JP4578790B2 - Method for producing lithium-nickel-cobalt-manganese-aluminum-containing composite oxide - Google Patents

Description

  The present invention relates to a method for producing an improved lithium-nickel-cobalt-manganese-aluminum-containing composite oxide suitable as a positive electrode active material for a lithium secondary battery.

In recent years, as devices become portable and cordless, expectations for non-aqueous electrolyte secondary batteries that are small, lightweight, and have high energy density are increasing. As active materials for non-aqueous electrolyte secondary batteries, composite oxides of lithium and transition metals, such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , are known.

  Recently, research on lithium-manganese composite oxides has been actively conducted as a highly safe and inexpensive material, and these materials are used as positive electrode active materials to occlude and release lithium. Development of a high-voltage, high-energy density non-aqueous electrolyte secondary battery by combining with a negative electrode active material such as a carbon material that can be used is underway.

  In general, the positive electrode active material used in non-aqueous electrolyte secondary batteries is composed of a complex oxide in which transition metals such as cobalt, nickel, and manganese are solid-dissolved in lithium, which is the main active material, and the transition used. Depending on the type of metal, electrode characteristics such as electric capacity, reversibility, operating voltage, and safety are different.

For example, a non-aqueous electrolyte secondary that uses an R-3m rhombohedral rock salt layered complex oxide in which cobalt or nickel is dissolved as a positive electrode active material, such as LiCoO ₂ and LiNi _0.8 Co _0.2 O ₂ The battery can achieve a relatively high capacity density of 140 to 160 mAh / g and 180 to 200 mAh / g, respectively, and exhibits good reversibility in a high voltage range of 2.7 to 4.3 V.

  However, when the battery is heated, there is a problem that the battery easily generates heat due to the reaction between the positive electrode active material and the electrolyte solvent during charging, and the cost of the active material is low because cobalt and nickel as raw materials are expensive. There is a problem of getting higher.

In Patent Document 1, in order to improve the characteristics of LiNi _0.8 Co _0.2 O ₂ , for example, a proposal of LiNi _0.75 Co _0.20 Mn _0.05 O ₂ and ammonium as the positive electrode active material intermediate are disclosed. A manufacturing method using a complex has been disclosed. Patent Document 2 proposes a manufacturing method using a chelating agent of a nickel-manganese binary hydroxide raw material for a lithium battery having a specific particle size distribution. A positive electrode active material that satisfies the three requirements of discharge capacity, cycle durability and safety at the same time has not been obtained.

  Patent Document 3 and Patent Document 4 propose using nickel-cobalt-manganese coprecipitated hydroxide as a raw material for a lithium-nickel-cobalt-manganese-containing composite oxide. However, in producing a target lithium-nickel-cobalt-manganese-containing composite oxide by reacting nickel-cobalt-manganese coprecipitated hydroxide with a lithium compound, when lithium hydroxide is used as the lithium compound, lithiation is When lithium hydroxide is used, the lithium-containing composite oxide is obtained when sintering is performed at a temperature of 800 to 1000 ° C. and sintering is excessively performed and uniform lithiation is difficult. The initial charge / discharge efficiency, initial discharge capacity, and charge / discharge cycle durability were inferior.

  In order to avoid this, it was necessary to first calcinate at 500 to 700 ° C., then crush the fired body, and then further calcinate at 800 to 1000 ° C. In addition, lithium hydroxide is not only more expensive than lithium carbonate, but also has a problem of high process costs such as intermediate crushing and multistage firing. On the other hand, when inexpensive lithium carbonate is used as the lithium compound, the lithiation reaction is slow, and it is difficult to industrially produce a lithium-nickel-cobalt-manganese-containing composite oxide having desired battery characteristics. It was.

  Patent Document 5 proposes a method in which a nickel-manganese-cobalt composite hydroxide is fired at 400 ° C. for 5 hours, mixed with lithium hydroxide and then fired. However, since this synthesis method includes a raw material hydroxide firing step, the process is complicated and the manufacturing cost is increased, and there is a difficulty in using lithium hydroxide having a high raw material cost. .

  Patent Document 6 proposes a method in which nickel-manganese-cobalt composite hydroxide is mixed with lithium hydroxide and then fired. As the lithium source, lithium hydroxide is more advantageous than lithium carbonate in terms of particle shape control and crystallinity control. It has also been proposed to oxidize a nickel-manganese-cobalt composite hydroxide, mix it with lithium hydroxide, and fire it. However, each method has a difficulty in using lithium hydroxide having a high raw material cost.

