JP5547223B2 - Method for producing lithium nickel manganese cobalt composite oxide - Google Patents

Description

  The present invention relates to a method for producing a lithium nickel manganese cobalt composite oxide.

  Conventionally, lithium cobaltate has been used as a positive electrode active material for lithium secondary batteries. However, since cobalt is a rare metal, a lithium nickel manganese cobalt composite oxide having a low cobalt content has been developed.

  Examples of a method for producing a lithium nickel manganese cobalt composite oxide include, for example, Japanese Patent Application Laid-Open No. 2003-34538 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2003-183022 (Patent Document 2). A slurry is prepared by mixing a manganese compound and a cobalt compound, and the resulting slurry is wet-pulverized to obtain a slurry having an average particle size of 0.30 μm in solid content. A method for producing a lithium nickel manganese cobalt composite oxide by spray drying and then firing the obtained granulated product is disclosed.

JP 2003-34538 A (Example) JP 2003-183022 A (Example)

  In recent years, the demand for lithium secondary batteries such as mobile phones, digital cameras, portable game machines, and electric vehicles has been increasing. These devices can be recharged and maintain their capacity from the viewpoint of long-term continuous use. A high rate is required.

  However, the manufacturing method of Patent Document 1 has a problem in that a lithium nickel manganese cobalt composite oxide that satisfies the recent demand for a high capacity retention rate cannot be obtained.

  Accordingly, an object of the present invention is to provide a method for producing a lithium nickel manganese cobalt composite oxide capable of increasing the capacity retention rate of a lithium secondary battery.

As a result of intensive studies in view of the above circumstances, the inventors of the present invention have obtained, as a result, at least nickel compound particles, manganese compound particles, and cobalt compound particles in a dispersion medium. Is pulverized by wet pulverization until 0.9 to 1.6 μm, and then spray-dried to obtain a spray-dried product containing a nickel compound, a manganese compound and a cobalt compound having a BET specific surface area of 80 to 100 m ² / g. In addition, the inventors have found that a lithium nickel manganese cobalt composite oxide capable of increasing the capacity retention rate of a lithium secondary battery can be obtained by mixing and firing a lithium compound, and the present invention has been completed. .

That is, the present invention provides the following general formula (1):
_{Li x Ni 1-y-z} Mn y Co z O 2 (1)
(Wherein x represents 0.98 ≦ x ≦ 1.2, y represents 0 <y ≦ 0.5, and z represents 0 <z ≦ 0.5, where y + z <1.0). A method for producing a lithium nickel manganese cobalt composite oxide represented by:
Spray-drying a slurry containing nickel compound particles, manganese compound particles and cobalt compound particles as the spray-drying raw material particles and having an average particle size of the spray-drying raw material particles of 0.9 to 1.6 μm, The BET specific surface area is 80 to 100 m ² / g , and the following formula (2):
Maintenance ratio (%) of average particle diameter of spray-dried product before and after pulverization test = (Y1 / X1) × 100 (2)
(In Formula (2), X1 shows the average particle diameter of the spray-dried material before a crushing test. Y1 shows the average particle diameter of the spray-dried material after a crushing test.)
A spray-drying step of obtaining a spray-dried product having an average particle size maintenance rate of 75 to 97% before and after the pulverization test of the spray-dried product obtained by
A firing raw material mixing step of mixing the spray-dried product and a lithium compound to obtain a firing raw material mixture;
A firing step of firing the firing raw material mixture to obtain a lithium nickel manganese cobalt composite oxide;
A method for producing a lithium nickel manganese cobalt composite oxide characterized by comprising:

  Furthermore, the present invention further includes one or more of compounds having a Me element, including a Me element selected from elements having an atomic number of 11 or more other than Ni, Mn, and Co, the spray drying step, or the The present invention provides a method for producing a lithium nickel manganese cobalt composite oxide, which is added to any or both of the firing raw material mixing steps.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the lithium nickel manganese cobalt complex oxide which can make the capacity | capacitance maintenance factor of a lithium secondary battery high can be provided.

The method for producing the lithium nickel manganese cobalt composite oxide of the present invention has the following general formula (1):
_{Li x Ni 1-y-z} Mn y Co z O 2 (1)
(Wherein x represents 0.98 ≦ x ≦ 1.2, y represents 0 <y ≦ 0.5, and z represents 0 <z ≦ 0.5, where y + z <1.0). A method for producing a lithium nickel manganese cobalt composite oxide represented by:
Spray-dried slurry containing nickel compound particles, manganese compound particles and cobalt compound particles as the spray-drying raw material particles, and having an average particle size of the spray-drying raw material particles of 0.9 to 1.6 μm, and BET A spray drying step for obtaining a spray dried product having a specific surface area of 80 to 100 m ² / g;
A firing raw material mixing step of mixing the spray-dried product and a lithium compound to obtain a firing raw material mixture;
A firing step of firing the firing raw material mixture to obtain a lithium nickel manganese cobalt composite oxide;
It is characterized by having.

