WO2011034152A1 - リチウム二次電池の負極用炭素材料及びその製造方法 - Google Patents
リチウム二次電池の負極用炭素材料及びその製造方法 Download PDFInfo
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- WO2011034152A1 WO2011034152A1 PCT/JP2010/066096 JP2010066096W WO2011034152A1 WO 2011034152 A1 WO2011034152 A1 WO 2011034152A1 JP 2010066096 W JP2010066096 W JP 2010066096W WO 2011034152 A1 WO2011034152 A1 WO 2011034152A1
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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
- C01B32/20—Graphite
- C01B32/205—Preparation
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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
- 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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/77—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by unit-cell parameters, atom positions or structure diagrams
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to a carbon material used as a negative electrode of a lithium secondary battery and a method for producing the same.
- lithium secondary batteries are lighter and have higher input / output characteristics than nickel cadmium batteries, nickel metal hydride batteries, and lead batteries, which are conventional secondary batteries.
- this type of battery is configured by a positive electrode containing lithium capable of reversible intercalation of lithium and a negative electrode made of a carbon material facing each other with a non-aqueous electrolyte interposed therebetween. Therefore, this type of battery is assembled in a discharged state and cannot be discharged unless it is charged.
- the charge / discharge reaction will be described by taking as an example a case where a lithium cobaltate (LiCoO 2 ) is used as the positive electrode, a carbon material is used as the negative electrode, and a non-aqueous electrolyte containing a lithium salt is used as the electrolyte.
- a lithium cobaltate LiCoO 2
- a carbon material is used as the negative electrode
- a non-aqueous electrolyte containing a lithium salt is used as the electrolyte.
- Carbon materials used as negative electrode materials for lithium secondary batteries are generally divided roughly into graphite and amorphous materials.
- the graphite-based carbon material has an advantage that the energy density per unit volume is higher than that of the amorphous carbon material. Accordingly, graphite-based carbon materials are generally used as negative electrode materials in lithium ion secondary batteries for mobile phones and notebook computers that are compact but require a large charge / discharge capacity.
- Graphite has a structure in which hexagonal network surfaces of carbon atoms are regularly stacked, and lithium ion insertion / extraction reaction proceeds at the edge of the hexagonal network surface during charge / discharge.
- this type of battery has been actively studied as a power storage device for automobiles, industrial use, and power supply infrastructure in recent years. Higher reliability is required than when it is used for personal computers.
- reliability is a characteristic related to the lifetime, even when the charge / discharge cycle is repeated, stored in a state charged to a predetermined voltage, or charged continuously at a constant voltage (floating). Even when charged), the charge / discharge capacity and internal resistance hardly change (are not easily deteriorated).
- the life characteristics of lithium ion secondary batteries that have been used in conventional mobile phones and notebook computers are largely dependent on the anode material.
- the reason is that, in principle, it is impossible to make the charge / discharge efficiency of the positive electrode reaction (Formula 2) and the negative electrode reaction (Formula 3) exactly the same, and the charge / discharge efficiency is lower in the negative electrode.
- the charge / discharge efficiency is the ratio of the electric capacity that can be discharged to the electric capacity consumed for charging.
- the positive electrode potential in the end-of-discharge state shifts in a more noble direction than the original potential before charge / discharge, while the negative electrode potential also has a noble direction than the original potential before charge / discharge. Will be transferred to. This is because all of the lithium released during the charging process of the positive electrode is not occluded (does not return) during discharging, so the potential that has shifted in the noble direction during the charging process shifts in the naive direction during the discharging process.
- the discharge of the lithium secondary battery is completed when the battery voltage (that is, the difference between the positive electrode potential and the negative electrode potential) reaches a predetermined value (discharge end voltage). This is because if the potential becomes noble, the negative electrode potential also shifts in the noble direction accordingly.
- this type of battery can be obtained within a predetermined voltage range (within a discharge end voltage and a charge end voltage range) by changing the operating region of the positive / negative electrode capacity when the charge / discharge cycle is repeated.
- a reaction mechanism of capacity degradation has also been reported by academic societies and the like (for example, Non-Patent Document 1 and Non-Patent Document 2).
- the positive and negative potentials once changed in the operating region are irreversible, cannot be restored in principle, and lack of capacity recovery means also exacerbates this problem.
- the reaction mechanism of capacity deterioration that occurs when the above-described charge / discharge cycle is repeated is basically the same as each reaction mechanism of capacity deterioration when the battery is stored in the charged state or capacity deterioration when the battery is floating charged. The same is true.
- the capacity lost due to side reactions / competitive reactions occurring in the charged state that is, the self-discharge amount is larger in the negative electrode than in the positive electrode.
- the battery capacity after storage deteriorates when the operating region changes before and after storage (for example, Non-Patent Document 3).
- the difference in the self-discharge rate between the positive and negative electrodes in the charged state is similar to the difference in the charge and discharge efficiency between the positive and negative electrodes described above. This is due to the higher rate of side reactions and competitive reactions that occur.
- the leakage current on the negative electrode side becomes larger than the leakage current on the positive electrode side, so that the negative electrode potential shifts to a direction in which the leakage current decreases, that is, a noble direction. Shifts in the direction of increasing, that is, the noble direction. Even when floating charging is performed in this manner, the operating areas of the positive and negative electrode capacities change irreversibly, resulting in a problem that the battery capacity deteriorates.
- the present invention is to improve the capacity deterioration of the lithium secondary battery as described above, and its purpose is to reduce the capacity deterioration due to repeated charge / discharge cycles, storage in a charged state, and floating charge.
- the present invention intends to provide a negative electrode material for lithium secondary batteries for automobiles, industrial use, and power storage infrastructure that requires high reliability.
- a first aspect of the invention is the crystallite size L in the c-axis direction calculated from the (112) diffraction line obtained by the X-ray wide angle diffraction method ( 112) is a 2.0 ⁇ 4.2 nm, and, in the Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms, the half width of the peaks present in the wavelength region of 1580 cm -1 ⁇ 100 cm -1 Artificial graphite for negative electrodes of lithium secondary batteries having ⁇ G of 15 to 19 cm ⁇ 1 .
- a second aspect of the invention according to the present application is artificial graphite for a negative electrode of a lithium secondary battery obtained through a step of performing a heat treatment after a heavy oil composition is subjected to a coking treatment by a delayed coking process.
- the crude oil composition is artificial graphite for negative electrodes of lithium secondary batteries having a normal paraffin content of 5 to 20 wt% and an aromatic index fa determined by the Knight method of 0.3 to 0.65.
- the third aspect of the present invention relates to a step of obtaining a carbon fine particle material by carbonizing and pulverizing the heat treatment step at 1500 ° C. or lower, and a maximum ultimate temperature of the carbon fine particle material in an inert gas atmosphere. And heating to 2200 to 2600 ° C. to obtain the artificial graphite, the artificial graphite for a lithium secondary battery negative electrode.
- a fourth aspect of the invention according to the present application is a method for producing graphite for a lithium secondary battery negative electrode comprising a step of coke treatment of a heavy oil composition by a delayed coking process and then heat treatment.
- the oil composition is a method for producing artificial graphite for a negative electrode of a lithium secondary battery having a normal paraffin content of 5 to 20 wt% and an aromatic index fa determined by the Knight method of 0.3 to 0.65.
- a fifth aspect of the invention according to the present application is artificial graphite for a lithium secondary battery negative electrode obtained by the above production method.
- a positive electrode including lithium capable of reversible lithium intercalation, and the lithium secondary according to claim 1, claim 2, 3 or claim 5.
- a lithium secondary battery including a negative electrode including artificial graphite for a battery negative electrode and a non-aqueous electrolyte.
- the crystallite size L in the c-axis direction calculated from the (112) diffraction line obtained by the X-ray wide angle diffraction method (112 ) is a 2.0 ⁇ 4.2 nm, and, in the Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 angstroms, a peak of the half width existing in the wavelength region of 1580cm -1 ⁇ 100cm -1 ⁇ wherein the carbon material G is 15 ⁇ 19cm -1, despite very high surface crystallinity of the carbon material, it lies in lower crystallinity of the inner bulk.
- carbon materials obtained by carbonizing and graphitizing certain types of organic polymer compounds differ in the degree of graphitization of the surface layer and the degree of graphitization inside the bulk, and the surface layer develops crystals faster (for example, non-patented Literature 4 and Non-patent literature 5).
- the carbon material according to the first and second aspects of the present application also utilizes this property.
- a predetermined heavy oil composition is subjected to coking treatment, and the obtained raw coke is calcined at about 1400 ° C., and then has a predetermined particle size.
- a process of pulverizing and classifying and graphitizing at about 2400 ° C. is known (for example, Patent Document 1).
- Graphite powder that has been graphitized after pulverizing and classifying such raw coke or calcined coke also has different crystallinity on the particle surface (surface layer) and crystallinity on the inside of the particle (bulk). The degree is generally higher.
