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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery.
• Lithium-ion secondary batteries are lighter and have higher input / output characteristics than other secondary batteries such as nickel metal hydride batteries and lead-acid batteries, so in recent years high-input / output used in electric vehicles, hybrid electric vehicles, etc. It is attracting attention as a power source. Since the lithium ion secondary battery was commercialized in 1991, it is still strongly desired to increase its energy density and further improve the input / output characteristics. As a means for that, a technique for improving a negative electrode material included in a negative electrode of a lithium ion secondary battery occupies an important position (see, for example, Patent Document 1 and Patent Document 2).
• JP-A-4-370662 Japanese Patent Laid-Open No. 5-307956
• carbon materials such as graphite and amorphous carbon are widely used.
• Graphite has a structure in which hexagonal network surfaces of carbon atoms are regularly stacked. Lithium ion insertion / extraction reactions proceed from the ends of the stacked network surfaces to charge and discharge.
• amorphous carbon has irregular hexagonal network stacks or no network structure, lithium ion insertion / desorption reaction proceeds on the entire surface, and has excellent input / output characteristics. Lithium ions are easily obtained.
• amorphous carbon has characteristics such as low crystallinity, low reaction with the electrolytic solution, and excellent life characteristics.
• Graphite cannot be said to have sufficient input / output performance because the insertion / release reaction of lithium ions proceeds only at the edges.
• the crystallinity is high and the surface reactivity is high, the reactivity with the electrolytic solution may be high particularly at high temperatures, and there is room for improvement in terms of the life characteristics of the lithium ion secondary battery.
• amorphous carbon has lower crystallinity than graphite, the crystal structure is irregular and the energy density is not sufficient.
• the present invention relates to a negative electrode material for a lithium ion secondary battery and a negative electrode for a lithium ion secondary battery capable of producing a lithium ion secondary battery excellent in input / output characteristics and life characteristics while maintaining high charge / discharge efficiency, and It aims at providing the lithium ion secondary battery manufactured using.
• Means for solving the above problems include the following embodiments. ⁇ 1>
• the average spacing d 002 determined by X-ray diffractometry is 0.335 nm ⁇ 0.339 nm
• specific surface area determined from nitrogen adsorption measurements at 77K is 0.5m 2 /g ⁇ 6.0m 2 / a negative electrode material for a lithium ion secondary battery, comprising a carbon material satisfying the following (1) and (2): (1)
• the particle size distribution based on the number the particle diameter when the difference relative particle amount q0 is the mode value is 11.601 ⁇ m or less.
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• the average interplanar distance d 002 obtained by the X-ray diffraction method is 0.335 nm to 0.339 nm
• the R value of Raman spectroscopic measurement is 0.1 to 1.0
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• the average interplanar distance d 002 obtained by X-ray diffraction method is 0.335 nm to 0.339 nm, and is arranged on at least a part of the surface of the first carbon phase serving as a nucleus and the first carbon phase. And a second carbon phase different from the first carbon phase, and a carbon material satisfying the following (1) and (2): a negative electrode material for a lithium ion secondary battery.
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• the integrated value Q3 when the particle diameter is 9.516 ⁇ m is 4.0% or more of the total carbon material.
• the carbon material has a particle diameter (50% D) of 1 ⁇ m to 20 ⁇ m when the accumulation is 50% when a volume cumulative distribution curve is drawn from the small particle diameter side.
• the negative electrode material for a lithium ion secondary battery according to any one of ⁇ 1> to ⁇ 4>.
• the carbon material has a particle diameter (99.9% D) when the accumulation is 99.9% when a volume cumulative distribution curve is drawn from the small particle diameter side.
• ⁇ 7> The negative electrode material for a lithium ion secondary battery according to any one of ⁇ 1> to ⁇ 6>, wherein the carbon material has a tap density of 0.90 g / cm 3 to 2.00 g / cm 3 .
• ⁇ 8> The negative electrode material for a lithium ion secondary battery according to any one of ⁇ 1> to ⁇ 7>, wherein the carbon material has a pellet density of 1.55 g / cm 3 or less.
• a negative electrode for a lithium ion secondary battery comprising a negative electrode material layer comprising the negative electrode material for a lithium ion secondary battery according to any one of ⁇ 1> to ⁇ 8>, and a current collector.
• a lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to ⁇ 9>, a positive electrode, and an electrolyte.
• a negative electrode material for a lithium ion secondary battery and a negative electrode for a lithium ion secondary battery capable of producing a lithium ion secondary battery excellent in input / output characteristics and life characteristics while maintaining high charge / discharge efficiency is provided.
• the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
• numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
• the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. Good. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
• the content rate or content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of kinds present in the composition unless otherwise specified. It means the total content or content of substances.
• the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
• the term “layer” or “film” refers to a part of the region in addition to the case where the layer or the film is formed when the region where the layer or film exists is observed. It is also included when it is formed only.
• the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.
• the negative electrode material for a lithium ion secondary battery of the present embodiment (hereinafter sometimes simply referred to as “negative electrode material”) has an average interplanar distance d 002 obtained by X-ray diffraction method of 0.335 nm to 0.339 nm.
