WO2013084506A1 - 複合黒鉛粒子およびその用途 - Google Patents
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- WO2013084506A1 WO2013084506A1 PCT/JP2012/007847 JP2012007847W WO2013084506A1 WO 2013084506 A1 WO2013084506 A1 WO 2013084506A1 JP 2012007847 W JP2012007847 W JP 2012007847W WO 2013084506 A1 WO2013084506 A1 WO 2013084506A1
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- H—ELECTRICITY
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- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/628—Coating the powders or the macroscopic reinforcing agents
- C04B35/62802—Powder coating materials
- C04B35/62828—Non-oxide ceramics
- C04B35/62839—Carbon
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- 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
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B2235/3225—Yttrium oxide or oxide-forming salts thereof
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
- C04B2235/54—Particle size related information
- C04B2235/5409—Particle size related information expressed by specific surface values
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
- C04B2235/54—Particle size related information
- C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
- C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
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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
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- 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 composite graphite particles and uses thereof. More specifically, the present invention relates to a lithium ion battery having a low resistance value and good cycle characteristics at low current charge / discharge, a lithium ion battery having a low resistance value and good input / output characteristics and high current cycle characteristics, etc.
- the present invention relates to composite graphite particles useful as a negative electrode material that can be obtained, a production method thereof, an electrode sheet using the composite graphite particles, and a lithium ion battery.
- Lithium ion batteries are used as power sources for portable electronic devices. Initially, lithium-ion batteries have many problems such as insufficient battery capacity and short charge / discharge cycle life. Currently, overcoming such challenges one by one, lithium-ion batteries can be used in applications such as mobile phones, notebook computers, digital cameras, and other low-power devices such as electric tools and electric bicycles. The application is also spreading. In addition, lithium ion batteries are particularly expected to be used as power sources for automobiles, and research and development on electrode materials, cell structures, etc. are actively promoted.
- Carbon-based materials and metal-based materials have been developed as negative electrode materials for lithium ion batteries.
- Carbon materials include carbon materials with high crystallinity, such as graphite, and carbon materials with low crystallinity, such as amorphous carbon. Any of these can be used as a negative electrode active material because lithium insertion / extraction reaction is possible.
- a battery obtained from a low crystalline carbon material has a high capacity, but it is known that the cycle deterioration is remarkable.
- a battery obtained from a highly crystalline carbon material has a relatively low resistance value and stable cycle characteristics, but has a low battery capacity.
- Patent Document 1 discloses a technique for coating the surface of natural graphite with amorphous carbon by mixing natural graphite and pitch and performing heat treatment at 900 to 1100 ° C. in an inert gas atmosphere.
- Patent Document 2 discloses a technique in which a carbon material serving as a core material is immersed in tar or pitch and dried or heat-treated at 900 to 1300 ° C.
- Patent Document 3 a carbon precursor such as pitch is mixed on the surface of graphite particles obtained by granulating natural graphite or scaly artificial graphite, and fired in a temperature range of 700 to 2800 ° C. in an inert gas atmosphere.
- Technology is disclosed.
- Patent Document 4 discloses that spherical graphite particles obtained by granulating and spheroidizing graphite having d 002 of 0.3356 nm, R value of about 0.07, and Lc of about 50 nm by mechanical external force are added to phenol. It is disclosed that composite graphite particles formed by coating a heated carbide of a resin such as a resin are used as a negative electrode active material.
- JP 2005-285633 A Japanese Patent No. 2976299 Japanese Patent No. 3193342 Japanese Patent Laid-Open No. 2004-210634
- lithium-ion batteries still have improved battery capacity, initial coulomb efficiency, low current charge / discharge cycle characteristics, input / output characteristics, large current cycle characteristics, resistance values, etc. It is requested to do.
- An object of the present invention is to provide a composite graphite particle useful as a negative electrode material capable of obtaining a lithium ion battery excellent in cycle characteristics during low current charge / discharge or a lithium ion battery excellent in input / output characteristics and large current cycle characteristics, A production method, and an electrode sheet and a lithium ion battery using the composite graphite particles are provided.
- the present invention includes the following.
- the intensity ratio I D / I G between the peak intensity (I D ) in the range of 1300 to 1400 cm ⁇ 1 and the peak intensity (I G ) in the range of 1500 to 1620 cm ⁇ 1 measured by Raman spectroscopy is 0.00.
- the 50% particle diameter (D 50 ) in the volume-based cumulative particle size distribution measured by laser diffraction method is 3 ⁇ m or more and 30 ⁇ m or less, and is pressed to a density of 1.35 to 1.45 g / cm 3 using a binder.
- Composite graphite particles in which the ratio I 110 / I 004 between the intensity of the 110 diffraction peak (I 110 ) and the intensity of the 004 diffraction peak (I 004 ) measured by the X-ray wide angle diffraction method is 0.2 or more.
- the composite graphite particles according to [2] d 002 based on the 002 diffraction peak measured by wide-angle X-ray diffraction is less than 0.342nm than 0.334nm (1).
- the organic compound is at least one compound selected from the group consisting of petroleum pitch, coal pitch, phenol resin, polyvinyl alcohol resin, furan resin, cellulose resin, polystyrene resin, polyimide resin, and epoxy resin. 5].
- Petroleum coke having a grindability index of 35 to 60 is heat-treated at 2500 ° C. to 3500 ° C. to obtain a core material made of graphite.
- the slurry or paste according to [10] further containing natural graphite.
- An electrode sheet comprising a laminate having a current collector and an electrode layer containing the composite graphite particles according to any one of [1] to [8].
- the electrode layer further contains natural graphite, and a ratio I 110 / I 004 between the intensity of the 110 diffraction peak (I 110 ) and the intensity of the 004 diffraction peak (I 004 ) measured by the X-ray wide angle diffraction method.
- the electrode sheet according to [12] wherein is 0.1 or more and 0.15 or less.
- a lithium ion battery including the electrode sheet according to [12] or [13] as a negative electrode.
- the composite graphite particles according to the present invention have high lithium ion acceptability, they are useful as an active material for a negative electrode of a lithium ion battery.
- the lithium ion battery obtained using the composite graphite particles has good low current cycle characteristics, input / output characteristics, large current cycle characteristics, and the like.
- the composite graphite particles of a preferred embodiment according to the present invention have a core material made of graphite and a carbonaceous layer present on the surface thereof.
- the graphite constituting the core material is artificial graphite obtained by heat-treating (graphitizing) petroleum coke.
- Petroleum coke used as a raw material has a grindability index, that is, HGI (see ASTM D409), usually 35 to 60, preferably 37 to 55, more preferably 40 to 50.
- HGI grindability index
- a lithium ion battery excellent in input / output characteristics, low current cycle characteristics, high current cycle characteristics, and the like can be obtained.
- HGI can be measured by the following method.
- the particle size of the sample is adjusted to 1.18 to 600 ⁇ m, and 50 g of the sample is set in a hard glove grinding tester. Stop the device after rotating 60 times at 5-20 rpm.
- the treatment temperature in graphitization of petroleum coke is usually 2500 ° C. or higher and 3500 ° C. or lower, preferably 2500 ° C. or higher and 3300 ° C. or lower, more preferably 2550 ° C. or higher and 3300 ° C. or lower.
- the graphitization treatment is preferably performed in an inert atmosphere.
- the graphitization treatment time may be appropriately selected according to the amount of treatment, the type of graphitization furnace, and the like, and is not particularly limited.
- the graphitization time is, for example, about 10 minutes to 100 hours.
- the graphitization treatment can be performed using, for example, an Atchison type graphitization furnace.
- the 50% particle diameter (D 50 ) of the core material is preferably 3 ⁇ m or more and 30 ⁇ m or less.
- the 50% particle size (D 50 ) of the core material is preferably 10 ⁇ m or more and 30 ⁇ m or less, more preferably 10 ⁇ m or more and 20 ⁇ m or less from the viewpoint of obtaining a lithium ion battery excellent in low current cycle characteristics and high current cycle characteristics.
- the 50% particle diameter (D 50 ) of the core material is preferably less than 10 ⁇ m, more preferably 3 ⁇ m or more and less than 10 ⁇ m, more preferably from the viewpoint of obtaining a lithium ion battery excellent in input / output characteristics and large current cycle characteristics.
- the adjustment to the 50% particle size (D 50 ) can be performed by a mechanochemical method such as hybridization, a known granulation method, pulverization, classification or the like.
- the 50% particle diameter (D 50 ) is calculated based on a volume-based cumulative particle size distribution measured by a laser diffraction method.
