WO2012026544A1 - 微細な炭素繊維と複合化されたリチウムチタン複合酸化物電極材料 - Google Patents
微細な炭素繊維と複合化されたリチウムチタン複合酸化物電極材料 Download PDFInfo
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- WO2012026544A1 WO2012026544A1 PCT/JP2011/069216 JP2011069216W WO2012026544A1 WO 2012026544 A1 WO2012026544 A1 WO 2012026544A1 JP 2011069216 W JP2011069216 W JP 2011069216W WO 2012026544 A1 WO2012026544 A1 WO 2012026544A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a lithium secondary battery using lithium occlusion and release, which improves cycle characteristics by improving the electron conductivity and lithium ion mobility of a lithium titanium composite oxide electrode active material used for a positive electrode or a negative electrode.
- the present invention relates to an electrode material that reduces deterioration and improves discharge characteristics under high load.
- lithium-ion secondary batteries such as Ni-MH alkaline storage batteries and lithium secondary batteries have been put into practical use and widely used with the downsizing, high performance, and portability of electronic devices.
- light-weight and high-energy density lithium-ion secondary batteries are used not only in conventional small-sized information communication devices such as mobile phones and notebook computers, but also in automobiles that require high output characteristics and long-term reliability. It is also being studied as a power source for rotating bodies such as moving bodies and electric tools, and for backup.
- lithium such as lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), and spinel structure lithium manganate (LiMn 2 O 4 ) capable of forming an operating voltage of 4V. Transition metal composite oxides are used.
- carbon materials are widely used as negative electrode active materials.
- conventional electrode materials to industrial applications such as backups and automotive batteries, which are expected to be in great demand in the future, requires resource depletion and high price resolution, improved battery performance, and safety. ing.
- lithium-titanium composite oxides have attracted attention as electrode active materials for lithium secondary batteries used in these applications.
- the lithium-titanium composite oxide has a charge / discharge potential that is nobler than that of the carbon material (the spinel type Li 4 Ti 5 O 12 is about 1.56 V with respect to Li / Li +), and the positive electrode active material of the wristwatch drive battery It has been applied as.
- Li 4 Ti 5 O 12 having a spinel structure has a large amount of lithium ions that can be electrochemically inserted and desorbed, and a volume change accompanying insertion and desorption is small, so that the crystal structure can be maintained. Excellent and little deterioration due to charge / discharge cycle.
- the lithium ion insertion / extraction potential is noble, so lithium metal deposition at low temperatures and reductive decomposition of the solvent by the negative electrode active material are suppressed, ensuring safety and battery life. Is known to be long.
- lithium-titanium composite oxides have extremely low electronic conductivity, large reaction resistance for insertion / extraction of lithium ions, and battery characteristics deteriorate significantly when charging / discharging at high loads, and high output characteristics are required. Application to the battery system is difficult.
- the refinement of lithium-titanium composite oxide particles can increase the area in which the reaction proceeds and the distance of movement of lithium ions and electrons within the particle can be shortened. Problems arise in the adhesion between the secondary agglomeration (dispersibility) and the current collector, and conversely, the battery characteristics such as capacity and output will be reduced, and the charge / discharge characteristics under high load will not be improved sufficiently (non- Patent Document 1).
- a method for imparting electrical conductivity to the lithium-titanium composite oxide a method of doping different metals into the crystal lattice of the lithium-titanium composite oxide, for example, more expensive than Ti (IV) for lithium titanate. It is characterized by doping with elements (V, Nb, Mo, P) (Patent Document 1) and doping with transition metals (V, Zr, Nb, Mo, Mn, Fe, Cu, Co) (Patent Document 2).
- An active material for a battery is disclosed.
- Patent Document 3 a battery active material characterized by coating the surface of lithium titanate particles with a specific ratio is disclosed.
- the electrode reaction In the electrode reaction, during the process of charging or discharging, the release and insertion of lithium ions and the accompanying movement of electrons cause oxidation and reduction of the electrode.
- the ease of movement determines the electrode reaction speed, that is, the output characteristics.
- the disclosed method for imparting electric conductivity to a lithium titanium composite oxide having low electric conductivity sufficient electric conductivity cannot be obtained because a highly conductive substance does not exist inside the particle, and a load due to electron transfer is not obtained. Resistance is not reduced sufficiently.
- the method of coating the particle surface with carbon by pyrolysis of an organic compound is low in carbon crystallinity and inferior in electrical conductivity, and the coated part does not directly contact the electrolyte surface with the active material surface.
- the diffusion movement of lithium ions is hindered, leaving problems in output characteristics and active material utilization.
- the present invention provides an electrode material for a secondary battery, in which a substance having excellent electrical conductivity is formed inside a particle of the lithium titanium composite oxide and on the particle surface to form a conductive circuit in a network form.
- the purpose is to facilitate the movement of lithium ions, reduce load characteristics, and improve output characteristics and battery life.
- the fine carbon fibers adhering to the particle surface in a network form do not cover the entire particle surface, so that the battery electrolyte and the particle surface are in direct contact, and the movement of electrons and lithium ions is facilitated. That is, the present invention relates to the following matters.
- An electrode material for a secondary battery characterized in that the inside and the surface of a lithium titanium composite oxide are complexed in a network with fine carbon fibers.
- the lithium titanium composite oxide has a spinel structure Li 4 Ti 5 O 12 as a main component, an average particle diameter of 50 nm or more and less than 1000 nm, and a specific surface area of 1 m 2 / g or more and 30 m 2 / g or less.
- the electrode material for a secondary battery as described in 1 above.
- the fine carbon fiber is manufactured by a vapor phase growth method, and a graphite net surface thereof forms a structural unit having a closed top portion and an open bottom portion, and the structural unit has a central axis. Any one of 1 to 4 above, wherein 2 to 30 layers are shared and stacked to form an aggregate, and the aggregate is connected with a space in a head-to-tail manner to form a fiber.
- An electrode material for a secondary battery as described above.
- the outer diameter D of the end of the aggregate body is 5 to 40 nm
- the inner diameter d is 3 to 30 nm
- the aspect ratio (L / D) of the aggregate is 2 to 150. 7.
- the electrode material as described in any one of 1 to 6 above.
- the fine carbon fiber is produced by a vapor phase growth method using a catalyst containing an element selected from the group consisting of Fe, Co, Ni, Al, Mg and Si, and the ash content in the fine carbon fiber is 4% by weight.
- the electrode material as described in any one of 1 to 7 above, wherein the electrode material is 1% or less.
- the fine carbon fiber is produced by supplying and reacting a mixed gas containing CO and H 2 on a catalyst containing a cobalt spinel oxide in which magnesium is substituted and dissolved, and growing the fine carbon fiber.
- a mixed gas containing CO and H 2 on a catalyst containing a cobalt spinel oxide in which magnesium is substituted and dissolved, and growing the fine carbon fiber.
- Step a-1 a step of kneading the fine carbon fiber aggregate and the titanium compound by applying a shearing force to obtain a mixture of the opened fine carbon fiber and the titanium compound;
- Step a-2) a step of mixing the mixture obtained in step a-1 and a lithium compound;
- Step a-3 A method for producing an electrode material for a secondary battery, comprising a step of firing the mixture obtained in Step a-2 in an inert atmosphere.
- Step b-1 a step of kneading the fine carbon fiber aggregate, the titanium compound and the lithium compound by applying a shearing force to obtain a mixture of the opened fine carbon fiber, the titanium compound and the lithium compound;
- Step b-2 A method for producing an electrode material for a secondary battery, comprising a step of firing the mixture obtained in Step b-1 in an inert atmosphere.
- Step c-1) a step of opening and dispersing fine carbon fiber aggregates in a dispersion medium using a dispersant;
- Step c-2) A step of mixing the finely dispersed carbon fiber dispersion obtained in Step c-1, a titanium compound, and a lithium compound;
- Step c-3) In Step c-2 And a step of firing the obtained mixture in an inert atmosphere.
- Step d-1 A step of opening, dispersing, and mixing fine carbon fiber aggregates using a dispersant in a mixture of a dispersion medium, a titanium compound, and a lithium compound;
- Step d-2) A method for producing an electrode material for a secondary battery, comprising a step of firing the mixture obtained in Step d-1 in an inert atmosphere.
- the titanium compound is titanium dioxide particles and / or titanium hydroxide particles having a size of 20 nm or more and less than 500 nm, and the lithium compound is lithium carbonate and / or lithium hydroxide.
- the production method according to any one of 11 to 14.
- the fine carbon fiber aggregate is produced by a vapor phase growth method, and the fine carbon fiber graphite network surface constituting the aggregate has a closed top part and a lower part of the structural unit.
- the structural units are stacked in the form of 2 to 30 layers sharing the central axis to form an aggregate, and the aggregate is connected at intervals in a head-to-tail manner to form fibers. 18.
- the production method according to any one of 11 to 17 above, wherein
- a lithium secondary battery in a lithium secondary battery, it is possible to improve the electronic conductivity and lithium ion mobility of a lithium titanium composite oxide electrode material used for a positive electrode or a negative electrode, reduce deterioration of cycle characteristics, and increase the load. It is possible to provide a lithium secondary battery having excellent discharge characteristics.
- FIG. 1 It is a figure which shows typically the minimum structural unit (bell-shaped structural unit) which comprises fine carbon fiber.
- B A diagram schematically showing an assembly in which 2 to 30 bell-shaped structural units are stacked.
- A It is a figure which shows typically a mode that an aggregate
- B It is a figure which shows typically a mode that it bent and connected, when an aggregate
- 2 is a SEM photographic image of a lithium titanium composite oxide combined with fine carbon fibers A manufactured in Example 1.
- the present invention is characterized in that the surface and the inside of the lithium titanium composite oxide are complexed in a network with fine carbon fibers.
- fine carbon fibers which are highly conductive materials are present on the surface and inside of the lithium titanium composite oxide, and high electrical conductivity can be obtained.
- the surface of the lithium titanium composite oxide can be in direct contact with the electrolyte, lithium ions can be easily diffused and transferred, and the electrode material has high output characteristics.
