WO2005008810A1 - Improved graphite granules and their method of fabrication - Google Patents
Improved graphite granules and their method of fabrication Download PDFInfo
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- WO2005008810A1 WO2005008810A1 PCT/CN2004/000834 CN2004000834W WO2005008810A1 WO 2005008810 A1 WO2005008810 A1 WO 2005008810A1 CN 2004000834 W CN2004000834 W CN 2004000834W WO 2005008810 A1 WO2005008810 A1 WO 2005008810A1
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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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
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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
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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
- 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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- 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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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
- This invention relates to improved graphite granules and their method of fabrication.
- it relates to improved graphite granules used as the active material in the negative electrode of a battery.
- the demand for power sources with dense energy capacity per body mass and high cu ⁇ ent characteristics is especially high.
- Electrical and electronic products such as modern portable products, electrical tools, electric bicycles, and electric cars can have very high demand for electrical consumption per unit time. Examples include modern cell phones with color screens and with functions such as wireless internet connections and multimedia capabilities, notebook computers demanding the ability to use electricity for a long time, and, the starter mechanism for automobiles.
- the lithium ion rechargeable batteries that are used as the power sources, these products high currents from these power sources. In other words, for many circumstances in recent years, greater demands are made on the high cu ⁇ ent characteristics of the lithium ion rechargeable batteries.
- the high cu ⁇ ent characteristics of lithium ion rechargeable batteries mainly depend on the material for their positive and negative electrodes.
- the active material for the negative electrode is especially critical for improving the high cu ⁇ ent characteristics that are mainly dependent on the electrical conducting properties and the stability of the structure of the underlying active material.
- the most common active material for the negative electrode in a lithium ion rechargeable battery is a graphite type material as graphite has a lower discharging electricity platform and better cycle stability characteristics.
- these graphite type materials natural graphite with a high degree of graphitization has higher specific capacity.
- the structure of the crystallite in the natural graphite can easily be loosened or even destroyed resulting in the deterioration of the cycle and high cu ⁇ ent characteristics.
- Chinese Patent CN1230159 entitled “Graphite Granules and Using Graphite Granules as the Negative Electrode for Lithium Rechargeable Batteries,” discloses a type of graphite granules. Lithium rechargeable batteries using those graphite granules have excellent rapid charge and discharge and cycle characteristics. The characteristics of this type of graphite granules are: lower directional property of the graphite granule resulting from the grouping or joining of many flat shaped granules together such that the directional position of the crystal surface of the neighboring flat shaped crystal granules are not parallel.
- An object of this invention is to provide improved graphite granules that have excellent electrochemical properties; such that when for negative electrodes in batteries such as lithium ion rechargeable batteries, it produces batteries with high cu ⁇ ent characteristics, higher reversible specific capacity, and longer cycle life.
- Another object of this invention is to provide a method for fabricating said improved graphite granules with technology that is simple, of low cost and easy for mass production.
- the present invention relates to a type of improved graphite granules and the method of fabrication of said improved graphite granules.
- Each granule of said improved graphite granules comprises of an unimproved graphite granule, and a membrane of amorphous carbon enveloping said unimproved graphite granules to form the outer membrane.
- the thickness of the amorphous carbon membrane is between 0.05/ m and l ⁇ rn.
- the unimproved graphite granule can be a natural, man-made, or even a modified graphite granule.
- the unimproved graphite granules is immersed in a surface modifying solution that is near saturation and the solution is produced by mixing a pre-determined amount of a surface modifying agent in a co ⁇ esponding solvent.
- the unimproved graphite granules are sti ⁇ ed in the surface modifying solution at predetermined speed for a predetermined time period to form coated graphite granules.
- the coated graphite granules are then separated from the surface modifying solution, and heat to dry.
- the coated graphite granules are then sifted, and solidified in an inert environment at a predetermined temperature for a predetermined period of time.
- said coated solidified graphite granules are carbonized in an inert environment at a predetermined temperature for a predetermined period of time to form the improved graphite granules.
- said improved graphite granules have excellent electrochemical properties, which, when used as the active material for the negative electrode in batteries (e.g. lithium ion batteries), produces batteries with excellent high cu ⁇ ent characteristics, higher reversible specific capacity, and longer cycle life that can satisfy the demands of practical application.
- the advantages of said method for fabrication of said improved graphite granules of this invention is that the technology for the fabrication is simple and inexpensive, thus making it easy to use for commercial production.
