WO2019131864A1 - Negative electrode material for lithium ion secondary battery - Google Patents

Negative electrode material for lithium ion secondary battery Download PDF

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Publication number
WO2019131864A1
WO2019131864A1 PCT/JP2018/048102 JP2018048102W WO2019131864A1 WO 2019131864 A1 WO2019131864 A1 WO 2019131864A1 JP 2018048102 W JP2018048102 W JP 2018048102W WO 2019131864 A1 WO2019131864 A1 WO 2019131864A1
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Prior art keywords
particles
negative electrode
lithium ion
ion secondary
secondary battery
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PCT/JP2018/048102
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French (fr)
Japanese (ja)
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貴行 栗田
石井　伸晃
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昭和電工株式会社
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Publication of WO2019131864A1 publication Critical patent/WO2019131864A1/en

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    • 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
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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 a negative electrode material for a lithium ion secondary battery.
  • the speed-up of the power saving of the electronic components has advanced the multifunctionalization of portable electronic devices, and the power consumption of the portable electronic devices is increasing. Therefore, there is a strong demand for higher capacity and smaller size of the lithium ion secondary battery, which is the main power source of portable electronic devices. In addition, demand for electric vehicles is increasing, and there is a strong demand for higher capacity in lithium ion secondary batteries used therein.
  • Patent Document 1 is a negative electrode material made of a Si-based alloy for a storage device accompanied by migration of lithium ions during discharge, and the negative electrode material made of the Si-based alloy is Si main phase and other than Si and Si.
  • the negative electrode material which consists of Si type alloys for electrical storage devices whose crystallite size of the compound phase which consists of Cu is 40 nm or less is disclosed.
  • Patent Document 2 is silicon mainly used as a negative electrode active material for a lithium ion secondary battery, and has a crystallite size of 1 to 200 nm by powder X-ray diffraction, and an average particle diameter of 0.1 by a laser method. It discloses silicon fine particles having a specific surface area of up to 5 ⁇ m and a BET surface area of at least 10 m 2 / g.
  • Patent Document 1 attempts to reduce the crystalline size, it is unclear which crystal plane is focused on, and the Si particle size is not described.
  • the invention of Patent Document 2 has an allowable Si crystallite size too large compared to Patent Document 1, and may not lead to expansion suppression.
  • the expansion suppression of the negative electrode is the point that the negative electrode material is formed of Si alone or the Si particle diameter is 0.1 ⁇ m or more.
  • An object of the present invention is to provide a negative electrode material for a lithium ion secondary battery, which has a small expansion of the electrode with use and a long life.
  • the present invention includes the following aspects.
  • Si particles (A1) having an average particle diameter d AV of 5 nm or more and 95 nm or less, an amorphous carbon coating layer (A1 C) with a thickness of 1 nm or more and 20 nm or less, which covers the particles (A1);
  • a negative electrode material for a lithium ion secondary battery comprising a composite (A) comprising particles (A2) comprising a material containing graphite and a carbonaceous material (A3), wherein the composite (A) is a powder X-ray
  • the negative electrode material for a lithium ion secondary battery wherein a half value width of a (111) plane diffraction peak of the Si particles (A1) by diffraction measurement is 0.40 degrees or more.
  • the particles (A2) have a 50% particle diameter DV50 in the volume-based cumulative particle size distribution of 2.0 ⁇ m to 20.0 ⁇ m, and a BET specific surface area (S BET ) of 1.0 m 2 / g to 10
  • the ratio I 110 / I 004 of the peak intensity I 110 of the ( 110 ) plane to the peak intensity I 004 of the (004) plane by powder X-ray diffraction method is 0.10 or more 0.35 or less
  • the average interplanar spacing d 002 of the (002) plane by powder X-ray diffraction is 0.3360 nm or less
  • the total fineness of pores with a diameter of 0.4 ⁇ m or less measured by nitrogen gas adsorption The negative electrode material for a lithium ion secondary battery according to the above 1 or 2, wherein the pore volume is 5.0 ⁇ L / g or more and 40.0 ⁇ L / g or less.
  • Material. [5] A sheet-like current collector and a negative electrode layer for covering the current collector, the negative electrode layer comprising a binder, a conductive additive and the negative electrode for lithium ion secondary battery according to any one of the above 1 to 4 Material containing negative electrode sheet. [6] A lithium ion secondary battery having the negative electrode sheet described in the preceding item 5.
  • a negative electrode material for a lithium ion secondary battery according to an embodiment of the present invention is a composite (particles (A1), an amorphous carbon coating layer (A1C), particles (A2), and a carbonaceous material (A3) A) is included.
  • the particles (A1) used in one embodiment of the present invention contain Si as a main component capable of inserting and extracting lithium ions.
  • the content of Si is preferably 90% by mass or more, more preferably 95% by mass or more.
  • the particles (A1) may be composed of a simple substance of Si or a compound containing a Si element, a mixture, a eutectic or a solid solution.
  • the particles (A1) before being complexed with the particles (A2) and the carbonaceous material (A3) may be aggregations of a plurality of fine particles, that is, secondary particles.
  • grains (A1) a lump shape, scale shape, spherical shape, fibrous shape etc. can be mentioned. Among these, spherical or massive is preferable.
  • the material containing Si element, the general formula and a element M other than Si alone or Si and Li: be mentioned M ( M a + M b + M c + M d ⁇ ) material represented by m Si it can.
  • the substance is a compound, a mixture, a eutectic or a solid solution containing the element M in a ratio of m moles to 1 mole of Si.
  • the element M which is an element other than Li include B, C, N, O, S, P, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Pt, Be, Nb, Nd, Ce, W, Ta, Ag, Au, Cd, Ga, In, Sb, Ba and the like can be mentioned.
  • m is preferably 0.01 or more, more preferably 0.10 or more, and still more preferably 0.30 or more.
  • the substance containing Si element include elemental Si, an alloy of Si and an alkaline earth metal; an alloy of Si and a transition metal; an alloy of Si and a semimetal; Si, Be, Ag, Al, Au , Cd, Ga, in, solid-solution alloys or KyoTorusei alloy of Sb or Zn; CaSi, CaSi 2, Mg 2 Si, BaSi 2, Cu 5 Si, FeSi, FeSi 2, CoSi 2, Ni 2 Si, NiSi 2, MnSi, MnSi 2, MoSi 2, CrSi 2, Cr 3 Si, TiSi 2, Ti 5 Si 3, NbSi 2, NdSi 2, CeSi 2, WSi 2, W 5 Si 3, TaSi 2, Ta 5 Si 3, It may be mentioned SiO 2, SiC, Si 3 N 4 and the like; PtSi, V 3 Si, VSi 2, PdSi, RuSi, silicides such RhSi.
  • the lower limit of the average particle diameter d AV of the primary particles of the particles (A1) is 5 nm, preferably 10 nm, and more preferably 35 nm. Further, the upper limit value of d AV of the primary particles is 95 nm, preferably 70 nm.
  • the d AV of the primary particles of the particles (A1) is larger than 95 nm, the particles (A1) expand and shrink in volume due to charge and discharge and the influence on the structure of the composite (A) containing the particles (A1) increases. Maintenance rate decreases.
  • the d AV of the primary particles is smaller than 5 nm, the specific surface area of the particles (A1) is increased, and the amount of side reaction is increased.
  • Average particle diameter d AV [nm] 6 x 10 3 / ( ⁇ x S BET ) Defined by Here, [[g / cm 3 ] is the true density of Si particles, and the theoretical value of 2.3 [g / cm 3 ] was adopted. S BET [m 2 / g] is a specific surface area measured by the BET method using N 2 gas as an adsorption gas.
  • the particles (A1) are coated on their surface with a thin amorphous carbon coating layer (A1C).
  • the upper limit of the thickness of the amorphous carbon coating layer (A1C) is 20 nm, preferably 10 nm, more preferably 5 nm. This is to suppress the side reaction between the electrolytic solution and the amorphous carbon coating layer (A1C).
  • the lower limit of the thickness of the amorphous carbon coating layer (A1C) is 1 nm, preferably 2 nm, and more preferably 3 nm. This is because the oxidation of the particles (A1) and the aggregation of the particles (A1) are suppressed.
  • the thickness of the amorphous carbon coating layer (A1C) can be determined by measuring the film thickness in an image taken by observation with a transmission electron microscope (TEM). An example of a specific TEM observation is shown below.
  • Device H9500 manufactured by Hitachi, Ltd. Acceleration voltage: 300 kV.
  • Preparation of sample A small amount of sample is taken in ethanol and dispersed by ultrasonic irradiation, and then placed on a microgrid observation mesh (without a supporting film) to make an observation sample.
  • Observation magnification 50,000 times (at the time of particle shape observation) and 400,000 times (at the time of thickness observation of an amorphous carbon layer)
  • the core-shell structure (hereinafter referred to as a structure ( ⁇ )) comprising particles (A1) and an amorphous carbon coating layer (A1C) covering the particles preferably has a BET specific surface area of 25 m 2 / g to 70 m. It is 2 / g or less, more preferably 52 m 2 / g or more and 67 m 2 / g or less. Moreover, the density of primary particles is 2.2 g / cm 3 or more.
  • the BET specific surface area (S BET ) of the structure ( ⁇ ) is 25 m 2 / g or more, the particle diameter of the structure ( ⁇ ) does not become too large, and the electron transfer path in the solid of the structure ( ⁇ ) and Li The ion diffusion path will not be long. That is, the resistance at the time of charge and discharge is kept low. Furthermore, the absolute value of the amount of expansion per particle of the structure ( ⁇ ) does not increase, and the possibility of destruction of the structure of the complex (A) around the structure ( ⁇ ) is low. In addition, when the density of the structure ( ⁇ ) is 2.2 g / cm 3 or more, it is also advantageous in terms of volumetric energy density.
  • the content of particles (A1) in the composite (A) is preferably 2% by mass to 95% by mass, more preferably 5% by mass to 80% by mass, and still more preferably 10% by mass to 70% by mass It is.
  • the content of the particles (A1) is 95% by mass or less, no problem occurs in the battery performance due to the increase in the electrical resistance.
  • the content of the particles (A1) is 2% by mass or more, the superiority in terms of volume or mass energy density is maintained.
  • the structure ( ⁇ ) composed of the particles (A1) and the amorphous carbon coating layer (A1C) can be produced by any of the solid phase method, liquid phase method and gas phase method, but the gas phase method is preferable.
  • the graphite particles contained in the particles (A2) in the preferred embodiment of the present invention are preferably artificial graphite particles.
  • the size and shape of the optical structure are in a specific range, and an artificial graphite particle having an appropriate degree of graphitization can provide an electrode material having both excellent crushing characteristics and battery characteristics.
  • D V 50 represents a 50% particle size in a volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer, and represents an apparent diameter of particles.
  • the 50% particle diameter D V50 in the volume-based cumulative particle size distribution of the graphite particles contained in the particles (A2) in the preferred embodiment of the present invention is preferably 2.0 ⁇ m or more and 20.0 ⁇ m or less, more preferably 5.0 ⁇ m or more 18 .0 ⁇ m or less. If the D V 50 is 2.0 ⁇ m or more, it is not necessary to grind with a special device at the time of grinding, and energy can be saved. Moreover, since it is hard to cause aggregation, the handling property at the time of coating is also good. Furthermore, since the specific surface area does not become excessively large, the decrease in the initial charge and discharge efficiency does not occur.
  • D V 50 is 20.0 ⁇ m or less, it does not take time to diffuse lithium in the negative electrode material, and hence the input / output characteristics are good. Further, since silicon-containing particles are uniformly compounded on the surface of the graphite particles, good cycle characteristics can be obtained.
  • Graphite particles contained in the particle (A2) in a preferred embodiment of the present invention BET specific surface area of preferably 1.0 m 2 / g or more 10.0 m 2 / g or less by N 2 gas adsorption method, 3.0 m 2 / g or more and 7.5 m 2 / g or less is more preferable.
  • BET specific surface area of the graphite particles is in the above range, a large area in contact with the electrolytic solution can be secured while suppressing an irreversible side reaction as a negative electrode material, so that the input / output characteristics are improved.
  • the artificial graphite particles contained in the particles (A2) in the preferred embodiment of the present invention have peak intensities I 110 of the (110) plane of the graphite crystal and peaks of the (004) plane in the diffraction peak profile obtained by powder X-ray diffraction. It preferably has a specific I 110 / I 004 intensity I 004 is 0.10 or more 0.35 or less.
  • the ratio is more preferably 0.18 or more and 0.30 or less, and still more preferably 0.21 or more and 0.30 or less. If the ratio is 0.10 or more, the orientation is not too high, and the current collector surface of the electrode is due to expansion and contraction associated with insertion and desorption (occluding and releasing) of lithium ions to Si and graphite in the negative electrode material.
  • the average interplanar spacing d 002 of the (002) plane according to powder X-ray diffraction method is preferably 0.3360 nm or less.
  • the thickness Lc in the C-axis direction of the crystallite of the artificial graphite particle is preferably 50 nm or more and 1000 nm or less from the viewpoint of mass energy density and crushability.
  • d 002 and Lc can be measured by powder X-ray diffraction (XRD) according to a known method (Michio Inagaki, “carbon”, 1963, No. 36, pages 25-34; Iwashita et al., Carbon vol. 42 (2004), p. 701-714).
  • XRD powder X-ray diffraction
  • the artificial graphite particles contained in the particles (A2) in the preferred embodiment of the present invention have a total pore volume of 5.0 ⁇ L / g or more of pores with a diameter of 0.4 ⁇ m or less according to nitrogen gas adsorption BET method under liquid nitrogen cooling. It is preferably 40.0 ⁇ L / g or less. More preferably, it is 25.0 ⁇ L / g or more and 40.0 ⁇ L / g or less.
  • An artificial graphite particle having a total pore volume of 5.0 ⁇ L / g or more tends to be complexed with the particle (A1) and the carbonaceous material (A3), and is preferable in terms of improvement of the cycle capacity retention rate.
  • the artificial graphite particles contained in the particles (A2) in a preferred embodiment of the present invention have a peak intensity I D of 1580 to 1620 cm of the peak derived from the amorphous component in the range of 1300 to 1400 cm.sup.- 1 measured by Raman spectroscopy.
  • the ratio I D / I G (R value) to the intensity I G of the peak derived from the graphite component in the range of -1 is preferably 0.04 or more and 0.18 or less, preferably 0.08 or more and 0.16 or less It is further preferred that If the R value is 0.04 or more, the crystallinity of graphite is not too high, and good rapid charge / discharge characteristics can be obtained.
  • the Raman spectrum can be measured, for example, by observing with a microscope attached using a laser Raman spectrophotometer (NRS-5100 manufactured by JASCO Corporation).
  • the graphite particles contained in the particles (A2) may be produced by heating particles obtained by crushing coke having a heat history of 1000 ° C. or less. it can.
  • a raw material of coke for example, petroleum pitch, coal pitch, coal pitch coke, petroleum coke and mixtures thereof can be used. That is, as the graphite particles contained in the particles (A2), it is preferable to use a material derived from petroleum-based coke and / or coal-based coke. Among these, those subjected to delayed coking under specific conditions are desirable.
  • the raw material to be passed through a delayed coker is a decanted oil from which the catalyst has been removed after fluid bed catalytic cracking has been performed on heavy fractions at the time of crude oil refining, coal tar extracted from bituminous coal, etc. And those obtained by sufficiently distilling the tar obtained by raising the temperature to 100 ° C. or higher.
  • the temperature of these liquids be raised to 450 ° C. or higher, 500 ° C. or higher, or even 510 ° C. or higher at least at the entrance of the drum.
  • the carbon content increases and the yield improves.
  • the pressure in the drum is preferably maintained at normal pressure or higher, more preferably 300 kPa or higher, and still more preferably 400 kPa or higher. This further increases the capacity as the negative electrode. As described above, by performing coking under more severe conditions than usual, the liquid can be reacted more and coke having a higher degree of polymerization can be obtained.
  • the obtained coke is cut out from the inside of the drum by a jet water flow, and the obtained mass is roughly crushed to about 5 cm with a gold crucible or the like.
  • a twin-roll crusher or a jaw crusher can also be used for the coarse grinding, it is preferable that the 1 mm sieve is ground to have 90% by mass or more.
  • the coke is then crushed.
  • the pulverization property is significantly reduced, so it is preferable to previously dry it at about 100 to 1000.degree. More preferably, it is 100 to 500 ° C.
  • the crushing strength becomes strong and the crushability deteriorates, and the crystal anisotropy develops, so that the cleavage property becomes strong and it becomes easy to be a scaly powder.
  • a known jet mill, hammer mill, roller mill, pin mill, vibration mill or the like can be used. Milling is preferably carried out as D V50 becomes 2.0 ⁇ m or 20.0 ⁇ m or less, and more preferably more than 5.0 .mu.m 18.0.
  • Graphitization is preferably performed at a temperature of 2400 ° C. or higher, more preferably 2800 ° C. or higher, still more preferably 3050 ° C. or higher, still more preferably 3150 ° C. or higher under an inert atmosphere (eg, nitrogen gas or argon gas atmosphere) Do.
  • an inert atmosphere eg, nitrogen gas or argon gas atmosphere
  • the graphitization temperature is preferably 3600 ° C. or less.
  • the carbon raw material be calcined to remove organic volatile components, that is, the fixed carbon content is 95% or more, more preferably 98% or more, and still more preferably 99% or more.
  • This firing can be performed, for example, by heating at 700 to 1500.degree. Since the reduction in mass at the time of graphitization is reduced by firing, the throughput of the graphitization processing apparatus can be increased once.
  • the carbonaceous material (A3) in a preferred embodiment of the present invention is a carbon material which is different from the particles (A2) and in which the development of crystals formed by carbon atoms is low, and a Raman spectrum by Raman scattering spectroscopy. Has a peak near 1360 cm -1 .
  • the carbonaceous material (A3) may be the same as the amorphous carbon coating layer (A1C).
  • the carbonaceous material (A3) can be produced, for example, by carbonizing a carbon precursor.
  • the carbon precursor is not particularly limited, but includes, but not limited to, thermal heavy oil, pyrolysis oil, straight asphalt, blown asphalt, petroleum-derived substances such as tar or petroleum pitch by-produced during ethylene production, coal tar produced during coal distillation,
  • the heavy component obtained by distilling off the low-boiling component of coal tar, and coal-derived materials such as coal tar pitch (coal pitch) are preferred, and petroleum pitch or coal pitch is particularly preferred.
  • Pitch is a mixture of multiple polycyclic aromatic compounds. When pitch is used, a carbonaceous material (A3) with few impurities can be produced at a high carbonization rate. Since the pitch has a low oxygen content, when the particles (A1) are coated with the carbonaceous material, the particles (A1) are less likely to be oxidized.
  • the pitch as a precursor of the carbonaceous material (A3) preferably has a softening point of 80 ° C. or more and 300 ° C. or less. If the softening point of pitch is 80 ° C. or higher, the average molecular weight of the polycyclic aromatic compound constituting it is not too small, and the volatile content is also relatively small, so the carbonization rate decreases, the manufacturing cost increases, and further There is no problem that a carbonaceous material (A3) having a large specific surface area containing many pores can be easily obtained. If the softening point of the pitch is 300 ° C. or less, the viscosity is not too high, so that it can be uniformly mixed with the particles (A1). The softening point of pitch can be measured by the Mettler method described in ASTM-D 3104-77.
  • the pitch of the carbonaceous material (A3) as a precursor is preferably 20% by mass to 70% by mass, and more preferably 25% by mass to 60% by mass, as a residual carbon ratio.
  • the residual carbon ratio of the pitch is 20% by mass or more, problems such as an increase in manufacturing cost and a carbonaceous material having a large specific surface area do not occur.
  • the residual carbon ratio of the pitch is 70% by mass or less, the viscosity is not too high, and therefore, it can be uniformly mixed with the particles (A1).
  • the residual coal rate is determined by the following method.
  • the solid pitch is ground in a mortar or the like, and the ground product is subjected to mass thermal analysis under a nitrogen gas flow.
  • the ratio of mass to charged mass at 1100 ° C. is defined as the residual carbon ratio.
  • the pitch used in the present invention preferably has a QI (quinoline insoluble content) content of 10% by mass or less, more preferably 5% by mass or less, and still more preferably 2% by mass or less.
  • the QI content of pitch is a value corresponding to the amount of free carbon.
  • the pitch containing a large amount of free carbon is heat-treated, the free carbon adheres to the surface of the sphere to form a three-dimensional network in the process of appearance of mesophase spheres, thereby hindering the growth of the sphere, and thus it tends to be a mosaic structure.
  • heat treatment is performed on a pitch having a small amount of free carbon, mesophase spheres grow large and tend to generate needle coke.
  • the QI content is in the above range, the electrode characteristics are further improved.
  • the pitch used in the present invention preferably has a TI (toluene insoluble content) content of 10% by mass to 70% by mass.
  • the pitch with low TI content has a low average carbon weight and high volatile content because the polycyclic aromatic compound constituting it has a low carbonization rate, an increase in production cost, and a large specific surface area including many pores. Carbonaceous materials are easily obtained.
  • the pitch with a high TI content has a high carbonization rate because the average molecular weight of the polycyclic aromatic compound constituting it is high, but the pitch with a high TI content is uniformly mixed with the particles (A1) since the viscosity is high. It tends to be difficult. When the TI content is in the above-mentioned range, it is possible to uniformly mix the pitch and the other components, and to obtain a negative electrode material having characteristics suitable as a battery active material.
