WO2013024739A1 - Active material for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and manufacturing method for active material for non-aqueous electrolyte secondary battery - Google Patents

Active material for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and manufacturing method for active material for non-aqueous electrolyte secondary battery Download PDF

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WO2013024739A1
WO2013024739A1 PCT/JP2012/070040 JP2012070040W WO2013024739A1 WO 2013024739 A1 WO2013024739 A1 WO 2013024739A1 JP 2012070040 W JP2012070040 W JP 2012070040W WO 2013024739 A1 WO2013024739 A1 WO 2013024739A1
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transition metal
silicide
electrolyte secondary
active material
lithium
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PCT/JP2012/070040
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French (fr)
Japanese (ja)
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正信 竹内
柳田　勝功
喜田　佳典
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三洋電機株式会社
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
    • 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
    • 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
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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 non-aqueous electrolyte secondary battery active material, a non-aqueous electrolyte secondary battery, and a method for producing a non-aqueous electrolyte secondary battery active material.
  • Patent Document 1 in order to obtain high output characteristics, a composite material of metal, oxide, nitride, carbide, boride or silicide and graphite or amorphous carbon is used as a conductive agent of the positive electrode active material. It has been proposed to use.
  • the main object of the present invention is to provide a non-aqueous electrolyte secondary battery active material capable of realizing a non-aqueous electrolyte secondary battery having high output characteristics.
  • the active material for a non-aqueous electrolyte secondary battery according to the present invention is obtained by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles.
  • the non-aqueous electrolyte secondary battery according to the present invention includes a non-aqueous electrolyte secondary battery electrode having an active material layer containing the non-aqueous electrolyte secondary battery active material according to the present invention.
  • an active material for a non-aqueous electrolyte secondary battery is obtained by sintering a transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles.
  • nonaqueous electrolyte secondary battery active material capable of realizing a nonaqueous electrolyte secondary battery having high output characteristics.
  • FIG. 1 is a schematic cross-sectional view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention.
  • FIG. 2 is a schematic view of a three-electrode test cell produced in Examples 1 to 4 and Comparative Examples 1 to 5.
  • FIG. 3 is a scanning electron micrograph of the positive electrode active material produced in Example 1.
  • the nonaqueous electrolyte secondary battery 1 includes a battery container 17.
  • the battery case 17 is a cylindrical shape.
  • the shape of the battery container is not limited to a cylindrical shape.
  • the shape of the battery container may be, for example, a flat shape.
  • an electrode body 10 impregnated with a nonaqueous electrolyte is accommodated.
  • non-aqueous electrolyte for example, a known non-aqueous electrolyte can be used.
  • the nonaqueous electrolyte solvent include cyclic carbonates, chain carbonates, and mixed solvents of cyclic carbonates and chain carbonates.
  • Specific examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and the like.
  • Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and the like.
  • a chain carbonate and a mixed solvent of a cyclic carbonate and a chain carbonate are preferably used as a non-aqueous solvent having a low viscosity and a low melting point and a high lithium ion conductivity.
  • the mixing ratio of cyclic carbonate to chain carbonate should be in the range of 2: 8 to 5: 5 by volume ratio. Is preferred.
  • An ionic liquid can also be used as a non-aqueous solvent for the non-aqueous electrolyte.
  • the cation species and anion species of the ionic liquid are not particularly limited. From the viewpoint of low viscosity, electrochemical stability, and hydrophobicity, for example, a pyridinium cation, an imidazolium cation, or a quaternary ammonium cation is preferably used as the cation.
  • an ionic liquid containing a fluorine-containing imide anion is preferably used as the anion.
  • a known lithium salt can be used as the solute of the nonaqueous electrolyte.
  • the lithium salt preferably used as the solute of the nonaqueous electrolyte include a lithium salt containing at least one element selected from the group consisting of P, B, F, O, S, N, and Cl.
  • Specific examples of such a lithium salt include, for example, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 , LiClO 4 and the like.
  • LiPF 6 is more preferably used as the solute of the nonaqueous electrolyte from the viewpoint of improving the high rate charge / discharge characteristics and durability.
  • the non-aqueous electrolyte may contain a kind of solute or may contain a plurality of kinds of solutes.
  • the electrode body 10 is formed by winding a negative electrode 11, a positive electrode 12, and a separator 13 disposed between the negative electrode 11 and the positive electrode 12.
  • the separator 13 is not particularly limited as long as it can suppress a short circuit due to contact between the positive electrode 12 and the negative electrode 11 and is impregnated with a non-aqueous electrolyte to obtain lithium ion conductivity.
  • Separator 13 can be constituted by a porous film made of resin, for example.
  • resin porous membrane include, for example, polypropylene and polyethylene porous membranes, and laminates of polypropylene porous membranes and polyethylene porous membranes.
  • the negative electrode 11 has a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode current collector can be composed of, for example, a foil made of a metal such as Cu or an alloy containing a metal such as Cu.
  • the negative electrode active material layer may contain a binder or a conductive agent in addition to the negative electrode active material.
  • the negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium.
  • Examples of the negative electrode active material include a carbon material, a material alloyed with lithium, and a metal oxide such as tin oxide.
  • Examples of the material to be alloyed with lithium include one or more metals selected from the group consisting of silicon, germanium, tin and aluminum, or one or more metals selected from the group consisting of silicon, germanium, tin and aluminum. What consists of an alloy containing is mentioned.
  • the carbon material examples include natural graphite, artificial graphite, mesophase pitch-based carbon fiber (MCF), mesocarbon microbead (MCMB), coke, hard carbon, fullerene, and carbon nanotube. From the viewpoint of improving the high rate charge / discharge characteristics, it is preferable to use a carbon material obtained by coating a graphite material with low crystalline carbon as the negative electrode active material.
  • the positive electrode 12 includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector can be made of, for example, a metal such as Al or an alloy containing a metal such as Al.
  • the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode active material layer may contain an appropriate material such as a binder and a conductive agent in addition to the positive electrode active material.
  • a binder preferably used include, for example, polyvinylidene fluoride.
  • a conductive agent preferably used include carbon materials such as graphite.
  • the positive electrode active material is formed by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles. Therefore, excellent output characteristics can be obtained.
  • the following reasons can be considered as this reason. That is, since the transition metal silicide having electron conductivity is sintered on the surface of the lithium-containing transition metal composite oxide particles, the lithium-containing transition metal is also charged / discharged during which the positive electrode active material expands and contracts. The state in which the composite oxide particles and the transition metal silicide are in contact can be maintained. Therefore, it is considered that the transition metal silicide functions suitably during charge and discharge, and as a result, excellent output characteristics can be obtained.
  • transition metal silicide is simply added to the positive electrode active material. However, in that case, excellent output characteristics cannot be obtained. This is because transition metal silicide lacks flexibility and cannot be deformed following the expansion and contraction behavior of lithium-containing transition metal composite oxide particles during charge and discharge. This is considered to be because the state in contact with the transition metal silicide cannot be suitably maintained during charging and discharging.
  • transition metal borides, transition metal carbides and the like can be cited as materials having electronic conductivity.
  • excellent output characteristics can be realized by using a transition metal silicide as in this embodiment.
  • the following reasons can be considered as this reason. That is, when the boride is sintered, an oxide film is formed on the surface, so that the electron conductivity is lowered. As a result, it is considered that the output characteristics are not as excellent as when the transition metal silicide is used. Even with a transition metal silicide, an oxide film may be formed during sintering, but the oxide film formed on the surface of the transition metal silicide is considered to be very thin. Transition metal carbides do not have excellent oxidation resistance, so transition metal carbides are oxidatively decomposed during sintering, so it is considered that excellent output characteristics cannot be obtained as much as transition metal silicides are used. It is done.
  • the kind of lithium-containing transition metal composite oxide particles is not particularly limited.
  • the lithium-containing transition metal composite oxide particles preferably used include a lithium-containing transition having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co and Mn).
  • a lithium-containing transition metal composite oxide having a spinel structure represented by the general formula LiMe 2 O 4 (Me is at least one selected from the group consisting of Fe, Ni, Co, and Mn).
  • Specific examples of the lithium-containing transition metal composite oxide particles preferably used include LiCoO 2 , LiNiO 2 , LiNi 0.3 Co 0.3 Mn 0.3 O 2 , LiFePO 4 , LiMn 2 O 4 and the like.
  • the general formula Li a (Ni b Co c Mn d) lithium-containing transition metal composite oxide particles represented by O 2 is also preferably used.
  • the volume change associated with the charge / discharge reaction tends to increase.
  • the technique of sintering the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles as in the present embodiment is suitable when applied to a positive electrode active material having a large volume change associated with the charge / discharge reaction.
  • b / d is 1.4 or more.
  • the technique of sintering the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles as in this embodiment is applied to a positive electrode active material having a low Co content and a low electron conductivity. Is preferred. Therefore, c is preferably 0.45 or less.
  • the lithium-containing transition metal composite oxide particles further include at least one selected from the group consisting of aluminum, titanium, chromium, vanadium, iron, copper, zinc, niobium, molybdenum, zirconium, tin, tungsten, sodium, and potassium. May be included.
  • the preferred transition metal silicide used for example, tungsten silicide, zirconium silicide, such ZrSi 2, titanium silicide such as TiSi 2, niobium silicide, such NbSi 2, silicide such as TaSi 2, such as WSi 2 tantalum, chromium silicide such as CrSi 2, include molybdenum silicide, etc., such as MoSi 2.
  • one type of transition metal silicide may be used, or a plurality of types of transition metal silicides may be mixed and used.
  • the content of the transition metal silicide in the positive electrode active material is not particularly limited, but is preferably 0.1 mol% or more and 5 mol% or less, and more preferably 0.5 mol% or more and 2 mol% or less. . If the content of the transition metal silicide in the positive electrode active material is too low, the effect of improving the output characteristics may be too small. On the other hand, if the content of the transition metal silicide in the positive electrode active material is too high, the proportion of the lithium-containing transition metal composite oxide particles in the positive electrode active material becomes too high, and the energy density of the positive electrode may become too low.
  • the transition metal silicide may cover the entire surface of the lithium-containing transition metal composite oxide particles, or may cover only a part thereof.
  • the coverage of the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles may be less than 10%.
  • lithium-containing transition metal composite oxide particles having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co, and Mn) are used, transition is performed.
  • the metal silicide at least one selected from the group consisting of tungsten silicide, zirconium silicide and titanium silicide is preferably used, and at least one of tungsten silicide and zirconium silicide is more preferably used.