- the crystallinity of the particle surface in the Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 Angstroms, with a peak of half width .DELTA..nu G existing in the wavelength region of 1580 cm -1 ⁇ 100 cm -1, the internal particle crystals
- the degree of conversion can be evaluated by the crystallite size L (112) calculated from the (112) diffraction line obtained by the X-ray wide angle diffraction method. It is generally known that ⁇ G has a smaller half-value width as the integrity of the local graphite crystal on the particle surface is higher (for example, Non-Patent Document 6).
- a high degree of graphitization of the surface layer means that the exposed region of the crystallite edge in the surface layer is small.
- a crystallite edge has a large number of dangling bonds, that is, many states of localized electrons that are not saturated with valence electron bonds and exist without a bonding partner.
- the present inventors have found that these localized electrons are present on the surface of the negative electrode carbon material in the charging process, that is, at the interface where the electrolyte and the carbon material are in contact. It has been found that the charging / discharging efficiency of the negative electrode is reduced by the catalytic action and side reactions / competitive reactions caused by reductive decomposition of the electrolyte.
- the present inventors can greatly improve the charge / discharge efficiency when the crystallinity of the particle surface is highly developed, that is, when ⁇ G of Raman spectrum analysis is smaller than a predetermined value. I found out.
- ⁇ G exceeds 19 cm ⁇ 1 , side reactions and competitive reactions due to reductive decomposition of the electrolyte are likely to occur rapidly on the particle surface, which is not preferable.
- ⁇ G is preferably as small as possible.
- the inventors have made various studies on the synthesis method, and as a result, it was impossible to obtain a product having a value of less than 15 cm ⁇ 1.
- ⁇ G is defined as 15 to 19 cm ⁇ 1 .
- the negative electrode carbon material according to the invention has a crystallite size L (112) calculated from a (112) diffraction line obtained by an X-ray wide angle diffraction method of 2.0 to 4.2 nm. It is prescribed.
- L (112) calculated from a (112) diffraction line obtained by an X-ray wide angle diffraction method of 2.0 to 4.2 nm. It is prescribed.
- the electrolyte solvent molecules are also taken together and co-intercalated, and reduced and decomposed between the crystal layers.
- the phenomenon is generally known (for example, Non-Patent Document 7).
- the co-intercalated solvent is easily reduced and decomposed between the crystal layers of graphite, so that the charge / discharge efficiency is inevitably lowered.
- the graphite powder synthesized by the manufacturing method described in Patent Document 1 that is, a method in which raw coke or calcined coke is pulverized and classified and then graphitized, has a large degree of crystallinity inside the particle (bulk). If it becomes too much, that is, if L (112) exceeds 4.2 nm, the above-mentioned co-intercalation phenomenon is likely to occur in the charging process, and the co-intercalated solvent is reduced and decomposed between the crystal layers as described above. As a result, the charge / discharge efficiency is remarkably lowered, which is not preferable.
- Non-Patent Document 8 It is generally known that the chargeable / dischargeable capacity of the negative electrode carbon material is smaller as the crystallite size calculated by the X-ray wide angle diffraction method is smaller (for example, Non-Patent Document 8). This tendency is similarly recognized for the carbon material defined in the first aspect of the present invention. That is, when L (112) is smaller than 2.0 nm, the chargeable / dischargeable capacity becomes small, which is not preferable.
- the crystallite size L (112) calculated from the (112) diffraction line obtained by the X-ray wide angle diffraction method is 2.0 to 4 A point of .2 nm is also specified.
- the electrochemical characteristics as a negative electrode of graphite powder in which L (112) is 2.0 to 4.2 nm and ⁇ G specified as described above is 15 to 19 cm ⁇ 1 are reversible.
- the chargeable / dischargeable capacity is large, and side reactions and competitive reactions due to co-intercalation of solvent molecules and dangling bonds on the particle surface are suppressed even during the charging process.
- the second aspect of the invention according to the present application defines a raw material oil composition for obtaining the carbon material defined in the first aspect. That is, the second aspect of the invention according to the present application is artificial graphite for a lithium secondary battery negative electrode obtained by subjecting a heavy oil composition to a coking treatment by a delayed coking process, followed by a heat treatment step,
- the heavy oil composition is artificial graphite for a negative electrode of a lithium secondary battery having a normal paraffin content of 5 to 20 wt% and an aromatic index fa determined by the Knight method of 0.3 to 0.65.
- the feature of the carbon material defined in the first aspect of the invention related to the present application is that the degree of graphitization of the particle surface (surface layer) is extremely higher than the degree of graphitization inside the particle (bulk). is there.
- raw coke or calcined coke is used.
- a method of pulverizing and classifying, adjusting the particle size, and then graphitizing is generally used.
- the degree of graphitization on the particle surface (surface layer) of the obtained graphite powder can be made higher than the degree of graphitization inside the particles (bulk).
- raw coke refers to the pyrolysis of heavy oil in a delayed coker
- calcined coke refers to carbonization of raw coke in an industrial furnace to remove moisture and volatiles to develop a crystal structure. It shall refer to something.
- the graphite powder obtained by pulverizing after graphitization gives mechanical energy by pulverization to the particle surface, so that the graphitization degree on the particle surface is lower than the graphitization degree inside the particle. For this reason, it is not possible to obtain a graphite powder that achieves the physical properties defined in the first aspect of the present invention.
- Unstructured carbon refers to carbon that is not incorporated into the carbon hexagonal network plane, and its characteristics are that the carbon hexagon gradually increases with increasing processing temperature while interfering with the growth and selective orientation of adjacent carbon crystallites. It is a carbon atom that is incorporated into the mesh plane.
- the present inventors have determined that the crystal structure of raw coke or calcined coke to be pulverized can be latticed on its surface layer even when mechanical energy is applied by pulverization. It was found that a graphite powder with a highly developed crystal structure of the surface layer can be obtained by controlling the structure so that defects and unstructured carbon are difficult to be introduced. Further, the present inventors have found that this structure can be realized by controlling the production method of raw coke and calcined coke.
- the structure is a crystalline structure having a selective orientation composed of crystallites in which hexagonal mesh planes of relatively small sizes are stacked. If the crystal structure is such a structure, even when mechanical energy is applied by crushing, the size of the hexagonal mesh plane to be stacked is small, so the probability of cracking between adjacent crystallites increases, and the hexagonal mesh It is possible to greatly reduce the probability that the plane will be cleaved and the probability that the hexagonal plane will crack.
- the structure of the crystal structure of raw coke or calcined coke to be crushed is composed of crystallites in which relatively large hexagonal mesh planes are stacked, the mechanical energy by crushing is relatively large.
- the crystal structure of crushed raw coke or calcined coke is a structure composed of crystallites composed of relatively small hexagonal mesh planes. It can also be said that the manufacturing method for this is specifically defined.
- the inventors In order to produce raw coke and calcined coke having such a structure by a delayed coking process suitable for mass production, the inventors have to control the physical properties and coking conditions of the heavy oil composition used as a raw material. As a result, the inventors have found that the second aspect of the invention according to the present application has been completed.
- the physical properties of the heavy oil composition used as a raw material are characterized by a normal paraffin content of 5 to 20 wt% and an aromatic index fa calculated by a specific method of 0.3 to 0. .65.
- a heavy oil component that produces a good bulk mesophase and a function of limiting the size of the hexagonal mesh plane laminate constituting the mesophase when the bulk mesophase is polycondensed and carbonized and solidified It is effective to use a feed oil composition containing both heavy oil components capable of producing a gas.
- the heavy oil component that produces a good bulk mesophase is a component that gives an aromatic index fa of 0.3 to 0.65, and the heavy oil component that can generate gas is 5 to 20 wt% of the normal paraffin content. It is a component equivalent to.
- fa is the aromatic carbon fraction (fa) determined by the Knight method.
- the distribution of carbon is divided into three components (A1, A2, A3) as a spectrum of aromatic carbon by the 13 C-NMR method.
- A1 is the number of carbon atoms inside the aromatic ring, half of the aromatic carbon that is not substituted with the substituted aromatic carbon (corresponding to a peak of about 40-60 ppm of 13 C-NMR), and A2 is substituted no other half of the aromatic carbons (corresponding to the peak of about 60 ⁇ 80 ppm of 13 C-NMR),
- the 13 C-NMR method is the best method for quantitatively determining fa, which is the most basic amount of chemical structural parameters of pitches.
- the literature (“Pitch Characterization II. Chemical Structure” Yokono, Sanada, (Carbon, 1981 (No. 105), p73-81)).
- the content of normal paraffin in the raw material oil composition means a value measured by a gas chromatograph equipped with a capillary column. Specifically, after testing with a normal paraffin standard substance, the sample of the non-aromatic component separated by the elution chromatography method is passed through a capillary column and measured. The content rate based on the total mass of the raw material oil composition can be calculated from this measured value.