On the other hand, a non-aqueous electrolyte secondary battery using, as an active material, a spinel-type composite oxide composed of LiMn ₂ O _{4 made of} relatively inexpensive manganese as a raw material is a mixture of a positive electrode active material and an electrolyte solvent during charging. Although heat generation of the battery due to the reaction is relatively difficult to generate, there is a problem that the capacity is as low as 100 to 120 mAh / g compared with the above-described cobalt-based and nickel-based active materials, and the charge / discharge cycle durability is poor, and less than 3V There is also a problem of rapidly deteriorating in a low voltage region.

In addition, batteries using orthorhombic Pmnm or monoclinic C2 / m series LiMnO ₂ , LiMn _0.95 Cr _0.05 O _2, LiMn _0.9 Al _0.1 O _2, etc. Although there are examples where the initial capacity is high and the initial capacity is high, there is a problem that the crystal structure is easily changed with the charge / discharge cycle and the cycle durability is insufficient.

JP-A-10-27611 Japanese Patent Laid-Open No. 10-81521 Japanese Patent Laid-Open No. 2002-201028 JP 2003-59490 A JP 2003-86182 A JP 2003-17052 A

  Therefore, the problem of the present invention is that when used as a positive electrode active material of a lithium secondary battery, it can be used in a wide voltage range, has high initial charge / discharge efficiency, high weight capacity density, and high volume capacity density. Provides a new method for producing lithium-nickel-cobalt-manganese-aluminum-containing composite oxide particles by a simple process using an inexpensive lithium source, which provides a battery with excellent high-current discharge characteristics and high safety. There is to do.

The present invention is characterized by comprising a step of dry-mixing nickel-cobalt-manganese composite oxyhydroxide aggregated particles, lithium carbonate particles, aluminum-containing compound particles, and a fluorine-containing compound and firing in an oxygen-containing atmosphere, formula _{Li p Ni x Mn 1-x} -y-z Co y Al z O 2-q F q
(However, 0.98 ≦ p ≦ 1.07, 0.32 ≦ x ≦ 0.42 , 0.1 ≦ y ≦ 0.38, 0 <z ≦ 0.05, 0.001 ≦ q ≦ 0.01 And a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide having an R-3m rhombohedral structure. Provide a method.

The present invention also provides a method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide in which the specific surface area of the nickel-cobalt-manganese composite oxyhydroxide aggregated particles is 4 to 30 m ² / g.

The present invention also relates to lithium-nickel-cobalt-manganese- in which the powder press density of nickel-cobalt-manganese composite oxyhydroxide aggregate particles at a pressure of 0.96 t / cm ² is 2.0 g / cm ³ or more. A method for producing an aluminum-containing composite oxide is provided.

  Further, in the present invention, in the X-ray diffraction using Cu-Kα rays of the nickel-cobalt-manganese composite oxyhydroxide aggregated particles, the half width of the diffraction peak at 2θ of 19 ± 1 ° is 0.3 to 0.5 °. A method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide is provided.

The present invention also provides a method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide having z of 0.001 to 0.02 .

  According to the present invention, the usable voltage range is wide, the charge / discharge cycle durability is high, the capacity is high, and the safety is high. It can be manufactured.

Lithium is produced by the present invention - nickel - cobalt - manganese - aluminum-containing composite oxide is in particulate form, the general formula _{Li p Ni x Mn 1-x} -y-z Co y Al z O 2-q F q ( but 0.98 ≦ p ≦ 1.07, 0.32 ≦ x ≦ 0.42 , 0.1 ≦ y ≦ 0.38, 0 <z ≦ 0.05, 0.001 ≦ q ≦ 0.01, and It is important that the Ni / Mn atomic ratio is 1 ± 0.05 .

  In the above general formula, if p is less than 0.98, the discharge capacity decreases, and if it exceeds 1.07, the discharge capacity decreases, or gas generation inside the battery at the time of charging increases. If x is less than 0.3, it is difficult to obtain a stable R-3m rhombohedral structure, and if it exceeds 0.5, the safety is lowered and thus cannot be adopted. A preferable range of x is 0.32 to 0.42. If y is less than 0.1, the initial charge / discharge efficiency and large current discharge characteristics are undesirably deteriorated. The preferred range for y is 0.23 to 0.35. If z is more than 0.05, the initial discharge capacity is lowered, which is not preferable. In order to express the safety improvement effect, a preferable range of z is 0.001 to 0.02.