- the core material the ratio I D / I G of the peak intensity (I G) in the range of the peak intensity (I D) and 1500 ⁇ 1620 cm -1 in the range of 1300 ⁇ 1400 cm -1 measured by Raman spectroscopy (R value) is preferably 0.2 or less, more preferably 0.175 or less, further preferably 0.15 or less, and most preferably 0.1 or less.
- the R value of the core material is a value obtained by measurement in a state before the carbonaceous layer is present on the surface of the core material.
- the ratio I D / I G (R value) is preferably 0.2 or more, more preferably 0.35 or more, and still more preferably 0.5 or more.
- the upper limit of the intensity ratio I D / I G (R value) is preferably 1.5, more preferably 1.
- the R value of the carbonaceous layer is a value obtained by measuring the carbonaceous material by obtaining the carbonaceous material by performing the same method as the method of forming the carbonaceous layer described later in the absence of the core material.
- the R value was measured using NRS-5100 manufactured by JASCO Corporation under the conditions of irradiation with an argon laser having a wavelength of 532 nm and an output of 7.4 mW, and measurement of Raman scattered light by a spectrometer.
- an organic compound is first attached to the core material.
- the method of attaching is not particularly limited.
- a method of adhering a core material and an organic compound by dry mixing a method of mixing a solution of an organic compound and a core material, and then removing the solvent and adhering can be mentioned.
- the method by dry mixing is preferable.
- the dry mixing can be performed using, for example, a stirring composite device equipped with an impeller.
- isotropic pitch As the organic compound to be adhered, isotropic pitch, anisotropic pitch, resin, resin precursor or monomer is preferable.
- the pitch include petroleum pitch and coal pitch, and either isotropic pitch or anisotropic pitch can be employed.
- a resin obtained by polymerizing a resin precursor or a monomer As the organic compound, it is preferable to use a resin obtained by polymerizing a resin precursor or a monomer. Suitable resin includes at least one selected from the group consisting of phenol resin, polyvinyl alcohol resin, furan resin, cellulose resin, polystyrene resin, polyimide resin and epoxy resin.
- the organic compound attached to the core material is preferably heat treated at 500 ° C. or higher, more preferably 500 ° C. or higher and 2000 ° C. or lower, further preferably 500 ° C. or higher and 1500 ° C. or lower, particularly preferably 900 ° C. or higher and 1200 ° C. or lower. It is preferable to do.
- the organic compound is carbonized to form a carbonaceous layer. When carbonized in this temperature range, the carbonaceous layer is sufficiently adhered to the core material, and the balance of battery characteristics, charging characteristics, etc. is improved.
- the carbonization by this heat treatment is preferably performed in a non-oxidizing atmosphere.
- the non-oxidizing atmosphere include an atmosphere filled with an inert gas such as argon gas or nitrogen gas.
- the heat treatment time for carbonization may be appropriately selected according to the production scale. For example, it is 30 to 120 minutes, preferably 45 to 90 minutes.
- the ratio of the core material and the carbonaceous layer constituting the composite graphite particles is not particularly limited, but the amount of the carbonaceous layer is preferably 0.05 to 10 with respect to 100 parts by mass of the core material. Part by mass, more preferably 0.1 to 7 parts by mass.
- the amount of the carbonaceous layer is too small, improvement effects such as cycle characteristics tend to be small. If the amount is too large, the battery capacity tends to decrease. Since the amount of the carbonaceous layer is substantially the same as the amount of the organic compound attached to the core material, it can be calculated as the amount of the organic compound attached to the core material.
- the composite graphite particles obtained by the carbonization treatment may be fused to form a lump, they can be atomized by crushing.
- the 50% particle size (D 50 ) in the volume-based cumulative particle size distribution measured by a laser diffraction method is usually 3 ⁇ m or more and 30 ⁇ m or less.
- the composite graphite particles of a preferred embodiment according to the present invention usually have a 50% particle size (D 50 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method. It is 10 ⁇ m or more and 30 ⁇ m or less, preferably 10 ⁇ m or more and 20 ⁇ m or less. From the viewpoint of low current cycle characteristics and high current cycle characteristics, the composite graphite particles of a preferred embodiment according to the present invention have a 90% particle diameter (D 90 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method.
- D 50 50% particle size
- D 90 90% particle diameter
- the composite graphite particles of a preferred embodiment according to the present invention have a 10% particle diameter (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method, Preferably they are 1 micrometer or more and 10 micrometers or less, More preferably, they are 4 micrometers or more and 6 micrometers or less.
- the composite graphite particles of a preferred embodiment according to the present invention have a 50% particle diameter (D 50 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method, usually 3 ⁇ m. It is 10 ⁇ m or less, preferably 3 ⁇ m or more and less than 10 ⁇ m, more preferably 3.5 ⁇ m or more and less than 10 ⁇ m, further preferably 3.5 ⁇ m or more and 8 ⁇ m or less, and most preferably 4 ⁇ m or more and 7 ⁇ m or less.
- D 50 50% particle diameter in a volume-based cumulative particle size distribution measured by a laser diffraction method
- the composite graphite particles of a preferred embodiment according to the present invention preferably have a 90% particle size (D 90 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method. They are 6 micrometers or more and 20 micrometers or less, More preferably, they are 8 micrometers or more and 15 micrometers or less.
- the composite graphite particles of a preferred embodiment according to the present invention have a 10% particle size (D 10 ) in a volume-based cumulative particle size distribution measured by a laser diffraction method, Preferably they are 0.1 micrometer or more and 5 micrometers or less, More preferably, they are 1 micrometer or more and 3 micrometers or less. Since the thickness of the carbonaceous layer is about several tens of nanometers, the 50% particle diameter of the composite graphite particles and the 50% particle diameter of the core material are almost the same as the measured values.
- the composite graphite particles of the preferred embodiment of the present invention d 002 based on the 002 diffraction peak measured by X-ray wide angle diffraction method, preferably 0.334nm than 0.342nm less, more preferably 0.334nm It is not less than 0.338 nm, more preferably not less than 0.3355 nm and not more than 0.3369 nm, particularly preferably not less than 0.3355 nm and not more than 0.3368 nm.
- the composite graphite particles of a preferred embodiment according to the present invention have a crystallite size Lc in the c-axis direction of preferably 50 nm or more, more preferably 75 to 150 nm.
- D 002 and Lc are powders of composite graphite particles set in a powder X-ray diffractometer (manufactured by Rigaku Corporation, Smart Lab IV), measured with a CuK ⁇ ray at an output of 30 kV and 200 mA, and JIS R Calculated according to 7651.
- the Raman range peak intensity in the spectrum 1300 is measured at ⁇ 1400cm -1 (I D) and the peak intensity in the range of 1500 ⁇ 1620cm -1 (I G
- the ratio I D / I G is usually 0.1 or more, preferably 0.1 to 1, more preferably 0.5 to 1, and still more preferably 0.7 to 0.95.
- the BET specific surface area of the composite graphite particles is preferably 0.2 to 30 m 2 / g, more preferably 0.3 to 10 m 2 / g, and still more preferably 0.4 to 5 m 2 / g.
- the composite graphite particles of a preferred embodiment according to the present invention have a 110 diffraction peak intensity (measured by an X-ray wide angle diffraction method) when pressed to a density of 1.35 to 1.45 g / cm 3 using a binder (
- the ratio I 110 / I 004 between I 110 ) and the intensity of the 004 diffraction peak (I 004 ) is usually 0.2 or more, preferably 0.3 or more, more preferably 0.4 or more, still more preferably 0.00. 5 or more.
- polyvinylidene fluoride was used as a binder.
- Other measurement conditions are the same as those described in the examples.
- a slurry or paste of a preferred embodiment according to the present invention contains the composite graphite particles, a binder, and a solvent.
- the slurry or paste of a more preferred embodiment according to the present invention further contains natural graphite.
- the slurry or paste is obtained by kneading the composite graphite particles, a binder, a solvent, and preferably natural graphite.
- the slurry or paste can be formed into a sheet shape, a pellet shape or the like, if necessary.
- the slurry or paste of a preferred embodiment according to the present invention is suitably used for producing battery electrodes, particularly negative electrodes.
- binder examples include polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, butyl rubber, and a polymer compound having high ionic conductivity.
- the polymer compound having a large ionic conductivity examples include polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphasphazene, polyacrylonitrile and the like.
- the mixing ratio of the composite graphite particles and the binder is preferably 0.5 to 20 parts by mass of the binder with respect to 100 parts by mass of the composite graphite particles.
