WO2022265040A1 - リチウムイオン二次電池負極用人造黒鉛材料の製造方法、リチウムイオン二次電池負極用人造黒鉛材料、リチウムイオン二次電池用負極、及び、リチウムイオン二次電池 - Google Patents

リチウムイオン二次電池負極用人造黒鉛材料の製造方法、リチウムイオン二次電池負極用人造黒鉛材料、リチウムイオン二次電池用負極、及び、リチウムイオン二次電池 Download PDF

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WO2022265040A1
WO2022265040A1 PCT/JP2022/023950 JP2022023950W WO2022265040A1 WO 2022265040 A1 WO2022265040 A1 WO 2022265040A1 JP 2022023950 W JP2022023950 W JP 2022023950W WO 2022265040 A1 WO2022265040 A1 WO 2022265040A1
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ion secondary
lithium ion
secondary battery
negative electrode
raw coal
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French (fr)
Japanese (ja)
Inventor
貴志 鈴木
寿之 廣木
振 王
慶三 猪飼
規之 木内
崇弘 白井
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Eneos Corp
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Eneos Corp
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Priority to CN202280042505.7A priority Critical patent/CN117529830A/zh
Priority to US18/570,495 priority patent/US20240290974A1/en
Priority to JP2023530373A priority patent/JPWO2022265040A1/ja
Priority to EP22825028.8A priority patent/EP4358190A4/en
Publication of WO2022265040A1 publication Critical patent/WO2022265040A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—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
    • 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
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • 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
    • 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
    • C01B32/21—After-treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M4/13—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
    • 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
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 method for producing an artificial graphite material for a lithium ion secondary battery negative electrode, an artificial graphite material for a lithium ion secondary battery negative electrode, a lithium ion secondary battery negative electrode, and a lithium ion secondary battery.
  • Lithium ion secondary batteries are used in industries such as automobiles and power storage for grid infrastructure.
  • Graphite such as artificial graphite material is used as a negative electrode material for lithium ion secondary batteries (see, for example, Patent Document 1). Since lithium-ion secondary batteries began to be used as a part of social infrastructure, especially rapid charging characteristics have been required. For example, when applied to an electric vehicle (BEV) application, (i) the shorter the time required for charging to full charge, the higher the operating rate of the power supply station, and (ii) the improvement of the regeneration efficiency of brake energy. This is because the cruising distance per charge can be extended by (improving the electric power consumption), thereby improving convenience for the user.
  • BEV electric vehicle
  • lithium ion secondary batteries using graphite as a negative electrode material have the problem that lithium metal is likely to deposit on the negative electrode during rapid charging. When lithium metal deposits on the negative electrode, lithium ions that can move between the positive electrode and the negative electrode decrease. Therefore, the capacity of the lithium ion secondary battery deteriorates.
  • a positive electrode made of a positive electrode active material having an olivine crystal structure and a negative electrode to which inorganic oxide nanoparticles are added are combined.
  • Li acceptance of the negative electrode Li deposition on the surface of the negative electrode during rapid charging, which was a problem of batteries with olivine-based positive electrodes, was suppressed, and the cycle characteristics under high load were dramatically improved. It is disclosed that it can be obtained.
  • a carbon precursor is pulverized and classified, coated with an optically isotropic coal-based pitch, fired, and graphitized.
  • a manufacturing method has been proposed.
  • high-performance negative electrode material for lithium-ion secondary batteries with high capacity, low discharge loss, high bulk density, and high bulk density can be used to fill a large amount of negative electrode material in the battery, and rapid charging is also possible. is disclosed to be able to provide
  • the carbonized material powder before graphitization is coated with a resin such as phenol resin, furan resin, epoxy resin, polyimide resin, acrylic resin, or the like, and then graphitized.
  • a resin such as phenol resin, furan resin, epoxy resin, polyimide resin, acrylic resin, or the like.
  • a manufacturing method has been proposed.
  • the graphite powder exhibits a high discharge capacity exceeding 340 mAh/g, which is quite close to the theoretical capacity, and has a high charge/discharge efficiency of 80% or more, preferably 90% or more, and is suitable as a negative electrode material for lithium ion secondary batteries. can be stably produced at a relatively low cost.
  • Patent Document 5 discloses a negative electrode material for a lithium ion secondary battery in which the surfaces of graphite particles serving as cores are coated with amorphous carbon.
  • core graphite particles and pitch are kneaded while applying mechanical impact to disperse and fix amorphous carbon on the graphite particle surfaces, followed by heat treatment.
  • the negative electrode material for a lithium-ion secondary battery not only suppresses capacity reduction by consuming the electrolytic solution and lithium ions to form a new protective coating on the surface of the core graphite particles, but also suppresses capacity reduction. It is disclosed to have the excellent rate properties of amorphous carbon.
  • Patent Document 6 proposes a composite graphite material having a low-crystalline graphite layer on the surface of a core of highly crystalline graphite particles.
  • the composite graphite material is obtained by mechanochemically treating a graphite precursor containing core graphite and then graphitizing it, and is disclosed to have high rate characteristics while maintaining high reversible capacity.
  • lithium-ion secondary batteries have begun to be used as social infrastructure, such as for electric vehicles and for grid connection of natural energy. Therefore, a lithium ion battery suitable for charge acceptance of a larger current and a negative electrode graphite material thereof are desired.
  • the negative electrode manufactured using the conventional negative electrode graphite material as described above is still insufficient in high-current charge acceptance and the like to meet the requirements.
  • the lithium ion secondary battery having a negative electrode containing the above-described conventional negative electrode material part of the coating material falls off when rapid charging and discharging are repeated, and highly crystalline graphite particles that are the core, that is, the active There is room for further improvement because the newly exposed surface of the high graphite particles consumes the electrolyte and lithium ions to form a new protective coating and reduce capacity.
  • a core graphite is required, and the raw material is purified natural graphite with high crystallinity or artificial graphite graphitized by heat treatment at a temperature close to 3000 ° C. should be used for Furthermore, after the mechanochemical treatment of the core particles together with the graphite precursor, a step including heat treatment at a temperature close to 3000° C. is required, which increases energy consumption and production costs during production.
  • the present invention has been made in view of the above circumstances.
  • Method for producing artificial graphite material for battery negative electrode, artificial graphite material for lithium ion secondary battery negative electrode obtained by the production method, negative electrode for lithium ion secondary battery produced from the graphite material, and lithium ion having the negative electrode An object is to provide a secondary battery.
  • the inventors produced raw coal powder having a relatively large specific surface area and coated the raw coal powder with a coating material. Since the area is large and it is easy to form a strong bond, even in the finally obtained graphite material, the graphite material (interphase between the phase derived from the coating material and the phase derived from the raw coal powder) Lithium ions can diffuse at high speed inside, and when the graphite material is used for the negative electrode of a lithium ion secondary battery, the deterioration of the discharge capacity is suitably suppressed even if the charge / discharge cycle is repeated at a large current. , have completed the present invention. Specifically, the present invention employs the following configurations.
  • a method for producing an artificial graphite material for a lithium ion secondary battery negative electrode comprising: coking a raw oil composition by a delayed coking process to produce a raw coal composition; obtaining a heat-treated raw coal composition by heat treatment; pulverizing the heat-treated raw coal composition to obtain raw coal powder; coating the raw coal powder with a coating material to obtain coated raw coal; obtaining a powder; and graphitizing the coated raw coal powder to obtain an artificial graphite material for a negative electrode of a lithium ion secondary battery, wherein the raw coal powder has a nitrogen adsorption specific surface area of 10.5 m 2 . /g or more, a method for producing an artificial graphite material for a lithium ion secondary battery negative electrode.
  • a method for producing an artificial graphite material for a secondary battery negative electrode [3] The method for producing an artificial graphite material for a lithium ion secondary battery negative electrode according to [1] or [2], wherein the temperature of the heat treatment in the step of obtaining the heat-treated raw coal composition is 500°C or higher and 700°C or lower. .
  • the raw oil composition has a normal paraffin content of 5 to 20% by mass relative to the total amount of the raw oil composition, and an aromatic index fa determined by the Knight method is 0.3 to 0. .65, the method for producing an artificial graphite material for a lithium ion secondary battery negative electrode according to any one of [1] to [3].
  • An artificial graphite material for a lithium ion secondary battery negative electrode obtained by the production method according to any one of [1] to [4].
  • a negative electrode for a lithium ion secondary battery comprising the artificial graphite material for a lithium ion secondary battery negative electrode according to [5].
  • a method for producing an artificial graphite material for a lithium-ion secondary battery negative electrode which can produce a negative electrode for a lithium-ion secondary battery whose discharge capacity is less likely to deteriorate even when charge-discharge cycles are repeated with a large current.
  • an artificial graphite material for a lithium ion secondary battery negative electrode obtained by the manufacturing method, a negative electrode for a lithium ion secondary battery produced from the graphite material, and a lithium ion secondary battery having the negative electrode can be provided. .