- Figure 1 is the scanning electron micrograph of the unimproved graphite granules used in Embodiment 1.
- Figure 2 is the scanning electron micrograph of the improved graphite granules made by of Embodiment 1.
- Figure 3 is a graph of the result of the heat analysis (DSC - Differential Scanning Calorimetry and Thermal Gravimetric Analysis) of the improved graphite granules of Embodiment 1.
- An embodiment of said improved graphite granules can by made as follows. Immerse the unimproved graphite granules in a surface modifying solution that is almost saturated by mixing a pre-determined amount of a surface modifying agent in a co ⁇ esponding solvent of said surface modifying solution.
- the surface modifying agent is one or more polymers selected from the group: coal pitch, coal tar, petroleum pitch, petroleum coke, benzene, naphthalene, copolymers of benzene and naphthalene copolymer, petroleum wax and petroleum resin.
- the co ⁇ esponding solvent for the surface modifying agent is an organic solvent selected from the following group: acetone, anhydrous ethanol, N-methyl py ⁇ olidone, chloroform, tetrahydrofuran, carbon tetrachloride, and cyclohexane.
- the average granule diameter of said unimproved graphite granules is between 7 ⁇ m and 35 ⁇ rn. 1.5 liters to 3 liters of said surface modifying solution is used for every 1 kg of unimproved graphite granules.
- the unimproved graphite granules are sti ⁇ ed in said surface modifying solution at lOOrpm to 2000 rpm for 0.5 hours tolO hours to form coated graphite granules until the surface modifying solution is fully in contact with the surface of said unimproved core material of graphite granules. Then, the coated graphite granules are separated from the surface modifying solution, and heat to dry the excess surface co ⁇ ecting solution. The coated graphite granules is then sifted and solidified in an inert environment at 200°C to 600°C for 0.2 hours to 12 hours. During solidification, the temperature is increased at a rate of 0.5°C/min to 35°C/min.
- said coated graphite is carbonized in an inert environment at 750°C to 1300°C for 1 hour to 24 hours to form said improved graphite granules.
- the rate of increase in temperature for carbonization is 0.1°C/min to 30°C/min.
- the unimproved graphite granules that form the core of said improved graphite granules can be natural, man-made graphite, or graphite modified by other means.
- the specifications for one of the prefe ⁇ ed embodiments of said fabrication method are: Said solidification proceeds at 300 °C to 500°C where the temperature is held for 0.5 hours to 3 hours and the rate of increase in temperature is 5°C/n ⁇ in to 20°C/min.
- each improved graphite granule includes an unimproved graphite granule and a membrane of amorphous carbon enveloping said unimproved graphite granules forming the outer membrane.
- the thickness of said amorphous carbon membrane is between 0.05/m ⁇ and l ⁇ rn.
- the crystallite interlayer spacing in said improved graphite granules, d 0 02 is between 0.335nm and 0.340nm.
- the specific surface area of said improved graphite granules is between 1.3 m /g and 4.2 m /g.
- the average granule diameter of the improved graphite granules is between 8 ⁇ m and 35 ⁇ rn.
- Further preferable specifications of the embodiments for said improved graphite granules are: the crystallite interlayer spacing in said improved graphite granules, d 0 o 2 , is between 0.335nm and 0.338nm.
- the specific surface area of said improved graphite granules is 1.8 m 2 /g and 3.5 m 2 /g and the average granule diameter of said improved graphite granules is between 10 ⁇ m and 20 ⁇ m.
- the average granule diameter is the D 50 measured by using a particle size analyzer.
- the crystallite interlayer spacing, doo 2 is measured using an X-ray diffractometer.
- the specific area of the surface is obtained using the single-point BET method.
- the amorphous carbon membrane that coats the surface of the core material of graphite granules can improve the surface morphology of the granule, lowering its specific surface area.
- the improved surface morphology raises the compatibility between the granules and the electrical conducting solution in the battery, resulting in the improvement of the initial charge and discharge efficiency of the battery.
- the improve surface morphology can also compensate for the weakness of the boundary edges of the crystallite structure of the core material of unimproved graphite granules, lowering the directional characteristics of the crystallite, stabilizing the graphite crystallite, and further improving its electrical conduction and the uniformity of the electron distribution of the electrode.
- the average granule diameter of said improved graphite granules is between 8um and 35um.
