WO2016121711A1 - リチウムイオン二次電池負極材用黒鉛粉の製造方法、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材用黒鉛粉の製造方法、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 PDFInfo
- Publication number
- WO2016121711A1 WO2016121711A1 PCT/JP2016/052063 JP2016052063W WO2016121711A1 WO 2016121711 A1 WO2016121711 A1 WO 2016121711A1 JP 2016052063 W JP2016052063 W JP 2016052063W WO 2016121711 A1 WO2016121711 A1 WO 2016121711A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- secondary battery
- graphite
- ion secondary
- electrode
- graphite powder
- Prior art date
Links
Classifications
-
- 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
- C01B32/20—Graphite
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/04—Specific amount of layers or specific thickness
-
- 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
- H01M4/36—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
- H01M4/5835—Comprising fluorine or fluoride salts
-
- 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 graphite powder, a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery using the same. More specifically, graphite powder suitable as an electrode material for a lithium ion secondary battery, a negative electrode material for a battery, and high capacity using the negative electrode material, excellent charge / discharge cycle characteristics, and small electrode expansion due to charge / discharge.
- the present invention relates to a lithium ion secondary battery.
- Lithium ion secondary batteries are mainly used as power sources for portable devices and the like.
- functions of portable devices and the like have been diversified and power consumption has been increasing. Therefore, the lithium ion secondary battery is required to increase its battery capacity and simultaneously improve the charge / discharge cycle characteristics.
- high-power and large-capacity secondary batteries such as electric tools such as electric drills and hybrid vehicles.
- lead secondary batteries, nickel cadmium secondary batteries, and nickel metal hydride secondary batteries have been mainly used in this field.
- expectations for high-density lithium-ion secondary batteries that are small, light, and high are high.
- the main required characteristics are long-term cycle characteristics over 10 years and large current load characteristics for driving high-power motors.
- a high volumetric energy density is required to extend the cruising range, which is harsh compared to mobile applications.
- This lithium ion secondary battery generally uses a lithium salt such as lithium cobaltate as a positive electrode active material and a carbonaceous material such as graphite as a negative electrode active material.
- a lithium salt such as lithium cobaltate
- a carbonaceous material such as graphite
- Graphite includes natural graphite and artificial graphite. Of these, natural graphite is available at low cost and has a high discharge capacity due to its high crystallinity. However, since natural graphite is scaly, when it is made into a paste with a binder and applied to a current collector, the natural graphite is oriented in one direction. When a secondary battery including an electrode using natural graphite having a high orientation as a carbonaceous material is charged, the electrode expands in one direction, and the performance as a battery is reduced. The expansion of the electrode leads to the expansion of the battery, and there is a possibility of damaging the substrate around the battery by cracking of the negative electrode due to the expansion and peeling of the paste from the current collector.
- Patent Document 1 proposes a method of coating carbon on the surface of natural graphite processed into a spherical shape.
- the cycle characteristics are not sufficient.
- Patent Document 4 discloses artificial graphite having excellent cycle characteristics, but there is room for improvement in energy density per volume.
- Patent Document 6 discloses an artificial graphite negative electrode manufactured from raw acicular coke. Although the improvement of the initial charge / discharge efficiency is seen with respect to the conventional artificial graphite, the discharge capacity is inferior to that of the natural graphite material.
- Patent Document 7 discloses an artificial graphite negative electrode manufactured from coke obtained by coating petroleum pitch with a liquid phase.
- Patent Document 8 discloses a method in which a coal tar pitch and a graphitization catalyst such as titanium oxide are mixed, then coked at a low temperature, carbonized at a medium temperature, and then graphitized at a high temperature to obtain graphite powder. Disclosure. Although the obtained graphite powder has improved discharge capacity and initial charge / discharge efficiency, it has many manufacturing processes, and the residual metal content in the graphite powder is high, so the possibility of long-term use is unknown.
- Japanese Patent No. 3534391 (US Pat. No. 6,632,569) Japanese Unexamined Patent Publication No. 4-190555 Japanese Patent No. 3361510 Japanese Unexamined Patent Publication No. 7-320740 (US Pat. No. 5,587,255) WO2011 / 049199 (US Pat. No. 8,372,373) Japanese Unexamined Patent Publication No. 2001-23638 WO2003 / 064560 (US Pat. No. 7,323,120) Japanese Unexamined Patent Publication No. 2002-025556
- Scale-like natural graphite, spheroidized natural graphite and natural graphite described in Patent Document 1 exhibit high discharge capacity, but it is difficult to achieve long-term cycle characteristics required for large batteries.
- artificial graphite excellent in cycle characteristics can be produced by graphitizing an easily graphitizable raw material such as petroleum, coal pitch, coke and the like.
- acicular coke with high crystallinity shows a high discharge capacity, but it becomes scaly and tends to be oriented in the electrode. Therefore, it is difficult to simultaneously achieve high discharge capacity, long-term cycle characteristics, and low orientation within the electrode.
- the present invention has the following configuration.
- a negative electrode material for a lithium ion secondary battery comprising a step of pulverizing a graphite precursor and a step of graphitizing by heating a mixture of the pulverized graphite precursor and an alkali compound at 2800 to 3500 ° C.
- a method for producing graphite powder [2] The method for producing a graphite powder for a negative electrode material for a lithium ion secondary battery as described in [1] above, wherein the alkali compound is an alkali metal or alkaline earth metal hydroxide.
- a step of obtaining a graphite powder for a lithium ion secondary battery negative electrode material by the method according to any one of 1 to 5 above, and a negative electrode for a lithium ion secondary battery using the obtained graphite powder as an active material The manufacturing method of the negative electrode for lithium ion secondary batteries which has a process.
- the manufacturing method of a lithium ion secondary battery which has the process which uses the obtained said negative electrode as the negative electrode of a lithium ion secondary battery.
- the lithium ion battery having high capacity and cycle characteristics and small expansion of the electrode due to charge and discharge, and high capacity and low orientation for realizing the lithium ion battery.
- the combined negative electrode and negative electrode material for a lithium ion battery can be obtained by a simple method.
- the following method is suitable for the method of producing graphite powder for negative electrode material of lithium ion secondary battery.
- the graphite precursor used for the raw material of the graphite powder is not particularly limited as long as it is a carbon material that can be graphitized by firing, but coke or coal is preferable in terms of easy handling.
- a graphite precursor may be used independently or may be used in combination of 2 or more type.
- Coke can be raw coke or calcined coke.
- a raw material for coke for example, coal pitch, petroleum pitch, and a mixture thereof can be used.
- calcined coke obtained by heating raw coke obtained by delayed coking under specific conditions in an inert gas atmosphere is preferred.
- decant oil obtained by removing the catalyst after fluidized bed catalytic cracking or coal tar extracted from bituminous coal at a temperature of 200 ° C. or higher is used for heavy distillate during crude oil refining.
- the liquid raw material such as decant oil is preferably heated to 450 ° C. or higher, more preferably 510 ° C. or higher, by raising the temperature to 450 ° C. The remaining charcoal rate increases during coke calcination.
- Calcination means heating to remove moisture and volatile organic components contained in raw materials such as raw coke obtained by delayed coking.
- the pressure in the drum is preferably maintained at normal pressure or higher, more preferably 300 kPa or higher, and further preferably 400 kPa or higher. By maintaining the pressure in the drum at or above normal pressure, the capacity of the negative electrode is further increased.
- coking is performed under conditions that are severer than usual, whereby a liquid raw material such as decant oil can be further reacted to obtain coke having a higher degree of polymerization.
- Calcination can be performed by heating by electricity or flame heating using LPG, LNG, kerosene, heavy oil or the like. Since heating at 2000 ° C. or lower is sufficient for removing moisture and volatile organic compounds contained in the raw material, flame heating, which is a cheaper heat source, is preferable for mass production. Especially when processing on a large scale, the energy cost can be reduced by heating the coke in the internal flame type or the internal heat type while burning the organic compounds of the fuel and unheated coke in the rotary kiln. Is possible.