The lithium nickel manganese cobalt composite oxide obtained by the method for producing a lithium nickel manganese cobalt composite oxide of the present invention has the following general formula (1):
_{Li x Ni 1-y-z} Mn y Co z O 2 (1)
(Wherein x represents 0.98 ≦ x ≦ 1.2, y represents 0 <y ≦ 0.5, and z represents 0 <z ≦ 0.5, where y + z <1.0). It is a lithium nickel manganese cobalt composite oxide represented.
And the manufacturing method of the lithium nickel manganese cobalt complex oxide of this invention has a spray-drying process, a baking raw material mixing process, and a baking process.

  The spray drying step according to the method for producing the lithium nickel manganese cobalt composite oxide of the present invention includes spray drying a slurry containing nickel compound particles, manganese compound particles and cobalt compound particles as spray drying raw material particles, and spray drying. This is a process for obtaining a product.

  In the spray drying step, the slurry to be spray dried contains nickel compound particles, manganese compound particles, and cobalt compound particles as spray drying raw material particles.

The nickel compound according to the spray drying process is a compound that becomes a nickel source of the lithium nickel manganese cobalt composite oxide. The nickel compound is not particularly limited, and examples thereof include nickel oxides and hydroxides such as Ni (OH) ₂ , NiO, and NiOOH; NiCO ₃ , Ni (NO ₃ ) ₂ , NiSO ₄ , NiSO ₄ , NiC _2. Inorganic salts of nickel such as O ₄ ; organic nickel compounds such as fatty acid nickel and the like. Among these, as the nickel compound, Ni (OH) ₂ is preferable in that it can be obtained as an industrial raw material at low cost and has high reactivity. The nickel compound may be a single type or a combination of two or more types. The nickel compound is preferably a compound that is hardly soluble in the dispersion medium.

The manganese compound according to the spray drying process is a compound that becomes a manganese source of the lithium nickel manganese cobalt composite oxide. The manganese compound is not particularly limited, for _{example, Mn (OH) 2, Mn} 3 O 4, Mn 2 O 3, MnO 2, MnOOH such oxides and hydroxides of _manganese; MnCO _3, Mn (NO 3 ) ₂ , inorganic salts of manganese such as MnSO ₄ ; organic manganese compounds such as manganese dicarboxylate, manganese citrate, and manganese fatty acid. Among these, as the manganese compound, MnCO ₃ is preferable in terms of high reactivity. The manganese compound may be used alone or in combination of two or more. The manganese compound is preferably a compound that is hardly soluble in the dispersion medium.

The cobalt compound which concerns on a spray-drying process is a compound used as the cobalt source of lithium nickel manganese cobalt complex oxide. The cobalt compound is not particularly limited, and examples thereof include cobalt oxides and hydroxides such as CoOOH, Co (OH) ₂ , CoO, Co ₂ O ₃ , and Co ₃ O ₄ ; Co (NO ₃ ) ₂ , Co Inorganic salts of cobalt such as (SO ₄ ) ₂ ; organic cobalt compounds such as Co (OAc) _{2 and the} like. Of these, as the cobalt compound, CoOOH is preferable in that it does not generate harmful gases such as NOx and SOx during the firing step, and more preferable in terms of being industrially available at low cost and high reactivity. . The cobalt compound may be a single type or a combination of two or more types. The cobalt compound is preferably a compound that is hardly soluble in the dispersion medium.

  The nickel compound, manganese compound, and cobalt compound contained in the spray-dried raw material may have any production history, but those having as little impurity content as possible are preferable.

  In the spray-drying process, in the slurry to be spray-dried, spray-drying raw material particles containing nickel compound particles, manganese compound particles, and cobalt compound particles are dispersed in a dispersion medium. Examples of the dispersion medium include water and a mixed dispersion medium of water and a water-soluble organic solvent.

  In the spray drying step, the content ratio of the nickel compound, manganese compound, and cobalt compound in the slurry to be spray dried is appropriately selected depending on what composition ratio of the lithium nickel manganese cobalt composite oxide is manufactured. In molar ratio in terms of atom, Ni / (Ni + Mn + Co) is 0.5 or more and less than 1, preferably 0.5 or more and 0.95 or less, and Mn / (Ni + Mn + Co) is more than 0 and 0.5 or less, preferably more than 0. 0.4 or less, Co / (Ni + Mn + Co) is larger than 0 and 0.5 or smaller, preferably larger than 0 and 0.4 or smaller.

  In the spray drying step, the concentration of the spray-dried raw material particles in the slurry to be spray-dried is a mass ratio of the spray-dried raw material particles to the whole slurry, preferably 5 to 60% by weight, particularly preferably 10 to 50% by weight, Preferably it is 15-40 mass%.

  In the spray-drying step, the slurry to be spray-dried may further contain additives such as a dispersant such as Poise 2100 (manufactured by Kao Corporation) and SN5468 (manufactured by San Nopco).

