WO2015029128A1 - Matériau actif d'électrode négative, mélange d'électrode négative l'utilisant, électrode négative et batterie secondaire au lithium-ion - Google Patents

Matériau actif d'électrode négative, mélange d'électrode négative l'utilisant, électrode négative et batterie secondaire au lithium-ion Download PDF

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WO2015029128A1
WO2015029128A1 PCT/JP2013/072806 JP2013072806W WO2015029128A1 WO 2015029128 A1 WO2015029128 A1 WO 2015029128A1 JP 2013072806 W JP2013072806 W JP 2013072806W WO 2015029128 A1 WO2015029128 A1 WO 2015029128A1
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negative electrode
lithium ion
electrode active
ion secondary
secondary battery
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PCT/JP2013/072806
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English (en)
Japanese (ja)
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岡井　誠
京谷　隆
康人 干川
孝文 石井
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株式会社日立製作所
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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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/0421—Methods of deposition of the material involving vapour deposition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a negative electrode active material, a negative electrode mixture using the same, a negative electrode, and a lithium ion secondary battery.
  • Graphite-based carbonaceous materials are widely used as negative electrode active materials for lithium ion secondary batteries.
  • Patent Document 1 describes that a C / Si / O composite material is produced by growing a Si phase from a liquid phase on the surface of graphite (expanded graphite) and performing a heat treatment.
  • Non-Patent Document 1 describes an example in which silicon nanoparticles and thermally expanded graphite oxide are mechanically mixed and the characteristics are measured as a negative electrode active material.
  • the present invention prevents irreversible battery capacity reduction due to expansion and destruction of silicon nanoparticles, and provides lithium ion secondary batteries having excellent charge / discharge cycle characteristics. It is an object to provide a secondary battery.
  • the negative electrode active material for a lithium ion secondary battery of the present invention includes a carbonaceous material having electrical conductivity and silicon nanoparticles, and the silicon nanoparticles are chemically bonded to the surface of the carbonaceous material. It is characterized by having.
  • the present invention it is possible to provide a lithium ion secondary battery having excellent charge / discharge cycle characteristics by preventing electrical isolation due to expansion and contraction of silicon nanoparticles accompanying lithium ion insertion and release.
  • FIG. 2 is a scanning electron micrograph in which a part of the thermally expanded graphite oxide of FIG. 1 is further enlarged. It is a scanning electron micrograph which shows the thermal expansion graphite oxide which attached the silicon nanoparticle which is a negative electrode active material of a 1st Example. It is the scanning electron micrograph which expanded further the surface of the thermal expansion graphite oxide of FIG. It is a transmission electron micrograph which shows the silicon nanoparticle which grew on the surface of the thermal expansion graphite oxide which comprises the negative electrode active material of a 1st Example. 6 is a transmission electron micrograph showing a bonding surface of the silicon nanoparticles of FIG. 5.
  • FIG. 12B is a side view of the silicon nanoparticles of FIG. 12A. It is a fragmentary sectional view which shows the internal structure of the lithium ion secondary battery of this invention.
  • the present invention relates to a lithium ion secondary battery using an organic solvent containing a lithium salt as an electrolyte, and is composed of silicon nanoparticles and a carbonaceous material having electrical conductivity, and the silicon nanoparticles are more than the average curvature thereof.
  • the present invention relates to a lithium ion secondary battery using a composite material bonded to the surface of a carbonaceous material as a negative electrode active material through a flat portion having a small curvature.
  • the silicon nanoparticles are nanoparticles substantially composed of silicon alone.
  • the diameter of silicon nanoparticles In order to prevent expansion and destruction of silicon nanoparticles due to insertion of lithium ions, it is effective to reduce the diameter of silicon nanoparticles.
  • the extent to which the diameter of the silicon nanoparticles should be reduced depends on the battery operating conditions such as the charge / discharge rate, but is preferably about 100 nm or less. More desirably, it is 30 nm or less.
  • the silicon nanoparticles and the thermally expanded graphite oxide are simply in contact with each other simply by mechanically mixing the silicon nanoparticles and the thermally expanded graphite oxide as in the configuration described in Non-Patent Document 1.
  • the silicon nanoparticles and the thermally expanded graphite oxide are physically separated, and as a result, the silicon nanoparticles are electrically isolated.
