure in which polysiloxane segments are chemically bonded to the ends of polymer segments. mentioned.
　ポリシロキサンセグメントが、下記一般式（Ｓ－１）および／または下記一般式（Ｓ－２）で表される構造単位を有するポリシロキサン化合物が好ましい。なかでもポリシロキサン化合物が、シロキサン結合（Ｓｉ－Ｏ－Ｓｉ）主骨格の側鎖または末端に、カルボキシ基、エポキシ基、アミノ基、またはポリエーテル基を有することがより好ましい。 A polysiloxane compound in which the polysiloxane segment has a structural unit represented by the following general formula (S-1) and/or the following general formula (S-2) is preferred. Among them, the polysiloxane compound more preferably has a carboxy group, an epoxy group, an amino group, or a polyether group at the side chain or end of the siloxane bond (Si--O--Si) main skeleton.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000002
 （前記一般式（Ｓ－１）および（Ｓ－２）中、Ｒ１は置換基を有していてもよい芳香族炭化水素基またはアルキル基、エポキシ基、カルボキシ基などを表す。Ｒ２およびＲ３は、それぞれアルキル基、シクロアルキル基、アリール基またはアラルキル基、エポキシ基、カルボキシ基などを示す。）
Figure JPOXMLDOC01-appb-C000002
 (In general formulas (S-1) and (S-2) above, R 1 represents an optionally substituted aromatic hydrocarbon group, an alkyl group, an epoxy group, a carboxy group, or the like. R 2 and R3 represents an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, an epoxy group, a carboxy group, etc.)
　アルキル基としては、例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ｔｅｒｔ－ペンチル基、１－メチルブチル基、２－メチルブチル基、１，２－ジメチルプロピル基、１－エチルプロピル基、ヘキシル基、イソヘシル基、１－メチルペンチル基、２－メチルペンチル基、３－メチルペンチル基、１，１－ジメチルブチル基、１，２－ジメチルブチル基、２，２－ジメチルブチル基、１－エチルブチル基、１，１，２－トリメチルプロピル基、１，２，２－トリメチルプロピル基、１－エチル－２－メチルプロピル基、１－エチル－１－メチルプロピル基等が挙げられる。前記のシクロアルキル基としては、例えば、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロヘキシル基等が挙げられる。 Alkyl groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 -methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylpropyl group, hexyl group, isohesyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 1,1 -dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethyl- 2-methylpropyl group, 1-ethyl-1-methylpropyl group and the like. Examples of the cycloalkyl group include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group and the like.
　アリール基としては、例えば、フェニル基、ナフチル基、２－メチルフェニル基、３－メチルフェニル基、４－メチルフェニル基、４－ビニルフェニル基、３－イソプロピルフェニル基等が挙げられる。 Examples of aryl groups include phenyl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-vinylphenyl, and 3-isopropylphenyl groups.
　アラルキル基としては、例えば、ベンジル基、ジフェニルメチル基、ナフチルメチル基等が挙げられる。 The aralkyl group includes, for example, a benzyl group, a diphenylmethyl group, a naphthylmethyl group and the like.
　ポリシロキサン化合物が有するポリシロキサンセグメント以外の重合体セグメントとしては、例えば、アクリル重合体、フルオロオレフィン重合体、ビニルエステル重合体、芳香族系ビニル重合体、ポリオレフィン重合体等のビニル重合体セグメントや、ポリウレタン重合体セグメント、ポリエステル重合体セグメント、ポリエーテル重合体セグメント等の重合体セグメント等が挙げられる。中でも、ビニル重合体セグメントが好ましい。 Examples of polymer segments other than the polysiloxane segment possessed by the polysiloxane compound include vinyl polymer segments such as acrylic polymers, fluoroolefin polymers, vinyl ester polymers, aromatic vinyl polymers, and polyolefin polymers, Examples include polymer segments such as polyurethane polymer segments, polyester polymer segments, and polyether polymer segments. Among them, a vinyl polymer segment is preferred.
　ポリシロキサン化合物が、ポリシロキサンセグメントと重合体セグメントとが下記の構造式（Ｓ－３）で示される構造で結合した複合樹脂でもよく、三次元網目状のポリシロキサン構造を有してもよい。 The polysiloxane compound may be a composite resin in which polysiloxane segments and polymer segments are bonded in a structure represented by the following structural formula (S-3), or may have a three-dimensional network-like polysiloxane structure.
Figure JPOXMLDOC01-appb-C000003
 （式中、炭素原子は重合体セグメントを構成する炭素原子であり、２個のケイ素原子はポリシロキサンセグメントを構成するケイ素原子である）
Figure JPOXMLDOC01-appb-C000003
 (Wherein, the carbon atom is the carbon atom that constitutes the polymer segment, and the two silicon atoms are the silicon atoms that constitute the polysiloxane segment)
　ポリシロキサン化合物が有するポリシロキサンセグメントは、ポリシロキサンセグメント中に重合性二重結合など加熱により反応が可能な官能基を有していてもよい。熱分解前にポリシロキサン化合物を加熱処理することにより、架橋反応が進行し、固体状とすることにより、熱分解処理を容易に行うことができる。 The polysiloxane segment of the polysiloxane compound may have a functional group capable of reacting by heating, such as a polymerizable double bond, in the polysiloxane segment. By heat-treating the polysiloxane compound before thermal decomposition, the cross-linking reaction proceeds and the polysiloxane compound becomes solid, thereby facilitating the thermal decomposition treatment.
　重合性二重結合としては、例えば、ビニル基や（メタ）アクリロイル基等が挙げられる。重合性二重結合は、ポリシロキサンセグメント中に２つ以上存在することが好ましく３から２００個存在することがより好ましく、３から５０個存在することが更に好ましい。また、ポリシロキサン化合物として重合性二重結合が２個以上存在する複合樹脂を使用することによって、架橋反応が容易に進行させることができる。 Examples of polymerizable double bonds include vinyl groups and (meth)acryloyl groups. Two or more polymerizable double bonds are preferably present in the polysiloxane segment, more preferably 3 to 200, and even more preferably 3 to 50. In addition, by using a composite resin having two or more polymerizable double bonds as the polysiloxane compound, the cross-linking reaction can be facilitated.
　ポリシロキサンセグメントは、シラノール基および／または加水分解性シリル基を有してもよい。加水分解性シリル基中の加水分解性基としては、例えば、ハロゲン原子、アルコキシ基、置換アルコキシ基、アシロキシ基、フェノキシ基、メルカプト基、アミノ基、アミド基、アミノオキシ基、イミノオキシ基、アルケニルオキシ基等が挙げられ、これらの基が加水分解されることにより加水分解性シリル基はシラノール基となる。前記熱硬化反応と並行して、シラノール基中の水酸基や加水分解性シリル基中の前記加水分解性基の間で加水分解縮合反応が進行することで、固体状のポリシロキサン化合物を得ることができる。 The polysiloxane segment may have silanol groups and/or hydrolyzable silyl groups. Hydrolyzable groups in hydrolyzable silyl groups include, for example, halogen atoms, alkoxy groups, substituted alkoxy groups, acyloxy groups, phenoxy groups, mercapto groups, amino groups, amido groups, aminooxy groups, iminooxy groups, alkenyloxy and the like, and the hydrolyzable silyl group becomes a silanol group by hydrolysis of these groups. In parallel with the thermosetting reaction, a hydrolytic condensation reaction proceeds between the hydroxyl group in the silanol group and the hydrolyzable group in the hydrolyzable silyl group, thereby obtaining a solid polysiloxane compound. can.
　本発明でいうシラノール基とはケイ素原子に直接結合した水酸基を有するケイ素含有基である。本発明で言う加水分解性シリル基とはケイ素原子に直接結合した加水分解性基を有するケイ素含有基であり、具体的には、例えば、下記の一般式（Ｓ－４）で表される基が挙げられる。 A silanol group as used in the present invention is a silicon-containing group having a hydroxyl group directly bonded to a silicon atom. The hydrolyzable silyl group referred to in the present invention is a silicon-containing group having a hydrolyzable group directly bonded to a silicon atom, specifically, for example, a group represented by the following general formula (S-4) is mentioned.
Figure JPOXMLDOC01-appb-C000004
 （式中、Ｒ４はアルキル基、アリール基またはアラルキル基等の１価の有機基を、Ｒ５はハロゲン原子、アルコキシ基、アシロキシ基、アリルオキシ基、メルカプト基、アミノ基、アミド基、アミノオキシ基、イミノオキシ基またはアルケニルオキシ基である。またｂは０から２の整数である。）
Figure JPOXMLDOC01-appb-C000004
 (wherein R4 represents a monovalent organic group such as an alkyl group, an aryl group or an aralkyl group; R5 represents a halogen atom, an alkoxy group, an acyloxy group, an allyloxy group, a mercapto group, an amino group, an amido group, an aminooxy group, iminooxy group or alkenyloxy group, and b is an integer of 0 to 2.)
　アルキル基としては、例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ｔｅｒｔ－ペンチル基、１－メチルブチル基、２－メチルブチル基、１，２－ジメチルプロピル基、１－エチルプロピル基、ヘキシル基、イソヘシル基、１－メチルペンチル基、２－メチルペンチル基、３－メチルペンチル基、１，１－ジメチルブチル基、１，２－ジメチルブチル基、２，２－ジメチルブチル基、１－エチルブチル基、１，１，２－トリメチルプロピル基、１，２，２－トリメチルプロピル基、１－エチル－２－メチルプロピル基、１－エチル－１－メチルプロピル基等が挙げられる。 Alkyl groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 -methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylpropyl group, hexyl group, isohesyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 1,1 -dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethyl- 2-methylpropyl group, 1-ethyl-1-methylpropyl group and the like.