In the spray drying step, the average particle diameter of the spray dried raw material particles in the slurry to be spray dried is 0.9 to 1.6 μm, preferably 1.0 to 1.5 μm, particularly preferably 1.1 to 1.4 μm. It is. When the average particle diameter of the spray-dried raw material particles in the slurry is in the above range, the capacity retention rate of the lithium secondary battery is increased. The average particle size of the spray-dried raw material particles is the average particle size of the mixture of nickel compound particles, manganese compound particles and cobalt compound particles when the slurry contains nickel compound particles, manganese compound particles and cobalt compound particles. Point to.
In addition, when a compound having a Me element described later is added to the slurry to be spray-dried in the spray-drying step, the average particle size of the spray-drying raw material particles in the slurry is nickel compound particles, manganese compound particles, cobalt compounds The average particle diameter of the compound particle which has particle | grains and Me element is shown.

  The slurry to be spray-dried is obtained by wet-grinding nickel compound particles, manganese compound particles, and cobalt compound particles in a dispersion medium. At this time, the average particle diameter of the spray-dried raw material particles in the slurry obtained by the laser diffraction / scattering method is 0.9 to 1.6 μm, preferably 1.0 to 1.5 μm, particularly preferably 1.1 to 1. Perform wet milling to 4 μm. In the wet pulverization, the average particle size of the spray-dried raw material particles in the slurry can be controlled by appropriately selecting the wet pulverization conditions.

  As a device for performing wet pulverization, it is preferable to use a media mill because it becomes easy to control the average particle diameter of spray-dried raw material particles in the slurry to be in the above range. , Ball mill, paint shaker, attritor, sand mill and the like.

  For example, when wet pulverization is performed using a bead mill, the wet pulverization conditions such as the concentration of spray-dried raw material particles, the presence / absence and concentration of a dispersant, the bead particle size, the mill frequency, the number of wet pulverization treatments, the input speed, etc. By appropriately selecting, the average particle size of the spray-dried raw material particles in the slurry obtained by wet pulverization, that is, the slurry to be spray-dried is adjusted.

  In the spray drying step, a spray-dried product is obtained by spray-drying the slurry adjusted so that the spray-drying raw material particles have a predetermined particle property.

  In the spray drying process, the method of spray drying the slurry is not particularly limited as long as it is a method capable of spraying the droplets of the slurry into a high-temperature gas and evaporating the dispersion medium in the slurry. The spray drying method is used. For example, while supplying the drying gas into the spray drying apparatus, while maintaining the temperature in the apparatus at the drying temperature, from the spray nozzles such as the rotary disk nozzle, the two-fluid and the four-fluid nozzle, The method of spraying the droplet of a slurry is mentioned.

  In the spray drying step, the spray drying temperature when the slurry is spray dried is preferably 100 to 400 ° C, particularly preferably 200 to 400 ° C, and further preferably 220 to 350 ° C. If the spray drying temperature when the slurry is spray-dried is lower than the above range, the agglomeration property of the spray-dried product is lowered, and it is difficult to obtain an agglomerate having an appropriate particle strength, which will be described later. On the other hand, when the spray drying temperature is higher than the above range, the porosity (pore volume) tends to be small and the reactivity with the lithium compound tends to be low.

  In the spray-drying step, the size of the slurry droplets when the slurry is sprayed is preferably such that the diameter of the spray-dried product is 5 to 50 μm, particularly preferably the diameter of the spray-dried product is 7 to 30 μm. The diameter of the slurry droplets is selected.

  The spray-dried product obtained by performing the spray-drying step is a granulated product containing nickel compound particles, manganese compound particles and cobalt compound particles, and is an aggregate of these compounds.

The BET specific surface area of the spray-dried product obtained by performing the spray-drying step is 80 to 100 m ² / g, preferably 82 to 95 m ² / g. When the BET specific surface area of the spray-dried product is in the above range, the capacity retention rate of the lithium secondary battery is increased. On the other hand, when the BET specific surface area of the spray-dried product is smaller than the above range, the physical adsorption force is weakened, and it is difficult to obtain an aggregate having an appropriate particle strength, which will be described later. When it becomes a dried product and the BET specific surface area of the spray-dried product is larger than the above range, a lithium nickel manganese cobalt composite oxide having low cycle characteristics is obtained. In addition, the BET specific surface area of a spray-dried material can be made into the said range by selecting suitably the conditions in the grinding | pulverization process of a spray-drying raw material.

  The average particle diameter of the spray-dried product is an average particle diameter determined by a laser diffraction / scattering method, and is preferably 5 to 50 μm, particularly preferably 7 to 30 μm. When the average particle size of the spray-dried product is in the above range, the stability of the coating process on the electrode is increased and the generation of fine particles is suppressed when a battery is produced with the finally obtained lithium nickel manganese cobalt composite oxide. As a result, the safety of the battery is improved.