  • the QI content and the TI content of the pitch used in the present invention can be measured by the method described in JIS K2425 or a method according thereto.
  • the mass ratio of the carbonaceous material (A3) to the total mass of the particles (A1), the particles (A2) and the carbonaceous material (A3) is preferably 2% by mass to 40% by mass, and more preferably 4% % Or more and 30% by mass or less.
  • the proportion of the carbonaceous material (A3) is 2% by mass or more, sufficient bonding between the particles (A1) and the particles (A2) can be obtained, and the surface of the particles (A1) can be a carbonaceous material (A3)
  • conductivity is easily imparted to the particles (A1), and an effect of suppressing surface reactivity of the particles (A1) and an effect of alleviating expansion and contraction are obtained, and good cycle characteristics are obtained.
  • the proportion of the carbonaceous material (A3) is 40% by mass or less, the initial efficiency does not decrease even if the proportion of the carbonaceous material (A3) is high.
  • the composite (A) comprises a structure ( ⁇ ) comprising particles (A1) and an amorphous carbon coating layer (A1C), particles (A2), and a carbonaceous material (A3). It is preferable that at least a part of the structure ( ⁇ ), the particles (A2) and the carbonaceous material (A3) be complexed with each other.
  • the complexing is, for example, a state in which the structure ( ⁇ ) and the particle (A2) are fixed by the carbonaceous material (A3) and bound, or the structure ( ⁇ ) and / or the particle (A2) is carbon The state covered with the quality material (A3) can be mentioned.
  • the structure ( ⁇ ) is completely covered with the carbonaceous material (A3) and the surface of the structure ( ⁇ ) is not exposed, among which the structure ( ⁇ ) And particles (A2) are linked via the carbonaceous material (A3), and the whole is covered with the carbonaceous material (A3), and the structure ( ⁇ ) and particles (A2) are in direct contact It is preferable that the whole is covered with the carbonaceous material (A3).
  • the surface of the structure ( ⁇ ) is not exposed, so that the electrolytic solution decomposition reaction is suppressed and the coulombic efficiency can be maintained high, and particles (the carbonaceous material (A3) A2) and the structure ( ⁇ ) can increase the conductivity between each other, and the structure ( ⁇ ) is covered with the carbonaceous material (A3) to be accompanied by its expansion and contraction. Volume changes can be buffered.
  • the composite (A) according to an embodiment of the present invention may contain the particles (A2), the carbonaceous material (A3) or the structure ( ⁇ ) alone, which are not complexed. It is preferable that the amount of the particles (A2), the carbonaceous material (A3), or the structures ( ⁇ ) contained alone without being complexed is small, and specifically, to the mass of the complex (A) On the other hand, it is preferably 10% by mass or less.
  • DV50 of the complex (A) which concerns on one Embodiment of this invention
  • 2.0 micrometers or more and 20.0 micrometers or less are preferable. More preferably, it is 2.0 micrometers or more and 18.0 micrometers or less. If DV50 is 2.0 micrometers or more, economical manufacture is possible. Also, there is no difficulty in increasing the electrode density. Furthermore, since the specific surface area is not excessively increased, the decrease in the initial charge and discharge efficiency due to the side reaction with the electrolytic solution does not occur. Further, if the DV50 is 20.0 ⁇ m or less, good input / output characteristics and cycle characteristics can be obtained.
  • the BET specific surface area (S BET ) of the composite (A) is preferably 1.0 m 2 / g or more and 10.0 m 2 / g or less. More preferably, it is 1.0 m 2 / g or more and 5.0 m 2 / g or less. If the BET specific surface area (S BET ) is 1.0 m 2 / g or more, uniform distribution in the electrode is maintained without deterioration of input / output characteristics, and good cycle characteristics can be obtained. When the BET specific surface area (S BET ) is 10.0 m 2 / g or less, the coating property is not lowered and the handling property is also good. In addition, it is easy to increase the electrode density without requiring a large amount of binder for electrode production, and it is possible to suppress a decrease in initial charge and discharge efficiency due to a side reaction with the electrolytic solution.
  • the half value width of the (111) plane diffraction peak of the Si particle (A1) measured by the X-ray diffraction method is 0.40 to 0.71 degrees. Preferably it is 0.40 degree or more and 0.65 degree or less, More preferably, it is 0.40 degree or more and 0.65 degree or less.
  • the half value width of the (111) plane diffraction peak of the Si particle (A1) is less than 0.40 degrees, the crystallite size of the Si particle (A1) becomes large and the expansion of the Si particle (A1) becomes anisotropic. . As a result, the electrode expansion rate increases and the cycle capacity retention rate decreases.
  • the half value width of the diffraction peak of the particles (A1) can be measured using the powder X-ray diffraction (XRD) method described above (Michio Inagaki, “carbon”, 1963, No. 36, pages 25-34; Iwashita et al., Carbon vol. 42 (2004), p. 701-714). In this measurement, when the half value width of the (111) plane diffraction peak of the Si particle (A1) exceeds 0.71 degrees, the crystallite size becomes less than 0 nm, which can not occur.
  • XRD powder X-ray diffraction
  • the complex (A) has a peak intensity I D of a peak in the range of 1300 to 1400 cm ⁇ 1 in a Raman spectrum obtained by measuring the particle end face with a microscopic Raman spectrometer.
  • the ratio I D / I G (R value) of the peak intensity to the peak intensity I G in the range of 1580 to 1620 cm -1 is preferably 0.15 or more and 1.0 or less. More preferably, it is 0.2 or more and 1.0 or less, still more preferably 0.4 or more and 1.0 or less.
  • the fact that the R value is too small means that the surface of the particles (A2) is exposed to a certain amount.
  • the particles (A2) and the particles (A1) are covered with the carbonaceous material (A3), and the effect of suppressing the surface reactivity of the particles (A1) or expansion and contraction Good cycle characteristics can be obtained because the effect of relieving is increased.
  • the R value is too large, it indicates that the carbonaceous material (A3) containing a large amount of amorphous carbon having a large initial irreversible capacity covers the surface of the particles (A2). Therefore, if R value is 1.0 or less, the fall of initial stage discharge efficiency is suppressed.
  • the complex (A) according to an embodiment of the present invention can be produced according to a known method.
  • the structure ( ⁇ ) consisting of the particles (A1) and the amorphous carbon coating layer (A1C), the particles (A2) and the precursor of the carbonaceous material (A3) are mixed, and the obtained mixture is heat-treated Complex (A) can be obtained by the method including making the said precursor into carbonaceous material (A3).
  • the mixture of the structure ( ⁇ ), the particles (A2) and the precursor of the carbonaceous material (A3) melts the pitch which is one of the precursors of the carbonaceous material (A3), and the molten pitch and structure
  • melts the pitch which is one of the precursors of the carbonaceous material (A3), and the molten pitch and structure
  • the body ( ⁇ ) in an inert atmosphere, solidifying and then grinding the mixture, and mixing the ground product with the particles (A2); the structure ( ⁇ ) and the particles (A2)
  • a known device such as a hybridizer (registered trademark, manufactured by Nara Machinery Co., Ltd.) can be used.
  • the means of grinding mainly by impact and shear such as a pin mill and a rotary cutter mill, tends to transmit shear force preferentially to large particle size particles and less to small particle size particles.
  • Such an apparatus can be used to grind or mix the particles (A1) and the structure ( ⁇ ) without promoting oxidation.
  • the non-oxidizing atmosphere an atmosphere filled with an inert gas such as argon gas or nitrogen gas can be mentioned.
  • the heat treatment for converting the carbonaceous material (A3) precursor to the carbonaceous material (A3) is preferably 200 ° C. or more and 2000 ° C. or less, more preferably 500 ° C. or more and 1500 ° C. or less, particularly preferably 600 ° C. or more and 1200 ° C. or less At a temperature of By this heat treatment, the carbonaceous material (A3) coats the structural body ( ⁇ ) and / or the particles (A2), and the carbonaceous material (A3) is between the structural bodies ( ⁇ ) and the particles (A2) And between the structure ( ⁇ ) and the particles (A2) to connect them.
  • the heat treatment is preferably performed in a non-oxidative atmosphere.
  • a non-oxidative atmosphere an atmosphere filled with an inert gas such as argon gas or nitrogen gas can be mentioned.
  • an inert gas such as argon gas or nitrogen gas
  • a crushing method a pulperizer using an impact force such as a hammer, a jet mill using a collision of objects to be crushed and the like are preferable.
  • a material containing the composite (A) and carbon for the purpose of improving battery performance as the negative electrode material for lithium ion secondary batteries and for the purpose of adjusting the capacity of the negative electrode material for lithium ion secondary batteries May be mixed.
  • a plurality of types of materials containing carbon to be mixed may be used.
  • As a material containing carbon graphite having a high capacity is preferable.
  • the graphite can be selected from natural graphite and artificial graphite.
  • the material containing carbon for adjusting the volume may be mixed with the composite (A) in advance, and additives such as a binder, a solvent, and a conductive additive may be added thereto to prepare a negative electrode paste.
  • the negative electrode paste may be prepared by simultaneously mixing the composite (A), a material containing carbon, a binder, a solvent, an additive such as a solvent, a conductive additive, and the like. The order and method of mixing may be appropriately determined in consideration of powder handling and the like.
  • the paste for an anode according to one embodiment of the present invention contains the above-mentioned anode material, a binder, a solvent, and, if necessary, an additive such as a conductive aid.
  • This negative electrode paste can be obtained, for example, by kneading the negative electrode material, the binder, the solvent, and the conductive auxiliary agent as needed.
  • the negative electrode paste can be formed into a sheet, a pellet, or the like.
  • Examples of the material used as the binder include polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, butyl rubber, acrylic rubber, and a polymer compound having a large ion conductivity.
  • Examples of the polymer compound having large ion conductivity include polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphasphazen, polyacrylonitrile and the like.
  • the amount of the binder is preferably 0.5 parts by mass to 100 parts by mass with respect to 100 parts by mass of the negative electrode material.
  • the conductive aid is not particularly limited as long as it plays the role of imparting conductivity and electrode stability (buffering action against volume change in insertion and detachment of lithium ions) to the electrode.
  • carbon nanotubes, carbon nanofibers, vapor-grown carbon fibers for example, “VGCF (registered trademark)” manufactured by Showa Denko KK
  • conductive carbon for example, “Denka Black (registered trademark)” Electric Chemical Industry Co., Ltd.
  • the amount of the conductive additive is preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the negative electrode material.
  • the solvent is not particularly limited, and N-methyl-2-pyrrolidone, dimethylformamide, isopropanol, water and the like can be used.
  • the binder which uses water as a solvent it is preferable to use a thickener together.
  • the amount of the solvent may be adjusted to have a viscosity such that the paste can be easily applied to the current collector.
  • Negative electrode sheet The negative electrode sheet which concerns on one Embodiment of this invention has a collector and the electrode layer which coat
  • a collector sheet-like things, such as nickel foil, copper foil, nickel mesh, or a copper mesh, are mentioned, for example.
  • the electrode layer contains a binder and the above-mentioned negative electrode material.
  • the electrode layer can be obtained, for example, by applying the above-mentioned paste on a current collector and drying it.
  • the application method of the paste is not particularly limited.
  • the thickness of the electrode layer is preferably 50 to 200 ⁇ m. If the electrode layer is too thick, it may not be possible to accommodate the negative electrode sheet in a standardized battery container. The thickness of the electrode layer can be adjusted by the amount of paste applied.
  • the electrode density of the negative electrode sheet can be calculated as follows. That is, the negative electrode sheet after pressing is punched into a circular shape having a diameter of 16 mm, and its mass and thickness are measured. The mass and thickness of the current collector foil (punched into a circular shape of 16 mm in diameter) separately measured therefrom are subtracted to obtain the mass and thickness of the electrode layer, and the electrode density is calculated based on the values.
  • a lithium ion secondary battery according to an embodiment of the present invention comprises at least one selected from the group consisting of a non-aqueous electrolytic solution and a non-aqueous polymer electrolyte, a positive electrode sheet and the negative electrode sheet.
  • a positive electrode sheet a sheet conventionally used in lithium ion secondary batteries, specifically, a sheet containing a positive electrode active material can be used.
  • the positive electrode active material include LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiNi 0.34 Mn 0.33 Co 0.33 O 2 , LiFePO 4 and the like.
  • the non-aqueous electrolytic solution and the non-aqueous polymer electrolyte used for the lithium ion secondary battery are not particularly limited.
  • lithium carbonates such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , CH 3 SO 3 Li, CF 3 SO 3 Li, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene Organic electrolytes dissolved in non-aqueous solvents such as carbonate, butylene carbonate, acetonitrile, propionitrile, dimethoxyethane, tetrahydrofuran, ⁇ -butyrolactone, etc. containing polyethylene oxide, polyacrylonitrile, polyfluorinated bilinidene, polymethyl methacrylate and the like Examples thereof include solid polymer electrolytes containing gel-like polymer electrolytes, polymers having ethylene oxide bonds, and the like.
  • a small amount of a substance that causes a decomposition reaction when charging a lithium ion secondary battery may be added to the electrolytic solution.
  • the substance include vinylene carbonate (VC), biphenyl, propane sultone (PS), fluoroethylene carbonate (FEC), ethylene sultone (ES) and the like.
  • VC vinylene carbonate
  • PS propane sultone
  • FEC fluoroethylene carbonate
  • ES ethylene sultone
  • the lithium ion secondary battery can be provided with a separator between the positive electrode sheet and the negative electrode sheet.
  • a separator for example, non-woven fabric mainly made of polyolefin such as polyethylene and polypropylene, cloth, microporous film, or a combination thereof can be mentioned.
  • Lithium-ion secondary batteries are used to power electronic devices such as mobile phones, personal computers and personal digital assistants; power sources for electric drills, electric vacuum cleaners and electric motors such as electric cars; fuel cells, solar power, wind power, etc. It can be used for storage of stored power.
  • the average particle diameter d AV of the primary particles of the particles (A1), the thickness of the amorphous carbon coating layer (A1C), and the (002) plane of the artificial graphite particles by X-ray diffraction method The average interplanar spacing d 002 , the thickness L C of the crystallite in the C-axis direction, the half value width of the (111) diffraction peak of the Si particle (A1), and the R value in the Raman spectrum It measures by the method described in "form". Moreover, the measurement of other physical properties and battery evaluation were performed as follows.
  • the resulting (004) intensity ratio becomes orientation index from the peak intensity I 110 between the peak intensity I 004 (110) plane of the surface was calculated I 110 / I 004.
  • the peak of each surface selected the thing of the largest intensity among the following ranges as each peak. (004) plane: 54.0 to 55.0 deg. (110) plane: 76.5 to 78.0 deg
  • Specific surface area Specific surface area / pore distribution measurement device (Quantam Chrome Instruments, NOVA 4200e), using nitrogen gas as a probe, BET specific surface area according to BET multipoint method with relative pressure of 0.1, 0.2, and 0.3 S BET (m 2 / g) was measured.
  • Carboxymethylcellulose (CMC; manufactured by Daicel, CMC 1300) was used as a binder. Specifically, an aqueous solution in which CMC powder having a solid content ratio of 2% was dissolved was obtained. Prepare carbon black, carbon nanotubes (CNT), and vapor grown carbon fiber (VGCF (registered trademark) -H, Showa Denko KK) as a conductive additive, and each is 3: 1: 1 (mass ratio) The mixture was used as a mixed conductive aid.
  • CMC carboxymethylcellulose
  • CMC 1300 Carboxymethylcellulose
  • the negative electrode paste was uniformly coated on a copper foil with a thickness of 20 ⁇ m using a doctor blade with a gap of 300 ⁇ m, dried on a hot plate, and then vacuum dried to obtain a negative electrode sheet.
  • the dried electrode was pressed by a uniaxial press at a pressure of 300 MPa to obtain a negative electrode sheet for battery evaluation.
  • the negative electrode sheet evaluates the amount of discharge per mass of active material in the half cell of the counter electrode Li in advance, and the negative electrode with respect to the capacity (Q C ) of the positive electrode sheet
  • the capacity of the negative electrode sheet was finely adjusted so that the ratio of the sheet capacity (Q A ) was a constant value of 1.2.
  • the electrolytic solution was prepared by mixing 1% by mass of vinylene carbonate (VC) and 10 parts of fluoroethylene carbonate (FEC) in a solvent in which ethylene carbonate, ethyl methyl carbonate and diethyl carbonate were mixed in a volume ratio of 3: 5: 2. mixed mass%, a further liquid electrolyte LiPF 6 was dissolved to a concentration of 1 mol / L to this.
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • Charging refers to applying a voltage to the cell
  • discharging refers to an operation that consumes the voltage of the cell.
  • the counter electrode is not Li metal, and a material having a higher redox potential than the negative electrode sheet is applied. Therefore, the negative electrode sheet is treated as a negative electrode. Therefore, in the bipolar laminate full cell, charging means an operation of inserting Li into the negative electrode sheet, and discharging means an operation of releasing Li from the negative electrode operation.
  • the discharge was carried out in CC mode up to 2.7 V with a current value of 0.1C.
  • the third cycle and the fourth cycle of the aging were under the same condition, and the current value in the second and the fifth cycle of the aging was replaced with 0.1 C to 0.2 C.
  • a charge / discharge cycle test was performed by the following method. The charging was performed to a voltage of 4.3 V in the CC mode with a current value of 1 C, and then switched to the discharge in the CV mode, and was performed with a cutoff current value of 0.05 C. Discharge was performed up to 3.0 V in CC mode with a current value of 1C.
  • This charge / discharge operation was performed as one cycle for 20 cycles, and at the 21st cycle, a low rate test was performed in which 1 C of the charge / discharge was replaced with 0.1 C. This 21 cycle test was repeated for a total of 500 cycles.
  • the first discharge capacity in this equation means the first cycle after the end of aging.
  • the bipolar laminate type full cell after discharge was recovered, and then disassembled in a glove box maintained in a dry argon gas atmosphere with a dew point of ⁇ 80 ° C. or less, and the negative electrode was taken out.
  • EMC ethyl methyl carbonate
  • the thickness of the electrode was measured using a dial gauge (manufactured by Mitutoyo Co., Ltd .; Code No. 547-401, scale 0.001 mm). The measurement locations were nine locations along the short side of the tab-attached side electrode, and the average value of the measured values was taken as the electrode thickness.
  • the electrode immediately after pressing was used as an electrode serving as a reference in determining the electrode expansion coefficient.
  • the electrode thickness here means the value which deducted the thickness of the copper foil collector altogether.
  • Si fine particles Silicon-containing particles
  • Table 1 Physical properties of Si particles and Si (1) to Si (3) used for the particles (A1) in Examples and Comparative Examples are shown in Table 1.
  • ⁇ is the true density (2.3 [g / cm 3 as theoretical value) of Si particles
  • S BET is the specific surface area [m 2 / g] measured by the BET method.
  • Pitch Petroleum pitch (softening point 220 ° C.) was used. It was 52 mass% when the residual carbon rate in 1100 degreeC was measured by thermal analysis under nitrogen gas distribution about this petroleum pitch. Further, the QI content of the petroleum pitch measured by the method described in JIS K2425 or a method according to the same was 0.62% by mass, and the TI content was 48.9% by mass.
  • Example 1 After petroleum-based coke is crushed by a bantam mill (manufactured by Hosokawa Micron Corporation), it is further crushed by a jet mill (manufactured by Seishin Enterprise Co., Ltd.) and heat-treated at 3000 ° C. in an Achison furnace to give a D V 50 of 7.5 ⁇ m. Artificial graphite particles (A2) -a having a BET specific surface area of 4.9 m 2 / g were obtained. Next, 16.4 parts by mass of the structure ( ⁇ ) -1 and 15.4 parts by mass of the petroleum pitch (as a mass after carbonizing the petroleum pitch), which is a precursor of the carbonaceous material (A3), are separated. It was charged into a bull flask.
  • Nitrogen gas was circulated to maintain an inert atmosphere, and the temperature was raised to 250 ° C.
  • the mixer was rotated at 500 rpm for agitation to uniformly mix the pitch and the silicon-containing particles. It was cooled and solidified to obtain a mixture.
  • 68.2 parts by mass of the above-mentioned artificial graphite particles which are particles (A2) -a are added to this mixture, charged into a rotary cutter mill, and mixed at a high speed of 25000 rpm and mixed while maintaining an inert atmosphere by flowing nitrogen gas. I did. This was put into a baking furnace, heated to 1100 ° C. at 150 ° C./h under nitrogen gas flow, and held at 1100 ° C.
  • a negative electrode sheet was produced using a mixture of 67.0 parts by mass of composite (A) -a, 16.5 parts by mass of graphite (1) and 16.5 parts by mass of graphite (2), and battery characteristics were measured. The results are shown in Table 3.
  • Comparative Example 1 A complex (A) -b was obtained in the same manner as in Example 1 except that the structure ( ⁇ ) -1 was changed to Si (2) in Table 1.
  • a negative electrode sheet was produced using a mixture of 67.0 parts by mass of the composite (A) -b, 16.5 parts by mass of graphite (1) and 16.5 parts by mass of graphite (2), and battery characteristics were measured. The results are shown in Table 3.
  • Comparative example 2 A complex (A) -c was obtained in the same manner as in Example 1 except that the structure ( ⁇ ) -1 was changed to Si (3) in Table 1.