  • FIG. 1 is a schematic cross-sectional view showing an example of a lithium ion secondary battery of the present invention
  • the manufacturing method of the artificial graphite material for lithium ion secondary battery negative electrode, the artificial graphite material for lithium ion secondary battery negative electrode, the lithium ion secondary battery negative electrode, and the lithium ion secondary battery of the present invention will be described in detail. .
  • the present invention is not limited only to the embodiments shown below.
  • the method for producing an artificial graphite material for a lithium ion secondary battery negative electrode includes a step of coking a raw oil composition by a delayed coking process to produce a raw coal composition (hereinafter also referred to as “step A”). ), a step of heat-treating the raw coal composition to obtain a heat-treated raw coal composition (hereinafter also referred to as “step B”), and pulverizing the heat-treated raw coal composition to obtain raw coal powder.
  • step C a step of coating the raw coal powder with a coating material to obtain coated raw coal powder
  • step D a coating material to obtain coated raw coal powder
  • step E a step of graphitizing the powder to obtain an artificial graphite material for a lithium ion secondary battery negative electrode
  • Step A is a step of coking the raw oil composition by a delayed coking process to produce a raw coal composition.
  • a specific example of the feedstock oil composition in step A is heavy oil.
  • Heavy oils include, for example, bottom oil of fluid catalytic cracking oil (FCC DO), heavy oil subjected to advanced hydrodesulfurization treatment, vacuum distillation residue (VR), coal liquefied oil, solvent extraction oil of coal , atmospheric distillation residue, shale oil, tar sand bitumen, naphtha tar pitch, coal tar pitch, ethylene bottom oil and the like.
  • the heavy oil may be subjected to various treatments such as hydrorefining.
  • the feedstock oil composition in step A it is preferable to use a heavy oil that contains an appropriate amount of aromatic components and an appropriate amount of normal paraffin and has undergone a high degree of hydrodesulfurization treatment.
  • a heavy oil that contains an appropriate amount of aromatic components and an appropriate amount of normal paraffin and has undergone a high degree of hydrodesulfurization treatment.
  • the raw oil composition contains heavy oil, a single heavy oil may be used, or two or more types of heavy oil may be mixed and used.
  • the mixing ratio of each heavy oil can be appropriately adjusted according to the properties of each heavy oil.
  • the properties of each heavy oil differ depending on the type of crude oil, processing conditions for obtaining heavy oil from crude oil, and the like.
  • a component that produces a good bulk mesophase during coking treatment and a component that reduces the size of the bulk mesophase when this bulk mesophase is polycondensed, carbonized and solidified Heavy oils containing gas-producing components are preferred.
  • a component that produces a good bulk mesophase during coking treatment includes a component that has an aromatic index fa within a predetermined range as determined by the Knight method.
  • the component is preferably a component having an aromatic index fa of 0.30 to 0.65 as determined by the Knight method, and more preferably a component having an aromatic index fa of 0.35 to 0.60. More preferred are components having an aromatic index fa of 0.40 to 0.55.
  • aromatic index fa is the aromatic carbon fraction determined by the Knight method.
  • the carbon distribution is divided into three components (A1, A2, A3) as an aromatic carbon spectrum by the 13 C-NMR method.
  • A1 is the number of carbon atoms in the aromatic ring (half of the number of substituted aromatic carbons and unsubstituted aromatic carbons (corresponding to a peak of about 40 to 60 ppm in 13 C-NMR))
  • A2 is the number of substituted aromatic carbons.
  • A3 is the number of aliphatic carbons (corresponding to about 130-190 ppm peak in 13 C-NMR), the remaining half being aromatic carbons (corresponding to about 60-80 ppm peak in 13 C-NMR).
  • the 13 C-NMR method is the best method for quantitatively obtaining fa, which is the most basic amount of chemical structural parameters of pitches, for example, in the literature ("Characterization of Pitch II. Chemical Structure” Yokono, Sanada, (Carbon, 1981 (No. 105), p73-81).
  • ⁇ A component that generates a gas that reduces the size of the bulk mesophase when the bulk mesophase is polycondensed, carbonized, and solidified >> Specific examples of components that generate gas that reduces the size of the bulk mesophase when the bulk mesophase undergoes polycondensation, carbonization, and solidification include normal paraffin.
  • the normal paraffin content in the raw material oil composition in step A is preferably 5 to 20% by mass, more preferably 10 to 15% by mass, relative to the total amount of the raw material oil composition.
  • normal paraffin content means a value measured by a gas chromatograph equipped with a capillary column. Specifically, after calibrating with normal paraffin standards, a sample of non-aromatic components separated by elution chromatography is passed through a capillary column and measured. From this measured value, the normal paraffin content based on the total amount of the raw oil composition can be calculated.
  • the normal paraffin contained in the raw oil composition generates gas during the coking process.
  • This gas plays an important role in limiting the size of the bulk mesophase produced during the coking process to a small size and limiting the mesophase to a small size.
  • the gas generated during the coking process also has the function of uniaxially orienting adjacent mesophases limited in size to form a microstructure with selective orientation.
  • the normal paraffin content of the raw oil composition When the normal paraffin content of the raw oil composition is 5% by mass or more, the bulk mesophase is prevented from growing more than necessary, and a carbon hexagonal net plane laminate of an appropriate size is more likely to be formed. Moreover, when the normal paraffin content of the raw material oil composition is 20% by mass or less, the amount of gas generated from the normal paraffin becomes more moderate. If excessive gas is generated during the coking process, the unevenness of the outermost surface of the particles generated by pulverization after the heat treatment of the raw coal composition tends to grow large, and even after graphitization, the atoms on the outermost surface of the particles have a surface superstructure suitable for rapid charging. It is not preferable because rearrangement becomes difficult.
  • the raw material oil composition in step A preferably has an aromatic index fa determined by the Knight method of 0.30 to 0.65, more preferably 0.35 to 0.60. It is preferably 0.40 to 0.55, and more preferably 0.40 to 0.55.
  • the surface of the raw coal powder has appropriate unevenness due to the combination of the heat treatment of the raw coal composition and the subsequent pulverization treatment. It becomes easier to form, and a surface structure suitable for rapid charging is more likely to be introduced to the surface of the particles after graphitization.
  • the raw coal powder and the covering material can be firmly bonded in the step D described later due to the effect of moderately increasing the surface area.
  • the finally obtained lithium ion secondary battery having a negative electrode containing the artificial graphite material for a lithium ion secondary battery negative electrode does not easily fall off of the coating material and does not easily deteriorate even after repeated rapid charging.
  • the aromatic index fa is too small, the unevenness caused by the pulverization of the raw coal composition after heat treatment tends to grow large, and the atoms on the outermost surface of the particles tend to form a surface superstructure suitable for rapid charging even after graphitization. It is not preferable because rearrangement becomes difficult.
  • the gas generated during the coking process tends to restrict the bulk mesophase to a small size, which is preferable.
  • the aromaticity index fa is too large, a large number of mesophases are abruptly generated in the matrix during the coking treatment, and the coalescence rate of the mesophases becomes faster than the single growth rate of the mesophases. As a result, it becomes difficult to obtain the effect of reducing the size of the bulk mesophase by the gas generated during the coking process, and it becomes difficult to limit the size of the bulk mesophase to a small size, which is not preferable.
  • the raw material oil composition in step A preferably has a normal paraffin content of 5 to 20% by mass, more preferably 10 to 15% by mass, based on the total amount of the raw material oil composition, and ,
  • the aromatic index fa determined by the Knight method is preferably 0.3 to 0.65, more preferably 0.35 to 0.60, still more preferably 0.40 to 0.55 be.
  • the raw oil composition in step A preferably has a normal paraffin content and an aromatic index fa within the above ranges and is heavy oil that has been subjected to a high degree of hydrodesulfurization treatment.
  • the raw material oil composition in step A more preferably has a normal paraffin content and an aromatic index fa within the above ranges, and a density D of 0.91 to 1.02 g/cm 3 . Furthermore, those having a viscosity V of 10 to 220 mm 2 /s are more preferable.
  • ⁇ Caulking treatment ⁇ As a method of coking the raw oil composition in step A by a delayed coking process, for example, a known method described in Japanese Patent No. 5415684 can be used.
  • the method of coking the raw material oil composition by the delayed coking process is very suitable for mass-producing raw materials for high-quality artificial graphite materials.
  • a delayed coking process is used as a method of coking the raw oil composition.
  • thermal decomposition and polycondensation reactions of the raw material oil composition occur, and a raw material coal composition is obtained through a process in which a large liquid crystal called mesophase is produced as an intermediate product.
  • the pressure is preferably 0.1 to 0.8 MPa, more preferably 0.2 to 0.6 MPa.
  • the temperature is preferably 400 to 600°C, more preferably 490 to 540°C.
  • the size of the hexagonal carbon mesh planes forming the mesophase is controlled by the gas generated from the raw oil composition during the coking process. Therefore, the residence time of the gas generated from the raw material oil composition during the coking process in the system is an important control parameter for determining the size of the carbon hexagonal mesh plane.