- the yield of coke from the heavy oil composition becomes extremely low, and a good bulk mesophase cannot be formed. It is not preferable because the tissue is difficult to develop. If it exceeds 0.65, a large number of mesophases are generated abruptly in the matrix during the production process of raw coke, and abrupt coalescence of mesophases is mainly repeated rather than single growth of mesophases. For this reason, the rate of coalescence between the mesophases is faster than the rate of gas generation due to the normal paraffin-containing component, which makes it impossible to limit the hexagonal mesh plane of the bulk mesophase to a small size.
- the aromatic index fa of the heavy oil composition is preferably 0.3 to 0.65.
- the aromatic index fa is such that the density D of the heavy oil composition is 0.91 to 1.02 g / cm 3 and the viscosity V is 10 to 220 mm 2 / sec.
- Particularly preferred are heavy oil compositions having a fa of 0.3 to 0.65.
- the normal paraffin component appropriately contained in the heavy oil composition plays an important role in limiting the size of the bulk mesophase to a small size by generating gas during the coking process as described above. ing.
- This gas generation also has a function of uniaxially orienting adjacent mesophases limited to a small size and selectively orienting the entire system. For this reason, although the size of the mesophase is limited to a small size, when the pulverized particles are carbonized and graphitized, the crystal structure of the particle surface layer is particularly easily developed. It is an essential component for obtaining an effect.
- the normal paraffin content of the normal paraffin-containing component is less than 5 wt%, the mesophase grows more than necessary and a huge carbon hexagonal plane is formed, which is not preferable.
- the normal paraffin content is preferably 5 to 20 wt%.
- This feedstock oil includes fluid catalytic cracking oil bottom oil (FCC DO), heavy oil with advanced hydrodesulfurization treatment, vacuum residue (VR), coal liquefied oil, coal solvent extraction oil, atmospheric pressure Residual oil, shell oil, tar sand bitumen, naphthatar pitch, coal tar pitch, ethylene bottom oil, heavy oil obtained by hydrotreating these, and the like.
- FCC DO fluid catalytic cracking oil bottom oil
- VR vacuum residue
- coal liquefied oil coal solvent extraction oil
- atmospheric pressure Residual oil shell oil, tar sand bitumen, naphthatar pitch, coal tar pitch, ethylene bottom oil, heavy oil obtained by hydrotreating these, and the like.
- a heavy oil subjected to a high degree of hydrodesulfurization treatment including an appropriate saturated component and an appropriate normal paraffin in the component can be preferably used.
- the blending ratio may be appropriately adjusted according to the properties of the raw material oil to be used. The properties of the raw material oil vary depending on the type of crude oil and the processing conditions until the raw material oil is obtained from the crude oil.
- the heavy oil composition according to this embodiment is coked, then carbonized and graphitized as necessary, and used as a carbon material for a negative electrode of a lithium secondary battery.
- a delayed coking method is preferable. More specifically, raw coke is obtained by heat-treating the raw oil composition with a delayed coker under pressurized conditions. At this time, in order to obtain the effect of the present invention, the conditions of the delayed coker are preferably a pressure of 0.1 to 0.8 MPa and a temperature of 400 to 600 ° C.
- the reason why a preferable range is defined for the pressure is that the release rate of the gas generated from the component containing normal paraffin to the outside of the system can be limited by the pressure.
- the residence time of the generated gas in the system is an important control for determining the size of the hexagonal mesh plane. It becomes a parameter.
- the preferable range is defined for the temperature is that it is an important temperature for growing the mesophase from the heavy oil adjusted to obtain the effect of the present invention.
- the graphite powder produced by a predetermined method is then used. Even if there is only a low graphitization degree of the surface layer, or if it is not graphitized until the crystallite size L (112) exceeds 4.2 nm, the degree of graphitization of the surface layer will not develop. It is not preferable.
- the second aspect of the invention according to the present application is artificial graphite for a lithium secondary battery negative electrode obtained by subjecting a heavy oil composition to a coking treatment by a delayed coking process and then a heat treatment step.
- the heavy oil composition has a normal paraffin content of 5 to 20 wt% and an aromatic index fa determined by the Knight method in the range of 0.3 to 0.65.
- the heat treatment is a heat treatment for obtaining a stable quality graphite material by heating the raw material powder to remove volatile components, and by dehydration, thermal decomposition, and solid phase graphitization reaction, preferably 1500 ° C. or less, preferably , Carbonized at 500 to 1500 ° C., and then graphitized at a temperature of 2000 ° C. or higher, preferably the maximum temperature of 2200 to 2600 ° C., which is the graphitization start temperature, and refers to a series of heat treatment processes.
- the heavy oil composition subjected to the coking treatment is subjected to 500 to 1500 in an inert gas atmosphere such as nitrogen or argon.
- an inert gas atmosphere such as nitrogen or argon.
- An example is a heat treatment process in which carbonization is performed at 0 ° C., pulverization and classification to an average particle diameter of 50 ⁇ m or less, and then graphitization is performed at a maximum temperature of 2200 to 2600 ° C. in an inert gas atmosphere.
- the graphite powder produced by such a method is less prone to introduce lattice strain in the crystalline region of the particle surface and is measured by Raman spectroscopy. This is because it is possible to suppress the ⁇ G to be reduced.
- the reason why the particle size is 50 ⁇ m or less is that it is a general particle size required for this type of graphite material.
- the method for producing a negative electrode for a lithium secondary battery is not particularly limited.
- a method in which (negative electrode mixture) is pressure-molded to a predetermined size is exemplified.
- a carbon material to which the invention according to the present application is applied, a binder (binder), a conductive auxiliary agent, and the like are kneaded and slurried in an organic solvent, and the slurry is a current collector such as a copper foil.
- a method in which a coated and dried (negative electrode mixture) is rolled and cut into a predetermined size.
- binder examples include polyvinylidene fluoride, polytetrafluoroethylene, and SBR (styrene-butadiene rubber).
- the content of the binder in the negative electrode mixture may be appropriately set as necessary in terms of battery design, from about 1 to 30 parts by mass with respect to 100 parts by mass of the carbon material.
- Examples of the conductive assistant include carbon black, graphite, acetylene black, conductive indium-tin oxide, or conductive polymers such as polyaniline, polythiophene, and polyphenylene vinylene.
- the amount of the conductive aid used is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the carbon material.
- organic solvent examples include dimethylformamide, N-methylpyrrolidone, isopropanol, toluene and the like.
- the carbon material, the binder, and, if necessary, the conductive aid and the organic solvent known devices such as a screw type kneader, a ribbon mixer, a universal mixer, a planetary mixer and the like can be used.
- the mixture is formed by roll pressing or press pressing, and the pressure at this time is preferably about 100 to 300 MPa.
- the material of the current collector can be used without particular limitation as long as it does not form an alloy with lithium.
- copper, nickel, titanium, stainless steel, etc. can be mentioned.
- the shape of the current collector can be used without any particular limitation.
- Examples of the current collector include a belt-like shape such as a foil shape, a perforated foil shape, and a mesh shape.
- a porous material such as porous metal (foamed metal) or carbon paper can also be used.
- the method of applying the slurry to the current collector is not particularly limited, for example, metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method, Known methods such as a screen printing method and a die coater method can be used. After coating, it is common to perform a rolling process using a flat plate press, a calender roll, or the like as necessary. Further, the integration of the negative electrode material slurry formed into a sheet shape, a pellet shape, and the like with the current collector can be performed by a known method such as a roll, a press, or a combination thereof.
- the lithium secondary battery using the carbon material for a negative electrode of a lithium ion secondary battery according to the present embodiment is arranged such that, for example, the negative electrode and the positive electrode manufactured as described above face each other with a separator interposed therebetween. It can be obtained by injecting a liquid.
- the active material used for the positive electrode is not particularly limited. For example, a metal compound, metal oxide, metal sulfide, or conductive polymer material that can be doped or intercalated with lithium ions may be used.
- lithium cobaltate LiCoO 2
- lithium nickelate LiNiO 2
- lithium manganate LiMn 2 O 4
- lithium vanadium compound V 2 O 5, V 6 O 13, VO 2, MnO 2, TiO 2, MoV 2 O 8, TiS 2, V 2 S 5, VS 2, MoS 2, MoS 3, Cr 3 O 8, Cr 2 O 5, olivine-type LiMPO 4 (M: Co, Ni , Mn, Fe), polyacetylene, polyaniline, polypyrrole Polythiophene, mention may be made of conductive polymers such as polyacene, porous carbon or the like and mixtures thereof.
- the separator for example, a nonwoven fabric, a cloth, a microporous film, or a combination thereof having a polyolefin such as polyethylene or polypropylene as a main component can be used.