  • a negative electrode sheet was produced using a mixture of 67.0 parts by mass of the composite (A) -c, 16.5 parts by mass of the graphite (1) and 16.5 parts by mass of the graphite (2), and battery characteristics were measured. The results are shown in Table 3.
  • the composite of Comparative Example 2 not only has a large Si (111) crystallite size but also the average particle diameter of Si particles. Also very big.
  • the average particle size of the Si particles is large, the amount of expansion per Si particle increases and at the same time the expanded portion is localized. As a result, the electrode mixture layer is largely destroyed.
  • the average particle diameter of the Si particles is small, the amount of expansion around the Si1 particles is reduced, and at the same time, the expansion superlocation is delocalized. As a result, breakage of the electrode mixture layer can be reduced. Accordingly, the electrode mixture layer expansion coefficient and capacity retention ratio of Comparative Example 2 are worse than those of Example 1 and Comparative Example 1.

Abstract

The present invention relates to a negative electrode material for a lithium ion secondary battery, the negative electrode material comprising: a composite (A) including Si particles (A1) having an average particle diameter dAV of primary particles of 5-95 nm; an amorphous carbon coating layer (A1C) having a thickness of 1 nm to 20 nm and covering the particles (A1); particles (A2) made of a material including graphite; and a carbonaceous material (A3), wherein the half-value width of the (111) plane diffraction peak of the Si particle (A1) in the composite (A) is 0.40 degrees or more as determined by powder X-ray diffraction measurement. The present invention also relates to a negative electrode sheet and a lithium ion secondary battery. In the negative electrode agent of the present invention, the crystallite size is decreased while reducing the size of the Si particles, thereby making it possible to obtain a lithium ion secondary battery having a small electrode expansion coefficient and a long battery life.

Description

リチウムイオン二次電池用負極材Negative electrode material for lithium ion secondary battery
　本発明はリチウムイオン二次電池用の負極材に関する。 The present invention relates to a negative electrode material for a lithium ion secondary battery.
　電子部品の省電力化を上回る速さで携帯電子機器の多機能化が進み、携帯電子機器の消費電力が増加している。そのため、携帯電子機器の主電源であるリチウムイオン二次電池の高容量化及び小型化が今まで以上に強く求められている。また、電気自動車の需要が伸び、それに使われるリチウムイオン二次電池にも高容量化が強く求められている。 The speed-up of the power saving of the electronic components has advanced the multifunctionalization of portable electronic devices, and the power consumption of the portable electronic devices is increasing. Therefore, there is a strong demand for higher capacity and smaller size of the lithium ion secondary battery, which is the main power source of portable electronic devices. In addition, demand for electric vehicles is increasing, and there is a strong demand for higher capacity in lithium ion secondary batteries used therein.
　このような要求に応えるために、珪素（Ｓｉ）粒子と炭素材料とを複合化した負極用材料が提案されている。しかし、Ｓｉ粒子と炭素材料の複合材料を用いたリチウムイオン二次電池は、高容量ではあるがＳｉ特有の充電放電時の体積変化により大きく劣化する。これに対応するため、Ｓｉのナノ粒子化、Ｓｉへのコート材の適用、Ｓｉへの異種金属ドープなど種々の対応がとられ、これら対応により高容量を維持しつつサイクル寿命は改善されつつある。 In order to meet such requirements, materials for negative electrodes in which silicon (Si) particles and a carbon material are combined have been proposed. However, a lithium ion secondary battery using a composite material of Si particles and a carbon material is greatly deteriorated due to a volume change at the time of charge and discharge peculiar to Si, although it has a high capacity. In order to cope with this, various measures such as forming of nano particles of Si, application of coating material to Si, doping of different metals to Si, etc. are taken, and cycle life is being improved while maintaining high capacity by these measures. .
　しかし、Ｓｉナノ粒子が小さくても結晶子サイズが大きいと、Ｓｉナノ粒子の膨張が異方的となるため、Ｓｉ含有負極電極全体の膨張率は増大してしまう。また、仮に膨張率を押さえる観点から適切なＳｉ結晶子サイズを有するＳｉ粒子を提案できても、十分な導電性が得られなければ、また電解液との副反応を抑制するコート材がなければ長期寿命を有する電池は実現できない。 However, even when the size of the Si nanoparticles is small, if the crystallite size is large, the expansion of the Si nanoparticles becomes anisotropic, and the expansion coefficient of the entire Si-containing negative electrode increases. Moreover, even if it is possible to propose Si particles having an appropriate Si crystallite size from the viewpoint of suppressing the expansion coefficient, if sufficient conductivity can not be obtained, and if there is no coating material that suppresses side reactions with the electrolyte. Batteries with long life can not be realized.
　そこで、Ｓｉ粒子の結晶子サイズを小さくする試みがいくつかなされている。例えば、特許文献１は、放電時にリチウムイオンの移動が伴う蓄電デバイス用Ｓｉ系合金からなる負極材料であって、前記Ｓｉ系合金からなる負極材料がＳｉからなるＳｉ主要相とＳｉとＳｉ以外の一種以上の元素からなる化合物相とを有し、前記化合物相がＳｉとＣｕからなる相を含んでなる相を有し、前記Ｓｉ主要相のＳｉ結晶子サイズが３０ｎｍ以下であり、かつＳｉとＣｕからなる化合物相の結晶子サイズが４０ｎｍ以下である蓄電デバイス用Ｓｉ系合金からなる負極材料を開示している。 Therefore, several attempts have been made to reduce the crystallite size of Si particles. For example, Patent Document 1 is a negative electrode material made of a Si-based alloy for a storage device accompanied by migration of lithium ions during discharge, and the negative electrode material made of the Si-based alloy is Si main phase and other than Si and Si. A compound phase comprising one or more elements, the compound phase comprising a phase comprising a phase comprising Si and Cu, the Si crystallite size of the Si main phase being 30 nm or less, and Si and The negative electrode material which consists of Si type alloys for electrical storage devices whose crystallite size of the compound phase which consists of Cu is 40 nm or less is disclosed.
　また、特許文献２は、主としてリチウムイオン二次電池用の負極活物質として使用するシリコンであって、粉末エックス線回折による結晶子サイズが１～２００ｎｍであり、レーザー法による平均粒径が０．１～５μｍであり、さらにＢＥＴ法による比表面積が１０ｍ2／ｇ以上であるシリコン微細粒子を開示している。 Patent Document 2 is silicon mainly used as a negative electrode active material for a lithium ion secondary battery, and has a crystallite size of 1 to 200 nm by powder X-ray diffraction, and an average particle diameter of 0.1 by a laser method. It discloses silicon fine particles having a specific surface area of up to 5 μm and a BET surface area of at least 10 m 2 / g.
特開第２０１４－１６０５５４号公報JP, 2014-160554, A 特開第２０１６－１５２９９号公報JP, 2016-15299, A
　特許文献１の発明は結晶性サイズの低減を図っているものの、どの面の結晶面に注目しているかが不明であり、またＳｉ粒径については記載されていない。
　特許文献２の発明は特許文献１に比べると許容できるＳｉ結晶子サイズが大きすぎ、膨張抑制につながらない可能性がある。また、Ｓｉの結晶子サイズが特許文献１と同じ３０ｎｍ以下であるとしても、Ｓｉ単体で負極材を形成している点や、Ｓｉ粒径が０．１μｍ以上である点は、負極の膨張抑制、電池寿命改善の手法としては不利である。
　本発明の課題は、使用に伴う電極の膨張が小さく、寿命が長いリチウムイオン二次電池のための負極材を提供することにある。 Although the invention of Patent Document 1 attempts to reduce the crystalline size, it is unclear which crystal plane is focused on, and the Si particle size is not described.
The invention of Patent Document 2 has an allowable Si crystallite size too large compared to Patent Document 1, and may not lead to expansion suppression. In addition, even if the crystallite size of Si is 30 nm or less as in Patent Document 1, the expansion suppression of the negative electrode is the point that the negative electrode material is formed of Si alone or the Si particle diameter is 0.1 μm or more. , It is disadvantageous as a method of battery life improvement.
An object of the present invention is to provide a negative electrode material for a lithium ion secondary battery, which has a small expansion of the electrode with use and a long life.
　本発明は、以下の態様を包含する。
［１］一次粒子の平均粒子径ｄAVが５ｎｍ以上９５ｎｍ以下であるＳｉ粒子（Ａ１）と、粒子（Ａ１）を被覆する厚さ１ｎｍ以上２０ｎｍ以下の非晶質炭素被覆層（Ａ１Ｃ）と、黒鉛を含む物質からなる粒子（Ａ２）と、炭素質材料（Ａ３）とを含む複合体（Ａ）を含むリチウムイオン二次電池用負極材であって、前記複合体（Ａ）は粉末Ｘ線回折測定による前記Ｓｉ粒子（Ａ１）の（１１１）面回折ピークの半値幅が０．４０度以上であることを特徴とするリチウムイオン二次電池用負極材。
［２］前記粒子（Ａ２）は、体積基準累積粒度分布における５０％粒子径ＤV50が２．０μｍ以上２０．０μｍ以下であり、ＢＥＴ比表面積（ＳBET）が１．０ｍ2／ｇ以上１０．０ｍ2／ｇ以下である前項１に記載のリチウムイオン二次電池用負極材。
［３］前記粒子（Ａ２）は、粉末Ｘ線回折法による黒鉛結晶の（１１０）面のピーク強度Ｉ110と（００４）面のピーク強度Ｉ004の比Ｉ110／Ｉ004が０．１０以上０．３５以下であり、粉末Ｘ線回折法による（００２）面の平均面間隔ｄ002が０．３３６０ｎｍ以下であり、窒素ガス吸着法によって測定される直径０．４μｍ以下の細孔の全細孔容積が５．０μＬ／ｇ以上４０．０μＬ／ｇ以下である前項１または２に記載のリチウムイオン二次電池用負極材。
［４］前記複合体（Ａ）中の前記Ｓｉ粒子（Ａ１）の含有率が１０質量％以上７０質量％以下である前項１～３のいずれか１項に記載のリチウムイオン二次電池用負極材。
［５］シート状集電体及び集電体を被覆する負極層を有し、前記負極層はバインダー、導電助剤及び前項１～４のいずれか１項に記載のリチウムイオン二次電池用負極材を含む負極シート。
［６］前項５に記載の負極シートを有するリチウムイオン二次電池。 The present invention includes the following aspects.
[1] Si particles (A1) having an average particle diameter d AV of 5 nm or more and 95 nm or less, an amorphous carbon coating layer (A1 C) with a thickness of 1 nm or more and 20 nm or less, which covers the particles (A1); A negative electrode material for a lithium ion secondary battery comprising a composite (A) comprising particles (A2) comprising a material containing graphite and a carbonaceous material (A3), wherein the composite (A) is a powder X-ray The negative electrode material for a lithium ion secondary battery, wherein a half value width of a (111) plane diffraction peak of the Si particles (A1) by diffraction measurement is 0.40 degrees or more.
[2] The particles (A2) have a 50% particle diameter DV50 in the volume-based cumulative particle size distribution of 2.0 μm to 20.0 μm, and a BET specific surface area (S BET ) of 1.0 m 2 / g to 10 The negative electrode material for a lithium ion secondary battery as recited in the aforementioned Item 1, which has a particle size of not more than 0 m 2 / g.
[3] In the particles (A2), the ratio I 110 / I 004 of the peak intensity I 110 of the ( 110 ) plane to the peak intensity I 004 of the (004) plane by powder X-ray diffraction method is 0.10 or more 0.35 or less, the average interplanar spacing d 002 of the (002) plane by powder X-ray diffraction is 0.3360 nm or less, and the total fineness of pores with a diameter of 0.4 μm or less measured by nitrogen gas adsorption The negative electrode material for a lithium ion secondary battery according to the above 1 or 2, wherein the pore volume is 5.0 μL / g or more and 40.0 μL / g or less.
[4] The negative electrode for a lithium ion secondary battery according to any one of the aforementioned Items 1 to 3, wherein the content of the Si particles (A1) in the composite (A) is 10% by mass to 70% by mass. Material.
[5] A sheet-like current collector and a negative electrode layer for covering the current collector, the negative electrode layer comprising a binder, a conductive additive and the negative electrode for lithium ion secondary battery according to any one of the above 1 to 4 Material containing negative electrode sheet.
[6] A lithium ion secondary battery having the negative electrode sheet described in the preceding item 5.
　本発明により、使用に伴う電極の膨張率が小さく、電池寿命が長いリチウムイオン二次電池のための用負極材を提供することができる。 According to the present invention, it is possible to provide a negative electrode material for a lithium ion secondary battery having a small expansion coefficient of the electrode and long battery life.
　本発明の一実施形態に係るリチウムイオン二次電池用負極材は、粒子（Ａ１）と非晶質炭素被覆層（Ａ１Ｃ）と粒子（Ａ２）と炭素質材料（Ａ３）とを含む複合体（Ａ）を含む。 A negative electrode material for a lithium ion secondary battery according to an embodiment of the present invention is a composite (particles (A1), an amorphous carbon coating layer (A1C), particles (A2), and a carbonaceous material (A3) A) is included.
（１）粒子（Ａ１）
　本発明の一実施形態に用いられる粒子（Ａ１）は、リチウムイオンを吸蔵・放出可能なＳｉを主成分とする。Ｓｉの含有率は好ましくは９０質量％以上であり、より好ましくは９５質量％以上である。粒子（Ａ１）はＳｉ単体またはＳｉ元素を含む化合物、混合体、共融体または固溶体からなるものでもよい。また、粒子（Ａ２）及び炭素質材料（Ａ３）との複合化前の粒子（Ａ１）は複数の微粒子が凝集したもの、すなわち二次粒子化したものでもよい。粒子（Ａ１）の形状としては、塊状、鱗片状、球状、繊維状などを挙げることができる。これらのうち、球状または塊状が好ましい。 (1) Particle (A1)
The particles (A1) used in one embodiment of the present invention contain Si as a main component capable of inserting and extracting lithium ions. The content of Si is preferably 90% by mass or more, more preferably 95% by mass or more. The particles (A1) may be composed of a simple substance of Si or a compound containing a Si element, a mixture, a eutectic or a solid solution. In addition, the particles (A1) before being complexed with the particles (A2) and the carbonaceous material (A3) may be aggregations of a plurality of fine particles, that is, secondary particles. As a shape of particle | grains (A1), a lump shape, scale shape, spherical shape, fibrous shape etc. can be mentioned. Among these, spherical or massive is preferable.
　Ｓｉ元素を含む物質としては、Ｓｉ単体またはＳｉとＬｉ以外の元素Ｍとを含む一般式：Ｍ（＝Ｍa＋Ｍb＋Ｍc＋Ｍd・・・）mＳｉで表される物質を挙げることができる。該物質はＳｉ１モルに対してｍモルとなる比で元素Ｍを含む化合物、混合体、共融体または固溶体である。
　Ｌｉ以外の元素である元素Ｍの具体例としては、Ｂ、Ｃ、Ｎ、Ｏ、Ｓ、Ｐ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｍｏ、Ｒｕ、Ｒｈ、Ｐｄ、Ｐｔ、Ｂｅ、Ｎｂ、Ｎｄ、Ｃｅ、Ｗ、Ｔａ、Ａｇ、Ａｕ、Ｃｄ、Ｇａ、Ｉｎ、Ｓｂ、Ｂａなどを挙げることができる。式中、ｍは好ましくは０．０１以上、より好ましくは０．１０以上、さらに好ましくは０．３０以上である。 The material containing Si element, the general formula and a element M other than Si alone or Si and Li: be mentioned M (= M a + M b + M c + M d ···) material represented by m Si it can. The substance is a compound, a mixture, a eutectic or a solid solution containing the element M in a ratio of m moles to 1 mole of Si.
Specific examples of the element M which is an element other than Li include B, C, N, O, S, P, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Pt, Be, Nb, Nd, Ce, W, Ta, Ag, Au, Cd, Ga, In, Sb, Ba and the like can be mentioned. In the formula, m is preferably 0.01 or more, more preferably 0.10 or more, and still more preferably 0.30 or more.
　Ｓｉ元素を含む物質の具体例としては、Ｓｉ単体、Ｓｉとアルカリ土類金属との合金；Ｓｉと遷移金属との合金；Ｓｉと半金属との合金；Ｓｉと、Ｂｅ、Ａｇ、Ａｌ、Ａｕ、Ｃｄ、Ｇａ、Ｉｎ、ＳｂまたはＺｎとの固溶性合金または共融性合金；ＣａＳｉ、ＣａＳｉ2、Ｍｇ2Ｓｉ、ＢａＳｉ2、Ｃｕ5Ｓｉ、ＦｅＳｉ、ＦｅＳｉ2、ＣｏＳｉ2、Ｎｉ2Ｓｉ、ＮｉＳｉ2、ＭｎＳｉ、ＭｎＳｉ2、ＭｏＳｉ2、ＣｒＳｉ2、Ｃｒ3Ｓｉ、ＴｉＳｉ2、Ｔｉ5Ｓｉ3、ＮｂＳｉ2、ＮｄＳｉ2、ＣｅＳｉ2、ＷＳｉ2、Ｗ5Ｓｉ3、ＴａＳｉ2、Ｔａ5Ｓｉ3、ＰｔＳｉ、Ｖ3Ｓｉ、ＶＳｉ2、ＰｄＳｉ、ＲｕＳｉ、ＲｈＳｉなどのケイ化物；ＳｉＯ2、ＳｉＣ、Ｓｉ3Ｎ4などを挙げることができる。 Specific examples of the substance containing Si element include elemental Si, an alloy of Si and an alkaline earth metal; an alloy of Si and a transition metal; an alloy of Si and a semimetal; Si, Be, Ag, Al, Au , Cd, Ga, in, solid-solution alloys or KyoTorusei alloy of Sb or Zn; CaSi, CaSi 2, Mg 2 Si, BaSi 2, Cu 5 Si, FeSi, FeSi 2, CoSi 2, Ni 2 Si, NiSi 2, MnSi, MnSi 2, MoSi 2, CrSi 2, Cr 3 Si, TiSi 2, Ti 5 Si 3, NbSi 2, NdSi 2, CeSi 2, WSi 2, W 5 Si 3, TaSi 2, Ta 5 Si 3, It may be mentioned SiO 2, SiC, Si 3 N 4 and the like; PtSi, V 3 Si, VSi 2, PdSi, RuSi, silicides such RhSi.
　粒子（Ａ１）は、一次粒子の平均粒子径ｄAVの下限値が５ｎｍであり、好ましくは１０ｎｍ、より好ましくは３５ｎｍである。また、一次粒子のｄAVの上限値は９５ｎｍであり、好ましくは７０ｎｍである。粒子（Ａ１）の一次粒子のｄAVが９５ｎｍより大きくなると、充放電により粒子（Ａ１）が体積膨張収縮して粒子（Ａ１）を含む複合体（Ａ）の構造に与える影響が大きくなり、容量維持率が低下する。また、一次粒子のｄAVが５ｎｍより小さくなると、粒子（Ａ１）の比表面積が増え、副反応量が増大する。
　平均粒子径ｄAV［ｎｍ］は、
　　ｄAV［ｎｍ］＝６×１０3／（ρ×ＳBET）
により定義される。ここでρ［ｇ／ｃｍ3］はＳｉ粒子の真密度であり、理論値の２．３［ｇ／ｃｍ3］を採用した。ＳBET［ｍ2／ｇ］はＮ2ガスを吸着ガスとするＢＥＴ法により測定した比表面積である。 The lower limit of the average particle diameter d AV of the primary particles of the particles (A1) is 5 nm, preferably 10 nm, and more preferably 35 nm. Further, the upper limit value of d AV of the primary particles is 95 nm, preferably 70 nm. When the d AV of the primary particles of the particles (A1) is larger than 95 nm, the particles (A1) expand and shrink in volume due to charge and discharge and the influence on the structure of the composite (A) containing the particles (A1) increases. Maintenance rate decreases. When the d AV of the primary particles is smaller than 5 nm, the specific surface area of the particles (A1) is increased, and the amount of side reaction is increased.
Average particle diameter d AV [nm] is
d AV [nm] = 6 x 10 3 / (ρ x S BET )
Defined by Here, [[g / cm 3 ] is the true density of Si particles, and the theoretical value of 2.3 [g / cm 3 ] was adopted. S BET [m 2 / g] is a specific surface area measured by the BET method using N 2 gas as an adsorption gas.
　粒子（Ａ１）は、その表面が薄い非晶質炭素被覆層（Ａ１Ｃ）により被覆されている。非晶質炭素被覆層（Ａ１Ｃ）の厚さの上限値は２０ｎｍであり、好ましくは１０ｎｍ、より好ましくは５ｎｍである。電解液と非晶質炭素被覆層（Ａ１Ｃ）との副反応を抑制するためである。非晶質炭素被覆層（Ａ１Ｃ）の厚さの下限値は１ｎｍであり、好ましくは２ｎｍであり、より好ましくは３ｎｍである。粒子（Ａ１）の酸化と粒子（Ａ１）同士の凝集が抑制されるためである。また、非晶質炭素被覆層（Ａ１Ｃ）よりも電解液との副反応が多く進行する粒子（Ａ１）が、非晶質炭素被覆層（Ａ１Ｃ）により被覆されているので、初期クーロン効率が大幅に向上する。 The particles (A1) are coated on their surface with a thin amorphous carbon coating layer (A1C). The upper limit of the thickness of the amorphous carbon coating layer (A1C) is 20 nm, preferably 10 nm, more preferably 5 nm. This is to suppress the side reaction between the electrolytic solution and the amorphous carbon coating layer (A1C). The lower limit of the thickness of the amorphous carbon coating layer (A1C) is 1 nm, preferably 2 nm, and more preferably 3 nm. This is because the oxidation of the particles (A1) and the aggregation of the particles (A1) are suppressed. In addition, since the particles (A1) in which side reactions with the electrolytic solution proceed more frequently than the amorphous carbon coating layer (A1C) are coated with the amorphous carbon coating layer (A1C), the initial coulombic efficiency is significantly increased. Improve.