The spray-dried product obtained by performing the spray-drying process is an aggregate containing moderately pulverized nickel compound particles, manganese compound particles, and cobalt compound particles, but the physical properties must be an aggregate with appropriate particle strength. For example, it is preferable in terms of controlling the average particle size of the aggregate. Here, when the spray-dried product is an aggregate having an appropriate particle strength, the maintenance ratio of the average particle diameter before and after the pulverization test of the spray-dried product obtained by the following formula (2) is 75. -97%, preferably 80-95%.
Maintenance ratio (%) of average particle diameter of spray-dried product before and after pulverization test = (Y1 / X1) × 100 (2)
(In Formula (2), X1 shows the average particle diameter of the spray-dried material before a crushing test. Y1 shows the average particle diameter of the spray-dried material after a crushing test.)
In Formula (2), X1 is an average particle diameter before the pulverization test of the spray-dried product, and Y1 is an average particle size after the pulverization test of the spray-dried product. In addition, the average particle diameter of the spray dried product of X1 and Y1 in Formula (2) is an average particle diameter calculated | required by the laser diffraction / scattering method. The pulverization test method is a method of pulverizing the spray-dried product for 60 seconds using a household mixer (MX-X4, manufactured by Matsushita Electric Industrial Co., Ltd.) as a mechanical mixing means. The higher the maintenance ratio of the average particle size of the spray-dried product before and after the pulverization test, the more possible the mixing with the lithium compound in the state of maintaining the shape of the spray-dried product (aggregate) in the firing raw material mixing step. However, the present inventors have found that it is preferable to control the average particle diameter by setting the maintenance ratio of the average particle diameter of the spray-dried product before and after the pulverization test within a specific range.

  The firing raw material mixing step is a step of obtaining a fired raw material mixture by mixing the spray-dried product and the lithium compound.

The lithium compound according to the firing raw material mixing step is a compound that becomes a lithium source of the lithium nickel manganese cobalt composite oxide. The lithium compound is not particularly limited, and examples thereof include lithium oxides or hydroxides such as LiOH.H ₂ O and Li ₂ O; and lithium inorganic salts such as Li ₂ CO ₃ , LiNO ₃ , and Li ₂ SO _4. An organic lithium compound such as alkyllithium and lithium acetate; Among them, the lithium compound, LiOH _· H 2 O, the _Li 2 CO ₃ preferred.

  The average particle size of the lithium compound is preferably 1 to 100 μm, particularly preferably 5 to 80 μm. When the average particle size of the lithium compound is in the above range, uniform mixing with the spray-dried product is possible, and the reactivity is improved.

  When the spray-dried product is a spray-dried product containing nickel compound particles, manganese compound particles, and cobalt compound particles, Li / (Ni + Mn + Co) is set to a molar ratio in terms of an atom of 0. The amount is 98 to 1.20, preferably 1.00 to 1.10, particularly preferably 1.01 to 1.05.

  The spray-dried product obtained by performing the spray-drying step is an aggregate in which particles are aggregated, and as described above, the average particle size of the spray-dried raw material particles in the slurry is 0.9 to 1.6 μm, preferably 1. When the thickness is from 0 to 1.5 μm, particularly preferably from 1.1 to 1.4 μm, it becomes easy to form an aggregate having an appropriate particle strength. In the firing raw material mixing step, a mixing process can be performed by mechanical mixing means. In addition, since the spray-dried product according to the firing raw material mixing step is excellent in reactivity with the lithium compound, the remaining lithium carbonate or the remaining amount of lithium carbonate and lithium hydroxide that causes battery swelling is low. can get.

  As a method of mixing the spray-dried product and the lithium compound in the firing raw material mixing step, for example, using a mechanical stirring means such as a Henschel mixer, a Nauter mixer, a ribbon blender, or a V-type mixer, The method of mixing with a lithium compound is mentioned.

In the firing raw material mixing step, the maintenance ratio of the average particle size of the spray-dried product before and after the mixing treatment obtained by the following formula (3) in terms of controlling the physical properties, for example, the average particle size of the aggregate. Is preferably 75 to 97%, particularly preferably 80 to 95%.
Maintenance ratio (%) of average particle diameter of spray-dried product before and after mixing treatment = (Y2 / X2) × 100 (3)
(In Formula (3), X2 represents the average particle size of the spray-dried product before the mixing treatment with the spray-dried product and the lithium compound. Y2 is the spray-drying after the mixing treatment with the spray-dried product and the lithium compound. Indicates the average particle size of the product.)
In formula (3), X2 is the average particle size of the spray-dried product mixed with the lithium compound in the firing raw material mixing step, and the average particle size of the spray-dried product before being mixed with the lithium compound in the firing material mixing step Is the diameter. Moreover, in Formula (3), Y2 is an average particle diameter of the spray-dried material in the baking raw material mixture after performing the mixing process of a lithium compound and a spray-dried material at a baking raw material mixing process. In addition, the value of Y2 is the average particle diameter of the spray-dried product after treating the spray-dried product alone under the same conditions as the mixing conditions for mixing the spray-dried product and the lithium compound in the firing raw material mixing step. It is a value obtained by obtaining. Moreover, the average particle diameter of the spray-dried product of X2 and Y2 in the formula (3) is an average particle diameter obtained by a laser diffraction / scattering method.
In addition, when the compound having the Me element described later is added together with the lithium compound in the firing raw material mixing step, X2 in the formula (3) is mixed with the lithium compound and the compound having the Me element in the firing raw material mixing step. The average particle size of the spray-dried product before being mixed with the lithium compound and the compound having the Me element in the firing raw material mixing step. Moreover, in Formula (3), Y2 is an average particle | grain of the spray dried material in the baking raw material mixture after performing the mixing process with the compound which has a lithium compound and Me element, and a spray dried material at a baking raw material mixing process. Indicates the diameter.

