WO2011002074A1 - Method for producing lithium transition metal oxide - Google Patents

Method for producing lithium transition metal oxide Download PDF

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WO2011002074A1
WO2011002074A1 PCT/JP2010/061308 JP2010061308W WO2011002074A1 WO 2011002074 A1 WO2011002074 A1 WO 2011002074A1 JP 2010061308 W JP2010061308 W JP 2010061308W WO 2011002074 A1 WO2011002074 A1 WO 2011002074A1
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transition metal
metal oxide
lithium transition
temperature
oxygen
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PCT/JP2010/061308
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French (fr)
Japanese (ja)
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蔭井　慎也
啓祐 宮之原
祥巳 畑
越智　康弘
徹也 光本
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三井金属鉱業株式会社
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Priority to JP2010545129A priority Critical patent/JP4673451B2/en
Publication of WO2011002074A1 publication Critical patent/WO2011002074A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Cobaltates
    • C01G51/42—Cobaltates containing alkali metals, e.g. LiCoO2
    • 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
    • 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
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/30—Three-dimensional structures
    • C01P2002/32—Three-dimensional structures spinel-type (AB2O4)
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/88—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by thermal analysis data, e.g. TGA, DTA, DSC
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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 method for producing a lithium transition metal oxide, particularly a lithium transition metal oxide that can be used as a positive electrode active material of a lithium secondary battery.
  • Lithium batteries especially lithium secondary batteries, have features such as high energy density and long life, and power supplies for home appliances such as video cameras, portable electronic devices such as notebook computers and mobile phones. Is widely used. Recently, application to large batteries mounted on electric vehicles (EV), hybrid electric vehicles (HEV), and the like is expected.
  • EV electric vehicles
  • HEV hybrid electric vehicles
  • a lithium secondary battery is a secondary battery with a structure in which lithium is extracted as ions from the positive electrode during charging, moves to the negative electrode and is stored, and reversely, lithium ions return from the negative electrode to the positive electrode during discharging. It is known to be due to the potential of the material.
  • lithium transition metal oxides such as LiCoO 2 , LiNiO 2 , and LiMnO 2 having a layer structure, LiMn 2 O 4 , and LiNi 0.5 Mn.
  • a lithium transition metal oxide having a manganese-based spinel structure (Fd-3m) such as 1.5 O 4 (also referred to as “spinel-type lithium transition metal oxide” or “LMO” in the present invention) is known.
  • Manganese spinel-type lithium transition metal oxide is a positive electrode for large batteries such as electric vehicles (EV) and hybrid electric vehicles (HEV) because of its low raw material price, non-toxicity, and high safety. It is attracting attention as an active material. Moreover, excellent output characteristics are particularly required for batteries for EVs and HEVs. In this regard, insertion and desorption of Li ions are three-dimensionally compared with lithium transition metal oxides such as LiCoO 2 having a layer structure. A possible spinel type lithium transition metal oxide (LMO) has excellent output characteristics.
  • LMO lithium transition metal oxide
  • Patent Document 1 discloses a method of suppressing oxygen deficiency by adding lithium hydroxide after high-temperature baking and re-baking at a lower temperature.
  • the starting material is baked in an oxidizing atmosphere at a temperature in the range of 900 to 1000 ° C. for 5 to 50 hours, and then in an oxidizing atmosphere at 600 to 900 ° C.
  • a method for suppressing oxygen deficiency by re-baking at a temperature in the range of 1 to 50 hours for a time in the range of 1 to 50 hours is disclosed.
  • Patent Document 3 proposes a method for producing a lithium composite oxide in which a mixture of raw materials is fired at a high temperature to produce a fired product, and the fired product is refired while flowing.
  • the present invention provides a method for producing a lithium transition metal oxide comprising a step of mixing raw materials, a step of firing, and a step of heat treatment, in an atmosphere having an oxygen partial pressure of 0.015 MPa to 0.15 MPa. And heat treatment at a primary oxygen release temperature of ⁇ 50 ° C. in an atmosphere having an oxygen partial pressure of 0.03 MPa or more after baking at 850 ° C. in a method for producing a lithium transition metal oxide This is a proposal.
  • the crystallite size can be increased and the distortion of the crystal structure can be suppressed, the distortion is reduced and the skeleton is strengthened.
  • a positive electrode active material of a lithium secondary battery When used, it is possible to provide a new lithium transition metal oxide capable of achieving both output characteristics (rate characteristics) and high-temperature cycle life characteristics.
  • the manufacturing method of the present invention it is possible to suppress the distortion of the crystal structure while increasing the crystallite size as described above, the strain is 0.05 or less, and the crystallite size is 250 nm to A 1000 nm spinel lithium transition metal oxide can be obtained.
  • Such spinel-type lithium transition metal oxides are not recognized as publicly known in Japan at the time of this application.
  • FIG. It is the figure which showed the structure of the cell for electrochemical produced in order to evaluate the battery characteristic of the sample obtained by the Example and the comparative example.
  • This embodiment relates to a method for producing a spinel (Fd-3m) lithium transition metal oxide.
  • the manufacturing method of this embodiment is characterized in that after the raw materials are mixed, calcined at 850 ° C. or higher in a predetermined oxygen partial pressure atmosphere, and then heat-treated in an atmosphere having a higher oxygen partial pressure than the atmosphere. .
  • the details will be described in order.
  • At least a lithium material and a manganese material may be appropriately selected.
  • the lithium raw material is not particularly limited.
  • lithium hydroxide LiOH
  • lithium carbonate Li 2 CO 3
  • lithium nitrate LiNO 3
  • LiOH.H 2 O LiOH.H 2 O
  • lithium oxide Li 2 O
  • lithium hydroxide salts carbonates and nitrates are preferred.
  • manganese raw material any of manganese dioxide, trimanganese tetroxide, dimanganese trioxide, manganese carbonate, or a mixture of two or more selected from these can be used.
  • manganese dioxide chemically synthesized manganese dioxide (CMD), electrolytic manganese dioxide (EMD) obtained by electrolysis, manganese carbonate, or natural manganese dioxide can be used.
  • a magnesium raw material in addition to the lithium raw material and the manganese raw material, for example, a magnesium raw material, an aluminum raw material, and other substances known as starting materials for lithium transition metal oxides can be blended.
  • the magnesium raw material is not particularly limited.
  • the aluminum raw material is not particularly limited.
  • aluminum hydroxide (Al (OH) 3 ), aluminum fluoride (AlF 3 ), or the like can be used, and aluminum hydroxide is particularly preferable.
  • Examples of other substances known as starting materials for lithium transition metal oxides include elements such as Ti, Ni, Co and Fe, and the starting materials are not particularly limited.
  • an oxide or hydroxide may be blended.
  • the method of mixing raw materials is not particularly limited as long as it can be uniformly mixed.
  • the respective raw materials may be added simultaneously or in an appropriate order using a known mixer such as a mixer, and mixed by stirring in a wet or dry manner.
  • a known mixer such as a mixer
  • wet mixing When adding an element that is difficult to replace, such as aluminum, it is preferable to employ wet mixing.
  • Examples of the dry mixing include a mixing method using a precision mixer that rotates mixed powder at a high speed.
  • examples of the wet mixing include a mixing method in which a liquid medium such as water or a dispersant is added and wet mixed to form a slurry, and the resulting slurry is pulverized with a wet pulverizer. It is particularly preferable to grind to submicron order. After pulverizing to the submicron order, granulation and baking can increase the uniformity of each particle before the baking reaction, and the reactivity can be increased.
  • the raw materials mixed as described above may be granulated to a predetermined size, if necessary, and then fired. However, granulation is not necessarily performed.
  • the granulation method may be wet or dry as long as the various raw materials pulverized in the previous step are dispersed in the granulated particles without being separated, and the extrusion granulation method, rolling granulation method, fluidized granulation method, A mixed granulation method, a spray drying granulation method, a pressure molding granulation method, or a flake granulation method using a roll or the like may be used. However, when wet granulation is performed, it is necessary to sufficiently dry before firing.
  • a drying method it may be dried by a known drying method such as a spray heat drying method, a hot air drying method, a vacuum drying method, a freeze drying method, etc.
  • the spray heat drying method is preferable.
  • the spray heat drying method is preferably performed using a heat spray dryer (spray dryer).
  • a thermal spray dryer spray dryer
  • the particle size distribution can be made sharper, and the secondary particles can be formed so as to contain agglomerated particles (secondary particles) formed by agglomeration. Forms can be prepared.
  • (Baking) Firing is preferably performed in an atmosphere having an oxygen partial pressure of 0.015 MPa to 0.15 MPa, for example, in an air atmosphere. If the oxygen partial pressure is higher than 0.15 MPa, crystal growth cannot be promoted and the crystallite size cannot be increased. In addition, as will be described later, in order to promote crystal growth by firing, it is preferable that the oxygen partial pressure in the atmosphere is low. However, if the oxygen partial pressure during firing is too low, oxygen deficiency will increase and heat treatment will also occur. Since the strain cannot be recovered, baking is preferably performed at an oxygen partial pressure of 0.015 MPa or more. From this point of view, the oxygen partial pressure during firing is more preferably 0.015 MPa to 0.13 MPa, particularly 0.015 MPa to 0.12 MPa, especially 0.015 MPa or more, or less than 0.08 MPa. preferable.
  • the firing temperature can be increased at 850 ° C. or more, particularly 910 to 1,050 ° C., particularly 910 to 980 ° C., because high temperature firing can promote crystal growth and increase the crystallite size. preferable.
  • the firing temperature means the product temperature of the fired product measured by bringing a thermocouple into contact with the fired product in the firing furnace.
  • the firing time that is, the time for maintaining the firing temperature may be 0.5 to 30 hours, although it depends on the firing temperature.
  • the type of firing furnace is not particularly limited. For example, it can be fired using a rotary kiln, a stationary furnace, or other firing furnace.
  • Heat treatment Next, it is important to perform heat treatment at a temperature of primary oxygen release temperature ⁇ 50 ° C. in an atmosphere having an oxygen partial pressure higher than that of air. By performing the heat treatment in this manner, crystal distortion can be reduced.
  • the atmosphere for the heat treatment is preferably such that the oxygen partial pressure is 0.03 MPa or higher and the oxygen partial pressure is higher than that during firing, particularly 0.05 MPa or higher, particularly 0.08 MPa or higher.
  • the pressure of the atmosphere during the heat treatment is preferably controlled to a pressure higher than atmospheric pressure, for example, 0.1 MPa to 1.5 MPa.
  • a pressure higher than atmospheric pressure for example, 0.1 MPa to 1.5 MPa.
  • the pressure of the atmosphere during the heat treatment is preferably controlled to 0.1 MPa to 1.5 MPa, more preferably 0.1 MPa to 1.3 MPa, and particularly preferably 0.1 MPa to 1.0 MPa.
  • the heat treatment preferably maintains the primary oxygen release temperature ⁇ 50 ° C., particularly ⁇ 35 ° C., especially ⁇ 30 ° C., and especially ⁇ 20 ° C. Among these, it is more preferable to maintain a temperature range higher than the primary oxygen release temperature in each of the above temperature ranges from the viewpoint that energy exceeding the primary oxygen release temperature can be given.
  • the temperature of this heat treatment means the product temperature of the processed material measured by bringing a thermocouple into contact with the processed material in the furnace.
  • the rate of temperature rise is preferably 0.5 ° C./min to 4 ° C./min, particularly 0.5 ° C./min to 3 ° C./min, and particularly 0.5 ° C./min to 2 ° C./min More preferably, it is set to min.
  • the primary oxygen release temperature can be obtained as the starting temperature at which the spinel-type lithium transition metal oxide after heating is heated and the weight is reduced in the range of 600 ° C. to 900 ° C. (see FIG. 1).
  • the time for maintaining the primary oxygen release temperature ⁇ 50 ° C. in the heat treatment needs to be at least 1 minute. In order to fully incorporate oxygen into the crystal structure, at least one minute is considered necessary. From this viewpoint, the time for maintaining the primary oxygen release temperature ⁇ 50 ° C. is preferably 5 minutes or more, particularly preferably 10 minutes or more.