　非晶質炭素被覆層（Ａ１Ｃ）の厚さは透過型電子顕微鏡（ＴＥＭ）による観察で撮影した画像において膜厚を計測することにより求めることができる。具体的なＴＥＭによる観察の一例を以下に示す。
　装置：日立製作所製　Ｈ９５００、
　加速電圧：３００ｋＶ。
　サンプル作製：エタノール中に試料を少量採取し超音波照射により分散させた後、マイクログリッド観察用メッシュ（支持膜無し）に載せて観察用試料とする。
　観察倍率：５万倍（粒子形状観察時）及び４０万倍（非晶質炭素層の厚さ観察時） The thickness of the amorphous carbon coating layer (A1C) can be determined by measuring the film thickness in an image taken by observation with a transmission electron microscope (TEM). An example of a specific TEM observation is shown below.
Device: H9500 manufactured by Hitachi, Ltd.
Acceleration voltage: 300 kV.
Preparation of sample: A small amount of sample is taken in ethanol and dispersed by ultrasonic irradiation, and then placed on a microgrid observation mesh (without a supporting film) to make an observation sample.
Observation magnification: 50,000 times (at the time of particle shape observation) and 400,000 times (at the time of thickness observation of an amorphous carbon layer)
　粒子（Ａ１）とこれを覆う非晶質炭素被覆層（Ａ１Ｃ）からなるコア・シェル構造体（以降、構造体（α）と呼ぶ。）は、ＢＥＴ比表面積が好ましくは２５ｍ2／ｇ以上７０ｍ2／ｇ以下、より好ましくは５２ｍ2／ｇ以上６７ｍ2／ｇ以下である。また、一次粒子の密度は２．２ｇ／ｃｍ3以上である。構造体（α）のＢＥＴ比表面積（ＳBET）が２５ｍ2／ｇ以上であると、構造体（α）の粒径が大きくなりすぎず、構造体（α）固体内の電子移動経路とＬｉイオン拡散経路が長くなることはない。つまり、充放電時の抵抗が低く保たれる。さらに、構造体（α）１粒子あたりの膨張量の絶対値も大きくならず、構造体（α）周囲の複合体（Ａ）の構造が破壊される可能性は低い。また、構造体（α）の密度が２．２ｇ／ｃｍ3以上であれば、体積エネルギー密度の点からも優位性がある。 The core-shell structure (hereinafter referred to as a structure (α)) comprising particles (A1) and an amorphous carbon coating layer (A1C) covering the particles preferably has a BET specific surface area of 25 m 2 / g to 70 m. It is 2 / g or less, more preferably 52 m 2 / g or more and 67 m 2 / g or less. Moreover, the density of primary particles is 2.2 g / cm 3 or more. When the BET specific surface area (S BET ) of the structure (α) is 25 m 2 / g or more, the particle diameter of the structure (α) does not become too large, and the electron transfer path in the solid of the structure (α) and Li The ion diffusion path will not be long. That is, the resistance at the time of charge and discharge is kept low. Furthermore, the absolute value of the amount of expansion per particle of the structure (α) does not increase, and the possibility of destruction of the structure of the complex (A) around the structure (α) is low. In addition, when the density of the structure (α) is 2.2 g / cm 3 or more, it is also advantageous in terms of volumetric energy density.
　複合体（Ａ）中の粒子（Ａ１）の含有率は、好ましくは２質量％以上９５質量％以下、より好ましくは５質量％以上８０質量％以下、さらに好ましくは１０質量％以上７０質量％以下である。粒子（Ａ１）の含有率が９５質量％以下の場合は、電気抵抗が大きくなることによる電池性能上の問題は発生しない。粒子（Ａ１）の含有率が２質量％以上の場合は、体積または質量エネルギー密度の点で優位性が保たれる。 The content of particles (A1) in the composite (A) is preferably 2% by mass to 95% by mass, more preferably 5% by mass to 80% by mass, and still more preferably 10% by mass to 70% by mass It is. When the content of the particles (A1) is 95% by mass or less, no problem occurs in the battery performance due to the increase in the electrical resistance. When the content of the particles (A1) is 2% by mass or more, the superiority in terms of volume or mass energy density is maintained.
　粒子（Ａ１）と非晶質炭素被覆層（Ａ１Ｃ）からなる構造体（α）は固相法、液相法、気相法のいずれでも作製可能であるが、気相法が好ましい。特にモノシランのような気相Ｓｉ原料からＣＶＤ法でＳｉ粒子を作製し、その後アセチレンやエチレンの様な炭素原料を用いてＣＶＤ法で均一な非晶質炭素被覆層（Ａ１Ｃ）を作製する方法などが好ましい。 The structure (α) composed of the particles (A1) and the amorphous carbon coating layer (A1C) can be produced by any of the solid phase method, liquid phase method and gas phase method, but the gas phase method is preferable. In particular, a method of producing Si particles from a vapor phase Si raw material such as monosilane by the CVD method, and thereafter producing a uniform amorphous carbon covering layer (A1C) by the CVD method using a carbon raw material such as acetylene or ethylene Is preferred.
（２）粒子（Ａ２）
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる黒鉛粒子は人造黒鉛粒子であることが好ましい。光学組織の大きさ及び形状が特定の範囲にあり、適切な黒鉛化度を有する人造黒鉛粒子により、つぶれ特性と電池特性がともに優れた電極材料を得ることができる。 (2) Particles (A2)
The graphite particles contained in the particles (A2) in the preferred embodiment of the present invention are preferably artificial graphite particles. The size and shape of the optical structure are in a specific range, and an artificial graphite particle having an appropriate degree of graphitization can provide an electrode material having both excellent crushing characteristics and battery characteristics.
　本明細書においてＤV50とはレーザー回折式粒度分布計により測定される体積基準粒度分布における５０％粒子径を表し、粒子の外見上の径を示す。 In the present specification, D V 50 represents a 50% particle size in a volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer, and represents an apparent diameter of particles.
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる黒鉛粒子の体積基準累積粒度分布における５０％粒子径ＤV50は、好ましくは２．０μｍ以上２０．０μｍ以下、より好ましくは５．０μｍ以上１８．０μｍ以下である。ＤV50が２．０μｍ以上であれば、粉砕時に特殊な機器により粉砕する必要がなく、エネルギーも節約できる。また、凝集が起こりにくいため、塗工時のハンドリング性もよい。さらに、比表面積が過度に大きくなることがないため、初期充放電効率の低下も起こらない。一方、ＤV50が２０．０μｍ以下であれば、負極材中のリチウム拡散にも時間がかからないため、入出力特性が良好である。また、黒鉛粒子の表面にケイ素含有粒子が均一に複合化することから、良好なサイクル特性が得られる。 The 50% particle diameter D V50 in the volume-based cumulative particle size distribution of the graphite particles contained in the particles (A2) in the preferred embodiment of the present invention is preferably 2.0 μm or more and 20.0 μm or less, more preferably 5.0 μm or more 18 .0 μm or less. If the D V 50 is 2.0 μm or more, it is not necessary to grind with a special device at the time of grinding, and energy can be saved. Moreover, since it is hard to cause aggregation, the handling property at the time of coating is also good. Furthermore, since the specific surface area does not become excessively large, the decrease in the initial charge and discharge efficiency does not occur. On the other hand, if D V 50 is 20.0 μm or less, it does not take time to diffuse lithium in the negative electrode material, and hence the input / output characteristics are good. Further, since silicon-containing particles are uniformly compounded on the surface of the graphite particles, good cycle characteristics can be obtained.
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる黒鉛粒子は、Ｎ2ガス吸着法によるＢＥＴ比表面積が１．０ｍ2／ｇ以上１０．０ｍ2／ｇ以下が好ましく、３．０ｍ2／ｇ以上７．５ｍ2／ｇ以下がより好ましい。黒鉛粒子のＢＥＴ比表面積が上記の範囲にあると、負極材として不可逆な副反応を抑制しつつ電解液と接触する面積を大きく確保できるため、入出力特性が向上する。 Graphite particles contained in the particle (A2) in a preferred embodiment of the present invention, BET specific surface area of preferably 1.0 m 2 / g or more 10.0 m 2 / g or less by N 2 gas adsorption method, 3.0 m 2 / g or more and 7.5 m 2 / g or less is more preferable. When the BET specific surface area of the graphite particles is in the above range, a large area in contact with the electrolytic solution can be secured while suppressing an irreversible side reaction as a negative electrode material, so that the input / output characteristics are improved.
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる人造黒鉛粒子は、粉末Ｘ線回折法により得られる回折ピークプロファイルにおいて黒鉛結晶の（１１０）面のピーク強度Ｉ110と（００４）面のピーク強度Ｉ004の比Ｉ110／Ｉ004が０．１０以上０．３５以下であることが好ましい。前記の比は、より好ましくは０．１８以上０．３０以下であり、より一層好ましくは０．２１以上０．３０以下である。前記の比が０．１０以上であれば配向性が高過ぎず、負極材中のＳｉや黒鉛へのリチウムイオンの挿入・脱離（吸蔵・放出）に伴う膨張収縮により、電極の集電体面に対して垂直方向への電極膨張が起こることがなく、良好なサイクル寿命が得られる。また黒鉛の炭素網面が電極面と平行にならないためＬｉの挿入が起こり易く、良好な急速充放電特性が得られる。前記の比が０．３５以下であれば配向性が低すぎず、その負極材を用いた電極作製時のプレスを行う際に電極密度が上がり易くなる。 The artificial graphite particles contained in the particles (A2) in the preferred embodiment of the present invention have peak intensities I 110 of the (110) plane of the graphite crystal and peaks of the (004) plane in the diffraction peak profile obtained by powder X-ray diffraction. it preferably has a specific I 110 / I 004 intensity I 004 is 0.10 or more 0.35 or less. The ratio is more preferably 0.18 or more and 0.30 or less, and still more preferably 0.21 or more and 0.30 or less. If the ratio is 0.10 or more, the orientation is not too high, and the current collector surface of the electrode is due to expansion and contraction associated with insertion and desorption (occluding and releasing) of lithium ions to Si and graphite in the negative electrode material. There is no electrode expansion in the direction perpendicular to the above, and a good cycle life can be obtained. Further, since the carbon net plane of graphite is not parallel to the electrode plane, Li insertion is likely to occur, and good rapid charge / discharge characteristics can be obtained. If the ratio is 0.35 or less, the orientation is not too low, and the electrode density tends to increase when pressing is performed at the time of electrode preparation using the negative electrode material.
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる人造黒鉛粒子は、粉末Ｘ線回折法による（００２）面の平均面間隔ｄ002が０．３３６０ｎｍ以下であることが好ましい。これにより負極材中の人造黒鉛粒子自身も質量あたりのリチウム挿入、脱離量が多く、すなわち負極材としても質量エネルギー密度が高くなる。また、負極材としてのＳｉへのリチウム挿入、脱離に伴う膨張収縮を緩和しやすくなりサイクル寿命が良くなる。
　人造黒鉛粒子の結晶子のＣ軸方向の厚みＬｃとしては５０ｎｍ以上１０００ｎｍ以下が、質量エネルギー密度やつぶれ性の観点から好ましい。 In the artificial graphite particles contained in the particles (A2) in a preferred embodiment of the present invention, the average interplanar spacing d 002 of the (002) plane according to powder X-ray diffraction method is preferably 0.3360 nm or less. As a result, the amount of lithium insertion and desorption per mass of the artificial graphite particles in the negative electrode material itself is large, that is, the mass energy density also increases as the negative electrode material. In addition, expansion and contraction due to lithium insertion and removal from Si as a negative electrode material can be easily alleviated, and the cycle life is improved.
The thickness Lc in the C-axis direction of the crystallite of the artificial graphite particle is preferably 50 nm or more and 1000 nm or less from the viewpoint of mass energy density and crushability.
　本明細書において、ｄ002及びＬｃは、既知の方法により粉末Ｘ線回折（ＸＲＤ）法を用いて測定することができる（稲垣道夫、「炭素」、１９６３、Ｎｏ．３６、２５－３４頁；Ｉｗａｓｈｉｔａ　ｅｔ　ａｌ．，Ｃａｒｂｏｎ　ｖｏｌ．４２（２００４），ｐ．７０１－７１４）。 In the present specification, d 002 and Lc can be measured by powder X-ray diffraction (XRD) according to a known method (Michio Inagaki, “carbon”, 1963, No. 36, pages 25-34; Iwashita et al., Carbon vol. 42 (2004), p. 701-714).
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる人造黒鉛粒子は、液体窒素冷却下における窒素ガス吸着ＢＥＴ法による直径０．４μｍ以下の細孔の全細孔容積が５．０μＬ／ｇ以上４０．０μＬ／ｇ以下であることが好ましい。さらに好ましくは２５．０μＬ／ｇ以上４０．０μＬ／ｇ以下である。全細孔容積が５．０μＬ／ｇ以上の人造黒鉛粒子は粒子（Ａ１）と炭素質材料（Ａ３）との複合化がされやすく、サイクル容量維持率の改善の点で好ましい。Ｘ線回折法で測定されるＬｃが１００ｎｍ以上の炭素材料において、前記全細孔容積が４０．０μＬ／ｇ以下であると、充放電時の黒鉛層の異方的な膨張収縮に起因する構造の不可逆変化が起こりにくく、負極材としてのサイクル特性もさらに向上する。また、人造黒鉛粒子の全細孔容積がこの範囲のとき、その負極材を活物質として用いた際に電解液が浸透しやすくなるので急速充放電特性の点でも好ましい。 The artificial graphite particles contained in the particles (A2) in the preferred embodiment of the present invention have a total pore volume of 5.0 μL / g or more of pores with a diameter of 0.4 μm or less according to nitrogen gas adsorption BET method under liquid nitrogen cooling. It is preferably 40.0 μL / g or less. More preferably, it is 25.0 μL / g or more and 40.0 μL / g or less. An artificial graphite particle having a total pore volume of 5.0 μL / g or more tends to be complexed with the particle (A1) and the carbonaceous material (A3), and is preferable in terms of improvement of the cycle capacity retention rate. In a carbon material having Lc of 100 nm or more measured by X-ray diffraction method, when the total pore volume is 40.0 μL / g or less, a structure caused by anisotropic expansion and contraction of a graphite layer during charge and discharge Irreversible change is unlikely to occur, and the cycle characteristics of the negative electrode material are further improved. In addition, when the total pore volume of the artificial graphite particles is in this range, the electrolyte easily penetrates when the negative electrode material is used as an active material, which is preferable in view of rapid charge / discharge characteristics.
　本発明の好ましい実施態様における粒子（Ａ２）に含まれる人造黒鉛粒子は、ラマン分光スペクトルで測定される１３００～１４００ｃｍ-1の範囲にある非晶質成分由来のピークの強度ＩDと１５８０～１６２０ｃｍ-1の範囲にある黒鉛成分由来のピークの強度ＩGとの比ＩD／ＩG（Ｒ値）が０．０４以上０．１８以下であることが好ましく、０．０８以上０．１６以下であることがさらに好ましい。Ｒ値が０．０４以上であれば黒鉛の結晶性が高過ぎず、良好な急速充放電特性が得られる。Ｒ値が０．１８以下であれば欠陥の存在により充放電時に副反応が生じることなく、良好なサイクル特性が得られる。
　ラマンスペクトルは、例えばレーザラマン分光光度計（日本分光株式会社製、ＮＲＳ－５１００）を用いて、付属の顕微鏡で観察することによって測定することができる。 The artificial graphite particles contained in the particles (A2) in a preferred embodiment of the present invention have a peak intensity I D of 1580 to 1620 cm of the peak derived from the amorphous component in the range of 1300 to 1400 cm.sup.- 1 measured by Raman spectroscopy. The ratio I D / I G (R value) to the intensity I G of the peak derived from the graphite component in the range of -1 is preferably 0.04 or more and 0.18 or less, preferably 0.08 or more and 0.16 or less It is further preferred that If the R value is 0.04 or more, the crystallinity of graphite is not too high, and good rapid charge / discharge characteristics can be obtained. If the R value is 0.18 or less, good cycle characteristics can be obtained without the occurrence of side reactions during charge and discharge due to the presence of defects.
The Raman spectrum can be measured, for example, by observing with a microscope attached using a laser Raman spectrophotometer (NRS-5100 manufactured by JASCO Corporation).
（３）粒子（Ａ２）の製造方法
　本発明の一実施形態に係る粒子（Ａ２）に含まれる黒鉛粒子は、熱履歴が１０００℃以下のコークスを粉砕した粒子を加熱することにより製造することができる。
　コークスの原料としては、例えば、石油ピッチ、石炭ピッチ、石炭ピッチコークス、石油コークス及びこれらの混合物を用いることができる。すなわち、粒子（Ａ２）に含まれる黒鉛粒子としては、石油系コークス及び／または石炭系コークス由来の物質を用いることが好ましい。これらの中でも、特定の条件下でディレイドコーキングを行ったものが望ましい。 (3) Method of Producing Particles (A2) The graphite particles contained in the particles (A2) according to one embodiment of the present invention may be produced by heating particles obtained by crushing coke having a heat history of 1000 ° C. or less. it can.
As a raw material of coke, for example, petroleum pitch, coal pitch, coal pitch coke, petroleum coke and mixtures thereof can be used. That is, as the graphite particles contained in the particles (A2), it is preferable to use a material derived from petroleum-based coke and / or coal-based coke. Among these, those subjected to delayed coking under specific conditions are desirable.
　ディレイドコーカーに通す原料としては、原油精製時の重質溜分に対して、流動床接触分解を行った後に触媒を除去したデカントオイルや、瀝青炭等から抽出されたコールタールを２００℃以上の温度で蒸留し、得られたタールを１００℃以上に昇温することによって十分に流動性を持たせたものが挙げられる。ディレイドコーキングプロセス中、少なくともドラム内入り口においては、これらの液体が４５０℃以上、さらには５００℃、よりさらには５１０℃以上に昇温されていることが好ましく、それにより後工程での熱処理時に残炭率が高くなり、収率が向上する。また、ドラム内での圧力は好ましくは常圧以上、より好ましくは３００ｋＰａ以上、さらに好ましくは４００ｋＰａ以上に維持する。これにより負極としての容量がより高まる。以上の通り、通常よりも過酷な条件においてコーキングを行うことにより、液体をより反応させ、より重合度の高いコークスを得ることができる。 The raw material to be passed through a delayed coker is a decanted oil from which the catalyst has been removed after fluid bed catalytic cracking has been performed on heavy fractions at the time of crude oil refining, coal tar extracted from bituminous coal, etc. And those obtained by sufficiently distilling the tar obtained by raising the temperature to 100 ° C. or higher. During the delayed coking process, it is preferable that the temperature of these liquids be raised to 450 ° C. or higher, 500 ° C. or higher, or even 510 ° C. or higher at least at the entrance of the drum. The carbon content increases and the yield improves. The pressure in the drum is preferably maintained at normal pressure or higher, more preferably 300 kPa or higher, and still more preferably 400 kPa or higher. This further increases the capacity as the negative electrode. As described above, by performing coking under more severe conditions than usual, the liquid can be reacted more and coke having a higher degree of polymerization can be obtained.
　得られたコークスをドラム内からジェット水流により切り出し、得られた塊を５ｃｍ程度まで金槌等で粗粉砕する。粗粉砕には、二軸ロールクラッシャーやジョークラッシャーを用いることもできるが、好ましくは１ｍｍ篩上が９０質量％以上となるように粉砕する。上記のように粉砕を行うことにより、以降の加熱の工程等において、乾燥後、コークス粉が舞い上がったり、焼損が増えるなどの不都合を防ぐことができる。 The obtained coke is cut out from the inside of the drum by a jet water flow, and the obtained mass is roughly crushed to about 5 cm with a gold crucible or the like. Although a twin-roll crusher or a jaw crusher can also be used for the coarse grinding, it is preferable that the 1 mm sieve is ground to have 90% by mass or more. By crushing as described above, it is possible to prevent inconveniences such as popping up of coke powder and increase in burnout after drying in the subsequent heating process and the like.
　次にコークスを粉砕する。
　乾式で粉砕を行う場合、粉砕時にコークスに水が含まれていると粉砕性が著しく低下するので、１００～１０００℃程度で予め乾燥させることが好ましい。より好ましくは１００～５００℃である。コークスが高い熱履歴を有していると圧砕強度が強くなり粉砕性が悪くなり、また結晶の異方性が発達してしまうので劈開性が強くなり鱗片状の粉末になり易くなる。粉砕する手法に特に制限はなく、公知のジェットミル、ハンマーミル、ローラーミル、ピンミル、振動ミル等が用いて行うことができる。
　粉砕は、ＤV50が２．０μｍ以上２０．０μｍ以下となるように行うことが好ましく、５．０μｍ以上１８．０μｍ以下がより好ましい。 The coke is then crushed.
