WO2018110645A1 - Graphite material and method for producing same - Google Patents

Graphite material and method for producing same Download PDF

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Publication number
WO2018110645A1
WO2018110645A1 PCT/JP2017/044890 JP2017044890W WO2018110645A1 WO 2018110645 A1 WO2018110645 A1 WO 2018110645A1 JP 2017044890 W JP2017044890 W JP 2017044890W WO 2018110645 A1 WO2018110645 A1 WO 2018110645A1
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Prior art keywords
graphite
graphite material
material according
value
producing
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PCT/JP2017/044890
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French (fr)
Japanese (ja)
Inventor
旭 汪
俊介 吉岡
文香 井門
安顕 脇坂
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昭和電工株式会社
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Priority to JP2018556740A priority Critical patent/JP6650656B2/en
Publication of WO2018110645A1 publication Critical patent/WO2018110645A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/205—Preparation
    • 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
    • H01M4/58—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
    • 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 graphite material suitable for a negative electrode of a lithium ion secondary battery excellent in a large current load characteristic and a direct current resistance characteristic, and a manufacturing method thereof.
  • a lithium salt such as lithium cobaltate is generally used for the positive electrode active material
  • a carbonaceous material such as graphite is used for the negative electrode active material.
  • Graphite includes natural graphite and artificial graphite.
  • Patent Document 1 discloses a method of coating artificial carbon on the surface of natural graphite processed into a spherical shape.
  • Patent Document 2 discloses a graphitized product of mesocarbon spherules.
  • Patent Document 3 discloses a graphite material in which a plurality of flat graphite particles are aggregated or bonded so that their orientation planes are non-parallel.
  • Patent Document 4 discloses a negative electrode material using so-called hard carbon or amorphous carbon.
  • Patent Document 5 discloses a carbon fiber vacuum-heated with a strong oxidizing agent.
  • Patent Document 6 discloses a graphite material that is preliminarily mixed with a Li compound and then heat-fired.
  • Patent Document 7 discloses immersing a graphite material in a solution containing a nonmetallic organic compound.
  • Japanese Patent No. 3534391 (US6632569 B1) Japanese Patent Laid-Open No. 4-190555 Japanese Patent No. 3361510 (US6344296 B1) JP-A-7-320740 (US5587255 A) JP-A-5-299074 Japanese Patent Laid-Open No. 5-135802 JP-A-10-270045 (CA2230948CAA1)
  • the materials manufactured by the methods described in Patent Documents 1 to 3 can cope with electric capacity at low current density and medium-term cycle characteristics when using batteries in mobile applications, but for large battery applications. It is very difficult to cope with electric capacity at a large current density and long-term cycle characteristics when used.
  • the negative electrode material described in Patent Document 4 has a volume energy density that is too low and is very expensive, so it is used only for some special large batteries.
  • a strong oxidizing agent is used and heated at a high temperature.
  • the treated graphite material has a low electric capacity and poor cycle performance, so that it is insufficient for use in a secondary battery.
  • the electric capacity is insufficient.
  • the present inventors have developed a graphite material suitable for producing a negative electrode of a lithium ion secondary battery excellent in large current load characteristics and DC resistance characteristics, and a production method thereof.
  • the headline and the present invention were completed.
  • the present invention relates to the following graphite materials (1) to (7) and methods for producing the graphite materials (8) to (10).
  • the surface carbon atomic ratio concentration measured by X-ray photoelectron spectroscopy (XPS) is 98.3% or more, and the R value (RE) and graphite of the graphite edge surface measured by Raman spectroscopic analysis using an argon laser
  • XPS X-ray photoelectron spectroscopy
  • a carbon material for battery electrodes comprising the graphite material as described in any one of 1 to 4 above.
  • a secondary battery comprising the battery electrode carbon material as described in 5 above.
  • a method for producing a graphite material comprising a step of mixing a solution containing a surface treatment compound and raw graphite particles, and a step of performing a heat treatment in an inert atmosphere, wherein the graphite material uses an argon laser.
  • a method for producing a graphite material wherein the R value (RE) of the graphite edge surface and the R value (RB) of the graphite basal surface measured by Raman spectroscopy satisfy the following requirements (c) and (d).
  • the surface treatment compound is transition metal chloride, transition metal nitrate, transition metal sulfate, transition metal phosphate, nitric acid, sulfuric acid, phosphoric acid, or a mixture thereof (excluding a mixture of nitric acid and sulfuric acid) 10.
  • the method for producing a graphite material as described in any one of 7 to 9 above, wherein
  • the graphite material of the present invention When the graphite material of the present invention is used as a negative electrode material of a lithium ion secondary battery, it is possible to obtain a battery having excellent electric capacity, coulomb efficiency, cycle characteristics and energy density, and particularly having a large current load characteristic and a low DC resistance value. . Moreover, the graphite material of the present invention is excellent in economy and mass productivity, and can be produced by a safe method.
  • the graphite material according to one embodiment of the present invention preferably has a surface carbon atomic ratio concentration of 98.3% or more as measured by X-ray photoelectron spectroscopy (XPS). More preferably, it is 98.7% or more, More preferably, it is 99.1% or more.
  • XPS X-ray photoelectron spectroscopy
  • the graphite material according to one embodiment of the present invention has the following requirements (a) for the R value (RE) of the graphite edge surface and the R value (RB) of the graphite basal surface measured by Raman spectroscopy using an argon laser: Satisfies (b).
  • the R value represents the ratio (ID / IG) of the intensity (ID) of the D peak appearing at the center wave number 1344 to 1348 cm ⁇ 1 to the intensity (IG) of the G peak appearing at the center wave number 1574 to 1576 cm ⁇ 1. .
  • the graphite material according to one embodiment of the present invention has 0.19 ⁇ RE ⁇ 0.54 and 0.10 ⁇ RB ⁇ 0.14 with respect to the RE that is the R value of the edge surface and the RB that is the R value of the basal surface. It is preferable that 0.20 ⁇ RE ⁇ 0.54 and 0.11 ⁇ RB ⁇ 0.14, and 0.25 ⁇ RE ⁇ 0.54 and 0.12 ⁇ RB ⁇ 0. More preferably, it is 14. When RE and RB are within such a range, the insertion positions of Li ions increase and the electrochemical reaction speed increases.
  • the graphite material in a preferred embodiment of the present invention preferably has a 50% cumulative diameter (D50) in a volume-based cumulative particle size distribution measured in a solvent using a laser diffraction type particle size distribution measuring apparatus of 2 ⁇ m or more and 55 ⁇ m or less. It is more preferably 3 ⁇ m or more and 40 ⁇ m or less, and most preferably 5 ⁇ m or more and 35 ⁇ m or less.
  • a laser diffraction type particle size distribution measuring device for example, Mastersizer (registered trademark) manufactured by Malvern can be used.
  • the graphite material in a preferred embodiment of the present invention does not substantially contain particles having a particle size of 0.5 ⁇ m or less. Particles of 0.5 ⁇ m or less have a large active point on the surface and reduce the initial efficiency of the battery.
  • substantially not contained means that particles having a particle size of 0.5 ⁇ m or less are 0.1% by mass or less. The content of particles of 0.5 ⁇ m or less can be measured by a laser diffraction particle size distribution measuring apparatus as described above.
  • the BET specific surface area is measured by a general method of measuring the amount of adsorption / desorption of gas per unit mass.
  • NOVA-1200 can be used as the measuring device.
  • the BET specific surface area (SBET) is preferably 1.0 m 2 / g or more and 8.0 m 2 / g or less, more preferably 1.2 m 2 / g or more and 7.0 m 2 / g or less, and 1.5 m 2 / g or more. Most preferred is 4.5 m 2 / g or less.
  • the graphite material preferably has an average interplanar spacing d002 of (002) planes of 0.3356 nm or more and 0.3375 nm or less by X-ray diffraction.
  • the thickness Lc in the C-axis direction of the crystal is preferably 30 nm or more and 1000 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or more and 100 nm or less.
  • the crystallite thickness La in the a-axis direction is preferably 100 nm or more.
  • d002 La and Lc can be measured by a known method using a powder X-ray diffraction (XRD) method (Michio Inagaki, “Carbon”, 1963, No. 36, pp. 25-34, Iwashita et al. , Carbon vol.42 (2004), p.701-714).
  • XRD powder X-ray diffraction
  • a solution containing a compound for introducing defects on the surface of raw material graphite particles (abbreviated as “surface treatment compound”) and raw material graphite particles are mixed.
  • a process for producing a graphite material comprising a process and a process of performing a heat treatment in an inert atmosphere. By adopting such a process, defects are introduced into the surface of the raw graphite particles.
  • Raman spectroscopic analysis is used as an index for measuring the amount of defects introduced into the edge and basal surfaces of graphite.
  • multipoint measurement of Raman spectroscopic analysis is performed, and the intensity ratio (ID / IG) is calculated from the G peak intensity and D peak intensity of the five-point averaged spectrum on each of the edge surface and the basal surface.
  • the RE that is the R value of the edge surface and the RB that is the R value of the basal surface can be calculated.
  • the R value represents the ratio (ID / IG) of the intensity (ID) of the D peak appearing at the center wave number 1344 to 1348 cm ⁇ 1 to the intensity (IG) of the G peak appearing at the center wave number 1574 to 1576 cm ⁇ 1.
  • RE which is the R value of the edge surface
  • RE of graphite material / RE of raw graphite particles is preferably 1.1 to 4.0, more preferably 1.5 to 4.0. More preferably, it is 8 to 4.0.
  • RB which is the R value of the basal plane
  • (RB of graphite material / RB of raw graphite particles) is preferably 1.2 to 2.0, more preferably 1.4 to 2.0, and 1.6 More preferably, ⁇ 2.0.
  • (RB of graphite material / RB of raw graphite particles) is 1.2 to 2.0, and (RE of graphite material / RE of raw graphite particles) is 1.1 to 4.0. More preferably, (RB of graphite material / RB of raw graphite particles) is 1.4 to 2.0, and (RE of graphite material / RE of raw graphite particles) is 1.5 to 4.0. . More preferably, (RB of graphite material / RB of raw graphite particle) is 1.6 to 2.0, and (RE of graphite material / RE of raw graphite particle) is 1.8 to 4.0. .
  • each R value is controlled to be within the above range, moderate defects are introduced on the surface of the graphite, the insertion positions of Li ions are increased, and the electrochemical reaction speed is increased, while the stability of the carbon material is improved. There is no effect, and long-term cycle characteristics are also good.
  • the graphite surface treatment compound can be selected from transition metal chlorides, transition metal nitrates, transition metal sulfates, transition metal phosphates, nitric acid, sulfuric acid, and phosphoric acid. These compounds may be used alone or in combination of two or more. However, the use of mixed acid mixed with nitric acid and sulfuric acid is excluded. This is because the mixed acid of nitric acid and sulfuric acid is too oxidizable and is not suitable for the surface treatment of the present invention. Moreover, as a transition metal, iron, cobalt, nickel, copper, and zinc can be used, for example.
  • the molar ratio in the case of mixing the graphite surface treatment compound and the raw material graphite particles is preferably 1: 1000 to 1: 100 of compound: graphite. More preferably, it is 1: 800 to 1: 100, and still more preferably 1: 500 to 1: 100. It is preferable that the solvent of a solution contains water and a volatile organic solvent. The boiling point of the volatile organic solvent is preferably 50 to 85 ° C. More preferably, it is 55 to 80 ° C., and most preferably 60 to 80 ° C.
