WO2013141041A1 - Composite graphitic particles and method for manufacturing same - Google Patents
Composite graphitic particles and method for manufacturing same Download PDFInfo
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- WO2013141041A1 WO2013141041A1 PCT/JP2013/056414 JP2013056414W WO2013141041A1 WO 2013141041 A1 WO2013141041 A1 WO 2013141041A1 JP 2013056414 W JP2013056414 W JP 2013056414W WO 2013141041 A1 WO2013141041 A1 WO 2013141041A1
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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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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/205—Preparation
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
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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
- H01M4/366—Composites as layered products
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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
Definitions
- the present invention relates to composite graphite particles and a method for producing the same.
- composite particles containing the following graphite and conductive carbonaceous fine particles have been proposed as electrode active material materials for lithium ion secondary batteries.
- a carbonaceous layer having a lower crystallinity than the graphite granule is filled and / or coated on the internal voids and / or the outer surface of the graphite granule formed by aggregating a plurality of scaly graphites, Composite graphite particles in which carbonaceous fine particles are added to a carbonaceous layer (for example, see JP-A-2004-066331).
- the average particle diameter is 0.05 to 2 ⁇ m and the average lattice spacing d (002) is 0.3360 nm.
- the above amorphous carbon powder is bound and coated with carbide of binder pitch, the nitrogen adsorption specific surface area is 3 to 7 m 2 / g, the average particle diameter is 7 to 40 ⁇ m, and the Raman spectral intensity ratio 11360/11580.
- An object of the present invention is to provide composite graphite particles capable of forming a dense conductive network in an electrode when forming an electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and a method for producing the same. is there.
- the composite graphite particles according to one aspect of the present invention include graphite, conductive carbonaceous fine particles, and non-graphitic carbon.
- the graphite is preferably natural graphite.
- the natural graphite is preferably a spherical graphite granule formed by aggregating a plurality of scaly natural graphites.
- the graphite is preferably smoothed.
- the circularity is 0.92 or more and 1.00 or less
- the incident angle dependence S 60/0 of the peak intensity ratio in the CK edge X-ray absorption spectrum is 0.00 . It is preferable that it is 7 or less.
- the conductive carbonaceous fine particles are directly attached to the graphite.
- Non-graphitic carbon is at least partially attached to the conductive carbonaceous fine particles and graphite.
- the composite graphite particles are configured as described above, a part or all of the conductive carbonaceous fine particles can be detached from the graphite by applying a predetermined external force. For this reason, if composite graphite particles are formed so that part or all of the conductive carbonaceous fine particles are desorbed from graphite with a force applied when preparing an electrode mixture slurry, Conductive carbonaceous fine particles can be uniformly dispersed. That is, if this composite graphite particle is used, a dense conductive network mainly composed of graphite and conductive carbonaceous fine particles can be formed in the electrode when forming the electrode of the nonaqueous electrolyte secondary battery.
- the ratio of "predetermined specific surface area after an external force is applied (m 2 / g)" "The specific surface area value before the predetermined force is applied (m 2 / g)" for the composite graphite particles described above It is preferably in the range of 1.10 or more and 2.00 or less. This is because such composite graphite particles can release a sufficient amount of conductive carbonaceous fine particles into the slurry during slurry preparation.
- the mass ratio of the conductive carbonaceous fine particles to graphite is preferably in the range of 0.3% to 2.0%.
- the mass ratio of non-graphitic carbon to the sum of graphite and conductive carbonaceous fine particles is preferably in the range of 0.8% to 15.0%.
- the method for producing composite graphite particles according to another aspect of the present invention includes a primary composite particle preparation step and a composite graphite particle preparation step.
- the conductive composite particles are prepared by directly attaching the conductive carbonaceous fine particles to the graphite.
- the graphite is preferably natural graphite.
- the natural graphite is preferably a spherical graphite granule formed by aggregating a plurality of scaly natural graphites.
- the graphite is preferably smoothed.
- the circularity is 0.92 or more and 1.00 or less, and the incident angle dependence of the peak intensity ratio in the CK edge X-ray absorption spectrum is 0.7 or less. It is preferable.
- a mechanochemical treatment is performed on the conductive carbonaceous fine particles and graphite.
- non-graphitic carbon is partially or wholly attached to the primary composite particles to prepare composite graphite particles.
- composite graphite particles in which part or all of the conductive carbonaceous fine particles are detached from the graphite by applying a predetermined external force can be constituted. For this reason, if the composite graphite particles are formed so that part or all of the conductive carbonaceous fine particles are detached from the graphite with a force applied when preparing the electrode mixture slurry, Conductive carbonaceous fine particles can be uniformly dispersed. That is, if this composite graphite particle is used, a dense conductive network can be formed in the electrode when forming the electrode of the nonaqueous electrolyte secondary battery.
- the composite graphite particle preparation step primary composite particles and non-graphitic carbon raw material powder are mixed and then heated. As a result, the non-graphitic carbon raw material powder is converted into non-graphitic carbon, and the non-graphitic carbon is partially or entirely attached to the primary composite particles.
- Nonaqueous electrolyte secondary batteries are represented by lithium ion secondary batteries.
- FIG. 2 is a scanning electron micrograph of composite graphite particles according to an embodiment of the present invention.
- 2 is a scanning electron micrograph of composite graphite particles after ultrasonic treatment of the composite graphite particles shown in FIG.
- It is a figure which shows the measurement principle of X-ray absorption spectroscopy by contrast with X-ray photoelectron spectroscopy (XPS).
- XPS X-ray photoelectron spectroscopy
- FIG. 6 is a diagram illustrating a CK end NEXAFS spectrum when radiant light is incident on the line. It is a figure explaining the case where HOPG is made into the sample for the quantitative evaluation method of the orientation of surface graphite crystal.
- the composite graphitic particles according to the embodiment of the present invention are mainly composed of graphite, conductive carbonaceous fine particles, and non-graphitic carbon.
- the graphite may be natural graphite or artificial graphite, but is preferably natural graphite.
- As the graphite a mixture of natural graphite and artificial graphite may be used.
- the graphite is preferably a spherical graphite granule formed by aggregating a plurality of scaly graphites.
- scale-like graphite natural graphite, artificial graphite, mesophase calcined carbon (bulk mesophase) made from tar pitch, coke (raw coke, green coke, pitch coke, needle coke, petroleum coke, etc.), etc.
- Graphitized, etc., and those granulated using a plurality of natural graphites having high crystallinity are particularly preferable.
- One graphite granule is usually formed by collecting 2 to 100, preferably 3 to 20, scaly graphite, but can be made spherical by folding one graphite. .