In the case of dry pulverization, if the coke contains water at the time of pulverization, the pulverization property is significantly reduced, so it is preferable to previously dry it at about 100 to 1000.degree. More preferably, it is 100 to 500 ° C. When the coke has a high heat history, the crushing strength becomes strong and the crushability deteriorates, and the crystal anisotropy develops, so that the cleavage property becomes strong and it becomes easy to be a scaly powder. There is no particular limitation on the method of pulverizing, and a known jet mill, hammer mill, roller mill, pin mill, vibration mill or the like can be used.
Milling is preferably carried out as D V50 becomes 2.0μm or 20.0μm or less, and more preferably more than 5.0 .mu.m 18.0.
　黒鉛化は、不活性雰囲気（例えば、窒素ガスやアルゴンガス雰囲気）下で、好ましくは２４００℃以上、より好ましくは２８００℃以上、より一層好ましくは３０５０℃以上、さらに好ましくは３１５０℃以上の温度で行う。より高い温度で処理すると、より黒鉛結晶が成長し、リチウムイオンをより高容量で蓄えることが可能な電極を得ることができる。一方、温度が高過ぎると黒鉛粉の昇華を防ぐことが困難であり、必要とされるエネルギーも大きくなるため、黒鉛化温度は３６００℃以下であることが好ましい。 Graphitization is preferably performed at a temperature of 2400 ° C. or higher, more preferably 2800 ° C. or higher, still more preferably 3050 ° C. or higher, still more preferably 3150 ° C. or higher under an inert atmosphere (eg, nitrogen gas or argon gas atmosphere) Do. When treated at a higher temperature, more graphite crystals grow, and an electrode capable of storing lithium ions with higher capacity can be obtained. On the other hand, if the temperature is too high, it is difficult to prevent the sublimation of the graphite powder, and the required energy also increases, so the graphitization temperature is preferably 3600 ° C. or less.
　これらの温度を達成するためには電気エネルギーを用いることが好ましい。電気エネルギーは他の熱源と比べると高価であり、特に２０００℃以上を達成するためには、極めて大きな電力を消費する。そのため、黒鉛化以外に電気エネルギーは消費されない方が好ましい。黒鉛化に先んじて炭素原料は焼成され、有機揮発分が除去された状態、すなわち固定炭素分が９５％以上、より好ましくは９８％以上、さらに好ましくは９９％以上となっていることが好ましい。この焼成は例えば７００～１５００℃で加熱することにより行うことができる。焼成により黒鉛化時の質量減少が低減するため、黒鉛化処理装置で一度の処理量を高めることができる。 It is preferred to use electrical energy to achieve these temperatures. Electrical energy is expensive compared to other heat sources and consumes a great deal of power, especially to achieve 2000 ° C. or higher. Therefore, it is preferable not to consume electrical energy other than graphitization. Prior to graphitization, it is preferable that the carbon raw material be calcined to remove organic volatile components, that is, the fixed carbon content is 95% or more, more preferably 98% or more, and still more preferably 99% or more. This firing can be performed, for example, by heating at 700 to 1500.degree. Since the reduction in mass at the time of graphitization is reduced by firing, the throughput of the graphitization processing apparatus can be increased once.
　黒鉛化後は粉砕処理を行わないことが好ましい。ただし、黒鉛化後に粒子が粉砕しない程度に解砕することはできる。
　黒鉛粒子を活物質として用いて電極を作製すると、電極圧縮時に電極内部で活物質が均一に分布しやすくなり、また隣接する粒子との接触も安定し、よって繰り返し充放電に一層優れた電池とすることができる。 After graphitization, it is preferable not to carry out the pulverizing treatment. However, it can be crushed to such an extent that the particles are not crushed after graphitization.
When an electrode is produced using graphite particles as an active material, the active material is easily distributed uniformly inside the electrode at the time of electrode compression, and the contact with adjacent particles is also stable, and thus a battery having more excellent charge and discharge repeatedly. can do.
（４）炭素質材料（Ａ３）
　本発明の好ましい実施態様における炭素質材料（Ａ３）は、粒子（Ａ２）とは異なるものであって、炭素原子により形成される結晶の発達が低い炭素材料であり、ラマン散乱分光法によるラマンスペクトルにおいて１３６０ｃｍ-1近傍にピークを持つ。また、炭素質材料（Ａ３）は非晶質炭素被覆層（Ａ１Ｃ）と同一であっても良い。
　炭素質材料（Ａ３）は、例えば、炭素前駆体を炭素化することによって製造することができる。前記炭素前駆体は、特に限定されないが、熱重質油、熱分解油、ストレートアスファルト、ブローンアスファルト、エチレン製造時に副生するタールまたは石油ピッチなどの石油由来物質、石炭乾留時に生成するコールタール、コールタールの低沸点成分を蒸留除去した重質成分、コールタールピッチ（石炭ピッチ）などの石炭由来物質が好ましく、特に石油系ピッチまたは石炭系ピッチが好ましい。ピッチは複数の多環芳香族化合物の混合物である。ピッチを用いると、高い炭素化率で、不純物の少ない炭素質材料（Ａ３）を製造できる。ピッチは酸素含有率が少ないので、粒子（Ａ１）を炭素質材料で被覆する際に、粒子（Ａ１）が酸化されにくい。 (4) Carbonaceous material (A3)
The carbonaceous material (A3) in a preferred embodiment of the present invention is a carbon material which is different from the particles (A2) and in which the development of crystals formed by carbon atoms is low, and a Raman spectrum by Raman scattering spectroscopy. Has a peak near 1360 cm -1 . The carbonaceous material (A3) may be the same as the amorphous carbon coating layer (A1C).
The carbonaceous material (A3) can be produced, for example, by carbonizing a carbon precursor. The carbon precursor is not particularly limited, but includes, but not limited to, thermal heavy oil, pyrolysis oil, straight asphalt, blown asphalt, petroleum-derived substances such as tar or petroleum pitch by-produced during ethylene production, coal tar produced during coal distillation, The heavy component obtained by distilling off the low-boiling component of coal tar, and coal-derived materials such as coal tar pitch (coal pitch) are preferred, and petroleum pitch or coal pitch is particularly preferred. Pitch is a mixture of multiple polycyclic aromatic compounds. When pitch is used, a carbonaceous material (A3) with few impurities can be produced at a high carbonization rate. Since the pitch has a low oxygen content, when the particles (A1) are coated with the carbonaceous material, the particles (A1) are less likely to be oxidized.
　炭素質材料（Ａ３）の前駆体としてのピッチは、軟化点が、好ましくは８０℃以上３００℃以下である。ピッチの軟化点が８０℃以上であれば、それを構成する多環芳香族化合物の平均分子量が小さ過ぎず、かつ揮発分も比較的少ないため、炭素化率の低下、製造コストの上昇、さらに細孔を多く含んだ比表面積の大きい炭素質材料（Ａ３）が得られやすいといった問題は生じない。ピッチの軟化点が３００℃以下であれば、粘度が高過ぎることがないため、粒子（Ａ１）と均一に混ぜ合わせることができる。ピッチの軟化点はＡＳＴＭ－Ｄ３１０４－７７に記載のメトラー法で測定することができる。 The pitch as a precursor of the carbonaceous material (A3) preferably has a softening point of 80 ° C. or more and 300 ° C. or less. If the softening point of pitch is 80 ° C. or higher, the average molecular weight of the polycyclic aromatic compound constituting it is not too small, and the volatile content is also relatively small, so the carbonization rate decreases, the manufacturing cost increases, and further There is no problem that a carbonaceous material (A3) having a large specific surface area containing many pores can be easily obtained. If the softening point of the pitch is 300 ° C. or less, the viscosity is not too high, so that it can be uniformly mixed with the particles (A1). The softening point of pitch can be measured by the Mettler method described in ASTM-D 3104-77.
　炭素質材料（Ａ３）の前駆体としてのピッチは、残炭率が好ましくは２０質量％以上７０質量％以下、より好ましくは２５質量％以上６０質量％以下である。ピッチの残炭率が２０質量％以上であれば、製造コストの上昇や、比表面積の大きい炭素質材料が得られるといった問題は生じない。ピッチの残炭率が７０質量％以下であれば、粘度が高過ぎることがないため、粒子（Ａ１）と均一に混合することができる。
　残炭率は以下の方法で決定される。固体状のピッチを乳鉢等で粉砕し、粉砕物を窒素ガス流通下で質量熱分析する。１１００℃における質量の仕込み質量に対する割合を残炭率と定義する。 The pitch of the carbonaceous material (A3) as a precursor is preferably 20% by mass to 70% by mass, and more preferably 25% by mass to 60% by mass, as a residual carbon ratio. When the residual carbon ratio of the pitch is 20% by mass or more, problems such as an increase in manufacturing cost and a carbonaceous material having a large specific surface area do not occur. If the residual carbon ratio of the pitch is 70% by mass or less, the viscosity is not too high, and therefore, it can be uniformly mixed with the particles (A1).
The residual coal rate is determined by the following method. The solid pitch is ground in a mortar or the like, and the ground product is subjected to mass thermal analysis under a nitrogen gas flow. The ratio of mass to charged mass at 1100 ° C. is defined as the residual carbon ratio.
　本発明に用いられるピッチは、ＱＩ（キノリン不溶分）含量が、好ましくは１０質量％以下、より好ましくは５質量％以下、さらに好ましくは２質量％以下である。ピッチのＱＩ含量はフリーカーボン量に対応する値である。フリーカーボンを多く含むピッチを熱処理すると、メソフェーズ球体が出現してくる過程で、フリーカーボンが球体表面に付着し三次元ネットワークを形成して、球体の成長を妨げるため、モザイク状の組織となりやすい。一方、フリーカーボンが少ないピッチを熱処理すると、メソフェーズ球体が大きく成長してニードルコークスを生成しやすい。ＱＩ含量が上記の範囲にあることにより、電極特性が一層良好になる。 The pitch used in the present invention preferably has a QI (quinoline insoluble content) content of 10% by mass or less, more preferably 5% by mass or less, and still more preferably 2% by mass or less. The QI content of pitch is a value corresponding to the amount of free carbon. When the pitch containing a large amount of free carbon is heat-treated, the free carbon adheres to the surface of the sphere to form a three-dimensional network in the process of appearance of mesophase spheres, thereby hindering the growth of the sphere, and thus it tends to be a mosaic structure. On the other hand, when heat treatment is performed on a pitch having a small amount of free carbon, mesophase spheres grow large and tend to generate needle coke. When the QI content is in the above range, the electrode characteristics are further improved.
　また、本発明に用いられるピッチは、ＴＩ（トルエン不溶分）含量が、好ましくは１０質量％以上７０質量％以下である。ＴＩ含量が低いピッチは、それを構成する多環芳香族化合物の平均分子量が小さく、揮発分が多いので、炭素化率が低くなり製造コストが上昇し、細孔を多く含んだ比表面積が大きい炭素質材料が得られやすい。ＴＩ含量が高いピッチは、それを構成する多環芳香族化合物の平均分子量が大きいので炭素化率が高くなるが、ＴＩ含量の高いピッチは粘度が高いので、粒子（Ａ１）と均一に混合させ難い傾向がある。ＴＩ含量が上記範囲にあることによりピッチとその他の成分とを均一に混合でき、かつ、電池用活物質として好適な特性を示す負極材を得ることができる。 The pitch used in the present invention preferably has a TI (toluene insoluble content) content of 10% by mass to 70% by mass. The pitch with low TI content has a low average carbon weight and high volatile content because the polycyclic aromatic compound constituting it has a low carbonization rate, an increase in production cost, and a large specific surface area including many pores. Carbonaceous materials are easily obtained. The pitch with a high TI content has a high carbonization rate because the average molecular weight of the polycyclic aromatic compound constituting it is high, but the pitch with a high TI content is uniformly mixed with the particles (A1) since the viscosity is high. It tends to be difficult. When the TI content is in the above-mentioned range, it is possible to uniformly mix the pitch and the other components, and to obtain a negative electrode material having characteristics suitable as a battery active material.
　本発明に用いられるピッチのＱＩ含量及びＴＩ含量はＪＩＳ　Ｋ２４２５に記載されている方法またはそれに準じた方法により測定することができる。 The QI content and the TI content of the pitch used in the present invention can be measured by the method described in JIS K2425 or a method according thereto.
　前記の粒子（Ａ１）、粒子（Ａ２）及び炭素質材料（Ａ３）の合計質量に対する炭素質材料（Ａ３）の質量割合は好ましくは２質量％以上４０質量％以下であり、より好ましくは４質量％以上３０質量％以下である。
　炭素質材料（Ａ３）の割合が２質量％以上であれば、粒子（Ａ１）と粒子（Ａ２）の十分な結合が得られ、また、粒子（Ａ１）の表面を炭素質材料（Ａ３）で覆うことが可能となるため、粒子（Ａ１）に導電性が付与され易くなり、粒子（Ａ１）の表面反応性を抑制する効果や膨張収縮を緩和する効果が得られ、良好なサイクル特性が得られる。一方、炭素質材料（Ａ３）の割合が４０質量％以下であれば、炭素質材料（Ａ３）の割合が高くても初期効率が低くなることはない。 The mass ratio of the carbonaceous material (A3) to the total mass of the particles (A1), the particles (A2) and the carbonaceous material (A3) is preferably 2% by mass to 40% by mass, and more preferably 4% % Or more and 30% by mass or less.
When the proportion of the carbonaceous material (A3) is 2% by mass or more, sufficient bonding between the particles (A1) and the particles (A2) can be obtained, and the surface of the particles (A1) can be a carbonaceous material (A3) As it becomes possible to cover, conductivity is easily imparted to the particles (A1), and an effect of suppressing surface reactivity of the particles (A1) and an effect of alleviating expansion and contraction are obtained, and good cycle characteristics are obtained. Be On the other hand, if the proportion of the carbonaceous material (A3) is 40% by mass or less, the initial efficiency does not decrease even if the proportion of the carbonaceous material (A3) is high.
（５）複合体（Ａ）
　本発明の一実施形態に係る複合体（Ａ）は、粒子（Ａ１）と非晶質炭素被覆層（Ａ１Ｃ）からなる構造体（α）と、粒子（Ａ２）と、炭素質材料（Ａ３）とを含み、前記の構造体（α）と粒子（Ａ２）と炭素質材料（Ａ３）とは少なくともその一部が互いに複合化していることが好ましい。複合化とは、例えば、構造体（α）と粒子（Ａ２）とが炭素質材料（Ａ３）により固定されて結合している状態、あるいは構造体（α）及び／または粒子（Ａ２）が炭素質材料（Ａ３）により被覆されている状態を挙げることができる。本発明においては構造体（α）が炭素質材料（Ａ３）によって完全に被覆され、構造体（α）の表面が露出していない状態となっていることが好ましく、その中でも構造体（α）と粒子（Ａ２）とが炭素質材料（Ａ３）を介して連結し、その全体が炭素質材料（Ａ３）により被覆されている状態、及び構造体（α）と粒子（Ａ２）とが直接接触し、その全体が炭素質材料（Ａ３）により被覆されている状態が好ましい。
　負極材として電池に用いた際に、構造体（α）の表面が露出しないことにより電解液分解反応が抑制されクーロン効率を高く維持することができ、炭素質材料（Ａ３）を介して粒子（Ａ２）及び構造体（α）が連結することによりそれぞれの間の導電性を高めることができ、また構造体（α）が炭素質材料（Ａ３）により被覆されることによりその膨張及び収縮に伴う体積変化を緩衝することができる。 (5) Complex (A)
The composite (A) according to one embodiment of the present invention comprises a structure (α) comprising particles (A1) and an amorphous carbon coating layer (A1C), particles (A2), and a carbonaceous material (A3). It is preferable that at least a part of the structure (α), the particles (A2) and the carbonaceous material (A3) be complexed with each other. The complexing is, for example, a state in which the structure (α) and the particle (A2) are fixed by the carbonaceous material (A3) and bound, or the structure (α) and / or the particle (A2) is carbon The state covered with the quality material (A3) can be mentioned. In the present invention, it is preferable that the structure (α) is completely covered with the carbonaceous material (A3) and the surface of the structure (α) is not exposed, among which the structure (α) And particles (A2) are linked via the carbonaceous material (A3), and the whole is covered with the carbonaceous material (A3), and the structure (α) and particles (A2) are in direct contact It is preferable that the whole is covered with the carbonaceous material (A3).
When used as a negative electrode material in a battery, the surface of the structure (α) is not exposed, so that the electrolytic solution decomposition reaction is suppressed and the coulombic efficiency can be maintained high, and particles (the carbonaceous material (A3) A2) and the structure (α) can increase the conductivity between each other, and the structure (α) is covered with the carbonaceous material (A3) to be accompanied by its expansion and contraction. Volume changes can be buffered.
　本発明の一実施形態に係る複合体（Ａ）には、複合化されていない、粒子（Ａ２）、炭素質材料（Ａ３）または構造体（α）が単独で含まれていてもよい。複合化されずに単独で含まれている粒子（Ａ２）、炭素質材料（Ａ３）、または構造体（α）の量は少ない方が好ましく、具体的には、複合体（Ａ）の質量に対して、好ましくは１０質量％以下である。 The composite (A) according to an embodiment of the present invention may contain the particles (A2), the carbonaceous material (A3) or the structure (α) alone, which are not complexed. It is preferable that the amount of the particles (A2), the carbonaceous material (A3), or the structures (α) contained alone without being complexed is small, and specifically, to the mass of the complex (A) On the other hand, it is preferably 10% by mass or less.
　本発明の一実施形態に係る複合体（Ａ）のＤV50は２．０μｍ以上２０．０μｍ以下が好ましい。より好ましくは２．０μｍ以上１８．０μｍ以下である。ＤV50が２．０μｍ以上であれば、経済性のよい製造が可能である。また、電極密度を上げることにも困難はない。さらに、比表面積が過度に大きくならないため、電解液との副反応による初期充放電効率の低下も起こらない。また、ＤV50が２０．０μｍ以下であれば、良好な入出力特性とサイクル特性が得られる。 As for DV50 of the complex (A) which concerns on one Embodiment of this invention, 2.0 micrometers or more and 20.0 micrometers or less are preferable. More preferably, it is 2.0 micrometers or more and 18.0 micrometers or less. If DV50 is 2.0 micrometers or more, economical manufacture is possible. Also, there is no difficulty in increasing the electrode density. Furthermore, since the specific surface area is not excessively increased, the decrease in the initial charge and discharge efficiency due to the side reaction with the electrolytic solution does not occur. Further, if the DV50 is 20.0 μm or less, good input / output characteristics and cycle characteristics can be obtained.
　本発明の一実施形態に係る複合体（Ａ）のＢＥＴ比表面積（ＳBET）は１．０ｍ2／ｇ以上１０．０ｍ2／ｇ以下が好ましい。より好ましくは１．０ｍ2／ｇ以上５．０ｍ2／ｇ以下である。ＢＥＴ比表面積（ＳBET）が１．０ｍ2／ｇ以上であれば、入出力特性が低下することなく、電極中での均一分布性が維持され、良好なサイクル特性が得られる。ＢＥＴ比表面積（ＳBET）が１０．０ｍ2／ｇ以下であれば、塗工性が低下することなくハンドリング性も良好である。また、電極作製にバインダーを多く必要とすることもなく、電極密度を上げやすく、電解液との副反応による初期充放電効率の低下を抑制できる。 The BET specific surface area (S BET ) of the composite (A) according to one embodiment of the present invention is preferably 1.0 m 2 / g or more and 10.0 m 2 / g or less. More preferably, it is 1.0 m 2 / g or more and 5.0 m 2 / g or less. If the BET specific surface area (S BET ) is 1.0 m 2 / g or more, uniform distribution in the electrode is maintained without deterioration of input / output characteristics, and good cycle characteristics can be obtained. When the BET specific surface area (S BET ) is 10.0 m 2 / g or less, the coating property is not lowered and the handling property is also good. In addition, it is easy to increase the electrode density without requiring a large amount of binder for electrode production, and it is possible to suppress a decrease in initial charge and discharge efficiency due to a side reaction with the electrolytic solution.
　本発明の一実施形態に係る複合体（Ａ）は、Ｘ線回折法により測定されるＳｉ粒子（Ａ１）の（１１１）面回折ピークの半値幅が０．４０度以上０．７１度以下であり、好ましくは０．４０度以上０．６５度以下であり、さらに好ましくは０．４０度以上０．６５度以下である。Ｓｉ粒子（Ａ１）の（１１１）面回折ピーク半値幅が、０．４０度を下回ると、Ｓｉ粒子（Ａ１）の結晶子サイズが大きくなり、Ｓｉ粒子（Ａ１）の膨張が異方的になる。その結果、電極膨張率が増大し、サイクル容量維持率が低下する。
　粒子（Ａ１）の回折ピークの半値幅は、前述の粉末Ｘ線回折（ＸＲＤ）法を用いて測定することができる（稲垣道夫、「炭素」、１９６３、Ｎｏ．３６、２５－３４頁；Ｉｗａｓｈｉｔａ　ｅｔ　ａｌ．，Ｃａｒｂｏｎ　ｖｏｌ．４２（２００４），ｐ．７０１－７１４）。なお、この測定において、Ｓｉ粒子（Ａ１）の（１１１）面回折ピークの半値幅が０．７１度を上回ることは、結晶子サイズが０ｎｍを下回ることになり、起こり得ない。 In the composite (A) according to one embodiment of the present invention, the half value width of the (111) plane diffraction peak of the Si particle (A1) measured by the X-ray diffraction method is 0.40 to 0.71 degrees. Preferably it is 0.40 degree or more and 0.65 degree or less, More preferably, it is 0.40 degree or more and 0.65 degree or less. When the half value width of the (111) plane diffraction peak of the Si particle (A1) is less than 0.40 degrees, the crystallite size of the Si particle (A1) becomes large and the expansion of the Si particle (A1) becomes anisotropic. . As a result, the electrode expansion rate increases and the cycle capacity retention rate decreases.