  Fluorine is included to improve safety, initial charge / discharge efficiency, and large current discharge characteristics, but it is important that q is 0.05 or less. If q is more than 0.05, the discharge capacity decreases, which is not preferable. A preferred range for q is 0.001 to 0.01. Furthermore, in the present invention, it is preferable that the atomic ratio of Ni and Mn is 1 ± 0.05 because battery characteristics are improved.

  The nickel-cobalt-manganese composite oxyhydroxide aggregated particles as the main raw material in the present invention can be produced, for example, as follows. A nickel-cobalt-manganese salt aqueous solution, an alkali metal hydroxide aqueous solution, and an ammonium ion supplier are continuously or intermittently supplied to the reaction system, and the temperature of the reaction system is within a range of 30 to 70 ° C. The primary particles obtained by advancing the reaction at a substantially constant temperature and maintaining the pH at a substantially constant value in the range of 10 to 13 and folding out the nickel-cobalt-manganese composite hydroxide aggregate. In this method, nickel-cobalt-manganese composite hydroxide aggregated particles in which secondary particles are formed are synthesized and an oxidizing agent is allowed to act on the particles.

  Examples of the nickel-cobalt-manganese salt aqueous solution used for the synthesis of the nickel-cobalt-manganese composite hydroxide aggregated particles include sulfate mixed aqueous solution, nitrate mixed aqueous solution, oxalate mixed aqueous solution, and chloride mixed aqueous solution. . The concentration of the metal salt in the nickel-cobalt-manganese salt mixed aqueous solution supplied to the reaction system is preferably 0.5 to 2.5 mol / L (liter) in total.

  Moreover, preferable examples of the aqueous alkali metal hydroxide solution supplied to the reaction system include an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, and an aqueous lithium hydroxide solution. The concentration of the alkali metal hydroxide aqueous solution is preferably 15 to 35 mol / L.

  The ammonium ion supplier functions to obtain a dense and spherical composite hydroxide by forming a complex salt with nickel or the like. Preferred examples of the ammonium ion supplier include ammonia water, ammonium sulfate aqueous solution, ammonium nitrate salt and the like. The concentration of ammonia or ammonium ions is preferably 2 to 20 mol / L.

  The manufacturing method of the nickel-cobalt-manganese composite hydroxide aggregated particles will be described more specifically. A nickel-cobalt-manganese salt mixed aqueous solution, an alkali metal hydroxide aqueous solution, and an ammonium ion supplier are continuously or intermittently used. The temperature of the slurry in the reaction tank is a constant temperature within the range of 30 to 70 ° C. (variation range: ± 2 ° C., preferably ± 0.5 ° C.). ) To control. If the temperature is lower than 30 ° C., the precipitation reaction is slow, and it becomes difficult to obtain spherical particles. If it exceeds 70 ° C, a large amount of energy is required, which is not preferable. A particularly preferred reaction temperature is a constant temperature within the range of 40-60 ° C.

  Further, the supply rate of the aqueous alkali metal hydroxide solution is controlled so that the pH of the slurry in the reaction tank is a constant pH (variation range: ± 0.1, preferably ± 0.05) within the range of 10 to 13. Hold by. A pH of less than 10 is not preferable because crystals grow too much. A pH exceeding 13 is not preferable because ammonia tends to be volatilized and fine particles increase.

  The residence time in the reaction vessel is preferably 0.5 to 30 hours, particularly preferably 5 to 15 hours. The slurry concentration is preferably 500 to 1200 g / L. If the slurry concentration is less than 500 g / L, the product particle filling property is lowered, which is not preferable. If it exceeds 1200 g / L, stirring of the slurry becomes difficult, which is not preferable. The nickel ion concentration in the slurry is preferably 100 ppm or less, particularly preferably 30 ppm or less. If the nickel ion concentration is too high, the crystal grows too much, which is not preferable.