  • the residence time of the gas generated during the coking process within the system can be adjusted by the pressure during the coking process. Therefore, when the pressure in the coking process is within the above preferred range, it becomes easier to limit the release rate of the gas generated from the raw oil composition to the outside of the system. Further, when the temperature in the coking treatment is within the above preferable range, better mesophase can be grown from the raw oil composition adjusted to obtain the effects of the present invention.
  • the temperature in the coking treatment is too low and the pressure is too high, the amount of gas generated during the coking treatment will be insufficient and the crystal structure of the raw coal composition will grow too much. In this case, pores having openings on the particle surfaces of the heat-treated raw coal composition produced by the heat treatment in the step B described later and irregularities on the particle surfaces are less likely to be formed, which is not preferable.
  • the temperature in the coking process is too high and the pressure is too low, the amount of gas generated during the coking process will be excessive, and even if the heat treatment is performed in the subsequent graphitization process, the graphite crystal structure will not grow easily, resulting in a high capacity. Since it does not appear, it is not preferable as an artificial graphite material for a negative electrode of a lithium ion secondary battery.
  • the raw coal composition in process A is a composition containing raw coke.
  • Step B is a step of heat-treating the raw coal composition described above to obtain a heat-treated raw coal composition.
  • heat treatment is performed in an atmosphere of an inert gas such as nitrogen, argon, or helium.
  • the atmosphere gas may contain oxygen gas in a range of 0.01 to 21% by volume with respect to the total amount of the atmosphere gas.
  • the heat treatment include a method of charging the coking coal composition into a sagger and using a roller hearth kiln, a method of directly charging the coking coal composition into a rotary kiln, and the like.
  • the nitrogen adsorption specific surface area (hereinafter also simply referred to as “specific surface area”) of the raw coal powder is determined by the heat treatment temperature of the raw coal composition (maximum temperature) and heat treatment time (holding time of maximum temperature).
  • the higher the heat treatment temperature, the longer the heat treatment time, or the higher the oxygen content of the heat treatment atmosphere gas the greater the specific surface area of the heat-treated raw coal composition and raw coal powder obtained therefrom.
  • the heat treatment temperature and heat treatment time of the raw coal composition or the oxygen content of the heat treatment atmosphere gas must be set so that the raw coal powder has a specific surface area of 10.5 cm 2 /g or more.
  • the “specific surface area” is the nitrogen adsorption specific surface area measured and calculated in accordance with JIS Z 8830 (2013) “Method for measuring specific surface area of powder (solid) by gas adsorption”.
  • the volatile matter and the true density of the raw coal powder are determined by the heat treatment temperature (maximum attainable temperature) and the heat treatment time (maximum retention time of reaching temperature).
  • the higher the heat treatment temperature or the longer the heat treatment time the lower the volatile content of the heat-treated raw coal composition and the raw coal powder obtained therefrom, and the higher the true density.
  • the heat treatment temperature and heat treatment time of the raw coal composition are such that the volatile content of the raw coal powder is less than 3.71% and the true density of the raw coal powder is more than 1.22 g/cm 3 and less than 1.73 g/cm 3 . It is preferable to set such that
  • the lower limit of the highest temperature reached in step B makes it easy to adjust the volatile content and true density of the raw coal powder within the above range, and makes it possible to shorten the heat treatment time, thereby further suppressing the production cost. Therefore, the temperature is preferably 450° C. or higher, more preferably 500° C. or higher, and even more preferably 550° C. or higher.
  • the upper limit of the highest temperature reached in step B makes it easier to adjust the volatile content and true density of the raw coal powder within the above ranges, and further improves the quality stability of the heat-treated raw coal composition and raw coal powder. 750° C. or less is preferable, 700° C. or less is more preferable, and 650° C. or less is even more preferable.
  • the highest temperature reached in step B is preferably 450 to 750°C, more preferably 500 to 700°C, still more preferably 550 to 650°C.
  • the heat treatment temperature is too low, it will take a long time and the manufacturing cost will increase unnecessarily, which is not preferable.
  • the heat treatment temperature is too high, the specific surface area and properties (volatile matter and true density) of the heat-treated raw coal composition and raw coal powder will vary greatly, which is not preferable from the viewpoint of quality stability.
  • the lower limit of the retention time for the highest temperature reached in step B is such that the volatile content and true density of the raw coal powder can be easily adjusted within the above range, and the quality stability of the heat-treated raw coal composition and raw coal powder is maintained. 0.1 hours or more is preferable, 0.2 hours or more is more preferable, and 0.5 hours or more is still more preferable because the time can be improved.
  • the upper limit of the holding time of the maximum temperature reached in step B is preferably 3 hours or less, because the volatile content and true density of the raw coal powder can be easily adjusted within the above range, and the production cost can be further reduced. , more preferably 2 hours or less, more preferably 1 hour or less.
  • the holding time for the highest temperature reached in step B is preferably 0.1 to 3 hours, more preferably 0.2 to 2 hours, and even more preferably 0.5 to 1 hour.
  • Step C is a step of pulverizing the heat-treated raw coal composition described above to obtain raw coal powder.
  • the raw coal powder obtained in step C has a specific surface area of 10.5 m 2 /g or more. Moreover, it is preferable that the volatile content is less than 3.71% and the true density is more than 1.22 g/cm 3 and less than 1.73 g/cm 3 .
  • the specific surface area of the raw coal powder is controlled by the step B, and is less affected by the pulverization conditions of the step C.
  • the volatile matter and the true density of the raw coal powder are also controlled by the step B, and are less affected by the pulverization conditions of the step C.
  • volatile matter refers to "7.2 Vertical tubular electric furnace” of "7.
  • Volatile content determination method described in “Coal and coke - Industrial analysis method” of JIS M 8812 (2004) means the volatile content [mass fraction (%)] calculated according to the Law", "b) for coke”.
  • true density refers to "7.3 True density test method” of "7. Density/porosity test method” described in “Cokes-Test method” of JIS K 2151 (2004). It means the true density [g/cm 3 ] calculated according to the standard.
  • the true density of the raw coal composition produced by coking the raw oil composition by the delayed coking process is usually 1.1 to 1.4 g/cm 3 and the volatile content is usually 5 to 15%. (See, for example, "Journal of Fuel Association", Vol. 58, No. 642 (1979), p.257-263).
  • the volatile content is lowered and the true density is improved.
  • the reason why the volatile matter is reduced is that the volatile matter contained in the raw material coal composition is a reaction product of the raw material oil composition that remains in a state of insufficient thermal decomposition and polycondensation reaction in the delayed coking process. This is because it scatters due to the heat treatment.
  • the reason why the true density is improved is that the thermal decomposition and polycondensation reactions further proceed by the heat treatment.
  • the raw coal composition having such properties is heat-treated and then pulverized, for example, to control the volatile content of the raw coal powder to less than 3.71%, and to control the true density of the raw coal powder. is controlled to be more than 1.22 g/cm 3 and less than 1.73 g/cm 3 , the specific surface area of the raw coal powder is improved to 10.5 m 2 /g or more, and the contact area with the coating material is increased. Lithium ions can diffuse at high speed in the graphite powder after graphitization.
  • the surface and internal bulk of the raw coal powder have an evaporation path for the volatile matter, i.e., winding pores of various sizes. is formed.
  • pores with small diameters grow as cavities (cracks), and pores with large diameters are cut (pulverized) after growing as cavities.
  • the raw coal powder has pores having openings on the particle surface and unevenness on the particle surface.
  • the raw coal powder obtained in step C has a specific surface area of 10.5 m 2 /g or more, preferably 11 m 2 /g or more, more preferably 11.5 m 2 /g or more, and 12 m 2 /g or more. 2 /g or more, and particularly preferably 20 m 2 /g or more. Further, the raw coal powder obtained in step C preferably has a specific surface area of 120 m 2 /g or less, more preferably 100 m 2 /g or less, and even more preferably 95 m 2 /g or less. .
  • the raw coal powder obtained in step C preferably has a specific surface area of 10.5 m 2 /g or more and 120 m 2 /g or less, more preferably 11 m 2 /g or more and 120 m 2 /g or less. , more preferably 11.5 m 2 /g or more and 100 m 2 /g or less, particularly preferably 12 m 2 /g or more and 95 m 2 /g or less, and 20 m 2 /g or more and 95 m 2 /g or less is most preferred.
  • the raw coal powder preferably has a volatile content of less than 3.71%, more preferably 0.1% or more and 3.6% or less. Further, the raw coal powder preferably has a true density of more than 1.22 g/cm 3 and less than 1.73 g/cm 3 , and more preferably 1.26 g/cm 3 or more and 1.68 g/cm 3 or less. more preferred.
  • the heat treatment of the raw coal composition is insufficient, for example, if the raw coal powder has a volatile content of more than 3.6% and a true density of less than 1.26 g/cm 3 , delayed coking will occur. Since only relatively low-molecular-weight compounds that are insufficiently subjected to thermal decomposition and polycondensation reactions in the process evaporate, the subsequent pulverization does not introduce irregularities of appropriate sizes to the particle surfaces of the raw coal powder. , it is difficult to form raw coal powder having a large specific surface area of 10.5 m 2 /g or more.