- the prefe ⁇ ed specification is between 10am and 20 ⁇ m. If the average granule diameter of the improved graphite granules is too small, then the improved graphite granules are too small and the specific surface area is too large. This can damage the reversibility discharge capacity in a battery with the negative electrode made from the improved graphite granules. If the average granule diameter is too large, then the distance between the improved graphite granule edge and the center is so large that the Li ⁇ +
- the crystallite interlayer spacing, (I 00 2) is between 0.335nm and 0.340nm.
- the prefe ⁇ ed size is between 0.335nm and 0.338nm.
- the crystallite interlayer spacing, do 0 2, of the graphite granules is mainly determined by the source of the unimproved graphite granules, i.e., whether said unimproved granules are made from natural graphite or man-made graphite with a high degree of graphitization.
- the surface modifying process does not greatly affect the crystallite layer interspacing, d 0 o 2 .
- the nearer the crystallite interlayer spacing, d 002 is to the ideal graphite value of 0.3354nm, the higher the degree of graphitization.
- the specific surface area of the improved graphite granules is between 1.3 m 2 /g and 4.2m 2 /g.
- a prefe ⁇ ed specification is between 1.8 m 2 /g and 3.5m 2 /g.
- the improved graphite that has undergone the surface modifying treatment effectively decreases the specific surface area of the unimproved graphite granules.
- the specific surface area of the source for the unimproved graphite granules is approximately 5m 2 /g.).
- the size of the specific surface area of the material for the negative electrode directly affects the amount of the i ⁇ eversible capacity used by the SEI membrane that is formed during the initial charging process in a lithium ion battery.
- the thickness of the membrane of said amorphous carbon is between 0.05 ⁇ m and lum.
- the thickness of the membrane of said amorphous carbon is calculated according to the volume of coating of the surface modifying agent on the surface of the graphite core material granules and the average diameter of the core material of graphite granules, the DSC (Differential Scanning Calorimetry and Thermal Gravimetric Analysis) graph of the improved graphite granules can be obtained by heat analysis.
- the improved graphite granules are obtained by treating and modifying the surfaces of natural or man-made graphite granules with high graphitization levels.
- the fabrication method is as follows: Immerse unimproved graphite granules in a polymer surface modifying solution that is saturated or almost saturated and prepared by dissolving a polymer surface modifying agent in its co ⁇ esponding organic solvent; Stir at a speed of lOOrpm to 2000rpm for 0.5 hours to 10 hours such that the surface modifying solution is fully in contact with the surface of said unimproved graphite granules to from coated graphite granules; Separate the coated graphite granules by filtering or centrifuge; Heat to dry excess surface modifying solution; Sift; Solidify and also carbonize the dried coated graphite granules in an inert environment.
- said surface modifying agent is a type of organic matter with high carbon content. It is one or more polymers selected from the following group: coal pitch, coal tar, petroleum pitch, petroleum coke, benzene, naphthalene, copolymers of benzene and naphthalene, petroleum wax, and petroleum resin.
- the co ⁇ esponding solvent is an organic solvent selected from the following group: acetone, anhydrous ethanol, N- methyl py ⁇ olidone, chloroform, tetrahydrofuran, carbon tetrachloride, and cyclohexane.
- the effect of the surface modification is related to the stirring time in above described stirring step.
- the stirring time is too long, the thickness of the organic membrane that is adhering to the surface of the core material of unimproved graphite granules is too thick and will affect the properties of the improved graphite granules such as lowering the initial charge/discharge efficiency the battery whose negative electrode is made from the improved graphite granules. If the stirring time is too short, then the membrane of organic material membrane adhering to the surface of the core material of unimproved graphite granule is too thin and not uniformly distributed on the surface of the core material of unimproved graphite granules thus affecting the properties of the improved graphite granules.
- the solidifying step of the fabrication method of the improved graphite granules of the embodiments of this invention increase the temperature at the rate of 0.5°C/min to35°C/min to reach the desired temperature for solidification.
- a better range is 5°C/min to 20°C/min.
- the solidification temperature is 200°C to 600°C.
- a better range is 300°C to 500°C. Hold the temperature for 0.2 hours to 12 hours.
- a better time is 0.5 hours to 3 hours.
- a better rate of increase is 3°C/min to 20°C/min.
- the carbonization temperature is 750°C to 1300°C.