  • the active material for a nonaqueous electrolyte secondary battery (positive electrode active material) of the present embodiment can be produced by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles.
  • the positive electrode active material of this embodiment can be produced by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles.
  • the atmosphere in which the lithium transition metal composite oxide particles and the transition metal silicide are sintered may be, for example, an air atmosphere.
  • the lithium transition metal composite oxide particles and the transition metal silicide are sintered at a temperature at which at least a part of the structure of the transition metal silicide before sintering is maintained even after the sintering.
  • the lithium transition metal composite oxide particles and the transition metal silicide are sintered at a temperature not higher than the oxidative decomposition start temperature of the transition metal silicide. Therefore, when molybdenum silicide is used as the transition metal silicide, it is preferable to sinter at less than 400 ° C. When titanium silicide is used as the transition metal silicide, it is preferable to sinter at less than 500 ° C. When niobium silicide is used as the transition metal silicide, sintering is preferably performed at less than 650 ° C. When tungsten silicide is used as the transition metal silicide, it is preferable to sinter at less than 700 ° C.
  • sintering is preferably performed at less than 800 ° C.
  • tantalum silicide is used as the transition metal silicide, it is preferable to sinter at less than 900 ° C.
  • chromium silicide is used as the transition metal silicide, sintering is preferably performed at less than 1050 ° C.
  • transition metal silicide after sintering maintains the crystal structure before sintering can be confirmed using an X-ray diffraction (XRD) method or the like.
  • the transition metal silicide particles used for the sintering are used. It is preferable to appropriately adjust the diameter, sintering time, etc. so that at least a part of the structure of the transition metal silicide before sintering is maintained even after sintering.
  • the sintering temperature of the lithium transition metal composite oxide particles and the transition metal silicide is too low, the sintering of the lithium transition metal composite oxide particles and the transition metal silicide does not proceed sufficiently, and the transition metal silicide is The lithium transition metal composite oxide particles may not be firmly held on the surface. For this reason, it is preferable that sintering temperature is 300 degreeC or more, and it is more preferable that it is 500 degreeC or more.
  • the reason why the sintering of the lithium transition metal composite oxide particles and the transition metal silicide proceeds favorably even at a low temperature is that lithium contained in the lithium transition metal composite oxide particles functions as a sintering accelerator. it is conceivable that.
  • lithium-containing transition metal composite oxide particles it is preferable to use particles having a layered structure represented by a general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co and Mn). .
  • the transition metal silicide at least one selected from the group consisting of molybdenum silicide, titanium silicide, niobium silicide, tungsten silicide, zirconium silicide, tantalum silicide, and chromium silicide can be used. Among them, it is preferable to use at least one selected from the group consisting of titanium silicide, niobium silicide, tungsten silicide, zirconium silicide, tantalum silicide, and chromium silicide having a high oxidative decomposition starting temperature. This is because when the transition metal silicide having a high oxidative decomposition starting temperature is used, the sintering temperature can be increased, and thus the transition metal silicide can be strongly sintered.
  • zirconium silicide and tungsten silicide it is more preferable to use at least one of zirconium silicide and tungsten silicide, and it is more preferable to use zirconium silicide.
  • the reason why excellent output characteristics can be obtained when at least one of zirconium silicide and tungsten silicide is used is as follows. That is, the compound produced by the interdiffusion of elements between the lithium transition metal composite oxide particles and the transition metal silicide functions as a catalyst, and the activity of the reaction between the lithium-containing transition metal compound and lithium ions. It is considered that excellent output characteristics can be obtained because of the reduction in the activation energy.
  • the lithium transition metal composite oxide particles are usually mixed with a lithium source such as lithium carbonate and lithium hydroxide and a transition metal source such as transition metal hydroxide at a predetermined ratio, and oxidized and fired at about 800 to 900 ° C. Can be obtained.
  • a transition metal silicide is added at this firing stage, the transition metal silicide is oxidatively decomposed, and the transition metal silicide diffuses into the lithium-containing transition metal oxide particles, so that the conductivity of the transition metal silicide is increased. Lost. For this reason, in order to sinter the transition metal silicide on the surface of the lithium-containing transition metal oxide particles, it is desirable to mix both and then fire at the above temperature range.
  • nonaqueous electrolyte secondary battery according to the present invention will be specifically described with reference to examples.
  • the nonaqueous electrolyte secondary battery of the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof.
  • Li 2 CO 3 and Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air to form a layered structure.
  • LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 ⁇ m, and the average particle size of secondary particles was about 10 ⁇ m.
  • the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and the WSi 2 particles having an average particle diameter of 3 ⁇ m are in a molar ratio of 99: 1.
  • WSi 2 particles were adhered to the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles.
  • baked 1 hour at 600 ° C. in air to prepare a positive electrode active material WSi 2 is formed by baking on the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles.
  • a positive electrode active material, an artificial graphite as a conductive agent, and an N-methyl-2-pyrrolidone solution in which polyvinylidene fluoride as a binder is dissolved are mixed in a mass ratio of the positive electrode active material, the conductive agent, and the binder.
  • a slurry was applied onto a positive electrode current collector made of an aluminum foil, dried, rolled with a rolling roller, and an aluminum current collecting tab was attached thereto to complete a positive electrode.
  • FIG. 3 shows a scanning electron micrograph of the positive electrode active material produced in Example 1.
  • the light-colored particles are WSi 2 particles.
  • Example 1 A positive electrode was produced in the same manner as in Example 1 except that WSi 2 was not added and not fired, and a three-electrode test cell 20 was produced.
  • Comparative Example 2 Similarly to Example 1, using a mechanofusion manufactured by Hosokawa Micron Co., Ltd., LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles having an average particle diameter of 3 ⁇ m were in a molar ratio of 99: 1. WSi 2 particles were adhered to the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles. However, in Comparative Example 2, the firing of the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and the WSi 2 particles was not performed. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a three-electrode test cell 20 was produced.
  • Example 2 A positive electrode was produced in the same manner as in Example 1 except that ZrSi 2 having an average particle diameter of 2 ⁇ m was used as a transition metal silicide, and a three-electrode test cell 20 was produced. Also in Example 2, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of ZrSi 2 before firing was maintained in the transition metal silicide after firing.
  • Example 3 A positive electrode was prepared in the same manner as in Example 2 except that firing of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and ZrSi 2 particles was not performed, and a three-electrode test cell 20 was made.
  • Example 3 A positive electrode was produced in the same manner as in Example 1 except that TiSi 2 having an average particle diameter of 1 ⁇ m was used as a transition metal silicide, and a three-electrode test cell 20 was produced. Also in Example 3, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of TiSi 2 before firing was maintained even in the transition metal silicide after firing.
  • Example 4 A positive electrode was produced in the same manner as in Example 3 except that firing of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and TiSi 2 particles was not performed, and a three-electrode test cell 20 was made.
  • the three-electrode test cell was charged at a constant current of up to 4.5 V (vs. Li / Li + ) at a current density of 2.0 mA / cm 2 at 25 ° C., and then the current density was 0.025 mA. Constant current-constant voltage charging was performed, maintaining a constant potential of 4.5 V (vs. Li / Li + ) until reaching / cm 2 .
  • the three-electrode test cell was stored at 60 ° C. for 10 days, it was discharged at 10.0 mA / cm 2 at 25 ° C., and the average discharge operating potential at that time was measured as the average discharge operating position after storage.
  • Example 4 A positive electrode was produced in the same manner as in Example 1 except that the firing temperature of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles was 500 ° C. A cell 20 was produced. Also in Example 4, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of WSi 2 before firing was maintained even in the transition metal silicide after firing.
  • Comparative Example 5 A positive electrode was produced in the same manner as in Example 1 except that the firing temperature of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles was 700 ° C. A cell 20 was produced. Also in Comparative Example 5, when the crystal structure of the positive electrode active material was confirmed using XRD, no peak derived from WSi 2 crystals was observed after firing, and WSi 2 was oxidized and decomposed. Was suggested.
  • Li 2 CO 3 and Ni 0.45 Co 0.30 Mn 0.25 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air to form a layered structure.
  • LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 ⁇ m, and the average particle size of secondary particles was about 10 ⁇ m.
  • the LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles and the ZrSi 2 particles having an average particle diameter of 2 ⁇ m are set to a molar ratio of 99: 1.
  • ZrSi 2 particles were adhered to the surface of LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles.
  • baked 1 hour at 600 ° C. in air the surface of LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles ZrSi 2 particles to prepare a positive electrode active material made by firing.
  • Li 2 CO 3 and Ni 0.55 Co 0.25 Mn 0.20 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air, thereby forming a layered structure.
  • LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 ⁇ m, and the average particle size of secondary particles was about 10 ⁇ m.
  • the LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles and the ZrSi 2 particles having an average particle diameter of 2 ⁇ m are set to a molar ratio of 99: 1.
  • ZrSi 2 particles were adhered to the surface of LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles.
  • baked 1 hour at 600 ° C. in air the surface of LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles ZrSi 2 particles to prepare a positive electrode active material made by firing.
  • Example 6 A positive electrode was prepared in the same manner as in Example 1 except that the ZrSi 2 particles were not adhered to the surface of the LiNi 0.50 Co 0.20 Mn 0.30 O 2 particles and were not fired. An electrode type test cell 20 was produced.
  • Example 7 A positive electrode was prepared in the same manner as in Example 5 except that the ZrSi 2 particles were not adhered to the surface of the LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles and were not fired. An electrode type test cell 20 was produced.
  • Example 8 A positive electrode was prepared in the same manner as in Example 6 except that the ZrSi 2 particles were not attached to the surface of the LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles and were not fired. An electrode type test cell 20 was produced.

Abstract

Provided is an active material for a non-aqueous electrolyte secondary battery that enables a non-aqueous electrolyte secondary battery having high output characteristics to be realized. The active material for a non-aqueous electrolyte secondary battery is formed by sintering transition metal silicide to the surface of lithium-containing transition metal composite oxide particles.

Description

非水電解質二次電池用活物質、非水電解質二次電池及び非水電解質二次電池用活物質の製造方法Non-aqueous electrolyte secondary battery active material, non-aqueous electrolyte secondary battery, and method for producing non-aqueous electrolyte secondary battery active material
　本発明は、非水電解質二次電池用活物質、非水電解質二次電池及び非水電解質二次電池用活物質の製造方法に関する。 The present invention relates to a non-aqueous electrolyte secondary battery active material, a non-aqueous electrolyte secondary battery, and a method for producing a non-aqueous electrolyte secondary battery active material.