  The firing step is a step of firing the firing raw material mixture to obtain a lithium nickel manganese cobalt composite oxide.

  In the firing step, the firing temperature when firing the firing raw material mixture is 750 to 1000 ° C, preferably 870 to 950 ° C. When the firing temperature of the firing raw material mixture is in the above range, a single-phase lithium nickel manganese cobalt composite oxide is obtained in the X-ray diffraction analysis, and the capacity retention rate of the lithium secondary battery is high. The discharge capacity of the secondary battery is increased. The firing time when firing the firing raw material mixture is 1 to 30 hours, preferably 3 to 20 hours. The firing atmosphere when firing the firing raw material mixture is not particularly limited, and examples include an air atmosphere or an oxygen atmosphere.

  And after baking a baking raw material mixture by a baking process, when it cools suitably and it crushes as needed, lithium nickel manganese cobalt complex oxide will be obtained.

  In addition, the present invention aims to further improve the safety and cycle performance of a lithium secondary battery, and further includes a Me element containing a Me element selected from elements having an atomic number of 11 or more other than Ni, Mn, and Co. 1 type or 2 types or more of the compound which has can be added to either the process of the said spray-drying process or the said baking raw material mixing process, or both processes.

The Me element related to the compound having the Me element is an element having an atomic number of 11 or more other than Ni, Mn, and Co, and preferably B, Mg, Ca, Al, Si, P, Ti, Fe, Ga, Zr. , Nb, Mo, Sn, W and Bi, or one or more elements.
Examples of the compound having the Me element include oxides, hydroxides, oxyhydroxides, carbonates, nitrates, sulfates, phosphates, and organic acid salts of these Me elements. Used in seeds and above.
Further, the compound having the Me element is not limited in the production history, but is preferably one having as little impurity content as possible.

  The addition amount of the compound having the Me element in the spray drying step and / or the firing raw material mixing step is an atomic conversion molar ratio, and Me / (Ni + Mn + Co) is 0.0005 to 0.02, preferably 0.001 to 0.00. The amount is 01.

The compound having the Me element added in the spray drying step is a compound that is hardly soluble in the dispersion medium, and the addition of the compound having the Me element is performed in the same manner as other manufacturing raw materials into the slurry to be spray dried. The BET specific surface area of the obtained spray-dried product is 80-100 m ² / g, preferably 82-95 m ² / g, and the spray-dried product represented by the above formula (2) is added. The average particle size retention rate before and after the pulverization test is preferable from the viewpoint of easily obtaining the above-mentioned range.

  The compound having the Me element added in the firing raw material mixing step may be either a compound that is hardly soluble in the dispersion medium or a compound that is soluble in the dispersion medium. Moreover, the average particle diameter of the compound which has Me element added at a baking raw material mixing process becomes like this. Preferably it is 0.1-50 micrometers, Most preferably, it is 0.5-10 micrometers. When the average particle diameter of the compound having the Me element is in the above range, the spray-dried product and the lithium compound can be uniformly mixed, and the reactivity is improved.

  In the firing raw material mixing step, the addition amount of the lithium compound in the case of adding the compound having the Me element is an atomic conversion molar ratio, and Li / (Ni + Mn + Co + Me) is 0.98 to 1.20, preferably 1.00 The amount is 1.10, particularly preferably 1.01 to 1.05.

The lithium nickel manganese cobalt composite oxide obtained by carrying out the method for producing the lithium nickel manganese cobalt composite oxide of the present invention is preferably the following general formula (1 ′):
_{Li x Ni 1-y-z} -a Mn y Co z Me a O 2 (1 ')
(In the formula (1 ′), Me represents an element having an atomic number of 11 or more other than Ni, Mn, and Co. x is 0.98 ≦ x ≦ 1.2, y is 0 <y ≦ 0.5, and z is (0 <z ≦ 0.5, a represents 0 ≦ a ≦ 0.1, where y + z + a <1.0)
Lithium nickel manganese cobalt composite oxide represented by

  The average particle diameter of the lithium nickel manganese cobalt composite oxide is an average particle diameter determined by a laser diffraction / scattering method, preferably 5 to 30 μm, and particularly preferably 5 to 25 μm. When the average particle diameter of the lithium nickel manganese cobalt composite oxide is in the above range, the particle diameter of the lithium nickel manganese cobalt composite oxide falls within the range of the coating thickness on the electrode, and the coating property, for example, the bending strength of the electrode, etc. Becomes better.

BET specific surface area of the lithium nickel manganese cobalt composite oxide is preferably 0.1~0.7m ² / g, particularly preferably 0.2 to 0.5 m ² / g. When the BET specific surface area of the lithium nickel manganese cobalt composite oxide exceeds the above range, the reaction area is widened, the residual alkali amount is increased, the battery swelling amount is increased, and the safety is likely to be lowered. When the BET specific surface area of the lithium nickel manganese cobalt composite oxide is in the above range, the safety of the battery is increased.