　アリール基としては、例えば、フェニル基、ナフチル基、２－メチルフェニル基、３－メチルフェニル基、４－メチルフェニル基、４－ビニルフェニル基、３－イソプロピルフェニル基等が挙げられる。 Examples of aryl groups include phenyl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-vinylphenyl, and 3-isopropylphenyl groups.
　アラルキル基としては、例えば、ベンジル基、ジフェニルメチル基、ナフチルメチル基等が挙げられる。 The aralkyl group includes, for example, a benzyl group, a diphenylmethyl group, a naphthylmethyl group and the like.
　ハロゲン原子としては、例えば、フッ素原子、塩素原子、臭素原子、ヨウ素原子等が挙げられる。 The halogen atom includes, for example, fluorine atom, chlorine atom, bromine atom, iodine atom and the like.
　アルコキシ基としては、例えば、メトキシ基、エトキシ基、プロポキシ基、イソプロポキシ基、ブトキシ基、第二ブトキシ基、第三ブトキシ基等が挙げられる。 Examples of alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, and tert-butoxy groups.
　アシロキシ基としては、例えば、ホルミルオキシ基、アセトキシ基、プロパノイルオキシ基、ブタノイルオキシ基、ピバロイルオキシ基、ペンタノイルオキシ基、フェニルアセトキシ基、アセトアセトキシ基、ベンゾイルオキシ基、ナフトイルオキシ基等が挙げられる。 Examples of acyloxy groups include formyloxy, acetoxy, propanoyloxy, butanoyloxy, pivaloyloxy, pentanoyloxy, phenylacetoxy, acetoacetoxy, benzoyloxy, and naphthoyloxy groups. mentioned.
　アリルオキシ基としては、例えば、フェニルオキシ基、ナフチルオキシ基等が挙げられる。 Examples of allyloxy groups include phenyloxy groups and naphthyloxy groups.
　アルケニルオキシ基としては、例えば、ビニルオキシ基、アリルオキシ基、１－プロペニルオキシ基、イソプロペニルオキシ基、２－ブテニルオキシ基、３－ブテニルオキシ基、２－ペテニルオキシ基、３－メチル－３－ブテニルオキシ基、２－ヘキセニルオキシ基等が挙げられる。 Examples of alkenyloxy groups include vinyloxy, allyloxy, 1-propenyloxy, isopropenyloxy, 2-butenyloxy, 3-butenyloxy, 2-petenyloxy, 3-methyl-3-butenyloxy, 2 -hexenyloxy group and the like.
　前記一般式（Ｓ－１）および／または前記一般式（Ｓ－２）で示される構造単位を有するポリシロキサンセグメントとしては、例えば以下の構造を有するもの等が挙げられる。 Examples of polysiloxane segments having structural units represented by general formula (S-1) and/or general formula (S-2) include those having the following structures.
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000005
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000006
Figure JPOXMLDOC01-appb-C000007
Figure JPOXMLDOC01-appb-C000007
　重合体セグメントは、本発明の効果を阻害しない範囲で、必要に応じて各種官能基を有していても良い。かかる官能基としては、例えばカルボキシル基、ブロックされたカルボキシル基、カルボン酸無水基、３級アミノ基、水酸基、ブロックされた水酸基、シクロカーボネート基、エポキシ基、カルボニル基、１級アミド基、２級アミド、カーバメート基、下記の構造式（Ｓ－５）で表される官能基等を使用することができる。 The polymer segment may have various functional groups as necessary to the extent that the effects of the present invention are not impaired. Such functional groups include, for example, carboxyl group, blocked carboxyl group, carboxylic anhydride group, tertiary amino group, hydroxyl group, blocked hydroxyl group, cyclocarbonate group, epoxy group, carbonyl group, primary amide group, secondary Amide, carbamate groups, functional groups represented by the following structural formula (S-5), and the like can be used.
Figure JPOXMLDOC01-appb-C000008
Figure JPOXMLDOC01-appb-C000008
　また、前記重合体セグメントは、ビニル基、（メタ）アクリロイル基等の重合性二重結合を有していてもよい。 In addition, the polymer segment may have polymerizable double bonds such as vinyl groups and (meth)acryloyl groups.
　上記ポリシロキサン化合物は、例えば、下記（１）から（３）に示す方法で製造することが好ましい。 The above polysiloxane compound is preferably produced, for example, by the methods shown in (1) to (3) below.
　（１）前記重合体セグメントの原料として、シラノール基および／または加水分解性シリル基を含有する重合体セグメントを予め調製しておき、この重合体セグメントと、シラノール基および／または加水分解性シリル基、並びに重合性二重結合を併有するシラン化合物とを混合し、加水分解縮合反応を行う方法。 (1) As a raw material for the polymer segment, a polymer segment containing a silanol group and/or a hydrolyzable silyl group is prepared in advance, and the polymer segment and the silanol group and/or the hydrolyzable silyl group are and a method of mixing with a silane compound having a polymerizable double bond and carrying out a hydrolytic condensation reaction.
　（２）前記重合体セグメントの原料として、シラノール基および／または加水分解性シリル基を含有する重合体セグメントを予め調製する。また、シラノール基および／または加水分解性シリル基、並びに重合性二重結合を併有するシラン化合物を加水分解縮合反応してポリシロキサンも予め調製しておく。そして、重合体セグメントとポリシロキサンとを混合し、加水分解縮合反応を行う方法。 (2) As a raw material for the polymer segment, a polymer segment containing a silanol group and/or a hydrolyzable silyl group is prepared in advance. Polysiloxane is also prepared in advance by subjecting a silane compound having both a silanol group and/or a hydrolyzable silyl group and a polymerizable double bond to a hydrolytic condensation reaction. Then, a method of mixing the polymer segment and polysiloxane and performing a hydrolytic condensation reaction.
　（３）前記重合体セグメントと、シラノール基および／または加水分解性シリル基、並びに重合性二重結合を併有するシラン化合物と、ポリシロキサンとを混合し、加水分解縮合反応を行う方法。
　前記方法によりポリシロキサン化合物が得られる。
　ポリシロキサン化合物としては、例えば、セラネート（登録商標）シリーズ（有機・無機ハイブリッド型コーティング樹脂；ＤＩＣ株式会社製）やコンポセランＳＱシリーズ（シルセスキオキサン型ハイブリッド；荒川化学工業株式会社製）が挙げられる。 (3) A method of mixing the polymer segment, a silane compound having both a silanol group and/or a hydrolyzable silyl group and a polymerizable double bond, and polysiloxane, and performing a hydrolytic condensation reaction.
A polysiloxane compound is obtained by the above method.
Examples of the polysiloxane compound include the Ceranate (registered trademark) series (organic/inorganic hybrid type coating resin; manufactured by DIC Corporation) and the Compoceran SQ series (silsesquioxane type hybrid; manufactured by Arakawa Chemical Industries, Ltd.). .
　前記炭素源樹脂は、ポリシロキサン化合物との混和性が良く、また、不活性雰囲気中、高温焼成により炭化され、芳香族官能基を有する合成樹脂や天然化学原料が好ましい。 The carbon source resin is preferably a synthetic resin or a natural chemical raw material that has good miscibility with the polysiloxane compound, is carbonized by high-temperature baking in an inert atmosphere, and has an aromatic functional group.
　合成樹脂としては、ポリビニルアルコール、ポリアクリル酸などの熱可塑性樹脂、フェノール樹脂、フラン樹脂などの熱硬化性樹脂が挙げられる。天然化学原料としては、重質油、特にはタールピッチ類としては、コールタール、タール軽油、タール中油、タール重油、ナフタリン油、アントラセン油、コールタールピッチ、ピッチ油、メソフェーズピッチ、酸素架橋石油ピッチ、ヘビーオイルなどが挙げられるが、安価入手や不純物排除の観点からフェノール樹脂の使用がより好ましい。 Synthetic resins include thermoplastic resins such as polyvinyl alcohol and polyacrylic acid, and thermosetting resins such as phenol resin and furan resin. Natural chemical raw materials include heavy oils, especially tar pitches such as coal tar, light tar oil, medium tar oil, heavy tar oil, naphthalene oil, anthracene oil, coal tar pitch, pitch oil, mesophase pitch, and oxygen-crosslinked petroleum pitch. , heavy oil, etc., but the use of phenolic resin is more preferable from the viewpoint of inexpensive availability and removal of impurities.
　特に、炭素源樹脂が芳香族炭化水素部位を含む樹脂であることが好ましく、芳香族炭化水素部位を含む樹脂がフェノール樹脂、エポキシ樹脂、または熱硬化性樹脂が好ましく、フェノール樹脂はレゾール型が好ましい。
　フェノール樹脂としては、例えばスミライトレジンシリーズ（レゾール型フェノール樹脂，住友ベークライト株式会社製）が挙げられる。
　本複合材料の製造においては、前記物性１から３の少なくともいずれか１の物性を有する本ケイ素系材料が得られるという観点から、前記ポリシロキサン化合物を炭素源樹脂としてフェノール樹脂との組合せが好ましい。 In particular, the carbon source resin is preferably a resin containing an aromatic hydrocarbon moiety, the resin containing an aromatic hydrocarbon moiety is preferably a phenol resin, an epoxy resin, or a thermosetting resin, and the phenol resin is preferably a resol type. .