• the specific surface area determined from nitrogen adsorption measurements at 77K is the 0.5m 2 /g ⁇ 6.0m 2 / g, and containing a carbon material satisfying the following (1) and (2).
• the particle size distribution based on the number the particle diameter when the difference relative particle amount q0 is the mode value is 11.601 ⁇ m or less.
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• the composition of the negative electrode material of the present embodiment is not particularly limited as long as it includes a carbon material that satisfies the above-described conditions. From the viewpoint of obtaining the effect of the present embodiment, the proportion of the carbon material in the entire negative electrode material is preferably 50% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. Further preferred is 100% by mass.
• the average interplanar spacing d 002 obtained from the X-ray diffraction method of the carbon material is 0.335 nm to 0.339 nm.
• 0.3354 nm is a theoretical value of the graphite crystal, and the energy density tends to increase as the value is closer to this value.
• excellent initial charge / discharge efficiency and energy density of the lithium ion secondary battery tend to be obtained.
• the average value of the interplanar spacing d 002 of the carbon material is preferably small from the viewpoint of the energy density of the lithium ion secondary battery. Specifically, for example, it is preferably 0.335 nm to 0.337 nm.
• the value of the average spacing d 002 of the carbon material for example, because there tends to be smaller by increasing the temperature of the heat treatment performed on the carbon material, the average plane spacing d 002 By utilizing this property the range Can be adjusted to.
• the specific surface area determined from nitrogen adsorption measurements at 77K carbon material (hereinafter sometimes referred to as N 2 specific surface area) is 0.5m 2 /g ⁇ 6.0m 2 / g.
• N 2 specific surface area of the carbon material is within the above range, the balance between the input / output characteristics and the initial efficiency tends to be well maintained.
• the N 2 specific surface area of the carbon material can be determined by using the BET method from the adsorption isotherm obtained from the nitrogen adsorption measurement at 77K.
• N 2 specific surface area is 1.0m 2 /g ⁇ 5.0m 2 / g.
• the N 2 specific surface area tends to be reduced by a method such as increasing the volume average particle diameter of the carbon material, increasing the temperature of the heat treatment performed on the carbon material, or modifying the surface of the carbon material. Therefore, the N 2 specific surface area can be set within the above range using this property.
• the carbon material has a particle diameter of 11.601 ⁇ m or less when the difference relative particle amount q0 is the mode value in the number-based particle size distribution.
• the particle diameter at which the difference relative particle quantity q0 is the mode value exceeds 11.601 ⁇ m, the proportion of the carbon material having a large particle diameter increases, so that the diffusion distance of lithium ions from the surface of the carbon material particle to the inside is increased. It becomes longer and the input / output characteristics of the lithium ion secondary battery tend to deteriorate.
• the particle diameter at which the relative particle amount q0 of the difference becomes the mode value is preferably 11.601 ⁇ m or 9.516 ⁇ m, and more preferably 11.601 ⁇ m.
• the carbon material preferably has a total value of the difference relative particle amount q0 when the particle diameter is 11.601 ⁇ m and the difference relative particle amount q0 when the particle diameter is 9.516 ⁇ m being 25 or more, and 30 or more. More preferably, it is more preferably 32 or more.
• the carbon material has a ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m. 1.20 to 3.00. If the value of q0A / q0B is less than 1.20, the input / output characteristics tend to deteriorate. When the value of q0A / q0B exceeds 3.00, the contact between the particles of the carbon material is deteriorated, and the life characteristics of the lithium ion secondary battery tend to be deteriorated. From the viewpoint of input / output characteristics and life characteristics, the value of q0A / q0B is preferably in the range of 1.20 to 2.20, and more preferably in the range of 1.25 to 2.10.
• the total value of the relative particle amount q0 for each particle diameter in the range of 0.1 ⁇ m to 2000 ⁇ m is 100.
• Table 1 also shows the value of the relative particle amount q0 of the difference in terms of the number of carbon materials used in Example 2 and the particle diameter.
• the integrated value Q3 when the particle diameter is 9.516 ⁇ m is 4.0% or more of the whole. Preferably, it is 9.0% or more.
• the integrated value Q3 when the particle diameter is 9.516 ⁇ m is 4.0% or more of the whole, the contact points between the particles are sufficiently secured by the fine particles contained in the carbon material, and the lithium ion secondary battery There is a tendency for the life characteristics of to improve.
• the upper limit of the integrated value Q3 is not particularly limited, but is preferably 30% or less, and more preferably 20% or less.
• the carbon material has a particle size distribution (50% D, hereinafter also referred to as a volume average particle size) when the cumulative volume distribution distribution curve is drawn from the small particle size side in the volume-based particle size distribution.
• a particle size distribution 50% D, hereinafter also referred to as a volume average particle size
• the volume average particle diameter of the carbon material is 1 ⁇ m or more, the specific surface area is too large, and the initial charge / discharge efficiency of the lithium ion secondary battery tends to be suppressed from decreasing.