- a separator when it is set as the structure where the positive electrode and negative electrode of the lithium ion secondary battery to produce are not in direct contact, it is not necessary to use a separator.
- electrolyte and electrolyte used for the lithium secondary battery known organic electrolytes, inorganic solid electrolytes, and polymer solid electrolytes can be used.
- organic electrolyte is preferable from the viewpoint of electrical conductivity.
- organic electrolyte examples include dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol phenyl ether, and other ethers, N-methylformamide, N, N-dimethylformamide, N Amides such as ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, sulfur-containing compounds such as dimethylsulfoxide and sulfolane, methyl ethyl ketone, Dialkyl ketones such as methyl isobutyl ketone, cyclic ethers such as tetrahydrofuran and 2-methoxytetrahydrofuran, ethylene carbonate , Cyclic carbonates such as butylene carbonate, propylene carbonate,
- lithium salts can be used as the solute of these solvents.
- Commonly known lithium salts include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCl, LiCF 3 SO 3 , LiCF 3 CO 2 , LiN (CF 3 SO 2 ) 2, LiN (C 2 F 5 SO 2 ) 2 and the like.
- polymer solid electrolyte examples include a polyethylene oxide derivative and a polymer containing the derivative, a polypropylene oxide derivative and a polymer containing the derivative, a phosphate ester polymer, a polycarbonate derivative and a polymer containing the derivative.
- the structure of the lithium ion secondary battery is not particularly limited, a wound electrode group in which a positive electrode and a negative electrode formed in a strip shape are wound in a spiral shape through a separator is inserted into a battery case and sealed.
- a structure in which a laminated electrode plate group in which a positive electrode and a negative electrode formed in a flat plate shape are sequentially laminated via a separator is enclosed in an exterior body.
- the lithium secondary battery is used as, for example, a paper-type battery, a button-type battery, a coin-type battery, a stacked battery, a cylindrical battery, a rectangular battery, or the like.
- the lithium secondary battery using the carbon material according to the invention of the present application can ensure a high degree of reliability as compared with a lithium secondary battery using a conventional carbon material. Specifically, it can be used for industrial purposes such as for hybrid vehicles, plug-in hybrid vehicles, electric vehicles, and power storage for grid infrastructure.
- the X-ray diffractometer was D8 ADVANCE (encapsulated tube type) manufactured by Bruker-AXS, the X-ray source was CuK ⁇ ray (using K ⁇ filter Ni), and the applied voltage and current to the X-ray tube were 40 kV and 40 mA.
- the obtained diffraction pattern was also analyzed by a method based on JIS R7651 (2007). Specifically, the measurement data is subjected to smoothing treatment, background removal, absorption correction, polarization correction, and Lorentz correction, and the peak position and value width of the (422) diffraction line of the Si standard sample are used. (112) The diffraction line was corrected and the crystallite size was calculated.
- the crystallite size was calculated from the half width of the corrected peak using the following Scherrer equation. Measurement and analysis were performed three times each, and the average value was L (112).
- L crystal size (nm)
- ⁇ B Bragg angle
- ⁇ 0 Half width (correction value)
- Table 1 The results of measurement of L (112) of the graphite powder described in Examples and Comparative Examples are as shown in Table 1.
- A1 is the number of carbon atoms inside the aromatic ring, half of the aromatic carbon that is not substituted with the substituted aromatic carbon (corresponding to a peak of about 40-60 ppm of 13 C-NMR), and A2 is substituted
- the other half of the aromatic carbon corresponding to about 60-80 ppm peak of 13 C-NMR
- the normal paraffin content of the raw material oil of the graphite powder and the aromatic index fa described in all Examples and Comparative Examples other than Comparative Example 8 are as shown in Table 1.
- FIG. 1 shows a cross-sectional view of a negative electrode material evaluation cell 1.
- the evaluation cell 1 uses as a container a hollow metal body 2 that can be kept airtight inside by a packing 4 made of ethylene tetrafluoride. In the hollow metal body 2, first, the reference electrode 15 and the working electrode 7 obtained by the above process were arranged apart from each other.
- a separator 9 made of a polypropylene microporous film (Celgard # 2400) having a diameter of ⁇ 24 mm and a counter electrode 5 made of a disk-like lithium metal foil having a thickness of 0.7 mm and a diameter of ⁇ 17 mm are formed on these electrodes. Laminated in order. In addition, the lamination positional relationship between the lithium metal foil and the working electrode was held by the holding jig 3 so that the outer peripheral portion of the lithium metal foil projected on the working electrode side surrounded the outer periphery of the working electrode 7. Further, terminals 8, 10, and 12 extending from the counter electrode 5, the working electrode 7, and the reference electrode 15 to the outside of the metal frame 2 are provided.
- the electrolytic solution 6 is injected into the hollow metal body 3, and the laminate is pressed by a stainless spring 13 through a stainless steel (SUS304) disk 11 having a thickness of 1 mm and a diameter of ⁇ 20 mm.
- the hollow metal body 3 is sealed so that a reference electrode 15 in which a lithium metal is wound around a nickel lead plate (thickness 50 ⁇ m, width 3 mm) is fixed in the vicinity of the working electrode 7, and the negative electrode material evaluation cell 1 was made.
- the electrolyte 6 used was obtained by dissolving lithium hexafluorophosphate (LiPF6) in a solvent in which ethylene carbonate and ethylethylmethyl carbonate were mixed at a volume ratio of 3: 7 so as to have a concentration of 1 mol / L. .
- the negative electrode material evaluation cell was placed in a thermostatic chamber at 25 ° C., and the following charge / discharge test was performed. First, using the area of the working electrode as a reference, the counter electrode and the working electrode are energized (discharged) at a current value such that the current density is 0.1 mA / cm 2, and the potential of the working electrode with respect to the reference electrode becomes 0.01V. Until this time, the working electrode was doped with lithium. After a pause of 10 minutes, electricity was charged (charged) with the same current value until the potential of the working electrode with respect to the reference electrode reached 1.2 V, and the lithium occluded in the working electrode was dedoped.
- the obtained lithium doping capacity (mAh / g) and lithium dedoping capacity (mAh / g) were confirmed, and the charge / discharge efficiency (%) of the initial charge / discharge cycle was calculated from the following formula from these values.
- the lithium dedoping capacity and the charge / discharge efficiency of the graphite powder described in Examples and Comparative Examples are as shown in Table 1.
- FIG. 2 shows a cross-sectional view of the battery 20 manufactured.
- the positive electrode 21 is composed of lithium nickel oxide having an average particle diameter of 6 ⁇ m (LiNi 0.8 Co 0.15 Al 0.05 manufactured by Toda Kogyo Co., Ltd.) and a polyvinylidene fluoride binder (KF # 1320 manufactured by Kureha Co., Ltd.).
- Acetylene black (Denka Black manufactured by Denka) was mixed at a weight ratio of 89: 6: 5, kneaded with N-methyl-2-pyrrolidinone, and then pasted into a 30 ⁇ m thick aluminum foil.
- the negative electrode 23 is composed of graphite powder obtained in the following Examples or Comparative Examples, which are negative electrode materials, polyvinylidene fluoride as a binder (KF # 9310, manufactured by Kureha), and acetylene black (Denka black, manufactured by Denka).
- the sheet electrode After mixing at a weight ratio of 90: 2: 8, adding N-methyl-2-pyrrolidinone and kneading, paste it, apply it to one side of a 18 ⁇ m thick copper foil, perform drying and rolling operations,
- the sheet electrode is cut so that the size of the application part is 32 mm in width and 52 mm in length. A part of this sheet electrode is scraped off the negative electrode mixture perpendicularly to the longitudinal direction of the sheet, and the exposed copper foil is integrally connected to the current collector 24 (copper foil) of the coating part. It plays a role as a lead plate.
- the battery 20 was fabricated by sufficiently drying the positive electrode 21, the negative electrode 23, the separator 25, the outer package 27, and other parts, and introducing them into a glove box filled with argon gas having a dew point of ⁇ 100 ° C.
- the drying conditions are such that the positive electrode 21 and the negative electrode 23 are under reduced pressure at 150 ° C. for 12 hours or more, and the separator 25 and other members are under reduced pressure at 70 ° C. for 12 hours or more.
- the positive electrode 21 and the negative electrode 23 thus dried were laminated with the positive electrode application portion and the negative electrode application portion facing each other with a microporous film made of polypropylene (Celgard # 2400) facing each other, and polyimide Fixed with tape.
- the positive electrode and the negative electrode were stacked so that the peripheral portion of the positive electrode application portion projected onto the negative electrode application portion was surrounded by the inside of the peripheral edge portion of the negative electrode application portion.
- the obtained single-layer electrode body is embedded with an aluminum laminate film, an electrolyte solution is injected, and the laminate film is heat-sealed in a state where the positive and negative electrode lead plates protrude from the sealed single unit electrode.