Examples of phenolic resins include the Sumilite Resin series (resol-type phenolic resin, manufactured by Sumitomo Bakelite Co., Ltd.).
In the production of the present composite material, from the viewpoint of obtaining the present silicon-based material having at least one of physical properties 1 to 3, it is preferable to combine the polysiloxane compound with a phenol resin as a carbon source resin.
　本シリコン粒子のスラリーを前記ポリシロキサン化合物と前記炭素源樹脂との混合物と混合し、脱溶媒して前駆体が得られる。
　ポリシロキサン化合物と炭素源樹脂を含む混合物は、ポリシロキサン化合物と炭素源樹脂とが均一に混合した状態であることが好ましい。前記混合は分散および混合の機能を有する装置を用いて行われる。分散および混合の機能を有する装置としては、例えば、攪拌機、超音波ミキサー、プリミックス分散機などが挙げられる。有機溶媒を溜去することを目的とする脱溶剤と乾燥の作業では、乾燥機、減圧乾燥機、噴霧乾燥機などを用いることができる。 The slurry of the present silicon particles is mixed with the mixture of the polysiloxane compound and the carbon source resin, and the solvent is removed to obtain a precursor.
The mixture containing the polysiloxane compound and the carbon source resin is preferably in a state in which the polysiloxane compound and the carbon source resin are uniformly mixed. Said mixing is carried out using a device having the function of dispersing and mixing. Apparatuses having dispersing and mixing functions include, for example, stirrers, ultrasonic mixers, premix dispersers, and the like. A dryer, a reduced-pressure dryer, a spray dryer, or the like can be used for solvent removal and drying for the purpose of distilling off the organic solvent.
　前駆体はポリシロキサン化合物の固形分を１５質量％から８５質量％、炭素源樹脂の固形分を１５質量％から８５質量％含有するのが好ましく、ポリシロキサン化合物の固形分を２０から７０質量％、炭素源樹脂の固形分を２０質量％から７０質量％含有するのがより好ましい。さらに本前駆体には、Ｓｉ粒子を１から９０質量％含んでもよい。 The precursor preferably contains 15% to 85% by mass of the solid content of the polysiloxane compound, 15% to 85% by mass of the solid content of the carbon source resin, and 20% to 70% by mass of the solid content of the polysiloxane compound. , the solid content of the carbon source resin is more preferably 20% by mass to 70% by mass. Furthermore, the precursor may contain 1 to 90% by mass of Si particles.
　前記で得られた前駆体を不活性雰囲気中、焼成して熱分解可能な有機成分を完全分解させて焼成物が得られる。焼成温度は、例えば、最高到達温度が９００℃から１２００℃の範囲の温度で焼成することで、熱分解可能な有機成分を完全分解することができる。またポリシロキサン化合物および炭素源樹脂が高温処理のエネルギーによってケイ素－酸素－炭素骨格とフリー炭素を有するシリコンオキシカーバイド相に転化される。 The precursor obtained above is fired in an inert atmosphere to completely decompose the thermally decomposable organic component to obtain a fired product. As for the firing temperature, for example, by firing at a temperature in which the maximum reaching temperature is in the range of 900° C. to 1200° C., the thermally decomposable organic component can be completely decomposed. Also, the polysiloxane compound and the carbon source resin are converted into a silicon oxycarbide phase having a silicon-oxygen-carbon skeleton and free carbon by the energy of the high temperature treatment.
　焼成は昇温速度、一定温度での保持時間等により規定される焼成のプログラムに沿って行われる。なお最高到達温度は、設定する最高温度であり、焼成物の構造や性能に強く影響を与えるものである。最高到達温度により、シリコンオキシカーバイド相のケイ素と炭素の化学結合状態を保有する本活物質の微細構造が精密に制御でき、より優れた充放電特性が得られる。 Firing is carried out according to a firing program that is defined by the rate of temperature increase, the holding time at a certain temperature, etc. The maximum attainable temperature is the maximum temperature to be set, and strongly affects the structure and performance of the fired product. Depending on the maximum temperature reached, the fine structure of the present active material, which possesses the chemical bonding state of silicon and carbon in the silicon oxycarbide phase, can be precisely controlled, and better charge-discharge characteristics can be obtained.
　焼成方法は、特に限定されないが、不活性雰囲気中にて加熱機能を有する反応装置を用いればよく、連続法、回分法での処理が可能である。焼成用装置については、流動層反応炉、回転炉、竪型移動層反応炉、トンネル炉、バッチ炉、ロータリーキルン等をその目的に応じ適宜選択することができる。 The calcination method is not particularly limited, but a reaction apparatus having a heating function may be used in an inert atmosphere, and continuous and batch processes are possible. A fluidized bed reactor, a rotary furnace, a vertical moving bed reactor, a tunnel furnace, a batch furnace, a rotary kiln, or the like can be appropriately selected as the firing apparatus according to the purpose.
　得られた焼成物を粉砕し、必要に応じて分級することで本複合材料が得られる。粉砕は目的とする粒径まで一段で行っても良いし、数段に分けて行っても良い。例えば１０ｍｍ以上の塊または凝集粒子の焼成物を、１０μｍ程度の活物質を作製する場合はジョークラッシャー、ロールクラッシャー等で粗粉砕を行い１ｍｍ程度の粒子にした後、グローミル、ボールミル等で１００μｍ程度とし、ビーズミル、ジェットミル等で１０μｍ程度まで粉砕する。粉砕で作製した粒子には粗大粒子が含まれる場合がありそれを取り除くため、また、微粉を取り除いて粒度分布を調整する場合は分級を行う。使用する分級機は風力分級機、湿式分級機等目的に応じて使い分けるが、粗大粒子を取り除く場合、篩を通す分級方式が確実に目的を達成できるために好ましい。尚、焼成前に前駆体混合物を噴霧乾燥等により目標粒子径付近の形状に制御し、その形状で焼成を行った場合は、粉砕工程を省くことも可能である。 This composite material can be obtained by pulverizing the obtained fired product and classifying it as necessary. The pulverization may be carried out in one step until the target particle size is obtained, or may be carried out in several steps. For example, when producing an active material of about 10 μm from a sintered mass or agglomerated particles of 10 mm or more, it is roughly pulverized with a jaw crusher, a roll crusher, etc. to particles of about 1 mm, and then pulverized to about 100 μm with a glow mill, ball mill, etc. , a bead mill, a jet mill, or the like to a size of about 10 μm. Particles produced by pulverization may contain coarse particles, and in order to remove them, or to adjust the particle size distribution by removing fine powder, classification is performed. The classifier to be used may be a wind classifier, a wet classifier, or the like depending on the purpose, but when removing coarse particles, the classification method through a sieve is preferable because the purpose can be reliably achieved. In addition, when the precursor mixture is controlled to have a shape near the target particle size by spray drying or the like before firing, and the firing is performed in that shape, the pulverization step can be omitted.
　本複合材料を含む二次電池用負極活物質は容量維持率に優れており、本複合材料を含む二次電池用負極活物質を負極として用いた二次電池は良好な特性を発揮する。
　具体的には、本複合材料と有機結着剤と、必要に応じてその他の導電助剤などの成分を含む二次電池用負極活物質のスラリーを集電体銅箔上へ薄膜状に塗付して負極とすることができる。また、前記のスラリーに黒鉛など炭素材料を加えて負極を作製することもできる。
　炭素材料としては、天然黒鉛、人工黒鉛、ハードカーボンまたはソフトカーボンのような非晶質炭素などが挙げられる。 A secondary battery negative electrode active material containing the present composite material has an excellent capacity retention rate, and a secondary battery using the secondary battery negative electrode active material containing the present composite material as a negative electrode exhibits good characteristics.
Specifically, a slurry of a negative electrode active material for secondary batteries containing the present composite material, an organic binder, and other components such as a conductive agent as necessary is applied in a thin film form onto a current collector copper foil. can be attached to form a negative electrode. A negative electrode can also be produced by adding a carbon material such as graphite to the slurry.
Carbon materials include natural graphite, artificial graphite, amorphous carbon such as hard carbon or soft carbon, and the like.
　例えば、本複合材料と、有機結着材であるバインダーとを、溶媒とともに撹拌機、ボールミル、スーパーサンドミル、加圧ニーダ等の分散装置により混練して、二次電池用負極活物質のスラリーを調製し、これを集電体に塗布して負極層を形成することで負極を得ることができる。また、ペースト状の二次電池用負極活物質のスラリーをシート状、ペレット状等の形状に成形し、これを集電体と一体化することでも得ることができる。 For example, the present composite material and a binder that is an organic binder are kneaded together with a solvent using a dispersing device such as a stirrer, ball mill, super sand mill, pressure kneader, etc. to prepare a slurry of a negative electrode active material for a secondary battery. Then, a negative electrode can be obtained by applying this to a current collector to form a negative electrode layer. It can also be obtained by forming a slurry of a pasty negative electrode active material for a secondary battery into a shape such as a sheet or pellet and integrating this with a current collector.