- a better range is 800°C to 1200°C. Hold the temperature for 1 to 24 hours. A better time is 2 hours to 10 hours. After carbonization, lower the temperature at the rate of l°C/min to 20°C/min. A better decrease rate is 5°C/min to 15°C/min. The temperature can also be lowered naturally. If the carbonization temperature is too low, such as lower than 750°C, then the carbonization of the organic layer on the surface of the core material of unimproved graphite granule is insufficient to form a stable compact carbon membrane and minute pores may even be fo ⁇ ned. A structure with minute holes and larger specific surface area may even be formed. This kind of structure does not improve the surface morphology.
- fu ⁇ iaces such as: box-style electrical resistance furnace, tubular furnace, push pull tunnel furnace, or rotating tunnel furnace can be used for solidification and carbonization as long as the furnace can reach desired temperature, can be sealed and is able to aerate the inert environment.
- Said inert environment can be a mixture of one or more of the following: argon gas, helium gas, and nitrogen gas.
- argon gas argon gas
- helium gas helium gas
- nitrogen gas nitrogen gas.
- the solvent for the electrolyte solution is a mixture of the following organic solvent: ethylene carbonate, ethyl methyl carbonate, diethyl carbonate. The concentration is 1 mole per liter.
- the separator is polyethylene and polypropylene multiple separator.
- Embodiment 1 The following steps comprise the method for the fabrication of Embodiment 1 : Dissolve 8 g of petroleum coke in carbon tetrachloride to formulate 200 ml of 4% surface modifying solution; Immerse lOOg of unimproved dried natural graphite granules and immerse in the surface modifying agent organic solution; Stir at 300rpm speed for 1 hour to form a thin layer of surface modifying membrane on the surface of the unimproved graphite granules; Filter the coated graphite granules that are obtained; Heat to dry and sift with 300 mesh; Put sifted coated graphite granules into sealed tubular high temperature furnace. Pass highly pure nitrogen at 10 liters/min of flow volume and increase the temperature at 15°C/min to 400°C and hold the temperature for 1 hour; and Increase the temperature at 10°C/min to 1000°C and hold the temperature for 3 hours.
- Embodiment is shown to be 13.8/ m. Its crystallite interlayer spacing, d 0 o2, is 0.3365nm, and its specific surface area is 2.8m /g.
- Embodiment 2 the surface modifying solution is a 5% coal pitch in tetrahydrofuran. Other than this, all other steps and specifications are the same as
- Embodiment 1 The improved graphite granule obtained from this embodiment has fundamentally the same average granule diameter D 50 and crystallite interlayer spacing, d 0 02- as the improved graphite granules of Embodiment 1.
- the surface modifying solution is a 3% petroleum pitch and chloroform solution.
- the surface modifying solution is a 3% petroleum pitch and chloroform solution.
- Embodiment 1 The improved graphite granules obtained from this embodiment has fundamentally the same average granule diameter D 50 and crystallite interlayer spacing, do 02 , as the improved graphite granules of Embodiment 1.
- Embodiment 4 This Embodiment uses a carbonization temperature of 800°C. Other than this, all other steps and specifications are the same as Embodiment 1.
- the improved graphite granules obtained from this embodiment has fundamentally the same average granule diameter
- Embodiment 5 This Embodiment uses a carbonization temperature of 1200°C. Other than this, all other steps and specifications are the same as Embodiment 1.
- the improved graphite granules obtained from this embodiment has fundamentally the same average granule diameter D 50 and crystallite interlayer spacing, d 002 , as the improved graphite granules in Embodiment 1.
- Embodiment 6 This Embodiment uses natural graphite with smaller average granule diameter as the unimproved graphite granules. Other than this, all other steps and specifications are the same as Embodiment 1.
- the improved graphite granules obtained from this Embodiment has an average granule diameter D 50 of 8.2um and its crystallite interlayer spacing, d 002 , is fundamentally the same as the improved graphite granules in Embodiment 1.
- Embodiment 7 This Embodiment uses natural graphite with larger average granule diameter as the unimproved graphite granules. Other than this, all other steps and specifications are the same as Embodiment 1.
- the improved graphite granules obtained from this Embodiment has an average granule diameter D 50 of 35.0um and its crystallite interlayer spacing, d 002 , is fundamentally the same as the improved graphite granules in Embodiment 1
- the properties of batteries whose negative electrodes are made from above described embodiments are compared with the properties of batteries whose negative electrodes are made from graphite granules that has not undergone the improvement described in the embodiments of this invention.