  • the specific surface area is preferably 10.5 m 2 /g or more.
  • the raw coal powder preferably has a volatile content of 0.1 to 3.6% and a true density of 1.26 to 1.68 g/cm 3 .
  • pulverization means in step C known methods such as a method using a hammer mill and a method using an airflow jet mill can be used, and are not particularly limited.
  • the raw coal powder obtained in step C preferably has an average particle size of 3 to 40 ⁇ m, more preferably 4 to 20 ⁇ m, even more preferably 5 to 10 ⁇ m.
  • the artificial graphite material obtained by graphitizing after coating with the coating material has a particle size suitable for a negative electrode of a lithium ion secondary battery. .
  • the average particle size of the raw coal powder is too small, the specific surface area of the artificial graphite material for the negative electrode of the lithium ion secondary battery, which is graphitized after coating with the coating material, becomes too large. It is not preferable to prepare the paste-like negative electrode mixture to be used because the amount of solvent required is enormous. On the other hand, if the average particle size of the raw coal powder is too large, when the artificial graphite material for lithium ion secondary battery negative electrode graphitized after coating with the coating material is used for the negative electrode of the lithium ion secondary battery, the negative electrode thickness will be reduced. It becomes difficult to set the thickness to 80 ⁇ m or less, and the degree of freedom in design tends to decrease.
  • the term "average particle size” means that the particle size distribution is measured using a laser diffraction/scattering particle size distribution analyzer, and the measurement results of the obtained particle size distribution are measured according to JIS Z 8819-2 (2001). "Expression of particle size measurement results-Part 2: Calculation of average particle size or average particle diameter and moment from particle size distribution” of "4.2.3 Weighted average particle size” "Weighted volume basis means a value calculated according to the "average diameter”.
  • the pulverization conditions in step C are appropriately set so that the raw coal powder has an average particle size of 3 to 40 ⁇ m.
  • the raw coal powder obtained in step C may be classified so as to have a predetermined particle size.
  • a known method such as a method using a classifier can be used, and is not particularly limited.
  • Step D is a step of coating raw coal powder with a coating material to obtain coated raw coal powder.
  • the specific surface area of the raw coal powder obtained in step C is controlled to be relatively large.
  • a strong bond is formed between the covering material and the raw coal powder due to the anchoring effect of the unevenness formed on the surface of the raw coal powder, which has a large contact area with the body.
  • the coating material typically uses a carbon material having a lower crystallinity than raw coal powder.
  • a coating material By coating the raw coal powder with a coating material, it is possible to increase the entrance of lithium ions in the finally obtained artificial graphite material for lithium ion secondary battery negative electrode. This makes it possible to improve the charge acceptance of lithium ions (make it difficult to deposit lithium metal).
  • the coating material for coating the raw coal powder general materials used for graphite materials for negative electrodes of lithium ion secondary batteries can be used without particular limitation.
  • general materials used for graphite materials for negative electrodes of lithium ion secondary batteries can be used without particular limitation.
  • petroleum-based anisotropic pitch petroleum-based isotropic pitch; coal-based anisotropic pitch; coal-based isotropic pitch; mesophase pitch; ); thermoplastic resins (such as acrylic resins) and the like.
  • a homogenous (molecular weight Narrow distribution) petroleum anisotropic pitch is preferred.
  • Petroleum-based anisotropic pitch is obtained by heat-treating petroleum-based isotropic pitch under reduced pressure.
  • Raw materials for petroleum-based isotropic pitch include bottom oil of fluid catalytic cracking oil (FCC DO), heavy oil subjected to advanced hydrodesulfurization treatment, vacuum residue (VR), and the like.
  • FCC DO fluid catalytic cracking oil
  • VR vacuum residue
  • These starting raw material oils are heated under an inert gas atmosphere such as nitrogen gas, helium gas, argon gas, preferably at a temperature of 350 to 550 ° C., more preferably 400 to 500 ° C., for preferably 0.5 to 10 hours, More preferably, it is obtained by heat-treating for 0.5 to 3 hours while stirring.
  • the pressure condition may be normal pressure or pressurized.
  • the heat-treated material has a high softening point and contains early coking components and solids such as ash and catalyst. Therefore, the mesophase generated by the heat treatment is removed together with these components in the form of bulk mesophase.
  • a homogeneous optically isotropic pitch with bulk mesophase removed is thus obtained.
  • the isotropic pitch thus obtained is heated in an inert gas atmosphere under a reduced pressure of 10 mmHg or less, preferably 1 to 5 mmHg, preferably at a temperature of 350 ° C. to 450 ° C., more preferably 380 to 420 ° C.
  • a homogeneous (narrow molecular weight distribution) petroleum-based anisotropic pitch is obtained by heat treatment.
  • the coating material preferably has an average particle size of 1 to 10 ⁇ m, more preferably 5 to 10 ⁇ m. When the coating material has an average particle size of 1 to 10 ⁇ m, the coating material is appropriately coated on the raw coal powder surface.
  • the amount of the coating material added is preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass, and more preferably 3 to 10 parts by mass with respect to 100 parts by mass of raw coal powder. is more preferable.
  • the amount of the coating material added is 2 to 30 parts by mass, the surface of the raw coal powder is appropriately coated with the coating material.
  • the amount added is large, the intra-particle voids increase due to granulation, and the tap density of the artificial graphite material for lithium ion secondary battery negative electrode after graphitization in step E described later may decrease.
  • step D general methods used for graphite materials for lithium ion secondary battery negative electrodes can be used without particular limitation.
  • liquid phase coating is performed by immersing raw coal powder in a coating material that is uniformly melted or dissolved in a liquid phase, or gasified coating material is introduced into a reaction apparatus together with a carrier gas, and raw coal powder is produced by a chemical reaction.
  • a mixed solid phase/semi-liquid phase coating method is preferable because the apparatus and manufacturing method are relatively simple and suitable for industrial mass production.
  • a mixer, a stirrer, a pulverizer, or the like can be used without particular limitation as a device for applying compressive shear stress.
  • Specific examples include Mechanofusion (registered trademark) system (manufactured by Hosokawa Micron Corporation), Nobilta (registered trademark) (manufactured by Hosokawa Micron Corporation), and Nanocura (registered trademark) (manufactured by Hosokawa Micron Corporation).
  • Nobilta registered trademark
  • Hosokawa Micron Corporation it is preferable to operate at a blade rotation speed of 1500 to 5000 rpm for 10 to 180 minutes.
  • step D may be performed in an atmosphere of an inert gas such as helium, nitrogen, or argon while heating at preferably 400 to 700°C, more preferably 500 to 600°C.
  • an inert gas such as helium, nitrogen, or argon
  • Step E is a step of graphitizing the coated raw coal powder described above to obtain an artificial graphite material for lithium ion secondary battery negative electrode. Specifically, the coated raw coal powder is further heat-treated to remove volatile components from the coated raw coal powder, dehydrated, thermally decomposed, and solid-phase graphitized. By performing this graphitization treatment, an artificial graphite material for a negative electrode of a lithium ion secondary battery of stable quality can be obtained.
  • the graphitization method for example, volatile components are removed from the coated raw coal powder, calcination is performed to obtain calcined coke, carbonization is performed, and then graphitization is performed. heat treatment. Calcination and carbonization may or may not be performed as desired. In the graphitization method, even if calcination and carbonization are omitted, there is almost no effect on the physical properties of the finally produced artificial graphite material.
  • Calcination is carried out, for example, in an inert gas atmosphere such as nitrogen, argon, or helium at a maximum temperature of preferably 500 to 1500° C., more preferably 900 to 1200° C., and a maximum temperature retention time of 0 to 10 hours.
  • an inert gas atmosphere such as nitrogen, argon, or helium
  • a maximum temperature preferably 500 to 1500° C., more preferably 900 to 1200° C., and a maximum temperature retention time of 0 to 10 hours.
  • the maximum temperature is preferably 500 to 1500° C., more preferably 900 to 1500° C., and the maximum temperature is maintained for 0 to 10 hours. and heat treatment.
  • the maximum temperature is preferably 2500 to 3200 ° C., more preferably 2800 to 3200 ° C., and the maximum temperature retention time is 0 to 100.
  • a method of performing heat treatment for a certain period of time can be mentioned.
  • the graphitization treatment may be performed, for example, by enclosing raw coal powder in a crucible made of graphite and using a graphitization furnace such as an Acheson furnace or an LWG furnace.
  • the manufacturing method of the artificial graphite material for a lithium ion secondary battery negative electrode according to the present embodiment has the steps A to E described above.