　近年、非水電解質二次電池を電動工具や電気自動車などの動力用電源として利用する試みがなされている。これに伴い、非水電解質二次電池の出力特性をさらに高めたいという要望がある。 In recent years, attempts have been made to use non-aqueous electrolyte secondary batteries as power sources for power tools and electric vehicles. Accordingly, there is a demand for further improving the output characteristics of the nonaqueous electrolyte secondary battery.
　例えば特許文献１には、高い出力特性を得るために、金属、酸化物、窒化物、炭化物、ホウ化物あるいはケイ化物と、黒鉛あるいは非晶質炭素との複合材料を正極活物質の導電剤として用いることが提案されている。 For example, in Patent Document 1, in order to obtain high output characteristics, a composite material of metal, oxide, nitride, carbide, boride or silicide and graphite or amorphous carbon is used as a conductive agent of the positive electrode active material. It has been proposed to use.
特開平１０－８３８１８号公報Japanese Patent Laid-Open No. 10-83818
　近年、非水電解質二次電池の出力特性をさらに高めたいという要望が高まってきている。 In recent years, there has been an increasing demand for further improving the output characteristics of non-aqueous electrolyte secondary batteries.
　本発明は、高い出力特性を有する非水電解質二次電池を実現し得る非水電解質二次電池用活物質を提供することを主な目的とする。 The main object of the present invention is to provide a non-aqueous electrolyte secondary battery active material capable of realizing a non-aqueous electrolyte secondary battery having high output characteristics.
　本発明に係る非水電解質二次電池用活物質は、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物が焼結されてなる。 The active material for a non-aqueous electrolyte secondary battery according to the present invention is obtained by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles.
　本発明に係る非水電解質二次電池は、本発明に係る非水電解質二次電池用活物質を含む活物質層を有する非水電解質二次電池用電極を備えている。 The non-aqueous electrolyte secondary battery according to the present invention includes a non-aqueous electrolyte secondary battery electrode having an active material layer containing the non-aqueous electrolyte secondary battery active material according to the present invention.
　本発明に係る非水電解質二次電池用活物質の製造方法では、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物を焼結させることにより非水電解質二次電池用活物質を得る。 In the method for producing an active material for a non-aqueous electrolyte secondary battery according to the present invention, an active material for a non-aqueous electrolyte secondary battery is obtained by sintering a transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles. .
　本発明によれば、高い出力特性を有する非水電解質二次電池を実現し得る非水電解質二次電池用活物質を提供することができる。 According to the present invention, it is possible to provide a nonaqueous electrolyte secondary battery active material capable of realizing a nonaqueous electrolyte secondary battery having high output characteristics.
図１は、本発明の一実施形態に係る非水電解質二次電池の略図的断面図である。FIG. 1 is a schematic cross-sectional view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. 図２は、実施例１～４及び比較例１～５において作製した三電極式試験用セルの模式図である。FIG. 2 is a schematic view of a three-electrode test cell produced in Examples 1 to 4 and Comparative Examples 1 to 5. 図３は、実施例１で作製した正極活物質の走査型電子顕微鏡写真である。FIG. 3 is a scanning electron micrograph of the positive electrode active material produced in Example 1.
　以下、本発明を実施した好ましい形態の一例について説明する。但し、下記の実施形態は、単なる例示である。本発明は、下記の実施形態に何ら限定されない。 Hereinafter, an example of a preferable embodiment in which the present invention is implemented will be described. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.
　また、実施形態等において参照する図面は、模式的に記載されたものであり、図面に描画された物体の寸法の比率などは、現実の物体の寸法の比率などとは異なる場合がある。具体的な物体の寸法比率等は、以下の説明を参酌して判断されるべきである。 The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The specific dimensional ratio of the object should be determined in consideration of the following description.
　図１に示されるように、非水電解質二次電池１は、電池容器１７を備えている。本実施形態では、電池容器１７は、円筒型である。但し、本発明において、電池容器の形状は、円筒型に限定されない。電池容器の形状は、例えば、扁平形状であってもよい。 As shown in FIG. 1, the nonaqueous electrolyte secondary battery 1 includes a battery container 17. In the present embodiment, the battery case 17 is a cylindrical shape. However, in the present invention, the shape of the battery container is not limited to a cylindrical shape. The shape of the battery container may be, for example, a flat shape.
　電池容器１７内には、非水電解質が含浸した電極体１０が収納されている。 In the battery container 17, an electrode body 10 impregnated with a nonaqueous electrolyte is accommodated.
　非水電解質としては、例えば、公知の非水電解質を用いることができる。非水電解質の溶媒の具体例としては、例えば、環状カーボネート、鎖状カーボネート及び環状カーボネートと鎖状カーボネートとの混合溶媒等が挙げられる。環状カーボネートの具体例としては、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネート等が挙げられる。鎖状カーボネートの具体例としては、例えば、ジメチルカーボネート、メチルエチルカーボネート、ジエチルカーボネート等が挙げられる。なかでも、低粘度且つ低融点でリチウムイオン伝導度の高い非水系溶媒として、鎖状カーボネート及び環状カーボネートと鎖状カーボネートとの混合溶媒が好ましく用いられる。環状カーボネートと鎖状カーボネートとの混合溶媒においては、環状カーボネートと鎖状カーボネートとの混合比（環状カーボネート：鎖状カーボネート）は、体積比で、２：８～５：５の範囲内にあることが好ましい。 As the non-aqueous electrolyte, for example, a known non-aqueous electrolyte can be used. Specific examples of the nonaqueous electrolyte solvent include cyclic carbonates, chain carbonates, and mixed solvents of cyclic carbonates and chain carbonates. Specific examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and the like. Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate and the like. Among these, as a non-aqueous solvent having a low viscosity and a low melting point and a high lithium ion conductivity, a chain carbonate and a mixed solvent of a cyclic carbonate and a chain carbonate are preferably used. In the mixed solvent of cyclic carbonate and chain carbonate, the mixing ratio of cyclic carbonate to chain carbonate (cyclic carbonate: chain carbonate) should be in the range of 2: 8 to 5: 5 by volume ratio. Is preferred.
　非水電解質の非水系溶媒としてイオン性液体を用いることもできる。イオン性液体のカチオン種、アニオン種は、特に限定されない。低粘度、電気化学的安定性、疎水性の観点から、カチオンとしては、例えばピリジニウムカチオン、イミダゾリウムカチオン、４級アンモニウムカチオンが好ましく用いられる。アニオンとしては、例えばフッ素含有イミド系アニオンを含むイオン性液体が好ましく用いられる。 An ionic liquid can also be used as a non-aqueous solvent for the non-aqueous electrolyte. The cation species and anion species of the ionic liquid are not particularly limited. From the viewpoint of low viscosity, electrochemical stability, and hydrophobicity, for example, a pyridinium cation, an imidazolium cation, or a quaternary ammonium cation is preferably used as the cation. As the anion, for example, an ionic liquid containing a fluorine-containing imide anion is preferably used.
　非水電解質の溶質としては、例えば、公知のリチウム塩を用いることができる。非水電解質の溶質として好ましく用いられるリチウム塩としては、Ｐ、Ｂ、Ｆ、Ｏ、Ｓ、Ｎ及びＣｌからなる群から選ばれた少なくとも一種の元素を含むリチウム塩があげられる。このようなリチウム塩の具体例としては、例えば、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ４Ｆ９ＳＯ２）、ＬｉＣ（Ｃ２Ｆ５ＳＯ２）３、ＬｉＡｓＦ６、ＬｉＣｌＯ４等があげられる。なかでも、高率充放電特性や耐久性を改善する観点から、ＬｉＰＦ６が非水電解質の溶質としてより好ましく用いられる。非水電解質は、一種の溶質を含んでいてもよいし、複数種類の溶質を含んでいてもよい。 As the solute of the nonaqueous electrolyte, for example, a known lithium salt can be used. Examples of the lithium salt preferably used as the solute of the nonaqueous electrolyte include a lithium salt containing at least one element selected from the group consisting of P, B, F, O, S, N, and Cl. Specific examples of such a lithium salt include, for example, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 , LiClO 4 and the like. Among these, LiPF 6 is more preferably used as the solute of the nonaqueous electrolyte from the viewpoint of improving the high rate charge / discharge characteristics and durability. The non-aqueous electrolyte may contain a kind of solute or may contain a plurality of kinds of solutes.
　電極体１０は、負極１１と、正極１２と、負極１１及び正極１２の間に配置されているセパレータ１３とが巻回されてなる。 The electrode body 10 is formed by winding a negative electrode 11, a positive electrode 12, and a separator 13 disposed between the negative electrode 11 and the positive electrode 12.
　セパレータ１３は、正極１２と負極１１との接触による短絡を抑制でき、かつ非水電解質を含浸して、リチウムイオン伝導性が得られるものである限りにおいて特に限定されない。セパレータ１３は、例えば、樹脂製の多孔膜により構成することができる。樹脂製の多孔膜の具体例としては、例えば、ポリプロピレン製やポリエチレン製の多孔膜、ポリプロピレン製の多孔膜とポリエチレン製の多孔膜との積層体などがあげられる。 The separator 13 is not particularly limited as long as it can suppress a short circuit due to contact between the positive electrode 12 and the negative electrode 11 and is impregnated with a non-aqueous electrolyte to obtain lithium ion conductivity. Separator 13 can be constituted by a porous film made of resin, for example. Specific examples of the resin porous membrane include, for example, polypropylene and polyethylene porous membranes, and laminates of polypropylene porous membranes and polyethylene porous membranes.
　負極１１は、負極集電体と、負極集電体の少なくとも一方の表面の上に配された負極活物質層とを有する。負極集電体は、例えば、Ｃｕなどの金属や、Ｃｕなどの金属を含む合金からなる箔により構成することができる。 The negative electrode 11 has a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector can be composed of, for example, a foil made of a metal such as Cu or an alloy containing a metal such as Cu.