- the amount of natural graphite is not particularly limited as long as the strength ratio I 110 / I 004 of the electrode sheet described later falls within the following range. Specifically, the amount of natural graphite is preferably 10 to 500 parts by mass with respect to 100 parts by mass of composite graphite particles. When natural graphite is used, a battery having a good balance between large current input / output characteristics and cycle characteristics can be obtained.
- Natural graphite is preferably spherical.
- the particle diameter of natural graphite is not particularly limited as long as the strength ratio I 110 / I 004 of the electrode sheet described later falls within the range described later.
- natural graphite preferably has a 50% particle size (D 50 ) in a volume-based cumulative particle size distribution of 1 to 40 ⁇ m. Adjustment of the above range to D 50 can be performed by mechanochemical methods such as hybridization, known granulation methods, pulverization, classification, and the like. For example, Chinese natural graphite having a D 50 of 7 ⁇ m is introduced into a hybridizer NHS1 type manufactured by Nara Machinery Co., Ltd.
- a slurry or paste is prepared by mixing 50 parts by mass of the spherical natural graphite particles thus obtained and 50 parts by mass of the composite graphite particles obtained in an example of the embodiment of the present invention, adding a binder to the mixture, and kneading. Can be obtained.
- the solvent is not particularly limited and includes N-methyl-2-pyrrolidone, dimethylformamide, isopropanol, water and the like.
- a binder using water as a solvent it is preferable to use a thickener together.
- the amount of the solvent is adjusted so that the viscosity is easy to apply to the current collector.
- the slurry or paste of the preferred embodiment according to the present invention may further contain a conductivity imparting agent.
- the conductivity imparting agent include fibrous carbon such as vapor grown carbon fiber and carbon nanotube, and conductive carbon such as acetylene black and ketjen black (trade name).
- the electrode sheet of a preferred embodiment according to the present invention comprises a laminate having a current collector and an electrode layer containing the composite graphite particles according to the present invention.
- the electrode layer preferably further contains natural graphite.
- the electrode sheet can be obtained, for example, by applying the slurry or paste according to the present invention on a current collector, drying, and pressure forming.
- the current collector include foils and meshes made of aluminum, nickel, copper, and the like.
- a conductive layer may be provided on the surface of the current collector.
- the conductive layer usually contains a conductivity imparting agent and a binder.
- the method for applying the slurry or paste is not particularly limited.
- the application thickness (when dried) of the slurry or paste is usually 50 to 200 ⁇ m.
- the negative electrode may not be accommodated in a standardized battery container.
- the pressure molding method include molding methods such as roll pressing and press pressing.
- the pressure during pressure molding is preferably about 100 MPa to about 300 MPa (about 1 to 3 t / cm 2 ).
- the negative electrode thus obtained is suitable for a lithium ion battery.
- the electrode sheet When the composite graphite particles and the natural graphite are contained in the electrode layer, the electrode sheet has a 110 diffraction peak intensity (I 110 ) and a 004 diffraction peak intensity (I) measured by the X-ray wide angle diffraction method.
- the ratio I 110 / I 004 to 004 ) is preferably 0.1 or more and 0.15 or less.
- the strength ratio I 110 / I 004 of the electrode sheet when natural graphite is used together is controlled by adjusting the ratio of the natural graphite particles to the composite graphite particles according to the present invention and the particle diameter of the natural graphite particles. Can do.
- the lithium ion battery of a preferred embodiment according to the present invention includes the electrode sheet according to the present invention as a negative electrode.
- the positive electrode of the lithium ion battery according to a preferred embodiment of the present invention those conventionally used for lithium ion batteries can be used.
- the active material used for the positive electrode include LiNiO 2 , LiCoO 2 , and LiMn 2 O 4 .
- the electrolyte used for the lithium ion battery is not particularly limited.
- lithium salts such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , CH 3 SO 3 Li, CF 3 SO 3 Li can be used, for example, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate,
- non-aqueous electrolytes dissolved in non-aqueous solvents such as propylene carbonate, butylene carbonate, acetonitrile, propyronitrile, dimethoxyethane, tetrahydrofuran, and ⁇ -butyrolactone, and so-called non-aqueous polymer electrolytes in solid or gel form.
- an additive that exhibits a decomposition reaction when the lithium ion battery is initially charged to the electrolyte.
- the additive include vinylene carbonate, biphenyl, propane sulfone and the like. The addition amount is preferably 0.01 to 5% by mass.
- a separator can be provided between the positive electrode and the negative electrode.
- the separator include non-woven fabrics, cloths, microporous films, or combinations thereof, which are mainly composed of polyolefins such as polyethylene and polypropylene.
- HGI Grindability index
- the paste was applied onto the current collector using an automatic coating machine and a doctor blade having a clearance of 250 ⁇ m.
- the current collector on which the paste was applied was placed on a hot plate at about 80 ° C. to remove moisture. Then, it was dried at 120 ° C. for 6 hours with a vacuum dryer. After drying, it was pressure-molded by uniaxial press so that the electrode density determined from the total mass and volume of the graphite particles and the binder was 1.40 ⁇ 0.05 g / cm 3 to obtain an electrode sheet.
- the obtained electrode sheet was cut into an appropriate size and attached to a glass cell for XRD measurement, and a wide-angle X-ray diffraction peak was measured. The ratio I 110 / I 004 between the intensity of the 004 diffraction peak and the intensity of the 110 diffraction peak was calculated.
- This paste was applied onto a 20 ⁇ m thick Cu foil with a doctor blade having a clearance of 150 ⁇ m.
- the current collector coated with the paste was placed on a hot plate at about 80 ° C. to remove N-methyl-2-pyrrolidone. Then, it dried at 90 degreeC with the vacuum dryer for 1 hour. After drying, it was pressure-molded by uniaxial pressing so that the electrode density determined from the total mass and volume of the graphite particles and the binder was 1.50 ⁇ 0.05 g / cm 3 to obtain a negative electrode. The obtained negative electrode was cut out to a size of ⁇ 15 mm.
- the cut negative electrode was pressed at 1.2 t / cm 2 for 10 seconds, and the average thickness of the coating film was measured to be 70 to 80 ⁇ m. Further, the loading level of the coating film was 6.5 to 7.5 mg / cm 2 .
- the negative electrode was introduced into a glove box filled with argon gas and controlled to a dew point of ⁇ 75 ° C. or lower.
- EC ethylene carbonate
- MEC methyl ethyl carbonate
- a separator Cut out at ⁇ 20 mm and a lithium foil of 3 mm thickness cut out at ⁇ 17.5 mm were placed in this order. From the top, a cap with a gasket was attached and caulked with a caulking device.
- N-methyl-2-pyrrolidone manufactured by Kishida Chemical Co., Ltd.
- N-methyl-2-pyrrolidone manufactured by Kishida Chemical Co., Ltd.
- the paste was applied to an aluminum foil having a thickness of 20 ⁇ m with a doctor blade having a clearance of 200 ⁇ m to produce a positive electrode.
- the negative electrode and the positive electrode were laminated in a laminate packaging material via a polypropylene separator (manufactured by Tonen Chemical Co., Ltd., Cellguard 2400).
- an electrolytic solution was injected and heat sealing was performed in a vacuum to obtain a laminate cell for evaluation.
- the first and second charge / discharge cycles were performed as follows.
- the battery was charged at a constant current of 5.5 mA from the rest potential to 4.2 V, then charged at a constant voltage of 4.2 V, and the charging was stopped when the current value decreased to 0.27 mA. Subsequently, constant current discharge was performed at 5.5 mA, and cut off at a voltage of 2.7 V.
- the third and subsequent charge / discharge cycles were performed as follows.
- the battery was charged at a constant current of 5.5 mA (corresponding to 1 C) from the rest potential to 4.2 V, and then charged at a constant voltage of 4.2 V. When the current value dropped to 55 ⁇ A, the charging was stopped. Subsequently, constant current discharge was performed at 5.5 mA (corresponding to 1 C), and cut off at a voltage of 2.7 V. This charge / discharge cycle was repeated.
- the ratio of the discharge capacity at the 200th time to the discharge capacity at the 3rd time was evaluated as a “cycle capacity retention rate”.
- N-methyl-2-pyrrolidone manufactured by Kishida Chemical Co., Ltd.
- N-methyl-2-pyrrolidone manufactured by Kishida Chemical Co., Ltd.
- the paste was applied to an aluminum foil having a thickness of 20 ⁇ m with a doctor blade having a clearance of 200 ⁇ m to produce a positive electrode.