  • the manufacturing method of the artificial graphite material for the lithium ion secondary battery negative electrode of the present embodiment is controlled so that the specific surface area of the raw coal powder is 10.5 m 2 /g or more. Further, preferably, the volatile content of the raw coal powder obtained in step C is less than 3.71%, and the true density of the raw coal powder is more than 1.22 g/cm 3 and less than 1.73 g/cm 3 . is controlled to be As a result, in step D, the contact area between the raw coal powder and the covering material increases, forming a strong bond.
  • lithium ions can diffuse in the graphite material at high speed.
  • the electrodeposition of lithium metal is less likely to occur, and even when rapid charging is repeated, the deterioration of the discharge capacity is suitably suppressed. be done.
  • a lithium ion secondary battery having a negative electrode containing an artificial graphite material for a lithium ion secondary battery negative electrode which is finally obtained by forming a strong bond between the raw coal powder and the coating material, Even after repeated rapid charging, the covering material does not fall off easily and does not easily deteriorate.
  • a lithium ion secondary battery having a negative electrode containing an artificial graphite material obtained by the method for producing an artificial graphite material for a lithium ion secondary battery negative electrode according to the present embodiment has a discharge capacity that is less likely to deteriorate even after repeated rapid charging. becomes.
  • the artificial graphite material for a lithium ion secondary battery negative electrode of the present embodiment is an artificial graphite material for a lithium ion secondary battery negative electrode obtained by the method for producing the artificial graphite material for a lithium ion secondary battery negative electrode described above.
  • the artificial graphite material for a lithium ion secondary battery negative electrode of the present embodiment is manufactured by controlling the raw coal powder and the coating material to be strongly bonded. Therefore, even in the finally obtained artificial graphite material for a lithium ion secondary battery negative electrode of the present embodiment, lithium ions can be diffused at a high speed inside the particles of the artificial graphite material, so that the artificial graphite material has a lithium ion secondary It is useful as a material for battery negative electrodes.
  • the negative electrode for lithium ion secondary batteries of this embodiment contains the artificial graphite material for negative electrodes of lithium ion secondary batteries of the embodiment described above. Specifically, it contains the artificial graphite material for a lithium ion secondary battery negative electrode, a binder (binding agent), and optionally a conductive aid.
  • the negative electrode for a lithium ion secondary battery of the present embodiment may optionally include not only the artificial graphite material for the negative electrode of the lithium ion secondary battery of the above-described embodiment, but also known graphite materials or amorphous carbon as a graphite material. It may contain one or more materials.
  • Known graphite materials include, for example, artificial graphite materials other than the artificial graphite materials for lithium ion secondary battery negative electrodes of the above-described embodiments (hereinafter referred to as "other artificial graphite materials"), natural graphite materials, and the like. mentioned.
  • other artificial graphite materials artificial graphite materials
  • amorphous carbon materials well-known graphitizable carbon materials and non-graphitizable carbon materials can be used.
  • Natural graphite-based materials include naturally occurring graphite, highly purified graphite, spherical graphite (including mechanochemical treatment), highly purified products, and spherical products whose surfaces are treated with Examples include those coated with other carbon (for example, pitch-coated products, CVD-coated products, etc.), plasma-treated products, and the like.
  • the shape of other artificial graphite materials, natural graphite materials, and amorphous carbon materials is not particularly limited, and may be, for example, scale-like, spherical, or block-like. .
  • the mixing ratio of the artificial graphite material for the lithium ion secondary battery negative electrode of the above-described embodiment and the other artificial graphite material can be any ratio.
  • 20% by mass of the artificial graphite material for the lithium ion secondary battery negative electrode of the above-described embodiment It preferably contains 30% by mass or more, more preferably 50% by mass or more.
  • binder known binders used for negative electrodes for lithium ion secondary batteries can be used.
  • CMC carboxymethyl cellulose
  • SBR styrene-butadiene rubber
  • the content of the binder in the negative electrode for the lithium ion secondary battery of the present embodiment may be appropriately set as necessary in terms of the design of the lithium ion secondary battery. , preferably 1 to 30 parts by mass.
  • conductive aid a known one used for negative electrodes for lithium ion secondary batteries can be used.
  • the content of the conductive aid in the negative electrode for the lithium ion secondary battery of the present embodiment may be appropriately set as necessary in terms of the design of the lithium ion secondary battery. On the other hand, it is preferably 1 to 15 parts by mass.
  • solvent used for the negative electrode mixture known solvents used for negative electrodes for lithium ion secondary batteries can be used.
  • organic solvents such as dimethylformamide, N-methylpyrrolidone, isopropanol, and toluene, water, and the like can be used alone or in combination of two or more.
  • the binder As means for mixing the graphite material, the binder, the optionally contained conductive aid, and the solvent, for example, known devices such as a screw kneader, a ribbon mixer, a universal mixer, and a planetary mixer are used. be able to.
  • a method for pressure-molding the electrode mixture into a predetermined size for example, a method such as roll pressurization or pressurization can be used.
  • Pressure molding of the negative electrode mixture is preferably performed at a pressure of about 100 to 300 MPa.
  • the negative electrode for lithium ion secondary batteries of the present embodiment may be produced, for example, by the method shown below. That is, a graphite material containing the artificial graphite material for a lithium ion secondary battery negative electrode of the above-described embodiment, a binder, a conductive aid contained as necessary, and a solvent are kneaded by a known method. A slurry-like or paste-like negative electrode mixture is produced. After that, the slurry or paste negative electrode mixture is applied onto a negative electrode current collector such as copper foil and dried to form a sheet or pellet shape, and from the dried negative electrode mixture form layers. After that, the layer made of the dried negative electrode mixture is rolled and cut into a predetermined size to manufacture a negative electrode for a lithium ion secondary battery.
  • the method of applying the slurry-like or paste-like negative electrode mixture onto the negative electrode current collector is not particularly limited.
  • known methods such as a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method and a die coater method can be used.
  • a flat plate press, calendar rolls, or the like can be used for rolling.
  • the layer composed of the dried negative electrode mixture formed on the negative electrode current collector can be integrated with the negative electrode current collector by a known method such as a method using a roll, a press, or a combination thereof.
  • any material can be used for the negative electrode current collector as long as it does not form an alloy with lithium.
  • materials for the negative electrode current collector include copper, nickel, titanium, and stainless steel.
  • the shape of the negative electrode current collector can also be used without any particular limitation.
  • examples of the shape of the negative electrode current collector include a foil shape, a perforated foil shape, a mesh shape, and a band shape as a whole.
  • the negative electrode current collector for example, a porous material such as porous metal (foamed metal) or carbon paper may be used.
  • the negative electrode for a lithium ion secondary battery of the present embodiment described above contains the artificial graphite material for a negative electrode of a lithium ion secondary battery of the embodiment described above, the discharge capacity deteriorates even if charge and discharge cycles are repeated at a large current. hard to do
  • the lithium ion secondary battery of this embodiment is a lithium ion secondary battery having the negative electrode for lithium ion secondary battery of the embodiment described above.
  • FIG. 1 is a schematic cross-sectional view showing an example of the lithium ion secondary battery of this embodiment.
  • a lithium ion secondary battery 10 shown in FIG. 1 has a negative electrode 11 integrated with a negative electrode current collector 12 and a positive electrode 13 integrated with a positive electrode current collector 14 .
  • the negative electrode 11 the above-described negative electrode for lithium ion secondary battery of the present embodiment is used.
  • the negative electrode 11 and the positive electrode 13 are arranged to face each other with the separator 15 interposed therebetween.
  • the negative electrode 11 integrated with the negative electrode current collector 12 and the positive electrode 13 integrated with the positive electrode current collector 14 are covered with an aluminum laminate sheath 16 .
  • An electrolytic solution is injected into the aluminum laminate exterior 16 .
  • the positive electrode 13 contains an active material, a binder, and optionally a conductive aid.
  • active material known materials used for positive electrodes for lithium ion secondary batteries can be used, and metal compounds, metal oxides, metal sulfides, or conductive polymers capable of doping or intercalating lithium ions can be used. materials can be used.
  • LiCoO 2 lithium cobaltate
  • LiNiO 2 lithium nickelate
  • LiMn 2 O 4 lithium manganate
  • the binder the same binder as that used for the negative electrode 11 can be used.
  • the conductive aid the same conductive aid as used for the negative electrode 11 can be used.
  • the positive electrode current collector 14 for example, it is preferable to use a valve metal or an alloy thereof that forms a passive film on the surface by anodization in an electrolytic solution. Specifically, Al, Ti, Zr, Hf, Nb, Ta and alloys containing these metals can be used. Al and its alloys are particularly preferred because of their light weight and high energy density.
  • separator 15 for example, non-woven fabric, cloth, microporous film, or a combination thereof, which is mainly composed of polyolefin such as polyethylene or polypropylene, can be used. If the lithium ion secondary battery has a structure in which the positive electrode and the negative electrode do not come into direct contact with each other, no separator is required.
  • the electrolytic solution and electrolyte used in the lithium ion secondary battery 10 known organic electrolytic solutions, inorganic solid electrolytes, and polymer solid electrolytes used in lithium ion secondary batteries can be used.