The pressure density of the lithium nickel manganese cobalt composite oxide is preferably 3.0 to 4.0 g / mL, particularly preferably 3.3 to 3.8 g / mL. When the pressure density of the lithium nickel manganese cobalt composite oxide is in the above range, the capacity per volume of the lithium secondary battery is increased. In the present invention, the pressurized density is the density of the sample to be measured in a state where the sample to be measured is put in a molding machine for compression and compressed with a pressure of 3 ton / cm ² .

  The electrode density of the lithium nickel manganese cobalt composite oxide is preferably 2.7 to 3.1 g / mL, particularly preferably 2.8 to 3.1 g / mL. When the electrode density of the lithium nickel manganese cobalt composite oxide is in the above range, the capacity per volume of the lithium secondary battery is increased. In the present invention, the electrode density means that a lithium nickel manganese cobalt composite oxide is applied on a current collector, an actual electrode is produced, the thickness and mass are measured, and the current collector content is calculated from the thickness and mass. It is the density of lithium nickel manganese cobalt composite oxide calculated by subtracting.

  The lithium carbonate remaining in the lithium nickel manganese cobalt composite oxide is preferably 0.20% by mass or less, and particularly preferably 0.19% by mass or less. The lithium hydroxide remaining in the lithium nickel manganese cobalt composite oxide is preferably 0.30% by mass or less, particularly preferably 0.20% by mass or less. When the lithium carbonate and lithium hydroxide remaining in the lithium nickel manganese cobalt composite oxide are in the above range, swelling of the lithium secondary battery can be suppressed, and safety can be improved.

  The lithium nickel manganese cobalt composite oxide obtained by the method for producing a lithium nickel manganese cobalt composite oxide of the present invention is used as a positive electrode active material for a lithium secondary battery.

  And the capacity | capacitance maintenance factor of a lithium secondary battery can be made high by using the lithium nickel manganese cobalt complex oxide obtained by the manufacturing method of the lithium nickel manganese cobalt complex oxide of this invention as a positive electrode active material.

  In addition, the average particle diameter of the spray-dried raw material particles in the slurry to be spray-dried in the spray-drying process, the average particle diameter of the spray-dried product obtained by performing the spray-drying process, and the average of the lithium compound mixed in the firing raw material mixing process The average particle size of the lithium manganese nickel cobalt composite oxide obtained by the particle size and the method for producing the lithium manganese nickel cobalt composite oxide of the present invention is an average particle size determined by a laser diffraction / scattering method, and Microtrack MT3300EXII It is an average particle diameter and particle size distribution measured using a particle size analyzer (the Nikkiso Co., Ltd. make, MTEX-SDU).

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

(Examples 1-5 and Comparative Examples 1-3)
(I) Spray drying step Cobalt oxyhydroxide (average particle size 14.0 μm), manganese carbonate (average particle size 27.3 μm), nickel hydroxide (average particle size 20.3 μm), calcium phosphate (average particle size 7.9 μm) ) And zirconium dioxide (average particle size: 1.1 μm), weighed to the ratio shown in Table 1, and put into a stirring vessel containing pure water to make a slurry with a solid content concentration of 25 mass%. Then, a poise 2100 of a dispersant was charged so as to have a ratio of 5% by mass with respect to the solid content. This mixed slurry was mixed for 1 hour to prepare a slurry having a solid content concentration of 25% by mass.
In the wet pulverization process, 19.3 kg of zirconia balls with a diameter of 0.5 mm are charged using a bead mill, and pulverization is performed while controlling the conditions of pulverization strength (peripheral speed) and the number of passes. A slurry containing was prepared.
The average particle size of the solid content in the slurry was determined by a laser diffraction / scattering method (company name: Nikkiso Co., Ltd., product name: Microtrac MT3300EXII particle size analyzer, model: MTEX-SDU).

  Next, various slurries were supplied to the spray dryer whose inlet temperature was set to the temperature shown in Table 2 at the supply rate shown in Table 2 to obtain a spray-dried product. Table 2 shows various physical properties of the obtained spray-dried product.

Furthermore, only the spray-dried product was ground for 60 seconds at a rotation speed of 20,000 times per minute using a household mixer (MX-X4, manufactured by Matsushita Electric Industrial Co., Ltd.) The maintenance ratio of the average particle diameter was evaluated by the following formula (2).
Maintenance ratio (%) of average particle diameter of spray-dried product before and after pulverization test = (Y1 / X1) × 100 (2)
X1 is the average particle size of the spray-dried product before the pulverization test, and Y1 is the average particle size of the spray-dried product after the pulverization test of the spray-dried product alone.