- the negative electrode and the positive electrode were laminated in a laminate packaging material via a polypropylene separator (manufactured by Tonen Chemical Co., Ltd., Cellguard 2400).
- an electrolytic solution was injected and heat sealing was performed in a vacuum to obtain a laminate cell for evaluation.
- the first and second charge / discharge cycles were performed as follows.
- the battery was charged at a constant current of 5.5 mA from the rest potential to 4.2 V, then charged at a constant voltage of 4.2 V, and the charging was stopped when the current value decreased to 0.27 mA. Subsequently, constant current discharge was performed at 5.5 mA, and cut off at a voltage of 2.7 V.
- the third and subsequent charge / discharge cycles were performed as follows.
- the battery was charged at a constant current of 16.5 mA (corresponding to 3C) from the rest potential to 4.2 V, and then charged at a constant voltage of 4.2 V.
- the charging was stopped when the current value dropped to 55 ⁇ A.
- constant current discharge was performed at 16.5 mA (corresponding to 3C), and cut off at a voltage of 2.7V. This charge / discharge cycle was repeated.
- the ratio of the 200th discharge capacity to the third discharge capacity was evaluated as “high rate cycle capacity retention”.
- I / O characteristics were evaluated by the following method. First, constant current discharge was performed at 5.5 mA. Then, constant current charging was performed at 5.5 mA from the rest potential to 4.2 V, and then constant voltage charging was performed at 4.2 V. When the current value decreased to 0.27 mA, charging was stopped. Subsequently, constant current discharge was performed at 0.55 mA (equivalent to 0.1 C) for 2 hours. The voltage value after discharge was recorded. A constant current discharge was performed at 1.1 mA (corresponding to 0.2 C) for 5 seconds, and rested for 30 minutes.
- the above-mentioned constant current discharge for 5 seconds is performed at 0.55 mA (corresponding to 0.1 C) for 3.5 hours, 5 hours, 6.5 hours, or 8 hours, and at that time, 0.2 C, 0.5 C
- the current value and voltage value were recorded under constant current charging conditions of 1C and 2C. DC resistance was calculated from these recorded values, and the value was evaluated as “input / output characteristics”.
- the direct current resistance is small, it is possible to suppress a decrease in input / output and a decrease in capacitance, and it is possible to obtain the high stability as designed.
- Example 1 Petroleum coke having an HGI of 40 was pulverized to adjust the 50% particle size (D 50 ) to 15 ⁇ m. This was put into an Atchison furnace and heated at 3000 ° C. to obtain a core material made of graphite.
- the powdery isotropic petroleum pitch was dry-mixed in an amount of 1% by mass with respect to the core material, and heated at 1100 ° C. for 1 hour in an argon atmosphere to obtain composite graphite particles.
- the obtained composite graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.2 m 2 / g, an R value of 0.85, d 002 of 0.336 nm, and I 110 / I 004 of 0.46. there were.
- the battery obtained using this composite graphite particle has an initial discharge capacity of 331 mAh / g, an initial efficiency of 92%, a cycle capacity retention ratio of 0.92, a high rate cycle capacity retention ratio of 0.88, and an input / output capacity.
- the characteristic was 4.8 ⁇ .
- Example 2 Composite graphite particles were obtained in the same manner as in Example 1 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 50.
- the obtained composite graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.4 m 2 / g, an R value of 0.77, d 002 of 0.337 nm, and I 110 / I 004 of 0.44. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 337 mAh / g, an initial efficiency of 90%, and a cycle capacity retention of 0.93.
- Example 3 Composite graphite particles were obtained in the same manner as in Example 1 except that the amount of the isotropic petroleum pitch mixed with the graphite core material was changed to 5% by mass with respect to the core material.
- the obtained composite graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.1 m 2 / g, an R value of 0.91, d 002 of 0.338 nm, and I 110 / I 004 of 0.35. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 330 mAh / g, an initial efficiency of 91%, and a cycle capacity retention of 0.94.
- Example 4 Composite graphite particles were obtained in the same manner as in Example 1 except that the heating temperature in the Atchison furnace was changed to 2500 ° C.
- the obtained composite graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.4 m 2 / g, an R value of 0.87, d 002 of 0.340 nm, and I 110 / I 004 of 0.32. there were. Further, the battery obtained using this composite graphite particle had an initial discharge capacity of 320 mAh / g, an initial efficiency of 89%, and a cycle capacity retention of 0.90.
- Comparative Example 1 Petroleum coke having an HGI of 40 was pulverized to adjust the 50% particle size (D 50 ) to 15 ⁇ m. This was put into an Atchison furnace and heated at 3000 ° C. to obtain graphite particles.
- the obtained graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.6 m 2 / g, an R value of 0.08, d 002 of 0.335 nm, and I 110 / I 004 of 0.59. It was. Further, the battery obtained using this composite graphite particle had an initial discharge capacity of 333 mAh / g, an initial efficiency of 90%, and a cycle capacity retention of 0.80.
- Comparative Example 2 Graphite particles were obtained in the same manner as in Comparative Example 1 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 50.
- the obtained graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.8 m 2 / g, an R value of 0.06, d 002 of 0.335 nm, and I 110 / I 004 of 0.57. It was. Further, the battery obtained using this composite graphite particle had an initial discharge capacity of 336 mAh / g, an initial efficiency of 89%, and a cycle capacity retention of 0.82.
- Comparative Example 3 Composite graphite particles were obtained in the same manner as in Example 1 except that the heating temperature in the Atchison furnace was changed to 2000 ° C.
- the obtained composite graphite particles had a 50% particle size of 15 ⁇ m, a BET specific surface area of 1.6 m 2 / g, an R value of 0.96, d 002 of 0.349 nm, and I 110 / I 004 of 0.25. there were. Further, the battery obtained using this composite graphite particle had an initial discharge capacity of 299 mAh / g, an initial efficiency of 82%, and a cycle capacity retention of 0.82.
- Comparative Example 4 Composite graphite particles were obtained in the same manner as in Example 1 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 30.
- the obtained composite graphite particles had a 50% particle diameter of 15 ⁇ m, a BET specific surface area of 1.5 m 2 / g, an R value of 0.87, d 002 of 0.335 nm, and I 110 / I 004 of 0.41. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 326 mAh / g, an initial efficiency of 85%, and a cycle capacity retention of 0.85.
- Composite graphite particles were obtained in the same manner as in Example 1 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 70.
- the obtained composite graphite particles had a 50% particle size of 18 ⁇ m, a BET specific surface area of 3.1 m 2 / g, an R value of 0.62, d 002 of 0.336 nm, and I 110 / I 004 of 0.57. there were.
- the battery obtained using this composite graphite particle had an initial discharge capacity of 356 mAh / g, an initial efficiency of 80%, and a cycle capacity retention of 0.61.
- Example 5 has a core material made of graphite obtained by heat-treating petroleum coke having a grindability index of 35 to 60 at 2500 ° C. or more, and a carbonaceous layer existing on the surface thereof.
- the intensity ratio of the peak intensity (I G) in the range of the peak intensity (I D) and 1500 ⁇ 1620 cm -1 in the range of 1300 ⁇ 1400 cm -1 as measured by Raman spectrum I D / I G is 0.1 or more
- 50% particle size (D 50 ) in the volume-based cumulative particle size distribution measured by laser diffraction method is 10 ⁇ m or more and 30 ⁇ m or less
- density is 1.35 using a binder.
- Example 5 Petroleum coke having an HGI of 40 was pulverized to adjust the 50% particle size (D 50 ) to 6 ⁇ m. This was put into an Atchison furnace and heated at 3000 ° C. to obtain a core material made of graphite.
- the powdery isotropic petroleum pitch was dry-mixed in an amount of 1% by mass with respect to the core, and heated at 1100 ° C. for 1 hour in an argon gas atmosphere to obtain composite graphite particles.
- the obtained composite graphite particles had a 50% particle diameter of 6 ⁇ m, a BET specific surface area of 2.3 m 2 / g, an R value of 0.85, d 002 of 0.336 nm, and I 110 / I 004 of 0.44. there were.
- the battery obtained using this composite graphite particle has an initial discharge capacity of 330 mAh / g, an initial efficiency of 92%, a high rate cycle capacity retention of 0.82, an input / output characteristic of 3.8 ⁇ , and a cycle capacity retention.
- the rate was 0.85.
- Example 6 Composite graphite particles were obtained in the same manner as in Example 5 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 50.