- the graphite is preferably smoothed.
- the circularity is 0.92 or more and 1.00 or less
- the incident angle dependence S 60/0 of the peak intensity ratio in the CK edge X-ray absorption spectrum is 0.00 . It is preferable that it is 7 or less.
- the lower limit of the incident angle dependence S 60/0 of the peak intensity ratio in the CK edge X-ray absorption spectrum is preferably 0.5, that is, 0.5 or more.
- the circularity of the graphite granule is 0.92 or more, since the graphite granule is relatively spherical, the graphite granule is not oriented when the electrode mixture slurry is applied. Is less likely to cause problems such as a decrease in capacity of the nonaqueous electrolyte secondary battery. Further, when the incident angle dependence S 60/0 of the peak intensity ratio in the CK edge X-ray absorption spectrum is 0.7 or less, the surface of the graphite granule becomes sufficiently smooth and an external force is applied. In addition, the conductive carbonaceous fine particles are easily detached from the graphite.
- the incident angle dependence of the peak intensity ratio in the CK edge X-ray absorption spectrum used as an index of the surface smoothness of the graphite granulated product is S 60/0 (hereinafter, simply referred to as “S 60/0 ”). Exist).
- the CK-edge X-ray absorption spectrum is also called a CK-edge NEXAFS (Near Edge X-ray Absorption Fine Structure) spectrum, which is an electron existing in the core level (1s orbital) of an occupied carbon atom (1s orbital).
- K-shell inner-shell electrons are absorption spectra that are observed when the irradiated X-ray energy is absorbed and excited to various vacant levels in an unoccupied state.
- the measurement principle of this X-ray absorption spectroscopy is shown in FIG. 3 in comparison with X-ray photoelectron spectroscopy (XPS).
- XPS X-ray photoelectron spectroscopy
- an energy variable light source in the soft X-ray region (280 eV to 320 eV) is necessary. Since the quantitative property of S 60/0 is based on the premise that the linear polarization property of the excitation light source is high, synchrotron radiation is used as the excitation light source in the CK edge NEXAFS spectrum.
- the vacant levels at which electrons in the inner core level are excited include ⁇ * levels attributed to antibonding orbitals of sp2 bonds that reflect the crystallinity (basal plane, orientation, etc.) in natural graphite, crystals ⁇ * level attributed to anti-bonding orbitals of sp3 bonds that reflect disorder of properties (edge surface, non-orientation, etc.), or anti-bonding orbitals such as CH bonds and CO bonds There are empty levels.
- the surface is a plane of a hexagonal network surface (AB surface described later) is a basal surface, and a surface on which an end of the hexagonal network appears. Is the edge surface. On the edge surface, carbon often has an sp3 bond (because there is a possibility that —C ⁇ O or the like is present at the terminal).
- the CK edge NEXAFS spectrum reflects the local structure in the vicinity of the carbon atom including the excited inner electrons, and in addition, the escape depth of electrons emitted from the solid into the vacuum by the irradiated light. Since the thickness is about 10 nm, only the measured surface structure of the graphite particles is reflected. Therefore, by using the CK edge NEXAFS spectrum, it is possible to measure the crystalline state (orientation) of graphite on the surface of the graphite granulated product, thereby evaluating the roughness of the surface of the graphite granulated product. it can.
- the method for fixing the graphite granule to be measured to the sample stage is not particularly limited. It is preferable to employ a method of supporting the graphite particles on the copper substrate with In foil or supporting it on the copper substrate with carbon tape so that an excessive load is not applied to the graphite particles.
- surface graphite crystal As described below, by measuring S 60/0 , the orientation of the graphite crystals in the vicinity of the surface of the measured graphite granulated product (hereinafter referred to as “surface graphite crystal”) can be quantitatively evaluated. it can.
- the incident angle of the radiated light to the sample is If the sample is a sample with a low orientation of a carbon material that forms sp2 bonds in the vicinity of the surface, such as a carbon vapor deposition film (non-graphite), the incident angle of the emitted light to the sample changes. Even if is changed, the spectrum shape hardly changes.
- HOPG highly oriented pyrolytic graphite
- FIG. 5 shows CK-edge NEXAFS spectra when radiated light is incident on carbon at different incident angles (0 °, 30 °, and 60 °).
- the graph on the left side shows a case where HOPG (highly oriented pyrolytic graphite) in which carbon is a single crystal
- the graph on the right side shows a carbon deposited film in which carbon is non-graphitic ( The case of film thickness: 10 nm) is shown.
- HOPG highly oriented pyrolytic graphite
- FIG. 5 shows CK-edge NEXAFS spectra when radiated light is incident on carbon at different incident angles (0 °, 30 °, and 60 °).
- the graph on the left side shows a case where HOPG (highly oriented pyrolytic graphite) in which carbon is a single crystal
- the graph on the right side shows a carbon deposited film in which carbon is non-graphitic ( The case of film thickness: 10 nm) is shown.
- the absorption peak intensity A is increased, and the absorption peak intensity B attributed to the transition from the C-1s level to the ⁇ * level is decreased. Therefore, the profile of the HOPG CK edge NEXAFS spectrum varies greatly depending on the incident angle.
- the profile of the CK edge NEXAFS spectrum of the non-graphitic carbon deposited film shown in the graph on the right side of FIG. 5 hardly depends on the incident angle, and the incident angle changes. But the profile hardly changes.
- FIG. 6 is a diagram for explaining the quantitative evaluation method for the orientation of the surface graphite crystal, taking HOPG as a sample as an example.
- Examples of the method of forming a graphite granulated product by aggregating a plurality of graphites include, for example, a method of mixing a plurality of scaly graphites in the presence of a binder of a graphite raw material, and a method of applying mechanical external force to a plurality of scaly graphites And a method using the above-mentioned two methods in combination.
- a method of granulating by applying a mechanical external force without using a binder component is particularly preferable.
- a counter jet mill AFG manufactured by Hosokawa Micron Corporation, registered trademark
- a current jet manufactured by Nissin Engineering Co., Ltd., registered trademark
- an ACM pulverizer Hosokawa Micron Corporation
- a pulverizer such as “manufactured registered trademark”, a hybridization system (manufactured by Nara Machinery Co., Ltd., registered trademark), mechano hybrid (manufactured by Nippon Coke Industries, Ltd., registered trademark), and the like can be used.
- a method of smoothing graphite for example, a method of applying mechanical external force to graphite can be mentioned.
- a shear compression processing machine such as a mechanofusion system (manufactured by Hosokawa Micron Corporation, “Mechanofusion” is a registered trademark) can be used.