　負極活物質層は、負極活物質に加えて、バインダーや導電剤等を含むものであってもよい。負極活物質は、リチウムを可逆的に吸蔵・放出できるものでれば特に限定されない。負極活物質としては、例えば、炭素材料、リチウムと合金化する材料、酸化スズ等の金属酸化物等があげられる。リチウムと合金化する材料としては、例えば、シリコン、ゲルマニウム、スズ及びアルミニウムからなる群から選ばれた一種以上の金属、またはシリコン、ゲルマニウム、スズ及びアルミニウムからなる群から選ばれた一種以上の金属を含む合金からなるものが挙げられる。炭素材料の具体例としては、例えば、天然黒鉛、人造黒鉛、メソフェーズピッチ系炭素繊維（ＭＣＦ）、メソカーボンマイクロビーズ（ＭＣＭＢ）、コークス、ハードカーボン、フラーレン、カーボンナノチューブ等があげられる。高率充放電特性を向上させる観点からは、黒鉛材料を低結晶性炭素で被覆した炭素材料を負極活物質として用いることが好ましい。 The negative electrode active material layer may contain a binder or a conductive agent in addition to the negative electrode active material. The negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium. Examples of the negative electrode active material include a carbon material, a material alloyed with lithium, and a metal oxide such as tin oxide. Examples of the material to be alloyed with lithium include one or more metals selected from the group consisting of silicon, germanium, tin and aluminum, or one or more metals selected from the group consisting of silicon, germanium, tin and aluminum. What consists of an alloy containing is mentioned. Specific examples of the carbon material include natural graphite, artificial graphite, mesophase pitch-based carbon fiber (MCF), mesocarbon microbead (MCMB), coke, hard carbon, fullerene, and carbon nanotube. From the viewpoint of improving the high rate charge / discharge characteristics, it is preferable to use a carbon material obtained by coating a graphite material with low crystalline carbon as the negative electrode active material.
　正極１２は、正極集電体と、正極集電体の少なくとも一方の表面の上に配された正極活物質層とを備えている。正極集電体は、例えば、Ａｌなどの金属や、Ａｌなどの金属を含む合金により構成することができる。 The positive electrode 12 includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector can be made of, for example, a metal such as Al or an alloy containing a metal such as Al.
　正極活物質層は、正極活物質を含む。正極活物質層は、正極活物質に加えて、結着剤や導電剤などの適宜の材料を含んでいてもよい。好ましく用いられる結着剤の具体例としては、例えばポリフッ化ビニリデン等が挙げられる。好ましく用いられる導電剤の具体例としては、例えば、黒鉛などの炭素材料等が挙げられる。 The positive electrode active material layer includes a positive electrode active material. The positive electrode active material layer may contain an appropriate material such as a binder and a conductive agent in addition to the positive electrode active material. Specific examples of the binder preferably used include, for example, polyvinylidene fluoride. Specific examples of the conductive agent preferably used include carbon materials such as graphite.
　本実施形態において、正極活物質は、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物が焼結されてなる。このため、優れた出力特性を得ることができる。この理由としては、以下の理由が考えられる。即ち、電子伝導性を有する遷移金属ケイ化物が、リチウム含有遷移金属複合酸化物粒子の表面に焼結しているため、正極活物質の膨張や収縮が生じる充放電中においても、リチウム含有遷移金属複合酸化物粒子と遷移金属ケイ化物とが接触した状態を維持することができる。従って、充放電時に遷移金属ケイ化物が好適に機能し、その結果、優れた出力特性が得られるものと考えられる。 In this embodiment, the positive electrode active material is formed by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles. Therefore, excellent output characteristics can be obtained. The following reasons can be considered as this reason. That is, since the transition metal silicide having electron conductivity is sintered on the surface of the lithium-containing transition metal composite oxide particles, the lithium-containing transition metal is also charged / discharged during which the positive electrode active material expands and contracts. The state in which the composite oxide particles and the transition metal silicide are in contact can be maintained. Therefore, it is considered that the transition metal silicide functions suitably during charge and discharge, and as a result, excellent output characteristics can be obtained.
　なお、遷移金属ケイ化物を正極活物質中に単に添加することも考えられる。しかしながら、その場合は、優れた出力特性が得られない。これは、遷移金属ケイ化物は柔軟性に欠け、充放電時のリチウム含有遷移金属複合酸化物粒子の膨張や収縮挙動に追随して変形することができないため、リチウム含有遷移金属複合酸化物粒子と遷移金属ケイ化物とが接触した状態を充放電時に好適に維持できないためであると考えられる。 Note that it is also conceivable that the transition metal silicide is simply added to the positive electrode active material. However, in that case, excellent output characteristics cannot be obtained. This is because transition metal silicide lacks flexibility and cannot be deformed following the expansion and contraction behavior of lithium-containing transition metal composite oxide particles during charge and discharge. This is considered to be because the state in contact with the transition metal silicide cannot be suitably maintained during charging and discharging.
　また、電子伝導性を有する材料としては、遷移金属ケイ化物以外にも、遷移金属ホウ化物、遷移金属炭化物等が挙げられる。これらの電子伝導性を有する材料の中でも、本実施形態のように、遷移金属ケイ化物を用いることにより、優れた出力特性を実現することができる。この理由としては、以下のような理由が考えられる。即ち、ホウ化物を焼結すると表面に酸化皮膜が形成されるため、電子伝導性が低くなり、その結果、遷移金属ケイ化物を用いた場合ほど優れた出力特性が得られないものと考えられる。遷移金属ケイ化物であっても、焼結時に酸化皮膜が形成される可能性はあるが、遷移金属ケイ化物の表面に形成される酸化皮膜は非常に薄いものと考えられる。遷移金属炭化物は、優れた耐酸化性を有さないため、焼結時に遷移金属炭化物が酸化分解してしまうため、遷移金属ケイ化物を用いた場合ほど優れた出力特性が得られないものと考えられる。 In addition to transition metal silicides, transition metal borides, transition metal carbides and the like can be cited as materials having electronic conductivity. Among these materials having electronic conductivity, excellent output characteristics can be realized by using a transition metal silicide as in this embodiment. The following reasons can be considered as this reason. That is, when the boride is sintered, an oxide film is formed on the surface, so that the electron conductivity is lowered. As a result, it is considered that the output characteristics are not as excellent as when the transition metal silicide is used. Even with a transition metal silicide, an oxide film may be formed during sintering, but the oxide film formed on the surface of the transition metal silicide is considered to be very thin. Transition metal carbides do not have excellent oxidation resistance, so transition metal carbides are oxidatively decomposed during sintering, so it is considered that excellent output characteristics cannot be obtained as much as transition metal silicides are used. It is done.
　リチウム含有遷移金属複合酸化物粒子の種類は特に限定されない。好ましく用いられるリチウム含有遷移金属複合酸化物粒子としては、一般式ＬｉＭｅＯ２（但し、Ｍｅは、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表される層状構造を有するリチウム含有遷移金属複合酸化物からなるもの、一般式ＬｉＭｅＰＯ４（ＭｅはＦｅ、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表されるオリビン構造を有するリチウム含有遷移金属複合酸化物からなるもの、一般式ＬｉＭｅ２Ｏ４（ＭｅはＦｅ、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表されるスピネル構造を有するリチウム含有遷移金属複合酸化物からなるもの等が挙げられる。好ましく用いられるリチウム含有遷移金属複合酸化物粒子の具体例としては、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＮｉ０．３Ｃｏ０．３Ｍｎ０．３Ｏ２、ＬｉＦｅＰＯ４、ＬｉＭｎ２Ｏ４などが挙げられる。 The kind of lithium-containing transition metal composite oxide particles is not particularly limited. The lithium-containing transition metal composite oxide particles preferably used include a lithium-containing transition having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co and Mn). A metal composite oxide, a lithium-containing transition metal composite oxide having an olivine structure represented by the general formula LiMePO 4 (Me is at least one selected from the group consisting of Fe, Ni, Co and Mn) And a lithium-containing transition metal composite oxide having a spinel structure represented by the general formula LiMe 2 O 4 (Me is at least one selected from the group consisting of Fe, Ni, Co, and Mn). Specific examples of the lithium-containing transition metal composite oxide particles preferably used include LiCoO 2 , LiNiO 2 , LiNi 0.3 Co 0.3 Mn 0.3 O 2 , LiFePO 4 , LiMn 2 O 4 and the like.
　また、一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２で表されるリチウム含有遷移金属複合酸化物粒子も好ましく用いられる。この場合、上記一般式において、０．９≦ａ／（ｂ＋ｃ＋ｄ）≦１．２、１．４≦ｂ／ｄ、０≦ｃ≦０．４５が満たされることが好ましい。ｂ／ｄの比が高くなるに伴い、充放電反応に伴う体積変化が大きくなる傾向にある。本実施形態のように遷移金属ケイ化物をリチウム含有遷移金属複合酸化物粒子の表面に焼結させる技術は、充放電反応に伴う体積変化が大きい正極活物質に適用した場合に好適である。従って、ｂ／ｄが１．４以上の場合特に高い効果が得られる。また、本実施形態のように遷移金属ケイ化物をリチウム含有遷移金属複合酸化物粒子の表面に焼結させる技術は、Ｃｏの含有率が低く、電子伝導性が低い正極活物質に適用した場合に好適である。従って、ｃは０．４５以下であることが好ましい。 Moreover, the general formula Li a (Ni b Co c Mn d) lithium-containing transition metal composite oxide particles represented by O 2 is also preferably used. In this case, it is preferable that 0.9 ≦ a / (b + c + d) ≦ 1.2, 1.4 ≦ b / d, and 0 ≦ c ≦ 0.45 are satisfied in the above general formula. As the b / d ratio increases, the volume change associated with the charge / discharge reaction tends to increase. The technique of sintering the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles as in the present embodiment is suitable when applied to a positive electrode active material having a large volume change associated with the charge / discharge reaction. Therefore, a particularly high effect is obtained when b / d is 1.4 or more. In addition, the technique of sintering the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles as in this embodiment is applied to a positive electrode active material having a low Co content and a low electron conductivity. Is preferred. Therefore, c is preferably 0.45 or less.
　リチウム含有遷移金属複合酸化物粒子は、アルミ二ウム、チタン、クロム、バナジウム、鉄、銅、亜鉛、ニオブ、モリブデン、ジルコニウム、錫、タングステン、ナトリウム及びカリウムからなる群から選ばれた少なくとも一種をさらに含んでいてもよい。 The lithium-containing transition metal composite oxide particles further include at least one selected from the group consisting of aluminum, titanium, chromium, vanadium, iron, copper, zinc, niobium, molybdenum, zirconium, tin, tungsten, sodium, and potassium. May be included.
　好ましく用いられる遷移金属ケイ化物としては、例えば、ＷＳｉ２などのケイ化タングステン、ＺｒＳｉ２などのケイ化ジルコニウム、ＴｉＳｉ２などのケイ化チタン、ＮｂＳｉ２などのケイ化ニオブ、ＴａＳｉ２などのケイ化タンタル、ＣｒＳｉ２などのケイ化クロム、ＭｏＳｉ２などのケイ化モリブデン等が挙げられる。これらのうちの一種の遷移金属ケイ化物を用いてもよく、複数種類の遷移金属ケイ化物を混合して用いてもよい。 The preferred transition metal silicide used, for example, tungsten silicide, zirconium silicide, such ZrSi 2, titanium silicide such as TiSi 2, niobium silicide, such NbSi 2, silicide such as TaSi 2, such as WSi 2 tantalum, chromium silicide such as CrSi 2, include molybdenum silicide, etc., such as MoSi 2. Of these, one type of transition metal silicide may be used, or a plurality of types of transition metal silicides may be mixed and used.