- the obtained composite graphite particles had a 50% particle size of 6 ⁇ m, a BET specific surface area of 2.7 m 2 / g, an R value of 0.77, d 002 of 0.337 nm, and I 110 / I 004 of 0.42. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 335 mAh / g, an initial efficiency of 90%, a high rate cycle capacity retention of 0.83, and an input / output characteristic of 3.7 ⁇ .
- Example 7 Composite graphite particles were obtained in the same manner as in Example 5, except that the amount of isotropic petroleum pitch mixed with the core material made of graphite was changed to an amount of 5% by mass with respect to the core material.
- the obtained composite graphite particles had a 50% particle size of 6 ⁇ m, a BET specific surface area of 2.1 m 2 / g, an R value of 0.91, d 002 of 0.338 nm, and I 110 / I 004 of 0.32. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 328 mAh / g, an initial efficiency of 91%, a high rate cycle capacity retention of 0.85, and an input / output characteristic of 3.6 ⁇ .
- Example 8 Composite graphite particles were obtained in the same manner as in Example 5 except that the heating temperature in the Atchison furnace was changed to 2500 ° C.
- the obtained composite graphite particles had a 50% particle diameter of 6 ⁇ m, a BET specific surface area of 2.6 m 2 / g, an R value of 0.86, d 002 of 0.340 nm, and I 110 / I 004 of 0.35. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 318 mAh / g, an initial efficiency of 88%, a high rate cycle capacity retention of 0.80, and an input / output characteristic of 4.0 ⁇ .
- Comparative Example 7 Graphite particles were obtained in the same manner as in Comparative Example 6, except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 50.
- the obtained graphite particles had a 50% particle size of 6 ⁇ m, a BET specific surface area of 3.5 m 2 / g, an R value of 0.06, d 002 of 0.335 nm, and I 110 / I 004 of 0.51. It was. Further, the battery obtained using this composite graphite particle had an initial discharge capacity of 334 mAh / g, an initial efficiency of 89%, a high rate cycle capacity retention of 0.58, and an input / output characteristic of 5.2 ⁇ .
- Comparative Example 8 Composite graphite particles were obtained in the same manner as in Example 5 except that the heating temperature in the Atchison furnace was changed to 2000 ° C.
- the obtained composite graphite particles had a 50% particle size of 6 ⁇ m, a BET specific surface area of 2.5 m 2 / g, an R value of 0.96, d 002 of 0.349 nm, and I 110 / I 004 of 0.21. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 295 mAh / g, an initial efficiency of 82%, a high rate cycle capacity retention of 0.75, and an input / output characteristic of 3.2 ⁇ .
- Composite graphite particles were obtained in the same manner as in Example 5 except that the petroleum coke having an HGI of 40 was replaced with the petroleum coke having an HGI of 30.
- the obtained composite graphite particles had a 50% particle size of 6 ⁇ m, a BET specific surface area of 2.1 m 2 / g, an R value of 0.87, d 002 of 0.335 nm, and I 110 / I 004 of 0.38. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 325 mAh / g, an initial efficiency of 85%, a high rate cycle capacity retention of 0.74, and an input / output characteristic of 5.0 ⁇ .
- Composite graphite particles were obtained in the same manner as in Example 5, except that petroleum coke with HGI of 40 was replaced with petroleum coke with HGI of 70, and the 50% particle size was adjusted to 18 ⁇ m by pulverization.
- the obtained composite graphite particles had a 50% particle size of 7 ⁇ m, a BET specific surface area of 5.5 m 2 / g, an R value of 0.62, d 002 of 0.336 nm, and I 110 / I 004 of 0.53. there were.
- the battery obtained using the composite graphite particles had an initial discharge capacity of 345 mAh / g, an initial efficiency of 80%, a high rate cycle capacity retention of 0.52, and an input / output characteristic of 5.5 ⁇ .
- Example 1 has a core material made of graphite obtained by heat-treating petroleum coke having a grindability index of 35 to 60 at 2500 ° C. or more, and a carbonaceous layer present on the surface thereof.
- the intensity ratio of the peak intensity (I G) in the range of the peak intensity (I D) and 1500 ⁇ 1620 cm -1 in the range of 1300 ⁇ 1400 cm -1 as measured by Raman spectrum I D / I G is 0.1 or more
- 50% particle size (D 50 ) in the volume-based cumulative particle size distribution measured by laser diffraction method is 3 ⁇ m or more and less than 10 ⁇ m
- density is 1.35 using a binder.
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Abstract
Description
炭素系材料には、黒鉛などの結晶化度の高い炭素材料と、アモルファスカーボンなどの結晶化度の低い炭素材料とがある。これらはいずれもリチウムの挿入脱離反応が可能であることから、負極活物質に用いることができる。
低結晶性の炭素材料によって得られる電池は、高容量であるが、サイクル劣化が著しいことが知られている。一方、高結晶性の炭素材料によって得られる電池は、抵抗値が比較的に低く且つ安定なサイクル特性を有するが、電池容量が低いことが知られている。
例えば、特許文献1には、天然黒鉛とピッチを混合して不活性ガス雰囲気下において、900~1100℃で熱処理を行うことにより、天然黒鉛の表面を非晶質炭素で被覆させる技術が開示されている。