  • the C / Si / O composite material described in Patent Document 1 has room for improvement in that the electrical conductivity is inferior to that of silicon alone because carbon and oxygen are chemically bonded to silicon.
  • the above problem is solved by realizing a state in which silicon nanoparticles having high electrical conductivity are strongly bonded to the surface of thermally expanded graphite oxide. Specifically, a state in which the silicon nanoparticles are bonded to the surface of the thermally expanded graphite oxide through a flat portion having a curvature smaller than the average curvature is realized. Such a bonded state can be realized by producing silicon nanoparticles on the surface of thermally expanded graphite oxide by a vapor phase growth method.
  • the thermally expanded graphite oxide was obtained by the heat treatment of the so-called graphite oxide oxidized by the Hummer method, that is, a mixture of sulfuric acid, sodium nitrate and potassium permanganate at 1050 ° C. for 2 hours in an argon atmosphere.
  • FIG. 1 is a scanning electron micrograph (SEM image) of thermally expanded graphite oxide.
  • a very thin graphite layer can be made from a graphite structure having an initial thickness of several tens of ⁇ m.
  • FIG. 2 is a high-magnification scanning electron micrograph of thermally expanded graphite oxide.
  • this thermally expanded graphite oxide has a structure in which a single layer of a honeycomb-like crystal lattice made of carbon atoms is overlapped by several to several tens of layers.
  • FIG. 3 is a scanning electron micrograph of thermally expanded graphite oxide having silicon nanoparticles attached to the surface, which is the negative electrode active material of the first example. This is produced by the vapor phase growth method described in detail later.
  • the particles that appear whitish in the form of particles are silicon nanoparticles, which are uniformly present on the surface of the thermally expanded graphite oxide.
  • FIG. 4 is an observation of the thermally expanded graphite oxide with the silicon nanoparticles shown in FIG. 3 attached to the surface at a high magnification.
  • spherical silicon nanoparticles 402 are uniformly attached to the surface of the thermally expanded graphite oxide 401 with an interval (approximately 30 to 100 nm).
  • the average diameter of the silicon nanoparticles 402 is about 30 nm.
  • the average diameter was calculated by statistically processing the diameter in one direction (horizontal direction) of the silicon nanoparticles 402 in the figure.
  • FIG. 5 and FIG. 6 are photographs (TEM images) obtained by photographing silicon nanoparticles on the surface of thermally expanded graphite oxide with a transmission electron microscope.
  • the portion that looks black and spherical is the silicon nanoparticle 501, and the portion that appears behind it is thermally expanded graphite oxide.
  • the silicon nanoparticle 601 shown in FIG. 6 is an oblique view of the bonding surface 602 (surface indicated by the arrow) between the silicon nanoparticle 601 and the thermally expanded graphite oxide. It can be seen that the bonding surface 602 is a flat surface. That is, it can be seen that the silicon nanoparticles 601 are bonded to the surface of the carbonaceous material via a flat portion (bonding surface 602) having a curvature smaller than the average curvature.
  • the bonding surface 602 is also referred to as an adhesion surface.
  • FIG. 13 shows the internal structure of the lithium ion secondary battery of the present invention.
  • 1310 is a positive electrode
  • 1311 is a separator
  • 1312 is a negative electrode
  • 1313 is a battery can
  • 1314 is a positive current collector tab
  • 1315 is a negative current collector tab
  • 1316 is an inner lid
  • 1317 is an internal pressure release valve
  • 1318 is a gasket
  • 1319 is a positive temperature coefficient resistance element (PTC resistance element; PTC is an abbreviation for Positive Temperature Coefficient)
  • 1320 is a battery lid.
  • the positive electrode was produced by the following procedure.
  • LiMn 2 O 4 was used as the positive electrode active material.
  • graphite powder and acetylene black were added as conductive materials.
  • the mixing ratio of the positive electrode active material, graphite powder, and acetylene black is 85.0: 7.0: 2.0 on a mass basis.
  • PVDF polyvinylidene fluoride
  • NMP 1-methyl-2-pyrrolidone
  • the positive electrode mixture refers to a mixture of a positive electrode active material, a binder and the like.
  • This slurry was applied uniformly and evenly on both sides of an aluminum foil having a thickness of 20 ⁇ m using an applicator. After the application, it was compression molded by a roll press so that the electrode density was 2.55 g / cm 3 . This was cut with a cutting machine to produce a positive electrode having a thickness of 100 ⁇ m, a length of 900 mm, and a width of 54 mm.