　前記有機結着剤としては、例えば、スチレン－ブタジエンゴム共重合体（以下、「ＳＢＲ」とも記す。）；メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、（メタ）アクリロニトリル、およびヒドロキシエチル（メタ）アクリレート等のエチレン性不飽和カルボン酸エステル、および、アクリル酸、メタクリル酸、イタコン酸、フマル酸、マレイン酸等のエチレン性不飽和カルボン酸からなる（メタ）アクリル共重合体等の不飽和カルボン酸共重合体；ポリ弗化ビニリデン、ポリエチレンオキサイド、ポリエピクロヒドリン、ポリホスファゼン、ポリアクリロニトリル、ポリイミド、ポリアミドイミド、カルボキシメチルセルロース（以下、「ＣＭＣ」とも記す。）などの高分子化合物が挙げられる。 Examples of the organic binder include styrene-butadiene rubber copolymer (hereinafter also referred to as "SBR"); methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile , and ethylenically unsaturated carboxylic acid esters such as hydroxyethyl (meth)acrylate, and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid (meth)acrylic copolymerization Unsaturated carboxylic acid copolymers such as coalescence; A high molecular compound is mentioned.
　これらの有機結着剤は、それぞれの物性によって、水に分散、あるいは溶解したもの、また、Ｎ－メチル－２－ピロリドン（ＮＭＰ）などの有機溶剤に溶解したものがある。リチウムイオン二次電池負極の負極層中の有機結着剤の含有比率は、１質量％から３０質量％であることが好ましく、２質量％から２０質量％であることがより好ましく、３質量％から１５質量％であることがさらに好ましい。 Depending on their physical properties, these organic binders can be dispersed or dissolved in water, or dissolved in an organic solvent such as N-methyl-2-pyrrolidone (NMP). The content ratio of the organic binder in the negative electrode layer of the lithium ion secondary battery negative electrode is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass, and 3% by mass. to 15% by mass is more preferable.
　有機結着剤の含有比率が１質量％以上であることで密着性がより良好で、充放電時の膨張および収縮によって負極構造の破壊がより抑制される。一方、３０質量％以下であることで、電極抵抗の上昇がより抑えられる。
　かかる範囲において、得られる二次電池用負極活物質は、化学安定性が高く、水性バインダーも採用することができる点で、実用化面においても取り扱い容易である。 When the content ratio of the organic binder is 1% by mass or more, the adhesion is better, and the destruction of the negative electrode structure due to expansion and contraction during charging and discharging is further suppressed. On the other hand, when the content is 30% by mass or less, an increase in electrode resistance can be further suppressed.
Within this range, the resulting negative electrode active material for secondary batteries has high chemical stability, and can be used with an aqueous binder, which makes it easy to handle in terms of practical use.
　また、前記二次電池用負極活物質のスラリーには、必要に応じて、導電助材を混合してもよい。導電助材としては、例えば、カーボンブラック、グラファイト、アセチレンブラック、あるいは導電性を示す酸化物や窒化物等が挙げられる。導電助剤の使用量は、本発明の負極活物質に対して１質量％から１５質量％程度とすればよい。 In addition, the slurry of the negative electrode active material for secondary batteries may be mixed with a conductive additive, if necessary. Examples of conductive aids include carbon black, graphite, acetylene black, oxides and nitrides exhibiting conductivity, and the like. The amount of the conductive aid used may be about 1% by mass to 15% by mass with respect to the negative electrode active material of the present invention.
　また前記集電体の材質および形状については、例えば、銅、ニッケル、チタン、ステンレス鋼等を、箔状、穴開け箔状、メッシュ状等にした帯状のものを用いればよい。また、多孔性材料、たとえばポーラスメタル（発泡メタル）やカーボンペーパーなども使用できる。 Regarding the material and shape of the current collector, for example, copper, nickel, titanium, stainless steel, etc. may be used in the form of a foil, a perforated foil, a mesh, or the like in a strip shape. Porous materials such as porous metal (foamed metal) and carbon paper can also be used.
　前記二次電池用負極活物質のスラリーを集電体に塗布する方法としては、例えば、メタルマスク印刷法、静電塗装法、ディップコート法、スプレーコート法、ロールコート法、ドクターブレード法、グラビアコート法、スクリーン印刷法などが挙げられる。塗布後は、必要に応じて平板プレス、カレンダーロール等による圧延処理を行うことが好ましい。 Examples of the method for applying the slurry of the negative electrode active material for a secondary battery to the current collector include a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, and a gravure method. Examples include a coating method and a screen printing method. After coating, it is preferable to carry out a rolling treatment using a flat plate press, calendar rolls, or the like, if necessary.
　また、前記二次電池用負極活物質のスラリーをシート状またはペレット状等として、これと集電体との一体化は、例えば、ロール、プレス、もしくはこれらの組み合わせ等により行うことができる。 Further, the slurry of the negative electrode active material for a secondary battery can be formed into a sheet or pellet form, and the sheet and the current collector can be integrated by, for example, rolling, pressing, or a combination thereof.
　前記集電体上に形成された負極層または集電体と一体化した負極層は、用いた有機結着剤に応じて熱処理することが好ましい。例えば、水系のスチレン－ブタジエンゴム共重合体（ＳＢＲ）などを用いた場合には１００から１３０℃で熱処理すればよく、ポリイミド、ポリアミドイミドを主骨格とした有機結着剤を用いた場合には１５０から４５０℃で熱処理することが好ましい。 The negative electrode layer formed on the current collector or the negative electrode layer integrated with the current collector is preferably heat-treated according to the organic binder used. For example, when a water-based styrene-butadiene rubber copolymer (SBR) or the like is used, heat treatment at 100 to 130° C. is sufficient, and when an organic binder having a main skeleton of polyimide or polyamideimide is used, Heat treatment at 150 to 450° C. is preferred.
　この熱処理により溶媒の除去、バインダーの硬化による高強度化が進み、粒子間および粒子と集電体間の密着性が向上できる。尚、これらの熱処理は、処理中の集電体の酸化を防ぐため、ヘリウム、アルゴン、窒素等の不活性雰囲気、真空雰囲気で行うことが好ましい。 This heat treatment removes the solvent and hardens the binder to increase the strength, improving the adhesion between particles and between the particles and the current collector. These heat treatments are preferably performed in an inert atmosphere such as helium, argon, or nitrogen, or in a vacuum atmosphere in order to prevent oxidation of the current collector during the treatment.
　また、熱処理した後に、負極は加圧処理しておくことが好ましい。本複合材料を用いた負極では、電極密度が１ｇ／ｃｍ３から１．８ｇ／ｃｍ３であることが好ましく、１．１ｇ／ｃｍ３から１．７ｇ／ｃｍ３であることがより好ましく、１．２ｇ／ｃｍ３から１．６ｇ／ｃｍ３であることがさらに好ましい。電極密度については、高いほど密着性および電極の体積容量密度が向上する傾向がある。一方、電極密度が高すぎると、電極中の空隙が減少することでケイ素など体積膨張の抑制効果が弱くなり、容量維持率が低下することがある。そのため電極密度の最適な範囲が選択される。 Moreover, it is preferable that the negative electrode is subjected to a pressure treatment after the heat treatment. The negative electrode using the present composite material preferably has an electrode density of 1 g/cm 3 to 1.8 g/cm 3 , more preferably 1.1 g/cm 3 to 1.7 g/cm 3 . More preferably from 0.2 g/cm 3 to 1.6 g/cm 3 . Regarding the electrode density, there is a tendency that the higher the electrode density, the higher the adhesion and the volume capacity density of the electrode. On the other hand, if the electrode density is too high, the voids in the electrode are reduced, which weakens the effect of suppressing the volume expansion of silicon or the like, and the capacity retention rate may decrease. Therefore, an optimum range of electrode densities is selected.
　本発明の二次電池は前記二次電池用負極活物質を負極に含む。前記二次電池用負極活物質を含む負極を有する二次電池としては、非水電解質二次電池と固体型電解質二次電池が好ましく、特に非水電解質二次電池の負極として用いた際に優れた性能を発揮するものである。 The secondary battery of the present invention includes the negative electrode active material for secondary batteries in the negative electrode. As a secondary battery having a negative electrode containing the negative electrode active material for a secondary battery, a non-aqueous electrolyte secondary battery and a solid electrolyte secondary battery are preferable. performance.
　前記本発明の二次電池は、例えば、湿式電解質二次電池に用いる場合、正極と、本発明の二次電池用負極活物質を含む負極とを、セパレータを介して対向して配置し、電解液を注入することにより構成することができる。 For example, when the secondary battery of the present invention is used in a wet electrolyte secondary battery, a positive electrode and a negative electrode containing the negative electrode active material for a secondary battery of the present invention are arranged to face each other with a separator interposed therebetween. It can be configured by injecting a liquid.
　正極は、負極と同様にして、集電体表面上に正極層を形成することで得ることができる。この場合の集電体はアルミニウム、チタン、ステンレス鋼等の金属や合金を、箔状、穴開け箔状、メッシュ状等にした帯状のものを用いることができる。 The positive electrode can be obtained by forming a positive electrode layer on the surface of the current collector in the same manner as the negative electrode. In this case, the current collector may be a strip-shaped one made of a metal or alloy such as aluminum, titanium, or stainless steel in the form of foil, foil with holes, mesh, or the like.