　正極活物質における遷移金属ケイ化物の含有率は、特に限定されないが、０．１モル％以上５モル％以下であることが好ましく、０．５モル％以上２モル％以下であることがより好ましい。正極活物質における遷移金属ケイ化物の含有率が低すぎると、出力特性の改善効果が小さくなりすぎる場合がある。一方、正極活物質における遷移金属ケイ化物の含有率が高すぎると、正極活物質に占めるリチウム含有遷移金属複合酸化物粒子の割合が高くなりすぎ、正極のエネルギー密度が低くなりすぎる場合がある。 The content of the transition metal silicide in the positive electrode active material is not particularly limited, but is preferably 0.1 mol% or more and 5 mol% or less, and more preferably 0.5 mol% or more and 2 mol% or less. . If the content of the transition metal silicide in the positive electrode active material is too low, the effect of improving the output characteristics may be too small. On the other hand, if the content of the transition metal silicide in the positive electrode active material is too high, the proportion of the lithium-containing transition metal composite oxide particles in the positive electrode active material becomes too high, and the energy density of the positive electrode may become too low.
　遷移金属ケイ化物は、リチウム含有遷移金属複合酸化物粒子の表面の全体を覆っていてもよいし、一部のみを覆っていてもよい。リチウム含有遷移金属複合酸化物粒子の表面における遷移金属ケイ化物の被覆率は、１０％未満であってもよい。 The transition metal silicide may cover the entire surface of the lithium-containing transition metal composite oxide particles, or may cover only a part thereof. The coverage of the transition metal silicide on the surface of the lithium-containing transition metal composite oxide particles may be less than 10%.
　なお、一般式ＬｉＭｅＯ２（但し、Ｍｅは、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表される層状構造を有するリチウム含有遷移金属複合酸化物粒子を用いた場合は、遷移金属ケイ化物として、ケイ化タングステン、ケイ化ジルコニウム及びケイ化チタンからなる群から選ばれた少なくともひとつを用いることが好ましく、ケイ化タングステン及びケイ化ジルコニウムの少なくとも一方を用いることがより好ましい。 When lithium-containing transition metal composite oxide particles having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co, and Mn) are used, transition is performed. As the metal silicide, at least one selected from the group consisting of tungsten silicide, zirconium silicide and titanium silicide is preferably used, and at least one of tungsten silicide and zirconium silicide is more preferably used.
　本実施形態の非水電解質二次電池用活物質（正極活物質）は、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物を焼結させることにより製造することができる。 The active material for a nonaqueous electrolyte secondary battery (positive electrode active material) of the present embodiment can be produced by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles.
　本実施形態の正極活物質は、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物を焼結させることにより製造することができる。リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結を行う雰囲気は、例えば、大気雰囲気であってもよい。 The positive electrode active material of this embodiment can be produced by sintering a transition metal silicide on the surface of lithium-containing transition metal composite oxide particles. The atmosphere in which the lithium transition metal composite oxide particles and the transition metal silicide are sintered may be, for example, an air atmosphere.
　遷移金属ケイ化物をリチウム遷移金属複合酸化物粒子の表面に強固に保持する観点からは、焼結温度を高くすることが好ましい。但し、焼結温度が高すぎると、優れた出力特性を実現できなくなる場合がある。これは、遷移金属ケイ化物の構造が焼結により変化してしまい、遷移金属ケイ化物の導電性が低くなること、及び生成した酸化ケイ素や遷移金属ケイ化物により、活物質の表面における充放電反応が阻害されることに起因するものと考えられる。従って、リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結を、焼結前の遷移金属ケイ化物の少なくとも一部の構造が焼結後にも維持される温度で行うことが好ましい。リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結を、遷移金属ケイ化物の酸化分解開始温度以下の温度で行うことがより好ましい。従って、遷移金属ケイ化物としてケイ化モリブデンを用いた場合は、４００℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化チタンを用いた場合は、５００℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化ニオブを用いた場合は、６５０℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化タングステンを用いた場合は、７００℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化ジルコニウムを用いた場合は、８００℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化タンタルを用いた場合は、９００℃未満で焼結することが好ましい。遷移金属ケイ化物としてケイ化クロムを用いた場合は、１０５０℃未満で焼結することが好ましい。 From the viewpoint of firmly holding the transition metal silicide on the surface of the lithium transition metal composite oxide particles, it is preferable to increase the sintering temperature. However, if the sintering temperature is too high, excellent output characteristics may not be realized. This is because the structure of the transition metal silicide is changed by sintering, the conductivity of the transition metal silicide is lowered, and the generated silicon oxide or transition metal silicide causes a charge / discharge reaction on the surface of the active material. This is considered to be caused by the inhibition. Therefore, it is preferable that the lithium transition metal composite oxide particles and the transition metal silicide are sintered at a temperature at which at least a part of the structure of the transition metal silicide before sintering is maintained even after the sintering. More preferably, the lithium transition metal composite oxide particles and the transition metal silicide are sintered at a temperature not higher than the oxidative decomposition start temperature of the transition metal silicide. Therefore, when molybdenum silicide is used as the transition metal silicide, it is preferable to sinter at less than 400 ° C. When titanium silicide is used as the transition metal silicide, it is preferable to sinter at less than 500 ° C. When niobium silicide is used as the transition metal silicide, sintering is preferably performed at less than 650 ° C. When tungsten silicide is used as the transition metal silicide, it is preferable to sinter at less than 700 ° C. When zirconium silicide is used as the transition metal silicide, sintering is preferably performed at less than 800 ° C. When tantalum silicide is used as the transition metal silicide, it is preferable to sinter at less than 900 ° C. When chromium silicide is used as the transition metal silicide, sintering is preferably performed at less than 1050 ° C.
　焼結後の遷移金属ケイ化物が、焼結前の結晶構造を維持しているか否かは、Ｘ線回折（ＸＲＤ）法等を用いて確認することができる。 Whether the transition metal silicide after sintering maintains the crystal structure before sintering can be confirmed using an X-ray diffraction (XRD) method or the like.
　なお、リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結を、遷移金属ケイ化物の酸化分解開始温度以上の温度で行う場合には、焼結に使用する遷移金属ケイ化物粒子の粒子径や焼結時間などを適宜調整し、焼結前の遷移金属ケイ化物の少なくとも一部の構造が焼結後にも維持されるようにすることが好ましい。 When the lithium transition metal composite oxide particles and the transition metal silicide are sintered at a temperature equal to or higher than the oxidation decomposition start temperature of the transition metal silicide, the transition metal silicide particles used for the sintering are used. It is preferable to appropriately adjust the diameter, sintering time, etc. so that at least a part of the structure of the transition metal silicide before sintering is maintained even after sintering.
　リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結温度が低すぎると、リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結が十分に進行せず、遷移金属ケイ化物がリチウム遷移金属複合酸化物粒子の表面に強固に保持されない場合がある。このため、焼結温度は、３００℃以上であることが好ましく、５００℃以上であることがより好ましい。 If the sintering temperature of the lithium transition metal composite oxide particles and the transition metal silicide is too low, the sintering of the lithium transition metal composite oxide particles and the transition metal silicide does not proceed sufficiently, and the transition metal silicide is The lithium transition metal composite oxide particles may not be firmly held on the surface. For this reason, it is preferable that sintering temperature is 300 degreeC or more, and it is more preferable that it is 500 degreeC or more.
　なお、リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との焼結が低温でも好適に進行するのは、リチウム遷移金属複合酸化物粒子に含まれるリチウムが焼結促進剤として機能するためであると考えられる。 The reason why the sintering of the lithium transition metal composite oxide particles and the transition metal silicide proceeds favorably even at a low temperature is that lithium contained in the lithium transition metal composite oxide particles functions as a sintering accelerator. it is conceivable that.
　リチウム含有遷移金属複合酸化物粒子としては、一般式ＬｉＭｅＯ２（但し、Ｍｅは、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表される層状構造を有する粒子を用いることが好ましい。 As the lithium-containing transition metal composite oxide particles, it is preferable to use particles having a layered structure represented by a general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co and Mn). .
　遷移金属ケイ化物としては、ケイ化モリブデン、ケイ化チタン、ケイ化ニオブ、ケイ化タングステン、ケイ化ジルコニウム、ケイ化タンタル及びケイ化クロムからなる群から選ばれた少なくともひとつを用いることができる。なかでも、酸化分解開始温度が高い、ケイ化チタン、ケイ化ニオブ、ケイ化タングステン、ケイ化ジルコニウム、ケイ化タンタル及びケイ化クロムからなる群から選ばれた少なくともひとつを用いることが好ましい。酸化分解開始温度が高い遷移金属ケイ化物を用いた場合は、焼結温度を高くすることができるため、遷移金属ケイ化物を強固に焼結させることができるからである。 As the transition metal silicide, at least one selected from the group consisting of molybdenum silicide, titanium silicide, niobium silicide, tungsten silicide, zirconium silicide, tantalum silicide, and chromium silicide can be used. Among them, it is preferable to use at least one selected from the group consisting of titanium silicide, niobium silicide, tungsten silicide, zirconium silicide, tantalum silicide, and chromium silicide having a high oxidative decomposition starting temperature. This is because when the transition metal silicide having a high oxidative decomposition starting temperature is used, the sintering temperature can be increased, and thus the transition metal silicide can be strongly sintered.
　また、さらに優れた出力特性を得る観点から、ケイ化ジルコニウム及びケイ化タングステンの少なくとも一方を用いることがより好ましく、ケイ化ジルコニウムを用いることがさらに好ましい。ケイ化ジルコニウム及びケイ化タングステンの少なくとも一方を用いた場合に優れた出力特性が得られる理由としては、以下の理由が考えられる。即ち、リチウム遷移金属複合酸化物粒子と遷移金属ケイ化物との間で元素が相互拡散することに起因して生成する化合物が触媒として機能し、リチウム含有遷移金属化合物とリチウムイオンとの反応の活性化エネルギーが低くなるため、優れた出力特性が得られるものと考えられる。 Further, from the viewpoint of obtaining further excellent output characteristics, it is more preferable to use at least one of zirconium silicide and tungsten silicide, and it is more preferable to use zirconium silicide. The reason why excellent output characteristics can be obtained when at least one of zirconium silicide and tungsten silicide is used is as follows. That is, the compound produced by the interdiffusion of elements between the lithium transition metal composite oxide particles and the transition metal silicide functions as a catalyst, and the activity of the reaction between the lithium-containing transition metal compound and lithium ions. It is considered that excellent output characteristics can be obtained because of the reduction in the activation energy.