  • the mixing ratio of the positive electrode active material, graphite powder, acetylene black, and polyvinylidene fluoride is 85.0: 7.0: 2.0: 6.0 on a mass basis.
  • the negative electrode was produced by the following procedure.
  • the silicon and carbon composite materials described in the first and second examples were used as the negative electrode active material.
  • a solution obtained by dissolving PVDF in NMP as a binder was added to the composite material.
  • the mixing ratio of the composite material and the binder is 95.0: 5.0 on a mass basis.
  • the negative electrode mixture refers to a mixture of a negative electrode active material, a binder and the like.
  • This slurry was applied uniformly and evenly on both sides of a rolled copper foil having a thickness of 10 ⁇ m with a coating machine. After application, the electrode was compression-molded with a roll press to make the electrode density 1.3 g / cm 3 . This was cut with a cutting machine to produce a negative electrode having a thickness of 110 ⁇ m, a length of 950 mm, and a width of 56 mm.
  • the positive electrode current collecting tab 1314 and the negative electrode current collecting tab 1315 were ultrasonically welded to the positive electrode 1310 produced as described above and the uncoated portion (current collector exposed surface) of the negative electrode 1312, respectively.
  • An aluminum lead piece was used for the positive electrode current collecting tab 1314, and a nickel lead piece was used for the negative electrode current collecting tab 1315.
  • a separator 1311 made of a porous polyethylene film having a thickness of 30 ⁇ m was sandwiched between the positive electrode 1310 and the negative electrode 1312, and the positive electrode 1310, the separator 1311, and the negative electrode 1312 were wound.
  • the wound body was housed in a battery can 1313, and the negative electrode current collecting tab 1315 was connected to the bottom of the battery can 1313 by a resistance welder.
  • the positive electrode current collecting tab 1314 was connected to the bottom surface of the inner lid 1316 by ultrasonic welding.
  • a non-aqueous electrolyte was injected.
  • the solvent of the electrolytic solution was composed of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), and the volume ratio was 1: 1: 1.
  • the electrolyte is LiPF 6 at a concentration of 1 mol / L (about 0.8 mol / kg). Such an electrolytic solution was dropped from above the electrode group, and the battery lid 1320 was caulked and sealed in the battery can 1313 to obtain a lithium ion secondary battery.
  • the fabricated battery was charged to 4.20 V at a current corresponding to 0.3 CA at 25 ° C., and then charged at a constant voltage until the current became 0.03 C at 4.20 V. After 30 minutes of rest, constant current discharge was performed to 2.7 V with a constant current corresponding to 0.3 CA. This was repeated for 3 cycles to initialize the battery capacity at the third cycle, and the measured battery capacity was defined as the initial battery capacity.
  • the initial battery capacity was 1.15 Ah.
  • Cycle capacity retention rate (%) (battery capacity after 500 cycles) / (initial battery capacity) Moreover, the storage test was done at 50 degreeC. The battery was charged to 4.20 V with a current corresponding to 0.3 CA, and then constant voltage charging was performed until the current became 0.03 C at 4.20 V. After a 30-minute rest, it was stored for 3 months in a thermostatic bath at 50 ° C. After storage, the sample was taken out from the thermostat and allowed to stand at 25 ° C. for 3 hours, and the capacity was measured. The battery capacity was measured as described above. The storage capacity maintenance rate after storage for 3 months was calculated by the following formula.
  • FIG. 7 is a schematic cross-sectional view showing a bonded state of the silicon nanoparticles of FIG. 6 which is the first embodiment.
  • the surface of a thermally expanded graphite oxide 701 has a structure in which silicon nanoparticles 702 are bonded via a flat portion 703 having a certain area.
  • the thermally expanded graphite oxide 701 has a thin film structure, the shape is close to an ellipse or a rectangle, and the length of the longest portion is about 100 ⁇ m.
  • the film thickness is 100 nm or less, and it is possible to make it 10 nm or less by devising the oxidation condition and the thermal expansion condition.
  • the specific surface area is 100 m 2 / g or more, and more silicon nanoparticles 702 can be bonded to the surface. Further preferred range of the specific surface area is 100 ⁇ 1000m 2 / g.