- Comparison Example 1 Directly use the natural graphite granules of Embodiment 1 as the active material for the negative electrode to make battery. Other than that, all other steps and processes for fabricating the lithium ion battery remains the same as Embodiment 1.
- Comparison Example 2 This Embodiment uses a carbonization temperature of 700°C, holding the temperature for 5 hours. Therefore, the graphite granules in this comparison example are modified but are not improved. Other than that, all other steps and specifications remains the same as
- Embodiment 1 The following operating characteristics of the batteries made from the Embodiments 1 through 7 and Comparison Examples 1 and 2 are measured and compared: For high cu ⁇ ent characteristics, C 3 c/C 0 . 5 c, the ratio of discharging capacity using 3C of cu ⁇ ent to discharge from 4.2V to 3.0V and from 0.5C of cu ⁇ ent from 4.2V to 3.0V; For high cu ⁇ ent characteristics, C 2 c/C 0 . 5 c, the ratio of discharging capacity using 2C of cu ⁇ ent to discharge from 4.2V to 3.0V and from 0.5C of cu ⁇ ent from 4.2V to 3.0V.
- C 3 c/C 0 . 5 c the ratio of discharging capacity using 3C of cu ⁇ ent to discharge from 4.2V to 3.0V and from 0.5C of cu ⁇ ent from 4.2V to 3.0V.
- ⁇ Reversible specific capacity the discharge capacity of the initial discharge of from 0.1C of cu ⁇ ent from 4.2V to 3.0 V after it had been initially charged with 0.1C of cu ⁇ ent to 4.2V)/the weight of the active material of the negative electrode; and Cycle life; a cycle is the process of using 1C of electricity to charge to 4.2V and then to discharge the electricity to 3.0V. For each cycle, the discharge capacity is the capacity of that cycle. In the measuring of electrochemical properties of the embodiments of this invention, the cycle life is the number of cycles its takes for the discharge capacity of that cycle to reach 80% of the discharge capacity of the initial cycle.
- the methodology for obtaining the electrochemical properties of the improved graphite granules in Embodiments 1 to 7 and Comparison Examples 1 and 2 are as follows:
- the specific surface area is obtained using the single-point BET method.
- the conditions for heat analysis testing are: Instrument model and number of instrument used are: NETSCH STA 449C
- the method used is the Differential Scanning Calorimetry and Thermal Gravimetric analysis, that is, DSC-TG
- the weight of the sample of unimproved graphite granules is 6.824mg
- the crucible material is: Al 2 O 3
- the furnace environment is gas with flow speed of 25Nml/min
- the temperature of the furnace environment is to start from toom temperature and increase the temperature at 10 °C /min to 1000 ° C .
- the results of the testing of the above described electrochemical characteristics are shown in the following table:
- FIG. 1 is the scanning electron micrograph of the unimproved graphite granules used in Embodiment 1.
- Figure 2 is the scanning electron micrograph of the improved graphite granules made by of Embodiment 1.
- the micrographs of Figures 1 and 2 are made using the equipment from JOEL equipment with model number JSM-5160.
- the micrograph shows that the shape of the improved graphite granules is potato shaped or spherical shaped.
- Figure 3 is the result of the heat analysis (DSC - Differential Scanning Calorimetry and Thermal Gravimetric Analysis) of the improved graphite granules in Embodiment 1.
- the peak co ⁇ esponding to 592.1 ° C is the amorphous carbon membrane.
- the peak co ⁇ esponding to 821.2 °C is the unimproved graphite granules core material.
- the peak co ⁇ esponding to 500 "C to 650°C should be the amorphous carbon membrane.
- the peak co ⁇ esponding to 750°C to 850°C should be the graphite granules core material.
- the detailed data relating to the complex peak of the unimproved graphite granules core material are listed below: Area: 15600J/g Peak: 821.2T Onset: 727.5 °C End: 874.7 °C Width: 122.8 °C (37.000%) Height: 23.2mW/mg.
- the detailed data relating to the complex peak of the amorphous carbon membrane are listed below: Area: 117.2 J/g Peak: 592.1 ° C Onset: 564.1°C End: 617.1 TJ Width: 40.0 ° C (37.000%) Height: 0.5611mW/mg.