  By appropriately controlling the temperature, pH, residence time, slurry concentration and ion concentration in the slurry, nickel-cobalt-manganese composite hydroxide aggregated particles having a desired average particle size, particle size distribution, and particle density can be obtained. it can. The reaction in a multi-stage reaction is more dense and spherical with an average particle diameter of 4 to 12 μm, and an intermediate having a preferable particle size distribution can be obtained rather than a single-stage reaction.

  Nickel-cobalt-manganese salt aqueous solution, alkali metal hydroxide aqueous solution, and ammonium ion supplier are supplied to the reaction vessel continuously or intermittently, and nickel-cobalt-manganese composite hydroxide produced by the reaction The slurry containing particles is overflowed or extracted continuously or intermittently from the reaction tank, and this is filtered and washed with water, whereby a powdery (particulate) nickel-cobalt-manganese composite hydroxide is obtained. Part of the product nickel-cobalt-manganese composite hydroxide particles may be returned to the reaction vessel to control the product particle properties.

The nickel-cobalt-manganese composite oxyhydroxide aggregated particles are obtained by allowing an oxidizing agent to act on the nickel-cobalt-manganese composite hydroxide aggregated particles. As a specific example, an oxidizing agent such as dissolved air is allowed to coexist in the slurry of the nickel-cobalt-manganese composite hydroxide synthesis reaction tank, or nickel-cobalt-manganese composite hydroxide is dispersed in an aqueous solution to form a slurry. Then, air, sodium hypochlorite, hydrogen peroxide, potassium persulfate, bromine, etc. are supplied as oxidizers and reacted at 10-60 ° C. for 5-20 hours. The resulting composite oxyhydroxide aggregated particles Is synthesized by washing with filtered water. When sodium hypochlorite, potassium persulfate, bromine or the like is used as an oxidizing agent, an oxidized Ni _x .Mn _{1- xy} .co _y OOH coprecipitate having an average metal valence of about 3 is obtained. can get.

The powder press density of the nickel-cobalt-manganese composite oxyhydroxide aggregated particles is preferably 2.0 g / cm ³ or more. If the powder press density is less than 2.0 g / cm ^3, it is difficult to increase the press density when firing with the lithium salt, which is not preferable. A particularly preferable powder press density is 2.2 g / cm ³ or more. The nickel-cobalt-manganese composite oxyhydroxide aggregated particles are preferably substantially spherical, and the average particle size D50 is preferably 3 to 15 μm. Further, this nickel-cobalt-manganese composite oxyhydroxide aggregated particle has an X-ray diffraction using Cu—Kα ray and the half width of the diffraction peak at 2θ of 19 ± 1 ° is 0.3 to 0.5 °. It is preferable that

  The average valence of the metal in the nickel-cobalt-manganese composite oxyhydroxide aggregated particles is preferably 2.6 or more. If the average valence is less than 2.6, the reaction rate with lithium carbonate decreases, which is not preferable. The average valence is particularly preferably 2.8 to 3.2.

  In the present invention, it is important to use lithium carbonate as a lithium source from the viewpoint of improving the simplicity and operability of the production process and the availability of raw materials. As a form of lithium carbonate, a powder having an average particle diameter of 1 to 50 μm is preferred mainly from the viewpoint of operability.

The powder press density when the lithium-nickel-cobalt-manganese-aluminum-containing composite oxide powder produced in the present invention is press-filled at a pressure of 0.96 t / cm ² is 2.6 g / cm ³ or more. Preferably, according to this, when the active material powder is mixed with a binder and a solvent to form a slurry, the capacity per volume can be increased when the current collector aluminum foil is coated, dried and pressed. . A particularly preferable powder press density is 2.9 g / cm ³ or more. Such a powder press density is achieved by optimizing the particle size distribution of the powder. That is, the particle size distribution is wide, the volume fraction of small particles is 20 to 50%, and the density can be increased by narrowing the particle size distribution of large particles.

  In the lithium-nickel-cobalt-manganese-aluminum-containing composite oxide according to the present invention, when a part of oxygen atoms is substituted with fluorine, the mixture is fired using a mixture in which a fluorine compound is added in addition to lithium carbonate. Examples of the fluorine compound include lithium fluoride, ammonium fluoride, nickel fluoride, and cobalt fluoride. Further, a fluorinating agent such as fluorine chloride, fluorine gas, hydrogen fluoride gas, or nitrogen trifluoride may be reacted.