  • the temperature lowering rate after the heat treatment is preferably slow cooling at a cooling rate of 10 ° C./min or less to at least 500 ° C., particularly 0.1 ° C./min to 8 ° C./min, especially 0.5 ° C./min to More preferably, it is controlled to 5 ° C./min. Since the oxygen taken in near the primary oxygen release temperature is considered to be stabilized, the oxygen is slowly cooled at a temperature lowering rate of 10 ° C./min or less until the temperature close to the primary oxygen release temperature, that is, at least 500 ° C. Can be considered preferable.
  • Lithium transition metal oxide According to the manufacturing method of the present embodiment described above, a spinel type lithium transition metal oxide (also referred to as “present LMO”) having the characteristics described below can be obtained.
  • the present LMO is a spinel (Fd-3m) lithium transition metal oxide containing, in addition to Li and Mn, any one of Ti, Ni, Mg, Co and Fe, or a combination of two or more thereof.
  • the content of substitutional elements other than Li and Mn is preferably 0 to 1.8 wt%, particularly 0.2 to 1.0 wt%, particularly 0.4 to 0.6 wt% from the viewpoint of strain removal. Is even more preferable.
  • the strain of the obtained spinel-type lithium transition metal oxide can be adjusted to 0.05 or less, preferably 0.02 or less, and more preferably 0.009 or less.
  • the skeleton of the spinel lithium transition metal oxide becomes stronger, and when used as a positive electrode active material for a lithium secondary battery, the output characteristics (rate characteristics) and high-temperature cycle life characteristics It can be compatible.
  • the spinel-type lithium transition metal oxide obtained has a crystallite size of 250 nm to 1000 nm, particularly 300 to 1000 nm, preferably 350 nm to 900 nm, and particularly preferably 420 nm to 750 nm. Can be adjusted.
  • the crystallite size of the present LMO By setting the crystallite size of the present LMO to 250 nm to 1000 nm, the high temperature cycle life characteristics can be improved, and both the output characteristics and the high temperature cycle life characteristics can be achieved.
  • crystallite means the largest group that can be regarded as a single crystal, and can be obtained by XRD measurement and Rietveld analysis.
  • the present LMO can be effectively used as a positive electrode active material of a lithium battery after being crushed and classified as necessary.
  • the positive electrode mixture can be manufactured by mixing the present LMO, a conductive material made of carbon black or the like, and a binder made of Teflon (registered trademark) binder or the like.
  • a positive electrode mixture is used for the positive electrode, for example, a material that can occlude / desorb lithium such as lithium or carbon is used for the negative electrode, and a lithium salt such as lithium hexafluorophosphate (LiPF6) is used for the non-aqueous electrolyte.
  • a lithium secondary battery can be formed by using a material in which is dissolved in a mixed solvent such as ethylene carbonate-dimethyl carbonate.
  • the present invention is not limited to the battery having such a configuration.
  • a lithium battery equipped with the LMO as a positive electrode active material has both excellent life characteristics (cycle life characteristics) and output characteristics when repeatedly used in charge and discharge in the central region of the charge / discharge depth (eg, SOC 50-80%). Since it exhibits, it is particularly excellent in the use of a positive electrode active material of a large-sized lithium battery used as a power source for driving a motor mounted on an electric vehicle (EV) or a hybrid electric vehicle (HEV).
  • EV electric vehicle
  • HEV hybrid electric vehicle
  • HEV means an automobile using two power sources, that is, an electric motor and an internal combustion engine.
  • lithium battery is intended to encompass all batteries containing lithium or lithium ions in the battery, such as lithium primary batteries, lithium secondary batteries, lithium ion secondary batteries, and lithium polymer batteries.
  • X is preferably greater than X” or “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It also includes the meaning of “smaller”.
  • X or more is an arbitrary number
  • Y or less is an arbitrary number
  • the Rietveld method using the fundamental method is a method for refining the crystal structure parameters from the diffraction intensity obtained by powder X-ray diffraction or the like. This method assumes a crystal structure model, and refines various parameters of the crystal structure so that the X-ray diffraction pattern derived from the structure and the measured X-ray diffraction pattern match as much as possible.
  • Detector PSD Detector Type: VANTEC-1 High Voltage: 5616V Discr. Lower Level: 0.35V Discr. Window Width: 0.15V Grid Lower Level: 0.075V Grid Window Width: 0.524V Flood Field Correction: Disabled Primary radius: 250mm Secondary radius: 250mm Receiving slit width: 0.1436626mm Divergence angle: 0.3 ° Filament Length: 12mm Sample Length: 25mm Receiving Slit Length: 12mm Primary Sollers: 2.623 ° Secondary Sollers: 2.623 ° Lorentzian, 1 / Cos: 0.01630098Th
  • Li battery evaluation was performed by the following method.
  • PVDF Korean Chemical Co., Ltd.
  • positive electrode active material spinel type lithium transition metal oxide obtained in Examples and Comparative Examples
  • 0.60 g of acetylene black manufactured by Denki Kagaku Kogyo
  • NMP N-methylpyrrolidone
  • 5.0 g of 12 wt% dissolved solution was accurately weighed and 5 ml of NMP was added and mixed well to prepare a paste.
  • This paste is placed on an aluminum foil as a current collector, formed into a coating film with an applicator adjusted to a gap of 250 ⁇ m, vacuum-dried at 120 ° C.
  • the negative electrode was made of metal Li having a diameter of 20 mm and a thickness of 1.0 mm, and an electrochemical evaluation cell TOMCEL (registered trademark) shown in FIG. 2 was produced using these materials.
  • the positive electrode 3 made of the positive electrode mixture was disposed at the inner center of the lower body 1 made of organic electrolyte-resistant stainless steel.
  • a separator 4 made of a microporous polypropylene resin impregnated with an electrolytic solution was disposed, and the separator was fixed with a Teflon (registered trademark) spacer 5.
  • a negative electrode 6 made of metal Li was disposed below, a spacer 7 also serving as a negative electrode terminal was disposed, and the upper body 2 was placed thereon and tightened with screws to seal the battery.
  • the electrolytic solution used was a mixture of EC and DMC in a volume of 3: 7, and a solvent in which LiPF 6 was dissolved in 1 mol / L as a solute.
  • the high temperature cycle life characteristic value (0.1 C) was obtained by dividing the percentage (%) of the numerical value obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the second cycle.
  • the same cycle condition was changed from 0.1 C to 1.0 C, and a high temperature cycle life characteristic value (1.0 C) was obtained. All are shown in Table 2 as relative values when the value of Example 3 is taken as 100.
  • Example 1-3 Lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, magnesium oxide 65.7 g were set at a high speed blade rotation speed 400 rpm cross screw with a precision mixer (vertical granulator (Fuji Sangyo Co., Ltd. (FM-VG-25)), Mix for 5 minutes.
  • the fired powder obtained by firing was crushed in a mortar, classified with a sieve having an opening of 53 ⁇ m, and the powder under the sieve was collected to obtain a crushed sample.
  • the obtained crushed sample was heat-treated using a tube furnace heating device (Koyo Thermo System Co., Ltd.). That is, 200 g of crushed samples were filled in a magnetic boat, and this magnetic boat was installed near the center of the tube furnace. Then, while flowing oxygen gas (oxygen concentration 100%) into the tube furnace at a flow rate of 0.5 l / min, the sample was heated to the set temperature shown in Table 1 at a heating rate of 1.7 ° C./min. Hold for a predetermined time. Then, while continuing oxygen inflow, it cooled to room temperature at the temperature-fall rate shown in Table 1, and obtained the spinel type lithium transition metal oxide (sample).
  • the oxygen concentration was measured using an oxygen concentration meter (XPO-318 (New Cosmos Electric Co., Ltd.)) (the same applies to comparative examples described later).
  • the temperature at the time of the firing and the heat treatment is the product temperature of the processed product measured by bringing a thermocouple into contact with the processed product in the furnace (the same applies to comparative examples described later).
  • Example 1 A spinel-type lithium transition metal oxide (sample) was obtained using the same raw materials as in Example 1 except that heat treatment was not performed, and mixing, firing, crushing, and classification were performed in the same manner as in Example 1.
  • Example 2 Using the same raw materials as in Example 1, mixing, firing, crushing and classification were performed in the same manner as in Example 1 to obtain a crushed sample. Next, the obtained crushed sample was heat-treated using a stationary electric furnace. That is, 200 g of the crushed sample was filled in a magnetic boat and shown in Table 1 at a temperature increase rate of 1.7 ° C./min in an air atmosphere (atmospheric pressure: 0.10 MPa, oxygen partial pressure: 0.021 MPa). Heated to the set temperature and held for a predetermined time after reaching. Then, while continuing oxygen inflow, it cooled to room temperature at the temperature-fall rate shown in Table 1, and obtained the spinel type lithium transition metal oxide (sample).
  • Example 4-9 Using the same raw materials as in Example 1, except for changing the atmosphere and heat treatment time in the heat treatment to the conditions shown in Table 3, the mixing of the raw materials to the heat treatment was performed in the same manner as in Example 1 to perform the spinel lithium transition. A metal oxide (sample) was obtained.
  • Examples 10-22 and Comparative Example 4> Using the same raw materials as in Example 1, except that the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3, the process from mixing of raw materials to heat treatment was carried out in the same manner as in Example 1 to spinel lithium transition A metal oxide (sample) was obtained.
  • Example 23 and Comparative Example 5 Example 1 except that the blending composition of the raw materials was changed to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, and 129.0 g of titanium oxide, and the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3.
  • the spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as described above.
  • Example 24 The raw material composition was changed to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 32.87 g of magnesium oxide, and 64.48 g of titanium oxide, and the conditions during firing and heat treatment were changed to the conditions shown in Table 3.
  • the spinel type lithium transition metal oxide was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in Example 1.
  • Example 25 Except for changing the composition of the raw materials to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 146.68 g of nickel hydroxide, and changing the conditions at the time of firing and heat treatment to the conditions shown in Table 3, Examples The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in 1.
  • Example 26 The raw material composition was changed to lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, cobalt oxyhydroxide 145.48 g, and the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3
  • the spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in Example 1.
  • Example 27 The raw material composition was changed to lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, iron (iii) 132.99 g, and the conditions during firing and heat treatment were changed to the conditions shown in Table 3, In the same manner as in Example 1, mixing of raw materials to heat treatment was performed to obtain a spinel type lithium transition metal oxide (sample).
  • Example 28> Except for changing the composition of the raw materials to 1756.3 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 61.83 g of aluminum hydroxide, and changing the conditions at the time of firing and heat treatment to the conditions shown in Table 3, Example The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in 1.
  • the reaction to be heated to around 900 ° C. is a reaction in which particles are grown while releasing oxygen at the primary oxygen release temperature, the secondary oxygen release temperature, and the like.
  • the secondary oxygen release temperature and the secondary oxygen release temperature shift to the high temperature side. As a result, it can be considered that the crystal growth reaction does not proceed and the crystallite size is reduced.
  • the lower the oxygen partial pressure the more the particle growth can be promoted. From this point of view, it is necessary to be 0.15 MPa or less in order to grow particles to the same extent as in the examples. Moreover, if it is about 0.015 Mpa, it can be considered that distortion can be recovered to about the level of the embodiment by heat treatment.
  • the firing temperature at the time of firing it can be considered from the examples and past experience that particles of 850 ° C. or higher can be sufficiently grown. In addition, since firing at a high temperature exceeding 1050 ° C. may cause phase separation in terms of crystal structure, firing at 1050 ° C. or less is preferable.
  • the oxygen partial pressure in the heat treatment is higher than that in the atmosphere (0.021 MPa), particularly an oxygen content of 0.03 MPa or more, from the viewpoint of recovering strain by incorporating oxygen into the crystal structure from Example 1-22. It is considered preferable to perform the heat treatment under pressure. In addition, it can be considered that it is preferable that the oxygen partial pressure is higher than that at the time of firing as compared with the atmosphere at the time of firing.
  • the heating temperature in the heat treatment is heated to the vicinity of the primary oxygen release temperature at which oxygen can easily be taken in, specifically, to the primary oxygen release temperature ⁇ 50 ° C.
  • the primary oxygen release temperature to the primary oxygen release temperature + 50 ° C., that is, higher than the primary oxygen release temperature.
  • heat treatment is preferably performed in the temperature range on the side. From the results of the examples, regarding the pressure of the atmosphere at the time of heat treatment, it can be considered that oxygen of 0.10 MPa or more is more preferable because it is easier to take in oxygen. 5 MPa or less.