- the improved graphite granules in the embodiments of tins invention have excellent high cu ⁇ ent characteristics with great practical potential and superiority in conditions that require a high demand for rapid charging and discharging.
- Such active material for the negative electrode retains higher reversible specific capacity, and possesses longer cycle life, is stable and reliable and can satisfy the demands of practical applications.
- the fabrication method of this improved graphite granules in the embodiments of this invention has simple technology, is low cost, and easy for industrial production. While the present invention has been described with reference to certain prefe ⁇ ed embodiments, it is to be understood that the present invention is not limited to such specific embodiments.
Abstract
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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EP04761988A EP1652250B1 (en) | 2003-07-22 | 2004-07-20 | Method of fabrication of modified graphite granules |
JP2006520651A JP2006528407A (en) | 2003-07-22 | 2004-07-20 | Improved graphite granules and method for producing the same |
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CNB03132939XA CN1259740C (en) | 2003-05-20 | 2003-07-22 | A lithium ion secondary battery |
CN03132939.X | 2003-07-22 | ||
CNB031401996A CN1305150C (en) | 2003-08-16 | 2003-08-16 | Modified graphite and its preparing method |
CN03140199.6 | 2003-08-16 |
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WO2005008810A1 true WO2005008810A1 (en) | 2005-01-27 |
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PCT/CN2004/000835 WO2005008811A1 (en) | 2003-07-22 | 2004-07-20 | Negative electrodes for rechargeable batteries |
PCT/CN2004/000834 WO2005008810A1 (en) | 2003-07-22 | 2004-07-20 | Improved graphite granules and their method of fabrication |
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PCT/CN2004/000835 WO2005008811A1 (en) | 2003-07-22 | 2004-07-20 | Negative electrodes for rechargeable batteries |
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EP (2) | EP1652250B1 (en) |
JP (2) | JP2006528408A (en) |
KR (2) | KR20060022230A (en) |
DE (1) | DE602004030799D1 (en) |
WO (2) | WO2005008811A1 (en) |
Cited By (2)
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US8999580B2 (en) | 2005-12-21 | 2015-04-07 | Show A Denko K.K. | Composite graphite particles and lithium rechargeable battery using the same |
CN115215335A (en) * | 2022-08-31 | 2022-10-21 | 浙江碳一新能源有限责任公司 | Modified graphite and preparation method and application thereof |
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JP4513822B2 (en) * | 2007-03-30 | 2010-07-28 | Tdk株式会社 | Electrode and electrochemical device |
KR100936571B1 (en) * | 2008-04-10 | 2010-01-13 | 엘에스엠트론 주식회사 | Negative active material used for secondary battery, electrode of secondary battery and secondary battery including the same |
JP5473886B2 (en) * | 2010-12-21 | 2014-04-16 | Jfeケミカル株式会社 | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
GB201307898D0 (en) * | 2012-06-14 | 2013-06-12 | Hexcel Composites Ltd | Improvements in composite materials |
US10944108B2 (en) | 2012-12-23 | 2021-03-09 | Raytheon Technologies Corporation | Graphite-containing electrode and method related thereto |
JP7388109B2 (en) | 2019-03-28 | 2023-11-29 | 三菱ケミカル株式会社 | Negative electrode materials for non-aqueous secondary batteries, negative electrodes for non-aqueous secondary batteries, and non-aqueous secondary batteries |
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- 2004-07-20 WO PCT/CN2004/000834 patent/WO2005008810A1/en not_active Application Discontinuation
- 2004-07-20 KR KR1020067001456A patent/KR100693397B1/en active IP Right Grant
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Also Published As
Publication number | Publication date |
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EP1652250A4 (en) | 2007-10-17 |
KR100693397B1 (en) | 2007-03-12 |
WO2005008811A1 (en) | 2005-01-27 |
EP1647066A1 (en) | 2006-04-19 |
JP2006528408A (en) | 2006-12-14 |
KR20060054334A (en) | 2006-05-22 |
EP1652250B1 (en) | 2011-12-28 |
JP2006528407A (en) | 2006-12-14 |
DE602004030799D1 (en) | 2011-02-10 |
EP1652250A1 (en) | 2006-05-03 |
KR20060022230A (en) | 2006-03-09 |
EP1647066A4 (en) | 2007-10-17 |
EP1647066B1 (en) | 2010-12-29 |
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