  The lithium-nickel-cobalt-manganese-aluminum-containing composite oxide according to the present invention includes, as an example, a mixture of the nickel-cobalt-manganese composite oxyhydroxide particles, lithium carbonate particles, and aluminum-containing compound particles in an oxygen-containing atmosphere. Obtained by baking at 800 to 1050 ° C. for 4 to 40 hours. If necessary, the firing may be performed by multi-stage firing.

  The lithium-containing composite oxide for a lithium secondary battery needs to be an active material having an R-3m rhombohedral structure, particularly from the viewpoint of charge / discharge cycle stability. The firing atmosphere must be an oxygen-containing atmosphere. In this way, high performance battery characteristics can be obtained. Although the lithiation reaction itself proceeds in the air, the oxygen concentration is preferably 25% or more for improving battery characteristics, particularly preferably 40% or more.

  The positive electrode mixture is formed by mixing the lithium-containing composite oxide powder of the present invention with a carbon conductive material such as acetylene black, graphite, Ketchen black and a binder. As the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin, or the like is used. The positive electrode active material layer is prepared by coating, drying and press rolling a slurry comprising the lithium-containing composite oxide powder of the present invention, a conductive material, a binder, and a solvent or dispersion medium of the binder on a positive electrode current collector such as an aluminum foil. Is formed on the positive electrode current collector.

  In the lithium battery including the positive electrode active material layer, a carbonate is preferably employed as a solvent for the electrolyte solution. Carbonates can be either cyclic or chain. Examples of cyclic carbonates include propylene carbonate and ethylene carbonate (EC). Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like.

  The carbonate ester may be used alone or in combination of two or more. Moreover, you may mix and use with another solvent. Depending on the material of the negative electrode active material, the combined use of a chain carbonate ester and a cyclic carbonate ester may improve the discharge characteristics, cycle durability, and charge / discharge efficiency. Further, by adding a vinylidene fluoride-hexafluoropropylene copolymer (for example, Akechem Kyner), a vinylidene fluoride-perfluoropropyl vinyl ether copolymer or the like to these organic solvents, and adding the following solute, the gel polymer electrolyte It is good.

As solutes, ClO ₄ −, CF ₃ SO ₃ −, BF ₄ −, PF ₆ −, AsF ₆ −, SbF ₆ −, CF ₃ CO ₂ −, (CF ₃ SO ₂ ) ₂ N— and the like are used as anions. It is preferable to use any one or more of lithium salts. In the above electrolyte solution or polymer electrolyte, an electrolyte composed of a lithium salt is preferably added to the solvent or the solvent-containing polymer at a concentration of 0.2 to 2.0 mol / L. If it deviates from this range, the ionic conductivity is lowered, and the electrical conductivity of the electrolyte is lowered. More preferably, 0.5 to 1.5 mol / L is selected. For the separator, porous polyethylene or porous polypropylene film is used.

  For the negative electrode active material, a material capable of inserting and extracting lithium ions is used. The material for forming the negative electrode active material is not particularly limited. For example, lithium metal, lithium alloy, carbon material, periodic table 14 and group 15 metal group oxide, carbon compound, silicon carbide compound, silicon oxide compound, Examples thereof include titanium sulfide and boron carbide compounds.

  As the carbon material, those obtained by pyrolyzing organic substances under various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, scale-like graphite, and the like can be used. As the oxide, a compound mainly composed of tin oxide can be used. As the negative electrode current collector, a copper foil, a nickel foil, or the like is used.

  The positive electrode and the negative electrode are preferably obtained by kneading an active material with an organic solvent to form a slurry, and applying, drying and pressing the slurry to a metal foil current collector. There are no particular restrictions on the shape of the lithium battery. A sheet shape (so-called film shape), a folded shape, a wound-type bottomed cylindrical shape, a button shape, or the like is selected depending on the application.