- the average particle size of the lithium titanium composite oxide composited with the fine carbon fiber of the present invention is preferably 50 nm or more and less than 1000 nm, and more preferably 50 nm or more and 800 nm or less.
- the specific surface area is preferably 1 m 2 / g or more and 30 m 2 / g or less, more preferably 2.5 m 2 / g or more and 30 m 2 / g or less.
- the amount of fine carbon fibers to be combined is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 7% by mass or less, and 0.75% by mass with respect to the total mass. % To 5% by mass is more preferable. Even if the content of the fine carbon fiber is small, there is no problem. However, if it is contained in an amount of 0.1% by mass or more, the effect of improving the conductivity is easily exhibited, which is preferable. On the other hand, if the content of fine carbon fibers is too large, the electric capacity of the electrode material is significantly reduced, which affects battery performance.
- the lithium titanium composite oxide composited with the fine carbon fiber of the present invention preferably has a volume resistivity of less than 10 5 ⁇ ⁇ cm in a compressed state of 10 MPa / cm 2 , for example.
- Step a-1 a step of kneading the fine carbon fiber aggregate and the titanium compound by applying a shearing force to obtain a mixture of the opened fine carbon fiber and the titanium compound;
- Step a-2) a step of mixing the mixture obtained in step a-1 and a lithium compound;
- Step a-3) including a step of baking the mixture obtained in Step a-2 in an inert atmosphere.
- Step b-1 a step of kneading the fine carbon fiber aggregate, the titanium compound and the lithium compound by applying a shearing force to obtain a mixture of the opened fine carbon fiber, the titanium compound and the lithium compound;
- Step b-2 including a step of firing the mixture obtained in the step b-1 in an inert atmosphere.
- Step c-1 a step of opening and dispersing fine carbon fiber aggregates in a dispersion medium using a dispersant;
- Step c-2) A step of mixing the finely dispersed carbon fiber dispersion obtained in Step c-1, a titanium compound, and a lithium compound;
- Step c-3) In Step c-2 And baking the obtained mixture in an inert atmosphere.
- Step d-1 A step of opening, dispersing, and mixing fine carbon fiber aggregates using a dispersant in a mixture of a dispersion medium, a titanium compound, and a lithium compound; (Step d-2) including a step of firing the mixture obtained in Step d-1 in an inert atmosphere.
- the fine carbon fiber, titanium compound, and lithium compound used for producing the lithium titanium composite oxide composited with the fine carbon fiber of the present invention will be described.
- the fine carbon fiber constituting the fine carbon fiber aggregate used in the present invention is not particularly limited, but the carbon carbon-containing compound is used in a state where the arc discharge of the carbon electrode or the catalyst is floated or fixed. Preference is given to fine carbon fibers having a single-layer or multi-layer graphite layer having an outer diameter of 100 nm or less and an aspect ratio of 3 or more, which has been deposited and grown by pyrolysis on a catalyst heated to a temperature of at least ° C. The following four nanostructured carbon materials have been reported mainly from the shape, form, and structure of fine carbon fibers.
- Multi-walled carbon nanotube (graphite layer is a multi-layer concentric cylinder) (non-fishbone-like) Japanese Patent Publication Nos. 3-64606 and 3-77288 (Hyperion Catalysis International Inc.) JP-A-2004-299986 (Mitsubishi Materials Corporation) (Ii) Cup-stacked carbon nanotube (fishbone) USP 4,855,091 (Method for the preparation of carbon filaments) M.M. Endo, Y. et al. A. Kim etc. : Appl. Phys. Lett.
- a fine carbon fiber having a structure having the following characteristics can be used.
- the fine carbon fiber has a bell-shaped structure as shown in FIG. 1A as a minimum structural unit.
- the temple bell (temple ⁇ ⁇ bell) is found in Japanese temples, has a relatively cylindrical body, and is different in shape from a conical Christmas bell.
- the structural unit 11 has a top portion 12 and a trunk portion 13 having an open end, like a bell, and has a rotating body shape rotated about the central axis. It has become.
- the structural unit 11 is formed of a graphite network surface made of only carbon atoms, and the circumferential portion of the body portion open end is the open end of the graphite network surface.
- the central axis and the body portion 13 are shown as straight lines for convenience, but they are not necessarily straight lines and may be curved as shown in FIG.
- the trunk portion 13 gently spreads toward the open end.
- the bus bar of the trunk portion 13 is slightly inclined with respect to the central axis of the bell-shaped structural unit, and the angle ⁇ formed by both is smaller than 15 °. More preferably, 1 ° ⁇ ⁇ 15 °, and further preferably 2 ° ⁇ ⁇ 10 °. If ⁇ is too large, fine fibers composed of the structural unit exhibit a fishbone-like carbon fiber-like structure, and the conductivity in the fiber axis direction is impaired.
- the fine carbon fiber has defects and irregular turbulence, but if such irregularity is eliminated and the shape of the whole is captured, the bell 13 in which the body portion 13 gradually spreads toward the open end side. It can be said that it has a shape structure. Fine carbon fiber does not mean that ⁇ indicates the above range in all parts, but when the structural unit 11 is captured as a whole while excluding defective parts and irregular parts, Overall, it means that ⁇ satisfies the above range. Therefore, in the measurement of ⁇ , it is preferable to exclude the vicinity of the crown 12 where the thickness of the trunk may be irregularly changed. More specifically, for example, if the length of the bell-shaped structural unit aggregate 21 (see below) is L as shown in FIG.
- 1B, (1/4) L, (1/2 ) L and (3/4) L may be measured at three points to obtain an average, and this value may be used as the overall ⁇ for the structural unit 11.
- the body part 13 is often a curved line in practice, it may be closer to the actual value when measured along the curve of the body part 13. .
- the shape of the top of the head when manufactured as fine carbon fiber, is smoothly continuous with the trunk and has a curved surface that is convex upward (in the figure).
- the length of the top of the head is typically about D (FIG. 1 (b)) or less and about d (FIG. 1 (b)) for explaining the bell-shaped structural unit aggregate.
- bell-shaped structural units In the fine carbon fiber, as shown in FIG. 1 (b), 2 to 30 such bell-shaped structural units share a central axis to form a bell-shaped structural unit aggregate 21.
- the number of stacked layers is preferably 2 to 25, and more preferably 2 to 15.
- the outer diameter D of the trunk portion of the bell-shaped structural unit assembly 21 is 5 to 40 nm, preferably 5 to 30 nm, and more preferably 5 to 20 nm.
- D is increased, the diameter of the fine fibers formed is increased, so that a large amount of addition is required in order to impart conductive performance in combination with the lithium titanium composite oxide.
- D becomes small, the diameter of the fine fibers formed becomes thin and the aggregation of the fibers becomes strong, making it difficult to disperse and combine in the preparation of the composite.
- the measurement of the trunk outer diameter D is preferably performed by measuring at three points (1/4) L, (1/2) L, and (3/4) L from the top of the aggregate.
- drum outer diameter D is shown for convenience in FIG.1 (b), the value of actual D has the preferable average value of the said 3 points
- the inner diameter d of the aggregate body is 3 to 30 nm, preferably 3 to 20 nm, more preferably 3 to 10 nm.
- the inner diameter d of the trunk is also measured and averaged at three points (1/4) L, (1/2) L, and (3/4) L from the top of the bell-shaped structural unit assembly. Is preferred.
- drum internal diameter d is shown in FIG.1 (b) for convenience, the actual value of d has the preferable average value of the said 3 points
- the aspect ratio (L / D) calculated from the length L of the bell-shaped structural unit aggregate 21 and the body outer diameter D is 2 to 150, preferably 2 to 50, more preferably 2 to 20.
- the aspect ratio is large, the structure of the formed fiber approaches a cylindrical tube shape, and the conductivity in the fiber axis direction of one fiber is improved.
- the open end of the graphite network surface constituting the structural unit body is a fiber. Since the frequency of exposure to the outer peripheral surface is reduced, the conductivity between adjacent fibers is deteriorated.
- the aspect ratio is small, the open end of the graphite mesh surface constituting the structural unit body portion is more frequently exposed to the outer peripheral surface of the fiber, so that the conductivity between adjacent fibers is improved. Since many short graphite mesh surfaces are connected in the axial direction, conductivity in the fiber axial direction of one fiber is impaired.
- fine carbon fibers are formed by further connecting the aggregates in a head-to-tail manner.
- the joining parts of the adjacent aggregates are the top part (Head) of one aggregate and the lower end part (Tail) of the other aggregate.
- a specific form of the joining portion is that the outermost layer of the second bell-shaped structural unit assembly 21b is located further inside the bell-shaped structural unit of the innermost layer at the lower end opening of the first bell-shaped structural unit assembly 21a. The top of the bell-shaped structural unit is inserted, and the top of the third bell-shaped structural unit assembly 21c is inserted into the lower end opening of the second bell-shaped structural unit assembly 21b.
- the fine carbon fiber obtained by such partial fiber shortening has a fiber length in which several to several tens of bell-shaped structural unit aggregates are connected, preferably about 10 to 50.
- the aspect ratio of one fine carbon fiber is about 5 to 200. A more preferred aspect ratio is 10 to 50.
- Each joining portion forming one fine fiber of fine carbon fibers does not have structural regularity.
- the first bell-shaped structural unit aggregate and the second bell-shaped structural unit aggregate
- the length of the joint portion of the body in the fiber axis direction is not necessarily the same as the length of the joint portion of the second bell-shaped structural unit assembly and the third bell-shaped structural unit assembly.
- the two bell-shaped structural unit assemblies to be joined may be connected linearly while sharing the central axis.
- the central axes may be joined without being shared, resulting in a bent structure at the joint.
- the length L of the bell-shaped structural unit assembly is generally constant for each fiber.
- the fine carbon fiber has a peak half-value width W (unit: degree) measured in the XRD of the fine carbon fiber in the range of 2 to 4.
- W exceeds 4
- the graphite crystallinity is low and the conductivity is low.
- W is less than 2
- the fiber diameter becomes large, and a large amount of addition is required to impart conductivity to the lithium titanium composite oxide.