- the conductive carbonaceous fine particles are directly attached to the graphite.
- the conductive carbonaceous fine particles are, for example, carbon black such as Ketjen Black (registered trademark), furnace black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanocoil and the like.
- carbon black such as Ketjen Black (registered trademark)
- furnace black acetylene black
- carbon nanotube carbon nanofiber
- carbon nanocoil and the like acetylene black
- acetylene black is particularly preferable.
- the conductive carbonaceous fine particles may be a mixture of different types of carbon black or the like.
- the mass ratio of the conductive carbonaceous fine particles to graphite is preferably in the range of 0.3% to 2.0%, more preferably in the range of 0.5% to 2.0%, More preferably, it is in the range of 0.7% or more and 2.0% or less, and particularly preferably in the range of 1.0% or more and 2.0% or less.
- Non-graphitic carbon is at least partially adhered to the conductive carbonaceous fine particles and graphite.
- Non-graphitic carbon is at least one of amorphous carbon and turbostratic carbon.
- amorphous carbon refers to carbon that has short-range order (on the order of several to tens of atoms) but does not have long-range order (on the order of hundreds to thousands of atoms).
- turbostratic structure carbon refers to carbon composed of carbon atoms having a turbulent structure parallel to the hexagonal plane direction, but having no crystallographic regularity in the three-dimensional direction.
- hkl diffraction lines corresponding to the 101 plane and the 103 plane do not appear.
- the composite graphite particles according to the embodiment of the present invention have strong diffraction lines of graphite as a base material, it is difficult to confirm the existence of the turbostratic carbon by X-ray diffraction. For this reason, it is preferable that the turbostratic structure carbon is confirmed with a transmission electron microscope (TEM) or the like.
- TEM transmission electron microscope
- This turbostratic carbon is obtained by firing a raw material of non-graphitic carbon.
- the raw material of non-graphitic carbon is an organic compound such as tar, petroleum-based pitch powder, coal-based pitch powder, and resin powder.
- the non-graphitic carbon raw material may be a mixture of different types of pitches. Among these, coal-based pitch powder is particularly preferable.
- the heat treatment temperature may be in the range of 800 ° C to 1200 ° C.
- This heat treatment time is appropriately determined in consideration of the heat treatment temperature and the characteristics of the organic compound, and is typically about 1 hour.
- the atmosphere during the heat treatment is preferably a non-oxidizing atmosphere (inert gas atmosphere, vacuum atmosphere), and a nitrogen atmosphere is preferred from an economic viewpoint.
- Amorphous carbon can be formed, for example, by a vapor phase method such as a vacuum deposition method or a plasma CVD method.
- the mass ratio of non-graphitic carbon to the sum of graphite and conductive carbonaceous fine particles is preferably in the range of 0.8% to 15.0%, and in the range of 2.0% to 14.0%. More preferably, it is more preferably within the range of 4.0% or more and 12.0% or less, and particularly preferably within the range of 6.0% or more and 10.0% or less.
- the composite graphite particles according to the embodiment of the present invention When an external force such as ultrasonic waves is applied to the composite graphite particles according to the embodiment of the present invention, some or all of the conductive carbonaceous fine particles are detached from the graphite (see FIGS. 1 and 2).
- the force required for this desorption is the various settings of the mechanochemical (registered trademark) processing device and mechanofusion (registered trademark) processing device, the type of non-graphitic carbon raw material powder, and the composition , And can be adjusted depending on the amount added.
- Such composite graphite particles can be used as an active material constituting an electrode, particularly a negative electrode of a nonaqueous electrolyte secondary battery.
- the nonaqueous electrolyte secondary battery is represented by a lithium ion secondary battery.
- the composite graphite particles according to the embodiment of the present invention are manufactured through a primary composite particle preparation step and a composite graphite particle preparation step.
- the conductive composite particles are directly attached to the graphite by a process such as a mechanochemical (registered trademark) process or a mechanofusion (registered trademark) process to produce primary composite particles.
- the composite graphite particle preparation step the primary composite particles and the non-graphitic carbon raw material powder are mixed and then heated. As a result, the non-graphitic carbon raw material powder is converted into non-graphitic carbon, and the non-graphitic carbon is partially or entirely attached to the primary composite particles.
- this spherical natural graphite powder is referred to as “smoothed spherical natural graphite powder”.
- the average particle diameter means a particle diameter (D50) at a volume fraction of 50% in the cumulative particle size distribution unless otherwise specified.
- the smoothed spherical natural graphite powder has a circularity of 0.92 or more and 1.00 or less, and the incident angle dependence S 60/0 of the peak intensity ratio in the CK edge X-ray absorption spectrum is 0.67. Was confirmed.
- the circularity was measured using a flow type particle image analyzer FPIA-2100 ("FPIA” is a registered trademark) manufactured by Sysmex Corporation.
- FPIA flow type particle image analyzer
- (Circularity) is a value obtained by dividing (perimeter of a circle having the same area as the projection shape) by (perimeter of the projection shape).
- the “projection shape” is a shape obtained by projecting the particles to be measured onto a two-dimensional plane, and the circumference length of a circle having the same area as the projection shape and the circumference length of the projection shape are It is obtained by image processing of an image.
- the CK edge X-ray absorption spectrum was measured using synchrotron radiation facility NEWVAL beam lines BL7B and BL9. During this measurement, emitted light is emitted when electrons accumulated in the storage ring with an acceleration voltage of 1.0 GeV to 1.5 GeV and an accumulation current of 80 to 350 mA meander through an insertion light source called an undulator. Was used as an excitation light source.
- the C-K edge X-ray absorption spectrum of the smooth spherical natural graphite powder was measured using a CK edge NEXAFS (Near Edge X-ray Absorbance Fine Structure) installed in the beam lines BL7B and BL9.
- a 60 is the C-1s level to ⁇ * level (ie, anti-bonding property of sp2 bond) in the CK edge X-ray absorption spectrum of the particle, measured with the incident angle of the emitted light being 60 °.
- Absorption peak intensity attributed to the transition to orbit: -C C-).
- B 60 is the C-1s level to ⁇ * level (that is, the antibonding orbital of sp3 bond in the CK edge X-ray absorption spectrum of the particle measured with the incident angle of the emitted light being 60 °: It is the absorption peak intensity attributed to the transition to -CC-).
- a 0 is the absorption peak intensity attributed to the transition from the C-1s level to the ⁇ * level in the CK edge X-ray absorption spectrum of the particle, measured with the incident angle of the emitted light being 0 °. is there.