　なお、リチウム遷移金属複合酸化物粒子は、通常、炭酸リチウムや水酸化リチウム等のリチウム源と、遷移金属水酸化物等の遷移金属源を所定比で混合し、８００～９００℃程度で酸化焼成することにより得られる。この焼成段階で遷移金属ケイ化物を加えた場合、遷移金属ケイ化物が酸化分解するとともに、リチウム含有遷移金属酸化物粒子中に遷移金属ケイ化物が拡散してしまい、遷移金属ケイ化物の導電性が失われる。このため、リチウム含有遷移金属酸化物粒子の表面に遷移金属ケイ化物を焼結するには、両者を混合した上で上記の温度範囲で焼成することが望ましい。 The lithium transition metal composite oxide particles are usually mixed with a lithium source such as lithium carbonate and lithium hydroxide and a transition metal source such as transition metal hydroxide at a predetermined ratio, and oxidized and fired at about 800 to 900 ° C. Can be obtained. When a transition metal silicide is added at this firing stage, the transition metal silicide is oxidatively decomposed, and the transition metal silicide diffuses into the lithium-containing transition metal oxide particles, so that the conductivity of the transition metal silicide is increased. Lost. For this reason, in order to sinter the transition metal silicide on the surface of the lithium-containing transition metal oxide particles, it is desirable to mix both and then fire at the above temperature range.
　以下、この発明に係る非水電解質二次電池について実施例を挙げて具体的に説明する。なお、本発明の非水電解質二次電池は下記の実施例に限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施できるものである。 Hereinafter, the nonaqueous electrolyte secondary battery according to the present invention will be specifically described with reference to examples. The nonaqueous electrolyte secondary battery of the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof.
　（実施例１）
　Ｌｉ２ＣＯ３と、共沈法によって得たＮｉ０．５Ｃｏ０．２Ｍｎ０．３（ＯＨ）２とを所定の割合で混合し、これらを空気中において焼成することにより、層状構造を有するＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子を作製した。この粒子の一次粒子の平均粒子径は、約１μｍであり、二次粒子の平均粒子径は、約１０μｍであった。 (Example 1)
Li 2 CO 3 and Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air to form a layered structure. LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 μm, and the average particle size of secondary particles was about 10 μm.
　次に、ホソカワミクロン社製メカノフュージョンを用いて、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、平均粒子径が３μｍのＷＳｉ２粒子とを９９：１のモル比となるように混合し、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子の表面にＷＳｉ２粒子を付着させた。その後、空気中において６００℃で１時間焼成し、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子の表面にＷＳｉ２が焼成されてなる正極活物質を作製した。ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＷＳｉ２の構造が焼成後の遷移金属ケイ化物においても維持されていることを確認できた。 Next, using a mechanofusion manufactured by Hosokawa Micron Co., Ltd., the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and the WSi 2 particles having an average particle diameter of 3 μm are in a molar ratio of 99: 1. After mixing, WSi 2 particles were adhered to the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles. Then baked 1 hour at 600 ° C. in air to prepare a positive electrode active material WSi 2 is formed by baking on the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles. When the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of WSi 2 before firing was maintained in the transition metal silicide after firing.
　次に、正極活物質と、導電剤として人造黒鉛と、結着剤のポリフッ化ビニリデンを溶解させたＮ－メチル－２－ピロリドン溶液とを、正極活物質と導電剤と結着剤の質量比が９５：３：２となるように混練し、スラリーを作製した。そのスラリーをアルミニウム箔からなる正極集電体の上に塗布し、乾燥させた後、圧延ローラーにより圧延し、これにアルミニウムの集電タブを取りつけることにより正極を完成させた。 Next, a positive electrode active material, an artificial graphite as a conductive agent, and an N-methyl-2-pyrrolidone solution in which polyvinylidene fluoride as a binder is dissolved are mixed in a mass ratio of the positive electrode active material, the conductive agent, and the binder. Was kneaded so as to be 95: 3: 2 to prepare a slurry. The slurry was applied onto a positive electrode current collector made of an aluminum foil, dried, rolled with a rolling roller, and an aluminum current collecting tab was attached thereto to complete a positive electrode.
　そして、図２に示すように、正極を作用極２１として用いる一方、負極となる対極２２及び参照極２３にそれぞれ金属リチウムを用い、また非水電解質２４として、エチレンカーボネートとメチルエチルカーボネートとジメチルカーボネートとを３：３：４の体積比で混合させた混合溶媒にＬｉＰＦ６を１モル／ｌの濃度になるように溶解させ、さらにビニレンカーボネートを１質量％溶解させたものを用いて、三電極式試験用セル２０を作製した。 Then, as shown in FIG. 2, while using the positive electrode as the working electrode 21, metallic lithium is used for the counter electrode 22 and the reference electrode 23, respectively, and the nonaqueous electrolyte 24 is ethylene carbonate, methyl ethyl carbonate, and dimethyl carbonate. Three-electrode was prepared by dissolving LiPF 6 in a mixed solvent in which a volume ratio of 3: 3: 4 was mixed to a concentration of 1 mol / l and further dissolving 1% by mass of vinylene carbonate. A cell 20 for the type test was produced.
　また、図３に、実施例１で作製した正極活物質の走査型電子顕微鏡写真を示す。図３に示す写真において、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子に付着している粒子のうち、淡色の粒子がＷＳｉ２粒子である。 FIG. 3 shows a scanning electron micrograph of the positive electrode active material produced in Example 1. In the photograph shown in FIG. 3, among the particles adhering to the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles, the light-colored particles are WSi 2 particles.
　（比較例１）
　ＷＳｉ２を添加しなかったこと、及び焼成しなかったこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 1)
A positive electrode was produced in the same manner as in Example 1 except that WSi 2 was not added and not fired, and a three-electrode test cell 20 was produced.
　（比較例２）
　実施例１と同様に、ホソカワミクロン社製メカノフュージョンを用いて、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、平均粒子径が３μｍのＷＳｉ２粒子とを９９：１のモル比となるように混合し、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子の表面にＷＳｉ２粒子を付着させた。但し、比較例２では、ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、ＷＳｉ２粒子との焼成を行わなかった。それ以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 2)
Similarly to Example 1, using a mechanofusion manufactured by Hosokawa Micron Co., Ltd., LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles having an average particle diameter of 3 μm were in a molar ratio of 99: 1. WSi 2 particles were adhered to the surface of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles. However, in Comparative Example 2, the firing of the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and the WSi 2 particles was not performed. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a three-electrode test cell 20 was produced.
　（実施例２）
　平均粒子径が２μｍのＺｒＳｉ２を遷移金属ケイ化物として用いたこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。実施例２においても、ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＺｒＳｉ２の構造が焼成後の遷移金属ケイ化物においても維持されていることを確認できた。 (Example 2)
A positive electrode was produced in the same manner as in Example 1 except that ZrSi 2 having an average particle diameter of 2 μm was used as a transition metal silicide, and a three-electrode test cell 20 was produced. Also in Example 2, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of ZrSi 2 before firing was maintained in the transition metal silicide after firing.
　（比較例３）
　ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、ＺｒＳｉ２粒子との焼成を行わなかったこと以外は、実施例２と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 3)
A positive electrode was prepared in the same manner as in Example 2 except that firing of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and ZrSi 2 particles was not performed, and a three-electrode test cell 20 Was made.
　（実施例３）
　平均粒子径が１μｍのＴｉＳｉ２を遷移金属ケイ化物として用いたこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。実施例３においても、ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＴｉＳｉ２の構造が焼成後の遷移金属ケイ化物においても維持されていることを確認できた。 (Example 3)
A positive electrode was produced in the same manner as in Example 1 except that TiSi 2 having an average particle diameter of 1 μm was used as a transition metal silicide, and a three-electrode test cell 20 was produced. Also in Example 3, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of TiSi 2 before firing was maintained even in the transition metal silicide after firing.
　（比較例４）
　ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、ＴｉＳｉ２粒子との焼成を行わなかったこと以外は、実施例３と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 4)
A positive electrode was produced in the same manner as in Example 3 except that firing of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and TiSi 2 particles was not performed, and a three-electrode test cell 20 Was made.
　以上のように作製した実施例１～３及び比較例１～４の三電極式試験用セルに対して以下の評価を行った。評価結果を表１に示す。 The following evaluation was performed on the three-electrode test cells of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured as described above. The evaluation results are shown in Table 1.
　［初期平均放電作動電位］
　三電極式試験用セルに対して、２５℃において、０．２５ｍＡ／ｃｍ２の電流密度で４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）まで定電流充電を行い、その後、電流密度が０．０２５ｍＡ／ｃｍ２に達するまで４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）定電位を保つ、定電流－定電圧充電を行った。その後、１０．０ｍＡ／ｃｍ２で放電させ、その際の平均放電作動電位を初期平均放電作動電位として測定した。 [Initial average discharge operating potential]
A three-electrode test cell was charged at a constant current of up to 4.5 V (vs. Li / Li + ) at a current density of 0.25 mA / cm 2 at 25 ° C., and then the current density was 0.025 mA. Constant current-constant voltage charging was performed, maintaining a constant potential of 4.5 V (vs. Li / Li + ) until reaching / cm 2 . Then, it discharged at 10.0 mA / cm < 2 > and measured the average discharge action potential in that case as an initial stage average discharge action potential.
　［保存後平均放電作動電位］
　三電極式試験用セルに対して、２５℃において、２．０ｍＡ／ｃｍ２の電流密度で４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）まで定電流充電を行い、その後、電流密度が０．０２５ｍＡ／ｃｍ２に達するまで４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）定電位を保つ、定電流－定電圧充電を行った。次に、三電極式試験用セルを６０℃で１０日間保存した後、２５℃において１０．０ｍＡ／ｃｍ２で放電させ、その際の平均放電作動電位を保存後平均放電作動位として測定した。 [Average discharge working potential after storage]
The three-electrode test cell was charged at a constant current of up to 4.5 V (vs. Li / Li + ) at a current density of 2.0 mA / cm 2 at 25 ° C., and then the current density was 0.025 mA. Constant current-constant voltage charging was performed, maintaining a constant potential of 4.5 V (vs. Li / Li + ) until reaching / cm 2 . Next, after the three-electrode test cell was stored at 60 ° C. for 10 days, it was discharged at 10.0 mA / cm 2 at 25 ° C., and the average discharge operating potential at that time was measured as the average discharge operating position after storage.