  • the silicon nanoparticles 702 are substantially spherical and are joined to the thermally expanded graphite oxide 701 through a flat portion 703 having a curvature smaller than the average curvature. Excluding the bonding surface of the silicon nanoparticle 702 with the thermally expanded graphite oxide 701, it is twice the average radius of curvature, that is, the average diameter is 100 nm or less, more preferably 30 nm or less. Since the silicon nanoparticles 702 are produced on the surface of the thermally expanded graphite oxide 701 by a vapor phase growth method, the joint surface between the two is inevitably in a form along the surface shape of the thermally expanded graphite oxide 701. The surface of the thermally expanded graphite oxide 701 is almost flat and has a gentle curvature depending on the location.
  • the silicon nanoparticle 702 and the carbon are joined by a covalent bond between silicon (silicon) and carbon. Therefore, the bonding force is very strong, and the electrical conduction characteristics between the two are also very good.
  • FIG. 8 schematically shows the structure of a composite material composed of silicon and carbon, which is the negative electrode active material of the first embodiment.
  • a plurality of silicon nanoparticles 802 are joined to the surface of the carbonaceous material through a certain area on the surface of the thermally expanded graphite oxide 801.
  • the thermally expanded graphite oxide 801 has a thin film structure, the shape is close to an ellipse or a rectangle, and the length of the longest portion is about 100 ⁇ m. Further, the film thickness is 100 nm or less, and it is possible to make it 10 nm or less by devising the oxidation condition and the thermal expansion condition. In particular, when the film thickness is 10 nm or less, the specific surface area is 100 m 2 / g or more, and more silicon nanoparticles 802 can be bonded to the surface.
  • the silicon nanoparticles 802 are substantially spherical and are joined to the thermally expanded graphite oxide 801 through a flat portion having a curvature smaller than the average curvature.
  • the average radius of curvature is twice, that is, the average diameter is 100 nm or less, and more preferably 30 nm or less. Since the silicon nanoparticles 802 are formed on the surface of the thermally expanded graphite oxide 801 by a vapor phase growth method, the joint surface between the two is inevitably in a form along the surface shape of the thermally expanded graphite oxide 801.
  • the surface of the thermally expanded graphite oxide 801 is almost flat and has a gentle curvature depending on the location.
  • the number of silicon nanoparticles 802 bonded to the surface of the same thermally expanded graphite oxide 801 can be controlled to some extent by changing the growth conditions in the vapor phase growth method. Basically, the number can be increased by increasing the growth time.
  • the joint between the silicon nanoparticle 802 and the thermally expanded graphite oxide 801 is joined by a covalent bond between silicon and carbon. Therefore, the bonding force is very strong, and the electrical conduction characteristics between the two are also very good.
  • the mass ratio of the thermally expanded graphite oxide 801 and the silicon nanoparticles 802 is 1: 1.
  • a lithium ion secondary battery using a composite material composed of silicon and carbon having the above structure as a negative electrode active material was produced.
  • a battery capacity per mass of the negative electrode active material was 1000 mAh / g, and a storage capacity retention rate after 5000 cycles was 95%, and a high capacity and long life lithium ion secondary battery could be realized.
  • FIG. 9 is a schematic cross-sectional view showing the negative electrode active material of the second embodiment.
  • This embodiment is different from the first embodiment in that the surface of the silicon nanoparticle 902 other than the bonding surface is covered with a coating 903 mainly composed of carbon.
  • the surface of the thermally expanded graphite oxide 901 has a structure in which silicon nanoparticles 902 are bonded via a flat portion 904 having a certain area. Further, the surface of the silicon nanoparticles 902 other than the bonding surface (flat portion 904) is covered with a coating 903 containing carbon as a main component.
  • the thermally expanded graphite oxide 901 has a thin film structure, the shape is close to an ellipse or a rectangle, and the length of the longest portion is about 100 ⁇ m. Further, the film thickness is 100 nm or less, and it is possible to make it 10 nm or less by devising the oxidation condition and the thermal expansion condition. In particular, when the film thickness is 10 nm or less, the specific surface area is 100 m 2 / g or more, and more silicon nanoparticles 902 can be bonded to the surface.