  • oxygen taken in the vicinity of the primary oxygen release temperature is stabilized, so that it slowly passes 10 ° C./min or less until the temperature close to the primary oxygen release temperature, that is, at least up to 500 ° C. It is considered preferable to cool at a temperature drop rate.

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Abstract

Disclosed is a novel method for producing a lithium transition metal oxide, which is capable of increasing the crystallite size, while suppressing oxygen defects. Specifically disclosed is a method for producing a lithium transition metal oxide, which comprises a step of mixing starting materials, a firing step, and a heat treatment step, and which is characterized in that the starting materials are fired in an atmosphere having an oxygen partial pressure of from 0.015 MPa to 0.15 MPa at a temperature not less than 850°C, and then the resulting material is heat-treated in an atmosphere having an oxygen partial pressure of not less than 0.03 MPa at a temperature that is the primary oxygen release temperature ± 50°C. Since the method is capable of suppressing oxygen defects while increasing the crystallite size, the strain is reduced and the lithium transition metal oxide has a strong skeleton. Consequently, when the lithium transition metal oxide is used as a positive electrode active material for a lithium secondary battery, the lithium secondary battery is able to have adequate output characteristics and adequate high-temperature cycle life characteristics at the same time.

Description

リチウム遷移金属酸化物の製造方法Method for producing lithium transition metal oxide
　本発明は、リチウム遷移金属酸化物、特にリチウム二次電池の正極活物質として使用し得るリチウム遷移金属酸化物の製造方法に関する。 The present invention relates to a method for producing a lithium transition metal oxide, particularly a lithium transition metal oxide that can be used as a positive electrode active material of a lithium secondary battery.
　リチウム電池、特にリチウム二次電池は、エネルギー密度が大きく、寿命が長いなどの特徴を有しており、ビデオカメラ等の家電製品や、ノート型パソコン、携帯電話機等の携帯型電子機器などの電源として広く用いられている。最近では、電気自動車（ＥＶ）やハイブリッド電気自動車（ＨＥＶ）などに搭載される大型電池への応用が期待されている。 Lithium batteries, especially lithium secondary batteries, have features such as high energy density and long life, and power supplies for home appliances such as video cameras, portable electronic devices such as notebook computers and mobile phones. Is widely used. Recently, application to large batteries mounted on electric vehicles (EV), hybrid electric vehicles (HEV), and the like is expected.
　リチウム二次電池は、充電時には正極からリチウムがイオンとして抜け出して負極へ移動して吸蔵され、放電時には逆に負極から正極へリチウムイオンが戻る構造の二次電池であり、その高いエネルギー密度は正極材料の電位に起因することが知られている。 A lithium secondary battery is a secondary battery with a structure in which lithium is extracted as ions from the positive electrode during charging, moves to the negative electrode and is stored, and reversely, lithium ions return from the negative electrode to the positive electrode during discharging. It is known to be due to the potential of the material.
　リチウム二次電池の正極活物質として使用し得るリチウム遷移金属酸化物としては、層構造をもつＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＭｎＯ2などのリチウム遷移金属酸化物のほか、ＬｉＭｎ2Ｏ4、ＬｉＮｉ0.5Ｍｎ1.5Ｏ4などのマンガン系のスピネル構造（Ｆｄ－３ｍ）を有するリチウム遷移金属酸化物（本発明では「スピネル型リチウム遷移金属酸化物」或いは「ＬＭＯ」とも称する）が知られている。 Examples of the lithium transition metal oxide that can be used as the positive electrode active material of the lithium secondary battery include lithium transition metal oxides such as LiCoO 2 , LiNiO 2 , and LiMnO 2 having a layer structure, LiMn 2 O 4 , and LiNi 0.5 Mn. A lithium transition metal oxide having a manganese-based spinel structure (Fd-3m) such as 1.5 O 4 (also referred to as “spinel-type lithium transition metal oxide” or “LMO” in the present invention) is known.
　マンガン系のスピネル型リチウム遷移金属酸化物（ＬＭＯ）は、原料価格が安く、毒性がなく、また安全性が高いため、電気自動車（ＥＶ）やハイブリッド電気自動車（ＨＥＶ）などの大型電池用の正極活物質として着目されている。また、ＥＶやＨＥＶ用電池には優れた出力特性が特に求められるが、この点、層構造をもつＬｉＣｏＯ2などのリチウム遷移金属酸化物に比べ、３次元的にＬｉイオンの挿入・脱離が可能なスピネル型リチウム遷移金属酸化物（ＬＭＯ）は出力特性に優れている。 Manganese spinel-type lithium transition metal oxide (LMO) is a positive electrode for large batteries such as electric vehicles (EV) and hybrid electric vehicles (HEV) because of its low raw material price, non-toxicity, and high safety. It is attracting attention as an active material. Moreover, excellent output characteristics are particularly required for batteries for EVs and HEVs. In this regard, insertion and desorption of Li ions are three-dimensionally compared with lithium transition metal oxides such as LiCoO 2 having a layer structure. A possible spinel type lithium transition metal oxide (LMO) has excellent output characteristics.
　ところで、通常のスピネル型リチウム遷移金属酸化物（ＬＭＯ）は、高温領域（例えば４５～６０℃）でサイクルを重ねると、Ｍｎ2+が溶出し易くなり、溶出したＭｎ2+が負極に析出し、これが抵抗となって容量劣化を起こすようになるため、スピネル型リチウム遷移金属酸化物（ＬＭＯ）を実用する際の課題は高温領域（例えば４５～６０℃）でのサイクル寿命特性にあると言われてきた。
　ＬＭＯの骨格は、酸素（Ｏ）で構成されるため、Ｏが欠損すると骨格が弱くなり、寿命、特に高温サイクル寿命特性が低下することになる。特に高温で焼成されるスピネル型リチウム遷移金属酸化物（ＬＭＯ）は、酸素欠損が大きくなって結晶構造の歪みが大きくなり、Ｌｉ－Ｍｎ－Ｏの結合力が低下し、充放電サイクル時のマンガンの溶出が顕著となり、電池の劣化が促進することが知られている。
　このため、ＬＭＯの製造に関しては、従来から酸素欠損若しくは結晶構造の歪みを少なくするための手段が検討されている。 By the way, in a normal spinel type lithium transition metal oxide (LMO), when cycles are repeated in a high temperature region (for example, 45 to 60 ° C.), Mn 2+ easily elutes, and the eluted Mn 2+ precipitates on the negative electrode. Since this becomes a resistance and causes capacity deterioration, it is said that the problem in practical use of the spinel type lithium transition metal oxide (LMO) is the cycle life characteristic in a high temperature region (for example, 45 to 60 ° C.). I have been.
Since the skeleton of LMO is composed of oxygen (O), if O is lost, the skeleton becomes weak, and the life, in particular, the high-temperature cycle life characteristics is deteriorated. In particular, spinel type lithium transition metal oxide (LMO) fired at a high temperature increases oxygen deficiency, increases the distortion of the crystal structure, decreases Li—Mn—O bond strength, and manganese during charge / discharge cycles. It is known that the elution of the battery becomes remarkable and the deterioration of the battery is promoted.
For this reason, with respect to the production of LMO, means for reducing oxygen vacancies or crystal structure distortion have been studied.
　例えば特許文献１には、高温焼成後に水酸化リチウムを添加して、さらに低い温度で再焼成することによって、酸素欠損を抑制する方法が開示されている。
　また、特許文献２には、出発原料を、酸化雰囲気中、９００～１０００℃の範囲の温度で、５～５０時間の範囲の時間をかけて焼成し、次いで、酸化雰囲気中、６００～９００℃の範囲の温度で、１～５０時間の範囲の時間をかけて再焼成することによって、酸素欠損を抑制する方法が開示されている。
　また、特許文献３には、原料の混合物を高温焼成して焼成物を作成し、前記焼成物を流動させながら再焼成するリチウム複合酸化物の製造方法が提案されている。 For example, Patent Document 1 discloses a method of suppressing oxygen deficiency by adding lithium hydroxide after high-temperature baking and re-baking at a lower temperature.
In Patent Document 2, the starting material is baked in an oxidizing atmosphere at a temperature in the range of 900 to 1000 ° C. for 5 to 50 hours, and then in an oxidizing atmosphere at 600 to 900 ° C. A method for suppressing oxygen deficiency by re-baking at a temperature in the range of 1 to 50 hours for a time in the range of 1 to 50 hours is disclosed.
Patent Document 3 proposes a method for producing a lithium composite oxide in which a mixture of raw materials is fired at a high temperature to produce a fired product, and the fired product is refired while flowing.
特開２００１－３３５３２３号公報JP 2001-335323 A 特開２００６－２５２９４０号公報JP 2006-252940 A 特開２００７－１４９４１４号公報JP 2007-149414 A
　本発明の課題は、出力特性（レート特性）と高温サイクル寿命特性とを両立し得るリチウム遷移金属酸化物を提供するべく、結晶子サイズを大きくすることができ、それでいて結晶構造の歪みを抑制することができる、新たなリチウム遷移金属酸化物の製造方法を提供することにある。 An object of the present invention is to provide a lithium transition metal oxide that can achieve both output characteristics (rate characteristics) and high-temperature cycle life characteristics, and can increase the crystallite size and suppress the distortion of the crystal structure. Another object of the present invention is to provide a new method for producing a lithium transition metal oxide.
　かかる課題を解決するため、本発明は、原料を混合する工程、焼成する工程、熱処理する工程を備えたリチウム遷移金属酸化物の製造方法において、酸素分圧０．０１５ＭＰａ～０．１５ＭＰａの雰囲気下にて８５０℃以上で焼成した後、酸素分圧０．０３ＭＰａ以上の雰囲気下にて、第１次酸素放出温度±５０℃の温度で熱処理することを特徴とするリチウム遷移金属酸化物の製造方法を提案するものである。 In order to solve this problem, the present invention provides a method for producing a lithium transition metal oxide comprising a step of mixing raw materials, a step of firing, and a step of heat treatment, in an atmosphere having an oxygen partial pressure of 0.015 MPa to 0.15 MPa. And heat treatment at a primary oxygen release temperature of ± 50 ° C. in an atmosphere having an oxygen partial pressure of 0.03 MPa or more after baking at 850 ° C. in a method for producing a lithium transition metal oxide This is a proposal.
　本発明の製造方法によれば、結晶子サイズを大きくしつつ、かつ結晶構造の歪みを抑制することができるため、歪が減少して骨格が強固となり、例えばリチウム二次電池の正極活物質として使用した場合に、出力特性（レート特性）と高温サイクル寿命特性とを両立することができる新たなリチウム遷移金属酸化物を提供することができる。 According to the production method of the present invention, since the crystallite size can be increased and the distortion of the crystal structure can be suppressed, the distortion is reduced and the skeleton is strengthened. For example, as a positive electrode active material of a lithium secondary battery When used, it is possible to provide a new lithium transition metal oxide capable of achieving both output characteristics (rate characteristics) and high-temperature cycle life characteristics.
　なお、本発明の製造方法によれば、上述のように結晶子サイズを大きくしつつ、かつ結晶構造の歪みを抑制することができ、歪み０．０５以下で、且つ、結晶子サイズが２５０ｎｍ～１０００ｎｍのスピネル型リチウム遷移金属酸化物を得ることができる。このようなスピネル型リチウム遷移金属酸化物は、本出願の時点では日本国内で公然知られた物とは認められない。 According to the manufacturing method of the present invention, it is possible to suppress the distortion of the crystal structure while increasing the crystallite size as described above, the strain is 0.05 or less, and the crystallite size is 250 nm to A 1000 nm spinel lithium transition metal oxide can be obtained. Such spinel-type lithium transition metal oxides are not recognized as publicly known in Japan at the time of this application.
第１次酸素放出温度及び第２次酸素放出温度を説明するために、実施例１のスピネル型リチウム遷移金属酸化物のＴＧ曲線を示した図である。In order to demonstrate a primary oxygen release temperature and a secondary oxygen release temperature, it is the figure which showed the TG curve of the spinel type lithium transition metal oxide of Example 1. FIG. 実施例及び比較例で得られたサンプルの電池特性を評価するために作製した電気化学用セルの構成を示した図である。It is the figure which showed the structure of the cell for electrochemical produced in order to evaluate the battery characteristic of the sample obtained by the Example and the comparative example.
　以下、本発明の実施形態について説明する。但し、本発明の範囲が下記実施形態に限定されるものではない。 Hereinafter, embodiments of the present invention will be described. However, the scope of the present invention is not limited to the following embodiment.