• the volume average particle diameter of the carbon material is 20 ⁇ m or less, the particle diameter is too large, the diffusion distance of Li from the particle surface to the inside becomes long, and the input / output characteristics of the lithium ion secondary battery may be deteriorated. It tends to be suppressed.
• the carbon material has a particle diameter (99.9% D, hereinafter referred to as the maximum particle diameter) when the accumulation is 99.9% when a volume cumulative distribution curve is drawn from the small particle diameter side in the volume-based particle size distribution.
• the maximum particle diameter of the carbon material is 63 ⁇ m or less, more preferably 50 ⁇ m or less, and even more preferably 45 ⁇ m or less.
• the volume-based particle size distribution of the carbon material is obtained by dividing the range of 0.1 ⁇ m to 2000 ⁇ m into 50 logarithmic ratios in the same manner as the number-based particle size distribution.
• the volume-based particle size distribution can be measured by the same method as the number-based particle size distribution.
• the particle size distribution of the carbon material can be measured by a known method.
• a dispersion prepared by dispersing a sample of a carbon material in purified water together with a surfactant is placed in a sample water tank of a laser diffraction particle size distribution analyzer, and ultrasonically applied for 1 minute while circulating with a pump. It can be obtained by measuring with a laser diffraction method under the measurement conditions.
• a laser diffraction particle size distribution measuring apparatus for example, “SALD-3000J” manufactured by Shimadzu Corporation can be used.
• “number” or “volume” as the output condition a number-based particle size distribution or a volume-based particle size distribution can be obtained.
• the carbon material of this embodiment can be obtained, for example, by combining two or more carbon materials having different particle diameters.
• a combination of such carbon materials a combination of a carbon material having a volume average particle diameter of 8 ⁇ m to 12 ⁇ m and a carbon material having a volume average particle diameter of 14 ⁇ m to 18 ⁇ m, a carbon material having a volume average particle diameter of 9 ⁇ m to 11 ⁇ m, and a volume average Examples thereof include a combination of carbon materials having a particle size of 15 ⁇ m to 17 ⁇ m.
• Examples of the ratio when two kinds of carbon materials having different particle diameters are combined include a mass ratio in the range of 7: 3 to 3: 7, a mass ratio in the range of 6: 4 to 4: 6, and the like.
• Carbon materials more preferably tap density is preferably 0.90g / cm 3 ⁇ 2.00g / cm 3, a 1.00g / cm 3 ⁇ 1.50g / cm 3, 1.05g / More preferably, it is cm 3 to 1.30 g / cm 3 .
• the tap density of the carbon material is 0.90 g / cm 3 or more, the amount of organic substances such as a binder used for producing the negative electrode can be reduced, and the energy density of the lithium ion secondary battery tends to increase.
• the tap density of the carbon material is 2.00 g / cm 3 or less, the input / output characteristics tend to be good.
• the tap density of the carbon material tends to increase its value, for example, by increasing the volume average particle diameter of the carbon material.
• the tap density can be set within the above range using this property.
• the total tap density of the negative electrode material including the carbon material may be 0.90 g / cm 3 to 3.00 g / cm 3 .
• Examples of a method for adjusting the tap density of the negative electrode material include a method of containing a metal component and the like described later in addition to the carbon material.
• the tap density of the carbon material or negative electrode material herein slowly charged sample powder 100 cm 3 graduated cylinder volume 100 cm 3, and the stoppered graduated cylinder causes the graduated cylinder from a height of 5cm dropped 250 times Means a value (g / cm 3 ) obtained by dividing the mass (g) of the sample powder after being divided by the volume (cm 3 ).
• Carbon material is preferably pellet density of 1.55 g / cm 3 or less, more preferably 1.50 g / cm 3 or less. If the pellet density is 1.55 g / cm 3 or less, when the electrode is densified, voids between the particles of the carbon material become too small and the ion concentration in the vicinity of the particles decreases, and the lithium ion secondary battery is inserted. It tends to be suppressed that the output characteristics are deteriorated.
• the pellet density of the carbon material tends to be lowered by, for example, reducing the volume average particle diameter of the carbon material, and the pellet density can be set within the above range by utilizing this property.
• Pellet density of the entire negative electrode material containing a carbon material may be 1.10g / cm 3 ⁇ 2.00g / cm 3.
• a method of adjusting the pellet density of the negative electrode material a method of controlling the temperature of the heat treatment performed on the carbon material can be mentioned.
• the pellet density of the carbon material or the negative electrode material is the thickness (cm) and the cross-sectional area of the sample after putting 1.00 g of the sample powder into the molding machine and pressurizing with a hydraulic press at a pressure of 1.0 t ( The value obtained by dividing the mass (g) by the volume obtained from (cm 2 ) and (g / cm 3 ).
• the carbon material preferably has an R value measured by Raman spectroscopy of 0.1 to 1.0, more preferably 0.2 to 0.8, and further preferably 0.3 to 0.7. preferable.