- the graphite interplanar spacing d002 obtained by XRD measurement of fine carbon fibers is 0.350 nm or less, preferably 0.341 to 0.348 nm. If d002 exceeds 0.350 nm, the graphite crystallinity is lowered and the conductivity is lowered. On the other hand, the fiber of less than 0.341 nm has a low yield in production.
- Ash contained in fine carbon fiber is 4% by weight or less, and refining is not required for normal use. Usually, it is 0.3 wt% or more and 1.5 wt% or less, more preferably 0.3 wt% or more and 1 wt% or less.
- the ash content is determined from the weight of the oxide remaining after burning 0.1 g or more of the fiber.
- the fine carbon fiber having the above characteristics forms an aggregate intricately intertwined into a lump of several tens ⁇ m to several mm immediately after generation by the vapor phase growth method described later.
- fine carbon fibers having the above characteristics can be easily separated at the joints by stress.
- the fine carbon fiber aggregate and the titanium compound are kneaded, or the dispersant and the fine carbon fiber aggregate are stirred and mixed in the dispersion medium, the fine carbon aggregate is obtained. Titanium dioxide particles enter inside, and the shearing force of kneading is given to the fine carbon fiber aggregates.
- the joints of the structural unit aggregates are joined at the graphite base surfaces adjacent to each other, and therefore, slippage easily occurs between the graphite base surfaces due to the application of stress parallel to the fiber axis. Are partly cut so that they can be pulled out from each other.
- the structural unit aggregate has a structure joined by van der Waals force, the joined portion can be separated with small energy, and the obtained fine carbon fiber is not damaged at all.
- the aggregates can be opened and dispersed efficiently while suppressing fiber cutting as much as possible.
- the graphite network surface of the same part which caused separation between structural units at the junction of some bell-shaped structural unit aggregates, is exposed on the outer peripheral surface of the fiber, and the end face of the graphite layer is more active. It exists as a site. As a result, fine carbon fibers adhere to the surface of the titanium particles, and solid particles whose surfaces are coated with fine carbon fibers are obtained.
- FIG. 4 shows a state in which the shearing force by kneading is applied to the fine carbon fiber.
- the force applied to the points A, B, and C acts as a compressive force perpendicular to the fiber axis direction and a tension parallel to the fiber axis direction with the B ′ point as a fulcrum.
- This tension acts at the joint of the structural unit assembly, which has the lowest tensile strength of the fiber of the present invention, in other words, easily slips between the graphite AB planes (between the graphite base surfaces), and the fibers are separated and cut at this portion. Is done.
- the carbon fiber is produced by a vapor phase growth method using a catalyst.
- a catalyst containing an element selected from the group consisting of Fe, Co, Ni, Al, Mg and Si is preferably used, and the supply gas is preferably a mixed gas containing CO and H 2 .
- the supply gas is preferably a mixed gas containing CO and H 2 .
- a catalyst in which magnesium is replaced by a solid solution with an oxide having a spinel crystal structure of cobalt a mixed gas containing CO and H 2 is supplied to the catalyst particles to form fine particles by vapor deposition.
- the fine carbon fiber having the bell-shaped structural unit supplies a mixed gas containing CO and H 2 to the catalyst particles by using a catalyst in which magnesium is substituted into an oxide having a spinel crystal structure of cobalt. And manufactured by vapor phase epitaxy.
- the spinel crystal structure of cobalt in which Mg is substituted and dissolved is represented by Mg x Co 3-x O y .
- x is a number indicating the replacement of Co by Mg, and formally 0 ⁇ x ⁇ 3.
- y is a number selected so that the entire expression is neutral in terms of charge, and formally represents a number of 4 or less. That is, in the spinel oxide Co 3 O 4 of cobalt, there are divalent and trivalent Co ions, where the divalent and trivalent cobalt ions are represented by Co II and Co III , respectively.
- a cobalt oxide having a spinel crystal structure is represented by Co II Co III 2 O 4 .
- Mg displaces both Co II and Co III sites and forms a solid solution. When Mg substitutes Co III for solid solution, the value of y becomes smaller than 4 in order to maintain charge neutrality. However, both x and y take values in a range where the spinel crystal structure can be maintained.
- the solid solution range of Mg is such that the value of x is 0.5 to 1.5, more preferably 0.7 to 1.5.
- the value of x is less than 0.5, the catalyst activity is low and the amount of fine carbon fibers produced is small.
- the value of x exceeds 1.5, it is difficult to prepare a spinel crystal structure.
- the spinel oxide crystal structure of the catalyst can be confirmed by XRD measurement, and the crystal lattice constant a (cubic system) is in the range of 0.811 to 0.818 nm, more preferably 0.812. ⁇ 0.818 nm. If “a” is small, the solid solution substitution of Mg is not sufficient and the catalytic activity is low. Also, the spinel oxide crystal having a lattice constant exceeding 0.818 nm is difficult to prepare.
- the particle size of the catalyst can be appropriately selected.
- the median diameter is 0.1 to 100 ⁇ m, preferably 0.1 to 10 ⁇ m.
- Catalyst particles are generally used by being applied to a suitable support such as a substrate or a catalyst bed by a method such as spraying.
- the catalyst particles may be sprayed directly onto the substrate or the catalyst bed, but the catalyst particles may be sprayed directly, but a desired amount may be sprayed by suspending in a solvent such as ethanol and drying.
- the catalyst particles are preferably activated before reacting with the raw material gas. Activation is usually performed by heating in a gas atmosphere containing H 2 or CO. These activation operations can be performed by diluting with an inert gas such as He or N 2 as necessary.
- the temperature at which the activation is performed is preferably 400 to 600 ° C., more preferably 450 to 550 ° C.
- the reactor for the vapor phase growth method there are no particular limitations on the reactor for the vapor phase growth method, and the reaction can be carried out using a reactor such as a fixed bed reactor or a fluidized bed reactor.
- a mixed gas containing CO and H 2 is used as a source gas that becomes a carbon source for vapor phase growth.
- the addition concentration of H 2 gas ⁇ H 2 / (H 2 + CO) ⁇ is preferably 0.1 to 30 vol%, more preferably 2 to 20 vol%. If the addition concentration is too low, a cylindrical graphitic network surface forms a carbon nanotube-like structure parallel to the fiber axis. On the other hand, if it exceeds 30 vol%, the inclination angle of the carbon-side peripheral surface of the bell-shaped structure with respect to the fiber axis becomes large, and the fish-bone shape is exhibited, leading to a decrease in conductivity in the fiber direction.
- the reaction temperature for carrying out the vapor phase growth is preferably 400 to 650 ° C., more preferably 500 to 600 ° C. If the reaction temperature is too low, fiber growth does not proceed. On the other hand, if the reaction temperature is too high, the yield decreases.
- reaction time is not specifically limited, For example, it is 2 hours or more, and is about 12 hours or less.
- the reaction pressure for carrying out the vapor phase growth is preferably normal pressure from the viewpoint of simplifying the reaction apparatus and operation, but it is carried out under pressure or reduced pressure as long as Boudard equilibrium carbon deposition proceeds. It doesn't matter.
- the amount of fine carbon fiber produced per unit weight of the catalyst was much larger than that of the conventional production method.
- the amount of fine carbon fibers produced by this fine carbon fiber production method is 40 times or more per unit weight of the catalyst, for example, 40 to 200 times. As a result, it is possible to produce fine carbon fibers with less impurities and ash as described above.
- the catalyst has a balance between the exothermic Boudouard equilibrium and the heat removal by the flow of the raw material gas. Since the temperature in the vicinity of the cobalt fine particles formed from oscillates up and down, it is considered that carbon deposition is formed by intermittent progress. That is, [1] formation of the top of the bell-shaped structure, [2] growth of the trunk of the bell-shaped structure, [3] growth stop due to temperature rise due to heat generated in the processes [1] and [2], [4] It is presumed that a fine junction of the carbon fiber structure is formed by repeating the four processes of cooling with the flow gas on the catalyst fine particles.
- the titanium compound used in the present invention is preferably titanium dioxide and / or titanium hydroxide.
- Titanium dioxide has an anatase type crystal, a rutile type crystal, or an amorphous type, and anatase type or amorphous type is preferably used. Titanium dioxide can be obtained by dehydrating and firing titanium hydroxide. Moreover, since the electric capacity per unit mass will fall when it uses as an electrode material when an impurity increases, it is preferable that the purity of titanium dioxide is 98 mass% or more.
- Titanium hydroxide metatitanic acid represented by TiO (OH) 2 (TiO 2 ⁇ H 2 O), ortho-titanate represented by Ti (OH) 4 (TiO 2 ⁇ 2H 2 O) and the like, Mixtures of these can also be used.
- Titanium hydroxide can be obtained by heat hydrolysis or neutralization hydrolysis of titanyl sulfate, titanium chloride, titanium alkoxide or the like.
- the shape of the titanium compound is not particularly limited, but a spherical shape or a pseudo-spherical shape (a rod shape, a spindle shape, or a polyhedral particle) is preferable.
- the particle size of the titanium compound is preferably 20 nm or more and less than 500 nm. If the particle size is too small, in the above (Step a-1) or (Step b-1), since the particle size of the titanium compound is small relative to the size of the fine carbon fiber aggregate, the shear force is weak, and the aggregate Opening is difficult to proceed.
- step c-2 the slurry viscosity increases in the preparation of the slurry solution in the above (step c-2), and it becomes difficult to prepare a high-concentration slurry. If the particle size is too large, the combination of fine carbon fibers and lithium titanate composite oxide does not proceed and separation is likely to occur.
- lithium compound used in the present invention examples include water-soluble lithium compound particles such as lithium hydroxide (LiOH, LiOH.H 2 O), lithium carbonate, lithium nitrate, and lithium sulfate.
- water-soluble lithium compound particles such as lithium hydroxide (LiOH, LiOH.H 2 O), lithium carbonate, lithium nitrate, and lithium sulfate.
- step a-1 titanium compound particles and fine carbon fiber aggregates are kneaded by applying a shearing force. Thereby, fine carbon fiber aggregates are opened, and titanium compound particles combined with fine carbon fibers are obtained.