- Coal is classified into anthracite, bituminous coal, subbituminous coal, and lignite according to the calorific value and fuel ratio.
- the coal used as the graphite precursor is not particularly limited, but anthracite coal that contains few volatile components and easily grows crystals is suitable. Mined coal is coarsely crushed and, in some cases, dried.
- the crushing and drying equipment is not particularly limited. For example, a biaxial roll crusher or a jaw crusher can be used as the crushing equipment, and a rotary kiln or the like can be used as the drying equipment.
- the graphite precursor Prior to the graphitization treatment, the graphite precursor is pulverized.
- the graphite precursor is large, it is preferable to first coarsely pulverize to a size of about 5 cm.
- Coarse pulverization can be performed using a hammer, a biaxial roll crusher, a jaw crusher, etc., and the crushed lump is passed through a sieve with a 1 mm side of the net, and the remaining part of the sieve is 90 mass in total. It is preferable to grind so that it may become more than%. If excessive pulverization is performed to such an extent that a fine powder having a particle diameter of 1 mm or less is generated in large quantities, there is a risk that in the subsequent heating process or the like, the fine powder will rise after drying or burnout may increase.
- the coarsely pulverized graphite precursor is further finely pulverized.
- the pulverization method is not particularly limited, and can be performed using a known jet mill, hammer mill, roller mill, pin mill, vibration mill or the like.
- the pulverization is preferably performed so that the median diameter D 50 in the volume-based cumulative particle size distribution by laser diffraction method is 1 to 50 ⁇ m.
- D 50 is more preferably 5 to 35 ⁇ m, and further preferably 10 to 25 ⁇ m.
- D 50 is more preferably 25 ⁇ m or less.
- the pulverized graphite precursor is mixed with an alkali compound (an alkali metal or alkaline earth metal compound).
- alkali metal include lithium, sodium, potassium, rubidium, and cesium
- examples of the alkaline earth metal include magnesium, calcium, strontium, and barium, and preferably calcium.
- the type of the compound is not particularly limited, and examples thereof include oxides, hydroxides, hydrides, carbides, and the like, preferably hydroxides.
- the alkali compound is preferably calcium hydroxide.
- the method of mixing is not particularly limited, but the alkali compound is dissolved in a solvent such as water or alcohol, and the solution is sprayed onto the pulverized graphite precursor, or the powder of the alkali compound and the pulverized graphite precursor are simply added.
- a solvent such as water or alcohol
- Alkali compounds become impurities when remaining in the graphite powder, but hardly remain because they evaporate with high temperature heating during the graphitization treatment.
- the mass ratio of the graphite precursor to the alkali compound is preferably 70:30 to 97: 3, more preferably 75:25 to 95: 5, and still more preferably 80:20 to 90:10.
- the graphite precursor after pulverization and the alkali compound are mixed, and then graphitized.
- the temperature for performing the graphitization treatment is 2800 to 3500 ° C., preferably 3050 to 3500 ° C., more preferably 3150 to 3500 ° C.
- the processing time is, for example, about 10 minutes to 100 hours.
- the degree of graphitization increases, graphite crystals grow, and an electrode capable of storing lithium ions at a higher capacity can be obtained.
- the graphitization temperature is preferably 3500 ° C. or lower. If it is less than 2800 ° C., the degree of graphitization is small.
- Alkali compounds have the effect of promoting graphitization (catalytic graphitization).
- graphitization For example, calcium oxide forms unstable compounds with carbon, and graphite with high crystallinity reprecipitates. This catalytic graphitization effect improves crystallinity and discharge capacity.
- the alkali compound to be used is a hydroxide, it is decomposed in the temperature rising process to produce water.
- calcium hydroxide is thermally decomposed at 580 ° C. to produce water and calcium oxide.
- a method of performing graphitization with water vapor water vapor activation
- carbon is oxidized by water vapor, and pores are formed between crystallites of the carbon material.
- alkali vapor penetrates between the layers of graphite and expands the layers to form pores between the layers.
- This alkali activation effect is enhanced when there are pores between the crystallites of the carbon material.
- the thickness Lc of the crystallite in the c-axis direction decreases.
- the graphitization treatment is performed by mixing an alkali compound with a graphite precursor such as coke or coal, thereby reducing the thickness Lc of the crystallite in the c-axis direction.
- a graphite precursor such as coke or coal
- graphitization is performed in an atmosphere that does not contain oxygen, for example, in a nitrogen gas-filled environment or an argon gas-filled environment.
- graphitization can also be performed in an environment containing a certain concentration of oxygen. It is.
- the graphitization when the graphitization is performed in a state where oxygen is contained in the reaction furnace, it is preferable to remove the impurity components derived from the mixed graphite precursor and the alkali compound at the portion in contact with oxygen because they are easily precipitated. . That is, a range from a portion where the raw material and oxygen are in contact to a predetermined depth is removed, and a portion deeper than the predetermined depth is obtained as a graphite material.
- the predetermined depth is 2 cm from the surface, more preferably 3 cm, and even more preferably 5 cm or more.
- the graphite powder for negative electrode material of lithium ion secondary battery according to one embodiment of the present invention has an average interplanar spacing of (002) planes by powder X-ray diffraction (XRD).
- d 002 is 0.33565 to 0.33580 nm, and the c-axis thickness Lc of the crystallite is 90 nm or less, or d 002 is 0.33540 to 0.33564 nm and Lc is 130 nm or less. It is.
- the peak intensity H of the diffraction line derived from the (004) plane when the density of the electrode using the graphite powder according to one embodiment of the present invention as the active material of the negative electrode is 1.3 to 1.5 g / cm 3.
- the intensity ratio H 004 / H 110 between 004 and the peak intensity H 110 of the diffraction line derived from the (110) plane is preferably 60 or less.
- H 004 / H 110 is an index of orientation, and the smaller the value, the lower the orientation of the active material in the electrode. More preferable H 004 / H 110 is 10 or less.
- d 002 , Lc, and H 004 / H 110 can be measured using a powder X-ray diffraction method by a known method (Noda Inayoshi, Inagaki Michio, Japan Society for the Promotion of Science, 117th Committee Materials, 117- 71-A-1 (1963), Michio Inagaki et al., Japan Society for the Promotion of Science, 117th Committee Sample, 117-121-C-5 (1972), Michio Inagaki, “Carbon”, 1963, No. 36, 25- (See page 34).
- the graphite powder for a negative electrode material for a lithium ion secondary battery preferably has a BET specific surface area of 0.4 to 15 m 2 / g, more preferably 1 to 11 m 2 / g. .
- the BET specific surface area is measured by a general method of measuring the amount of adsorption / desorption of gas per unit mass. As a measuring device, for example, NOVA-1200 manufactured by Yuasa Ionics Co., Ltd. can be used, and measurement can be performed by adsorption of nitrogen gas molecules.
- the graphite powder for a negative electrode material for a lithium ion secondary battery preferably has a median diameter D 50 in a volume-based cumulative particle size distribution by a laser diffraction method of 5 to 35 ⁇ m.
- D 50 is preferably 10 to 30 ⁇ m, more preferably 15 to 25 ⁇ m. It is more preferable that D 50 is 15 ⁇ m or more because an unintended reaction hardly occurs. In view of the necessity of generating a large current when used as a driving power source for automobiles and the like, D 50 is more preferably 25 ⁇ m or less.
- the total pore volume by the nitrogen gas adsorption method under liquid nitrogen cooling Becomes 10.0 to 65.0 ⁇ L / g.
- the electrolytic solution easily penetrates into the electrode and the rapid charge / discharge characteristics are improved.