• R value measured by Raman spectroscopy of 0.1 to 1.0, more preferably 0.2 to 0.8, and further preferably 0.3 to 0.7. preferable.
• the R value is 0.1 or more, there are sufficient graphite lattice defects used for insertion and desorption of lithium ions, and the input / output characteristics are likely to be prevented from deteriorating.
• the R value is 1.0 or less, the decomposition reaction of the electrolytic solution is sufficiently suppressed, and the decrease in the initial efficiency tends to be suppressed.
• the peak appearing near 1580 cm -1 generally a peak identified as corresponding to the graphite crystal structure, means a peak observed in the example 1530cm -1 ⁇ 1630cm -1.
• the peak appearing in the vicinity of 1360 cm ⁇ 1 is usually a peak identified as corresponding to the amorphous structure of carbon, for example, a peak observed at 1300 cm ⁇ 1 to 1400 cm ⁇ 1 .
• Raman spectroscopic measurement is performed using a laser Raman spectrophotometer (model number: NRS-1000, JASCO Corporation), and an argon laser on a sample plate in which a negative electrode material for a lithium ion secondary battery is set flat. Measurement is performed by irradiation with light (excitation wavelength: 532 nm).
• the carbon material examples include carbon materials such as graphite (artificial graphite, natural graphite, graphitized mesophase carbon, graphitized carbon fiber, etc.), low crystalline carbon, and mesophase carbon. From the viewpoint of increasing the charge / discharge capacity, it is preferable that at least a part of the carbon material is graphite.
• the shape of the carbon material is not particularly limited. For example, a scale shape, a spherical shape, a lump shape, etc. are mentioned. From the viewpoint of obtaining a high tap density, a spherical shape is preferable.
• a carbon material having the above-described physical properties may be appropriately selected from these carbon materials.
• a carbon material may be used individually by 1 type, or may be used in combination of 2 or more types from which a material, a shape, etc. differ.
• the carbon material is a composite material including a first carbon phase serving as a nucleus and a second carbon phase different from the first carbon phase disposed on at least a part of the surface of the carbon material (for example, covering the nucleus). It may be. By constituting the carbon material from a plurality of different carbon phases, a carbon material that can more effectively exhibit the desired physical properties or properties can be obtained.
• the carbon material is a composite material including a first carbon phase serving as a nucleus and a second carbon phase disposed on at least a part of the surface thereof, a combination of the first carbon phase and the second carbon phase As a combination of a first carbon phase and a second carbon phase different in crystallinity from the first carbon phase, and the first carbon phase is less crystalline than the first carbon phase ( A combination of second carbon phases (d 002 value greater than the first carbon phase) is preferred.
• the carbon material is a composite material including a first carbon phase serving as a nucleus and a second carbon phase having lower crystallinity than the first carbon phase
• the material of the first carbon phase serving as a nucleus is It is preferable to select from the above-mentioned graphite.
• the second carbon phase is preferably selected from those having lower crystallinity than the first carbon phase (hereinafter also referred to as a low crystalline carbon phase).
• the material of the second carbon phase which is lower in crystallinity than the first carbon phase, is not particularly limited, and is appropriately selected according to desired properties.
• Preferable examples of the second carbon phase include a carbon phase obtained from an organic compound (carbon precursor) that can be changed to carbon by heat treatment.
• ethylene heavy end pitch, crude oil pitch, coal tar pitch, asphalt cracking pitch, pitch produced by pyrolyzing organic compounds such as polyvinyl chloride, and naphthalene are polymerized in the presence of super strong acid.
• the synthesized pitch is mentioned.
• thermoplastic synthetic polymers such as polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, and polyvinyl butyral, and natural polymers such as starch and cellulose can be used as the carbon precursor.
• the core first carbon phase is a graphite material having an average interplanar spacing d 002 in the range of 0.335 nm to 0.339 nm.
• the charge / discharge capacity is as large as 330 mAh / g to 370 mAh / g and good lithium ion Secondary batteries tend to be obtained.
• the graphite material to be the first carbon phase preferably has a volume average particle diameter (50% D) of 1 ⁇ m to 20 ⁇ m.
• a volume average particle diameter of the graphite material is 1 ⁇ m or more, fine powder is contained in the raw material graphite in an appropriate amount, and the occurrence of aggregation in the step of attaching the organic compound as the carbon precursor to the core material is suppressed, Both tend to be mixed more evenly.
• the volume average particle diameter of the graphite material is 20 ⁇ m or less, the mixture of coarse particles in the negative electrode material is suppressed, and the occurrence of stringing or the like tends to be suppressed when the negative electrode material is applied.
• the graphite material to be the first carbon phase preferably has a specific surface area determined by nitrogen adsorption measurement at 77 K, that is, a BET specific surface area (N 2 specific surface area) of 0.1 m 2 / g to 30 m 2 / g. 0.5 m 2 / g to 25 m 2 / g is more preferable, and 0.5 m 2 / g to 15 m 2 / g is still more preferable.
• N 2 specific surface area of the graphite material is 0.1 m 2 / g or more, aggregation tends to hardly occur in the step of attaching an organic compound as a carbon precursor to the core material.