特許文献2には、芯材となる炭素材料をタールまたはピッチに浸漬させ、それを乾燥または900~1300℃で熱処理する技術が開示されている。
特許文献3には、天然黒鉛または鱗状人造黒鉛を造粒させて得られる黒鉛粒子の表面にピッチなどの炭素前駆体を混合し、不活性ガス雰囲気下で700~2800℃の温度範囲で焼成させる技術が開示されている。
さらに、特許文献4には、d002が0.3356nm、R値が約0.07、Lcが約50nmである鱗片状黒鉛を機械的外力で造粒球状化して得られる球状黒鉛粒子に、フェノール樹脂などの樹脂の加熱炭化物を被覆してなる複合黒鉛粒子を負極活物質として用いることが開示されている。
〔1〕 粉砕性指数が35~60である石油系コークスを2500℃以上3500℃以下で熱処理して得られる黒鉛からなる芯材と、 その表面に存在する炭素質層とを有する複合黒鉛粒子であって、
ラマン分光スペクトルで測定される1300~1400cm-1の範囲にあるピーク強度(ID)と1500~1620cm-1の範囲にあるピーク強度(IG)との強度比ID/IGが0.1以上であり、
レーザー回折法によって測定される体積基準累積粒度分布における50%粒子径(D50)が3μm以上30μm以下であり、且つ
バインダーを用いて密度1.35~1.45g/cm3に加圧成形した際にX線広角回折法によって測定される110回折ピークの強度(I110)と004回折ピークの強度(I004)との比I110/I004が0.2以上である、複合黒鉛粒子。
〔3〕 窒素吸着に基づくBET比表面積が0.2~30m2/gである〔1〕または〔2〕に記載の複合黒鉛粒子。
〔4〕 炭素質層の量が、芯材100質量部に対して0.05~10質量部である〔1〕~〔3〕のいずれかひとつに記載の複合黒鉛粒子。
〔5〕 炭素質層が、有機化合物を500℃以上の温度で熱処理して得られるものである〔1〕~〔4〕のいずれかひとつに記載の複合黒鉛粒子。
〔6〕 有機化合物が、石油系ピッチ、石炭系ピッチ、フェノール樹脂、ポリビニルアルコール樹脂、フラン樹脂、セルロース樹脂、ポリスチレン樹脂、ポリイミド樹脂およびエポキシ樹脂からなる群から選ばれる少なくとも1種の化合物である〔5〕に記載の複合黒鉛粒子。
〔8〕 レーザー回折法によって測定される体積基準累積粒度分布における50%粒子径(D50)が10μm以上30μm以下である、〔1〕~〔6〕のいずれかひとつに記載の複合黒鉛粒子。
有機化合物を黒鉛からなる芯材に付着させ、次いで
500℃以上の温度で熱処理することを含む、〔1〕~〔8〕のいずれかひとつに記載の複合黒鉛粒子の製法。
〔10〕 〔1〕~〔8〕のいずれかひとつに記載の複合黒鉛粒子、バインダーおよび溶媒を含有するスラリーまたはペースト。
〔11〕 天然黒鉛をさらに含有する〔10〕に記載のスラリーまたはペースト。
〔12〕 集電体と、〔1〕~〔8〕のいずれかひとつに記載の複合黒鉛粒子を含有する電極層とを有する積層体からなる電極シート。
〔13〕 電極層は天然黒鉛をさらに含有し、且つ
X線広角回折法によって測定される110回折ピークの強度(I110)と004回折ピークの強度(I004)との比I110/I004が0.1以上0.15以下である〔12〕に記載の電極シート。
〔14〕 〔12〕または〔13〕に記載の電極シートを負極として含むリチウムイオン電池。
本発明に係る好ましい実施形態の複合黒鉛粒子は、黒鉛からなる芯材と、その表面に存在する炭素質層とを有する。
原料として用いられる石油系コークスは、粉砕性指数、すなわちHGI(ASTM D409参照)が、通常、35~60、好ましくは37~55、より好ましくは40~50である。HGIがこの範囲にあると、出入力特性、低電流サイクル特性、高電流サイクル特性などに優れたリチウムイオン電池が得られる。
HGI=13+6.93W
なお、R値が大きいほど結晶性が低いことを示す。炭素質層のR値は、芯材の無い状態で、後述する炭素質層の形成方法と同じ方法を行って炭素質材を得、この炭素質材を測定して得た値である。R値の測定は、日本分光社製 NRS-5100を用いて、波長532nmおよび出力7.4mWのアルゴンレーザによる照射、分光器によるラマン散乱光測定という条件で行った。
なお、炭素質層の厚さは数十ナノメーター程度であるので、複合黒鉛粒子の50%粒子径と芯材の50%粒子径とは測定値としてほとんど変わらない。
本発明に係る好ましい実施形態の複合黒鉛粒子は、c軸方向の結晶子サイズLcが好ましくは50nm以上、より好ましくは75~150nmである。
なお、d002およびLcは、複合黒鉛粒子の粉末を、粉末X線回折装置(リガク社製、Smart Lab IV)にセットし、CuKα線にて出力30kV、200mAで回折ピークを測定し、JIS R 7651に従って算出した。
本発明に係る好ましい実施形態のスラリーまたはペーストは、前記複合黒鉛粒子とバインダーと溶媒とを含むものである。本発明に係るより好ましい実施形態のスラリーまたはペーストは、天然黒鉛をさらに含むものである。該スラリーまたはペーストは、前記複合黒鉛粒子とバインダーと溶媒と、好ましくはさらに天然黒鉛とを混練することによって得られる。スラリーまたはペーストは、必要に応じて、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。本発明に係る好ましい実施形態のスラリーまたはペーストは電池の電極、特に負極を作製するために好適に使用される。
たとえば、D507μmの中国産天然黒鉛を奈良機械製作所社製ハイブリダイザーNHS1型に投入し、ローター周速度60m/sにて3分間処理し、D5015μmの球状天然黒鉛粒子を得る。このようにして得られる球状天然黒鉛粒子50質量部と本願発明の実施態様の一例で得られる複合黒鉛粒子50質量部とを混合し、該混合物にバインダーを添加し、混練することによってスラリーまたはペーストを得ることができる。
本発明に係る好ましい実施形態の電極シートは、集電体と、本発明に係る複合黒鉛粒子を含有する電極層とを有する積層体からなるものである。該電極層は天然黒鉛をさらに含有することが好ましい。当該電極シートは、例えば、本発明に係るスラリーまたはペーストを集電体上に塗布し、乾燥し、加圧成形することによって得られる。
集電体としては、例えば、アルミニウム、ニッケル、銅などからなる箔、メッシュなどが挙げられる。集電体表面には導電性層が設けられていてもよい。該導電性層は、通常、導電性付与剤とバインダーとを含む。
スラリーまたはペーストの塗布方法は特に制限されない。スラリーまたはペーストの塗布厚(乾燥時)は、通常50~200μmである。塗布厚が大きくなりすぎると、規格化された電池容器に負極を収容できなくなることがある。
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を挙げることができる。加圧成形するときの圧力は約100MPa~約300MPa(1~3t/cm2程度)が好ましい。このようにして得られる負極は、リチウムイオン電池に好適である。
本発明に係る好ましい実施形態のリチウムイオン電池は、本発明に係る電極シートを負極として含むものである。本発明に係る好ましい実施形態のリチウムイオン電池の正極には、リチウムイオン電池に従来から使われていたものを用いることができる。正極に用いられる活物質としては、例えば、LiNiO2、LiCoO2、LiMn2O4などが挙げられる。
窒素吸着量の測定に基づきBET法により算出した。
試料を極小型スパーテル2杯分、および非イオン性界面活性剤(トリトン-X)2滴を水50mlに添加し、超音波で3分間分散させた。得られた分散液をレーザー回折式粒度分布測定器(セイシン企業製、LMS-2000S)にセットし、体積基準の粒度分布を測定した。該測定値からD10、D50、およびD90を算出した。
粒度1.18~600μmにそろえた試料50gをハードグローブ粉砕試験機にセットした。5~20rpmで60回回転させたところで装置を止めた。処理した試料を10分間、5分間、および5分間の合計3回(計20分間)75μmの篩にかけた。篩下の重量W[g]を計測した。下式で粉砕性指数を算出した。
HGI=13+6.93W
粉末X線回折装置(リガク社製、Smart Lab IV)で、CuKα線にて出力30kV、200mAでX線回折ピークを測定した。002回折ピークからJIS R 7651に従ってd002を算出した。
1質量%カルボキシメチルセルロース水溶液を少量ずつ黒鉛粒子に加えながら混練し固形分1.5質量%となるようにした。これにバインダーとしてポリフッ化ビニリデン(クレハ製、KFポリマー W#9300)1.5質量%を加えてさらに混錬し、十分な流動性を持つようにさらに純水を加え、脱泡ニーダー(日本精機製作所製、NBK-1)を用いて500rpmで5分間混練を行い、ペーストを得た。自動塗工機とクリアランス250μmのドクターブレードを用いて、前記ペーストを集電体上に塗布した。ペーストが塗布された集電体を約80℃のホットプレート上に置いて水分を除去した。その後、真空乾燥機にて120℃で6時間乾燥させた。乾燥後、黒鉛粒子とバインダーの合計質量と体積とから割り出される電極密度が1.40±0.05g/cm3になるように一軸プレスにより加圧成形し、電極シートを得た。
得られた電極シートを適当な大きさに切り取り、XRD測定用のガラスセルに貼り付け、広角X線回折ピークを測定した。004回折ピークの強度および110回折ピークの強度との比I110/I004を算出した。
日本分光社製 NRS-5100を用いて、波長532nmおよび出力7.4mWのアルゴンレーザを試料黒鉛に照射し、ラマン散乱光を分光器で測定した。測定されたラマン分光スペクトルから、1300~1400cm-1の範囲にあるピーク強度(ID)と1500~1620cm-1の範囲にあるピーク強度(IG)との強度比ID/IGを算出した。
黒鉛粒子を8.00g、導電助材としてアセチレンブラック(電気化学社製、HS-100)を1.72g、バインダーとしてポリフッ化ビニリデン(クレハ製、KFポリマー W#9300)を4.30gそれぞれ秤量した。これらを充分に混合した後にN-メチル-2-ピロリドン9.32gを徐々に添加し脱泡ニーダー(日本精機製作所製、NBK-1)を用いて混練を行い、ペーストを得た。なおペーストに気相法炭素繊維を添加する場合は、この混練の前に添加する。このペーストをクリアランス150μmのドクターブレードで20μm厚のCu箔上に塗工した。ペーストが塗布された集電体を約80℃のホットプレート上に置いてN-メチル-2-ピロリドンを除去した。その後、真空乾燥機にて90℃で1時間乾燥させた。乾燥後、黒鉛粒子とバインダーの合計質量と体積とから割り出される電極密度が1.50±0.05g/cm3になるように一軸プレスにより加圧成形し、負極を得た。得られた負極をφ15mmの大きさに切り出した。その後、切り出した負極を1.2t/cm2で10秒間プレスし、その塗膜の平均厚さを測定したところ70~80μmであった。また、塗膜のローディングレベルは6.5~7.5mg/cm2であった。
アルゴンガスで充満され、露点が-75℃以下に制御されたグローブボックス内に前記負極を導入した。負極をコインセル(宝泉製 CR2320)に置き電解液(1M LiPF6 エチレンカーボネート(EC):メチルエチルカーボネート(MEC)=40:60〔体積比〕)を浸透させた。その上にφ20mmで切り出したセパレーター(セルガード2400)、φ17.5mmで切り出した3mm厚のリチウム箔の順に載せた。その上から、ガスケットを取り付けたキャップをし、かしめ器によりかしめた。