　正極層に用いる正極材料としては、特に制限されない。非水電解質二次電池の中でも、リチウムイオン二次電池を作製する場合には、例えば、リチウムイオンをドーピングまたはインターカレーション可能な金属化合物、金属酸化物、金属硫化物、または導電性高分子材料を用いればよい。例えば、コバルト酸リチウム（ＬｉＣｏＯ２）、ニッケル酸リチウム（ＬｉＮｉＯ２）、マンガン酸リチウム（ＬｉＭｎＯ２）、およびこれらの複合酸化物（ＬｉＣｏｘＮｉｙＭｎｚＯ２、ｘ＋ｙ＋ｚ＝１）、リチウムマンガンスピネル（ＬｉＭｎ２Ｏ４）、リチウムバナジウム化合物、Ｖ２Ｏ５、Ｖ６Ｏ１３、ＶＯ２、ＭｎＯ２、ＴｉＯ２、ＭｏＶ２Ｏ８、ＴｉＳ２、Ｖ２Ｓ５、ＶＳ２、ＭｏＳ２、ＭｏＳ３、Ｃｒ３Ｏ８、Ｃｒ２Ｏ５、オリビン型ＬｉＭＰＯ４（ただし、ＭはＣｏ、Ｎｉ、ＭｎまたはＦｅ）、ポリアセチレン、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセン等の導電性ポリマー、多孔質炭素等などを単独或いは混合して使用することができる。 The positive electrode material used for the positive electrode layer is not particularly limited. Among non-aqueous electrolyte secondary batteries, when producing a lithium ion secondary battery, for example, a metal compound, a metal oxide, a metal sulfide, or a conductive polymer material capable of doping or intercalating lithium ions should be used. For example, lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), lithium manganate (LiMnO 2 ), composite oxides thereof (LiCoxNiyMnzO 2 , x+y+z=1), lithium manganese spinel (LiMn 2 O 4 ) , lithium vanadium compounds , V2O5 , V6O13 , VO2 , MnO2 , TiO2 , MoV2O8 , TiS2 , V2S5 , VS2 , MoS2 , MoS3 , Cr3O8 , Cr 2 O 5 , olivine-type LiMPO 4 (where M is Co, Ni, Mn or Fe), conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene and polyacene, porous carbon, etc. can be used.
　セパレータとしては、例えば、ポリエチレン、ポリプロピレン等のポリオレフィンを主成分とした不織布、クロス、微孔フィルムまたはそれらを組み合わせたものを使用することができる。なお、作製する非水電解質二次電池の正極と負極が直接接触しない構造にした場合は、セパレータを使用する必要はない。 As the separator, for example, a non-woven fabric, cloth, microporous film, or a combination of them can be used, the main component of which is polyolefin such as polyethylene or polypropylene. In addition, when the positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery to be manufactured are structured such that they do not come into direct contact with each other, there is no need to use a separator.
　電解液としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＳＯ３ＣＦ３等のリチウム塩を、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネート、フルオロエチレンカーボネート、シクロペンタノン、スルホラン、３－メチルスルホラン、２，４－ジメチルスルホラン、３－メチル－１，３－オキサゾリジン－２－オン、γ－ブチロラクトン、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、メチルプロピルカーボネート、ブチルメチルカーボネート、エチルプロピルカーボネート、ブチルエチルカーボネート、ジプロピルカーボネート、１，２－ジメトキシエタン、テトラヒドロフラン、２－メチルテトラヒドロフラン、１，３－ジオキソラン、酢酸メチル、酢酸エチル等の単体もしくは２成分以上の混合物の非水系溶剤に溶解した、いわゆる有機電解液を使用することができる。 Examples of electrolytes include lithium salts such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 and LiSO 3 CF 3 , ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, cyclopentanone, sulfolane. , 3-methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl Non-aqueous solvents such as propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate and ethyl acetate, or a mixture of two or more components. A dissolved, so-called organic electrolyte can be used.
　本発明の二次電池の構造は、特に限定されないが、通常、正極および負極と、必要に応じて設けられるセパレータとを、扁平渦巻状に巻回して巻回式極板群としたり、これらを平板状として積層して積層式極板群としたりし、これら極板群を外装体中に封入した構造とするのが一般的である。尚、本発明の実施例で用いるハーフセルは、負極に本複合材料を主体とする構成とし、対極に金属リチウムを用いた簡易評価を行っているが、これはより活物質自体のサイクル特性を明確に比較するためである。 The structure of the secondary battery of the present invention is not particularly limited, but usually, a positive electrode, a negative electrode, and an optional separator are wound into a flat spiral to form a wound electrode plate group. It is common to have a structure in which flat plates are laminated to form a laminated electrode plate group, and these electrode plate groups are enclosed in an outer package. The half-cell used in the examples of the present invention has a structure mainly composed of this composite material for the negative electrode, and a simple evaluation is performed using metallic lithium for the counter electrode. for comparison.
　本複合材料を用いた二次電池は、特に限定されないが、ペーパー型電池、ボタン型電池、コイン型電池、積層型電池、円筒型電池、角型電池などとして使用される。上述した本発明の負極活物質は、リチウムイオンを挿入脱離することを充放電機構とする電気化学装置全般、例えば、ハイブリッドキャパシタ、固体リチウム二次電池などにも適用することが可能である。 Secondary batteries using this composite material are not particularly limited, but are used as paper-type batteries, button-type batteries, coin-type batteries, laminated-type batteries, cylindrical batteries, square-type batteries, and the like. The negative electrode active material of the present invention described above can also be applied to general electrochemical devices having a charging/discharging mechanism of intercalating and deintercalating lithium ions, such as hybrid capacitors and solid lithium secondary batteries.
　前記のとおり、本複合材料を二次電池用負極活物質とした時、容量維持率が改良された二次電池を与える。
　本複合材料は前記方法により負極として用い、前記負極を有する二次電池とすることができる。 As described above, when the present composite material is used as a negative electrode active material for a secondary battery, it provides a secondary battery with an improved capacity retention rate.
This composite material can be used as a negative electrode by the method described above to form a secondary battery having the negative electrode.
　以上、本ケイ素系材料、本複合材料、本複合材料含む二次電池用活物質、前記二次電池用活物質を含む負極および前記負極を含む二次電池に関して説明したが、本発明は前記の実施形態の構成に限定されない。
　本ケイ素系材料、本複合材料、本複合材料含む二次電池用活物質、前記二次電池用活物質を含む負極および前記負極を含む二次電池は前記実施形態の構成において、他の任意の構成を追加してもよいし、同様の機能を発揮する任意の構成と置換されていてもよい。 The silicon-based material, the composite material, the secondary battery active material containing the composite material, the negative electrode containing the secondary battery active material, and the secondary battery containing the negative electrode have been described above. It is not limited to the configuration of the embodiment.
The silicon-based material, the composite material, the active material for a secondary battery containing the composite material, the negative electrode containing the active material for a secondary battery, and the secondary battery containing the negative electrode have the configurations of the above embodiments, and any other Features may be added or replaced with any features that serve a similar function.
　以下、実施例によって本発明を詳細に説明するが、本発明はこれらに限定されない。
　尚、本発明の実施例で用いるハーフセルは、負極に本発明のケイ素含有活物質を主体とする構成とし、対極に金属リチウムを用いた簡易評価を行っているが、これはより活物質自体のサイクル特性を明確に比較するためである。 EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
The half-cell used in the examples of the present invention has a negative electrode composed mainly of the silicon-containing active material of the present invention, and a simple evaluation using metallic lithium as the counter electrode. This is to clearly compare the cycle characteristics.
　合成例１：ポリシロキサン化合物１の作製
　攪拌機、温度計、滴下ロート、冷却管および窒素ガス導入口を備えた反応容器に、１５０質量部のｎ－ブタノール（以下、「ｎ－ＢｕＯＨ」とも記す。）、２４９質量部のフェニルトリメトキシシラン（以下、「ＰＴＭＳ」とも記す。）、２６３質量部のジメチルジメトキシシラン（以下、「ＤＭＤＭＳ」とも記す。）を仕込んで、８０℃まで昇温した。次いで、同温度で１８質量部のメチルメタアクリレート（以下、「ＭＭＡ」とも記す。）、１４質量部のブチルメタアクリレート（以下、「ＢＭＡ」とも記す。）、７質量部の酪酸（以下、「ＢＡ」とも記す。）、１質量部のアクリル酸（以下、「ＡＡ」とも記す。）、２質量部のメタクリロイルオキシプロピルトリメトキシシラン（以下、「ＭＰＴＳ」とも記す。）、６質量部のｎ－ＢｕＯＨおよび０．９質量部のブチルペルオキシ－２－エチルヘキサノエート（以下、「ＴＢＰＥＨ」とも記す。）を含有する混合物を、前記反応容器中へ５時間で滴下した。滴下終了後、更に同温度で１０時間反応させて加水分解性シリル基を有する数平均分子量が２０，１００のビニル重合体（ａ２－２）の有機溶剤溶液を得た。 Synthesis Example 1: Preparation of Polysiloxane Compound 1 150 parts by mass of n-butanol (hereinafter also referred to as "n-BuOH") was added to a reaction vessel equipped with a stirrer, thermometer, dropping funnel, cooling tube and nitrogen gas inlet. ), 249 parts by mass of phenyltrimethoxysilane (hereinafter also referred to as “PTMS”), and 263 parts by mass of dimethyldimethoxysilane (hereinafter also referred to as “DMDMS”) were charged and heated to 80°C. Then, at the same temperature, 18 parts by mass of methyl methacrylate (hereinafter also referred to as "MMA"), 14 parts by mass of butyl methacrylate (hereinafter also referred to as "BMA"), 7 parts by mass of butyric acid (hereinafter referred to as " BA”), 1 part by mass of acrylic acid (hereinafter also referred to as “AA”), 2 parts by mass of methacryloyloxypropyltrimethoxysilane (hereinafter also referred to as “MPTS”), 6 parts by mass of n A mixture containing -BuOH and 0.9 parts by mass of butylperoxy-2-ethylhexanoate (hereinafter also referred to as "TBPEH") was added dropwise into the reaction vessel over 5 hours. After completion of the dropwise addition, reaction was continued at the same temperature for 10 hours to obtain an organic solvent solution of a vinyl polymer (a2-2) having a hydrolyzable silyl group and a number average molecular weight of 20,100.