- a layer laminate battery was prepared.
- the electrolyte used was a solution in which lithium hexafluorophosphate (LiPF 6 ) was dissolved at a concentration of 1 mol / L in a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3: 7. .
- Atmospheric distillation residue having a sulfur content of 3.1% by mass was hydrodesulfurized in the presence of a catalyst so that the hydrocracking rate was 25% or less to obtain hydrodesulfurized oil.
- the hydrodesulfurization conditions are a total pressure of 180 MPa, a hydrogen partial pressure of 160 MPa, and a temperature of 380 ° C.
- an atmospheric distillation residue oil was distilled under reduced pressure and further hydrodesulfurized (sulfur content: 380 mass ppm, density: 0.83 g / cm 3 at 15 ° C.), reaction temperature: 530 ° C., total pressure: 2.3 kgf / cm 2.
- a silica / alumina catalyst having platinum supported thereon was used as the catalyst.
- the above-mentioned hydrodesulfurized oil, fluid catalytic cracking residual oil, and ethylene bottom oil are mixed at a mass ratio of 1: 3: 1 to produce a heavy oil composition (hereinafter, particularly a raw oil composition) that becomes a raw material for coke. (Abbreviated as "thing").
- Table 1 shows the normal paraffin content and the aromatic index fa of this raw material oil composition. This raw material oil composition was introduced into a delayed coker apparatus and subjected to coking treatment at 550 ° C.
- the raw coal composition was introduced into a rotary kiln and calcined at 1400 ° C. to obtain a carbon material.
- the obtained carbon material is pulverized with a mechanical pulverizer (Super Rotor Mill / Nisshin Engineering) and classified with a precision air classifier (Turbo Classifier / Nisshin Engineering) to obtain carbon having an average particle size of 12 ⁇ m.
- a particulate material was obtained.
- This carbon fine particle material was put into a crucible, installed in an electric furnace, and heat-treated at a maximum temperature of 2100 ° C. in a nitrogen gas stream of 80 L / min.
- the heat treatment after obtaining the carbon fine particle material is hereinafter referred to as “graphitization”.
- the obtained graphite powder is designated as graphite A.
- Example 1 The carbon fine particle material obtained in the same manner as in Comparative Example 1 was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2200 ° C.
- the obtained graphite powder is designated as graphite B.
- Example 2 The carbon fine particle material obtained in the same manner as in Comparative Example 1 was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2400 ° C.
- the obtained graphite powder is designated as graphite C.
- Example 3 The carbon fine particle material obtained in the same manner as in Comparative Example 1 was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2600 ° C.
- the obtained graphite powder is designated as graphite D.
- Comparative Example 4 The normal paraffin content of the fluid catalytic cracking residual oil described in Comparative Example 1 and the aromatic index fa are shown in Table 1. Using this fluid catalytic cracking residual oil as a raw material oil composition, a raw material charcoal composition and carbon fine particles were obtained in the same manner as described in Comparative Example 1. The carbon fine particle material was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2400 ° C. The obtained graphite powder is designated as graphite G.
- Example 4 The fluid catalytic cracking residual oil described in Comparative Example 1 was mixed by adding the same volume of n-heptane, and then selectively extracted with dimethylformamide to separate it into an aromatic component and a saturated component. Among them, the aromatic component and the hydrodesulfurized oil described in Comparative Example 1 were mixed at a mass ratio of 4: 1 to obtain a coke raw material oil composition. Table 1 shows the normal paraffin content and the aromatic index fa of this raw material oil composition. This raw material oil was processed in the same manner as described in Comparative Example 1 to obtain a raw material carbon composition and carbon fine particles. The carbon fine particle material was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2400 ° C. The obtained graphite powder is designated as graphite H.
- Example 5 The same volume of n-heptane was added to and mixed with the fluid catalytic cracking residual oil described in Comparative Example 1, and then selectively extracted with dimethylformamide to separate it into an aromatic component and a saturated component. Among them, the saturated content and the fluid catalytic cracking residual oil described in Comparative Example 1 were mixed at a mass ratio of 1: 1 to obtain a coke raw material oil composition. Table 1 shows the normal paraffin content and the aromatic index fa of this raw material oil composition. This raw material oil composition was treated in the same manner as in the method described in Comparative Example 1 to obtain a raw material charcoal composition and carbon fine particles. The carbon fine particle material was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2400 ° C. The obtained graphite powder is designated as graphite J.
- Comparative Example 7 The fluid catalytic cracking residual oil described in Comparative Example 1 was selectively extracted with dimethylformamide and separated into an aromatic component and a saturated component. The aromatic component and the saturated component thus obtained were mixed at a mass ratio of 4: 1 to obtain a coke raw material oil composition. Table 1 shows the normal paraffin content and the aromatic index fa of this raw material oil composition.
- This raw material oil was processed in the same manner as described in Comparative Example 1 to obtain a raw material carbon composition and carbon fine particles.
- the carbon fine particle material was graphitized in the same manner as in Comparative Example 1 except that the maximum temperature reached 2400 ° C.
- the obtained graphite powder is designated as graphite L.
- Comparative Example 1 ⁇ Consideration on Test Results of Examples and Comparative Examples> Comparative Example 1, Examples 1 to 3 and Comparative Example 2 are graphite powders obtained from the same raw material oil composition, and differ only in the graphitization temperature.
- Graphite A of Comparative Example 1 has L (112) of 1.5 nm, ⁇ G of 22.3 cm ⁇ 1 , L (112) which is the range of the first aspect according to the present application is 2 to 4.2 nm, ⁇ G is out of the two ranges of 15 to 19 cm ⁇ 1 .
- L (112) is relatively small at 2 nm or less is considered that the graphitization temperature is as low as 2100 ° C. . For this reason, the capacity as the negative electrode (lithium dedoping capacity of the negative electrode material evaluation cell) was lowered.
- the capacity retention rate after 1000 cycles of the battery using graphite A as the negative electrode was 75%, which was a relatively low value.
- the reason for this is that the following considerations do not limit the technical scope of the present invention.
- ⁇ G is low and there are many exposed portions of crystallites on the particle surface, that is, unstructured carbon and dangling bonds, This is probably because the electrolyte solvent is easily reduced and decomposed in this region, and the resistance polarization increases with the progress of the charge / discharge cycle.
- ⁇ G of the graphite powder used for the negative electrode exceeds the upper limit range of 19 cm ⁇ 1 stipulated in the first aspect of the present application, the cycle deterioration of the battery increases, which is not preferable.
- graphites B, C and D in Examples 1 to 3 are graphite powders produced from the same raw material oil as in Comparative Example 1, but differ only in that the graphitization temperature is high and it is 2200 to 2600 ° C. L (112) and ⁇ G are both included in the scope of the present invention. Therefore, the capacity as the negative electrode (lithium dedoping capacity of the negative electrode material evaluation cell) is ensured to be 290 mAh / g or more, and the capacity retention rate after 1000 cycles of the batteries using these graphite powders as the negative electrode is 90% or more. It is preferable because it is secured.
- Graphite E of Comparative Example 2 is also a graphite powder produced from the same raw material oil as in Examples 1 to 3, except that the graphitization temperature is higher and it is 2700 ° C.
- Graphite E of Comparative Example 2 has a small .DELTA..nu G, but the exposed area of the edge surface of the crystallites present on the particle surfaces is small, the size of the crystallite L (112) is relatively large, inter lithium in graphite crystal When the curation is performed, the solvent of the electrolytic solution is easily co-inserted. For this reason, this solvent molecule was easily reduced and decomposed between the crystal layers, and the initial charge / discharge efficiency (charge / discharge efficiency of the negative electrode material evaluation cell) was greatly reduced to 62%.
- the capacity retention rate after 1000 cycles of the battery using graphite E as the negative electrode was 72%, which was significantly lower than that of the batteries of Examples 1 to 3 (90 to 93%).
- the following considerations do not limit the technical scope of the present invention at all.
- the cause is that the reductive decomposition reaction of the solvent co-inserted into the graphite crystal continues even when the charge / discharge cycle is repeated. I suggest that. That is, in the charging process in each cycle, this type of side reaction occurs, the resulting reaction product continues to accumulate, and the resistance polarization increases each time the cycle is repeated.
- L (112) of the negative electrode graphite powder exceeds 4.2 nm, which is the upper limit range of the first aspect according to the present application, cycle deterioration of a battery using the same becomes unfavorable.
- Graphite F of Comparative Example 3 is also a graphite powder produced from the same raw material oil as in Examples 1 to 3 and Comparative Examples 1 and 2, except that it is pulverized after graphitization.
- L (112) of graphite F is the same as that of graphite C, and is within the scope of the invention of the present application. but its .DELTA..nu G became a large value compared 21.3 cm -1, and the it graphite C and (17.4cm -1).