  • the electrolytic solution it is preferable to use an organic electrolytic solution from the viewpoint of electrical conductivity.
  • organic electrolyte examples include ethers such as dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and ethylene glycol phenyl ether, N-methylformamide, N,N-dimethylformamide, N - amides such as ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, dimethylsulfoxide, sulfur-containing compounds such as sulfolane, methyl ethyl ketone, dialkyl ketones such as methyl isobutyl ketone; cyclic ethers such as tetrahydrofuran and 2-methoxytetrahydrofuran; cyclic carbonates such as ethylene carbonate, butylene carbonate, propylene carbonates
  • lithium salts include LiClO4, LiBF4 , LiPF6 , LiAlCl4 , LiSbF6 , LiSCN , LiCl, LiCF3SO3 , LiCF3CO2 , LiN ( CF3SO2 ) 2 , LiN ( C2F5 SO 2 ) 2 and the like.
  • Polymer solid electrolytes include polyethylene oxide derivatives and polymers containing such derivatives, polypropylene oxide derivatives and polymers containing such derivatives, phosphate ester polymers, polycarbonate derivatives and polymers containing such derivatives.
  • the lithium ion secondary battery 10 of the present embodiment includes the negative electrode 11 containing the artificial graphite material for the lithium ion secondary battery negative electrode of the present embodiment described above, the discharge capacity deteriorates even if the charge and discharge cycles are repeated at a large current. hard to do Therefore, the lithium ion secondary battery 10 of the present embodiment can be preferably used for industrial applications such as automobiles such as hybrid automobiles, plug-in hybrid automobiles and electric automobiles, and power storage for system infrastructure.
  • the lithium ion secondary battery of the present embodiment may use the negative electrode for lithium ion secondary batteries of the above-described embodiments, and there are no restrictions on the selection of members necessary for the battery configuration other than the negative electrode. is not.
  • the structure of the lithium ion secondary battery of the present invention is not limited to the lithium ion secondary battery 10 shown in FIG.
  • a method for manufacturing the lithium ion secondary battery of the present embodiment is not particularly limited as long as it utilizes the negative electrode for lithium ion secondary battery of the above embodiment, and a known manufacturing method can be used.
  • it includes a step of arranging the negative electrode for a lithium ion secondary battery of the embodiment described above and the positive electrode so as to face each other with a separator interposed therebetween. More specifically, the negative electrode for the lithium ion secondary battery of the embodiment described above and the negative electrode current collector are integrated, the positive electrode and the positive electrode current collector are integrated, and the negative electrode is integrated with the negative electrode current collector. and a step of arranging the positive electrode integrated with the positive electrode current collector so as to face each other with the separator interposed therebetween.
  • a single-layer electrode body in which the negative electrode integrated with the negative electrode current collector and the positive electrode integrated with the positive electrode current collector are arranged opposite to each other with a separator interposed therebetween is housed in an outer package, and the inside of the outer package is
  • the lithium ion secondary battery of the present embodiment can be obtained by injecting an electrolytic solution into the .
  • the structure of a lithium-ion secondary battery is, for example, a structure in which a wound electrode group in which a strip-shaped positive electrode and a negative electrode are spirally wound with a separator interposed therebetween is inserted into a battery case and sealed.
  • the structure of the lithium ion secondary battery may be a structure in which a laminated electrode plate group in which a plate-shaped positive electrode and a negative electrode are successively laminated via a separator is enclosed in an outer package.
  • the lithium-ion secondary battery of this embodiment can be used as, for example, a paper-type battery, a button-type battery, a coin-type battery, a laminate-type battery, a cylindrical battery, a prismatic battery, or the like.
  • raw material oil composition used in the production of the artificial graphite material for the lithium ion secondary battery negative electrode of Example 1 is referred to as "raw oil composition of Example 1", and other raw materials and manufactured Objects are also written in the same way.
  • Example 1 ⁇ Production of artificial graphite material for lithium ion secondary battery negative electrode> (Example 1) ⁇ Production of raw oil composition ⁇ The atmospheric distillation residue was distilled under reduced pressure and further hydrodesulfurized (sulfur content 380 mass ppm, density at 15 ° C. 0.83 g / cm 3 ), reaction temperature 530 ° C., total pressure 0.23 MPa, catalyst / oil Fluid catalytic cracking was performed at a ratio of 13 and a contact time of 7 seconds to obtain a fluid catalytic cracking residue.
  • the catalyst a silica-alumina catalyst supporting platinum was used.
  • “Sulfur content” means a value measured according to JIS K2541.
  • the atmospheric distillation residue (sulfur content 0.35% by mass, density 0.92 g/cm 3 at 15°C) was distilled under reduced pressure under the conditions of a heating furnace outlet temperature of 350°C and a pressure of 1.3 kPa.
  • a vacuum distillation residue with a temperature of 410° C., an asphalt content of 9% by mass, a saturate content of 61% by mass, a sulfur content of 0.1% by mass, and a nitrogen content of 0.3% by mass was obtained.
  • the mixture was selectively extracted with dimethylformamide to separate the aromatic component and the saturated component.
  • “Nitrogen content” means a value measured according to JIS K2609.
  • saturated content and “asphalt content” mean values measured using a thin layer chromatograph.
  • the normal paraffin content and the aromatic index fa of the obtained raw material oil composition of Example 1 were determined by the methods described below. Table 1 shows the results.
  • Normal paraffin content The normal paraffin content of the feed oil composition was measured by a gas chromatograph equipped with a capillary column. Specifically, a sample of non-aromatic components separated by elution chromatography was measured through a capillary column after being calibrated with normal paraffin standards. From this measured value, the content (% by mass) based on the total mass of the raw material oil composition was calculated.
  • the aromatic index fa of the feed oil composition was determined by the Knight method. Specifically, the carbon distribution was divided into three components (A1, A2, A3) as an aromatic carbon spectrum by the 13 C-NMR method.
  • A1 is the number of carbon atoms in the aromatic ring (half of the number of substituted aromatic carbons and unsubstituted aromatic carbons (corresponding to a peak of about 40 to 60 ppm in 13 C-NMR))
  • A2 is the number of substituted aromatic carbons.
  • A3 is the number of aliphatic carbons (corresponding to about 130-190 ppm peak in 13 C-NMR), the remaining half being aromatic carbons (corresponding to about 60-80 ppm peak in 13 C-NMR).
  • Example 1 was placed in a test tube and heat-treated for 3 hours at normal pressure of 500° C. for coking to obtain a raw material coal composition of Example 1.
  • Step B The obtained raw coal composition of Example 1 was heated at 550° C. under a mixed gas stream in which the volume ratio of nitrogen and oxygen was 83:17 to obtain a heat-treated raw coal composition of Example 1.
  • the temperature is raised from room temperature (25 ° C.) to 550 ° C. for 1 hour, the temperature is held at 550 ° C. for 1 hour, and the temperature is lowered from 550 ° C. to 400 ° C. for 1 hour.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • the dispersion liquid used for the measurement was obtained by mixing about 0.5 g of graphite powder with 0.1 wt % sodium hexametaphosphate aqueous solution (several drops) and a surfactant (several drops) in a mortar so as to be homogeneous. After that, 40 mL of a 0.1 wt % sodium hexametaphosphate aqueous solution was further added, and dispersed by an ultrasonic homogenizer.
  • the volatile content [mass fraction (%)] of the coking coal powder is measured according to “7. .2 Vertical Tubular Electric Furnace Method” and “b) Case of Coke”.
  • the true density [g/cm 3 ] of the raw coal powder is determined according to "7.3 true density” of "7. Density/porosity test method” described in “Cokes - test method” of JIS K 2151 (2004). Test method”.
  • the obtained optically isotropic pitch was heat-treated under a reduced pressure of 5 mmHg or less at 400° C. for 3 hours with stirring to obtain petroleum-based anisotropic pitch.
  • the anisotropic petroleum pitch thus obtained was pulverized with an air jet mill so as to have an average particle size of about 5 ⁇ m, to produce a coating material composed of the anisotropic petroleum pitch.
  • Example 1 ⁇ Covering the raw coal powder with the coating material
  • the obtained coating material and the raw coal powder of Example 1 were mixed at a weight ratio of 5:95, and the mixture was transferred to a compressive shear application device "Nobilta 130 type" manufactured by Hosokawa Micron Corporation.
  • the coated raw coal powder of Example 1 was obtained by charging so that the filling rate based on the bulk density was 50%, rotating the blade at 3500 rpm, and operating for 60 minutes with a gap between the blade and the housing of 3 mm. .
  • Example 1 The coated raw coal powder of Example 1 was put into a crucible made of graphite, and the crucible was embedded in packing coke as a heating material and a heat insulating material in an Acheson furnace, and then graphitized at 2950°C.
  • the heating time from room temperature (25 ° C.) to 2950 ° C. was 130 hours
  • the holding time at 2950 ° C. was 8 hours
  • the lithium ion secondary battery of Example 1 was taken out after cooling for 25 days.