Reference Example 1

  Ion exchange water was put into a 2 L (liter) reaction vessel and stirred at 400 rpm while maintaining the internal temperature at 50 ± 1 ° C. A metal sulfate aqueous solution containing 1.5 mol / L nickel sulfate, 1.5 mol / L manganese sulfate, and 1.5 mol / L cobalt sulfate was added to 0.4 L / hr, and 1.5 mol / L manganese sulfate. While supplying a mol / L ammonium sulfate aqueous solution at a rate of 0.03 L / hr simultaneously, an 18 mol / L sodium hydroxide aqueous solution is continuously supplied so that the pH in the reaction vessel is maintained at 10.85 ± 0.05. did. The mother liquor in the reaction tank was periodically extracted, and the slurry was concentrated until the final slurry concentration was about 720 g / L. After reaching the target slurry concentration, after aging at 50 ° C. for 5 hours, filtration and washing were repeated to obtain nickel-manganese-cobalt coprecipitated hydroxide aggregated particles having a spherical shape and an average particle size of 9 μm.

To 60 parts by weight of an aqueous solution containing 0.071 mol / L potassium peroxodisulfate and 1 mol / L sodium hydroxide, 1 part by weight of this nickel-manganese-cobalt coprecipitated hydroxide aggregated particle was added. The mixture was mixed at a ratio and stirred at 15 ° C. for 8 hours. After the reaction, filtration, washing with water were repeated, and drying was performed to obtain nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder Ni _1/3 Mn _1/3 Co _1/3 OOH.

About this powder, using an X-ray diffractometer (RINT2100 type, manufactured by Rigaku Corporation), Cu-Kα rays were used, and powder X at 40 KV-40 mA, sampling interval 0.020 °, and Fourier transform integration time 2.0 seconds A diffraction spectrum similar to CoOOH was confirmed by the XRD diffraction spectrum obtained in the line diffraction. The half width of the diffraction peak at 2θ around 19 ° was 0.400 °. Further, nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder was dissolved in a 20 wt% sulfuric acid aqueous solution in the presence of Fe ²⁺ , and then titrated with a 0.1 mol / L KMn ₂ O ₇ solution. From the results, it was confirmed that the obtained nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder had an average valence of 2.99 and a composition mainly composed of oxyhydroxide.

The average particle diameter of this nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder was 9 μm. Moreover, the specific surface area by BET method was 13.3 m < ² > / g. From the SEM photograph of this powder, it was found that many scaly primary particles of 0.1 to 0.5 μm aggregated to form secondary particles. Moreover, when this nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder was hydraulically pressed at a pressure of 0.96 t / cm ² and the powder press density was determined from the volume and weight, it was found to be 2.18 g / cm ^3. Met.

This nickel-manganese-cobalt coprecipitated oxyhydroxide aggregated particle powder, lithium carbonate powder, and aluminum hydroxide powder are mixed, calcined and pulverized at 900 ° C. for 10 hours in an atmosphere having an oxygen concentration of 40 volume%, and an average particle size of 9 A composite oxide powder of 0.5 μm was synthesized. As a result of elemental analysis of the composite oxide, this composite oxide was Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.99 Al _0.01 O ₂ .

As a result of measuring X-ray diffraction analysis of this powder by Cu-Kα under the same conditions as the X-ray diffraction of the coprecipitated oxyhydroxide, it was an R-3m rhombohedral layered rock salt structure and 2θ was 65 ± 0.00. It was found that the half-value width of the diffraction peak of the 5 ° (110) plane was 0.248 °, and the half-value width of the diffraction peak of the (003) plane having 2θ of 19 ± 1 ° was 0.170 °. The specific surface area was 0.50 m ² / g. The a-axis lattice constant was 2.862 Å, and the c-axis lattice constant was 14.239 Å. About the obtained complex oxide powder, the compression fracture strength was measured using the micro compression tester MCT-W500 of Shimadzu Corporation. That is, a test load was set to 100 mN, a load speed of 3.874 mN / sec, a flat type indenter with a diameter of 50 μm was used to measure 10 arbitrary particles having a known particle size, and the fracture strength was found to be 102 MPa. .

Further, this Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.99 Al _0.01 O ₂ powder was hydraulically pressed at a pressure of 0.96 t / cm ² to determine the volume and weight. The powder press density was determined to be 2.92 g / cm ³ . This Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.99 Al _0.01 O ₂ powder, acetylene black and polyvinylidene fluoride in a weight ratio of 83/10/7 are N- A ball mill was mixed with methylpyrrolidone to make a slurry. This slurry was applied onto an aluminum foil positive electrode current collector having a thickness of 20 μm and dried at 150 ° C. to remove N-methylpyrrolidone. Thereafter, roll press rolling was performed to obtain a positive electrode body. 25 μm thick porous polyethylene is used for the separator, 300 μm thick metal lithium foil is used for the negative electrode, nickel foil is used for the negative electrode current collector, and 1M LiPF ₆ / EC + DEC (1: 1) is used for the electrolyte. Was used to assemble the coin cell 2030 type in an argon glove box.