- the reversible capacity of graphite F as the negative electrode that is, the lithium dedoping capacity of the negative electrode material evaluation cell is the same as that of graphite C having the same L (112), but the capacity after 1000 cycles of the battery used as the negative electrode The maintenance rate is 68%, which is significantly lower than that of graphite C.
- the reason for this is that, as is evident from the low ⁇ G, there are many unstructured carbons and dangling bonds present on the particle surface, so the electrolyte solvent is easily reduced and decomposed in this region, and the charge / discharge cycle progresses. This is the same as in the case of graphite A because the resistance polarization increases.
- Graphite G of Comparative Example 4 is considered to have a small ⁇ G of 13.6 cm ⁇ 1 and a small amount of unstructured carbon and the region where the crystallite edge of the particle surface is exposed. For this reason, when the charge / discharge cycle is repeated, the region in which the solvent is reductively decomposed is small, and it is considered that the cycle deterioration can be suppressed.
- L (112) is as large as 4.7 nm. The upper limit is exceeded. For this reason, the capacity maintenance rate of the charge / discharge cycle of the battery was as low as 62% and the cycle deterioration was large, but this is considered to be the same as the graphite E of Comparative Example 2.
- L (112) is within the range of the first aspect according to the present application, while ⁇ G is as large as 19.8 cm ⁇ 1 , exceeding the upper limit range of the invention according to the present application. Yes. For this reason, the capacity maintenance rate of the charge / discharge cycle of the battery was as low as 78%, and the cycle deterioration was large. The cause of this is considered to be the same as that of the graphite A of Comparative Example 1.
- Graphite K of Comparative Example 6 is the same as Graphite C of Example 2, Graphite H of Example 4, and Graphite J of Example 5 at a heat treatment temperature of 2400 ° C., but L (112) is the first in the present application. It is below the lower limit of one embodiment and ⁇ G is as large as 21.4, which exceeds the upper limit range of the invention according to the present application. For this reason, the capacity maintenance rate of the charge / discharge cycle of the battery was as low as 64%, and the cycle deterioration was large. It is considered that this cause is exactly the same as that of the graphite A of Comparative Example 1.
- Graphite L of Comparative Example 7 is the same as Graphite C of Example 2, Graphite H of Example 4, and Graphite J of Example 5 at a heat treatment temperature of 2400 ° C., but L (112) is the first in the present application. It became larger than the upper limit of the aspect of one invention.
- ⁇ G is within the range defined in the aspect of the first invention according to the present application, but a large cycle deterioration was recognized as in the behavior of the batteries of Comparative Examples 2 and 4. This is because L (112) is too large, and even if ⁇ G is a graphite material within the range defined in the first aspect of the present invention, the co-insertion reaction of the solvent cannot be suppressed. As a result of reductive decomposition between graphite crystal layers and the reaction products continuously deposited by repeated charge and discharge cycles, the resistance of the battery is increased and the capacity is considered to be deteriorated.
- Graphite M of Comparative Example 8 has ⁇ G within the range of the first aspect according to the present application, while L (112) is as large as 32.4 nm, which exceeds the upper limit range of the invention according to the present application. Since L (112) of graphite M is the largest among graphites A to M, the charge / discharge capacity as the negative electrode (corresponding to the lithium dedoping capacity of the negative electrode material evaluation cell) was found to be the highest. However, since L (112) is too large, the capacity maintenance rate of the charge / discharge cycle of the battery was as low as 69%, and the cycle deterioration was large. This cause is considered to be the same as that of the graphite E of Comparative Example 2.
- the initial reversible capacity as a negative electrode (corresponding to the lithium dedoping capacity of the negative electrode material evaluation cell) is 221 to 365 mAh.
- the capacity retention rate after 1000 cycles of charge and discharge of the battery used as the negative electrode was 62 to 78. It was clarified that the life characteristics were lower than when the graphite material of the example was used.
- the raw material oil composition for obtaining the graphite material of the examples is within the range of the second aspect according to the present application, that is, the normal paraffin content is 5 to 20 wt%, and It became clear that the aromatic index fa is desirably 0.3 to 0.65. Therefore, as a production method for completing the graphite material defined in the first aspect of the present application, when a heavy oil composition is obtained by coking by a delayed coking process and then heat-treated, its raw oil composition It is clear that the product preferably has a normal paraffin content of 5 to 20 wt% and an aromatic index fa of 0.3 to 0.65, as defined in the second aspect of the present application. It became.