- the total pore volume is 10.0 ⁇ L / g or more, the negative electrode obtained from the graphite powder becomes a negative electrode with few side reactions and high initial charge / discharge efficiency.
- the graphite powder for a negative electrode material for a lithium ion secondary battery has a high discharge capacity.
- the working electrode of the coin battery composed of the working electrode using the graphite powder as an active material, the lithium metal counter electrode, the separator, and the electrolyte is produced by a method including a step of compressing the graphite powder with a predetermined pressure, the first cycle
- the discharge capacity per mass of the active material can be 350 mAh / g or more.
- the graphite powder for a lithium ion secondary battery negative electrode material has an electrode density of 1. when the electrode using the graphite powder as an active material is compressed at a pressure of 3 t / cm 2 . It is preferably 3 to 2.1 g / cm 3 . A more preferable electrode density is 1.5 to 2.1 g / cm 3 .
- the graphite powder for a negative electrode material for a lithium ion secondary battery according to an embodiment of the present invention does not substantially contain a metal element.
- “Substantially free” means that the amount of metal element detected by ICP emission spectroscopic analysis is less than 100 ppm by mass for each metal element.
- the negative electrode material contains impurities such as metal elements, there is a risk that an increase in electrical resistance or a side reaction occurs, resulting in deterioration of battery characteristics or heat generation. Therefore, in general, the lower the impurity concentration, the better, preferably 50 ppm by mass or less, more preferably 30 ppm by mass or less, and still more preferably 20 ppm by mass or less.
- the graphite powder for a negative electrode material for a lithium ion secondary battery preferably has an R value determined by laser Raman spectroscopy of 0.05 to 0.5, more preferably 0.05 to 0.5. 0.15.
- the R value is in the range of 0.05 to 0.5, lithium ions are smoothly inserted and released, and the internal structure of the graphite structure has regularity. Can be secured.
- the R value is an intensity ratio ID between a peak intensity ID in the range of 1300 to 1400 cm ⁇ 1 and a peak intensity IG in the range of 1580 to 1620 cm ⁇ 1 in the spectrum obtained by laser Raman spectroscopy. / I mean IG.
- the R value is determined by using, for example, a laser Raman spectrometer (NRS-3100) manufactured by JASCO Corporation, an excitation wavelength of 532 nm, an incident slit width of 200 ⁇ m, an exposure time of 15 seconds, an integration count of 2 times, and a diffraction grating of 600 lines / mm. conditions in was measured can be calculated based on the peak intensity in the vicinity of the resulting 1360cm peak intensity near -1 and 1580 cm -1.
- NRS-3100 laser Raman spectrometer
- the graphite material for electrodes which concerns on one embodiment of this invention comprises the said graphite powder.
- a battery electrode having a high energy density can be obtained while maintaining a high capacity, a high coulomb efficiency, and a high cycle characteristic.
- a graphite material for electrodes for example, it can be used as a negative electrode active material and a negative electrode conductivity-imparting material of a lithium ion secondary battery.
- d 002 is 0.3370 nm or less with respect to 100 parts by mass of the graphite powder.
- Spherical natural graphite or artificial graphite blended in an amount of 0.01 to 200 parts by weight, preferably 0.01 to 100 parts by weight, or natural graphite having d 002 of 0.3370 nm or less and an aspect ratio of 2 to 100 It is also possible to use artificial graphite (for example, flaky graphite) blended in an amount of 0.01 to 120 parts by mass, preferably 0.01 to 100 parts by mass.
- the mixing can be performed by appropriately selecting a mixed material and setting a mixing ratio according to required battery characteristics.
- carbon fiber can be added to the electrode graphite material.
- the blending amount is 0.01 to 20 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the graphite powder.
- carbon fibers examples include organic carbon fibers such as PAN-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers, and vapor grown carbon fibers.
- organic carbon fibers such as PAN-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers
- vapor grown carbon fibers having particularly high crystallinity and high thermal conductivity are preferable.
- the vapor grown carbon fiber is produced, for example, by using an organic compound as a raw material, introducing an organic transition metal compound as a catalyst into a high-temperature reactor together with a carrier gas, and subsequently heat-treating (Japanese Patent Publication No. 62-49363). No., Japanese Patent No. 2778434, etc.).
- the fiber diameter is 2 to 1000 nm, preferably 10 to 500 nm, and the aspect ratio is preferably 10 to 15000.
- organic compound used as a raw material for carbon fiber examples include gases such as toluene, benzene, naphthalene, ethylene, acetylene, ethane, natural gas, carbon monoxide, and mixtures thereof. Of these, aromatic hydrocarbons such as toluene and benzene are preferred.
- the organic transition metal compound contains a transition metal serving as a catalyst.
- the transition metal include elements from Group 3 to Group 11 of the Periodic Table.
- compounds such as ferrocene and nickelocene are preferable.
- the carbon fiber may be one obtained by pulverizing or pulverizing long fibers obtained by a vapor phase method or the like. Further, the carbon fibers may be aggregated in a flock shape.
- the carbon fiber is preferably one having no thermal decomposition product derived from an organic compound or the like on its surface or one having a high carbon structure crystallinity.
- Carbon fibers to which no pyrolyzate is attached or carbon fibers having a high carbon structure crystallinity are obtained by, for example, firing (heat treatment) carbon fibers, preferably vapor grown carbon fibers, in an inert gas atmosphere. It is done.
- carbon fibers to which no pyrolyzate is attached can be obtained by heat treatment at about 800 to 1500 ° C. in an inert gas such as argon.
- the carbon fiber having high carbon structure crystallinity is preferably obtained by heat treatment in an inert gas such as argon at 2000 ° C. or higher, more preferably 2000 to 3000 ° C.
- the carbon fiber preferably contains a branched fiber. Further, the branched portion may have a communicating hollow structure.
- the carbon layer constituting the cylindrical portion of the fiber is continuous.
- a hollow structure is a structure in which a carbon layer is wound in a cylindrical shape, and includes a structure that is not a complete cylinder, a structure that has a partial cut portion, a structure in which two stacked carbon layers are bonded to one layer, etc. .
- the cross section of the cylinder is not limited to a perfect circle, but includes a shape close to an ellipse or a polygon.
- the carbon fibers have an average spacing d 002 of the X-ray diffraction (002) plane is preferably 0.3440nm or less, more preferably 0.3390nm or less, more preferably not more than 0.3380Nm. Further, it is preferable that the thickness Lc in the c-axis direction of the crystallite is 40 nm or less.
- the electrode density of the graphite material for electrodes is preferably included in the range described for the graphite powder.
- the electrode paste according to an embodiment of the present invention comprises the electrode graphite material and a binder.
- This electrode paste is obtained by kneading the electrode graphite material 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 known polymers such as fluorine-based polymers such as polyvinylidene fluoride and polytetrafluoroethylene, and rubber-based polymers 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 graphite material for electrodes, but 3 to 20 parts by mass is particularly preferable.
- a solvent can be used when kneading.
- solvent known solvents suitable for each binder, such as toluene and N-methylpyrrolidone in the case of fluorine-based polymers; water in the case of rubber-based polymers; dimethylformamide in the case of other binders, 2 -Propanol and the like.
- a binder using water as a solvent it is preferable to use a thickener together. The amount of the solvent is adjusted so that the viscosity is easy to apply to the current collector.
- Electrode which concerns on one embodiment of this invention consists of a molded object of the said paste for electrodes.
- the electrode is obtained, for example, by applying the electrode paste onto a current collector, drying, and pressure-molding.
- the current collector include metal foils such as aluminum, nickel, copper, and stainless steel, or meshes.
- 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 doctor blade and a bar coater.
- Examples of the pressure molding method include molding methods such as roll pressing and press pressing.
- the pressure during pressure molding is preferably 0.5 to 5.0 t / cm 2 , more preferably 1.0 to 4.0 t / cm 2 , and still more preferably 1.5 to 3.0 t / cm 2 . .