  • the silicon nanoparticles 902 are substantially spherical, and are joined to the thermally expanded graphite oxide 901 through a flat portion 904 having a curvature smaller than the average curvature. Excluding the bonding surface of the silicon nanoparticles 902 with the thermally expanded graphite oxide 901, it is twice the average radius of curvature, that is, the average diameter is 100 nm or less, and more preferably 30 nm or less. Since the silicon nanoparticles 902 are produced on the surface of the thermally expanded graphite oxide 901 by a vapor phase growth method, the joint surface between the two is necessarily in a form along the surface shape of the thermally expanded graphite oxide 901. The surface of the thermally expanded graphite oxide 901 is almost flat and has a gentle curvature depending on the location.
  • the joint between the silicon nanoparticle 902 and the thermally expanded graphite oxide 901 is joined by a covalent bond between silicon and carbon. Therefore, the bonding force is very strong, and the electrical conduction characteristics between the two are also very good.
  • the thermally expanded graphite oxide 901 of the silicon nanoparticles 902 is formed by thermal vapor deposition using propylene as a raw material gas.
  • a film 903 mainly composed of carbon and having a multilayer structure of nanographene (a structure in which a single layer of graphite is laminated) is formed on the surface other than the joint portion.
  • the film 903 mainly composed of carbon is 10 nm. In some cases, it is possible to use a coating 903 mainly composed of carbon having a thickness of 1 to 30 nm.
  • the film thickness of the coating 903 containing carbon as a main component can be adjusted by changing the growth time in the thermal vapor deposition method.
  • the surface of the silicon nanoparticle 902 By covering the surface of the silicon nanoparticle 902 with the coating 903 containing carbon as a main component, the surface of the silicon nanoparticle 902 can be prevented from being oxidized and stable electric conductivity can be secured. The life of the lithium ion secondary battery can be extended.
  • FIG. 9 shows a structure in which one silicon nanoparticle 902 is bonded to the surface of thermally expanded graphite oxide 901. However, at least a plurality of silicon nanoparticles 902 are the same through a bonding surface having a certain area. It is also possible to use a structure bonded to the surface of the thermally expanded graphite oxide 901.
  • a lithium ion secondary battery using a composite material composed of silicon and carbon having the above structure as a negative electrode active material was produced. As a result, it was possible to realize a high-capacity and long-life lithium ion secondary battery with a battery capacity per mass of the negative electrode active material of 1000 mAh / g and a storage capacity retention rate of 950 cycles after 95%.
  • FIG. 10 shows the structure of the negative electrode of the lithium ion secondary battery.
  • the negative electrode shown in this drawing has a structure in which a composite material in which silicon nanoparticles 1002 are bonded to the surface of thermally expanded graphite oxide 1001 is press-molded on a negative electrode current collector 1003.
  • a film 903 mainly composed of carbon in FIG. 9 may be formed on the surface of the silicon nanoparticle 1002.
  • the negative electrode active material is mixed with a binder and applied to the negative electrode current collector 1003.
  • FIG. 11 is a schematic view showing a thermal vapor phase growth apparatus for forming silicon nanoparticles on the surface of thermally expanded graphite oxide.
  • the thermal vapor phase growth apparatus includes a reaction furnace 1101 having a raw material installation unit 1102.
  • the reaction furnace 1101 is made of quartz and has a diameter of 5 cm and a length of 40 cm.
  • the reaction furnace 1101 is connected to a first pipe for supplying hydrogen, a second pipe for supplying silicon tetrachloride (SiCl 4 ) together with hydrogen, and a third pipe for discharging exhaust gas to the outside.
  • the second pipe is provided with a container 1103 in which liquid silicon tetrachloride (SiCl 4 ) serving as a silicon raw material is placed. By bubbling with hydrogen gas (H 2 ), silicon tetrachloride (SiCl 4 ) is provided. Is introduced into the reactor 1101.
  • the third pipe is provided with a container 1104 containing a sodium hydroxide aqueous solution so as to absorb and remove harmful acid gases and the like.
  • the hydrogen is used for reducing and removing oxygen present on the surface of the thermally expanded graphite by setting the inside of the reaction furnace 1101 as a reducing atmosphere. Therefore, any gas other than hydrogen can be used as long as it can be a reducing atmosphere.
  • the first pipe and the second pipe are provided with flow controllers 1105 and 1106 (Mass Flow Controller) and a plug 1107 so that the flow rates of hydrogen and silicon tetrachloride can be adjusted respectively. .