The half value width of the diffraction peak of the particles (A1) can be measured using the powder X-ray diffraction (XRD) method described above (Michio Inagaki, “carbon”, 1963, No. 36, pages 25-34; Iwashita et al., Carbon vol. 42 (2004), p. 701-714). In this measurement, when the half value width of the (111) plane diffraction peak of the Si particle (A1) exceeds 0.71 degrees, the crystallite size becomes less than 0 nm, which can not occur.
　本発明の一実施形態に係る複合体（Ａ）は、顕微ラマン分光測定器で粒子端面を測定して得られたラマン分光スペクトルにおいて、１３００～１４００ｃｍ-1の範囲にあるピークのピーク強度ＩDと１５８０～１６２０ｃｍ-1の範囲にあるピークのピーク強度ＩGとの比ＩD／ＩG（Ｒ値）が０．１５以上１．０以下であることが好ましい。より好ましくは、０．２以上１．０以下、より一層好ましくは０．４以上１．０以下である。Ｒ値が小さ過ぎることは、粒子（Ａ２）の表面が一定量露出していることを表す。よって、Ｒ値が０．１５以上であれば、粒子（Ａ２）と粒子（Ａ１）が炭素質材料（Ａ３）で覆われており、粒子（Ａ１）の表面反応性を抑制する効果や膨張収縮を緩和する効果が高くなるために良好なサイクル特性が得られる。一方、Ｒ値が大きすぎることは、初期不可逆容量の大きな非晶質炭素を多量に含む炭素質材料（Ａ３）が粒子（Ａ２）の表面を覆っていることを表す。よって、Ｒ値が１．０以下であれば、初期放電効率の低下が抑えられる。 The complex (A) according to one embodiment of the present invention has a peak intensity I D of a peak in the range of 1300 to 1400 cm −1 in a Raman spectrum obtained by measuring the particle end face with a microscopic Raman spectrometer. And the ratio I D / I G (R value) of the peak intensity to the peak intensity I G in the range of 1580 to 1620 cm -1 is preferably 0.15 or more and 1.0 or less. More preferably, it is 0.2 or more and 1.0 or less, still more preferably 0.4 or more and 1.0 or less. The fact that the R value is too small means that the surface of the particles (A2) is exposed to a certain amount. Therefore, if the R value is 0.15 or more, the particles (A2) and the particles (A1) are covered with the carbonaceous material (A3), and the effect of suppressing the surface reactivity of the particles (A1) or expansion and contraction Good cycle characteristics can be obtained because the effect of relieving is increased. On the other hand, when the R value is too large, it indicates that the carbonaceous material (A3) containing a large amount of amorphous carbon having a large initial irreversible capacity covers the surface of the particles (A2). Therefore, if R value is 1.0 or less, the fall of initial stage discharge efficiency is suppressed.
（６）複合体（Ａ）の製造方法
　本発明の一実施形態に係る複合体（Ａ）は、公知の方法に従って製造することができる。
　例えば、粒子（Ａ１）と非晶質炭素被覆層（Ａ１Ｃ）からなる構造体（α）と粒子（Ａ２）と炭素質材料（Ａ３）の前駆体とを混ぜ合わせ、得られた混合物を熱処理して前記前駆体を炭素質材料（Ａ３）とすることを含む方法によって複合体（Ａ）を得ることができる。
　構造体（α）と粒子（Ａ２）と炭素質材料（Ａ３）の前駆体との混合物は、例えば、炭素質材料（Ａ３）前駆体の一つであるピッチを溶融させ、該溶融ピッチと構造体（α）とを不活性雰囲気にて混合し、該混合物を固化させた後に粉砕し、該粉砕物を粒子（Ａ２）と混合することによって；構造体（α）と粒子（Ａ２）とを混合し、次いで構造体（α）及び粒子（Ａ２）の混合物と炭素質材料（Ａ３）前駆体とを混合してメカノケミカル処理を行うことによって；または炭素質材料（Ａ３）前駆体を溶媒に溶解し、該前駆体溶液に構造体（α）と粒子（Ａ２）を添加混合し、溶媒を除去して得られた固形物を粉砕することによって；得ることができる。メカノケミカル処理は、例えば、ハイブリダイザー（登録商標、株式会社奈良機械製作所製）などの公知の装置を用いることができる。 (6) Method of Producing Complex (A) The complex (A) according to an embodiment of the present invention can be produced according to a known method.
For example, the structure (α) consisting of the particles (A1) and the amorphous carbon coating layer (A1C), the particles (A2) and the precursor of the carbonaceous material (A3) are mixed, and the obtained mixture is heat-treated Complex (A) can be obtained by the method including making the said precursor into carbonaceous material (A3).
The mixture of the structure (α), the particles (A2) and the precursor of the carbonaceous material (A3), for example, melts the pitch which is one of the precursors of the carbonaceous material (A3), and the molten pitch and structure By mixing the body (α) in an inert atmosphere, solidifying and then grinding the mixture, and mixing the ground product with the particles (A2); the structure (α) and the particles (A2) By mixing and then mixing the mixture of the structure (α) and the particles (A2) with the carbonaceous material (A3) precursor and performing the mechanochemical treatment; or the carbonaceous material (A3) precursor in the solvent It can be obtained by dissolving, adding and mixing the structure (α) and the particles (A2) to the precursor solution, removing the solvent and grinding the solid obtained. For the mechanochemical treatment, for example, a known device such as a hybridizer (registered trademark, manufactured by Nara Machinery Co., Ltd.) can be used.
　粉砕や混合のために、ボールミル、ジェットミル、ロッドミル、ピンミル、ロータリーカッターミル、ハンマーミル、アトマイザー、乳鉢等の公知の装置・器具を用いることができるが、粒子（Ａ１）及び構造体（α）の酸化度合いが高くならないような方法を採用することが好ましい。一般的に酸化は比表面積の大きい小粒径粒子ほど進みやすいと考えられるため、大粒径粒子の粉砕が優先的に進行し、小粒径粒子の粉砕はあまり進まない装置が好ましい。例えば、ロッドミル、ハンマーミルなどのような、主に衝撃によって粉砕する手段は、衝撃力が大粒径粒子に優先的に伝わり、小粒径粒子にはあまり伝わらない傾向がある。ピンミル、ロータリーカッターミルなどのような、主に衝撃とせん断によって粉砕する手段は、せん断力が大粒径粒子に優先的に伝わり、小粒径粒子にはあまり伝わらない傾向がある。このような装置を使用し、粒子（Ａ１）及び構造体（α）の酸化を進ませずに、粉砕や混合することができる。 For grinding and mixing, known devices and apparatus such as ball mill, jet mill, rod mill, pin mill, rotary cutter mill, hammer mill, atomizer, mortar and the like can be used, but the particles (A1) and the structure (α) It is preferable to adopt a method that does not increase the degree of oxidation of In general, it is considered that oxidation tends to progress to small particle size particles having a large specific surface area, so grinding of large particle size particles preferentially proceeds, and apparatus in which small particle size particles do not progress much is preferable. For example, in means for mainly crushing by impact, such as a rod mill, a hammer mill, etc., the impact force tends to be transmitted preferentially to large particle size particles and not to much to small particle size particles. The means of grinding mainly by impact and shear, such as a pin mill and a rotary cutter mill, tends to transmit shear force preferentially to large particle size particles and less to small particle size particles. Such an apparatus can be used to grind or mix the particles (A1) and the structure (α) without promoting oxidation.
　また、粒子（Ａ１）及び構造体（α）の酸化進行を抑えるために、前記の粉砕・混合は非酸化性雰囲気で行うことが好ましい。非酸化性雰囲気としては、アルゴンガス、窒素ガスなどの不活性ガスを充満させた雰囲気が挙げられる。 Further, in order to suppress the progress of oxidation of the particles (A1) and the structural body (α), it is preferable to carry out the aforementioned pulverization / mixing in a non-oxidative atmosphere. As the non-oxidizing atmosphere, an atmosphere filled with an inert gas such as argon gas or nitrogen gas can be mentioned.
　炭素質材料（Ａ３）前駆体を炭素質材料（Ａ３）とするための熱処理は、好ましくは２００℃以上２０００℃以下、より好ましくは５００℃以上１５００℃以下、特に好ましくは６００℃以上１２００℃以下の温度で行う。この熱処理によって、炭素質材料（Ａ３）が構造体（α）及び／または粒子（Ａ２）を被覆し、また炭素質材料（Ａ３）が、構造体（α）相互の間、粒子（Ａ２）相互の間、及び構造体（α）と粒子（Ａ２）との間に入り込みこれらを連結した形態にすることができる。熱処理温度が低すぎると炭素質材料（Ａ３）前駆体の炭素化が十分に終了せず、負極材中に水素や酸素が残留し、それらが電池特性に悪影響を及ぼすことがある。逆に熱処理温度が高過ぎると結晶化が進みすぎて充電特性が低下したり、粒子（Ａ１）構成元素と炭素とが結合してＬｉイオンに対し不活性な状態を生じさせることがある。熱処理は、非酸化性雰囲気で行うことが好ましい。非酸化性雰囲気としては、アルゴンガス、窒素ガスなどの不活性ガスを充満させた雰囲気が挙げられる。また、熱処理により粒子が融着しで塊になっていることがあるため、熱処理品を電極活物質として用いるためには解砕することが好ましい。解砕方法としては、ハンマーなどの衝撃力を利用したパルベライザー、被解砕物同士の衝突を利用したジェットミルなどが好ましい。 The heat treatment for converting the carbonaceous material (A3) precursor to the carbonaceous material (A3) is preferably 200 ° C. or more and 2000 ° C. or less, more preferably 500 ° C. or more and 1500 ° C. or less, particularly preferably 600 ° C. or more and 1200 ° C. or less At a temperature of By this heat treatment, the carbonaceous material (A3) coats the structural body (α) and / or the particles (A2), and the carbonaceous material (A3) is between the structural bodies (α) and the particles (A2) And between the structure (α) and the particles (A2) to connect them. If the heat treatment temperature is too low, carbonization of the carbonaceous material (A3) precursor is not completed sufficiently, and hydrogen and oxygen may remain in the negative electrode material, which may adversely affect battery characteristics. On the other hand, if the heat treatment temperature is too high, crystallization proceeds too much to deteriorate the charge characteristics, or the constituent element of the particles (A1) and carbon may be combined to cause an inactive state with respect to Li ions. The heat treatment is preferably performed in a non-oxidative atmosphere. As the non-oxidizing atmosphere, an atmosphere filled with an inert gas such as argon gas or nitrogen gas can be mentioned. In addition, since the particles may be fused and agglomerated by heat treatment, it is preferable to crush the heat-treated product in order to use it as an electrode active material. As a crushing method, a pulperizer using an impact force such as a hammer, a jet mill using a collision of objects to be crushed and the like are preferable.
（７）容量の調整
　リチウムイオン二次電池用負極材として、電池性能を向上する目的やリチウムイオン二次電池用負極材の容量を調節する目的で、複合体（Ａ）と炭素とを含む材料を混合してもよい。混合する炭素を含む材料は複数種類用いてもよい。炭素を含む材料としては容量の高い黒鉛が好ましい。黒鉛としては天然黒鉛、人造黒鉛から選択して用いることができる。この際、複合体（Ａ）は比較的高容量（７００ｍＡｈ／ｇ以上）である複合体を用いた方がリチウムイオン二次電池用負極材のコストが低減できるため好ましい。この容量調整用の炭素を含む材料は、予め複合体（Ａ）と混合しておき、これにバインダー、溶剤、導電助剤等の添加剤を加えて負極用ペーストを作製してもよい。また、複合体（Ａ）、炭素を含む材料、バインダー、溶剤、導電助剤等の添加剤を同時に混合して負極用ペーストを作製してもよい。混合の順序や方法は粉体のハンドリング等を考慮して適宜決めればよい。 (7) Adjustment of Capacity A material containing the composite (A) and carbon for the purpose of improving battery performance as the negative electrode material for lithium ion secondary batteries and for the purpose of adjusting the capacity of the negative electrode material for lithium ion secondary batteries May be mixed. A plurality of types of materials containing carbon to be mixed may be used. As a material containing carbon, graphite having a high capacity is preferable. The graphite can be selected from natural graphite and artificial graphite. At this time, it is preferable to use a composite having a relatively high capacity (700 mAh / g or more) as the composite (A) because the cost of the negative electrode material for a lithium ion secondary battery can be reduced. The material containing carbon for adjusting the volume may be mixed with the composite (A) in advance, and additives such as a binder, a solvent, and a conductive additive may be added thereto to prepare a negative electrode paste. In addition, the negative electrode paste may be prepared by simultaneously mixing the composite (A), a material containing carbon, a binder, a solvent, an additive such as a solvent, a conductive additive, and the like. The order and method of mixing may be appropriately determined in consideration of powder handling and the like.
（８）負極用ペースト
　本発明の一実施形態に係る負極用ペーストは、前記負極材とバインダーと溶媒と必要に応じて導電助剤などの添加剤を含む。この負極用ペーストは、例えば、前記負極材とバインダーと溶媒と必要に応じて導電助剤などを混練することによって得ることができる。負極用ペーストは、シート状、ペレット状などの形状に成形することができる。 (8) Paste for Anode The paste for an anode according to one embodiment of the present invention contains the above-mentioned anode material, a binder, a solvent, and, if necessary, an additive such as a conductive aid. This negative electrode paste can be obtained, for example, by kneading the negative electrode material, the binder, the solvent, and the conductive auxiliary agent as needed. The negative electrode paste can be formed into a sheet, a pellet, or the like.
　バインダーとして用いられる材料としては、例えば、ポリエチレン、ポリプロピレン、エチレンプロピレンターポリマー、ブタジエンゴム、スチレンブタジエンゴム、ブチルゴム、アクリルゴム、イオン伝導率の大きな高分子化合物などが挙げられる。イオン伝導率の大きな高分子化合物としては、ポリフッ化ビニリデン、ポリエチレンオキサイド、ポリエピクロロヒドリン、ポリファスファゼン、ポリアクリロニトリルなどが挙げられる。バインダーの量は、負極材１００質量部に対して、好ましくは０．５質量部以上１００質量部以下である。 Examples of the material used as the binder include polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, butyl rubber, acrylic rubber, and a polymer compound having a large ion conductivity. Examples of the polymer compound having large ion conductivity include polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphasphazen, polyacrylonitrile and the like. The amount of the binder is preferably 0.5 parts by mass to 100 parts by mass with respect to 100 parts by mass of the negative electrode material.
　導電助剤は電極に対し導電性及び電極安定性（リチウムイオンの挿入・脱離における体積変化に対する緩衝作用）を付与する役目を果たすものであれば特に限定されない。例えば、カーボンナノチューブ、カーボンナノファイバー、気相法炭素繊維（例えば、「ＶＧＣＦ（登録商標）」昭和電工株式会社製）、導電性カーボン（例えば、「デンカブラック（登録商標）」電気化学工業株式会社製、「Ｓｕｐｅｒ　Ｃ６５」ＴＩＭＣＡＬ社製、「Ｓｕｐｅｒ　Ｃ４５」ＴＩＭＣＡＬ社製、「ＫＳ６Ｌ」ＴＩＭＣＡＬ社製）などが挙げられる。導電助剤の量は、負極材１００質量部に対して、好ましくは１０質量部以上１００質量部以下である。 The conductive aid is not particularly limited as long as it plays the role of imparting conductivity and electrode stability (buffering action against volume change in insertion and detachment of lithium ions) to the electrode. For example, carbon nanotubes, carbon nanofibers, vapor-grown carbon fibers (for example, "VGCF (registered trademark)" manufactured by Showa Denko KK), conductive carbon (for example, "Denka Black (registered trademark)" Electric Chemical Industry Co., Ltd. Manufactured by "Super C65", manufactured by TIMCAL, "Super C45", manufactured by TIMCAL, manufactured by "KS6L", manufactured by TIMCAL, and the like. The amount of the conductive additive is preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the negative electrode material.
　溶媒は、特に制限はなく、Ｎ－メチル－２－ピロリドン、ジメチルホルムアミド、イソプロパノール、水などが使用できる。溶媒として水を使用するバインダーの場合は、増粘剤を併用することが好ましい。溶媒の量はペーストが集電体に塗布しやすいような粘度となるように調整すればよい。 The solvent is not particularly limited, and N-methyl-2-pyrrolidone, dimethylformamide, isopropanol, water and the like can be used. In the case of the binder which uses water as a solvent, it is preferable to use a thickener together. The amount of the solvent may be adjusted to have a viscosity such that the paste can be easily applied to the current collector.
（９）負極シート
　本発明の一実施形態に係る負極シートは、集電体と、集電体を被覆する電極層とを有する。
　集電体としては、例えば、ニッケル箔、銅箔、ニッケルメッシュまたは銅メッシュなどシート状のものが挙げられる。
　電極層は、バインダーと前記の負極材とを含有する。電極層は、例えば、前記のペーストを集電体上に塗布し乾燥させることによって得ることができる。ペーストの塗布方法は特に制限されない。電極層の厚さは、好ましくは５０～２００μｍである。電極層が厚くなりすぎると、規格化された電池容器に負極シートを収容できなくなることがある。電極層の厚さは、ペーストの塗布量によって調整できる。また、ペーストを乾燥させた後、加圧成形することによっても調整することができる。加圧成形法としては、ロール加圧、プレス加圧などの成形法が挙げられる。プレス成形するときの圧力は、好ましくは１００～５００ＭＰａ程度である。
　負極シートの電極密度は次のようにして計算することができる。すなわち、プレス後の負極シートを直径１６ｍｍの円形状に打ち抜き、その質量と厚みを測定する。そこから別途測定しておいた集電体箔（直径１６ｍｍの円形状に打ち抜いたもの）の質量と厚みを差し引いて電極層の質量と厚みを求め、その値を元に電極密度を計算する。 (9) Negative electrode sheet The negative electrode sheet which concerns on one Embodiment of this invention has a collector and the electrode layer which coat | covers a collector.
As a collector, sheet-like things, such as nickel foil, copper foil, nickel mesh, or a copper mesh, are mentioned, for example.
The electrode layer contains a binder and the above-mentioned negative electrode material. The electrode layer can be obtained, for example, by applying the above-mentioned paste on a current collector and drying it. The application method of the paste is not particularly limited. The thickness of the electrode layer is preferably 50 to 200 μm. If the electrode layer is too thick, it may not be possible to accommodate the negative electrode sheet in a standardized battery container. The thickness of the electrode layer can be adjusted by the amount of paste applied. Moreover, after drying a paste, it can also adjust by pressure-molding. Examples of pressure molding methods include molding methods such as roll pressure and press pressure. The pressure for press molding is preferably about 100 to 500 MPa.
The electrode density of the negative electrode sheet can be calculated as follows. That is, the negative electrode sheet after pressing is punched into a circular shape having a diameter of 16 mm, and its mass and thickness are measured. The mass and thickness of the current collector foil (punched into a circular shape of 16 mm in diameter) separately measured therefrom are subtracted to obtain the mass and thickness of the electrode layer, and the electrode density is calculated based on the values.
（１０）リチウムイオン二次電池
　本発明の一実施形態に係るリチウムイオン二次電池は、非水系電解液及び非水系ポリマー電解質からなる群から選ばれる少なくとも一つ、正極シート、及び前記負極シートを有する。
　正極シートとしては、リチウムイオン二次電池に従来から使われていたもの、具体的には正極活物質を含んでなるシートを用いることができる。正極活物質としては、ＬｉＮｉＯ2、ＬｉＣｏＯ2、ＬｉＭｎ2Ｏ4、ＬｉＮｉ0.34Ｍｎ0.33Ｃｏ0.33Ｏ2、ＬｉＦｅＰＯ4などが挙げられる。 (10) Lithium Ion Secondary Battery A lithium ion secondary battery according to an embodiment of the present invention comprises at least one selected from the group consisting of a non-aqueous electrolytic solution and a non-aqueous polymer electrolyte, a positive electrode sheet and the negative electrode sheet. Have.
As the positive electrode sheet, a sheet conventionally used in lithium ion secondary batteries, specifically, a sheet containing a positive electrode active material can be used. Examples of the positive electrode active material include LiNiO 2 , LiCoO 2 , LiMn 2 O 4 , LiNi 0.34 Mn 0.33 Co 0.33 O 2 , LiFePO 4 and the like.