• the N 2 specific surface area of the graphite material is 30 m 2 / g or less, the specific surface area is maintained in an appropriate range, and the organic compound tends to adhere more evenly.
• Examples of the shape of the graphite material used as the first carbon phase include scaly, spherical, and massive shapes, and a spherical shape is preferable from the viewpoint of increasing the tap density.
• the aspect ratio of the graphite material is a value obtained by “maximum length vertical length / maximum length”, and the maximum value is 1.
• the “maximum length” is the maximum value of the distance between two points on the contour line of the graphite material particles
• the “maximum length vertical length” is perpendicular to the line segment connecting the two points that is the maximum length. It is the length of the longest line segment connecting two points on the particle outline.
• the aspect ratio of the graphite material can be measured using, for example, a flow type particle image analyzer. Examples of the flow type particle image analyzer include “FPIA-3000” manufactured by Sysmex Corporation.
• the graphite material to be the first carbon phase preferably has an average aspect ratio of 0.1 or more, and more preferably 0.3 or more.
• the average aspect ratio of the graphite material is 0.1 or more, the ratio of flake graphite in the graphite material is not too high, and the amount of the edge surface of the graphite material can be suppressed within an appropriate range. Since the edge surface is more active than the basal surface, there is a concern that more organic compounds will adhere to the edge surface in the step of attaching the organic compound as the carbon precursor to the core material, but the average aspect ratio is If it is 0.1 or more, the organic compound tends to adhere to the core material more evenly. As a result, the distribution of low crystalline carbon and crystalline carbon in the obtained carbon material tends to be more uniform.
• the negative electrode material may contain other components as required in addition to the carbon material.
• a metal component may be included.
• a metal powder made of an element that forms an alloy with lithium such as Al, Si, Ga, Ge, In, Sn, Sb, and Ag, Al, Si, Ga
• examples thereof include a powder of a multi-component alloy containing at least an element that forms an alloy with lithium, such as Ge, In, Sn, Sb, and Ag, and a powder of a lithium alloy.
• a metal component may be used individually by 1 type, or may be used in combination of 2 or more type.
• a metal component may be added separately from a carbon material, or may be added in the state compounded with the carbon material.
• the tap density of the whole negative electrode material tends to increase as compared with the case where only the carbon material is contained.
• the tap density of the entire negative electrode material can be 0.3 g / cm 3 to 3.0 g / cm 3 .
• the amount is not particularly limited.
• the amount may be 1% by mass to 50% by mass of the whole negative electrode material.
• the negative electrode material for a lithium ion secondary battery of this embodiment has an average interplanar distance d 002 determined by X-ray diffraction method of 0.335 nm to 0.339 nm, and an R value of Raman spectroscopic measurement of 0.1 to 1. And a carbon material satisfying the following (1) and (2).
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• the negative electrode material for a lithium ion secondary battery of this embodiment has an average interplanar spacing d 002 obtained by an X-ray diffraction method of 0.335 nm to 0.339 nm, the first carbon phase serving as a nucleus, and the first carbon And a second carbon phase different from the first carbon phase disposed on at least a part of the surface of the carbon phase, and a carbon material satisfying the following (1) and (2).
• the ratio (q0A / q0B) of the difference relative particle amount q0A when the particle size is 11.601 ⁇ m and the difference relative particle amount q0B when the particle size is 7.806 ⁇ m is 1 20 to 3.00.
• examples of the production method include a carbon precursor and There is a method in which an organic compound to be deposited is attached to the surface of a core material to be a first carbon phase and then baked in an inert atmosphere at 750 ° C. to 1200 ° C. to carbonize the carbon precursor.
• examples of the organic compound used as the carbon precursor include the organic compounds described above as examples of the carbon precursor.
• the method for attaching the carbon precursor to the surface of the first carbon phase is not particularly limited.
• a wet method that removes the solvent after mixing the core material that becomes the first carbon phase in a liquid in which the carbon precursor is dissolved or dispersed in a solvent, and the core material and the carbon precursor are mixed in a solid state.
• Examples include a dry method in which mechanical energy is applied to the obtained mixture and a vapor phase method such as a CVD method. From the viewpoint of controlling the specific surface area of the carbon material, it is preferably carried out by a dry method.
• the method of attaching the carbon precursor to the surface of the first carbon phase by a dry method is not particularly limited.
• the mixture of the first carbon and the carbon precursor is filled in a container having a structure capable of at least one of mixing and stirring the contents, and at least one of mixing and stirring is performed while applying mechanical energy.
• the magnitude of the mechanical energy applied to the mixture is not particularly limited.
• it is preferably 0.360 kJ / kg to 36000 kJ / kg, more preferably 0.360 kJ / kg to 7200 kJ / kg, and even more preferably 2.50 kJ / kg to 2000 kJ / kg.
• the mechanical energy applied to the mixture is a value obtained by dividing the value obtained by multiplying the load (kW) by time (h) by the mass (kg) of the filled mixture.