- the graphitization temperature and the pulverization treatment are performed even when the normal paraffin content and the aromatic index of the raw material oil composition are within the range of the second aspect according to the present application.
- the graphite material defined in the first aspect of the application may not necessarily be obtained.
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Abstract
Description
また、シート状、ペレット状等の形状に成形された負極材スラリーと集電体との一体化は、例えば、ロール、プレス、もしくはこれらの組み合わせ等、公知の方法により行うことができる。
正極に用いる活物質としては、特に制限はなく、例えば、リチウムイオンをドーピング又はインターカレーション可能な金属化合物、金属酸化物、金属硫化物、又は導電性高分子材料を用いればよく、例示するのであれば、コバルト酸リチウム(LiCoO2)、ニッケル酸リチウム(LiNiO2)、マンガン酸リチウム(LiMn2O4)、及び複酸化物(LiCoXNiYMnZO2、X+Y+Z=1)、リチウムバナジウム化合物、V2O5、V6O13、VO2、MnO2、TiO2、MoV2O8、TiS2、V2S5、VS2、MoS2、MoS3、Cr3O8、Cr2O5、オリビン型LiMPO4(M:Co、Ni、Mn、Fe)、ポリアセチレン、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセン等の導電性ポリマー、多孔質炭素等及びこれらの混合物を挙げることができる。
セパレータとしては、例えば、ポリエチレン、ポリプロピレン等のポリオレフィンを主成分とした不織布、クロス、微多孔性フィルム又はそれらを組み合わせたものを使用することができる。なお、作製するリチウムイオン二次電池の正極と負極が直接接触しない構造にした場合は、セパレータを使用する必要はない。
<物性の測定>
(1)黒鉛粉末の結晶子の大きさL(112)の算出
黒鉛粉末に、内部標準としてSi標準試料を10wt%混合し、ガラス製回転試料ホルダー(25mmφ×0.2mmt)に詰め、JIS R7651(2007)に基づき、広角X線回折法で測定を行い、黒鉛粉末の結晶子の大きさL(112)を算出した。X線回折装置は、Bruker-AXS社製 D8 ADVANCE(封入管型)、X線源はCuKα線(KβフィルターNiを使用)、X線管球への印可電圧及び電流は40kV及び40mAとした。
得られた回折図形についても、JIS R7651(2007)に準拠した方法で解析を行った。具体的には、測定データにスムージング処理、バックグラウンド除去の後、吸収補正、偏光補正、Lorentz 補正を施し、Si標準試料の(422)回折線のピーク位置、及び値幅を用いて、黒鉛粉末の(112)回折線に対して補正を行い、結晶子サイズを算出した。なお、結晶子サイズは、補正ピークの半値幅から以下のScherrerの式を用いて計算した。測定・解析は3 回ずつ実施し、その平均値をL(112)とした。
L=K×λ/(β0×cosθB)- - - - - -Scherrerの式
ここで、L :結晶サイズ(nm)
K:形状因子定数(=1.0)
λ :X線の波長(=0.15406nm)
θB:ブラッグ角
β0:半値幅(補正値)
実施例及び比較例に記載された黒鉛粉末のL(112)が測定された結果は、表1に示された通りである。
光源をAr+レーザー(励起波長514.5 nm)としたラマン分光分析を行った。測定はマクロモードで、レーザーのスポット径は約100μmであり、レーザー照射範囲全体からの平均的な情報が得られるように設定した。測定装置はRamanor T-64000 (Jobin Yvon/愛宕物産)、測定配置は60°、レーザーパワーは10mWである。
得られたラマンスペクトル図において、1580cm-1±100cm-1の波長領域に存在するピークの半価幅ΔνGを、最小二乗法による直接読み取りにより算出した。なお測定・解析は3回ずつ実施し、その平均値をΔνGとした。
実施例及び比較例に記載された黒鉛粉末のΔνGが測定された結果は、表1に示された通りである。
原料油組成物のノルマルパラフィンの含有率は、キャピラリーカラムが装着されたガスクロマトグラフによって測定した。具体的には、ノルマルパラフィンの標準物質によって検定した後、溶出クロマトグラフィー法によって分離された非芳香族成分の試料をキャピラリーカラムに通して測定した。この測定値から原料油組成物の全質量を基準とした含有率を算出した。
また芳香族炭素分率(fa)は、Knight法により算出した。すなわち、重質油組成物の13C-NMR法による芳香族炭素のスペクトルとして3つの成分(A1,A2,A3)に分割する。ここで、A1は芳香族環内部炭素数、置換されている芳香族炭素と置換していない芳香族炭素の半分(13C-NMRの約40~60ppmのピークに相当)、A2は置換していない残りの半分の芳香族炭素(13C-NMRの約60~80ppmのピークに相当)、A3は脂肪族炭素数(13C-NMRの約130~190ppmのピークに相当)であり、これらからfaは、fa=(A1+A2)/(A1+A2+A3)により算出した。比較例8以外の全ての実施例及び比較例に記載された黒鉛粉末の原料油のノルマルパラフィン含有率、及び芳香族指数faは、表1に示された通りである。
(1)負極材料評価用セルの作製方法
負極材料として、下記実施例又は比較例で得られた黒鉛粉末と結着剤のポリフッ化ビニリデン(クレハ社製KF#9310)、アセチレンブラック(デンカ社製のデンカブラック)を重量比で90:2:8に混合し、N-メチル-2-ピロリジノンを加えて混練した後、ペースト状にして、厚さ18μmの銅箔の片面に塗布し、乾燥及び圧延した。得られたシート状の電極を直径φ15mmに打ち抜き作用極とした。この作用極及びその他の必要部材を十分に乾燥させ、露点-100℃のアルゴンガスが満たされたグローブボックス内に導入し、負極材料評価用セルを組み立てた。乾燥条件は、作用極が減圧状態の下150℃で12時間以上、その他部材が減圧状態の下70℃で12時間以上である。
図1に負極材料評価用セル1の断面図を示す。評価用セル1は、四弗化エチレン製パッキング4により内部の気密が保持可能な中空金属体2を容器としている。当該中空金属体2にはまず、参照極15と上記工程により得られた作用極7とを離間して配置した。次に、これらの電極上に直径φ24mmのポリプロピレン製のマイクロポーラスフィルム(セルガード社製#2400)からなるセパレータ9と、厚さ0.7mm、直径φ17mmの円盤状リチウム金属箔からなる対極5とを順に積層した。なおリチウム金属箔と作用極との積層位置関係は、リチウム金属箔を作用極側に投影したときにその外周部が作用極7の外周を包囲するように押さえ治具3によって保持した。さらに、対極5、作用極7および参照極15から各々金属枠2の外部に延びる端子8、10、12を設けた。
次いで、前記中空金属体3に電解液6を注入すると共に、この積層体が、厚さ1mm、直径φ20mmのステンレス(SUS304)製円盤11を介してステンレス製のバネ13で加圧され、帯状のニッケル製リード板(厚さ50μm,幅3mm)にリチウム金属が巻きつけられた参照極15が作用極7近傍で固定されるように前記中空金属体3を封止し、負極材料評価用セル1を作製した。使用した電解液6は、エチレンカーボネートとエチルエチルメチルカーボネートとを体積比で3:7に混合した溶媒にヘキサフルオロリン酸リチウム(LiPF6)を1mol/Lの濃度となるように溶解したものである。
負極材料評価用セルを25℃の恒温室内に設置し、以下に示す充放電試験を行った。先ず作用極の面積を基準とし、電流密度が0.1mA/cm2となるような電流値で対極及び作用極の間を通電(放電)し、参照極に対する作用極の電位が0.01Vになるまで作用極にリチウムをドープした。10分間の休止の後、同じ電流値で参照極に対する作用極の電位が1.2Vになるまで通電(充電)し、作用極に吸蔵されたリチウムを脱ドープした。得られたリチウムドープ容量(mAh/g)とリチウム脱ドープ容量(mAh/g)を確認し、これらの値から初期充放電サイクルの充放電効率(%)を以下の式から算出した。
(1)電池の作製方法
図2に作製した電池20の断面図を示す。正極21は、正極材料である平均粒子径6μmのニッケル酸リチウム(戸田工業社製LiNi0.8Co0.15Al0.05)と結着剤のポリフッ化ビニリデン(クレハ社製KF#1320)、アセチレンブラック(デンカ社製のデンカブラック)を重量比で89:6:5に混合し、N-メチル-2-ピロリジノンを加えて混練した後、ペースト状にして、厚さ30μmのアルミニウム箔の片面に塗布し、乾燥及び圧延操作を行い、塗布部のサイズが、幅30mm、長さ50mmとなるように切断されたシート電極である。このシート電極の一部はシートの長手方向に対して垂直に正極合剤が掻き取られ、その露出したアルミニウム箔が塗布部の集電体22(アルミニウム箔)と一体化して繋がっており、正極リード板としての役割を担っている。
負極23は、負極材料である下記実施例又は比較例で得られた黒鉛粉末と結着剤のポリフッ化ビニリデン(クレハ社製KF#9310)と、アセチレンブラック(デンカ社製のデンカブラック)とを重量比で90:2:8に混合し、N-メチル-2-ピロリジノンを加えて混練した後、ペースト状にして、厚さ18μmの銅箔の片面に塗布し、乾燥及び圧延操作を行い、塗布部のサイズが、幅32mm、長さ52mmとなるように切断されたシート電極である。このシート電極の一部はシートの長手方向に対して垂直に負極合剤が掻き取られ、その露出した銅箔が塗布部の集電体24(銅箔)と一体化して繋がっており、負極リード板としての役割を担っている。
電池20の作製は、正極21、負極23、セパレータ25、外装27及びその他部品を十分に乾燥させ、露点-100℃のアルゴンガスが満たされたグローブボックス内に導入して組み立てた。乾燥条件は、正極21及び負極23が減圧状態の下150℃で12時間以上、セパレータ25及びその他部材が減圧状態の下70℃で12時間以上である。
このようにして乾燥された正極21及び負極23を、正極の塗布部と負極の塗布部とが、ポリポロピレン製のマイクロポーラスフィルム(セルガード社製#2400)を介して対向させる状態で積層し、ポリイミドテープで固定した。なお、正極及び負極の積層位置関係は、負極の塗布部に投影される正極塗布部の周縁部が、負極塗布部の周縁部の内側で囲まれるように対向させた。得られた単層電極体を、アルミラミネートフィルムで包埋させ、電解液を注入し、前述の正・負極リード板がはみ出した状態で、ラミネートフィルムを熱融着することにより、密閉型の単層ラミネート電池を作製した。使用した電解液は、エチレンカーボネートとエチルメチルカーボネートが体積比で3:7に混合された溶媒にヘキサフルオロリン酸リチウム(LiPF6)が1mol/Lの濃度となるように溶解されたものである。
得られた電池を25℃の恒温室内に設置し、以下に示す充放電試験を行った。先ず1.5mAの電流で、電池電圧が4.2Vとなるまで定電流で充電した。10分間休止の後、同じ電流で電池電圧が3.0Vとなるまで定電流で放電する充放電サイクルを10回繰り返した。この充放電サイクルは、電池の異常を検地するためのものであるため、充放電サイクル試験のサイクル数には含まなかった。本実施例で作製された電池は、全て異常がないことを確認した。
次の充放電サイクルを第1サイクル(初期サイクル)とする。75mAの電流で、電池電圧が4.2Vとなるまで定電流で充電し、1分間休止の後、同じ電流で電池電圧が3.0Vとなるまで定電流で放電する充放電サイクルを設定し、このサイクルを1000回繰り返した。充放電サイクルの容量維持率として、初期放電容量に対する1000サイクル目の放電容量の割合(%)を算出した。実施例及び比較例で作製した黒鉛粉末を負極として使用した電池の充放電サイクルの容量維持率を表1中に示す。
(比較例1)
硫黄分3.1質量%の常圧蒸留残油を、触媒存在下、水素化分解率が25%以下となるように水素化脱硫し、水素化脱硫油を得た。水素化脱硫条件は、全圧180MPa、水素分圧160MPa、温度380℃である。また、常圧蒸留残渣油を減圧蒸留し、更に水素化脱硫したもの(硫黄分380質量ppm、15℃における密度0.83g/cm3)を、反応温度530℃、全圧2.3kgf/cm2、触媒/油比13、接触時間7秒で流動接触分解し、流動接触分解残油を得た。触媒としては、シリカ・アルミナ触媒に白金が担持されたものを使用した。次に、前述の水素化脱硫油と流動接触分解残油及びエチレンボトム油とを、質量比1:3:1で混合し、コークスの原料となる重質油組成物(以下、特に原料油組成物と略記)を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。