  • An artificial graphite material for a negative electrode was obtained.
  • Example 2 ⁇ Production of raw oil composition ⁇ An atmospheric distillation residue with a sulfur content of 3.1% by mass was hydrodesulfurized in the presence of a catalyst so that the hydrocracking rate was 25% or less to obtain a hydrodesulfurized oil.
  • the hydrodesulfurization conditions were a total pressure of 18 MPa, a hydrogen partial pressure of 16 MPa, and a temperature of 380°C.
  • Example 2 The hydrodesulfurized oil thus obtained and the fluidized catalytic cracking residual oil obtained in Example 1 were mixed at a mass ratio of 5:95 to obtain the feed oil composition of Example 2. rice field.
  • the normal paraffin content and aromatic index fa of the raw oil composition of Example 2 were determined by the same method as in Example 1. Table 1 shows the results.
  • Example 2 The raw oil composition of Example 2 was coked by the same coking treatment as in Example 1 to obtain a raw coal composition of Example 2.
  • Step B The raw coal composition of Example 2 was heated at 700° C. under a mixed gas stream with a volume ratio of nitrogen to oxygen of 98:2 to obtain a heat-treated raw coal composition of Example 2.
  • the temperature is raised from room temperature (25 ° C.) to 700 ° C. for 2 hours, the temperature is held at 700 ° C. for 1 hour, and the temperature is lowered from 700 ° C. to 400 ° C. for 2 hours.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Example 2 The heat-treated raw coal composition of Example 2 was subjected to an airflow jet so that the average particle size measured by the method described in Example 1 [Measurement of average particle size] was in the range of 7.5 to 8.5 ⁇ m.
  • the raw coal powder of Example 2 was obtained by pulverizing with a mill.
  • the specific surface area, volatile content and true density of the raw coal powder of Example 2 were determined in the same manner as in Example 1. Table 1 shows the results.
  • Step D, Step E ⁇ The raw coal powder of Example 2 was coated with the same coating material as in Example 1 by the same method, and then graphitized by the same method as in Example 1 to obtain the artificial graphite material for lithium ion secondary battery negative electrode of Example 2. Obtained.
  • Example 3 ⁇ Production of raw oil composition ⁇ The saturated content of the fluid catalytic cracking residue obtained in Example 1 and the aromatic content of the fluid catalytic cracking residue were mixed at a mass ratio of 70:30 to obtain the feed oil composition of Example 3. rice field. The normal paraffin content and aromatic index fa of the raw oil composition of Example 3 were obtained by the same method as in Example 1. Table 1 shows the results.
  • Example 3 The raw oil composition of Example 3 was coked by the same coking treatment as in Example 1 to obtain a raw coal composition of Example 3.
  • Step B The raw coal composition of Example 3 was heated at 600° C. under a mixed gas stream containing nitrogen and oxygen at a volume ratio of 90:10 to obtain a heat-treated raw coal composition of Example 3.
  • the temperature was raised from room temperature (25 ° C.) to 600 ° C. for 1 hour and 30 minutes, the holding time at 600 ° C. was 1 hour, and the temperature was lowered from 600 ° C. to 400 ° C. for 1 hour and 30 minutes. After °C, cooling was performed for 4 hours while the airflow of the mixed gas was continued.
  • Example 3 The heat-treated raw coal composition of Example 3 was subjected to an airflow jet so that the average particle size measured by the method described in Example 1 (Measurement of average particle size) was in the range of 7.5 to 8.5 ⁇ m.
  • the raw coal powder of Example 3 was obtained by pulverizing with a mill.
  • the specific surface area, volatile content and true density of the raw coal powder of Example 3 were determined in the same manner as in Example 1. Table 1 shows the results.
  • Step D, Step E ⁇ The raw coal powder of Example 3 was coated with the same coating material as in Example 1 by the same method, and then graphitized by the same method as in Example 1 to obtain the artificial graphite material for lithium ion secondary battery negative electrode of Example 3. Obtained.
  • Example 4 ⁇ Production of raw oil composition ⁇ The saturated content of the vacuum distillation residue obtained in Example 1 and the aromatic content of the fluid catalytic cracking residue similarly obtained in Example 1 were mixed at a mass ratio of 30:70. No. 4 feed oil composition was obtained. The normal paraffin content and aromatic index fa of the raw oil composition of Example 4 were obtained by the same method as in Example 1. Table 1 shows the results.
  • Example 4 The raw oil composition of Example 4 was coked by the same coking treatment as in Example 1 to obtain a raw coal composition of Example 4.
  • Step B The raw coal composition of Example 4 was heated at 500° C. under a mixed gas stream containing nitrogen and oxygen at a volume ratio of 83:17 to obtain a heat-treated raw coal composition of Example 4.
  • the temperature is raised from room temperature (25 ° C.) to 500 ° C. for 1 hour, held at 500 ° C. for 1 hour, and cooled from 500 ° C. to 400 ° C. for 1 hour.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Example 4 The heat-treated raw coal composition of Example 4 was subjected to an airflow jet so that the average particle size measured by the method described in Example 1 (Measurement of average particle size) was in the range of 7.5 to 8.5 ⁇ m.
  • the raw coal powder of Example 4 was obtained by pulverizing with a mill.
  • the specific surface area, volatile content and true density of the raw coal powder of Example 4 were determined in the same manner as in Example 1. Table 1 shows the results.
  • Step D, Step E ⁇ The raw coal powder of Example 4 was coated with the same coating material as in Example 1 by the same method, and then graphitized by the same method as in Example 1 to obtain the artificial graphite material for lithium ion secondary battery negative electrode of Example 4. Obtained.
  • Example 5 ⁇ Production of raw oil composition ⁇ The saturated content of the fluid catalytic cracking residue obtained in Example 1, the aromatic content of the fluid catalytic cracking residue similarly obtained in Example 1, and the hydrodesulfurized oil obtained in Example 2, They were mixed at a mass ratio of 20:20:60 to obtain a raw material oil composition of Example 5. The normal paraffin content and aromatic index fa in the raw oil composition of Example 5 were obtained by the same methods as in Example 1. Table 1 shows the results.
  • Example 5 The raw oil composition of Example 5 was coked by the same coking treatment as in Example 1 to obtain a raw coal composition of Example 5.
  • Step B The raw coal composition of Example 5 was heated at 500° C. under a mixed gas stream containing nitrogen and oxygen at a volume ratio of 83:17 to obtain a heat-treated raw coal composition of Example 5.
  • the temperature is raised from room temperature (25 ° C.) to 500 ° C. for 1 hour, held at 500 ° C. for 1 hour, and cooled from 500 ° C. to 400 ° C. for 1 hour.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Example 5 The heat-treated raw coal composition of Example 5 was subjected to an airflow jet so that the average particle size measured by the method described in Example 1 (Measurement of average particle size) was in the range of 7.5 to 8.5 ⁇ m.
  • the raw coal powder of Example 5 was obtained by pulverizing with a mill.
  • the specific surface area, volatile content and true density of the raw coal powder of Example 5 were determined in the same manner as in Example 1. Table 1 shows the results.
  • Step D, Step E ⁇ The raw coal powder of Example 5 was coated with the same coating material as in Example 1 by the same method, and then graphitized by the same method as in Example 1 to obtain the artificial graphite material for lithium ion secondary battery negative electrode of Example 5. Obtained.
  • Step B The raw coal composition of Comparative Example 4 was heated at 500° C. under a mixed gas stream with a volume ratio of nitrogen to oxygen of 83:17 to obtain a heat-treated raw coal composition of Comparative Example 4.
  • the temperature is raised from room temperature (25 ° C.) to 500 ° C. for 1 hour, held at 500 ° C. for 1 hour, and cooled from 500 ° C. to 400 ° C. for 1 hour.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Step B The raw coal composition of Comparative Example 5 was heated at 700° C. under a mixed gas stream having a nitrogen/oxygen volume ratio of 98:2 to obtain a heat-treated raw coal composition of Comparative Example 5.
  • the temperature is raised from room temperature (25 ° C.) to 700 ° C. for 2 hours, the temperature is held at 700 ° C. for 1 hour, and the temperature is lowered from 700 ° C. to 400 ° C. for 2 hours.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Step B The raw coal composition of Comparative Example 6 was heated at 600° C. under a mixed gas stream having a volume ratio of nitrogen and oxygen of 90:10 to obtain a heat-treated raw coal composition of Comparative Example 6.
  • the temperature was raised from room temperature (25 ° C.) to 600 ° C. for 1 hour and 30 minutes, the holding time at 600 ° C. was 1 hour, and the temperature was lowered from 600 ° C. to 400 ° C. for 1 hour and 30 minutes. After °C, cooling was performed for 4 hours while the airflow of the mixed gas was continued.
  • Step B The raw coal composition of Comparative Example 7 was heated at 650° C. under a mixed gas stream containing nitrogen and oxygen at a volume ratio of 94:6 to obtain a heat-treated raw coal composition of Comparative Example 7.