  • flow controllers 1105 and 1106 Mass Flow Controller
  • plug 1107 so that the flow rates of hydrogen and silicon tetrachloride can be adjusted respectively.
  • the vapor pressure of silicon tetrachloride at 20 ° C. is 30 kPa.
  • the amount of silicon tetrachloride introduced is 34%.
  • the amount of silicon tetrachloride introduced (mixing ratio of hydrogen and silicon tetrachloride) can be controlled by adjusting the flow rate using the flow rate control units 1105 and 1106 and the plug 1107.
  • An example of a procedure for producing a negative electrode active material (a procedure for growing nanosilicon on the surface of thermally expanded graphite oxide) is as follows.
  • the thermally expanded graphite oxide was placed in the raw material container and installed in the raw material installation unit 1102 inside the reaction furnace 1101. Hydrogen was allowed to flow through the first pipe at a flow rate of 200 mL / min, and the second pipe was closed. In this state, the temperature of the reactor 1101 was increased from room temperature to 1000 ° C. at a rate of 10 ° C./min.
  • the hydrogen flow rate was changed to 100 mL / min, and the hydrogen flow rate of the second pipe was set to 100 mL / min. Under this condition, 17% silicon tetrachloride can be introduced.
  • the hydrogen flow rate of the first pipe was changed to 200 mL / min, held at 1000 ° C. for 30 minutes, and then naturally cooled.
  • silicon nanoparticles having an average diameter of 30 nm could be formed on the surface of the thermally expanded graphite oxide.
  • the ratio of silicon nanoparticles to the total composite material is 20% by mass.
  • the ratio of silicon nanoparticles can be adjusted by changing the growth time.
  • the ratio of silicon nanoparticles to the whole negative electrode active material is desirably 20 to 80% by mass.
  • the temperature is lowered at a rate of 10 ° C./min before the natural cooling, and when the temperature reaches 800 ° C., the first pipe Then, argon gas containing 5% propylene gas is introduced at a flow rate of 200 mL / min, and after 1 hour, it is switched to 200 mL / min pure argon gas, held for 30 minutes, and then naturally cooled.
  • argon gas containing 5% propylene gas is introduced at a flow rate of 200 mL / min, and after 1 hour, it is switched to 200 mL / min pure argon gas, held for 30 minutes, and then naturally cooled.
  • the carbon which comprises the film formed in this way has a nano graphene structure.
  • Flake graphite having an average diameter of 10 to 100 ⁇ m is immersed in a solution containing concentrated sulfuric acid, sodium nitrate and potassium permanganate for several days and stirred. This is the so-called Hummers method. After oxidation by the Hummers method, heat-expanded graphite oxide was produced by further heat treatment in an argon atmosphere at 600 to 1100 ° C. for 30 minutes to 3 hours.
  • the film thickness in the C-axis direction of the thermally expanded graphite oxide is 1.0 to 100.0 nm, and can be adjusted to some extent by changing the oxidation conditions and the foaming treatment conditions.
  • Flaked graphite and benzoyl peroxide powder are mixed and oxidized by heat treatment at 110 ° C. for 10 minutes. This is further subjected to heat treatment at 600 to 1100 ° C. for 30 minutes to 3 hours in an argon atmosphere to obtain thermally expanded graphite oxide.
  • FIG. 12A is a schematic perspective view showing the shape of silicon nanoparticles constituting the negative electrode active material of the present invention.
  • FIG. 12B is a side view of the silicon nanoparticles of FIG. 12A. These figures show the case where the silicon nanoparticles are assumed to be spherical and the joint surface with the thermally expanded graphite oxide is assumed to be a flat surface.
  • the area of the joint surface is A 2 and the area of the other spherical portion is A 1 .
  • the radius of the sphere and r, and the distance from the center of the sphere to the joining surfaces and xr (provided that 0 ⁇ x ⁇ 1), the ratio of A 2 to the total area A 1 + A 2 is, (x-1) / (X-3).
  • thermally expanded graphite oxide was used as the carbonaceous material, but desirable results can be obtained even if the carbonaceous material is fine graphite, carbon nanotube or carbon nanohorn. Since these have a regular arrangement of carbon atoms like the thermally expanded graphite oxide, they have high electrical characteristics such as conductivity.