• the product after the carbon precursor is attached to the surface of the first carbon phase (intermediate product) is further heated and fired.
• the firing temperature is not particularly limited as long as the carbon precursor can be carbonized.
• the temperature is preferably 750 ° C. to 2000 ° C., more preferably 800 ° C. to 1800 ° C., and further preferably 900 ° C. to 1400 ° C.
• the firing temperature is 750 ° C. or higher, the charge / discharge efficiency, input / output characteristics and cycle characteristics of the lithium ion secondary battery tend to be maintained well, and when the firing temperature is 2000 ° C. or lower, the low crystalline carbon It tends to be suppressed that the crystallinity of the portion becomes too high.
• the atmosphere during firing is not particularly limited as long as the intermediate product is not easily oxidized.
• a nitrogen gas atmosphere, an argon gas atmosphere, a self-decomposition gas atmosphere, or the like can be applied.
• the type of furnace used for firing is not particularly limited. For example, a batch furnace or a continuous furnace using at least one of electricity and gas as a heat source is preferable.
• the negative electrode for a lithium ion secondary battery of the present embodiment includes a negative electrode material layer including the negative electrode material described above, and a current collector. This makes it possible to configure a lithium ion secondary battery that is excellent in input / output characteristics and life characteristics while maintaining high charge / discharge efficiency.
• the negative electrode for a lithium ion secondary battery may include other components as necessary in addition to the negative electrode material layer and the current collector including the negative electrode material described above.
• the method for producing a negative electrode for a lithium ion secondary battery is not particularly limited.
• a negative electrode material and an organic binder are mixed with a solvent using a dispersing device such as a stirrer, a ball mill, a super sand mill, a pressure kneader to prepare a slurry-like negative electrode composition, which is the surface of the current collector
• a dispersing device such as a stirrer, a ball mill, a super sand mill, a pressure kneader
• a paste-like negative electrode composition shape it into a sheet shape, pellet shape, etc., and integrate this with a current collector, etc. Can be mentioned.
• the organic binder is not particularly limited.
• ethylenically unsaturated carboxylic acid ester such as styrene-butadiene copolymer, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxyethyl (meth) acrylate, acrylic acid ,
• High molecular compounds with high ionic conductivity such as ethylenically unsaturated carboxylic acids such as methacrylic acid, itaconic acid, fumaric acid, maleic acid, polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, etc.
• Etc. (Meth) acrylate represents at least one of acrylate and methacrylate.
• the amount of the organic binder contained in the negative electrode composition is not particularly limited, but is preferably 0.5 parts by mass to 20 parts by mass with respect to 100 parts by mass in total of the negative electrode material and the organic binder.
• the negative electrode composition may contain a thickener for adjusting the viscosity.
• a thickener for adjusting the viscosity.
• the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein.
• the negative electrode composition may contain a conductive auxiliary material.
• the conductive auxiliary material include carbon materials such as carbon black, graphite, and acetylene black, as well as oxides and nitrides that exhibit conductivity.
• the amount of the conductive auxiliary agent is not particularly limited, but may be about 0.5% by mass to 15% by mass with respect to 100 parts by mass of the negative electrode material. *
• the material and shape of the current collector are not particularly limited.
• metal materials such as aluminum, copper, nickel, titanium, stainless steel, foil shape, perforated foil shape, mesh shape, etc.
• porous materials such as porous metal (foamed metal), carbon paper, and the like can be used.
• the method for applying the negative electrode composition to the current collector is not particularly limited. Examples thereof include coating methods such as a metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, comma coating method, gravure coating method, and screen printing method.
• coating methods such as a metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, comma coating method, gravure coating method, and screen printing method.
• the negative electrode composition is dried by a hot air dryer, an infrared dryer or a dryer combining these in order to remove the solvent contained in the negative electrode composition. Further, a rolling process using a flat plate press, a calendar roll or the like is performed as necessary.
• the method of forming the negative electrode material composition into a sheet shape, a pellet shape or the like and integrating it with the current collector is not particularly limited. For example, it can be performed by a known method using a roll, a press, or a combination thereof.
• the pressure at the time of integration is preferably about 1 MPa to 200 MPa.
• the negative electrode density of the negative electrode for a lithium ion secondary battery is preferably 1.3 g / cm 3 to 1.8 g / cm 3 , more preferably 1.4 g / cm 3 to 1.8 g / cm 3. More preferably, it is 1.5 g / cm 3 to 1.7 g / cm 3 .
• the negative electrode density is 1.3 g / cm 3 or more, the resistance value is unlikely to decrease and the capacity tends to be maintained high.
• the negative electrode density is 1.8 g / cm 3 or less, the deterioration of rate characteristics and cycle characteristics is suppressed. Tend to be.
• the lithium ion secondary battery of the present embodiment includes the above-described negative electrode for a lithium ion secondary battery, a positive electrode, and an electrolyte.
• a lithium ion secondary battery is placed in a container so that the negative electrode and the positive electrode for a lithium ion secondary battery face each other with a separator interposed therebetween, and an electrolyte prepared by dissolving an electrolyte in a solvent is injected into the container. Can be obtained.