- the weight ratio of the titanium compound and the fine carbon fiber aggregate during kneading is preferably 1000: 1.15 to 10: 1.15, and preferably 1000: 8.6 to 20: 1.15. Particularly preferred.
- a solvent may be used or no solvent may be used.
- the solvent include polar solvents such as water and alcohol, aromatic compounds such as xylene and toluene, and aprotic polar solvents such as N-methyl-2-pyrrolidone and dimethyl sulfoxide.
- the apparatus to which the shearing force can be applied is not particularly limited. For example, a mortar, a ball mill, a centrifugal ball mill, a planetary ball mill, a vibrating ball mill, an attritor type high-speed ball mill, a roll mill, and the like can be used.
- the kneading time is not particularly limited, but is preferably 15 seconds or longer.
- the mixture of the finely spread carbon fiber obtained in (Step a-1) and the titanium compound and the lithium compound are mixed at a Li / Ti molar ratio. It is preferable to mix so that it may become 0.75 or more and 0.88 or less. The reason why this molar ratio is preferable will be described later.
- a centrifugal planetary mill, a media mill, a roll mill, or the like can be used.
- step a-3 the mixture obtained in the above (step a-2) is heated in an inert atmosphere such as nitrogen gas or argon gas, dried, dehydrated, and fired.
- an inert atmosphere such as nitrogen gas or argon gas
- Step a-3 Li 2 TiO 3 is formed on the surface of titanium dioxide particles at a temperature exceeding about 470 ° C. at which LiOH melts (the following formula (1)), 2LiOH + TiO 2 ⁇ Li 2 TiO 3 + H 2 O (g) (1)
- Li 2 TiO 3 further reacts with TiO 2 inside the particles, titanium dioxide TiO 2 is converted into a lithium titanium composite Li 4 Ti 5 O 12 (the following formula (2)).
- step a-2 by mixing so that the Li / Ti molar ratio in the mixture is 0.75 or more and 0.88 or less, the spinel structure Li 4 Ti excellent in electrochemical characteristics is obtained. It becomes easy to produce a lithium titanium composite oxide containing 5 O 12 as a main component. If the Li / Ti molar ratio is too large, the formation of Li 2 TiO 3 becomes remarkable, and if it is too small, the by-product Li 2 Ti 3 O 7 and unreacted TiO 2 remain.
- the firing temperature in (Step a-3) is preferably 550 ° C. or higher and lower than 950 ° C., more preferably 650 ° C. or higher and 900 ° C. or lower. If the firing temperature is too low, in the reaction exemplified above, the conversion to the lithium titanium composite oxide Li 4 Ti 5 O 12 having a spinel structure becomes incomplete, and if the firing temperature is too high, the ramsdellite structure Li 2 A heterogeneous phase such as Ti 3 O 7 is generated, causing a decrease in charge / discharge capacity and load characteristics.
- the firing time is preferably 60 minutes or more and less than 300 minutes. If the firing time is too short, the conversion of the starting raw material TiO 2 is insufficient, and if the firing time is too long, grain growth proceeds and the particles become coarse.
- a reaction such as drying, dehydration, or firing, or a rotary heating furnace
- a solvent is used in (Step a-1) or (Step a-2)
- the mixture is similarly filled in a mortar, dehydrated and fired.
- the target can also be obtained.
- step b-1 the fine carbon fiber aggregate, the titanium compound and the lithium compound are kneaded by applying a shearing force. Thereby, the aggregate of a fine carbon fiber is opened, and the mixture of a fine carbon fiber, a titanium compound, and a lithium compound is obtained.
- Step b-1 the weight ratio of fine carbon fiber and titanium compound and the molar ratio of titanium compound and lithium compound during kneading are described in the above (Step a-1) and (Step a- Same as 2).
- the kneading method is the same as the method described in the above (Step a-1).
- Step b-2) is the same as (Step a-3) described above.
- step c-1 fine carbon fiber aggregates are opened and dispersed in a dispersion medium using a dispersant.
- Dispersants include surfactants such as sodium oleate, polyoxyethylene carboxylic acid ester, monoalcohol ester, ferrocene derivative, pyrene compound (pyrene ammonium), porphyrin compound (ZnPP, Hemin, PPEt), polyfluorene, cyclic glucan Cyclic / polycyclic aromatic compounds such as folic acid, lactam compounds (—CONH—), lactone compounds (—CO—O—), linear conjugated polymers such as polythiophene, polyphenylene vinylene, polyphenylene ethylene, polyvinylpyrrolidone ( Cyclic amides such as PVP), polystyrene sulfonic acid, polymer micelles, water-soluble pyrene-containing polymers, fructose, polysaccharides (such as carboxymethylcellulose), saccharides such as amylose, inclusion complexes such as lataxane, and cholic acid analogs.
- surfactants such as sodium ole
- dispersion medium is an aqueous solution system
- carboxymethyl cellulose, polyvinyl pyrrolidone are preferred.
- the dispersant is preferably added in a mass ratio of 1/100 to 50/100 with respect to the fine carbon fiber aggregates.
- the dispersion medium is not particularly limited, but polar solvents such as water and alcohols are usually used from the viewpoint of handling and solubility of the lithium compound.
- the fine carbon fiber aggregates are spread and dispersed by combining the dispersion medium, the dispersant and the fine carbon fiber aggregates, and stirring them with a homomixer, trimix, etc.
- a bead mill and a paint shaker using ultrasonic waves by vibration shock waves, impact of beads, balls, etc., shaking are used.
- the fine carbon fiber aggregates can be oxidized before the fine carbon fiber aggregates are dispersed.
- the fine carbon fiber aggregates can be oxidized.
- the fine carbon fibers are easily adapted to the dispersion medium.
- an oxidation treatment method for example, liquid phase oxidation with nitric acid / sulfuric acid, ozone, supercritical water, supercritical carbon dioxide gas, or the like, or hydrophilization treatment on the surface of carbon fiber by air firing, gas phase oxidation with oxygen plasma, etc. The method of giving is mentioned.
- Step c-2 the fine carbon fiber dispersion obtained in (Step c-1), the titanium compound, and the lithium compound are mixed. At the time of mixing, it is preferable to mix the titanium compound and the lithium compound so that the Li / Ti molar ratio is 0.75 or more and 0.88 or less, as in the above (Step a-2).
- step c-2 a slurry solution in which a titanium compound is suspended in a lithium compound solution is prepared, and the slurry solution and the fine carbon fiber dispersion obtained in (step c-1) Are preferably mixed.
- the slurry solution is preferably prepared by mixing in the same dispersion medium used for opening and dispersing fine carbon fiber aggregates so that the weight ratio is 10 to 70%.
- Step c-3) is the same as (Step a-3) described above.
- step d-1 fine carbon fiber aggregates are opened, dispersed, and mixed using a dispersant in a mixture of a dispersion medium, a titanium compound, and a lithium compound.
- the dispersion medium, dispersant, dispersion method, and the like used here are the same as in the above (Step c-1).
- a preferable molar ratio in mixing the titanium compound and the lithium compound is the same as in the above (step c-2).
- Step d-2) is the same as (Step a-3) described above.
- the dispersant when used in a mode other than the above, when the fine carbon fiber aggregate is opened, at least the dispersion medium, the dispersant, and the fine carbon fiber aggregate may be included. These compounds may be mixed when the fine carbon fiber aggregate is opened, or may be mixed after the opening.
- the fine carbon fiber may be fixed and fixed using a binder.
- a method for fixing fine carbon fibers to the inside or the surface of lithium titanium composite oxide particles for example, a method using a binder such as carbon, an aqueous binder, a non-aqueous binder, or a fluorine binder. Is mentioned.
- the method using carbon as the binder include a method using a carbon precursor and a CVD method.
- a carbon precursor is used as the binder, for example, in the above (Step a-1), (Step b-1), (Step c-1) or (Step d-1), the carbon precursor is used as it is or A solution obtained by dissolving a carbon precursor in a solvent and fine carbon fibers are kneaded and mixed together, and the fine carbon fibers are opened and dispersed, and then the mixture is heat-treated in an inert gas atmosphere. Thereby, the precursor is converted to carbon, and solid particles in which fine carbon fibers are dispersed and bound to the surface through the carbon are obtained.
- the carbon precursor coal tar, coal tar pitch, petroleum heavy oil, petroleum pitch, saccharides such as sucrose (sucrose), polyhydric alcohol, (water-soluble) phenol resin, furan resin, etc. may be used. it can.
- the heat treatment can be performed simultaneously with the firing in an inert atmosphere under the flow of an organic gas vaporized and entrained in an inert gas.
- lithium titanium composite oxide Li 4 Ti 5 O 12 particles, etc.
- Step a-3 lithium titanium composite oxide (Li 4 Ti 5 O 12 particles, etc.) once calcined by the above (Step a-3), (Step b-2), (Step c-3) or (Step d-2)
- Step d-2 lithium titanium composite oxide
- impurities of lithium titanium composite oxide are mainly due to titanium dioxide / titanium hydroxide as a starting material and contamination from the heating device.
- the impurities of titanium dioxide / titanium hydroxide are derived from ore and the manufacturing process (sulfuric acid method, chlorine method), Nb 2 O 5 (0.1 to 0.5 wt%), SO 3 (0.1 to 0.2 wt%).
- TiO 2 purity for electrical capacity per unit mass when the impurity increases decreases is preferably at least 98 mass%.
- the electrolyte contains a lithium compound as a solute that exhibits ionic conductivity, and a solvent that dissolves and holds the solute is a charge / discharge of the battery. It can be used as long as it does not decompose at the time of storage or storage.
- solutes include LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3, etc.
- solvents include ethylene carbonate (EC), Cyclic carbonates such as propylene carbonate (PC) and vinylene carbonate (VC), chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC), tetrahydrofuran (THF), 2 methyl tetrahydrofuran (2 MeTHF) ), Cyclic ethers such as dimethoxyethane (DME), ⁇ -butyrolactone (BL), acetonitrile (AN), sulfolane (SL), and sultone such as 1,3-propane sultone and 1,3-propene sultone
- the organic solvents can be used singly or in combination.