- B 0 is the absorption peak intensity attributed to the transition from the C-1s level to the ⁇ * level in the CK edge X-ray absorption spectrum of the particle, measured with the incident angle of the emitted light being 0 °. is there.
- this mixed powder 600 g was put into a mechano-fusion system (AMS-Lab made by Hosokawa Micron) with a gap of 5 mm between the rotor and the inner piece, and then the mixed powder was processed at a rotational speed of 2600 rpm for 5 minutes to make it smooth Spherical natural graphite powder and acetylene black were combined.
- this composite is referred to as “primary composite powder”.
- the contents of the beaker were filtered. And after fully drying the filtrate, the specific surface area was calculated
- the BET specific surface area of the composite graphite particles after the ultrasonic treatment was 3.81 m 2 / g (see Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.14 (see Table 2).
- the coating film was punched into a disk shape having a diameter of 13 mm. Thereafter, the disk was pressed with a press molding machine so that the density of the disk was 1.60 g / cm 3 , thereby producing an electrode.
- (3-2) Battery Preparation An electrode assembly was prepared by disposing the above electrode and a counter Li metal foil on both sides of a polyolefin separator. And the electrolyte solution was inject
- dedoping (corresponding to detachment of lithium ions from the electrode and discharging of the lithium ion secondary battery) was performed at a constant current of 0.325 mA until the potential difference became 1.5 V, and the dedoping capacity was measured.
- the doping capacity and the dedoping capacity at this time correspond to the charging capacity and discharging capacity when this electrode is used as the negative electrode of the lithium ion secondary battery, and these were used as the charging capacity and discharging capacity.
- the discharge capacity of the non-aqueous test cell according to this example was 367 mAh / g (see Table 2).
- the ratio of dedoping capacity / doping capacity corresponds to the ratio of discharge capacity / charge capacity of the lithium ion secondary battery, this ratio was defined as charge / discharge efficiency.
- the charge / discharge efficiency of the non-aqueous test cell according to this example was 93.3% (see Table 2).
- Cycle characteristics were measured using a coin-type non-aqueous test cell configured in the same manner as described above.
- this test cell the above-described charging / discharging was performed, and from this, a “discharge capacity at the first dedoping” was obtained.
- doping was continued at a constant voltage until 50 ⁇ A was maintained while maintaining 5 mV.
- undoping was performed at a constant current of 1.56 mA until the potential difference became 1.5 V (corresponding to discharge), and the dedoping capacity was measured.
- the dedope capacity at this time was defined as the discharge capacity.
- the average particle size of the composite graphite particles was 19.5 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 4.54 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.73 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.22 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 55.1% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 365 mAh / g (see Table 2), the charge / discharge efficiency was 92.8% (see Table 2), and the capacity retention rate was 98.6% (see Table 2). ).
- the average particle size of the composite graphite particles was 19.5 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 4.67 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.48 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.34 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 53.9% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 364 mAh / g (see Table 2), the charge / discharge efficiency was 92.5% (see Table 2), and the capacity retention rate was 99.3% (see Table 2). ).
- the average particle size of the composite graphite particles was 19.6 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 4.94 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.40 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.45 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 53.0% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 362 mAh / g (see Table 2), the charge / discharge efficiency was 91.9% (see Table 2), and the capacity retention rate was 99.5% (see Table 2). ).
- the average particle size of the composite graphite particles was 19.7 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 1.60 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 1.40 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.14 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 54.9% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 355 mAh / g (see Table 2), the discharge efficiency was 92.3% (see Table 2), and the capacity retention rate was 97.4% (see Table 2). .
- the average particle size of the composite graphite particles was 19.9 ⁇ m (see Table 1).
- the BET specific surface area of the composite graphite particles before ultrasonication was 1.00 m 2 / g (see Table 2), and the BET specific surface area of the particles after ultrasonic treatment was 0.90 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.11 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 55.3 mass% (see Table 2).
- the discharge capacity of the non-aqueous test cell was 340 mAh / g (see Table 2), the discharge efficiency was 91.9% (see Table 2), and the capacity retention rate was 94.2% (see Table 2). .
- the average particle size of the composite graphite particles was 19.6 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 3.98 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.66 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before the ultrasonic treatment to the BET specific surface area after the ultrasonic treatment was 1.09 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 56.6% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 367 mAh / g (see Table 2), the discharge efficiency was 93.5% (see Table 2), and the capacity retention rate was 84.6% (see Table 2). .
- the average particle size of the composite graphite particles was 19.6 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 5.44 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.48 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before ultrasonic treatment to the BET specific surface area after ultrasonic treatment was 1.56 (see Table 2).
- the solid concentration of the electrode mixture slurry was 51.4% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 359 mAh / g (see Table 2), the discharge efficiency was 91.2% (see Table 2), and the capacity retention rate was 99.7% (see Table 2). .
- the target composite graphite particles were obtained, and the characteristics of the composite graphite particles were evaluated in the same manner as in Example 1.
- the mass ratio of the spherical natural graphite powder, acetylene black, and non-graphitic carbon in the composite graphite particles was 98.0: 1.0: 1.0 (see Table 1).
- the average particle size of the composite graphite particles was 19.5 ⁇ m (see Table 1).
- BET specific surface area before sonication composite graphite particles is 4.50 m 2 / g (see Table 2), the BET specific surface area after sonication of the same particles was 4.15m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before ultrasonic treatment to the BET specific surface area after ultrasonic treatment was 1.08 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 55.3 mass% (see Table 2).
- the discharge capacity of the non-aqueous test cell was 365 mAh / g (see Table 2), the discharge efficiency was 98.5% (see Table 2), and the capacity retention rate was 86.3% (see Table 2). .
- Example 1 “(2) Smoothing spherical natural graphite powder and acetylene black are not composited”, and “(3) Primary composite powder and non-graphitic carbon are composited”.
- the control was carried out in the same manner as in Example 1 except that the smoothed spherical natural graphite powder and the coal-based pitch powder were mixed so that the mass ratio with the powder (average particle size 20 ⁇ m) was 100.0: 2.0.
- a powder was obtained, and the control powder was evaluated in the same manner as in Example 1.
- the mass ratio of the smoothed spherical natural graphite powder, acetylene black and non-graphitic carbon was 99.0: 0.0: 1.0 (see Table 1).
- the average particle size of the composite graphite particles was 19.6 ⁇ m (see Table 1).
- the BET specific surface area before ultrasonic treatment of the composite graphite particles was 3.83 m 2 / g (see Table 2), and the BET specific surface area after ultrasonic treatment of the particles was 3.60 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before ultrasonic treatment to the BET specific surface area after ultrasonic treatment was 1.06 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 57.2% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 367 mAh / g (see Table 2), the discharge efficiency was 93.9% (see Table 2), and the capacity retention rate was 78.8% (see Table 2). .