  • the drying temperature is preferably 70 to 120 ° C, more preferably 80 to 110 ° C, and further preferably 90 to 110 ° C.
  • the mixture is heat treated in an inert atmosphere.
  • the heat treatment temperature is preferably 400 to 1300 ° C, more preferably 500 to 1100 ° C, and further preferably 500 to 1000 ° C.
  • the heat treatment time is preferably 0.5 to 5 hours, more preferably 1 to 4 hours, and further preferably 1.5 to 3 hours.
  • the graphite material obtained after the heat treatment is preferably washed, filtered and dried.
  • the carbon material for battery electrodes in a preferred embodiment of the present invention comprises the above graphite material.
  • the graphite material is used as a carbon material for battery electrodes, a battery electrode with reduced DC resistance and improved charge / discharge rate can be obtained while maintaining high capacity, high coulomb efficiency, and high cycle characteristics.
  • a carbon material for battery electrodes it can use, for example as a negative electrode active material and negative electrode electroconductivity imparting material of a lithium ion secondary battery.
  • the carbon material for battery electrodes in a preferred embodiment of the present invention may be used by mixing other graphite material and the graphite material, or may use only the graphite material.
  • the electrode paste in a preferred embodiment of the present invention comprises the battery electrode carbon material and a binder.
  • This electrode paste is obtained by kneading the carbon material for battery electrodes and a binder.
  • known apparatuses such as a ribbon mixer, a screw kneader, a Spartan rewinder, a ladyge mixer, a planetary mixer, and a universal mixer can be used.
  • the electrode paste can be formed into a sheet shape, a pellet shape, or the like.
  • binder used for the electrode paste examples include fluorine-based polymers such as polyvinylidene fluoride and polytetrafluoroethylene, and known binders such as rubbers such as SBR (styrene butadiene rubber).
  • the amount of the binder used is suitably 1 to 30 parts by mass with respect to 100 parts by mass of the carbon material for battery electrodes, and particularly preferably 3 to 20 parts by mass.
  • a solvent can be used when kneading.
  • the solvent include known solvents suitable for each binder, such as toluene and N-methylpyrrolidone in the case of a fluoropolymer; water in the case of SBR; and dimethylformamide and isopropanol.
  • 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 electrode in a preferred embodiment of the present invention comprises a molded body of the electrode paste.
  • the electrode is obtained, for example, by applying the electrode paste onto a current collector, drying, and pressure-molding.
  • the current collector examples include aluminum, nickel, copper, stainless steel foil, mesh, and the like.
  • the coating thickness of the paste is usually 50 to 200 ⁇ m. If the coating thickness becomes too large, the negative electrode may not be accommodated in a standardized battery container.
  • the method for applying the paste is not particularly limited, and examples thereof include a method in which the paste is applied with a doctor blade or a bar coater and then molded with a roll press or the like.
  • Examples of the pressure molding method include molding methods such as roll pressing and press pressing.
  • the pressure during the pressure molding is preferably about 100 to 300 MPa (about 1 to 3 t / cm 2 ).
  • the battery capacity per volume usually increases.
  • the electrode density is too high, the cycle characteristics usually deteriorate.
  • the electrode paste according to a preferred embodiment of the present invention is used, a decrease in cycle characteristics is small even when the electrode density is increased, so that an electrode having a high electrode density can be obtained.
  • the maximum value of the electrode density of the electrode obtained by using this electrode paste is usually 1.7 to 1.9 g / cm 3 .
  • the electrode thus obtained is suitable for a negative electrode of a battery, particularly a negative electrode of a secondary battery.
  • a battery or a secondary battery can be formed using the electrode as a component (preferably a negative electrode).
  • a battery or a secondary battery in a preferred embodiment of the present invention will be described by taking a lithium ion secondary battery as a specific example.
  • a lithium ion secondary battery has a structure in which a positive electrode and a negative electrode are immersed in an electrolytic solution or an electrolyte. The electrode in a preferred embodiment of the present invention is used for the negative electrode.
  • a known positive electrode active material can be used for the positive electrode of the lithium ion secondary battery.
  • a lithium-containing transition metal oxide can be used, and preferably contains at least one transition metal element selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, and W and lithium.
  • a compound that is an oxide and has a molar ratio of lithium to a transition metal element of 0.3 to 2.2 can be used.
  • a separator may be provided between the positive electrode and the negative electrode.
  • the separator include non-woven fabric, cloth, microporous film, or a combination thereof, mainly composed of polyolefin such as polyethylene and polypropylene.
  • the electrolyte and electrolyte known organic electrolytes, inorganic solid electrolytes, and polymer solid electrolytes can be used.
  • D50 Using a Malvern Mastersizer (registered trademark) as a laser diffraction particle size distribution measuring device, D50, which is a 50% particle size in a volume-based cumulative particle size distribution, was determined.
  • BET BET specific surface area
  • the BET specific surface area (SBET) was calculated from the adsorption / desorption amount of nitrogen gas using a specific surface area measuring device NOVA-1200 (manufactured by Yuasa Ionics Co., Ltd.).
  • the punched electrode was sandwiched between super steel press plates and pressed so that the pressing pressure was about 100 to 300 MPa (about 1 to 3 t / cm 2 ) with respect to the electrode. Then, it dried at 120 degreeC and 12 hours with the vacuum dryer, and was set as the electrode for evaluation.
  • a coin cell (counter electrode lithium cell) was produced as follows. The following operation was performed in a dry argon atmosphere with a dew point of -80 ° C or lower. In a cell with a screw-in lid made of polypropylene (inner diameter of about 18 mm), a separator (polypropylene microporous film (Cell Guard 2400)) was sandwiched between the carbon electrode with copper foil and metal lithium foil prepared in b) above and laminated. . An electrolytic solution was added thereto to obtain a test cell.
  • Electrolytic solution LiPF 6 is dissolved in an amount of 1 mol / liter as an electrolyte in a mixed solution of 8 parts by mass of EC (ethylene carbonate) and 12 parts by mass of DEC (diethyl carbonate).
  • Charging rate test A test was performed using a coin cell. After discharging at 0.2 mA (0.05 C) and measuring the discharge capacity, charging is performed by the above method, and further charging at 2.0 mA (0.5 C) and 4.0 mA (1.0 C). The capacities were measured, respectively, and these were divided by the charge capacity at 0.2 mA (0.05 C) to determine the charge capacity maintenance rates at 0.5 C and 1.0 C.
  • (C) Production of Battery A monolayer laminate cell was produced using a produced negative electrode, a positive electrode, and a polypropylene separator as a separator.
  • As the electrolytic solution a solution obtained by dissolving 1 mol / L of LiPF6 in a solvent in which ethyl carbonate, ethyl methyl carbonate, and vinylene carbonate were mixed at a volume ratio of 30: 70: 1 was used.
  • the negative electrode used was prepared in (5).
  • Example 1 20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (water: ethanol volume ratio 1: 1) containing 0.757 g of zinc chloride are mixed (molar ratio of graphite (carbon) and zinc chloride is 300: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 500 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 2 Mixing 20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.540 g of nickel chloride (molar ratio of graphite (carbon) to nickel chloride is 400: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 700 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 3 Mixing artificial graphite A 20.00g and water-ethanol mixed solution (volume ratio of water and ethanol 1: 1) containing 1.292g of cobalt sulfate (Molar ratio of graphite (carbon) and cobalt sulfate is 200: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 800 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 4 20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.817 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 200: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 5 20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 1.633 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 100: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 6 20.00 g of artificial graphite B and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.181 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 900: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 7 Artificial graphite C20.00g and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.327 g of phosphoric acid were mixed (molar ratio of graphite (carbon) to phosphoric acid was 500: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
  • Comparative Example 1 With respect to the untreated artificial graphite A, physical property measurement and battery evaluation were performed.
  • Comparative Example 2 With respect to the untreated artificial graphite B, physical property measurement and battery evaluation were performed.
  • Comparative Example 6 Except that 20.00 g of graphite A and 10 ml of a water-ethanol mixed solution containing 4.54 g of zinc chloride (volume ratio of water to ethanol of 1: 1) were mixed (the molar ratio of graphite to zinc chloride was 50: 1). Treated as in Example 1. Thereafter, physical property measurement and battery evaluation were performed.
  • Comparative Example 7 Example 3 except that a solution of water and ethanol containing 20.00 g of graphite B and 0.136 g of phosphoric acid (volume ratio of water to ethanol of 1: 1) was mixed (the molar ratio of graphite to phosphoric acid was 1200: 1). Treated in the same way. Thereafter, physical property measurement and battery evaluation were performed.
  • Comparative Example 8 A mixture of artificial graphite A and zinc chloride was treated in the same manner as in Example 1 except that it was heat-treated in a nitrogen atmosphere at 300 ° C. for 3 hours. Thereafter, physical property measurement and battery evaluation were performed.
  • Comparative Example 9 A mixture of artificial graphite A and zinc chloride was treated in the same manner as in Example 1 except that it was heat treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. Thereafter, physical property measurement and battery evaluation were performed.
  • Example 1 to 7 and Comparative Examples 1 to 9 the physical property values of the raw material graphite particles used are shown in Table 1, the processing conditions are shown in Table 2, the physical property evaluation results of the obtained graphite materials are shown in Table 3, and the battery evaluation results The results are shown in Table 4.
  • a lithium ion secondary battery using the graphite material of the present invention as an electrode active material is small and light, and has a high discharge capacity and high cycle characteristics. Therefore, it is suitable for a wide range of applications from mobile phones to electric tools and hybrid vehicles. Can be used.

Abstract

The present invention relates to: a graphite material which is suitable for a negative electrode for a lithium ion secondary battery having excellent high current load properties and direct current resistance properties; and a method for producing the graphite material. The graphite material according to the present invention has a surface carbon atom concentration of 98.3% or more as measured by X-ray photoelectron spectroscopy (XPS), wherein the R value (RE) of a graphite edge surface and the R value (RB) of a graphite basal surface as measured by Raman spectroscopy using argon laser satisfy the following requirements (a) and (b): (a) 0.19 ≤ RE ≤ 0.54; and (b)0.10 ≤ RB ≤ 0.14.

Description

黒鉛材料及びその製造方法Graphite material and manufacturing method thereof
　本発明は、大電流負荷特性、直流抵抗特性に優れたリチウムイオン二次電池の負極用に好適な黒鉛材料、及びその製造方法に関する。 The present invention relates to a graphite material suitable for a negative electrode of a lithium ion secondary battery excellent in a large current load characteristic and a direct current resistance characteristic, and a manufacturing method thereof.
　リチウムイオン二次電池では、一般に、正極活物質にコバルト酸リチウムなどのリチウム塩が使用され、負極活物質に黒鉛などの炭素質材料が使用されている。黒鉛には、天然黒鉛と人造黒鉛がある。 In lithium ion secondary batteries, a lithium salt such as lithium cobaltate is generally used for the positive electrode active material, and a carbonaceous material such as graphite is used for the negative electrode active material. Graphite includes natural graphite and artificial graphite.