- a gel polymer electrolyte obtained by impregnating a polymer electrolyte such as polyethylene oxide or polyacrylonitrile with an electrolytic solution, or an inorganic solid electrolyte such as LiI can be used.
- the negative electrode active material is a carbon material such as graphite or coke, Li metal, Li / Al alloy, Li / In alloy, Li / Al / A Li alloy such as a Mn alloy can be used, and the charging voltage is about 3.0 V and the discharging voltage is about 1.0 to 1.5 V.
- the positive electrode active material LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiMnO 2 , LiCo 0.5 Ni 0.5 O 2 , LiCo 1/3 Ni 1/3 Mn 1 / 3 O 2 , LiNi 0.7 Co 0.2 Mn 0.1 O 2 , LiCo 0.9 Ti 0.1 O 2 , LiCo 0.5 Ni 0.4 Zr 0.1 O 2 , LiFePO 4 , LiFe 1 A lithium-containing transition metal composite oxide such as -x Co x PO 4 can be used, and the charging voltage is about 2.5 to 3.0 V and the discharging voltage is about 2 to 2.5 V.
- these positive electrode active materials are electrode materials examined in the lithium ion secondary battery in which a high load characteristic is requested
- fine carbon fibers used in the examples are as follows.
- fine carbon fiber A cobalt nitrate fine carbon fiber of ion-exchanged water 500mL with graphite quality temple-bell-shaped structural unit [Co (NO 3) 2 ⁇ 6H 2 O: molecular weight 291.03] 115 g (0.40 mol) , magnesium nitrate [Mg (NO 3) 2 ⁇ 6H 2 O: molecular weight 256.41] 102 g (0.40 mol) was dissolved, the raw material solution (1) was prepared.
- Fine carbon fiber B concentric multi-walled carbon nanotube (Aldrich reagent) Aggregates (outer diameter of pills of 5 to 5 nm), in which fine carbon fibers having an outer diameter of 5 to 25 nm, an inner diameter of 3 to 10 nm, a number of layers of 3 to 17, a length of 0.5 to 10 ⁇ m, and an aspect ratio of 50 to 400 are assembled 100 ⁇ m, pore diameter 500 nm).
- Example 1 Anatase-type titanium dioxide particles [TiO 2 : molecular weight 799.8658] (Sakai Chemical Industry Co., Ltd. SA-1, average primary particle size 0.15 ⁇ m, specific surface area 9.7 m 2 / g) Carbon fiber aggregate A 2.35 parts by mass (2% by mass with respect to the total weight of lithium titanate), an appropriate amount of ethanol as a solvent was added and mixed, and then the number of revolutions was 250 RPM using a ball centrifugal planetary mill with an inner diameter of 5 cm. For 30 minutes. The balls used were made from agate and had a diameter of 10 mm.
- the solvent is dried at 100 ° C., and a mixture of titanium dioxide particles in which fine carbon fibers A are dispersed and coated is mixed with lithium hydroxide [LiOH.H 2 O: molecular weight 41.96362] (Honjo Chemical Co., Ltd.). 42.0 parts by mass (Li / Ti molar ratio 0.80) was added, mixed for 10 minutes using a centrifugal planetary mill, and used as a firing raw material. The mixture was filled in an alumina bowl and baked at 800 ° C. for 180 minutes in a nitrogen gas atmosphere.
- lithium hydroxide LiOH.H 2 O: molecular weight 41.96362
- the fine carbon fiber A as shown in FIG. was taken into the grain interface and within the grain and was observed to be uniformly dispersed throughout the field of view.
- the average particle size quantified using a laser diffraction / scattering particle size distribution analyzer Microtrac MT3300EXII (manufactured by Nikkiso Co., Ltd.) was 250 nm. After degassing by drying at 100 ° C.
- Li 4 Ti 5 O 12 Lithium titanium composite oxide particles in which fine carbon fibers A were complexed in a network shape were pressurized to 100 kg / cm 2 G and measured with a DC resistance meter. The volume resistivity was 2 ⁇ 10 3 ⁇ ⁇ cm.
- Examples 2 to 7 Lithium titanate composited with fine carbon fibers by using the same titanium dioxide particles and fine carbon fibers A and B as in Example 1 and changing the content of fine carbon fibers and firing conditions under the conditions in Table 1 Composite oxide particles were produced, and the average particle size, specific surface area, crystal structure analysis, and volume resistivity were measured in the same manner as in Example 1. Their preparation conditions and physical properties are shown in Table 1.
- Lithium titanium composite oxide particles were prepared in the same manner without adding the fine carbon fibers of Example 1, and the same method as in Example 1 was used to obtain the average particle diameter, specific surface area, XRD crystal structure analysis, volume resistance. The rate was measured. The results are shown in Table 1.
- Example 8 Preparation of fine carbon fiber aqueous dispersion 5 parts by weight of fine carbon fiber A is added to an aqueous solution in which 1 part by weight of carboxymethylcellulose (Daicel Finechem Co., Ltd. CMC Daicel 1110) is dissolved in 94 parts by weight of ion-exchanged water. After mixing, the mixture was opened and dispersed for 40 minutes with an ultrasonic generator (Ultrasonic Homogenizer Model US-600T), and a fine carbon fiber aqueous dispersion containing 5% by mass of fine carbon fibers. was prepared.
- an ultrasonic generator Ultrasonic Homogenizer Model US-600T
- Lithium carbonate [Li 2 CO 3 : molecular weight 73.8909] (60M manufactured by Kennametal, average primary particle size 5.3 ⁇ m, specific surface area 1.4 m 2 / g) 38.0 parts by weight (Li / Ti molar ratio 0.82) was stirred, mixed and dissolved in 160 parts by weight of ion-exchanged water, and then titanium dioxide particles (the same as those used in Example 1) 100 parts by weight. The part was put into suspension and slurried.
- the lithium titanium composite oxide composited with fine carbon fibers has an average particle size of 250 nm and a specific surface area of 11 m 2 / g, and shows a single phase of Li 4 Ti 5 O 12 from X-ray diffraction crystal structure analysis (XRD). It was. Lithium titanium composite oxide particles in which fine carbon fibers A were complexed in a network shape were pressurized to 100 kg / cm 2 G and measured with a DC resistance meter. The volume resistivity was 2 ⁇ 10 2 ⁇ ⁇ cm.
- Example 2 A lithium titanium composite oxide complexed with carbonaceous matter was produced in the same manner as in Example 8 except that the carbonaceous precursor sucrose (sucrose) was used in place of the fine carbon fiber. 5.59 parts by weight of sucrose (carbonization rate 42% by mass, 2% by mass with respect to the total mass) and 38.0 parts by weight of lithium carbonate (Li / Ti molar ratio 0.82) were dissolved in 200 parts by weight of ion-exchanged water. 100 parts by weight of titanium dioxide particles were suspended, slurried, spray-dried and fired.
- sucrose carbonization rate 42% by mass, 2% by mass with respect to the total mass
- lithium carbonate Li / Ti molar ratio 0.82
- the obtained lithium titanium composite oxide particles showed an average particle diameter of 250 nm, a specific surface area of 12 m 2 / g, and a single phase of Li 4 Ti 5 O 12 from XRD crystal structure analysis.
- the volume resistivity was 3 ⁇ 10 5 ⁇ ⁇ cm.
- Example 9 Instead of the titanium dioxide of Example 8, amorphous fine particle titanium dioxide having an average primary particle diameter of 21 nm (Nippon Aerosil Co., Ltd. AEROXIDE TiO 2 P-25, average primary particle diameter of 30 nm, specific surface area of 50 m 2 / g) was used.
- a lithium titanium composite oxide composited with fine carbon fibers was produced in the same manner as in Example 8. After stirring and mixing and dissolving 38.0 parts by weight of lithium carbonate (Li / Ti molar ratio 0.82) in 300 parts by weight of ion-exchanged water, 100 parts by weight of fine particle titanium dioxide was added, suspended and slurried.
- the lithium titanium composite oxide particles composited with fine carbon fibers showed an average particle diameter of 100 nm, a specific surface area of 21 m 2 / g, and a single phase of Li 4 Ti 5 O 12 from XRD crystal structure analysis.
- the volume resistivity was 9 ⁇ 10 3 ⁇ ⁇ cm.
- Example 10 Using the electrode materials obtained in Examples and Comparative Examples as active materials, the electrode materials, acetylene black (Denka Black, Denki Kagaku Kogyo Co., Ltd.) and polyvinylidene fluoride (PVDF) (Kureha KF Polymer Co., Ltd.) An electrode slurry was prepared by kneading in a kneader using N-methylpyrrolidone as a solvent at a mass ratio of 90: 5: 5. After applying the electrode paste to the aluminum mesh substrate, vacuum drying was performed at 150 ° C. to prepare a positive electrode plate (15 mm ⁇ ).
- acetylene black Denki Kagaku Kogyo Co., Ltd.
- PVDF polyvinylidene fluoride
- EC ethylene carbonate
- DMC dimethyl carbonate
- the lithium titanium composite oxide particles composited with the fine carbon fibers of the present invention are lithium titanium with poor electrical conductivity because fine carbon fibers having a graphite structure are composited in a network form on the particle surface and inside the particles. Conductivity is imparted to the composite oxide particles to facilitate the movement of electrons and lithium ions.
- an electrode material that is useful as a lithium battery that requires high load characteristics and cycle characteristics for in-vehicle use and tools.