＜製造方法＞
　本実施形態は、スピネル型（Ｆｄ－３ｍ）リチウム遷移金属酸化物の製造方法に関する実施形態である。 <Manufacturing method>
This embodiment relates to a method for producing a spinel (Fd-3m) lithium transition metal oxide.
　本実施形態の製造方法は、原料を混合した後、所定の酸素分圧雰囲気下にて８５０℃以上で焼成した後、大気よりも酸素分圧の高い雰囲気下にて熱処理することを特徴とする。
　以下、順を追って詳細に説明する。 The manufacturing method of this embodiment is characterized in that after the raw materials are mixed, calcined at 850 ° C. or higher in a predetermined oxygen partial pressure atmosphere, and then heat-treated in an atmosphere having a higher oxygen partial pressure than the atmosphere. .
Hereinafter, the details will be described in order.
（原料）
　出発原料としては、少なくともリチウム原料及びマンガン原料を適宜選択すればよい。 (material)
As the starting material, at least a lithium material and a manganese material may be appropriately selected.
　リチウム原料は、特に限定するものではなく、例えば水酸化リチウム（ＬｉＯＨ）、炭酸リチウム（Ｌｉ２ＣＯ３）、硝酸リチウム（ＬｉＮＯ3）、ＬｉＯＨ・Ｈ2Ｏ、酸化リチウム（Ｌｉ2Ｏ）、その他脂肪酸リチウムやリチウムハロゲン化物等が挙げられる。中でもリチウムの水酸化物塩、炭酸塩、硝酸塩が好ましい。 The lithium raw material is not particularly limited. For example, lithium hydroxide (LiOH), lithium carbonate (Li 2 CO 3 ), lithium nitrate (LiNO 3 ), LiOH.H 2 O, lithium oxide (Li 2 O), and others Examples include lithium fatty acid and lithium halide. Of these, lithium hydroxide salts, carbonates and nitrates are preferred.
　マンガン原料としては、二酸化マンガン、四酸化三マンガン、三酸化二マンガン、炭酸マンガン等のいずれか或いはこれらから選択される二種類以上の組合わせからなる混合物を用いることができる。
　二酸化マンガンとしては、化学合成二酸化マンガン（ＣＭＤ）、電解によって得られる電解二酸化マンガン（ＥＭＤ）、炭酸マンガン或いは天然二酸化マンガンを用いることができる。 As the manganese raw material, any of manganese dioxide, trimanganese tetroxide, dimanganese trioxide, manganese carbonate, or a mixture of two or more selected from these can be used.
As manganese dioxide, chemically synthesized manganese dioxide (CMD), electrolytic manganese dioxide (EMD) obtained by electrolysis, manganese carbonate, or natural manganese dioxide can be used.
　本実施形態においては、リチウム原料及びマンガン原料の他に、例えばマグネシウム原料やアルミニウム原料、その他、リチウム遷移金属酸化物の出発原料として知られている物質を配合することもできる。
　この際、マグネシウム原料としては、特に限定するものではなく、例えば酸化マグネシウム（ＭｇＯ）、水酸化マグネシウム（Ｍｇ（ＯＨ）2）、フッ化マグネシウム（ＭｇＦ2）、硝酸マグネシウム（Ｍｇ（ＮＯ3）2）などを用いることができ、中でも酸化マグネシウムが好ましい。
　アルミニウム原料としては、特に限定するものではない。例えば水酸化アルミニウム（Ａｌ（ＯＨ）3）、フッ化アルミニウム（ＡｌＦ３）などを用いることができ、中でも水酸化アルミニウムが好ましい。 In the present embodiment, in addition to the lithium raw material and the manganese raw material, for example, a magnesium raw material, an aluminum raw material, and other substances known as starting materials for lithium transition metal oxides can be blended.
In this case, the magnesium raw material is not particularly limited. For example, magnesium oxide (MgO), magnesium hydroxide (Mg (OH) 2 ), magnesium fluoride (MgF 2 ), magnesium nitrate (Mg (NO 3 ) 2 Etc.), among which magnesium oxide is preferred.
The aluminum raw material is not particularly limited. For example, aluminum hydroxide (Al (OH) 3 ), aluminum fluoride (AlF 3 ), or the like can be used, and aluminum hydroxide is particularly preferable.
　リチウム遷移金属酸化物の出発原料として知られているその他の物質としては、例えばＴｉ、Ｎｉ、Ｃｏ及びＦｅなどの元素を挙げることができ、出発原料としては、特に限定するものではない。例えば酸化物或いは水酸化物などを配合すればよい。 Examples of other substances known as starting materials for lithium transition metal oxides include elements such as Ti, Ni, Co and Fe, and the starting materials are not particularly limited. For example, an oxide or hydroxide may be blended.
（原料の混合）
　原料の混合は、均一に混合できれば、その方法を特に限定するものではない。例えばミキサー等の公知の混合機を用いて各原料を同時又は適当な順序で加えて湿式又は乾式で攪拌混合すればよい。置換しにくい元素、例えばアルミニウムなどを添加する場合には湿式混合を採用するのが好ましい。 (Mixing of raw materials)
The method of mixing raw materials is not particularly limited as long as it can be uniformly mixed. For example, the respective raw materials may be added simultaneously or in an appropriate order using a known mixer such as a mixer, and mixed by stirring in a wet or dry manner. When adding an element that is difficult to replace, such as aluminum, it is preferable to employ wet mixing.
　乾式混合としては、例えば高速で混合粉を回転させる精密混合機を使用した混合方法を例示することができる。
　他方、湿式混合としては、水や分散剤などの液媒体を加えて湿式混合してスラリー化させ、得られたスラリーを湿式粉砕機で粉砕する混合方法を例示することができる。特にサブミクロンオーダーまで粉砕するのが好ましい。サブミクロンオーダーまで粉砕した後、造粒及び焼成することにより、焼成反応前の各粒子の均一性を高めることができ、反応性を高めることができる。 Examples of the dry mixing include a mixing method using a precision mixer that rotates mixed powder at a high speed.
On the other hand, examples of the wet mixing include a mixing method in which a liquid medium such as water or a dispersant is added and wet mixed to form a slurry, and the resulting slurry is pulverized with a wet pulverizer. It is particularly preferable to grind to submicron order. After pulverizing to the submicron order, granulation and baking can increase the uniformity of each particle before the baking reaction, and the reactivity can be increased.
（造粒）
　上記の如く混合した原料は、必要に応じて所定の大きさに造粒した後、焼成してもよい。但し、造粒は必ずしもしなくてもよい。
　造粒方法は、前工程で粉砕された各種原料が分離せずに造粒粒子内で分散していれば湿式でも乾式でもよく、押し出し造粒法、転動造粒法、流動造粒法、混合造粒法、噴霧乾燥造粒法、加圧成型造粒法、或いはロール等を用いたフレーク造粒法でもよい。但し、湿式造粒した場合には、焼成前に充分に乾燥させることが必要である。
　乾燥方法としては、噴霧熱乾燥法、熱風乾燥法、真空乾燥法、フリーズドライ法などの公知の乾燥方法によって乾燥させればよく、中でも噴霧熱乾燥法が好ましい。噴霧熱乾燥法は、熱噴霧乾燥機（スプレードライヤー）を用いて行なうのが好ましい。熱噴霧乾燥機（スプレードライヤー）を用いて造粒することにより、粒度分布をよりシャープにすることができるばかりか、丸く凝集してなる凝集粒子（２次粒子）を含むように２次粒子の形態を調製することができる。 (Granulation)
The raw materials mixed as described above may be granulated to a predetermined size, if necessary, and then fired. However, granulation is not necessarily performed.
The granulation method may be wet or dry as long as the various raw materials pulverized in the previous step are dispersed in the granulated particles without being separated, and the extrusion granulation method, rolling granulation method, fluidized granulation method, A mixed granulation method, a spray drying granulation method, a pressure molding granulation method, or a flake granulation method using a roll or the like may be used. However, when wet granulation is performed, it is necessary to sufficiently dry before firing.
As a drying method, it may be dried by a known drying method such as a spray heat drying method, a hot air drying method, a vacuum drying method, a freeze drying method, etc. Among them, the spray heat drying method is preferable. The spray heat drying method is preferably performed using a heat spray dryer (spray dryer). By granulating with a thermal spray dryer (spray dryer), the particle size distribution can be made sharper, and the secondary particles can be formed so as to contain agglomerated particles (secondary particles) formed by agglomeration. Forms can be prepared.
（焼成）
　焼成は、酸素分圧が０．０１５ＭＰａ～０．１５ＭＰａの雰囲気下、例えば大気雰囲気下で行うのが好ましい。酸素分圧が０．１５ＭＰａより高いと、結晶成長を促進させることができず、結晶子サイズを大きくすることができない。また、後述するように、焼成によって結晶成長を促すためには、雰囲気の酸素分圧が低い方が好ましいが、焼成する際の酸素分圧が低過ぎると、酸素欠損が増大して熱処理によっても歪みを回復させることができなくなるため、酸素分圧０．０１５ＭＰａ以上で焼成するのが好ましい。
　かかる観点から、焼成時の酸素分圧は０．０１５ＭＰａ～０．１３ＭＰａであるのがさらに好ましく、特に０．０１５ＭＰａ～０．１２ＭＰａ、中でも０．０１５ＭＰａ以上、或いは０．０８ＭＰａ未満であるのがさらに好ましい。 (Baking)
Firing is preferably performed in an atmosphere having an oxygen partial pressure of 0.015 MPa to 0.15 MPa, for example, in an air atmosphere. If the oxygen partial pressure is higher than 0.15 MPa, crystal growth cannot be promoted and the crystallite size cannot be increased. In addition, as will be described later, in order to promote crystal growth by firing, it is preferable that the oxygen partial pressure in the atmosphere is low. However, if the oxygen partial pressure during firing is too low, oxygen deficiency will increase and heat treatment will also occur. Since the strain cannot be recovered, baking is preferably performed at an oxygen partial pressure of 0.015 MPa or more.
From this point of view, the oxygen partial pressure during firing is more preferably 0.015 MPa to 0.13 MPa, particularly 0.015 MPa to 0.12 MPa, especially 0.015 MPa or more, or less than 0.08 MPa. preferable.
　焼成温度は、高温焼成することにより、結晶成長を促進して結晶子サイズを大きくすることができるため、８５０℃以上、特に９１０～１，０５０℃、中でも特に９１０～９８０℃で焼成するのが好ましい。
　なお、この焼成温度とは、焼成炉内の焼成物に熱電対を接触させて測定される焼成物の品温を意味する。
　焼成時間、すなわち上記焼成温度を保持する時間は、焼成温度にもよるが、０．５時間～３０時間とすればよい。 The firing temperature can be increased at 850 ° C. or more, particularly 910 to 1,050 ° C., particularly 910 to 980 ° C., because high temperature firing can promote crystal growth and increase the crystallite size. preferable.
The firing temperature means the product temperature of the fired product measured by bringing a thermocouple into contact with the fired product in the firing furnace.
The firing time, that is, the time for maintaining the firing temperature may be 0.5 to 30 hours, although it depends on the firing temperature.
　焼成炉の種類は特に限定するものではない。例えばロータリーキルン、静置炉、その他の焼成炉を用いて焼成することができる。 The type of firing furnace is not particularly limited. For example, it can be fired using a rotary kiln, a stationary furnace, or other firing furnace.
（熱処理）
　次に、少なくとも大気よりも酸素分圧の高い雰囲気下にて、第１次酸素放出温度±５０℃の温度で熱処理することが重要である。
　このようにして熱処理することにより、結晶の歪みを低減することができる。 (Heat treatment)
Next, it is important to perform heat treatment at a temperature of primary oxygen release temperature ± 50 ° C. in an atmosphere having an oxygen partial pressure higher than that of air.
By performing the heat treatment in this manner, crystal distortion can be reduced.
　熱処理の雰囲気は、酸素分圧を０．０３ＭＰａ以上であって、焼成時より酸素分圧が高いことが好ましく、特に０．０５ＭＰａ以上、中でも特に０．０８ＭＰａ以上に制御して行うのが好ましい。酸素分圧の高い雰囲気で熱処理することで、平衡論的に酸素を取り込み易くなり、酸素欠損を抑えて歪みを低減することができる。 The atmosphere for the heat treatment is preferably such that the oxygen partial pressure is 0.03 MPa or higher and the oxygen partial pressure is higher than that during firing, particularly 0.05 MPa or higher, particularly 0.08 MPa or higher. By performing heat treatment in an atmosphere having a high oxygen partial pressure, oxygen can be easily taken in equilibrium, and oxygen vacancies can be suppressed to reduce strain.