　これらのうち天然黒鉛は安価に入手できるという利点がある。しかし、天然黒鉛の表面がアクティブであるために初回充電時にガスが多量に発生し、初期効率が低く、サイクル特性も良くなかった。これらを解決するため、特許文献１では、球状に加工した天然黒鉛の表面に、人造カーボンをコーティングする方法が開示されている。
　一方、人造黒鉛については、特許文献２にメソカーボン小球体の黒鉛化品が開示されている。 Among these, natural graphite has an advantage that it can be obtained at low cost. However, since the surface of natural graphite is active, a large amount of gas is generated during the first charge, the initial efficiency is low, and the cycle characteristics are not good. In order to solve these problems, Patent Document 1 discloses a method of coating artificial carbon on the surface of natural graphite processed into a spherical shape.
On the other hand, for artificial graphite, Patent Document 2 discloses a graphitized product of mesocarbon spherules.
　石油ピッチ、石炭ピッチ、石油コークス、石炭コークスの黒鉛化品に代表される人造黒鉛は比較的安価に入手できる。しかし、結晶性のよい針状コークスは鱗片状になり配向しやすい。この問題を解決するため、特許文献３では、複数の扁平状黒鉛粒子を、配向面が非平行となるように集合または結合させた黒鉛材料が開示されている。
　また、特許文献４には、いわゆるハードカーボンや非結晶質カーボンを用いた負極材料が開示されている。 Artificial graphite represented by graphitized products of petroleum pitch, coal pitch, petroleum coke, and coal coke can be obtained at a relatively low cost. However, acicular coke with good crystallinity is scaly and easily oriented. In order to solve this problem, Patent Document 3 discloses a graphite material in which a plurality of flat graphite particles are aggregated or bonded so that their orientation planes are non-parallel.
Patent Document 4 discloses a negative electrode material using so-called hard carbon or amorphous carbon.
　特許文献５には、強力な酸化剤で真空加熱した炭素繊維が開示されている。
　特許文献６には、予めＬｉ化合物と混合した後、加熱焼成処理を行った黒鉛材料が開示されている。
　特許文献７には、非金属有機化合物を含む溶液に黒鉛材料を浸漬することが開示されている。 Patent Document 5 discloses a carbon fiber vacuum-heated with a strong oxidizing agent.
Patent Document 6 discloses a graphite material that is preliminarily mixed with a Li compound and then heat-fired.
Patent Document 7 discloses immersing a graphite material in a solution containing a nonmetallic organic compound.
特許第３５３４３９１号公報（US6632569 B1）Japanese Patent No. 3534391 (US6632569 B1) 特開平４－１９０５５５号公報Japanese Patent Laid-Open No. 4-190555 特許第３３６１５１０号公報（US6344296 B1）Japanese Patent No. 3361510 (US6344296 B1) 特開平７－３２０７４０号公報（US5587255 A）JP-A-7-320740 (US5587255 A) 特開平５－２９９０７４号公報JP-A-5-299074 特開平５－１３５８０２号公報Japanese Patent Laid-Open No. 5-135802 特開平１０－２７００４５号公報（CA2230948 A1）JP-A-10-270045 (CA2230948CAA1)
　特許文献１～特許文献３に記載の方法で製造された材料は、モバイル用途で電池を使用する場合の低電流密度での電気容量や中期サイクル特性については対応可能であるが、大型電池用途で使用する場合の大電流密度での電気容量や、長期サイクル特性に対応することは非常に難しい。
　特許文献４に記載の負極材料は、体積エネルギー密度があまりにも低く、価格も非常に高価なため、一部の特殊な大型電池にしか使用されていない。
　特許文献５に記載の方法では、強力な酸化剤を使用し、高温で加熱するので、生産過程において危険を伴う。
　特許文献６に記載の方法では、大量のＬｉを含む化合物を使用するため、コストが高い。また、処理した黒鉛材料は電気容量が低く、サイクル性能も良くないので、二次電池に用いるには不十分である。
　特許文献７に記載の方法では、電気容量が不十分である。 The materials manufactured by the methods described in Patent Documents 1 to 3 can cope with electric capacity at low current density and medium-term cycle characteristics when using batteries in mobile applications, but for large battery applications. It is very difficult to cope with electric capacity at a large current density and long-term cycle characteristics when used.
The negative electrode material described in Patent Document 4 has a volume energy density that is too low and is very expensive, so it is used only for some special large batteries.
In the method described in Patent Document 5, a strong oxidizing agent is used and heated at a high temperature.
In the method described in Patent Document 6, since a compound containing a large amount of Li is used, the cost is high. Further, the treated graphite material has a low electric capacity and poor cycle performance, so that it is insufficient for use in a secondary battery.
In the method described in Patent Document 7, the electric capacity is insufficient.
　本発明者らは、上記の課題を解決すべく鋭意検討を重ねた結果、大電流負荷特性、直流抵抗特性に優れたリチウムイオン二次電池の負極製造用に好適な黒鉛材料及びその製造方法を見出し、本発明を完成した。 As a result of intensive studies to solve the above-mentioned problems, the present inventors have developed a graphite material suitable for producing a negative electrode of a lithium ion secondary battery excellent in large current load characteristics and DC resistance characteristics, and a production method thereof. The headline and the present invention were completed.
　すなわち、本発明は、以下の（１）～（７）の黒鉛材料、（８）～（１０）の黒鉛材料の製造方法に関する。
（１）Ｘ線光電子分光法（ＸＰＳ）により測定した表面炭素原子比濃度が９８．３％以上であり、アルゴンレーザーを用いたラマン分光分析で測定した黒鉛エッジ面のＲ値（ＲＥ）及び黒鉛ベーサル面のＲ値（ＲＢ）が以下の要件（ａ）及び（ｂ）を満たす黒鉛材料。
　　　（ａ）０．１９≦ＲＥ≦０．５４
　　　（ｂ）０．１０≦ＲＢ≦０．１４
（２）Ｘ線回折法で測定される（００２）面の平均面間隔ｄ００２が０．３３５６ｎｍ～０．３３７５ｎｍである前項１に記載の黒鉛材料。
（３）ＢＥＴ比表面積が１．０ｍ2／ｇ以上８．０ｍ2／ｇ以下である前項１または２に記載の黒鉛材料。
（４）体積基準の累積粒度分布における５０％粒子径Ｄ５０が２μｍ～５５μｍである前項１～３のいずれかに記載の黒鉛材料。
（５）前項１～４のいずれかに記載の黒鉛材料を含む電池電極用炭素材料。
（６）前項５に記載の電池電極用炭素材料を含む二次電池。
（７）表面処理用化合物を含む溶液と原料黒鉛粒子を混合する工程、不活性雰囲気中で熱処理を行う工程を含有する黒鉛材料の製造方法であって、前記黒鉛材料は、アルゴンレーザーを用いたラマン分光分析で測定した黒鉛エッジ面のＲ値（ＲＥ）及び黒鉛ベーサル面のＲ値（ＲＢ）が以下の要件（ｃ）及び（ｄ）を満たす黒鉛材料の製造方法。
　（ｃ）（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が１．１～４．０
　（ｄ）（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．２～２．０
（８）表面処理用化合物と原料黒鉛粒子の混合モル比が、１：１０００～１：１００である前項７に記載の黒鉛材料の製造方法。
（９）熱処理温度が、４００℃以上１３００℃以下である前項７または８に記載の黒鉛材料の製造方法。
（１０）表面処理用化合物が、遷移金属塩化物、遷移金属硝酸塩、遷移金属硫酸塩、遷移金属リン酸塩、硝酸、硫酸、リン酸、またはそれらの混合物（但し、硝酸と硫酸の混合物は除く。）であるである前項７～９のいずれかに記載の黒鉛材料の製造方法。 That is, the present invention relates to the following graphite materials (1) to (7) and methods for producing the graphite materials (8) to (10).
(1) The surface carbon atomic ratio concentration measured by X-ray photoelectron spectroscopy (XPS) is 98.3% or more, and the R value (RE) and graphite of the graphite edge surface measured by Raman spectroscopic analysis using an argon laser A graphite material in which the R value (RB) of the basal surface satisfies the following requirements (a) and (b).
(A) 0.19 ≦ RE ≦ 0.54
(B) 0.10 ≦ RB ≦ 0.14
(2) The graphite material as described in (1) above, wherein an average interplanar spacing d002 of the (002) plane measured by X-ray diffraction method is 0.3356 nm to 0.3375 nm.
(3) The graphite material according to item 1 or 2, wherein the BET specific surface area is 1.0 m 2 / g or more and 8.0 m 2 / g or less.
(4) The graphite material according to any one of items 1 to 3, wherein a 50% particle size D50 in a cumulative particle size distribution on a volume basis is 2 to 55 μm.
(5) A carbon material for battery electrodes, comprising the graphite material as described in any one of 1 to 4 above.
(6) A secondary battery comprising the battery electrode carbon material as described in 5 above.
(7) A method for producing a graphite material comprising a step of mixing a solution containing a surface treatment compound and raw graphite particles, and a step of performing a heat treatment in an inert atmosphere, wherein the graphite material uses an argon laser. A method for producing a graphite material, wherein the R value (RE) of the graphite edge surface and the R value (RB) of the graphite basal surface measured by Raman spectroscopy satisfy the following requirements (c) and (d).
(C) (RE of graphite material / RE of raw graphite particles) is 1.1 to 4.0
(D) (RB of graphite material / RB of raw graphite particles) is 1.2 to 2.0
(8) The method for producing a graphite material as described in (7) above, wherein the mixing molar ratio of the surface treatment compound and the raw graphite particles is from 1: 1000 to 1: 100.
(9) The method for producing a graphite material as described in (7) or (8) above, wherein the heat treatment temperature is from 400 ° C to 1300 ° C.
(10) The surface treatment compound is transition metal chloride, transition metal nitrate, transition metal sulfate, transition metal phosphate, nitric acid, sulfuric acid, phosphoric acid, or a mixture thereof (excluding a mixture of nitric acid and sulfuric acid) 10. The method for producing a graphite material as described in any one of 7 to 9 above, wherein
　本発明の黒鉛材料をリチウムイオン二次電池の負極材料として用いると、電気容量、クーロン効率、サイクル特性、エネルギー密度に優れ、特に、大電流負荷特性及び直流抵抗値の低い電池を得ることができる。
　また、本発明の黒鉛材料は経済性、量産性に優れ、安全な方法により製造することができる。 When the graphite material of the present invention is used as a negative electrode material of a lithium ion secondary battery, it is possible to obtain a battery having excellent electric capacity, coulomb efficiency, cycle characteristics and energy density, and particularly having a large current load characteristic and a low DC resistance value. .
Moreover, the graphite material of the present invention is excellent in economy and mass productivity, and can be produced by a safe method.
　本発明の一実施態様にかかる黒鉛材料は、Ｘ線光電子分光法（ＸＰＳ）により測定した表面炭素原子比濃度が９８．３％以上であることが好ましい。さらに好ましくは９８．７％以上、より好ましくは９９．１％以上である。表面炭素原子比濃度が９８．３％以上であると、黒鉛材料表面の異質な元素が少ないため、電気化学副反応が低減する。 The graphite material according to one embodiment of the present invention preferably has a surface carbon atomic ratio concentration of 98.3% or more as measured by X-ray photoelectron spectroscopy (XPS). More preferably, it is 98.7% or more, More preferably, it is 99.1% or more. When the surface carbon atomic ratio concentration is 98.3% or more, there are few extraneous elements on the surface of the graphite material, so that electrochemical side reactions are reduced.