この原料油組成物をディレードコーカー装置に導入して、不活性ガス雰囲気下、550℃でコーキング処理し、原料炭組成物を得た。次いで、当該原料炭組成物をロータリーキルンに導入して1400℃でか焼し、炭素材料を得た。得られた炭素材料を機械式粉砕機(スーパーローターミル/日清エンジニアリング製)で粉砕し、精密空気分級機(ターボクラシファイヤー/日清エンジニアリング製)で分級することにより、平均粒子径12μmの炭素微粒子材料を得た。この炭素微粒子材料をるつぼに投入し、電気炉に設置して、80L/分の窒素ガス気流中、最高到達温度2100℃で熱処理した。このとき昇温速度は200℃/時間、最高到達温度の保持時間は16時間、降温速度は1000℃までが100℃/時間とし、その後窒素気流を保持させた状態で室温まで放冷させた。炭素微粒子材料を得た後の熱処理を、以下「黒鉛化」と呼称する。得られた黒鉛粉末を、黒鉛Aとする。
比較例1と同様にして得た炭素微粒子材料に対し、最高到達温度を2200℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Bとする。
比較例1と同様にして得た炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Cとする。
比較例1と同様にして得た炭素微粒子材料に対し、最高到達温度を2600℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Dとする。
比較例1と同様にして得た炭素微粒子材料に対し、最高到達温度を2700℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Eとする。
比較例1と同様にして得た原料炭組成物をるつぼに投入し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。この黒鉛を機械式粉砕機(スーパーローターミル/日清エンジニアリング製)で粉砕し、精密空気分級機(ターボクラシファイヤー/日清エンジニアリング製)で分級することにより、平均粒子径12μmの炭素微粒子材料を得た。得られた黒鉛粉末を黒鉛Fとする。
比較例1記載の流動接触分解残油のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この流動接触分解残油を原料油組成物とし、比較例1に記載された方法と同様にして原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Gとする。
比較例1記載の流動接触分解残油を、同体積のn-ヘプタンを加え混合した後、ジメチルホルムアミドで選択抽出し、芳香族分と飽和分に分離させた。このうちの芳香族分と比較例1記載の水素化脱硫油とを質量比4:1で混合し、コークスの原料油組成物を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この原料油を、比較例1に記載された方法と同様に処理し、原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Hとする。
比較例1記載の水素化脱硫油と流動接触分解残油とを質量比3:1で混合し、コークスの原料油組成物を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この原料油組成物を、比較例1に記載された方法と同様に処理し、原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Iとする。
比較例1記載の流動接触分解残油に、同体積のn-ヘプタンを加え混合した後、ジメチルホルムアミドで選択抽出し、芳香族分と飽和分に分離させた。このうちの飽和分と比較例1記載の流動接触分解残油とを質量比1:1で混合し、コークスの原料油組成物を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この原料油組成物を、比較例1に記載された方法と同様に処理し、原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Jとする。
比較例1記載の水素化脱硫油と流動接触分解残油とを質量比4:1で混合し、コークスの原料油組成物を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この原料油組成物を、比較例1に記載された方法と同様に処理し、原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Kとする。
比較例1記載の流動接触分解残油を、ジメチルホルムアミドで選択抽出し、芳香族分と飽和分に分離させた。このようにして得られた芳香族分と飽和分を質量比4:1で混合し、コークスの原料油組成物を得た。この原料油組成物のノルマルパラフィン含有率、及び芳香族指数faを表1に示す。この原料油を、比較例1に記載された方法と同様に処理し、原料炭組成物及び炭素微粒子を得た。この炭素微粒子材料に対し、最高到達温度を2400℃とした以外は比較例1と同様な方法で黒鉛化した。得られた黒鉛粉末を、黒鉛Lとする。
高純度化処理された市販のブラジル産鱗片状天然黒鉛(固定炭素=99.6%,灰分=0.1%,揮発分=0.3%)を機械式粉砕機(スーパーローターミル/日清エンジニアリング製)で粉砕し、精密空気分級機(ターボクラシファイヤー/日清エンジニアリング製)で分級することにより、平均粒子径12μmの炭素微粒子材料を得た。得られた黒鉛粉末を黒鉛Mとする。
比較例1、実施例1~3及び比較例2は同一の原料油組成物から得られた黒鉛粉末で、黒鉛化温度のみが異なっている。比較例1の黒鉛Aは、L(112)が1.5nm、ΔνGが22.3cm-1で、本出願に係る第一の態様の範囲であるL(112)が2~4.2nm、ΔνGが15~19cm-1の2つの範囲から共に外れている。
本発明の技術的範囲を以下の考察が何ら制約するものではないが、L(112)が2nm以下と相対的に小さくなった要因は、黒鉛化温度が2100℃と低かったからであると考えられる。このため負極としての容量(負極材料評価用セルのリチウム脱ドープ容量)が低くなった。
2 中空金属体
3 押さえ治具
4 パッキン
5、21 対極(正極)
6 電解液
7、23 作用極(負極)
8、10、12 端子
9、25 セパレータ
11 対極押さえ板
13 ばね
15 参照極
20 電池
22 正極集電体
24 負極集電体
27 外装
Claims (7)
- X線広角回折法によって得られた(112)回折線から算出されるc軸方向の結晶子の大きさL(112)が2.0~4.2nmであって、且つ、波長5145オングストロームのアルゴンイオンレーザー光を用いたラマンスペクトル分析において、1580cm-1±100cm-1の波長領域に存在するピークの半価幅ΔνGが15~19cm-1であるリチウム二次電池負極用人造黒鉛。
- 重質油組成物をディレードコーキングプロセスによってコーキング処理した後、熱処理する工程を経て得られたリチウム二次電池負極用人造黒鉛であって、前記重質油組成物は、ノルマルパラフィン含有率が5~20wt%、Knight法により求められた芳香族指数faが0.3~0.65である請求項1に記載のリチウム二次電池負極用人造黒鉛。
- 前記熱処理する工程が、1500℃以下で炭素化し粉砕することにより炭素微粒子材料を得るステップと、該炭素微粒子材料を不活性ガス雰囲気下最高到達温度が2200から2600℃になるまで加熱して前記人造黒鉛を得るステップとを含む請求項2に記載のリチウム二次電池負極用人造黒鉛。
- 重質油組成物をディレードコーキングプロセスによってコーキング処理した後、熱処理する工程を含むリチウム二次電池負極用黒鉛の製造方法であって、前記重質油組成物は、ノルマルパラフィン含有率が5~20wt%、Knight法により求められた芳香族指数faが0.3~0.65であるリチウム二次電池負極用人造黒鉛の製造方法。
- 請求項4に記載の製造方法により得られたリチウム二次電池負極用人造黒鉛。
- リチウムの可逆的なインターカレーションが可能なリチウムを含んだ正極と、請求項1に記載のリチウム二次電池負極用人造黒鉛を含む負極と、非水電解質とを備えたリチウム二次電池。
- リチウムの可逆的なインターカレーションが可能なリチウムを含んだ正極と、請求項5に記載のリチウム二次電池負極用人造黒鉛を含む負極と、非水電解質とを備えたリチウム二次電池。
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EP10817265.1A EP2479823A4 (en) | 2009-09-18 | 2010-09-16 | NEGATIVE ELECTRODE CARBON MATERIAL FOR LITHIUM RECHARGEABLE BATTERY AND METHOD FOR MANUFACTURING THE SAME |
CN201080041837.0A CN102511096B (zh) | 2009-09-18 | 2010-09-16 | 锂二次电池的负极用碳材料及其制造方法 |
US13/422,513 US8617508B2 (en) | 2009-09-18 | 2012-03-16 | Carbon material for negative electrode of lithium secondary battery and method for producing the same |
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WO2012133511A1 (ja) * | 2011-03-30 | 2012-10-04 | Jx日鉱日石エネルギー株式会社 | リチウムイオン二次電池の負極用炭素材料およびその製造方法 |
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WO2021256558A1 (ja) * | 2020-06-18 | 2021-12-23 | Eneos株式会社 | リチウムイオン二次電池負極用人造黒鉛材料、及びその製造方法 |
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KR102016181B1 (ko) * | 2011-03-30 | 2019-08-29 | 제이엑스티지 에네루기 가부시키가이샤 | 리튬이온 이차전지의 음극용 탄소 재료 및 그 제조 방법 |
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US9831490B2 (en) | 2012-06-29 | 2017-11-28 | Mt Carbon Co., Ltd. | Graphite material for negative electrode of lithium-ion secondary battery, lithium-ion secondary battery including the graphite material, and method of manufacturing graphite material for lithium-ion secondary battery |
WO2021256558A1 (ja) * | 2020-06-18 | 2021-12-23 | Eneos株式会社 | リチウムイオン二次電池負極用人造黒鉛材料、及びその製造方法 |
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EP2479823A4 (en) | 2016-03-02 |
KR20120081114A (ko) | 2012-07-18 |
CN102511096B (zh) | 2014-11-26 |
US20140079622A1 (en) | 2014-03-20 |
KR101820071B1 (ko) | 2018-01-18 |
JP2011065961A (ja) | 2011-03-31 |
US20120171572A1 (en) | 2012-07-05 |
JP5367521B2 (ja) | 2013-12-11 |
US8617508B2 (en) | 2013-12-31 |
CN102511096A (zh) | 2012-06-20 |
EP2479823A1 (en) | 2012-07-25 |
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