　また、酸素濃度８０％～１００％の酸素ガスを流しながら熱処理するのが好ましい。新鮮な酸素を常に供給しながら熱処理することで、酸素を取り込み易くなり、酸素欠損をより一層抑えることができる。 Further, it is preferable to perform heat treatment while flowing oxygen gas having an oxygen concentration of 80% to 100%. By performing heat treatment while always supplying fresh oxygen, oxygen can be easily taken in, and oxygen vacancies can be further suppressed.
　さらに、熱処理時の雰囲気の圧力は、大気圧よりも大きい圧力、例えば０．１ＭＰａ～１．５ＭＰａに制御するのが好ましい。このように、酸素雰囲気を加圧することで、より一層酸素を取り込み易くなり、酸素欠損をより一層抑えることができる。
　かかる観点から、熱処理時の雰囲気の圧力は０．１ＭＰａ～１．５ＭＰａに制御するのが好ましく、特に０．１ＭＰａ～１．３ＭＰａ、中でも特に０．１ＭＰａ～１．０ＭＰａに制御するのが好ましい。 Furthermore, the pressure of the atmosphere during the heat treatment is preferably controlled to a pressure higher than atmospheric pressure, for example, 0.1 MPa to 1.5 MPa. Thus, by pressurizing the oxygen atmosphere, it becomes easier to take in oxygen and oxygen deficiency can be further suppressed.
From this viewpoint, the pressure of the atmosphere during the heat treatment is preferably controlled to 0.1 MPa to 1.5 MPa, more preferably 0.1 MPa to 1.3 MPa, and particularly preferably 0.1 MPa to 1.0 MPa.
　熱処理は、第１次酸素放出温度±５０℃、特に±３５℃、中でも±３０℃、その中でも特に±２０℃の温度範囲を保持することが好ましい。これらの中でも、第１次酸素放出温度を超えるエネルギーを与えることができる観点から、前記の各温度範囲において第１次酸素放出温度よりも高温側の温度範囲を保持することがより一層好ましい。
　この熱処理の温度とは、炉内の処理物に熱電対を接触させて測定される処理物の品温を意味する。
　リチウム遷移金属酸化物は、第１次酸素放出温度あたりまで加熱すると、Ｍｎ－Ｏの熱振動が大きくなってＭｎ－Ｏの結合力と拮抗して不安定になるため、第１次酸素放出温度±５０℃の温度範囲内で酸素を強制的に供給しながら熱処理することにより、結晶構造中に酸素を取り込んで歪みを効果的に低減することができる。
　この際、昇温速度は、０．５℃／ｍｉｎ～４℃／ｍｉｎとするのが好ましく、特に０．５℃／ｍｉｎ～３℃／ｍｉｎ、中でも特に０．５℃／ｍｉｎ～２℃／ｍｉｎとするのがさらに好ましい。
　なお、第１次酸素放出温度は、焼成後のスピネル型リチウム遷移金属酸化物を加熱し、６００℃～９００℃の範囲で重量減少する開始温度として求めることができる（図１参照）。 The heat treatment preferably maintains the primary oxygen release temperature ± 50 ° C., particularly ± 35 ° C., especially ± 30 ° C., and especially ± 20 ° C. Among these, it is more preferable to maintain a temperature range higher than the primary oxygen release temperature in each of the above temperature ranges from the viewpoint that energy exceeding the primary oxygen release temperature can be given.
The temperature of this heat treatment means the product temperature of the processed material measured by bringing a thermocouple into contact with the processed material in the furnace.
When the lithium transition metal oxide is heated to around the primary oxygen release temperature, the thermal vibration of Mn—O becomes large and becomes unstable by antagonizing the bonding force of Mn—O. By performing heat treatment while forcibly supplying oxygen within a temperature range of ± 50 ° C., oxygen can be taken into the crystal structure and distortion can be effectively reduced.
At this time, the rate of temperature rise is preferably 0.5 ° C./min to 4 ° C./min, particularly 0.5 ° C./min to 3 ° C./min, and particularly 0.5 ° C./min to 2 ° C./min More preferably, it is set to min.
The primary oxygen release temperature can be obtained as the starting temperature at which the spinel-type lithium transition metal oxide after heating is heated and the weight is reduced in the range of 600 ° C. to 900 ° C. (see FIG. 1).
　熱処理において第１次酸素放出温度±５０℃を保持する時間は、少なくとも１分間以上である必要がある。結晶構造内に酸素を十分に取り込ませるためには、少なくとも１分間は必要であると考えられる。かかる観点から、第１次酸素放出温度±５０℃を保持する時間は、好ましくは５分以上、特に好ましくは１０分以上である。 The time for maintaining the primary oxygen release temperature ± 50 ° C. in the heat treatment needs to be at least 1 minute. In order to fully incorporate oxygen into the crystal structure, at least one minute is considered necessary. From this viewpoint, the time for maintaining the primary oxygen release temperature ± 50 ° C. is preferably 5 minutes or more, particularly preferably 10 minutes or more.
　熱処理後の降温速度は、少なくとも５００℃までは１０℃／ｍｉｎ以下の冷却速度でゆっくり冷却するのが好ましく、特に０．１℃／ｍｉｎ～８℃／ｍｉｎ、中でも特に０．５℃／ｍｉｎ～５℃／ｍｉｎに制御するのがさらに好ましい。
　第１次酸素放出温度近辺で取り込んだ酸素が安定化すると考えられるため、第１次酸素放出温度近辺を過ぎるまで、すなわち、少なくとも５００℃まではゆっくり１０℃／ｍｉｎ以下の降温速度で冷却するのが好ましいと考えることができる。 The temperature lowering rate after the heat treatment is preferably slow cooling at a cooling rate of 10 ° C./min or less to at least 500 ° C., particularly 0.1 ° C./min to 8 ° C./min, especially 0.5 ° C./min to More preferably, it is controlled to 5 ° C./min.
Since the oxygen taken in near the primary oxygen release temperature is considered to be stabilized, the oxygen is slowly cooled at a temperature lowering rate of 10 ° C./min or less until the temperature close to the primary oxygen release temperature, that is, at least 500 ° C. Can be considered preferable.
＜リチウム遷移金属酸化物＞
　上述した本実施形態の製造方法によれば、次に説明する特徴を有するスピネル型リチウム遷移金属酸化物（「本ＬＭＯ」とも称する）を得ることができる。 <Lithium transition metal oxide>
According to the manufacturing method of the present embodiment described above, a spinel type lithium transition metal oxide (also referred to as “present LMO”) having the characteristics described below can be obtained.
（組成）
　本ＬＭＯは、Ｌｉ及びＭｎのほかに、Ｔｉ、Ｎｉ、Ｍｇ、Ｃｏ及びＦｅの何れか、或いはこれら２種類以上の組み合わせを含むスピネル型（Ｆｄ－３ｍ）リチウム遷移金属酸化物である。
　Ｌｉ及びＭｎ以外の置換元素の含有量としては、歪み除去の観点から、０～１．８ｗｔ%が好ましく、特に０．２～１．０ｗｔ％、中でも特に０．４～０．６ｗｔ％であるのがより一層好ましい。 (composition)
The present LMO is a spinel (Fd-3m) lithium transition metal oxide containing, in addition to Li and Mn, any one of Ti, Ni, Mg, Co and Fe, or a combination of two or more thereof.
The content of substitutional elements other than Li and Mn is preferably 0 to 1.8 wt%, particularly 0.2 to 1.0 wt%, particularly 0.4 to 0.6 wt% from the viewpoint of strain removal. Is even more preferable.
（歪み）
　本実施形態の製造方法によれば、得られるスピネル型リチウム遷移金属酸化物の歪みを０．０５以下、中でも好ましくは０．０２以下、その中でも好ましくは０．００９以下に調整することができる。この程度に歪みを減少させれば、スピネル型リチウム遷移金属酸化物の骨格が強固となり、リチウム二次電池の正極活物質として使用した場合に、出力特性（レート特性）と高温サイクル寿命特性とを両立することができる。 (distortion)
According to the production method of the present embodiment, the strain of the obtained spinel-type lithium transition metal oxide can be adjusted to 0.05 or less, preferably 0.02 or less, and more preferably 0.009 or less. By reducing the strain to this extent, the skeleton of the spinel lithium transition metal oxide becomes stronger, and when used as a positive electrode active material for a lithium secondary battery, the output characteristics (rate characteristics) and high-temperature cycle life characteristics It can be compatible.
（結晶子サイズ）
　本実施形態の製造方法によれば、得られるスピネル型リチウム遷移金属酸化物の結晶子サイズを２５０ｎｍ～１０００ｎｍ、中でも３００～１０００ｎｍ、その中でも好ましくは３５０ｎｍ～９００ｎｍ、その中でも特に好ましくは４２０ｎｍ～７５０ｎｍに調整することができる。
　本ＬＭＯの結晶子サイズを２５０ｎｍ～１０００ｎｍにすることで、高温サイクル寿命特性を改善することができ、出力特性と高温サイクル寿命特性とを両立することができる。
　ここで、「結晶子」とは、単結晶とみなせる最大の集まりを意味し、ＸＲＤ測定しリートベルト解析を行なうことにより求めることができる。 (Crystallite size)
According to the manufacturing method of the present embodiment, the spinel-type lithium transition metal oxide obtained has a crystallite size of 250 nm to 1000 nm, particularly 300 to 1000 nm, preferably 350 nm to 900 nm, and particularly preferably 420 nm to 750 nm. Can be adjusted.
By setting the crystallite size of the present LMO to 250 nm to 1000 nm, the high temperature cycle life characteristics can be improved, and both the output characteristics and the high temperature cycle life characteristics can be achieved.
Here, “crystallite” means the largest group that can be regarded as a single crystal, and can be obtained by XRD measurement and Rietveld analysis.
（特性・用途）
　本ＬＭＯは、必要に応じて解砕・分級した後、リチウム電池の正極活物質として有効に利用することができる。
　例えば、本ＬＭＯと、カーボンブラック等からなる導電材と、テフロン（登録商標）バインダー等からなる結着剤とを混合して正極合剤を製造することができる。そしてそのような正極合剤を正極に用い、例えば負極にはリチウムまたはカーボン等のリチウムを吸蔵・脱蔵できる材料を用い、非水系電解質には六フッ化リン酸リチウム（ＬｉＰＦ６）等のリチウム塩をエチレンカーボネート－ジメチルカーボネート等の混合溶媒に溶解したものを用いてリチウム２次電池を構成することができる。但し、このような構成の電池に限定する意味ではない。 (Characteristics / Applications)
The present LMO can be effectively used as a positive electrode active material of a lithium battery after being crushed and classified as necessary.
For example, the positive electrode mixture can be manufactured by mixing the present LMO, a conductive material made of carbon black or the like, and a binder made of Teflon (registered trademark) binder or the like. Such a positive electrode mixture is used for the positive electrode, for example, a material that can occlude / desorb lithium such as lithium or carbon is used for the negative electrode, and a lithium salt such as lithium hexafluorophosphate (LiPF6) is used for the non-aqueous electrolyte. A lithium secondary battery can be formed by using a material in which is dissolved in a mixed solvent such as ethylene carbonate-dimethyl carbonate. However, the present invention is not limited to the battery having such a configuration.
　本ＬＭＯを正極活物質として備えたリチウム電池は、充放電深度の中心領域（例えばＳＯＣ５０－８０％）で充放電を繰り返して使用した場合に優れた寿命特性（サイクル寿命特性）及び出力特性をともに発揮するから、特に電気自動車（ＥＶ）やハイブリッド電気自動車（ＨＥＶ）に搭載するモータ駆動用電源として用いる大型のリチウム電池の正極活物質の用途に特に優れている。 A lithium battery equipped with the LMO as a positive electrode active material has both excellent life characteristics (cycle life characteristics) and output characteristics when repeatedly used in charge and discharge in the central region of the charge / discharge depth (eg, SOC 50-80%). Since it exhibits, it is particularly excellent in the use of a positive electrode active material of a large-sized lithium battery used as a power source for driving a motor mounted on an electric vehicle (EV) or a hybrid electric vehicle (HEV).