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Abstract
Description
(工程a-2)工程a-1で得られた混合物と、リチウム化合物とを混合する工程と、
(工程a-3)工程a-2で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。
(工程b-2)工程b-1で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。
(工程c-2)工程c-1で得られた開繊された微細な炭素繊維の分散液と、チタン化合物と、リチウム化合物とを混合する工程と
(工程c-3)工程c-2で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。
(工程d-2)工程d-1で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。
本発明は、リチウムチタン複合酸化物の表面および内部が、微細な炭素繊維で網状に複合化されていることを特徴とする。本発明は、高導電物質である微細な炭素繊維が、リチウムチタン複合酸化物の表面および内部に存在しており、高い電気伝導性が得られる。また、微細な炭素繊維が網状に複合化しているため、リチウムチタン複合酸化物の表面が電解質と直接接触可能であり、リチウムイオンの拡散移動がしやすく、電極材料として高い出力特性を有する。
上記微細な炭素繊維と複合化されたリチウムチタン複合酸化物の製造方法は、たとえば、下記の態様を挙げることができる。
(工程a-1)微細な炭素繊維凝集体とチタン化合物とを剪断力を加えて混練し、開繊された微細な炭素繊維とチタン化合物との混合物を得る工程と、
(工程a-2)工程a-1で得られた混合物と、リチウム化合物とを混合する工程と、
(工程a-3)工程a-2で得られた混合物を、不活性雰囲気中焼成する工程とを含む。
(工程b-1)微細な炭素繊維凝集体とチタン化合物とリチウム化合物とを、剪断力を加えて混練し、開繊された微細な炭素繊維とチタン化合物とリチウム化合物との混合物を得る工程と、
(工程b-2)工程b-1で得られた混合物を、不活性雰囲気中焼成する工程とを含む。
(工程c-1)分散媒体中、微細な炭素繊維凝集体を、分散剤を用いて開繊および分散させる工程と、
(工程c-2)工程c-1で得られた開繊された微細な炭素繊維の分散液と、チタン化合物と、リチウム化合物とを混合する工程と
(工程c-3)工程c-2で得られた混合物を、不活性雰囲気中焼成する工程とを含む。
(工程d-1)分散媒体とチタン化合物とリチウム化合物との混合物中、分散剤を用いて微細な炭素繊維凝集体を開繊および分散・混合させる工程と、
(工程d-2)工程d-1で得られた混合物を、不活性雰囲気中焼成する工程とを含む。
本発明に用いられる微細な炭素繊維の凝集体を構成する微細な炭素繊維は、特に限定されないが、炭素電極のアーク放電や、触媒を浮遊あるいは固定させた状態でガス状の炭素含有化合物を500℃以上に加熱した触媒上で熱分解することによって析出、成長した外径100nm以下、アスペクト比3以上の単層あるいは多層のグラファイト層をもつ微細な炭素繊維であることが好ましい。微細な炭素繊維は、その形状、形態、構造から、主に以下の4つのナノ構造炭素材料が報告されている。
(i)多層カーボンナノチューブ(グラファイト層が多層同心円筒状)(非魚骨状)
特公平3-64606、同3-77288(Hyperion Catalysis International Inc.)
特開2004-299986(三菱マテリアル(株))
(ii)カップ積層型カーボンナノチューブ(魚骨状(フィッシュボーン))
USP 4,855,091(Method for the preparation of carbon filaments)
M.Endo, Y.A.Kime etc.:Appl.Phys.Lett.,vol80(2002)1267~
特開2003-073928((株)GSIクレオス)
特開2004-360099(三菱化学(株))
(iii)節型カーボンナノファイバー(非魚骨構造)
J.P.Pinheiro, P.Gadelle etc.:Carbon,41(2003)2949~2959
P.E.Nolan,M.J.Schabel,D.C.Lynch:Carbon,33[1](1995)79~85
(iv) プレートレット型カーボンナノファイバー(トランプ状)
H.Murayama、 T.maeda,:Nature, vol345[No28](1990)791~793
特開2004-300631(三菱マテリアル(株))
微細な炭素繊維の製造方法としては、アーク放電法や気相成長法、レーザー法、鋳型法等が知られているが、好ましくは触媒を用いて、気相成長法により製造される。触媒としては、好ましくはFe、Co、Ni、Al、MgおよびSiからなる群より選ばれる元素を含む触媒が使用され、供給ガスは、好ましくはCO及びH2を含む混合ガスである。最も好ましくは、コバルトのスピネル型結晶構造を有する酸化物に、マグネシウムが固溶置換した触媒を用いて、CO及びH2を含む混合ガスを触媒粒子に供給して気相成長法により、微細な炭素繊維を製造する。以下、気相成長法による上記釣鐘状構造体を有する微細な炭素繊維の製造方法について一例として説明する。
本発明において使用されるチタン化合物は、二酸化チタン及び/又は水酸化チタンであることが好ましい。
本発明において使用されるリチウム化合物としては、例えば、水酸化リチウム(LiOH、LiOH・H2O)、炭酸リチウム及び硝酸リチウム、硫酸リチウムなど水溶性リチウム化合物粒子が挙げられる。
2LiOH + TiO2 → Li2TiO3 + H2O(g) (1)
Li2TiO3が更に粒子内部のTiO2と反応することにより二酸化チタンTiO2がリチウムチタン複合物Li4Ti5O12へ転換する(下記式(2))。
上記のように、二酸化チタン粒子が、リチウムチタン複合酸化物粒子へ転換する際に、微細な炭素繊維が網状に粒子内部へ取り込まれ、また粒子表面を覆い、微細な炭素繊維との複合化が達成される。
本発明の微細な炭素繊維と複合化されたリチウムチタン複合酸化物においては、微細な炭素繊維が、結着剤を用いて固定、固着されていてもよい。微細な炭素繊維をリチウムチタン複合酸化物の粒子内部又は表面に固着する方法として、例えば、炭素、水系結着剤、非水系結着剤、あるいはフッ素系結着剤等の結着剤を用いる方法が挙げられる。結着剤として炭素を用いる方法としては、炭素前駆体を用いる方法やCVD法等が挙げられる。
なお、リチウムチタン複合酸化物には不純物が取り込まれうるが、これらは主に出発原料となる二酸化チタン/水酸化チタン及び加熱装置からの混入に因る。二酸化チタン/水酸化チタンの不純物は、鉱石と製造プロセス(硫酸法、塩素法)に由来し、Nb2O5(0.1~0.5wt%)、SO3(0.1~0.2wt%)、HCl(0.3wt%以下)、P2O5(0.1~0.2wt%)、K2O(0.01~0.3wt%)、Na2O(0.005~0.3wt%)、Fe(0.01wt%)、SiO2(0.02~0.2wt%)、Al2O3(0.3wt%)、MgO(0.005wt%)、Pb(40ppm以下)、ZnO(0.1wt%以下)、Cr(0.01wt%以下)、Ni(0.01wt%以下)等が含まれるが、リチウムチタン複合酸化物の電気化学反応に影響を及ぼすものではない。また、電極材料としての特性を低下させるものではないが、不純物が多くなると単位質量当たりの電気容量が下がるためTiO2純度は98質量%以上が好ましい。
本発明のリチウムチタン複合酸化物をリチウム二次電池用電極材料として用いる場合、その電解質は、イオン導電性を発現させる溶質としてのリチウム化合物を含み、溶質を溶解、保持する溶媒が電池の充放電時又は保存時において分解しない限り用いることができる。具体的な溶質としては、LiClO4、LiPF6、LiBF4、LiCF3SO3、LiN(CF3SO2)2、LiC(CF3SO2)3等、溶媒としては、エチレンカーボネート(EC)、プロピレンカーボネート(PC)、ビニレンカーボネート(VC)等の環状カーボネート、ジメチルカーボネート(DMC)、メチルエチルカーボネート(MEC)、ジエチルカーボネート(DEC)等の鎖状カーボネート、テトラヒドロフラン(THF)、2メチルテトラヒドロフラン(2MeTHF)等の環状エーテル、ジメトキシエタン(DME)等の鎖状エーテル、γ―ブチロラクトン(BL)、アセトニトリル(AN)、スルホラン(SL)及び1,3-プロパンスルトン、1,3-プロペンスルトン等のスルトン類が挙げられ、これらの有機溶媒は、単独又は2種以上の混合物で用いることができる。更に電解質として、ポリエチレンオキシド、ポリアクリロニトリル等のポリマー電解質に電解液を含浸したゲル状ポリマー電解質や、LiI等の無機固体電解質が用いることができる。
<参考例>
(i)微細な炭素繊維A:グラファイト質釣鐘状構造単位を有する微細な炭素繊維
イオン交換水500mLに硝酸コバルト〔Co(NO3)2・6H2O:分子量291.03〕115g(0.40モル)、硝酸マグネシウム〔Mg(NO3)2・6H2O:分子量256.41〕102g(0.40モル)を溶解させ、原料溶液(1)を調製した。また、重炭酸アンモニウム〔(NH4)HCO3:分子量79.06〕粉末220g(2.78モル)をイオン交換水1100mLに溶解させ、原料溶液(2)を調製した。次に、反応温度40℃で原料溶液(1)と(2)を混合し、その後4時間攪拌混合した。生成した沈殿物のろ過、洗浄を行い、乾燥した。
これを焼成した後、乳鉢で粉砕し、43gの触媒を取得した。本触媒中のスピネル構造の結晶格子定数a(立方晶系)は0.8162nm、置換固溶によるスピネル構造中の金属元素の比はMg:Co=1.4:1.6であった。
石英製反応管(内径75mmφ、高さ650mm)を立てて設置し、その中央部に石英ウール製の支持体を設け、その上に触媒0.9gを散布した。He雰囲気中で炉内温度を550℃に加熱した後、CO、H2からなる混合ガス(容積比:CO/H2=95.1/4.9)を原料ガスとして反応管の下部から1.28L/分の流量で7時間流し、微細な炭素繊維凝集体を合成した。
収量は53.1gであり、灰分を測定したところ1.5重量%であった。生成物のXRD分析で観察されたピーク半価幅W(degree)は3.156、d002は0.3437nmであった。本参考例で得られた微細な炭素繊維AのTEM像を図3に示す。TEM画像から、得られた微細な炭素繊維を構成する釣鐘状構造単位及びその集合体の寸法に関するパラメータは、D=12nm、d=7nm、L=114nm、L/D=9.5、θは0から7°であり、平均すると約3°であった。また、集合体を形成する釣鐘状構造単位の積層数は約10であった。尚、D、dおよびθについては、集合体の塔頂から(1/4)L、(1/2)Lおよび(3/4)Lの3点について測定した。
外径5~25nm、内径3~10nm、層数3~17、長さ0.5~10μm、アスペクト比50~400)の微細な炭素繊維が毛玉状に集合した凝集体(毛玉外径5~100μm、空孔直径500nm)。