　本発明の一実施態様にかかる黒鉛材料は、アルゴンレーザーを用いたラマン分光分析で測定した黒鉛エッジ面のＲ値（ＲＥ）及び黒鉛ベーサル面のＲ値（ＲＢ）が以下の要件（ａ）及び（ｂ）を満たす。
　　　（ａ）０．１９≦ＲＥ≦０．５４
　　　（ｂ）０．１０≦ＲＢ≦０．１４
　Ｒ値は、中心波数１５７４～１５７６ｃｍ-1に現れるＧピークの強度（ＩＧ）に対する中心波数１３４４～１３４８ｃｍ-1に現れるＤピークの強度（ＩＤ）の比率（ＩＤ／ＩＧ）を示したものである。 The graphite material according to one embodiment of the present invention has the following requirements (a) for the R value (RE) of the graphite edge surface and the R value (RB) of the graphite basal surface measured by Raman spectroscopy using an argon laser: Satisfies (b).
(A) 0.19 ≦ RE ≦ 0.54
(B) 0.10 ≦ RB ≦ 0.14
The R value represents the ratio (ID / IG) of the intensity (ID) of the D peak appearing at the center wave number 1344 to 1348 cm −1 to the intensity (IG) of the G peak appearing at the center wave number 1574 to 1576 cm −1. .
　ラマン分光分析において、多点測定を行い、エッジ面、ベーサル面それぞれの５点平均化スペクトルのＧピーク強度、Ｄピーク強度より、強度比（ＩＤ／ＩＧ）を計算することにより、エッジ面のＲ値であるＲＥ、ベーサル面のＲ値であるＲＢを算出することができる。本発明の一実施態様にかかる黒鉛材料は、エッジ面のＲ値であるＲＥ及びベーサル面のＲ値であるＲＢについて、０．１９≦ＲＥ≦０．５４かつ０．１０≦ＲＢ≦０．１４であることが好ましく、０．２０≦ＲＥ≦０．５４かつ０．１１≦ＲＢ≦０．１４であることがより好ましく、０．２５≦ＲＥ≦０．５４かつ０．１２≦ＲＢ≦０．１４であることがさらに好ましい。
　ＲＥ及びＲＢがこのような範囲であると、Ｌｉイオンの挿入位置が多くなり、電気化学反応スピードが高くなる。 In Raman spectroscopic analysis, multipoint measurement is performed, and by calculating the intensity ratio (ID / IG) from the G peak intensity and D peak intensity of the five-point averaged spectra of the edge plane and the basal plane, the R of the edge plane is calculated. The value RE and the basal R value RB can be calculated. The graphite material according to one embodiment of the present invention has 0.19 ≦ RE ≦ 0.54 and 0.10 ≦ RB ≦ 0.14 with respect to the RE that is the R value of the edge surface and the RB that is the R value of the basal surface. It is preferable that 0.20 ≦ RE ≦ 0.54 and 0.11 ≦ RB ≦ 0.14, and 0.25 ≦ RE ≦ 0.54 and 0.12 ≦ RB ≦ 0. More preferably, it is 14.
When RE and RB are within such a range, the insertion positions of Li ions increase and the electrochemical reaction speed increases.
　本発明の好ましい実施態様における黒鉛材料は、レーザー回折型粒度分布測定装置を用いて溶媒中で測定した体積基準の累積粒度分布における５０％累積径（Ｄ５０）が２μｍ以上５５μｍ以下であることが好ましく、３μｍ以上４０μｍ以下であることがさらに好ましく、５μｍ以上３５μｍ以下であることが最も好ましい。
　レーザー回折式粒度分布測定装置としては、例えばマルバーン製マスターサイザー（登録商標）が利用できる。 The graphite material in a preferred embodiment of the present invention preferably has a 50% cumulative diameter (D50) in a volume-based cumulative particle size distribution measured in a solvent using a laser diffraction type particle size distribution measuring apparatus of 2 μm or more and 55 μm or less. It is more preferably 3 μm or more and 40 μm or less, and most preferably 5 μm or more and 35 μm or less.
As a laser diffraction type particle size distribution measuring device, for example, Mastersizer (registered trademark) manufactured by Malvern can be used.
　また、本発明の好ましい実施態様における黒鉛材料には、粒径が０．５μｍ以下の粒子を実質的に含まないことが好ましい。０．５μｍ以下の粒子は、表面の活性ポイントが大きく、電池の初期効率を低下させる。ここで実質的に含まないとは粒径が０．５μｍ以下の粒子が０．１質量％以下であることを意味する。０．５μｍ以下の粒子の含有量は前記したようなレーザー回折式粒度分布測定装置により測定できる。 Moreover, it is preferable that the graphite material in a preferred embodiment of the present invention does not substantially contain particles having a particle size of 0.5 μm or less. Particles of 0.5 μm or less have a large active point on the surface and reduce the initial efficiency of the battery. Here, “substantially not contained” means that particles having a particle size of 0.5 μm or less are 0.1% by mass or less. The content of particles of 0.5 μm or less can be measured by a laser diffraction particle size distribution measuring apparatus as described above.
　ＢＥＴ比表面積（ＳＢＥＴ）については、単位質量あたりのガスの吸着脱離量の計測という一般的な手法によって測定する。測定装置としては、例えばＮＯＶＡ－１２００を用いることができる。ＢＥＴ比表面積（ＳＢＥＴ）が、１．０ｍ2／ｇ以上８．０ｍ2／ｇ以下が好ましく、１．２ｍ2／ｇ以上７．０ｍ2／ｇ以下がより好ましく、１．５ｍ2／ｇ以上４．５ｍ2／ｇ以下が最も好ましい。ＳＢＥＴがこの範囲にあることにより、結着剤を過剰に使用することなく、かつ、電解液と接触する面積を大きく確保し、リチウムがスムーズに挿入脱離され、電池の反応抵抗を小さくすることができる。 The BET specific surface area (SBET) is measured by a general method of measuring the amount of adsorption / desorption of gas per unit mass. For example, NOVA-1200 can be used as the measuring device. The BET specific surface area (SBET) is preferably 1.0 m 2 / g or more and 8.0 m 2 / g or less, more preferably 1.2 m 2 / g or more and 7.0 m 2 / g or less, and 1.5 m 2 / g or more. Most preferred is 4.5 m 2 / g or less. By having SBET within this range, it is possible to ensure a large area in contact with the electrolyte without excessive use of the binder, to smoothly insert and desorb lithium, and to reduce the battery reaction resistance. Can do.
　黒鉛材料は、Ｘ線回折法による（００２）面の平均面間隔ｄ００２が０．３３５６ｎｍ以上０．３３７５ｎｍ以下であることが好ましい。結晶のＣ軸方向の厚さＬｃは３０ｎｍ以上１０００ｎｍ以下であることが好ましく、１００ｎｍ以下がさらに好ましく、５０ｎｍ以上１００ｎｍ以下が特に好ましい。また、ａ軸方向の結晶子の厚みＬａは、１００ｎｍ以上が好ましい。このような範囲とすることで活物質がドープされるサイトが十分に得られ、かつ結晶子のエッジ部が多すぎないので、電解液の分解がさらに抑制される。 The graphite material preferably has an average interplanar spacing d002 of (002) planes of 0.3356 nm or more and 0.3375 nm or less by X-ray diffraction. The thickness Lc in the C-axis direction of the crystal is preferably 30 nm or more and 1000 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or more and 100 nm or less. The crystallite thickness La in the a-axis direction is preferably 100 nm or more. By setting it as such a range, the site | part where an active material is doped is fully obtained, and since there are not too many edge parts of a crystallite, decomposition | disassembly of electrolyte solution is further suppressed.
　ｄ００２、Ｌａ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．７０１－７１４参照）。
　平均面間隔ｄ００２が０．３３５６ｎｍ～０．３３７５ｎｍにあることにより黒鉛の結晶性が高く、リチウムイオンがインターカレーション可能な空間が増す。 d002, La and Lc can be measured by a known method using a powder X-ray diffraction (XRD) method (Michio Inagaki, “Carbon”, 1963, No. 36, pp. 25-34, Iwashita et al. , Carbon vol.42 (2004), p.701-714).
When the average interplanar spacing d002 is in the range of 0.3356 nm to 0.3375 nm, the crystallinity of graphite is high and the space in which lithium ions can be intercalated increases.
［黒鉛材料の製造方法］
　本発明の一実施態様にかかる黒鉛材料の製造方法は、原料黒鉛粒子の表面に欠陥を導入するための化合物（「表面処理用化合物」と略記する。）を含む溶液と原料黒鉛粒子を混合する工程、不活性雰囲気中で熱処理を行う工程を含有する黒鉛材料の製造方法である。このような工程を採用することにより、原料黒鉛粒子の表面に欠陥を導入する。
　原料黒鉛粒子の表面に欠陥を導入する場合、黒鉛のエッジ面、ベーサル面に導入する欠陥量を一定の範囲内にコントロールすることが好ましい。 [Method for producing graphite material]
In a method for producing a graphite material according to an embodiment of the present invention, a solution containing a compound for introducing defects on the surface of raw material graphite particles (abbreviated as “surface treatment compound”) and raw material graphite particles are mixed. A process for producing a graphite material comprising a process and a process of performing a heat treatment in an inert atmosphere. By adopting such a process, defects are introduced into the surface of the raw graphite particles.
When introducing defects into the surface of the raw material graphite particles, it is preferable to control the amount of defects introduced into the edge surface and basal surface of the graphite within a certain range.
　黒鉛のエッジ面、ベーサル面に導入する欠陥量を測定する指標として、ラマン分光分析を使用する。原料黒鉛粒子及び黒鉛材料について、ラマン分光分析の多点測定を行い、エッジ面、ベーサル面それぞれの５点平均化スペクトルのＧピーク強度、Ｄピーク強度より、強度比（ＩＤ／ＩＧ）を計算することで、エッジ面のＲ値であるＲＥ、ベーサル面のＲ値であるＲＢを算出することができる。
　Ｒ値は、中心波数１５７４～１５７６ｃｍ-1に現れるＧピークの強度（ＩＧ）に対する中心波数１３４４～１３４８ｃｍ-1に現れるＤピークの強度（ＩＤ）の比率（ＩＤ／ＩＧ）を示したものである。 Raman spectroscopic analysis is used as an index for measuring the amount of defects introduced into the edge and basal surfaces of graphite. For raw material graphite particles and graphite materials, multipoint measurement of Raman spectroscopic analysis is performed, and the intensity ratio (ID / IG) is calculated from the G peak intensity and D peak intensity of the five-point averaged spectrum on each of the edge surface and the basal surface. Thus, the RE that is the R value of the edge surface and the RB that is the R value of the basal surface can be calculated.
The R value represents the ratio (ID / IG) of the intensity (ID) of the D peak appearing at the center wave number 1344 to 1348 cm −1 to the intensity (IG) of the G peak appearing at the center wave number 1574 to 1576 cm −1. .
　エッジ面のＲ値であるＲＥについて、（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が、１．１～４．０となるのが好ましく、１．５～４．０がより好ましく、１．８～４．０がさらに好ましい。
　ベーサル面のＲ値であるＲＢについて、（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．２～２．０となるのが好ましく、１．４～２．０がより好ましく、１．６～２．０がさらに好ましい。 Regarding RE, which is the R value of the edge surface, (RE of graphite material / RE of raw graphite particles) is preferably 1.1 to 4.0, more preferably 1.5 to 4.0. More preferably, it is 8 to 4.0.