- the average particle size of the composite graphite particles was 19.5 ⁇ m (see Table 1).
- the BET specific surface area of the composite graphite particles before ultrasonic treatment was 6.80 m 2 / g (see Table 2), and the BET specific surface area of the particles after ultrasonic treatment was 5.48 m 2 / g ( (See Table 2). That is, the ratio of the BET specific surface area before ultrasonic treatment to the BET specific surface area after ultrasonic treatment was 1.24 (see Table 2).
- the solid content concentration of the electrode mixture slurry was 57.2% by mass (see Table 2).
- the discharge capacity of the non-aqueous test cell was 364 mAh / g (see Table 2), the discharge efficiency was 89.8% (see Table 2), and the capacity retention rate was 98.3% (see Table 2). .
- the capacity retention rate is at a high level. It was found to be maintained. It was also found that the larger the mass ratio of acetylene black to non-graphitic carbon, the greater the ratio of the BET specific surface area before ultrasonic treatment to the BET specific surface area after ultrasonic treatment.
- the ratio of the discharge capacity of the 10th cycle to the discharge capacity of the 1st cycle is expressed as a percentage as an evaluation index of charge / discharge cycle characteristics. As the performance of secondary batteries increases, evaluation of discharge capacity of about 10 cycles is not sufficient for practical use.
- non-aqueous test cell of the present application has a non-aqueous test cell (hereinafter referred to as “conventional non-aqueous test cell”) disclosed in Japanese Patent Application Laid-Open No. 2004-066331. It is difficult to simply compare the two non-aqueous test cells, but the non-aqueous test cell of the present application is more severe than the conventional non-aqueous test cell. Since the charge / discharge cycle characteristics are evaluated, it is considered that the non-aqueous test cell of the present application is superior in charge / discharge cycle characteristics than the conventional non-aqueous test cell.
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Abstract
Description
結合エネルギーが283.8eVである炭素の内殻準位から種々の空準位への電子遷移を観測するためには、軟X線領域(280eV~320eV)におけるエネルギー可変光源が必要であること、およびS60/0の定量性は励起光源の直線偏光性が高いことを前提としていることから、C-K端NEXAFSスペクトルでは励起光源として放射光を用いる。 The measurement principle of this X-ray absorption spectroscopy is shown in FIG. 3 in comparison with X-ray photoelectron spectroscopy (XPS).
In order to observe electronic transitions from the core level of carbon having a binding energy of 283.8 eV to various vacant levels, an energy variable light source in the soft X-ray region (280 eV to 320 eV) is necessary. Since the quantitative property of S 60/0 is based on the premise that the linear polarization property of the excitation light source is high, synchrotron radiation is used as the excitation light source in the CK edge NEXAFS spectrum.
したがって、ある黒鉛系材料に対して異なる入射角でC-K端NEXAFSスペクトルを測定した結果、吸収ピーク強度Aに対する吸収ピーク強度Bの比I(=B/A)が入射角に応じて変化する場合には、その材料の表面近傍に存在する黒鉛結晶は規則正しく並んで配置されており、つまり、配向性が高く、その比Iに入射角依存性が見られない場合には、その材料の表面近傍に存在する黒鉛結晶は不規則に並んでいて配向性が低いということになる。そうすると、吸収ピーク強度Aに対する吸収ピーク強度Bの比Iの入射角依存性を定量化することにより、黒鉛系材料の表面近傍に存在する黒鉛結晶の配向性を定量的に評価することができることになる。[Correction 21.05.2013 based on Rule 91]
Therefore, as a result of measuring the CK edge NEXAFS spectrum at a different incident angle for a certain graphite-based material, the ratio I (= B / A) of the absorption peak intensity B to the absorption peak intensity A varies depending on the incident angle. In this case, the graphite crystals existing in the vicinity of the surface of the material are regularly arranged, that is, when the orientation is high and the incidence angle dependence is not seen in the ratio I, the surface of the material The graphite crystals present in the vicinity are irregularly arranged and have low orientation. Then, by quantifying the incident angle dependence of the ratio I of the absorption peak intensity B to the absorption peak intensity A, the orientation of the graphite crystals existing in the vicinity of the surface of the graphite-based material can be quantitatively evaluated. Become.
そこで、ここでは、二つの入射角60°および0°の場合における吸収ピーク強度Aに対する吸収ピーク強度Bの比I60およびI0を用いて導かれるピーク強度比の入射角依存性S60/0(=I60/I0)を用いて、表面黒鉛結晶の配向性を定量評価する。図6は、表面黒鉛結晶の配向性の定量評価方法を、HOPGを試料とした場合を例として説明する図である。[Correction 21.05.2013 based on Rule 91]
Therefore, here, the incident angle dependence S 60/0 of the peak intensity ratio derived using the ratios I 60 and I 0 of the absorption peak intensity B to the absorption peak intensity A in the case of two incident angles 60 ° and 0 °. (= I 60 / I 0 ) is used to quantitatively evaluate the orientation of the surface graphite crystals. FIG. 6 is a diagram for explaining the quantitative evaluation method for the orientation of the surface graphite crystal, taking HOPG as a sample as an example.
本発明の実施の形態に係る複合黒鉛質粒子は、一次複合粒子調製工程および複合黒鉛質粒子調製工程を経て製造される。一次複合粒子調製工程では、メカノケミカル(登録商標)処理、メカノフュージョン(登録商標)処理等の処理により、導電性炭素質微粒子が直接的に黒鉛に付着されて一次複合粒子が作製される。複合黒鉛質粒子調製工程では、一次複合粒子と非黒鉛質炭素の原料粉末とが混合された後に加熱される。その結果、非黒鉛質炭素の原料粉末が非黒鉛質炭素に変換されると共に、一次複合粒子に非黒鉛質炭素が部分的に又は全体的に付着される。 <Manufacture of composite graphite particles>
The composite graphite particles according to the embodiment of the present invention are manufactured through a primary composite particle preparation step and a composite graphite particle preparation step. In the primary composite particle preparation step, the conductive composite particles are directly attached to the graphite by a process such as a mechanochemical (registered trademark) process or a mechanofusion (registered trademark) process to produce primary composite particles. In the composite graphite particle preparation step, the primary composite particles and the non-graphitic carbon raw material powder are mixed and then heated. As a result, the non-graphitic carbon raw material powder is converted into non-graphitic carbon, and the non-graphitic carbon is partially or entirely attached to the primary composite particles.