　［サイクル後平均放電作動電位］
　三電極式試験用セルに対して、２５℃において、２．０ｍＡ／ｃｍ２の電流密度で４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）まで定電流充電を行い、その後、電流密度が０．０２５ｍＡ／ｃｍ２に達するまで４．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）定電位を保つ、定電流－定電圧充電を行った。次に、２．０ｍＡ／ｃｍ２の電流密度で２．５Ｖ（ｖｓ．Ｌｉ／Ｌｉ＋）まで定電流放電を行った。これら定電流－定電圧充電と定電流放電とを１５回繰り返した。次に、１０．０ｍＡ／ｃｍ２で放電させ、その際の平均放電作動電位をサイクル後平均放電作動電位として測定した。 [Average discharge operating potential after cycle]
The three-electrode test cell was charged at a constant current of up to 4.5 V (vs. Li / Li + ) at a current density of 2.0 mA / cm 2 at 25 ° C., and then the current density was 0.025 mA. Constant current-constant voltage charging was performed, maintaining a constant potential of 4.5 V (vs. Li / Li + ) until reaching / cm 2 . Next, constant current discharge was performed up to 2.5 V (vs. Li / Li + ) at a current density of 2.0 mA / cm 2 . These constant current-constant voltage charging and constant current discharging were repeated 15 times. Next, discharge was performed at 10.0 mA / cm 2 , and the average discharge operation potential at that time was measured as the average discharge operation potential after the cycle.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示す結果から分かるように、リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物を焼結した実施例１～３では、遷移金属ケイ化物を添加しなかった比較例１よりも初期平均放電作動電位、保存後平均放電作動電位及びサイクル後平均放電作動電位のいずれもが高かった。また、実施例１～３では、遷移金属ケイ化物を添加したが焼結を行わなかった比較例２～４よりも、初期平均放電作動電位、保存後平均放電作動電位及びサイクル後平均放電作動電位のいずれもが高かった。 As can be seen from the results shown in Table 1, in Examples 1 to 3 in which the transition metal silicide was sintered on the surface of the lithium-containing transition metal composite oxide particles, compared to Comparative Example 1 in which no transition metal silicide was added. The initial average discharge working potential, the average discharge working potential after storage and the average discharge working potential after cycle were all high. Further, in Examples 1 to 3, the initial average discharge operating potential, the average discharge operating potential after storage, and the average discharge operating potential after cycle were higher than those of Comparative Examples 2 to 4 in which transition metal silicide was added but sintering was not performed. None of them were expensive.
　（実施例４）
　ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、ＷＳｉ２粒子との焼成温度を５００℃としたこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。実施例４においても、ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＷＳｉ２の構造が焼成後の遷移金属ケイ化物においても維持されていることを認できた。 (Example 4)
A positive electrode was produced in the same manner as in Example 1 except that the firing temperature of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles was 500 ° C. A cell 20 was produced. Also in Example 4, when the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of WSi 2 before firing was maintained even in the transition metal silicide after firing.
　（比較例５）
　ＬｉＮｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２粒子と、ＷＳｉ２粒子との焼成温度を７００℃としたこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。なお、比較例５においても、ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成後においては、ＷＳｉ２の結晶に由来するピークは認められず、ＷＳｉ２が酸化分解していることが示唆された。 (Comparative Example 5)
A positive electrode was produced in the same manner as in Example 1 except that the firing temperature of LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles and WSi 2 particles was 700 ° C. A cell 20 was produced. Also in Comparative Example 5, when the crystal structure of the positive electrode active material was confirmed using XRD, no peak derived from WSi 2 crystals was observed after firing, and WSi 2 was oxidized and decomposed. Was suggested.
　実施例４及び比較例５において作製した三電極式試験用セルに関しても同様に、初期平均放電作動電位及び保存後平均放電作動電位を測定した。結果を表２に示す。 For the three-electrode test cells prepared in Example 4 and Comparative Example 5, the initial average discharge working potential and the average discharge working potential after storage were measured in the same manner. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示す結果から分かるように、焼結温度が高すぎたために遷移金属ケイ化物が分解してしまった比較例５では、遷移金属ケイ化物がリチウム含有遷移金属複合酸化物粒子の表面に焼結した実施例１，４よりも初期平均放電作動電位及び保存後平均放電作動電位のいずれもが低かった。 As can be seen from the results shown in Table 2, in Comparative Example 5 in which the transition metal silicide was decomposed because the sintering temperature was too high, the transition metal silicide was sintered on the surface of the lithium-containing transition metal composite oxide particles. Both the initial average discharge operating potential and the average discharge operating potential after storage were lower than those of Examples 1 and 4 that were concluded.
　（実施例５）
　Ｌｉ２ＣＯ３と、共沈法によって得たＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５（ＯＨ）２とを所定の割合で混合し、これらを空気中において焼成することにより、層状構造を有するＬｉＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５Ｏ２粒子を作製した。この粒子の一次粒子の平均粒子径は、約１μｍであり、二次粒子の平均粒子径は、約１０μｍであった。 (Example 5)
Li 2 CO 3 and Ni 0.45 Co 0.30 Mn 0.25 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air to form a layered structure. LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 μm, and the average particle size of secondary particles was about 10 μm.
　次に、ホソカワミクロン社製メカノフュージョンを用いて、ＬｉＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５Ｏ２粒子と、平均粒子径が２μｍのＺｒＳｉ２粒子とを９９：１のモル比となるように混合し、ＬｉＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５Ｏ２粒子の表面にＺｒＳｉ２粒子を付着させた。その後、空気中において６００℃で１時間焼成し、ＬｉＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５Ｏ２粒子の表面にＺｒＳｉ２粒子が焼成されてなる正極活物質を作製した。ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＺｒＳｉ２粒子の構造が焼成後の遷移金属ケイ化物においても維持されていることを確認できた。それ以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。 Next, using a mechanofusion manufactured by Hosokawa Micron Co., Ltd., the LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles and the ZrSi 2 particles having an average particle diameter of 2 μm are set to a molar ratio of 99: 1. After mixing, ZrSi 2 particles were adhered to the surface of LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles. Then baked 1 hour at 600 ° C. in air, the surface of LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles ZrSi 2 particles to prepare a positive electrode active material made by firing. When the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of the ZrSi 2 particles before firing was maintained even in the transition metal silicide after firing. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a three-electrode test cell 20 was produced.
　（実施例６）
　Ｌｉ２ＣＯ３と、共沈法によって得たＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０（ＯＨ）２とを所定の割合で混合し、これらを空気中において焼成することにより、層状構造を有するＬｉＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０Ｏ２粒子を作製した。この粒子の一次粒子の平均粒子径は、約１μｍであり、二次粒子の平均粒子径は、約１０μｍであった。 (Example 6)
Li 2 CO 3 and Ni 0.55 Co 0.25 Mn 0.20 (OH) 2 obtained by the coprecipitation method are mixed at a predetermined ratio, and these are fired in the air, thereby forming a layered structure. LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles were prepared. The average particle size of primary particles of this particle was about 1 μm, and the average particle size of secondary particles was about 10 μm.
　次に、ホソカワミクロン社製メカノフュージョンを用いて、ＬｉＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０Ｏ２粒子と、平均粒子径が２μｍのＺｒＳｉ２粒子とを９９：１のモル比となるように混合し、ＬｉＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０Ｏ２粒子の表面にＺｒＳｉ２粒子を付着させた。その後、空気中において６００℃で１時間焼成し、ＬｉＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０Ｏ２粒子の表面にＺｒＳｉ２粒子が焼成されてなる正極活物質を作製した。ＸＲＤを用いて正極活物質の結晶構造を確認したところ、焼成前のＺｒＳｉ２粒子の構造が焼成後の遷移金属ケイ化物においても維持されていることを確認できた。それ以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。 Next, using a mechano-fusion manufactured by Hosokawa Micron Co., Ltd., the LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles and the ZrSi 2 particles having an average particle diameter of 2 μm are set to a molar ratio of 99: 1. After mixing, ZrSi 2 particles were adhered to the surface of LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles. Then baked 1 hour at 600 ° C. in air, the surface of LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles ZrSi 2 particles to prepare a positive electrode active material made by firing. When the crystal structure of the positive electrode active material was confirmed using XRD, it was confirmed that the structure of the ZrSi 2 particles before firing was maintained even in the transition metal silicide after firing. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a three-electrode test cell 20 was produced.
（比較例６）
ＬｉＮｉ０．５０Ｃｏ０．２０Ｍｎ０．３０Ｏ２粒子の表面にＺｒＳｉ２粒子を付着させなかったこと、及び焼成しなかったこと以外は、実施例１と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 6)
A positive electrode was prepared in the same manner as in Example 1 except that the ZrSi 2 particles were not adhered to the surface of the LiNi 0.50 Co 0.20 Mn 0.30 O 2 particles and were not fired. An electrode type test cell 20 was produced.
　（比較例７）
　ＬｉＮｉ０．４５Ｃｏ０．３０Ｍｎ０．２５Ｏ２粒子の表面にＺｒＳｉ２粒子を付着させなかったこと、及び焼成しなかったこと以外は、実施例５と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 7)
A positive electrode was prepared in the same manner as in Example 5 except that the ZrSi 2 particles were not adhered to the surface of the LiNi 0.45 Co 0.30 Mn 0.25 O 2 particles and were not fired. An electrode type test cell 20 was produced.
　（比較例８）
　ＬｉＮｉ０．５５Ｃｏ０．２５Ｍｎ０．２０Ｏ２粒子の表面にＺｒＳｉ２粒子を付着させなかったこと、及び焼成しなかったこと以外は、実施例６と同様にして正極を作製し、三電極式試験用セル２０を作製した。 (Comparative Example 8)
A positive electrode was prepared in the same manner as in Example 6 except that the ZrSi 2 particles were not attached to the surface of the LiNi 0.55 Co 0.25 Mn 0.20 O 2 particles and were not fired. An electrode type test cell 20 was produced.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３に示す結果から分かるように、層状構造を有する一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２で表されるリチウム含有遷移金属複合酸化物粒子に対して、遷移金属ケイ化物を焼結した実施例２、５、６では、遷移金属窒化物を添加しなかった比較例６～８よりも、サイクル後平均放電作動電位が高かった。 As it can be seen from the results shown in Table 3, with respect to the general formula Li a (Ni b Co c Mn d) lithium-containing transition metal composite oxide particles represented by O 2 having a layered structure, a transition metal silicide baked In Examples 2, 5, and 6, the average discharge operating potential after cycle was higher than those of Comparative Examples 6 to 8 in which no transition metal nitride was added.