  Then, under a temperature atmosphere of 25 ° C., a constant current charge is performed up to 4.3 V at 10 mA per 1 g of the positive electrode active material, a constant current discharge is performed up to 2.7 V at 10 mA per 1 g of the positive electrode active material, and a charge / discharge test is performed. A charge / discharge test was conducted at a discharge capacity and charge / discharge efficiency at the time of charge / discharge of 150 mA / g to obtain a discharge capacity. Also, for battery safety evaluation under a temperature atmosphere of 25 ° C., the cell after 4.3 V charging was disassembled, and the positive electrode was put together with ethylene carbonate in a sealed container as a sample, using a differential scanning calorimeter, The exothermic peak temperature when the temperature was raised was determined. The initial charge / discharge efficiency at 10 mA / g was 91.8%, the initial discharge capacity was 163 mAh / g, the initial discharge capacity at 150 mA / g was 143 mAh / g, and the exothermic peak temperature was 272 ° C.

Reference Example 2

In the above-mentioned Reference Example 1, except for changing the addition amount of aluminum _{hydroxide, Li 1.04 (Ni 1/3 Mn 1/3} Co 1/3) in the same manner as in Reference Example 1 _0.95 Al _0.05 O ₂ was synthesized. As a result of X-ray diffraction analysis of this powder by Cu-Kα, it was found to be an R-3m rhombohedral layered rock salt structure. The half width of the diffraction peak of the (110) plane with 2θ of 65 ± 0.5 ° is 0.248 °, and the half width of the diffraction peak of the (003) plane with 2θ of 19 ± 1 ° is 0.170 °. I found out. The specific surface area was 0.50 m ² / g. The a-axis lattice constant was 2.862 Å, and the c-axis lattice constant was 14.239 Å. The average particle size was 9.7 μm. The fracture strength measured in the same manner as in Reference Example 1 was 82 MPa. In addition, this Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.95 Al _0.05 O ₂ powder was hydraulically pressed at a pressure of 0.96 t / cm ² to determine the volume and weight. The powder press density was determined to be 2.98 g / cm ³ . Using this Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.95 Al _0.05 O ₂ powder, battery performance and safety were evaluated in the same manner as in Reference Example 1 above. As a result, the initial charge / discharge efficiency at 10 mA / g was 92,3%, the initial discharge capacity was 159 mAh / g, the initial discharge capacity at 150 mA / g was 139 mAh / g, and the exothermic peak temperature was 276 ° C.

In the above-mentioned Reference Example 1, except that in addition to the aluminum hydroxide was added lithium fluoride powder in the same manner as in Reference Example _{1 Li 1.04 (Ni 1/3 Mn 1/3} Co 1/3) _0.99 Al _0.01 O _1.998 F _0.002 was synthesized. As a result of X-ray diffraction analysis of this powder by Cu-Kα, it was found to be an R-3m rhombohedral layered rock salt structure. The half-value width of the (110) plane diffraction peak with 2θ of 65 ± 0.5 ° is 0.193 °, and the half-value width of the (003) plane with 2θ of 19 ± 1 ° is 0.139 °. I found out. The specific surface area was 0.68 m ² / g. The lattice constant of the a axis was 2.863 Å, and the lattice constant of the c axis was 14.241 Å. The average particle size was 9.6 μm. Also, this Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.99 Al _0.01 O _1.998 F _0.002 powder was hydraulically pressed at a pressure of 0.96 t / cm ^2. The press density obtained from the volume and weight was 2.93 g / cm ³ . Using this Li _1.04 (Ni _1/3 Mn _1/3 Co _1/3 ) _0.99 Al _0.01 O _1.998 F _0.002 powder, battery performance was obtained in the same manner as in Reference Example 1 above. As a result, the initial charge / discharge efficiency at 10 mA / g was 93.0%, the initial discharge capacity was 165 mAh / g, the initial discharge capacity at 150 mA / g was 149 mAh / g, and the exothermic peak temperature was 273 ° C. Met.