- the maximum value of the electrode density of the electrode obtained using this electrode paste is usually 1.5 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 secondary battery according to an embodiment of the present invention will be described using 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, and the electrode according to one embodiment of the present invention is used for the negative electrode.
- a lithium-containing transition metal oxide is usually used as the positive electrode active material, preferably at least selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo and W.
- An oxide mainly containing one kind of transition metal element and lithium and having a molar ratio of lithium to transition metal element of 0.3 to 2.2 is used. More preferably, it is an oxide mainly containing at least one transition metal element selected from V, Cr, Mn, Fe, Co and Ni and lithium.
- Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc. may be contained within a range of less than 30 mol% with respect to the transition metal present mainly.
- the value of x is a value before the start of charging / discharging, and increases / decreases by charging / discharging.
- the median diameter D 50 in the volume-based cumulative particle size distribution of the positive electrode active material is not particularly limited, but is preferably 0.1 to 50 ⁇ m, and the volume occupied by the particle group of 0.5 to 30 ⁇ m is 95% or more of the total volume. Preferably there is. Further, it is more preferable that the volume occupied by the particle group having D 50 of 3 ⁇ m or less is 18% or less of the total volume, and the volume occupied by the particle group having D 50 of 15 to 25 ⁇ m is 18% or less of the total volume. . D 50 can be measured by a laser diffraction type particle size distribution measuring device such as Malvern Mastersizer (registered trademark).
- the specific surface area of the positive electrode active material is not particularly limited, but the specific surface area measured by the BET method is preferably 0.01 to 50 m 2 / g, and more preferably 0.2 to 1 m 2 / g.
- the pH of the supernatant when the positive electrode active material 5 g is dissolved in 100 ml of distilled water is preferably 7-12.
- a separator may be provided between the positive electrode and the negative electrode.
- the separator include non-woven fabrics, cloths, microporous films, or combinations thereof, which are mainly composed of polyolefins such as polyethylene and polypropylene.
- organic electrolytes As the electrolyte and electrolyte constituting the lithium ion secondary battery according to one embodiment of the present invention, known organic electrolytes, inorganic solid electrolytes, and polymer solid electrolytes can be used. From the viewpoint of electrical conductivity, organic electrolytes are used. Is preferred.
- Organic electrolytes include dioxolane, diethyl ether, dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene glycol phenyl ether Ethers such as diethoxyethane; formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide N, N-diethylacetamide, N, N-dimethylpropion Amides such as amide and hexamethylphosphorylamide; sulfur-containing compounds such as dimethyl sulfoxide and sulfolane; dialkyl ketones such as methyl eth
- esters such as ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, vinylene carbonate, ⁇ -butyrolactone, ethers such as dioxolane, diethyl ether, diethoxyethane, dimethyl sulfoxide, acetonitrile, tetrahydrofuran, etc.
- carbonate-based non-aqueous solvents such as ethylene carbonate and propylene carbonate. These solvents can be used alone or in admixture of two or more.
- Lithium salts are used as solutes (electrolytes) for these solvents.
- Commonly known lithium salts include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCl, LiCF 3 SO 3 , LiCF 3 CO 2 , LiN (CF 3 SO 2 ) 2 and the like. is there.
- polymer solid electrolyte examples include a polyethylene oxide derivative and a polymer containing the derivative, a polypropylene oxide derivative and a polymer containing the derivative, a phosphate ester polymer, a polycarbonate derivative and a polymer containing the derivative. There are no restrictions on the selection of members other than those described above necessary for the battery configuration.
- the present invention will be described in more detail below with typical examples. Note that these are merely illustrative examples, and the present invention is not limited to these.
- crystallization were measured by the above-mentioned method.
- other physical property measuring methods are as follows.
- Electrode preparation Pure water was added to the above-mentioned main agent stock solution, and after adjusting the viscosity, it was applied onto a high-purity copper foil and dried in vacuo at 120 ° C. for 1 hour to obtain an electrode material. The amount of application was such that the amount of graphite powder was 5 mg / cm 2 . The obtained electrode material was punched out into a circle and compressed with a press pressure at a pressure of about 3 t / cm 2 for 10 seconds to obtain an electrode.
- a coin battery comprising a polyethylene separator, an electrolyte solution, and a case was prepared using the obtained electrode as a working electrode and lithium metal as a counter electrode.
- the electrolytic solution a mixture of 8 parts by mass of EC (ethylene carbonate) and 12 parts by mass of DEC (diethyl carbonate) in which LiPF 6 was dissolved as an electrolyte to a concentration of 1 mol / L was used.
- Evaluation method of orientation H 004 / H 110 was calculated as an index of the orientation of the active material in the electrode.
- an electrode material was obtained by the same method as the evaluation method using a coin battery. The obtained electrode material was punched into a circle, compressed at a pressure of about 3 t / cm 2 for 10 seconds, and allowed to stand at room temperature and normal pressure for 3 days. After standing, the density of the graphite powder in each electrode is measured, and the diffraction lines derived from the (004) plane and the (110) plane obtained by the X-ray diffraction method for the electrode having a density of 1.3 to 1.5 g / cm 3. The peak intensity ratio H 004 / H 110 was calculated using the X-ray diffraction method described above.
- Example 1 Coal-based calcined needle coke was pulverized with a bantam mill manufactured by Hosokawa Micron Corporation, and then coarse powder was removed using a sieve having an opening of 32 ⁇ m. Next, airflow classification was performed with a turbo classifier (registered trademark) TC-15N manufactured by Nissin Engineering Co., Ltd., and powder coke 1 substantially free of particles having a particle size of 1.0 ⁇ m or less was obtained.
- “substantially free” means that particles having a particle size of 1.0 ⁇ m or less measured using a Malvern Mastersizer (registered trademark) is 0.1% by mass or less.
- Powder coke 1 and powder of calcium hydroxide are mixed at a mass ratio of 80:20, and the mixture is heated at a graphitization temperature of 3300 ° C. for 1 hour in an argon atmosphere to graphitize. Went. Coarse powder was removed from the obtained graphite powder using a sieve having an opening of 45 ⁇ m.
- the median diameter D 50 in the volume-based cumulative particle size distribution of the obtained graphite powder, the results of ICP elemental analysis, and the average plane spacing d 002 from the X-ray diffraction, the thickness Lc in the c-axis direction, and H 004 which is an index of orientation / H110 was calculated and the results are shown in Table 1.
- the obtained graphite powder was used as an electrode, and the discharge capacity of a coin battery produced with the electrode compression pressure of 3 t / cm 2 was measured.
- Example 2 Anthracite was pulverized with a bantam mill manufactured by Hosokawa Micron Corporation, and then coarse powder was removed using a sieve having an opening of 32 ⁇ m. Next, air classification was performed with a turbo classifier TC-15N manufactured by Nissin Engineering Co., Ltd. to obtain powdered anthracite 1 substantially free of particles having a particle size of 1.0 ⁇ m or less. The obtained powder anthracite 1 was fired at a temperature of 1300 ° C. to obtain fired powder anthracite 1.
- the calcined powder anthracite 1 and calcium hydroxide are mixed at a mass ratio of 80:20, and the mixture is graphitized by heating at a graphitization temperature of 3300 ° C. for 1 hour in an argon atmosphere. Processed. Coarse powder was removed from the obtained graphite powder using a sieve having an opening of 45 ⁇ m. Table 1 shows the calculated results of median diameter D 50 , ICP elemental analysis, d 002 , Lc, and H 004 / H 110 . Further, the discharge capacity of a coin battery using the obtained graphite powder as an electrode was measured and shown in Table 1.
- Example 3 Graphite powder was obtained in the same manner as in Example 2, except that the calcined powder anthracite 1 obtained in Example 2 and calcium hydroxide powder were mixed at a mass ratio of 90:10. Table 1 shows the calculated results of median diameter D 50 , ICP elemental analysis, d 002 , Lc, and H 004 / H 110 . Further, the discharge capacity of a coin battery using the obtained graphite powder as an electrode was measured and shown in Table 1.