(B) Firing raw material mixing step This spray-dried product and lithium carbonate (average particle size 6.1 μm) are Li atoms relative to the total atomic moles of Ni, Mn, Co, and Me atoms in the spray-dried product. The molar ratio (Li / (Ni + Mn + Co + Me)) was weighed so as to have the blending ratio shown in Table 3, and using a household mixer (MX-X4, manufactured by Matsushita Electric Industrial Co., Ltd.) as a mixing device, 20,000 times per minute A mixing process was performed at a rotational speed of 60 seconds to obtain a firing raw material mixture. In addition, since the mixing treatment conditions of the spray dried product and the lithium compound in the firing raw material mixing step are the same as the above pulverization test conditions, the maintenance ratio of the average particle size of the spray dried product before and after the mixing treatment in the firing raw material mixing step ( %) Is the same as the maintenance ratio of the average particle diameter of the spray-dried product before and after the grinding test shown in Table 2.

(C) Firing step The calcined raw material mixture obtained above is calcined in a KDF furnace under the temperature, time and air atmosphere shown in Table 3, and after cooling, the calcined product is pulverized and classified to obtain a lithium nickel manganese cobalt composite oxide. A sample was obtained.

(Example 6)
(I) Spray drying step A spray-dried product was obtained in the same manner as in Example 1.

(B) Firing raw material mixing step This spray-dried product, lithium carbonate (average particle size 6.1 μm), and calcium phosphate (average particle size 7.9 μm) were used as the compound having the Me element. As for the compounding amount of lithium carbonate, the molar ratio of Li atom to the total number of moles of Ni atom, Mn atom, Co atom and Me atom in the spray-dried product (Li / (Ni + Mn + Co + Me)) is the compounding ratio shown in Table 4. Weighed as follows. In addition, the compounding amount of calcium phosphate is such that the molar ratio of Me atoms (Me / (Ni + Mn + Co)) to the total number of moles of Ni atoms, Mn atoms, and Co atoms in the spray-dried product is the blending ratio shown in Table 4. Weighed.
These spray-dried products, lithium carbonate and calcium phosphate are mixed for 60 seconds at a rotational speed of 20,000 rotations per minute using a home mixer (MX-X4, manufactured by Matsushita Electric Industrial Co., Ltd.) as a mixing device. A firing raw material mixture was obtained. In the firing raw material mixing step, the maintenance ratio (%) of the average particle size of the spray-dried product before and after the mixing treatment is the same as the maintenance rate of the average particle size of the spray-dried product before and after the grinding test shown in Example 1 of Table 2. became.

(C) Firing step The firing raw material mixture obtained above is fired in a KDF furnace in the atmosphere at the temperature and time shown in Table 4, and after cooling, the fired product is pulverized and classified to obtain lithium nickel manganese cobalt composite oxidation. A physical sample was obtained.

(Example 7)
(I) Spray drying step A spray-dried product was obtained in the same manner as in Example 1.

(B) Firing raw material mixing step A calcining raw material mixture was obtained in the same manner as in Example 6 except that zirconium dioxide (average particle size 1.1 μm) was used as the compound having the Me element. In the firing raw material mixing step, the maintenance ratio (%) of the average particle size of the spray-dried product before and after the mixing treatment is the same as the maintenance rate of the average particle size of the spray-dried product before and after the grinding test shown in Example 1 of Table 2. became.

(C) Firing step The firing raw material mixture obtained above is fired in a KDF furnace in the atmosphere at the temperature and time shown in Table 4, and after cooling, the fired product is pulverized and classified to obtain lithium nickel manganese cobalt composite oxidation. A physical sample was obtained.

<Evaluation of physical properties of lithium nickel manganese cobalt composite oxide>
For the obtained lithium nickel manganese cobalt composite oxide in Examples and Comparative Examples, the average particle diameter, BET specific surface area, pressure compaction degree, electrode density, LiCO ₃ content was determined LiOH content. The results are shown in Table 5.
(Measurement of average particle size)
Average particles of lithium nickel manganese composite oxide (secondary particles) were determined by a laser diffraction / scattering method.
(Measurement of pressure density)
Weighing 3 g of the sample to be measured, putting it in a biaxial molding machine (bottom area: 7.07 cm ² ), and applying a pressure of 3 tons / cm ² for 1 minute using a press machine, The height of the pressed product was measured, and the pressure density of the sample to be measured was calculated from the mass and volume of the sample to be measured (calculated from the area of the bottom surface of the biaxial molding machine and the thickness of the pressed product).
(Measurement of electrode density)
The diameter and thickness of the electrode produced from the sample to be measured are measured. The density of the positive electrode material is calculated from the value obtained by subtracting the thickness and mass of the current collector from here. The positive electrode material is a mixture of 95% by mass of lithium nickel manganese cobalt composite oxide, 2.5% by mass of graphite powder, and 2.5% by mass of polyvinylidene fluoride. 6 ton / cm.

(Measurement of Li ₂ CO ₃ content and LiOH content)
5 g of a sample to be measured and 100 g of pure water were weighed in a beaker and stirred for 5 minutes using a magnetic stirrer. Next, the sample solution after stirring was filtered, and 30 ml of the filtrate was titrated with 0.1 N HCl with an automatic titrator (model COMMITITE-2500) to calculate the Li ₂ CO ₃ content and the LiOH content.