  • the temperature was raised from room temperature (25 ° C.) to 650 ° C. for 1 hour and 30 minutes, the holding time at 650 ° C. was 1 hour, and the temperature was lowered from 650 ° C. to 400 ° C. for 1 hour and 30 minutes. After °C, cooling was performed for 4 hours while the airflow of the mixed gas was continued.
  • Comparative Example 8 The aromatic content of the fluid catalytic cracking residue obtained in Example 1 and the hydrodesulfurized oil obtained in Example 2 were mixed at a mass ratio of 15:85, and the feedstock of Comparative Example 8 A composition was obtained.
  • the normal paraffin content and aromatic index fa of the raw oil composition of Comparative Example 8 were obtained by the same methods as in Example 1. Table 1 shows the results.
  • Step B The raw coal composition of Comparative Example 8 was heated at 550° C. under a mixed gas stream in which the volume ratio of nitrogen and oxygen was 83:17 to obtain a heat-treated raw coal composition of Comparative Example 8.
  • the temperature is raised from room temperature (25 ° C.) to 550 ° C. for 1 hour, the temperature is held at 550 ° C. for 1 hour, and the temperature is lowered from 550 ° C. to 400 ° C. for 1 hour.
  • a process of cooling for 4 hours while continuing the flow of the mixed gas was performed.
  • Example 6 From a mixture obtained by mixing the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Example 1 and the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Comparative Example 3 at a mass ratio of 50:50 An artificial graphite material for a lithium ion secondary battery negative electrode of Example 6 was obtained.
  • Example 7 From a mixture obtained by mixing the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Example 1 and the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Comparative Example 3 at a mass ratio of 30:70 An artificial graphite material for a lithium ion secondary battery negative electrode of Example 7 was obtained.
  • Example 8 From a mixture obtained by mixing the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Example 1 and the artificial graphite material for a lithium ion secondary battery negative electrode obtained in Comparative Example 3 at a mass ratio of 20:80 An artificial graphite material for a lithium ion secondary battery negative electrode of Example 8 was obtained.
  • a lithium ion secondary battery 10 shown in FIG. 1 was produced as an evaluation battery by the method described below.
  • the negative electrode 11 the negative electrode current collector 12, the positive electrode 13, the positive electrode current collector 14, and the separator 15, the following materials were used.
  • CMC carboxymethyl cellulose
  • SBR styrene-butadiene rubber
  • the obtained negative electrode mixture was applied to the entire surface of one side of a copper foil having a thickness of 18 ⁇ m as the negative electrode current collector 12, followed by drying and rolling. A negative electrode sheet formed on 12 was obtained. The coating amount of the negative electrode mixture per unit area on the negative electrode sheet was adjusted so that the mass of the graphite material was about 10 mg/cm 2 .
  • the negative electrode sheet was cut to have a width of 32 mm and a length of 52 mm. Then, part of the negative electrode 11 was scraped off in the direction perpendicular to the longitudinal direction of the sheet to expose the negative electrode current collector 12 that serves as a negative electrode lead plate.
  • the obtained positive electrode mixture was applied to the entire surface of a 30 ⁇ m thick aluminum foil as the positive electrode current collector 14, dried and rolled, and the positive electrode 13, which is a layer made of the positive electrode mixture, became the positive electrode current collector.
  • a positive electrode sheet formed on 14 was obtained.
  • the amount of the positive electrode mixture applied to the positive electrode sheet per unit area was adjusted to be about 17.2 mg/cm 2 in terms of the mass of NCM523.
  • the positive electrode sheet was cut to have a width of 30 mm and a length of 50 mm. Then, part of the positive electrode 13 was scraped off in the direction perpendicular to the longitudinal direction of the sheet to expose the positive electrode current collector 14 that serves as a positive electrode lead plate.
  • Separator 15 As the separator 15, a cellulose-based nonwoven fabric (TF40-50 manufactured by Nippon Kodo Paper Co., Ltd.) was used. In order to manufacture the lithium ion secondary battery 10 shown in FIG. The positive electrode sheet integrated with the lead plate, the separator 15, and other members used in the lithium ion secondary battery 10 were dried. Specifically, the negative electrode sheet and the positive electrode sheet were dried at 120° C. for 12 hours or more under reduced pressure. Also, the separator 15 and other members were dried at 70° C. for 12 hours or more under reduced pressure.
  • the dried negative electrode sheet, positive electrode sheet, separator 15 and other members were assembled in an argon gas circulation type glove box whose dew point was controlled to -60°C or lower.
  • a single-layer electrode body in which the positive electrode 13 and the negative electrode 11 were laminated facing each other with the separator 15 interposed therebetween and fixed with a polyimide tape (not shown) was obtained.
  • the negative electrode sheet and the positive electrode sheet were laminated such that the peripheral edge portion of the laminated positive electrode sheet was surrounded inside the peripheral edge portion of the negative electrode sheet.
  • the single-layer electrode body was housed in the aluminum laminate sheath 16, and an electrolytic solution was injected inside.
  • an electrolytic solution lithium hexafluorophosphate (LiPF 6 ) as an electrolyte is dissolved in a solvent so as to have a concentration of 1 mol/L, and further vinylene carbonate (VC) is mixed so as to have a concentration of 1% by mass. I used something else.
  • a solvent a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) in a volume ratio of 30:40:30 was used.
  • the battery was placed in a constant temperature room at 25 ° C., the charging current was 30 mA, the charging voltage was 4.2 V, and the charging time was 3 hours. The battery was discharged at a constant current (30 mA) until the battery voltage reached 3.0V. These charging, resting, and discharging were regarded as one charging/discharging cycle, and the charging/discharging cycle was repeated three times under the same conditions.
  • constant current/constant voltage charging was performed with a charging current of 160 mA, a charging voltage of 4.2 V, and a charging time of 3 hours. It was discharged to 3.0V.
  • These charging, resting, and discharging were regarded as one charging/discharging cycle, and the charging/discharging cycle was repeated 100 times under the same conditions.
  • the battery was placed in the same constant temperature bath and left for 5 hours. Then, the charge/discharge cycle was repeated three times under the same conditions as the charge/discharge cycle used to obtain the initial discharge capacity. discharge capacity after repeated charging”.
  • raw coal powder having a specific surface area of 10.5 m 2 /g or more was used in the method for producing the artificial graphite material for lithium ion secondary battery negative electrode of Examples 1 to 5.
  • the raw coal powder has a volatile content of less than 3.71% and a true density within the range of more than 1.22 g/cm 3 and less than 1.73 g/cm 3 .
  • the "discharge capacity retention rate (%) after repeated rapid charging” was 70% or more. From this, it was confirmed that the discharge capacity of the lithium ion secondary batteries using the negative electrodes containing the artificial graphite materials for lithium ion secondary battery negative electrodes of Examples 1 to 5 is difficult to deteriorate even if rapid charging is repeated. .
  • the artificial graphite material for a lithium ion secondary battery negative electrode of Example 1 in which raw coal powder having a specific surface area of 10.5 m 2 /g or more is used, and In the lithium ion secondary batteries of Examples 6 to 8 using the negative electrode in combination with another artificial graphite material (artificial graphite material for lithium ion secondary battery negative electrode of Comparative Example 3), "rapid charging was repeated The post-discharge capacity retention rate (%)" was 70% or more, and it was confirmed that the discharge capacity hardly deteriorated even after repeated rapid charging.
  • a lithium ion secondary battery having a negative electrode containing an artificial graphite material obtained by the method for producing an artificial graphite material for a lithium ion secondary battery negative electrode according to the present invention has a discharge capacity that is less likely to deteriorate even after repeated rapid charging. . Therefore, a lithium ion secondary battery having a negative electrode containing an artificial graphite material obtained by the method for producing an artificial graphite material for a lithium ion secondary battery negative electrode according to the present invention is suitable for use in electric vehicles, system interconnection of natural energy, and the like. can be preferably used for industrial purposes.

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PCT/JP2022/023950 2021-06-18 2022-06-15 リチウムイオン二次電池負極用人造黒鉛材料の製造方法、リチウムイオン二次電池負極用人造黒鉛材料、リチウムイオン二次電池用負極、及び、リチウムイオン二次電池 Ceased WO2022265040A1 (ja)

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US18/570,495 US20240290974A1 (en) 2021-06-18 2022-06-15 Method for producing synthetic graphite material for lithium-ion secondary battery negative electrodes, synthetic graphite material for lithium-ion secondary battery negative electrodes, negative electrode for lithium-ion secondary batteries, and lithium-ion secondary battery
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EP22825028.8A EP4358190A4 (en) 2021-06-18 2022-06-15 METHOD FOR PRODUCING ARTIFICIAL GRAPHITE MATERIAL FOR NEGATIVE ELECTRODES OF LITHIUM ION SECONDARY BATTERY, ARTIFICIAL GRAPHITE MATERIAL FOR NEGATIVE ELECTRODES OF LITHIUM ION SECONDARY BATTERY, NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERIES, AND LITHIUM ION SECONDARY BATTERY

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