- Comparative Example 1 Graphite powder was obtained in the same manner as in Example 1 except that only the powder coke 1 obtained in Example 1 was graphitized without adding calcium hydroxide. Table 1 shows the calculated results of median diameter D 50 , ICP elemental analysis, d 002 , Lc, and H 004 / H 110 . Further, the discharge capacity of a coin battery using the obtained graphite powder as an electrode was measured and shown in Table 1.
- Comparative Example 2 Graphite powder was obtained in the same manner as in Example 2 except that only the calcined powder anthracite 1 obtained in Example 2 was graphitized without adding calcium hydroxide. Table 1 shows the calculated results of median diameter D 50 , ICP elemental analysis, d 002 , Lc, and H 004 / H 110 . Further, the discharge capacity of a coin battery using the obtained graphite powder as an electrode was measured and shown in Table 1.
- Comparative Example 3 Graphite powder was obtained in the same manner as in Example 3 except that the graphitization temperature was 2700 ° C. Table 1 shows the calculated results of median diameter D 50 , ICP elemental analysis, d 002 , Lc, and H 004 / H 110 . Further, the discharge capacity of a coin battery using the obtained graphite powder as an electrode was measured and shown in Table 1.
- Graphite powders for negative electrode materials (Examples 1 to 3) prepared using a mixture of a carbon material and calcium hydroxide during graphitization were graphitized only for the carbon material without adding calcium hydroxide.
- the thickness Lc in the c-axis direction of the crystal is suppressed.
- the value of H 004 / H 110 that serves as an index of orientation also decreases, suggesting that the orientation of the active material in the electrode is low. This is an effect of water vapor activation and alkali activation due to the addition of calcium hydroxide during the graphitization treatment.
- the use of the graphite powder according to the present invention for the negative electrode material can suppress the expansion of the electrode accompanying charge / discharge and improve the cycle characteristics.
- anthracite is used as a carbon material and graphitized so as to have the same maximum temperature (Examples 2 to 3 and Comparative Example 2)
- the graphite of the present invention to which calcium hydroxide is added during graphitization is used.
- the improvement of the initial charge / discharge capacity in the battery using powder can be confirmed.
- the effect of mixing calcium hydroxide during the graphitization treatment is not confirmed.
- the lithium ion secondary battery using the graphite powder for negative electrode material of the present invention is small and light and has a high discharge capacity and high cycle characteristics. Therefore, it requires a discharge capacity such as a mobile phone, an electric tool, or a hybrid car. It can be suitably used in a wide range.
Abstract
Description
さらに、電動ドリル等の電動工具や、ハイブリッド自動車用等、高出力で大容量の二次電池への要求が高まってきている。この分野は従来、鉛二次電池、ニッケルカドミウム二次電池、ニッケル水素二次電池が主に使用されているが、小型軽量で高エネルギー密度のリチウムイオン二次電池への期待は高く、大電流負荷特性に優れたリチウムイオン二次電池が求められている。
特許文献5にはサイクル特性に優れた人造黒鉛が開示されているが、体積当たりのエネルギー密度に向上の余地がある。
特許文献6には生の針状コークスから製造された人造黒鉛負極が開示されている。従来の人造黒鉛に対して、初回充放電効率の改善は見られるものの、放電容量が天然黒鉛材料に比して劣る。
特許文献7には石油ピッチを液相でコーティングしたコークスから製造された人造黒鉛負極が開示されている。この負極では、電極の容量密度に課題が残っている。また、大量の有機溶剤を使用し、使用後に該有機溶剤を揮発させるという操作を伴い、製造方法が煩雑となる。
特許文献8にはコールタールピッチと酸化チタン等の黒鉛化触媒を混合させたのち、低温でコークス化、中温度で炭化し、さらに高温度で黒鉛化する工程を経て黒鉛粉を得るという方法を開示している。得られた黒鉛粉は放電容量、初期充放電効率が向上しているが、製造工程が多く、また黒鉛粉中の残存金属の含有量が高く長期間の使用可能性が不明である。
一方で石油、石炭ピッチ、コークス等の易黒鉛化性原料を黒鉛化することで、サイクル特性に優れた人造黒鉛が製造できることがわかっている。中でも結晶性の高い針状コークスは高い放電容量を示すが、鱗片状になり電極内で配向しやすい。そのため、高い放電容量、長期にわたるサイクル特性、電極内での低配向性を同時に達成するのは困難である。
[1]黒鉛前駆体を粉砕する工程、及び粉砕後の黒鉛前駆体とアルカリ化合物との混合物を2800~3500℃で加熱して黒鉛化処理をする工程を含む、リチウムイオン二次電池負極材用黒鉛粉の製造方法。
[2]前記アルカリ化合物がアルカリ金属またはアルカリ土類金属の水酸化物である前項1に記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
[3]前記アルカリ土類金属の水酸化物が水酸化カルシウムである前項2に記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
[4]前記混合物における黒鉛前駆体とアルカリ化合物の質量比が70:30~97:3である前項1~3のいずれかに記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
[5]前記黒鉛前駆体がコークスまたは石炭を含む前項1~4のいずれかに記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
[6]前項1~5のいずれかに記載の製造方法により得られる黒鉛粉。
[7]金属元素を実質的に含まない前項6に記載の黒鉛粉。
[8]前項6または7に記載の黒鉛粉を活物質として用いたリチウムイオン二次電池用負極。
[9]前項8に記載の負極を備えるリチウムイオン二次電池。
[10]前項1~5のいずれかに記載の方法によりリチウムイオン二次電池負極材用黒鉛粉を得る工程、及び得られた前記黒鉛粉を活物質として用いリチウムイオン二次電池用負極を得る工程を有する、リチウムイオン二次電池用負極の製造方法。
[11]前項1~5のいずれかに記載の方法によりリチウムイオン二次電池負極材用黒鉛粉を得る工程、得られた前記黒鉛粉を活物質として用いリチウムイオン二次電池用負極を得る工程、及び得られた前記負極をリチウムイオン二次電池の負極とする工程を有する、リチウムイオン二次電池の製造方法。
リチウムイオン二次電池負極材用黒鉛粉の製造方法は、以下のような方法が好適である。黒鉛粉の原料に用いる黒鉛前駆体は、焼成によって黒鉛化が可能な炭素材料であれば特に限定されないが、取り扱いが容易である点でコークスまたは石炭が好ましい。また黒鉛前駆体は単独で用いても、2種以上を組み合わせて用いてもよい。