本発明の実施の形態に係る複合黒鉛質粒子に所定の外力が加えられると、導電性炭素質微粒子の一部または全部が黒鉛から脱離する。このため、この複合黒鉛質粒子を利用すれば、電極合剤スラリー調製時に電極合剤スラリー中に導電性炭素質微粒子を均一に分散させることができる。つまり、この複合黒鉛質粒子を用いれば、非水電解質二次電池の電極形成時において電極内に緻密な導電ネットワークを形成することができる。 <Characteristics of composite graphite particles>
When a predetermined external force is applied to the composite graphite particles according to the embodiment of the present invention, some or all of the conductive carbonaceous fine particles are detached from the graphite. For this reason, if this composite graphite particle | grain is utilized, electroconductive carbonaceous microparticles | fine-particles can be disperse | distributed uniformly in an electrode mixture slurry at the time of electrode mixture slurry preparation. That is, if this composite graphite particle is used, a dense conductive network can be formed in the electrode when forming the electrode of the nonaqueous electrolyte secondary battery.
以下、実施例および比較例を示して、本発明について詳述する。 <Examples and Comparative Examples>
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
(1)球状天然黒鉛粉末の平滑化処理
球状天然黒鉛粉末(平均粒径19.5μm,比表面積5.0m2/g,タップ密度1.02g/cm3,吸油量50.8mL/100g)を600g秤量し、ローターとインナーピースとの隙間を5mmとしたメカノフュージョン(ホソカワミクロン製AMS-Lab)内に投入した後、その球状天然黒鉛粉末を回転数2600rpmで20分間、平滑化処理した。以下、この球状天然黒鉛粉末を「平滑化球状天然黒鉛粉末」と称する。本明細書中において、平均粒径は、特に断りのない限り、累積粒径分布において体積分率50%時の粒子径(D50)を意味する。 <Manufacture of composite graphite particles>
(1) Smoothing treatment of spherical natural graphite powder Spherical natural graphite powder (average particle diameter 19.5 μm, specific surface area 5.0 m 2 / g, tap density 1.02 g / cm 3 , oil absorption 50.8 mL / 100 g) 600 g was weighed and put into a mechanofusion (AMS-Lab manufactured by Hosokawa Micron Co., Ltd.) in which the gap between the rotor and the inner piece was 5 mm, and the spherical natural graphite powder was smoothed at a rotational speed of 2600 rpm for 20 minutes. Hereinafter, this spherical natural graphite powder is referred to as “smoothed spherical natural graphite powder”. In the present specification, the average particle diameter means a particle diameter (D50) at a volume fraction of 50% in the cumulative particle size distribution unless otherwise specified.
平滑化球状天然黒鉛粉末(平均粒径19.4μm,比表面積5.0m2/g,タップ密度1.06g/cm3,吸油量41.6mL/100g)とアセチレンブラック(電気化学工業株式会社製デンカブラック(登録商標),粉状品)との質量比が100.0:0.5となるように平滑化球状天然黒鉛粉末とアセチレンブラックとを混ぜ合わせて600gの混合粉末を調製した。この600gの混合粉体を、ローターとインナーピースとの隙間を5mmとしたメカノフュージョンシステム(ホソカワミクロン製AMS-Lab)内に投入した後、その混合粉末を回転数2600rpmで5分間処理して、平滑化球状天然黒鉛粉末とアセチレンブラックとを複合化させた。以下、この複合化物を「一次複合粉末」と称する。 (2) Compounding of smoothed spherical natural graphite powder and acetylene black Smoothed spherical natural graphite powder (average particle size 19.4 μm, specific surface area 5.0 m 2 / g, tap density 1.06 g / cm 3 , oil absorption 41.6 mL / 100 g) and acetylene black (Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd., powdered product) and a smooth spherical natural graphite powder so that the mass ratio is 100.0: 0.5 600 g of mixed powder was prepared by mixing with acetylene black. 600 g of this mixed powder was put into a mechano-fusion system (AMS-Lab made by Hosokawa Micron) with a gap of 5 mm between the rotor and the inner piece, and then the mixed powder was processed at a rotational speed of 2600 rpm for 5 minutes to make it smooth Spherical natural graphite powder and acetylene black were combined. Hereinafter, this composite is referred to as “primary composite powder”.
一次複合粉末と石炭系ピッチ粉末(平均粒径20μm)との質量比が100.5:2.0となるように一次複合粉末と石炭系ピッチ粉末とを混ぜ合わせた後、その混合粉末を窒素気流下、1000℃で1時間、加熱処理して目的の複合黒鉛質粒子を得た。なお、この加熱処理中、石炭系ピッチ粉末は非黒鉛質炭素に変化した。また、加熱処理前後の質量変化からピッチ残炭率は50%であることを確認した。また、この複合黒鉛質粒子における平滑化球状天然黒鉛粉末、アセチレンブラックおよび非黒鉛質炭素の質量比は、98.5:0.5:1.0であった(表1参照)。 (3) Composite of primary composite powder and non-graphitic carbon Primary composite powder and coal so that the mass ratio of primary composite powder and coal-based pitch powder (average particle size 20 μm) is 100.5: 2.0. After mixing with the system pitch powder, the mixed powder was heat-treated at 1000 ° C. for 1 hour under a nitrogen stream to obtain the desired composite graphite particles. During this heat treatment, the coal-based pitch powder changed to non-graphitic carbon. Moreover, it confirmed that the pitch residual carbon rate was 50% from the mass change before and behind heat processing. Further, the mass ratio of the smoothed spherical natural graphite powder, acetylene black and non-graphitic carbon in the composite graphite particles was 98.5: 0.5: 1.0 (see Table 1).
(1)平均粒径(D50)の測定
レーザー回折/散乱式粒度分布計(株式会社堀場製作所製LA-910)を用いて光散乱回折法により複合黒鉛質粒子の体積基準の粒度分布を測定した。その後、得られた粒度分布を用いて体積分率50%時の粒子径(メジアン径)を求め、これを平均粒径とした。その結果、同平均粒径は、19.5μmであった(表1参照)。 <Characteristic evaluation of composite graphite particles>
(1) Measurement of average particle size (D50) The volume-based particle size distribution of the composite graphite particles was measured by a light scattering diffraction method using a laser diffraction / scattering particle size distribution analyzer (LA-910, manufactured by Horiba, Ltd.). . Then, using the obtained particle size distribution, the particle diameter (median diameter) at a volume fraction of 50% was determined, and this was used as the average particle diameter. As a result, the average particle diameter was 19.5 μm (see Table 1).