<Battery performance test>
(1) Production of lithium secondary battery 95% by mass of lithium nickel manganese cobalt composite oxide obtained in Examples 1 to 7 and Comparative Examples 1 to 3, 2.5% by mass of graphite powder, 2.5% by mass of polyvinylidene fluoride % Was used as a positive electrode agent, and this was dispersed in N-methyl-2-pyrrolidinone to prepare a kneaded paste. The kneaded paste was applied to an aluminum foil, dried, pressed and punched into a disk with a diameter of 15 mm to obtain a positive electrode plate.
Using this positive electrode plate, a coin-type lithium secondary battery was manufactured using each member such as a separator, a negative electrode, a positive electrode, a current collector plate, a mounting bracket, an external terminal, and an electrolytic solution. Among these, a metal lithium foil was used for the negative electrode, and 1 mol of LiPF ₆ was dissolved in 1 liter of 25:60:15 kneaded solution of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

(2) Evaluation of battery performance The produced lithium secondary battery was operated at room temperature (25 ° C) under the following conditions, and the following battery performance was evaluated.
<Evaluation of cycle characteristics>
The positive electrode is charged to 4.3 V with a current equivalent to a constant current of 0.5 C, switched to constant voltage charging, and after a constant current and constant voltage charging to 4.3 V over 5 hours as a whole, a discharge rate of 0.2 C Charging / discharging was performed at a considerable current to 2.7 V, and these operations were taken as one cycle, and the discharge capacity for each cycle was measured. This cycle was repeated 20 times, and the capacity retention rate was calculated from the following formula (4) from the discharge capacities of the first and 20th cycles. The discharge capacity at the first cycle was defined as the initial discharge capacity. The results are shown in Table 6.
Capacity retention rate (%) = (discharge capacity at 20th cycle / discharge capacity at 1st cycle) × 100 (4)

本発明で得られるリチウムニッケルマンガンコバルト複合酸化物をリチウム二次電池の正極活物質として用いることにより（実施例１〜３）、リチウム二次電池の容量維持率を高くすることができることが分かる。さらに本発明のリチウムニッケルマンガンコバルト複合酸化物にＭｅ元素を含有させたものをリチウム二次電池の正極活物質として用いることにより（実施例４〜７）、容量維持率が更に向上することがわかる。

It turns out that the capacity | capacitance maintenance factor of a lithium secondary battery can be made high by using the lithium nickel manganese cobalt complex oxide obtained by this invention as a positive electrode active material of a lithium secondary battery (Examples 1-3). Furthermore, it can be seen that the capacity retention rate is further improved by using a lithium nickel manganese cobalt composite oxide containing the Me element as a positive electrode active material of a lithium secondary battery (Examples 4 to 7). .

  ADVANTAGE OF THE INVENTION According to this invention, a lithium secondary battery with a high capacity | capacitance maintenance factor of a lithium secondary battery can be manufactured.

Claims (5)

The following general formula (1):
_{Li x Ni 1-y-z} Mn y Co z O 2 (1)
(Wherein x represents 0.98 ≦ x ≦ 1.2, y represents 0 <y ≦ 0.5, and z represents 0 <z ≦ 0.5, where y + z <1.0). A method for producing a lithium nickel manganese cobalt composite oxide represented by:
Spray-drying a slurry containing nickel compound particles, manganese compound particles and cobalt compound particles as the spray-drying raw material particles and having an average particle size of the spray-drying raw material particles of 0.9 to 1.6 μm, The BET specific surface area is 80 to 100 m ² / g , and the following formula (2):
Maintenance ratio (%) of average particle diameter of spray-dried product before and after pulverization test = (Y1 / X1) × 100 (2)
(In Formula (2), X1 shows the average particle diameter of the spray-dried material before a crushing test. Y1 shows the average particle diameter of the spray-dried material after a crushing test.)
A spray-drying step of obtaining a spray-dried product having an average particle size maintenance rate of 75 to 97% before and after the pulverization test of the spray-dried product obtained by
A firing raw material mixing step of mixing the spray-dried product and a lithium compound to obtain a firing raw material mixture;
A firing step of firing the firing raw material mixture to obtain a lithium nickel manganese cobalt composite oxide;
A method for producing a lithium nickel manganese cobalt-based composite oxide, comprising:   2. The method for producing a lithium nitromanganese cobalt composite oxide according to claim 1, wherein a spray drying temperature in the spray drying step is 100 to 400 ° C. 3.   2. The method for producing a lithium nitromanganese cobalt composite oxide according to claim 1, wherein a spray drying temperature in the spray drying step is 200 to 400 ° C. 3.   Further, one or more of the compounds having the Me element, including the Me element selected from the elements having an atomic number of 11 or more other than Ni, Mn, and Co, are used in either the spray drying step or the firing raw material mixing step. It adds to a process or both processes, The manufacturing method of the lithium nickel manganese cobalt complex oxide of any one of Claim 1 thru | or 3 characterized by the above-mentioned.   5. The lithium nickel manganese cobalt composite oxide according to claim 4, wherein the Me element is B, Mg, Ca, Al, Si, P, Ti, Fe, Ga, Zr, Nb, Mo, Sn, W, and Bi. Production method.