コーキング処理により黒鉛前駆体としてのコークスを得た場合には、得られた黒鉛前駆体をドラム内からジェット水流により切り出し、得られた塊を粗粉砕する。
粗粉砕は、金槌、二軸ロールクラッシャー、ジョークラッシャー等を用いることができ、粉砕後の塊を網の一辺の長さが1mmの篩(ふるい)にかけ、篩に残った部分が全体の90質量%以上となるように粉砕するのが好ましい。粒径1mm以下の微粉が大量に発生する程度にまで過粉砕を行うと、以降の加熱の工程等において、乾燥後微粉が舞い上がる、または焼損が増える等の不都合が生じるおそれがある。
また使用するアルカリ化合物が水酸化物である場合、昇温過程で分解され、水を生じる。例えば水酸化カルシウムは580℃で熱分解し、水と酸化カルシウムを生じる。水蒸気とともに黒鉛化処理を行う手法(水蒸気賦活)を用いると、水蒸気によって炭素が酸化され、炭素材料の結晶子間に細孔が形成される。
さらに、炭化物の賦活にアルカリ化合物を利用するアルカリ賦活では、アルカリの蒸気が黒鉛の層間に侵入し、層間を押し広げて層間に細孔を形成する。このアルカリ賦活の効果は炭素材料の結晶子間に細孔があると高まる。層間に細孔が形成されることにより、結晶子のc軸方向の厚みLcが低下する。
本発明の一実施態様に係るリチウムイオン二次電池負極材用黒鉛粉は、粉末X線回折法(XRD)による(002)面の平均面間隔d002が、0.33565~0.33580nmであり、かつ結晶子のc軸方向の厚みLcが90nm以下であるか、またはd002が0.33540~0.33564nmであり、かつLcが130nm以下である。また、本発明の一実施態様に係る黒鉛粉を負極の活物質として用いた電極の密度を1.3~1.5g/cm3としたときの(004)面由来の回折線のピーク強度H004と、(110)面由来の回折線のピーク強度H110の強度比H004/H110が60以下であることが好ましい。H004/H110は配向性の指標であり、値が小さいほど電極内の活物質の配向性が低いことを示す。より好ましいH004/H110は10以下である。
d002、Lc、及びH004/H110は、既知の方法により粉末X線回折法を用いて測定することができる(野田稲吉、稲垣道夫、日本学術振興会、第117委員会資料、117-71-A-1(1963)、稲垣道夫他、日本学術振興会、第117委員会試料、117-121-C-5(1972)、稲垣道夫、「炭素」、1963、No.36、25-34頁参照)。
本明細書においてR値とは、レーザーラマン分光法により得られたスペクトルにおける1300~1400cm-1の範囲にあるピーク強度IDと、1580~1620cm-1の範囲にあるピーク強度IGとの強度比ID/IGのことをいう。R値が大きいほど結晶性が低いことを示す。
R値は、例えば、日本分光株式会社製レーザーラマン分光測定装置(NRS-3100)を用いて、励起波長532nm、入射スリット幅200μm、露光時間15秒、積算回数2回、回折格子600本/mmの条件で測定を行い、その結果得られた1360cm-1付近のピーク強度と1580cm-1付近のピーク強度に基づいて算出することができる。
本発明の一実施態様に係る電極用黒鉛材料は、上記黒鉛粉を含んでなる。上記黒鉛粉を電極用黒鉛材料に用いると、高容量、高クーロン効率、高サイクル特性を維持したまま、高エネルギー密度の電池電極を得ることができる。電極用黒鉛材料としては、例えば、リチウムイオン二次電池の負極活物質及び負極導電性付与材として用いることができる。
本発明の一実施態様に係る電極用ペーストは、前記電極用黒鉛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、前記電極用黒鉛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。
バインダーの使用量は、電極用黒鉛材料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。
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;ゴム系のポリマーの場合は水等;その他のバインダーの場合にはジメチルホルムアミド、2-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する。
本発明の一実施態様に係る電極は前記電極用ペーストの成形体からなる。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。
集電体としては、例えばアルミニウム、ニッケル、銅、ステンレス等の金属箔、またはメッシュ等が挙げられる。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等が挙げられる。
前記電極は電池または二次電池の電極として使用することができる。
リチウムイオン二次電池を具体例に挙げて、本発明の一実施態様に係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もつものであり、負極には本発明の一実施態様に係る電極が用いられる。
リチウムイオン二次電池の正極には、正極活物質として、通常、リチウム含有遷移金属酸化物が用いられ、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の化合物が用いられる。また、より好ましくはV、Cr、Mn、Fe、Co及びNi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る。
なお、主として存在する遷移金属に対し30モル%未満の範囲でAl、Ga、In、Ge、Sn、Pb、Sb、Bi、Si、P、B等を含有していてもよい。上記の正極活物質の中で、一般式LixMO2(MはCo、Ni、Fe、Mnの少なくとも1種、x=0.02~1.2)、またはLiyN2O4(Nは少なくともMnを含む、y=0.02~2)で表わされるスピネル構造を有する材料の少なくとも1種を用いることが好ましい。
正極活物質の比表面積は特に限定されないが、BET法で測定した比表面積が0.01~50m2/gであることが好ましく、さらに0.2~1m2/gであることが好ましい。また正極活物質5gを蒸留水100mlに溶解したときの上澄み液のpHが7~12となることが好ましい。
なお、上記以外の電池構成上必要な部材の選択についてはなんら制約を受けるものではない。
なお、実施例及び比較例の黒鉛粉についての、X線回折法により求められる平均面間隔d002と結晶のc軸方向の厚みLcは前述の方法により測定した。また、その他の物性の測定方法は以下の通りである。
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)を用いて測定した。
株式会社日立ハイテクサイエンス製ICP発光分光分析装置(SPS3520UV)によって、構成する元素の種類とその濃度を測定した。
a)ペースト作製:
黒鉛粉97質量部にSBR(スチレンブタジエンゴム)とCMC(カルボキシメチルセルロース;ダイセルファインケム株式会社製)それぞれの2質量%水溶液を各1.5質量部加え、プラネタリーミキサーにて混練し、主剤原液とした。
上記主剤原液に純水を加え、粘度を調整後、高純度銅箔上に塗布して120℃で1時間真空乾燥し、電極材料を得た。塗布の量は、黒鉛粉の量が5mg/cm2となる量とした。得られた電極材料を円形に打ち抜き、プレス加圧で約3t/cm2の圧力で10秒間圧縮し、電極を得た。
露点-80℃以下の乾燥アルゴンガス雰囲気下で、得られた電極を作用極、リチウム金属を対極として、さらにポリエチレンセパレータと電解液とケースから成るコイン電池を作製した。電解液には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を濃度が1mol/Lとなるように溶解したものを用いた。
作製したコイン電池で前記作用極の充放電試験を25℃に設定した恒温槽内で行った。
はじめに、開回路電圧が0.002Vとなるまで0.05Cの電流を流し、0.002Vで維持し、電流値が25.4μAに低下した時点で停止させることで作用極の充電容量を測定した。次に、開回路電圧が1.5Vとなるまで0.05Cで電流を流すことで放電容量を測定した。
電極内の活物質の配向性の指標としてH004/H110の算出を行った。まずコイン電池による評価方法と同様の方法で電極材料を得た。得られた電極材料を円形に打ち抜き、約3t/cm2の圧力で10秒間圧縮し、3日間常温・常圧下で静置した。静置後、各電極における黒鉛粉の密度を計測し、密度1.3~1.5g/cm3である電極についてX線回折法により求められる(004)面と(110)面由来の回折線のピーク強度比H004/H110を前述のX線回折法を用いて算出した。
石炭系か焼ニードルコークスをホソカワミクロン株式会社製バンタムミルで粉砕し、その後32μmの目開きの篩を用いて粗粉を除去した。次に、日清エンジニアリング株式会社製ターボクラシファイア(登録商標)TC-15Nで気流分級し、粒径が1.0μm以下の粒子を実質的に含まない粉末コークス1を得た。本発明において、実質的に含まないとはマルバーン製マスターサイザー(登録商標)を用いて測定した粒径が1.0μm以下の粒子が0.1質量%以下であることをいう。
粉末コークス1と水酸化カルシウム(関東化学株式会社製)の粉末とを質量比80:20の割合で混合し、混合物をアルゴン雰囲気下で黒鉛化処理温度3300℃で一時間加熱して黒鉛化処理を行った。得られた黒鉛粉を45μmの目開きの篩を用いて粗粉を除去した。
得られた黒鉛粉の体積基準累積粒径分布におけるメジアン径D50、ICP元素分析の結果、及びX線回折から平均面間隔d002、c軸方向の厚みLc、配向性の指標であるH004/H110を算出し、結果を表1に示した。また、得られた黒鉛粉を電極に用い、電極の圧縮圧力を3t/cm2として作製したコイン電池の放電容量を測定し、表1に併せて示した。
無煙炭をホソカワミクロン株式会社製バンタムミルで粉砕し、その後32μmの目開きの篩を用いて粗粉を除去した。次に、日清エンジニアリング株式会社製ターボクラシファイアTC-15Nで気流分級し、粒径が1.0μm以下の粒子を実質的に含まない粉末無煙炭1を得た。得られた粉末無煙炭1を1300℃の温度で焼成し、焼成粉末無煙炭1を得た。
焼成粉末無煙炭1と水酸化カルシウム(関東化学株式会社製)の粉末とを質量比80:20の割合で混合し、混合物をアルゴン雰囲気下で黒鉛化処理温度3300℃で一時間加熱して黒鉛化処理を行った。得られた黒鉛粉を45μmの目開きの篩を用いて粗粉を除去した。