Regarding RB which is the R value of the basal plane, (RB of graphite material / RB of raw graphite particles) is preferably 1.2 to 2.0, more preferably 1.4 to 2.0, and 1.6 More preferably, ˜2.0.
　好ましくは、（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．２～２．０であって、（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が１．１～４．０である。
　より好ましくは、（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．４～２．０であって、（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が１．５～４．０である。
　さらに好ましくは、（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．６～２．０であって、（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が１．８～４．０である。 Preferably, (RB of graphite material / RB of raw graphite particles) is 1.2 to 2.0, and (RE of graphite material / RE of raw graphite particles) is 1.1 to 4.0.
More preferably, (RB of graphite material / RB of raw graphite particles) is 1.4 to 2.0, and (RE of graphite material / RE of raw graphite particles) is 1.5 to 4.0. .
More preferably, (RB of graphite material / RB of raw graphite particle) is 1.6 to 2.0, and (RE of graphite material / RE of raw graphite particle) is 1.8 to 4.0. .
　各Ｒ値が上記範囲になるようにコントロールすると、黒鉛の表面に適度な欠陥が導入されて、Ｌｉイオンの挿入位置が多くなり、電気化学反応スピードが高くなる一方で、炭素材料の安定性に対する影響もなく、長期サイクル特性も良好である。 When each R value is controlled to be within the above range, moderate defects are introduced on the surface of the graphite, the insertion positions of Li ions are increased, and the electrochemical reaction speed is increased, while the stability of the carbon material is improved. There is no effect, and long-term cycle characteristics are also good.
　黒鉛表面処理用化合物としては、遷移金属塩化物、遷移金属硝酸塩、遷移金属硫酸塩、遷移金属リン酸塩、硝酸、硫酸、リン酸から選択することが可能である。これらの化合物は１種類を使用しても、２種類以上を混合して使用してもよい。但し、硝酸と硫酸を混合した混酸の使用は除く。これは、硝酸と硫酸の混酸は酸化性が強すぎ、本発明の表面処理用には適さないためである。また、遷移金属としては、例えば鉄、コバルト、ニッケル、銅、亜鉛が使用可能である。 The graphite surface treatment compound can be selected from transition metal chlorides, transition metal nitrates, transition metal sulfates, transition metal phosphates, nitric acid, sulfuric acid, and phosphoric acid. These compounds may be used alone or in combination of two or more. However, the use of mixed acid mixed with nitric acid and sulfuric acid is excluded. This is because the mixed acid of nitric acid and sulfuric acid is too oxidizable and is not suitable for the surface treatment of the present invention. Moreover, as a transition metal, iron, cobalt, nickel, copper, and zinc can be used, for example.
　黒鉛表面処理用化合物と原料黒鉛粒子とを混合する場合のモル比は、化合物：黒鉛が１：１０００～１：１００となるのが好ましい。より好ましくは、１：８００～１：１００であり、さらに好ましくは、１：５００～１：１００である。
　溶液の溶媒は、水と揮発性有機溶媒を含むことが好ましい。揮発性有機溶媒の沸点は、５０～８５℃が好ましい。さらに好ましくは、５５～８０℃であり、６０～８０℃が最も好ましい。 The molar ratio in the case of mixing the graphite surface treatment compound and the raw material graphite particles is preferably 1: 1000 to 1: 100 of compound: graphite. More preferably, it is 1: 800 to 1: 100, and still more preferably 1: 500 to 1: 100.
It is preferable that the solvent of a solution contains water and a volatile organic solvent. The boiling point of the volatile organic solvent is preferably 50 to 85 ° C. More preferably, it is 55 to 80 ° C., and most preferably 60 to 80 ° C.
　化合物を含む溶液と原料黒鉛粒子とを混合した後に、乾燥することが好ましい。乾燥温度は７０～１２０℃が好ましく、８０～１１０℃がより好ましく、９０～１１０℃がさらに好ましい。 It is preferable to dry after mixing the solution containing the compound and the raw material graphite particles. The drying temperature is preferably 70 to 120 ° C, more preferably 80 to 110 ° C, and further preferably 90 to 110 ° C.
　混合物は、不活性雰囲気中で熱処理を行う。熱処理温度は４００～１３００℃が好ましく、５００～１１００℃がより好ましく、５００～１０００℃がさらに好ましい。
　熱処理時間は０．５～５時間が好ましく、１～４時間がより好ましく、１．５～３時間がさらに好ましい。
　熱処理後に得られた黒鉛材料は、洗浄、ろ過、乾燥することが好ましい。 The mixture is heat treated in an inert atmosphere. The heat treatment temperature is preferably 400 to 1300 ° C, more preferably 500 to 1100 ° C, and further preferably 500 to 1000 ° C.
The heat treatment time is preferably 0.5 to 5 hours, more preferably 1 to 4 hours, and further preferably 1.5 to 3 hours.
The graphite material obtained after the heat treatment is preferably washed, filtered and dried.
［電池電極用炭素材料］
　本発明の好ましい実施態様における電池電極用炭素材料は、上記黒鉛材料を含んでなる。上記黒鉛材料を電池電極用炭素材料として用いると、高容量、高クーロン効率、高サイクル特性を維持したまま、直流抵抗が低減され、充放電レートが向上した電池用電極を得ることができる。
　電池電極用炭素材料としては、例えば、リチウムイオン二次電池の負極活物質や負極導電付与材として用いることができる。
　本発明の好ましい実施態様における電池電極用炭素材料は、他の黒鉛材料と上記黒鉛材料とを混合して用いてもよいし、上記黒鉛材料のみを使用してもよい。 [Carbon material for battery electrode]
The carbon material for battery electrodes in a preferred embodiment of the present invention comprises the above graphite material. When the graphite material is used as a carbon material for battery electrodes, a battery electrode with reduced DC resistance and improved charge / discharge rate can be obtained while maintaining high capacity, high coulomb efficiency, and high cycle characteristics.
As a carbon material for battery electrodes, it can use, for example as a negative electrode active material and negative electrode electroconductivity imparting material of a lithium ion secondary battery.
The carbon material for battery electrodes in a preferred embodiment of the present invention may be used by mixing other graphite material and the graphite material, or may use only the graphite material.
［電極用ペースト］
　本発明の好ましい実施態様における電極用ペーストは、前記電池電極用炭素材料とバインダーとを含んでなる。この電極用ペーストは、前記電池電極用炭素材料とバインダーとを混練することによって得られる。混錬には、リボンミキサー、スクリュー型ニーダー、スパルタンリューザー、レディゲミキサー、プラネタリーミキサー、万能ミキサー等公知の装置が使用できる。電極用ペーストは、シート状、ペレット状等の形状に成形することができる。 [Paste for electrodes]
The electrode paste in a preferred embodiment of the present invention comprises the battery electrode carbon material and a binder. This electrode paste is obtained by kneading the carbon material for battery electrodes and a binder. For kneading, known apparatuses such as a ribbon mixer, a screw kneader, a Spartan rewinder, a ladyge mixer, a planetary mixer, and a universal mixer can be used. The electrode paste can be formed into a sheet shape, a pellet shape, or the like.
　電極用ペーストに用いるバインダーとしては、ポリフッ化ビニリデンやポリテトラフルオロエチレン等のフッ素系ポリマー、ＳＢＲ（スチレンブタジエンラバー）等のゴム系等公知のバインダーが挙げられる。
　バインダーの使用量は、電池電極用炭素材料１００質量部に対して１～３０質量部が適当であるが、特に３～２０質量部が好ましい。 Examples of the binder used for the electrode paste include fluorine-based polymers such as polyvinylidene fluoride and polytetrafluoroethylene, and known binders such as rubbers such as SBR (styrene butadiene rubber).
The amount of the binder used is suitably 1 to 30 parts by mass with respect to 100 parts by mass of the carbon material for battery electrodes, and particularly preferably 3 to 20 parts by mass.
　混練する際に溶媒を用いることができる。溶媒としては、各々のバインダーに適した公知のもの、例えばフッ素系ポリマーの場合はトルエン、Ｎ－メチルピロリドン等；ＳＢＲの場合は水等；その他にジメチルホルムアミド、イソプロパノール等が挙げられる。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。溶媒の量は集電体に塗布しやすい粘度となるように調整される。 A solvent can be used when kneading. Examples of the solvent include known solvents suitable for each binder, such as toluene and N-methylpyrrolidone in the case of a fluoropolymer; water in the case of SBR; and dimethylformamide and isopropanol. In the case of 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.
［電極］
　本発明の好ましい実施態様における電極は前記電極用ペーストの成形体からなるものである。電極は例えば前記電極用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。 [electrode]
The electrode in a preferred embodiment of the present invention comprises a molded body of the electrode paste. The electrode is obtained, for example, by applying the electrode paste onto a current collector, drying, and pressure-molding.
　集電体としては、例えばアルミニウム、ニッケル、銅、ステンレス等の箔、メッシュなどが挙げられる。ペーストの塗布厚は、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。ペーストの塗布方法は特に制限されず、例えばドクターブレードやバーコーターなどで塗布後、ロールプレス等で成形する方法等が挙げられる。 Examples of the current collector include aluminum, nickel, copper, stainless steel foil, mesh, and the like. The coating thickness of the paste is usually 50 to 200 μm. If the coating thickness becomes too large, the negative electrode may not be accommodated in a standardized battery container. The method for applying the paste is not particularly limited, and examples thereof include a method in which the paste is applied with a doctor blade or a bar coater and then molded with a roll press or the like.
　加圧成形法としては、ロール加圧、プレス加圧等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１００～３００ＭＰａ（約１～３ｔ／ｃｍ2）程度が好ましい。電極の電極密度が高くなるほど体積あたりの電池容量が通常大きくなる。しかし電極密度を高くしすぎるとサイクル特性が通常低下する。本発明の好ましい実施態様における電極用ペーストを用いると電極密度を高くしてもサイクル特性の低下が小さいので、高い電極密度の電極を得ることができる。この電極用ペーストを用いて得られる電極の電極密度の最大値は、通常１．７～１．９ｇ／ｃｍ3である。このようにして得られた電極は、電池の負極、特に二次電池の負極に好適である。 Examples of the pressure molding method include molding methods such as roll pressing and press pressing. The pressure during the pressure molding is preferably about 100 to 300 MPa (about 1 to 3 t / cm 2 ). As the electrode density of the electrode increases, the battery capacity per volume usually increases. However, if the electrode density is too high, the cycle characteristics usually deteriorate. When the electrode paste according to a preferred embodiment of the present invention is used, a decrease in cycle characteristics is small even when the electrode density is increased, so that an electrode having a high electrode density can be obtained. The maximum value of the electrode density of the electrode obtained by using this electrode paste is usually 1.7 to 1.9 g / cm 3 . The electrode thus obtained is suitable for a negative electrode of a battery, particularly a negative electrode of a secondary battery.
［電池、二次電池］
　前記電極を構成要素（好ましくは負極）として、電池または二次電池とすることができる。
　リチウムイオン二次電池を具体例に挙げて本発明の好ましい実施態様における電池または二次電池を説明する。リチウムイオン二次電池は、正極と負極とが電解液または電解質の中に浸漬された構造をしたものである。負極には本発明の好ましい実施態様における電極が用いられる。 [Battery, secondary battery]
A battery or a secondary battery can be formed using the electrode as a component (preferably a negative electrode).