• the positive electrode can be obtained by applying a positive electrode material to the surface of the current collector and forming a positive electrode layer in the same manner as the negative electrode.
• a band-shaped material made of a metal material such as aluminum, titanium, stainless steel or the like in a foil shape, a punched foil shape, a mesh shape, or the like can be used.
• the material used for the positive electrode is not particularly limited. Examples thereof include positive electrode active materials such as metal compounds, metal oxides, metal sulfides, and phosphoric acid compounds that can be doped or intercalated with lithium ions, and other materials.
• positive electrode active material such as metal compounds, metal oxides, metal sulfides, and phosphoric acid compounds that can be doped or intercalated with lithium ions, and other materials.
• As a positive electrode active material at least a part of cobalt in lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMnO 2 ), or lithium cobaltate was replaced with at least one of nickel and manganese.
• other materials include conductive polymers such as polyacetylene, polyaniline, polypyrrole,
• the separator examples include non-woven fabrics, cloths, microporous films, or a combination of these, mainly composed of polyolefins such as polyethylene and polypropylene. Note that the separator may be omitted when the positive electrode and the negative electrode are not in contact with each other due to the structure of the lithium ion secondary battery.
• Examples of the electrolyte include lithium salts such as LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , and LiSO 3 CF 3 .
• Solvents that dissolve the electrolyte include ethylene carbonate, fluoroethylene carbonate, chloroethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, cyclohexylbenzene, sulfolane, propane sultone, 3-methylsulfolane, and 2,4-dimethyl.
• the electrode configuration in the lithium ion secondary battery is not particularly limited. Generally, a state in which a positive electrode and a negative electrode and, if necessary, a separator provided between the positive electrode and the negative electrode are stacked in a spiral shape (winding type electrode plate group) and a spiral shape The plate-shaped thing (lamination type electrode plate group) which is not wound around is mentioned.
• the type of lithium ion secondary battery is not particularly limited.
• a laminate type battery, a paper type battery, a button type battery, a coin type battery, a laminated type battery, a cylindrical type battery, a square type battery and the like can be mentioned.
• the negative electrode material of the present embodiment is excellent in input / output characteristics and life characteristics in charge and discharge, a lithium ion secondary that is required to have a relatively large capacity for electric vehicles, power tools, power storage, etc. It is suitably used for batteries.
• a lithium ion secondary that is required to have a relatively large capacity for electric vehicles, power tools, power storage, etc. It is suitably used for batteries.
• EV electric vehicles
• HEV hybrid electric vehicles
• PHEV plug-in hybrid electric vehicles
• charging / discharging with a large current is required to improve acceleration performance and brake regeneration performance.
• it is desirable to use the negative electrode material of the present embodiment which is excellent in input / output characteristics.
• the mixture obtained by mixing 5 parts by mass was put in a cylinder in which a rotor blade was arranged, and was rubbed between the inner wall of the cylinder and the rotor blade to attach coal tar pitch to the surface of spherical natural graphite. .
• the rubbing process was performed for 5 minutes at a load of 24 kW (load: 1800 kJ / kg).
• the temperature was raised to 1000 ° C. at a rate of temperature increase of 20 ° C./hour and held for 1 hour to carbonize the coal tar pitch. Thereafter, the mixture was crushed with a cutter mill and sieved with a 300-mesh sieve.
• Composite material 1 and composite material 2 were mixed at a mass ratio of 5: 5 (composite material 1: composite material 2) to produce a carbon material.
• the obtained carbon material was subjected to XRD analysis, specific surface area measurement, particle size distribution measurement, tap density measurement, and pellet density measurement by the following methods.
• N 2 specific surface area measurement For carbon materials, nitrogen adsorption at a liquid nitrogen temperature (77 K) was measured by a multipoint method using a high-speed specific surface area / pore distribution measuring device (“ASAP2010” manufactured by MICROMERITICS), and the BET method (relative pressure range: 0). .05-0.2).
• ASAP2010 high-speed specific surface area / pore distribution measuring device
• a solution in which a carbon material is dispersed in purified water together with a surfactant is placed in a sample water tank of a laser diffraction particle size distribution measuring apparatus (“SALD-3000J” manufactured by Shimadzu Corporation), and ultrasonicated for 1 minute while being circulated by a pump. And measured by a laser diffraction method under the following measurement conditions. At this time, the output conditions were set on the basis of number or volume, and values corresponding to the following (1) to (5) were examined.
• SALD-3000J laser diffraction particle size distribution measuring apparatus
• the accumulation is 50% when a volume cumulative distribution curve is drawn from the small particle diameter side.
• the particle size (50% D) was examined.
• volume-based particle size distribution obtained by setting the output condition distribution criterion as “volume” in the above particle size distribution measurement, when the volume cumulative distribution curve is drawn from the small particle diameter side, the accumulation is 99.9%. The particle diameter (99.9% D) was examined.
• the average aspect ratio of the carbon material was determined using a flow type particle image analyzer (“FPIA-3000” manufactured by Sysmex Corporation).