グローブボックスから取り出し、24時間室温で静置した。その後、0.2mAで定電流充電し、4.5Vに到達後、4.5Vで定電圧充電を行い、0.2mAになった時点で充電を止めた。次いで0.2mAで定電流放電し、2.5Vに到達した時点で放電を止め、10分間休止した。
この充放電サイクルにおける初回充電容量および初回放電容量に基づき、下式にて初期効率を算出した。
(初期効率)=(初回放電容量)/(初回充電容量)
露点-80℃以下の乾燥アルゴンガス雰囲気下に保ったグローブボックス内で下記の操作を実施した。
正極材(Unicore社製三元系正極材 Li(Ni,Mn,Co)O2 )90質量%、導電性付与剤(TIMCAL社製、C45)2質量%、導電性付与剤(TIMCAL社製、KS6L)3質量%、およびポリフッ化ビニリデン(クレハ製、KFポリマー W#1300)5質量%(固形分)を混合した。その後、これにN-メチル-2-ピロリドン(キシダ化学製)を加えて混錬し、ペーストを得た。 自動塗工機を用いて、前記ペーストをクリアランス200μmのドクターブレードで20μm厚のアルミニウム箔に塗工して、正極を作製した。
ラミネート外装材の中に、上記負極と正極とをポリプロピレン製セパレーター(東燃化学社製、セルガード2400)を介して積層した。次に、電解液を注入し、真空中でヒートシールを行い、評価用のラミネートセルを得た。
初回と2回目の充放電サイクルは、次のようにして行った。レストポテンシャルから4.2Vまで5.5mAで定電流充電し、次に4.2Vで定電圧充電を行い、電流値が0.27mAに低下した時点で充電を止めた。次いで、5.5mAで定電流放電を行い、電圧2.7Vでカットオフした。
そして、3回目の放電容量に対する200回目の放電容量の割合を、「サイクル容量保持率」として評価を行った。
露点-80℃以下の乾燥アルゴンガス雰囲気下に保ったグローブボックス内で下記の操作を実施した。
正極材(Unicore社製三元系正極材 Li(Ni,Mn,Co)O2 )90質量%、導電性付与剤(TIMCAL社製、C45)2質量%、導電性付与材(TIMCAL社製、KS6L)3質量%、およびポリフッ化ビニリデン(クレハ製、KFポリマー W#1300)5質量%(固形分)を混合した。その後、これにN-メチル-2-ピロリドン(キシダ化学製)を加えて混錬し、ペーストを得た。 自動塗工機を用いて、前記ペーストをクリアランス200μmのドクターブレードで20μm厚のアルミニウム箔に塗工して、正極を作製した。
ラミネート外装材の中に、上記負極と正極とをポリプロピレン製セパレーター(東燃化学社製、セルガード2400)を介して積層した。次に、電解液を注入し、真空中でヒートシールを行い、評価用のラミネートセルを得た。
初回と2回目の充放電サイクルは、次のようにして行った。レストポテンシャルから4.2Vまで5.5mAで定電流充電し、次に4.2Vで定電圧充電を行い、電流値が0.27mAに低下した時点で充電を止めた。次いで、5.5mAで定電流放電を行い、電圧2.7Vでカットオフした。
そして、3回目の放電容量に対する200回目の放電容量の割合を、「ハイレートサイクル容量保持率」として評価を行った。
上記で作製したラミネートセルを用いて、以下の方法で出入力特性を評価した。
まず、5.5mAで定電流放電を行った。そしてレストポテンシャルから4.2Vまで5.5mAで定電流充電し、次に4.2Vで定電圧充電を行い、電流値が0.27mAに低下した時点で充電を止めた。次いで0.55mA(0.1Cに相当)で2時間定電流放電を行った。放電後の電圧値を記録した。
1.1mA(0.2Cに相当)で5秒間定電流放電を行い、30分間休止した。その後0.11mA(0.02Cに相当)で定電流充電し、次に4.2Vで定電圧充電を行った。50秒間で充電を停止させ、電圧を5秒間放電させる前の状態に戻した。
上記の1.1mA(0.2Cに相当)5秒間の定電流放電、30分間休止、およびその後の定電流充電および定電圧充電を50秒間行う充放電サイクルを、0.2C、0.5C、1C、および2Cの定電流充電の条件で行った。それらのときの電流値および電圧値を記録した。
さらに上記の5秒間定電流放電を、0.55mA(0.1Cに相当)で3.5時間、5時間、6.5時間、または8時間で行い、その際の0.2C、0.5C、1Cおよび2Cの定電流充電の条件における、電流値と電圧値を記録した。
記録したそれらの値から直流抵抗を算出し、その値を「出入力特性」として評価を行った。直流抵抗が小さいと出入力の低下を抑えられ、容量の低下も小さく、設計で目指したとおりの高い安定性を得ることができる。
HGIが40である石油系コークスを粉砕して50%粒子径(D50)を15μmに調整した。これをアチソン炉に入れ、3000℃にて加熱し、黒鉛からなる芯材を得た。
これに粉末状の等方性石油系ピッチを芯材に対して1質量%となる量で乾式混合し、アルゴン雰囲気下、1100℃にて1時間加熱して、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.2m2/g、R値が0.85、d002が0.336nm、I110/I004が0.46であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が331mAh/g、初期効率が92%、サイクル容量保持率が0.92、ハイレートサイクル容量保持率が0.88、出入力特性が4.8Ωであった。
HGIが40である石油系コークスをHGIが50である石油系コークスに替えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.4m2/g、R値が0.77、d002が0.337nm、I110/I004が0.44であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が337mAh/g、初期効率が90%、サイクル容量保持率が0.93であった。
黒鉛からなる芯材に混合させる等方性石油系ピッチの量を芯材に対して5質量%となる量に変えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.1m2/g、R値が0.91、d002が0.338nm、I110/I004が0.35であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が330mAh/g、初期効率が91%、サイクル容量保持率が0.94であった。
アチソン炉による加熱温度を2500℃に変えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.4m2/g、R値が0.87、d002が0.340nm、I110/I004が0.32であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が320mAh/g、初期効率が89%、サイクル容量保持率が0.90であった。
HGIが40である石油系コークスを粉砕して50%粒子径(D50)を15μmに調整した。これをアチソン炉に入れ、3000℃にて加熱して、黒鉛粒子を得た。
得られた黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.6m2/g、R値が0.08、d002が0.335nm、I110/I004が0.59であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が333mAh/g、初期効率が90%、サイクル容量保持率が0.80であった。
HGIが40である石油系コークスをHGIが50である石油系コークスに替えた以外は比較例1と同じ方法で、黒鉛粒子を得た。
得られた黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.8m2/g、R値が0.06、d002が0.335nm、I110/I004が0.57であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が336mAh/g、初期効率が89%、サイクル容量保持率が0.82であった。
アチソン炉による加熱温度を2000℃に変えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.6m2/g、R値は0.96、d002が0.349nm、I110/I004が0.25であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が299mAh/g、初期効率が82%、サイクル容量保持率が0.82であった。
HGIが40である石油系コークスをHGIが30である石油系コークスに替えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が15μm、BET比表面積が1.5m2/g、R値が0.87、d002が0.335nm、I110/I004が0.41であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が326mAh/g、初期効率が85%、サイクル容量保持率が0.85であった。
HGIが40である石油系コークスをHGIが70である石油系コークスに替えた以外は実施例1と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が18μm、BET比表面積が3.1m2/g、R値が0.62、d002が0.336nm、I110/I004が0.57であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量は356mAh/g、初期効率は80%、サイクル容量保持率は0.61であった。
HGIが40である石油系コークスを粉砕して50%粒子径(D50)を6μmに調整した。これをアチソン炉に入れ、3000℃にて加熱し、黒鉛からなる芯材を得た。
これに粉末状の等方性石油系ピッチを芯材に対して1質量%となる量で乾式混合し、アルゴンガス雰囲気下、1100℃にて1時間加熱して、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.3m2/g、R値が0.85、d002が0.336nm、I110/I004が0.44であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が330mAh/g、初期効率が92%、ハイレートサイクル容量保持率が0.82、出入力特性が3.8Ω、サイクル容量保持率は0.85であった。
HGIが40である石油系コークスをHGIが50である石油系コークスに替えた以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.7m2/g、R値が0.77、d002が0.337nm、I110/I004が0.42であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が335mAh/g、初期効率が90%、ハイレートサイクル容量保持率が0.83、出入力特性が3.7Ωであった。