ユアサアイオニクス株式会社製カンタソープを用いて、上述の複合黒鉛質粒子の比表面積をBET1点法により求めた。その結果、上述の複合黒鉛質粒子のBET比表面積は、4.34m2/gであった(表2参照)。 (2) Evaluation of separation characteristics of acetylene black Using a canter soap manufactured by Yuasa Ionics Co., Ltd., the specific surface area of the composite graphite particles was determined by the BET one-point method. As a result, the BET specific surface area of the composite graphite particles was 4.34 m 2 / g (see Table 2).
(3-1)電極作製
上述の複合黒鉛質粒子にCMC(カルボキシメチルセルロースナトリウム)粉末を混合し、その混合粉末にSBR(スチレン-ブタジエンゴム)の水性分散液を加えた後、その混合物を攪拌して電極合剤スラリーを得た。ここで、CMC及びSBRは結着剤である。複合黒鉛質粒子、CMC及びSBRの配合比は、質量比で98.0:1.0:1.0であった。この電極合剤スラリーの固形分濃度は、55.7質量%であった。そして、この電極合剤スラリーを、厚み17μmの銅箔(集電体)上にドクターブレード法により塗布した(塗布量は10~11mg/cm2であった)。塗布液を乾燥させて塗膜を得た後、その塗膜を直径13mmのディスク状に打ち抜いた。その後、ディスクの密度が1.60g/cm3となるように、ディスクをプレス成形機により加圧して電極を作製した。 (3) Battery characteristics evaluation (3-1) Electrode preparation After mixing CMC (carboxymethylcellulose sodium) powder with the composite graphite particles described above, and adding an aqueous dispersion of SBR (styrene-butadiene rubber) to the mixed powder The mixture was stirred to obtain an electrode mixture slurry. Here, CMC and SBR are binders. The compounding ratio of the composite graphite particles, CMC and SBR was 98.0: 1.0: 1.0 by mass ratio. The solid content concentration of this electrode mixture slurry was 55.7% by mass. Then, this electrode mixture slurry was applied onto a copper foil (current collector) having a thickness of 17 μm by a doctor blade method (the coating amount was 10 to 11 mg / cm 2 ). After drying the coating solution to obtain a coating film, the coating film was punched into a disk shape having a diameter of 13 mm. Thereafter, the disk was pressed with a press molding machine so that the density of the disk was 1.60 g / cm 3 , thereby producing an electrode.
ポリオレフィン製セパレーターの両側に上述の電極と対極のLi金属箔とを配置して電極組立体を作製した。そして、その電極組立体の内部に電解液を注入してコイン型の非水試験セルを作製した。電解液の組成は、エチレンカーボネート(EC):エチルメチルカーボネート(EMC):ジメチルカーボネート(DMC):ビニレンカーボネート(VC):フルオロエチレンカーボネート(FEC):LiPF6=23:4:48:1:8:16(質量比)とした。 (3-2) Battery Preparation An electrode assembly was prepared by disposing the above electrode and a counter Li metal foil on both sides of a polyolefin separator. And the electrolyte solution was inject | poured in the inside of the electrode assembly, and the coin type non-aqueous test cell was produced. The composition of the electrolytic solution was ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC): vinylene carbonate (VC): fluoroethylene carbonate (FEC): LiPF 6 = 23: 4: 48: 1: 8 : 16 (mass ratio).
(3-3)放電容量、充放電効率および充放電サイクルの評価
23℃の環境温度下、この非水試験セルにおいて、先ず、0.325mAの電流値で、対極に対して電位差0(ゼロ)Vになるまで定電流ドープ(電極へのリチウムイオンの挿入、リチウムイオン二次電池の充電に相当)を行った後、さらに0Vを保持したまま、5μAになるまで定電圧で対極に対してドープを続け、ドープ容量を測定した。次に、0.325mAの定電流で、電位差1.5Vになるまで脱ドープ(電極からのリチウムイオンの離脱、リチウムイオン二次電池の放電に相当)を行い、脱ドープ容量を測定した。このときのドープ容量、脱ドープ容量は、この電極をリチウムイオン二次電池の負極として用いた時の充電容量、放電容量に相当するので、これらを充電容量、放電容量とした。本実施例に係る非水試験セルの放電容量は、367mAh/gであった(表2参照)。脱ドープ容量/ドープ容量の比は、リチウムイオン二次電池の放電容量/充電容量の比に相当するので、この比を充放電効率とした。本実施例に係る非水試験セルの充放電効率は、93.3%であった(表2参照)。[Correction 21.05.2013 based on Rule 91]
(3-3) Evaluation of discharge capacity, charge / discharge efficiency and charge / discharge cycle In this non-aqueous test cell at an environmental temperature of 23 ° C., first, a potential difference of 0 (zero) with respect to the counter electrode at a current value of 0.325 mA After constant current doping until V is reached (equivalent to insertion of lithium ions into the electrode and charging of the lithium ion secondary battery), while maintaining 0 V, the constant electrode is doped with constant voltage until 5 μA Then, the doping capacity was measured. Next, dedoping (corresponding to detachment of lithium ions from the electrode and discharging of the lithium ion secondary battery) was performed at a constant current of 0.325 mA until the potential difference became 1.5 V, and the dedoping capacity was measured. The doping capacity and the dedoping capacity at this time correspond to the charging capacity and discharging capacity when this electrode is used as the negative electrode of the lithium ion secondary battery, and these were used as the charging capacity and discharging capacity. The discharge capacity of the non-aqueous test cell according to this example was 367 mAh / g (see Table 2). Since the ratio of dedoping capacity / doping capacity corresponds to the ratio of discharge capacity / charge capacity of the lithium ion secondary battery, this ratio was defined as charge / discharge efficiency. The charge / discharge efficiency of the non-aqueous test cell according to this example was 93.3% (see Table 2).
「(2)平滑化球状天然黒鉛粉末とアセチレンブラックとの複合化」を行わず、「(3)一次複合粉末と非黒鉛質炭素との複合化」において平滑化球状天然黒鉛粉末と石炭系ピッチ粉末(平均粒径20μm)との質量比が100.0:2.0となるように平滑化球状天然黒鉛粉末と石炭系ピッチ粉末とを混ぜ合わせた以外は、実施例1と同様にして対照粉末を得、実施例1と同様にして対照粉末の特性評価を行った。この対照粉末において、平滑化球状天然黒鉛粉末、アセチレンブラックおよび非黒鉛質炭素の質量比は、99.0:0.0:1.0であった(表1参照)。 (Comparative Example 1)
“(2) Smoothing spherical natural graphite powder and acetylene black are not composited”, and “(3) Primary composite powder and non-graphitic carbon are composited”. The control was carried out in the same manner as in Example 1 except that the smoothed spherical natural graphite powder and the coal-based pitch powder were mixed so that the mass ratio with the powder (average particle size 20 μm) was 100.0: 2.0. A powder was obtained, and the control powder was evaluated in the same manner as in Example 1. In this control powder, the mass ratio of the smoothed spherical natural graphite powder, acetylene black and non-graphitic carbon was 99.0: 0.0: 1.0 (see Table 1).