In the above Reference Example 1, except that aluminum fluoride was added instead of aluminum hydroxide, a positive electrode active material powder was synthesized in the same manner as in the above Reference Example 1, and its powder properties and battery performance were determined. The average particle diameter of the positive electrode active material powder was 11.1 μm. This composite oxide was Li _1.04 (Ni _1/3 Co _1/3 Mn _1/3 ) _0.995 Al _0.005 O _1.99 F _0.01 . As a result of X-ray diffraction analysis of Cu—Kα of this powder, the half-value width of the diffraction peak on the (110) plane having an R-3m rhombohedral layered rock salt structure and 2θ of 65 ± 0.5 ° was 0.205. It was found that the half width of the diffraction peak of the (003) plane with 2θ of 19 ± 1 ° was 0.137 °. The specific surface area was 0.52 m ² / g. The powder breath density was determined to be 2.93 g / cm ³ . The lattice constant of the a axis was 2.863８６, and the lattice constant of the c axis was 14.250Å. The fracture strength of this composite oxide powder was 111 MPa. The initial charge and discharge efficiency at 10 mA / g was 92.8%, the initial discharge capacity was 164 mAh / g, the initial discharge capacity at 150 mA / g was 149 mAh / g, and the exothermic peak temperature was 282 ° C.

Comparative Example 1

In the above Reference Example 1, except that the aluminum hydroxide powder was not added, a positive electrode active material powder was synthesized in the same manner as in the above Reference Example 1, and the powder properties and battery performance were determined. The average particle diameter of the positive electrode active material powder was 9.5 μm. This composite oxide was Li _1.04 Ni _1/3 Mn _1/3 Co _1/3 O ₂ . As a result of X-ray diffraction analysis of this powder by Cu-Kα, the half-value width of the diffraction peak of the (110) plane having an R-3m rhombohedral layered rock salt structure and 2θ of 65 ± 0.5 ° is 0.290. It was found that the half-value width of the diffraction peak on the (003) plane with 2θ of 19 ± 1 ° was 0.201 °. The specific surface area was 0.45 m ² / g. The powder press density was determined to be 2.76 g / cm ³ . The a-axis lattice constant was 2.862８６, and the c-axis lattice constant was 14.240Å. The fracture strength of the particles of this composite oxide powder was 105 MPa. The initial charge / discharge efficiency at 10 mA / g was 90.4%, the initial discharge capacity was 162 mAh / g, the initial discharge capacity at 150 mA / g was 143 mAh / g, and the exothermic peak temperature was 239 ° C.

  According to the present invention, when used as a positive electrode active material, it can be used in a wide voltage range, the initial charge / discharge efficiency, the weight capacity density and the volume capacity density are all high, and it has excellent large current discharge characteristics, A lithium secondary battery excellent in safety and availability can be realized.

Claims (5)

Characterized in that it includes a step of dry mixing nickel-cobalt-manganese composite oxyhydroxide aggregated particles, lithium carbonate particles, aluminum-containing compound particles and fluorine-containing compound and firing in an oxygen-containing atmosphere.
Formula _{Li p Ni x Mn 1-x} -y-z Co y Al z O 2-q F q
(However, 0.98 ≦ p ≦ 1.07, 0.32 ≦ x ≦ 0.42 , 0.1 ≦ y ≦ 0.38, 0 <z ≦ 0.05, 0.001 ≦ q ≦ 0.01 And a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide having an R-3m rhombohedral structure. Method. ^{2. The} method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide according to claim 1, wherein the specific surface area of the nickel-cobalt-manganese composite oxyhydroxide aggregated particles is 4 to 30 m ² / g. Nickel - cobalt - manganese complex lithium powder pressing density at a pressure of 0.96t / cm ² of oxyhydroxide agglomerated particles according to claim 1 or 2 is 2.0 g / cm ³ or more - nickel - cobalt -Manufacturing method of manganese-aluminum-containing composite oxide.   2. The half width of a diffraction peak at 2θ of 19 ± 1 ° in an X-ray diffraction using Cu—Kα rays of nickel-cobalt-manganese composite oxyhydroxide aggregated particles is 0.3 to 0.5 °. 4. The method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide according to any one of items 1 to 3.   The method for producing a lithium-nickel-cobalt-manganese-aluminum-containing composite oxide according to any one of claims 1 to 4, wherein z is 0.001 to 0.02.