A battery or a secondary battery in a preferred embodiment of the present invention will be described by taking a lithium ion secondary battery as a specific example. A lithium ion secondary battery has a structure in which a positive electrode and a negative electrode are immersed in an electrolytic solution or an electrolyte. The electrode in a preferred embodiment of the present invention is used for the negative electrode.
　リチウムイオン二次電池の正極には、公知の正極活物質が採用可能である。例えば、リチウム含有遷移金属酸化物が採用可能であり、好ましくはＴｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｍｏ及びＷから選ばれる少なくとも１種の遷移金属元素とリチウムとを主として含有する酸化物であって、リチウムと遷移金属元素のモル比が０．３～２．２の化合物が採用可能である。 A known positive electrode active material can be used for the positive electrode of the lithium ion secondary battery. For example, a lithium-containing transition metal oxide can be used, and preferably contains at least one transition metal element selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, and W and lithium. A compound that is an oxide and has a molar ratio of lithium to a transition metal element of 0.3 to 2.2 can be used.
　リチウムイオン二次電池では正極と負極との間にセパレーターを設けることがある。セパレーターとしては、例えば、ポリエチレン、ポリプロピレン等のポリオレフィンを主成分とした不織布、クロス、微孔フィルムまたはそれらを組み合わせたものなどを挙げることができる。
　電解液及び電解質としては公知の有機電解液、無機固体電解質、高分子固体電解質が使用可能である。 In a lithium ion secondary battery, a separator may be provided between the positive electrode and the negative electrode. Examples of the separator include non-woven fabric, cloth, microporous film, or a combination thereof, mainly composed of polyolefin such as polyethylene and polypropylene.
As the electrolyte and electrolyte, known organic electrolytes, inorganic solid electrolytes, and polymer solid electrolytes can be used.
　以下に本発明について代表的な例を示し、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。 In the following, typical examples of the present invention will be shown and more specifically described. Note that these are merely illustrative examples, and the present invention is not limited thereto.
　実施例及び比較例における物性値測定及び電池評価は以下のように行った。
（１）表面炭素原子濃度（ａｔｏｍｉｃ％）
　ＱｕａｎｔｅｒａII（登録商標）（アルバック・ファイ社製）を使用したＸ線光電子分光法（ＸＰＳ）測定により表面領域における炭素原子濃度（ａｔｏｍｉｃ　％）（「表面炭素原子濃度」と略記する。）を求めることができる。測定条件は、Ｘ線源：Ａｌモノクロ（２５Ｗ、１５ｋＶ）、分析面積：１００μｍ（Ｓｐｏｔ）、電子・イオン中和銃：ＯＮ、光電子取出し角：４５度とした。結合エネルギーのスキャン範囲は、０－１１００ｅＶとした。測定で得られたＸＰＳスペクトルをＸＰＳ用のデータ解析ソフトウェア（アルバック・ファイ社製、ＰＨＩ　ＭｕｌｔｉＰａｋ（登録商標））を用いてデータ処理することにより、表面領域における全元素（原子）の総量に対する炭素原子の量の相対比（ａｔｏｍｉｃ　％）として表面炭素濃度を算出した。 Measurement of physical properties and battery evaluation in Examples and Comparative Examples were performed as follows.
(1) Surface carbon atom concentration (atomic%)
Obtaining the carbon atom concentration (atomic%) in the surface region (abbreviated as “surface carbon atom concentration”) by X-ray photoelectron spectroscopy (XPS) measurement using Quantera II (registered trademark) (manufactured by ULVAC-PHI). Can do. The measurement conditions were as follows: X-ray source: Al monochrome (25 W, 15 kV), analysis area: 100 μm (Spot), electron / ion neutralization gun: ON, photoelectron extraction angle: 45 degrees. The scan range of the binding energy was 0-1100 eV. By processing the XPS spectrum obtained by the measurement using data analysis software for XPS (manufactured by ULVAC-PHI, PHI MultiPak (registered trademark)), carbon atoms relative to the total amount of all elements (atoms) in the surface region The surface carbon concentration was calculated as a relative ratio (atomic%).
（２）ラマン分光分析
　日本分光株式会社製ＪＡＳＣＯ　ＮＲＳ－５１００を使用し、中心波数２０８２．２４ｃｍ-1、励起波長５３２．３６ｎｍ、レーザー強度０．８ｍＷで測定した。ＩＧは中心波数１５７４～１５７６ｃｍ-1に現れるＧピークの強度である。ＩＤは中心波数１３４４～１３４８ｃｍ-1に現れるＤピークの強度である。試料において多点測定を行い、エッジ面、ベーサル面それぞれ５点平均化スペクトルのＧ、Ｄピーク強度より、Ｒ値（強度比ＩＤ／ＩＧ）を計算した。
（３）Ｄ５０
　レーザー回折式粒度分布測定装置として、マルバーン製マスターサイザー（登録商標）を用いて、体積基準の累積粒度分布における５０％粒子径であるＤ５０を求めた。
（４）ＢＥＴ比表面積（ＳＢＥＴ）
　ＢＥＴ比表面積（ＳＢＥＴ）は、比表面積測定装置ＮＯＶＡ－１２００（ユアサアイオニクス（株）製）を使用し、窒素ガスの吸着脱離量から算出した。 (2) Raman spectroscopic analysis JASCO NRS-5100 manufactured by JASCO Corporation was used, and measurement was performed at a central wave number of 2082.24 cm −1 , an excitation wavelength of 532.36 nm, and a laser intensity of 0.8 mW. IG is the intensity of the G peak appearing at a center wave number of 1574 to 1576 cm −1 . ID is the intensity of the D peak appearing at a center wavenumber of 1344 to 1348 cm −1 . The sample was subjected to multipoint measurement, and the R value (intensity ratio ID / IG) was calculated from the G and D peak intensities of the five-point averaged spectra on the edge surface and the basal surface.
(3) D50
Using a Malvern Mastersizer (registered trademark) as a laser diffraction particle size distribution measuring device, D50, which is a 50% particle size in a volume-based cumulative particle size distribution, was determined.
(4) BET specific surface area (SBET)
The BET specific surface area (SBET) was calculated from the adsorption / desorption amount of nitrogen gas using a specific surface area measuring device NOVA-1200 (manufactured by Yuasa Ionics Co., Ltd.).
（５）コインセルによる電池評価
ａ）ペースト作製：
　黒鉛材料１質量部にＪＳＲ社製ＳＢＲを２質量％含有した水溶液０．１質量部を加え、プラネタリーミキサーにて混練し、主剤原液とした。
ｂ）電極作製：
　主剤原液に水を加え、粘度を調整した後、高純度銅箔上でドクターブレードを用いて１５０μｍ厚に塗布した。これを７０℃で１時間真空乾燥し、１６ｍｍφに打ち抜いた。打ち抜いた電極を超鋼製プレス板で挟み、プレス圧が電極に対して約１００～３００ＭＰａ（約１～３ｔ／ｃｍ2）となるようにプレスした。その後、真空乾燥器で１２０℃、１２時間乾燥して、評価用電極とした。 (5) Battery evaluation by coin cell a) Paste production:
0.1 parts by mass of an aqueous solution containing 2% by mass of SBR manufactured by JSR Corporation was added to 1 part by mass of the graphite material, and the mixture was kneaded with a planetary mixer to obtain a main agent stock solution.
b) Electrode preparation:
Water was added to the main agent stock solution to adjust the viscosity, and then applied onto a high purity copper foil to a thickness of 150 μm using a doctor blade. This was vacuum-dried at 70 ° C. for 1 hour and punched out to 16 mmφ. The punched electrode was sandwiched between super steel press plates and pressed so that the pressing pressure was about 100 to 300 MPa (about 1 to 3 t / cm 2 ) with respect to the electrode. Then, it dried at 120 degreeC and 12 hours with the vacuum dryer, and was set as the electrode for evaluation.
ｃ）電池作製：
　下記のようにしてコインセル（対極リチウムセル）を作製した。なお以下の操作は露点－８０℃以下の乾燥アルゴン雰囲気下で実施した。
　ポリプロピレン製のねじ込み式フタ付きのセル（内径約１８ｍｍ）内において、上記ｂ）で作製した銅箔付き炭素電極と金属リチウム箔でセパレーター（ポリプロピレン製マイクロポーラスフィルム（セルガード２４００））を挟み込んで積層した。これに電解液を加えて試験用セルとした。
ｄ）電解液：
　ＥＣ（エチレンカーボネート）８質量部及びＤＥＣ（ジエチルカーボネート）１２質量部の混合液に、電解質としてＬｉＰＦ6を１モル／リットル溶解する。 c) Battery production:
A coin cell (counter electrode lithium cell) was produced as follows. The following operation was performed in a dry argon atmosphere with a dew point of -80 ° C or lower.
In a cell with a screw-in lid made of polypropylene (inner diameter of about 18 mm), a separator (polypropylene microporous film (Cell Guard 2400)) was sandwiched between the carbon electrode with copper foil and metal lithium foil prepared in b) above and laminated. . An electrolytic solution was added thereto to obtain a test cell.
d) Electrolytic solution:
LiPF 6 is dissolved in an amount of 1 mol / liter as an electrolyte in a mixed solution of 8 parts by mass of EC (ethylene carbonate) and 12 parts by mass of DEC (diethyl carbonate).
ｅ）放電容量及び初期効率の測定試験：
　コインセルを用いて試験を行った。充電（炭素へのリチウムの挿入）はレストポテンシャルから０．００２Ｖまで０．２ｍＡ（０．０５Ｃ）でＣＣ（コンスタントカレント：定電流）充電を行った。次に０．００２ＶでＣＶ（コンスタントボルト：定電圧）充電に切り替え、電流値が２５．４μＡに低下した時点で停止させた。電流密度０．２ｍＡ（０．０５Ｃ相当）で定電流放電試験を行った。試験は２５℃に設定した恒温槽内で行った。放電容量は、０．２ｍＡ（０．０５Ｃ）での放電電気量を活物質の質量で除して算出した。また、初回充放電サイクルにおける放電容量と充電容量を測定し、放電容量／充電容量の比から初期効率を算出した。 e) Measurement test of discharge capacity and initial efficiency:
The test was conducted using a coin cell. Charging (insertion of lithium into carbon) was performed by CC (constant current) at 0.2 mA (0.05 C) from the rest potential to 0.002 V. Next, it switched to CV (constant voltage: constant voltage) charge at 0.002 V, and stopped when the current value decreased to 25.4 μA. A constant current discharge test was performed at a current density of 0.2 mA (corresponding to 0.05 C). The test was conducted in a thermostatic chamber set at 25 ° C. The discharge capacity was calculated by dividing the discharge electricity at 0.2 mA (0.05 C) by the mass of the active material. Further, the discharge capacity and the charge capacity in the first charge / discharge cycle were measured, and the initial efficiency was calculated from the ratio of the discharge capacity / charge capacity.