＜語句の説明＞
　本発明において、「ＨＥＶ」とは、電気モータと内燃エンジンという２つの動力源を併用した自動車の意である。
　また、「リチウム電池」とは、リチウム一次電池、リチウム二次電池、リチウムイオン二次電池、リチウムポリマー電池など、電池内にリチウム又はリチウムイオンを含有する電池を全て包含する意である。 <Explanation of words>
In the present invention, “HEV” means an automobile using two power sources, that is, an electric motor and an internal combustion engine.
The term “lithium battery” is intended to encompass all batteries containing lithium or lithium ions in the battery, such as lithium primary batteries, lithium secondary batteries, lithium ion secondary batteries, and lithium polymer batteries.
　本明細書において「Ｘ～Ｙ」（Ｘ，Ｙは任意の数字）と表現する場合、特にことわらない限り「Ｘ以上Ｙ以下」の意と共に、「好ましくはＸより大きい」或いは「好ましくはＹより小さい」の意も包含する。
　また、「Ｘ以上」（Ｘは任意の数字）或いは「Ｙ以下」（Ｙは任意の数字）と表現した場合、「Ｘより大きいことが好ましい」或いは「Ｙ未満であるのが好ましい」旨の意図も包含する。 In the present specification, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” or “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It also includes the meaning of “smaller”.
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.
　次に、実施例及び比較例に基づいて、本発明について更に説明するが、本発明が以下に示す実施例に限定されるものではない。 Next, the present invention will be further described based on examples and comparative examples, but the present invention is not limited to the examples shown below.
＜第１次酸素放出温度の測定＞
　焼成後のスピネル型リチウム遷移金属酸化物を４０ｍｇ秤量してＡｌ２Ｏ３深皿容器に入れ、空気を１００ｍｌ／ｍｉｎの流量でフローさせた状態（酸素分圧０．０２１ＭＰａ、酸素濃度２１％）で、昇温速度を５℃／ｍｉｎとして１１００℃まで加熱測定し、得られたＴＧ曲線（図１参照）から、６００℃～９００℃の範囲で重量減少した開始温度を「第一次酸素放出温度」として求めた。
　熱分析には、株式会社マック・サイエンス製ＴＧ－ＤＴＡ装置（ＴＧ－ＤＴＡ２０００Ｓ）を用いた。
　なお、特願２００９－１５９１６１号には、「Ｏ2ガス（純度９９．９％）を１００ｍｌ／ｍｉｎの流量でフローさせた状態で」と記載されていたが、当該「Ｏ2ガス（純度９９．９％）」は「空気」の誤記であった。 <Measurement of primary oxygen release temperature>
40 mg of spinel-type lithium transition metal oxide after calcination was weighed and placed in an Al 2 O 3 deep dish container, and air was allowed to flow at a flow rate of 100 ml / min (oxygen partial pressure 0.021 MPa, oxygen concentration 21%). Then, the temperature was increased to 1100 ° C. at a rate of temperature increase of 5 ° C./min. From the obtained TG curve (see FIG. 1), the starting temperature where the weight decreased in the range of 600 ° C. to 900 ° C. Calculated as “temperature”.
For thermal analysis, a TG-DTA apparatus (TG-DTA2000S) manufactured by Mac Science Co., Ltd. was used.
Note that Japanese Patent Application No. 2009-159161 has been described as "O 2 gas (purity 99.9%) in a state of being flow at a flow rate of 100 ml / min", the "O 2 gas (purity 99 .9%) ”was an error in“ air ”.
＜ＸＲＤの測定＞
　実施例及び比較例で得られたサンプル（粉体）について、結晶子サイズ及び歪みを、次に説明するファンダメンタル法を用いたリートベルト法により測定した。
　ファンダメンタル法を用いたリートベルト法は、粉末Ｘ線回折等により得られた回折強度から、結晶の構造パラメータを精密化する方法である。結晶構造モデルを仮定し、その構造から計算により導かれるＸ線回折パターンと、実測されたＸ線回折パターンとができるだけ一致するように、その結晶構造の各種パラメータを精密化する手法である。 <Measurement of XRD>
For the samples (powder) obtained in the examples and comparative examples, the crystallite size and strain were measured by the Rietveld method using the fundamental method described below.
The Rietveld method using the fundamental method is a method for refining the crystal structure parameters from the diffraction intensity obtained by powder X-ray diffraction or the like. This method assumes a crystal structure model, and refines various parameters of the crystal structure so that the X-ray diffraction pattern derived from the structure and the measured X-ray diffraction pattern match as much as possible.
　Ｘ線回折パターンの測定には、Ｃｕ‐Ｋα線を用いたＸ線回折装置（ブルカー・エイエックスエス株式会社製Ｄ８　ＡＤＶＡＮＣＥ）を使用した。回折角２θ＝１０～１２０°の範囲より得られたＸ線回折パターンのピークについて解析用ソフトウエア（製品名「Ｔｏｐａｓ　Ｖｅｒｓｉｏｎ３」）を用いて解析することにより結晶子サイズ及び歪みを求めた。
　なお、結晶構造は、空間群Ｆｄ－３ｍ(Ｏｒｉｇｉｎ　Ｃｈｏｉｃｅ2)の立方晶に帰属され、その８ａサイトにＬｉ、１６ｄサイトにＭｎ、Ｍｇ、そして過剰なＬｉ分ｘ、そして３２eにＯが占有されていると仮定し、パラメータＢｅｑ.を1と固定し、酸素の分率座標を変数として、表に示す通り観測強度と計算強度の一致の程度を表す指標Ｒｗｐ＜８．０、ＧＯＦ＜２．０を目安に収束するまで繰り返し計算を行った。なお、結晶子サイズ及び歪みはガウス関数を用い、解析を行った。 For the measurement of the X-ray diffraction pattern, an X-ray diffraction apparatus (D8 ADVANCE manufactured by Bruker AXS Co., Ltd.) using Cu-Kα rays was used. The peak of the X-ray diffraction pattern obtained from the diffraction angle 2θ = 10 to 120 ° was analyzed using analysis software (product name “Topas Version 3”) to obtain the crystallite size and strain.
The crystal structure is attributed to the cubic crystal of the space group Fd-3m (Origin Choice 2), with Li occupied at the 8a site, Mn, Mg at the 16d site, and an excess Li content x, and O at 32e. Assuming that the parameter Beq. Is fixed at 1 and the oxygen coordinate is a variable, the index Rwp <8.0, GOF <2.0 indicating the degree of agreement between the observed intensity and the calculated intensity as shown in the table The calculation was repeated until convergence was achieved. The crystallite size and strain were analyzed using a Gaussian function.
　その他測定・リートベルト法解析に使用した機器仕様・条件等は以下の通りである。
　Ｄｅｔｅｃｔｏｒ：ＰＳＤ
　Ｄｅｔｅｃｔｏｒ　Ｔｙｐｅ：ＶＡＮＴＥＣ－１
　Ｈｉｇｈ　Ｖｏｌｔａｇｅ：５６１６Ｖ
　Ｄｉｓｃｒ．　Ｌｏｗｅｒ　Ｌｅｖｅｌ：０．３５Ｖ
　Ｄｉｓｃｒ．　Ｗｉｎｄｏｗ　Ｗｉｄｔｈ：０．１５Ｖ
　Ｇｒｉｄ　Ｌｏｗｅｒ　Ｌｅｖｅｌ：０．０７５Ｖ
　Ｇｒｉｄ　Ｗｉｎｄｏｗ　Ｗｉｄｔｈ：０．５２４Ｖ
　Ｆｌｏｏｄ　Ｆｉｅｌｄ　Ｃｏｒｒｅｃｔｉｏｎ：Ｄｉｓａｂｌｅｄ
　Ｐｒｉｍａｒｙ　ｒａｄｉｕｓ：２５０ｍｍ
　Ｓｅｃｏｎｄａｒｙ　ｒａｄｉｕｓ：２５０ｍｍ
　Ｒｅｃｅｉｖｉｎｇ　ｓｌｉｔ　ｗｉｄｔｈ：０．１４３６６２６ｍｍ
　Ｄｉｖｅｒｇｅｎｃｅ　ａｎｇｌｅ：０．３°
　Ｆｉｌａｍｅｎｔ　Ｌｅｎｇｔｈ：１２ｍｍ
　Ｓａｍｐｌｅ　Ｌｅｎｇｔｈ：２５ｍｍ
　Ｒｅｃｅｉｖｉｎｇ　Ｓｌｉｔ　Ｌｅｎｇｔｈ：１２ｍｍ
　Ｐｒｉｍａｒｙ　Ｓｏｌｌｅｒｓ：２．６２３°
　Ｓｅｃｏｎｄａｒｙ　Ｓｏｌｌｅｒｓ：２．６２３°
　Ｌｏｒｅｎｔｚｉａｎ，１／Ｃｏｓ：０．０１６３００９８Ｔｈ Other equipment specifications and conditions used for other measurements and Rietveld analysis are as follows.
Detector: PSD
Detector Type: VANTEC-1
High Voltage: 5616V
Discr. Lower Level: 0.35V
Discr. Window Width: 0.15V
Grid Lower Level: 0.075V
Grid Window Width: 0.524V
Flood Field Correction: Disabled
Primary radius: 250mm
Secondary radius: 250mm
Receiving slit width: 0.1436626mm
Divergence angle: 0.3 °
Filament Length: 12mm
Sample Length: 25mm
Receiving Slit Length: 12mm
Primary Sollers: 2.623 °
Secondary Sollers: 2.623 °
Lorentzian, 1 / Cos: 0.01630098Th
＜電池評価＞
（電池の作製）
　Ｌｉ電池評価は以下の方法で行った。 <Battery evaluation>
(Production of battery)
Li battery evaluation was performed by the following method.
　正極活物質（実施例・比較例で得られたスピネル型リチウム遷移金属酸化物）８．８０ｇとアセチレンブラック（電気化学工業製）０．６０ｇ及びＮＭＰ（Ｎ-メチルピロリドン）中にＰＶＤＦ（キシダ化学製）１２ｗｔ％溶解した液５．０ｇを正確に計り取り、そこにＮＭＰを５ｍｌ加え十分に混合し、ペーストを作製した。このペーストを集電体であるアルミ箔上にのせ、２５０μｍのギャップに調整したアプリケーターで塗膜化し、１２０℃一昼夜真空乾燥した後、φ１６ｍｍで打ち抜き、４t／ｃｍ２でプレス厚密し、正極とした。電池作製直前に１２０℃で１２０ｍｉｎ以上真空乾燥し、付着水分を除去し電池に組み込んだ。また、予めφ１６ｍｍのアルミ箔の重さの平均値を求めておき、正極の重さからアルミ箔の重さを差し引き正極合材の重さを求め、また正極活物質とアセチレンブラック、ＰＶＤＦの混合割合から正極活物質の含有量を求めた。
　負極はφ２０ｍｍ×厚み１．０ｍｍの金属Ｌｉとし、これらの材料を使用して図２に示す電気化学評価用セルＴＯＭＣＥＬ（登録商標）を作製した。 PVDF (Kishida Chemical Co., Ltd.) in 8.80 g of positive electrode active material (spinel type lithium transition metal oxide obtained in Examples and Comparative Examples), 0.60 g of acetylene black (manufactured by Denki Kagaku Kogyo) and NMP (N-methylpyrrolidone) (Product made) 5.0 g of 12 wt% dissolved solution was accurately weighed and 5 ml of NMP was added and mixed well to prepare a paste. This paste is placed on an aluminum foil as a current collector, formed into a coating film with an applicator adjusted to a gap of 250 μm, vacuum-dried at 120 ° C. all day and night, punched out at φ16 mm, pressed thick at 4 t / cm 2 , did. Immediately before producing the battery, it was vacuum-dried at 120 ° C. for 120 minutes or more to remove the adhering moisture and incorporated into the battery. In addition, the average value of the weight of φ16 mm aluminum foil is obtained in advance, the weight of the positive electrode mixture is obtained by subtracting the weight of the aluminum foil from the weight of the positive electrode, and the mixture of the positive electrode active material, acetylene black and PVDF The content of the positive electrode active material was determined from the ratio.
The negative electrode was made of metal Li having a diameter of 20 mm and a thickness of 1.0 mm, and an electrochemical evaluation cell TOMCEL (registered trademark) shown in FIG. 2 was produced using these materials.