アナターゼ型二酸化チタン粒子[TiO2:分子量79.8658](堺化学工業(株)SA-1、平均一次粒子径0.15μm、比表面積9.7m2/g)100質量部に対し、微細な炭素繊維凝集体A2.35質量部(チタン酸リチウム総重量に対し2質量%)、溶媒としてエタノールを適当量加えて混合後、本体内径直径5cmメノウ製ボール遠心遊星ミルを用いて、回転数250RPMで30分間混合した。尚、用いたボールはメノウ製であり、その直径は10mmであった。混合終了後、溶媒を100℃で乾燥し、微細な炭素繊維Aが分散、被覆された二酸化チタン粒子混合物に水酸化リチウム[LiOH・H2O:分子量41.96362](本荘ケミカル(株)製ザラメ状)42.0質量部(Li/Tiモル比0.80)を加え、遠心遊星ミルを用いて10分間混合し、焼成原料に供した。混合物をアルミナ製匣鉢に充填し、窒素ガス雰囲気中800℃、180分の焼成を行った。焼成処理後の微細な炭素繊維Aと複合化されたリチウムチタン複合酸化物粒子を走査電子顕微鏡(日立ハイテクノロジー株式会社製 S-4800)で観察したところ、図5のように微細な炭素繊維Aは粒子界面及び粒内に取り込まれ、視野全体に均一分散している状態が観察できた。この微細な炭素繊維と複合化されたリチウムチタン複合酸化物について解析したところ、レーザー回折・散乱型粒度分布計Microtrac MT3300EXII(日機装株式会社製)を用いて定量化した平均粒子径は250nm、試料を窒素ガス流通下、100℃、30分間乾燥脱気した後、Macsorb HM-model1208(株式会社 MOUNTECH)を用いてBET1点連続法により求めた比表面積は11m2/gであり、X線回折の結晶構造解析(XRD)からLi4Ti5O12の単相を示した。微細な炭素繊維Aが網状に複合化されたリチウムチタン複合酸化物粒子を100kg/cm2Gに加圧し、直流抵抗計で測定したところ体積抵抗率は2×103Ω・cmであった。
実施例1と同一の二酸化チタン粒子と微細な炭素繊維AとBを用い、表1の条件で微細な炭素繊維の含有量および焼成条件を変化させて微細な炭素繊維で複合されたリチウムチタン酸複合酸化物粒子を製造し、実施例1と同一の方法でそれぞれの平均粒子径、比表面積、結晶構造解析、体積抵抗率を測定した。それらの調製条件と物性を表1に示す。
実施例1の微細な炭素繊維を添加せずに同様の方法でリチウムチタン複合酸化物粒子を調製し、実施例1と同一の方法で、平均粒子径、比表面積、XRD結晶構造解析、体積抵抗率を測定した。その結果を表1に示す。
(1)微細な炭素繊維水分散液の調製
微細な炭素繊維A5重量部を、カルボキシメチルセルロース(ダイセルファインケム(株)CMCダイセル1110)1重量部をイオン交換水94重量部に溶解した水溶液に添加、混合した後、超音波発生装置((株)日本精機製作所Ultrasonic Homogenizer MODEL US-600T)にて40分開繊、分散処理をおこない、微細な炭素繊維を5質量%含有する微細な炭素繊維水分散液を調製した。
(2)焼成用原料スラリーの調製とリチウムチタン複合酸化物粒子の製造
炭酸リチウム[Li2CO3:分子量73.8909](ケナメタル社製60M、平均一次粒子径5.3μm、比表面積1.4m2/g)38.0重量部(Li/Tiモル比0.82)をイオン交換水160重量部に攪拌混合、溶解した後、二酸化チタン粒子(実施例1で使用したものと同じ)100重量部を投入し、懸濁、スラリー化した。
微細な炭素繊維の代わりに炭素質前駆体のショ糖(スクロース)を用いた以外は実施例8と同様に炭素質と複合化したリチウムチタン複合酸化物を製造した。ショ糖5.59重量部(炭化率42質量%、総質量に対し2質量%)、炭酸リチウム38.0重量部(Li/Tiモル比0.82)をイオン交換水200重量部に溶解し、二酸化チタン粒子100重量部を懸濁、スラリー化し、噴霧乾燥、焼成した。得られたリチウムチタン複合酸化物粒子は、平均粒子径250nm、比表面積12m2/g、XRD結晶構造解析からLi4Ti5O12の単相を示した。体積抵抗率3×105Ω・cmを示した。
実施例8の二酸化チタンの代わりに平均一次粒子径21nmのアモルファス微粒子二酸化チタン(日本アエロジル(株)AEROXIDE TiO2P-25、平均一次粒子径30nm、比表面積50m2/g)を用いた以外は実施例8と同様な方法で微細な炭素繊維と複合化したリチウムチタン複合酸化物を製造した。炭酸リチウム38.0重量部(Li/Tiモル比0.82)をイオン交換水300重量部に攪拌混合、溶解した後、微粒子二酸化チタン100重量部を投入し、懸濁、スラリー化した。これに5質量%含有する微細な炭素繊維水分散液46.5重量部(総質量に対し2質量%)を添加、攪拌混合し、120℃で噴霧乾燥した後、窒素ガス雰囲気中775℃、90分の焼成を行った。微細な炭素繊維と複合されたリチウムチタン複合酸化物粒子は、平均粒子径100nm、比表面積21m2/g、XRD結晶構造解析からLi4Ti5O12の単相を示した。体積抵抗率9×103Ω・cmを示した。
実施例及び比較例で得られた電極材料をそれぞれ活物質として用い、該電極材料、アセチレンブラック(電気化学工業(株)デンカブラック)及びポリフッ化ビニリデン(PVDF)(クレハ(株)KFポリマー)を90:5:5の質量比でN-メチルピロリドンを溶媒としてニーダーで混練し、電極スラリーを作製した。アルミメッシュ基材に電極ペーストを塗布後、150℃で真空乾燥を行って、正極板(15mm□)を作製した。該正極板、対極としてLi板を、エチレンカーボネート(EC)とジメチルカーボネート(DMC)の1:2の溶媒にLiPF6を1mol/Lの濃度で溶解した電解液を含浸させたセパレーターを用いてコインセルを作製して、評価用非水電解質電池とした。
12 頭頂部
13 胴部
21、21a、21b、21c 集合体
Claims (21)
- リチウムチタン複合酸化物の内部および表面が微細な炭素繊維で網状に複合化されたことを特徴とする二次電池用電極材料。
- 前記リチウムチタン複合酸化物が、スピネル型構造Li4Ti5O12を主成分とし、平均粒子径が50nm以上1000nm未満、比表面積が1m2/g以上30m2/g以下であることを特徴とする、請求項1記載の二次電池用電極材料。
- 前記微細な炭素繊維の含有量が、総質量の0.1質量%以上、10質量%以下の量であることを特徴とする請求項1または2に記載の電極材料。
- 体積抵抗率が、10MPa/cm2の圧縮した状態において105Ω・cm未満である請求項1~3のいずれか1項に記載の電極材料。
- 前記微細な炭素繊維が、気相成長法により製造され、そのグラファイト網面が、閉じた頭頂部と、下部が開いた胴部とを有する構造単位を形成し、前記構造単位が、中心軸を共有して2~30個層状に積み重なって集合体を形成し、前記集合体が、Head-to-Tail様式で間隔をもって連結して繊維を形成していること特徴とする請求項1~4のいずれか1項に記載の二次電池用電極材料。
- 前記微細な炭素繊維において、繊維軸方向に対し15°より小さな角度で黒鉛AB面(黒鉛基底面)が配列したことを特徴とする請求項1~5のいずれか1項に記載の電極材料。
- 前記微細な炭素繊維において、前記集合体胴部の端の外径Dが5~40nm、内径dが3~30nmであり、該集合体のアスペクト比(L/D)が2~150であることを特徴とする請求項1~6のいずれか1項に記載の電極材料。
- 前記微細な炭素繊維が、Fe、Co、Ni、Al、MgおよびSiからなる群より選ばれる元素を含む触媒を用いた気相成長法により製造され、該微細な炭素繊維中の灰分が4重量%以下であることを特徴とする請求項1~7のいずれか1項に記載の電極材料。
- 前記微細な炭素繊維が、マグネシウムが置換固溶したコバルトのスピネル型酸化物を含む触媒上に、CO及びH2を含む混合ガスを供給して反応させ、微細な炭素繊維を成長させることにより製造されることを特徴とする請求項1~8のいずれか1項に記載の電極材料。
- 前記マグネシウムが置換固溶したコバルトのスピネル型酸化物を、MgxCo3-xOyで表したとき、マグネシウムの固溶範囲を示すxの値が、0.5~1.5であることを特徴とする請求項9に記載の電極材料。
- (工程a-1)微細な炭素繊維凝集体とチタン化合物とを剪断力を加えて混練し、開繊された微細な炭素繊維とチタン化合物との混合物を得る工程と、
(工程a-2)工程a-1で得られた混合物と、リチウム化合物とを混合する工程と、
(工程a-3)工程a-2で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。 - (工程b-1)微細な炭素繊維凝集体とチタン化合物とリチウム化合物とを、剪断力を加えて混練し、開繊された微細な炭素繊維とチタン化合物とリチウム化合物との混合物を得る工程と、
(工程b-2)工程b-1で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。 - (工程c-1)分散媒体中、微細な炭素繊維凝集体を、分散剤を用いて開繊および分散させる工程と、
(工程c-2)工程c-1で得られた開繊された微細な炭素繊維の分散液と、チタン化合物と、リチウム化合物とを混合する工程と
(工程c-3)工程c-2で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。 - (工程d-1)分散媒体とチタン化合物とリチウム化合物との混合物中、分散剤を用いて微細な炭素繊維凝集体を開繊および分散・混合させる工程と、
(工程d-2)工程d-1で得られた混合物を、不活性雰囲気中焼成する工程と、を含む二次電池用電極材料の製造方法。 - 前記チタン化合物が、その大きさが20nm以上、500nm未満の二酸化チタン粒子及び/又は水酸化チタン粒子であり、かつ、前記リチウム化合物が炭酸リチウム及び/又は水酸化リチウムであることを特徴とする請求項11~14のいずれか1項に記載の製造方法。
- 前記二酸化チタンが、アナターゼ型またはルチル型の酸化チタンであることを特徴とする、請求項15記載の製造方法。
- 前記水酸化チタンがメタチタン酸またはオルトチタン酸であることを特徴とする、請求項15記載の製造方法。
- 前記微細な炭素繊維凝集体が、気相成長法により製造され、該凝集体を構成する微細な炭素繊維のグラファイト網面が、閉じた頭頂部と、下部が開いた胴部とを有する構造単位を形成し、前記構造単位が、中心軸を共有して2~30個層状に積み重なって集合体を形成し、前記集合体が、Head-to-Tail様式で間隔をもって連結して繊維を形成していることを特徴とする請求項11~17のいずれか1項に記載の製造方法。
- 前記分散剤が、カルボキシメチルセルロースまたはポリビニルピロリドンであることを特徴とする請求項13~18のいずれか1項に記載の製造方法。
- 前記分散媒体が、極性有機溶媒を含むことを特徴とする請求項13~19のいずれか1項に記載の製造方法。
- 前記焼成する温度が550℃以上、950℃未満であることを特徴とする、請求項11~20のいずれか1項に記載の製造方法。
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EP11820007.0A EP2610950B1 (en) | 2010-08-26 | 2011-08-25 | Lithium-titanium composite oxide electrode material conjugated with fine carbon fibers |
KR1020137007500A KR20130103730A (ko) | 2010-08-26 | 2011-08-25 | 미세한 탄소 섬유와 복합화된 리튬티탄 복합 산화물 전극 재료 |
US13/818,767 US9190660B2 (en) | 2010-08-26 | 2011-08-25 | Lithium—titanium complex oxide electrode material conjugated with fine carbon fiber |
CN201180051672.XA CN103181004B (zh) | 2010-08-26 | 2011-08-25 | 复合有细碳纤维的锂钛复合氧化物电极材料 |
RU2013113232/04A RU2013113232A (ru) | 2010-08-26 | 2011-08-25 | Электродный материал из сложного литий-титан оксида, соединенного с тонким углеродным волокном |