• aqueous dispersion having a concentration of SBR (“BM-400B” from Nippon Zeon Co., Ltd.) of 40% by mass as a binder is added so that the solid content of SBR is 1 part by mass, and the paste is mixed for 10 minutes.
• a negative electrode material composition was prepared. This negative electrode material composition was applied to an electrolytic copper foil having a thickness of 40 ⁇ m in a circular shape having a diameter of 9.5 mm using a mask having a thickness of 200 ⁇ m. Further, the sample was dried at 105 ° C. to remove moisture, and a sample electrode (negative electrode) was produced.
• the sample electrode, separator, and counter electrode stacked in this order are placed in a battery container, and LiPF 6 is added to a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) (EC and MEC are in a volume ratio of 1: 3).
• the coin electrolyte was prepared by injecting an electrolyte solution dissolved in a concentration of 1.5 mol / liter.
• Metal lithium was used for the counter electrode, and a polyethylene microporous film having a thickness of 20 ⁇ m was used for the separator.
• a negative electrode material composition produced by the same method as the negative electrode material composition used for the measurement of the initial charge / discharge efficiency was applied to an electrolytic copper foil with a thickness of 40 ⁇ m so that the coating amount per unit area was 9.0 mg / cm 2. It was coated with a comma coater with adjusted clearance. Thereafter, the electrode density was adjusted to 1.5 g / cm 3 with a hand press. This electrode was punched into a disk shape having a diameter of 14 mm to produce a sample electrode (negative electrode). A coin battery was fabricated in the same manner as the measurement of the initial charge / discharge efficiency except that this sample electrode was used.
• the life characteristics were evaluated according to the following procedure.
• a coin battery was produced by a method equivalent to the life characteristics, and the input / output characteristics were evaluated by the following procedure. (1) The battery was charged to 0 V (Vvs. Li / Li + ) at a constant current of 0.96 mA, and then charged at a constant voltage of 0 V until the current value reached 0.096 mA. (2) After a rest time of 30 minutes, the battery was discharged to 1.5 V (Vvs. Li / Li + ) with a constant current of 0.96 mA. (3) The battery was charged to half the capacity with a constant current of 0.96 mA.
• Example 2 A carbon material was produced in the same manner as in Example 1 except that the composite material 1 and the composite material 2 were mixed so that the mass ratio was 4: 6 (composite material 1: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• Example 3 A carbon material was prepared in the same manner as in Example 1 except that the composite material 1 and the composite material 2 were mixed so that the mass ratio was 3: 7 (composite material 1: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• Example 4 A carbon material was prepared in the same manner as in Example 1 except that the composite material 1 and the composite material 2 were mixed so that the mass ratio was 6: 4 (composite material 1: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• Example 1 A carbon material was produced in the same manner as in Example 1 except that the composite material 1 and the composite material 2 were mixed so that the mass ratio was 2: 8 (composite material 1: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• Example 2 A carbon material was produced in the same manner as in Example 1 except that only the composite material 2 was used, and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• Example 3 A carbon material was produced in the same manner as in Example 1 except that only the composite material 1 was used, and its characteristics were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• composite material 3 was obtained.
• a carbon material was produced in the same manner as in Example 1 except that the composite material 3 and the composite material 2 were mixed so that the mass ratio was 5: 5 (composite material 3: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• the composite material was the same as the composite material 1 except that a mixture obtained by mixing 100 parts by mass of the carbon particles and 20 parts by mass of polyvinyl alcohol (degree of polymerization 1700, complete saponification type, carbonization rate 15% by mass) was used. 4 was obtained.
• a carbon material was produced in the same manner as in Example 1 except that the composite material 4 and the composite material 2 were mixed so that the mass ratio was 5: 5 (composite material 4: composite material 2), and the characteristics thereof were examined. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• the obtained lump was pulverized with a pin mill and then molded into a block shape having a density of 1.52 g / cm 3 with a mold press.
• the obtained block was fired at a maximum temperature of 800 ° C. in a muffle furnace, and then graphitized at 2900 ° C. in an autolysis gas atmosphere in an Atchison furnace.
• the graphitized block was roughly crushed with a hammer, and a graphite powder having an average particle size of 30 ⁇ m was obtained with a pin mill. Further, this graphite powder was processed for 10 minutes using a spheroidizing apparatus (manufactured by Hosokawa Micron, Faculty) at a grinding rotation speed of 1800 rotations / minute (rpm) and a classification rotation speed of 7000 rotations / minute (rpm). Chemical artificial graphite powder was prepared. This spheroidized artificial graphite powder was passed through a 200-mesh sieve to obtain a carbon material under the sieve. The characteristics of this carbon material were examined in the same manner as in Example 1. Moreover, the coin battery was produced and the performance was evaluated. The results are shown in Table 2.
• the lithium ion secondary batteries of Examples 1 to 4 manufactured using the negative electrode material containing the carbon material of the present embodiment were able to input / output while maintaining high charge / discharge efficiency. Excellent properties and life characteristics.

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