ｆ）充電レート試験
　コインセルを用いて試験を行った。０．２ｍＡ（０．０５Ｃ）での放電を行い、放電容量を測定した後、上記手法により充電を行い、さらに、２．０ｍＡ（０．５Ｃ）及び４．０ｍＡ（１．０Ｃ）での充電容量をそれぞれ測定し、これらを０．２ｍＡ（０．０５Ｃ）での充電容量で除して、０．５Ｃ時及び１．０Ｃ時の充電容量維持率を求めた。 f) Charging rate test A test was performed using a coin cell. After discharging at 0.2 mA (0.05 C) and measuring the discharge capacity, charging is performed by the above method, and further charging at 2.0 mA (0.5 C) and 4.0 mA (1.0 C). The capacities were measured, respectively, and these were divided by the charge capacity at 0.2 mA (0.05 C) to determine the charge capacity maintenance rates at 0.5 C and 1.0 C.
ｇ）充放電サイクル容量維持率の測定試験
　コインセルを用いて試験を行った。３００サイクル容量維持率は、０．５ＣのＣＣ充電と０．５ＣのＣＣ放電の充放電サイクルを３００サイクル繰り返し、２回目の放電容量に対する３００回目の放電容量の比として算出した。 g) Measurement test of charge / discharge cycle capacity maintenance rate A test was performed using a coin cell. The 300 cycle capacity retention rate was calculated as a ratio of the 300th discharge capacity to the second discharge capacity by repeating the charge / discharge cycle of CC charge of 0.5 C and CC discharge of 0.5 C for 300 cycles.
（６）ラミネートセルによる電池評価
（ａ）負極のプレス
　（５）と同様の手順で作製した負極極板を、プレスを行って約１８時間後の電極密度が１．７０ｇ／ｃｍ3になるように、一軸プレス機によるプレスを実施して負極を作製した。プレス後の負極は真空中７０℃で１時間再乾燥を行った。電極密度が上がりにくい場合は圧力を増加させてプレスを行ったが、圧力を最大３００ＭＰａ（約３ｔ／ｃｍ2）まで上げて１０秒間加圧してもプレス直後の電極密度が１．７０ｇ／ｃｍ3に到達しない場合については、実質的に電極密度が１．７０ｇ／ｃｍ3に到達不可能であるとみなした。 (6) Battery Evaluation by Laminate Cell (a) Negative Electrode Press The negative electrode plate produced by the same procedure as in (5) is pressed so that the electrode density becomes 1.70 g / cm 3 after about 18 hours. Furthermore, the negative electrode was produced by performing the press with a uniaxial press. The negative electrode after pressing was re-dried in vacuum at 70 ° C. for 1 hour. When it was difficult to increase the electrode density, pressing was performed while increasing the pressure. However, even if the pressure was increased to a maximum of 300 MPa (about 3 t / cm 2 ) and pressurized for 10 seconds, the electrode density immediately after pressing was 1.70 g / cm 3. In the case where the electrode density does not reach 1.70 g / cm 3 , the electrode density was considered to be substantially unattainable.
（ｂ）正極の作製
　正極活物質としてコバルト酸リチウム（平均粒径５μｍ）９７．５質量％と、気相法炭素繊維（昭和電工株式会社製、ＶＧＣＦ（登録商標）－Ｈ）０．５質量％、カーボンブラック（イメリス・ジーシー・ジャパン製、Ｃ４５）２．０質量％、ポリフッ化ビニリデン（ＰＶＤＦ）３．０質量％をＮ－メチルピロリドンに分散し、塗布量が１９．２ｍｇ／ｃｍ2となるようにアルミニウム箔上に塗工して正極極板を作製した。その後正極極板は真空中７０℃で１時間乾燥を行った。次に、作製した正極極板をロールプレス機でプレスすることにより、電極密度を３．５５ｇ／ｃｍ3に高め、正極を得た。 (B) Preparation of positive electrode 97.5% by mass of lithium cobaltate (average particle size 5 μm) as a positive electrode active material and 0.5% by mass of vapor grown carbon fiber (VGCF (registered trademark) -H, manufactured by Showa Denko KK) %, Carbon black (Imeris GC Japan, C45) 2.0 mass%, polyvinylidene fluoride (PVDF) 3.0 mass% is dispersed in N-methylpyrrolidone, and the coating amount is 19.2 mg / cm 2 Thus, a positive electrode plate was prepared by coating on an aluminum foil. Thereafter, the positive electrode plate was dried in a vacuum at 70 ° C. for 1 hour. Next, the produced positive electrode plate was pressed with a roll press to increase the electrode density to 3.55 g / cm 3 to obtain a positive electrode.
（ｃ）電池の作製
　作製した負極、正極と、セパレーターにポリプロピレン製セパレーターを用い、単層ラミネートセルを作製した。電解液には炭酸エチル、炭酸エチルメチル、炭酸ビニレンを３０：７０：１の体積比率で混合した溶媒にＬｉＰＦ６を１ｍｏｌ／Ｌ溶解したものを使用した。負極には（５）で作製したものを使用した。
（ｄ）直流抵抗値の測定
　ラミネートセルを用いて測定を行った。５０％充電状態において、異なる電流値の電流を流し、その電圧変化をオームの法則にプロットし計算することにより、直流抵抗値（ｏｈｍ）を算出した。 (C) Production of Battery A monolayer laminate cell was produced using a produced negative electrode, a positive electrode, and a polypropylene separator as a separator. As the electrolytic solution, a solution obtained by dissolving 1 mol / L of LiPF6 in a solvent in which ethyl carbonate, ethyl methyl carbonate, and vinylene carbonate were mixed at a volume ratio of 30: 70: 1 was used. The negative electrode used was prepared in (5).
(D) Measurement of DC resistance value It measured using the lamination cell. The DC resistance value (ohm) was calculated by flowing currents of different current values in a 50% state of charge, and plotting and calculating the voltage change in Ohm's law.
実施例１：
　人造黒鉛Ａ２０．００ｇと、塩化亜鉛０．７５７ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合し（黒鉛（炭素）と塩化亜鉛のモル比が３００：１）、９０℃のオーブンで７時間乾燥した。混合物は、窒素雰囲気中で、５００℃、３時間熱処理した。熱処理されたサンプルを０．１ＭのＨＣｌ水溶液と蒸留水で洗浄し、ろ過、乾燥した。その後、物性値測定及び電池評価を実施した。 Example 1:
20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (water: ethanol volume ratio 1: 1) containing 0.757 g of zinc chloride are mixed (molar ratio of graphite (carbon) and zinc chloride is 300: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 500 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
実施例２：
　人造黒鉛Ａ２０．００ｇと、塩化ニッケル０．５４０ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合し（黒鉛（炭素）と塩化ニッケルのモル比が４００：１）、９０℃のオーブンで７時間乾燥した。混合物は、窒素雰囲気中で、７００℃、３時間熱処理した。熱処理されたサンプルは０．１ＭのＨＣｌ水溶液と蒸留水で洗浄し、ろ過、乾燥した。その後、物性値測定及び電池評価を実施した。 Example 2:
Mixing 20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.540 g of nickel chloride (molar ratio of graphite (carbon) to nickel chloride is 400: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 700 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
実施例３：
　人造黒鉛Ａ２０．００ｇと、硫酸コバルト１．２９２ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合し（黒鉛（炭素）と硫酸コバルトのモル比が２００：１）、９０℃のオーブンで７時間乾燥した。混合物は、窒素雰囲気中で、８００℃、３時間熱処理した。熱処理されたサンプルは０．１ＭのＨＣｌ水溶液と蒸留水で洗浄し、ろ過、乾燥した。その後、物性値測定及び電池評価を実施した。 Example 3:
Mixing artificial graphite A 20.00g and water-ethanol mixed solution (volume ratio of water and ethanol 1: 1) containing 1.292g of cobalt sulfate (Molar ratio of graphite (carbon) and cobalt sulfate is 200: 1) And dried in an oven at 90 ° C. for 7 hours. The mixture was heat-treated at 800 ° C. for 3 hours in a nitrogen atmosphere. The heat-treated sample was washed with 0.1 M HCl aqueous solution and distilled water, filtered and dried. Thereafter, physical property measurement and battery evaluation were performed.
実施例４：
　人造黒鉛Ａ２０．００ｇと、リン酸０．８１７ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合（黒鉛（炭素）とリン酸のモル比が２００：１）した以外は実施例３と同様に処理した。その後、物性値測定及び電池評価を実施した。 Example 4:
20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.817 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 200: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
実施例５：
　人造黒鉛Ａ２０．００ｇと、リン酸１．６３３ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合（黒鉛（炭素）とリン酸のモル比が１００：１）した以外は実施例３と同様に処理した。その後、物性値測定及び電池評価を実施した。 Example 5:
20.00 g of artificial graphite A and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 1.633 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 100: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
実施例６：
　人造黒鉛Ｂ２０．００ｇと、リン酸０．１８１ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合（黒鉛（炭素）とリン酸のモル比が９００：１）した以外は実施例３と同様に処理した。その後、物性値測定及び電池評価を実施した。 Example 6:
20.00 g of artificial graphite B and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.181 g of phosphoric acid were mixed (the molar ratio of graphite (carbon) to phosphoric acid was 900: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
実施例７：
　人造黒鉛Ｃ２０．００ｇと、リン酸０．３２７ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合（黒鉛（炭素）とリン酸のモル比が５００：１）した以外は実施例３と同様に処理した。その後、物性値測定及び電池評価を実施した。 Example 7:
Artificial graphite C20.00g and 10 ml of a water-ethanol mixed solution (volume ratio of water to ethanol of 1: 1) containing 0.327 g of phosphoric acid were mixed (molar ratio of graphite (carbon) to phosphoric acid was 500: 1). Except for this, the same treatment as in Example 3 was performed. Thereafter, physical property measurement and battery evaluation were performed.
比較例１：
　無処理の人造黒鉛Ａについて、物性値測定及び電池評価を実施した。 Comparative Example 1:
With respect to the untreated artificial graphite A, physical property measurement and battery evaluation were performed.
比較例２：
　無処理の人造黒鉛Ｂについて、物性値測定及び電池評価を実施した。 Comparative Example 2:
With respect to the untreated artificial graphite B, physical property measurement and battery evaluation were performed.
比較例３：
　人造黒鉛Ａ１０．００ｇを硫酸と硝酸の混酸（２Ｍ硫酸：２Ｍ硝酸＝１:１、体積比率）５０ｍｌに３０分間浸漬し、純水でろ過し、洗浄した後、３０分間真空加熱(８００℃、１０-3ｔｏｒｒ)を行った。その後、物性値測定及び電池評価を実施した。 Comparative Example 3:
10.00 g of artificial graphite A was immersed in 50 ml of a mixed acid of sulfuric acid and nitric acid (2M sulfuric acid: 2M nitric acid = 1: 1, volume ratio) for 30 minutes, filtered with pure water, washed, and then heated under vacuum (800 ° C., 10 −3 torr). Thereafter, physical property measurement and battery evaluation were performed.
比較例４：
　人造黒鉛Ａ１０．００ｇを０．１Ｍの水酸化リチウム水溶液１５ｍｌに加え（黒鉛（炭素）と水酸化リチウムのモル比＝５６０：１）、室温で１時間撹拌した後、水を減圧ろ過した。残渣をアルゴンガス雰囲気下、４００℃で５時間焼成した。その後、物性値測定及び電池評価を実施した。 Comparative Example 4:
10.00 g of artificial graphite A was added to 15 ml of a 0.1 M aqueous lithium hydroxide solution (molar ratio of graphite (carbon) to lithium hydroxide = 560: 1) and stirred at room temperature for 1 hour, and then water was filtered under reduced pressure. The residue was calcined at 400 ° C. for 5 hours in an argon gas atmosphere. Thereafter, physical property measurement and battery evaluation were performed.