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JP2010189907A JP5672859B2 (ja) | 2010-08-26 | 2010-08-26 | 微細な炭素繊維と複合化されたリチウムチタン複合酸化物電極材料 |
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EP (1) | EP2610950B1 (ja) |
JP (1) | JP5672859B2 (ja) |
KR (1) | KR20130103730A (ja) |
CN (1) | CN103181004B (ja) |
RU (1) | RU2013113232A (ja) |
TW (1) | TW201230476A (ja) |
WO (1) | WO2012026544A1 (ja) |
Cited By (2)
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RU2522887C2 (ru) * | 2012-09-05 | 2014-07-20 | Федеральное государственное бюджетное учреждение науки Институт нанотехнологий микроэлектроники Российской академии наук | Способ формирования электропроводящих слоев на основе углеродных нанотрубок |
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005135872A (ja) * | 2003-10-31 | 2005-05-26 | Hitachi Maxell Ltd | 非水二次電池の電極材料およびその製造方法、並びにそれを用いた非水二次電池 |
JP2006164859A (ja) * | 2004-12-10 | 2006-06-22 | Shin Kobe Electric Mach Co Ltd | リチウム二次電池用正極材料とその製造法及びリチウム二次電池 |
JP2006221881A (ja) * | 2005-02-08 | 2006-08-24 | Gs Yuasa Corporation:Kk | 非水電解質電池用活物質及びその製造方法、並びに、非水電解質電池用電極及び非水電解質電池 |
JP2007160151A (ja) * | 2005-12-09 | 2007-06-28 | K & W Ltd | 反応方法及びこの方法で得られた金属酸化物ナノ粒子、またはこの金属酸化物ナノ粒子を担持したカーボン及びこのカーボンを含有する電極、並びにこれを用いた電気化学素子。 |
WO2009081704A1 (ja) * | 2007-12-25 | 2009-07-02 | Kao Corporation | リチウム電池正極用複合材料 |
WO2009110570A1 (ja) * | 2008-03-06 | 2009-09-11 | 宇部興産株式会社 | 微細な炭素繊維、微細な炭素短繊維およびそれらの製造方法 |
WO2011078112A1 (ja) * | 2009-12-22 | 2011-06-30 | 石原産業株式会社 | チタン酸リチウム、該チタン酸リチウムの製造方法、該製造方法に用いるスラリー、該チタン酸リチウムを含む電極活物質及び該電極活物質を用いたリチウム二次電池 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3625680B2 (ja) | 1999-03-25 | 2005-03-02 | 三洋電機株式会社 | リチウム二次電池 |
JP4667071B2 (ja) * | 2004-03-30 | 2011-04-06 | 三洋電機株式会社 | 非水電解質二次電池 |
US7879493B2 (en) | 2006-06-05 | 2011-02-01 | A123 Systems, Inc. | Alkali metal titanates and methods for their synthesis |
JP2009238656A (ja) | 2008-03-28 | 2009-10-15 | Gs Yuasa Corporation | 非水電解質電池用活物質及びそれを備えた非水電解質電池 |
CN101630732B (zh) | 2009-07-27 | 2011-12-28 | 深圳市德方纳米科技有限公司 | 纳米钛酸锂复合物及其制备方法 |
CN101752560B (zh) * | 2010-01-13 | 2011-10-19 | 北京大学 | 钛酸锂-碳复合纳米材料及其制备方法与应用 |
CN101777645B (zh) | 2010-02-10 | 2012-08-22 | 赵县强能电源有限公司 | 一种碳改性钛酸锂的制备方法 |
EP2554517B1 (en) | 2010-03-31 | 2017-08-02 | Nippon Chemi-Con Corporation | Composite of lithium titanate nanoparticles and carbon, electrode containing said electrode material, electrochemical capacitor and method for producing said composite |
-
2010
- 2010-08-26 JP JP2010189907A patent/JP5672859B2/ja not_active Expired - Fee Related
-
2011
- 2011-08-25 RU RU2013113232/04A patent/RU2013113232A/ru not_active Application Discontinuation
- 2011-08-25 KR KR1020137007500A patent/KR20130103730A/ko not_active Application Discontinuation
- 2011-08-25 EP EP11820007.0A patent/EP2610950B1/en not_active Not-in-force
- 2011-08-25 CN CN201180051672.XA patent/CN103181004B/zh not_active Expired - Fee Related
- 2011-08-25 US US13/818,767 patent/US9190660B2/en not_active Expired - Fee Related
- 2011-08-25 WO PCT/JP2011/069216 patent/WO2012026544A1/ja active Application Filing
- 2011-08-26 TW TW100130665A patent/TW201230476A/zh unknown
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005135872A (ja) * | 2003-10-31 | 2005-05-26 | Hitachi Maxell Ltd | 非水二次電池の電極材料およびその製造方法、並びにそれを用いた非水二次電池 |
JP2006164859A (ja) * | 2004-12-10 | 2006-06-22 | Shin Kobe Electric Mach Co Ltd | リチウム二次電池用正極材料とその製造法及びリチウム二次電池 |
JP2006221881A (ja) * | 2005-02-08 | 2006-08-24 | Gs Yuasa Corporation:Kk | 非水電解質電池用活物質及びその製造方法、並びに、非水電解質電池用電極及び非水電解質電池 |
JP2007160151A (ja) * | 2005-12-09 | 2007-06-28 | K & W Ltd | 反応方法及びこの方法で得られた金属酸化物ナノ粒子、またはこの金属酸化物ナノ粒子を担持したカーボン及びこのカーボンを含有する電極、並びにこれを用いた電気化学素子。 |
WO2009081704A1 (ja) * | 2007-12-25 | 2009-07-02 | Kao Corporation | リチウム電池正極用複合材料 |
WO2009110570A1 (ja) * | 2008-03-06 | 2009-09-11 | 宇部興産株式会社 | 微細な炭素繊維、微細な炭素短繊維およびそれらの製造方法 |
WO2011078112A1 (ja) * | 2009-12-22 | 2011-06-30 | 石原産業株式会社 | チタン酸リチウム、該チタン酸リチウムの製造方法、該製造方法に用いるスラリー、該チタン酸リチウムを含む電極活物質及び該電極活物質を用いたリチウム二次電池 |
Non-Patent Citations (2)
Title |
---|
KATSUHIKO NAOI ET AL.: "High-rate nano-crystalline Li4Ti5O12 attached on carbon nano-fibers for hybrid supercapacitors", JOURNAL OF POWER SOURCES, vol. 195, 13 January 2010 (2010-01-13), pages 6250 - 6254, XP027148175 * |
See also references of EP2610950A4 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
RU2522887C2 (ru) * | 2012-09-05 | 2014-07-20 | Федеральное государственное бюджетное учреждение науки Институт нанотехнологий микроэлектроники Российской академии наук | Способ формирования электропроводящих слоев на основе углеродных нанотрубок |
JP2018181750A (ja) * | 2017-04-20 | 2018-11-15 | トヨタ自動車株式会社 | 全固体電池 |
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CN103181004A (zh) | 2013-06-26 |
EP2610950A4 (en) | 2014-08-13 |
JP5672859B2 (ja) | 2015-02-18 |
US20130149612A1 (en) | 2013-06-13 |
US9190660B2 (en) | 2015-11-17 |
JP2012048963A (ja) | 2012-03-08 |
TW201230476A (en) | 2012-07-16 |
KR20130103730A (ko) | 2013-09-24 |
CN103181004B (zh) | 2015-08-19 |
EP2610950A1 (en) | 2013-07-03 |
EP2610950B1 (en) | 2015-09-23 |
RU2013113232A (ru) | 2014-10-10 |
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