黒鉛からなる芯材に混合させる等方性石油系ピッチの量を芯材に対して5質量%となる量に変えた以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.1m2/g、R値が0.91、d002が0.338nm、I110/I004が0.32であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が328mAh/g、初期効率が91%、ハイレートサイクル容量保持率が0.85、出入力特性が3.6Ωであった。
アチソン炉による加熱温度を2500℃に変えた以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.6m2/g、R値が0.86、d002が0.340nm、I110/I004が0.35であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が318mAh/g、初期効率が88%、ハイレートサイクル容量保持率が0.80、出入力特性が4.0Ωであった。
HGIが40である石油系コークスを粉砕して50%粒子径(D50)を6μmに調整した。これをアチソン炉に入れ、3000℃にて加熱して、黒鉛粒子を得た。
得られた黒鉛粒子は、50%粒子径が6μm、BET比表面積が3.0m2/g、R値が0.08、d002が0.335nm、I110/I004が0.56であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が331mAh/g、初期効率が90%、ハイレートサイクル容量保持率が0.61、出入力特性が5.3Ωであった。
HGIが40である石油系コークスをHGIが50である石油系コークスに替えた以外は比較例6と同じ方法で、黒鉛粒子を得た。
得られた黒鉛粒子は、50%粒子径が6μm、BET比表面積が3.5m2/g、R値が0.06、d002が0.335nm、I110/I004が0.51であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が334mAh/g、初期効率が89%、ハイレートサイクル容量保持率が0.58、出入力特性が5.2Ωであった。
アチソン炉による加熱温度を2000℃に変えた以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.5m2/g、R値が0.96、d002が0.349nm、I110/I004が0.21であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が295mAh/g、初期効率が82%、ハイレートサイクル容量保持率が0.75、出入力特性が3.2Ωであった。
HGIが40である石油系コークスをHGIが30である石油系コークスに替えた以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が6μm、BET比表面積が2.1m2/g、R値が0.87、d002が0.335nm、I110/I004が0.38であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が325mAh/g、初期効率が85%、ハイレートサイクル容量保持率が0.74、出入力特性が5.0Ωであった。
HGIが40である石油系コークスをHGIが70である石油系コークスに替え、粉砕による調整で50%粒子径を18μmにした以外は実施例5と同じ方法で、複合黒鉛粒子を得た。
得られた複合黒鉛粒子は、50%粒子径が7μm、BET比表面積が5.5m2/g、R値が0.62、d002が0.336nm、I110/I004が0.53であった。
また、この複合黒鉛粒子を用いて得られた電池は、初期放電容量が345mAh/g、初期効率が80%、ハイレートサイクル容量保持率が0.52、出入力特性が5.5Ωであった。
Claims (14)
- 粉砕性指数が35~60である石油系コークスを2500℃以上3500℃以下で熱処理して得られる黒鉛からなる芯材と、 その表面に存在する炭素質層とを有する複合黒鉛粒子であって、
ラマン分光スペクトルで測定される1300~1400cm-1の範囲にあるピーク強度(ID)と1500~1620cm-1の範囲にあるピーク強度(IG)との強度比ID/IGが0.1以上であり、
レーザー回折法によって測定される体積基準累積粒度分布における50%粒子径(D50)が3μm以上30μm以下であり、且つ
バインダーを用いて密度1.35~1.45g/cm3に加圧成形した際にX線広角回折法によって測定される110回折ピークの強度(I110)と004回折ピークの強度(I004)との比I110/I004が0.2以上である、複合黒鉛粒子。 - X線広角回折法によって測定される002回折ピークに基づくd002が0.334nm以上0.342nm以下である請求項1に記載の複合黒鉛粒子。
- 窒素吸着に基づくBET比表面積が0.2~30m2/gである請求項1または2に記載の複合黒鉛粒子。
- 炭素質層の量が、芯材100質量部に対して0.05~10質量部である請求項1~3のいずれかひとつに記載の複合黒鉛粒子。
- 炭素質層が、有機化合物を500℃以上の温度で熱処理して得られるものである請求項1~4のいずれかひとつに記載の複合黒鉛粒子。
- 有機化合物が、石油系ピッチ、石炭系ピッチ、フェノール樹脂、ポリビニルアルコール樹脂、フラン樹脂、セルロース樹脂、ポリスチレン樹脂、ポリイミド樹脂およびエポキシ樹脂からなる群から選ばれる少なくとも1種の化合物である請求項5に記載の複合黒鉛粒子。
- レーザー回折法によって測定される体積基準累積粒度分布における50%粒子径(D50)が3μm以上10μm未満である、請求項1~6のいずれかひとつに記載の複合黒鉛粒子。
- レーザー回折法によって測定される体積基準累積粒度分布における50%粒子径(D50)が10μm以上30μm以下である、請求項1~6のいずれかひとつに記載の複合黒鉛粒子。
- 粉砕性指数が35~60である石油系コークスを2500℃以上3500℃以下で熱処理して黒鉛からなる芯材を得、
有機化合物を黒鉛からなる芯材に付着させ、次いで
500℃以上の温度で熱処理することを含む、請求項1~8のいずれかひとつに記載の複合黒鉛粒子の製法。 - 請求項1~8のいずれかひとつに記載の複合黒鉛粒子、バインダーおよび溶媒を含有するスラリーまたはペースト。
- 天然黒鉛をさらに含有する請求項10に記載のスラリーまたはペースト。
- 集電体と、請求項1~8のいずれかひとつに記載の複合黒鉛粒子を含有する電極層とを有する積層体からなる電極シート。
- 電極層は天然黒鉛をさらに含有し、且つ
X線広角回折法によって測定される110回折ピークの強度(I110)と004回折ピークの強度(I004)との比I110/I004が0.1以上0.15以下である請求項12に記載の電極シート。 - 請求項12または13に記載の電極シートを負極として含むリチウムイオン電池。
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EP2908366B1 (en) * | 2012-10-12 | 2018-12-19 | Showa Denko K.K. | Method for the production of a composite carbon particle |
US9614218B2 (en) | 2012-10-12 | 2017-04-04 | Showa Denko K.K. | Composite carbon particle and lithium-ion secondary cell using same |
WO2014057690A1 (ja) * | 2012-10-12 | 2014-04-17 | 昭和電工株式会社 | 複合炭素粒子およびそれを用いたリチウムイオン二次電池 |
WO2015016182A1 (ja) * | 2013-07-29 | 2015-02-05 | 昭和電工株式会社 | 炭素材料、電池電極用材料、及び電池 |
CN105408248A (zh) * | 2013-07-29 | 2016-03-16 | 昭和电工株式会社 | 碳材料、电池电极用材料以及电池 |
JPWO2015016182A1 (ja) * | 2013-07-29 | 2017-03-02 | 昭和電工株式会社 | 炭素材料、電池電極用材料、及び電池 |
KR20180088497A (ko) * | 2013-07-29 | 2018-08-03 | 쇼와 덴코 가부시키가이샤 | 탄소 재료, 전지 전극용 재료, 및 전지 |
US10144646B2 (en) | 2013-07-29 | 2018-12-04 | Showa Denko K.K. | Carbon material, material for a battery electrode, and battery |
KR101971448B1 (ko) | 2013-07-29 | 2019-04-23 | 쇼와 덴코 가부시키가이샤 | 탄소 재료, 전지 전극용 재료, 및 전지 |
US10377634B2 (en) | 2013-07-29 | 2019-08-13 | Showa Denko K.K. | Carbon material, material for a battery electrode, and battery |
US10305108B2 (en) | 2014-03-31 | 2019-05-28 | Nec Energy Devices, Ltd. | Graphite-based active material, negative electrode, and lithium ion secondary battery |
WO2015182560A1 (ja) * | 2014-05-30 | 2015-12-03 | 昭和電工株式会社 | 炭素材料、その製造方法及びその用途 |
JP5877284B1 (ja) * | 2014-05-30 | 2016-03-02 | 昭和電工株式会社 | 炭素材料、その製造方法及びその用途 |
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JP6126902B2 (ja) | 2017-05-10 |
TW201339093A (zh) | 2013-10-01 |
JP2013179074A (ja) | 2013-09-09 |
US20140057166A1 (en) | 2014-02-27 |
KR20130097224A (ko) | 2013-09-02 |
DE112012004320T5 (de) | 2014-07-03 |
CN103492316B (zh) | 2015-03-18 |
JP5270050B1 (ja) | 2013-08-21 |
JPWO2013084506A1 (ja) | 2015-04-27 |
KR101361567B1 (ko) | 2014-02-12 |
CN103492316A (zh) | 2014-01-01 |
TWI482734B (zh) | 2015-05-01 |
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