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

La présente invention concerne un matériau actif d'électrode négative destiné à des batteries secondaires au lithium-ion, qui contient un matériau carboné présentant une conductivité électrique et des nanoparticules de silicium présentant des surfaces de liaison qui sont liées chimiquement à la surface du matériau carboné. Par conséquent, une isolation électrique due à l'expansion et à la contraction des nanoparticules de silicium accompagnant une intercalation et une désintercalation des ions lithium est empêchée, ce qui permet d'obtenir une batterie secondaire au lithium-ion qui présente d'excellentes caractéristiques de cycles de charge/décharge.
PCT/JP2013/072806 2013-08-27 2013-08-27 Matériau actif d'électrode négative, mélange d'électrode négative l'utilisant, électrode négative et batterie secondaire au lithium-ion WO2015029128A1 (fr)

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Cited By (4)

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JP2017050142A (ja) * 2015-09-02 2017-03-09 日立化成株式会社 リチウムイオン二次電池用負極活物質、およびリチウムイオン二次電池
CN111433943A (zh) * 2017-12-07 2020-07-17 新强能电池公司 包含碳化硅和碳颗粒的复合物
CN111525114A (zh) * 2020-05-09 2020-08-11 四川聚创石墨烯科技有限公司 一种连续制备免集流体硅碳负极电极纸的方法
WO2022029575A1 (fr) * 2020-08-07 2022-02-10 株式会社半導体エネルギー研究所 Électrode, matériau actif d'électrode négative, électrode négative, batterie secondaire, corps mobile, dispositif électronique, procédé de production de matériau actif d'électrode négative et procédé de production d'électrode négative

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JP2008243661A (ja) * 2007-03-28 2008-10-09 Sanyo Electric Co Ltd 円筒型リチウム二次電池
JP2010525549A (ja) * 2007-04-23 2010-07-22 アプライド・サイエンシズ・インコーポレーテッド ケイ素を炭素材料へ蒸着しリチウムイオン電池用アノードを形成する方法
JP2011503804A (ja) * 2007-11-05 2011-01-27 ナノテク インスツルメンツ インク ナノグラフェンプレートレットを主体とするリチウムイオン電池用複合負極化合物
JP2013506264A (ja) * 2009-09-29 2013-02-21 ジョージア テック リサーチ コーポレイション 電極、リチウムイオン電池ならびにこれらを作製する方法および使用する方法
WO2013031993A1 (fr) * 2011-08-31 2013-03-07 国立大学法人東北大学 MATERIAU COMPOSITE SiC, SON PROCEDE DE FABRICATION ET ELECTRODE

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008243661A (ja) * 2007-03-28 2008-10-09 Sanyo Electric Co Ltd 円筒型リチウム二次電池
JP2010525549A (ja) * 2007-04-23 2010-07-22 アプライド・サイエンシズ・インコーポレーテッド ケイ素を炭素材料へ蒸着しリチウムイオン電池用アノードを形成する方法
JP2011503804A (ja) * 2007-11-05 2011-01-27 ナノテク インスツルメンツ インク ナノグラフェンプレートレットを主体とするリチウムイオン電池用複合負極化合物
JP2013506264A (ja) * 2009-09-29 2013-02-21 ジョージア テック リサーチ コーポレイション 電極、リチウムイオン電池ならびにこれらを作製する方法および使用する方法
WO2013031993A1 (fr) * 2011-08-31 2013-03-07 国立大学法人東北大学 MATERIAU COMPOSITE SiC, SON PROCEDE DE FABRICATION ET ELECTRODE

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017050142A (ja) * 2015-09-02 2017-03-09 日立化成株式会社 リチウムイオン二次電池用負極活物質、およびリチウムイオン二次電池
CN111433943A (zh) * 2017-12-07 2020-07-17 新强能电池公司 包含碳化硅和碳颗粒的复合物
CN111433943B (zh) * 2017-12-07 2023-08-25 新强能电池公司 包含碳化硅和碳颗粒的复合物
CN111525114A (zh) * 2020-05-09 2020-08-11 四川聚创石墨烯科技有限公司 一种连续制备免集流体硅碳负极电极纸的方法
WO2022029575A1 (fr) * 2020-08-07 2022-02-10 株式会社半導体エネルギー研究所 Électrode, matériau actif d'électrode négative, électrode négative, batterie secondaire, corps mobile, dispositif électronique, procédé de production de matériau actif d'électrode négative et procédé de production d'électrode négative

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