「(2)平滑化球状天然黒鉛粉末とアセチレンブラックとの複合化」において平滑化球状天然黒鉛粉末とアセチレンブラックとの質量比が100.0:1.0となるように平滑化球状天然黒鉛粉末とアセチレンブラックとを混ぜ合わせ、「(3)一次複合粉末と非黒鉛質炭素との複合化」を行わなかった以外は、実施例1と同様にして対照粉末を得、実施例1と同様にして対照粉末の特性評価を行った。この対照粉末における平滑化球状天然黒鉛粉末、アセチレンブラックおよび非黒鉛質炭素の質量比は、99.0:1.0:0.0であった(表1参照)。 (Comparative Example 2)
Smoothed spherical natural graphite powder so that the mass ratio of smoothed spherical natural graphite powder and acetylene black is 100.0: 1.0 in “(2) Composite of smoothed spherical natural graphite powder and acetylene black” And acetylene black were mixed, and a control powder was obtained in the same manner as in Example 1 except that “(3) Composite of primary composite powder and non-graphitic carbon” was not performed. The control powder was characterized. The mass ratio of the smoothed spherical natural graphite powder, acetylene black and non-graphitic carbon in this control powder was 99.0: 1.0: 0.0 (see Table 1).
Claims (10)
- 黒鉛と、
前記黒鉛に直接的に付着する導電性炭素質微粒子と、
前記導電性炭素質微粒子および前記黒鉛に少なくとも部分的に付着する非黒鉛質炭素と
を備える、複合黒鉛質粒子。 Graphite,
Conductive carbonaceous fine particles directly attached to the graphite;
Composite graphite particles comprising the conductive carbonaceous fine particles and non-graphitic carbon that adheres at least partially to the graphite. - 所定の外力が加えられると、前記導電性炭素質微粒子の一部または全部が前記黒鉛から脱離する
請求項1に記載の複合黒鉛質粒子。 The composite graphitic particles according to claim 1, wherein a part or all of the conductive carbonaceous fine particles are detached from the graphite when a predetermined external force is applied. - 「前記外力が加えられた後の比表面積値(m2/g)」に対する「前記外力が加えられる前の比表面積値(m2/g)」の比が1.10以上である
請求項2に記載の複合黒鉛質粒子。 The ratio of the “specific surface area value before the external force is applied (m 2 / g)” to the “specific surface area value after the external force is applied (m 2 / g)” is 1.10 or more. 2. Composite graphite particles described in 1. - 前記黒鉛は、球状であり、円形度が0.92以上であり、C-K端X線吸収スペクトルにおけるピーク強度比の入射角依存性S60/0が0.7以下である
請求項1から3のいずれかに記載の複合黒鉛質粒子。 The graphite is spherical, has a circularity of 0.92 or more, and an incident angle dependency S 60/0 of a peak intensity ratio in a CK edge X-ray absorption spectrum is 0.7 or less. 4. The composite graphite particle according to any one of 3. - 前記黒鉛に対する前記導電性炭素質微粒子の質量割合が0.3%以上2.0%以下の範囲内であり、
前記黒鉛と前記導電性炭素質微粒子との和に対する前記非黒鉛質炭素の質量割合が0.8%以上15.0%以下の範囲内である
請求項1から4のいずれかに記載の複合黒鉛質粒子。 The mass ratio of the conductive carbonaceous fine particles to the graphite is in the range of 0.3% to 2.0%,
The composite graphite according to any one of claims 1 to 4, wherein a mass ratio of the non-graphitic carbon to a sum of the graphite and the conductive carbonaceous fine particles is in a range of 0.8% to 15.0%. Particle. - 導電性炭素質微粒子を直接的に黒鉛に付着させて一次複合粒子を調製する一次複合粒子調製工程と、
前記一次複合粒子に非黒鉛質炭素を部分的に又は全体的に付着させて複合黒鉛質粒子を調製する複合黒鉛質粒子調製工程と
を備える、複合黒鉛質粒子の製造方法。 A primary composite particle preparation step of preparing primary composite particles by directly attaching conductive carbonaceous fine particles to graphite;
A method for producing composite graphite particles, comprising: a composite graphite particle preparation step of preparing composite graphite particles by partially or entirely attaching non-graphitic carbon to the primary composite particles. - 前記複合黒鉛質粒子調製工程では、前記一次複合粒子と非黒鉛質炭素の原料粉末とが混合された後に加熱される
請求項6に記載の複合黒鉛質粒子の製造方法。 The method for producing composite graphite particles according to claim 6, wherein in the composite graphite particle preparation step, the primary composite particles and the non-graphitic carbon raw material powder are mixed and then heated. - 請求項6または7に記載の複合黒鉛質粒子の製造方法により得られる複合黒鉛質粒子。 Composite graphite particles obtained by the method for producing composite graphite particles according to claim 6 or 7.
- 請求項1、2、3、4、5及び8のいずれかに記載の複合黒鉛質粒子を活物質とする電極。 An electrode using the composite graphite particles according to any one of claims 1, 2, 3, 4, 5, and 8 as an active material.
- 請求項9に記載の電極を備える非水電解質二次電池。 A nonaqueous electrolyte secondary battery comprising the electrode according to claim 9.
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JP2016154100A (en) * | 2015-02-20 | 2016-08-25 | トヨタ自動車株式会社 | Nonaqueous electrolyte secondary battery and method for manufacturing the same |
JP2019175776A (en) * | 2018-03-29 | 2019-10-10 | 三菱ケミカル株式会社 | Negative electrode material for non-aqueous secondary battery and manufacturing method thereof, negative electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
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KR102588919B1 (en) * | 2022-09-16 | 2023-10-16 | 주식회사 엘지에너지솔루션 | Negative electrode for lithium secondary battery and lithium secondary battery containing the same |
WO2024058588A1 (en) * | 2022-09-16 | 2024-03-21 | 주식회사 엘지에너지솔루션 | Negative electrode for lithium secondary battery and lithium secondary battery comprising same |
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