　次いで、０．０５質量部のｉｓｏ－プロピルアシッドホスフェート（ＳＣ有機化学株式会社製「Ｐｈｏｓｌｅｘ　Ａ－３」）と１４７質量部の脱イオン水との混合物を、５分間で滴下し、更に同温度で１０時間撹拌して加水分解縮合反応させることで、ビニル重合体（ａ２－２）の有する加水分解性シリル基と、前記ＰＴＭＳおよびＤＭＤＭＳ由来のポリシロキサンの有する加水分解性シリル基およびシラノール基とが結合した複合樹脂を含有する液を得た。次いで、この液に７６質量部の３－グリシドキシプロピルトリメトキシシラン、２３１質量部の合成例１で得られたＭＴＭＳの縮合物（ａ１）、５６質量部の脱イオン水を添加し、同温度で１５時間撹拌して加水分解縮合反応させたものを、合成例１と同様の条件で蒸留することによって生成したメタノールおよび水を除去した。次いで、２５０質量部のｎ－ＢｕＯＨを添加し、ケイ素系材料として不揮発分が６０．０質量％の硬化性樹脂組成物（２）を１，０００質量部得た。 Next, a mixture of 0.05 parts by mass of iso-propyl acid phosphate (“Phoslex A-3” manufactured by SC Organic Chemical Co., Ltd.) and 147 parts by mass of deionized water was added dropwise over 5 minutes, and further at the same temperature. A hydrolytic condensation reaction is carried out with stirring for 10 hours to convert the hydrolyzable silyl groups of the vinyl polymer (a2-2) and the hydrolyzable silyl groups and silanol groups of the PTMS- and DMDMS-derived polysiloxanes. A liquid containing bound composite resin was obtained. Next, 76 parts by mass of 3-glycidoxypropyltrimethoxysilane, 231 parts by mass of the condensate (a1) of MTMS obtained in Synthesis Example 1, and 56 parts by mass of deionized water were added to the liquid. The resulting hydrolytic condensation reaction was stirred at the temperature for 15 hours and distilled under the same conditions as in Synthesis Example 1 to remove the generated methanol and water. Next, 250 parts by mass of n-BuOH was added to obtain 1,000 parts by mass of a curable resin composition (2) having a non-volatile content of 60.0% by mass as a silicon-based material.
　合成例２：ポリシロキサン化合物２の作製
　攪拌機、温度計、滴下ロート、冷却管及び窒素ガス導入口を備えた反応容器に、５５質量部のイソプロパノール（以下、「ＩＰＡ」とも記す。）、９５２質量部のメチルトリメトキシシラン（以下、「ＭＴＭＳ」とも記す。）と１８０質量部のＰＴＭＳ、１５２質量部のＤＭＤＭＳを仕込んで、６０℃まで昇温した。次いで、前記反応容器中にｉｓｏ－プロピルアシッドホスフェート（ＳＣ有機化学株式会社製「Ｐｈｏｓｌｅｘ　Ａ－３」）０．１７質量部と脱イオン水１５０質量部との混合物を５分間で滴下した後、８０℃の温度で４時間撹拌して加水分解縮合反応させた。
　上記の加水分解縮合反応によって得られた縮合物を、温度４０から６０℃および４０から１．３ｋＰａの減圧下で蒸留し前記反応過程で生成したメタノール及び水を除去することによって、ケイ素系材料として数平均分子量１，２００の縮合物を含有する、有効成分が７０質量％の液を１，０００質量部得た。
　なお、「４０から１．３ｋＰａの減圧下」とは、メタノールの留去開始時の減圧条件が４０ｋＰａであり、最終的に１．３ｋＰａとなるまで減圧することを意味する。以下の記載においても同様である。
　また、前記有効成分とは、ＭＴＭＳ等のシランモノマーのメトキシ基が全て縮合反応した場合の理論収量（質量部）を、縮合反応後の実収量（質量部）で除した値、〔シランモノマーのメトキシ基が全て縮合反応した場合の理論収量（質量部）／縮合反応後の実収量（質量部）〕、により算出したものである。 Synthesis Example 2: Preparation of polysiloxane compound 2 Into a reaction vessel equipped with a stirrer, thermometer, dropping funnel, cooling tube and nitrogen gas inlet, 55 parts by mass of isopropanol (hereinafter also referred to as "IPA"), 952 parts by mass of Parts of methyltrimethoxysilane (hereinafter also referred to as “MTMS”), 180 parts by mass of PTMS, and 152 parts by mass of DMDMS were charged, and the temperature was raised to 60°C. Next, a mixture of 0.17 parts by mass of iso-propyl acid phosphate ("Phoslex A-3" manufactured by SC Organic Chemical Co., Ltd.) and 150 parts by mass of deionized water was added dropwise to the reaction vessel over 5 minutes. C. for 4 hours to carry out a hydrolytic condensation reaction.
The condensate obtained by the above hydrolytic condensation reaction is distilled at a temperature of 40 to 60 ° C. and a reduced pressure of 40 to 1.3 kPa to remove the methanol and water produced in the reaction process, thereby obtaining a silicon-based material. 1,000 parts by mass of a liquid containing a condensate with a number average molecular weight of 1,200 and an active ingredient content of 70% by mass was obtained.
Note that "under a reduced pressure of 40 to 1.3 kPa" means that the reduced pressure condition is 40 kPa at the start of distillation of methanol, and the pressure is finally reduced to 1.3 kPa. The same applies to the following description.
In addition, the effective ingredient is a value obtained by dividing the theoretical yield (parts by mass) when all the methoxy groups of the silane monomer such as MTMS are condensed by the actual yield (parts by mass) after the condensation reaction. Theoretical yield when all methoxy groups are condensed (parts by mass)/Actual yield after condensation reaction (parts by mass)].
　合成例３：シリコン粒子の作製
　１５０ｍｌの小型ビーズミル装置の容器中に６０％の充填率で粒径が０．１ｍｍから０．２ｍｍのジルコニアビーズおよび１００ｍｌのメチルエチルケトン（以下、「ＭＥＫ」とも記す。）溶媒を入れた。その後、平均粒径が５μｍのシリコン粉体（市販品）とカチオン性分散剤液（ビックケミー・ジャパン株式会社：ＢＹＫ１４５）を入れ、表１に記載の条件下にてビーズミル湿式粉砕を行い、固形物濃度が３０質量％の濃い褐色液体状のシリコンスラリーを得た。ＴＥＭ観察で得られたシリコン粒子の形態およびサイズを確認し、表１に示したように、それぞれをＳｉ１、Ｓｉ２およびＳｉ３とした。 Synthesis Example 3 Preparation of Silicon Particles Zirconia beads with a particle size of 0.1 mm to 0.2 mm and 100 ml of methyl ethyl ketone (hereinafter also referred to as "MEK") were prepared at a filling rate of 60% in a container of a 150 ml small bead mill device. Added solvent. After that, silicon powder (commercially available) with an average particle size of 5 μm and a cationic dispersant liquid (BYK-Chemie Japan Co., Ltd.: BYK145) are added, and wet milling is performed under the conditions shown in Table 1 to obtain a solid. A dark brown liquid silicon slurry having a concentration of 30% by mass was obtained. The morphology and size of the silicon particles obtained by TEM observation were confirmed, and as shown in Table 1, Si1, Si2 and Si3, respectively.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　実施例１
　上記合成例１で作製したポリシロキサン化合物１とフェノール樹脂（スミライトレジン：ＰＲ－５３５７０、住友ベークライト社製）を樹脂固形物重量比で１：９の割合で撹拌機中にて十分に混合させ脱溶媒を行た。その後、プレート型に成形し、減圧乾燥を行い、プレート型成形乾燥物を得た。成形物を窒素雰囲気中、１０５０℃で６時間、高温焼成して、黒色固形物を得た。 Example 1
The polysiloxane compound 1 prepared in Synthesis Example 1 and a phenol resin (Sumilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.) were sufficiently mixed in a stirrer at a resin solid weight ratio of 1:9. Desolvation was performed. After that, it was molded into a plate mold and dried under reduced pressure to obtain a plate-shaped dried product. The molding was high temperature fired at 1050° C. for 6 hours in a nitrogen atmosphere to obtain a black solid.