１…非水電解質二次電池
１０…電極体
１１…負極
１２…正極
１３…セパレータ
１７…電池容器
２０…三電極式試験用セル
２１…作用極
２２…対極
２３…参照極
２４…非水電解質 DESCRIPTION OF SYMBOLS 1 ... Nonaqueous electrolyte secondary battery 10 ... Electrode body 11 ... Negative electrode 12 ... Positive electrode 13 ... Separator 17 ... Battery container 20 ... Three-electrode type test cell 21 ... Working electrode 22 ... Counter electrode 23 ... Reference electrode 24 ... Nonaqueous electrolyte

Claims (15)

  1. 　リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物が焼結されてなる、非水電解質二次電池用活物質。 An active material for a non-aqueous electrolyte secondary battery, in which a transition metal silicide is sintered on the surface of lithium-containing transition metal composite oxide particles.
  2. 　前記リチウム含有遷移金属複合酸化物粒子は、一般式ＬｉＭｅＯ２（但し、Ｍｅは、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表される層状構造を有するリチウム含有遷移金属複合酸化物からなり、
    　前記遷移金属ケイ化物は、ケイ化タングステン、ケイ化ジルコニウム、ケイ化チタン、ケイ化ニオブ、ケイ化タンタル、ケイ化クロム及びケイ化モリブデンからなる群から選ばれた少なくともひとつからなる、請求項１に記載の非水電解質二次電池用活物質。     The lithium-containing transition metal composite oxide particles include a lithium-containing transition metal composite oxide having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co, and Mn). Made of things,
    The transition metal silicide comprises at least one selected from the group consisting of tungsten silicide, zirconium silicide, titanium silicide, niobium silicide, tantalum silicide, chromium silicide, and molybdenum silicide. The active material for nonaqueous electrolyte secondary batteries as described.
  3. 　前記遷移金属ケイ化物は、ケイ化タングステン、ケイ化ジルコニウム及びケイ化チタンからなる群から選ばれた少なくともひとつからなる、請求項２に記載の非水電解質二次電池用活物質。 The non-aqueous electrolyte secondary battery active material according to claim 2, wherein the transition metal silicide is made of at least one selected from the group consisting of tungsten silicide, zirconium silicide, and titanium silicide.
  4. 　前記リチウム含有遷移金属複合酸化物粒子が、一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２（ａ、ｂ、ｃ、ｄは、０．９≦ａ／（ｂ＋ｃ＋ｄ）≦１．２、１．４≦ｂ／ｄ、及び０≦ｃ≦０．４５を満足する。）で表されることを特徴とする請求項１～３に記載の非水電解質二次電池。 The lithium-containing transition metal composite oxide particles, the general formula Li a (Ni b Co c Mn d) O 2 (a, b, c, d is, 0.9 ≦ a / (b + c + d) ≦ 1.2,1 4. The nonaqueous electrolyte secondary battery according to claim 1, wherein: 4 ≦ b / d and 0 ≦ c ≦ 0.45 are satisfied.
  5. 　前記リチウム含有遷移金属複合酸化物粒子が、一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２（ａ、ｂ、ｃ、ｄは、０．９≦ａ／（ｂ＋ｃ＋ｄ）≦１．２、１．４≦ｂ／ｄ、０≦ｃ≦０．４５、４５≦ｂ≦５５、２０≦ｃ≦３０、及び２０≦ｄ≦３０を満足する。）で表されることを特徴とする請求項４に記載の非水電解質二次電池用活物質。 The lithium-containing transition metal composite oxide particles, the general formula Li a (Ni b Co c Mn d) O 2 (a, b, c, d is, 0.9 ≦ a / (b + c + d) ≦ 1.2,1 4 ≦ b / d, 0 ≦ c ≦ 0.45, 45 ≦ b ≦ 55, 20 ≦ c ≦ 30, and 20 ≦ d ≦ 30). The active material for nonaqueous electrolyte secondary batteries as described in 2.
  6. 　請求項１～５のいずれか一項に記載の非水電解質二次電池用活物質を含む活物質層を有する非水電解質二次電池用電極を備える、非水電解質二次電池。 A nonaqueous electrolyte secondary battery comprising an electrode for a nonaqueous electrolyte secondary battery having an active material layer containing the active material for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 5.
  7. 　リチウム含有遷移金属複合酸化物粒子の表面に遷移金属ケイ化物を焼結させることにより非水電解質二次電池用活物質を得る、非水電解質二次電池用活物質の製造方法。 The manufacturing method of the active material for nonaqueous electrolyte secondary batteries which obtains the active material for nonaqueous electrolyte secondary batteries by sintering a transition metal silicide on the surface of lithium containing transition metal complex oxide particle.
  8. 　前記リチウム遷移金属複合酸化物粒子と前記遷移金属ケイ化物との焼結を、前記焼結前の遷移金属ケイ化物の少なくとも一部の構造が焼結後にも維持される温度で行う、請求項７に記載の非水電解質二次電池用活物質の製造方法。 The sintering of the lithium transition metal composite oxide particles and the transition metal silicide is performed at a temperature at which at least a part of the structure of the transition metal silicide before sintering is maintained even after sintering. The manufacturing method of the active material for nonaqueous electrolyte secondary batteries as described in any one of.
  9. 　前記リチウム遷移金属複合酸化物粒子と前記遷移金属ケイ化物との焼結を、前記遷移金属ケイ化物の酸化分解開始温度以下の温度で行う、請求項７または８に記載の非水電解質二次電池用活物質の製造方法。 The nonaqueous electrolyte secondary battery according to claim 7 or 8, wherein sintering of the lithium transition metal composite oxide particles and the transition metal silicide is performed at a temperature not higher than an oxidation decomposition start temperature of the transition metal silicide. For producing an active material.
  10. 　前記リチウム含有遷移金属複合酸化物粒子として、一般式ＬｉＭｅＯ２（但し、Ｍｅは、Ｎｉ、Ｃｏ及びＭｎからなる群から選ばれた少なくともひとつ）で表される層状構造を有するリチウム含有遷移金属複合酸化物からなる粒子を用い、
    　前記遷移金属ケイ化物として、ケイ化タングステン、ケイ化ジルコニウム、ケイ化チタン、ケイ化ニオブ、ケイ化タンタル、ケイ化クロム及びケイ化モリブデンからなる群から選ばれた少なくともひとつを用いる、請求項７～９のいずれか一項に記載の非水電解質二次電池用活物質の製造方法。     As the lithium-containing transition metal composite oxide particles, a lithium-containing transition metal composite oxide having a layered structure represented by the general formula LiMeO 2 (where Me is at least one selected from the group consisting of Ni, Co and Mn). Using particles consisting of things,
    The transition metal silicide is at least one selected from the group consisting of tungsten silicide, zirconium silicide, titanium silicide, niobium silicide, tantalum silicide, chromium silicide and molybdenum silicide. The manufacturing method of the active material for nonaqueous electrolyte secondary batteries as described in any one of 9.
  11. 　前記遷移金属ケイ化物として、ケイ化タングステン、ケイ化ジルコニウム及びケイ化チタンからなる群から選ばれた少なくともひとつを用いる、請求項１０に記載の非水電解質二次電池用活物質の製造方法。 The method for producing an active material for a non-aqueous electrolyte secondary battery according to claim 10, wherein at least one selected from the group consisting of tungsten silicide, zirconium silicide, and titanium silicide is used as the transition metal silicide.
  12. 　前記リチウム含有遷移金属複合酸化物粒子が、一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２（ａ、ｂ、ｃ、ｄは、０．９≦ａ／（ｂ＋ｃ＋ｄ）≦１．２、１．４≦ｂ／ｄ及び０≦ｃ≦０．４５を満足する。）で表されることを特徴とする請求項７～１１に記載の非水電解質二次電池の製造方法。 The lithium-containing transition metal composite oxide particles, the general formula Li a (Ni b Co c Mn d) O 2 (a, b, c, d is, 0.9 ≦ a / (b + c + d) ≦ 1.2,1 The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 7, wherein: 4 ≦ b / d and 0 ≦ c ≦ 0.45 are satisfied.
  13. 　前記リチウム含有遷移金属複合酸化物粒子が、一般式Ｌｉａ（ＮｉｂＣｏｃＭｎｄ）Ｏ２（ａ、ｂ、ｃ、ｄは、０．９≦ａ／（ｂ＋ｃ＋ｄ）≦１．２、１．４≦ｂ／ｄ、０≦ｃ≦０．４５、５≦ｂ≦５５、２０≦ｃ≦３０、及び２０≦ｄ≦３０を満足する。）で表されることを特徴とする請求項１２に記載の非水電解質二次電池用活物質の製造方法。 The lithium-containing transition metal composite oxide particles, the general formula Li a (Ni b Co c Mn d) O 2 (a, b, c, d is, 0.9 ≦ a / (b + c + d) ≦ 1.2,1 .. 4 ≦ b / d, 0 ≦ c ≦ 0.45, 5 ≦ b ≦ 55, 20 ≦ c ≦ 30, and 20 ≦ d ≦ 30. The manufacturing method of the active material for nonaqueous electrolyte secondary batteries as described in any one of.
  14. 　前記遷移金属ケイ化物としてケイ化タングステンを用い、
    　前記リチウム遷移金属複合酸化物粒子と前記遷移金属ケイ化物とを、５００℃以上７００℃未満で焼結する、請求項１１に記載の非水電解質二次電池用活物質の製造方法。     Using tungsten silicide as the transition metal silicide,
    The manufacturing method of the active material for nonaqueous electrolyte secondary batteries of Claim 11 which sinters the said lithium transition metal complex oxide particle and the said transition metal silicide at 500 degreeC or more and less than 700 degreeC.
  15. 　前記遷移金属ケイ化物としてケイ化ジルコニウムを用い、
    　前記リチウム遷移金属複合酸化物粒子と前記遷移金属ケイ化物とを、５００℃以上８００℃未満で焼結する、請求項１１に記載の非水電解質二次電池用活物質の製造方法。     Using zirconium silicide as the transition metal silicide,
    The method for producing an active material for a nonaqueous electrolyte secondary battery according to claim 11, wherein the lithium transition metal composite oxide particles and the transition metal silicide are sintered at 500 ° C. or higher and lower than 800 ° C. 12.
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