比較例５：
　人造黒鉛Ａ１０．００ｇを、０．５Ｍ五塩化リンの塩化メチレン溶液５０ｍｌに混合し（黒鉛（炭素）と五塩化リンのモル比＝３３：１）、１２時間接触させた。次に４０度で溶媒を蒸発により除去した。その後、物性値測定及び電池評価を実施した。 Comparative Example 5:
10.00 g of artificial graphite A was mixed with 50 ml of 0.5M phosphorus pentachloride in methylene chloride (molar ratio of graphite (carbon) and phosphorus pentachloride = 33: 1) and contacted for 12 hours. The solvent was then removed by evaporation at 40 degrees. Thereafter, physical property measurement and battery evaluation were performed.
比較例６：
　黒鉛Ａ２０．００ｇと、塩化亜鉛４．５４ｇを含む水－エタノール混合溶液（水とエタノールの体積比１：１）１０ｍｌを混合（黒鉛と塩化亜鉛のモル比が５０：１）した以外は、実施例１と同様に処理した。その後、物性値測定及び電池評価を実施した。 Comparative Example 6:
Except that 20.00 g of graphite A and 10 ml of a water-ethanol mixed solution containing 4.54 g of zinc chloride (volume ratio of water to ethanol of 1: 1) were mixed (the molar ratio of graphite to zinc chloride was 50: 1). Treated as in Example 1. Thereafter, physical property measurement and battery evaluation were performed.
比較例７：
　黒鉛Ｂ２０．００ｇとリン酸０．１３６ｇを含む水とエタノールの溶液（水とエタノールの体積比１：１）を混合（黒鉛とリン酸のモル比が１２００：１）した以外は実施例３と同様に処理した。その後、物性値測定及び電池評価を実施した。 Comparative Example 7:
Example 3 except that a solution of water and ethanol containing 20.00 g of graphite B and 0.136 g of phosphoric acid (volume ratio of water to ethanol of 1: 1) was mixed (the molar ratio of graphite to phosphoric acid was 1200: 1). Treated in the same way. Thereafter, physical property measurement and battery evaluation were performed.
比較例８：
　人造黒鉛Ａと塩化亜鉛の混合物を、窒素雰囲気中で、３００℃、３時間熱処理した以外は実施例１と同様に処理した。その後、物性値測定及び電池評価を実施した。 Comparative Example 8:
A mixture of artificial graphite A and zinc chloride was treated in the same manner as in Example 1 except that it was heat-treated in a nitrogen atmosphere at 300 ° C. for 3 hours. Thereafter, physical property measurement and battery evaluation were performed.
比較例９：
　人造黒鉛Ａと塩化亜鉛の混合物を、窒素雰囲気中で、１５００℃、３時間熱処理した以外は実施例１と同様に処理した。その後、物性値測定及び電池評価を実施した。 Comparative Example 9:
A mixture of artificial graphite A and zinc chloride was treated in the same manner as in Example 1 except that it was heat treated at 1500 ° C. for 3 hours in a nitrogen atmosphere. Thereafter, physical property measurement and battery evaluation were performed.
　実施例１～７及び比較例１～９において、使用した原料黒鉛粒子の物性値を表１に、処理条件を表２に、得られた黒鉛材料の物性評価結果を表３に、電池評価の結果を表４に示す。 In Examples 1 to 7 and Comparative Examples 1 to 9, the physical property values of the raw material graphite particles used are shown in Table 1, the processing conditions are shown in Table 2, the physical property evaluation results of the obtained graphite materials are shown in Table 3, and the battery evaluation results The results are shown in Table 4.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表４に示す結果より、黒鉛材料のエッジ面及びベーサル面のラマンＲ値が請求項１に記載の範囲内である場合には、これらの少なくとも一方が前記の範囲外である比較例１～４及び比較例６～９に較べて、高い充電容量維持率（０．５Ｃ及び１．０Ｃ時）及び低い直流抵抗値が得られることがわかる。なお、対極リチウムセルにおいては、１Ｃ程度の電流でも大電流の領域になる。
　また、黒鉛材料のエッジ面及びベーサル面のラマンＲ値が請求項１に記載の範囲内であっても、表面炭素原子濃度が９８．３％より低い比較例５の場合には、直流抵抗が高くなることがわかる。 From the results shown in Table 4, when the Raman R values of the edge surface and the basal surface of the graphite material are within the range described in claim 1, Comparative Examples 1 to 4 in which at least one of them is outside the above range. As compared with Comparative Examples 6 to 9, it can be seen that a high charge capacity retention ratio (at 0.5 C and 1.0 C) and a low DC resistance value can be obtained. In the counter electrode lithium cell, even a current of about 1 C becomes a large current region.
Further, even when the Raman R values of the edge surface and the basal surface of the graphite material are within the range described in claim 1, in the case of Comparative Example 5 where the surface carbon atom concentration is lower than 98.3%, the DC resistance is It turns out that it becomes high.
　黒鉛表面の欠陥を制御することにより、充電性能と直流抵抗値が改善される。本発明の黒鉛材料を電極活物質に用いたリチウムイオン二次電池は、小型軽量であり高い放電容量及び高いサイクル特性をもつため、携帯電話から電動工具、またハイブリッド自動車まで多岐にわたる範囲において好適に用いることができる。 Controlling defects on the graphite surface improves charging performance and DC resistance. A lithium ion secondary battery using the graphite material of the present invention as an electrode active material is small and light, and has a high discharge capacity and high cycle characteristics. Therefore, it is suitable for a wide range of applications from mobile phones to electric tools and hybrid vehicles. Can be used.

Claims (10)

  1. 　Ｘ線光電子分光法（ＸＰＳ）により測定した表面炭素原子濃度が９８．３％以上であり、アルゴンレーザーを用いたラマン分光分析で測定した黒鉛エッジ面のＲ値（ＲＥ）及び黒鉛ベーサル面のＲ値（ＲＢ）が以下の要件（ａ）及び（ｂ）を満たす黒鉛材料。
    　　　（ａ）０．１９≦ＲＥ≦０．５４
    　　　（ｂ）０．１０≦ＲＢ≦０．１４     Surface carbon atom concentration measured by X-ray photoelectron spectroscopy (XPS) is 98.3% or more, R value (RE) of graphite edge surface and R of graphite basal surface measured by Raman spectroscopic analysis using argon laser Graphite material whose value (RB) satisfies the following requirements (a) and (b).
    (A) 0.19 ≦ RE ≦ 0.54
    (B) 0.10 ≦ RB ≦ 0.14
  2. 　Ｘ線回折法で測定される（００２）面の平均面間隔ｄ００２が０．３３５６ｎｍ～０．３３７５ｎｍである請求項１に記載の黒鉛材料。 2. The graphite material according to claim 1, wherein an average interplanar spacing d002 of (002) planes measured by an X-ray diffraction method is 0.3356 nm to 0.3375 nm.
  3. 　ＢＥＴ比表面積が１．０ｍ2／ｇ以上８．０ｍ2／ｇ以下である請求項１または請求項２に記載の黒鉛材料。 The graphite material according to claim 1 or 2, wherein the BET specific surface area is 1.0 m 2 / g or more and 8.0 m 2 / g or less.
  4. 　体積基準の累積粒度分布における５０％粒子径Ｄ５０が２μｍ～５５μｍである請求項１～３のいずれかに記載の黒鉛材料。 The graphite material according to any one of claims 1 to 3, wherein a 50% particle diameter D50 in a cumulative particle size distribution on a volume basis is 2 to 55 µm.
  5. 　請求項１～４のいずれかに記載の黒鉛材料を含む電池電極用炭素材料。 A carbon material for battery electrodes, comprising the graphite material according to any one of claims 1 to 4.
  6. 　請求項５に記載の電池電極用炭素材料を含む二次電池。 A secondary battery comprising the battery electrode carbon material according to claim 5.
  7. 　表面処理用化合物を含む溶液と原料黒鉛粒子を混合する工程、不活性雰囲気中で熱処理を行う工程を含有する黒鉛材料の製造方法であって、前記黒鉛材料は、アルゴンレーザーを用いたラマン分光分析で測定した黒鉛エッジ面のＲ値（ＲＥ）及び黒鉛ベーサル面のＲ値（ＲＢ）が以下の要件（ｃ）及び（ｄ）を満たす黒鉛材料の製造方法。
    　（ｃ）（黒鉛材料のＲＥ／原料黒鉛粒子のＲＥ）が１．１～４．０
    　（ｄ）（黒鉛材料のＲＢ／原料黒鉛粒子のＲＢ）が１．２～２．０     A method for producing a graphite material comprising a step of mixing a solution containing a surface treatment compound and raw graphite particles, and a step of performing a heat treatment in an inert atmosphere, wherein the graphite material is analyzed by Raman spectroscopy using an argon laser. A method for producing a graphite material, wherein the R value (RE) of the graphite edge surface and the R value (RB) of the graphite basal surface measured in (1) satisfy the following requirements (c) and (d).
    (C) (RE of graphite material / RE of raw graphite particles) is 1.1 to 4.0
    (D) (RB of graphite material / RB of raw graphite particles) is 1.2 to 2.0
  8. 　表面処理用化合物と原料黒鉛粒子の混合モル比が、１：１０００～１：１００である請求項７に記載の黒鉛材料の製造方法。 The method for producing a graphite material according to claim 7, wherein the mixing molar ratio of the surface treatment compound and the raw material graphite particles is 1: 1000 to 1: 100.
  9. 　熱処理温度が、４００℃以上１３００℃以下である請求項７または請求項８に記載の黒鉛材料の製造方法。 The method for producing a graphite material according to claim 7 or 8, wherein the heat treatment temperature is 400 ° C or higher and 1300 ° C or lower.
  10. 表面処理用化合物が、遷移金属塩化物、遷移金属硝酸塩、遷移金属硫酸塩、遷移金属リン酸塩、硝酸、硫酸、リン酸、またはそれらの混合物（但し、硝酸と硫酸の混合物は除く。）である請求項７～９のいずれかに記載の黒鉛材料の製造方法。 The surface treatment compound is transition metal chloride, transition metal nitrate, transition metal sulfate, transition metal phosphate, nitric acid, sulfuric acid, phosphoric acid, or a mixture thereof (excluding a mixture of nitric acid and sulfuric acid). The method for producing a graphite material according to any one of claims 7 to 9.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09245794A (en) * 1996-03-05 1997-09-19 Canon Inc Lithium secondary battery
JP2011181505A (en) * 2004-06-30 2011-09-15 Mitsubishi Chemicals Corp Negative electrode material for lithium secondary battery and method for manufacturing the same, and negative electrode for lithium secondary battery using the same, and lithium secondary battery
JP2014089887A (en) * 2012-10-30 2014-05-15 Hitachi Chemical Co Ltd Negative electrode material for lithium ion secondary battery and lithium ion secondary battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09245794A (en) * 1996-03-05 1997-09-19 Canon Inc Lithium secondary battery
JP2011181505A (en) * 2004-06-30 2011-09-15 Mitsubishi Chemicals Corp Negative electrode material for lithium secondary battery and method for manufacturing the same, and negative electrode for lithium secondary battery using the same, and lithium secondary battery
JP2014089887A (en) * 2012-10-30 2014-05-15 Hitachi Chemical Co Ltd Negative electrode material for lithium ion secondary battery and lithium ion secondary battery

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