　前記のように作製した黒色固形物をナノインテンダー測定装置（ＥＮＴ－２１００：エリオ二クス（株）社製）を用いて、力学的物性の測定を行った。測定はＩＳＯ１４５７７に準拠した方式で実施した。試料形状は、測定圧子に対して垂直であり、局所的に平面である構造体で、凹凸面を少なくする為、試料は厚さを３ｍｍ以下とし、場合に応じて表面を粒度２０００、５０００およびバフ研磨を行ったものを用いた。測定条件は、開始荷重０ｍＮ、終了荷重１００ｍＮ、分割数５００、ステップ間隔２０ｍｓの負荷、除荷試験を任意の箇所で２０点測定し、平均値を算出した。押し込み硬度は１．２ＧＰａであった。 The mechanical properties of the black solid produced as described above were measured using a nanointender measuring device (ENT-2100: manufactured by Elionix Co., Ltd.). The measurement was carried out in accordance with ISO14577. The shape of the sample is a structure that is perpendicular to the measuring indenter and is locally flat. A buffed one was used. Measurement conditions were as follows: starting load 0 mN, ending load 100 mN, number of divisions 500, step interval 20 ms loading, unloading test was measured at 20 arbitrary points, and the average value was calculated. The indentation hardness was 1.2 GPa.
　ポリシロキサン化合物１とフェノール樹脂（スミライトレジン：ＰＲ－５３５７０、住友ベークライト社製）を混合し、合成例３で作製し平均粒径が５０ｎｍのＳｉ１を５０重量％となるように調整した液体状シリコンスラリーを添加し、撹拌機中にて十分に混合させた。その後、脱溶媒、減圧乾燥を行い、前駆体を得た。窒素雰囲気中、１０５０℃で６時間、高温焼成して、遊星型ボールミル装置（ボールミルＰ－６クラシックライン：ＦＲＩＴＳＣＨ社製）で粉砕後に黒色粉体を得た。得られた黒色粉体を活物質粉末として充放電測定に用いた。活物質粉末の平均粒径が約７．０μｍ±１．０μｍであり、比表面積は１５ｍ２／ｇを示した。
　ハーフセルの評価は、８質量部の負極活物質と導電助剤として１質量部のアセチレンブラックと１質量部の有機結着材を混合して、自転公転式の泡取り錬太郎で１０分間攪拌することでスラリーを調整した。なお有機結着材は０．７５質量部のＳＢＲ（市販品）と０．２５質量部のＣＭＣとの混合物である。アプリケーターを用いて厚み２０μｍの銅箔へ得られたスラリーを塗膜後、１１０℃、減圧条件下で乾燥し、厚みが約４０μｍの電極薄膜を得た。 Polysiloxane compound 1 and phenolic resin (Sumilite Resin: PR-53570, manufactured by Sumitomo Bakelite Co., Ltd.) are mixed, and Si1 having an average particle size of 50 nm prepared in Synthesis Example 3 is adjusted to 50% by weight. Silicon slurry was added and mixed well in a stirrer. After that, the solvent was removed and dried under reduced pressure to obtain a precursor. It was sintered at a high temperature of 1050° C. for 6 hours in a nitrogen atmosphere, and pulverized with a planetary ball mill (ball mill P-6 classic line: manufactured by FRITSCH) to obtain a black powder. The resulting black powder was used as an active material powder for charge/discharge measurements. The active material powder had an average particle size of about 7.0 μm±1.0 μm and a specific surface area of 15 m 2 /g.
Half-cell evaluation is carried out by mixing 8 parts by mass of the negative electrode active material, 1 part by mass of acetylene black as a conductive aid, and 1 part by mass of an organic binder, and stirring for 10 minutes with a rotation-revolution type Awatori Rentaro. The slurry was adjusted by The organic binder is a mixture of 0.75 parts by mass of SBR (commercial product) and 0.25 parts by mass of CMC. After coating the obtained slurry on a copper foil having a thickness of 20 μm using an applicator, it was dried at 110° C. under reduced pressure conditions to obtain an electrode thin film having a thickness of about 40 μm.
　得られた電極薄膜を直径１４ｍｍの円状電極に打ち抜き、露点－４０℃以下である水分含有量の極低であるドライルームにおいてＬｉ箔を対極にし、２５μｍのポリプロピレン製セパレータを介して本発明の電極を対向させた。炭酸ジエチルと炭酸エチレンを容量比で１：１に１ｍｏｌ／ＬのＬｉＰＦ６を含有する電解液（キシダ化学製）を吸着させ評価用ハーフ電池（ＣＲ２０３２型）を作製した。二次電池充放電試験装置（北斗電工製）を用いて電池特性を測定し、室温２５℃、カットオフ電圧範囲が０．００５－１．４Ｖに、１から３サイクル目までは充電レートを０．１Ｃ、４サイクル目以後は０．２Ｃとし、定電流・定電圧式の充放電および定電流式充放電の設定条件下で充放電特性の評価試験を行った。各充放電時の切り替えには、３０分間、開回路で放置した。 The obtained electrode thin film was punched into a circular electrode with a diameter of 14 mm, and in a dry room with a dew point of −40° C. or less and a very low moisture content, Li foil was used as the counter electrode, and the electrode of the present invention was passed through a 25 μm polypropylene separator. The electrodes were opposed. An electrolytic solution (manufactured by Kishida Chemical Co., Ltd.) containing diethyl carbonate and ethylene carbonate at a volume ratio of 1:1 and containing 1 mol/L of LiPF 6 was adsorbed to prepare a half battery for evaluation (CR2032 type). Battery characteristics are measured using a secondary battery charge-discharge test device (manufactured by Hokuto Denko), room temperature is 25 ° C., the cutoff voltage range is 0.005-1.4 V, and the charge rate is 0 from the 1st to the 3rd cycle. The charging/discharging characteristics were evaluated under conditions of constant current/constant voltage type charging/discharging and constant current type charging/discharging at 0.2 C after the 4th cycle. At each charge/discharge switch, the battery was left open circuit for 30 minutes.
　フルセルの評価は、正極材料としてＬｉＣｏＯ２を正極活物質、集電体としてアルミ箔を用いた単層シートを用いて、正極膜を作製し、４５０ｍＡｈ／ｇ放電容量設計値にて黒鉛粉体や活物質粉末とバインダーを混合して負極膜を作製した。活物質粉体はハーフセルの充電容量が１５００ｍＡｈ／ｇになるように組成を調整し、非水電解質には六フッ化リン酸リチウムをエチレンカーボネートとジエチルカーボネートを体積比で１／１の混合液に１ｍｏｌ／Ｌの濃度で溶解した非水電解質溶液を用い、セパレータに厚さ３０μｍのポリエチレン製微多孔質フィルムを用いたラミネート型リチウムイオン二次電池を作製した。ラミネート型リチウムイオン二次電池を室温下、テストセルの電圧が４．２Ｖに達するまで１．２ｍＡ（正極基準で０．２５ｃ）の定電流で充電を行い、４．２Ｖに達した後は、セル電圧を４．２Ｖに保つように電流を減少させて充電を行い、放電容量を求めた。室温下３００サイクルの容量維持率は７２％であった。結果を表３に示した。 In the evaluation of the full cell, a single-layer sheet using LiCoO 2 as the positive electrode active material and aluminum foil as the current collector was used to prepare the positive electrode film, and graphite powder and A negative electrode film was produced by mixing an active material powder and a binder. The composition of the active material powder was adjusted so that the charge capacity of the half cell was 1500 mAh/g, and the non-aqueous electrolyte was lithium hexafluorophosphate mixed with ethylene carbonate and diethyl carbonate in a volume ratio of 1/1. A laminated lithium ion secondary battery was fabricated using a non-aqueous electrolyte solution dissolved at a concentration of 1 mol/L and using a polyethylene microporous film having a thickness of 30 μm as a separator. A laminated lithium ion secondary battery is charged at room temperature at a constant current of 1.2 mA (0.25c based on the positive electrode) until the voltage of the test cell reaches 4.2 V. After reaching 4.2 V, Charging was performed by decreasing the current so as to keep the cell voltage at 4.2 V, and the discharge capacity was determined. The capacity retention rate after 300 cycles at room temperature was 72%. Table 3 shows the results.
　実施例２、３、６から８、１１から１３、１６から１８、２５、２６
　実施例１と同様にして、表２に示した樹脂構成比で活物質を作製し、各材料の力学的測定と充放電特性などを評価した。評価結果を表２、３に示した。 Examples 2, 3, 6-8, 11-13, 16-18, 25, 26
In the same manner as in Example 1, active materials were produced with the resin composition ratios shown in Table 2, and mechanical measurements and charge/discharge characteristics of each material were evaluated. The evaluation results are shown in Tables 2 and 3.
　実施例４、５、９、１０、１４、１５、１９、２０
　フェノール樹脂２（スミライトレジン：ＰＲ－５４３８７、住友ベークライト社製）を用いて、表２に示した樹脂構成比で活物質を作製し、各材料の力学的測定と充放電特性などを評価した。評価結果を表２、３に示した。 Examples 4, 5, 9, 10, 14, 15, 19, 20
Using phenolic resin 2 (SUMILITE RESIN: PR-54387, manufactured by Sumitomo Bakelite Co., Ltd.), an active material was produced with the resin composition ratio shown in Table 2, and mechanical measurements and charge/discharge characteristics of each material were evaluated. . The evaluation results are shown in Tables 2 and 3.
　実施例２１および２２
　合成例２に示したポリシロキサン化合物を用いて、表２に示した樹脂構成比で活物質を作製し、材料の力学的測定と充放電特性などを評価した。評価結果を表２、３に示した。 Examples 21 and 22
Using the polysiloxane compound shown in Synthesis Example 2, active materials were produced with the resin composition ratios shown in Table 2, and mechanical measurements and charge/discharge characteristics of the materials were evaluated. The evaluation results are shown in Tables 2 and 3.