　リチウムイオン二次電池に用いられる非水系電解液及び非水系ポリマー電解質は特に制限されない。例えば、ＬｉＣｌＯ4、ＬｉＰＦ6、ＬｉＡｓＦ6、ＬｉＢＦ4、ＬｉＳＯ3ＣＦ3、ＣＨ3ＳＯ3Ｌｉ、ＣＦ3ＳＯ3Ｌｉなどのリチウム塩を、エチレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、プロピレンカーボネート、ブチレンカーボネート、アセトニトリル、プロピオニトリル、ジメトキシエタン、テトラヒドロフラン、γ－ブチロラクトンなどの非水系溶媒に溶かしてなる有機電解液；ポリエチレンオキシド、ポリアクリロニトリル、ポリフッ化ビリニデン、及びポリメチルメタクリレートなどを含有するゲル状のポリマー電解質；エチレンオキシド結合を有するポリマーなどを含有する固体状のポリマー電解質が挙げられる。 The non-aqueous electrolytic solution and the non-aqueous polymer electrolyte used for the lithium ion secondary battery are not particularly limited. For example, lithium carbonates such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , CH 3 SO 3 Li, CF 3 SO 3 Li, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene Organic electrolytes dissolved in non-aqueous solvents such as carbonate, butylene carbonate, acetonitrile, propionitrile, dimethoxyethane, tetrahydrofuran, γ-butyrolactone, etc. containing polyethylene oxide, polyacrylonitrile, polyfluorinated bilinidene, polymethyl methacrylate and the like Examples thereof include solid polymer electrolytes containing gel-like polymer electrolytes, polymers having ethylene oxide bonds, and the like.
　また、電解液には、リチウムイオン二次電池の充電時に分解反応が起きる物質を少量添加してもよい。該物質としては、例えば、ビニレンカーボネート（ＶＣ）、ビフェニール、プロパンスルトン（ＰＳ）、フルオロエチレンカーボネート（ＦＥＣ）、エチレンスルトン（ＥＳ）などが挙げられる。添加量としては０．０１質量％以上５０質量％以下が好ましい。 In addition, a small amount of a substance that causes a decomposition reaction when charging a lithium ion secondary battery may be added to the electrolytic solution. Examples of the substance include vinylene carbonate (VC), biphenyl, propane sultone (PS), fluoroethylene carbonate (FEC), ethylene sultone (ES) and the like. As addition amount, 0.01 mass% or more and 50 mass% or less are preferable.
　リチウムイオン二次電池には正極シートと負極シートとの間にセパレータを設けることができる。セパレータとしては、例えば、ポリエチレン、ポリプロピレンなど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などが挙げられる。 The lithium ion secondary battery can be provided with a separator between the positive electrode sheet and the negative electrode sheet. As the separator, for example, non-woven fabric mainly made of polyolefin such as polyethylene and polypropylene, cloth, microporous film, or a combination thereof can be mentioned.
　リチウムイオン二次電池は、携帯電話、携帯パソコン、携帯情報端末などの電子機器の電源；電動ドリル、電気掃除機、電動自動車などの電動機の電源；燃料電池、太陽光発電、風力発電などによって得られた電力の貯蔵などに用いることができる。 Lithium-ion secondary batteries are used to power electronic devices such as mobile phones, personal computers and personal digital assistants; power sources for electric drills, electric vacuum cleaners and electric motors such as electric cars; fuel cells, solar power, wind power, etc. It can be used for storage of stored power.
　以下に本発明について実施例及び比較例を示し、さらに具体的に説明する。なお、これらは説明のための単なる例示であって、本発明はこれらに何等制限されるものではない。なお、実施例及び比較例において、粒子（Ａ１）の一次粒子の平均粒子径ｄAV、非晶質炭素被覆層（Ａ１Ｃ）の厚さ、人造黒鉛粒子のＸ線回折法による（００２）面の平均面間隔ｄ002、結晶子のＣ軸方向の厚さＬC及びＳｉ粒子（Ａ１）の（１１１）面回折ピークの半値幅、ラマン分光スペクトルにおけるＲ値は本明細書の「発明を実施するための形態」に記載した方法により測定する。また、その他の物性の測定及び電池評価は下記のように行った。 Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. Note that these are merely illustrative for the purpose of illustration, and the present invention is in no way limited thereto. In Examples and Comparative Examples, the average particle diameter d AV of the primary particles of the particles (A1), the thickness of the amorphous carbon coating layer (A1C), and the (002) plane of the artificial graphite particles by X-ray diffraction method The average interplanar spacing d 002 , the thickness L C of the crystallite in the C-axis direction, the half value width of the (111) diffraction peak of the Si particle (A1), and the R value in the Raman spectrum It measures by the method described in "form". Moreover, the measurement of other physical properties and battery evaluation were performed as follows.
［粉末Ｘ線回折法によるＩ110／Ｉ004の測定］
　炭素粉末試料をガラス製試料板（試料板窓１８×２０ｍｍ、深さ０．２ｍｍ）に充填し、以下の条件で測定を行った。
　　Ｘ線回折装置：リガク製ＳｍａｒｔＬａｂ（登録商標）
　　Ｘ線種：Ｃｕ－Ｋα線
　　Ｋβ線除去方法：Ｎｉフィルター
　　Ｘ線出力：４５ｋＶ、２００ｍＡ
　　測定範囲：５．０～１０．０ｄｅｇ．
　　スキャンスピード：１０．０ｄｅｇ．／ｍｉｎ．
　得られた波形に対し、平滑化、バックグラウンド除去、Ｋα２除去を行い、プロファイルフィッティングを行った。その結果得られた（００４）面のピーク強度Ｉ004と（１１０）面のピーク強度Ｉ110から配向性の指標となる強度比Ｉ110／Ｉ004を算出した。なお、各面のピークは以下の範囲のうち最大の強度のものをそれぞれのピークとして選択した。
　　（００４）面：５４．０～５５．０ｄｅｇ
　　（１１０）面：７６．５～７８．０ｄｅｇ [Measurement of I 110 / I 004 by powder X-ray diffraction method]
A carbon powder sample was filled in a glass sample plate (sample plate window 18 × 20 mm, depth 0.2 mm), and measurement was performed under the following conditions.
X-ray diffractometer: Rigaku SmartLab (registered trademark)
X-ray type: Cu-Kα ray K β-ray removal method: Ni filter X-ray output: 45 kV, 200 mA
Measurement range: 5.0 to 10.0 deg.
Scanning speed: 10.0 deg. / Min.
The obtained waveform was subjected to smoothing, background removal, Kα2 removal, and profile fitting. The resulting (004) intensity ratio becomes orientation index from the peak intensity I 110 between the peak intensity I 004 (110) plane of the surface was calculated I 110 / I 004. In addition, the peak of each surface selected the thing of the largest intensity among the following ranges as each peak.
(004) plane: 54.0 to 55.0 deg.
(110) plane: 76.5 to 78.0 deg
［粒子径ＤV50］
　粉体を極小型スパーテル２杯分、及び非イオン性界面活性剤（ＴＲＩＴＯＮ（登録商標）－Ｘ；Roche Applied Science製）２滴を水５０ｍｌに添加し、３分間超音波分散させた。この分散液をレーザー回折式粒度分布測定器（ＬＭＳ－２０００ｅ、株式会社セイシン企業製）に投入し、体積基準累積粒度分布を測定して５０％粒子径Ｄv50（μｍ）を求めた。 [Particle diameter D V50 ]
The powder was added to 2 cups of very small spatula and 2 drops of nonionic surfactant (TRITON®-X; manufactured by Roche Applied Science) in 50 ml of water and ultrasonically dispersed for 3 minutes. This dispersion was charged into a laser diffraction particle size distribution analyzer (LMS-2000e, manufactured by Seishin Enterprise Co., Ltd.), and the volume-based cumulative particle size distribution was measured to determine 50% particle diameter D v50 (μm).
［比表面積］
　比表面積／細孔分布測定装置（カンタムクローム・インスツルメンツ社製、ＮＯＶＡ　４２００ｅ）を用い、窒素ガスをプローブとして相対圧０．１、０．２、及び０．３のＢＥＴ多点法によりＢＥＴ比表面積ＳBET（ｍ2／ｇ）を測定した。 [Specific surface area]
Specific surface area / pore distribution measurement device (Quantam Chrome Instruments, NOVA 4200e), using nitrogen gas as a probe, BET specific surface area according to BET multipoint method with relative pressure of 0.1, 0.2, and 0.3 S BET (m 2 / g) was measured.
［細孔容積］
　炭素材料約５ｇをガラス製セルに秤量し、１ｋＰａ以下の減圧下３００℃で約３時間乾燥して、水分等の吸着成分を除去した後、炭素材料の質量を測定した。その後、液体窒素冷却下における乾燥後の炭素材料の窒素ガスの吸着等温線をカンタクローム（Quantachrome）社製Ａｕｔｏｓｏｒｂ－１で測定した。得られた吸着等温線のＰ／Ｐ0＝０．９９２～０．９９５での測定点における窒素吸着量と乾燥後の炭素材料の質量から直径０．４μｍ以下の全細孔容積(μＬ／ｇ)を求めた。 [Pore volume]
About 5 g of a carbon material was weighed in a glass cell and dried at 300 ° C. under a reduced pressure of 1 kPa or less for about 3 hours to remove adsorption components such as water, and then the mass of the carbon material was measured. Thereafter, the adsorption isotherm of nitrogen gas of the carbon material after drying under liquid nitrogen cooling was measured by Autosorb-1 manufactured by Quantachrome. The nitrogen adsorption amount at the measurement point of P / P 0 = 0.992 to 0.995 of the obtained adsorption isotherm and the mass of the carbon material after drying, the total pore volume (μL / g) having a diameter of 0.4 μm or less Asked for).
［複合体（Ａ）の粉末Ｘ線回折法測定］
　複合体（Ａ）粉末をガラス製試料板（試料板窓１８×２０ｍｍ、深さ０．２ｍｍ）に充填し、以下の条件で測定した。
　　Ｘ線回折装置：リガク製ＳｍａｒｔＬａｂ（登録商標）、
　　Ｘ線種：Ｃｕ－Ｋα線、
　　Ｋβ線除去方法：Ｎｉフィルター、
　　Ｘ線出力：４５ｋＶ、２００ｍＡ、
　　測定範囲：１０．０～８０．０ｄｅｇ、
　　スキャンスピード：１０．０ｄｅｇ．／ｍｉｎ、
　得られた波形に対し、平滑化、バックグラウンド除去、Ｋα２除去を行い、プロファイルフィッティングを行った。そこからＳｉ（１１１）面回折ピークの半値幅を算出した。
　　Ｓｉ（１１１）：２７．５～２９．０ｄｅｇ。 [Powder X-ray Diffraction Measurement of Complex (A)]
The composite (A) powder was filled in a glass sample plate (sample plate window 18 × 20 mm, depth 0.2 mm) and measured under the following conditions.
X-ray diffractometer: Rigaku SmartLab (registered trademark),
X-ray type: Cu-Kα ray,
K beta radiation removal method: Ni filter,
X-ray output: 45 kV, 200 mA,
Measurement range: 10.0 to 80.0 deg,
Scanning speed: 10.0 deg. / Min,
The obtained waveform was subjected to smoothing, background removal, Kα2 removal, and profile fitting. From this, the half width of the Si (111) plane diffraction peak was calculated.
Si (111): 27.5-29.0 deg.
［正極シートの製造］
　ＬｉＮｉ0.6Ｍｎ0.2Ｃｏ0.2Ｏ2を１９２ｇ、導電助剤としてカーボンブラック４ｇ、及び結着材としてポリフッ化ビニリデン（ＰＶｄＦ）４ｇにＮ－メチルピロリドンを適宜加えながら撹拌・混合し、スラリー状の正極用ペーストを得た。
　前記の正極用ペーストを厚さ２０μｍのアルミ箔上にロールコーターにより塗布し、乾燥させて正極用シートを得た。乾燥した電極はロールプレスにより密度を３．６ｇ／ｃｍ3とし、電池評価用正極シートを得た。 [Manufacture of positive electrode sheet]
For the slurry-like positive electrode, stir and mix while appropriately adding N-methylpyrrolidone to 192 g of LiNi 0.6 Mn 0.2 Co 0.2 O 2 , 4 g of carbon black as a conductive additive, and 4 g of polyvinylidene fluoride (PVdF) as a binder. I got a paste.
The above positive electrode paste was applied onto a 20 μm thick aluminum foil by a roll coater and dried to obtain a positive electrode sheet. The dried electrode was adjusted to a density of 3.6 g / cm 3 by a roll press to obtain a positive electrode sheet for battery evaluation.
［負極シートの製造］
　バインダーとしてカルボキシメチルセルロース（ＣＭＣ；ダイセル製、ＣＭＣ１３００）を用いた。具体的には、固形分比２％のＣＭＣ粉末を溶解した水溶液を得た。
　導電助剤としてカーボンブラック、カーボンナノチューブ（ＣＮＴ）、及び気相成長法炭素繊維（ＶＧＣＦ（登録商標）－Ｈ，昭和電工株式会社製）を用意し、それぞれ３：１：１（質量比）で混合したものを混合導電助剤とした。
　後述の実施例及び比較例で製造した複合体（Ａ）と、容量を調節する目的の炭素を含む材料としての黒鉛の混合物を９０質量部、混合導電助剤２質量部、ＣＭＣ固形分８質量部となるようにＣＭＣ水溶液を混合し、自転・公転ミキサーにて混練し負極用ペーストを得た。
　または、実施例及び比較例で製造した複合体（Ａ）を９０質量部、混合導電助剤２質量部、ＣＭＣ固形分８質量部となるようにＣＭＣ水溶液を混合し、自転・公転ミキサーにて混練し負極用ペーストを得た。
　前記の負極用ペーストを厚み２０μｍの銅箔上に３００μｍギャップのドクターブレードを用いて均一に塗布し、ホットプレートにて乾燥後、真空乾燥させて負極シートを得た。乾燥した電極は３００ＭＰａの圧力にて一軸プレス機によりプレスして電池評価用負極シートを得た。 [Production of negative electrode sheet]
Carboxymethylcellulose (CMC; manufactured by Daicel, CMC 1300) was used as a binder. Specifically, an aqueous solution in which CMC powder having a solid content ratio of 2% was dissolved was obtained.
Prepare carbon black, carbon nanotubes (CNT), and vapor grown carbon fiber (VGCF (registered trademark) -H, Showa Denko KK) as a conductive additive, and each is 3: 1: 1 (mass ratio) The mixture was used as a mixed conductive aid.
90 parts by mass of a mixture of composite (A) manufactured in the following Examples and Comparative Examples and graphite as a material containing carbon for the purpose of adjusting volume, 2 parts by mass of mixed conductive aid, 8 parts by weight of solid CMC The CMC aqueous solution was mixed to be a part, and the mixture was kneaded by a rotation / revolution mixer to obtain a paste for a negative electrode.
Alternatively, 90 parts by mass of the composite (A) manufactured in Examples and Comparative Examples, 2 parts by mass of mixed conductive support agent, and CMC aqueous solution are mixed so that the solid content of CMC is 8 parts by mass, using a rotation / revolution mixer It knead | mixed and obtained the paste for negative electrodes.
The negative electrode paste was uniformly coated on a copper foil with a thickness of 20 μm using a doctor blade with a gap of 300 μm, dried on a hot plate, and then vacuum dried to obtain a negative electrode sheet. The dried electrode was pressed by a uniaxial press at a pressure of 300 MPa to obtain a negative electrode sheet for battery evaluation.
［正負極容量比の微調整］
　正極シートと負極シートを対向させてリチウムイオン電池を作製する際、両者の容量バランスを考慮する必要がある。すなわち、リチウムイオンを受け入れる側の負極の容量が少な過ぎると過剰なＬｉが負極側に析出してサイクル劣化の原因となり、逆に負極の容量が多過ぎるとサイクル特性は向上するものの負荷の小さい状態での充放電となるためエネルギー密度は低下する。これを防ぐために、正極シートは同一のものを使用しつつ、負極シートは対極Ｌｉのハーフセルにて事前に活物質質量当たりの放電量を評価しておき、正極シートの容量（ＱC）に対する負極シートの容量（ＱA）の比が１．２で一定値となるよう負極シートの容量を微調整した。 [Fine adjustment of positive and negative electrode capacity ratio]
When making a positive electrode sheet and a negative electrode sheet opposite, and producing a lithium ion battery, it is necessary to consider both capacity balance. That is, when the capacity of the negative electrode receiving lithium ions is too small, excessive Li precipitates on the negative electrode side to cause cycle deterioration, and conversely, when the capacity of the negative electrode is too large, the cycle characteristics improve but the load is small. The energy density is reduced because of the charge and discharge in In order to prevent this, while using the same positive electrode sheet, the negative electrode sheet evaluates the amount of discharge per mass of active material in the half cell of the counter electrode Li in advance, and the negative electrode with respect to the capacity (Q C ) of the positive electrode sheet The capacity of the negative electrode sheet was finely adjusted so that the ratio of the sheet capacity (Q A ) was a constant value of 1.2.
［評価用電池の作製］
　露点－８０℃以下の乾燥アルゴンガス雰囲気に保ったグローブボックス内で下記の操作を実施した。 [Fabrication of evaluation battery]
The following operation was carried out in a glove box maintained in a dry argon gas atmosphere with a dew point of −80 ° C. or less.
［二極式ラミネート型フルセル］
　上記負極シート及び正極シートを打ち抜いて面積２０ｃｍ2の負極片及び正極片を得た。正極片のＡｌ箔にＡｌタブを、負極片のＣｕ箔にＮｉタブをそれぞれ取り付けた。ポリプロピレン製フィルム微多孔膜を負極片と正極片との間に挟み入れ、その状態でアルミラミネート包材でパックし、電解液を７００μＬ注液した。その後、開口部を熱融着によって封止して評価用の電池を作製した。なお、電解液は、エチレンカーボネート、エチルメチルカーボネート、及びジエチルカーボネートが体積比で３：５：２の割合で混合した溶媒にビニレンカーボネート（ＶＣ）を１質量％、フルオロエチレンカーボネート（ＦＥＣ）を１０質量％混合し、さらにこれに電解質ＬｉＰＦ6を１ｍｏｌ／Ｌの濃度になるように溶解させた液である。 [Two-pole laminate type full cell]
The negative electrode sheet and the positive electrode sheet were punched out to obtain a negative electrode piece and a positive electrode piece having an area of 20 cm 2 . The Al tab was attached to the Al foil of the positive electrode piece, and the Ni tab was attached to the Cu foil of the negative electrode piece. A microporous film made of polypropylene was sandwiched between the negative electrode piece and the positive electrode piece, and was packed with an aluminum laminate packaging material in that state, and 700 μL of an electrolytic solution was injected. Thereafter, the opening was sealed by heat fusion to prepare a battery for evaluation. The electrolytic solution was prepared by mixing 1% by mass of vinylene carbonate (VC) and 10 parts of fluoroethylene carbonate (FEC) in a solvent in which ethylene carbonate, ethyl methyl carbonate and diethyl carbonate were mixed in a volume ratio of 3: 5: 2. mixed mass%, a further liquid electrolyte LiPF 6 was dissolved to a concentration of 1 mol / L to this.
［充電、放電の定義］
　充電とはセルに対して電圧を付与することであり、放電とはセルの電圧を消費する操作である。二極式ラミネート型フルセルの場合、対極はＬｉ金属でなく、上記負極シートよりも高い酸化還元電位を有する材料を適用する。そのため、負極シートは負極として扱われる。従って、二極式ラミネート型フルセルにおいて、充電とは上記負極シートに対してＬｉを挿入する操作を意味し、放電とは上記負極操作からＬｉを放出する操作を意味する。 [Definition of charge and discharge]
Charging refers to applying a voltage to the cell, and discharging refers to an operation that consumes the voltage of the cell. In the case of the bipolar laminate type full cell, the counter electrode is not Li metal, and a material having a higher redox potential than the negative electrode sheet is applied. Therefore, the negative electrode sheet is treated as a negative electrode. Therefore, in the bipolar laminate full cell, charging means an operation of inserting Li into the negative electrode sheet, and discharging means an operation of releasing Li from the negative electrode operation.
［二極式ラミネート型フルセルを用いた充放電サイクル試験］
　二極式ラミネート型フルセルを用いたサイクル試験では、エージングは５サイクル実施した。エージングの内１サイクル目は、レストポテンシャルから０．０２５Ｃの電流値で６時間４５分間ＣＣモードにて充電し、１２時間の休止を導入した。その後さらに４．２Ｖまで０．０５ＣでＣＣ充電を実施した。放電は、０．０５Ｃの電流値にて２．７ＶまでＣＣモードで実施した。エージングの２サイクル目、５サイクル目は同一の条件であり、充電は、４．３Ｖまで電流値０．１ＣでＣＣ充電したあと、４．３ＶでＣＶ充電に切り替え、カットオフ電流値を０．０２５Ｃで充電を行った。放電は、０．１Ｃの電流値にて２．７ＶまでＣＣモードで実施した。エージングの３サイクル目、４サイクル目は同一の条件であり、エージング２サイクル目、５サイクル目の電流値を０．１Ｃから０．２Ｃに置き換えた。
　上記エージングを行った後、次の方法で充放電サイクル試験を行った。
　充電は、電流値１ＣのＣＣモードで４．３Ｖまで行った後、ＣＶモードの放電に切り替え、カットオフ電流値を０．０５Ｃにして実施した。
　放電は、電流値１ＣのＣＣモードで３．０Ｖまで行った。
この充放電操作を１サイクルとして２０サイクル行い、２１サイクル目に上記充放電の１Ｃを０．１Ｃに置き換えた低レート試験を行った。この２１サイクル試験を繰り返し、計５００サイクルの試験とした。
　Ｎサイクル目の放電容量維持率を次式で定義して計算した。
　　（Ｎサイクル後放電容量維持率（％））＝
　　　　　　｛（Ｎサイクル時放電容量）／（初回放電容量）｝×１００
　この式における初回放電容量とはエージング終了後の１サイクル目を意味する。 [Charge / Discharge Cycle Test Using Bipolar Laminated Full Cell]
In the cycle test using a bipolar laminate type full cell, aging was performed 5 cycles. In the first cycle of aging, charging was performed in CC mode for 6 hours and 45 minutes at a current value of 0.025 C from the rest potential, and a 12 hour rest was introduced. After that, CC charging was further performed at 0.05 C to 4.2 V. The discharge was carried out in CC mode up to 2.7 V with a current value of 0.05C. Under the same conditions for the second and fifth cycles of aging, charging was performed by CC charging at a current value of 0.1 C to 4.3 V, then switching to CV charging at 4.3 V, and a cutoff current value of 0. 0. Charged at 025C. The discharge was carried out in CC mode up to 2.7 V with a current value of 0.1C. The third cycle and the fourth cycle of the aging were under the same condition, and the current value in the second and the fifth cycle of the aging was replaced with 0.1 C to 0.2 C.