　図２の電気化学用セルは、耐有機電解液性のステンレス鋼製の下ボディ１の内側中央に、前記正極合材からなる正極３を配置した。この正極３の上面には、電解液を含浸した微孔性のポリプロピレン樹脂製のセパレータ４を配置し、テフロン（登録商標）スペーサー５によりセパレータを固定した。更に、セパレータ上面には、下方に金属Ｌｉからなる負極６を配置し、負極端子を兼ねたスペーサー７を配置し、その上に上ボディ２を被せて螺子で締め付け、電池を密封した。
　電解液は、ＥＣとＤＭＣを３：７体積混合したものを溶媒とし、これに溶質としてＬｉＰＦ6を１ｍｏＬ／Ｌ溶解させたものを用いた。 In the electrochemical cell of FIG. 2, the positive electrode 3 made of the positive electrode mixture was disposed at the inner center of the lower body 1 made of organic electrolyte-resistant stainless steel. On the upper surface of the positive electrode 3, a separator 4 made of a microporous polypropylene resin impregnated with an electrolytic solution was disposed, and the separator was fixed with a Teflon (registered trademark) spacer 5. Further, on the upper surface of the separator, a negative electrode 6 made of metal Li was disposed below, a spacer 7 also serving as a negative electrode terminal was disposed, and the upper body 2 was placed thereon and tightened with screws to seal the battery.
The electrolytic solution used was a mixture of EC and DMC in a volume of 3: 7, and a solvent in which LiPF 6 was dissolved in 1 mol / L as a solute.
（レート特性評価）
　上記のようにして準備した電気化学用セルを用いて下記に記述する方法で出力特性を求めた。
　２０℃にて４．３Ｖまで０．１Ｃで充電した状態で、正極中の正極活物質の含有量から、０．１Ｃ、１．０Ｃ、３．０Ｃ、５．０Ｃ、７．０Ｃの放電レートになるように電流値を算出した。その電流値を基にそれぞれのレートで定電流放電した時の３．０Ｖまでの放電容量（ｍＡｈ/ｇ）を測定した。レート－放電容量図を作成し、最小二乗法によって外挿し、直線近似式を求め直線傾きを算出し、実施例３の値を１００とした時の相対値として表２に示した。 (Rate characteristics evaluation)
Using the electrochemical cell prepared as described above, the output characteristics were determined by the method described below.
From the content of the positive electrode active material in the positive electrode in a state charged at 0.1 C to 4.3 V at 20 ° C., a discharge rate of 0.1 C, 1.0 C, 3.0 C, 5.0 C, 7.0 C The current value was calculated so that Based on the current value, the discharge capacity (mAh / g) up to 3.0 V when constant current discharge was performed at each rate was measured. A rate-discharge capacity diagram was created, extrapolated by the least square method, a linear approximation equation was obtained to calculate a linear slope, and the relative values when the value of Example 3 was set to 100 are shown in Table 2.
（高温サイクル寿命特性評価）
　上記のようにして準備した電気化学用セルを用いて下記に記述する方法で充放電試験し、高温サイクル寿命特性を求めた。
　電池充放電する環境温度を４５℃となるようにセットした環境試験機内にセルを入れ、充放電できるように準備し、セル温度が環境温度になるように４時間静置後、充放電範囲を３．０Ｖ～４．３Ｖとし、０．１Ｃで２サイクル充放電行った後、ＳＯＣ５０－８０％の充放電深度で、１Ｃにて充放電サイクルを４７回行い、５０サイクル目は容量確認の為、充放電範囲３．０Ｖ～４．３Ｖで０．１Ｃにて充放電を行った。
　５０サイクル目の放電容量を２サイクル目の放電容量で割り算して求めた数値の百分率（％）を高温サイクル寿命特性値（０．１Ｃ）を求めた。また、０．１Ｃを１．０Ｃに変更して同様なサイクル条件を行い、高温サイクル寿命特性値（１．０Ｃ）を求めた。いずれも、実施例３の値を１００とした時の相対値として表２に示した。 (High temperature cycle life characteristics evaluation)
Using the electrochemical cell prepared as described above, a charge / discharge test was performed by the method described below, and the high-temperature cycle life characteristics were obtained.
Place the cell in an environmental tester set so that the environmental temperature for charging and discharging the battery is 45 ° C., prepare for charging and discharging, and let stand for 4 hours so that the cell temperature becomes the environmental temperature. After charging and discharging at 3.0C to 4.3V for 2 cycles at 0.1C, the charge / discharge cycle was performed 47 times at 1C at an SOC of 50-80%, and the 50th cycle was for capacity confirmation. Then, charging / discharging was performed at 0.1 C in a charging / discharging range of 3.0 V to 4.3 V.
The high temperature cycle life characteristic value (0.1 C) was obtained by dividing the percentage (%) of the numerical value obtained by dividing the discharge capacity at the 50th cycle by the discharge capacity at the second cycle. In addition, the same cycle condition was changed from 0.1 C to 1.0 C, and a high temperature cycle life characteristic value (1.0 C) was obtained. All are shown in Table 2 as relative values when the value of Example 3 is taken as 100.
＜実施例１-３＞
　炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、酸化マグネシウム６５．７ｇを精密混合機(バーチカルグラニュレータ（富士産業株式会社製（ＦＭ-ＶＧ-２５））でブレード回転数４００ｒｐｍクロススクリュー高速に設定し、５分間混合した。
　得られた混合粉を、焼成容器（アルミナ製のルツボ大きさ＝たて＊よこ＊たかさ＝１０＊１０＊５（ｃｍ））内に、開放面積と充填高さの比（開放面積ｃｍ2／充填高さｃｍ）が１００となるように充填した。そして、静置式電気炉を用いて、表１に示す雰囲気において、常温から焼成設定温度まで昇温速度＝１５０℃／ｈｒで昇温し、表１に示す焼成温度（保持温度）を１４時間保持し、その後、保持温度から６００℃まで降温速度＝２０℃／ｈｒで降温させ、その後は常温まで自然冷却させた。なお、保持時間内の温度ばらつきは±５℃の範囲内で制御した。
　焼成して得られた焼成粉を乳鉢で解砕し、目開き５３μｍの篩で分級し、篩下の粉体を回収して解砕サンプルを得た。 <Example 1-3>
Lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, magnesium oxide 65.7 g were set at a high speed blade rotation speed 400 rpm cross screw with a precision mixer (vertical granulator (Fuji Sangyo Co., Ltd. (FM-VG-25)), Mix for 5 minutes.
The obtained mixed powder was placed in a firing container (alumina crucible size = vertical * width * warm = 10 * 10 * 5 (cm)) ratio of open area to filling height (open area cm 2 / Filling height cm) was filled to 100. Then, using a static electric furnace, in the atmosphere shown in Table 1, the temperature is raised from room temperature to the firing setting temperature at a heating rate = 150 ° C./hr, and the firing temperature (holding temperature) shown in Table 1 is held for 14 hours. Thereafter, the temperature was lowered from the holding temperature to 600 ° C. at a temperature lowering rate = 20 ° C./hr, and then naturally cooled to room temperature. The temperature variation within the holding time was controlled within a range of ± 5 ° C.
The fired powder obtained by firing was crushed in a mortar, classified with a sieve having an opening of 53 μm, and the powder under the sieve was collected to obtain a crushed sample.
　次に、得られた解砕サンプルをチューブ炉加熱装置（光洋サーモシステム株式会社）を使用して熱処理した。すなわち、解砕サンプル２００ｇを磁製ボートに充填し、この磁製ボートをチューブ炉の中心付近に設置した。その後、酸素ガス（酸素濃度１００％）を流量０．５ｌ／ｍｉｎでチューブ炉内に流入させながら、１．７℃／ｍｉｎの昇温速度で、表１に示す設定温度まで加熱し、到達後所定時間保持した。その後、酸素流入を継続しながら、室温まで表１に示す降温速度で冷却してスピネル型リチウム遷移金属酸化物（サンプル）を得た。 Next, the obtained crushed sample was heat-treated using a tube furnace heating device (Koyo Thermo System Co., Ltd.). That is, 200 g of crushed samples were filled in a magnetic boat, and this magnetic boat was installed near the center of the tube furnace. Then, while flowing oxygen gas (oxygen concentration 100%) into the tube furnace at a flow rate of 0.5 l / min, the sample was heated to the set temperature shown in Table 1 at a heating rate of 1.7 ° C./min. Hold for a predetermined time. Then, while continuing oxygen inflow, it cooled to room temperature at the temperature-fall rate shown in Table 1, and obtained the spinel type lithium transition metal oxide (sample).
　なお、酸素濃度は酸素濃度計(ＸＰＯ－３１８（新コスモス電機株式会社）)を用い測定した（後述する比較例でも同じ）。
　上記焼成時及び熱処理時の温度は、炉内の処理物に熱電対を接触させて測定した処理物の品温である（後述する比較例でも同じ）。 The oxygen concentration was measured using an oxygen concentration meter (XPO-318 (New Cosmos Electric Co., Ltd.)) (the same applies to comparative examples described later).
The temperature at the time of the firing and the heat treatment is the product temperature of the processed product measured by bringing a thermocouple into contact with the processed product in the furnace (the same applies to comparative examples described later).
＜比較例１＞
　熱処理を行わなかった以外、実施例１と同様の原料を用いて、実施例１と同様に混合、焼成、解砕し及び分級を行い、スピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Comparative Example 1>
A spinel-type lithium transition metal oxide (sample) was obtained using the same raw materials as in Example 1 except that heat treatment was not performed, and mixing, firing, crushing, and classification were performed in the same manner as in Example 1.
＜比較例２＞
　実施例１と同様の原料を用いて、実施例１と同様に混合、焼成、解砕し及び分級を行って解砕サンプルを得た。
　次に、得られた解砕サンプルを、静置式電気炉を用いて熱処理した。すなわち、解砕サンプル２００ｇを磁性ボート内に充填し、大気雰囲気（雰囲気圧力：０．１０ＭＰａ、酸素分圧：０．０２１ＭＰａ）において、１．７℃／ｍｉｎの昇温速度で、表１に示す設定温度まで加熱し、到達後所定の時間保持した。その後、酸素流入を継続しながら、室温まで表１に示す降温速度で冷却してスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Comparative Example 2>
Using the same raw materials as in Example 1, mixing, firing, crushing and classification were performed in the same manner as in Example 1 to obtain a crushed sample.
Next, the obtained crushed sample was heat-treated using a stationary electric furnace. That is, 200 g of the crushed sample was filled in a magnetic boat and shown in Table 1 at a temperature increase rate of 1.7 ° C./min in an air atmosphere (atmospheric pressure: 0.10 MPa, oxygen partial pressure: 0.021 MPa). Heated to the set temperature and held for a predetermined time after reaching. Then, while continuing oxygen inflow, it cooled to room temperature at the temperature-fall rate shown in Table 1, and obtained the spinel type lithium transition metal oxide (sample).
＜比較例３＞
　焼成時の雰囲気を、表１に示すような酸素加圧雰囲気に変更した以外は、比較例１と同様にしてスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Comparative Example 3>
A spinel type lithium transition metal oxide (sample) was obtained in the same manner as in Comparative Example 1 except that the atmosphere during firing was changed to an oxygen-pressurized atmosphere as shown in Table 1.
＜実施例４－９＞
　実施例１と同様の原料を用いて、熱処理時の雰囲気及び熱処理時間を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 4-9>
Using the same raw materials as in Example 1, except for changing the atmosphere and heat treatment time in the heat treatment to the conditions shown in Table 3, the mixing of the raw materials to the heat treatment was performed in the same manner as in Example 1 to perform the spinel lithium transition. A metal oxide (sample) was obtained.
＜実施例１０－２２・比較例４＞
　実施例１と同様の原料を用いて、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Examples 10-22 and Comparative Example 4>
Using the same raw materials as in Example 1, except that the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3, the process from mixing of raw materials to heat treatment was carried out in the same manner as in Example 1 to spinel lithium transition A metal oxide (sample) was obtained.
＜実施例２３・比較例５＞
　原料の配合組成を、炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、酸化チタン１２９．０ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 23 and Comparative Example 5>
Example 1 except that the blending composition of the raw materials was changed to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, and 129.0 g of titanium oxide, and the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3. The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as described above.