　実施例２３および２４
　実施例１との同様にして、表２に示した樹脂構成比とＳｉの平均粒径を１００ｎｍおよび２００ｎｍに変えた活物質を作製し、材料の力学的測定と充放電特性などを評価した。評価結果を表２、３に示した。 Examples 23 and 24
In the same manner as in Example 1, active materials were prepared by changing the resin composition ratio and the average particle size of Si shown in Table 2 to 100 nm and 200 nm, and mechanical measurements and charge/discharge characteristics of the materials were evaluated. The evaluation results are shown in Tables 2 and 3.
　実施例２７および２８
　実施例１との同様にして、表２に示した樹脂構成比に窒素元素源として、メラミンを加えて活物質を作製し、各材料の力学的測定と充放電特性などを評価した。評価結果を表２、３に示した。 Examples 27 and 28
In the same manner as in Example 1, an active material was produced by adding melamine as a nitrogen element source to the resin composition ratio shown in Table 2, and the mechanical measurement and charge/discharge characteristics of each material were evaluated. The evaluation results are shown in Tables 2 and 3.
　比較例１および２
　実施例１において、ポリシロキサン樹脂単独またはフェノール樹脂単独で前駆体を乾燥後、窒素雰囲気、１０５０℃にて６時間焼成して活物質を得た。活物質の押し込み弾性率はそれぞれ１１４ＧＰａ、４．５ＧＰａ、弾性変形仕事率は１８％、１０５％であった。フルセルの充放電測定結果は、室温下３００サイクル後の容量維持率がそれぞれ５０％、６５％であり、大幅に低下した。評価結果を表２、３に示した。 Comparative Examples 1 and 2
In Example 1, after drying the precursor with polysiloxane resin alone or phenol resin alone, it was baked at 1050° C. for 6 hours in a nitrogen atmosphere to obtain an active material. The indentation elastic moduli of the active material were 114 GPa and 4.5 GPa, and the elastic deformation power was 18% and 105%, respectively. As a result of charge-discharge measurement of the full cell, the capacity retention rates after 300 cycles at room temperature were 50% and 65%, respectively, which were greatly reduced. The evaluation results are shown in Tables 2 and 3.
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
［評価方法］
　平均粒径および比表面積は以下の方法で求めた。
　平均粒径：レーザー回折式粒度分布測定装置（マルバーン・パナリティカル社製、マスターサイザー３０００）を用いて測定しＤ５０の値を平均粒径とした。
　比表面積：比表面積測定装置（ＢＥＬＪＡＰＡＮ社製、ＢＥＬＳＯＲＰ－ｍｉｎｉ）を用いて窒素吸着測定より、ＢＥＴ法で測定した。 [Evaluation method]
The average particle size and specific surface area were obtained by the following methods.
Average particle size: measured using a laser diffraction particle size distribution analyzer (Mastersizer 3000, manufactured by Malvern Panalytical), and the D50 value was defined as the average particle size.
Specific surface area: Measured by BET method from nitrogen adsorption measurement using a specific surface area measuring device (BELSORP-mini, manufactured by BEL JAPAN).
　押し込み硬度、押し込み弾性率、および弾性変形仕事率は以下の方法で求めた。
測定サンプルの力学的物性測定をナノインテンダー測定装置（ＥＮＴ－２１００：エリオ二クス（株）社製）を用いて行った。測定はＩＳＯ１４５７７に準拠した方式で実施した。試料形状は、測定圧子に対して垂直であり、局所的に平面である構造体で、凹凸面を少なくする為、試料は厚さを３ｍｍ以下とし、場合に応じて表面を粒度２０００、５０００およびバフ研磨を行ったものを用いた。測定条件は、開始荷重０ｍＮ、終了荷重１００ｍＮ、分割数５００、ステップ間隔２０ｍｓの負荷、除荷試験を任意の箇所で２０点測定し、平均値を算出した。 The indentation hardness, indentation elastic modulus, and elastic deformation power were obtained by the following methods.
The mechanical properties of the measurement sample were measured using a nanointender measuring device (ENT-2100: manufactured by Elionix Co., Ltd.). The measurement was carried out in accordance with ISO14577. The shape of the sample is a structure that is perpendicular to the measuring indenter and is locally flat. A buffed one was used. Measurement conditions were as follows: starting load 0 mN, ending load 100 mN, number of divisions 500, step interval 20 ms loading, unloading test was measured at 20 arbitrary points, and the average value was calculated.
　電池特性評価：二次電池充放電試験装置（北斗電工株式会社製）を用いて電池特性を測定し、室温２５℃、カットオフ電圧範囲が０．００５から１．４Ｖに、１から３サイクル目までは充放電レートを０．１Ｃ、４サイクル目以後は０．２Ｃとし、定電流・定電圧式充電／定電流式放電の設定条件下で充放電特性の評価試験を行った。各充放電時の切り替え時には、３０分間、開回路で放置した。２５℃でフルセルを３００サイクル充放電後の容量維持率は以下のようにして、フルセル（ラミネートセル）の測定で求めた。容量維持率（％＠３００回目）＝３００回目の負極放電容量（ｍＡｈ／ｇ）／負極初回放電容量（ｍＡｈ／ｇ） Battery characteristics evaluation: Battery characteristics are measured using a secondary battery charge-discharge test device (manufactured by Hokuto Denko Co., Ltd.), room temperature 25 ° C., cutoff voltage range from 0.005 to 1.4 V, 1st to 3rd cycles The charge/discharge rate was set to 0.1 C up to the fourth cycle and 0.2 C from the fourth cycle onward, and the charge/discharge characteristics were evaluated under the set conditions of constant current/constant voltage charge/constant current discharge. At the time of switching between charging and discharging, the battery was left in an open circuit for 30 minutes. The capacity retention rate after 300 cycles of charging and discharging a full cell at 25° C. was obtained by measuring a full cell (laminate cell) as follows. Capacity retention rate (% @ 300th cycle) = 300th negative electrode discharge capacity (mAh/g)/negative electrode initial discharge capacity (mAh/g)
　前記結果から明らかなように、前記物性１から３のいずれかを満たす珪素系材料を含む本活物質を負極活物質として用いた場合、容量維持率に優れる。また本活物質を負極活物質として含む二次電池はその電池特性に優れると考えられる。 As is clear from the above results, when the present active material containing a silicon-based material that satisfies any of the physical properties 1 to 3 is used as the negative electrode active material, the capacity retention rate is excellent. In addition, secondary batteries containing the present active material as a negative electrode active material are considered to have excellent battery characteristics.

Claims (11)

  1. 　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａ以下、および弾性変形仕事率が２０％以上９０％以下からなる群より選択される少なくとも１の物性を有するケイ素系材料。 At least one selected from the group consisting of an indentation hardness of 1 GPa or more and 11 GPa or less, an indentation elastic modulus of 10 GPa or more and 110 GPa or less, and an elastic deformation power of 20% or more and 90% or less in mechanical strength measurement using a nanoindentation method. A silicon-based material with physical properties of
  2. 　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下で且つ、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａである請求項１に記載のケイ素系材料。 The silicon-based material according to claim 1, which has an indentation hardness of 1 GPa or more and 11 GPa or less and an indentation elastic modulus of 10 GPa or more and 110 GPa in a mechanical strength measurement using a nanoindentation method.
  3. 　ナノインデンテーション法を用いた力学強度測定において、押し込み硬度が１ＧＰａ以上１１ＧＰａ以下で且つ、弾性変形仕事率が２０％以上９０％以下である請求項１に記載のケイ素系材料。 The silicon-based material according to claim 1, which has an indentation hardness of 1 GPa or more and 11 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
  4. 　ナノインデンテーション法を用いた力学強度測定において、押し込み弾性率が１０ＧＰａ以上１１０ＧＰａ以下で且つ、弾性変形仕事率が２０％以上９０％以下である請求項１に記載のケイ素系材料。 The silicon-based material according to claim 1, which has an indentation elastic modulus of 10 GPa or more and 110 GPa or less and an elastic deformation work rate of 20% or more and 90% or less in a mechanical strength measurement using a nanoindentation method.
  5. 　主成分としてケイ素元素、酸素元素、炭素元素を含む請求項１から４のいずれか１項に記載のケイ素系材料。 The silicon-based material according to any one of claims 1 to 4, which contains silicon element, oxygen element, and carbon element as main components.
  6. 　主成分としてＳｉＯｘＣｙ　（１≦ｘ＜２、１≦ｙ≦８０）を含む請求項５に記載のケイ素系材料。 The silicon-based material according to claim 5, containing SiOxCy (1≤x<2, 1≤y≤80) as a main component.
  7. 　窒素元素を含む請求項６に記載のケイ素系材料。 The silicon-based material according to claim 6, which contains a nitrogen element.
  8. 　請求項１から７のいずれか１項に記載のケイ素系材料を主成分とするマトリクス相に平均粒径２００ｎｍ以下のシリコン粒子が分散された複合材料。 A composite material in which silicon particles having an average particle size of 200 nm or less are dispersed in a matrix phase containing the silicon-based material according to any one of claims 1 to 7 as a main component.
  9. 　請求項８に記載の複合材料を含む二次電池用負極活物質。 A negative electrode active material for a secondary battery comprising the composite material according to claim 8.
  10. 　請求項９に記載の二次電池用負極活物質を含む負極。 A negative electrode comprising the negative electrode active material for a secondary battery according to claim 9.
  11. 　請求項１０に記載の負極を含む二次電池。 A secondary battery comprising the negative electrode according to claim 10.
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