メジアン径D50、ICP元素分析、d002、Lc及びH004/H110の算出結果を表1に示した。また、得られた黒鉛粉を電極に用いたコイン電池の放電容量を測定し、表1に併せて示した。
実施例2で得られた焼成粉末無煙炭1と水酸化カルシウムの粉末を質量比90:10の割合で混合した以外は、実施例2と同じ方法で黒鉛粉を得た。
メジアン径D50、ICP元素分析、d002、Lc及びH004/H110の算出結果を表1に示した。また、得られた黒鉛粉を電極に用いたコイン電池の放電容量を測定し、表1に併せて示した。
水酸化カルシウムを加えず実施例1で得られた粉末コークス1のみを黒鉛化処理をした以外は実施例1と同じ方法で黒鉛粉を得た。
メジアン径D50、ICP元素分析、d002、Lc及びH004/H110の算出結果を表1に示した。また、得られた黒鉛粉を電極に用いたコイン電池の放電容量を測定し、表1に併せて示した。
水酸化カルシウムを加えず実施例2で得られた焼成粉末無煙炭1のみを黒鉛化処理をした以外は実施例2と同じ方法で黒鉛粉を得た。
メジアン径D50、ICP元素分析、d002、Lc及びH004/H110の算出結果を表1に示した。また、得られた黒鉛粉を電極に用いたコイン電池の放電容量を測定し、表1に併せて示した。
黒鉛化処理温度を2700℃とした以外は実施例3と同じ方法で黒鉛粉を得た。
メジアン径D50、ICP元素分析、d002、Lc及びH004/H110の算出結果を表1に示した。また、得られた黒鉛粉を電極に用いたコイン電池の放電容量を測定し、表1に併せて示した。
また、無煙炭を炭素材料とし、同じ最高到達温度となるように黒鉛化処理した場合(実施例2~3及び比較例2)では、黒鉛化処理の際に水酸化カルシウムを加えた本発明の黒鉛粉を用いた電池における初回充放電容量の向上が確認できる。さらにICP発光分析の結果において、黒鉛粉に含まれるカルシウム元素量に違いが見られないことから、黒鉛化処理の際に水酸化カルシウムを混合したことによる影響は確認されない。これは黒鉛化処理時の3300℃という高温で処理したことにより、水酸化カルシウムが気化したためと考えられる。
一方、黒鉛化処理の際に炭素材料と水酸化カルシウムとの混合物を使用した場合でも、最高到達温度が2700℃と低い場合(比較例3)では、平均面間隔d002が大きくなってしまう。黒鉛化処理時の温度が低いために黒鉛化が進みにくいと考えられる。
以上から本発明の方法で作製した黒鉛粉を電極の活物質として用いると、電極内での黒鉛の配向性を低下させることで、本発明の黒鉛粉を用いたリチウムイオン二次電池は従来の黒鉛粉を用いた電池に対してより高いサイクル特性をもつと考えられる。
Claims (9)
- 黒鉛前駆体を粉砕する工程、及び粉砕後の黒鉛前駆体とアルカリ化合物との混合物を2800~3500℃で加熱して黒鉛化処理をする工程を含む、リチウムイオン二次電池負極材用黒鉛粉の製造方法。
- 前記アルカリ化合物がアルカリ金属またはアルカリ土類金属の水酸化物である請求項1に記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
- 前記アルカリ土類金属の水酸化物が水酸化カルシウムである請求項2に記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
- 前記混合物における黒鉛前駆体とアルカリ化合物の質量比が70:30~97:3である請求項1~3のいずれかに記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
- 前記黒鉛前駆体がコークスまたは石炭を含む請求項1~4のいずれかに記載のリチウムイオン二次電池負極材用黒鉛粉の製造方法。
- 請求項1~5のいずれかに記載の製造方法により得られる黒鉛粉。
- 金属元素を実質的に含まない請求項6に記載の黒鉛粉。
- 請求項6または7に記載の黒鉛粉を活物質として用いたリチウムイオン二次電池用負極。
- 請求項8に記載の負極を備えるリチウムイオン二次電池。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2016572029A JPWO2016121711A1 (ja) | 2015-01-27 | 2016-01-26 | リチウムイオン二次電池負極材用黒鉛粉の製造方法、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 |
US15/545,850 US20180019472A1 (en) | 2015-01-27 | 2016-01-26 | Method for manufacturing graphite powder for negative-electrode material for lithium-ion secondary battery, negative electrode for lithium-ion secondary battery, and lithium-ion secondary battery |
CN201680005384.3A CN107112537A (zh) | 2015-01-27 | 2016-01-26 | 锂离子二次电池负极材料用石墨粉的制造方法、锂离子二次电池用负极和锂离子二次电池 |
DE112016000490.7T DE112016000490T5 (de) | 2015-01-27 | 2016-01-26 | Verfahren zum Herstellen von Graphitpulver für ein Negativelektrodenmaterial für eine Lithiumionen-Sekundärbatterie, negative Elektrode für eine Lithiumionen-Sekundärbatterie und Lithiumionensekundärbatterie |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015-013313 | 2015-01-27 | ||
JP2015013313 | 2015-01-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016121711A1 true WO2016121711A1 (ja) | 2016-08-04 |
Family
ID=56543324
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2016/052063 WO2016121711A1 (ja) | 2015-01-27 | 2016-01-26 | リチウムイオン二次電池負極材用黒鉛粉の製造方法、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 |
Country Status (5)
Country | Link |
---|---|
US (1) | US20180019472A1 (ja) |
JP (1) | JPWO2016121711A1 (ja) |
CN (1) | CN107112537A (ja) |
DE (1) | DE112016000490T5 (ja) |
WO (1) | WO2016121711A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20190081325A1 (en) * | 2017-09-14 | 2019-03-14 | Toyota Jidosha Kabushiki Kaisha | Graphite material for negative electrode of lithium ion secondary cell and method for producing the same |
KR102268996B1 (ko) * | 2020-10-26 | 2021-06-24 | 블랙머티리얼즈 주식회사 | 무연탄으로부터 고순도 흑연 분말의 제조방법 |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108178140A (zh) * | 2017-12-28 | 2018-06-19 | 石家庄尚太科技有限公司 | 锂离子电池、负极材料及负极材料加工方法 |
CN108808068B (zh) * | 2018-05-10 | 2019-09-27 | 宁德时代新能源科技股份有限公司 | 二次电池 |
CN112424118A (zh) * | 2019-06-13 | 2021-02-26 | 杰富意化学株式会社 | 整体中间相石墨化物的制造方法 |
JP7226559B2 (ja) * | 2019-07-31 | 2023-02-21 | 株式会社レゾナック | リチウムイオン二次電池用負極材の製造方法及びリチウムイオン二次電池の製造方法 |
DE102020100907A1 (de) | 2020-01-16 | 2021-07-22 | Netzsch Trockenmahltechnik Gmbh | Vorrichtung und verfahren zum verrunden von graphitflocken eines graphitmaterials |
CN116375015B (zh) * | 2023-03-16 | 2024-02-20 | 湖北斯诺新材料科技有限公司 | 一种人造石墨材料的制备方法及其应用 |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001278609A (ja) * | 2000-03-30 | 2001-10-10 | Sumitomo Durez Co Ltd | 酸素含有炭素材の製造方法 |
JP2002008661A (ja) * | 2000-05-17 | 2002-01-11 | Samsung Sdi Co Ltd | リチウム二次電池用負極活物質 |
JP2007200871A (ja) * | 2005-12-28 | 2007-08-09 | Mitsubishi Chemicals Corp | リチウムイオン二次電池 |
JP2009263160A (ja) * | 2008-04-24 | 2009-11-12 | Jfe Chemical Corp | 黒鉛質材料の製造方法、リチウムイオン二次電池用負極材料およびリチウムイオン二次電池 |
WO2014003135A1 (ja) * | 2012-06-29 | 2014-01-03 | 昭和電工株式会社 | 炭素材料、電池電極用炭素材料、及び電池 |