＜実施例２４＞
　原料の配合組成を、炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、酸化マグネシウム３２．８７ｇ、酸化チタン６４．４８ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 24>
The raw material composition was changed to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 32.87 g of magnesium oxide, and 64.48 g of titanium oxide, and the conditions during firing and heat treatment were changed to the conditions shown in Table 3. The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in Example 1.
＜実施例２５＞
　原料の配合組成を、炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、水酸化ニッケル１４６．６８ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 25>
Except for changing the composition of the raw materials to 1770.9 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 146.68 g of nickel hydroxide, and changing the conditions at the time of firing and heat treatment to the conditions shown in Table 3, Examples The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in 1.
＜実施例２６＞
　原料の配合組成を、炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、オキシ水酸化コバルト１４５．４８ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 26>
The raw material composition was changed to lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, cobalt oxyhydroxide 145.48 g, and the conditions at the time of firing and heat treatment were changed to the conditions shown in Table 3 The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in Example 1.
＜実施例２７＞
　原料の配合組成を、炭酸リチウム１７７０．９ｇ、電解二酸化マンガン７５００ｇ、酸化鉄(iii)１３２．９９ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 27>
The raw material composition was changed to lithium carbonate 1770.9 g, electrolytic manganese dioxide 7500 g, iron (iii) 132.99 g, and the conditions during firing and heat treatment were changed to the conditions shown in Table 3, In the same manner as in Example 1, mixing of raw materials to heat treatment was performed to obtain a spinel type lithium transition metal oxide (sample).
＜実施例２８＞
　原料の配合組成を、炭酸リチウム１７５６．３ｇ、電解二酸化マンガン７５００ｇ、水酸化アルミニウム６１．８３ｇに変更すると共に、焼成時及び熱処理時の条件を表３に示した条件に変更した以外は、実施例１と同様に原料の混合から熱処理までを行ってスピネル型リチウム遷移金属酸化物（サンプル）を得た。 <Example 28>
Except for changing the composition of the raw materials to 1756.3 g of lithium carbonate, 7500 g of electrolytic manganese dioxide, 61.83 g of aluminum hydroxide, and changing the conditions at the time of firing and heat treatment to the conditions shown in Table 3, Example The spinel type lithium transition metal oxide (sample) was obtained by carrying out from the mixing of the raw materials to the heat treatment in the same manner as in 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
（考察）
　比較例１の場合、熱処理しなかったため、焼成によって酸素が欠損したままであり、そのため、結晶構造の歪みが大きくなり、また、実施例１－３に比べると結晶子サイズも小さくなり、レート特性及び高温サイクル寿命特性のいずれも劣ることになった。
　比較例２の場合、常圧・大気雰囲気で熱処理を行っているため、酸素分圧が足りず、酸素の取り込みが不足したため、結晶構造の歪みが大きく、特にレート特性が劣る結果となった。ちなみに、Ｍｎ酸化物（例えばＭｎＯ2は約５６０℃でＭｎ2Ｏ3に還元する。）は加熱されると酸素を放出する熱還元特性をもっているため、平衡論的に見て、結晶構造中に十分に酸素を取り込み得る酸素分圧に達していなかったものと推察される。 (Discussion)
In the case of Comparative Example 1, since heat treatment was not performed, oxygen remained deficient by firing, so that the distortion of the crystal structure was increased, and the crystallite size was also reduced as compared with Example 1-3, and the rate characteristics. Both high temperature cycle life characteristics were inferior.
In the case of Comparative Example 2, since the heat treatment was performed under normal pressure and atmospheric atmosphere, the oxygen partial pressure was insufficient and the oxygen uptake was insufficient, resulting in large distortion of the crystal structure and particularly poor rate characteristics. By the way, Mn oxide (for example, MnO 2 is reduced to Mn 2 O 3 at about 560 ° C.) has a thermal reduction property that releases oxygen when heated. It is presumed that the oxygen partial pressure at which oxygen could be sufficiently taken in was not reached.
　比較例３のように酸素加圧しながら焼成すると、結晶子サイズが小さくなり、レート特性及び高温サイクル寿命特性のいずれも劣ることになることが分かった。９００℃近辺まで加熱する反応は、第１次酸素放出温度及び第２次酸素放出温度等で酸素を放出しながら粒子成長する反応であるため、酸素の分圧が高い状態で焼成すると、第１次酸素放出温度及び第２次酸素放出温度が高温側にシフトすることになる。その結果、結晶成長反応が進まなくなり、結晶子サイズが小さくなるものと考えることができる。 It was found that when firing with oxygen pressurization as in Comparative Example 3, the crystallite size was reduced and both the rate characteristics and the high-temperature cycle life characteristics were inferior. The reaction to be heated to around 900 ° C. is a reaction in which particles are grown while releasing oxygen at the primary oxygen release temperature, the secondary oxygen release temperature, and the like. The secondary oxygen release temperature and the secondary oxygen release temperature shift to the high temperature side. As a result, it can be considered that the crystal growth reaction does not proceed and the crystallite size is reduced.
　このような比較例１～３に対し、実施例１～３のように、酸素分圧０．０１５ＭＰａ～０．１５ＭＰａの雰囲気下にて８５０℃以上で焼成した後、大気よりも酸素分圧の高い雰囲気下にて熱処理することにより、結晶子サイズを大きくしつつ、かつ結晶構造の歪みを抑制することができるため、歪が減少して骨格が強固となり、出力特性（レート特性）と高温サイクル寿命特性とを両立できることが分かった。 In contrast to Comparative Examples 1 to 3, after firing at 850 ° C. or higher in an atmosphere with an oxygen partial pressure of 0.015 MPa to 0.15 MPa as in Examples 1 to 3, the oxygen partial pressure was higher than that of the atmosphere. By heat-treating in a high atmosphere, the crystallite size can be increased and the distortion of the crystal structure can be suppressed, so the distortion is reduced and the skeleton is strengthened, and the output characteristics (rate characteristics) and high-temperature cycle are reduced. It was found that both life characteristics can be achieved.
　また、焼成時の酸素分圧に関しては、上述のように、酸素分圧が低い方が粒子成長を促すことができる反面、酸素欠損を生じて歪みは大きくなる。かかる観点から、実施例と同程度に粒子成長させるためには０．１５ＭＰａ以下である必要がある。また、０．０１５ＭＰａ程度であれば、熱処理によって実施例程度に歪みを回復させることができるものと考えることができる。
　焼成時の焼成温度に関しては、実施例及びこれまでの経験から、８５０℃以上であれば十分に粒子を成長させることができるものと考えることができる。なお、１０５０℃を超えて高温焼成すると、結晶構造的な相分離する可能性があるため、１０５０℃以下で焼成するのが好ましい。 Regarding the oxygen partial pressure during firing, as described above, the lower the oxygen partial pressure, the more the particle growth can be promoted. From this point of view, it is necessary to be 0.15 MPa or less in order to grow particles to the same extent as in the examples. Moreover, if it is about 0.015 Mpa, it can be considered that distortion can be recovered to about the level of the embodiment by heat treatment.
Regarding the firing temperature at the time of firing, it can be considered from the examples and past experience that particles of 850 ° C. or higher can be sufficiently grown. In addition, since firing at a high temperature exceeding 1050 ° C. may cause phase separation in terms of crystal structure, firing at 1050 ° C. or less is preferable.
　熱処理における酸素分圧は、実施例１－２２より、酸素を結晶構造中に取り込んで歪みを回復させる観点から、大気（０．０２１ＭＰａ）よりも高い酸素分圧、特に０．０３ＭＰａ以上の酸素分圧で熱処理を行うのが好ましいと考えられる。また、焼成時の雰囲気と比較すると、焼成時より酸素分圧が高いことが好ましいと考えることができる。 The oxygen partial pressure in the heat treatment is higher than that in the atmosphere (0.021 MPa), particularly an oxygen content of 0.03 MPa or more, from the viewpoint of recovering strain by incorporating oxygen into the crystal structure from Example 1-22. It is considered preferable to perform the heat treatment under pressure. In addition, it can be considered that it is preferable that the oxygen partial pressure is higher than that at the time of firing as compared with the atmosphere at the time of firing.
　熱処理における加熱温度は、実施例１０－２２及び比較例４の結果より、酸素を取り込み易い第１次酸素放出温度付近まで、具体的には、第１次酸素放出温度±５０℃まで加熱するのが好ましく、特に第１次酸素放出温度を超えるエネルギーを与えることができる観点から、第１次酸素放出温度～第１次酸素放出温度+５０℃まで、すなわち、第１次酸素放出温度よりも高温側の温度域で熱処理するのが好ましいと考えることができる。
　実施例の結果から、熱処理時の雰囲気の圧力に関しては、０．１０ＭＰａ以上であれば酸素をより一層取込易くなり好ましくなると考えることができるが、現実的に制御可能な雰囲気の圧力は１．５ＭＰａ以下である。 From the results of Examples 10-22 and Comparative Example 4, the heating temperature in the heat treatment is heated to the vicinity of the primary oxygen release temperature at which oxygen can easily be taken in, specifically, to the primary oxygen release temperature ± 50 ° C. In particular, from the viewpoint of providing energy exceeding the primary oxygen release temperature, the primary oxygen release temperature to the primary oxygen release temperature + 50 ° C., that is, higher than the primary oxygen release temperature. It can be considered that heat treatment is preferably performed in the temperature range on the side.
From the results of the examples, regarding the pressure of the atmosphere at the time of heat treatment, it can be considered that oxygen of 0.10 MPa or more is more preferable because it is easier to take in oxygen. 5 MPa or less.
　熱処理後の降温速度に関しては、第１次酸素放出温度近辺で取り込んだ酸素が安定化するため、第１次酸素放出温度近辺を過ぎるまで、すなわち、少なくとも５００℃まではゆっくり１０℃／ｍｉｎ以下の降温速度で冷却するのが好ましいものと考えられる。

  Regarding the temperature lowering rate after the heat treatment, oxygen taken in the vicinity of the primary oxygen release temperature is stabilized, so that it slowly passes 10 ° C./min or less until the temperature close to the primary oxygen release temperature, that is, at least up to 500 ° C. It is considered preferable to cool at a temperature drop rate.

Claims (5)

  1. 　原料を混合する工程、焼成する工程、熱処理する工程を備えたリチウム遷移金属酸化物の製造方法において、酸素分圧０．０１５ＭＰａ～０．１５ＭＰａの雰囲気下にて８５０℃以上で焼成した後、酸素分圧０．０３ＭＰａ以上の雰囲気下にて、第１次酸素放出温度±５０℃の温度で熱処理することを特徴とするリチウム遷移金属酸化物の製造方法。 In a method for producing a lithium transition metal oxide comprising a raw material mixing step, a firing step, and a heat treatment step, after firing at 850 ° C. or higher in an oxygen partial pressure of 0.015 MPa to 0.15 MPa, oxygen A method for producing a lithium transition metal oxide, comprising performing heat treatment at a primary oxygen release temperature of ± 50 ° C in an atmosphere having a partial pressure of 0.03 MPa or more.
  2. 　熱処理時の雰囲気の酸素分圧を０．０８ＭＰａ以上とすることを特徴とする請求項１記載のリチウム遷移金属酸化物の製造方法。 2. The method for producing a lithium transition metal oxide according to claim 1, wherein the oxygen partial pressure of the atmosphere during the heat treatment is 0.08 MPa or more.
  3. 　酸素濃度が８０～１００％のガスを流しながら熱処理することを特徴とする請求項１又は２に記載のリチウム遷移金属酸化物の製造方法。 3. The method for producing a lithium transition metal oxide according to claim 1, wherein the heat treatment is performed while flowing a gas having an oxygen concentration of 80 to 100%.
  4. 　熱処理後、少なくとも５００℃まで１０℃／ｍｉｎ以下の降温速度で冷却することを特徴とする請求項１～３の何れかに記載のリチウム遷移金属酸化物の製造方法。 4. The method for producing a lithium transition metal oxide according to claim 1, wherein after the heat treatment, the lithium transition metal oxide is cooled to at least 500 ° C. at a temperature lowering rate of 10 ° C./min or less.
  5. 　リチウム遷移金属酸化物は、スピネル型リチウム遷移金属酸化物であることを特徴とする請求項１～４の何れかに記載のリチウム遷移金属酸化物の製造方法。

          5. The method for producing a lithium transition metal oxide according to claim 1, wherein the lithium transition metal oxide is a spinel type lithium transition metal oxide.

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