After the aging described above, a charge / discharge cycle test was performed by the following method.
The charging was performed to a voltage of 4.3 V in the CC mode with a current value of 1 C, and then switched to the discharge in the CV mode, and was performed with a cutoff current value of 0.05 C.
Discharge was performed up to 3.0 V in CC mode with a current value of 1C.
This charge / discharge operation was performed as one cycle for 20 cycles, and at the 21st cycle, a low rate test was performed in which 1 C of the charge / discharge was replaced with 0.1 C. This 21 cycle test was repeated for a total of 500 cycles.
The discharge capacity maintenance rate at the Nth cycle was defined by the following equation and calculated.
(Discharge capacity retention rate after N cycles (%)) =
{(N cycle discharge capacity) / (initial discharge capacity)} × 100
The first discharge capacity in this equation means the first cycle after the end of aging.
［電極膨張率の測定］
　上記５０４サイクルの試験が終わった放電後の二極式ラミネート型フルセルを回収後、露点－８０℃以下の乾燥アルゴンガス雰囲気に保ったグローブボックス内で解体し、負極を取り出した。負極をエチルメチルカーボネート（ＥＭＣ）で洗浄した後、ダイヤルゲージ（株式会社ミツトヨ製；Ｃｏｄｅ．Ｎｏ５４７－４０１　目盛り０．００１ｍｍ）を用いて電極の厚みを測定した。測定箇所はタブ取り付けの側電極短辺に沿った９箇所とし、その測定値の平均値を電極厚みとした。電極膨張率を求める際の基準となる電極としては、プレス直後の電極を使用した。なお、ここでの電極厚みは、全て銅箔集電体の厚みを差し引いた値を意味している。 [Measurement of electrode expansion rate]
After the test of the 504 cycles was completed, the bipolar laminate type full cell after discharge was recovered, and then disassembled in a glove box maintained in a dry argon gas atmosphere with a dew point of −80 ° C. or less, and the negative electrode was taken out. After washing the negative electrode with ethyl methyl carbonate (EMC), the thickness of the electrode was measured using a dial gauge (manufactured by Mitutoyo Co., Ltd .; Code No. 547-401, scale 0.001 mm). The measurement locations were nine locations along the short side of the tab-attached side electrode, and the average value of the measured values was taken as the electrode thickness. The electrode immediately after pressing was used as an electrode serving as a reference in determining the electrode expansion coefficient. In addition, the electrode thickness here means the value which deducted the thickness of the copper foil collector altogether.
　下記の実施例及び比較例で使用した材料は以下の通りである。
（１）ケイ素含有粒子（Ｓｉ微粒子）
　実施例及び比較例で、粒子（Ａ１）に使用したＳｉ粒子、Ｓｉ（１）～Ｓｉ（３）の物性を表１に示す。
　一次粒子の平均粒子径ｄAVは前述の通り、ｄAV［ｎｍ］＝６×1０3／（ρ×ＳBET）である。ここで、ρはＳｉ粒子の真密度（理論値としての２．３［ｇ／ｃｍ3］）であり、ＳBETはＢＥＴ法により測定した比表面積［ｍ2／ｇ］である。
Figure JPOXMLDOC01-appb-T000001
 The materials used in the following examples and comparative examples are as follows.
(1) Silicon-containing particles (Si fine particles)
Physical properties of Si particles and Si (1) to Si (3) used for the particles (A1) in Examples and Comparative Examples are shown in Table 1.
The average particle diameter d AV of the primary particles is d AV [nm] = 6 × 10 3 / (ρ × S BET ) as described above. Here, ρ is the true density (2.3 [g / cm 3 as theoretical value) of Si particles, and S BET is the specific surface area [m 2 / g] measured by the BET method.
Figure JPOXMLDOC01-appb-T000001
（２）構造体（α）の作製
　Ｓｉ微粒子Ｓｉ（１）をＣＶＤ法で作製後、連続してアセチレンガスを原料に用いてＣＶＤ法で厚さ２ｎｍの炭素被覆層形成させることにより構造体（α）－１を得た（表１）。なお、Ｓｉ微粒子Ｓｉ（２）及びＳｉ（３）については、構造体（α）の作製は行わなかった。 (2) Preparation of structure (α) After preparing Si fine particle Si (1) by the CVD method, the structure is continuously formed by forming a carbon coating layer with a thickness of 2 nm by the CVD method using acetylene gas as a raw material α) -1 was obtained (Table 1). The structure (α) was not produced for the Si fine particles Si (2) and Si (3).
（３）ピッチ
　石油ピッチ（軟化点２２０℃）を使用した。この石油ピッチについて、窒素ガス流通下の熱分析により１１００℃における残炭率を測定したところ、５２質量％であった。
　また、ＪＩＳ　Ｋ２４２５に記載されている方法またはそれに準じた方法で測定した石油ピッチのＱＩ含量は０．６２質量％、ＴＩ含量は４８．９質量％であった。 (3) Pitch Petroleum pitch (softening point 220 ° C.) was used. It was 52 mass% when the residual carbon rate in 1100 degreeC was measured by thermal analysis under nitrogen gas distribution about this petroleum pitch.
Further, the QI content of the petroleum pitch measured by the method described in JIS K2425 or a method according to the same was 0.62% by mass, and the TI content was 48.9% by mass.
（４）黒鉛粒子
　実施例及び比較例で、粒子（Ａ２）と共に、容量調節の目的で炭素を含む材料として使用した黒鉛粒子の物性を表２に示す。 (4) Graphite particles The physical properties of graphite particles used as a material containing carbon for the purpose of adjusting the volume together with the particles (A2) in Examples and Comparative Examples are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
実施例１：
　石油系コークスをバンタムミル（ホソカワミクロン株式会社製）で粉砕した後、さらにジェットミル（株式会社セイシン企業製）で粉砕し、これをアチソン炉にて３０００℃で熱処理して、ＤV50が７．５μｍ、ＢＥＴ比表面積が４．９ｍ2／ｇの人造黒鉛粒子（Ａ２）－ａを得た。
　次に、構造体（α）－１　１６．４質量部と炭素質材料（Ａ３）の前駆体である前記の石油ピッチ１５．４質量部（石油ピッチを炭化した後の質量として）とをセパラブルフラスコに投入した。窒素ガスを流通させて不活性雰囲気を保ち、２５０℃まで昇温した。ミキサーを５００ｒｐｍで回転させて撹拌し、ピッチとケイ素含有粒子とを均一に混合させた。これを冷却し固化させて混合物を得た。
　この混合物に、粒子（Ａ２）－ａである前記の人造黒鉛粒子６８．２質量部を加え、ロータリーカッターミルに投入し、窒素ガスを流通させて不活性雰囲気を保ちつつ２５０００ｒｐｍで高速撹拌し混合させた。
　これを焼成炉に入れ、窒素ガス流通下で、１５０℃／ｈで１１００℃まで昇温し、１１００℃にて１時間保持し、（Ａ３）前駆体を（Ａ３）に変換した。室温まで冷やし焼成炉から取り出しロータリーカッターミルで解砕後、４５μｍ目開きの篩にて篩分した篩下を複合体（Ａ）－ａとして得た。
　上記とは別に、石油系コークスをバンタムミル（ホソカワミクロン株式会社製）で粉砕し、これをアチソン炉にて３０００℃で熱処理して、ＤV50が１２．１μｍ、ＢＥＴ比表面積が２．５ｍ2／ｇである黒鉛（１）を得た。また、石油系コークスをバンタムミル（ホソカワミクロン株式会社製）で粉砕した後、さらにジェットミル（株式会社セイシン企業製）で粉砕し、これをアチソン炉にて３０００℃で熱処理して、ＤV50が６．７μｍでＢＥＴ比表面積が６．１ｍ2／ｇの黒鉛（２）を得た。 Example 1:
After petroleum-based coke is crushed by a bantam mill (manufactured by Hosokawa Micron Corporation), it is further crushed by a jet mill (manufactured by Seishin Enterprise Co., Ltd.) and heat-treated at 3000 ° C. in an Achison furnace to give a D V 50 of 7.5 μm. Artificial graphite particles (A2) -a having a BET specific surface area of 4.9 m 2 / g were obtained.
Next, 16.4 parts by mass of the structure (α) -1 and 15.4 parts by mass of the petroleum pitch (as a mass after carbonizing the petroleum pitch), which is a precursor of the carbonaceous material (A3), are separated. It was charged into a bull flask. Nitrogen gas was circulated to maintain an inert atmosphere, and the temperature was raised to 250 ° C. The mixer was rotated at 500 rpm for agitation to uniformly mix the pitch and the silicon-containing particles. It was cooled and solidified to obtain a mixture.
68.2 parts by mass of the above-mentioned artificial graphite particles which are particles (A2) -a are added to this mixture, charged into a rotary cutter mill, and mixed at a high speed of 25000 rpm and mixed while maintaining an inert atmosphere by flowing nitrogen gas. I did.
This was put into a baking furnace, heated to 1100 ° C. at 150 ° C./h under nitrogen gas flow, and held at 1100 ° C. for 1 hour to convert the (A3) precursor to (A3). The mixture was cooled to room temperature, taken out from a calcining furnace, crushed with a rotary cutter mill, and sieved with a 45 μm mesh sieve to obtain a sieved part as a composite (A) -a.
Apart from the above, pulverized petroleum coke in a bantam mill (manufactured by Hosokawa Micron Corporation), which was heat-treated at 3000 ° C. in an Acheson furnace, D V50 is 12.1Myuemu, BET specific surface area of 2.5 m 2 / g Graphite (1) was obtained. Further, after pulverizing the petroleum coke with a bantam mill (manufactured by Hosokawa Micron Corporation), and further pulverized with a jet mill (Seishin Ltd. company), which was heat-treated at 3000 ° C. the at Acheson furnace, D V50 is 6. Graphite (2) having a BET specific surface area of 6.1 m 2 / g at 7 μm was obtained.
　複合体（Ａ）－ａ　６７．０質量部と黒鉛（１）１６．５質量部と黒鉛（２）１６．５質量部との混合物を用いて負極シートを作製し、電池特性を測定した。結果を表３に示す。 A negative electrode sheet was produced using a mixture of 67.0 parts by mass of composite (A) -a, 16.5 parts by mass of graphite (1) and 16.5 parts by mass of graphite (2), and battery characteristics were measured. The results are shown in Table 3.
比較例１：
　構造体（α）－１を表１のＳｉ（２）に替えた以外は、実施例１と同じ方法で複合体（Ａ）－ｂを得た。 Comparative Example 1:
A complex (A) -b was obtained in the same manner as in Example 1 except that the structure (α) -1 was changed to Si (2) in Table 1.
　複合体（Ａ）－ｂ　６７．０質量部と黒鉛（１）１６．５質量部と黒鉛（２）１６．５質量部との混合物を用いて負極シートを作製し、電池特性を測定した。結果を表３に示す。 A negative electrode sheet was produced using a mixture of 67.0 parts by mass of the composite (A) -b, 16.5 parts by mass of graphite (1) and 16.5 parts by mass of graphite (2), and battery characteristics were measured. The results are shown in Table 3.
比較例２：
　構造体（α）－１を表１のＳｉ（３）に替えた以外は、実施例１と同じ方法で複合体（Ａ）－ｃを得た。 Comparative example 2:
A complex (A) -c was obtained in the same manner as in Example 1 except that the structure (α) -1 was changed to Si (3) in Table 1.
　複合体（Ａ）－ｃ　６７．０質量部と黒鉛（１）１６．５質量部と黒鉛（２）１６．５質量部との混合物を用いて負極シートを作製し、電池特性を測定した。結果を表３に示す。 A negative electrode sheet was produced using a mixture of 67.0 parts by mass of the composite (A) -c, 16.5 parts by mass of the graphite (1) and 16.5 parts by mass of the graphite (2), and battery characteristics were measured. The results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３に示す結果について、実施例１と比較例１とを比べると、Ｓｉ粒子の平均粒径はほぼ同一なものの、比較例１のＳｉ（１１１）面回折ピークの半値幅は非常に小さい。つまり比較例１の複合体に含まれるＳｉ（１１１）結晶子サイズは大きいことを意味し、Ｓｉ粒子に含まれる結晶子は少ないことになる。その結果、比較例１の複合体中のＳｉ粒子は異方的に膨張し、５００サイクル放電終了時の電極合剤層膨張率は増大する。従って、容量維持率も低下する。 As for the results shown in Table 3, when Example 1 and Comparative Example 1 are compared, the average particle diameter of Si particles is almost the same, but the half value width of the Si (111) surface diffraction peak of Comparative Example 1 is very small. This means that the size of the Si (111) crystallite contained in the composite of Comparative Example 1 is large, and the crystallite contained in the Si particles is small. As a result, the Si particles in the composite of Comparative Example 1 expand anisotropically, and the electrode mixture layer expansion coefficient at the end of 500 cycles of discharge increases. Therefore, the capacity retention rate also decreases.
　表３に示す結果について、実施例１と、比較例１及び比較例２とを比べると、比較例２の複合体はＳｉ（１１１）結晶子サイズが大きいだけではなく、Ｓｉ粒子の平均粒径も非常に大きい。Ｓｉ粒子の平均粒径が大きいと、Ｓｉ１粒子あたりの膨張量が増大すると同時に膨張箇所が局在化する。その結果、電極合剤層を大きく破壊してしまう。一方、Ｓｉ粒子の平均粒径が小さいと、Ｓｉ１粒子のあたりの膨張量が低減すると同時に、膨張超箇所が非局在化する。その結果、電極合剤層の破壊が小さくて済む。従って、比較例２の電極合剤層膨張率と容量維持率は、実施例１と比較例１よりも悪くなっている。 When the results shown in Table 3 are compared with Example 1 and Comparative Examples 1 and 2, the composite of Comparative Example 2 not only has a large Si (111) crystallite size but also the average particle diameter of Si particles. Also very big. When the average particle size of the Si particles is large, the amount of expansion per Si particle increases and at the same time the expanded portion is localized. As a result, the electrode mixture layer is largely destroyed. On the other hand, when the average particle diameter of the Si particles is small, the amount of expansion around the Si1 particles is reduced, and at the same time, the expansion superlocation is delocalized. As a result, breakage of the electrode mixture layer can be reduced. Accordingly, the electrode mixture layer expansion coefficient and capacity retention ratio of Comparative Example 2 are worse than those of Example 1 and Comparative Example 1.

Claims (6)

  1. 　粒子（Ａ１）を被覆する厚さ１ｎｍ以上２０ｎｍ以下の非晶質炭素被覆層（Ａ１Ｃ）と黒鉛を含む物質からなる粒子（Ａ２）と炭素質材料（Ａ３）とを含む複合体（Ａ）を含むリチウムイオン二次電池用負極材であって、前記複合体（Ａ）は粉末Ｘ線回折測定による前記Ｓｉ粒子（Ａ１）の（１１１）面回折ピークの半値幅が０．４０度以上であることを特徴とするリチウムイオン二次電池用負極材。 A composite (A) containing an amorphous carbon coating layer (A1C) having a thickness of 1 nm to 20 nm and a particle (A2) made of a material containing graphite and a carbonaceous material (A3) for covering the particles (A1) The negative electrode material for a lithium ion secondary battery, wherein the composite (A) has a half value width of (111) plane diffraction peak of the Si particle (A1) measured by powder X-ray diffraction measurement of 0.40 degrees or more What is claimed is: 1. A negative electrode material for a lithium ion secondary battery characterized by:
  2. 　前記粒子（Ａ２）は、体積基準累積粒度分布における５０％粒子径ＤV50が２．０μｍ以上２０．０μｍ以下であり、ＢＥＴ比表面積（ＳBET）が１．０ｍ2／ｇ以上１０．０ｍ2／ｇ以下である請求項１に記載のリチウムイオン二次電池用負極材。 The particles (A2) have a 50% particle diameter DV50 in the volume-based cumulative particle size distribution of 2.0 μm to 20.0 μm, and a BET specific surface area (S BET ) of 1.0 m 2 / g to 10.0 m 2 The negative electrode material for a lithium ion secondary battery according to claim 1, which is not more than 1 / g.
  3. 　前記粒子（Ａ２）は、粉末Ｘ線回折法による黒鉛結晶の（１１０）面のピーク強度Ｉ110と（００４）面のピーク強度Ｉ004の比Ｉ110／Ｉ004が０．１０以上０．３５以下であり、粉末Ｘ線回折法による（００２）面の平均面間隔ｄ002が０．３３６０ｎｍ以下であり、窒素ガス吸着法によって測定される直径０．４μｍ以下の細孔の全細孔容積が５．０μＬ／ｇ以上４０．０μＬ／ｇ以下である請求項１または２に記載のリチウムイオン二次電池用負極材。 In the particles (A2), the ratio I 110 / I 004 of the peak intensity I 110 of the ( 110 ) plane to the peak intensity I 004 of the (004) plane by powder X-ray diffraction method is 0.10 or more and 0.35 Or less, the average interplanar spacing d 002 of the (002) plane by powder X-ray diffraction is 0.3360 nm or less, and the total pore volume of pores with a diameter of 0.4 μm or less measured by nitrogen gas adsorption is The negative electrode material for a lithium ion secondary battery according to claim 1 or 2, which is 5.0 μL / g or more and 40.0 μL / g or less.
  4. 　前記複合体（Ａ）中の前記Ｓｉ粒子（Ａ１）の含有率が１０質量％以上７０質量％以下である請求項１～３のいずれか１項に記載のリチウムイオン二次電池用負極材。 The negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 3, wherein a content of the Si particles (A1) in the composite (A) is 10% by mass to 70% by mass.
  5. 　シート状集電体及び集電体を被覆する負極層を有し、前記負極層はバインダー、導電助剤及び請求項１～４のいずれか１項に記載のリチウムイオン二次電池用負極材を含む負極シート。 A sheet-like current collector and a negative electrode layer for covering the current collector, the negative electrode layer comprising a binder, a conductive additive and a negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 4. Negative electrode sheet.
  6. 　請求項５に記載の負極シートを有するリチウムイオン二次電池。 A lithium ion secondary battery comprising the negative electrode sheet according to claim 5.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111180712A (en) * 2020-01-22 2020-05-19 佛山科学技术学院 Nano silicon/carbon nano tube microsphere/graphite composite structure negative electrode material and preparation method thereof
CN114094077A (en) * 2021-11-15 2022-02-25 珠海冠宇电池股份有限公司 Negative electrode material and negative plate containing same
JP7424555B1 (en) 2022-09-01 2024-01-30 Dic株式会社 Negative active materials and secondary batteries
WO2024048051A1 (en) * 2022-09-01 2024-03-07 Dic株式会社 Negative electrode active material and secondary battery

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008102712A1 (en) * 2007-02-21 2008-08-28 Jfe Chemical Corporation Negative electrode material for lithium ion secondary battery, method for production thereof, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
WO2015159935A1 (en) * 2014-04-16 2015-10-22 昭和電工株式会社 Negative electrode material for lithium-ion battery, and use therefor
WO2017002959A1 (en) * 2015-07-02 2017-01-05 昭和電工株式会社 Negative electrode material for lithium-ion batteries and use therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008102712A1 (en) * 2007-02-21 2008-08-28 Jfe Chemical Corporation Negative electrode material for lithium ion secondary battery, method for production thereof, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
WO2015159935A1 (en) * 2014-04-16 2015-10-22 昭和電工株式会社 Negative electrode material for lithium-ion battery, and use therefor
WO2017002959A1 (en) * 2015-07-02 2017-01-05 昭和電工株式会社 Negative electrode material for lithium-ion batteries and use therefor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111180712A (en) * 2020-01-22 2020-05-19 佛山科学技术学院 Nano silicon/carbon nano tube microsphere/graphite composite structure negative electrode material and preparation method thereof
CN114094077A (en) * 2021-11-15 2022-02-25 珠海冠宇电池股份有限公司 Negative electrode material and negative plate containing same
JP7424555B1 (en) 2022-09-01 2024-01-30 Dic株式会社 Negative active materials and secondary batteries
WO2024048051A1 (en) * 2022-09-01 2024-03-07 Dic株式会社 Negative electrode active material and secondary battery

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