WO2014050097A1 (ja) * | 2012-09-27 | 2014-04-03 | 昭和電工株式会社 | リチウムイオン二次電池負極用炭素材およびその製造方法並びに用途 |
JP2014060168A (ja) * | 2013-11-12 | 2014-04-03 | Mitsubishi Chemicals Corp | 黒鉛負極材料及びその製造方法、並びにそれを用いたリチウム二次電池用負極及びリチウム二次電池 |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100366346B1 (ko) * | 2000-06-16 | 2002-12-31 | 삼성에스디아이 주식회사 | 리튬 이차 전지용 음극 활물질 및 그의 제조 방법 |
WO2006022100A1 (ja) * | 2004-08-27 | 2006-03-02 | Jfe Chemical Corporation | 黒鉛質材料とその製造方法、リチウムイオン二次電池用負極材料、リチウムイオン二次電池用負極およびリチウムイオン二次電池 |
-
2016
- 2016-01-26 CN CN201680005384.3A patent/CN107112537A/zh active Pending
- 2016-01-26 US US15/545,850 patent/US20180019472A1/en not_active Abandoned
- 2016-01-26 JP JP2016572029A patent/JPWO2016121711A1/ja active Pending
- 2016-01-26 DE DE112016000490.7T patent/DE112016000490T5/de not_active Withdrawn
- 2016-01-26 WO PCT/JP2016/052063 patent/WO2016121711A1/ja active Application Filing
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001278609A (ja) * | 2000-03-30 | 2001-10-10 | Sumitomo Durez Co Ltd | 酸素含有炭素材の製造方法 |
JP2002008661A (ja) * | 2000-05-17 | 2002-01-11 | Samsung Sdi Co Ltd | リチウム二次電池用負極活物質 |
JP2007200871A (ja) * | 2005-12-28 | 2007-08-09 | Mitsubishi Chemicals Corp | リチウムイオン二次電池 |
JP2009263160A (ja) * | 2008-04-24 | 2009-11-12 | Jfe Chemical Corp | 黒鉛質材料の製造方法、リチウムイオン二次電池用負極材料およびリチウムイオン二次電池 |
WO2014003135A1 (ja) * | 2012-06-29 | 2014-01-03 | 昭和電工株式会社 | 炭素材料、電池電極用炭素材料、及び電池 |
WO2014050097A1 (ja) * | 2012-09-27 | 2014-04-03 | 昭和電工株式会社 | リチウムイオン二次電池負極用炭素材およびその製造方法並びに用途 |
JP2014060168A (ja) * | 2013-11-12 | 2014-04-03 | Mitsubishi Chemicals Corp | 黒鉛負極材料及びその製造方法、並びにそれを用いたリチウム二次電池用負極及びリチウム二次電池 |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20190081325A1 (en) * | 2017-09-14 | 2019-03-14 | Toyota Jidosha Kabushiki Kaisha | Graphite material for negative electrode of lithium ion secondary cell and method for producing the same |
KR20190030623A (ko) * | 2017-09-14 | 2019-03-22 | 도요타 지도샤(주) | 리튬 이온 이차 전지의 부극용 흑연재 및 그 제조 방법 |
KR102183159B1 (ko) * | 2017-09-14 | 2020-11-25 | 도요타 지도샤(주) | 리튬 이온 이차 전지의 부극용 흑연재 및 그 제조 방법 |
US10950860B2 (en) * | 2017-09-14 | 2021-03-16 | Toyota Jidosha Kabushiki Kaisha | Graphite material for negative electrode of lithium ion secondary cell and method for producing the same |
KR102268996B1 (ko) * | 2020-10-26 | 2021-06-24 | 블랙머티리얼즈 주식회사 | 무연탄으로부터 고순도 흑연 분말의 제조방법 |
Also Published As
Publication number | Publication date |
---|---|
JPWO2016121711A1 (ja) | 2017-11-02 |
US20180019472A1 (en) | 2018-01-18 |
CN107112537A (zh) | 2017-08-29 |
DE112016000490T5 (de) | 2017-11-02 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5033325B2 (ja) | 黒鉛材料、電池電極用炭素材料、及び電池 | |
US10892482B2 (en) | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery | |
KR102102099B1 (ko) | 비수계 이차 전지용 탄소재, 그 탄소재를 사용한 부극 및 비수계 이차 전지 | |
WO2016121711A1 (ja) | リチウムイオン二次電池負極材用黒鉛粉の製造方法、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 | |
WO2013058349A1 (ja) | 黒鉛材料、電池電極用炭素材料、及び電池 | |
JP6535467B2 (ja) | リチウムイオン二次電池負極活物質用黒鉛粉 | |
JP5228141B1 (ja) | 黒鉛材料、その製造方法、電池電極用炭素材料、及び電池 | |
JP5162092B2 (ja) | 黒鉛材料、電池電極用炭素材料、及び電池 | |
KR20080073706A (ko) | 흑연 재료, 전지 전극용 탄소 재료 및 전지 | |
TW201336783A (zh) | 鋰離子電池用電極材料之製造方法 | |
US10508038B2 (en) | Carbon material, method for manufacturing same, and use thereof | |
US10388984B2 (en) | Method for producing graphite powder for negative electrode materials for lithium ion secondary batteries | |
JP5333963B2 (ja) | リチウムイオン二次電池用負極活物質及びそれを使用した負極 | |
JP5728475B2 (ja) | リチウムイオン二次電池負極材料用原料炭組成物 | |
JP2018006270A (ja) | リチウムイオン二次電池負極用黒鉛質炭素材料、その製造方法、それを用いた負極又は電池 | |
JP5162093B2 (ja) | 黒鉛材料、電池電極用炭素材料、及び電池 | |
JP2011060467A (ja) | リチウムイオン二次電池用負極材料およびその製造方法 | |
JP2007294374A (ja) | 非水電解液二次電池用負極材、該負極材を用いた非水電解液二次電池用負極および非水電解液二次電池 | |
WO2017010476A1 (ja) | 二次電池用黒鉛含有炭素粉の製造方法及び電池電極用炭素材料 | |
JP2011029197A (ja) | リチウム二次電池用負極炭素材料、その製造法、リチウム二次電池用負極及びリチウム二次電池 | |
JP4721038B2 (ja) | リチウム二次電池用負極炭素材料、その製造法、リチウム二次電池用負極及びリチウム二次電池 | |
JP2005019096A (ja) | 非水系2次電池 | |
EP4358190A1 (en) | Method for producing artificial graphite material for lithium ion secondary battery negative electrodes, artificial graphite material for lithium ion secondary battery negative electrodes, negative electrode for lithium ion secondary batteries, and lithium ion secondary battery | |
JP7009049B2 (ja) | リチウムイオン二次電池負極用炭素材料、その中間体、その製造方法、及びそれを用いた負極又は電池 | |
WO2019131547A1 (ja) | リチウムイオン二次電池 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 16743314 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2016572029 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 15545850 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 112016000490 Country of ref document: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 16743314 Country of ref document: EP Kind code of ref document: A1 |